LPCVD in-situ doped silicon for thermoelectric applications

Abstract

In semiconductor industry doping of polysilicon materials is often achieved with ion-implantation, provoking a relatively high thermal budget. In this study we have analyzed an alternative approach via low pressure chemical vapor deposition (LPCVD) in-situ phosphorus doping with subsequent rapid thermal anneal (RTA) on 150mm/300mm wafers in order to obtain Si-based materials for thermoelectric applications. With this process integration a lower thermal budget, a release of film stress and an enhancement of throughput are reached. Additionally, the dopants are distributed uniformly and there are more process tuning possibilities. The investigation includes time-of-flight secondary ion mass spectrometry (ToF-SIMS) for depth profiling of the dopant and X-Ray diffraction (XRD) and scanning electron microscopy (SEM) analysis for microstructure analysis. Film stress was also calculated from wafer bow measurement. The LPCVD amorphous silicon in-situ P-doped (a-Si:P) with RTA and LPCVD polycrystalline silicon in-situ P-doped (poly-Si:P) with RTA thin films were patterned in order to investigate the thermoelectric properties. The results suggest these LPCVD in-situ P-doped Si-based materials as suitable candidates for practical applications in the semiconductor industry.