Insulated gate semiconductor device having shield electrode structure

• US 8,907,394 B2
• Filed: 06/03/2014
• Issued: 12/09/2014
• Est. Priority Date: 07/16/2012
• Status: Active Grant

• Current Assignee: Semiconductor Components Industries LLC (ON Semiconductor Corporation)
• Original Assignee: Semiconductor Components Industries LLC (ON Semiconductor Corporation)
• Inventors: Hossain, Zia
• Primary Examiner(s): Vu, David
• Assistant Examiner(s): FOX, BRANDON C
• Application Number:
  US14/294,971
• Publication Number:
  US 20140284710A1
• Time in Patent Office: 189 Days
• Field of Search: 257/302, 257/330, 438/270
• US Class Current: 257/302
• 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 29/0878 Impurity concentration or distribution
• CPC Class Codes: H01L 29/36 characterised by the concentration or distribution of impurities in the bulk material within semiconductor regions H01L29/06
• CPC Class Codes: H01L 29/407 Recessed field plates, e.g. trench field plates, buried field plates
• CPC Class Codes: H01L 29/41 characterised by their shape, relative sizes or dispositions
• CPC Class Codes: H01L 29/41766 with at least part of the source or drain electrode having contact below the semiconductor surface, e.g. the source or drain electrode formed at least partially in a groove or with inclusions of conductor inside the semiconductor H01L29/41733 - H01L29/41758 take precedence
• CPC Class Codes: H01L 29/4236 within a trench, e.g. trench gate electrode, groove gate electrode
• CPC Class Codes: H01L 29/42376 characterised by the length or the sectional shape
• CPC Class Codes: H01L 29/66666 Vertical transistors H01L29/66712, H01L29/66742 take precedence
• CPC Class Codes: H01L 29/66734 with a step of recessing the gate electrode, e.g. to form a trench gate electrode
• 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 29/7827 Vertical transistors H01L29/7802, H01L29/78642 take precedence

Abstract

In one embodiment, a semiconductor device includes a multi-portion shield electrode structure formed in a drift region. The shield electrode includes a wide portion formed in proximity to a channel side of the drift region, and a narrow portion formed deeper in the drift region. The narrow portion is separated from the drift region by a thicker dielectric region, and the wide portion is separated from the drift region by a thinner dielectric region. That portion of the drift region in proximity to the wide portion can have a higher dopant concentration than other portions of the drift region.

Claims

1. An insulated gate semiconductor device structure comprising:

a region of semiconductor material including a semiconductor layer of a first conductivity type and having a major surface;

a body region of a second conductivity type formed in the semiconductor layer extending from the major surface; and

a trench structure formed in the semiconductor layer extending from the major surface adjacent the body region, and wherein the trench structure comprises;

an insulated gate electrode; and

a shield electrode having a first portion and a second portion, wherein the first portion is wider than the second portion, and wherein the first portion is between the gate electrode and the second portion, and wherein the first portion is separated at least in part from the semiconductor layer by a first dielectric layer, and wherein the second portion is separated from the semiconductor layer by a second dielectric layer that is thicker than the first dielectric layer, and wherein the semiconductor layer has a first dopant concentration in proximity to the first portion and a second dopant concentration in proximity to the second portion, and wherein the first dopant concentration is greater than the second dopant concentration.

2. The structure of claim 1, wherein the insulated gate electrode includes a gate electrode separated from the semiconductor layer by a third dielectric layer, and wherein the third dielectric layer is thinner than the first dielectric layer.

3. The structure of claim 1 further comprising a source region formed in spaced relationship with the body region, and wherein the insulated gate electrode includes a gate electrode having a wide portion in proximity to the body region and narrow portion in proximity to the source region.

4. The structure of claim 1 further comprising a dielectric liner formed between the first dielectric layer and the first portion.

5. The structure of claim 4, wherein the dielectric liner comprises a nitride, and wherein the first dielectric layer comprises an oxide.

6. The structure of claim 1, wherein the insulated gate electrode includes a gate electrode having a wide portion in proximity to the body region and fin portions between the wide portion and the shield electrode.

7. The structure of claim 1, wherein the body region and the semiconductor layer form a junction, and wherein the first portion is formed in proximity to the junction.

8. A semiconductor device comprising:

a region of semiconductor material having a semiconductor layer of a first conductivity type and having a major surface;

a trench structure comprising;

shield electrode within the trench structure having a first portion and a second portion, wherein the first portion is wider than the second portion, and wherein the first portion is separated at least in part from the semiconductor layer by a first dielectric layer, and wherein the second portion is separated from the semiconductor layer by a second dielectric layer thicker than the first dielectric layer; and

an insulated gate electrode;

a doped region of the first conductivity type in the semiconductor layer in proximity to the first portion of the shield electrode but not in proximity to at least a portion of the second portion of the shield electrode, wherein the doped region has a higher dopant concentration than that of the semiconductor layer; and

a body region of a second conductivity type in the semiconductor layer extending from the major surface, wherein the body region and the trench structure are adjacent, wherein the body region is between the major surface and the doped region.

9. The semiconductor device of claim 8, wherein the doped region is in proximity to the first portion but not adjoining any part of the second portion.

10. The semiconductor device of claim 8 further comprising a dielectric liner between the first dielectric layer and the first portion.

11. The semiconductor device of claim 10, wherein the dielectric liner comprises a nitride liner.

12. The semiconductor device of claim 8, wherein the insulated gate electrode comprises an insulated gate electrode having a wide portion and fin portions, wherein the fin portions are between the shield electrode and the wide portion of the insulated gate electrode.

13. The semiconductor device of claim 8 further comprising a source region within the body region, and wherein the insulated gate electrode comprises an insulated gate electrode having a wide portion and a narrow portion, and wherein the narrow portion is proximate to the source region.

14. A semiconductor device comprising:

a region of semiconductor material having a semiconductor layer of a first conductivity type and having a major surface;

a trench structure extending from the major surface at least into the semiconductor layer;

a shield electrode within the trench structure having a first portion and a second portion, wherein the first portion is wider than the second portion, and wherein the first portion is separated at least in part from the semiconductor layer by a first dielectric layer, and wherein the second portion is separated from the semiconductor layer by a second dielectric layer that is thicker than the first dielectric layer;

a dielectric liner between the first dielectric layer and the first portion of the shield electrode;

an insulated gate electrode in the trench structure;

a body region of a second conductivity type in the semiconductor layer extending from the major surface, wherein the body region and the trench structure are adjacent; and

a source region of the first conductivity type in spaced relationship with the body region.

15. The semiconductor device of claim 14 further comprising a doped region of the first conductivity type in the semiconductor layer in proximity to the first portion of the shield electrode, wherein the body region is between the major surface and the doped region, and wherein the doped region has a higher dopant concentration than that of the semiconductor layer.

16. The semiconductor device of claim 15, wherein the doped region is in proximity to the first portion of the shield electrode but not in proximity to at least a portion of the second portion of the shield electrode.

17. The semiconductor device of claim 14, wherein the dielectric liner comprises a nitride liner.

18. The semiconductor device of claim 14, wherein the insulated gate electrode comprises an insulated gate electrode having a wide portion and fin portions, wherein the fin portions are between the shield electrode and the wide portion of the gate electrode.

19. The semiconductor device of claim 14, wherein the insulated gate electrode comprises an insulated gate electrode having a wide portion and a narrow portion, and wherein the narrow portion is adjacent the source region.

20. A semiconductor device comprising:

a region of semiconductor material having a semiconductor layer of a first conductivity type and having a major surface;

a trench structure extending from the major surface at least into the semiconductor layer comprising;

a shield electrode within the trench structure having a first portion and a second portion, wherein the first portion is wider than the second portion, and wherein the first portion is separated at least in part from the semiconductor layer by a first dielectric layer, and wherein the second portion is separated from the semiconductor layer by a second dielectric layer that is thicker than the first dielectric layer; and

an insulated gate electrode in the trench structure, wherein the trench structure has a first width proximate to the second portion of the shield electrode and a second width proximate to the insulated gate electrode, and wherein the first width is greater than the second width;

a body region of a second conductivity type in the semiconductor layer extending from the major surface, wherein the body region and the trench structure are adjacent; and

a source region of the first conductivity type in spaced relationship with the body region.

21. The semiconductor device of claim 20 further comprising a dielectric liner between the first dielectric layer and the first portion of the shield electrode.

22. The semiconductor device of claim 20 further comprising a doped region of the first conductivity type in the semiconductor layer in proximity to the first portion of the shield electrode, wherein the body region is between the major surface and the doped region, and wherein the doped region has a higher dopant concentration than that of the semiconductor layer.