| 摘要 |
PURPOSE:To stabilize the threshold voltage of an MOS semiconductor device by covering the surface of a channel region with an oxide film and a nitride film when diffusing an n<+>-type source and drain to eliminate external diffusion of phosphorus impurity at the time of oxidizing gate. CONSTITUTION:A surface oxide film 2 is formed on a p<->-type Si substrate 1, and with a nitride film 13 formed thereon as a mask an n<->-type well 3 is formed in the drain region. Then, n<+>-type layers 14, 15 becoming source and drain are formed to form n<+>-type source 8 and n<+>-type drain 9 by thermal diffusion, and oxide films 16, 17 are formed. Then, the film 13 is removed, thin portion 2 of the oxide film is once removed, and a gate oxide film 18 is newly formed thereafter. Subsequently, a polysilicon gate 19 is formed, and with the gate 19 as a mask an n<+>-type layer 20 is formed. Then, a PSG film 21 is formed on the entire surface, contact photoetching is executed in the source and the drain regions, and aluminum wires 22 are then formed. |
