Shallow PtSi-Si Schottky barrier contacts formed by a multilayer metallization technique

Abstract

Shallow PtSi-Si Schottky barrier contacts have been formed by heat treatment at 400–500 °C of structures prepared by vacuum deposition of thin alternating Pt and Si layers on n-type (100) Si substrates. This multilayer technique permits the formation of very shallow contacts without placing any limitation on the thickness of the PtSi layer. For a layer of given thickness the contact (PtSi-Si) interface is more uniform than the interface for a PtSi layer of the same thickness formed by annealing a single layer of Pt on Si. The interfacial uniformity is independent of PtSi thickness for shallow PtSi-Si contacts produced from multilayer samples, while that for conventional PtSi-Si contacts produced from single-layer samples degrades as the thickness of PtSi increases. Large-area (9.4×10−3 cm2) diodes utilizing shallow PtSi-Si contacts about 200 Å deep have been fabricated without guard rings. These diodes exhibit near-ideal forward I-V characteristics, low reverse-leakage currents (less than 10 nA at −10 V) and high breakdown voltages (over −70 V). These characteristics are superior to those of conventional diodes formed by heat treatment of structures prepared by depositing a single Pt layer on Si.