By Will Soutter
SPTS Technologies, the company that provides wafer processing solutions globally for semiconductor packaging, MEMS, power management device markets and such related markets, has introduced a low temperature plasma-enhanced chemical vapour deposition (PECVD) solution that addresses the issues in via-reveal passivation or post-through silicon via (TSV) processing in packaging of 3D integrated circuits.
SPTS PECVD solution for Low Temperature 3D-IC
Labeled the Delta fxP PECVD system, the solution has already proven its performance in volume production of 300 mm fabrication. The PECVD system demonstrates throughputs twice that of existing systems while depositing dielectric layers onto wafers bonded to carriers at temperatures less than 2000C.
Via-reveal or post TSV processing which is carried out subsequent to the formation of TSV involves the thinning of the backside of wafers bonded temporarily to a carrier in order to reveal the vias. An amalgamation of silicon nitride and oxide is employed for passivation of via tips and then subjected to redistribution metallization.
The PECVD process however faces two challenges owing to the temporary bonding between the wafer and carrier. The first one is the delivery of specified passivation characteristics at wafer temperatures below 2000C necessary to sustain the temporary bond. The second issue is the impediment to the quality of the growing PECVD film resulting from out-gassing of the bonding adhesive inside the PECVD vacuum chamber. The Delta fxP system employs the innovative process and hardware solutions developed by STPS to deposit TEOS oxides and nitrides characterized by high breakdown voltage or low leakage current under low wafer temperatures. An integrated batch Multi-Wafer Degas is used to address the out-gassing issue. Productivity is enhanced by out-gassing multiple wafers simultaneously.