Apparatus and method for testing defects

• US 7,639,350 B2
• Filed: 03/05/2007
• Issued: 12/29/2009
• Est. Priority Date: 04/02/1991
• Status: Expired due to Fees

• Current Assignee: Hitachi High-Technologies Corporation (Hitachi, Ltd.), Hitachi, Ltd.
• Original Assignee: Hitachi High-Technologies Corporation (Hitachi, Ltd.), Hitachi, Ltd.
• Inventors: Sakai, Keiji, Matsumoto, Shunichi, Nishiyama, Hidetoshi, Jingu, Takahiro, Ohshima, Yoshimasa, Ninomiya, Takanori, Noguchi, Minori, Watanabe, Tetsuya, Chikamatsu, Shuichi, Morishige, Yoshio, Kembo, Yukio, Matsunaga, Ryouji, Nakamura, Hisato
• Primary Examiner(s): Chowdhury; Tarifur R.
• Assistant Examiner(s): Akanbi; Isiaka O
• Application Number:
  US11/681,981
• Publication Number:
  US 20070146696A1
• Time in Patent Office: 1,030 Days
• Field of Search: 3562372-2375, 359/625, 359/639, 359456-457
• US Class Current: 356/237.2
• CPC Class Codes: B82Y 15/00 Nanotechnology for interacting, sensing or actuating, e.g. quantum dots as markers in protein assays or molecular motors
• CPC Class Codes: G01N 2021/8822 Dark field detection
• CPC Class Codes: G01N 21/94 Investigating contamination, e.g. dust G01N21/85 takes precedence
• CPC Class Codes: G01N 21/95623 using a spatial filtering method per se G02B
• CPC Class Codes: G01N 21/95684 Patterns showing highly reflecting parts, e.g. metallic elements
• CPC Class Codes: G01R 31/308 using non-ionising electromagnetic radiation, e.g. optical radiation investigating or analysing materials by the use of optical means G01N21/00; image analysis G06T7/00
• CPC Class Codes: H01J 2237/022 Avoiding or removing foreign or contaminating particles, debris or deposits on sample or tube
• CPC Class Codes: H01J 2237/0225 Detecting or monitoring foreign particles
• CPC Class Codes: H01J 37/00 Discharge tubes with provision for introducing objects or material to be exposed to the discharge, e.g. for the purpose of examination or processing thereof H01J33/00, H01J40/00, H01J41/00, H01J47/00, H01J49/00 take precedence
• CPC Class Codes: H01L 21/67253 Process monitoring, e.g. flow or thickness monitoring
• CPC Class Codes: H01L 21/67288 Monitoring of warpage, curvature, damage, defects or the like
• CPC Class Codes: H01L 21/681 using optical controlling means
• CPC Class Codes: H01L 22/12 for structural parameters, e.g. thickness, line width, refractive index, temperature, warp, bond strength, defects, optical inspection, electrical measurement of structural dimensions, metallurgic measurement of diffusions electrical measurement of diffusions H01L22/14
• CPC Class Codes: H01L 2924/00 Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/0002 Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00

Abstract

A method for detecting defects on a specimen includes mounting a specimen on a table with which is movable, obliquely projecting a laser as a line onto a surface of the specimen, detecting with an image sensor an image of light formed by light reflected from the specimen and passed through a filter which blocks scattered light resulting from repetitive patterns formed on the specimen, processing a signal outputted from the image sensor to extract defects of the specimen, and a displaying information of defects extracted by the signal processor.

Claims

1. A method for detecting defects on an object, comprising the steps of:

obliquely illuminating the object with slit shaped laser light, the slit shaped laser light being converged in one direction and collimated in a direction transverse to the one direction;

detecting with a first detection optical unit a first image formed by light reflected from the object by the illumination of the slit shaped laser light and reflected in a first oblique direction to the surface of the object;

detecting with a second detection optical unit a second image formed by light reflected from the object by the illumination of the slit shaped laser light and reflected in a second oblique direction to the surface of the object;

processing with an image signal processing unit both of a signal outputted from the first detection optical unit by the detection of the first image and a signal outputted from the second detection optical unit by the detection of the second image; and

outputting information processed by the image signal processing unit;

wherein the step of detecting with the first detection optical unit includes cutting off light reflected from patterns formed on the object by utilizing a first variable spatial filter; and

wherein the step of detecting with the second detection optical unit includes cutting off light reflected from patterns formed on the object by utilizing a second variable spatial filter.

2. The method according to claim 1, wherein the step of detecting with the second detection includes detecting the second image reflected in the second oblique direction which is a different direction from the first oblique direction.

3. The method according to claim 1, wherein the step of obliquely illuminating includes controlling a polarization state of the slit shaped laser light.

4. The method according to claim 3, wherein both of the steps of detecting with the first detection optical unit and detecting with the second detection optical unit includes controlling a polarization state of the reflected light.

5. The method according to claim 1, wherein both of the first variable spatial filter and the second variable spatial filter include plural patterns which cut off the light reflected from patterns formed on the object, the plural patterns having pitches which are changeable.

6. The method according to claim 1, wherein both of the first variable spatial filter and the second variable spatial filter include a liquid crystal device.

7. The method according to claim 1, wherein the step of obliquely illuminating includes obliquely illuminating the object with slit shaped ultraviolet laser light.

8. The method according to claim 1, wherein the step of obliquely illuminating includes obliquely utilizing a cylindrical shaped lens.

9. The method according to claim 1, wherein the step of detecting with the first detection optical unit includes utilizing a first image sensor which is a TDI image sensor or a CCD image sensor.

10. The method according to claim 1, wherein the step of detecting with the second detection optical unit includes utilizing a second image sensor which is a TDI image sensor or a COD image sensor.

11. A method for detecting defects on an object, comprising the steps of:

obliquely projecting a slit shaped laser light focused onto a line on a surface of the object, the slit shaped laser light being converged in one direction and collimated in a direction transverse to the one direction;

detecting with a first detection optical unit a first image formed by light reflected from the object by the illumination of the slit shaped laser light and reflected in a first oblique direction to the surface of the object;

detecting with a second detection optical unit a second image formed by light reflected from the object by the illumination of the slit shaped laser light and reflected in a second oblique direction to the surface of the object; and

processing both of a signal outputted from the first detection optical unit by the detection of the first image and a signal outputted from the second detection optical unit by the detection of the second image;

wherein the step of detecting with the first detection optical unit includes cutting off light reflected from patterns formed on the object by utilizing a first variable spatial filter; and

wherein the step of detecting with the second detection optical unit includes cutting off light reflected from patterns formed on the object by utilizing a second variable spatial filter.

12. The method according to claim 11, wherein the step of detecting with the second detection includes detecting the second image reflected in the second oblique direction which is a different direction from the first oblique direction.

13. The method according to claim 11, wherein the step of obliquely projecting includes controlling a polarization state of the slit shaped laser light.

14. The method according to claim 13, wherein both of the steps of detecting with the first detection optical unit and detecting with the second detection optical unit includes controlling a polarization state of the reflected light.

15. The method according to claim 11, wherein both of the first variable spatial filter and the second variable spatial filter include plural patterns which cut off the light reflected from patterns formed on the object, the plural patterns having pitches which are changeable.

16. The method according to claim 11, wherein both of the first variable spatial filter and the second variable spatial filter include a liquid crystal device.

17. The method according to claim 11, wherein the step of obliquely projecting includes obliquely projecting the object with slit shaped ultraviolet laser light.

18. The method according to claim 11, wherein the step of obliquely projecting includes obliquely projecting utilizing a cylindrical shaped lens.

19. The method according to claim 11, wherein the step of detecting with the first detection optical unit includes utilizing a first image sensor which is a TDI image sensor or a COD image sensor.

20. The method according to claim 11, wherein the step of detecting with the second detection optical unit includes utilizing a second image sensor which is a TDI image sensor or a COD image sensor.