MORPHOLOGICAL AND ELECTRICAL STUDY OF POLY-SiGe ALLOY DEPOSITED BY VERTICAL LPCVD

摘要

In this paper authors report morphological and deposition analysis of poly-SiGe thin films by means of AFM, SEM and Raman measurements and electrical characteristics of MOS capacitors using poly-SiGe electrodes. The samples were deposited in a pancake vertical LPCVD system using Silane and Germane as precursor gases in a Hydrogen carrier flow. The process pressure was 5 or 10 Torr, in a temperature range from 500 °C to 750 °C. Surface RMS roughness, grain size and deposition rate are evaluated. We found that very uniform films can be obtained, with rms roughness below 4 nm and grain size below 50 nm. Deposition rates as high as 1500 A/min are achieved. The deposited samples presented Rs values well bellow similar poly-Si films and electrical characterization shows poly-SiGe as a suitable material for MOS devices.