Overlay Variance Stabilization Methods and Systems

Patent metadata

Field	Value
Publication number	US-2017219928-A1
Application number	US-201615256410-A
Country	US
Kind code	A1
Filing date	Sep 2, 2016
Priority date	Feb 2, 2016
Publication date	Aug 3, 2017
Grant date	—

Abstract

Methods and systems for providing overlay corrections are provided. A method may include: selecting an overlay model configured to perform overlay modeling for a wafer; obtaining a first set of modeled results from the overlay model, the first set of modeled results indicating adjustments applicable to a plurality of term coefficients of the overlay model; calculating a significance matrix indicating the significance of the plurality of term coefficients; identifying at least one less significant term coefficient among the plurality of term coefficients based on the calculated significance matrix; obtaining a second set of modeled results from the overlay model, the second set of modeled results indicating adjustments applicable to the plurality of term coefficients except for the identified at least one less significant term coefficient; and providing the second set of modeled results to facilitate overlay correction.

First claim

What is claimed is:

1 . A method, comprising:
selecting an overlay model configured to perform overlay modeling for a wafer; obtaining a first set of modeled results from the overlay model, the first set of modeled results indicating adjustments applicable to a plurality of term coefficients of the overlay model; calculating a significance matrix indicating the significance of the plurality of term coefficients; identifying at least one less significant term coefficient among the plurality of term coefficients based on the calculated significance matrix; obtaining a second set of modeled results from the overlay model, the second set of modeled results indicating adjustments applicable to the plurality of term coefficients except for the identified at least one less significant term coefficient; and providing the second set of modeled results to facilitate overlay correction.

2 . The method of claim 1 , wherein the significant matrix is calculated at least partially based on an impact of each term coefficient on the first set of modeled results.

3 . The method of claim 1 , wherein the significant matrix is calculated at least partially based on a variance and a covariance of each term coefficient.

4 . The method of claim 1 , wherein the identified at least one less significant term coefficient is removed from the overlay model when obtaining the second set of modeled results.

5 . The method of claim 1 , wherein the identified at least one less significant term coefficient is cascaded and provide along with the second set of modeled results to facilitate overlay correction.

6 . The method of claim 1 , wherein the identified at least one less significant term coefficient is weighted based on its corresponding significance and provide along with the second set of modeled results to facilitate overlay correction.

7 . The method of claim 1 , further comprising:
providing a feedback or a feed forward control of at least one process tool based on the significance matrix.

8 . The method of claim 1 , wherein the overlay modeling is performed based on a plurality of sampling points selected for the wafer.

9 . The method of claim 8 , further comprising:
modifying the plurality of sampling points selected based on the significance matrix.

10 . The method of claim 1 , wherein the overlay model is an orthogonal model.

11 . A system, comprising:
an overlay metrology tool configured to obtain metrology data from a set of wafers; and an analyzer in communication with the overlay metrology tool, the analyzer configured to:
select an overlay model configured to perform overlay modeling for the set of wafers;
obtain a first set of modeled results from the overlay model, the first set of modeled results indicating adjustments applicable to a plurality of term coefficients of the overlay model;
calculate a significance matrix indicating the significance of the plurality of term coefficients;
identify at least one less significant term coefficient among the plurality of term coefficients based on the calculated significance matrix;
obtain a second set of modeled results from the overlay model, the second set of modeled results indicating adjustments applicable to the plurality of term coefficients except for the identified at least one less significant term coefficient; and
provide the second set of modeled results to facilitate overlay correction.

12 . The system of claim 11 , wherein the analyzer is configured to calculate the significant matrix at least partially based on an impact of each term coefficient on the first set of modeled results.

13 . The system of claim 11 , wherein the analyzer is configured to calculate the significant matrix at least partially based on a variance and a covariance of each term coefficient.

14 . The system of claim 11 , wherein the analyzer is configured to remove the identified at least one less significant term coefficient from the overlay model when the analyzer obtains the second set of modeled results.

15 . The system of claim 11 , wherein the analyzer is configured to cascade the identified at least one less significant term coefficient and provide the identified at least one less significant term coefficient along with the second set of modeled results to facilitate overlay correction.

16 . The system of claim 11 , wherein the analyzer is configured to weight the identified at least one less significant term coefficient based on its corresponding significance and provide the weighted at least one less significant term coefficient along with the second set of modeled results to facilitate overlay correction.

17 . The system of claim 11 , wherein the analyzer is further configured to provide a feedback or a feed forward control to at least one process tool based on the significance matrix.

18 . The system of claim 11 , wherein the overlay modeling is performed based on a plurality of sampling points selected for the set of wafers.

19 . The system of claim 18 , wherein the analyzer is further configured to modify the plurality of sampling points selected based on the significance matrix.

20 . The system of claim 11 , wherein the overlay model is an orthogonal model.

21 . A system, comprising:
an overlay metrology tool configured to obtain metrology data from a set of wafers; and an analyzer in communication with the overlay metrology tool, the analyzer configured to:
select a plurality of sampling points from the set of wafers and select an overlay model configured to perform overlay modeling based on the plurality of sampling points;
obtain a first set of modeled results from the overlay model, the first set of modeled results indicating adjustments applicable to a plurality of term coefficients of the overlay model;
calculate a significance matrix indicating the significance of the plurality of term coefficients; and
modify the plurality of sampling points selected for overlay modeling based on the significance matrix.

22 . The system of claim 21 , wherein the analyzer is configured to modify the plurality of sampling points selected for overlay modeling when a variance of at least one term coefficient of the plurality of term coefficients is above a threshold.

23 . The system of claim 21 , wherein the analyzer is further configured to perform overlay modeling based on the modified sampling points.

Assignees

• Kla Tencor Corp

Inventors

• Heo Hoyoung
• Pierson William
• Nabeth Jeremy
• Jeon Sanghuck
• Demirer Onur N
• Garcia-Medina Miguel
• Vuppala Soujanya

Classifications

• G06F17/5036

  Physics · mapped topic

• G03F7/70533

  Controlling abnormal operating mode, e.g. taking account of waiting time, decision to rework or rework flow · CPC title

• G03F7/705 Primary

  Modelling or simulating from physical phenomena up to complete wafer processes or whole workflow in wafer productions · CPC title

• G06F17/5081

  Physics · mapped topic

• G03F7/70625

  Dimensions, e.g. line width, critical dimension [CD], profile, sidewall angle or edge roughness · CPC title