Wisconsin Alumni Research Foundation

Semiconductors & Integrated Circuits
Semiconductors Integrated Circuits
Method for Bonding Stacks of Silicon Layers by Electromagnetic Induction Heating
WARF: P01426US

Inventors: John Booske, Keith Thompson, Yogesh Gianchandani, Reid Cooper

The Wisconsin Alumni Research Foundation (WARF) is seeking commercial partners interested in developing a method of using electromagnetic induction heating to bond silicon layers without intermediate metal layers.
Silicon-silicon (Si-Si) bonding is used in a wide array of technologies, including micromechanical structures and power electronics, and is a candidate for manufacturing silicon-on-insulator (SOI) wafers. Si-Si bonding processes require high temperatures (approximately 1000 °C) to ensure thorough bond formation.

Currently, bonding is conducted inside large furnaces that entail long ramp times, slow throughput rates, large power consumption and a significant manufacturing footprint. Until recently, it was assumed that because silicon is transparent to electromagnetic radiation, a technique called electromagnetic induction heating (EMIH) could only be used to bond silicon layers by adding intermediate metal layers.
The Invention
UW-Madison researchers have now found that EMIH can in fact be used to generate an ohmic silicon response, which directly heats the silicon. After stacking silicon wafers on top of each other, an EM field is generated that intersects the stack of wafers and heats them to a predetermined temperature.
  • Si-Si bonding for micromechanical structures and power electronics
Key Benefits
  • Increases throughput
  • Significantly reduces manufacturing footprint, maintenance, thermal budget and capital expenditure costs
  • Provides rapid heating of silicon wafers to temperatures in excess of 1000 degrees Celsius
  • Creates uniform, strong Si-Si bonds in under five minutes
  • Increases the flexibility of the bonding process, allowing simultaneous bonding of stacks of wafers and construction of unique structures on wafer surfaces
Additional Information
For More Information About the Inventors
For current licensing status, please contact Emily Bauer at [javascript protected email address] or 608-960-9842