Next-Generation System for Power Devices Transitioning to Large Wafer Formats

September 03, 2013 by Jeff Shepard

SPTS Technologies announced the launch of its Sigma fxP physical vapor deposition (PVD) system for 300mm power device manufacturing. Available system options include modules for frontside thick aluminum processing and backside metal deposition on ultra-thin wafers. The new system is designed to address the technical challenges customers face as they scale power PVD processes up to 300 mm wafer size.

In a discrete MOSFET power device, current passes through the silicon substrate so electrical contacts are required on both sides of the wafer. Due to the high currents involved, thick aluminum alloy layers are deposited on the frontside of the wafer (typically > 4 microm rather than 1.4 microm/min without any yield destroying whiskers or extrusions.

With frontside processing complete, wafers are thinned down to 50 microm or less to reduce 'on-state' resistance and solder metal layers are deposited on the backside. No supporting carrier substrates are used and the ultra-thin, large area wafer will deform under the influence of uncontrolled film stresses, with miss-handling a potential consequence. The Sigma fxP carries thin wafer handling hardware and uses film deposition stress control techniques to deliver high throughput processes with low wafer bow.

Currently, seven out of the top ten power device manufacturers, and all major foundries use the Sigma fxP as the process tool of record for power PVD processing. With power device manufacturing moving to 300mm format wafers, SPTS has successfully transferred its market leading process knowledge and capability to the new platform.

"We are pleased to offer customers a complete solution for 300 mm Power PVD processing," said Chris Jones, product marketing manager at SPTS. "Sigma fxP systems are in full production for frontside thick Al and thin wafer backside processing. We are prepared to support the IDMs and foundries as they make the transition from 150 and 200mm wafer formats to 300mm."