Simultaneous Formation of Through Wafer Electrical Interconnects and Highly Dense & Uniform Nickel Tips for Silicon-Cantilever Probe-Cards

Presented is a novel MEMS probe-card for wafer-level IC testing. In one 4-inch wafer, a total of 17300 cantilever-tip probes are fabricated, with 90 mum pitch for adjacent probes. Combined with the silicon cantilevers formed by advanced bulk micromachining techniques, the electroplated nickel is used to simultaneously form the probing tips and the through-wafer interconnects (TWIs). The TWIs are designed to transfer the testing signals from the dies under test (DUT) at the wafer bottom side to the I/O interface at the front side. The cantilever spring-constant is measured as about 1520 N/m. The contact resistance values on Al, Cu and Au pads on DUT wafers are measured always below 1 Omega, while the current-leakage is about 90 pA under 5 V applied voltage between two adjacent tips.