| 摘要 |
PROBLEM TO BE SOLVED: To provide a method for manufacturing a punched through type IGBT (conductivity modulated MOSFET) having a buffer layer which enables cost reduction and high performance simultaneously. SOLUTION: This method uses a low-cost FZ wafer (for forming an n- drift layer), and has a process of forming active element regions (a p+ base region 4, an n+ emitter region 5, a gate oxide film 6, a gate electrode 7, etc.), on the surface side of the wafer, grinding off the backside of the water up to specified thickness, performing proton irradiation from the backside after that, performing low-temperature annealing processing and forming an n+ buffer layer 2b, and a process of performing corpuscular irradiation of boron ions from the backside, performing annealing processing to be done by irradiating the backside of the wafer with light or a laser beam cooling the surface of the wafer and forming a p+ collector layer 1b. An n-type defect layer being a lattice defect is formed by the proton irradiation and the low-temperature annealing processing. The n-type defect layer practically functions as an n-type high n+ buffer layer 2b.
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