Adaptive Sampling for Process Window Determination

Patent metadata

Field	Value
Publication number	US-2016274036-A1
Application number	US-201615067118-A
Country	US
Kind code	A1
Filing date	Mar 10, 2016
Priority date	Mar 16, 2015
Publication date	Sep 22, 2016
Grant date	—

Abstract

Methods and systems for determining a process window for a process performed on a specimen are provided. In general, the embodiments preferentially sample locations in an instance of at least a portion of a device formed on a specimen at a value of a parameter of a process performed on the specimen that is closest to an edge of a determined process window for the process. If defects are detected at the sampled locations, then the sampling may be performed again but for a different instance of the device formed at a value of the parameter that is closer to nominal than the previously used value. When no defects are detected at the sampled locations, then the sampling may be ended, and the determined process window may be modified based on the value of the parameter corresponding to the instance of the device in which no defects were detected.

First claim

What is claimed is:

1 . A system configured to determine a process window for a process performed on a specimen, comprising:
an output acquisition subsystem comprising at least an energy source and a detector, wherein the energy source is configured to generate energy that is directed to a specimen, and wherein the detector is configured to detect energy from the specimen and to generate output responsive to the detected energy; and one or more computer subsystems configured for:
acquiring results of an inspection of the specimen, wherein the specimen comprises multiple instances of at least a portion of a device formed thereon with different values of a parameter of a process performed on the specimen, and wherein the results of the inspection comprise information for defects detected in the multiple instances during the inspection, information for hot spots within the at least the portion of the device detected during the inspection, and information for a process window of the process determined by the inspection;
selecting, based on the results of the inspection, a portion of locations within a first of the multiple instances formed on the specimen with a first of the different values that is closest to a value of the parameter at an edge of the process window;
acquiring the output of the output acquisition subsystem for at least one of the locations in the portion;
determining if defects are present at the at least one of the locations based on the acquired output;
when one or more of the defects are determined to be present at the at least one of the locations, repeating the selecting, acquiring the output, and determining if the defects are present for another of the multiple instances formed on the specimen with another of the different values that is closer to nominal than the first of the different values; and
when the defects are determined to be not present at the locations in the selected portion, determining a revised process window based on which of the different values corresponds to the multiple instance in which the defects were determined to be not present.

2 . The system of claim 1 , wherein the inspection comprises a first inspection pass in which the hot spots are detected and a second inspection pass in which the process window is determined.

3 . The system of claim 1 , wherein selecting the portion of the locations is performed independently for different groups of the hot spots.

4 . The system of claim 1 , wherein, when the selecting is repeated, selecting the portion of the locations within the other of the multiple instances is performed based on the results of the inspection and the one or more defects determined to be present at the at least one of the locations in the first of the multiple instances.

5 . The system of claim 1 , wherein the selected portion of the locations comprises locations at which the inspection detected the defects.

6 . The system of claim 1 , wherein the selected portion of the locations comprises locations at which the inspection did not detect the defects.

7 . The system of claim 1 , wherein the one or more computer subsystems are further configured to determine a number of the locations that are selected based on a predetermined confidence for determining a failure rate of the locations, and wherein the one or more computer subsystems are further configured to determine the failure rate based on the defects determined to be present at the locations in the selected portion.

8 . The system of claim 1 , wherein selecting the portion of the locations comprises selecting as many of the locations at which the defects were detected by the inspection as possible for inclusion in the selected portion of the locations.

9 . The system of claim 1 , wherein selecting the portion of the locations comprises randomly selecting locations of the hot spots for inclusion in the selected portion of the locations.

10 . The system of claim 1 , wherein acquiring the output and determining if the defects are present are performed for a first of the locations in the portion, and wherein when the one or more defects are determined to be present in the first of the locations, the one or more computer subsystems are further configured for determining that acquiring the output and determining if the defects are present are not to be performed for any other of the locations in the selected portion.

11 . The system of claim 1 , wherein when the defects are determined to be not present at the locations in the selected portion, the one or more computer subsystems are further configured for determining that the selecting, acquiring the output, and determining if the defects are present are not to be performed for any other of the multiple instances.

12 . The system of claim 1 , wherein the one or more computer subsystems are further configured for classifying the defects determined to be present at one or more of the locations in the selected portion based on the acquired output and modifying the selected portion of the locations based on results of the classifying.

13 . The system of claim 1 , wherein the hot spots comprise different groups of hot spots, and wherein the portion of the locations is selected to include the hot spots in only one of the different groups.

14 . The system of claim 1 , wherein the hot spots comprise different groups of hot spots, and wherein the portion of the locations is selected to include the hot spots in more than one of the different groups.

15 . The system of claim 1 , wherein the specimen comprises a wafer.

16 . The system of claim 1 , wherein the energy directed to the specimen comprises light, and wherein the energy detected from the specimen comprises light.

17 . The system of claim 1 , wherein the energy directed to the specimen comprises electrons, and wherein the energy detected from the specimen comprises electrons.

18 . A non-transitory computer-readable medium, storing program instructions executed on a computer system for performing a computer-implemented method for determining a process window for a process performed on a specimen, wherein the computer-implemented method comprises:
acquiring results of an inspection of a specimen, wherein the specimen comprises multiple instances of at least a portion of a device formed thereon with different values of a parameter of a process performed on the specimen, and wherein the results of the inspection comprise information for defects detected in the multiple instances during the inspection, information for hot spots within the at least the portion of the device detected during the inspection, and information for a process window of the process determined by the inspection; selecting, based on the results of the inspection, a portion of locations within a first of the multiple instances formed on the specimen with a first of the different values that is closest to a value of the parameter at an edge of the process window; acquiring output of an output acquisition subsystem for at least one of the locations in the portion, wherein the output acquisition subsystem comprises at least an energy source and a detector, wherein the energy source is configured to generate energy that is directed to the specimen, and wherein the detector is configured to detect energy from the specimen and to generate output responsive to the detected energy; determining if defects are present at the at least one of the locations based on the acquired output; when one or more of the defects are determined to be present at the at least one of

Assignees

• Kla Tencor Corp

Inventors

• Plihal Martin

Classifications

• H10P74/203

  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

• H01L21/67288

  Electricity · mapped topic

• G01N2201/12

  Circuits of general importance; Signal processing · CPC title

• G01N21/9501 Primary

  Semiconductor wafers (manufacturing processes per se of semiconductor devices implementing a measuring step H10P74/20) · CPC title