Optical thickness and flatness measurement of bonded silicon wafer assemblies

Abstract—The silicon wafer manufacturing process relies heavily on precision polished wafers that have uniform thickness and, depending on the application, also control parallelism to a secondary wafer after bonding. Lumetrics’ low coherence interferometer, commercially marketed as OptiGauge II, is a device capable of measuring the simultaneous wafer thickness, adhesive thickness, and parallelism between surfaces to sub-micron precision. Combined with custom software and a precision XY raster scanner, a wafer or wafer assembly can be fully characterized with respect to layer thicknesses and surface parallelism.

Optical Thickness and Flatness Measurement App Note Download