Wafer Flatness Characterization
Original Publication Date: 1978-Jan-01
Included in the Prior Art Database: 2005-Feb-20
The surface mapping capability of the IBM System Model 7840 is utilized to provide an output in the form of a contour map indicating hills and dales of a film-coated semiconductor wafer for determining its flatness, particularly after hot processing. For this purpose, a nonconformal transparent film of a polyimide is coated on the wafer surface so that the top boundary of the film would appear to be relatively flat (Fig. 1). A contour map of the film may then be generated by the 7840. The wafer is then subjected to hot processing and contour mapped (Fig. 2) for comparison with the previous contour map. Any change "T" in film thickness due to wafer warpage (on hot processing) can be detected in the microinch range.