Radiation-hardened silicon-on-insulator junction field-effect transistors fabricated by a self-aligned process

A self-aligned process has been developed for fabricating JFET´s in zone-melting-recrystallized (ZMR) Si films on SiO2-coated Si substrates. This process has been used to fabricate n-JFET´s exhibiting transconductance values up to 63 mS/mm. For 228 devices within an area of about 4 × 4 cm², the mean threshold voltage is 578 mV and the standard deviation is 22 mV. With a -15-V bias applied to the Si substrate during irradiation and device operation, the devices show low threshold voltage shift (< -75 mV) and small transconductance degradation (∼30 percent) for exposure to total-dose radiation of 10⁸rad(Si).