Investigation of strain induced effects in silicon wafers due to proximity rapid thermal processing using micro-Raman spectroscopy and synchrotron x-ray topography

Abstract

Thermal stress induced by rapid thermal oxidation (RTO) and rapid thermal doping (RTD) of ⟨001⟩ silicon wafers was analysed using micro-Raman spectroscopy and synchrotron x-ray topography. The RTO wafers exhibited elevated stress levels as the process time was increased. The maximum magnitude and topographical distribution of the strain was found to agree with theoretical predictions. A maximum compressive strain of 320 MPa was observed after 166 s of RTO. The introduction of boron into the silicon lattice via the RTD process enhanced the rate at which the stress in the wafer exceeded the yield stress. Stress relief was subsequently accomplished through the formation of slip and misfit dislocations. The thermally induced stress and dislocation density increased with the time spent at the process peak temperature.