US 6,204,533 B1Granted

Vertical trench-gated power MOSFET having stripe geometry and high cell density

AssigneeSiliconix Incorporated

InventorsRichard K. Williams, Wayne B. Grabowski

Life of this patent

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Abstract

A vertical trench-gated power MOSFET includes MOSFET cells in the shape of longitudinal stripes. The body diffusion of each cell contains a relatively heavily-doped region which extends parallel to the length of the cell and contacts an overlying metal source/body contact layer at specific locations. In one embodiment, the contact is made at an end of the cell. In another embodiment, the contact is made at intervals along the length of the cell. In addition, the power MOSFET contains diode cells placed at intervals in the array of cells. The diode cells contain diodes connected in parallel with the MOSFET cells and protect the gate oxide layer lining the trenches from damage due to large electric fields and hot carrier injection. By restricting the areas where the body contact is made and using the diode cells, the width of the MOSFET cells can be reduced substantially, thereby reducing the on-resistance of the power MOSFET.

Claims8

Dependent claims

A power MOSFET formed in a semiconductor chip, said MOSFET comprising:

at least one MOSFET cell, said cell being formed in the shape of a longitudinal stripe having a length and a width, said stripe being located between opposing gate sections and having a top surface coincident with a surface of said chip, each of said gate sections being formed in a trench, said MOSFET cell comprising:
a source region of a first conductivity type located adjacent a portion of said top surface;
a body region of a second conductivity type located beneath said source region, said body region containing a channel region adjacent a wall of said trench;
a drain region of said first conductivity type adjoining said body region;
and
a heavily-doped region within said body region, said heavily-doped region being of said second conductivity type and having a dopant concentration greater than a dopant concentration of a remainder of said body region, said heavily-doped region extending along said length of said cell and including at least one contact portion which extends to said surface of said cell.

3 more elements

Dependencies are inferred from the claim text.

Facts

Application: 09/089,250Filed 2 Jun 1998 · continuation in part
Priority: 2 Jun 1995
Granted: 20 Mar 2001
Term ends: Not estimatedThe source records don’t support an estimate.

Classification8 codes

H10D 30/668
Vertical dmos [vdmos] fets: having trench gate electrodes, e.g. UMOS transistors
H10D 30/63
Insulated-gate field-effect transistors [IGFET]: vertical IGFETs
H10D 62/127
Top-view geometrical layouts of the regions or the junctions: of cellular field-effect devices, e.g. multicellular DMOS transistors or IGBTs
H10D 62/393
Semiconductor regions connected to electrodes not carrying current to be rectified, amplified or switched, e.g. channel regions: body regions of…

Family

Application08/459,555Parent of this continuation · filed 2 Jun 1995
Application08/846,688Parent of this continuation-in-part · filed 30 Apr 1997
Application08/919,523Parent of this continuation-in-part · filed 28 Aug 1997
US 5,998,837 AParent of this continuation-in-part
US 5,998,836 AParent of this continuation-in-part
Application08/846,688Parent of this continuation
US 6,204,533 B1This patent

From the US filing history. Foreign family members aren’t listed.