| 摘要 |
PURPOSE:To reduce a withstand voltage irregularity between a source and a drain by forming twice drain and source regions of a electrically rewritable semiconductor memory device when forming the drain and source regions and specifying the length of a channel region in the first formation. CONSTITUTION:A thinned gate SiO2 film 2 is coated on a tunnel region corresponding to the center of a drain region on a p-type Si substrate 1, resist masks 8 are formed at both sides with the thinned film as a mark, and a channel length L between the drain and source regions to be formed of one of them is specified. Then, As ions are implanted to the entire surface while interrupting the masks 8, the n-type first drain region 104 is formed on the thinned portion, and the first source region 105 is formed at the portion separated therefrom. Thereafter, a laminated gate electrode D is formed from the region 104 to the end of the region 105, with the electrode as a mask ions are implanted to form the deep n<+> type second drain and source regions 15, 16 while containing the regions 104, 105. |
