US 4,936,928 A · Semiconductor device

Abstract

A semiconductor structure is provided comprising a bulk substrate of semiconductor material having a first-type doping conductivity in a first dopant concentration. A first layer of semiconductor material is epitaxially formed on the substrate, such first layer having the first-type doping conductivity in a second dopant concentration lower than the first concentration. A second layer of semiconductor material is epitaxially formed on the first layer, the second layer having a second-type doping conductivity opposite to the first-type doping conductvity and thereby forming a P-N junction with the first layer. A plurality of regions, comprising semiconductor material having the first-type doping conductivity and extending through the second layer and a predetermined distance into the first layer, are further included for providing electrical isolation between active devices formed in different regions of the second layer. The thickness of the first layer is selected to be greater than the diffusion lengths of electron-hole pairs emitted by the bulk substrate in response to incident radiation and smaller than the thickness of the bulk substrate. With such arrangement, electron-hole pairs emitted by the substrate are substantially prevented from reaching such P-N junction, and few electron-hole pairs are emitted by the first layer, due to the small thickness thereof. Thus, electron-hole current at such P-N junction is reduced, thereby decreasing the effects of incident radiation on active devices formed in the semiconductor structure.

Claims19

Dependent claims

A semiconductor structure comprising:

(a) a substrate comprising semiconductor material having a first-type doping conductivity and a first predetermined thickness;
(b) a first layer of semiconductor material disposed on the substrate, said first layer having the first-type doping conductivity and a dopant concentration lower than a dopant concentration in the substrate, said first layer having a second predetermined thickness substantially less than the first predetermined thickness of the substrate;
(c) a second layer of semiconductor disposed on the first layer of semiconductor material, said second layer having a second-type doping conductivity opposite to the first-type doping conductivity;
and
(d) a digital circuit formed in the second layer using bipolar junction technology.

2 more elements

A semiconductor structure comprising;

(a) a substrate comprising semiconductor material having a first-type doping conductivity in a first dopant concentration, said substrate having a predetermined thickness;
(b) a first layer of semiconductor material epitaxially formed on the substrate, said first layer having the first-type doping conductivity in a second dopant concentration lower than the first dopant concentration, said first layer having a thickness substantially less than the predetermined thickness of the substrate;
(c) a second layer of semiconductor material epitaxially formed on the first layer, said second layer having a second-type doping conductivity opposite to the first-type doping conductivity and forming a p-n junction with the first layer;
and
(d) means, formed in the second layer, for providing electrical isolation between active devices formed in different regions of the second layer of semiconductor material, each one of the active devices comprising:
a first semiconductor region having a first conductivity type;
a second semiconductor region, having the first conductivity type;
and a third semiconductor region, disposed between the first and second semiconductor regions, having a conductivity type opposite the first conductivity type, and each one of active devices operating without current flow across the p-n junction.

5 more elements

Dependencies are inferred from the claim text.

Semiconductor device

Life of this patent

Semiconductor device

Life of this patent

Abstract

Claims19