Low-temperature epitaxy of phosphorus doped Si and Si1-xGex films by RTP/VLP-CVD

In situ phosphorus doped Si and Si_1-xGe_x epitaxial layers have been grown at 600°C in a very low pressure chemical vapor deposition system using SiH₄ and 1800 ppm PH ₃ diluted in H₂. The epitaxial growth rates were found to decrease with phosphorus doping and input of the diluent H₂. The constant phosphorus concentration with depth for a steady flow of PH₃ was achieved. Dopant concentration is a function of gas phase dopant concentration. Chemical concentrations as high as 2.5×10²⁰ P/cm³ were obtained in Si epitaxial layers. The doping level can be modulated between 1.2×10 ²⁰ and 1.5×10¹⁷ P/cm³. There is no evidence of a time-dependent accumulation of phosphorus on the growth surface or the reactor wall