P‐Doped Polysilicon Film Growth Technology

Abstract

This paper deals with P‐doped polysilicon film growth in the and gas reaction by hot‐wall low pressure CVD technology. In P‐doped polysilicon film growth, between 600° and 650°C, the injection of carrier gas through an additional port at the exhaust vacuum pump side, which is opposite to the ports for and reaction gases, yielded uniform film thickness and resistivity, and a lower resistivity at a higher deposition rate. As the carrier, He gas, which has a long mean‐free path and a large diffusion constant, has proved effective for controlling the film thickness and resistivity distribution across the wafer. The P‐doped polysilicon film growth mechanism was explained by the Langmuir‐Hinshelwood's adsorption reaction model. The P‐doped polysilicon films, deposited on 4 in. wafers under the optimum growth condition in a batch of 50 wafers, were ±3% across the wafer and ±5% wafer to wafer in both film thickness and resistivity. A 70Å/min deposition rate was maintained for these films. After being subjected to a post heat‐treatment in an atmosphere at 1000°C for 30 min the wafers had a resistivity for 5000Å film thickness.