Granted Patent B2

US 11,658,233 · App. 16/688,344 · Granted May 23, 2023

Inventor: Kyoung-Keun Lee (Cary, NC)

Assignee: WOLFSPEED, INC.

H01L29/7786H01L21/0217H01L21/28581H01L21/28587H01L21/31111H01L21/765H01L29/2003H01L29/205H01L29/402H01L29/408H01L29/42316H01L29/475H01L29/66462H03F3/21H03F2200/451

Abstract

Claims (105)

1. A device comprising:

a substrate;

a buffer layer on the substrate;

a barrier layer on the buffer layer;

a passivation layer on the barrier layer and the passivation layer comprising a recess;

a source electrically coupled to the barrier layer;

a gate on the barrier layer and the gate is structured and arranged to further extend across the passivation layer;

a drain electrically coupled to the barrier layer; and

the gate comprising at least one first surface connected to at least one second surface through at least one inflection point on either side of the recess,

wherein the at least one inflection point, the at least one first surface, and the at least one second surface are arranged within the passivation layer;

wherein the gate fills the recess of the passivation layer;

wherein the at least one first surface comprises at least four of the at least one first surface; and

wherein the at least one second surface comprises at least four of the at least one second surface.

2. The device according to claim 1 further comprising at least one step portion that includes the at least one inflection point,

wherein the gate further comprises a portion arranged vertically above the at least one step portion and vertically above the passivation layer;

wherein the at least one step portion includes the at least one first surface and the at least one second surface; and

wherein the at least one first surface is connected to the at least one second surface by the at least one inflection point.

3. The device according to claim 1 further comprising a spacer layer arranged over the gate, wherein:

the at least one first surface is inclined with respect to a line perpendicular to an upper surface of the passivation layer; and

at least one of the at least one first surface extends to a bottom surface of the gate.

4. The device according to claim 2 wherein:

the gate further comprises a surface arranged along an upper surface of the passivation layer and the surface is connected to the portion;

the gate comprises a third surface; and

the at least one step portion is connected to the third surface.

5. The device according to claim 4 further comprising a spacer layer arranged over the gate,

wherein the third surface extends to a bottom surface of the gate.

6. The device according to claim 4 further comprising a spacer layer arranged over the gate,

wherein the third surface is inclined with respect to a line perpendicular to an upper surface of the passivation layer.

7. A device comprising:

a substrate;

a buffer layer on the substrate;

a barrier layer on the buffer layer;

a passivation layer on the barrier layer and the passivation layer comprising a recess;

a source electrically coupled to the barrier layer;

a gate on the barrier layer;

a drain electrically coupled to the barrier layer;

the gate comprising at least one first surface connected to at least one second surface through at least one inflection point on either side of the recess;

at least one step portion that includes the at least one inflection point; and

at least one field plate,

wherein the at least one inflection point, the at least one first surface, and the at least one second surface are arranged within the passivation layer;

wherein the gate fills the recess of the passivation layer;

wherein the at least one first surface comprises at least four of the at least one first surface; and

wherein the at least one second surface comprises at least four of the at least one second surface;

wherein the gate further comprises a portion arranged vertically above the at least one step portion;

wherein the at least one step portion includes the at least one first surface and the at least one second surface;

wherein the at least one first surface is connected to the at least one second surface by the at least one inflection point; and

wherein a depth of the at least one first surface along a line perpendicular to an upper surface of the passivation layer being 10%-80% of a depth of the passivation layer.

8. The device according to claim 2 further comprising a spacer layer arranged over the gate,

wherein a depth of the at least one second surface along a line parallel to an upper surface of the passivation layer is 5%-80% of a distance from a lower left edge of the gate to a lower right edge of the source.

9. The device according to claim 1 wherein:

the gate further comprises a surface arranged along an upper surface of the passivation layer and the surface is connected to a portion arranged vertically above the passivation layer; and

the gate is configured to modulate an electromagnetic field in a channel layer to lower a pinch-off voltage and reduce a leakage current flow.

10. The device according to claim 1 wherein:

the gate further comprises a surface arranged along an upper surface of the passivation layer and the surface is connected to a portion arranged vertically above the passivation layer; and

the gate is configured to enhance a depletion region in a channel layer to reduce a leakage current flow and maintain designed parasitic capacitances for designed device performance.

11. An amplifier comprising the device according to claim 1 .

12. A process of forming a device comprising:

providing a substrate;

arranging a buffer layer on the substrate;

arranging a barrier layer on the buffer layer;

electrically coupling a source to the barrier layer;

electrically coupling a drain to the barrier layer;

forming a passivation layer on the barrier layer and the passivation layer comprising a recess; and

forming a gate on the barrier layer and the gate extends across the passivation layer, the gate comprising at least one first surface connected to at least one second surface through at least one inflection point on either side of the recess,

wherein the at least one inflection point, the at least one first surface, and the at least one second surface are arranged within the passivation layer; and

wherein the gate fills the recess of the passivation layer;

wherein the at least one first surface comprises at least four of the at least one first surface; and

wherein the at least one second surface comprises at least four of the at least one second surface.

13. The process of forming the device according to claim 12 further comprising:

forming at least one step portion to include the at least one first surface, the at least one second surface, and the at least one inflection point; and

forming the at least one first surface to connect to the at least one second surface by the at least one inflection point,

wherein the gate further comprises a portion arranged vertically above the at least one step portion and vertically above the passivation layer.

14. The process of forming the device according to claim 13 further comprising:

forming the at least one first surface to be inclined with respect to a line perpendicular to an upper surface of the passivation layer, wherein at least one of the at least one first surface extends to a bottom surface of the gate; and

arranging a spacer layer over the gate.

15. The process of forming the device according to claim 13 further comprising:

forming the gate to include a third surface; and

forming the at least one step portion to connect to the third surface,

wherein the gate further comprises a surface arranged along an upper surface of the passivation layer and the surface is connected to the portion.

16. The process of forming the device according to claim 15 further comprising:

forming the third surface to extend to a bottom surface of the gate; and

arranging a spacer layer over the gate.

17. The process of forming the device according to claim 15 further comprising:

forming the third surface to be inclined with respect to a line perpendicular to an upper surface of the passivation layer; and

arranging a spacer layer over the gate.

18. The process of forming the device according to claim 14 wherein:

the at least one step portion comprises at least four of the at least one step portion.

19. The process of forming the device according to claim 13 further comprising:

forming at least one field plate; and

forming the at least one step portion to have a depth of the at least one first surface along a line perpendicular to an upper surface of the passivation layer can be 10%-80% of a depth of the passivation layer.

20. The process of forming the device according to claim 13 further comprising forming the at least one step portion to have a depth of the at least one second surface along a line parallel to an upper surface of the passivation layer to be 5%-80% of a distance from a lower left edge of the gate to a lower right edge of the source.

21. The process of forming the device according to claim 12 further comprising forming the gate to modulate an electromagnetic field in a channel layer to lower a pinch-off voltage and reduce a leakage current flow and maintain designed parasitic capacitances for designed device performance,

wherein the gate further comprises a surface arranged along an upper surface of the passivation layer and the surface is connected to a portion arranged vertically above the passivation layer.

22. The process of forming the device according to claim 12 further comprising forming the gate to enhance a depletion region in a channel layer to reduce a leakage current flow and maintain designed parasitic capacitances for designed device performance,

wherein the gate further comprises a surface arranged along an upper surface of the passivation layer and the surface is connected to a portion arranged vertically above the passivation layer.

23. The process of forming the device according to claim 13 wherein the forming the at least one step portion comprises:

forming at least one layer of the passivation layer;

etching the at least one layer of the passivation layer to form an etched surface consistent with at least a portion of the at least one step portion in the at least one layer of the passivation layer; and

forming the gate in the etched surface so as to form the gate with the at least one step portion in the at least one layer of the passivation layer.

24. The device according to claim 1 further comprising a spacer layer arranged over the gate,

wherein the gate further comprises a portion arranged vertically above the at least one inflection point, the at least one first surface, the at least one second surface and the passivation layer; and

wherein the gate further comprises a surface arranged along an upper surface of the passivation layer and the surface is connected to the portion.

25. The process of forming the device according to claim 13 further comprising arranging a spacer layer over the gate,

wherein the gate further comprises a portion arranged vertically above the at least one inflection point, the at least one first surface, the at least one second surface and the passivation layer; and

wherein the gate further comprises a surface arranged along an upper surface of the passivation layer and the surface is connected to the portion.

Assignments (9)

Continuity (1)