A High-Stability RC Circuit Using High Nitrogen Doped Tantalum

A fabrication process and reliability studies for RC hybrid integrated circuits utilizing alpha tantalum capacitors and tantalum nitride resistors are described. The alpha tantalum used in this study was reactively sputtered tantalum film containing from 10-20 atomic percent nitrogen and has a body centered cubic structure. The ac and dc characteristics of the alpha tantalum capacitors are in agreement with those shown by Anders and Rottersman [5], [6]. The longterm thermal stability of these capacitors is shown to be at least three times better than for beta tantalum capacitors. Accelerated life tests at various voltages show the alpha tantalum RC circuits to be at least equivalent in reliability to those using standard beta tantalum capacitors. The RC product shows excellent temperature compensation and stability during accelerated parametric aging tests which were done on production RC filter circuits.