# US 7,746,459 B2 · Systems configured to inspect a wafer

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- Number: US 7,746,459 B2
- Document ID: US7746459B2
- Status: Granted
- Kind: B2
- Application number: 11/837,220
- Filed: 2007-08-10
- Published: 2009-02-12
- Granted: 2010-06-29
- Earliest claimed: 2007-08-10
- Assignees: KLA-Tencor Technologies Corporation
- Inventors: Azmi Kadkly; Stephen Biellak; Mehdi Vaez-Iravani
- Web page: https://patentgrep.com/patent/US7746459B2

## CPC

- G01N 21/9501: {Semiconductor wafers (manufacturing processes per se of semiconductor devices implementing a measuring step H10P74/20)}
- G01N: INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES (measuring or testing apparatus or processes other than immunoassay, involving enzymes or microorganisms C12M, C12Q)

## Abstract

Systems configured to inspect a wafer are provided. One system includes an illumination subsystem configured to illuminate an area on the wafer by directing light to the wafer at an oblique angle of incidence. The system also includes a collection subsystem configured to simultaneously collect light scattered from different spots within the illuminated area and to focus the light collected from the different spots to corresponding positions in an image plane. In addition, the system includes a detection subsystem configured to separately detect the light focused to the corresponding positions in the image plane and to separately generate output responsive to the light focused to the corresponding positions in the image plane. The output can be used to detect defects on the wafer.

## Claims

### Claim 1

A system configured to inspect a wafer, comprising:
an illumination subsystem configured to illuminate an area on the wafer by directing light to the wafer at an oblique angle of incidence;
a collection subsystem configured to simultaneously collect light scattered from different spots within the illuminated area and to focus the light collected from the different spots to corresponding positions in an image plane, wherein the different spots are spatially separated from each other within the illuminated area on the wafer, and wherein each of the different spots is configured such that an amount of haze collected from each of the different spots is significantly less than an amount of haze associated with the illuminated area on the wafer; and
a detection subsystem configured to separately detect the light focused to the corresponding positions in the image plane and to separately generate output responsive to the light focused to the corresponding positions in the image plane, wherein the output can be used to detect defects on the wafer.

### Claim 2 (depends on 1)

The system of claim 1, wherein the different spots within the illuminated area do not overlap with each other within the illuminated area.

### Claim 3 (depends on 1)

The system of claim 1, wherein a size of each of the different spots on the wafer is approximately equal.

### Claim 4 (depends on 1)

The system of claim 1, wherein each of the different spots is further configured such that a direct current light level due to the haze collected from each of the different spots is significantly less than a direct current light level due to the haze associated with the illuminated area on the wafer.

### Claim 5 (depends on 1)

The system of claim 1, wherein each of the different spots is further configured such that spatial noise collected from each of the different spots due to roughness of the wafer is significantly less than spatial noise associated with the illuminated area on the wafer due to the roughness of the wafer.

### Claim 6 (depends on 1)

The system of claim 1, wherein the collection subsystem comprises an optical element configured to simultaneously collect the light scattered from the different spots, and wherein a section of the optical element is removed such that the illumination subsystem can direct the light through the section to the area on the wafer at the oblique angle of incidence.

### Claim 7 (depends on 1)

The system of claim 1, wherein the wafer comprises an unpatterned wafer.

### Claim 8 (depends on 1)

The system of claim 1, wherein the wafer comprises a patterned wafer, and wherein the system is further configured to scan the light directed to the patterned wafer across the patterned wafer in x and y directions.

### Claim 9 (depends on 1)

The system of claim 1, wherein the collection subsystem comprises a miniaturized refractive optical element configured to simultaneously collect the light scattered from the different spots.

### Claim 10 (depends on 1)

The system of claim 1, wherein the collection subsystem comprises a refractive optical element configured to simultaneously collect the light scattered from the different spots, and wherein the refractive optical element has a size allowing the system to move the refractive optical element during scanning of the light over the wafer in response to changes in focus of the collection subsystem.

### Claim 11 (depends on 1)

The system of claim 1, wherein the collection subsystem is corrected such that the light scattered from the different spots is imaged to the corresponding positions in the image plane with a defined point spread function.

### Claim 12 (depends on 1)

The system of claim 1, wherein the system is further configured to scan the light directed to the wafer across the wafer by simultaneously rotating and translating the wafer.

### Claim 13 (depends on 1)

The system of claim 1, wherein the detection subsystem comprises a detector array configured to separately detect the light focused to the corresponding positions in the image plane.

### Claim 14 (depends on 1)

The system of claim 1, wherein the detection subsystem comprises a set of optical fibers configured to separately transmit the light from the corresponding positions in the image plane to different detectors of the detection subsystem.

### Claim 15

A system configured to inspect a patterned wafer, comprising:
an illumination subsystem configured to simultaneously illuminate multiple spots on the patterned wafer at a substantially normal angle of incidence;
a collection subsystem configured to separately collect light from the multiple spots and to focus the light collected from the multiple spots to corresponding positions in an image plane, wherein each of the multiple spots is configured such that an amount of haze collected from each of the multiple spots is significantly less than an amount of haze associated with an area covered by all of the multiple spots on the patterned wafer; and
a detection subsystem configured to separately detect the light focused to the corresponding positions in the image plane and to separately generate output responsive to the light focused to the corresponding positions in the image plane, wherein the output can be used to detect defects on the patterned wafer.

### Claim 16 (depends on 15)

The system of claim 15, wherein the multiple spots do not overlap with each other on the patterned wafer.

### Claim 17 (depends on 15)

The system of claim 15, wherein the light from the multiple spots comprises scattered light.

### Claim 18 (depends on 15)

The system of claim 15, wherein the light from the multiple spots comprises reflected light.

### Claim 19 (depends on 15)

The system of claim 15, wherein a size of each of the multiple spots on the patterned wafer is approximately equal.

### Claim 20 (depends on 15)

The system of claim 15, wherein each of the multiple spots is further configured such that a direct current light level due to the haze collected from each of the multiple spots is significantly less than a direct current light level due to the haze associated with the area covered by all of the multiple spots on the patterned wafer.

### Claim 21 (depends on 15)

The system of claim 15, wherein each of the multiple spots is further configured such that spatial noise collected from each of the multiple spots due to roughness of the patterned wafer is significantly less than spatial noise associated with the area covered by all of the multiple spots on the patterned wafer due to the roughness of the patterned wafer.

### Claim 22 (depends on 15)

The system of claim 15, wherein the collection subsystem comprises a miniaturized refractive optical element configured to collect the light from the multiple spots.

### Claim 23 (depends on 15)

The system of claim 15, wherein the collection subsystem comprises a refractive optical element configured to collect the light from the multiple spots, and wherein the refractive optical element has a size allowing the system to move the refractive optical element during scanning of the patterned wafer in response to changes in focus of the collection subsystem.

### Claim 24 (depends on 15)

The system of claim 15, wherein the collection subsystem is corrected such that the light from the multiple spots is imaged to the corresponding positions in the image plane with a defined point spread function.

### Claim 25 (depends on 15)

The system of claim 15, wherein the system is further configured to scan light directed to the multiple spots on the patterned wafer across the patterned wafer by simultaneously rotating and translating the patterned wafer.

### Claim 26 (depends on 15)

The system of claim 15, wherein the detection subsystem comprises a detector array configured to separately detect the light focused to the corresponding positions in the image plane.

### Claim 27 (depends on 15)

The system of claim 15, wherein the detection subsystem comprises a set of optical fibers configured to separately transmit the light from the corresponding positions in the image plane to different detectors of the detection subsystem.

### Claim 28 (depends on 1)

The system of claim 1, wherein a size of each of the different spots on the wafer is selected such that a substantial amount of the light scattered from the different spots is not scattered from a surface of the wafer.

### Claim 29 (depends on 15)

The system of claim 15, wherein a size of each of the different spots on the wafer is selected such that a substantial amount of the light scattered from the different spots is not scattered from a surface of the wafer.