Patent ID: 8569899
Filing Date: 2013-10-29
Classification: H01L

Abstract:
1. A wafer stack, comprising: a first wafer having a first surface and a second surface; a plurality of first alignment structures formed through the first wafer having a plurality of first transmission columns arranged in a pattern, a first end and a second end of each of the first transmission columns extending from the first surface by a first distance and the second surface by a second distance, respectively, and the first ends and second ends of the first transmission columns being non-overlaying of any portion of the first and second surface of the first wafer, respectively; a second wafer having a first surface and a second surface, the second surface of the second wafer positioned facing the first surface of the first wafer; and a plurality of second alignment structures formed through the second wafer having a plurality of second transmission columns arranged in the same pattern as the first transmission columns, a first end and a second end of each of the second transmission columns extending from the first surface by a third distance and the second surface of the second wafer by a fourth distance, respectively, and the first end and second end of the second transmission columns being non-overlaying of any portion of the first and second surface of the second wafer, respectively.