TRENCH MOSGATED DEVICE WITH DEEP TRENCH BETWEEN GATE TRENCHES

• US 20080211016A1
• Filed: 03/03/2008
• Published: 09/04/2008
• Est. Priority Date: 03/01/2007
• Status: Active Grant

• Current Assignee: Infineon Technologies Americas Corp. (Infineon Technologies AG)
• Original Assignee: International Rectifier Corporation (Infineon Technologies AG)
• Inventors: Boden, Milton J.
• Granted Patent: US 8,125,024 B2
• Time in Patent Office: Days
• US Class Current: 257/330
• CPC Class Codes: H01L 29/0653 adjoining the input or output region of a field-effect device, e.g. the source or drain region
• 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 29/41766 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 29/7813 with trench gate electrode, e.g. UMOS transistors trench gate electrodes per se H01L29/4236

Abstract

A trench gated MOSFET especially for operation in high radiation environments has a deep auxiliary trench located between the gate trenches. A boron implant is formed in the walls of the deep trench (in an N channel device); a thick oxide is formed in the bottom of the trench, and boron doped polysilicon which is connected to the source electrode fills the trench. The structure has reduced capacitance and improved resistance to single event rupture and single event breakdown and improved resistance to parasitic bipolar action.

Claims

1. A trench MOSFET structure comprising a plurality of parallel spaced gate trenches extending through a source region of a first conductivity type, an underlying channel region of the opposite conductivity type and into a drift region of the first conductivity type;

and a deep trench disposed between each pair of said gate trenches;

each of said deep trenches being filled with a conductive polysilicon of the conductivity type of said channel region; and

a top contact connected to said source region and said conductive polysilicon in said deep trenches.

2. The device of claim 1, wherein said deep trenches have a relatively thick insulation mass beneath said conductive polysilicon therein.

3. The device of claim 1, wherein the walls of said deep trench have an implant therein of the conductivity type of said polysilicon mass filling said deep trench.

4. The device of claim 2, wherein the walls of said deep trench have an implant therein of the conductivity type of said polysilicon mass filling said deep trench.