WO2024118574A1

WO2024118574A1 - Extreme low volume showerheads with dual distribution spokes and high-density holes

Info

Publication number: WO2024118574A1
Application number: PCT/US2023/081298
Authority: WO
Inventors: Nivin VIKRAMAN; Panya Wongsenakhum; Srinivas Rao Hemanth Rao Kallurkar; Lipyeow Yap
Original assignee: Lam Research Corporation
Priority date: 2022-12-02
Filing date: 2023-11-28
Publication date: 2024-06-06

Abstract

A showerhead for a substrate processing system includes a first plate and a faceplate. The first plate includes a first plurality of gas channels of a first length and a second plurality of gas channels of a second length that is greater than the first length. The first and second plurality of gas channels extend radially from a center of the first plate towards an outer diameter of the first plate in an alternating sequence. The faceplate is coupled to the first plate and includes a plurality of through holes. The faceplate and the first plate define a plenum. The first and second plurality of gas channels and the plurality of through holes are in fluid communication with the plenum.

Description

EXTREME LOW VOLUME SHOWERHEADS WITH DUAL DISTRIBUTION SPOKES AND HIGH-DENSITY HOLES

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of U.S. Provisional Application No. 63/429,660 filed on December 2, 2022. The entire disclosure of the application referenced above is incorporated herein by reference.

FIELD

[0002] The present disclosure relates generally to substrate processing systems and more particularly to extreme low volume showerheads with dual distribution spokes and high-density holes.

BACKGROUND

[0003] The background description provided here is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure.

[0004] Atomic Layer Deposition (ALD) is a thin-film deposition method that sequentially performs a gaseous chemical process to deposit a thin film on a surface of a material (e.g., a surface of a substrate such as a semiconductor wafer). Most ALD reactions use at least two chemicals called precursors (reactants) that react with the surface of the material one precursor at a time in a sequential, self-limiting manner. Through repeated exposure to separate precursors, a thin film is gradually deposited on the surface of the material.

[0005] Thermal ALD (T-ALD) is carried out in a heated processing chamber. The processing chamber is maintained at a sub-atmospheric pressure using a vacuum pump and a controlled flow of an inert gas. The substrate to be coated with an ALD film is placed in the processing chamber and is allowed to equilibrate with the temperature of the processing chamber before starting the ALD process. SUMMARY

[0006] A showerhead for a substrate processing system comprises a first plate and a faceplate. The first plate comprises a first plurality of gas channels of a first length and a second plurality of gas channels of a second length that is greater than the first length. The first and second plurality of gas channels extend radially from a center of the first plate towards an outer diameter of the first plate in an alternating sequence. The faceplate is coupled to the first plate. The faceplate comprises a plurality of through holes. The faceplate and the first plate define a plenum. The first and second plurality of gas channels and the plurality of through holes are in fluid communication with the plenum.

[0007] In additional features, the first plate comprises a circular cavity at the center of the first plate. The first and second plurality of gas channels extend from the circular cavity. The showerhead further comprises a second plate disposed on the first plate. The second plate comprises a conduit extending through the second plate. The conduit comprises an inlet at a top surface of the second plate and a flared outlet at a bottom surface of the second plate. The flared outlet extends radially outwardly towards an outer diameter of the second plate and is aligned with the circular cavity at the center of the first plate.

[0008] In additional features, diameters of the circular cavity and the flared outlet are equal.

[0009] In additional features, a depth of the first and second plurality of gas channels and the circular cavity is less than a thickness of the first plate.

[0010] In additional features, the first plurality of gas channels are separated from each other by a first angle, the second plurality of gas channels are separated from each other by the first angle, and adjacent ones of the first and second plurality of gas channels are separated from each other by a second angle that is less than the first angle.

[0011] In additional features, each of the first plurality of gas channels comprises a first portion, a second portion, and a third portion. The first portion extends radially from the circular cavity. The second portion extends from a distal end of the first portion towards an adjacent one of the second plurality of gas channels. The third portion extends from a distal end of the second portion along a radius of the first plate. The second and third portions are of shorter length than the first portion. The third portion comprises a plurality of holes extending through a bottom surface of the first plate coupled to the faceplate. The plurality of holes is in fluid communication with the plenum.

[0012] In additional features, the first portions of diametrically opposite ones of the first plurality of gas channels lie along a first diameter of the first plate. The third portions and respective ones of the holes in the third portions of the diametrically opposite ones of the first plurality of gas channels lie along a second diameter of the first plate.

[0013] In additional features, the faceplate comprises concentric ridges and radially extending gas passages that intersect and pass through a plurality of the concentric ridges. The third portions of the first plurality of gas channels are aligned with a plurality of the gas passages.

[0014] In additional features, the concentric ridges contact the bottom surface of the first plate.

[0015] In additional features, a height of the concentric ridges is equal to a depth of the plenum.

[0016] In additional features, the plurality of through holes are arranged along concentric circles distributed from a center of the faceplate to an outer diameter of the faceplate, with three of the concentric circles being distributed between successive ones of the concentric ridges. Outlets of the plurality of through holes are conical.

[0017] In additional features, each of the second plurality of gas channels comprises a first portion, a second portion, and a third portion. The first portion extends radially from the circular cavity. The second portion extends from a distal end of the first portion towards an adjacent one of the first plurality of gas channels. The third portion extends from a distal end of the second portion along a radius of the first plate. The second and third portions are of shorter length than the first portion. The third portion comprises a plurality of holes extending through a bottom surface of the first plate coupled to the faceplate. The plurality of holes is in fluid communication with the plenum.

[0018] In additional features, the first portions of diametrically opposite ones of the second plurality of gas channels lie along a first diameter of the first plate. The third portions and respective ones of the holes in the third portions of the diametrically opposite ones of the second plurality of gas channels lie along a second diameter of the first plate. [0019] In additional features, the faceplate comprises concentric ridges and radially extending gas passages that intersect and pass through a plurality of the concentric ridges. The third portions of the second plurality of gas channels are aligned with a plurality of the gas passages.

[0020] In additional features, the concentric ridges contact the bottom surface of the first plate.

[0021] In additional features, a height of the concentric ridges is equal to a depth of the plenum.

[0022] In additional features, the plurality of through holes are arranged along concentric circles distributed from a center of the faceplate to an outer diameter of the faceplate, with three of the concentric circles being distributed between successive ones of the concentric ridges. Outlets of the plurality of through holes are conical.

[0023] In additional features, the second plate comprises an inner cylindrical portion and a sidewall surrounding the inner cylindrical portion and defining an annular channel between the inner cylindrical portion and the sidewall.

[0024] In additional features, outer diameters of the first plate, the faceplate, and the sidewall are equal.

[0025] In additional features, the showerhead further comprises a heater, a third plate, and a cooling plate. The heater is disposed in the annular channel. The third plate is disposed on the inner cylindrical portion. The third plate comprises a material of a different thermal conductivity than the first and second plates and the faceplate. The cooling plate comprises a cooling channel disposed on the third plate.

[0026] In additional features, outer diameters of the third plate and the cooling plate are less than or equal to an inner diameter of the annular channel.

[0027] In additional features, the first plate, the second plate, and the faceplate comprise a metallic material. The material of the third plate comprises a polyimide.

[0028] In additional features, the third plate comprises air pockets.

[0029] In additional features, the first plate comprises a circular cavity and a conduit. The circular cavity is at the center of the first plate. The circular cavity is proximate to a bottom surface of the first plate. The first and second plurality of gas channels extend from the circular cavity along the bottom surface of the first plate. The conduit extends from a top surface of the first plate towards the bottom surface of the first plate through the center of the first plate. The conduit comprises an inlet at the top surface of the first plate and a flared outlet that extends radially outwardly towards an outer diameter of the first plate and that is aligned with the circular cavity.

[0030] In additional features, diameters of the circular cavity and the flared outlet are equal.

[0031] In additional features, a depth of the first and second plurality of gas channels and the circular cavity is less than a thickness of the first plate.

[0032] In additional features, the first plurality of gas channels are separated from each other by a first angle, the second plurality of gas channels are separated from each other by the first angle, and adjacent ones of the first and second plurality of gas channels are separated from each other by a second angle that is less than the first angle.

[0033] In additional features, each of the first plurality of gas channels comprises a first portion, a second portion, and a third portion. The first portion extends radially from the circular cavity. The second portion extends from a distal end of the first portion towards an adjacent one of the second plurality of gas channels. The third portion extends from a distal end of the second portion along a radius of the first plate. The second and third portions are of shorter length than the first portion. The third portion comprises a plurality of holes extending through the bottom surface of the first plate.

[0034] In additional features, the first portions of diametrically opposite ones of the first plurality of gas channels lie along a first diameter of the first plate. The third portions and respective ones of the holes in the third portions of the diametrically opposite ones of the first plurality of gas channels lie along a second diameter of the first plate.

[0035] In additional features, the showerhead further comprises a second plate disposed between the first plate and the faceplate. The second plate comprises a second plurality of through holes that are aligned with the plurality of holes in the first plate.

[0036] In additional features, the first plurality of gas channels and the plurality of holes in the first plate and the second plurality of through holes in the second plate are in fluid communication with the plenum. [0037] In additional features, the faceplate comprises concentric ridges and radially extending gas passages that intersect and pass through a plurality of the concentric ridges. The third portions of the first plurality of gas channels in the first plate and the second plurality of through holes in the second plate are aligned with a plurality of the gas passages.

[0038] In additional features, the concentric ridges contact the bottom surface of the second plate.

[0039] In additional features, a height of the concentric ridges is equal to a depth of the plenum.

[0040] In additional features, the plurality of through holes are arranged along concentric circles distributed from a center of the faceplate to an outer diameter of the faceplate, with three of the concentric circles being distributed between successive ones of the concentric ridges. Outlets of the plurality of through holes are conical.

[0041] In additional features, each of the second plurality of gas channels comprises a first portion, a second portion, and a third portion. The first portion extends radially from the circular cavity. The second portion extends from a distal end of the first portion towards an adjacent one of the first plurality of gas channels. The third portion extends from a distal end of the second portion along a radius of the first plate. The second and third portions are of shorter length than the first portion. The third portion comprises a plurality of holes extending through the bottom surface of the first plate.

[0042] In additional features, the first portions of diametrically opposite ones of the second plurality of gas channels lie along a first diameter of the first plate. The third portions and respective ones of the holes in the third portions of the diametrically opposite ones of the second plurality of gas channels lie along a second diameter of the first plate.

[0043] In additional features, the showerhead further comprises a second plate disposed between the first plate and the faceplate. The second plate comprises a second plurality of holes that are aligned with the plurality of holes in the first plate.

[0044] In additional features, the second plurality of gas channels and the plurality of holes in the first plate and the second plurality of through holes in the second plate are in fluid communication with the plenum. [0045] In additional features, the faceplate comprises concentric ridges and radially extending gas passages that intersect and pass through a plurality of the concentric ridges. The third portions of the second plurality of gas channels in the first plate and the second plurality of holes in the second plate are aligned with a plurality of the gas passages.

[0046] In additional features, the concentric ridges contact the bottom surface of the second plate.

[0047] In additional features, a height of the concentric ridges is equal to a depth of the plenum.

[0048] In additional features, the plurality of through holes are arranged along concentric circles distributed from a center of the faceplate to an outer diameter of the faceplate, with three of the concentric circles being distributed between successive ones of the concentric ridges. Outlets of the plurality of through holes are conical.

[0049] In additional features, the first plate comprises an inner cylindrical portion and a sidewall surrounding the inner cylindrical portion and defining an annular channel between the inner cylindrical portion and the sidewall.

[0050] In additional features, the first and second plurality of gas channels are disposed in the inner cylindrical portion and lie within an inner diameter of the annular channel.

[0051] In additional features, the first and second plurality of gas channels comprise a plurality of holes that extend through the bottom surface of the first plate. The showerhead further comprises a second plate disposed between the first plate and the faceplate. The second plate comprises a second plurality of through holes that are aligned with the plurality of holes in the first plate.

[0052] In additional features, outer diameters of the second plate, the faceplate, and the sidewall are equal.

[0053] In additional features, the showerhead further comprises a heater, a third plate, and a cooling plate. The heater is disposed in the annular channel. The third plate is disposed on the inner cylindrical portion. The third plate comprises a material of a different thermal conductivity than the first and second plates and the faceplate. The cooling plate comprises a cooling channel disposed on the third plate. [0054] In additional features, outer diameters of the third plate and the cooling plate are less than or equal to an inner diameter of the annular channel.

[0055] In additional features, the first plate, the second plate, and the faceplate comprise a metallic material. The material of the third plate comprises a polyimide.

[0056] In additional features, the third plate comprises air pockets.

[0057] In additional features, the second plate further comprises concentric ridges extending from a bottom surface of the second plate and contacting the faceplate. The faceplate comprises radially extending gas passages that intersect and pass through a plurality of the concentric ridges. The third portions of the first plurality of gas channels in the first plate and the second plurality of through holes in the second plate are aligned with a plurality of the gas passages.

[0058] In additional features, a height of the concentric ridges is equal to a depth of the plenum.

[0059] In additional features, the plurality of through holes are arranged along concentric circles distributed from a center of the faceplate to an outer diameter of the faceplate, with three of the concentric circles being distributed between successive ones of the concentric ridges. Outlets of the plurality of through holes are conical.

[0060] In additional features, the second plate further comprises concentric ridges extending from a bottom surface of the second plate and contacting the faceplate. The faceplate comprises radially extending gas passages that intersect and pass through a plurality of the concentric ridges. The third portions of the second plurality of gas channels in the first plate and the second plurality of through holes in the second plate are aligned with a plurality of the gas passages.

[0061] In additional features, a height of the concentric ridges is equal to a depth of the plenum.

[0062] In additional features, the plurality of through holes are arranged along concentric circles distributed from a center of the faceplate to an outer diameter of the faceplate, with three of the concentric circles being distributed between successive ones of the concentric ridges. Outlets of the plurality of through holes are conical.

[0063] In additional features, the first plate comprises an inner cylindrical portion and a sidewall surrounding the inner cylindrical portion and defining an annular channel between the inner cylindrical portion and the sidewall. The first and second plurality of gas channels are disposed in the inner cylindrical portion and lie within an inner diameter of the annular channel. The first and second plurality of gas channels comprise a plurality of holes that extend through the bottom surface of the first plate.

[0064] In additional features, the showerhead further comprises a second plate disposed between the first plate and the faceplate. The second plate comprises a second plurality of through holes that are aligned with the plurality of holes in the first plate and comprises concentric ridges extending from a bottom surface of the second plate and contacting the faceplate.

[0065] In additional features, outer diameters of the second plate, the faceplate, and the sidewall are equal.

[0066] In additional features, the showerhead further comprises a heater, a third plate, and a cooling plate. The heater is disposed in the annular channel. The third plate is disposed on the inner cylindrical portion. The third plate comprises a material of a different thermal conductivity than the first and second plates and the faceplate. The cooling plate comprises a cooling channel disposed on the third plate.

[0067] In additional features, outer diameters of the third plate and the cooling plate are less than or equal to an inner diameter of the annular channel.

[0068] In additional features, the first plate, the second plate, and the faceplate comprise a metallic material. The material of the third plate comprises a polyimide.

[0069] In additional features, the third plate comprises air pockets.

[0070] In additional features, the first plate further comprises concentric ridges extending from a bottom surface of the first plate and contacting the faceplate. The faceplate comprises radially extending gas passages that intersect and pass through a plurality of the concentric ridges. The third portions of the first plurality of gas channels in the first plate and the second plurality of through holes in the second plate are aligned with a plurality of the gas passages.

[0071] In additional features, a height of the concentric ridges is equal to a depth of the plenum.

[0072] In additional features, the plurality of through holes are arranged along concentric circles distributed from a center of the faceplate to an outer diameter of the faceplate, with three of the concentric circles being distributed between successive ones of the concentric ridges. Outlets of the plurality of through holes are conical. [0073] In additional features, the first plate further comprises concentric ridges extending from a bottom surface of the first plate and contacting the faceplate. The faceplate comprises radially extending gas passages that intersect and pass through a plurality of the concentric ridges. The third portions of the second plurality of gas channels in the first plate and the second plurality of through holes in the first plate are aligned with a plurality of the gas passages.

[0074] In additional features, a height of the concentric ridges is equal to a depth of the plenum.

[0075] In additional features, the plurality of through holes are arranged along concentric circles distributed from a center of the faceplate to an outer diameter of the faceplate, with three of the concentric circles being distributed between successive ones of the concentric ridges. Outlets of the plurality of through holes are conical.

[0076] Further areas of applicability of the present disclosure will become apparent from the detailed description, the claims, and the drawings. The detailed description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

[0077] The present disclosure will become more fully understood from the detailed description and the accompanying drawings, wherein:

[0078] FIG. 1 shows an example of a substrate processing system comprising a processing chamber and a showerhead according to the present disclosure;

[0079] FIG. 2 shows a side view of an example of the showerhead comprising a top plate, a middle plate, and a faceplate for use in the processing chamber of FIG. 1 ;

[0080] FIG. 3 shows a cross-sectional view of an example of the top plate of the showerhead of FIG. 2 taken along line A-A shown in FIG. 2 showing a flared gas outlet at the bottom of the top plate;

[0081] FIG. 4 shows a perspective view of an example of the middle plate of the showerhead of FIG. 2 comprising spoke-like gas distribution channels;

[0082] FIG. 5 shows a top view of the middle plate shown in FIG. 4 showing the spoke-like gas distribution channels; [0083] FIG. 6 shows an example of a geometric arrangement of the spoke-like gas distribution channels shown in FIG. 5;

[0084] FIG. 7 shows an example a geometric arrangement of holes disposed in the spoke-like gas distribution channels shown in FIG. 5;

[0085] FIG. 8 shows an example of the alignment of the holes disposed in the spokelike gas distribution channels shown in FIG. 7;

[0086] FIG. 9 shows a bottom view of the middle plate along with the holes shown in FIGS. 7 and 8;

[0087] FIG. 10 shows a top view of the middle plate along with the spoke-like gas distribution channels shown in FIGS. 5-7 and the holes shown in FIGS. 7 and 8;

[0088] FIG. 11 shows a transverse section of the middle plate taken along line B-B shown in FIG. 4;

[0089] FIG. 12 shows a cross-sectional view of the middle plate taken along line C-C shown in FIG. 10;

[0090] FIG. 13 shows a cross-sectional view of the middle plate taken along line D-D shown in FIG. 10;

[0091] FIG. 14 shows a perspective view of an example of the faceplate of the showerhead of FIG. 2;

[0092] FIG. 15 shows a top view of the faceplate shown in FIG. 14 showing concentric ridges, radial gas passages, and through holes;

[0093] FIG. 16 shows an overlay of the holes of the middle plate shown in FIGS. 7 and 8 on the faceplate shown in FIG. 15;

[0094] FIG. 17 shows a cross-sectional view of the faceplate of FIG. 15 taken along line E-E shown in FIG. 15;

[0095] FIG. 18 shows a bottom view of the faceplate shown in FIG. 14;

[0096] FIG. 19 shows the cross-sectional view of the top plate shown in FIG. 3 along with a thermal resistor and a cooling plate disposed on the top plate;

[0097] FIG. 20 shows an example of the thermal resistor shown in FIG. 19;

[0098] FIG. 21 shows a cross-sectional view of an example of the top plate when instead of the middle plate, the top plate comprises the spoke-like gas distribution channels shown in FIG. 7, with the cross-sectional view taken along line C-C shown in FIG. 7;

[0099] FIG. 22 shows a cross-sectional view of the top plate when instead of the middle plate, the top plate comprises the spoke-like gas distribution channels shown in FIG. 7, with the cross-sectional view taken along line D-D shown in FIG. 7;

[0100] FIG. 23 shows a cross-sectional view of an example of the middle plate when instead of the middle plate, the top plate comprises the spoke-like gas distribution channels shown in FIG. 7, with the cross-sectional view taken along lines C-C and D-D shown in FIG. 10;

[0101] FIG. 24 shows a bottom view of an example of the middle plate when instead of the middle plate, the top plate comprises the spoke-like gas distribution channels shown in FIG. 7; the middle plate comprises the holes shown in FIGS. 7-11 ; and instead of the faceplate, the middle plate comprises the ridges shown in FIG. 15 at the bottom of the middle plate;

[0102] FIG. 25 shows a top view of an example of the faceplate when instead of the faceplate, the middle plate comprises the ridges shown in FIG. 15 at the bottom of the middle plate as shown in FIG. 24;

[0103] FIG. 26 shows a cross-sectional view of the faceplate shown in FIG. 25 taken along line H-H shown in FIG. 25;

[0104] FIG. 27 shows a cross-sectional view of the middle plate shown in FIG. 24 taken along lines F-F and G-G shown in FIG. 24;

[0105] FIG. 28 shows a cross-sectional view of an example of the middle plate when instead of the faceplate, the middle plate shown in FIG. 4 additionally comprises the ridges shown in FIG. 15 at the bottom of the middle plate, with the cross-sectional view taken along line C-C shown in FIG. 10;

[0106] FIG. 29 shows a cross-sectional view of the middle plate when instead of the faceplate, the middle plate shown in FIG. 4 additionally comprises the ridges shown in FIG. 15 at the bottom of the middle plate, with the cross-sectional view taken along line D-D shown in FIG. 10; and

[0107] FIG. 30 shows a summary of all the features shown in FIGS. 2-29. [0108] In the drawings, reference numbers may be reused to identify similar and/or identical elements.

DETAILED DESCRIPTION

[0109] In atomic layer deposition (ALD) processes, reduction in chemistry usage is desirable to reduce cost and cycle time (e.g., dose time and purge time) and to increase throughput. Chemistry usage, which is typically measured in terms of amount of chemistry used per ALD cycle (and therefore also called ALD volume), can be reduced by reducing volume of a plenum in a showerhead. The plenum is defined by a bottom surface (substrate-facing or faceplate-facing surface) of a top plate of the showerhead, sidewalls of the showerhead, a plurality of concentrically arranged and segmented vertical walls (called ridges or islands) formed on an upper surface of a faceplate of the showerhead, and passages between the ridges. When the volume of the plenum is reduced (e.g., by varying the height of the ridges), a depth of the plenum varies radially across the showerhead. The variation in the depth of the plenum causes a pressure gradient in process gases flowing through the showerhead in a radial direction across the showerhead. The pressure of the process gases is highest at the center of the showerhead, and decreases as the radius of the showerhead increases, and is lowest at the edge (near an outer diameter or OD) of the showerhead.

[0110] The ALD volume can also be reduced by reducing the showerhead to substrate gap. However, reducing the plenum volume and/or reducing the showerhead to substrate gap causes high velocity jets of process gases to impinge on the substrate surface, which causes deposition of a reflection (or a signature) of a hole-pattern of the showerhead on the substrate. This phenomenon is called flow-jetting, which occurs due to the pressure gradient, and which increases non-uniformity of the material deposited on the substrate.

[0111] The present disclosure solves the flow-jetting problem by providing multiple sets of dual spokes (spoke-like channels) that extend to different radial distances from the center towards the OD of the showerhead, which forms two radial zones (called an inner zone and an outer zone) in the showerhead as follows. A first spoke of the two spokes extends from the center to about half the radius of the showerhead, and a second spoke of the two spokes extends from the center of the showerhead to about 3/4^th of the radius (or near the OD) of the showerhead. Accordingly, the first spoke is shorter than the second spoke. The first and second spokes are trenches or gas channels. The first and second spokes have holes at distal ends (i.e., second ends that are farther from first ends that are proximate to the center of the showerhead) to deliver process gases into the faceplate. A first area of the showerhead from the center of the showerhead to where the first spokes end near the half radius point of the showerhead is called a first zone or the inner zone of the showerhead. The first spokes deliver the process gases to the first zone. A second area (i.e., the remainder) of the showerhead from the center of the showerhead to which the second spokes deliver the process gases is called a second zone or the outer zone of the showerhead.

[0112] Multiple sets of the dual spokes are distributed radially throughout the showerhead, which divides the showerhead into multiple sectors or pie-shaped regions. For example, six sets of the dual spokes may be distributed radially throughout the showerhead, where the first spokes are 60 degrees apart from each other; the second spokes are also 60 degrees apart from each other; and in each set of the dual spokes, the first and second spokes are less than or equal to 15 degrees apart from each other. Any number of dual spokes may be used. Stated generally, the dual spokes are separated from each other by an angle 360/N, where N is the number of dual spokes. The first spokes are 360/N degrees apart from each other; the second spokes are also 360/N degrees apart from each other; and in each set of the dual spokes, the first and second spokes are less than or equal to 360/4N degrees apart from each other. In each of the dual spokes, the first and second spokes extend from the center of the showerhead towards the OD of the showerhead at an acute angle (e.g., less than or equal to 360/4N) between the first and second spokes.

[0113] Each of the dual spokes provides two gas distribution channels via the first and second spokes. In each of the dual spokes, the gas channels provided by the first and second spokes deliver the process gases to the inner zone and to the inner outer zones of each sector, respectively. In other words, the dual spokes provide dual spoke-like gas channels, where the first spoke provides a first spoke-like gas channel (i.e., the first gas channel), and the second spoke provides a second spoke-like gas channel (i.e., the second channel). Accordingly, the dual spokes are also called dual spoke-like gas channels.

[0114] The number and geometry of distribution of the dual spokes can be optimized to divide mass flow of the process gases to feed the process gases equally to the holes at the distal ends of the first and second spokes and to the through holes in the faceplate in the inner and outer zones of the plenum. Thus, the dual spoke design of the showerhead mitigates the radial pressure drop in the plenum while keeping the volume of the plenum low. Additionally, an outlet of the gas supply conduit that supplies process gases to the showerhead at the center of the showerhead to which the inlets of the first and second spokes are connected, is flared radially outwardly like a funnel. The first and second spokes extend radially outwardly from the flared portion of the gas outlet. The flared gas outlet of the showerhead at the entry of the dual spokes near the center of the showerhead prevents formation of a recirculation zone, which further improves a mass distribution balance of the process gases between outer and the inner zone of the plenum.

[0115] Further, the hole density (i.e., the number of through holes) in the faceplate of the showerhead can be increased (e.g., doubled) to reduce the flow jetting due to reduction in mass flow and gas velocity per through hole, which improves the diffusion of the process gases on the substrate surface. The increased hole density is achieved by optimizing width (instead of height) of the separation walls (i.e., the ridges) in the plenum and by including an additional set of through holes (three sets of through holes instead of two sets of through holes) in the azimuthal direction between successive plenum separation walls (ridges). Further, the exit or outlet of the through holes in the faceplate of the showerhead is conical, which further reduces the velocity of the gas jets exiting the through holes and distributes the process gases evenly (uniformly) on the substrate.

[0116] The showerhead is fabricated using a diffusion bonding process of three plates of a metallic material (e.g., an aluminum alloy): a first plate, which is the faceplate; a second plate (middle plate) comprising the spoke-like gas channels formed by extracting material from the second plate; and a third plate (i.e., the top plate) comprising the flared gas outlet that is coupled to the inlets of the spoke-like gas channels in the middle plate. The diffusion bonding process is followed by electroless nickel plating of the entire showerhead.

[0117] In some implementations, the dual spoke-like gas channels can be formed in a bottom region (near the substrate-facing or faceplate-facing surface) of the third plate (the top plate) instead of in the second plate (the middle plate), which only has holes. In some implementations, the dual spoke-like gas channels can be formed in the bottom region (near substrate-facing or faceplate-facing surface) of the third plate (the top plate) instead of in the second plate (the middle plate) and the ridges can be formed on a bottom surface (substrate-facing or faceplate-facing surface) of the second plate (the middle plate) instead of on the upper surface of the faceplate. In some implementations, the dual spoke-like gas channels can be formed in the second plate (the middle plate) and the ridges can be formed on the bottom surface (substrate-facing or faceplate-facing surface) of the second plate (the middle plate) instead of on the upper surface of the faceplate. Additionally, a thermal resistor (heat choke) and a cooling plate are disposed on top of the third plate (the top plate) of the showerhead to control the temperature and axial cooling of the showerhead. These and other features of the present disclosure are described below in detail.

[0118] The present disclosure is organized as follows. An example of a processing chamber in which a showerhead according to the present disclosure can be used is shown and described with reference to FIG. 1. A first showerhead according to the present disclosure comprising a middle plate with the dual spoke-like gas channels is shown and described with reference to FIGS. 2-20. A second showerhead according to the present disclosure comprising a top plate (instead of the middle plate) with the dual spoke-like gas channels and the middle plate with only holes is shown and described with reference to FIGS. 21 -22. A third showerhead according to the present disclosure comprising a top plate (instead of the middle plate) with the dual spoke-like gas channels and the middle plate (instead of the faceplate) with the holes and the ridges is shown and described with reference to FIGS. 24-27. A fourth showerhead according to the present disclosure comprising the middle plate with the dual spoke-like gas channels and the holes and the middle plate (instead of the faceplate) with the ridges is shown and described with reference to FIGS. 28 and 29. FIG. 30 shows a summary of all the features of the top plates, middle plates, and the faceplates of the four showerheads that are shown in FIGS. 2-29.

EXAMPLE OF A SUBSTRATE PROCESSING SYSTEM

[0119] FIG. 1 shows an example of a substrate processing system 100 comprising a processing chamber 102 configured to process a substrate using an atomic layer deposition (ALD) process (e.g., a thermal ALD or T-ALD process). The processing chamber 102 encloses other components of the substrate processing system 100. The processing chamber 102 comprises a substrate support (e.g., a pedestal) 104. During processing, a substrate 106 is arranged on the pedestal 104. [0120] One or more heaters 108 (e.g., a heater array) may be disposed in a ceramic plate arranged on a metallic baseplate of the pedestal 104 to heat the substrate 106 during processing. One or more additional heaters called zone heaters or primary heaters (not shown) may be arranged in the ceramic plate above or below the heaters 108. Additionally, while not shown, a cooling system comprising cooling channels through which a coolant can flow to cool the pedestal 104 may be disposed in the baseplate of the pedestal 104; and one or more temperature sensors may be disposed in the pedestal 104 to sense the temperature of the pedestal 104.

[0121] The processing chamber 102 comprises a gas distribution device 110 such as a showerhead to introduce and distribute process gases into the processing chamber 102. The gas distribution device (hereinafter the showerhead) 110 is described in further detail with reference to subsequent figures. Briefly, the showerhead 110 comprises a stem 112. One end of the stem 112 is connected to a top surface of the processing chamber 102. The showerhead 110 is generally cylindrical and extends radially outwardly from an opposite end of the stem 112 at a location that is spaced from the top surface of the processing chamber 102. A substrate-facing surface of the showerhead 110 comprises a faceplate (shown in subsequent figures). The showerhead 110 further comprises a middle plate (shown and described in detail in subsequent figures) between the top plate and the faceplate. The middle plate comprises spoke-like gas distribution channels to route process gases received from the stem 112 to the faceplate. The faceplate comprises a plurality of outlets or features (e.g., slots or through holes) through which process gases flow into the processing chamber 102.

[0122] The showerhead 110 further comprises a heater, a thermal resistor, and a cooling plate (shown and described with reference to subsequent figures). The thermal resistor (shown and described in detail with reference to FIG. 20) conducts heat from the top plate of the showerhead 110 to the cooling plate. The cooling plate comprises a conduit or a cooling channel (see FIG. 19) through which a coolant can be circulated. Additionally, while not shown, one or more temperature sensors may be disposed in the showerhead 110 to sense the temperature of the showerhead 110.

[0123] The substrate processing system 100 further comprises a gas delivery system 130. The gas delivery system 130 comprises one or more gas sources 132-1 , 132-2, ..., and 132-N (collectively, the gas sources 132), where N is an integer greater than zero. The gas sources 132 may supply process gases, cleaning gases, purge gases, inert gases, etc. The gas sources 132 are connected by valves 134-1 , 134-2, ..., and 134-N (collectively, the valves 134) and mass flow controllers 136-1 , 136-2, ..., and 136-N (collectively, the mass flow controllers 136) to a manifold 139. An output of the manifold 139 is fed to the stem 112 of the showerhead 110. The showerhead 110 receives one or more gases from the gas delivery system 130 through the stem 112 and supplies the one or more gases to the processing chamber 102.

[0124] The substrate processing system 100 further comprises a fluid delivery system 140. The fluid delivery system 140 supplies a coolant to the cooling system in the pedestal 104 and to the cooling plate in the showerhead 110. A temperature controller 150 may be connected to the heaters 108, the zone heaters, the cooling system, and the temperature sensors in the pedestal 104. The temperature controller 150 may also be connected to the heaters, the cooling plate, and the temperature sensors in the showerhead 110. The temperature controller 150 may control power supplied to the heaters 108, the zone heaters, and coolant flow through the cooling system in the pedestal 104 to control the temperature of the pedestal 104 and the substrate 106. The temperature controller 150 may also control power supplied to the heater disposed in the showerhead 110 and coolant flow through the conduit disposed in the cooling plate of the showerhead 110 to control the temperature of the showerhead 110.

[0125] A vacuum pump 158 maintains sub-atmospheric pressure inside the processing chamber 102 during substrate processing. A valve 156 is connected to an exhaust port of the processing chamber 102. The valve 156 and the vacuum pump 158 are used to control pressure in the processing chamber 102 and to evacuate reactants from the processing chamber 102 via the valve 156. A system controller 160 controls the components of the substrate processing system 100 described above.

FIRST EXAMPLE OF SHOWERHEAD

[0126] FIG. 2 schematically shows a side view of a first example of a showerhead (a first showerhead) 200 according of the present disclosure. The first showerhead 200 can be used as the showerhead 110 in the substrate processing system 100 shown in FIG. 1 . The first showerhead 200 comprises a top plate (also called a backplate) 202, a middle plate 204, and a faceplate 206. The top plate 202, the middle plate 204, and the faceplate 206 can be made of a metallic material. The top plate 202, the middle plate 204, and the faceplate 206 can be stacked on top of each other as shown. The top plate 202, the middle plate 204, and the faceplate 206 can be diffusion bonded to each other.

[0127] Internal structures of the top plate 202, the middle plate 204, and the faceplate 206 are shown and described below in detail with reference to FIGS. 3-20. Thereafter, variations in the internal structures of the top plate 202, the middle plate 204, and the faceplate 206 are shown and described with reference to FIGS. 21 -29. The variations in the internal structures of the top plate 202, the middle plate 204, and the faceplate 206 yield different showerheads. The different showerheads are described as second, third, and fourth showerheads with reference to FIGS. 21 -29. The different showerheads (i.e., the second, third, and fourth showerheads) are structurally different than the first showerhead 200 but are functionally identical to the first showerhead 200. In general, regardless of the variations, in each of the first through the fourth showerheads, the faceplate 206 and at least one of the top plate 202 and the middle plate 204 define a plenum 259 in the showerheads as shown and described with reference to subsequent figures. In the description of the second, third, and fourth showerheads, references are made to the structures (e.g., views) of the first showerhead 200 shown in FIGS. 2-20 to avoid repetitions of drawings and description for brevity.

EXAMPLE OF TOP PLATE

[0128] FIG. 3 shows a cross-sectional view of an example of the top plate 202 of the first showerhead 200 shown in FIG. 2 taken along line A-A shown in FIG. 2. The top plate 202 is made of a metallic material. The top plate 202 is generally cylindrical. The top plate 202 is solid (i.e., not hollow) except for the features described below. The top plate 202 comprises an inner cylindrical portion 210 and a sidewall 212 that surrounds the inner cylindrical portion 210. The sidewall 212 has an outer diameter (OD) and an inner diameter (ID). An OD of the inner cylindrical portion 210 is less than the ID of the sidewall 212. An annular channel 214 is formed between the ID of the sidewall 212 and the OD of the inner cylindrical portion 210. One or more heater elements (not shown) are disposed circumferentially in the annular channel 214.

[0129] The inner cylindrical portion 210 comprises a top surface 215 and a bottom surface 218. The top surface 215 and the bottom surface 218 are parallel to each other and perpendicular to a vertical axis of the first showerhead 200. The bottom surface 218 faces the substrate 106 and the pedestal 104 (shown in FIG. 1 ). An OD of the top surface 215 is equal to the OD of the inner cylindrical portion 210. An OD of the bottom surface 218 is equal to the OD of the sidewall 212. The sidewall 212 extends vertically upwards from the OD of the bottom surface 218, extends parallel to the vertical axis of the first showerhead 200 and perpendicularly to the top and bottom surfaces 215, 218 above the top surface 215, and then extends radially outwards parallel to the top and bottom surfaces 215, 218 to form a flange 216. An OD of the flange 216 is greater than the OD of the sidewall 212. The flange 216 is attached to the sidewall of the processing chamber 102 shown in FIG. 1 .

[0130] The top plate 202 (specifically, the inner cylindrical portion 210 of the top plate 202) comprises a conduit 220. For example, the conduit 220 can be bored through the center of the inner cylindrical portion 210. The conduit 220 extends vertically downwardly from the top surface 215 of the inner cylindrical portion 210 to the bottom surface 218 of the inner cylindrical portion 210. The conduit 220 extends perpendicularly to the top and the bottom surfaces 215, 218. The conduit 220 is parallel to the vertical axis of the first showerhead 200. A first end 222 of the conduit 220 at the top surface 215 is connected to the stem 112 (shown in FIG. 1 ). The first end 222 receives a process gas from the stem 112. Near the bottom surface 218, a second end of the conduit 220 extends downwardly and flares (i.e., extends downwardly and radially outwardly in a curved manner like a funnel) to form a flared gas outlet 224 at the bottom surface 218 (i.e., at the bottom of the top plate 202). The flared gas outlet 224 provides advantages that are described below in the description of the middle plate 204 in further detail. In some examples, the flared gas outlet 224 can be conical.

EXAMPLE OF MIDDLE PLATE

[0131] FIG. 4 shows a perspective view of an example of the middle plate 204 of the first showerhead 200 of FIG. 2. The middle plate 204 is shaped as a flat cylinder. The middle plate 204 is also made of a metallic material. The middle plate 204 is also solid (i.e., not hollow) except for the features described below. An OD of the middle plate 204 is equal to the OD of the sidewall 212 of the top plate 202. The middle plate 204 comprises a plurality of spoke-like gas distribution channels (hereinafter called the gas channels). For example, the middle plate 204 comprises first gas channels 250-1 , 250- 2, ..., 250-6 (collectively the first gas channels 250) and second gas channels 252-1 , 252-2, ..., 252-6 (collectively the second gas channels 252). While only six of each of the first and second gas channels 250, 252 are shown for example, the middle plate 204 can comprise any number of the first and second gas channels 250, 252. Regardless of the number of the first and second gas channels 250, 252, the number of the first gas channels 250 is equal to the number of the second gas channels 252. The first gas channel 250-1 and the second gas channel 252-1 that is adjacent to the first gas channel 250-1 are collectively called a first dual gas channel; the first gas channel 250-2 and the second gas channel 252-2 that is adjacent to the first gas channel 250-2 are collectively called a second dual gas channel; and so on.

[0132] The first and second gas channels 250, 252 are formed by removing material from the middle plate 204 as follows. For example, the middle plate 204 has a thickness (height) H. The first and second gas channels 250, 252 are formed by removing material from a top surface (i.e., a surface facing the top plate 202) 256 of the middle plate 204 up to a depth X that is less than H (e.g., up to a depth of X = H/4, H/3, H/2, 3H/4, or any fraction of H). Each of the first and second gas channels 250, 252 has the same depth X<H.

[0133] Additionally, a circular cavity 254 is formed on the top surface 256 at the center of the middle plate 204 by removing material from the top surface 256 up to the depth X. Each of the first gas channels 250 and each of the second gas channels 252 extend radially outwardly from a circumference of the circular cavity 254 towards the OD of the middle plate 204 as described below in further detail. The circular cavity 254 of the middle plate 204 and the flared gas outlet 224 of the top plate 202 have the same circumference (i.e., diameter). When the middle plate 204 is bonded to the top plate 202 (i.e., when the top surface 256 of the middle plate 204 is bonded to the bottom surface 218 of the top plate 202), the circular cavity 254 of the middle plate 204 mates (i.e., aligns) with the flared gas outlet 224 of the top plate 202. Additional structural details of the first and second gas channels 250, 252 are described below.

EXAMPLES OF SPOKE-LIKE GAS CHANNELS

[0134] FIG. 5 shows a top view of the middle plate 204 showing the spoke-like first and second gas channels 250, 250. Each of the first gas channels 250 extends radially outwardly from the circumference of the circular cavity 254 towards the OD of the middle plate 204 up to a first radial distance R1 . For example, R1 may be equal to half the radius of the middle plate 204. In some examples, R1 may be less than half the radius of the middle plate 204. In other examples, R1 may be greater than half the radius of the middle plate 204. In any of these designs, each of the first gas channels 250 is of the same length. That is, the first gas channels 250 are of equal length (e.g., a first length).

[0135] Each of the second gas channels 252 also extends radially outwardly from the circumference of the circular cavity 254 towards the OD of the middle plate 204 up to a second radial distance R2, where R2>R1 . For example, R2 may be equal to 3/4^th of the radius of the middle plate 204. In some examples, R2 may be less than 3/4^th of the radius of the middle plate 204 but greater than R1. In other examples, R2 may be greater than 3/4^th of the radius of the middle plate 204. In any of these designs, each of the second gas channels 252 is of the same length. That is, the second gas channels 252 are of equal length (e.g., a second length). Since R2>R1 , the second length (R2) of the second gas channels 252 is greater than the first length (R1 ) of the first gas channels 250.

[0136] The first and second gas channels 250, 252 of the first and second lengths, respectively, are arranged on the middle plate 204 radially (in the form of spokes of a wheel) in an alternating sequence as follows: the first gas channel 250-1 , the second gas channel 252-1 , the first gas channel 250-2, the second gas channel 252-2, the first gas channel 250-3, the second gas channel 252-3, and so on. Due to the spoke-like alternating arrangement and different lengths, the first and second gas channels 250, 252 supply process gases to inner and outer radial zones of the first showerhead 200 as described below in detail. Due to the spoke-like alternating arrangement and other structural features of the first and second gas channels 250, 252, the first showerhead 200 supplies the process gases evenly and uniformly without flow jetting into the processing chamber 102 (shown in FIG. 1 ). The first and second gas channels 250, 252 are now described in further detail.

[0137] In each of the dual gas channels, the first gas channel 250 comprises three portions: a first portion 260, a second portion 262, and a third portion 264 (shown only for some of the first gas channels 250 for clarity and to avoid cluttering the figure). The first portion 260 extends from the circumference of the circular cavity 254 radially up to a distance less than R1 . The second portion 262 extends from a distal end of the first portion 260, curves towards the second gas channel 252, and extends towards the second gas channel 252 for a first distance. The distal end of the first portion 160 is a second end of the first portion 160 with a first end of the first portion 160 being proximate to the circumference of the circular cavity 254. After the first distance, the second portion 262 connects to and terminates into a center of the third portion 264. The third portion 264 extends along a radius of the middle plate 204. A length of the third portion 264 is less than a length of the first portion 260 and greater than a length of the second portion 262. The second and third portions 262, 264 form a shape of the letter “T.” A first end of the third portion 264 extends towards the center of the middle plate 204. A second end of the third portion 264 extends towards the OD of the middle plate 204 and lies on the circle of radius R1 .

[0138] In each of the dual gas channels, the second gas channel 252 also comprises three portions: a first portion 270, a second portion 272, and a third portion 274 (shown only for some of the second gas channels 252 for clarity and to avoid cluttering the figure). The first portion 270 extends from the circumference of the circular cavity 254 radially up to a distance less than R2. The second portion 272 extends from a distal end of the first portion 270, curves towards the first gas channel 250, and extends towards the first gas channel 250 for a second distance. The distal end of the first portion 270 is a second end of the first portion 270 with a first end of the first portion 270 being proximate to the circumference of the circular cavity 254. After the second distance, the second portion 272 connects to and terminates into a center of the third portion 274. The third portion 274 extends along a radius of the middle plate 204. A length of the third portion 274 is less than a length of the first portion 270 and greater than a length of the second portion 272. The second and third portions 272, 274 also form a shape of the letter “T.” A first end of the third portion 274 extends towards the center of the middle plate 204. A second end of the third portion 274 extends towards the OD of the middle plate 204 and lies on the circle of radius R2. The lengths of the third portions 264, 274 of the first and second gas channels 250, 252 are equal.

[0139] FIG. 6 shows an example of the geometric arrangement of the spoke-like first and second gas channels 250, 252 shown in FIGS. 4 and 5. In general, if the number of each of the first gas channels 250 and the second gas channels 252 is N, the middle plate 204 comprises N dual gas channels (defined above). The first gas channels 250 are 360/N degrees apart from each other. The second gas channels 252 are also 360/N degrees apart from each other. In each dual gas channel, the first and second gas channels 250, 252 are less than or equal to 360/4N degrees apart from each other. In each of the dual gas channels, the first and second gas channels 250, 252 extend from the circumference of the circular cavity 254 towards the OD of the showerhead at an acute angle (e.g., less than or equal to 360/4N) between the first and second gas channels 250, 252. In general, the first and second gas channels 250, 252 have an appearance of spokes of a wheel.

[0140] The first portions 260 of diametrically opposite first gas channels 250 are radially aligned (i.e., lie along the same diameter of the middle plate 204). The first portions 270 of diametrically opposite second gas channels 252 are also radially aligned (i.e., lie along the same diameter of the middle plate 204). For example, the first portion 260 of the first gas channel 250-1 is radially aligned (i.e., lie along the same diameter of the middle plate 204) with the first portion 260 of the first gas channel 250-4 that is diametrically opposite to the first gas channel 250-1 ; and so on. For example, the first portion 270 of the second gas channel 252-1 is radially aligned (i.e., lie along the same diameter of the middle plate 204) with the first portion 270 of the first second channel 252-4 that is diametrically opposite to the second gas channel 252-1 ; and so on.

[0141] The third portions 264 of diametrically opposite first gas channels 250 are radially aligned (i.e., lie along the same diameter of the middle plate 204). The third portions 274 of diametrically opposite second gas channels 252 are also radially aligned (i.e., lie along the same diameter of the middle plate 204). For example, the third portion 264 of the first gas channel 250-1 is radially aligned (i.e., lie along the same diameter of the middle plate 204) with the third portion 264 of the first gas channel 250-4 that is diametrically opposite to the first gas channel 250-1 ; and so on as shown by dotted lines. For example, the third portion 274 of the second gas channel 252-1 is radially aligned (i.e., lie along the same diameter of the middle plate 204) with the third portion 274 of the first second channel 252-4 that is diametrically opposite to the second gas channel 252-1 ; and so on as shown by dotted lines.

[0142] Dotted lines showing similar diametric alignment (i.e., diametrically symmetric arrangement) of the first portions 260, 270 of the first and second gas channels 250, 252 described above are omitted to not clutter the figure. Examples of the omitted dotted lines showing the diametric alignment of the first portions 260, 270 of the first and second gas channels 250, 252 are shown as lines C-C and D-D in FIG. 7.

[0143] FIG. 7 shows an example of the geometric arrangement of holes disposed in the spoke-like first and second gas channels 250, 252 shown in FIGS. 4-6. Reference numerals for the portions 260, 262, 270, 272 of the first and second gas channels 250, 252 are omitted for clarity and to not clutter the figure. Each of the third portions 264, 274 of the first and second gas channels 250, 252 comprise at least two holes. For example, the third portion 264 of the first gas channel 250 comprises a first hole 280 at the first end of the third portion 264 and a second hole 282 at the second end of the third portion 264. The holes 280, 282 are identified only for some of the first gas channels 250 for clarity and to avoid cluttering the figure. The first and second holes 280, 282 of the third portion 264 lie on a radius of the middle plate 204.

[0144] The third portion 274 of the second gas channel 252 comprises a first hole 284 at the first end of the third portion 274 and a second hole 286 at the second end of the third portion 274. The holes 284, 286 are identified only for some of the second gas channels 252 for clarity and to avoid cluttering the figure. The first and second holes 284, 286 of the third portion 274 lie on a radius of the middle plate 204. The holes 280, 282, 284, 286 are drilled in the third portions 264, 274 through a bottom surface 257 of the middle plate 204 (shown in FIG. 9). The depth (height) of each of the holes 280, 282, 284, 286 is equal to (H-X), where H is the thickness (height) of the middle plate 204, and X is the depth of the first and second gas channels 250, 252.

[0145] Accordingly, the holes 280, 282 in each third portion 264 of each of the first gas channels 250 are radially aligned (i.e., lie along the same radius of the middle plate 204). The holes 284, 286 in each third portion 274 of each of the second gas channels 252 are also radially aligned (i.e., lie along the same radius of the middle plate 204). For example, the holes 280, 282 in the third portion 264 of the first gas channel 250-1 are radially aligned (i.e., lie along the same radius of the middle plate 204); and so on as shown by dotted lines in FIG. 8. For example, the holes 284, 286 in the third portion 274 of the second gas channel 252-1 are radially aligned (i.e., lie along the same radius of the middle plate 204); and so on as shown by dotted lines in FIG. 8.

[0146] Further, the holes 280, 282 of diametrically opposite first gas channels 250 are radially aligned (i.e., lie along the same diameter of the middle plate 204). The holes 284, 286 of diametrically opposite second gas channels 252 are also radially aligned (i.e., lie along the same diameter of the middle plate 204). For example, the holes 280, 282 of the first gas channel 250-1 are radially aligned (i.e., lie along the same diameter of the middle plate 204) with the holes 280, 282 of the first gas channel 250-4 that is diametrically opposite to the first gas channel 250-1 ; and so on as shown by dotted lines in FIG. 8. For example, the holes 284, 286 of the second gas channel 252-1 are radially aligned (i.e., lie along the same diameter of the middle plate 204) with the holes 284, 286 of the first second channel 252-4 that is diametrically opposite to the second gas channel 252-1 ; and so on as shown by dotted lines in FIG. 8.

[0147] FIG. 8 shows an example of the alignment of the holes disposed in the spokelike first and second gas channels 250, 252 shown in FIG. 7. The holes 282 of the third portions 264 of the first gas channels 250 lie on the circle of radius R1 . The holes 286 of the third portions 274 of the second gas channels 252 lie on the circle of radius R2. The holes 280 of the third portions 264 of the first gas channels 250 lie on a circle of radius R3 that is less than R1 . The holes 284 of the third portions 274 of the second gas channels 252 lie on a circle of radius R4 that is less than R2 and greater than R1 .

[0148] FIG. 9 shows a bottom view of the middle plate 204 along with the holes 280, 282, 284, 286 shown in FIGS. 7 and 8. The circles on which the holes 280, 282, 284, 286 lie, which are shown in FIG. 8, are omitted to clearly show the holes 280, 282, 284, 286. Further, only some of the holes 280, 282, 284, 286 are identified for clarity and to avoid cluttering the figure.

[0149] FIG. 10 shows a top view of the middle plate 204 along with the spoke-like first and second gas channels 250, 252 and the circular cavity 254 shown in FIGS. 4-7 and the holes 280, 282, 284, 286 shown in FIGS. 7-9. The circles on which the first and second gas channels 250, 252 and the holes 280, 282, 284, 286 lie, which are shown in FIGS. 5, 7, and 8 are omitted for clarity. Reference numerals for the portions 260, 262, 264, 270, 272, 274 of the first and second gas channels 250, 252 are also omitted for clarity. Further, only some of the holes 280, 282, 284, 286 are identified for clarity and to avoid cluttering the figure. Other elements that are shown and that are already described above are not described again for brevity.

[0150] FIG. 11 shows a transverse section of the middle plate 204 taken along line B- B shown in FIG. 4. The transverse section shows the spoke-like first and second gas channels 250, 252 and the circular cavity 254 shown in FIGS. 4-7 and 10 and the holes 280, 282, 284, 286 shown in FIGS. 7-10. The circles on which the first and second gas channels 250, 252 and the holes 280, 282, 284, 286 lie, which are shown in FIGS. 5, 7, and 8 are omitted for clarity. Reference numerals for the portions 260, 262, 264, 270, 272, 274 of the first and second gas channels 250, 252 are also omitted for clarity. Further, only some of the holes 280, 282, 284, 286 are identified for clarity and to avoid cluttering the figure. Other elements that are shown and that are already described above are not described again for brevity. [0151] FIG. 12 shows a cross-sectional view of the middle plate 204 taken along line C-C shown in FIG. 10. The spoke-like second gas channels 252-2, 252-5 are visible in the cross-sectional view shown.

[0152] FIG. 13 shows a cross-sectional view of the middle plate 204 taken along line D-D shown in FIG. 10. The spoke-like first gas channels 252-3, 252-6 are visible in the cross-sectional view shown.

EXAMPLE OF FACEPLATE

[0153] FIG. 14 shows a perspective view of an example of the faceplate 206 of the first showerhead 200 of FIG. 2. The faceplate 206 is also made of a metallic material and is also cylindrical. An OD of the faceplate 206 is equal to the OD of the middle plate 204 and the OD of the sidewall 212 of the top plate 202. The faceplate 206 comprises a plurality of concentric ridges 290-1 , 290-2, ..., and 290-11 (collectively the ridges 290) on a top surface (i.e., the surface facing the middle plate 204) 207 of the faceplate 206. While only eleven ridges 290 are shown for example, the faceplate 206 can comprise any number of ridges 290. The ridges 290 are vertical walls formed on the top surface 207 of the faceplate 206. For example, the ridges 290 are formed by removing material from the top surface 207 of the faceplate 206 up to a depth d (shown in FIG. 17). Accordingly, the ridges 290 have a height d (shown in FIG. 17). The ridges 290 are arranged concentrically on the top surface 207 from the center of the faceplate 206 to an OD of the top surface 207 of the faceplate 206.

[0154] The ridges 290 divide the top surface 207 of the faceplate 206 to form a plurality of circular and concentric gas passages on the top surface 207 of the faceplate 206. Examples of the circular and concentric gas passages are shown at 291 -1 , 291 -2, 291 -3, and so on (collectively the gas passages 291 ). The gas passages 291 lie between the ridges 290. The gas passages 291 are distributed throughout the top surface 207 of the faceplate 206. The gas passages 291 are distributed from the center of the top surface 207 to the OD of the top surface 207 of the faceplate 206.

[0155] The ridges 290 are segmented (i.e., each of the ridges 290 is circumferentially discontinuous) as follows. The faceplate 206 comprises a plurality of radial gas passages on the top surface 207 of the faceplate 206. Examples of the radial gas passages are shown at 292-1 , 292-2, 292-3, 292-4 (collectively the gas passages 292). The gas passages 292 extend radially throughout the top surface 207 of the faceplate 206. The gas passages 292 radially intersect the gas passages 291. The gas passages 292 radially intersect the concentric ridges 290 and segment the ridges 290. The gas passages 292 divide the ridges 290 into arc-shaped segments. The ridges 290, the gas passages 291 , 292, the bottom surface 257 of the middle plate, the top surface 207 of the faceplate 206, and a sidewall 205 of the faceplate 206 define the plenum 259 of the first showerhead 200. The plenum 259 extends radially across the faceplate 206 and has a depth (height) d (shown in FIG. 17). The ridges 290 and the gas passages 292 are arranged in a pattern that is consistent with a pattern in which the spoke-like first and second gas channels 250, 252 and the holes 280, 282, 284, 286 are arranged in the middle plate 204 as described below in detail.

[0156] The faceplate 206 further comprises a plurality of through holes 294. The through holes 294 are shown by dotted circles in FIGS. 14, 15, and 18. The through holes 294 are arranged in concentric circles between the ridges 290. The through holes 294 are drilled through the top surface 207 and a bottom surface 209 (shown in FIGS. 17 and 18) of the faceplate 206. The through holes 294 are distributed radially from the center of the faceplate 206 to the OD of the faceplate 206. The through holes 294 are in fluid communication with the plenum 259. The through holes 294 are shown and described in further detail below with reference to subsequent figures.

[0157] FIG. 15 shows a top view of the faceplate 206 shown in FIG. 14 showing the ridges 290, the gas passages 291 , 292, and the through holes 294. The ridges 290 and the gas passages 292 are arranged in a pattern that is consistent with a pattern in which the spoke-like first and second gas channels 250, 252 and the holes 280, 282, 284, 286 are arranged in the middle plate 204 as follows. Specifically, the ridges 290 and the gas passages 292 are arranged such that the holes 280, 282, 284, 286 of the spoke-like first and second gas channels 250, 252 lie between the segments of the some of the ridges 290 and are coincident with some of the gas passages 292 when the top surface 207 of the faceplate 206 is bonded to the bottom surface 257 of the middle plate 204. A view of an overlay (i.e., a layout) of the holes 280, 282, 284, 286 of the spoke-like first and second gas channels 250, 252 relative to the segments of the ridges 290 and the gas passages 292 when the top surface 207 of the faceplate 206 is bonded to the bottom surface 257 of the middle plate 204 is shown in FIG. 16.

[0158] The gas passages 292 are of three types, which are identified as 292-1 , 292-3, and 292-3. The first gas passage 292-1 is the shortest of the three gas passages 292- 1 , 292-3, and 292-3. The first gas passage 292-1 extends radially from about half the radius of the faceplate 206 to the OD of the faceplate 206. The second gas passage 292-2 is the longest of the three gas passages 292-1 , 292-3, and 292-3. The second gas passage 292-2 extends radially from the ID of the faceplate 206 to the OD of the faceplate 206 except that one of the ridges 290 intersects and blocks the second gas passage 292-2. Thus, the second gas passage 292-2 is segmented (i.e., is radially discontinuous due to the presence of one of the ridges 290 that intersects the second gas passage 292-2). The third gas passage 292-3 has a length greater than the first gas passage 292-1 and less than the second gas passage 292-2. The third gas passage 292-3 extends radially from less than half the radius of the faceplate 206 to the OD of the faceplate 206. Specifically, the third gas passage 292-3 extends radially from the one of the ridges 290 that intersects the second gas passage 292-2 to the OD of the faceplate 206.

[0159] A fourth gas passage 292-4 lies between the second gas passage 292-2 and the third gas passage 292-3. The fourth gas passage 292-4 is identical to the first gas passage 292-1. That is, the fourth gas passage 292-4 also extends radially from about half the radius of the faceplate 206 to the OD of the faceplate 206 and is of the same length as the first gas passage 292-1. The gas passages 292 are arranged in the following sequence that is repeated throughout the faceplate 206: 292-1 , 292-2, 292-4, 292-3; 292-1 , 292-2, 292-4, 292-3; and so on. The first, third, and fourth gas passages 292-1 , 292-3, 292-4 are not segmented (i.e., are radially continuous and are not blocked by an intersecting ridge 290).

[0160] FIG. 16 shows the overlay of the holes 280, 282, 284, 286 of the spoke-like first and second gas channels 250, 252 in the middle plate 204 shown in FIGS. 4 and 7-10 on the faceplate 206 shown in FIGS. 14 and 15 when the top surface 207 of the faceplate 206 is bonded to the bottom surface 257 of the middle plate 204. The holes 284, 286 of the spoke-like second gas channels 252 lie along (i.e., are coincident with) the first gas passage 292-1 . The 280, 282, of the spoke-like first gas channels 250 lie along (i.e., are coincident with) the second gas passage 292-2. The through holes 294 of the faceplate 206 are omitted for clarity and to avoid cluttering of the figure.

[0161] When the top plate 202, the middle plate 204, and the faceplate 206 are bonded together as described above, the following elements of the first showerhead 200 are in fluid communication with each other: the conduit 220; the flared gas outlet 224; the first and second gas channels 250, 252; the through holes 280, 282, 284, 286; the plenum 259; and the through holes 294. When the process is supplied to the first showerhead 200 through the stem 112 (shown in FIG. 1 ), the process gas flows through the conduit 220 (shown in FIG. 3) in the top plate 202. The process gas flows through the conduit 220 through the flared gas outlet 224 of the top plate 202 (shown in FIG. 3). The process gas flows through the flared gas outlet 224 into the spoke-like first and second gas channels 250, 252 in the middle plate 204 (shown in FIGS. 4-7, 10, and 11 ). The process gas flows through the spoke-like first and second gas channels 250, 252 through the holes 280, 282, 284, 286 in the middle plate 204 (shown in FIGS. 4 and 7-10). The process gas flows through the holes 280, 282, 284, 286 in the middle plate 204 into the faceplate 206. The process gas flows through the holes 280, 282, 284, 286 in the middle plate 204 into the plenum 259 in the faceplate 206. The process gas flows through the gas passages 291 , 292 of the plenum 259 in the faceplate 206 and via the through holes 294 of the faceplate 206 into the processing chamber 102 and onto the substrate 106 (both shown in FIG. 1 ).

[0162] Due to the overlay of the holes 280, 282, 284, 286 of the spoke-like first and second gas channels 250, 252 relative to the ridges 290 and the gas passages 292 in the faceplate 206 described above, the process gas is distributed evenly (uniformly) without radial pressure gradient via all of the through holes 294 in the faceplate 206. Specifically, the process gas is distributed to the through holes 294 in the faceplate 206 in the inner zone of the first showerhead 200 via the holes 280, 282 of the first gas channels 250 and the ridges 290 and portions of the gas passages 291 , 292 that lie in the inner zone of the first showerhead 200. The inner zone of the first showerhead 200 comprises the holes 280, 282 of the first gas channels 250 and the ridges 290 and the portions of the gas passages 291 , 292 that lie within a circle of radius R1 . The process gas is distributed to the through holes 294 in the faceplate 206 in the outer zone of the first showerhead 200 via the holes 284, 286 of the second gas channels 252 and the ridges 290 and portions of the gas passages 291 , 292 in the outer zone of the first showerhead 200. The outer zone of the first showerhead 200 comprises the holes 284, 286 of the second gas channels 252 and the ridges 290 and the portions of the gas passages 291 , 292 that lie outside the circle of radius R1 (i.e., in the remainder area of the faceplate 206 from R1 to R2 or the OD of the faceplate 206).

[0163] FIG. 17 shows a cross-sectional view of the faceplate 206 shown in FIGS. 14 and 15 taken along line E-E shown in FIG. 15. The second passages 292-2 and one of the ridges 290 that intersects (blocks) the second passages 292-2 is visible in the cross-sectional view shown. The structure of the through holes 294 is shown in further detail. Specifically, the through holes 294 are cylindrical and extend vertically along the axis of the first showerhead 200 from the top surface 207 of the faceplate 206 to a bottom surface 209 of the faceplate 206. First ends or inlets of the through holes 294 at the bottom surface 209 of the faceplate 206 are cylindrical. Distal (or second) ends or outlets of the through holes 294 at the bottom surface 209 of the faceplate 206 are conical. Thus, each of the through holes 294 comprises a cylindrical portion and a conical portion. Each of the through holes 294 has a height equal to a thickness of the faceplate 206 minus the depth d of the plenum 259. The conical shape of the distal ends of the through holes 294 reduces the velocity of the gas jets exiting the through holes 294 and distributes the process gases evenly (uniformly) on the substrate 106.

[0164] FIG. 18 shows a bottom view of the faceplate 206 shown in FIGS. 14-17. The hole density (i.e., the number of through holes 294) in the faceplate 206 of the first showerhead 200 is increased (e.g., doubled) to reduce the flow jetting due to reduction in mass flow and gas velocity per through hole 294, which improves the diffusion of the process gases on the surface of the substrate 106. The increased hole density is achieved by optimizing width (instead of height) of the ridges 290 (shown in FIGS. 14- 16) and by including an additional set of through holes 294 (e.g., three sets of through holes 294 instead of two sets of through holes 294) in the azimuthal direction between successive ridges 290 as shown in FIGS. 14, 15, and 18.

[0165] In addition to distributing the process gas uniformly throughout the plenum 259, the ridges 290 provide axial heat transfer from the faceplate 206 to the middle plate 204, which helps in cooling the first showerhead 200 in the axial direction (i.e., along the vertical axis that is perpendicular a diameter of the first showerhead 200). Specifically, when the faceplate 206 is bonded to the middle plate 204 (see FIG. 2), distal ends of the ridges 290 (i.e., ends points or terminal points up to which the ridges 290 extend) contact the bottom surface 257 of the middle plate 204. Thus, the ridges 290 are thermally coupled to the middle plate 204. The heat from the pedestal 104 (shown in FIG. 1 ) conducted by the faceplate 206 is transferred through the ridges 290 to the middle plate 204 and from the middle plate 204 to the top plate 202 of the first showerhead 200 (see FIG. 2). The heat transfer is optimized by designing the width (instead of height) of the ridges 290. For example, the width of the ridges 290 can be varied azimuthally (along the radius of the faceplate 206) to optimize the heat transfer. The heat transferred to the top plate 202 can be further conducted using a thermal resistor and can be removed using a cooling plate as follows.

EXAMPLES OF THERMAL RESISTOR AND COOLING PLATE

[0166] FIG. 19 shows the cross-sectional view of the top plate 202 shown in FIG. 3 along with a thermal resistor 300 and a cooling plate 310 disposed on the top plate 202. The thermal resistor 300 and the cooling plate 310 are generally cylindrical and have outer diameters less than or equal to the OD of the inner cylindrical portion 210 of the top plate 202 as described below in detail. The thermal resistor 300 and the cooling plate 310 shown and described herein are identical for the other showerheads (second, third, and fourth showerheads) shown and described below with reference to subsequent figures.

[0167] The thermal resistor 300 is disposed on the top surface 215 of the inner cylindrical portion 210 of the top plate 202. The thermal resistor 300 is described below in detail with reference to FIG. 20. Briefly, the thermal resistor 300 extends radially outwardly from an OD of the stem 112 (shown in FIG. 1) to the OD of the inner cylindrical portion 210 of the top plate 202. In some examples, the thermal resistor 300 may extend up to the annular channel 214. In some examples, the thermal resistor 300 may have an OD equal to the OD of the inner cylindrical portion 210 of the top plate 202. In some examples, the OD of the thermal resistor 300 may be less than the OD of the inner cylindrical portion 210 of the top plate 202. The thermal resistor 300 conducts the heat from the top plate 202 that is transferred to the top plate 202 from the faceplate 206 through the middle plate 204 (shown in FIG. 2).

[0168] The cooling plate 310 is stacked on top of the thermal resistor 300. The cooling plate 310 also extends radially outwardly from the OD of the stem 112 (shown in FIG. 1 ) to the OD of the inner cylindrical portion 210 of the top plate 202. In some examples, the cooling plate 310 may extend up to the annular channel 214. In some examples, the cooling plate 310 may have an OD equal to the OD of the inner cylindrical portion 210 of the top plate 202. In some examples, the OD of the cooling plate 310 may be less than the OD of the inner cylindrical portion 210 of the top plate 202.

[0169] The cooling plate 310 comprises a cooling channel 312 (e.g., a conduit). The cooling channel 312 is circular (e.g., spiral). The coolant from the fluid delivery system 140 (shown in FIG. 1 ) is circulated through the cooling channel 312. The cooling plate 310 conducts the heat from the thermal resistor 300. The coolant flowing through the cooling channel 312 removes the heat from the cooling plate 310, which cools the first showerhead 200.

[0170] FIG. 20 shows an example of the thermal resistor (also called the heat choke) 300 that is disposed between the top plate 202 and the cooling plate 310 as shown in FIG. 19. For example, the thermal resistor 300 comprises a first plate 330 and a second plate 332. The outer diameters of the first and second plates 330, 332 are less than or equal to the OD of the inner cylindrical portion 210 of the top plate 202. The first and second plates 330, 332 are made of materials (e.g., polyimide) having different thermal conductivities, each of which is less than the thermal conductivity of the material of which the top plate 202 and the cooling plate 310 are made (e.g., a metallic material).

[0171] In some examples, if the top plate 202 and the cooling plate 310 are made of a metallic material such as aluminum, the first plate 330 can be made of polyimide, and the second plate 332 can be made of a non-metal (e.g., a semiconductor material). Accordingly, the thermal conductivity of the first plate 330 may be less than that of the top plate 202 and greater than that of the second plate 332. Accordingly, the first and second plates 330, 332 form the thermal resistor 300 that gradually impedes heat flow (i.e., makes the heat flow gradual) from the top plate 202 to the cooling plate 310 to prevent overheating of the coolant in the cooling channel 312. Thus, the thermal resistor 300 prevents the coolant that flows through the cooling plate 310 from reaching a boiling point.

[0172] The first plate 330 additionally comprises the recessed portions 334, which provide air pockets that further increase the thermal resistance of the thermal resistor 300. Specifically, the first plate 330 comprises a plurality of recessed portions 334-1 , 334-2, 334-3, ..., and 334-N, where N is an integer greater than 1 (collectively, the recessed portions 334). The recessed portions 334 can be arranged on at least one of the top and bottom surfaces of the first plate 330. The size, shape, and quantity of the recessed portions 334 on the top surface of the first plate 330 can be such that about 65% of the surface area of the top surface of the first plate 330 is in contact with the bottom surface of the cooling plate 310.

[0173] Similarly, the size, shape, and quantity of the recessed portions 334 on the bottom surface of the first plate 330 can be such that about 65% of the surface area of the bottom surface of the first plate 330 is in contact with the top surface of the second plate 332. Other percentages may be used for contact areas of the top and bottom surfaces of the first plate 330. For example, the contact areas of the top and bottom surfaces of the first plate 330 may vary between 50-80%. Further, the contact areas of the top and bottom surfaces of the first plate 330 may be different (i.e., unequal).

[0174] More specifically, the first and second plates 330, 332 are made of materials having relatively low thermal conductivities. The first plate 330 may have a higher thermal conductivity than the second plate 332. The first and second plates 330, 332 provide thermal barriers for heat flowing from the top plate 202 to the cooling plate 310. The second plate 332 provides a thermal barrier for heat flowing from the top plate 202 to the first plate 330, and the first plate 330 provides a thermal barrier for heat flowing from the second plate 332 to the cooling plate 310. The first and second plates 330, 332 function as heat chokes or thermal resistors that are in series with each other. Accordingly, the second plate 332 and the first plate 330 present a gradually increasing thermal barrier or thermal resistance to the heat flowing from the top plate 202 to the cooling plate 310.

[0175] The recessed portions 334 comprise air pockets and are spaced throughout the first plate 330 on at least one of the top and bottom surfaces to further increase the thermal barrier. The stack of the first and second plates 330, 332 forms the thermal resistor 300 that prevents the cooling plate 310 from conducting relatively large amount of heat away from the top plate 202, which can force the heater elements disposed in the annular channel 214 (see FIGS. 2 and 19) to operate at a relatively higher capacity.

[0176] The thermal resistor 300 also prevents the coolant (e.g., water) in the cooling channel 312 from approaching the boiling point due to the heat flow. Accordingly, the cooling plate 310, and the heater elements disposed in the annular channel 214 (see FIGS. 2 and 19) provide a balance between the heating and cooling of the first showerhead 200 to minimize a temperature gradient across the faceplate 206.

[0177] In some examples, the first plate 330 may be manufactured as a monolithic plate. Alternatively, the first plate 330 may comprise three layers: two layers (top and bottom layers) comprising the recessed portions 334 (in the form of recesses or slots that are cut through the layers), and a third layer that is flat (i.e., without the recessed portions 334) and that is sandwiched between the two layers. The three layers may be bonded to each other (e.g., brazed or diffusion bonded).

[0178] The recessed portions 334 can be arranged on at least one of the top and bottom surfaces of the first plate 330 in many ways. The recessed portions 334 on the top surface of the first plate 330 may be aligned with the recessed portions 334 on the bottom surface of the first plate 330. Alternatively, the recessed portions 334 on the top surface of the first plate 330 may be offset relative to the recessed portions 334 on the bottom surface of the first plate 330. For example, the recessed portions 334 on the top surface of the first plate 330 may overlap at least one of the recessed portions 334 on the bottom surface of the first plate 330. Alternatively, none of the recessed portions 334 on the top surface of the first plate 330 may overlap the recessed portions 334 on the bottom surface of the first plate 330.

[0179] The recessed portions 334 on the top and bottom surfaces of the first plate 330 can have any size, shape, and quantity so long as the contact areas of the top and bottom surfaces of the first plate 330 are as described above. For example, the recessed portions 334 on the top and bottom surfaces of the first plate 330 may be of the same size and shape. Alternatively, the recessed portions 334 on the top surface of the first plate 330 may be of a different size and/or shape than the recessed portions 334 on the bottom surface of the first plate 330. The recessed portions 334 can be arranged on the top and bottom surfaces of the first plate 330 symmetrically or asymmetrically.

[0180] The number of the recessed portions 334 can be different (e.g., fewer or more) than that shown. The top and bottom surfaces of the first plate 330 may have the same number of the recessed portions 334. Alternatively, the top surface of the first plate 330 may comprise different number of the recessed portions 334 than the bottom surface of the first plate 330. The depth of the recessed portions 334 can be the same or can be different. The recessed portions 334 on the top and bottom surfaces of the first plate 330 can have the same depth. Alternatively, the recessed portions 334 on the top surface of the first plate 330 can have a first depth, and the recessed portions 334 on the bottom surface of the first plate 330 can have a second depth. The depths of the recessed portions 334 on the top surface of the first plate 330 can vary in a first pattern, and the depths of the recessed portions 334 on the bottom surface of the first plate 330 can vary in a second pattern. Any combination of the above variations may be used.

[0181] The ODs of the first and second plates 330, 332 may be less than or equal to the OD of the cooling plate 310. The thicknesses of the first and second plates 330, 332 can be varied depending on process requirements. The first plate 330 may be thicker than the second plate 332. In some applications, the second plate 332 may also comprise recessed portions on at least one of top and bottom surfaces and may comprise any of the variations described above with reference to the first plate 330.

[0182] Further, there may be additional permutations and combinations possible between the recessed portions of the first and second plates 330, 332. In some applications, the second plate 332 can be made of a thermoplastic material (e.g., polyimide), can comprise all of the structural features of the first plate 330 described above, and can be used independently (i.e., by itself instead of being used together with the first plate 330). Alternatively, in some applications, the second plate 332 may be omitted, and the first plate 330 can be made of the thermoplastic material (e.g., polyimide).

[0183] Further, while not shown, a third plate having a relatively low thermal conductivity may be used in addition to the first and second plates 330, 332. The third plate may be similar to any of the first and second plates 330, 332 except that the thermal conductivity of the third plate may be different than the first and second plates 330, 332. The third plate may be arranged above, below, or between the first and second plates 330, 332. The thermal conductivity of the third plate may be selected based on the location of the third plate. For example, the third plate arranged below the second plate 332 may have a lower thermal conductivity than the second plate 332. The third plate arranged above the first plate 330 may have a higher thermal conductivity than the first plate 330. The third plate arranged between the first and second plates 330, 332 may have a thermal conductivity less than the first plate 330 and greater than the second plate 332.

EXAMPLE OF SECOND SHOWERHEAD

[0184] A second showerhead can be constructed differently than the first showerhead 200 as follows. For example, in the second showerhead, the spoke-like first and second gas channels 250, 252 can be implemented in the top plate 202 instead of in the middle plate 204. In the second showerhead, instead of the middle plate 204, the top plate 202 comprises the first and second gas channels 250, 252 and the holes 280, 282, 284, 286 as described above with reference to FIGS. 4-8; and the middle plate 204 comprises only the holes 280, 282, 284, 286, which are in addition to the holes 280, 282, 284, 286 in the top plate 202. The holes 280, 282, 284, 286 in the top plate 202 mate (i.e., vertically align along the axis of the second showerhead) with the holes 280, 282, 284, 286 in the middle plate 204. Accordingly, the cross-sectional views of the top plate 202 and the middle plate 204 of the second showerhead differ from those for the first showerhead 200 shown in FIGS. 3 and 12-13 as follows. All of the description provided above with reference to the first showerhead 200 for the first and second gas channels 250, 252 and the holes 280, 282, 284, 286, and the description for the faceplate 206, which is identical to the faceplate 206 shown and described above with reference to FIGS. 14-18, applies to the second showerhead.

[0185] To differentiate from the top plate 202 and the middle plate 204 of the first showerhead 200, the top plate and the middle plate of the second showerhead are called a top plate 402 and a middle plate 404, respectively. As in the first showerhead 200, the sidewall 212 of the top plate 402, the middle plate 404, and the faceplate 206 have the same outer diameters (ODs). The top plate 402, the middle plate 404, and the faceplate 206 are diffusion bonded to form the second showerhead as described above with reference to the first showerhead 200. The side view of the second showerhead is identical to the side view of the first showerhead 200 shown in FIG. 2. The thermal resistor 300 and the cooling plate 310 can be stacked on the top plate 402 of the second showerhead similar to the first showerhead 200 as shown in FIG. 19. The second showerhead can be used as the showerhead 110 in the substrate processing system 100 shown in FIG. 1.

[0186] FIG. 21 shows a cross-sectional view of an example of the top plate 402 of the second showerhead, where instead of the middle plate 404, the top plate 402 comprises the spoke-like first and second gas channels 250, 252 and the holes 280, 282, 284, 286 shown in FIGS. 5-8, with the cross-sectional view taken along line C-C shown in FIG. 7. The outer geometry of the top plate 402 is identical to that of the top plate 202 shown and described above with reference to the first showerhead 200 (e.g., with reference to FIGS. 2 and 3). The internal structure of the top plate 402 of the second showerhead differs from that of the top plate 202 of the first showerhead 200 as follows.

[0187] The first and second gas channels 250, 252 and the circular cavity 254 are formed in the top plate 402 proximate to (above) the bottom surface 218 of the inner cylindrical portion 210 of the top plate 402. The second gas channel 252-5, the circular cavity 254, and the second gas channel 252-3 formed in the top plate 402 are visible in the view shown. The holes 280, 282, 284, 286 of the first and second gas channels 250, 252 (not visible in the view shown) are drilled through the bottom surface 218 of the inner cylindrical portion 210 of the top plate 402. The first and second gas channels 250, 252 lie within an ID of the annular channel 214 (i.e., within the OD of the inner cylindrical portion 210 of the top plate 402). Accordingly, the circle with radius R2 (shown in FIGS. 5, 7, and 8) lies within the OD of the inner cylindrical portion 210 of the top plate 402. A combined length of the conduit 220 and the flared gas outlet 224 in the second showerhead is less than that in the first showerhead 200.

[0188] FIG. 22 shows a cross-sectional view of the top plate 402 of the second showerhead, where instead of the middle plate 404, the top plate 402 comprises the spoke-like first and second gas channels 250, 252 and the holes 280, 282, 284, 286 shown in FIGS. 5-8, with the cross-sectional view taken along line D-D shown in FIG. 7. The first gas channel 250-3, the circular cavity 254, and the first gas channel 250-6 formed in the top plate 402 are visible in the view shown. Again, the outer geometry of the top plate 402 is identical to that of the top plate 202 of the first showerhead 200 shown and described above with reference to FIGS. 2 and 3. The internal structure of the top plate 402 of the second showerhead differs from that of the top plate 202 of the first showerhead 200 as described above with reference to FIG. 21 .

[0189] A bottom view of the top plate 402 and top and bottom views of the middle plate 404 of the second showerhead (and corresponding geometries and description) are identical to the bottom view (and corresponding geometries and description) of the middle plate 204 of the first showerhead 200 shown in FIG. 9 and are therefore omitted along with the corresponding description for brevity. Further, as described above, the faceplate 206 of the second showerhead is identical to the faceplate 206 of the first showerhead 200. Therefore, FIGS. 14-18 showing the faceplate 206 of the first showerhead 200 and corresponding description, which apply equally to the second showerhead, are also omitted for brevity.

[0190] FIG. 23 shows a cross-sectional view of an example of the middle plate 404 of the second showerhead, where instead of the middle plate 404, the top plate 402 comprises the spoke-like first and second gas channels 250, 252 and the holes 280, 282, 284, 286 shown in FIGS. 5-8, with the cross-sectional view taken along lines C-C and D-D shown in FIG. 10. As described above, the middle plate 404 comprises only the holes 280, 282, 284, 286, which, unlike in the middle plate 204 of the first showerhead 200, extend through the entire middle plate 404 from the top surface 256 of the middle plate 404 to the bottom surface 257 of the middle plate 404. While the holes 280, 282, 284, 286 in the middle plate 404 are not visible in the view shown, the top and bottom views of the middle plate 404 (and corresponding geometries and description) are identical to the bottom view (and corresponding geometries and description) of the middle plate 204 of the first showerhead 200 shown in FIG. 9.

[0191] When the top plate 402, the middle plate 404, and the faceplate 206 are bonded to form the second showerhead, the following elements of the second showerhead are in fluid communication with each other: the conduit 220; the flared gas outlet 224; the first and second gas channels 250, 252; the through holes 280, 282, 284, 286; the plenum 259; and the through holes 294. Specifically, the holes 280, 282, 284, 286 in the top plate 402 mate (i.e., vertically align along the axis of the showerhead) with the holes 280, 282, 284, 286 in the middle plate 404. The bottom surface 257 of middle plate 404, the gas passages 291 , 292 on the top surface 207 of the faceplate 206, and the sidewall 205 of the faceplate 206 define the plenum 259 of the second showerhead. Throughout the present disclosure, in all of the four showerheads, the plenum 259 also comprises the first and second gas channels 250, 252 and the through holes 280, 282, 284, 286 of the first and second gas channels 250, 252 regardless of where the first and second gas channels 250, 252 are implemented.

[0192] The process gas supplied through the stem 112 (shown in FIG. 1 ) flows through the conduit 220 and the flared gas outlet 224 in the top plate 402; the first and second gas channels 250, 252 in the top plate 402; the holes 280, 282, 284, 286 in the top plate 402; the holes 280, 282, 284, 286 in the middle plate 404; the gas passages 291 , 292 of the plenum 259 in the faceplate 206; and the through holes 294 in the faceplate 206 into the processing chamber 102 (shown in FIG. 1 ).

EXAMPLE OF THIRD SHOWERHEAD

[0193] A third showerhead can be constructed differently than the first showerhead 200 as follows. For example, in the third showerhead, the spoke-like first and second gas channels 250, 252 can be implemented in the top plate 202 instead of in the middle plate 204. In the third showerhead, instead of the middle plate 204, the top plate 202 comprises the first and second gas channels 250, 252 and the holes 280, 282, 284, 286 as described above with reference to FIGS. 4-8; and the middle plate 204 comprises the holes 280, 282, 284, 286, which are in addition to the holes 280, 282, 284, 286 in the top plate 202. The holes 280, 282, 284, 286 in the top plate 202 mate (i.e., vertically align along the axis of the third showerhead) with the holes 280, 282, 284, 286 in the middle plate 204.

[0194] Additionally, in the third showerhead, the ridges 290 are implemented on the bottom surface 257 of middle plate 204 instead of in the faceplate 206. Accordingly, the cross-sectional views of the top plate 202, the middle plate 204, and the faceplate 206 for the third showerhead differ from those for the first showerhead 200 shown in FIGS. 3 and 12-19 as follows. All of the description of the first and second gas channels 250, 252 and the holes 280, 282, 284, 286 provided above with reference to the first showerhead 200 applies to the third showerhead.

[0195] To differentiate from the top plate 202, the middle plate 204, and the faceplate 206 of the first showerhead 200, the top plate, the middle plate, and the faceplate of the third showerhead are called the top plate 402, which is identical to the top plate 402 described above with reference to the second showerhead, a middle plate 504, and a faceplate 506, respectively. As in the first showerhead 200, the sidewall 212 of the top plate 402, the middle plate 504, and the faceplate 506 have the same outer diameters (ODs). The top plate 402, the middle plate 504, and the faceplate 506 are diffusion bonded to form the third showerhead as described above with reference to the first showerhead 200. The side view of the third showerhead is identical to the side view of the first showerhead 200 shown in FIG. 2. Since the top plate 402 of the third showerhead (and corresponding geometries and description) is identical to the top plate 402 described above with reference to the second showerhead, the top plate 402 of the third showerhead (and corresponding geometries and description) is not shown and described again for brevity. The thermal resistor 300 and the cooling plate 310 can be stacked on the top plate 402 of the third showerhead similar to the first showerhead 200 as shown in FIG. 19. The third showerhead can be used as the showerhead 110 in the substrate processing system 100 shown in FIG. 1.

[0196] FIG. 24 shows a bottom view of an example of the middle plate 504 of the third showerhead, where instead of the middle plate 504, the top plate 402 comprises the spoke-like first and second gas channels 250, 252 and the holes 280, 282, 284, 286 shown in FIGS. 5-8; and instead of the faceplate 506, the middle plate 504 comprises the ridges 290 shown in FIGS. 14-17 at the bottom (i.e., on the bottom surface 257) of the middle plate 504. The ridges 290 extend vertically downwards parallel to the axis of the third showerhead from the bottom surface 257 of the middle plate 504. The ridges 290 have the same height d (shown in FIG. 27) as the depth d of the plenum 259 in the faceplate 506 (shown in FIG. 26). The geometric arrangement of the ridges 290 on the bottom surface 257 of the middle plate 504 is identical to the geometric arrangement of the ridges 290 on the top surface 207 of the faceplate 206 and is therefore not described again for brevity.

[0197] When the middle plate 504 is bonded to the faceplate 506, distal ends of the ridges 290 contact the top surface 207 of the faceplate 506. The ridges 290 lie on the top surface 207 of the faceplate 506 as shown and described with reference to FIGS. 14-17. The geometric arrangement of the holes 280, 282, 284, 286 in the middle plate 504 is identical to that described above with reference to the middle plate 404 of the second showerhead and is therefore not described again for brevity. The bottom view of the top plate 402 and the top view of the middle plate 504 of the third showerhead are identical to the bottom view of the middle plate 204 of the first showerhead 200 shown and described with reference to FIG. 9 and are therefore not shown and described again for brevity.

[0198] FIG. 25 shows a top view of an example of the faceplate 506 of the third showerhead, where instead of the faceplate 506, the middle plate 504 comprises the ridges 290 as shown in FIG. 15 at the bottom (i.e., on the bottom surface 257) of the middle plate 504 as shown in FIG. 24. Since the ridges 290 are not formed on the top surface 207 of the faceplate 506, only the through holes 294 are formed and are visible in the top view of the faceplate 506. The through holes 294 of the faceplate 506 of the third showerhead are identical to the through holes 294 of the faceplate 206 of the first showerhead 200 and are therefore not described again for brevity. Gaps between some of the concentric circles representing the through holes 294 on the top surface 207 of the faceplate 506 do not exist but are shown only to illustrate locations where the ridges 290 on the bottom surface 257 of the middle plate 504 lie on the top surface 207 of the faceplate 506 when the middle plate 504 is bonded to the faceplate 506.

[0199] When the middle plate 504 is bonded to the faceplate 506, the ridges 290 on the bottom surface 257 of the middle plate 504 lie on the top surface 207 of the faceplate 506. Due to the geometric arrangement of the ridges 290 described above, the ridges 290 form the gas passages 291 , 292 on the top surface 207 of the faceplate 506. The ridges 290 and the gas passages 292 are arranged in a pattern that is consistent with a pattern in which the spoke-like first and second gas channels 250, 252 and the holes 280, 282, 284, 286 are arranged in the top plate 402 and in the middle plate 504. The ridges 290 on the bottom surface 257 of the middle plate 504, the gas passages 291 , 292 on the top surface 207 of the faceplate 506, the bottom surface 257 of the middle plate 504, the top surface 207 of the faceplate 506, and the sidewall 205 of the faceplate 506 define the plenum 259 (shown in FIG. 26) of the third showerhead.

[0200] FIG. 26 shows a cross-sectional view of the faceplate 506 shown in FIG. 25 taken along line H-H shown in FIG. 25. The plenum 259 is visible in the view shown. The structure of the through holes 294 is identical to that shown and described with reference to FIG. 17 and is therefore not repeated for brevity.

[0201] FIG. 27 shows a cross-sectional view of the middle plate 504 shown in FIG. 24 taken along lines F-F and G-G shown in FIG. 24. The ridges 290 formed on the bottom surface 257 of the middle plate 504 are visible in the cross-sectional view shown. Since the ridges 290 have the same height d as the depth d of the plenum 259 formed in the faceplate 506, when the faceplate 506 is bonded to the middle plate 504, the distal ends of the ridges 290 contact the top surface 207 of the faceplate 506 (shown in FIG. 26). The holes 280, 282, 284, 286 in the middle plate 504 are not visible in the cross- sectional view shown. As in the middle plate 404 of the second showerhead and unlike in the middle plate 204 of the first showerhead 200, the holes 280, 282, 284, 286 in the middle plate 504 extend through the entire middle plate 504 from the top surface 256 of the middle plate 504 to the bottom surface 257 of the middle plate 504.

[0202] When the top plate 402, the middle plate 504, and the faceplate 506 are bonded to form the third showerhead, the following elements of the third showerhead are in fluid communication with each other: the conduit 220; the flared gas outlet 224; the first and second gas channels 250, 252; the through holes 280, 282, 284, 286; the plenum 259; and the through holes 294. Specifically, the holes 280, 282, 284, 286 in the top plate 402 mate (i.e., vertically align along the axis of the showerhead) with the holes 280, 282, 284, 286 in the middle plate 504; and the ridges 290 on the bottom surface 257 of the middle plate 504 lie on the top surface 207 of the faceplate 506 as described above. The process gas supplied through the stem 112 (shown in FIG. 1 ) flows through the conduit 220 and the flared gas outlet 224 in the top plate 402; the first and second gas channels 250, 252 in the top plate 402; the holes 280, 282, 284, 286 in the top plate 402; the holes 280, 282, 284, 286 in the middle plate 504; the gas passages 291 , 292 of the plenum 259 in the faceplate 506; and the through holes 294 in the faceplate 506 into the processing chamber 102 (shown in FIG. 1 ).

EXAMPLE OF FOURTH SHOWERHEAD

[0203] A fourth showerhead can be constructed differently than the first showerhead 200 as follows. For example, in the fourth showerhead, in addition to the spoke-like first and second gas channels 250, 252, the ridges 290 can be implemented in the middle plate 204 instead of in the faceplate 206. In the fourth showerhead, the middle plate 204 comprises the first and second gas channels 250, 252 and the holes 280, 282, 284, 286 as described above with reference to FIGS. 4-8; and instead of the faceplate 206, the middle plate 204 additionally comprises the ridges 290. Specifically, in the fourth showerhead, the ridges 290 are formed on the bottom surface 257 of middle plate 204 of the fourth showerhead instead of in the faceplate 206. Accordingly, the cross- sectional views of the middle plate 204 and the faceplate 206 of the fourth showerhead differ from those for the first showerhead 200 shown in FIGS. 3 and 12-19 as follows. All of the description of the first and second gas channels 250, 252 and the holes 280, 282, 284, 286 provided above with reference to the first showerhead 200 applies to the fourth showerhead.

[0204] To differentiate from the middle plate 204 and the faceplate 206 of the first showerhead 200, the middle plate and the faceplate of the fourth showerhead are called a middle plate 604, and the faceplate 506, which is identical to the faceplate 506 of the third showerhead, respectively. As in the first showerhead 200, the sidewall 212 of the top plate 202, the middle plate 604, and the faceplate 506 have the same outer diameters (ODs). The top plate 202, the middle plate 604, and the faceplate 506 are diffusion bonded to form the fourth showerhead as described above with reference to the first showerhead 200. The side view of the fourth showerhead is identical to the side view of the first showerhead 200 shown in FIG. 2. The fourth showerhead can be used as the showerhead 110 in the substrate processing system 100 shown in FIG. 1 .

[0205] The top plate 202 of the fourth showerhead (and corresponding geometries and description) is identical to the top plate 202 of the first showerhead 200 shown in FIGS. 2 and 3. Accordingly, the top plate 202 of the fourth showerhead (and corresponding geometries and description) is not shown and described again for brevity. The thermal resistor 300 and the cooling plate 310 can be stacked on the top plate 202 of the fourth showerhead similar to the first showerhead 200 as shown in FIG. 19. [0206] The top view and the transverse section of the middle plate 604 (and corresponding geometries and description) are identical to those of the middle plate 204 of the first showerhead 200 (and corresponding geometries and description) shown in FIGS. 4-8, 10, and 11 and are therefore not shown and described again for brevity. The bottom view of the middle plate 604 (and corresponding geometries and description) is identical to the bottom view of the middle plate 504 of the third showerhead (and corresponding geometries and description) shown in FIG. 24 and is therefore not shown and described again for brevity. The faceplate 506 of the fourth showerhead (and corresponding geometries and description) is identical to the faceplate 506 of the third showerhead (and corresponding geometries and description) shown in FIGS. 25 and 26 and is therefore not shown and described again for brevity.

[0207] FIG. 28 shows a cross-sectional view of an example of the middle plate 604 of the fourth showerhead, where instead of the faceplate 506, the middle plate 604 additionally comprises the ridges 290 as shown in FIG. 24 at the bottom of the middle plate 604, with the cross-sectional view taken along line C-C shown in FIG. 10. As in the cross-sectional view of the middle plate 204 of the first showerhead 200 shown in FIG. 12, the spoke-like second gas channels 252-2, 252-5 and the circular cavity 254 are visible in the cross-sectional view of the middle plate 604 taken along line C-C shown in FIG. 10. Additionally, the ridges 290 on the bottom surface 257 of the middle plate 604 are visible. The ridges 290 have the same height d as the depth d of the plenum 259 in the faceplate 506 (shown in FIG. 26).

[0208] FIG. 29 shows a cross-sectional view of an example of the middle plate 604 of the fourth showerhead, where instead of the faceplate 506, the middle plate 604 additionally comprises the ridges 290 as shown in FIG. 24 at the bottom of the middle plate 604, with the cross-sectional view taken along line D-D shown in FIG. 10. As in the cross-sectional view of the middle plate 204 of the first showerhead 200 shown in FIG. 13, the spoke-like first gas channels 252-3, 252-6 and the circular cavity 254 are visible in the cross-sectional view of the middle plate 604 taken along line D-D shown in FIG. 10. Additionally, the ridges 290 on the bottom surface 257 of the middle plate 604 are visible. The ridges 290 have the same height d as the depth d of the plenum 259 in the faceplate 506 (shown in FIG. 26).

[0209] When the middle plate 604 is bonded to the faceplate 506, the ridges 290 on the bottom surface 257 of the middle plate 604 lie on the top surface 207 of the faceplate 506. Due to the geometric arrangement of the ridges 290 described above, the ridges 290 form the gas passages 292 on the top surface 207 of the faceplate 506. The ridges 290 and the gas passages 292 are arranged in a pattern that is consistent with a pattern in which the spoke-like first and second gas channels 250, 252 and the holes 280, 282, 284, 286 arranged in the middle plate 604. The ridges 290 on the bottom surface 257 of the middle plate 604, the gas passages 291 , 292 on the top surface 207 of the faceplate 506, the bottom surface 257 of the middle plate 604, the top surface 207 of the faceplate 506, and the sidewall 205 of the faceplate 506 define the plenum 259 (shown in FIG. 26) of the fourth showerhead.

[0210] When the top plate 202, the middle plate 604, and the faceplate 506 are bonded to form the fourth showerhead, the following elements of the fourth showerhead are in fluid communication with each other: the conduit 220; the flared gas outlet 224; the first and second gas channels 250, 252; the through holes 280, 282, 284, 286; the plenum 259; and the through holes 294. The process gas supplied through the stem 112 (shown in FIG. 1 ) flows through the conduit 220 and the flared gas outlet 224 in the top plate 202; the first and second gas channels 250, 252 and the holes 280, 282, 284, 286 in the middle plate 604; the gas passages 291 , 292 of the plenum 259 in the faceplate 506; and the through holes 294 in the faceplate 506 into the processing chamber 102 (shown in FIG. 1 ).

[0211] FIG. 30 shows a summary of all the features of the top plates, middle plates, and the faceplates of the four showerheads that are shown in FIGS. 2-29. The figure is self-explanatory and is therefore not described for brevity.

[0212] The foregoing description is merely illustrative in nature and is not intended to limit the disclosure, its application, or uses. The broad teachings of the disclosure can be implemented in a variety of forms. Therefore, while this disclosure includes particular examples, the true scope of the disclosure should not be so limited since other modifications will become apparent upon a study of the drawings, the specification, and the following claims.

[0213] It should be understood that one or more steps within a method may be executed in different order (or concurrently) without altering the principles of the present disclosure. Further, although each of the examples is described above as having certain features, any one or more of those features described with respect to any one of the examples of the disclosure can be implemented in and/or combined with features of any of the other examples, even if that combination is not explicitly described. In other words, the described examples are not mutually exclusive, and permutations of one or more examples with one another remain within the scope of this disclosure.

[0214] Spatial and functional relationships between elements (for example, between modules, circuit elements, semiconductor layers, etc.) are described using various terms, including “connected,” “engaged,” “coupled,” “adjacent,” “next to,” “on top of,” “above,” “below,” and “disposed.” Unless explicitly described as being “direct,” when a relationship between first and second elements is described in the above disclosure, that relationship can be a direct relationship where no other intervening elements are present between the first and second elements, but can also be an indirect relationship where one or more intervening elements are present (either spatially or functionally) between the first and second elements. As used herein, the phrase at least one of A, B, and C should be construed to mean a logical (A OR B OR C), using a non-exclusive logical OR, and should not be construed to mean “at least one of A, at least one of B, and at least one of C.”

[0215] In some implementations, a controller is part of a system, which may be part of the above-described examples. Such systems can comprise semiconductor processing equipment, including a processing tool or tools, chamber or chambers, a platform or platforms for processing, and/or specific processing components (a wafer pedestal, a gas flow system, etc.). These systems may be integrated with electronics for controlling their operation before, during, and after processing of a semiconductor wafer or substrate.

[0216] The electronics may be referred to as the “controller,” which may control various components or subparts of the system or systems. The controller, depending on the processing requirements and/or the type of system, may be programmed to control any of the processes disclosed herein, including the delivery of processing gases, temperature settings (e.g., heating and/or cooling), pressure settings, vacuum settings, power settings, radio frequency (RF) generator settings, RF matching circuit settings, frequency settings, flow rate settings, fluid delivery settings, positional and operation settings, wafer transfers into and out of a tool and other transfer tools and/or load locks connected to or interfaced with a specific system.

[0217] Broadly speaking, the controller may be defined as electronics having various integrated circuits, logic, memory, and/or software that receive instructions, issue instructions, control operation, enable cleaning operations, enable endpoint measurements, and the like. The integrated circuits may include chips in the form of firmware that store program instructions, digital signal processors (DSPs), chips defined as application specific integrated circuits (ASICs), and/or one or more microprocessors, or microcontrollers that execute program instructions (e.g., software).

[0218] Program instructions may be instructions communicated to the controller in the form of various individual settings (or program files), defining operational parameters for carrying out a particular process on or for a semiconductor wafer or to a system. The operational parameters may, in some examples, be part of a recipe defined by process engineers to accomplish one or more processing steps during the fabrication of one or more layers, materials, metals, oxides, silicon, silicon dioxide, surfaces, circuits, and/or dies of a wafer.

[0219] The controller, in some implementations, may be a part of or coupled to a computer that is integrated with the system, coupled to the system, otherwise networked to the system, or a combination thereof. For example, the controller may be in the “cloud” or all or a part of a fab host computer system, which can allow for remote access of the wafer processing. The computer may enable remote access to the system to monitor current progress of fabrication operations, examine a history of past fabrication operations, examine trends or performance metrics from a plurality of fabrication operations, to change parameters of current processing, to set processing steps to follow a current processing, or to start a new process.

[0220] In some examples, a remote computer (e.g., a server) can provide process recipes to a system over a network, which may include a local network or the Internet. The remote computer may include a user interface that enables entry or programming of parameters and/or settings, which are then communicated to the system from the remote computer. In some examples, the controller receives instructions in the form of data, which specify parameters for each of the processing steps to be performed during one or more operations. It should be understood that the parameters may be specific to the type of process to be performed and the type of tool that the controller is configured to interface with or control.

[0221] Thus, as described above, the controller may be distributed, such as by comprising one or more discrete controllers that are networked together and working towards a common purpose, such as the processes and controls described herein. An example of a distributed controller for such purposes would be one or more integrated circuits on a chamber in communication with one or more integrated circuits located remotely (such as at the platform level or as part of a remote computer) that combine to control a process on the chamber. [0222] Without limitation, example systems may include a plasma etch chamber or module, a deposition chamber or module, a spin-rinse chamber or module, a metal plating chamber or module, a clean chamber or module, a bevel edge etch chamber or module, a physical vapor deposition (PVD) chamber or module, a chemical vapor deposition (CVD) chamber or module, an atomic layer deposition (ALD) chamber or module, an atomic layer etch (ALE) chamber or module, an ion implantation chamber or module, a track chamber or module, and any other semiconductor processing systems that may be associated or used in the fabrication and/or manufacturing of semiconductor wafers.

[0223] As noted above, depending on the process step or steps to be performed by the tool, the controller might communicate with one or more of other tool circuits or modules, other tool components, cluster tools, other tool interfaces, adjacent tools, neighboring tools, tools located throughout a factory, a main computer, another controller, or tools used in material transport that bring containers of wafers to and from tool locations and/or load ports in a semiconductor manufacturing factory.

Claims

CLAIMS What is claimed is:

1 . A showerhead for a substrate processing system, the showerhead comprising: a first plate comprising a first plurality of gas channels of a first length and a second plurality of gas channels of a second length that is greater than the first length, the first and second plurality of gas channels extending radially from a center of the first plate towards an outer diameter of the first plate in an alternating sequence; and a faceplate coupled to the first plate, the faceplate comprising a plurality of through holes, the faceplate and the first plate defining a plenum, and the first and second plurality of gas channels and the plurality of through holes being in fluid communication with the plenum.

2. The showerhead of claim 1 wherein the first plate comprises a circular cavity at the center of the first plate and the first and second plurality of gas channels extend from the circular cavity, the showerhead further comprising: a second plate disposed on the first plate, the second plate comprising a conduit extending through the second plate, the conduit comprising an inlet at a top surface of the second plate and a flared outlet at a bottom surface of the second plate, the flared outlet extending radially outwardly towards an outer diameter of the second plate and aligning with the circular cavity at the center of the first plate.

3. The showerhead of claim 2 wherein diameters of the circular cavity and the flared outlet are equal.

4. The showerhead of claim 2 wherein a depth of the first and second plurality of gas channels and the circular cavity is less than a thickness of the first plate.

5. The showerhead of claim 2 wherein the gas channels of the first plurality of gas channels are separated from each other by a first angle, the gas channels of the second plurality of gas channels are separated from each other by the first angle, and adjacent ones of the first and second plurality of gas channels are separated from each other by a second angle that is less than the first angle.

6. The showerhead of claim 2 wherein each of the first plurality of gas channels comprises: a first portion extending radially from the circular cavity; a second portion extending from a distal end of the first portion towards an adjacent one of the second plurality of gas channels; and a third portion extending from a distal end of the second portion along a radius of the first plate, the second and third portions being of shorter length than the first portion, the third portion comprising a plurality of holes extending through a bottom surface of the first plate coupled to the faceplate, the plurality of holes being in fluid communication with the plenum.

7. The showerhead of claim 6 wherein: the first portions of diametrically opposite ones of the first plurality of gas channels lie along a first diameter of the first plate; and the third portions and respective ones of the holes in the third portions of the diametrically opposite ones of the first plurality of gas channels lie along a second diameter of the first plate.

8. The showerhead of claim 7 wherein the faceplate comprises concentric ridges and radially extending gas passages that intersect and pass through a plurality of the concentric ridges and wherein the third portions of the first plurality of gas channels are aligned with a plurality of the gas passages.

9. The showerhead of claim 8 wherein the concentric ridges contact the bottom surface of the first plate.

10. The showerhead of claim 8 wherein a height of the concentric ridges is equal to a depth of the plenum.

11 . The showerhead of claim 8 wherein the through holes are arranged along concentric circles distributed from a center of the faceplate to an outer diameter of the faceplate, with three of the concentric circles being distributed between successive ones of the concentric ridges, and wherein outlets of the through holes are conical.

12. The showerhead of claim 2 wherein each of the second plurality of gas channels comprises: a first portion extending radially from the circular cavity; a second portion extending from a distal end of the first portion towards an adjacent one of the first plurality of gas channels; and a third portion extending from a distal end of the second portion along a radius of the first plate, the second and third portions being of shorter length than the first portion, the third portion comprising a plurality of holes extending through a bottom surface of the first plate coupled to the faceplate, the plurality of holes being in fluid communication with the plenum.

13. The showerhead of claim 12 wherein: the first portions of diametrically opposite ones of the second plurality of gas channels lie along a first diameter of the first plate; and the third portions and respective ones of the holes in the third portions of the diametrically opposite ones of the second plurality of gas channels lie along a second diameter of the first plate.

14. The showerhead of claim 13 wherein the faceplate comprises concentric ridges and radially extending gas passages that intersect and pass through a plurality of the concentric ridges and wherein the third portions of the second plurality of gas channels are aligned with a plurality of the gas passages.

15. The showerhead of claim 14 wherein the concentric ridges contact the bottom surface of the first plate.

16. The showerhead of claim 14 wherein a height of the concentric ridges is equal to a depth of the plenum.

17. The showerhead of claim 14 wherein the through holes are arranged along concentric circles distributed from a center of the faceplate to an outer diameter of the faceplate, with three of the concentric circles being distributed between successive ones of the concentric ridges, and wherein outlets of the through holes are conical.

18. The showerhead of claim 2 wherein the second plate comprises an inner cylindrical portion and a sidewall surrounding the inner cylindrical portion and defining an annular channel between the inner cylindrical portion and the sidewall.

19. The showerhead of claim 18 wherein outer diameters of the first plate, the faceplate, and the sidewall are equal.

20. The showerhead of claim 18 further comprising: a heater disposed in the annular channel; a third plate disposed on the inner cylindrical portion, the third plate comprising a material of a different thermal conductivity than the first and second plates and the faceplate; and a cooling plate comprising a cooling channel disposed on the third plate.

21. The showerhead of claim 20 wherein outer diameters of the third plate and the cooling plate are less than or equal to an inner diameter of the annular channel.

22. The showerhead of claim 20 wherein the first plate, the second plate, and the faceplate comprise a metallic material and wherein the material of the third plate comprises a polyimide.

23. The showerhead of claim 20 wherein the third plate comprises air pockets.

24. The showerhead of claim 1 wherein the first plate comprises: a circular cavity at the center of the first plate, the circular cavity being proximate to a bottom surface of the first plate, the first and second plurality of gas channels extending from the circular cavity along the bottom surface of the first plate; and a conduit extending from a top surface of the first plate towards the bottom surface of the first plate through the center of the first plate, the conduit comprising an inlet at the top surface of the first plate and a flared outlet that extends radially outwardly towards an outer diameter of the first plate and that is aligned with the circular cavity.

25. The showerhead of claim 24 wherein diameters of the circular cavity and the flared outlet are equal.

26. The showerhead of claim 24 wherein a depth of the first and second plurality of gas channels and the circular cavity is less than a thickness of the first plate.

27. The showerhead of claim 24 wherein the gas channels of the first plurality of gas channels are separated from each other by a first angle, the gas channels of the second plurality of gas channels are separated from each other by the first angle, and adjacent ones of the first and second plurality of gas channels are separated from each other by a second angle that is less than the first angle.

28. The showerhead of claim 24 wherein each of the first plurality of gas channels comprises: a first portion extending radially from the circular cavity; a second portion extending from a distal end of the first portion towards an adjacent one of the second plurality of gas channels; and a third portion extending from a distal end of the second portion along a radius of the first plate, the second and third portions being of shorter length than the first portion, the third portion comprising a plurality of holes extending through the bottom surface of the first plate.

29. The showerhead of claim 28 wherein: the first portions of diametrically opposite ones of the first plurality of gas channels lie along a first diameter of the first plate; and the third portions and respective ones of the holes in the third portions of the diametrically opposite ones of the first plurality of gas channels lie along a second diameter of the first plate.

30. The showerhead of claim 29 further comprising a second plate disposed between the first plate and the faceplate, the second plate comprising a second plurality of through holes that is aligned with the plurality of holes in the first plate.

31. The showerhead of claim 30 wherein the first plurality of gas channels and the plurality of holes in the first plate and the second plurality of through holes in the second plate are in fluid communication with the plenum.

32. The showerhead of claim 30 wherein: the faceplate comprises concentric ridges and radially extending gas passages that intersect and pass through a plurality of the concentric ridges; and the third portions of the first plurality of gas channels in the first plate and the second plurality of through holes in the second plate are aligned with a plurality of the gas passages.

33. The showerhead of claim 32 wherein the concentric ridges contact the bottom surface of the second plate.

34. The showerhead of claim 32 wherein a height of the concentric ridges is equal to a depth of the plenum.

35. The showerhead of claim 32 wherein the through holes are arranged along concentric circles distributed from a center of the faceplate to an outer diameter of the faceplate, with three of the concentric circles being distributed between successive ones of the concentric ridges, and wherein outlets of the through holes are conical.

36. The showerhead of claim 24 wherein each of the second plurality of gas channels comprises: a first portion extending radially from the circular cavity; a second portion extending from a distal end of the first portion towards an adjacent one of the first plurality of gas channels; and a third portion extending from a distal end of the second portion along a radius of the first plate, the second and third portions being of shorter length than the first portion, the third portion comprising a plurality of holes extending through the bottom surface of the first plate.

37. The showerhead of claim 36 wherein: the first portions of diametrically opposite ones of the second plurality of gas channels lie along a first diameter of the first plate; and the third portions and respective ones of the holes in the third portions of the diametrically opposite ones of the second plurality of gas channels lie along a second diameter of the first plate.

38. The showerhead of claim 37 further comprising a second plate disposed between the first plate and the faceplate, the second plate comprising a second plurality of through holes that is aligned with the plurality of holes in the first plate.

39. The showerhead of claim 38 wherein the second plurality of gas channels and the plurality of holes in the first plate and the second plurality of through holes in the second plate are in fluid communication with the plenum.

40. The showerhead of claim 38 wherein: the faceplate comprises concentric ridges and radially extending gas passages that intersect and pass through a plurality of the concentric ridges; and the third portions of the second plurality of gas channels in the first plate and the second plurality of through holes in the second plate are aligned with a plurality of the gas passages.

41 . The showerhead of claim 40 wherein the concentric ridges contact the bottom surface of the second plate.

42. The showerhead of claim 40 wherein a height of the concentric ridges is equal to a depth of the plenum.

43. The showerhead of claim 40 wherein the through holes are arranged along concentric circles distributed from a center of the faceplate to an outer diameter of the faceplate, with three of the concentric circles being distributed between successive ones of the concentric ridges, and wherein outlets of the through holes are conical.

44. The showerhead of claim 24 wherein the first plate comprises an inner cylindrical portion and a sidewall surrounding the inner cylindrical portion and defining an annular channel between the inner cylindrical portion and the sidewall.

45. The showerhead of claim 44 wherein the first and second plurality of gas channels are disposed in the inner cylindrical portion and lie within an inner diameter of the annular channel.

46. The showerhead of claim 45 wherein the first and second plurality of gas channels comprise a plurality of holes extending through the bottom surface of the first plate, the showerhead further comprising: a second plate disposed between the first plate and the faceplate, the second plate comprising a second plurality of through holes that is aligned with the plurality of holes in the first plate.

47. The showerhead of claim 46 wherein outer diameters of the second plate, the faceplate, and the sidewall are equal.

48. The showerhead of claim 46 further comprising: a heater disposed in the annular channel; a third plate disposed on the inner cylindrical portion, the third plate comprising a material of a different thermal conductivity than the first and second plates and the faceplate; and a cooling plate comprising a cooling channel disposed on the third plate.

49. The showerhead of claim 48 wherein outer diameters of the third plate and the cooling plate are less than or equal to an inner diameter of the annular channel.

50. The showerhead of claim 48 wherein the first plate, the second plate, and the faceplate comprise a metallic material and wherein the material of the third plate comprises a polyimide.

51 . The showerhead of claim 48 wherein the third plate comprises air pockets.

52. The showerhead of claim 30 wherein the second plate further comprises concentric ridges extending from a bottom surface of the second plate and contacting the faceplate, and wherein: the faceplate comprises radially extending gas passages that intersect and pass through a plurality of the concentric ridges; and the third portions of the first plurality of gas channels in the first plate and the second plurality of through holes in the second plate are aligned with a plurality of the gas passages.

53. The showerhead of claim 52 wherein a height of the concentric ridges is equal to a depth of the plenum.

54. The showerhead of claim 52 wherein the through holes are arranged along concentric circles distributed from a center of the faceplate to an outer diameter of the faceplate, with three of the concentric circles being distributed between successive ones of the concentric ridges, and wherein outlets of the through holes are conical.

55. The showerhead of claim 38 wherein the second plate further comprises concentric ridges extending from a bottom surface of the second plate and contacting the faceplate, and wherein: the faceplate comprises radially extending gas passages that intersect and pass through a plurality of the concentric ridges; and the third portions of the second plurality of gas channels in the first plate and the second plurality of through holes in the second plate are aligned with a plurality of the gas passages.

56. The showerhead of claim 55 wherein a height of the concentric ridges is equal to a depth of the plenum.

57. The showerhead of claim 55 wherein the through holes are arranged along concentric circles distributed from a center of the faceplate to an outer diameter of the faceplate, with three of the concentric circles being distributed between successive ones of the concentric ridges, and wherein outlets of the through holes are conical.

58. The showerhead of claim 24 wherein: the first plate comprises an inner cylindrical portion and a sidewall surrounding the inner cylindrical portion and defining an annular channel between the inner cylindrical portion and the sidewall; the first and second plurality of gas channels are disposed in the inner cylindrical portion and lie within an inner diameter of the annular channel; and the first and second plurality of gas channels comprise a plurality of holes extending through the bottom surface of the first plate.

59. The showerhead of claim 58 further comprising a second plate disposed between the first plate and the faceplate, the second plate comprising a second plurality of through holes that is aligned with the plurality of holes in the first plate and comprising concentric ridges extending from a bottom surface of the second plate and contacting the faceplate.

60. The showerhead of claim 59 wherein outer diameters of the second plate, the faceplate, and the sidewall are equal.

61 . The showerhead of claim 59 further comprising: a heater disposed in the annular channel; a third plate disposed on the inner cylindrical portion, the third plate comprising a material of a different thermal conductivity than the first and second plates and the faceplate; and a cooling plate comprising a cooling channel disposed on the third plate.

62. The showerhead of claim 61 wherein outer diameters of the third plate and the cooling plate are less than or equal to an inner diameter of the annular channel.

63. The showerhead of claim 61 wherein the first plate, the second plate, and the faceplate comprise a metallic material and wherein the material of the third plate comprises a polyimide.

64. The showerhead of claim 61 wherein the third plate comprises air pockets.

65. The showerhead of claim 7 wherein the first plate further comprises concentric ridges extending from a bottom surface of the first plate and contacting the faceplate, and wherein: the faceplate comprises radially extending gas passages that intersect and pass through a plurality of the concentric ridges; and the third portions of the first plurality of gas channels in the first plate and the plurality of holes in the second plate are aligned with a plurality of the gas passages.

66. The showerhead of claim 65 wherein a height of the concentric ridges is equal to a depth of the plenum.

67. The showerhead of claim 65 wherein the through holes are arranged along concentric circles distributed from a center of the faceplate to an outer diameter of the faceplate, with three of the concentric circles being distributed between successive ones of the concentric ridges, and wherein outlets of the through holes are conical.

68. The showerhead of claim 13 wherein the first plate further comprises concentric ridges extending from a bottom surface of the first plate and contacting the faceplate, and wherein: the faceplate comprises radially extending gas passages that intersect and pass through a plurality of the concentric ridges; and the third portions of the second plurality of gas channels in the first plate and the plurality of holes in the first plate are aligned with a plurality of the gas passages.

69. The showerhead of claim 68 wherein a height of the concentric ridges is equal to a depth of the plenum.

70. The showerhead of claim 68 wherein the through holes are arranged along concentric circles distributed from a center of the faceplate to an outer diameter of the faceplate, with three of the concentric circles being distributed between successive ones of the concentric ridges, and wherein outlets of the through holes are conical.