Semiconductor device with isolated circuit elements

Claim 2

A semiconductor device comprising: a. a substrate of low resistivity semiconductive material of a given conductivity type, and an electrical connection to said substrate; b. an epitaxial layer of high resistivity semiconductive material disposed on said substrate and having said given conductivity type; c. semiconductor circuit elements formed in a surface portion of said epitaxial layer, at least one of said semiconductor circuit elements comprising at least two semiconductor zones defining an active part of said one semiconductor circuit element; and d. an electrically isolating zone substantially completely enclosing said one semiconductor circuit element except for a restricted opening positioned laterally with respect to said active part thereof, said electrically isolating zone being cup-shaped and having a bottom portion which extends at the boundary of the epitaxial layer and the substrate and a wall portion which extends from the bottom portion through the epitaxial layer up to the surface thereof, the bottom portion comprisIng a semiconductor layer of a second opposite conductivity type and having a higher impurity concentration than an adjoining part of the substrate, said electrically isolating zone separating said enclosed semiconductor circuit element from other semiconductor circuit elements, the shape of said isolating zone at least partially defining a lateral resistor located in said epitaxial layer and extending through said opening, said lateral resistor providing an electrically resistive path between said enclosed semiconductor circuit element and said substrate.

Claim 3

A semiconductor device as defined in claim 1, wherein at least a portion of said wall portion consists of an electrically insulating material.

Claim 4

A semiconductor device comprising: a. a substrate of low resistivity semiconductive material of a given conductivity type, and electrical connection means connected to said substrate; b. a first layer of high resistivity semiconductive material on said substrate and of said given conductivity type; c. semiconductor circuit elements formed in a surface portion of said first layer, at least one of said semiconductor circuit elements comprising at least two semiconductor zones defining an active part of said one semiconductor circuit element; and d. an electrically isolating zone substantially completely enclosing said one semiconductor circuit element except for a restricted opening positioned laterally with respect to said active part thereof, said electrically isolating zone being cup-shaped and having both a bottom portion which extends at the boundary of the first layer and the substrate and a wall portion which extends from the bottom portion through the first layer up to the surface thereof, the bottom portion comprising a semiconductor layer of a second opposite conductivity type and having a higher impurity concentration than an adjoining part of the substrate, the wall portion consisting at least partly of an electrically insulating material, said electrically isolating zone separating said enclosed semiconductor circuit element from other semiconductor circuit elements, the shape of said isolating zone at least partially defining a lateral resistor located in said first layer and extending through said opening, said lateral resistor providing an electrically resistive path between said enclosed semiconductor circuit element and said substrate.

Claim 5

A semiconductor device comprising: a. a substrate of low resistivity semiconductive material of a given conductivity type, and electrical connection means connected to said substrate; b. a first layer of high resistivity semiconductive material on said substrate and of said given conductivity type; c. semiconductor circuit elements formed in a surface portion of said first layer, at least one of said semiconductor circuit elements comprising at least two semiconductor zones defining an active part of said one semiconductor circuit element; and d. an electrically isolating zone substantially completely enclosing said one semiconductor circuit element except for a restricted opening positioned laterally with respect to said active part thereof, said electrically isolating zone being cup-shaped and having both a bottom portion which extends at the boundary of the first layer and the substrate and a wall portion which extends from the bottom portion through the first layer up to the surface thereof, the bottom portion comprising a semiconductor layer of a second opposite conductivity type and having a higher impurity concentration than an adjoining part of the substrate, the wall portion consisting at least partly of an electrically insulating material, said electrically isolating zone separating said enclosed semiconductor circuit element from other semiconductor circuit elements, the shape of said isolating zone at least partially defining a lateral resistor located in said first layer and extending through said opening, said lateral resistor providing an electrically resistive path between said enclosed semiconductor circuit element and said substrate.

Claim 6

A semiconductor device as claimed in claim 3, comprising a further circuit element formed in a second surface portion of said first layer outside said isolation zone and spaced from said one circuit element, and wherein said substrate serves as a common low ohmic connection for said further circuit element.

Claim 7

A semiconductor device as claimed in claim 3, comprising a further surface zone formed in a second surface portion of said first layer at a portion thereof in the vicinity of said opening, said further surface zone extending partially through said first layer thereby to constrict the thickness of said first layer and increase the resistance value of the electrical path between said first one circuit element and said electrical connection means.

Claim 8

A semiconductor device as claimed in claim 3, comprising a further surface zone formed in a second surface portion of said first layer at a portion thereof in the vicinity of said opening, and means for applying an electrical potential to said further surface zone thereby to constrict current flow in the portion of said first layer adjacent to said further surface zone and increase the effective resistance value of the electrical path between said one circuit element and said electrical connection means.

Claim 9

A semiconductor device as claimed in claim 3, wherein the first layer comprises a region of low resistivity material interposed between one of said at least two semiconductor zones and said electrically isolating zone in the region of said one semiconductor circuit element.

Claim 10

A semiconductor device as defined in claim 3, wherein said openinG is located in said wall portion.

Claim 11

A semiconductor device as defined in claim 3, wherein one of said semiconductor zones is conductively connected to said substrate via said resistor and the other of said zones is of opposite conductivity and coheres at the surface with said cup-shaped isolating zone.

Claim 12

A semiconductor device as defined in claim 3, characterized in that said further circuit element is a transverse bipolar transistor, said transistor including a collector zone comprising a part of said first layer and a base zone having a conductivity type opposite to that of said first layer, said base zone adjoining the surface and surrounding at least an emitter zone in the semiconductor body, and said substrate providing a collector connection to said transistor.

Claim 13

A semiconductor device as defined in claim 3, wherein said one semiconductor circuit element comprises a transverse bipolar transistor comprising a first zone formed by part of said first layer, a second zone of said second opposite conductivity type, said second zone being located within said first zone and forming a base region of said transistor, and a further zone of said given conductivity type located within said second zone.