Method of detecting defects on an object

• US 7,940,383 B2
• Filed: 12/03/2009
• Issued: 05/10/2011
• 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: Ninomiya, Takanori, Noguchi, Minori, Morishige, Yoshio, Watanabe, Tetsuyai, Kembo, Yukio, Matsunaga, Ryouji, Nakamura, Hisato, Sakai, Keiji, Matsumoto, Shunichi, Nishiyama, Hidetoshi, Jingu, Takahiro, Ohshima, Yoshimasa, Chikamatsu, Shuichi
• Primary Examiner(s): Chowdhury; Tarifur R.
• Assistant Examiner(s): Akanbi; Isiaka O
• Application Number:
  US12/630,307
• Publication Number:
  US 20100088042A1
• Time in Patent Office: 523 Days
• Field of Search: 3562372-2375
• 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 an object includes an illumination optical unit which obliquely projects a laser focused onto a line on a surface of the object and white-color, a table unit which mounts the specimen and which is movable, a detection optical unit which detects with an image sensor an image of light formed by light reflected from the object and passed through a filter which blocks diffraction light resulting from patterns formed on the object, a signal processor which processes a signal outputted from the image sensor of the detection optical unit to extract defects of the object, and a display unit which displays information of defects extracted by the signal processor. The filter is adjustable.

Claims

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

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

illuminating the surface of the object with white-color light;

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 or the white-color light;

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 or the white-color light;

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 the 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 optical unit includes detecting the second image reflected in an oblique direction.

3. The method according to claim 1, wherein the step of illuminating the object with a slit shaped laser light 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 include controlling polarization states 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 the 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 illuminating the object with a slit shaped laser light includes illuminating the object with a slit shaped ultraviolet laser light.

8. The method according to claim 1, wherein the step of illuminating the object with a slit shaped laser light includes 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 COD 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 of detecting defects on an object, comprising the steps of:

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;

projecting white-color light onto the surface of the object;

detecting with a first detection optical unit a first image formed by light reflected from the object by the projection of the slit shaped laser light and the white-color light;

detecting with a second detection optical unit a second image formed by light reflected from the object by the projection of the slit shaped laser light and the white-color light; 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 the 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 optical unit includes detecting the second image reflected in an oblique direction.

13. The method according to claim 11, wherein the step of projecting a slit shaped laser light 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 include controlling polarization states 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 the 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 projecting a slit shaped laser light includes projecting the object with a slit shaped ultraviolet laser light.

18. The method according to claim 11, wherein the step of projecting a slit shaped laser light includes 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 CCD image sensor.