US 8,558,275 B2 · Sawtooth electric field drift region structure for power semiconductor devices

Abstract

This invention discloses a semiconductor power device formed in a semiconductor substrate. The semiconductor power device further includes rows of multiple horizontal columns of thin layers of alternate conductivity types in a drift region of the semiconductor substrate where each of the thin layers having a thickness to enable a punch through the thin layers when the semiconductor power device is turned on. In a specific embodiment the thickness of the thin layers satisfying charge balance equation q*ND*WN=q*NA*WP and a punch through condition of WP<2*WD*[ND/(NA+ND)] where ND and WN represent the doping concentration and the thickness of the N type layers 160, while NA and WP represent the doping concentration and thickness of the P type layers; WD represents the depletion width; and q represents an electron charge, which cancel out. This device allows for a near ideal rectangular electric field profile at breakdown voltage with sawtooth like ridges. In another exemplary embodiment, the semiconductor power device further includes a sawtooth insulated gate bipolar transistor (IGBT). In another exemplary embodiment, the semiconductor power device further includes a metal oxide semiconductor field effect transistor (MOSFET). In another exemplary embodiment, the semiconductor power device further includes a power diode.

Claims20

Dependent claims

A vertical semiconductor power device formed in a semiconductor substrate comprising:

a first electrode disposed on a top surface and a plurality of dopant regions near the top surface in an epitaxial layer wherein a bottom portion of the epitaxial layer below the dopant regions constituting a uniformly doped region extending continuously and horizontally over an entire length of the semiconductor substrate functioning as a top layer of a drift region and a second electrode disposed on a bottom surface of the semiconductor surface;
and
rows of multiple horizontal slices of continuous thin layers of alternating P-type and N-type doped layers disposed immediately below the uniformly doped region of the epitaxial layer extending continuously and horizontally over substantially an entire horizontal length of the semiconductor substrate across the drift region of the semiconductor substrate where each of the continuous thin layers having a doping and a layer thickness to enable a charge balance and a punch through in said alternating doped layers during a conduction mode in conducting a current in a vertical direction between the first electrode and the second electrode perpendicular to and cross over said horizontal slices of said P-doped and N-doped layers.

A vertical semiconductor power device formed in a semiconductor substrate comprising:

a first electrode disposed on a top surface and a plurality of dopant regions near the top surface in an epitaxial layer wherein a bottom portion of the epitaxial layer below the dopant regions constituting a uniformly doped region extending continuously and horizontally over an entire length of the semiconductor substrate functioning as a top layer of a drift region and a second electrode disposed on a bottom surface of the semiconductor surface;
and
rows of multiple horizontal slices of continuous thin layers of alternating P-type and N-type doped layers disposed immediately below the uniformly doped region of the epitaxial layer extending continuously and horizontally under an insulated gate over substantially an entire horizontal length of the semiconductor substrate across the drift region of the semiconductor substrate where each of the continuous thin layers having a doping and a layer thickness to enable a charge balance and a punch through in said alternating doped layers during a conduction mode in conducting a current in a vertical direction between the first electrode and the second electrode perpendicular to and cross over said horizontal slices of said P-doped and N-doped layers.

Dependencies are inferred from the claim text.

Sawtooth electric field drift region structure for power semiconductor devices

Life of this patent

Sawtooth electric field drift region structure for power semiconductor devices

Life of this patent

Abstract

Claims20