Semiconductor device
An embodiment of a semiconductor device may include a transistor having a first doped region and a second doped region that extend laterally underlying the source, body, and drain of the transistor. The transistor may have an embodiment that includes an additional bias contact to apply a bias potential to the first doped region and or alternately the second doped region.
1. A semiconductor device having a transistor comprising:
a semiconductor substrate;
an insulator on the semiconductor substrate;
a source region of a first conductivity type overlying the insulator;
a drift region of the first conductivity type overlying the insulator;
drain region of the first conductivity type within the drift region and overlying the insulator, the drain region spaced apart from the source region by at least a portion of the drift region;
a first doped region of the first conductivity type on the insulator having a first doping concentration, the first doped region formed to extend continuously across the insulator underlying the source region, the drain region, and the drift region;
a restriction layer of a second conductivity type on the first doped region and having a second doping concentration that is greater than the first doping concentration, the restriction layer formed to extend continuously across the first doped region underlying the source region, the drain region, and the drift region;
an epitaxial layer of the first conductivity type on the restriction layer, the epitaxial layer having a third doping concentration that is less than the second doping concentration and greater than the first doping concentration wherein a portion of the epitaxial layer forms a P-N junction with the restriction layer;
a body region of the second conductivity type in the epitaxial layer wherein the source region is in the body region wherein the body region is electrically coupled to the restriction layer and wherein the restriction layer receives a potential applied to the body region; and
a bias contact including a second doped region of the first conductivity type formed in the epitaxial layer, the bias contact electrically coupled to the first doped region wherein a potential applied to the bias contact is applied to a portion of the P-N junction.
2. The semiconductor device of claim 1 wherein a depletion region along the restriction layer is substantially depleted for an interval that the transistor is disabled.
3. The semiconductor device of claim 1 wherein a depletion region along the restriction layer is substantially depleted for an interval that the transistor is enabled.
4. The semiconductor device of claim 1 wherein a potential on the first doped region is substantially constant for a first interval that the transistor is enabled and for a second interval that the transistor is disabled.
5. The semiconductor device of claim 1 further including a third doped region of the second conductivity type in the epitaxial layer and extending to abut both the restriction layer and the body region.
6. The semiconductor device of claim 5 wherein the third doped region underlies the body region, the source region and a portion of the drift region but does not underlie the drain region.
7. The semiconductor device of claim 1 wherein the restriction layer underlies the bias contact.
8. The semiconductor device of claim 7 wherein a portion of the epitaxial layer extends between and abuts the bias contact and the restriction layer.
9. The semiconductor device of claim 1 wherein the restriction layer does not underlie the bias contact.
10. The semiconductor device of claim 9 wherein the first doped region underlies the bias contact.
11. The semiconductor device of claim 1 wherein the restriction layer underlies the bias contact.
12. A semiconductor device having a transistor comprising:
a first doped region of a first conductivity type and a first doping concentration;
a drift region of the first conductivity type within the first doped region and having a drain region of the first conductivity type formed therein;
a body region of a second conductivity type spaced a distance from the drift region;
a source region of the first conductivity type within the body region;
a channel region positioned between the source region and the drift region;
a restrictive layer of the second conductivity type and having a second doping concentration that is greater than the first doping concentration, the restrictive layer extending continuously underlying the body region, the source region, the channel region, the drift region, and the drain region wherein the restrictive layer is electrically connected to the body region; and
a blocking layer of the first conductivity type, the blocking layer having a second doping concentration that is less than the first doping concentration, the blocking layer underlying the restrictive layer and abutting the restrictive layer wherein a potential of the blocking layer is substantially constant.
13. The semiconductor device of claim 12 further including a second doped region of the second conductivity type formed on the restrictive layer and extending to contact the body region.
14. The semiconductor device of claim 13 wherein the second doped region underlies the body region and at least a portion of the drift region but does not underlie the drain region.
15. The semiconductor device of claim 12 wherein at least a portion of the restrictive layer along a length of the restrictive layer is substantially depleted of carriers under a condition of the transistor being enabled.
16. The semiconductor device of claim 12 further including a bias contact formed as a second doped region of the first conductivity type in the first doped region.
17. The semiconductor device of claim 12 wherein a potential of the blocking layer is substantially constant under a condition of the transistor being enabled and disabled.
18. A semiconductor device comprising:
a semiconductor substrate;
a first doped region of a first conductivity type overlying the semiconductor substrate, the first doped region having a first doping concentration;
a second doped region of a second conductivity type on the first doped region, the second doped region having a second doping concentration;
a third doped region of the first conductivity type on the second doped region, the third doped region having a third doping concentration that is less than the second doping concentration; and
a body region in the third doped region;
a source region within the body region;
a drift region within the third doped region, the drift region having a fourth doping concentration that is greater than the first doping concentration;
a drain region within the drift region;
the first doped region and the second doped region extending to continuously underlie the source region, the drift region, and the drain region, and wherein the second doped region is electrically coupled to the body region.
19. The semiconductor device of claim 18 further including a bias contact formed as a fourth doped region of the first conductivity type within the third doped region wherein a potential of the first doped region is substantially constant for both an enabled and a disabled operational state of the transistor.
20. The semiconductor device of claim 19 wherein the fourth doped region is coupled to receive the potential independently of voltages applied to the source region, the body region, and the drain region.