Method and circuit element for the selective charging of a semiconductor diffusion region

Claim 2

A chargeable circuit element comprising: a substrate of a first type of semi-conductive material; a chargeable diffusion region of opposite type of semiconductive material formed at a surface of the substrate; an output terminal connected to the diffusion region for coupling an output signal from the circuit element to an external circuit; a substrate terminal for establishing an electrical connection with the substrate remote from the diffusion region; a layer of insulating material on the surface of the substrate; a layer of metallization on the insulation layer and defining at the surface of the substrate a gate region which extends across the substrate to a location adjacent the diffusion region and serves to supply charge to the chargeable diffusion region through the selective formation of an inversion region substantially coterminous with the metallization layer in response to the application of a potential of one sign to the metallization layer; and, means for applying electrical pulses to the layer of metallization defining the gate region; the metallization layer defining the gate region comprising a portion of relatively large surface area spaced from the diffusion region and a relatively strip-like portion extending across the substrate from the portion of relatively large surface area to a location adjacent the diffusion region, the diffusion region thereby being operable to acquire a charge of the one sign during fluctuations in gate metallization potential toward the one sign and to lose a smaller amount of charge during fluctuations in gate metallization potential toward the other sign, the diffusion region thereby being operable to acquire a net amount of charge of the one sign.

Claim 3

A circuit element according to claim 1 wherein the substrate is of N-type silicon and the diffusion region is of P-type silicon.

Claim 4

A circuit element according to claim 1 wherein the insulating material extends over the entire surface of the substrate and diffusion region except in contact regions thereof.

Claim 5

A circuit element according to claim 3 wherein the insulating material beneath the metallisation layer is of less thickness than surrounding insulating material.

Claim 6

A circuit element according to claim 3 wherein the insulating material beneath the metallisation layer differs in composition from the surrounding insulating material.

Claim 7

A circuit element according to claim 1 wherein a plurality of diffusion regions are provided in the substrate and a single layer of metallization extends across the substrate to a location adjacent each diffusion region.

Claim 8

A circuit element according to claim 1 wherein the metallization layer defining the gate region comprises a portion of relatively large surface area spaced from the diffusion region and a relatively strip like portion extending across the substrate from the portion of relatively large surface area to a location adjacent the diffusion region.

Claim 9

An arrangement including a circuit element according to claim 1 including capacitive coupling means operatively connected to the diffusion region for providing an output signal related to the charge acquired by the diffusion region.

Claim 10

An arrangement aCcording to claim 8 wherein the capacitive coupling means comprises a second metallised region in contact with the diffusion region and connected to the gate terminal of a metal oxide silicon transistor.

Claim 11

An integrated circuit including an arrangement according to claim 9.

Claim 12

An electrical circuit comprising: a circuit element including: a substrate of a first type of semi-conductive material; a chargeable diffusion region of opposite type of semi-conductive material formed at a surface of the substrate; a substrate terminal remote from the diffusion region; a layer of insulating material on the surface of the substrate; a layer of metallization on the insulating layer and comprising a portion of relatively large surface area spaced from the diffusion region and a relatively narrow strip-like portion extending across the substrate from the portion of relatively large surface area to a location adjacent the diffusion region, the metallization layer defining at the surface of the substrate a gate region which extends across the substrate to a location adjacent the diffusion region and serves to supply charge to the diffusion region through the selective formation of an inversion layer substantially coterminous with the metallization layer; means for biasing the substrate terminal of the circuit element; means for applying electrical pulses to the layer of metallization defining the gate region; the pulses being of an appropriate sign and a magnitude greater than a threshold voltage at which the inversion layer is formed in the gate region whereby the chargeable diffusion region acquires charge of one sign during fluctuations in gate metallization potential toward the one sign and loses a smaller amount of such charge during the fluctuations in gate metallization potential toward the opposite sign, the diffusion region thereby acquiring a net amount of charge of the one sign; and, means for coupling an output signal from the chargeable diffusion region, the output signal being related to the net amount of charge of the one sign.

Claim 13

An electrical circuit comprising: a circuit element including: a substrate of a first type of semi-conductive material; a chargeable diffusion region of opposite type of semi-conductive material formed at a surface of the substrate; a substrate terminal remote from the diffusion region; a layer of insulating material on the surface of the substrate; a layer of metallization on the insulating layer and comprising a portion of relatively large surface area spaced from the diffusion region and a relatively narrow strip-like portion extending across the substrate from the portion of relatively large surface area to a location adjacent the diffusion region, the metallization layer defining at the surface of the substrate a gate region which extends across the substrate to a location adjacent the diffusion region and serves to supply charge to the diffusion region through the selective formation of an inversion layer substantially coterminous with the metallization layer; means for biasing the substrate terminal of the circuit element; means for applying electrical pulses to the layer of metallization defining the gate region; the pulses being of an appropriate sign and a magnitude greater than a threshold voltage at which the inversion layer is formed in the gate region whereby the chargeable diffusion region acquires charge of one sign during fluctuations in gate metallization potential toward the one sign and loses a smaller amount of such charge during the fluctuations in gate metallization potential toward the opposite sign, the diffusion region thereby acquiring a net amount of charge of the one sign; and, means for coupling an output signal from the chargeable diffusion region, the output signal being related to the net amount of charge of the one sign.

Claim 14

A radiation detector comprising: a circuit element including: a substrate of a first type of semi-conductive material; a first chargeable diffusion region of semi-conductive material of opposite type relative to the material of the substrate, said first chargeable diffusion region being formed at a surface of the substrate to permit exposure thereof to radiation to be detected; a second chargeable diffusion region of semi-conductive material of opposite type relative to the material of the substrate, formed at a surface of the substrate to permit exposure thereof to the radiation to be detected; a substrate terminal for establishing an electrical connection with the substrate remote from the diffusion regions; a layer of insulating material on the surface of the substrate; a first layer of metallization on the insulating layer and defining at the surface of the substrate a gate region which extends across the substrate to a location adjacent each diffusion region and serves to supply charge to the diffusion regions, said first layer of metallization comprising a portion of relatively large surface area spaced from each diffusion region and relatively narrow strip-like portions extending across the substrate from said portion of relatively large surface area to locations adjacent each diffusion region; and a second metallization region electrically connected to the second diffusion region to form a terminal for the second diffusion region; means for applying electrical pulses between the first layer of metallization defining the gate region and the substrate terminal, the electrical pulses being of appropriate sign and of a magnitude greater than a threshold voltage at which an inversion layer substantially coterminous with the first layer of metallization is formed in the gate region, whereby the diffusion regions will acquire charge of one sign during Fluctuation in gate metallization potential toward the one sign and lose a smaller amount of such charge during fluctuations in the gate metallization potential toward the opposite sign, the diffusion regions thereby acquiring a net amount of charge; and an amplifier of substantially infinite input impedance to direct current electrically connected to the terminal formed by the second metallization region, the amplifier providing an output signal related to the level of radiation to which the first diffusion region is exposed.

Claim 15

A radiation detector comprising: a circuit element including: a substrate of a first type of semi-conductive material; a first chargeable diffusion region of semi-conductive material of opposite type relative to the material of the substrate, said first chargeable diffusion region being formed at a surface of the substrate to permit exposure thereof to radiation to be detected; a second chargeable diffusion region of semi-conductive material of opposite type relative to the material of the substrate, formed at a surface of the substrate to permit exposure thereof to the radiation to be detected; a substrate terminal for establishing an electrical connection with the substrate remote from the diffusion regions; a layer of insulating material on the surface of the substrate; a first layer of metallization on the insulating layer and defining at the surface of the substrate a gate region which extends across the substrate to a location adjacent each diffusion region and serves to supply charge to the diffusion regions, said first layer of metallization comprising a portion of relatively large surface area spaced from each diffusion region and relatively narrow strip-like portions extending across the substrate from said portion of relatively large surface area to locations adjacent each diffusion region; and a second metallization region electrically connected to the second diffusion region to form a terminal for the second diffusion region; means for applying electrical pulses between the first layer of metallization defining the gate region and the substrate terminal, the electrical pulses being of appropriate sign and of a magnitude greater than a threshold voltage at which an inversion layer substantially coterminous with the first layer of metallization is formed in the gate region, whereby the diffusion regions will acquire charge of one sign during Fluctuation in gate metallization potential toward the one sign and lose a smaller amount of such charge during fluctuations in the gate metallization potential toward the opposite sign, the diffusion regions thereby acquiring a net amount of charge; and an amplifier of substantially infinite input impedance to direct current electrically connected to the terminal formed by the second metallization region, the amplifier providing an output signal related to the level of radiation to which the first diffusion region is exposed.

Claim 16

A radiation detector according to claim 12 wherein the first diffusion region is of larger surface area than the second diffusion region.

Claim 19

A method according to claim 14 wherein the net amount of charge acquired is related to the amount of leakage current from the diffusion region during the period between pulses and including the further steps of: exposing the circuit element to a condition to be monitored, the condition affecting the amount of leakage current; and monitoring the net amount of charge of the one sign acquired by the diffusion region to provide an indication related to the condition

Claim 20

The method of claim 15 wherein the circuit element is exposed to temperature variations and the condition indicated is temperature.

Claim 21

The method of claim 16 wherein the circuit element is exposed to radiation and the condition indicated is the level of radiation.