| 摘要 |
PURPOSE: To obtain a nonvolatile semiconductor device which exhibits excellent transistor characteristics and can shorten its TAT, by providing a large number of MOS memory transistors in it, and by recording informations in it through varying the impurity concentrations of their gate electrodes. CONSTITUTION: In a nonvolatile semiconductor device, a large number of first conduction type MOS memory transistors each of which has a semiconductor substrate 11 whereon a source region 12 and a drain region 13 are formed and has a gate electrode 15, 16 formed on the semiconductor substrate 11 via a gate insulation film 14 are provided. By varying the impurity concentration of the gate electrode 15, a piece of information is stored in the MOS memory transistor. For example, the gate electrode is configured out of a polycide film comprising a polysilicon film 15 and a metallic silicide film 16. Further, using a mask including ON information and OFF information, boron ions are implanted only into the n<-> -doped polysilicon film 15 of an nMOS memory transistor to be brought into OFF state. |
