| 摘要 |
PURPOSE:To decrease well forming processes, by diffusing impurities into the surface of a semiconductor from a P-or N-type diffused layer, which is prepared as an embedded diffused layer, in a BI (¦bipolar) MOS or BICMOS, and forming the wells. CONSTITUTION:An N-type embedded diffused layer 18 is formed by implanting arsenic ions. The peak concentration immediately after the ion implantaion is about 1X10<19>cm<-3>. A P-type embedded diffused layer 19 is formed by implanting boron ions. The peak concentration immediately after the ion implantation is 5X10<17>cm<-3>N. In epitaxial layer 17, arsenic is doped to the concentration of about 5X10<15>cm<-3>, and its thickness is 1.5 mum. After the ion implantations for the P-and N-type embedded diffused layers, drive-in is performed in an 02/N2 atmosphere at 1,100 deg.C for three hours. Then the impurity concentrations shown in the Figure are obtained. As the threshold voltage for the P-and Nchannel transistors, a desired value of 0.7 V is obtained. |
