Apparatus and method for testing defects

• US 7,037,735 B2
• Filed: 06/14/2002
• Issued: 05/02/2006
• Est. Priority Date: 04/02/1991
• Status: Expired due to Fees

• Current Assignee: Hitachi High-Technologies Corporation (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): NGUYEN, THANH T
• Application Number:
  US10/170,378
• Publication Number:
  US 20020168787A1
• Time in Patent Office: 1,418 Days
• Field of Search: 3562371-2375, 438/16, 250/492.1, 250/492.2
• US Class Current: 438/18
• 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 defect inspection method includes radiating an illumination slit-shaped beam having lights substantially parallel to a longitudinal direction to a substrate having circuit patterns in a direction inclined at a predetermined gradient relative to the direction of a line normal to the substrate and inclined at a predetermined gradient on a surface with respect to a group of main straight lines of the circuit patterns with its longitudinal direction oriented almost perpendicularly to a direction of a movement of the substrate. Scattered light reflected by a defect such as a foreign particle existing on the illuminated substrate is received and converted into a detection signal by using an image sensor, and defect judging is effected of an extracted a signal indicating a defect such as a foreign particle on the basis of the detection signal output.

Claims

1. A defect inspecting apparatus comprising:

a stage used for mounting a substrate serving as an object of inspection and having circuit patterns created thereon, said stage enabling movement of said substrate;

an illumination optical system for radiating an illumination beam to said substrate;

a detection optical system for receiving scattered light reflected from said substrate illuminated by said illumination optical system and for converting said received light into detection image signals by using an image sensor; and

an image-signal processing unit including a variation computation unit which computes a variation of said detection image signals at corresponding locations including corresponding adjacent locations between areas where circuit patterns with substantially identical shapes are naturally repeated on said inspected substrate, a criterion setting unit which sets a criterion on the basis of said variation computed by said variation computation unit, and a signal extracting unit which extracts a signal indicating a defect such as a foreign particle whether said detection image signal is exceeded by said criterion set by said criterion setting unit.

2. A defect inspecting apparatus according to claim 1, wherein said illumination optical system is constructed so as to irradiate a slit-shaped beam as said illumination beam from a light source to said substrate in a direction inclined at a predetermined gradient related to a direction of a line normal to said inspected with a longitudinal direction thereof being oriented substantially perpendicularly to a movement of said stage.

3. A defect inspecting apparatus according to claim 1, wherein said signal extracting unit has a unit for which said criterion is set for each of a variety of areas constituting said circuit pattern.

4. A defect inspecting apparatus according to claim 1, wherein in said illumination optical system, said light source is a laser light source.

5. A defect inspecting apparatus according to claim 1, wherein a spatial filter is provided in said detection optical system.

6. A defect inspecting apparatus according to claim 1, wherein said criterion setting unit sets said criterion on the basis of a value which is multiplied by a magnification m1 according to a false-information generation rate to said variation.

7. A defect inspecting apparatus according to claim 1, wherein in said image-signal processing unit, said variation computation unit computes said variation of said detection signals at corresponding locations including corresponding adjacent locations between areas as a variation of differential detection signals at corresponding locations between adjacent areas, said detection signals being differential detection signals at said corresponding locations between said adjacent areas.

8. A defect inspecting apparatus according to claim 1, wherein said image-signal processing unit has an output unit which outputs pieces of data representing a result inspection extracted by said signal extracting unit and said criterion set by said criterion setting unit.

9. A defect inspecting apparatus according to claim 1, wherein said image-signal processing unit has a display unit which displays map information on said area as said criterion or an image of said criterion used in said signal extracting unit.

10. A defect inspecting apparatus according to claim 1, wherein said illumination optical system has a control unit which controls power of the illumination beam in accordance with an area priority mode, a standard mode and a sensitivity priority mode.

11. A defect inspecting apparatus according to claim 1, wherein said image-signal processing unit has a display unit which displays a relation between said criterion and an index about sensitivity corresponding to said criterion.

12. A defect inspecting apparatus according to claim 1, wherein said image-signal processing unit has a display unit which displays sensitivity information for said area corresponding to said criterion.

13. A defect inspecting apparatus according to claim 1, wherein said illumination beam radiated by said illumination optical system is a Deep Ultra-Violet beam.

14. A defect inspecting apparatus comprising:

an illumination optical system for radiating an illumination beam to a substrate serving as an object of inspection;

a detection optical system including a beam splitting optical system for splitting a light beam reflected by said substrate into reflected beams with one of said reflected beams having an intensity which is different from an intensity of another of said reflected beams, and a plurality of image sensors for receiving said reflected beams output by said beam splitting optical system; and

an image-signal processing unit for processing said detection signals output by each of image sensors so as to extract a signal indicating a defect.

15. A defect inspecting apparatus according to claim 14, wherein in said beam splitting optical system, a ratio of intensity difference of said reflected beams is about 1/100.

16. A defect inspecting apparatus according to claim 14, wherein an optical axis in said detection optical system is inclined with respect to a line normal to said substrate.

17. A defect inspecting apparatus comprising:

an illumination optical system for radiating an illumination beam to a substrate serving as an object of inspection;

a detection optical system having an optical axis inclined with respect to a line normal to said substrate so as to receive light obtained through a spatial filter from scattered light reflected from said substrate illuminated by said illumination optical system, said spatial filter enabling shielding of a Fourier-transmission image formed by a diffraction light generated from at least repetitive patterns in circuit pattern existing on said substrate, and an image sensor for converting received light into detection image signals; and

an image-signal processing unit for processing said detection image signals to extract a signal indicating a defect such as a foreign particle, by using criteria set on the basis of variation of said detection image signals.

18. A defect inspecting apparatus comprising:

a stage used for mounting a substrate serving as an object of inspection and having circuit patterns created thereon, said stage enabling movement of said substrate;

an illumination optical system for radiating an illumination beam to said substrate;

a detection optical system for receiving scattered light reflected from said substrate illuminated by said illumination optical system and for converting said received light into detection image signals by using an image sensor; and

an image-signal processing unit including an image memory which memorizes said detection image signals in a pixel unit converted by said image sensor;

a plurality of operators having different dimensions changed by size of pixel unit to each other in order to judge defects for which sizes differ, the detection image signals obtained from said image memory by each of different dimensions in each if said operators being extracted and being outputted as gradation image signals of predetermined level from a central pixel by convolution of said extracted image signals; and

a comparison circuit which compares gradation image signals outputted from each of said operators with predetermined threshold values in order to judge said defects such as foreign particles for which sizes differ.