Ramp Baking of Polyimides to Enhance Gap Filling
Original Publication Date: 1985-Jan-01
Included in the Prior Art Database: 2005-Feb-18
Scanning electron microscope (SEM) pictures and thermo-gravitational analysis (TGA) data on various polyimides and their studies have shown that before the curing of polyimides begins in the oven, most of the solvent should be driven off as far as possible. (It is observed that curing is done between 100ŒC and 130ŒC for most of the polyimides.) In addition, most of the solvents should be driven off from the polyimide as slowly as possible due to its diffusion process with a moving boundary layer. Polyimides have traditionally been baked in a stepwise sequence, such as 10 min. at 100ŒC on a hot plate followed by 20 min. at 200ŒC in an oven, resulting in voids in the 2.5 mm wide and 5.0 mm deep isolation regions currently designed (Fig. 1).