JPS6421948A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To improve the controllability and the uniformity of resistivity in a BiCMOS and also to improve the reliability of the title semiconductor device by a method wherein a buried layer, having the same conductivity type as a semiconductor substrate, and another buried layer having the conductivity type opposite to that of said buried layer are formed on a one-conductivity type semiconductor substrate, an undoped epitaxial layer is formed thereon, and a well is formed on the buried layer by diffusing the impurities of the same conductivity type as the buried layer. CONSTITUTION:When a bipolar transistor and a complementary type MOS transistor are formed on the same semiconductor substrate, a buried layer 14 of the same conductivity type as the substrate 11 and another buried layer 13 of the conductivity type opposite to that of the layer 14 are formed on the one-conductivity type semiconductor substrate 11, and an undoped epitaxial layer 12a is grown thereon. Then, wells 15 and 16 of the same conductivity type as the substrate 11 and the conductivity type opposite to that of the substrate 11 are formed. For example, when the undoped epitaxial layer 12a is grown, the impurities of the buried layers 13 and 14 creep up as shown in the diagram. Then, phosphorus is ion- implanted into the upper part of the n<+> type buried layer 13, boron is ion-implanted into the upper part of the p<+> type buried layer 14, and when annealing is conducted subsequently, an n-well 15 and a p-well 16 are formed as shown in the diagram.