Process for forming a short channel trench MOSFET and device formed thereby

• US 9,831,336 B2
• Filed: 11/10/2014
• Issued: 11/28/2017
• Est. Priority Date: 02/23/2006
• Status: Active Grant

• Current Assignee: Vishay Siliconix
• Original Assignee: Vishay Siliconix
• Inventors: Lee, Zachary, Pattanayak, Deva
• Primary Examiner(s): Han, Jonathan
• Assistant Examiner(s): Vu, David
• Application Number:
  US14/537,760
• Publication Number:
  US 20150061000A1
• Time in Patent Office: 1,114 Days
• Field of Search: 257329, 257330, 257331, 257341, 257342
• CPC Class Codes: H01L 21/26513 of electrically active species
• 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 29/0878 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 29/4236 within a trench, e.g. trench gate electrode, groove gate electrode
• 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

Abstract

A process for forming a short channel trench MOSFET. The process includes forming a first implant at the bottom of a trench that is formed in the body of the trench MOSFET and forming a second or angled implant that is tilted in its orientation and directed perpendicular to the trench that is formed in the body of the trench MOSFET. The second implant is adjusted so that it does not reach the bottom of the trench. In one embodiment the angled implant is n-type material.

Claims

1. A short-channel trench MOSFET, comprising;

a substrate;

a trench formed in said substrate;

a first implant formed at a bottom of said trench; and

a second implant formed in said substrate that is tilted in orientation and adjusted to not reach said bottom of said trench.

2. The short-channel trench MOSFET of claim 1 wherein said first implant is self-aligned to said trench bottom and defines a channel bottom.

3. The short-channel trench MOSFET of claim 1 wherein said second implant is an anti-pinching implant.

4. The short-channel trench MOSFET of claim 1 wherein said trench has a depth that determines a channel length.

5. The short-channel trench MOSFET of claim 1 wherein said second implant is formed prior to the formation of contact and contact-clamping implants.

6. The short-channel trench MOSFET of claim 1 wherein said second implant is formed at two twist angles.

7. The short-channel trench MOSFET of claim 1 wherein said first implant comprises an n-type dopant.

8. The short-channel trench MOSFET of claim 2 wherein said second implant comprises an n-type dopant.

9. A trench MOSFET, comprising;

a substrate;

a trench formed in said substrate;

a first implant formed at a bottom of said trench; and

a second implant formed in said substrate that is tilted in orientation, having a serpentine shape, and adjusted to not reach said bottom of said trench.

10. The trench MOSFET of claim 9 wherein said first implant is self-aligned to said trench bottom and defines a channel bottom.

11. The trench MOSFET of claim 9 wherein said second implant is an anti-pinching implant.

12. The trench MOSFET of claim 9 wherein said trench has a depth that determines a channel length.

13. The trench MOSFET of claim 9 wherein said second implant is formed prior to the formation of contact and contact-clamping implants.

14. The trench MOSFET of claim 9 wherein said second implant is formed at two twist angles.

15. The trench MOSFET of claim 9 wherein said first implant comprises an n-type dopant.

16. The trench MOSFET of claim 10 wherein said second implant comprises an n-type dopant.

17. A short channel trench MOSFET, comprising;

a substrate;

a trench formed in said substrate;

a first implant formed at a bottom of said trench; and

a second implant formed in said substrate via angled implantation, wherein said second implant has a doping profile reflecting said angled implantation, and adjusted to not reach said bottom of said trench,

wherein said second implant is configured to prevent pinch-off of said short channel.

18. The short channel trench MOSFET of claim 17, wherein bottom of said trench defines a bottom of the MOSFET channel.

19. The short channel trench MOSFET of claim 17, wherein said second implant is configured to confine p-type regions formed by a contact implant and a contact-clamping implant such that said contact implant and said contact-clamping implant remain above the bottom of said trench.

20. The short channel trench MOSFET of claim claim 17, wherein said second implant is configured to be implanted at an angle through a contact window.