Three-dimensional (3D) numerical equipment modeling using the simulator PHOENICS-CVD was used to investigate a low pressure chemical vapor deposition process for boron and phosphorus doped silicon glass deposition from TEOS, PH3, O-2, and TEE gas sources. The simulation allows the 3D visualization of gas flow, temperature, and chemical concentration profiles in the reactor, as well as the calculation of the deposition rate as a function of position. Mixing of gases from different inlets and deposition uniformity due to reactive gas depletion were studied as a function of pressure, gas flow velocity, and reactor geometry. Comparison with experimental deposition rate data shows that published chemical models can well describe the undoped deposition, while additional chemical reactions seem to become important when PH3 is introduced in the reactor for phosphorus doped glass deposition.