Surface inspecting apparatus and method

• US 6,587,192 B2
• Filed: 02/20/2001
• Issued: 07/01/2003
• Est. Priority Date: 02/25/2000
• Status: Expired due to Fees

• Current Assignee: Kabushiki Kaisha Topcon
• Original Assignee: Kabushiki Kaisha Topcon
• Inventors: Isozaki, Hisashi, Shida, Yutaka
• Primary Examiner(s): Epps, Georgia
• Assistant Examiner(s): Hasan, M.
• Application Number:
  US09/785,530
• Publication Number:
  US 20020005945A1
• Time in Patent Office: 861 Days
• Field of Search: 356/237.1, 356/237.2, 356/237.3, 356/237.4, 356/237.5, 250/559.4, 250/559.41, 250/559.42, 250/559.45
• US Class Current: 356/237.2
• CPC Class Codes: G01N 21/9501 Semiconductor wafers manufacturing processes per se of semiconductor devices implementing a measuring step H01L22/10

Abstract

A surface inspection apparatus includes a light source section for emitting first and second luminous fluxes; a first irradiation optical system which irradiates the first luminous flux on an inspected object at a first irradiation angle; a second irradiation optical system which irradiates the second luminous flux on an inspected object at a second irradiation angle; a light receiving optical system for receiving scattered light of the first and second luminous fluxes; first and second light receiving sections for converting the scattered light of the first and second luminous fluxes into first and second light receiving signals, respectively; a displacement section for relatively displacing an inspected object and an irradiation luminous flux of the irradiation optical system; and a discrimination section for discriminating the kind of inspection object based on the strength of the scattered light and the scattered range of the first and second light receiving signals.

Claims

1. A surface inspection apparatus comprising:

a light source section for emitting a first luminous flux and a second luminous flux;

a first irradiation optical system in which the first luminous flux is irradiated on the surface of an inspected object at a first irradiation angle;

a second irradiation optical system in which the second luminous flux is irradiated on the surface of an inspected object at a second irradiation angle different from the first irradiation angle;

a light receiving optical system for receiving scattered light for the first luminous flux irradiated by the first irradiation optical system and produced from an inspection object on the surface of an inspected object and scattered light of the second luminous flux irradiated by the second irradiation optical system and produced from an inspection object on the surface of an inspected object;

a first light receiving section for converting the scattered light of the first luminous flux received by the light receiving optical system into a first light receiving signal;

a second light receiving section for converting the scattered light of the second luminous flux received by the light receiving optical system into a second light receiving signal;

a displacement section for relatively displacing an inspected object and an irradiation luminous flux of the irradiation optical system; and

a discrimination section for discriminating the kind of an inspection object on an inspected object on the basis of the strength of the scattered light of the first and second light receiving signals, and the scattered range of the scattered light of the first and second light receiving signals,

wherein the discrimination section carries out the scattered light quantity ratio process for obtaining the strength ratio of the scattered light of the first and second light receiving signals, and the scattered range detection process for obtaining the scattered range of the scattered light according to whether or not the first and second light receiving signals is above a predetermined level.

2. A surface inspection apparatus according to claim 1, wherein the first characteristic of the first luminous flux emitted by the light source section and the second characteristic of the second luminous flux emitted by the light source section lie in wavelength of luminous flux or polarized-light component.

3. A surface inspection apparatus according to claim 1, wherein a first irradiation angle of the first irradiation optical system is set to be smaller than a second irradiation angle of the second irradiation optical system.

4. A surface inspection apparatus according to claim 1, wherein the discrimination section carries out the discrimination processes as described below every position of the surface of an inspected object:

(A) when judgment is made that the scattered light generated from the inspection object is present in only one of either the first light receiving signal or the second light receiving signal, the first discrimination process for discriminating that the kind of the inspection object is a first inspection object is carried out;

(B) when judgment is made that the scattered light generated from the inspection object is present in both the first light receiving signal and the second light receiving signal, the ratio between the strength of scattered light of the first light receiving signal and the strength of scattered light of the second light receiving signal is obtained, and if the ratio is at a level above a predetermined level, the second discrimination process for discriminating that the kind of the inspection object is a second inspection object is carried out;

(C) when judgment is made that the scattered light generated from the inspection object is present in both the first light receiving signal and the second light receiving signal, the ratio between the strength of scattered light of the first light receiving signal and the strength of scattered light of the second light receiving signal is obtained, and the ratio is at a level above a predetermined level, and further, a first function due to the strength of scattered light and the scattered range of scattered light of the first light receiving signal and a second function due to the strength of scattered light and the scattered range of scattered light of the second light receiving signal are obtained, and when the ratio therebetween is at a value above a predetermined value, the third discrimination process for discriminating that the kind of the inspection object is a third inspection object is carried out; and

(D) when judgment is made that scattered light generated from the inspection object not falling under the process is present in the first light receiving signal or the second light receiving signal, the discrimination process for discriminating that the kind of the inspection object is normal foreign matter is carried out.

5. A surface inspection apparatus according to claim 1, wherein the kind of the inspection object discriminated by the discrimination section is decided according to what kind the inspected object is.

6. A surface inspection apparatus comprising:

a tight source section for emitting a first luminous flux and a second luminous flux;

a first irradiation optical system in which the first luminous flux is irradiated on the surface of an inspected object at a first irradiation angle;

a second irradiation optical system in which the second luminous flux is irradiated on the surface of an inspected object at a second irradiation angle different from the first irradiation angle;

a light receiving optical system for receiving scattered light of the first luminous flux irradiated by the first irradiation optical system and produced from an inspection object on the surface of an inspected object and scattered light of the second luminous flux irradiated by the second irradiation optical system and produced from an inspection object on the surface of an inspected object;

a first light receiving section for converting the scattered light of the first luminous flux received by the light receiving optical system into a first light receiving signal;

a second light receiving section for converting the scattered light of the second luminous flux received by the light receiving optical system into a second light receiving signal;

a displacement section for relatively displacing an inspected object and an irradiation luminous flux of the irradiation optical system; and

a discrimination section for discriminating the kind of an inspection object on an inspected object on the basis of the strength of the scattered light of the first and second light receiving signals, and the scattered range of the scattered light of the first and second light receiving signals,

wherein the kind of the inspection object discriminated by the discrimination section is decided according to what kind the inspected object is, and

wherein where an inspected object is a bare wafer, the discrimination section discriminates COP (crystal defect) as a first inspection object by a first discrimination process, discriminates COP (crystal defect) as a second inspection object by a second discrimination process, and discriminates a thin foreign matter as a third inspection object by a third discrimination process.

7. A surface inspection apparatus comprising:

a light source section for emitting a first luminous flux and a second luminous flux;

a first irradiation optical system in which the first luminous flux is irradiated on the surface of an inspected object at a first irradiation angle;

a second irradiation optical system in which the second luminous flux is irradiated on the surface of an inspected object at a second irradiation angle different from the first irradiation angle;

a light receiving optical system for receiving scattered light of the first luminous flux irradiated by the first irradiation optical system and produced from an inspection object on the surface of an inspected object and scattered light of the second luminous flux irradiated by the second irradiation optical system and produced from an inspection object on the surface of an inspected object;

a first light receiving section for converting the scattered light of the first luminous flux received by the light receiving optical system into a first light receiving signal;

a second light receiving section for converting the scattered light of the second luminous flux received by the light receiving optical system into a second light receiving signal;

a displacement section for relatively displacing an inspected object and an irradiation luminous flux of the irradiation optical system; and

a discrimination section for discriminating the kind of an inspection object on an inspected object on the basis of the strength of the scattered light of the first and second light receiving signals, and the scattered range of the scattered light of the first and second light receiving signals,

wherein the kind of the inspection object discriminated by the discrimination section is decided according to what kind the inspected object is, and

wherein where an inspected object is a semiconductor wafer after CMP (chemical mechanical process) process of a wafer with a membrane, the discrimination section discriminates COP (crystal defect) as a first foreign matter by a first discrimination process, discriminates a micro-scratch as a second foreign matter by a second discrimination process, and discriminates a micro-scratch as a third foreign matter by a third discrimination process.

8. A surface inspection method, in a method for discriminating a foreign matter in a state for relatively displacing an inspected object and an irradiation luminous flux of an irradiation optical system by a displacement section, comprising:

a step of irradiating a first luminous flux on the surface of an inspected object at a first irradiation angle, and irradiating a second luminous flux on the surface of an inspected object at a second irradiation angle different from the first irradiation angle;

a step of receiving scattered light of the first luminous flux and the second luminous flux irradiated by the irradiation optical system and produced from an inspection object on the surface of an inspected object by the first light receiving section and the second light receiving section;

a step of converting the scattered light of the first luminous flux received by the first light receiving section into a first light receiving signal, and converting the scattered light of the second luminous flux received by the second light receiving section into a second light receiving signal; and

a step of discriminating the kind of an inspection object on an inspected object on the basis of the strength of the scattered light of the first and second light receiving signals, and the scattered range of the scattered light of the first and second light receiving signals.

9. A surface inspection method comprising:

a step of emitting a first luminous flux and a second luminous flux;

a step of irradiating the first luminous flux on the surface of an inspected object at a first irradiation angle;

a step of irradiating the second luminous flux on the surface of an inspected object at a second irradiation angle different from the first irradiation angle;

a step of receiving scattered light of the first luminous flux produced from an inspection object on the surface of an inspected object and scattered light of the second luminous flux produced from an inspection object on the surface of an inspected object;

a step of converting the scattered light of the first luminous flux into a first light receiving signal;

a step of converting the scattered light of the second luminous flux into a second light receiving signal;

a step of relatively displacing an inspected object and an irradiation luminous flux; and

a step of discriminating the kind of an inspection object on an inspected object on the basis of the strength of the scattered light of the first and second light receiving signals, and the scattered range of the scattered light of the first and second light receiving signals.

10. A surface inspection method according to claim 9, wherein the first characteristic of the first luminous flux and the second characteristic of the second luminous flux lie in wavelength of luminous flux or polarized-light component.

11. A surface inspection method according to claim 9, wherein a first irradiation angle is set to be smaller than a second irradiation angle.

12. A surface inspection method according to claim 9, wherein in the discrimination step, there carries out carries out the scattered light quantity ratio process for obtaining the strength ratio of the scattered light of the first and second light receiving signals, and the scattered range detection process for obtaining the scattered range of the scattered light according to whether or not the first and second light receiving signals is above a predetermined level.

13. A surface inspection method according to claim 9, wherein in the discrimination step, there carries out the discrimination processes as described below every position of the surface of an inspected object:

(A) when judgment is made that the scattered light generated from the inspection object is present in only one of either the first light receiving signal or the second light receiving signal, the first discrimination process for discriminating that the kind of the inspection object is a first inspection object is carried out;

(B) when judgment is made that the scattered light generated from the inspection object is present in both the first light receiving signal and the second light receiving signal, the ratio between the strength of scattered light of the first light receiving signal and the strength of scattered light of the second light receiving signal is obtained, and if the ratio is at a level above a predetermined level, the second discrimination process for discriminating that the kind of the inspection object is a second inspection object is carried out;

(C) when judgment is made that the scattered light generated from the inspection object is present in both the first light receiving signal and the second light receiving signal, the ratio between the strength of scattered light of the first light receiving signal and the strength of scattered light of the second light receiving signal is obtained, and the ratio is at a level above a predetermined level, and further, a first function due to the strength of scattered light and the scattered range of scattered light of the first light receiving signal and a second function due to the strength of scattered light and the scattered range of scattered light of the second light receiving signal are obtained, and when the ratio therebetween is at a value above a predetermined value, the third discrimination process for discriminating that the kind of the inspection object is a third inspection object is carried out; and

(D) when judgment is made that scattered light generated from the inspection object not falling under the process is present in the first light receiving signal or the second light receiving signal, the discrimination process for discriminating that the kind of the inspection object is normal foreign matter is carried out.

14. A surface inspection method according to claim 9, wherein in the discrimination step, the kind of the inspection object to be discriminated is decided according to what kind the inspected object is.

15. A surface inspection method according to claim 14, wherein where an inspected object is a bare wafer, a first discrimination process discriminates COP (crystal defect) as a first inspection object, a second discrimination process discriminates COP (crystal defect) as a second inspection object, and a third discrimination process discriminates a thin foreign matter as a third inspection object.

16. A surface inspection method according to claim 14, wherein where an inspected object is a semiconductor wafer after CMP (chemical mechanical process) process of a wafer with a membrane, a first discrimination process discriminates COP (crystal defect) as a first foreign matter, a second discrimination process discriminates a micro-scratch as a second foreign matter, and a third discrimination process discriminates a micro-scratch as a third foreign matter.

17. A surface inspection apparatus comprising:

a means for emitting a first luminous flux and a second luminous flux;

a means for irradiating the first luminous flux on the surface of an inspected object at a first irradiation angle;

a means for irradiating the second luminous flux on the surface of an inspected object at a second irradiation angle different from the first irradiation angle;

a means for receiving scattered light of the first luminous produced from an inspection object on the surface of an inspected object and scattered light of the second luminous flux produced from an inspection object on the surface of an inspected object;

a means for converting the scattered light of the first luminous flux received by the light receiving means into a first light receiving signal;

a means for converting the scattered light of the second luminous flux into received by the light receiving means a second light receiving signal;

a means for relatively displacing an inspected object and an irradiation luminous flux; and

a means for discriminating the kind of an inspection object on an inspected object on the basis of the strength of the scattered light of the first and second light receiving signals, and the scattered range of the scattered light of the first and second light receiving signals.

18. A surface inspection apparatus according to claim 17, wherein the first characteristic of the first luminous flux emitted by the light emitting means and the second characteristic of the second luminous flux emitted by the light emitting means lie in wavelength of luminous flux or polarized-light component.

19. A surface inspection apparatus according to claim 18, wherein a first irradiation angle is set to be smaller than a second irradiation angle.

20. A surface inspection apparatus according to claim 17, wherein in the discrimination means, there carries out the scattered light quantity ratio process for obtaining the strength ratio of the scattered light of the first and second light receiving signals, and the scattered range detection process for obtaining the scattered range of the scattered light according to whether or not the first and second light receiving signals is above a predetermined level.

21. A surface inspection apparatus according to claim 17, wherein in the discrimination means, there carries out the discrimination processes as described below every position of the surface of an inspected object:

(A) when judgment is made that the scattered light generated from the inspection object is present in only one of either the first light receiving signal or the second light receiving signal, the first discrimination process for discriminating that the kind of the inspection object is a first inspection object is carried out;

(B) when judgment is made that the scattered light generated from the inspection object is present in both the first light receiving signal and the second light receiving signal, the ratio between the strength of scattered light of the first light receiving signal and the strength of scattered light of the second light receiving signal is obtained, and if the ratio is at a level above a predetermined level, the first discrimination process for discriminating that the kind of the inspection object is a second inspection object is carried out;

(C) when judgment is made that the scattered light generated from the inspection object is present in both the first light receiving signal and the second light receiving signal, the ratio between the strength of scattered light of the first light receiving signal and the strength of scattered light of the second light receiving signal is obtained, and the ratio is at a level above a predetermined level, and further, a first function due to the strength of scattered light and the scattered range of scattered light of the first light receiving signal and a second function due to the strength of scattered light and the scattered range of scattered light of the second light receiving signal are obtained, and when the ratio therebetween is at a value above a predetermined value, the third discrimination process for discriminating that the kind of the inspection object is a third inspection object is carried out; and

(D) when judgment is made that scattered light generated from the inspection object not falling under the process is present in the first light receiving signal or the second light receiving signal, the discrimination process for discriminating that the kind of the inspection object is normal foreign matter is carried out.

22. A surface inspection apparatus according to claim 17, wherein the kind of the inspection object discriminated by the discrimination means is decided according to what kind the inspected object is.

23. A surface inspection apparatus according to claim 22, wherein where an inspected object is a bare wafer, the discrimination means discriminates COP (crystal defect) as a first inspection object by a first discrimination process, discriminates COP (crystal defect) as a second inspection object by a second discrimination process, and discriminates a thin foreign matter as a third inspection object by a third discrimination process.

24. A surface inspection apparatus according to claim 22, wherein where an inspected object is a semiconductor wafer after CMP (chemical mechanical process) process of a wafer with a membrane, the discrimination means discriminates COP (crystal defect) as a first foreign matter by a first discrimination process, discriminates a micro-scratch as a second foreign matter by a second discrimination process, and discriminates a micro-scratch as a third foreign matter by a third discrimination process.