Power semiconductor devices, methods, and structures with embedded dielectric layers containing permanent charges
View Patent ↗Power devices using refilled trenches with permanent charge at or near their sidewalls. These trenches extend vertically into a drift region.
1. A semiconductor device, comprising:
a current-controlling structure at a first surface of a semiconductor mass;
a semiconductive drift region extending down into said semiconductor mass; said current-controlling structure and said drift region being jointly connected in series between a first source/drain region at said first surface, and a second source/drain region which is not connected to said first source/drain region; and
trenches extending down into said semiconductor mass, at least some of said trenches being at least partially filled with a trench-filling material which is not an insulator, and which is electrically separated from said drift region and electrically connected to said second source/drain region.
2. The device of claim 1 , wherein permanent electrostatic charge is present at sidewalls of said trenches.
3. The device of claim 1 , wherein said trenches are lined with a dielectric layer which contains immobile cesium ions.
4. The device of claim 1 , wherein the device is unipolar, and said first source/drain region is a source.
5. The device of claim 1 , wherein the device is a diode, and said first source/drain region is a cathode.
6. The device of claim 1 , wherein said semiconductor mass is a Group IV semiconductor.
7. The device of claim 1 , wherein said mass is a die of crystalline semiconductive material.
8. The device of claim 1 , wherein said trench-filling material is a semiconductive material.
9. The device of claim 1 , wherein said trench-filling material is made of the same semiconductive material as said drift region.
10. The device of claim 1 , wherein said trench-filling material is a doped crystalline semiconductive material.
11. The device of claim 1 , wherein said trench-filling material is a semiconductive material grown by selective epitaxy.
12. The device of claim 1 , wherein said trench-filling material is a semiconductive material which has approximately the same doping as said drift region.
13. The device of claim 1 , wherein said trenches are generally shaped as linear slots, and said trench-filling material is semiconductive, and wherein the volumetric doping density of said trench-filling material, times the width of said trenches, is approximately equal to the volumetric doping density of said drift region, times the distance between adjacent ones of said trenches.
14. The device of claim 1 , wherein said second source/drain region is connected as an anode.
15. The device of claim 1 , wherein said trench-filling material is at least partly insulated from said drift region.
16. The device of claim 1 , wherein said trench-filling material is completely insulated from said drift region.
17. The device of claim 1 , wherein said trench-filling material extends down to contact said drift region directly.
18. The device of claim 1 , wherein said trench-filling material is at least partly insulated from said drift region, and not insulated from said second source/drain region.
19. A semiconductor power device, comprising:
a layered semiconductor structure which includes at least an upper semiconductor portion and a lower semiconductor portion;
said upper portion including a current-controlling structure, and said lower portion including a drift region; said current-controlling structure and said drift region being jointly connected in series between a first source/drain region at said first surface, and a second source/drain region; and
trenches extending down into said semiconductor structure, at least some ones of said trenches being at least partially filled with a trench-filling material which is not an insulator, and which is electrically separated from said drift region and electrically connected to said second source/drain region.
20. The device of claim 19 , wherein said lower portion is a crystalline semiconductor substrate, and said upper portion is an epitaxial layer on said substrate.
21. The device of claim 19 , wherein said trenches are lined with a dielectric layer which includes immobile cesium ions.
22. The device of claim 19 , wherein the device is unipolar, and said first source/drain region is a source.
23. The device of claim 19 , wherein said trench-filling material is at least partly insulated from said drift region.
24. The device of claim 19 , wherein said trench-filling material is completely insulated from said drift region.
25. The device of claim 19 , wherein said trench-filling material is at least partly insulated from said drift region, and not insulated from said second source/drain region.
26. The device of claim 19 , wherein said trench-filling material extends down to contact said drift region directly.
27. A semiconductor power device, comprising:
a current-controlling structure at a first surface of a semiconductor mass;
a semiconductive drift region extending down into said semiconductor mass;
said current-controlling structure and said drift region being jointly connected in series between a first source/drain region at said first surface, and a second source/drain region at a second surface of said semiconductor mass; and
trenches extending down through said drift region into said semiconductor mass, at least some ones of said trenches being at least partially filled with a trench-filling material which is not an insulator, and which is electrically connected to said second source/drain region;
said trenches and said current-controlling structure having completely independent lateral alignment.
28. The device of claim 27 , wherein said trenches and said current-controlling structure have different respective pitches.
29. The device of claim 27 , wherein permanent electrostatic charge is present at sidewalls of said trenches.
30. The device of claim 27 , wherein said trenches are lined with a dielectric layer which includes immobile ions.
31. The device of claim 27 , wherein the device is unipolar, and said first source/drain region is a source.
32. The device of claim 27 , wherein the device is a diode, and said first source/drain region is a cathode.
33. The device of claim 27 , wherein said semiconductor mass is a Group IV semiconductor.
34. The device of claim 27 , wherein said mass is a die of crystalline semiconductive material.
35. The device of claim 27 , wherein said trench-filling material is a semiconductive material.
36. The device of claim 27 , wherein said trench-filling material is made of the same semiconductive material as said drift region.
37. The device of claim 27 , wherein said trench-filling material is a doped crystalline semiconductive material.
38. The device of claim 27 , wherein said trench-filling material is a semiconductive material grown by selective epitaxy.
39. The device of claim 27 , wherein said trench-filling material is a semiconductive material which has approximately the same doping as said drift region.
40. The device of claim 27 , wherein said trenches are generally shaped as linear slots, and said trench-filling material is semiconductive, and wherein the volumetric doping density of said trench-filling material, times the width of said trenches, is approximately equal to the volumetric doping density of said drift region, times the distance between adjacent ones of said trenches.
41. The device of claim 27 , wherein said second source/drain region is connected as an anode.