US20110203735A1

US20110203735A1 - Gas injection system for etching profile control

Info

Publication number: US20110203735A1
Application number: US13/032,861
Authority: US
Inventors: Seongsul SEO; Sungyong KO; Yunsook CHAE; Hwankook CHAE; Keehyun KIM; Weonmook LEE
Original assignee: Individual
Current assignee: DMS Co Ltd
Priority date: 2010-02-23
Filing date: 2011-02-23
Publication date: 2011-08-25
Also published as: TW201130041A; CN102162099B; KR101092122B1; TWI446441B; CN102162099A; KR20110096649A

Abstract

A gas injection system provided in a plasma etching equipment is provided. The system includes a top gas injector for supplying a reaction gas at a top of a chamber, and a side gas injector for supplying a tuning gas from a side surface of the chamber or a backside gas injector upward jetting a tuning gas from a lower side of a wafer. The side gas injector or backside gas injector forms a plurality of jets in a radial shape and simultaneously installs the jets adjacently to an edge part of a wafer such that a tuning gas is jetted adjacently to the edge part of the wafer, thereby being capable of easily controlling a an etch rate or CD uniformity or profile of the edge part.

Description

CROSS REFERENCE

This application claims foreign priority under Paris Convention and 35 U.S.C. §119 to Korean Patent Application No. 10-2010-0015999, filed Feb. 23, 2010 with the Korean Intellectual Property Office.

BACKGROUND OF THE INVENTION

1. Field of the Invention
The present invention relates to a gas injection system provided in a plasma etching equipment. More particularly, the present invention relates to a gas injection system for etching profile control, for jetting a tuning gas adjacently to an edge part of a wafer for a user to precisely control an etch rate or a Critical Dimension (CD) uniformity and profile in the edge part, thereby being capable of improving an etching uniformity through uniform formation of a Critical Dimension (CD) and profile of the whole wafer and minimizing a process failure.
2. Description of the Related Art
Generally, an ultra-fine circuit or pattern of a desired is formed on a surface of a large-diameter wafer used for a semiconductor Integrated Circuit (IC) device, a glass substrate being a key part used for a Liquid Crystal Display (LCD) or the like by forming several thin film layers on the surface and also selectively removing only part of a thin film.
This fine circuit or pattern manufacturing is generally carried out through many manufacturing processes such as a rinse process, a deposition process, a photolithography process, a plating process, an etching process and the like.
In the above various treatment processes, a wafer or substrate is input to a chamber or reaction furnace capable of isolating the wafer or substrate from the external and is processed.
Among the above processes, particularly, the etching process is a process of jetting a suitable reaction gas (e.g., CxFx series, SxFx series, hydrogen bromide (HBr), oxygen (O₂), argon (Ar) and the like) into the chamber or reaction furnace, thereby selectively removing desired materials from a wafer surface through a physical or chemical reaction of a plasma state and forming a specific fine circuit on a substrate surface.
In this etching process, because it is of significance above all things to make a CD or profile uniform and maintain an etching uniformity in the whole wafer surface, it is of significance to uniformly diffuse a reaction gas within a chamber and uniformly distribute plasma within the chamber.
However, there was a problem that a chip yield of an edge part is remarkably deteriorated because etch rates of a center part and outer part (i.e., edge part) of a wafer are generally different from each other and CD uniformity or profiles are differently formed. Particularly, with the large-diameter trend of a wafer and the progress of high integration of a semiconductor device, the control of a CD uniformity or profile of an edge part is being raised as the most important issue.
Accordingly, to address the problems, the conventional art divides a coolant chiller into inner and outer parts and uses a temperature difference on a wafer, thereby controlling a CD. Or, the conventional art forms dividing a showerhead supplying a reaction gas into inner and outer parts to divide a reaction gas supply area, thereby controlling the distribution of plasma in a center part and edge part of a wafer and controlling a CD.
Besides this, a method of controlling a CD by additionally supplying a gas of O₂to a wafer was used.
However, the conventional control method had the following problems.
Firstly, regarding controlling a temperature of a wafer, in a case where high power is used as in an oxide film etching process (i.e., an oxide process), a CD control effect due to temperature control is unsatisfied.
Secondly, regarding dividing a showerhead into inner and outer parts or additionally supplying a O₂gas to a wafer, in a case where a chamber volume is large like an etching device making use of a high-density Inductively Coupled Plasma (ICP) source, a spaced distance between a gas supply unit and a wafer edge part is large, so it is difficult to precisely control the distribution of plasma by a difference of gas diffusion generated in a process in which a reaction gas or O₂gas reaches a wafer edge part and also, the CD control effect is greatly degraded and thus an etching uniformity of the edge part cannot be guaranteed.

SUMMARY OF THE INVENTION

An aspect of exemplary embodiments of the present invention is to address at least the problems and/or disadvantages and to provide at least the advantages described below. Accordingly, an aspect of exemplary embodiments of the present invention is to jet a tuning gas for plasma control adjacently to an edge part of a wafer, thereby optimizing a jet effect through the minimization of a tuning gas diffusion phenomenon and effectively controlling a CD uniformity or profile of the edge part of the wafer.
Another aspect of exemplary embodiments of the present invention is to effectively compensate an etch rate and CD difference between a center part and edge part of a wafer by installing a plurality of tuning gas jets along the edge part of the wafer in a radial shape and uniformly jetting a tuning gas to the whole edge part of the wafer.
A further aspect of exemplary embodiments of the present invention is to minimize a process failure by effectively removing a reaction by-product such as polymer generated in an edge part of a wafer and also removing organic materials, foreign materials or the like attached to an outer side surface or lower part of the edge part.
A yet another aspect of exemplary embodiments of the present invention is to remarkably improving a chip yield of an edge part by not only reducing a process time through a rapid and uniform diffusion and plasma control but also guaranteeing an etching uniformity in the whole surface of a wafer.
According to one aspect of the present invention, a gas injection system for etching profile control is provided. The system includes a top gas injector and a side gas injector. The top gas injector supplies a reaction gas at a top of a chamber. The side gas injector has a plurality of jets formed in a radial shape such that a tuning gas is simultaneously jetted in a plurality of positions along an inner circumference of the chamber, and has guidance ducts each connected and installed at one ends of the jets such that the tuning gas is jetted adjacently to an edge part of a wafer loaded inside the chamber.
The guidance duct can have a center part downward bent and formed such that its front end is positioned adjacently to an upper part of the edge part of the wafer.
The guidance duct may be installed such that its front end is adjacent to an upper part of the edge part of the wafer, and may be downward tilted such that the tuning gas is jetted at a constant angle from the outside direction of the wafer to the edge part.
A gas inlet is formed at an outer part of the side gas injector, and a distribution channel is formed in the inner part of the side gas injector such that the gas inlet communicates with the plurality of jets.
Desirably, the distribution channel is through formed in the inner part of the side gas injector to form a concentric circle with the side gas injector.
According to another aspect of the present invention, a gas injection system for etching profile control is provided. The system includes a top gas injector and a backside gas injector. The top gas injector supplies a reaction gas at a top of a chamber. The backside gas injector is out inserted and installed in an outer circumference of an upper part of an ElectroStatic Chuck (ESC) on which a wafer is loaded, and has a plurality of jets spaced and formed at an upper surface such that a tuning gas is upward jetted adjacently to an edge part of the wafer.
A gas inlet can be formed at an outer part of the backside gas injector, and a distribution channel can be formed in the inner part of the backside gas injector such that the gas inlet communicates with the plurality of jets.
A gas inlet can be formed in a lower surface of the backside gas injector, and a distribution channel can be formed in the inner part of the backside gas injector such that the gas inlet communicates with the plurality of jets, and a through-path can be formed in the ESC supporting the wafer and backside gas injector to communicate with the gas inlet.
Desirably, the distribution channel is through formed in the inner part of the backside gas injector to form a concentric circle with the backside gas injector.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects, features and advantages of the present invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings in which:

FIG. 1 is a schematic diagram illustrating a construction of an exemplary embodiment of the present invention;

FIG. 2 is a perspective diagram illustrating a side gas injector according to an exemplary embodiment of the present invention;

FIG. 3 is a cross section taken along line A-A of FIG. 2;

FIG. 4 is a schematic diagram illustrating a construction of another exemplary embodiment of the present invention;

FIG. 5 is a partial cross section of a side gas injector of an exemplary embodiment of FIG. 4;

FIG. 6 is a partial side diagram of another exemplary embodiment of the present invention;

FIG. 7 is a perspective diagram of a backside gas injector of FIG. 6; and

FIG. 8 is a partial side diagram of another exemplary embodiment of the present invention.

DESCRIPTION OF SYMBOLS OF KEY PARTS OF THE DRAWINGS


	1: chamber	10: top gas injector
	20: electrostatic chuck	25: passage
	30, 40: side gas injector
	31, 41: body part	32, 42, 52, 62: gas inlet
	33, 43, 53, 63: distribution channel
	15, 35, 45, 55, 65: jet	36, 46: guidance duct
	39, 59: hollow part	50, 60: backside gas injector
	110, 130, 135, 140, 145: arrow	W: wafer

Throughout the drawings, the same drawing reference numerals will be understood to refer to the same elements, features and structures.

DETAILED DESCRIPTION OF THE INVENTION

Exemplary embodiments of the present invention will now be described in detail with reference to the annexed drawings. In the following description, a detailed description of known functions and configurations incorporated herein has been omitted for conciseness.
FIG. 1 is a schematic diagram illustrating a construction of an exemplary embodiment of the present invention. FIG. 2 is a perspective diagram illustrating a side gas injector according to an exemplary embodiment of the present invention. FIG. 3 is a cross section taken along line A-A of FIG. 2.
As illustrated in FIG. 1, the gas injection system of the present invention includes a top gas injector 10 and a side gas injector 30.
The top gas injector 10 is installed on a top surface inside a chamber 1, and the side gas injector 30 is installed along a side surface of the chamber 1.
The chamber 1 is to provide a plasma reaction space isolated from the external in an etching process. The chamber 1 forms a sealing space of a predetermined size therein, and can be formed in various forms according to a size of a wafer (W) or a process characteristic.
An ElectroStatic Chuck (ESC) 20 loading the wafer (W) for process performance is provided at a lower part of the chamber 1. Also, an outlet (not shown) is installed to discharge out a reaction by-product such as a reaction gas, a polymer, a particle or the like.
Also, a Radio Frequency (RF) power source is installed in the chamber 1, and etches and processes a surface of the wafer (W) by plasma by electrically discharging and converting a reaction gas into a plasma state.
Commonly, a gas duct (not shown) for circulating a gas of helium (He) and the like and enabling a control of a temperature of the wafer (W), a cooling water duct (not shown) for circulating a coolant or the like can be installed in the ESC 20.
The wafer (W) is safely mounted and fixed in a horizontal state on a top of the ESC 20.
The top gas injector 10 is to jet a reaction gas into the chamber 1. Desirably, the top gas injector 10 has a plurality of jets 15 for jetting a reaction gas in a down direction and a lateral direction as indicated by arrow 110 such that the jetted reaction gas can be rapidly diffused into the chamber 1 and uniform plasma can be formed.
The top gas injector 10 can be a showerhead of a common structure in which the plurality of jets 15 are formed in several directions.
Accordingly, the top gas injector 10 connects with a separate external gas supply unit (not shown) and jets a suitable flow of reaction gas into the chamber 1.
The reaction gas jetted from the top gas injector 10 is diffused into the chamber 1 and simultaneously, is converted into the plasma state by high voltage. This plasma gets in contact with and reacts with a surface of the wafer (W), thereby etching and processing the surface of the wafer (W) into a constant pattern.
At this time, the reaction gas can be a variety of kinds of gases adaptive to respective etching process characteristics but, commonly, can be a gas of CxFx or SxFx series, hydrogen bromide (HBr), argon (Ar), oxygen (O₂), or the like. After reaction completion, the reaction gas or reaction by-product is forcibly discharged out through the outlet.
As illustrated in FIG. 1, the side gas injector 30 is installed along a sidewall of the chamber 1 and jets a tuning gas from the lateral direction of the wafer (W).
Commonly, the top gas injector 10 of the showerhead form installed at a top of the chamber 1 jets a reaction gas in a plurality of directions. However, at this time, the reaction gas cannot form uniform plasma due to a difference of the extent of diffusion in a process in which the reaction gas reaches a center part and edge part (i.e., outer part) of the wafer (W), thereby generating an etch rate and CD difference between the center part and edge part of the wafer (W), and causing not only a process failure but also greatly deteriorating a chip yield of the edge part.
Particularly, with the large-diameter trend of the wafer (W) and high integration of a semiconductor device, a process margin is reduced. Also, as a CD decreases to 30 nm or less, failure generation caused by plasma non-uniformity in the edge part greatly increases.
Accordingly, the side gas injector 30 is to precisely control the uniformity of plasma distributed in the edge part of the wafer (W) and compensate an etch rate difference and a CD difference between the center part and edge part of the wafer (W).
That is, exemplary embodiments of the present invention jet a tuning gas adjacently to the edge part of the wafer (W) and minimize diffusion in a movement process, thereby making it easy to independently control the tuning gas. Also, through this, the exemplary embodiments of the present invention can effectively control an amount of a reaction gas reaching the edge part and a plasma distribution and can improve etching non-uniformity, CD deviation, or the like of the center part and edge part of the wafer (W).
Below, the side gas injector 30 is described in detail with reference to FIGS. 2 and 3.
As illustrated in FIG. 2, the side gas injector 30 includes a body part 31 and a guidance duct 36 installed in the body part 31.
The body part 31 is installed in an outer circumference of the chamber 1 and jets a tuning gas from the lateral direction of the chamber 1. The body part 31 is formed in a panel form of a predetermined thickness, and a hollow part 39 is provided in a center part.
The body part 31 can be formed by coupling an upper plate and a lower plate of the same size with each other. The body part 31 is variously formed corresponding to a size and form of the chamber 1 and the hollow part 39 is formed corresponding to an inner circumference of the chamber 1.
At least one or more gas inlets 32 are formed in the outside inner part of the body part 31, and a plurality of jets 35 are arranged and formed at an equal interval around the hollow part 39.
A distribution channel 33 having a predetermined diameter is formed in the inner part of the body part 1.
The distribution channel 33 is provided to form a concentric circle with the hollow part 39, and is installed to communicate with the gas inlets 32 and the jets 35.
The guidance ducts 36 are installed connecting to the jets 35.
As illustrated in FIG. 1, the guidance ducts 36 are installed at an equal interval such that a tuning gas is jetted adjacently to the edge part of the wafer (W), and are installed such that their rear ends are connected to the jets 35 and their front ends are adjacent to an upper part of the edge part of the wafer (W).
Accordingly, the guidance ducts 36 are formed such that their center parts are downward bent by one step, but this does not intend to limit the scope of the present invention. The guidance ducts 36 can be formed in various forms such as a curve shape and the like such that the front ends are adjacent to the edge part of the wafer (W), and the rear ends can be connected to the jets 35 by screw coupling and the like by interposing a sealing member.
Accordingly, after the tuning gas is introduced into the gas inlet 32, the tuning gas is distributed to the jets 35 via the distribution channel 33, and is jetted to the edge part of the wafer (W) through the guidance duct 36.
The tuning gas can be CxFx series, a gas of O₂or the like.
The tuning gas is adjacently jetted to a top of the edge part of the wafer (W) and varies a density or distribution degree of plasma that is formed in the edge part by a reaction gas.
Accordingly, the side gas injector 30 jets the tuning gas adjacently to the edge part of the wafer (W) through the guidance duct 36, thereby being capable of minimizing the diffusion of gas generated in a process in which the tuning gas reaches the edge part. Also, the side gas injector 30 can precisely control a flow of the tuning gas reaching the edge part and compensate a plasma distribution difference in the center part and edge part of the wafer (W), thereby being capable of removing an etch rate, CD uniformity or profile difference between the center part and edge part of the wafer (W).
FIGS. 4 and 5 are a diagram illustrating a construction and a cross section of a side gas injector of another exemplary embodiment of the present invention, respectively. Besides jets 45 and guidance ducts 46, FIGS. 4 and 5 are the same as FIGS. 1 and 2 and thus, only a modified construction is described.
As illustrated in FIG. 5, the jets 45 are through formed in a lower part of a body part 41 of the side gas injector 40 such that the jets 45 are downward tilted at a constant angle. The jets 45 communicate at their one ends with a distribution channel 43, and communicate at the other ends with the guidance ducts 46.
The guidance ducts 46 are installed to pass through a sidewall of the chamber 1 supporting the body part 41 and communicate with the jets 45, with maintaining the same angle with the jets 45.
Like the jets 35 and the guidance ducts 36 of the exemplary embodiment of FIG. 2, the jets 45 and the guidance ducts 46 are installed in plurality in a radial shape.
Front ends of the guidance ducts 46 are installed adjacently to an edge part such that a tuning gas is jetted from the outside direction of the wafer (W) to the edge part of the wafer (W) with being tilted at a constant angle.
Accordingly, after the tuning gas is introduced through the gas inlet 42 and goes through the distribution channel 43, the tuning gas is distributed to the plurality of jets 45 and jetted on the tilt through the guidance duct 46, thereby being capable of controlling an etching uniformity in the edge part.
Another exemplary embodiment of the present invention is described in detail with reference to FIGS. 6 to 8.
FIG. 6 is a partial side diagram of another exemplary embodiment of the present invention. FIG. 7 is a perspective diagram of a backside gas injector 50. FIG. 8 is a partial side diagram of another exemplary embodiment of the present invention. Besides the side gas injector 30 of FIG. 1, this exemplary embodiment of the present invention is the same as the exemplary embodiment of FIG. 1 and thus, only a modified construction is described.
As illustrated in FIG. 6, the backside gas injector 50 upward jets a tuning gas from the lateral rear direction of a wafer (W) as indicated by arrow 135, and is out inserted and fixedly installed in an upper part of an ESC 20.
Also, the backside gas injector 50 can not only jet a tuning gas and simultaneously concentrate plasma on a top of the wafer (W) loaded on an upper part of the ESC 20 but also plays a focus ring role of preventing plasma from getting in contact with the ESC 20 and damaging the ESC 20.
Accordingly, desirably, the backside gas injector 50 is formed to have a ring shape composed of materials of silicon, quartz or the like. Also, the backside gas injector 50 can be constructed by a focus ring assembly accumulating and fixing a plurality of rings.
A plurality of jets 55 are formed in an upper part of the backside gas injector 50 such that a tuning gas can be upward jetted, and gas inlets 52 are formed in an outer circumference of the backside gas injector 50.
Here, the jets 55 are installed adjacently to an edge part of the wafer (W) such that a tuning gas is jetted adjacently to the edge part of the wafer (W). The jets 55 and the gas inlets 52 are through installed to communicate with each other through a distribution channel 53.
The distribution channel 53 is through installed in the inner part to form the same center as a hollow part 59 of FIG. 7. Lower ends of the jets 55 are installed connecting to the distribution channel 53.
Like the distribution channel 33 illustrated in FIGS. 2 and 3, the distribution channel 53 can be also manufactured dividing the backside gas injector 50 into an upper part and a lower part.
Accordingly, after the tuning gas is introduced into the gas inlet 52 as indicated by arrow 130, the tuning gas goes through the distribution channel 53 and is distributed to the plurality of jets 55, respectively. After that, the tuning gas is upward jetted as indicated by arrow 135 and affects the distribution of plasma formed in the edge part of the wafer (W), whereby a user can control a flow of the tuning gas and more precisely control an etch rate or a CD uniformity or profile of the edge part of the wafer (W).
At least one or more gas inlets 32 and 52 can be formed according to need, and are connected with a separate gas supply unit (not shown) installed in the external.
A backside gas injector 60 of FIG. 8 downward forms a gas inlet 62. Only a position of the gas inlet 62 is different from that of the backside gas injector 50 of FIG. 7 and other constructions are the same.
At least one or more gas inlets 62 are formed in down direction, and passages 25 are formed corresponding to the number of the gas inlets 62 to communicate with the gas inlets 62 in the ESC 20 supporting the backside gas injector 60.
The passage 25 of the ESC 20 is connected with a gas supply unit installed in the external.
Accordingly, a tuning gas passes through the passage 25 of the ESC 20 as indicated by arrow 140, goes through the gas inlet 62 of the backside gas injector 60, moves to a distribution channel 63, and is upward jetted through a plurality of jets 65 as indicated by arrow 145, thereby varying the distribution of plasma around an edge part of a wafer (W).
Accordingly, exemplary embodiments of the present invention jet a tuning gas adjacently to an edge part of a wafer (W) through jets 35, 45, 55, and 65 of side gas injectors 30 and 40 and backside gas injectors 50 and 60, thereby being capable of minimizing a phenomenon of tuning gas diffusion and effectively controlling the distribution of plasma of the edge part, and not only removing a reaction by-product such as a polymer generated in the edge part of the wafer (W) but also removing organic materials, foreign materials or the like through an etching effect of an outer side surface or lower part of the edge part. Also, the exemplary embodiments of the present invention install a plurality of the jets 35, 45, 55, and 65 in a radial shape along the edge part of the wafer (W), thereby uniformly jetting a tuning gas to the whole edge part and effectively compensating an etch rate or CD difference between the center part and edge part of the wafer (W), thus being capable of not only reducing a process time but also guaranteeing an etching uniformity in the whole wafer surface.
As above, exemplary embodiments of the present invention have the following effects.
Firstly, the exemplary embodiments of the present invention jet a tuning gas adjacently to an edge part of a wafer and minimize a gas diffusion phenomenon, thereby being capable of precisely controlling a CD or profile of an edge part of a wafer.
Secondly, the exemplary embodiments of the present invention rapidly remove polymer, organic materials, foreign materials or the like from the edge part of the wafer and obtain a cleaning effect, thereby being capable of minimizing a process failure.
Thirdly, the exemplary embodiments of the present invention make it possible to effectively control an etch rate or CD of the edge part through a rapid and uniform diffusion of a tuning gas and guarantee an etching uniformity in the whole wafer surface, thereby not only improving a process efficiency but also improving productivity resulting from an increase of a chip yield of the edge part.
The above exemplary embodiments of the present invention are merely described as an example only for description convenience. So, the above exemplary embodiments of the present invention do not intend to limit the scope of the claims and are applicable to all of other plasma vacuum processing equipments such as a sputter device and a Chemical Vapor Deposition (CVD) device as well.
While the invention has been shown and described with reference to a certain preferred embodiment thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.

Claims

1. A gas injection system for etching profile control, the system comprising:

a top gas injector for supplying a reaction gas at a top of a chamber; and

a side gas injector having a plurality of jets formed in a radial shape such that a tuning gas is simultaneously jetted in a plurality of positions along an inner circumference of the chamber, and having guidance ducts each connected and installed at one ends of the jets such that the tuning gas is jetted adjacently to an edge part of a wafer loaded inside the chamber.

2. The system of claim 1, wherein the guidance duct has a center part downward bent and formed such that its front end is positioned adjacently to an upper part of the edge part of the wafer.

3. The system of claim 1, wherein the guidance duct is installed such that its front end is adjacent to an upper part of the edge part of the wafer, and is downward tilted such that the tuning gas is jetted at a constant angle from the outside direction of the wafer to the edge part.

4. The system of any of claim 1, wherein a gas inlet is formed at an outer part of the side gas injector, and a distribution channel is formed in the inner part of the side gas injector such that the gas inlet communicates with the plurality of jets.

5. The system of claim 4, wherein the distribution channel is through formed in the inner part of the side gas injector to form a concentric circle with the side gas injector.

6. A gas injection system for etching profile control, the system comprising:

a top gas injector for supplying a reaction gas at a top of a chamber; and

a backside gas injector out inserted and installed in an outer circumference of an upper part of an ElectroStatic Chuck (ESC) on which a wafer is loaded, and having a plurality of jets spaced and formed at an upper surface such that a tuning gas is upward jetted adjacently to an edge part of the wafer.

7. The system of claim 6, wherein a gas inlet is formed at an outer part of the backside gas injector, and a distribution channel is formed in the inner part of the backside gas injector such that the gas inlet communicates with the plurality of jets.

8. The system of claim 6, wherein a gas inlet is formed in a lower surface of the backside gas injector, and a distribution channel is formed in the inner part of the backside gas injector such that the gas inlet communicates with the plurality of jets, and a through-path is formed in the ESC supporting the wafer and backside gas injector to communicate with the gas inlet.

9. The system of claim 7, wherein the distribution channel is through formed in the inner part of the backside gas injector to form a concentric circle with the backside gas injector.