Room temperature desorption of Self Assembled Monolayer from Copper surface for low temperature & low pressure thermocompression bonding

In this paper the utility of Self Assembled Monolayer (SAM) of Propanethiol (C3) for Copper protection from oxidation and subsequent desorption of the Thiol layer from Copper surface by using cold Helium plasma has been investigated. The major bottleneck of achieving low temperature and low pressure bonding is the presence of contamination and oxidation on the Copper surface. Use of Thiol can protect the freshly deposited Copper surface from oxidation and other contamination. Removal of this Thiol layer by Helium plasma just prior to bonding can bring down the required temperature of bonding to 200° and pressure to 4kN. This technique can open up a whole new platform for low temperature bonding for 3D ICs.