WSIX THIN-FILMS FOR RESISTORS

We have fabricated and characterized thin films of WSiX in order to pr oduce highly resistive films (about 1 k Ohm/sq), with temperature coef ficients of resistivity (TCR) less than 0.2%/K, by a technique which, in our experience, is more reproducible, and has better uniformity tha n comparable techniques involving cermets. Although there are a variet y of materials that are capable of producing highly resistive films, t hese tend to involve very thin films (in the case of metals), reproduc ibility and uniformity problems (in the case of cermets), or have larg e TCRs (in the case of semiconductors). We applied a variety of physic al vapour deposition techniques for the sputter deposition of films ra nging in composition from pure silicon to pure tungsten. In doing so, we have identified a range of compositions and thicknesses in which th e TCR and resistivity are independent of thickness, suggesting that th ese films do not suffer from any significant changes in microstructure at any critical thickness in the range of 70 to 2000 nm. These result s were also independent of the type of sputter deposition used. These factors suggest that such films will be useful in the manufacture of s table resistors on the order of 1 k Ohm or more. (C) 1997 Elsevier Sci ence S.A.