Growth and Characterization of Undoped Polysilicon Thick Layers: Revisiting an Old System

Abstract

Thick layer of polycrystalline silicon (poly-Si) grown by Atmospheric Pressure Chemical Vapor Deposition (APCVD) is still a reference material in a number of applications, despite the high thermal budget of this technique. This work presents a material study of undoped poly-Si layers of different thicknesses, using different characterization techniques such as secondary electron microscope in backscattered detection configuration, electron backscattering diffraction imaging, secondary ion mass spectrometry and spreading resistance profiling. The poly-Si layers, grown at 1000 °C by APCVD on thermal oxide, were found to have a columnar microstructure with [110] main orientation. By correlating layer purity, grain size and electrical resistivity, no straightforward relation between grain size and resistivity could be found. The layers resistivity is found almost independent on thickness and thus grain size. The possible reasons for such difference with previous other works are discussed taking into account the grain size determination uncertainty and the electrical characterization limitations.