Semiconductor memory and manufacture thereof

Abstract

Abstract PURPOSE:To make it possible to form easily various kinds of well regions, and improve their performance and characteristics remarkably, by providing a semiconductor substrate with a plurality of identical conductivity type wells whose surface concentrations are different, and arranging a memory cell in a well whose surface concentration is highest. CONSTITUTION:Boron is ion-implanted in a part 102 turning to a first P-well region in the cell region A of a dynamic RAM on a P-type semiconductor substrate 101, and at the same time, and at the same time, ion is implanted also in a part 102' turning to a second P-well region in the peripheral part B. Next, phosphorus 104 is ion-implanted in the part turning to a first P-well region and the part turning to the second P-well region, by using a resist 103. In a cell region, is formed a first P-well region 107 whose surface concentration is 5X10<17>cm<-3>. In an N-channel region of peripheral circuits, is formed a second P-well region 105 whose surface concentration is 2X10<17>cm<-3>. On the second P-well and the first N-well for peripheral circuits, the following are formed to constitute a DRAM; a gate electrode 113, a gate electrode 114, diffusion layer regions 115, 116, a wiring layer 117 to lead out each electrode, and so on.

Inventors

• 👤 Shizuo Sawada

Bibliographic Details