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US 6,888,205 B2Granted
Metal oxide semiconductor field-effect transistor having a gate oxide layer with portions of different thicknesses and associated methods
AssigneeSTMicroelectronics S.r.l.
InventorsAlessandro Moscatelli, Giuseppe Croce
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Abstract
A metal oxide semiconductor transistor integrated in a wafer of semiconductor material includes a gate structure located on a surface of the wafer and includes a gate oxide layer. The gate oxide layer includes a first portion having a first thickness and a second portion having a second thickness differing from the first thickness.
Claims21
A metal oxide semiconductor transistor integrated in a substrate of semiconductor material and comprising:
- a gate structure located on one surface of the substrate and including an insulating gate layer, a gate electrode on the insulating gate layer, and lateral spacers extending from the surface of the substrate on lateral walls of the insulating gate layer and the gate electrode;
- the insulating gate layer comprising a first portion having a first thickness and a second portion having a second thickness that is less than the first thickness;
- a first active region including a drain region;
- and
- a second active region spaced apart from the first active region and including a source region;
- the first and second active regions being integrated in the substrate, the first portion of the insulating gate layer being adjacent to the first active region, and the second portion being adjacent to the second active region;
- the first thickness provides a predetermined value of the breakdown voltage of the transistor, and the second thickness provides a predetermined value of the transconductance of the transistor.
4 more elements
A method for manufacturing a metal oxide semiconductor field-effect transistor the method comprising:
- providing a semiconductor substrate;
- forming, in the substrate, a first active region, including a drain region;
- forming, in the substrate, a second active region spaced apart from the first region and including a source region;
- forming a layer of gate oxide on a surface of the substrate, the layer of gate oxide including a first portion having a first thickness and a second portion having a second thickness less than the first thickness, forming the gate oxide comprising selecting the first thickness to obtain a specified breakdown voltage of the transistor, and selecting the second thickness to obtain a specified value of transconductance of the transistor;
- forming a gate electrode on the gate oxide layer;
- and
- forming lateral spacers extending from the surface of the substrate on lateral walls of the insulating gate layer and the gate electrode;
- the first portion and the second portion of the gate oxide being adjacent, respectively, to the first active region and to the second active region.
5 more elements
Dependencies are inferred from the claim text.