ION-PLATED DISCONTINUOUS THIN-FILM STRAIN-GAUGES

The major advantage of tunnelling thin film strain gauges over continu ous thin films is high sensitivity. The main problem lies in instabili ty with time, presumably due to island coalescence. In this study, the films were stabilized by the use of ion-plating deposition, which con tributes to immobilize the grains. Discontinuous gold thin film strain gauges were prepared by deposition on Kapton substrates, which are re sistant to plasma heating. Gauge factors measurement and resistance ob servations on hysteresis and stability were made for film sheet resist ance in the range 10(2)-10(7) Omega/sq. For a representative 7 nm thic k strain gauge, a gauge factor of 38 was measured. Individual grains o f 25-nm diameter with 6-nm separation distance were observed. The redu ction of aging effects attainable by ion-plating deposition render dis continuous thin films applicable for high sensitivity strain gauges. ( C) 1998 Elsevier Science S.A.