Downstream Microwave Plasma BCB-Descum Process Using Oxygen-Free Chemistry for Wafer-Level Chip Packaging Applications

摘要

1. The etch rate of BCB tends to linearly increase with increasing temperature under forming gas plasma with or without a small amount of CF_4. 2. The addition of a small amount of CF_4 (< 0.5%) into the forming gas significantly increases the etch rate of BCB. 3. Under oxygen-free, low fluorine plasma, both nitride and oxide film loss is negligible, therefore the etch selectivity of BCB against nitride and oxide is virtually infinite. 4. The oxygen-free plasma process does not have any impact to copper while O_2/CF_4 plasma interacts with Cu to result in corrosion. 5. This oxygen-free plasma process can be extended to BCB rework, particularly for fully cured BCB since no wet chemicals can effectively remove fully cured BCB without inducing damage to metals and other dielectric materials. 6. Adhesion test is under way with BCB, Al, Cu, Si_3N_4, and SiO_2 films.