| 摘要 |
PURPOSE:To make a chip size small by raising the impurity concentration of a guard ring under a wiring layer, and increasing the thickness of an insulating film between the wiring layer and the guard ring. CONSTITUTION:The impurity concentration of a guard ring 2 is made thicker at a part 21 through which a polysilicon wiring layer 1 passes than other parts 22, and the thickness of an insulating film above a guard ring 2 is made thicker at a part 81 through which a polysilicon wiring layer 1 passes than a gate insulating film 8. To raise the concentration of a guard ring 21 part below the wiring layer 1, it is enough to implant much impurity, but to make chip size small, the concentration at the guard ring 21 part is raised with BF2 in case of P-type, and with As, etc., in case of N-type. Also, to increase the thickness of the film under the wiring layer 1, an exclusive photo-etching process is added so as to increase the thickness of a film between the wiring layer 1 and the guard ring 2 by additional stacking, whereby without changing the characteristics of a high breakdown strength transistor, the inversion threshold voltage of the guard ring under the polysilicon wiring layer is increased. |
