Optical measurement of bump hieght
A method of generating 3D information including: varying the distance between the sample and an objective lens of the optical microscope at pre-determined steps; capturing an image at each pre-determined step; determining a characteristic value of each pixel in each captured image; determining, for each captured image, the greatest characteristic value across a first portion of pixels in the captured image; comparing the greatest characteristic value for each captured image to determine if a surface of the sample is present at each pre-determined step; determining a first captured image that is focused on an apex of a bump of the sample; determining a second captured image that is focused on a first surface of the sample based on the characteristic value of each pixel in each captured image; and determining a first distance between the apex of the bump and the first surface.
1. A method of generating three-dimensional (3-D) information of a sample using an optical microscope, the method comprising:
varying the distance between the sample and an objective lens of the optical microscope at pre-determined steps;
capturing an image at each pre-determined step, wherein a first surface of the sample and a second surface of the sample are within a field of view of each of the captured images;
determining a characteristic value of each pixel in each captured image, wherein the characteristic value of each pixel is selected from the group consisting of: intensity, contrast and fringe contrast;
determining, for each captured image, the greatest characteristic value across a first portion of pixels in the captured image;
comparing the greatest characteristic value for each captured image to determine if a surface of the sample is present at each pre-determined step;
determining a first captured image that is focused on an apex of a bump of the sample;
determining a second captured image that is focused on a first surface of the sample based on the characteristic value of each pixel in each captured image; and
determining a first distance between the apex of the bump and the first surface, wherein the bump is a metal bump.
2. The method of claim 1 , wherein the optical microscope includes a stage, wherein the sample is supported by the stage, wherein the optical microscope is adapted to communicate with a computer system, wherein the computer system includes a memory device that is adapted to store each captured image, and wherein the optical microscope is selected from the group consisting of: a confocal microscope, a structured illumination microscope, and an interferometer.
3. The method of claim 1 , wherein the determining of the first captured image further comprises:
determining a maximum characteristic value for each x-y pixel location, within a second portion of x-y pixel locations, across all captured images, wherein the second portion of x-y pixel locations includes at least some of the x-y pixel locations included in each captured image;
determining a subset of the captured images, wherein only captured images that include a x-y pixel location maximum characteristic value are included in the subset; and
determining that, of all captured images within the subset of captured images, the first captured image is focused on a highest z-position compared to all other captured images within the subset of captured images.
4. The method of claim 1 , wherein the first portion of pixels includes all pixels included in the captured image.
5. The method of claim 1 , wherein the first portion of pixels includes less than all pixels included in the captured image.
6. The method of claim 3 , wherein the second portion of pixels includes all pixels included in the captured image.
7. The method of claim 3 , wherein the second portion of pixels includes less than all pixels included in the captured image.
8. The method of claim 1 , wherein the first portion of pixels does not receive reflected light from the metal bump.
9. The method of claim 3 , wherein the second portion of pixels receive reflected light from the apex of the metal bump.
10. The method of claim 3 , wherein the spacial relationship between the first portion of pixels to the second portion of pixels is fixed.
11. The method of claim 3 , wherein the second portion of pixels are contiguous and centered on the apex of the bump.
12. The method of claim 1 , wherein the first surface is a top surface of a passivation layer.
13. A method of generating three-dimensional (3-D) information of a sample using an optical microscope, the method comprising:
varying the distance between the sample and an objective lens of the optical microscope at pre-determined steps;
capturing an image at each pre-determined step, wherein a first surface of the sample and a second surface of the sample are within a field of view of each of the captured images;
determining a characteristic value of each pixel in each captured image, wherein the characteristic value of each pixel is selected from the group consisting of: intensity, contrast and fringe contrast;
determining, for each captured image, a count of pixels that have a characteristic value within a first range across a first portion of pixels, wherein all pixels that do not have a characteristic value within the first range are not included in the count of pixels;
determining if a surface of the sample is present at each pre-determined step based on the count of pixels for each captured image;
determining a first captured image that is focused on an apex of a bump of the sample;
determining a second captured image that is focused on a first surface of the sample based on the characteristic value of each pixel in each captured image; and
determining a first distance between the apex of the bump and the first surface, wherein the bump is a metal bump.
14. The method of claim 13 , wherein the optical microscope includes a stage, wherein the sample is supported by the stage, wherein the optical microscope is adapted to communicate with a computer system, wherein the computer system includes a memory device that is adapted to store each captured image, and wherein the optical microscope is selected from the group consisting of: a confocal microscope, a structured illumination microscope, and an interferometer.
15. The method of claim 13 , wherein the determining of the first captured image further comprises:
determining a maximum characteristic value for each x-y pixel location, within a second portion of x-y pixel locations, across all captured images, wherein the second portion of x-y pixel locations includes at least some of the x-y pixel locations included in each captured image;
determining a subset of the captured images, wherein only captured images that include a x-y pixel location maximum characteristic value are included in the subset; and
determining that, of all captured images within the subset of captured images, the first captured image is focused on the highest z-position compared to all other captured images within the subset of captured images.
16. The method of claim 13 , wherein the first portion of pixels includes all pixels included in the captured image.
17. The method of claim 13 , wherein the first portion of pixels includes less than all pixels included in the captured image.
18. The method of claim 15 , wherein the second portion of pixels includes all pixels included in the captured image.
19. The method of claim 15 , wherein the spacial relationship between the first portion of pixels to the second portion of pixels is fixed.
20. The method of claim 15 , wherein the second portion of pixels are contiguous and centered on the apex of the bump.
21. A method of generating three-dimensional (3-D) information of a sample using an optical microscope, the method comprising:
varying the distance between the sample and an objective lens of the optical microscope at pre-determined steps;
capturing an image at each pre-determined step, wherein a first surface of the sample and a second surface of the sample are within a field of view of each of the captured images;
determining a characteristic value of each pixel in each captured image, wherein the characteristic value of each pixel is selected from the group consisting of: intensity, contrast and fringe contrast;
determining a z-position of an apex of a bump of the sample;
determining a first captured image that is focused on a first surface of the sample based on the characteristic value of each pixel in each captured image; and
determining a first distance between the apex of the bump and the first surface, wherein the bump is a metal bump.
22. The method of claim 21 , wherein the determining of the z-position of the apex comprises:
identifying a plurality of x, y, z pixel locations across all captured images, wherein the plurality of x, y, z pixel locations are associated with a top surface of the bump;
applying a best fit algorithm to a generate a continuous 3-D estimate of the top surface of the bump; and
determining a maximum height of the continuous 3-D estimate.