Bonded wafer metrology
AssigneeKLA-Tencor Corporation
InventorsKaushik Sah, Thomas Krah, Shifang Li, Heiko Eisenbach, Moritz Stoerring
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Abstract
Wafer edge profile images are analyzed at locations around a bonded wafer, which may have a top wafer and a carrier wafer. An offset curve is generated based on the wafer edge profile images. Displacement of the top wafer to the carrier wafer is determined based on the offset curve. The wafer edge profile images may be generated at multiple locations around the wafer. The wafer edge profile images may be shadowgram images. A system to determine displacement of the top wafer to the carrier wafer can include an imaging system connected with a controller.
Claims17
A metrology system comprising:
- a stage configured support a bonded wafer, wherein the bonded wafer has a top wafer disposed on a carrier wafer;
- an imaging system configured to generate wafer edge profile images of a circumferential edge of the bonded wafer, wherein the imaging system includes a light source configured to generate collimated light and a detector configured to generate the wafer edge profile images;
- and
- a controller in electronic communication with the imaging system, wherein the controller is programmed to:
- analyze the wafer edge profile images at a plurality of locations around the bonded wafer;
- generate an offset curve based on the wafer edge profile images;
- and
- determine a displacement of the top wafer to the carrier wafer based on the offset curve;
- wherein during the analyzing, the controller is further configured to:
- extract edge coordinates from each of the wafer edge profile images;
- determine coordinates of points at a bevel and an apex in each of the wafer edge profile images;
- fit the bevel coordinates and the apex coordinates to an elliptical model;
- and
- calculate a center position of the top wafer and the carrier wafer.
A method comprising:
- analyzing, with a controller, wafer edge profile images at a plurality of locations around a bonded wafer, wherein the bonded wafer has a top wafer disposed on a carrier wafer, and wherein the analyzing includes:
- extracting edge coordinates from each of the wafer edge profile images;
- determining coordinates of points at a bevel and an apex in each of the wafer edge profile images;
- fitting the bevel coordinates and the apex coordinates to an elliptical model;
- and
- calculating a center position of the top wafer and the carrier wafer;
- generating, with the controller, an offset curve based on the wafer edge profile images;
- and
- determining, with the controller, a displacement of the top wafer to the carrier wafer based on the offset curve.
A non-transitory computer readable medium storing a program configured to instruct a processor to:
- analyze wafer edge profile images at a plurality of locations around a bonded wafer, wherein the bonded wafer has a top wafer disposed on a carrier wafer, and wherein the analyzing includes:
- extracting edge coordinates from each of the wafer edge profile images;
- determining coordinates of points at a bevel and an apex in each of the wafer edge profile images;
- fitting the bevel coordinates and the apex coordinates to an elliptical model;
- and
- calculating a center position of the top wafer and the carrier wafer;
- generate an offset curve based on the wafer edge profile images;
- and
- determine a displacement of the top wafer to the carrier wafer based on the offset curve.
Dependencies are inferred from the claim text.