Transistor devices and methods of forming transistor devices
An LDMOS transistor device may be provided, including a substrate having a conductivity region arranged therein, a first isolation structure arranged within the substrate, a source region and a drain region arranged within the conductivity region, a second isolation (local isolation) structure arranged between the source region and the drain region, and a gate structure arranged at least partially within the second isolation structure. The first isolation structure may extend along at least a portion of a border of the conductivity region, and a depth of the second isolation structure may be less than a depth of the first isolation structure. In use, a channel for electron flow may be formed along at least a part of a side of the gate structure arranged within the second isolation (local isolation) structure.
1. A transistor device comprising:
a substrate having a conductivity region arranged therein;
a first isolation structure arranged within the substrate, wherein the first isolation structure extends along at least a portion of a border of the conductivity region;
a source region and a drain region arranged within the conductivity region;
a second isolation structure arranged between the source region and the drain region, wherein a depth of the second isolation structure is less than a depth of the first isolation structure; and
a gate structure arranged at least partially within the second isolation structure.
2. The transistor device of claim 1 , wherein each of the first isolation structure and the second isolation structure comprises a dielectric material.
3. The transistor device of claim 1 , further comprising a body region arranged between the first isolation structure and the gate structure, wherein the source region is arranged within the body region.
4. The transistor device of claim 3 , wherein the gate structure adjoins the body region along a side of the gate structure.
5. The transistor device of claim 3 , wherein a depth of the body region is between the depth of the second isolation structure and a depth of the gate structure arranged within the second isolation structure.
6. The transistor of claim 3 , further comprising a body contact arranged within the body region, wherein the body contact adjoins the source region.
7. The transistor device of claim 1 , further comprising a drift region arranged within the conductivity region, wherein the drain region and the second isolation region are arranged within the drift region.
8. The transistor device of claim 1 , wherein the first isolation structure is arranged partially within the conductivity region.
9. The transistor device of claim 1 , wherein the depth of the second isolation structure is less than or equal to 120 nm.
10. The transistor device of claim 1 , wherein the depth of the second isolation structure ranges from one-third of the depth of the first isolation structure to two-thirds of the depth of the first isolation structure.
11. The transistor device of claim 1 , wherein the second isolation structure is an ultra-shallow trench isolation structure.
12. The transistor device of claim 1 , wherein a side of the gate structure facing the source region is aligned with a side of the second isolation structure.
13. The transistor device of claim 1 , wherein a portion of the second isolation structure extends from the gate structure towards the drain region.
14. The transistor device of claim 1 , wherein a first part of the gate structure is arranged within the second isolation structure and a second part of the gate structure is arranged over the substrate.
15. The transistor device of claim 14 , further comprising a silicide block layer extending from above the second part of the gate structure to a top surface of the substrate.
16. The transistor device of claim 1 , wherein the gate structure is arranged entirely within the second isolation structure.
17. A method of forming a transistor device, the method comprising:
providing a substrate;
forming a conductivity region within the substrate;
forming a first isolation structure within the substrate, wherein the first isolation structure extends along at least a portion of a border of the conductivity region;
forming a second isolation structure within the conductivity region, wherein a depth of the second isolation structure is less than a depth of the first isolation structure;
forming a gate structure at least partially within the second isolation structure; and
forming a source region and a drain region within the conductivity region, such that the second isolation structure is arranged between the source region and the drain region.
18. The method of claim 17 , further comprising forming a body region between the first isolation structure and the gate structure.
19. The method of claim 18 , wherein the body region is formed after forming the gate structure.
20. The method of claim 18 , wherein forming the body region comprises depositing dopants into the substrate at an angle substantially perpendicular to a top surface of the substrate.