A study of moderately in situ doped polycrystalline silicon deposition from SiH4, PH3, and H2 by single-wafer reduced pressure chemical vapor deposition has been carried out. The process window which yielded P concentrations on the order of 1019 cm-3 was a pressure of 80 Torr in a hydrogen carrier with a PH3/SiH4 mole fraction range of 0.1×10-4–1×10-4, and temperatures of 600–700 °C. It was found that the PH3/SiH4 mole fraction in this process window has little effect on the deposition rate unlike the rate reduction caused by PH3 in a saturation-doped polysilicon process with doping levels in excess of 1020 cm-3. The activation energy of the process, 48 kCal mol-1, over this temperature range approaches one of a hydrogen desorption limited process, 49 kCal mol-1, suggesting that the deposition rate is dominated by the high H2 pressure. The transition of the as-deposited film structure from predominately amorphous to completely polycrystalline occurs at about 675 °C, about 100 °C higher than in typical low-pressure chemical vapor deposition and is likely due to a combination of high H2 pressure and high deposition rates. To a first order, the post-anneal film resistivity appears to be dominated by the grain structure and not by the P incorporation rate in the moderately doped concentration regime. © 1998 American Vacuum Society.