POWER SEMICONDUCTOR DEVICES, METHODS, AND STRUCTURES WITH Embedded Dielectric Layers Containing Permanent Charges

• US 20110079843A1
• Filed: 04/13/2010
• Published: 04/07/2011
• Est. Priority Date: 04/13/2009
• Status: Active Grant

• Current Assignee: MaxPower Semiconductor, Inc. (Vishay Intertechnology Incorporated)
• Original Assignee: MaxPower Semiconductor, Inc. (Vishay Intertechnology Incorporated)
• Inventors: Blanchard, Richard A., Darwish, Mohamed N., Zeng, Jun
• Granted Patent: US 8,330,213 B2
• Time in Patent Office: Days
• US Class Current: 257/331
• CPC Class Codes: H01L 21/26586 characterised by the angle between the ion beam and the crystal planes or the main crystal surface
• CPC Class Codes: H01L 29/0634 Multiple reduced surface field (multi-RESURF) structures, e.g. double RESURF, charge compensation, cool, superjunction (SJ), 3D-RESURF, composite buffer (CB) structures
• CPC Class Codes: H01L 29/0661 specially adapted for altering the breakdown voltage by removing semiconductor material at, or in the neighbourhood of, a reverse biased junction, e.g. by bevelling, moat etching, depletion etching
• CPC Class Codes: H01L 29/0873 Drain regions
• CPC Class Codes: H01L 29/0882 Disposition
• CPC Class Codes: H01L 29/1095 Body region, i.e. base region, of DMOS transistors or IGBTs cell layout H01L29/0696
• CPC Class Codes: H01L 29/402 Field plates
• CPC Class Codes: H01L 29/407 Recessed field plates, e.g. trench field plates, buried field plates
• CPC Class Codes: H01L 29/408 with an insulating layer with a particular dielectric or electrostatic property, e.g. with static charges or for controlling trapped charges or moving ions, or with a plate acting on the insulator potential or the insulator charges, e.g. for controlling charges effect or potential distribution in the insulating layer, or with a semi-insulating layer contacting directly the semiconductor surface
• CPC Class Codes: H01L 29/7802 Vertical DMOS transistors, i.e. VDMOS transistors
• CPC Class Codes: H01L 29/7811 with an edge termination structure guard regions per se H01L29/0619; field plates per se H01L29/402
• CPC Class Codes: H01L 29/7813 with trench gate electrode, e.g. UMOS transistors trench gate electrodes per se H01L29/4236
• CPC Class Codes: H01L 29/8611 Planar PN junction diodes

Abstract

Power devices using refilled trenches with permanent charge at or near their sidewalls. These trenches extend vertically into a drift region.

Claims

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 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.

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. 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 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.

16. The device of claim 15, wherein said lower portion is a crystalline semiconductor substrate, and said upper portion is an epitaxial layer on said substrate.

17. The device of claim 15, wherein said trenches are lined with a dielectric layer which includes immobile cesium ions.

18. The device of claim 15, wherein the device is unipolar, and said first source/drain region is a source.

19. The device of claim 15, wherein said semiconductor mass is a Group IV semiconductor.

20-21. -21. (canceled)

22. 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.

23-36. -36. (canceled)