Trench MOSFET with sidewall spacer gates

• US 7,671,441 B2
• Filed: 04/03/2006
• Issued: 03/02/2010
• Est. Priority Date: 04/05/2005
• Status: Active Grant

• Current Assignee: Infineon Technologies Americas Corp. (Infineon Technologies AG)
• Original Assignee: International Rectifier Corporation (Infineon Technologies AG)
• Inventors: Henson, Timothy
• Primary Examiner(s): Fahmy; Wael
• Assistant Examiner(s): ARMAND, MARC ANTHONY
• Application Number:
  US11/396,759
• Publication Number:
  US 20060223260A1
• Time in Patent Office: 1,429 Days
• Field of Search: 257/500, 257/151, 257/E21.54, 257/E21.55, 257/153, 257/118, 257/244, 257/513, 257/594, 438/243, 438/391
• US Class Current: 257/500
• CPC Class Codes: H01L 21/2815 part or whole of the electrode is a sidewall spacer or made by a similar technique, e.g. transformation under mask, plating
• CPC Class Codes: H01L 29/0878 Impurity concentration or distribution
• 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 29/4933 with a silicide layer contacting the silicon layer, e.g. Polycide gate with a barrier layer between the silicide and silicon layers H01L29/4941
• 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 semiconductor power device includes a semiconductor body with a plurality of gate trenches formed therein. Disposed within each gate trench is a spacer gate that extends along at least a portion of the sidewalls of the gate trench but not along at least a portion of the bottom surface of the trench. The spacer gate of each gate trench may also include a layer of silicide along outer surfaces thereof. The semiconductor body may include a channel region and each gate trench may extend through the channel region and into the semiconductor body. Formed at the bottom of each gate trench within the semiconductor body may be a tip implant of the same conductivity as the semiconductor body. In addition, a deep body implant of the same conductivity as the channel region may be formed at the base of the channel region.

Claims

1. A power semiconductor device, comprising:

a semiconductor body of a first conductivity type;

at least one gate trench along a surface of said semiconductor body, said gate trench having sidewalls and a bottom surface;

a gate insulation layer lining at least portions of the sidewalls and the bottom surface of said gate trench;

an insulation body disposed within said gate trench adjacent said bottom surface thereof;

a gate electrode disposed between respective opposing sides of said insulation body and a respective sidewall of said gate trench, wherein each said gate electrode includes an outer surface facing said insulation body and interior of said gate trench, said outer surface including a top portion that curves downwardly toward the bottom of said gate trench and each said gate electrode including a silicide layer along an outer surface thereof;

each said silicide layer extending from the bottom surface of said gate trench towards an upper end of said gate trench;

a channel region of a second conductivity type in said semiconductor body, wherein said gate trench extends through said channel region; and

a tip implant of said first conductivity type formed within said semiconductor body at the bottom of said gate trench;

wherein said tip implant at the bottom of said gate trench is disposed directly below said insulation body within said gate trench and extends below said gate electrodes, wherein said gate insulation layer is disposed between said insulation body and said tip implant at the bottom of said gate trench.

2. The power semiconductor device of claim 1, wherein said insulation body within said gate trench extends from the bottom surface of said gate trench towards an upper end of said gate trench.

3. The power semiconductor device of claim 1, wherein said gate insulation layer within said gate trench has a substantially uniform thickness along the sidewalls and the bottom surface of said gate trench.

4. The power semiconductor device of claim , wherein said gate electrode within said gate trench has a thickness of about 100Å

to about 1000Å

along the sidewalls of said gate trench.

5. A power semiconductor device, comprising:

a semiconductor body of a first conductivity type;

a trench along a surface of said semiconductor body, said trench having sidewalls and a bottom surface;

a gate insulation layer lining at least portions of the sidewalls and the bottom surface of said trench;

spacer gate electrodes disposed along at least a portion of the sidewalls of said trench, said spacer gate electrodes within said trench forming a void therein that extends from an upper end of said trench to the bottom surface of said trench; and

an insulation body adjacent the bottom surface of said trench and filling said void formed by said spacer gate electrodes within said trench, wherein each said spacer gate electrode includes a silicide layer along an outer surface thereof disposed between said gate electrode and said insulation body;

a channel region of a second conductivity type in said semiconductor body, wherein said trench extends through said channel region;

a deep body implant of said second conductivity type formed along a bottom of said channel region and extending to said trench; and

a tip implant of said first conductivity type formed within said semiconductor body directly below the bottom of said trench, wherein said tip implant extends deeper into said semiconductor body than said deep body implant.