US 5,858,826 A · Method of making a blanket N-well structure for SRAM data stability in P-type substrates

Abstract

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.

Claims11

Dependent claims

A method of making an NMOS device comprising:

providing a P-type substrate having a surface;
forming a blanket N-well region on at least a portion of the surface of the P-type substrate by implanting phosphorous ions to a dosage of between 5.times.10.sup.12 to 2.times.10.sup.13 /cm.sup.2 ;
forming a P-well isolation region within the blanket N-well region;
forming N-type source and drain regions within the P-well isolation region;
forming a gate insulator and a gate corresponding to the N-type source and drain regions;
forming a second N-well region;
forming P-type source and drain regions within the second N-well region;
and
forming a gate insulator and a gate corresponding to the P-type source and drain regions.

6 more elements

Dependencies are inferred from the claim text.

Method of making a blanket N-well structure for SRAM data stability in P-type substrates

Life of this patent

Method of making a blanket N-well structure for SRAM data stability in P-type substrates

Life of this patent

Abstract

Claims11