Herman Sol Hoffman

Cermet Resistors on Ceramic Substrates

Cermet (CrSiO) has been used extensively for chip resistors. The application for CrSiO on CrCuCr metallized ceramic substrates is described. The process was designed for potential high volume production needs. Basic operations are described, including radio frequency (RF) magnetron sputtering, photoprocessing, plasma etching, and trimming. Resistor design features have more flexibility over thick film resistors. A much wider aspect ratio is achieved by the improved line resolution. Low resistor values employ a comb design; high resistor values employ convention serpentine designs. Consistent with the IBM data base for silicon substrates, film resistivity, and thermal coefficient of resistance (TCR) are controlled by CrSiO composition and subsequent thermal treatments of the film. Thermal stabilization is significantly improved by film annealing.