Semiconductor component comprising trench structures and production method therefor

• US 10,593,799 B2
• Filed: 08/10/2018
• Issued: 03/17/2020
• Est. Priority Date: 08/11/2017
• Status: Active Grant

• Current Assignee: Infineon Technologies AG
• Original Assignee: Infineon Technologies AG
• Inventors: Zundel, Markus, Bach, Karl-Heinz, Brandl, Peter, Wood, Andrew Christopher Graeme
• Primary Examiner(s): Harriston, William A
• Application Number:
  US16/100,496
• Publication Number:
  US 20190051749A1
• Time in Patent Office: 585 Days
• CPC Class Codes: H01L 21/2253 by ion implantation
• CPC Class Codes: H01L 21/2257 the applied layer being silicon or silicide or SIPOS, e.g. polysilicon, porous silicon
• 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 21/266 using masks H01L21/26586 takes precedence
• CPC Class Codes: H01L 29/0696 of cellular field-effect devices, e.g. multicellular DMOS transistors or IGBTs
• CPC Class Codes: H01L 29/0878 Impurity concentration or distribution
• 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 29/404 Multiple field plate structures
• CPC Class Codes: H01L 29/407 Recessed field plates, e.g. trench field plates, buried field plates
• CPC Class Codes: H01L 29/4236 within a trench, e.g. trench gate electrode, groove gate electrode
• CPC Class Codes: H01L 29/66666 Vertical transistors H01L29/66712, H01L29/66742 take precedence
• CPC Class Codes: H01L 29/66712 Vertical DMOS transistors, i.e. VDMOS transistors
• 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 29/7802 Vertical DMOS transistors, i.e. VDMOS transistors
• 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

A semiconductor component includes a field-effect transistor arrangement having a drift zone and body region between the drift zone and a first surface of a semiconductor body. Trench structures of a first type extend from the first surface into the semiconductor body and have a maximum lateral dimension at the first surface which is less than a depth of first and second ones of the trench structures. A net doping concentration at a reference depth at a first location in the drift zone is at least 10% greater than at a second location in the drift zone at the reference depth, which is located between the body region and a bottom of the first trench structure. The first location is at the same first lateral distance from the first and second trench structures. The second location is at the same second lateral distance from the first and second trench structures.

Claims

1. A semiconductor component, comprising:

a field effect transistor arrangement in a semiconductor body, the field effect transistor arrangement comprising a drift zone and a body region between the drift zone and a first surface of the semiconductor body;

a plurality of acicular trench structures comprising a first and a second acicular trench structure, which extend from the first surface into the semiconductor body and have a maximum lateral dimension at the first surface which is less than a depth of the first and second acicular trench structures; and

at least one trench structure of a second type which comprises a gate electrode and a gate dielectric and extends from the first surface into the semiconductor body less deeply than the plurality of acicular trench structures,

wherein the at least one trench structure of the second type forms grid spanning elements,

wherein one of the first or second acicular trench structures is positioned at a centre of the grid spanning elements,

wherein a net doping concentration is 10% greater at a first location in the drift zone than at a second location in the drift zone at a reference depth which is located between the body region and a bottom of the first acicular trench structure,

wherein the first location is at a same first lateral distance from the first and from the second acicular trench structure, the second location is at a same second lateral distance from the first acicular trench structure and from the second acicular trench structure,

wherein the second distance is greater than the first distance.

2. The semiconductor component of claim 1, wherein the first distance is a shortest lateral distance from the first acicular trench structure and from the second acicular trench structure.

3. The semiconductor component of claim 1, wherein the second distance is maximally double the magnitude of the first distance.

4. The semiconductor component of claim 1, wherein each acicular trench structure of the plurality of acicular trench structures comprises a field electrode and a field dielectric.

5. The semiconductor component of claim 1, wherein a minimum lateral dimension of the first acicular trench structure at the first surface is at least 20% of a maximum lateral dimension of the first acicular trench structure at the first surface.

6. The semiconductor component of claim 1, wherein the net doping concentration in the drift zone decreases continuously along a direct connecting line from the first location to the second location.

7. The semiconductor component of claim 1, wherein the doping concentration at the reference depth along a path section has at least two maxima and at least two minima, and wherein the path section extends around the first acicular trench structure and has a distance from the first acicular trench structure that corresponds maximally to the second distance.

8. The semiconductor component of claim 1, wherein a maximum doping concentration at the reference depth in a vertical direction is located below a bottom of the at least one trench structure of the second type.

9. The semiconductor component of claim 1, wherein a minimum doping concentration at the reference depth in a vertical direction is located below a bottom of the at least one trench structure of the second type.

10. The semiconductor component of claim 1, wherein a degree of compensation of the doping at the reference depth is greater at the second location than at the first location.

11. The semiconductor component of claim 1, further comprising:

at least one trench structure of a third type which comprises a dopant source and extends less deeply from the first surface into the semiconductor body than the plurality of acicular trench structures.

12. The semiconductor component of claim 11, wherein the dopant source comprises doped polycrystalline silicon.

13. A semiconductor component, comprising:

a field effect transistor arrangement in a semiconductor body, the field effect transistor arrangement comprising a drift zone and a body region between the drift zone and a first surface of the semiconductor body;

a first trench structure extending from a first surface into the semiconductor body and having a maximum lateral dimension at the surface which is less than a depth of the trench structure, wherein the trench structure comprises a field electrode and a field dielectric; and

a second trench structure which comprises a gate electrode and a gate dielectric and extends from the first surface into the semiconductor body less deeply than the first trench structure,

wherein a net doping concentration at a reference depth, which is located between the body region and a bottom of the first trench structure, along a path section which extends around the first trench structure at the reference depth has at least two maxima and at least two minima.

14. The semiconductor component of claim 13, wherein a maximum lateral distance between the first trench structure and the path section extending around the first trench structure is less than a shortest lateral distance between the first trench structure and the second trench structure.

15. A method for producing a semiconductor component, the method comprising:

forming a field effect transistor arrangement in a semiconductor body, comprising;

forming a plurality of acicular trenches comprising a first and a second acicular trench, which extend from a first surface into the semiconductor body and have a maximum lateral dimension at the first surface which is less than a depth of the first and second acicular trenches, wherein the first acicular trench and the second acicular trench are directly adjacent;

forming at least one trench structure of a second type which comprises a gate electrode and a gate dielectric and extends from the first surface into the semiconductor body less deeply than the plurality of acicular trenches, the at least one trench structure of the second type forming grid spanning elements, wherein one of the first or second acicular trench structures is positioned at a centre of the grid spanning elements; and

setting a net doping concentration in a drift zone at a first location, which is at a same first lateral distance from the first acicular trench and from the second acicular trench, to be at least 10% greater than at a second location, which is at a same second lateral distance from the first acicular trench and from the second acicular trench, wherein the second distance is greater than the first distance and the first location and also the second location are located at a reference depth between the first surface and a bottom of the first acicular trench.

16. The method of claim 15, further comprising:

forming a field dielectric and a field electrode in the plurality of acicular trenches.

17. The method of claims 15, wherein setting the net doping concentration in the drift zone comprises:

implanting dopants of a conductivity type corresponding to the conductivity type of the drift zone,

wherein the dopants are implanted into the semiconductor body through an opening of an implantation mask that is formed above the first location in a vertical direction.

18. The method of claim 15, wherein setting the net doping concentration in the drift zone comprises:

implanting dopants of a conductivity type different from the conductivity type of the drift zone,

wherein the dopants are implanted into the semiconductor body through an opening of an implantation mask that is formed above the second location in a vertical direction.

19. The method of claim 15, wherein the net doping concentration is set in the drift zone by implanting dopants, wherein the dopants are implanted before forming the plurality of acicular trenches, and wherein a thickness of the semiconductor body is then increased by applying a semiconductor layer on the first surface of the semiconductor body.

20. The method of claim 15, wherein setting the net doping concentration in the drift zone comprises:

implanting dopants of a conductivity type corresponding to the conductivity type of the drift zone,

wherein the dopants are implanted through a sidewall of the first and second acicular trenches.

21. The method of claim 15, wherein setting the net doping concentration in the drift zone comprises:

forming at least one trench of a third type which extends from the first surface into the semiconductor body; and

forming a dopant source in the at least one trench of the third type and diffusing dopants from the dopant source into the drift zone via a sidewall of the at least one trench of the third type.

22. The method of claim 21, wherein the dopant source comprises doped polycrystalline silicon.