Monitoring of Semiconductor Surfaces using Photoconductance Decay (PCD) Method

Abstract

This experiment is concerned with photoconductive decay (PCD) measurements devised specifically for the purpose of characterization of the near-surface region of semiconductor substrates. The method was tested through the measurements of the germanium wafers for which the surface was roughened in a controlled fashion, and multi-crystalline silicon wafers with textured surfaces. The near-surface lifetime of minority carriers and carrier mobility were reduced as the Ge surface roughness increased, and increased for mc-Si as saw damage was removed by chemical treatment. These results demonstrate a direct correlation between condition of the semiconductor surface and the electrical parameters measured. It is postulated that the PCD method using temporary contact can be effectively used to monitor the condition of semiconductor surfaces during device processing.