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US 6,211,555 B1Granted
Semiconductor device with a pair of transistors having dual work function gate electrodes
AssigneeLSI Logic Corporation
InventorsTodd A. Randazzo, Jan Kolnik
Life of this patent
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Abstract
Techniques are described for fabricating a pair of β-identical transistors, in other words, a pair of transistors whose dimensions and electrical characteristics, other than their respective gate electrode work functions, are substantially similar. In particular, the lengths of respective channel regions for the transistors are substantially the same, and portions of each gate electrode extending above a channel region include only dopants of a single conductivity type. The techniques can be incorporated into a standard CMOS process.
Claims24
A semiconductor device comprising:
- a substrate of a first conductivity type;
- a pair of field effect transistors formed in the substrate, wherein each transistor includes:
- (a) source and drain regions of a second conductivity type opposite the first conductivity type, wherein the source and drain regions include well-extension regions;
- (b) a channel region, wherein an area extending from the source region to the drain region defines a length of the channel;
- and
- (c) a gate electrode disposed above the channel region;
- wherein the gate electrode of a first one of the transistors is of the second conductivity type, wherein a portion of the gate electrode of the second one of the transistors is of the first conductivity type and extends above the entire length of the channel of the second transistor, and wherein the lengths of the channels of the first and second transistors are substantially the same.
4 more elements
A semiconductor device comprising:
- a substrate of a first conductivity type;
- a pair of field effect transistors formed in the substrate, wherein each transistor includes:
- (a) source and drain regions of a second conductivity type opposite the first conductivity type;
- (b) a channel region, wherein an area extending from the source region to the drain region defines a length of the channel;
- and
- (c) a gate electrode disposed above the channel region;
- wherein the gate electrode of a first one of the transistors is of the second conductivity type, wherein a portion of the gate electrode of the second one of the transistors is of the first conductivity type and extends above the entire length of the channel of the second transistor, wherein the lengths of the channels of the first and second transistors are substantially the same,
- wherein the gate electrode of the second transistor includes a central portion and edges adjacent the central portion, wherein the central portion is of the first conductivity type, extends above the entire length of the channel of the second transistor and extends partially above the source and drain regions of the second transistor, and wherein the edges are of the second conductivity type and are disposed above the source and drain regions of the second transistor.
5 more elements
A reference voltage source comprising:
- a pair of field effect transistors formed in a substrate of a first conductivity type and electrically coupled to one another, wherein each transistor includes:
- (a) source and drain regions of a second conductivity type opposite the first conductivity type, wherein the source and drain regions include well-extension regions;
- (b) a channel region, wherein an area extending from the source region to the drain region defines a length of the channel;
- and
- (c) a gate electrode disposed above the channel region;
- wherein the gate electrode of a first one of the transistors is of the second conductivity type, wherein a portion of the gate electrode of the second one of the transistors is of the first conductivity type and extends above the entire length of the channel of the second transistor, and wherein the lengths of the channels of the first and second transistors are substantially the same.
3 more elements
A semiconductor device comprising:
- a substrate of a first conductivity type;
- a pair of field effect transistors formed in the substrate, wherein each transistor includes:
- (a) source and drain regions of a second conductivity type opposite the first conductivity type;
- (b) a channel region, wherein an area extending from the source region to the drain region defines a length of the channel;
- (c) a gate electrode disposed above the channel region;
- and
- (d) a field oxide region disposed between the gate electrode and the channel region;
- wherein the gate electrode of a first one of the transistors has a first work function and includes dopants only of the first type of conductivity, wherein the gate electrode of the second one of the transistors has a second work function and includes dopants only of the second type of conductivity, and wherein the lengths of the channels of the first and second transistors are substantially the same.
5 more elements
A reference voltage source comprising:
- a pair of field effect transistors formed in a substrate of a first conductivity type and electrically coupled to one another, wherein each transistor includes:
- (a) source and drain regions of a second conductivity type opposite the first conductivity type;
- (b) a channel region, wherein an area extending from the source region to the drain region defines a length of the channel;
- (c) a gate electrode disposed above the channel region;
- and
- (d) a field oxide region disposed between the gate electrode and the channel region;
- wherein the gate electrode of a first one of the transistors has a first work function and includes dopants only of the first type of conductivity, wherein the gate electrode of the second one of the transistors has a second work function and includes dopants only of the second type of conductivity, and wherein the lengths of the channels of the first and second transistors are substantially the same.
4 more elements
Dependencies are inferred from the claim text.