Adaptive endpoint method for pad life effect on chemical mechanical polishing

Patent metadata

Field	Value
Publication number	US-9333619-B2
Application number	US-201313758658-A
Country	US
Kind code	B2
Filing date	Feb 4, 2013
Priority date	Mar 10, 2011
Publication date	May 10, 2016
Grant date	May 10, 2016

Abstract

The present disclosure provides a chemical mechanical polishing (CMP) system. The CMP system includes a pad designed for wafer polishing, a motor driver coupled with the pad and designed to drive the pad during the wafer polishing, and a controller coupled with the motor driver and designed to control the motor driver. The CMP system further includes an in-situ rate monitor designed to collect polishing data from a wafer on the pad, determine CMP endpoint based on a life stage of the pad, and provide the CMP endpoint to the controller.

First claim

What is claimed is:

1. A chemical mechanical polishing (CMP) system, comprising:
a pad designed for wafer polishing;
a motor driver coupled with the pad and designed to drive the pad during the wafer polishing;
a controller coupled with the motor driver and designed to control the motor driver; and
an in-situ rate monitor including a signal module designed to extract a polishing signal during the wafer polishing, wherein the in-situ rate monitor is designed to amplify the polishing signal according to a life stage of the pad, determine CMP endpoint based on the life stage of the pad, and provide the CMP endpoint to the controller.

2. The CMP system of claim 1 , wherein the in-situ rate monitor includes:
a window module for defining and applying multiple endpoint windows with respective window widths; and
an endpoint module for determining the CMP endpoint by applying one of the multiple endpoint windows to the polishing signal according to the life stage of the pad.

3. The CMP system of claim 1 , further comprising another pad for wafer polishing and coupled with the in-situ rate monitor.

4. A chemical mechanical polishing (CMP) system, comprising:
a polishing pad configured to polish a wafer;
a motor driver coupled with the polishing pad and configured to drive the polishing pad during wafer polishing;
an in-situ rate monitor configured to define a time region of pad life for the polishing pad and configured to assign a ladder coefficient to the polishing pad according to the time region of pad life; and
a controller coupled with the motor driver and in-situ rate monitor and configured to control the motor driver to apply a CMP process to the wafer positioned on the polishing pad and control the motor driver to end the CMP process at an endpoint according to the time region of pad life for the polishing pad.

5. The CMP system of claim 4 , wherein the in-situ rate monitor is further configured to determine the endpoint using an endpoint window having a window width particular to the time region of the polishing pad.

6. The CMP system of claim 4 , wherein the in-situ rate monitor is further configured to determine whether the polishing pad is in the time region based on a level of a polishing signal being applied during the CMP process to the wafer.

7. The CMP system of claim 6 , wherein the in-situ rate monitor is further configured to associate an endpoint window to the polishing signal according to the time region, the endpoint window having a width particular to the time region of the polishing pad.

8. A chemical mechanical polishing (CMP) system, comprising:
a polishing pad configured to polish a wafer;
a motor driver coupled with the polishing pad and configured to drive the polishing pad during wafer polishing;
an in-situ rate monitor configured to:
define a plurality of time regions of pad life for the polishing pad;
assign a ladder coefficient to the polishing pad according to the plurality of time regions of pad life;
define a plurality of endpoint windows to the plurality of time regions, respectively, according to pad life effect;
determine a time region of a polishing signal of the wafer based on the ladder coefficient; and
associate one of the endpoint windows to the polishing signal according to the time region; and

a controller coupled with the motor driver and in-situ rate monitor and configured to control the motor driver to apply a CMP process to the wafer positioned on the polishing pad and control the motor driver to end the CMP process at an endpoint determined by the endpoint window associated with the polishing signal.

9. The CMP system of claim 8 , wherein the in-situ rate monitor is further configured to, before an end of the CMP process, determine the endpoint by fitting the endpoint window to a portion of the polishing signal.

10. The CMP system of claim 8 , wherein the polishing signal is a signal from the wafer multiplied by the ladder coefficient within the time region.

11. The CMP system of claim 8 , wherein the in-situ rate monitor is further configured to
define an upper limit and a lower limit of the polishing signal relative to the time region and determine that the polishing signal is associated with the time region if a flat portion of the polishing signal is within a range between the upper limit and the lower limit.

12. The CMP system of claim 8 , wherein the in-situ rate monitor is further configured to define a plurality of window widths corresponding to the plurality of endpoint windows, respectively.

13. The CMP system of claim 8 , wherein the in-situ rate monitor is further configured to define the ladder coefficient with a plurality of gain levels corresponding to the plurality of time regions of pad life, respectively.

14. The CMP system of claim 8 , wherein the in-situ rate monitor is further configured to define an initial pad life region, a middle pad life region, and an end pad life region.

15. The CMP system of claim 8 , wherein the in-situ rate monitor is further configured to collecting CMP data, and extracting a polishing characteristic parameter of the polishing pad.

16. The CMP system of claim 15 , wherein the in-situ rate monitor is further configured to define the plurality of time regions of pad life for the polishing pad based on the polishing characteristic parameter.

17. The CMP system of claim 15 , wherein the polishing characteristic parameter includes a polishing ratio defined as a ratio between a polishing rate of a metal material and a polishing rate of a dielectric material.

18. The CMP system of claim 17 , wherein the polishing ratio is defined as a ratio between an aluminum polishing rate and a silicon oxide polishing rate.

19. The CMP system of claim 8 , further including a CMP data module configured to collect data associated with the polishing pad.

20. The CMP system of claim 19 , wherein the data associated with the polishing pad includes at least one of polishing rate, CMP failure information, system maintenance record data, polishing pad replacement record data, and out of specification (OOS) records.

Assignees

• Lee Chu-An
• Huang Hui-Chi
• Jangjian Peng-Chung
• Taiwan Semiconductor Mfg

Inventors

• Lee Chu-An
• Huang Hui-Chi
• Jangjian Peng-Chung

Classifications

• H10P74/238

  comprising acting in response to an ongoing measurement without interruption of processing, e.g. endpoint detection or in-situ thickness measurement · CPC title

• H10P52/403

  of conductive or resistive materials · CPC title

• B24B37/013

  Devices or means for detecting lapping completion · CPC title

• H01J37/32963

  End-point detection · CPC title

• G05B2219/49085

  CMP end point analysis, measure parameters on points to detect end of polishing process · CPC title