Thin film thickness adjustments for three-dimensional interferometric measurements
View Patent ↗A 3D surface map of a workpiece is determined using an interferometric quantitative phase imaging technique. The workpiece includes a transparent thin film or layers stack. The 3D surface map is corrected based on a thickness and a refractive index of the transparent thin film or layers stack. This technique can be used with an inspection system configured to perform an interferometric quantitative phase imaging.
1 . A system comprising:
a stage configured to hold a workpiece;
an inspection system configured to perform an interferometric quantitative phase imaging; and
a processor in electronic communication with the inspection system, wherein the processor is configured to:
determine a 3D surface map that includes height information in a 2D arrangement from a phase map, wherein the workpiece includes a transparent thin film or layers stack near or on a feature, and wherein the phase map is generated from phase imaging data; and
correct at least one value in the height information of the 3D surface map based on a thickness and a complex refractive index of the transparent thin film or layers stack.
2 . The system of claim 1 , wherein the feature is a bump, a micro-bump, a pillar, a metal-nail, an electronic device, or a transparent feature.
3 . The system of claim 1 , wherein the workpiece is a semiconductor wafer, flat panel, printed circuit board, or glass substrate.
4 . The system of claim 1 , further including a reflectometer configured to measure the thickness and the refractive index.
5 . The system of claim 1 , wherein the correcting uses a phase shift correction.
6 . The system of claim 5 , wherein the transparent thin film or layers stack technique uses only one wavelength, dual wavelength, or multi-wavelength illumination.
7 . The system of claim 1 , wherein the interferometric quantitative phase imaging uses coherent illumination, non-coherent illumination, or partially-coherent illumination.
8 . A method comprising:
determining a 3D surface map of a workpiece using an interferometric quantitative phase imaging technique, wherein the workpiece includes a transparent thin film or layers stack near or on a feature, and wherein the 3D surface map includes height information in a 2D arrangement;
measuring a thickness and a refractive index using a reflectometer; and
correcting, using a processor, at least one value in the height information of the 3D surface map based on the thickness and the refractive index of the transparent thin film or layers stack.
9 . The method of claim 8 , wherein the feature is a bump, a micro-bump, a pillar, a metal-nail, an electronic device, or a transparent feature.
10 . The method of claim 8 , wherein the workpiece is a semiconductor wafer, flat panel, printed circuit board, or glass substrate.
11 . The method of claim 8 , wherein the correcting uses a phase shift correction.
12 . The method of claim 11 , wherein the transparent thin film or layers stack technique uses only one wavelength, dual wavelength, or multi-wavelength illumination.
13 . The method of claim 8 , wherein the interferometric quantitative phase imaging uses coherent illumination, non-coherent illumination, or partially-coherent illumination.
14 . The method of claim 8 , wherein the thickness is based on a measured phase difference between two points on the workpiece.
15 . The method of claim 8 , wherein the refractive index has a real part and an imaginary part.
16 . A non-transitory computer-readable storage medium, comprising one or more programs for executing the following steps on one or more computing devices comprising:
determining a 3D surface map of a workpiece from data generated using an interferometric quantitative phase imaging technique, wherein the workpiece includes a transparent thin film or layers stack near or on a feature, and wherein the 3D surface map includes height information in a 2D arrangement;
correcting at least one value in the height information of the 3D surface map based on a thickness and a refractive index of the transparent thin film or layers stack.
17 . The non-transitory computer-readable storage medium of claim 16 , wherein the feature is a bump, a micro-bump, a pillar, a metal-nail, an electronic device, or a transparent feature.
18 . The non-transitory computer-readable storage medium of claim 16 , wherein the workpiece is a semiconductor wafer, flat panel, printed circuit board, or glass substrate.
19 . The non-transitory computer-readable storage medium of claim 16 wherein the correcting uses a phase shift correction.