| 摘要 |
PURPOSE:To enable the maintenance of CMOS circuit characteristics regardless of conductivity of the conductor substrate and the well layer by a method wherein the impurity concentration of the channel region of a MOS transistor of the second conductivity type is made almost equal to that of the channel region of a MOS transistor of the first conductivity type. CONSTITUTION:A p-well layer 20 is formed in the n-type semiconductor sub strate 10, and a p-channel MOS transistor is formed on the surface of the sub strate 10. The impurity concentration of the p-well layer 20 is higher than that of the n-type semiconductor substrate 10, but the impurity concentration of a p-channel region 13 under a gate oxide film 14 in the Y'-Y' cross section is almost equal to that of an n-channel region 27 under a gate oxide film 24 in the Y-Y cross section. Since the impurity concentrations of the channel regions are almost equal, even if the semiconductor substrate is p-type and the well layer n-type, the mobilities of the channel transistors are almost equal, and so circuit characteristics are. Therefore, the titled device of the same characteristics can be obtained even if well patterns are changed with the same circuit patterns. |
