Structure and formation of semiconductors with transverse conductivity gradients

Claim 2

A semiconductor unit comprising: a mass of semiconductor material of one conductivity type; a first region of semiconductor material of opposite conductivity type formed in said mass and providing a first junction therewith; and a second region of said one conductivity type formed within said first region in nesting relationship and providing a second junction therewith; said first and second junctions having substantially uniform spacing therebetween throughout said first region; said first region having a transverse conductivity gradient in a direction substantially parallel to said first and second junctions, said gradient extending between a central portion of relatively lower conductivity and a peripheral portion of relatively higher conductivity.

Claim 3

The semiconductor unit of claim 1 wherein the conductivity of said first region is imparted by ion-implanted atoms of a first type and further wherein said second region contains ion-implanted atoms of said first type to a concentration below the concentration in said first region.

Claim 4

The semiconductor unit of claim 1 wherein: said first and second junctions intersect a surface of said mass at peripheral portions of said first and second junctions; said second region comprises central and peripheral separately produced portions whereby said first and second junctions may be substantially matched; and said first and second junctions extend centrally from points of intersection of said surface in arcs directed away from said surface of said mass at the points of intersection with said surface and arcs directed back toward said surface of said mass nearer the central extent of said junctions.

Claim 5

The semiconductor unit of claim 1 wherein: said first region comprises partially diffused, implAnted ions imparting said opposite conductivity type; and said second region comprises diffused ions imparting said one conductivity type.

Claim 6

A semiconductor unit comprising: a mass of semiconductor material of one conductivity type; a first region of semiconductor material of opposite conductivity type formed in said mass and providing a first junction therewith; and a second region of said one conductivity type formed within said first region in nesting relationship and providing a second junction therewith; said first region having a transverse conductivity gradient in a direction substantially parallel to said first and second junctions, said gradient extending between a central portion of relatively lower conductivity and a peripheral portion of relatively higher conductivity; said first and second junctions being spaced at least substantially as far apart through said portion of lower conductivity as through said portion of higher conductivity.

Claim 7

A semiconductor unit comprising: a mass of semiconductor material of one conductivity type; a first region of semiconductor material of opposite conductivity type formed in said mass and providing a first junction therewith; and a second region of said one conductivity type formed within said first region in nesting relationship and providing a second junction therewith; said first region having a transverse conductivity gradient in a direction substantially parallel to said first and second junctions, said gradient extending between a central portion of relatively lower conductivity and a peripheral portion of relatively higher conductivity; said first and second junctions being spaced at least substantially as far apart through said portion of lower conductivity as through said portion of higher conductivity.

Claim 8

A semiconductor unit comprising: a mass of semiconductor material of one conductivity type; a first region of semiconductor material of opposite conductivity type formed in said mass to produce a first junction therewith; said first region having a gradient in the conductivity thereof existing in a direction parallel to said first junction from a central portion of said first region of relatively lower conductivity to a peripheral portion of said first region of relatively higher conductivity; a second region of said one conductivity type formed within said first region to provide a second junction therewith; said second junction extending adjacent said first region throughout the gradient portion of said first region and substantially coextensive with portions of both relatively higher and lower conductivity of said first region.

Claim 9

A semiconductor unit comprising: a mass of semiconductor material of one conductivity type; a first region of semiconductor material of opposite conductivity type formed in said mass to produce a first junction therewith; said first region having a gradient in the conductivity thereof existing in a direction parallel to said first junction from a central portion of said first region of relatively lower conductivity to a peripheral portion of said first region of relatively higher conductivity; a second region of said one conductivity type formed within said first region to provide a second junction therewith; said second junction extending adjacent said first region throughout the gradient portion of said first region and substantially coextensive with portions of both relatively higher and lower conductivity of said first region.

Claim 10

The semiconductor unit of claim 6 wherein said first and second junctions are substantially uniformly spaced.

Claim 11

A semiconductor unit comprising: a mass of semiconductor material of one conductivity type; a first region of semiconductor material of an opposite conductivity type formed within said mass and providing a first junction with said mass of semiconductor material; said first region having a plurality of portions of relatively different conductivities imparted by a plurality of different concentrations of dopant producing said opposite conductivity type; a second region of said one conductivity type formed within said first region and providing a second junction with said first region; said second junction extending in adjacent relationship to said plurality of portions of different conductivity type of said first region; said second junction being operative in response to potentials applied to said first and second regions and said mass of semiconductor material to conduct current of relatively low levels across portions of said second junction adjacent to portions of said first region of relatively lower conductivity and to conduct currents of relatively higher levels across said second junction at points adjacent to portions of said first region of relatively higher conductivity as well as portions of relatively lower conductivity.

Claim 12

A semiconductor unit comprising: a mass of semiconductor material of one conductivity type; a first region of semiconductor material of an opposite conductivity type formed within said mass and providing a first junction with said mass of semiconductor material; said first region having a plurality of portions of relatively different conductivities imparted by a plurality of different concentrations of dopant producing said opposite conductivity type; a second region of said one conductivity type formed within said first region and providing a second junction with said first region; said second junction extending in adjacent relationship to said plurality of portions of different conductivity type of said first region; said second junction being operative in response to potentials applied to said first and second regions and said mass of semiconductor material to conduct current of relatively low levels across portions of said second junction adjacent to portions of said first region of relatively lower conductivity and to conduct currents of relatively higher levels across said second junction at points adjacent to portions of said first region of relatively higher conductivity as well as portions of relatively lower conductivity.

Claim 13

A semiconductor unit comprising: a mass of semiconductor material of one conductivity type; a first region of semiconductor material of opposite conductivity type formed in said mass to provide a first junction with said mass; said first region having a first portion of predetermined significantly higher conductivity and having a concentration of dopant producing said predetermined higher conductivity of no greater than 1019 atoms per cubic centimeter; said first region having a second portion of a predetermined significantly lower concentration than said first portion; a second region of said one conductivity type formed within said first region to provide a second junction with said first region; said second Junction extending adjacent to said first region from said portion of no greater than 1019 atoms concentration to said portion of significantly lower concentration to produce areas of conduction across said second junction in response to potentials applied to said first and second regions and said mass which are substantially limited to the portion of said second junction adjacent to said portion of significantly lower impurity concentration for low current levels and which areas of junction conduction increase to encompass the portion of said second junction adjacent to the portion of higher impurity concentrations with increasing junction current.

Claim 14

A semiconductor unit comprising: a mass of semiconductor material of one conductivity type; a first region of semiconductor material of opposite conductivity type formed in said mass to provide a first junction with said mass; said first region having a first portion of predetermined significantly higher conductivity and having a concentration of dopant producing said predetermined higher conductivity of no greater than 1019 atoms per cubic centimeter; said first region having a second portion of a predetermined significantly lower concentration than said first portion; a second region of said one conductivity type formed within said first region to provide a second junction with said first region; said second Junction extending adjacent to said first region from said portion of no greater than 1019 atoms concentration to said portion of significantly lower concentration to produce areas of conduction across said second junction in response to potentials applied to said first and second regions and said mass which are substantially limited to the portion of said second junction adjacent to said portion of significantly lower impurity concentration for low current levels and which areas of junction conduction increase to encompass the portion of said second junction adjacent to the portion of higher impurity concentrations with increasing junction current.

Claim 15

The semiconductor unit of claim 9 wherein: said portion of relatively lower impurity concentration of said first region is centrally located within said first region; said portion of relatively higher impurity concentration of said first region is peripherally located around said portion of relatively lower impurity concentration; and said second junction extends from points adjacent said central portion of relatively lower impurity concentrations to points adjacent substantial parts of said peripheral portion of relatively higher impurity concentrations.

Claim 16

The semiconductor unit of claim 9 wherein: said first and second junctions bounding said first region are substantially uniformly spaced throughout the active current carrying portion of said second junction.