CN117415722A - Chemical mechanical polishing system and polishing method - Google Patents

Abstract

The invention discloses a chemical mechanical polishing system and a polishing method, wherein the chemical mechanical polishing system comprises: a front unit; a polishing unit comprising at least one sub-polishing unit; a cleaning unit for cleaning the polished wafer; a transverse transmission mechanism is arranged between the polishing unit and the cleaning unit, and the end part of the transverse transmission mechanism is adjacent to the front unit, so that the wafer is transmitted between the front unit and the polishing unit and between the cleaning unit and the front unit; the sub-polishing unit includes a polishing platen and a polishing module configured with at least two carrier heads for carrying wafers to polish the wafers on adjacent polishing platens.

Description

Chemical mechanical polishing system and polishing method

Technical Field

The invention belongs to the technical field of chemical mechanical polishing, and particularly relates to a chemical mechanical polishing system and a polishing method.

Background

The integrated circuit industry is the core of the information technology industry and plays a key role in the process of converting and upgrading the boosting manufacturing industry into digital and intelligent conversion. The chip is a carrier of an integrated circuit, and the chip manufacturing involves the process flows of integrated circuit design, wafer manufacturing, wafer processing, electrical measurement, dicing packaging, testing, and the like. Among them, chemical mechanical polishing (Chemical Mechanical Polishing, CMP) is one of five main core processes in the wafer manufacturing process.

CMP is a globally planarized ultra-precise surface processing technique that typically requires polishing and cleaning of the wafer by means of a CMP system to achieve "dry in dry out" of the wafer to obtain a wafer that meets process requirements. CMP systems typically include a head unit, a polishing unit, and a cleaning unit, typically disposed between the head unit and the polishing unit.

In order to realize the transmission of the wafer, a plurality of buffer mechanisms are required to be arranged in the cleaning unit, so that the number of times of clamping the wafer by the manipulator is increased, and the transmission efficiency of the wafer is affected; meanwhile, the wafer transmission route is longer, so that the time for exposing the wafer outside is prolonged, and secondary pollution is easy to cause; in addition, the buffer mechanism is arranged on the cleaning unit, so that the working space of operators is reduced, and the daily maintenance of equipment is not facilitated.

Disclosure of Invention

The embodiment of the invention provides a chemical mechanical polishing system and a polishing method, which aim to at least solve one of the technical problems in the prior art.

A first aspect of an embodiment of the present invention provides a chemical mechanical polishing system comprising:

a front unit;

a polishing unit comprising at least one sub-polishing unit;

a cleaning unit for cleaning the polished wafer;

a transverse transmission mechanism is arranged between the polishing unit and the cleaning unit, and the end part of the transverse transmission mechanism is adjacent to the front unit, so that the wafer is transmitted between the front unit and the polishing unit and between the cleaning unit and the front unit;

the sub-polishing unit includes a polishing platen and a polishing module configured with at least two carrier heads for carrying wafers to polish the wafers on adjacent polishing platens.

In some embodiments, the sub-polishing unit further comprises a handling assembly disposed adjacent to the transport mechanism and between adjacent polishing discs.

In some embodiments, the transport mechanism includes a first buffer assembly and a second buffer assembly, both disposed at a lateral spacing; the first buffer assembly is arranged close to the front unit so as to temporarily store wafers to be polished and/or cleaned; the second buffer assembly is arranged between the polishing unit and the cleaning unit to temporarily store the polished wafer.

In some embodiments, the transfer mechanism further comprises a polishing transfer robot disposed between the first cache assembly and the second cache assembly; the polishing transfer robot is capable of moving laterally to transfer a wafer.

In some embodiments, the polishing module comprises a fixed frame, under which a carrier head is arranged; the fixing frame can rotate along the central axis to change the phase of the bearing head.

In some embodiments, the mount is capable of moving in a longitudinal direction such that the carrier head moves in the longitudinal direction during polishing.

In some embodiments, the cleaning unit includes a plurality of cleaning modules vertically stacked to form a cleaning module; a cleaning and conveying manipulator is arranged between the adjacent cleaning modules.

In some embodiments, the cleaning module is a single chamber cleaning apparatus that cleans and/or dries wafers in a horizontal manner.

In some embodiments, the cleaning transfer robot is disposed adjacent to the transfer mechanism to transfer polished wafers into the cleaning module.

A second aspect of an embodiment of the present invention provides a polishing method using the chemical mechanical polishing system described above, comprising:

s1, transmitting a wafer of a front unit to a first buffer assembly, and transmitting the wafer of the first buffer assembly to a loading and unloading assembly by a polishing transmission manipulator;

s2, after the carrier head of the polishing module loads the wafer from the loading and unloading assembly, the fixing frame rotates around the central axis, and other carrier heads of the polishing module continue to load the wafer;

s3, the bearing head loaded with the wafer is pressed against the polishing pad above the polishing disk so as to implement chemical mechanical polishing;

s4, unloading the polished wafer to a loading and unloading assembly, and conveying the polished wafer to a second buffer assembly by a polishing conveying manipulator;

s5, the cleaning and conveying mechanical arm conveys the wafer of the second buffer assembly to the cleaning unit, then the surface of the wafer is processed, and the wafer after the post-processing is conveyed to the front unit.

The beneficial effects of the invention include:

a. a transmission mechanism parallel to the length direction of the CMP is arranged between the polishing unit and the cleaning unit, and the transmission mechanism is adjacent to the front unit, so that the number of turnover times of wafer transmission is reduced, and the wafer transmission efficiency is improved;

b. the polishing module is provided with at least two bearing heads which can polish the wafer at the same time on the adjacent polishing disk so as to improve the processing efficiency of the polishing system;

c. the cleaning modules of the cleaning units are vertically stacked, so that space occupation is reduced, the overall size of the polishing system is controlled, and the layout of each functional unit is more reasonable.

Drawings

The advantages of the present invention will become more apparent and more readily appreciated from the detailed description given in conjunction with the following drawings, which are meant to be illustrative only and not limiting of the scope of the invention, wherein:

FIG. 1 is a schematic diagram of a chemical mechanical polishing system provided in accordance with one embodiment of the present invention;

FIG. 2 is a schematic diagram of a first cache module according to an embodiment of the present invention;

FIG. 3 is a schematic view of a first sub-polishing unit according to one embodiment of the present invention;

FIG. 4 is a schematic diagram of a cleaning module according to an embodiment of the invention;

fig. 5 is a flowchart of a polishing method according to an embodiment of the present invention.

Detailed Description

The following describes the technical scheme of the present invention in detail with reference to specific embodiments and drawings thereof. The examples described herein are specific embodiments of the present invention for illustrating the concept of the present invention; the description is intended to be illustrative and exemplary in nature and should not be construed as limiting the scope of the invention in its aspects. In addition to the embodiments described herein, those skilled in the art can adopt other obvious solutions based on the disclosure of the claims of the present application and the specification thereof, including those adopting any obvious substitutions and modifications to the embodiments described herein.

The drawings in the present specification are schematic views, which assist in explaining the concept of the present invention, and schematically show the shapes of the respective parts and their interrelationships. It should be understood that for the purpose of clearly showing the structure of various parts of embodiments of the present invention, the drawings are not drawn to the same scale and like reference numerals are used to designate like parts in the drawings.

In the present invention, "chemical mechanical polishing (Chemical Mechanical Polishing, CMP)" is also referred to as "chemical mechanical planarization (Chemical Mechanical Planarization, CMP)", and Wafer (W) is also referred to as Substrate (Substrate), the meaning and actual function are equivalent. The term "comprising" and its like are to be construed as open-ended, i.e., including, but not limited to. The term "based on" should be understood as "based at least in part on". The term "one embodiment" or "the embodiment" should be understood as "at least one embodiment". The terms "first," "second," and the like, may refer to different or the same object and are used solely to distinguish one from another without implying a particular spatial order, temporal order, order of importance, etc. of the referenced objects. In some embodiments, the values, processes, selected items, determined items, devices, means, parts, components, etc. are referred to as "best," "lowest," "highest," "smallest," "largest," etc. It should be understood that such description is intended to indicate that a selection may be made among many available options of functionality, and that such selection need not be better, lower, higher, smaller, larger, or otherwise preferred in further or all respects than other selections.

Embodiments of the present disclosure generally relate to Chemical Mechanical Polishing (CMP) systems used in the semiconductor device manufacturing industry. When in chemical mechanical polishing, polishing solution composed of submicron or nanometer abrasive particles and chemical solution flows between a wafer and a polishing pad, the polishing solution is uniformly distributed under the action of transmission and rotation centrifugal force of the polishing pad to form a layer of liquid film between the wafer and the polishing pad, chemical components in the liquid react with the wafer to convert insoluble substances into soluble substances, then the chemical reactants are removed from the surface of the wafer through micro-mechanical friction of the abrasive particles and dissolved in the flowing liquid to be taken away, namely surface materials are removed in the alternating process of chemical film forming and mechanical film removing to realize surface planarization treatment, so that the aim of global planarization is achieved.

FIG. 1 is a schematic diagram of a chemical mechanical polishing system 100 according to one embodiment of the present invention, comprising:

a front unit 10, abbreviated as EFEM (Equipment Front End Module), for storing wafers to be polished and polished;

a polishing unit 20 including at least one sub-polishing unit; in the embodiment shown in fig. 1, the polishing unit 20 comprises a first sub-polishing unit 20A and a second sub-polishing unit 20B, both arranged in a lateral direction of the chemical mechanical polishing system 100; it will be appreciated that the polishing elements 20 may also include other numbers of sub-polishing elements;

and a cleaning unit 30 for cleaning the polished wafer to remove the residual contaminants on the wafer surface and obtain a clean wafer.

Further, a lateral transfer mechanism 40 is provided between the polishing unit 20 and the cleaning unit 30, and an end of the transfer mechanism 40 abuts against the front unit 10, so that the wafer is transferred between the front unit 10 and the polishing unit 20, and between the cleaning unit 30 and the front unit 10. The term "lateral" as used herein refers to the lengthwise direction of the CMP system and the term "longitudinal" refers to the widthwise direction of the CMP system.

In fig. 1, the front unit 10 includes four front opening unified pods (Front Opening Unified Pod, FOUPs) for storing wafers and a front robot. The front robot is disposed at one side of the front opening unified pod, and is used for transferring wafers between the front unit 10 and the transfer mechanism 40 and the cleaning unit 30. The front-end robot is typically configured with upper and lower clamping jaws to grasp the polished wafer and/or wafer to be polished, respectively, to avoid cross-contamination during wafer clamping.

In the present invention, the sub-polishing unit includes a polishing platen 21 and a polishing module 22, wherein the polishing module 22 is provided with at least two carrier heads 23 for loading wafers to be polished to polish the wafers on the adjacent polishing platen 21. In fig. 1, the polishing module 22 is provided with three carrier heads 23 to polish two wafers simultaneously on adjacent polishing disks 21.

A polishing pad is disposed above the polishing disk 21, and a polishing liquid is disposed above the polishing pad. Meanwhile, the sub-polishing unit further includes a conditioner and a liquid supply arm, which are not shown; wherein the conditioner is used for conditioning the surface of the polishing pad to maintain the polishing characteristics of the polishing pad; the liquid supply arm is used for supplying polishing liquid to the polishing pad. In chemical mechanical polishing, a polishing liquid is disposed between the polishing pad and the wafer to effect removal of material under chemical and mechanical action.

Further, the sub-polishing unit includes a handling assembly 24 shown in fig. 3, the handling assembly 24 being disposed adjacent to the transport mechanism 40, and the handling assembly 24 being located between adjacent polishing disks 21. The handling assembly 24, also referred to as a load cup, is capable of interacting with the robot and carrier head 23 to facilitate wafer transfer.

In the embodiment shown in fig. 1, the first sub-polishing unit 20A and the second sub-polishing unit 20B are each provided with a pair of polishing disks 21, wherein a loading/unloading assembly 24 is provided between adjacent polishing disks 21.

In the present invention, the transmission mechanism 40 includes a first buffer assembly 41 and a second buffer assembly 42, which are disposed at intervals along the lateral direction, so as to temporarily store wafers in different positions and different states.

Further, the first buffer assembly 41 is disposed adjacent to the front unit 10 to temporarily store the wafer to be polished and/or cleaned; the second buffer assembly 42 is disposed between the polishing unit 20 and the cleaning unit 30 to temporarily store polished wafers.

The transfer mechanism 40 further includes a polishing transfer robot 43 disposed between the first buffer assembly 41 and the second buffer assembly 42, which is capable of moving along the length direction of the CMP system to transfer the wafer.

Specifically, the conveying mechanism 40 further includes a slide rail 44 shown in fig. 1, the slide rail 44 is transversely disposed on a device base of the CMP system, and the polishing conveying manipulator 43 is slidably connected to the slide rail 44, so that the polishing conveying manipulator 43 can move along the length direction of the slide rail 44, so as to change the position of the wafer clamped by the polishing conveying manipulator 43, and realize the conveying of the wafer. In this embodiment, the polishing transfer robot 43 is laterally hung on the slide rail 44.

In the embodiment shown in fig. 1, the first buffer assembly 41 and the second buffer assembly 42 are respectively disposed at two ends of the slide rail 44, and the clamping claws on the polishing transfer robot 43 can cover the first buffer assembly 41 and the second buffer assembly 42, so as to place the wafer in the buffer assemblies and temporarily store the wafer.

In the present invention, the first buffer unit 41 and the second buffer unit 42 are similar in structure, and the first buffer unit 41 shown in fig. 2 is described herein; in order to embody the internal structure of the buffer assembly, the upper protective cover is removed.

Specifically, the first buffer assembly 41 includes at least one support assembly including a plurality of support columns 41a, and the plurality of support columns 41a can horizontally support the wafer to temporarily hold the wafer on the first buffer assembly 41.

In order to increase the number of wafers accommodated in the buffer assembly, a plurality of support assemblies may be configured for the first buffer assembly 41, and the support assemblies are stacked in a vertical direction to reduce occupation of a horizontal space of the CMP system.

In the embodiment shown in fig. 1, the first buffer assembly 41 and the second buffer assembly 42 are relatively fixed, and the polishing transfer robot 43 disposed therebetween can move in a lateral direction so as to take and place wafers.

As a variation of this embodiment, the first buffer assembly 41 and/or the second buffer assembly 42 may move in a lateral direction, and the polishing transfer robot 43 is disposed adjacent to the polishing disk 21, so as to omit the configuration of the slide rail 44, and avoid the influence on the reliability of the wafer transfer caused by insufficient stability of the slide rail 44 that is fixed by side hanging.

As an embodiment of the present invention, the polishing module 22 includes a fixing frame 22a, as shown in fig. 3, a carrier head 23 is disposed below the fixing frame 22 a; the holder 22a can be rotated along the central axis to change the phase of the carrier head 23. Specifically, when the polishing module 22 loads a wafer from the loading and unloading assembly 24, the fixing frame 22a rotates around its central axis, so that the carrier head 23 below it is aligned with the loading assembly 24, and the carrier head 23 loads the wafer to be polished placed above the loading and unloading assembly 24.

Further, the polishing module 22 further includes a longitudinal moving mechanism, not shown, which can drive the fixing frame 22a to move longitudinally, so that the carrier head 23 moves longitudinally during polishing. Specifically, after the carrier head 23 on the fixed frame 22a loads the wafer, the fixed frame 22a moves toward the direction of the polishing disk 21, so that the wafer moves above the polishing disk 21; then, the wafer is pressed against the polishing pad above the polishing platen 21 by the elastic membrane on the carrier head 23, and at the same time, the liquid supply arm supplies the polishing liquid toward the polishing pad to perform the chemical mechanical polishing.

In the polishing process, the fixing frame 22a moves back and forth along the longitudinal direction in a small amplitude so as to change the contact area between the wafer and the polishing pad, so that the polishing rate of each area of the wafer is approximately the same, and further, the wafer meeting the process requirements is obtained.

In the embodiment shown in fig. 1, the cleaning unit 30 includes a plurality of cleaning modules 30A, and the cleaning modules 30A are vertically stacked to form a cleaning module (shown in fig. 4); the cleaning and conveying manipulators 50 are arranged between the adjacent cleaning modules, the cleaning and conveying manipulators 50 can convey the wafers between the adjacent cleaning modules, then residual particles on the surfaces of the wafers are removed according to the cleaning process sequence, and finally, the water film on the surfaces of the wafers is peeled off, so that clean and dry wafers are obtained.

Further, the cleaning module 30A is a single chamber cleaning apparatus that cleans and/or dries the wafer in a horizontal manner.

It is understood that the end of the polishing unit 30 near the front unit 10 may also be configured with a lift drying module or a spin drying module to obtain a wafer with a desired cleanliness according to the wafer processing requirements.

In fig. 4, an inlet 30A-1 is provided on a side of the cleaning module 30A so that the clamping claws of the cleaning and transporting robot 50 can carry in or out a wafer from one side of the cleaning module 30A via the inlet 30A-1.

In the invention, the cleaning modules 30A are vertically stacked, so that the upper space of the equipment is fully utilized, the space occupation in the horizontal direction is reduced, the volume of the cleaning unit 30 is reduced, and the flexibility of the module layout is improved.

In the embodiment shown in fig. 1, a cleaning transfer robot 50 is disposed adjacent to the second buffer assembly 42 so that the cleaning transfer robot 50 transfers polished wafers to the cleaning module 30A of the cleaning unit 30. That is, at least one cleaning transfer robot 50 is disposed at an end of the transfer mechanism 40 remote from the front unit 10 to reliably transfer the wafer between the polishing unit 20 and the cleaning unit 30.

In the present invention, the inlet and outlet 30A-1 is configured on both sides of the cleaning module 30A disposed adjacent to the front unit 10, so that the front manipulator of the front unit 10 can directly transfer the dried wafer to the front open type wafer transfer box of the front unit 10, thereby further shortening the transfer path of the wafer and reducing the probability of secondary pollution.

Also disclosed is a polishing method using the chemical mechanical polishing system 100 described above, FIG. 5 being a flow chart of the polishing method, the polishing method comprising:

s1, transmitting the wafer of the front unit 10 to a first buffer assembly 41, and transmitting the wafer of the first buffer assembly 41 to a loading and unloading assembly 24 by a polishing transmission manipulator 43;

specifically, the front robot of the front unit 10 transfers the wafers in the front opening unified pod to the first buffer module 41, and then the polishing transfer robot 43 transfers the wafers in the first buffer module 41 to the loading/unloading module 24 for loading by the loading head 23.

S2, after the carrier head 23 of the polishing module 22 loads the wafer from the loading and unloading assembly 24, the fixing frame 22a rotates around the central axis, and other carrier heads 23 of the polishing module 22 continue to load the wafer;

in this step, during the rotation of the fixing frame 22a around the central axis, the polishing transfer robot 43 transfers the wafer of the first buffer component 41 to the handling component 24, so as to reduce the waiting time of the process and improve the working efficiency.

S3, the carrying head 23 loaded with the wafer is pressed against the polishing pad above the polishing disk 21 to carry out chemical mechanical polishing;

in the wafer polishing process, the liquid supply arm swings to the upper side of the polishing disc 21 so as to supply polishing liquid at a fixed position, so that sufficient polishing liquid is guaranteed to enter between the wafer and the polishing pad, and meanwhile unused polishing liquid is prevented from being centrifugally thrown out, so that the manufacturing cost of the wafer is controlled, and the polishing quality of the wafer is guaranteed.

S4, unloading the polished wafer to the loading and unloading assembly 24, and conveying the polished wafer to the second buffer assembly 42 by the polishing conveying mechanical arm 43;

s5, the cleaning and conveying mechanical arm 50 conveys the wafer of the second buffer assembly 42 to the cleaning unit 30, further post-processes the surface of the wafer, and the wafer after post-processing is conveyed to the front unit 10.

"post-treatment" in the present invention refers generally to the surface treatment of a wafer, and in particular to the cleaning and/or drying of the wafer surface.

In this step, the cleaning transfer robot 50 can move vertically to pick and place wafers between the vertically stacked cleaning modules 30A.

In the present invention, the wafer after finishing the post-processing may be directly grasped by the front robot of the front unit 10 and then placed in the front opening unified pod. In some embodiments, the wafers after finishing the post-processing are also pre-placed in the first buffer assembly 41, and then transferred to the front opening unified pod by the front robot to adjust the tact time, so as to avoid the excessive stacking of the wafers at a certain station.

While embodiments of the present invention have been shown and described, it will be understood by those of ordinary skill in the art that: many changes, modifications, substitutions and variations may be made to the embodiments without departing from the spirit and principles of the invention, the scope of which is defined by the claims and their equivalents.

Claims (10)

1. A chemical mechanical polishing system comprising:

a front unit;

a polishing unit comprising at least one sub-polishing unit;

a cleaning unit for cleaning the polished wafer;

a transverse transmission mechanism is arranged between the polishing unit and the cleaning unit, and the end part of the transverse transmission mechanism is adjacent to the front unit, so that the wafer is transmitted between the front unit and the polishing unit and between the cleaning unit and the front unit;

the sub-polishing unit includes a polishing platen and a polishing module configured with at least two carrier heads for carrying wafers to polish the wafers on adjacent polishing platens.

2. The chemical mechanical polishing system of claim 1 wherein the sub-polishing unit further comprises a handling assembly disposed adjacent the transport mechanism and between adjacent polishing disks.

3. The chemical mechanical polishing system of claim 1, wherein the transport mechanism comprises a first buffer assembly and a second buffer assembly, the first buffer assembly and the second buffer assembly being laterally spaced apart; the first buffer assembly is arranged close to the front unit so as to temporarily store wafers to be polished and/or cleaned; the second buffer assembly is arranged between the polishing unit and the cleaning unit to temporarily store the polished wafer.

4. The chemical mechanical polishing system of claim 3, wherein the transfer mechanism further comprises a polishing transfer robot disposed between the first buffer assembly and the second buffer assembly; the polishing transfer robot is capable of moving laterally to transfer a wafer.

5. The chemical mechanical polishing system of claim 1, wherein the polishing module comprises a fixture with a carrier head disposed below; the fixing frame can rotate along the central axis to change the phase of the bearing head.

6. A chemical mechanical polishing system according to claim 5, wherein the mount is capable of moving in a longitudinal direction such that the carrier head moves in the longitudinal direction during polishing.

7. The chemical mechanical polishing system of claim 1, wherein the cleaning unit comprises a plurality of cleaning modules vertically stacked to form a cleaning module; a cleaning and conveying manipulator is arranged between the adjacent cleaning modules.

8. The chemical mechanical polishing system of claim 7, wherein the cleaning module is a single chamber cleaning apparatus that cleans and/or dries wafers in a horizontal manner.

9. The chemical mechanical polishing system of claim 7 wherein the cleaning transfer robot is disposed adjacent to the transfer mechanism to transfer polished wafers into the cleaning module.

10. A polishing method characterized by using the chemical mechanical polishing system according to any one of claims 1 to 9, comprising:

s1, transmitting a wafer of a front unit to a first buffer assembly, and transmitting the wafer of the first buffer assembly to a loading and unloading assembly by a polishing transmission manipulator;

s2, after the carrier head of the polishing module loads the wafer from the loading and unloading assembly, the fixing frame rotates around the central axis, and other carrier heads of the polishing module continue to load the wafer;

s3, the bearing head loaded with the wafer is pressed against the polishing pad above the polishing disk so as to implement chemical mechanical polishing;

s4, unloading the polished wafer to a loading and unloading assembly, and conveying the polished wafer to a second buffer assembly by a polishing conveying manipulator;

s5, the cleaning and conveying mechanical arm conveys the wafer of the second buffer assembly to the cleaning unit, then the surface of the wafer is processed, and the wafer after the post-processing is conveyed to the front unit.