Trench transistors and methods for fabricating trench transistors

• US 6,903,416 B2
• Filed: 09/29/2003
• Issued: 06/07/2005
• Est. Priority Date: 09/27/2002
• Status: Expired due to Fees

• Current Assignee: Infineon Technologies AG
• Original Assignee: Infineon Technologies AG
• Inventors: Hirler, Franz, Henninger, Ralf
• Primary Examiner(s): Hu, Shouxiang
• Application Number:
  US10/673,966
• Publication Number:
  US 20040104428A1
• Time in Patent Office: 617 Days
• Field of Search: 257328-342
• US Class Current: 257/330
• CPC Class Codes: H01L 21/2254 from or through or into an applied layer, e.g. photoresist, nitrides
• CPC Class Codes: H01L 21/2255 the applied layer comprising oxides only, e.g. P2O5, PSG, H3BO3, doped oxides
• 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 29/4232 with insulated gate
• CPC Class Codes: H01L 29/4238 characterised by the surface lay-out
• CPC Class Codes: H01L 29/456 on silicon
• CPC Class Codes: H01L 29/66727 with a step of recessing the source 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 29/7802 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

Abstract

A trench transistor has a source zone introduced from a doped spacer into a body region and a channel running vertically along the insulation layer of the trench. A method is taught for fabricating the trench transistor of this type.

Claims

1. A trench transistor, comprising:

a semi-conductor body of a first conduction type having a surface region;

a semiconductor region of a second conduction type opposite to said first conduction type provided in said surface region of said semiconductor body and having a top surface;

a trench formed in said semiconductor body and said semiconductor region and extending from said top surface of said semiconductor region to a level below said semiconductor region, said trench having a wall, a lower region, and an upper region;

an insulation layer at least partially lining said wall of said trench and having an upper end;

a conductive trench filling disposed in said lower region of said trench and having a top side;

an insulating trench filling disposed in said upper region of said trench, having a top surface, and adjoining said top side of said conductive trench filling; and

a semiconductor zone of said first conduction type provided along said insulation layer in said semiconductor region and having a lower edge;

said upper end of said insulation layer and said top surface of said insulating trench filling at least partially disposed above said surface of said semiconductor region;

said lower edge of said semiconductor zone being curved and lying lower than said top side of said conductive trench filling;

a spacer provided along said insulation layer and disposed above said top surface of said semiconductor region and serving as a dopant source for said semiconductor zone; and

a channel zone running along said insulation layer in said semiconductor region.

2. The trench transistor according to claim 1, wherein said top surface of said semiconductor region has a an additional trench formed between two cells.

3. The trench transistor according to claim 1, further comprising a silicide layer in contact with said semiconductor region and said semiconductor zone.

4. The trench transistor according to claim 1, wherein said semiconductor region has a contact zone.

5. The trench transistor according to claim 4, wherein said contact zone is implanted.

6. The trench transistor according to claim 1, further comprising an insulating spacer layer underlying said spacer.

7. The trench transistor according to claim 6, wherein said insulating spacer layer is made of a material selected from the group consisting of silicon nitride and silicon oxide.

8. The trench transistor according to claim 1, wherein said spacer is made of a material selected from the group consisting of polycrystalline silicon, a metal provided with dopant, borophosphosilicate glass, phosphosilicate glass, and borosilicate glass.

9. The trench transistor according to claim 1, wherein said semiconductor body is made from a material selected from the group consisting of silicon, silicon carbide, and a compound semiconductor.

10. The trench transistor according to claim 1, further comprising additional electrodes disposed in said trench.

11. The trench transistor according to claim 1, further comprising a field plate disposed in said trench.