SOI TRANSISTOR WITH FLOATING BODY FOR INFORMATION STORAGE HAVING ASYMMETRIC DRAIN/SOURCE REGIONS
First Claim
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1. A floating body storage transistor, comprising:
- a gate electrode formed above a semiconductor region and separated therefrom by a gate insulation layer;
a drain region and a source region formed in said semiconductor region, said drain region and source region defined by a dopant species of a first conductivity type; and
a floating body region located in said semiconductor region adjacent to and in contact with said drain region and said source region so as to form a first PN junction with said drain region and a second PN junction with said source region, said floating body region being defined by a dopant species of a second conductivity type that is opposite to said first conductivity type, a concentration of said dopant species of the second conductivity type being higher at said first PN junction as compared to said second PN junction.
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Abstract
By laterally asymmetrically defining the well dopant concentration in a floating body storage transistor, an increased well dopant concentration may be provided at the drain side, while a moderately low concentration may remain in the rest of the floating body region. Consequently, compared to conventional symmetric designs, a reduction in the read/write voltages for switching on the parasitic bipolar transistor may be accomplished, while the increased punch-through immunity may allow further scaling of the gate length of the floating body storage transistor.
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Citations
24 Claims
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1. A floating body storage transistor, comprising:
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a gate electrode formed above a semiconductor region and separated therefrom by a gate insulation layer; a drain region and a source region formed in said semiconductor region, said drain region and source region defined by a dopant species of a first conductivity type; and a floating body region located in said semiconductor region adjacent to and in contact with said drain region and said source region so as to form a first PN junction with said drain region and a second PN junction with said source region, said floating body region being defined by a dopant species of a second conductivity type that is opposite to said first conductivity type, a concentration of said dopant species of the second conductivity type being higher at said first PN junction as compared to said second PN junction. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A semiconductor device, comprising:
a plurality of floating body storage transistors configured to store information on the basis of charge storage in a floating body region, each of said plurality of floating body storage transistors having a well region with an increased well dopant concentration at a PN junction at a drain side compared to a PN junction at a source side. - View Dependent Claims (10, 11, 12, 13, 14)
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15. A method of forming a storage transistor, the method comprising:
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defining a well region in a semiconductor region in a laterally asymmetric manner with respect to a drain region and a source region to be formed in said well region; and forming said drain region and said source region by introducing a dopant species of a first conductivity type to define a first PN junction connecting to said drain region and a second PN junction connecting to said source region. - View Dependent Claims (16, 17, 18, 19, 20, 21, 22, 23, 24)
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Specification