Silicon-on-insulator transistors having improved current characteristics and reduced electrostatic discharge susceptibility
First Claim
1. A field effect transistor formed in a semiconductor material layer on an insulating layer formed in a supporting substrate comprisinga first region in said semiconductor material and having a first conductivity type, said first layer functioning as a source region,a second region in said semiconductor material layer having said first conductivity type and spaced from said first region, said second region functioning as a drain region,a third region in said semiconductor material layer underlying said first region abutting said insulating layer and separating said first region from said insulating layer, said third region having a second conductivity type and functioning as a body contact for charge carriers,a fourth region in said semiconductor material layer between said first region and said second region and functioning as a channel interconnecting said first region and said second region,a conductor overlying said fourth region and insulatively spaced therefrom and functioning as a gate contact,a source contact to said first region, and a drain contact to said second region.
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Accused Products
Abstract
An SOI MOSFET having improved electrical characteristics includes a low barrier body contact under the source region, and alternatively under the drain region, to facilitate collection and removal of current carriers generated by impact ionization. Fully-depleted and non-fully-depleted SOI MOSFETs can be integrated on the same chip by providing some transistors with thicker source and drain regions with a recessed channel therebetween and by selective channel dopant implant. Accordingly, digital circuitry and analog circuitry can be combined on one substrate. Improved electrostatic discharge protection is provided by fabricating transistors for the protection circuit directly in the supporting substrate by first removing the silicon thin film and underlying insulation barrier. Alternatively, improved transistors for electrostatic discharge protection can be formed in the silicon film by fabricating the transistor in a plurality of electrically isolated segments, each segment having source and drain regions separated by a channel region with the regions being electrically interconnected with like regions in other segments. Increased ESD current can be realized as compared to the ESD current for a wider unsegmented device.
347 Citations
13 Claims
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1. A field effect transistor formed in a semiconductor material layer on an insulating layer formed in a supporting substrate comprising
a first region in said semiconductor material and having a first conductivity type, said first layer functioning as a source region, a second region in said semiconductor material layer having said first conductivity type and spaced from said first region, said second region functioning as a drain region, a third region in said semiconductor material layer underlying said first region abutting said insulating layer and separating said first region from said insulating layer, said third region having a second conductivity type and functioning as a body contact for charge carriers, a fourth region in said semiconductor material layer between said first region and said second region and functioning as a channel interconnecting said first region and said second region, a conductor overlying said fourth region and insulatively spaced therefrom and functioning as a gate contact, a source contact to said first region, and a drain contact to said second region.
Specification