Method and apparatus for detecting defects

• US 20070058164A1
• Filed: 07/03/2006
• Published: 03/15/2007
• Est. Priority Date: 09/09/2005
• Status: Active Grant

• Current Assignee: Hitachi High-Technologies Corporation (Hitachi, Ltd.)
• Original Assignee: Hitachi High-Technologies Corporation (Hitachi, Ltd.)
• Inventors: Nishiyama, Hidetoshi, Maeda, Shunji, Shibata, Yukihiro
• Granted Patent: US 7,400,393 B2
• Time in Patent Office: Days
• US Class Current: 356/237.200
• CPC Class Codes: G01N 2021/8822 Dark field detection
• CPC Class Codes: G01N 21/95607 using a comparative method

Abstract

This invention provides a defect inspection method and apparatus that can easily and quickly determine, from among a plurality of inspection conditions, a condition that allows for an inspection with high sensitivity. The inspection apparatus has a variety of optical functions to cover a variety of kinds of defects to be inspected (shape, material, nearby pattern, etc.). For each optical function, grayscale depths of defects that the operator wants detected and of pseudo defects that he or she wants undetected are accumulated for future use, so that conditions conducive to a higher sensitivity and a lower pseudo defect detection rate can be selected efficiently. Conditions that can be selected for optical systems include a bright-field illumination, a dark-field illumination and a bright-/dark-field composite illumination, illumination wavelength bands, polarization filters and spatial filters.

Claims

1. A defect inspection apparatus comprising:

a light source means for emitting beams of a plurality of wavelength bands;

a light radiation means for selecting a beam of a desired wavelength from among the beams of the plurality of wavelength bands emitted by the light source means and radiating the selected beam onto a specimen formed with a wire pattern;

a detection means for receiving an optical image of the specimen, radiated with the beam of the desired wavelength from the light radiation means and formed with the wire pattern, and for outputting an image signal;

an image processing means for processing the image signal output from the detection means to detect defects;

a control means for controlling at least one of the light source means, the light radiation means, the image detection means and the image processing means;

an inspection information database means having a database associated with the specimen and a database associated with optical conditions of at least one of the light source means, the light radiation means, the image detection means and the image processing means; and

an input means for inputting information associated with the specimen;

wherein the light radiation means has a wavelength selection unit and a plurality of optical systems;

wherein the control means, based on information associated with a material of the wire pattern of the specimen input from the input means, controls the wavelength selection unit to select a beam of wavelength band to be radiated onto the specimen formed with the wire pattern, from among the beams of the plurality of wavelength bands emitted from the light source means and at the same time selects, from among the plurality of optical systems, an illumination optical system that corresponds to the beam of the selected wavelength band.

2. A defect inspection apparatus according to claim 1, wherein the light radiation means further includes an illumination polarization control unit to control a polarized state of the selected beam of the desired wavelength.

3. A defect inspection apparatus according to claim 1, wherein the detection means controls the polarized state of a reflected beam from the specimen radiated with the beam of the desired wavelength to form an optical image.

4. A defect inspection apparatus comprising:

a light source means for emitting beams of a plurality of wavelength bands;

a light radiation means for selecting a beam of a desired wavelength from among the beams of the plurality of wavelength bands emitted by the light source means and radiating the selected beam onto a specimen formed with a wire pattern;

a detection means for receiving an optical image of the specimen, radiated with the beam of the desired wavelength from the light radiation means and formed with the wire pattern, and for outputting an image signal;

an image processing means for processing the image signal output from the detection means to detect defects;

a control means for controlling at least one of the light source means, the light radiation means, the image detection means and the image processing means; and

an input means for inputting information associated with the specimen;

wherein the light radiation means has a plurality of illumination optical systems;

wherein the control means, based on information associated with the specimen input from the input means, selects by the light radiation means a beam of a desired wavelength from among the beams of the plurality of wavelength bands and at the same time selects one of the plurality of illumination optical systems to illuminate the specimen.

5. A defect inspection apparatus according to claim 4, wherein the plurality of illumination optical systems provided by the light radiation means include a bright-field illumination optical system, a dark-field illumination optical system, and a combination of the bright-field illumination optical system and the dark-field illumination optical system.

6. A defect inspection apparatus comprising:

a light source means for emitting beams of a plurality of wavelength bands;

a light radiation means for selecting a beam of a desired wavelength from among the beams of the plurality of wavelength bands emitted by the light source means, adjusting a polarized state of the selected beam of the desired wavelength, and radiating the adjusted beam onto a specimen formed with a wire pattern;

a detection means for receiving an optical image of the specimen, radiated with the beam of the desired wavelength from the light radiation means and formed with the wire pattern, and for outputting an image signal;

an image processing means for processing the image signal output from the detection means to detect defects; and

a control means for controlling the selection of the beam of the desired wavelength performed by the light radiation means and for controlling the adjustment of the polarized state performed by the light radiation means.

7. A defect inspection apparatus according to claim 6, further including an input means for inputting information on the specimen;

wherein the control means controls the light radiation means according to the information on the specimen entered from the input means.

8. A defect inspection methods comprising the steps of:

selecting a beam of a desired wavelength from among beams of a plurality of wavelength bands emitted from a light source and radiating the selected beam onto a specimen formed with a wire pattern;

photographing an optical image of the specimen formed with the wire pattern and radiated with the beam of the desired wavelength to obtain an image signal;

processing the obtained image signal to detect defects;

wherein in the step of selecting the beam of the desired wavelength and radiating the selected beam onto the specimen, according to information on a material of the wire pattern of the specimen, a desired wavelength band of the beam to be radiated onto the specimen and an illumination optical system corresponding to the beam of the desired wavelength band are selected and the selected beam of the desired wavelength band is radiated, through the corresponding illumination optical system, onto the specimen formed with the wire pattern.

9. A defect inspection methods according to claim 8, wherein the illumination optical system corresponding to the beam of the desired wavelength band is selected from among a plurality of bright-field optical systems.

10. A defect inspection methods comprising the steps of:

selecting a beam of a desired wavelength from among beams of a plurality of wavelength bands emitted from a light source;

controlling a polarized state of the selected beam of the desired wavelength and radiating the beam onto a specimen formed with a wire pattern;

photographing an optical image of the specimen radiated with the beam of the desired wavelength and formed with the wire pattern by controlling the polarized state of the beam; and

processing the photographed and detected image.

11. A defect inspection methods according to claim 10, wherein the selection of the beam of the desired wavelength, the control of the polarized state of the beam to be radiated onto the specimen, the photographing of the specimen by controlling the polarized state, and the detection of the defects are executed by referencing past data accumulated in a database by using information on a material of the wire pattern.

12. A defect inspection methods according to claim 10, wherein in the radiating step, the beams of the plurality of wavelength bands emitted from the light source are separated into a plurality of beams according to the wavelength bands and the beams of the plurality of separated wavelength bands are radiated onto different locations on the specimen.

13. A defect inspection methods according to claim 12, wherein in the photographing step, with the beams of the plurality of separated wavelength bands radiated onto different locations on the specimen, optical images of different locations on the specimen are photographed.