Abstract: An apparatus for forming a film on a wafer in the semiconductor process is provided. The apparatus includes an inner part containing a susceptor for mounting thereon the wafer, and an outer part covering the inner part. There are an inlet and an outlet between the inner part and the outer part and gases can flow in and out through them. A special gas-feeding pipe is partially mounted inside the inlet. The gases are ejected from the gas-feeding pipe and toward the outer part instead of the inner part. Hence, the temperature difference between the gases and the inner part is diminished and the film adhered to the inner part will not peel to form particles. It reduces the contamination problem. A gas-feeding method is also provided according to the present apparatus.