Trench MOSFET having reduced gate charge

• US 9,318,598 B2
• Filed: 05/30/2014
• Issued: 04/19/2016
• Est. Priority Date: 05/30/2014
• Status: Active Grant

• Current Assignee: Texas Instruments, Inc.
• Original Assignee: Texas Instruments, Inc.
• Inventors: Grebs, Thomas Eugene, Kocon, Christopher Boguslaw, Rahman, Touhidur
• Primary Examiner(s): Nicely, Joseph C
• Application Number:
  US14/291,913
• Publication Number:
  US 20150349112A1
• Time in Patent Office: 690 Days
• US Class Current: 1/1
• CPC Class Codes: H01L 29/063 Reduced surface field [RESURF] pn-junction structures
• CPC Class Codes: H01L 29/0696 of cellular field-effect devices, e.g. multicellular DMOS transistors or IGBTs
• CPC Class Codes: H01L 29/0865 Disposition
• CPC Class Codes: H01L 29/0882 Disposition
• 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 29/402 Field plates
• CPC Class Codes: H01L 29/407 Recessed field plates, e.g. trench field plates, buried field plates
• CPC Class Codes: H01L 29/41741 for vertical or pseudo-vertical devices
• CPC Class Codes: H01L 29/4236 within a trench, e.g. trench gate electrode, groove gate electrode
• CPC Class Codes: H01L 29/4916 the conductor material next to the insulator being a silicon layer, e.g. polysilicon doped with boron, phosphorus or nitrogen H01L29/4908, H01L29/4983 take precedence
• CPC Class Codes: H01L 29/66356 Gated diodes, e.g. field controlled diodes [FCD], static induction thyristors [SITh], field controlled thyristors [FCTh]
• CPC Class Codes: H01L 29/7391 Gated diode structures
• CPC Class Codes: H01L 29/7803 structurally associated with at least one other device assemblies H01L25/00; integrated circuits H01L27/00
• CPC Class Codes: H01L 29/7804 the other device being a pn-junction diode
• CPC Class Codes: H01L 29/7805 in antiparallel, e.g. freewheel diode
• CPC Class Codes: H01L 29/7806 the other device being a Schottky barrier diode
• CPC Class Codes: H01L 29/7811 with an edge termination structure guard regions per se H01L29/0619; field plates per se H01L29/402
• CPC Class Codes: H01L 29/7813 with trench gate electrode, e.g. UMOS transistors trench gate electrodes per se H01L29/4236
• CPC Class Codes: H01L 29/861 Diodes

Abstract

A trench MOSFET device includes a semiconductor layer of a first doping type. MOS transistor cells are in a body region of a second doping type in the semiconductor layer. The transistor cells include a first cell type including a first trench providing a first gate electrode or the first gate electrode is on the semiconductor surface between the first trench and a second trench, and a first source region is formed in the body region. The first gate electrode is electrically isolated from the first source region. A second cell type has a third trench providing a second gate electrode or the second gate electrode is on the semiconductor surface between the third trench and a fourth trench, and a second source region is in the body region. An electrically conductive member directly connects the second gate electrode, first source region and second source region together.

Claims

1. A trench metal-oxide-semiconductor field-effect transistor (MOSFET) device, comprising:

a semiconductor layer of a first doping type to form a drain region;

a body region of a second doping type positioned above the drain region;

a source region of the first doping type positioned above the body region;

an active transistor cell including;

a first gate electrode positioned in a first trench extending through the source region and the body region; and

a dielectric liner positioned in the first trench and isolating the first gate electrode from the source region; and

a diode-connected transistor cell adjacent to the active transistor cell, the diode-connected transistor cell including;

a second gate electrode positioned in a second trench extending through the source region and the body region; and

a conductor coupling the second gate electrode with the source region adjacent to the second gate electrode to establish a diode structure.

2. The trench MOSFET device of claim 1, further comprising:

an epitaxial layer positioned above the semiconductor layer, the epitaxial layer defining a drain drift region under the body region.

3. The trench MOSFET device of claim 1, wherein the first doping type is n-type, and the active transistor cell includes n-channel between the drain region and the source region.

4. The trench MOSFET device of claim 1, wherein the first doping type is p-type and the active transistor cell includes a p-channel between the drain region and the source region.

5. The trench MOSFET device of claim 1, wherein the first gate electrode and the second gate electrode both comprise polysilicon.

6. The trench MOSFET device of claim 1, wherein the active transistor cell includes N first gate electrodes positioned in N first trenches, each extending through the source region and the body region, the diode-connected transistor cell includes M second gate electrodes positioned in M first trenches, each extending through the source region and the body region such that a ratio of N over M ranges from 3:

1 to 10;

1.

7. The trench MOSFET device of claim 1, wherein the conductor includes a metal filled trench extending into the second gate electrode and connecting to a source metal layer above the source region.

8. The trench gate MOSFET device of claim 1, further comprising:

a source contact hole positioned between the first gate electrode and the second gate electrode, the source contact hole extending into the source region;

wherein the conductor couples the second gate electrode with the source region via the source contact hole.