| 摘要 |
PURPOSE:To obtain a vertical FET having fast switching velocity by superposing a polysilicon and a resist mask on an oxide film of an N-type Si layer, etching to form overhangs, reactively ion-etched to form a groove, forming a shallow P-type layer and mainly an N<+> type source around the wall of the groove by utilizing a deep P<+> type layer and a polysilicon gate in the groove. CONSTITUTION:A non-doped polysilicon 6a is superposed on a gate oxide film 5a on an N-type layer 2 on an N<+> type Si substrate 1, a resist mask 7 is applied, etched to form overhangs, reactively ion-etched to form a vertical groove 3b. Ions 3a are implanted, heat treated to form a P<+> type layer 3, then with a layer 6a as a mask a shallow P-type layer 4 partly superposed under the end of the film 6a by ion implanting and heat treating, Vth is decided by the ion implanting amount, and a channel width is decided in the diffusing length of the P-type layer. Then, ions 8a are implanted, an SiO2 5b, a PSG 5c are superposed and heat-treated to diffuse an N<+> type layer 9, and an electrode 11 is attached. According to this configuration, since a P-channel region 4 is narrow, a large power vertical FET having large gm, a fast switching velocity and low ON resistance is obtained. |
