Semiconductor devices having reduced gate-drain capacitance
View Patent ↗Embodiments of a semiconductor device include a semiconductor substrate having a first surface and a second surface opposed to the first surface, a trench formed in the semiconductor substrate and extending from the first surface partially through the semiconductor substrate, a gate electrode material deposited in the trench, and a void cavity in the semiconductor substrate between the gate electrode material and the second surface. A portion of the semiconductor substrate is located between the void cavity and the second surface.
1. A semiconductor device comprising:
a semiconductor substrate having a source region, a drain region, and a body region intermediate the source region and the drain region;
a trench formed in the semiconductor substrate;
a gate disposed at least partially within the trench and including a gate electrode material with an elongated fissure extending entirely through the gate electrode material;
a dielectric plug material disposed within the elongated fissure; and
an enclosed void cavity formed in the semiconductor substrate between the gate and the drain region.
2. The semiconductor device of claim 1 , wherein the dielectric plug material encloses the enclosed void cavity.
3. The semiconductor device of claim 1 , wherein the enclosed void cavity contains a gas.
4. The semiconductor device of claim 3 , wherein the enclosed void cavity contains a chlorine gas.
5. The semiconductor device of claim 1 , further comprising:
an oxide layer on inner surfaces of the semiconductor substrate that define the enclosed void cavity.
6. The semiconductor device of claim 1 , further comprising:
a dielectric layer that electrically insulates the gate from the semiconductor substrate.
7. The semiconductor device of claim 1 , wherein:
the source region is located at an upper surface of the semiconductor substrate;
the trench extends into the semiconductor substrate from the upper surface; and
the drain region is located at a lower surface of the semiconductor substrate.
8. The semiconductor device of claim 7 , further comprising:
a body region of a first polarity underlying the source region; and
a drift space of a second, opposing polarity underlying the body region and overlying the drain region.
9. The semiconductor device of claim 8 , wherein the enclosed void cavity extends into the drift space.
10. A semiconductor device comprising:
a semiconductor substrate having a first surface and a second surface opposed to the first surface;
a trench formed in the semiconductor substrate and extending from the first surface partially through the semiconductor substrate;
a gate electrode material deposited in the trench, wherein the gate electrode material includes an elongated fissure that extends entirely through the gate electrode material;
a dielectric plug material disposed within the elongated fissure; and
a void cavity in the semiconductor substrate between the gate electrode material and the second surface, wherein a portion of the semiconductor substrate is located between the void cavity and the second surface.
11. The semiconductor device of claim 10 , wherein the plug material and the gate electrode material seal the void cavity.
12. The semiconductor device of claim 10 , further comprising:
a source region proximate the first surface of the semiconductor substrate; and
a drain region proximate the second surface of the semiconductor substrate.
13. The semiconductor device of claim 12 , further comprising:
a body region of the semiconductor substrate, the body region having a first polarity and positioned below the source region and adjacent the gate electrode material; and
a drift space of a second, opposing polarity positioned between the body region and the drain region, wherein the portion of the semiconductor substrate located between the void cavity and the second surface forms a portion of the drift space.
14. A semiconductor device comprising:
a semiconductor substrate;
a trench extending partially through the semiconductor substrate, the trench having sidewalls perpendicular with a first surface of the semiconductor substrate;
a gate electrode material deposited in the trench and including an elongated fissure that extends entirely through the gate electrode material;
a plug material disposed within the elongated fissure; and
a void cavity underlying the gate electrode material, wherein the plug material and the gate electrode material seal the void cavity.
15. The semiconductor device of claim 14 , wherein the semiconductor substrate comprises a source region, a drain region, a body region intermediate the source region and the drain region, and a drift space intermediate the body region and the drain region.
16. The semiconductor device of claim 15 , wherein the gate electrode material is adjacent the body region and the void cavity is adjacent the drift space.
17. The semiconductor device of claim 14 , further comprising:
a dielectric layer on the sidewalls of the trench between the gate electrode material and the semiconductor substrate.
18. The semiconductor device of claim 14 , further comprising:
an oxide layer on surfaces of the semiconductor substrate, the gate electrode material, and the plug material that define the void cavity.