Rabin & Champagne, P.C.
Method of making a blanket N-well structure for SRAM data stability in P-type substrates
 SRAMs conventionally formed on N-type substrates are instead formed on P-type substrates which have had the surface layer of the substrate converted to a blanket N-type well region. Preferably, the blanket N-type well region is formed by ion implantation of phosphorus ions to a dosage of between 5.times.10.sup.12 to 2.times.10.sup.13 /cm.sup.2 at an energy of 200-1000 KeV. Use of a P-type substrate having a blanket N-well region formed by ion implantation are less expensive than the N-type substrates conventionally used, and make the SRAM processing techniques compatible with the P-type substrates conventionally used in microprocessors and other logic devices. 
United Microelectronics Corporation
H
H01L
inventional
Chung-Yuan Chun-Yen Chen-Chiu Sun-Chieh
Lee Chang Hsue Chien