US 5,144,390 A · Silicon-on insulator transistor with internal body node to source node connection

Abstract

A transistor and a method of making a transistor are disclosed, where a tunnel diode is formed to make connection between the source of the transistor and the body node underlying the gate. For the example of an n-channel transistor, a p+ region is formed by implant and diffusion under the n+ source region, the p+ region in contact on one end with the relatively lightly doped p-type body node. The relatively high dopant concentration of both the p+ region and the n+ source region creates a tunnel diode. The tunnel diode conducts with very low forward voltages, which causes the body node region to be substantially biased to the potential of the source region. Methods for forming the transistor are also disclosed, including the use of a source/drain anneal prior to p-type implant, or alternatively a second sidewall oxide filament, to preclude the boron from counterdoping the LDD extension at the source side. Both silicon-on-insulator and bulk embodiments are disclosed.

Claims13

Dependent claims

A field-effect transistor formed at a surface of a semiconductor, comprising:

a source region of a first conductivity type formed at said surface;
a drain region of said first conductivity type formed at said surface;
a gate disposed over said surface at a location between said source and drain regions;
a body node region of a second conductivity type disposed in said semiconductor underlying said gate;
a highly doped contact region of said second conductivity type disposed only under said source region and in contact with said body node region, said contact region being more highly doped than said body node region, said body node region being not externally shortened to said source region, said transistor not having a region of said second conductivity type under said drain region;
and
wherein said contact region and said source region are both sufficiently highly doped so that conduction from the contact region to the source region occurs under operating drain-to-source bias conditions, whereby the body node is biased to a potential close to that of the source region.

4 more elements

Dependencies are inferred from the claim text.

Silicon-on insulator transistor with internal body node to source node connection

Life of this patent

Silicon-on insulator transistor with internal body node to source node connection

Life of this patent

Abstract

Claims13