| 摘要 |
PURPOSE:To prevent the fluctuation of gate threshold voltage even when an N layer as a punch-through top is formed at a shallow position in high concen tration by shaping the N guard layer, using a gate electrode as a mask and forming source-drain layers, employing the gate electrode and an oxide film in the periphery of the gate electrode as masks. CONSTITUTION:When a buried channel type PMOS type semiconductor device having a channel in a section inner than the surface of an N-type region 2 in a semiconductor substrate 1 is manufactured, a gate electrode 10 is formed onto the surface of the N-type region 2 through a gate oxide film 5, an N type impurity is implanted onto the N-type region 2, using the gate electrode 10 as a mask, and an N guard layer 14 is shaped near the surface of the N-type region 2. An oxide film 15 is formed around the gate electrode 10, and a P-type impurity is implanted into the N-type region 2, employing the gate electrode 10 and the oxide film 15 as masks, thus forming source-drain layers 16 in the external sections of a section under the oxide film 15 in the N guard layer 14 as the section under the oxide film 15 in the N guard layer 14 is left as it is. The source-drain layers 16 are diffused to the inside through heat treat ment, and the N guard layers 14 are changed into P-type layers 21. |
