Method of manufacturing a semiconductor device
View Patent ↗There is provided a method of manufacturing a high quality P-channel trench MOSFET which stably operates. In the method of manufacturing a P-channel trench MOSFET having a P-type gate electrode, the process in which BF 2 ions are implanted into a polycrystalline silicon film and thereafter the heat treatment is carried out is performed plural times to thereby form the gate electrode, and it is possible to provide the P-channel trench MOSFET of high quality which stably operates.
1. A method of manufacturing a P-channel MOSFET, comprising:
forming a trench within an N-type semiconductor substrate;
forming a gate oxide film on an inner surface of the trench;
depositing a first polycrystalline silicon film on the semiconductor substrate;
implanting BF 2 ions into the first polycrystalline silicon film by utilizing an ion implantation method and carrying out a first heat treatment;
depositing a second polycrystalline silicon film on the heated first polycrystalline silicon film;
implanting BF 2 ions into the second polycrystalline silicon film by utilizing the ion implantation method and carrying out a second heat treatment;
depositing a third polycrystalline silicon on the second polycrystalline silicon film; and
implanting BF 2 ions into the third polycrystalline silicon film by utilizing the ion implantation method and carrying out a third heat treatment.
2. A method of manufacturing a P-channel MOSFET according to claim 1 , wherein a thickness of each of the first, second, and third polycrystalline silicon films is in a range of 300 to 400 nm.
3. A method of manufacturing a P-channel MOSFET according to claim 1 , wherein a dose of the BF 2 ions implanted into each of the first, second, and third polycrystalline silicon films is in a range of 1×10 15 to 7×10 15 cm −2 .
4. A method of manufacturing a P-channel MOSFET according to claim 1 , wherein each of the first, second, and third heat treatments is carried out at a temperature of 800 to 900 C.