Process window analysis

Patent metadata

Field	Value
Publication number	US-2016284579-A1
Application number	US-201514666183-A
Country	US
Kind code	A1
Filing date	Mar 23, 2015
Priority date	Mar 23, 2015
Publication date	Sep 29, 2016
Grant date	—

Abstract

A method for process analysis includes acquiring first inspection data, using a first inspection modality, with respect to a substrate having multiple instances of a predefined pattern of features formed thereon using different, respective sets of process parameters. Characteristics of defects identified in the first inspection data are processed so as to select a first set of defect locations in which the first inspection data are indicative of an influence of the process parameters on the defects. Second inspection data are acquired, using a second inspection modality having a finer resolution than the first inspection modality, of the substrate at the locations in the first set. The defects appearing in the second inspection data are analyzed so as to select, from within the first set of the locations, a second set of the locations in which the second inspection data are indicative of an optimal range of the process parameters.

First claim

1 . A method for process analysis, comprising:
acquiring first inspection data, using a first inspection modality, with respect to a substrate having multiple instances of a predefined pattern of features formed thereon by a fabrication process in which different, respective sets of process parameters are applied in forming different ones of the instances; processing the first inspection data so as to identify defects at respective locations in the instances of the pattern; analyzing characteristics of the defects identified in the first inspection data so as to select a first set of the locations in which the first inspection data are indicative of an influence of the process parameters on the defects; acquiring second inspection data, using a second inspection modality having a finer resolution than the first inspection modality, of the substrate at the locations in the first set; and analyzing the defects appearing in the second inspection data so as to select, from within the first set of the locations, a second set of the locations in which the second inspection data are indicative of an optimal range of the process parameters.

2 . The method according to claim 1 , wherein the pattern is formed on the substrate in accordance with a predefined design, and wherein the method comprises setting the process parameters for fabrication of devices in accordance with the design based on the selected second inspection data.

3 . The method according to claim 1 , wherein the first inspection modality is an optical imaging modality, and wherein the second inspection modality is an electron imaging modality.

4 . The method according to claim 1 , wherein the substrate comprises a semiconductor wafer, and wherein the fabrication process comprises lithographic patterning of the semiconductor wafer, and the instances of the predefined pattern comprise dies defined by the lithographic patterning.

5 . The method according to claim 4 , wherein the process parameters comprise a focal adjustment and an exposure level applied in the lithographic patterning.

6 . The method according to claim 1 , wherein analyzing the characteristics of the defects comprises:
clustering the defects into a plurality of bins corresponding to the respective locations of the defects in the instances of pattern; sorting the bins so as to prioritize the bins that are indicative of an influence of the process parameters on the defects; and selecting the first set of the locations from among the prioritized bins.

7 . The method according to claim 6 , wherein the pattern is formed on the substrate in accordance with a predefined design, and wherein clustering the defects comprises defining the bins responsively to respective features of the design occurring in the bins.

8 . The method according to claim 6 , wherein sorting the bins comprises identifying a correlation in one or more of the bins between changes in at least one of the process parameters and the defects in the one or more of the bins, and prioritizing the one or more of the bins responsively to the identified correlation.

9 . The method according to claim 1 , wherein analyzing the characteristics of the defects comprises computing for the defects corresponding values of a utility function that are indicative of an information content of the first inspection data at the respective locations of the defects, and selecting the first set of the locations in response to the values of the utility function.

10 . A method for process analysis, comprising:
acquiring inspection data with respect to a substrate having features formed thereon; processing the inspection data so as to identify a set of defects at respective locations on the substrate; computing for the defects in the set corresponding values of a utility function that are indicative of an information content of the inspection data at the respective locations of the defects; selecting a defect from the set in response to the values of the utility function; iteratively removing the selected defect from the set, recomputing the corresponding values of the utility function, and selecting another defect in response to the values of the recomputed utility function until a specified number of the defects have been selected; and outputting the respective locations of the selected defects.

11 . The method according to claim 10 , wherein the features comprise multiple instances of a predefined pattern of features formed thereon by a fabrication process in which different process parameters are applied in forming different ones of the instances, and wherein outputting the respective locations comprises providing an indication of an optimal range of the process parameters.

12 . The method according to claim 11 , wherein computing the corresponding values of the utility function comprises evaluating the information content of the inspection data with respect to the process parameters.

13 . The method according to claim 10 , wherein processing the inspection data comprises classifying the defects into a plurality of classes, wherein computing the corresponding values of the utility function comprises calculating an uncertainty of classification of the defects.

14 . The method according to claim 10 , wherein the inspection data comprise at least one image.

15 . A system for process analysis, comprising:
a first inspection machine, which is configured to acquire first inspection data, using a first inspection modality, with respect to a substrate having multiple instances of a predefined pattern of features formed thereon by a fabrication process in which different, respective sets of process parameters are applied in forming different ones of the instances; a second inspection machine, which is configured to acquire second inspection data with respect to the substrate, using a second inspection modality having a finer resolution than the first inspection modality; and a processor, which is configured to process the first inspection data so as to identify defects at respective locations in the instances of the pattern, to analyze characteristics of the defects identified in the first inspection data so as to select a first set of the locations in which the first inspection data are indicative of an influence of the process parameters on the defects, and to cause the second imaging machine to acquire the second inspection data at the locations in the first set, wherein the processor is configured to analyze the defects appearing in the second inspection data so as to select, from within the first set of the locations, a second set of the locations in which the second inspection data are indicative of an optimal range of the process parameters.

16 . The system according to claim 15 , wherein the pattern is formed on the substrate in accordance with a predefined design, and wherein the processor is configured to compute the process parameters for fabrication of devices in accordance with the design based on the selected second images.

17 . The system according to claim 15 , wherein the first inspection modality is an optical imaging modality, and wherein the second inspection modality is an electron imaging modality.

18 . The system according to claim 15 , wherein the substrate comprises a semiconductor wafer, and wherein the fabrication process comprises lithographic patterning of the semiconductor wafer, and the instances of the predefined pattern comprise dies defined by the lithographic patterning.

19 . The system according to claim 17 , wherein the p

Assignees

• Applied Materials Israel Ltd

Inventors

• Kaizerman Idan
• SOFER Yotam

Classifications

• H10P74/203 Primary

  Structural properties, e.g. testing or measuring thicknesses, line widths, warpage, bond strengths or physical defects · CPC title

• H10P74/23

  characterised by multiple measurements, corrections, marking or sorting processes · CPC title

• H01J2237/2817

  Pattern inspection · CPC title

• H01J37/304

  Controlling tubes by information coming from the objects {or from the beam}, e.g. correction signals · CPC title

• H01J37/28

  with scanning beams {(H01J37/268, H01J37/292, H01J37/2955 take precedence)} · CPC title