A thin film TaN resistor reliability evaluation

A reliability evaluation for TaN thin film resistors based on accelerated life test experiments is presented. The resistors degrade by a gradual resistance increase and the functional dependence on time and temperature has been established. Normalized resistance increases with a ln(t) time dependence, with an activation energy of 1.55 eV. Current was shown not to be an independent acceleration factor, aside from its effect on Joule heating. Assuming a 1% failure criterion, a characteristic life of 9 × 10
⁶
h has been established for T
_j
= 125°C. The local encapsulation environment is believed to play a role in resistor degradation. The data are consistent with a model based on gradual conversion to non-conducting of a portion of the TaN film, suggested to be oxidation originating from residual water in the benzocyclobutene encapsulating film.