Method and apparatus for inspecting defects

• US 7,161,671 B2
• Filed: 07/07/2004
• Issued: 01/09/2007
• Est. Priority Date: 10/29/2001
• Status: Expired due to Term

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Maeda, Shunji, Shibata, Yukihiro
• Primary Examiner(s): Toatley, Jr.; Gregory J.
• Assistant Examiner(s): Nguyen; Sang H.
• Application Number:
  US10/885,077
• Publication Number:
  US 20040257560A1
• Time in Patent Office: 916 Days
• Field of Search: 3562371-2376, 356/394, 356367-369, 250/559.42, 250/559.48, 250/548, 382/149, 182/149, 430/30, 219/121.68, 219/121.6
• US Class Current: 356/237.2
• CPC Class Codes: G01N 21/21 Polarisation-affecting properties G01N21/19 takes precedence
• CPC Class Codes: G01N 21/33 using ultraviolet light G01N21/39 takes precedence
• CPC Class Codes: G01N 21/9501 Semiconductor wafers manufacturing processes per se of semiconductor devices implementing a measuring step H01L22/10
• CPC Class Codes: G01N 21/95607 using a comparative method

Abstract

Laser lights having a plurality of wavelengths from DUV to VUV range are used to inspect defects of a pattern at high speeds and in a high sensitivity using high light-output lasers, while solving a temporal/spatial coherence problem caused by using lasers as light source. This reduces the laser light temporal/spatial coherence. Further, to correct chromatic aberration caused by illumination with VUV and DUD lights, the lights of the VUV and DUV wavelengths are arranged in a coaxial illumination relation. The chromatic aberration left uncorrected is detected such that a detection optical path is branched into two optical path systems corresponding to respective wavelengths and an image sensor is placed on an image plane of each wavelength.

Claims

1. A method for inspecting a defect, comprising the steps of:

irradiating a pulse laser beam emitted from a pulse-oscillating laser light source to a sample by dark field illumination;

sensing light reflected from said sample caused by the irradiation of said pulse laser beam by said dark field illumination with a sensor; and

detecting a defect on said sample by processing a signal output from said sensor;

wherein said pulse laser beam which irradiates said sample is divided in time into plural pulses from said pulse laser beam emitted from said pulse-oscillating laser light source, and said plural pulses are irradiated to substantially a same position on said sample.

2. A defect inspecting method as claimed in claim 1, wherein a pattern is formed on said sample, and in the step of detecting, a defect of said pattern is detected.

3. A defect inspecting method as claimed in claim 1, wherein said pulse laser beam which irradiates said sample is divided into plural pulses from said pulse laser beam emitted from said pulse-oscillating laser light source by passing through a plurality of optical paths having different optical path lengths from each other.

4. A method for inspecting a defect comprising the steps of:

irradiating a pulse laser beam emitted from a pulse-oscillating laser light source to a sample by dark field illumination;

sensing, with a sensor, light from said sample to which the pulse laser beam is irradiated; and

detecting a defect on said sample by processing a signal output from said sensor;

wherein of said pulse laser beam which irradiates said sample is divided in time into plural pulses from said pulse laser beam emitted from said pulse-oscillating laser light source, and amplitudes of said plural pulses are substantially equal to one another.

5. A defect inspecting method as claimed in claim 4, wherein a pattern is formed on said sample, and in the step of detecting, a defect of said pattern is detected.

6. A defect inspecting method as claimed in claim 4, wherein said pulse laser beam which irradiates said sample is divided into plural pulses from said pulse laser beam emitted from said pulse-oscillating laser light source by passing through a plurality of optical paths having different optical path lengths from each other.

7. A defect inspecting method as claimed in claim 4, wherein said sensor is a time delay integration sensor.

8. A method for inspecting a defect comprising the steps of:

irradiating plural laser beams having different wavelengths from each other emitted from plural laser light sources to a sample;

splitting reflection light reflected from said sample to which said plural laser beams are irradiated by each of the plural wavelengths;

sensing each of said split reflection light with sensors;

synthesizing detection signals output from said sensors with each other corresponding to each of the plural wavelengths; and

detecting a defect on said sample by processing said synthesized detection signals;

wherein said plural laser beams include at least one pulse laser beam emitted from a pulse-oscillating laser light source, said at least one pulse laser beam being divided in time into plural pulses.

9. A defect inspecting method as claimed in claim 8, wherein a pattern is formed on said sample, and in the step of detecting, a defect of said pattern is detected.

10. A defect inspecting method as claimed in claim 8, wherein said pulse laser beam which irradiates said sample is divided into plural pulses from said pulse laser beam emitted from said pulse-oscillating laser light source by passing through a plurality of optical paths having different optical path lengths from each other.

11. A method for inspecting a defect of a specimen, comprising the steps of:

irradiating a pulse laser beam to a sample, said pulse laser beam being produced by a pulse-oscillating laser light source which emits said pulse laser beam;

sensing light reflected from said sample by the irradiation with a sensor; and

detecting a defect having a dimension of 30 nm to 20 nm by processing an output signal from said sensor;

wherein said pulse laser beam emitted from said pulse-oscillating laser light source is so arranged that plural pulses are irradiated to substantially a same portion on said sample within a range of a storage time of said sensor.

12. A defect inspecting method as claimed in claim 11, wherein a wavelength of said pulse-oscillating laser light is 157 nm.

13. A defect inspecting method as claimed in clam 11, wherein said pulse-oscillating laser light source is a vacuum ultraviolet pulse-oscillating laser light source.