High-speed rotating-disk chemical vapor deposition process for in-situ arsenic-doped polycrystalline silicon films

We have developed high-speed rotating-disk chemical vapor deposition (CVD) equipment for polycrystalline silicon (poly-Si) films. This CVD equipment has an enhanced ability to reduce the boundary layer thickness at a given temperature above a wafer surface, and to suppress vapor-phase reactions. We investigated in-situ arsenic-doped poly-Si film deposition using silane (SiH₄), arsine (AsH₃) and nitrogen (N₂) in a high-speed rotating-disk CVD as functions of AsH₃ flow rate and deposition temperature. Both the deposition rate and resistivity decreased with increasing AsH₃ flow rate. A deposition rate of 120 nm/min, a resistivity of 16 mω.cm, a film thickness nonuniformity of ±5%, and a number of particles of less than 20 (over 200 nm in diameter) were achieved at a deposition temperature of 680°C for in-situ arsenic-doped poly-Si deposition on a 200-mm-diameter silicon (Si) wafer. Moreover, it was confirmed that the concentration of As in the poly-Si film was low at the initial stage of deposition, and that this process has a high gap filling capability in a hole of 0.18 μm width and 7 μm depth. It was also confirmed that there were conditions for a high step coverage of more than 1. These properties are inferred to be due to the adsorbed AsH₃ preventing the adsorption of SiH₄