| 摘要 |
PURPOSE:To stabilize an E/D type MOS circuit by forming a well having high density in a low impurity density substrate and forming an E type FET in the well and a D type FET in the low density region, thereby reducing the substrate bias effect. CONSTITUTION:An inverter circuit is, for example, formed with an n-channel E/D type FET. A mask 9 is formed on a region forming a D type FET in a P<-> type substrate 7 of 10<14>-10<15>cm<-3> of impurity density, and B ions are injected in the amount of approx. 10<12>-10<13>cm<-2>. Then, it is elongated, diffused, and a P type well 6 of 10<16>cm<-3> of surface density is formed in the injected region. Then, an E type FET is formed in the well 6 and a D type FET is formed in the substrate 7 by an ordinary process to form an inverter formed of the E type driving FET and the D type loading FET. Thus, it can form a device having small back gate bias dependency, while its gain can be increased, and the characteristics can be stabilized. |
