CN-122029004-A - Polishing head with decoupling film position control

Abstract

The chemical mechanical polishing system and method includes loading a substrate into a carrier head having a housing with an upper carrier body and a lower carrier body and a membrane assembly below the lower carrier body. The space between the lower carrier body and the membrane assembly defines a pressurizable chamber, the distance from the sensor in the lower carrier body to the membrane assembly is measured, and the pressure in the pressurizable chamber is controlled based on the measured distance to maintain a consistent total downforce on the membrane assembly as the distance between the sensor and the membrane assembly changes.

Inventors

• A. J. nagenggast
• W. R. Fernando
• WU ZHENGXUN
• CHEN KUNXIANG
• S.M. Suniga
• FUJIKAWA TAKASHI
• J. Gurusami
• E.A. Mikhailichenko
• E.LIU
• ZHANG HUANBO

Assignees

• 应用材料公司

Dates

Publication Date

20260512

Application Date

20240926

Priority Date

20231003

Claims (19)

1. 1. A chemical mechanical polishing system comprising: A pressing plate; a carrier head, the carrier head comprising A housing for attachment to a drive shaft, wherein the housing comprises an upper carrier body and a lower carrier body vertically movable relative to the upper carrier body, A first flexible seal forming a first pressurizable chamber between the upper carrier body and the lower carrier body, A membrane assembly disposed below the lower carrier body, the membrane assembly including a membrane support and a flexible membrane secured to the membrane support to define a plurality of pressurizable lower chambers, the flexible membrane having a lower surface providing a substrate mounting surface, and A second flexible seal forming a second pressurizable chamber between the upper carrier body and the lower carrier body, an A controller configured to receive a signal from a sensor arranged to generate data indicative of pressure in the second pressurizable chamber and configured to control a pressure source to pressurize the second pressurizable chamber based on the signal.
2. 2. The system of claim 1, the sensor contained in the housing, the sensor configured to measure a distance from the sensor to the membrane assembly.
3. 3. The system of claim 2, comprising the sensor configured in the lower carrier body and configured to generate the signal based on a distance between the lower carrier body and the membrane support.
4. 4. A system according to claim 3, wherein the sensor is mounted on the lower carrier body.
5. 5. The system of claim 4, wherein the lower carrier body is vertically movable relative to the upper carrier body.
6. 6. The system of claim 2, wherein the sensor is an eddy current sensor, a radar sensor, a laser sensor, or an ultrasonic sensor.
7. 7. The system of claim 1, wherein the controller is configured to decrease the pressure in the pressurizable chamber to offset the pressure increased by the flexible connection.
8. 8. The system of claim 1, further comprising a retaining ring coupled to the lower carrier body, wherein wear on the retaining ring results in the distance being reduced.
9. 9. The system of claim 1, wherein the controller is configured to vent the second pressurizable chamber to atmosphere to allow the membrane assembly to rest on the polishing pad for generating the signal from the sensor.
10. 10. The system of claim 1, wherein the controller is configured to pressurize the second pressurizable chamber to press the membrane assembly against the polishing pad for generating the signal from the sensor.
11. 11. The system of claim 1, wherein the carrier head comprises a flexible connection connecting the membrane support to the lower carrier body, the flexible connection extending through the second pressurizable chamber.
12. 12. The system of claim 11, wherein a first portion of the second pressurizable chamber above the flexible connection is fluidly connected to a second portion of the second pressurizable chamber below the flexible connection.
13. 13. The system of claim 12, wherein the flexible connection is sufficiently rigid to horizontally center the membrane assembly within the housing.
14. 14. The system of claim 12, wherein the flexible connection has sufficient rigidity to vertically center the membrane assembly within the housing.
15. 15. A method for chemical mechanical polishing comprising the steps of: Loading a substrate into a carrier head, the carrier head having a housing with an upper carrier body and a lower carrier body, and a membrane assembly below the lower carrier body, wherein a space between the lower carrier body and the membrane assembly defines a pressurizable chamber; measuring a distance from a sensor in the lower carrier body to the membrane assembly, and Controlling the pressure in the pressurizable chamber based on the measured distance, wherein the step of controlling the pressure in the pressurizable chamber includes the step of maintaining a consistent total downforce on the membrane assembly as the distance between the sensor and the membrane assembly changes.
16. 16. The method of claim 15, wherein the step of controlling the pressure in the pressurizable chamber includes the step of compensating for changes in the load on the membrane assembly based on wear of a retaining ring.
17. 17. The method of claim 15, comprising the step of venting the second pressurizable chamber to atmosphere to allow the membrane assembly to rest on the polishing pad for measuring the distance.
18. 18. The method of claim 15, comprising the step of pressurizing the second pressurizable chamber to press the membrane assembly against the polishing pad to produce a measurement of the distance.
19. 19. The method of claim 15 including the step of reducing the pressure in the pressurizable chamber as the measured distance decreases.

Description

Polishing head with decoupling film position control Technical Field The present disclosure relates to a carrier head for use in Chemical Mechanical Polishing (CMP). Background Integrated circuits are typically formed on a substrate by sequentially depositing conductive, semiconductive, or insulative layers over a semiconductor wafer. Various fabrication processes require planarization of layers on a substrate. For example, one fabrication step involves depositing a fill layer on a non-planar surface and then planarizing the fill layer. For some applications, the fill layer is planarized until the top surface of the patterned layer is exposed. For example, a metal layer may be deposited on the patterned insulating layer to fill the trenches and holes in the insulating layer. After planarization, the trenches and the remaining portions of the metal in the holes of the patterned layer form vias, plugs, and lines to provide conductive paths between thin film circuits on the substrate. As another example, a dielectric layer may be deposited over the patterned conductive layer and then planarized to enable subsequent photolithography steps. Chemical Mechanical Polishing (CMP) is a well-known planarization method. Such planarization methods typically require the substrate to be mounted on a carrier head. The exposed surface of the substrate is typically placed against a rotating polishing pad. The carrier head provides a controllable load on the substrate to urge the substrate against the polishing pad. Polishing slurry containing abrasive particles is typically supplied to the surface of the polishing pad. Disclosure of Invention In one aspect, a carrier head for chemical mechanical polishing includes a housing for attachment to a drive shaft, a membrane assembly disposed below a lower carrier body, and a flexible connection. The membrane assembly includes a membrane support and a flexible membrane secured to the membrane support to define a plurality of pressurizable lower chambers, wherein the flexible membrane has a lower surface that provides a substrate mounting surface. The flexible seal forms a pressurizable upper chamber between the housing and the membrane support. A flexible connection connects the membrane support to the housing, and the flexible connection extends through the pressurizable upper chamber. In another aspect, a chemical mechanical polishing system includes a platen, a carrier head, and a controller. The carrier head includes a housing for attachment to the drive shaft, and the housing includes an upper carrier body and a lower carrier body vertically movable relative to the upper carrier body. The first flexible seal forms a first pressurizable chamber between the upper carrier body and the lower carrier body. A membrane assembly is disposed below the lower carrier body, the membrane assembly including a membrane support and a flexible membrane secured to the membrane support to define a plurality of pressurizable lower chambers. The flexible film has a lower surface that provides a substrate mounting surface. The second flexible seal forms a second pressurizable chamber between the upper carrier body and the lower carrier body. The controller is configured to receive a signal from a sensor arranged to generate data indicative of a pressure in the second pressurizable chamber and configured to control the pressure source to pressurize the second pressurizable chamber based on the signal. In another aspect, a method for chemical mechanical polishing includes loading a substrate into a carrier head having a housing with an upper carrier body and a lower carrier body, and a membrane assembly below the lower carrier body, wherein a space between the lower carrier body and the membrane assembly defines a pressurizable chamber, measuring a distance from a sensor in the lower carrier body to the membrane assembly, and controlling a pressure in the pressurizable chamber based on the measured distance. Controlling the pressure in the pressurizable chamber includes the step of maintaining a consistent total downforce on the membrane assembly as the distance between the sensor and the membrane assembly changes. Advantages may include, but are not limited to, the following. The sensor may detect a change in the distance between the carrier body and the membrane assembly. Such a change in distance may occur even if the chamber pressure is unchanged, for example, due to wear of the retaining ring. The controller may reduce the pressure in the chamber above the membrane assembly to maintain a consistent load on the substrate during multiple polishing operations, thereby improving wafer-to-wafer uniformity. The vertical position of the membrane assembly can be changed without skewing the pressure distribution across the membrane. The details of one or more implementations are set forth in the accompanying drawings and the description below. Other aspects, features, and advantages will be apparent from