Direct Wire-Bonding of Silicon Devices Without Metal Pads

We demonstrate a new method for direct wire-bonding of silicon devices, which does not require any metal bond-pads. A wire bond-ball is pressed into a hole etched in the silicon device layer, and is wedged in the hole by plastic deformation. Experimental measurements show that strength and conductivity of direct-bonds are comparable to those of standard wire-bonds on metal pads. The relevance of direct wire-bonding is that by eliminating metal bond-pads, constraints on high temperature processing steps and limitations on sacrificial release steps, are alleviated.