Implantation method

• US 6,802,719 B2
• Filed: 09/06/2001
• Issued: 10/12/2004
• Est. Priority Date: 09/09/2000
• Status: Expired due to Term

• Current Assignee: Zetex Plc (Diodes Incorporated)
• Original Assignee: Zetex Plc (Diodes Incorporated)
• Inventors: Finney, Adrian
• Primary Examiner(s): Mulpuri, Savitri
• Application Number:
  US09/947,791
• Publication Number:
  US 20020048913A1
• Time in Patent Office: 1,132 Days
• Field of Search: 438/302, 438/514, 438/524, 438/525
• US Class Current: 438/270
• CPC Class Codes: H01L 21/26586 characterised by the angle between the ion beam and the crystal planes or the main crystal surface

Abstract

A method for implanting ions into a surface of a semiconductor structure covered by a layer of insulating material, for example into a trench wall covered by a layer of oxide. A beam of ions is directed at a glancing angle to the layer of insulating material such that a substantial proportion of ions which are implanted into the semiconductor structure surface are scattered from the beam by the layer of insulating material. It is possible therefore to implant ions into a trench wall without requiring a beam source arranged to deliver a beam at a large angle to the trench wall surface.

Claims

1. A method for implanting ions into a surface of a semiconductor structure covered by a layer of insulating material, wherein a beam of ions is directed at the layer of insulating material such that a substantial proportion of ions which are implanted into the semiconductor structure surface are scattered from the beam by the layer of insulating material, wherein the surface is defined by a wall of trench formed in the semicoductor structure,

wherein, before ion implantation, the trench is partially filled with conductive material electrically insulated from the semiconductor structure,

wherein the trench is formed in the semiconductor structure, the trench walls are oxidized, and the trench is partially filled with a conductive material, the beam of ions being directed at a glancing angle to the oxide covering the trench walls above the conductive material, and

wherein the glancing angle is between approximately 0 and 10 degrees from the perpendicular to the surface of the semiconductor device.

2. A method according to claim 1, wherein the beam of ions is directed at a glancing angle to the layer of insulating material.

3. A method according to claim 1, wherein the insulating material is a layer of oxide.

4. A method according to claim 1, wherein the trench is formed in the semiconductor structure, the trench walls are oxidised, the trench is partially filled with the conductive material, oxide covering the trench walls above the conductive material is stripped away, and the walls of the trench above the conductive material are oxidised to form then insulating layer through which ions are implanted.

5. A method according to claim 1, wherein then trench is formed in them semiconductor structure, the trench walls are oxidised, the trench is partially filled with the conductive material, and the thickness of oxide covering the trench walls above the conductive material is reduced, the beam of ions being directed at a glancing angle to the remaining oxide covering the trench walls above the conductive material.

6. A method according to claim 1, wherein implanted ions are driven into the semiconductor structure by thermal processing.

7. The method recited in claim 1, wherein the semiconductor structure is a metal oxide semiconductor field effect transistor (MOSFET) structure.

8. The method recited in claim 7, wherein the MOSFET structure is a U-grooved metal oxide semiconductor (UMOS) structure.

9. A method of implanting ions into a surface of a semiconductor device wherein the semiconductor device has a surface with at least one trench gate semiconductor structure formed therein, the trench gate semiconductor structure having trench wall covered by a layer of insulating material, the method comprising directing a beam of ions at the layer of insulating material at an angle substantially perpendicular to the surface of the semiconductor device such that a substantial proportion of ions are scattered from the beam by the layer of insulating material and implanted into the trench wall,

wherein then angle is between approximately 0 and 10 degrees from the perpendicular to the surface of the semiconductor device.

10. The method recited in claim 9, wherein the insulating material is oxide.

11. The method recited in claim 9, wherein, before implantation, the trench is partially filled with a conductive material electrically insulated from the trench wall.

12. The method recited in claim 9, wherein the trench wall is oxidized, the trench is partially filled with a conductive material, oxide covering the trench wall above the conductive material is stripped away, and the trench wall above the conductive material is oxidized to form the insulating layer.

13. The method recited in claim 9, wherein the trench wall is oxidized, the trench is partially filled with a conductive material, and then thickness of oxide covering then trench wall above the conductive material is reduced, the beam of ions being directed at an angle substantially perpendicular to then surface of the semiconductor device to the remaining oxide covering the trench wall above the conductive material.

14. The method recited in claim 9, the trench wall is oxidized, the trench is partially filled within a conductive material, the beam of ions being directed at an angle substantially perpendicular to the surface of the semiconductor device to the oxide covering the trench wall above the conductive material.

15. The method recited in claim 9, wherein implanted ions are driven into the trench wall by thermal processing.

16. The method recited in claim 9, wherein the trench gate semiconductor structure is a trench gate metal oxide semiconductor field effect transistor (MOSFET) structure.