Permanent And Transient Radiation Effects On Thin Oxide 200 A Mos Transistors

An approach for hardening metal oxide semiconductor (MOS) transistors to ionizing radiation by reducing the thickness of the gate oxide is presented. It is shown that Si gate, n-channel MOS field-effect transistors with oxides 200 A thick continue to operate in the enhancement mode after irradiation to 1,000,000 rads (Si) with a positive bias applied to the gate during the irradiation. This represents a considerable improvement over conventional thick-oxide (approximately 1000-A) devices, which go into the depletion mode of operation at 100,000 rads (Si). The thin-oxide devices after exposure to pulsed ionizing radiation showed improved performance over that of thick-oxide devices. It was found also that device operation following irradiation depended on the source-drain spacing (Channel length): Shortening the channel length leads to an increased shift of the threshold voltage induced by irradiation. (Author).