Kaoru Ishikawa

Electroplating Ni micro-cantilevers for low contact-force IC probing ☆

We present a new MEMS probe card made of electroplated nickel micro-cantilevers, which has compliant structures, and uses a kind of electric breakdown, or fritting, to make electric contacts to electrodes on ICs. The characteristics of fritting contact between nickel probe and Al electrodes were investigated, and nickel was found to have lower contact resistance than other materials. A micro-machining process for the probe cards, including deposition of layers having different internal stress to make a protruding cantilever shape, was developed. It was found that the fritting process using the micro-cantilevers could make the low-resistance contacts with the force of less than a few micronewtons.

Low contact-force and compliant MEMS probe card utilizing fritting contact

We present a new MEMS probe card made of electroplated Ni micro-cantilevers, which has compliant structures, and uses a kind of electric breakdown, or fritting, to make electric contacts to electrodes on ICs. The characteristics of fritting contact between Ni probe and Al electrodes were investigated, and Ni was found to have lower contact resistance than other materials. A micro-machining process for the probe cards, including deposition of layers having different internal stress to make a protruding cantilever shape, was developed.

Formation of Micrometer Scale Metal Structures on Glass by Selective Electroless Plating on Photopatterned Titanium and Copper Containing Films

A procedure for formation of catalytic SiO2 substrate adhesive layer patterns and selective electrochemical metal deposition on the catalyst images was investigated. A photoreactive solution containing a diazonaphthoquinone sulfonate ester and Ti and Cu complexes was developed to deposit Cu catalyst-TiO2 adhesive layer latent images on glass. Sub-micrometer/micrometer scale positive tone photoactive TiCu complex film patterns were formed using a conventional photolithography technique. The Cu ions in 40-50 nm thick Ti and Cu oxide layers formed by pyrolysis of the TiCu complex films were reduced, residual Cu displaced with Pd then the porous Ti oxide structure filled and plated with Cu by selective electroless then electrolytic plating. Annealing the Cu plating filled TiO2 layers on glass resulted in formation of a smooth Ti3+/Cu1+ oxide interface that enabled formation of 20 μm thick Cu deposits on glass substrate with up to 1 kN/m adhesion strength. The adhesion strength was attributed to chemical bonding of Ti3+ and Cu1+ oxides to the glass and Ti4+ oxide to the Cu plating that was formed upon annealing the Cu filled TiO2 interlayer. Furthermore, a dip coating procedure was adapted that allowed copper film deposition on the entire surface of a 300 μm thick glass substrate with 50 μm in diameter holes enabling formation of electrically conductive through glass substrate interconnects.