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US 4,788,581 AGranted
MOS dosimeter
AssigneeHahn-Meitner-Institut Berlin GmbH
InventorsMeinhard Knoll, Dietrich Braunig
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AssigneeHahn-Meitner-Institut Berlin GmbH
InventorsMeinhard Knoll, Dietrich Braunig
Estimating the term…
In known MOS dosimeters for measuring an energy dosage within radiation fields, which comprise a semiconductor substrate with an insulator layer and a metal contact or poly-si-contact, a measurement is taken and irreversible damage is done to the insulator layer. Prior art dosimeters of this kind cannot be electrically reset, nor can such MOS structures be directly integrated with evaluating electronics. The present invention avoids these drawbacks by providing a hard-radiation resistant insulator layer with a floating gate X. Such a resistant insulator layer is produced in a "hardened" process by thermal dry oxidation of silicon at low temperatures of about 850.degree. to 950.degree. C. The inventive dosimeter makes it possible to integrate, on the floating gate, both negative and positive charges. This permits an integration of MOS sensors and signal processing electronic elements on a single chip. By providing a concentrator, the sensitivity of the inventive MOS dosimeter can be augmented by several orders of magnitude, as compared to conventional devices.
An electrically resettable MOS dosimeter for non-destructively measuring energy doses of a radiation field in dependance upon corresponding measurable changes in electric charges relative to an initial value and which dosimeter is electrically resettable to such initial value for taking a new such measurement, which comprises a semiconductor substrate having source and drain electrodes, an insulator layer applied to said semiconductor substrate with said source and drain electrodes adjacent thereto, said insulator layer being composed of radiation resistant material which is capable of capturing radiation and which has been radiation hardened sufficiently to render said insulator layer hardened to radiation and resistant to damage by such radiation yet which is capable of capturing such radiation, an electrode gate contact connected to said insulator layer, a floating gate embedded in said insulator layer, and means for applying a voltage to said electrode gate contact such that when said insulator layer is exposed to a radiation field, and a voltage is applied to said electrode gate contact, charges are generated by said insulator layer and are collected by said floating gate in dependence upon the radiation dosage, which charges are electrically resettable to such initial value for taking a new such measurement.
MOS dosimeter for non-destructively measuring energy doses of a radiation field, comprising a semiconductor substrate having source and drain electrodes, an insulator layer applied to said semiconductor substrate with said source and drain electrodes adjacent thereto, said insulator layer being composed of radiation resistant silicon dioxide, said insulator layer constituting a radiation hardened layer which has been produced by oxidizing silicon in a thermal, dry hardening process at low temperatures of 850.degree. to 950.degree. C. sufficiently to render said insulator layer hardened to radiation and resistant to damage by such radiation, a metal contact connected to said insulator layer, a floating gate embedded in said insulator layer, and means for applying a voltage to said metal contact such that when said insulator layer is exposed to a radiation field and a voltage is applied to said metal contact, charges are generated by said insulator layer and are collected by said floating gate.
Dependencies are inferred from the claim text.