Multi-functioned optical measurement device and method for optically measuring a plurality of parameters

• US 9,395,173 B2
• Filed: 10/22/2014
• Issued: 07/19/2016
• Est. Priority Date: 10/22/2014
• Status: Active Grant

• Current Assignee: National Applied Research Laboratories (Government of The Republic of China)
• Original Assignee: National Applied Research Laboratories (Government of The Republic of China)
• Inventors: Shen, Ming-Hsing, Sze, Jyh-Rou, Chang, Chun-Li, Wang, Wei-Chung, Huang, Chi-Hung
• Primary Examiner(s): HANSEN, JONATHAN M
• Application Number:
  US14/521,440
• Publication Number:
  US 20160116271A1
• Time in Patent Office: 636 Days
• Field of Search: 356/491, 356/495, 356/503, 356/511
• US Class Current: 1/1
• CPC Class Codes: G01B 9/02042 Confocal imaging
• CPC Class Codes: G01B 9/02044 Imaging in the frequency domain, e.g. by using a spectrometer
• CPC Class Codes: G01B 9/0209 Low-coherence interferometers
• CPC Class Codes: G01J 3/447 Polarisation spectrometry
• CPC Class Codes: G01J 3/45 Interferometric spectrometry
• CPC Class Codes: G01N 21/21 Polarisation-affecting properties G01N21/19 takes precedence
• CPC Class Codes: G02B 21/0024 Confocal scanning microscopes (CSOMs) or confocal "macroscopes"; Accessories which are not restricted to use with CSOMs, e.g. sample holders

Abstract

The conventional white-light interferometer, confocal microscope, and ellipsometer are integrated as one device set in a functional sense, and the geometrical parameters conventionally measured may be deduced on the integrated device. Thus, the advantages and efficacies of equipment cost saving, on-line measuring, rapid monitoring, reduced manufacturing time, and reduced possibility of object damage during the manufacturing process may be secured, compared with the prior art.

Claims

1. An optically measurement device for measuring a plurality of parameters, comprising:

a light source unit, comprising;

an external light source;

a collimation unit, coupling the external light source to provide a collimated reference light and a collimated subject light; and

a polarizer unit, polarizing the collimated reference light and the collimated subject light, to obtain a polarized reference light and a polarized subject light, the polarized reference light propagating on a propagating path;

an aperture unit, comprising a reference light aperture, controlling a light flux of the polarized reference light, having an open and close states, and closing the propagating path of the polarized reference light when the close state is acted;

an incident light aperture, controlling a light flux of the polarized subject light; and

a measured light aperture;

a light splitting unit, diving the polarized light into the reference light and the polarized subject light and coupling the reference light and the polarized subject light onto a first path and a second path, respectively;

a measured end unit, locating on the second path, receiving and focusing the polarized subject light to the measured object, the measured object reflecting the polarized subject light passing the light-splitting unit to generate a measured light, the measured light being reflected onto a third path reverse to the second path;

a reference light processing unit, locating on the first path, and reflecting the polarized reference light to generate a collimated effect reference light onto the third path when the reference light aperture is at the open state and the optical measurement device is on an interferometer mode and the measured light and the collimated effect reference light jointly generate an interference image through the light-splitting unit, and generating a guided measured image on the third path when the reference light aperture is at the close state and the optical measurement device is on a microscope mode;

a spectrum obtaining/image acquiring unit, comprising a polarized light splitting unit, guiding the interference image on the interferometer mode and guiding the measured image on the microscope mode to obtain a first to-be-analyzed image and a second to-be-analyzed image;

a spectrum obtaining unit, receiving the first to-be-analyzed image to generate a spectrum data; and

an image acquiring unit, receiving the second to-be-analyzed image; and

a control-processing unit, performing steps of;

controlling the measured object to move along a vertical direction on the interferometer mode, and analyzing the second to-be-analyzed image, thereby securing a zero optical path difference for each of a plurality of pixels in the second to-be-analyzed image and recording the zero optical path difference for each of the plurality of pixels in the second to-be-analyzed image, thereby enabling the spectrum obtaining unit to obtain the spectrum data, thereby calculating a surface topography of the measured object according to at least one of the spectrum data and the second to-be-analyzed image;

closing the reference light aperture to enable the optical measurement device to enter the microscope mode, enabling the spectrum obtaining unit to obtain the spectrum data when the zero optical path difference exists;

activating the measured object to move along the vertical direction, analyzing a focal information of each of the plurality of pixels in the second to-be-analyzed image to obtain a full focal colorful image and a full focal gray-level image, and establishing a depth response curve;

activating the measured object to move laterally, to obtain a large-range surface profile according to the spectrum data, the depth response curve and an axial dispersion extent; and

deducing a thin-film thickness and an another surface profile according to the spectrum data when the zero optical path difference face exists, when the measured object is a substrate having a coating layer thereon,

wherein the surface profile is the another surface profile and the control-processing unit selects to only calculate and present one of the surface profile and the another surface profile.

2. The optically measurement device as claimed in claim 1, wherein:

the reference light processing unit further comprises;

an optical path difference precision shift mechanism, used for adjusting the collimated effect reference light, so that the collimated effect reference light has a zero path difference with respect to the measured light; and

a reference light reflector precision shift mechanism, used for adjusting a contrast of a plurality of interference stripes in the interference image;

the polarized light splitting unit further comprises a splitter angle adjustment rotation platform, used for adjusting an image definition of the plurality of interference stripes in the interference image; and

the optical measurement device further comprises a measured object supporting mechanism, comprising;

a piezoelectric activator, being controlled by the signal processing unit to move the measured object along the vertical direction on the interference mode; and

an precision shift platform, used for supporting the piezoelectric activator.

3. The optically measurement device as claimed in claim 1, wherein the signal processing unit activates the measured object to move along the vertical direction on the microscope mode, analyzing a high frequency information of each of the plurality of pixels in the second measured image, matching a depth of field gray value of each of the plurality of pixels, restoring an image out-focal information to form the full focal colorful image and the full focal gray-level image, and establishing the depth response curve.

4. The optically measurement device as claimed in claim 3, wherein the signal processing unit restores the image out-focal information to deduce the full focal gray-level image by using an image contrast filtering method and analyzed high frequency information of each of the plurality of pixels in the second measured image.

5. The optically measurement device as claimed in claim 1, wherein the spectrum obtaining unit acquires a spectrum message of an upper surface of the substrate and an upper face of the coating layer, respectively, and reversely deduces a distance between the upper surface of the substrate and the upper face of the coating layer of the measured object and serving the distance as a thickness of the coating layer.

6. The optically measurement device as claimed in claim 1, wherein the external light source is one of a white-light halogen lamp and an infrared lamp and has a Gaussian distributed intensity.

7. The optically measurement device as claimed in claim 1, wherein the image acquiring unit is capable of detecting one of a visible light and a non-visible light.

8. The optically measurement device as claimed in claim 1, wherein the signal processing unit applies a phase shift algorithm onto the plurality of interference stripes and analyzes a maximum strength of the plurality of interference stripes, so as to establish a surface profile information to acquire a surface profile of the measured object.

9. A method for optically measuring a plurality of parameters of an object, comprising steps of:

(a) providing a collimated reference light and a collimated subject light;

(b) polarizing the collimated reference light and the collimated subject light, to obtain a polarized reference light and a polarized subject light, the polarized reference light having a propagating path;

(c) controlling a light flux of the polarized reference light, having an open and close states, and closing the propagating path of the polarized reference light when the close state is acted;

(d) controlling a light flux of the polarized subject light;

(e) diving the polarized light into the reference light and the polarized subject light and coupling the reference light and the polarized subject light onto a first path and a second path, respectively;

(f) receiving and focusing the polarized subject light to the measured object, the measured object reflecting the polarized subject light passing the light-splitting unit to generate a measured light, the measured light being reflected onto a third path reverse to the second path;

(g) reflecting the polarized reference light to generate a collimated effect reference light onto the third path when the reference light aperture is at the open state and the optical measurement device is on an interferometer mode and the measured light and the collimated effect reference light jointly generate an interference image, and generating a guided measured image on the third path when the reference light aperture is at the close state and the optical measurement device is on a microscope mode;

(h) guiding the interference image on the interferometer mode and guiding the measured image on the microscope mode to obtain a first to-be-analyzed image and a second to-be-analyzed image;

(i) receiving the first to-be-analyzed image to generate a spectrum data, and receiving the second to-be-analyzed image;

(j) controlling the measured object to move along a vertical direction on the interferometer mode, and analyzing the second to-be-analyzed image, thereby securing a zero optical path difference for each of a plurality of pixels in the second to-be-analyzed image and recording the zero optical path difference for each of the plurality of pixels in the second to-be-analyzed image, thereby enabling the spectrum obtaining unit to obtain the spectrum data, thereby calculating a surface topography of the measured object according to at least one of the spectrum data and the second to-be-analyzed image;

(k) closing the reference light aperture to enable the optical measurement device to enter the microscope mode, enabling the spectrum obtaining unit to obtain the spectrum data when the zero optical path difference exists;

(l) activating the measured object to move along the vertical direction, analyzing a focal information of each of the plurality of pixels in the second to-be-analyzed image to obtain a full focal colorful image and a full focal gray-level image, and establishing a depth response curve;

(m) activating the measured object to move laterally, to obtain a large-range surface profile according to the spectrum data, the depth response curve and an axial dispersion extent; and

(n) deducing a thin-film thickness and an another surface profile according to the spectrum data when the zero optical path difference face exists, when the measured object is a substrate having a coating layer thereon, wherein the surface profile is the another surface profile and the control-processing unit selects to only calculate and present one of the surface profile and the another surface profile.

10. The optically measurement device as claimed in claim 9, wherein:

extent the step (c) further comprises a step of;

(c1) adjusting the collimated effect reference light, so that the collimated effect reference light has a zero path difference with respect to the measured light;

the step (e) further comprises steps of;

(e1) adjusting a contrast of a plurality of interference stripes in the interference image; and

(e2) adjusting an image definition of the plurality of interference stripes in the interference image; and

the method further comprises a step prior to the step (a) of;

(a1) supporting the piezoelectric activator and controlling the measured object to move along the vertical direction on the interference mode.

11. The method as claimed in claim 9, wherein the step (l) further comprises a step of:

(l1) analyzing a high frequency information of each of the plurality of pixels in the second measured image, matching a depth of field gray value of each of the plurality of pixels, restoring an image out-focal information to form the full focal colorful image and the full focal gray-level image, and establishing the depth response curve.

12. The method as claimed in claim 11, wherein the step (l1) further comprises a step of:

(l2) restoring the image out-focal information to deduce the full focal gray-level image by using an image contrast filtering method and analyzed high frequency information of each of the plurality of pixels in the second measured image.

13. The method as claimed in claim 9, wherein the step (n) further comprises a step of:

(n1) acquiring a spectrum message of an upper surface of the substrate and an upper face of the coating layer, respectively, and reversely deduces a distance between the upper surface of the substrate and the upper face of the coating layer of the measured object and serving the distance as a thickness of the coating layer.

14. The method as claimed in claim 9, wherein the collimated reference light is one of a white-light halogen lamp and an infrared lamp and has a Gaussian distributed intensity.

15. The method as claimed in claim 9, wherein the image acquiring unit is capable of detecting one of a visible light and a non-visible light.

16. The method as claimed in claim 9, wherein the step (k) further comprises a step of:

(k1) applying a phase shift algorithm onto the plurality of interference stripes and analyzes a maximum strength of the plurality of interference stripes, so as to establish a surface profile information to acquire a surface profile of the measured object.