Particle detecting apparatus using two light beams

• US 6,266,137 B1
• Filed: 03/30/1999
• Issued: 07/24/2001
• Est. Priority Date: 04/10/1998
• Status: Expired due to Fees

• Current Assignee: NEC Electronics Corporation (Renesas Electronics Corporation)
• Original Assignee: NEC Corporation
• Inventors: Morinaga, Shirou
• Primary Examiner(s): Pham, Hoa Q.
• Application Number:
  US09/281,285
• Time in Patent Office: 847 Days
• Field of Search: 356/237.1, 356/237.2, 356/237.3, 356/237.4, 356/237.5, 356/237.6, 356/239.1, 356/239.3, 356/239.7, 356/394, 356/319, 356/328, 356/326, 356/338, 250/559.41, 385/12
• US Class Current: 356/237.1
• CPC Class Codes: G01N 21/8806 Specially adapted optical and illumination features

Abstract

A particle detecting apparatus for testing a substrate with a film on its surface includes a light source section, an optical system, a light quantity measuring section and an operation section. The light source section emits first and second light beams respectively having first and second wavelengths which are different from each other. The optical system directs the first and second light beams to an incident point on the substrate, wherein the first and second light beams are scattered on the substrate to produce first and second scattered light beams. The light quantity measuring section measures a quantity of the first scattered light beam and a quantity of the second scattered light beam. The operation section detects a foreign particle on or in the film based on the first scattered light beam quantity and the second scattered light beam quantity measured by the light quantity measuring section.

Claims

1. A particle detecting apparatus for testing a substrate and a film provided on a top surface of said substrate, comprising:

a light source section for emitting first and second light beams respectively having first and second wavelengths which are different from each other, wherein said first and second light beams are directed to said substrate at a same time and orthogonal to said top surface;

an optical system for directing said first and second light beams to an incident point on said substrate, wherein said first and second light beams are scattered by said top surface of said substrate to produce first and second scattered light beams;

a light quantity measuring section for measuring a quantity of said first scattered light beam and a quantity of said second scattered light beam, wherein said light quantity measuring section comprises;

a beam collecting section for collecting said first scattered light beam and said second scattered light beam, comprising a set of optical fibers, wherein a first end of each of said optical fibers is arranged on a semi-spherical surface having the incident point as a center and a second end is connected to a light wave guide for guiding said first scattered light beam and said second scattered light beam;

a spectroscope for separating said first scattered light beam and said second scattered light beam guided by said light wave guide;

a first measuring section for measuring said quantity of said first scattered light beam separated by said spectroscope; and

a second measuring section for measuring said quantity of said second scattered light beam separated by said spectroscope; and

an operation section for detecting a foreign particle located on said film and in said film, and determining a diameter of said foreign particle and a depth of said foreign particle, based on said first scattered light beam quantity and said second scattered light beam quantity measured by said light quantity measuring section and independent of incidence angles of said first and second light beams.

2. A particle detecting apparatus according to claim 1, wherein said beam collecting section and said light wave guide are made as a unit, and said light wave guide comprises said set of optical fibers.

3. A particle detecting apparatus according to claim 1, wherein said beam collecting section further includes:

a set of lenses, each of which is provided for one of said optical fibers in front of said first end.

4. A particle detecting apparatus according to claim 1, wherein a wavelength of said first light beam is smaller than a grain diameter of said foreign particle.

5. A particle detecting apparatus according to claim 1, wherein the wavelength of said first light beam is shorter than 488 nm.

6. A particle detecting apparatus according to claim 1, wherein a wavelength of said first light beam is smaller than that of said second light beam, and the wavelength of said second light beam is smaller than a grain diameter of said foreign particle.

7. A particle detecting apparatus according to claim 1, wherein said first light beam is irregularly scattered by said foreign particle on a surface of said film to create a first irregularly scattered light beam and said second light beam is irregularly scattered by said top surface of said substrate to create a second irregularly scattered light beam.

8. A particle detecting apparatus according to claim 1,

wherein a thickness of said film varies,

wherein said light source section emits a third light beam having a third wavelength different from said wavelengths of said first and second light beams and directed to said substrate at a same time as said first and second light beams,

wherein said third light beam is scattered by said substrate to produce a third scattered light beam,

wherein said light quantity measuring section measures a quantity of said third scattered light beam,

wherein said operation section detects a foreign particle located on said film, a foreign particle located in said film, and determines a thickness of said film, a diameter of said foreign particle and a depth of said foreign particle.

9. A particle detecting apparatus for testing a substrate and a film provided on a top surface of said substrate, comprising:

a light source section for emitting first and second light beams respectively having first and second wavelengths which are different from each other, wherein said first and second light beams are alternately directed to said substrate and orthogonal to said top surface;

an optical system for directing said first and second light beams to an incident point on said substrate, wherein said first and second light beams are scattered by said top surface of said substrate to produce first and second scattered light beams;

a light quantity measuring section for measuring a quantity of said first scattered light beam and a quantity of said second scattered light beam, wherein said light quantity measuring section comprises;

a beam collecting section for collecting said first scattered light beam and said second scattered light beam, comprising a set of optical fibers, wherein a first end of each of said optical fibers is arranged on a semi-spherical surface having the incident point as a center and a second end is connected to a light wave guide for guiding said first scattered light beam and said second scattered light beam; and

a measuring section for measuring said quantity of said first scattered light beam and said quantity of said second scattered light beam by said light wave guide; and

an operation section for detecting a foreign particle located on said film and in said film, and determining a diameter of said foreign particle and a depth of said foreign particle, based on said first scattered light beam quantity and said second scattered light beam quantity measured by said light quantity measuring section and independent of incidence angles of said first and second light beams.

10. A particle detecting apparatus according to claim 9, wherein said beam collecting section further comprises:

a set of lenses, each of which is provided for one of said optical fibers in front of said first end.

11. A method for detecting a foreign particle located on and in a film formed on a top surface of a substrate, comprising:

emitting a first light beam having a first wavelength;

emitting a second light beam having a second wavelength which is different from the first wavelength, wherein said first and second light beams are directed to said substrate at a same time;

directing said first and second light beams to an incident point on said top surface of said substrate and orthogonal to said top surface;

scattering said first light beam and said second light beam by said substrate to create a first and second scattered light beam, respectively;

measuring a quantity of said first scattered light beam and a quantity of said second scattered light beam, wherein said measuring comprises;

collecting said first scattered light beam and said second scattered light beam into a set of optical fibers by lenses;

guiding said first scattered light beam and said second scattered light beam;

after guiding said first scattered light beam and said second scattered light beam, using a spectroscope to separate said first scattered light beam and said second scattered light beam; and

measuring said quantity of said first scattered light beam separated and said quantity of said second scattered light beam separated; and

detecting a foreign particle located on said film and in said film and determining a diameter of said foreign particle and a depth of said foreign particle based on said first scattered light beam quantity and said second scattered light beam quantity measured by said light quantity measuring section and independent of incidence angles of said first and second scattered light beams.

12. A method according to claim 11, wherein a wavelength of said first light beam is smaller than a grain diameter of said foreign particle.

13. A method according to claim 11, wherein the wavelength of said first light beam is shorter than 488 nm.

14. A method according to claim 11, wherein a wavelength of said first light beam is smaller than a grain diameter of said foreign particle, a wavelength of said second light beam is larger than the grain diameter of said foreign particle.

15. A method according to claim 11, wherein a wavelength of said first light beam is smaller than that of said second light beam, and the wavelength of said second light beam is smaller than a grain diameter of said foreign particle.

16. A method for detecting a foreign particle located on and in a film formed on a top surface of a substrate, comprising:

emitting a first light beam having a first wavelength;

emitting a second light beam having a second wavelength which is different from the first wavelength, wherein said first and second light beams are alternately directed to said substrate;

directing said first and second light beams to an incident point on said top surface of said substrate and orthogonal to said top surface;

scattering said first light beam and said second light beam by said substrate to create a first and second scattered light beam, respectively;

measuring a quantity of said first scattered light beam and a quantity of said second scattered light beam, wherein said measuring comprises;

collecting said first scattered light beam and said second scattered light beam into a set of optical fibers by lenses; and

measuring said quantity of said first scattered light beam and said quantity of said second scattered light beam, and

detecting a foreign particle located on said film and in said film and determining a diameter of said foreign particle and a depth of said foreign particle based on said first scattered light beam quantity and said second scattered light beam quantity measured by said light quantity measuring section and independent of incidence angles of said first and second light beams.

17. A particle detecting apparatus for testing a substrate and a film provided on a top surface of said substrate, comprising:

a light source section for emitting first and second light beams respectively having first and second wavelengths which are different from each other;

an optical system for directing said first and second light beams to an incident point on said substrate and orthogonal to said top surface, wherein said first and second light beams are scattered by said top surface of said substrate to produce first and second scattered light beams;

a light quantity measuring section for measuring a quantity of said first scattered light beam and a quantity of said second scattered light beam; and

an operation section for detecting a foreign particle located on said film and in said film, and determining a diameter of said foreign particle and a depth of said foreign particle, based on said first scattered light beam quantity and said second scattered light beam quantity measured by said light quantity measuring section and independent of incidence angles of said first and second light beams.

18. A particle detecting apparatus according to claim 17, wherein said light quantity measuring section comprises:

a beam collecting section for collecting said first scattered light beam and said second scattered light beam, comprising a set of optical fibers, wherein a first end of each of said optical fibers is arranged on a semi-spherical surface having the incident point as a center and a second end is connected to a light wave guide for guiding said first scattered light beam and said second scattered light beam;

a spectroscope for separating said first scattered light beam and said second scattered light beam guided by said light wave guide;

a first measuring section for measuring said quantity of said first scattered light beam separated by said spectroscope; and

a second measuring section for measuring said quantity of said second scattered light beam separated by said spectroscope.

19. A particle detecting apparatus according to claim 18, wherein said beam collecting section and said light wave guide are made as a unit.

20. A particle detecting apparatus according to claim 19, wherein said light wave guide comprises said set of optical fibers.

21. A particle detecting apparatus according to claim 17, wherein said foreign particle includes a void formed in said substrate.

22. A particle detecting apparatus according to claim 17, wherein said apparatus detects an existence of said foreign particle having a diameter of less than 0.1 μ

m.

23. A particle detecting apparatus according to claim 17, wherein said apparatus distinguishes between a foreign particle which includes a hole formed in said substrate and a foreign particle which comprises a substance other than a hole.