The Fabrication of Self-Aligned Ohmic Cobalt Contacts to Relaxed, N-Type Si0.7Ge0.3

Abstract

ABSTRACTCo(SiGe)x contacts have been formed on low defect density, relaxed Si0.7Ge0.3 layers by conventional self-aligned contact processing techniques. Test structures measuring the contact metal sheet resistance indicate that the resistivity is high for anneal temperatures from 450°C to 750°C. The lowest sheet resistivity was 100 Ω/□, about 10 times the resistivity of a comparable amount of CoSi2. Contact resistivities, measured by the transmission line method, were as low as 2 × 10−5 Ω cm2. There is a large discrepancy between contact resistivities measured by transmission line and 4 point Kelvin test structures that may be due to the fabricated contact sizes.