Effects of low-energy proton radiation damage on the TCR of reactively sputtered Ta thin-film resistors

Tantalum thin-film resistors reactively sputtered in oxygen and nitrogen simultaneously have been irradiated with 150-keV protons. The TCR (Temperature Coefficient of Resistance) of these discontinuous films, consisting of interconnected metallic islands largely surrounded by Ta 2 O 5 , may be considered to be compsed of two components: a negative component due to activated tunneling between islands, and a positive component due to metallic conduction. The observed negative increase in room temperature (30°C to 100°C) TCR with fluence is attributed to an increase in the proportion of the tunneling component relative to the metallic component as the result of an enhanced tunneling mechanism which is due to radiation-produced defects with in the inter-island oxide regions. Following irradiation at 30°K, the low temperature (−240°C to −229°C) TCR recovers rapidly with annealing temperature up to 150°K. Between 150°K and 300°K, relatively little TCR recovery occurs. The TCR recovery is attributed to the annihilation of radiation-produced defects within both island and gap regions of the films.