Optics: measuring and testing – Dimension – Thickness
Reexamination Certificate
2005-08-30
2005-08-30
Pham, Hoa Q. (Department: 2877)
Optics: measuring and testing
Dimension
Thickness
C356S614000
Reexamination Certificate
active
06937351
ABSTRACT:
The thickness of a semiconductor wafer is non-destructively measured using infrared (IR) microscopy. The wafer is placed on a stage. A distance between the stage and a detector is then varied so that a first image of the wafer is focused on the detector. When focused, a first separation distance is measured. The distance between the stage and the detector is again varied so that a second image is focused on the detector. When again focused, a second separation distance is measured. The difference between the first and second separation distances is then determined and multiplied by the refractive index of light in silicon.
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Gemmill Zachary Joshua
Jacobson Steven
Weaver Kevin
National Semiconductor Corporation
Pham Hoa Q.
Pickering Mark C.
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