Automated Single-Wafer Lift-Off System

Karl Suss has unveiled its latest tool, the M6000L Metal Lift-Off Cluster System, a single wafer tool that enables significantly higher process control over existing batch methods. Single-wafer processing eliminates errors in device manufacture by preventing metal redeposition back onto the wafer, which can be a problem of batch processes. Furthermore, single wafer dry in/dry out processes allow improved process control and tuning to accommodate various metal and resist film stacks. This technology is especially suited to the production of high frequency devices. The M6000L Lift-Off System is available immediately for customer sample generation with volume shipments to begin early this year.

Metal lift-off is a critical process step that is required for the production of high-frequency devices and can be used to create three-dimensional metal interconnects surrounded by air, known as air bridges, which utilize the inherent low-k value of air over other dielectric materials. Metal lift-off processes also enable the deposition/patterning of materials such as Au, Ta and Ti that are not easily etched using traditional plasma or wet chemical processes and can do so without damage to the substrate.

The process takes place following a lithography step that leaves a resist profile with an overhang, contradictory to the straight sidewall normally desired. Next, a layer of metal is deposited over the resist and onto the wafer, leaving a discontinuous metal film due to the retrograde resist sidewall profile. The M6000L lift-off tool is then used to peel away the unwanted metal by attacking the resist exposed at the discontinuities leaving behind metal traces on the wafer where desired.

"This equipment was designed to open process bottlenecks in GaAs wafer fabs and allow fab output to reach new levels with confidence," explained James Hermanowski, international product manager for Suss. "The M6000L combines exceptional process capability and yield in a single wafer system that prevents waste metal redeposition that is often a problem for traditional batch processes. Its compact footprint, approximately 1200 mm by 1200 mm, low chemical consumption, and potential for high process material utilization reduces cost of ownership even further for metal lift-off processes."

The M6000L Lift-Off System specifically addresses the special needs of the gallium arsenide (GaAs), optoelectronics and telecom markets by meeting process challenges for manufacturing high frequency telecommunication chips such as laser diodes, SAW filters and other high frequency chips. Designed for removing deposited metal films, the tool utilizes single wafer process sequencing that provides greater control and reliability than existing batch or mixed batch and single wafer systems. This system complements Suss' existing exposure tools, coat/develop clusters, flip chip bonders and high frequency prober solutions to provide a more complete end to end package for its customers engaged in creating the next generation of communication chips.

Suss, Karl, Kg Gmbh & Co., Schleissheimer Str. 90, Garching Munchen, ?? 85748. Tel: 89-320-07-0; Fax: 89-320-07-162.