Multilayer Cleavage Technique
Original Publication Date: 1985-Apr-01
Included in the Prior Art Database: 2005-Feb-18
Physical cleavage of semiconductor wafers having a polyimide layer, to expose an etched profile or step coverage over topography, is very difficult, and yields typically poor results. The polyimide does not break cleanly, but normally pulls and curls away from the cleaved edge, preventing inspection of the desired features. The following cleavage technique eliminates these problems since it does not require breaking of the wafers. The procedure is performed as follows: 1. The wafers which have the desired features to be inspected, e.g., coverage of polyimide over topography or an etched via hole profile, are coated with a photoresist layer whose thickness is about the same as the polyimide thickness. This step fills in all etched via holes and planarizes the wafer surface. The photoresist is baked at about 130ŒC. 2.