Patent Document ID: 9734568
Application ID: 14630252
Patent Status: 1

Claim One:
1. A system comprising: a light source configured to tangentially direct collimated light at a circumferential edge of a stacked wafer, wherein the stacked wafer includes a first layer and a second layer disposed on top of the first layer; a detector disposed on an opposite side of the stacked wafer from the light source to receive at least some of the collimated light from the light source, wherein the detector is configured to acquire a shadow-gram image of the circumferential edge of the stacked wafer, wherein the shadow-gram image is configured to image a shadow of an edge profile of the first layer and the second layer of the stacked wafer by applying a shadowgraph technique; and a controller operatively connected to the detector, wherein the controller is configured to: receive the shadow-gram image; and compare characteristics of the shadow-gram image with predetermined measurements to inspect an edge profile of the stacked wafer.