Contact Resistance Measurements for Electrodes on Silicon Prepared by Autocatalytic Electroless Metallization Using Metal Nanoparticles

Recently, we reported on autocatalytic electroless metallization of silicon using gold nanoparticles. This technology is expected to be a useful, low-cost, and reliable method to form electrodes on silicon for several devices, such as solar cells and power devices. For the fabrication of electrodes, it is important that the resistance, consisting of the sheet resistance of the metal patterns and the contact resistance between the metal and silicon, is low. In this study, we measure the contact resistance of metal electrodes on silicon prepared by autocatalytic electroless metallization using gold nanoparticles. The transfer length method is suitable to evaluate the contact resistance between electrolessly plated nickel-phosphorus alloy thin films and silicon. The values obtained for the contact resistivity decrease as the film thickness increases from 0.5 to 2.3 µm. This decrease is caused by the decrease of the sheet resistance of the metal films. Reliable values for the contact resistivity were determined to be 0.9 and 1.2 mΩ·cm2 for p+- and n+-doped wafers, respectively. The contact resistivity depends on the gold nanoparticle coverage.