Scatterfield microscopical measuring method and apparatus

• US 8,319,971 B2
• Filed: 08/06/2008
• Issued: 11/27/2012
• Est. Priority Date: 05/06/2008
• Status: Active Grant

• Current Assignee: Industrial Technology Research Institute
• Original Assignee: Industrial Technology Research Institute
• Inventors: Shyu, Deh-Ming, Chou, Sen-Yih, Ku, Yi-Sha
• Primary Examiner(s): Toatley, Gregory J
• Assistant Examiner(s): AKANBI, ISIAKA O
• Application Number:
  US12/187,057
• Publication Number:
  US 20100007881A1
• Time in Patent Office: 1,574 Days
• Field of Search: 356/445, 356/497, 356/237.1, 250/492.1, 250/201.3, 355/67, 355/43, 355/77
• US Class Current: 356/445
• CPC Class Codes: G01N 21/47 Scattering, i.e. diffuse reflection G01N21/25, G01N21/41 take precedence G01N21/55 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: G02B 21/0016 Technical microscopes, e.g. for inspection or measuring in industrial production processes
• CPC Class Codes: G02B 21/082 for incident illumination only
• CPC Class Codes: G02F 1/1313 specially adapted for a particular application
• CPC Class Codes: G02F 1/291 Two-dimensional analogue deflection
• CPC Class Codes: G02F 1/294 Variable focal length devices
• CPC Class Codes: G02F 2203/12 spatial light modulator
• CPC Class Codes: G02F 2203/28 focussing or defocussing

Abstract

The present invention provides a scatterfield microscopical measuring method and apparatus, which combine scatterfield detecting technology into microscopical device so that the microscopical device is capable of measuring the sample whose dimension is under the limit of optical diffraction. The scatterfield microscopical measuring apparatus is capable of being controlled to focus uniform and collimated light beam on back focal plane of an objective lens disposed above the sample. By changing the position of the focus position on the back focal plane, it is capable of being adjusted to change the incident angle with respect to the sample.

Claims

1. A scatterfield microscopical measuring apparatus, comprising:

a light source module, for providing a light field;

an objective lens module, being configured with a back focal plane and being disposed at a side of a sample to be inspected;

a spatial light modulator, disposed on an optical path defined between the light source module and the sample, comprising a plurality of modulation cells, wherein by controlling the light transmittance of each modulation cell, the spatial light modulator is configured to act as a simulated Fresnel lens for modulating an optical characteristic of the light field provided from the light source module to form a first beam focusing on the back focal plane while enabling the first beam to project on the sample where it is reflected back as a second beam focusing on the back focal plane; and

a detector, for recording an optical image formed on the back focal plane in response to the second beam,

wherein a center of the simulated Fresnel lens in the spatial light modulator is changed so as to change the focusing position of the first beam on the back focal plane so that an illumination angle of the first beam upon the sample is going to change accordingly.

2. The apparatus of claim 1, wherein the spatial light modulator is a liquid crystal modulator.

3. The apparatus of claim 1, further comprising:

a lens set, being disposed at a position between the light source module and the spatial light modulator to be used for collimating the light field; and

a first beam splitter, being disposed at a position between the source module and the spatial light modulator to be used for splitting the collimated light field while guiding the split light to the spatial light modulator.

4. The apparatus of claim 3, further comprising:

a polarizer, being disposed at a position between the lens set and the first beam splitter to be used for polarizing the light field.

5. The apparatus of claim 4, wherein the polarizer is a linear polarizer.

6. The apparatus of claim 1, further comprising:

a second beam splitter, being disposed at a position between the detector and the objective lens module to be used for guiding the first beam to the back focal plane; and

a lens set, being disposed at a position between the detector and the objective lens module to be used for focusing the second beam on the detector after it is scattered by the back focal plane.

7. The apparatus of claim 1, wherein the detector is a device selected from the group consisting a charge couple device (CCD) and a complementary metal-oxide-semiconductor (CMOS) device.

8. The apparatus of claim 1, wherein the optical characteristic of the light field is a characteristic selected from the amplitude of the light field, the phase of the light field and the combination thereof.

9. A scatterfield microscopical measuring method, comprising the steps of:

providing a light field from a light source module and a spatial light modulator comprising a plurality of modulation cells, wherein the spatial light modulator is disposed on an optical path defined between the light source module and a sample to be inspected;

controlling the light transmittance of each modulation cell so that the spatial light modulator is configured to act as a simulated Fresnel lens for modulating an optical characteristic of the light field for focusing the light field on a back focal plane of an objective lens module to form a first beam;

projecting the first beam on the sample to be inspected where it is reflected and forms a second beam focusing on the back focal plane;

recording an optical image formed on the back focal plane in response to the second beam; and

performing an adjustment operation for changing the focusing position of the first beam on the back focal plane, wherein changing the focusing position of the first beam is performed by changing a center of the simulated Fresnel lens in the spatial light modulator so as to change the focusing position of the first beam on the back focal plane so that an illumination angle of the first beam upon the sample is going to change accordingly.

10. The method of claim 9, wherein the optical characteristic of the light field is a characteristic selected from the amplitude of the light field, the phase of the light field and the combination thereof.

11. The method of claim 9, further comprising the step of:

collimating and polarizing the light field before the modulating of the optical characteristic.

12. The method of claim 11, wherein the polarizing of the light field is a linear polarization process.

13. The method of claim 9, wherein the modulating of the optical characteristic is performed by the use of a spatial light modulator.

14. The method of claim 13, wherein the spatial light modulator is a liquid crystal modulator.