Annealing Effects on Electrical and Mechanical Properties of Integrated Passive Device-Resistor
Uma Iyerc and R. Chandramani
This paper presents the characterization of the integrated passive components (resistor) into a thin film multi layer system or integrated passive device (IPD). To realise integrated resistor for adjusting the sheet resistance, good pattern properties as well as low temperature coefficient, two metal layers are required. Hence, Ni-Cr and Pt are chosen in the present study. Al-Cu/Ni-Cr/Pt is deposited on Al2O3 and Si substrate using High Rate Magnetron (HRM) sputtering. To find the suitability of substrates, the electrical and mechanical characterizations for pure and thermally annealed (in argon atmosphere) samples have been studied. Micro hardness studies of films on Oxide substrate show regular square indentation up to 500 gms. There is no deformation, no diffusion for both the pure and the annealed samples. But multi layer on Si substrate has answered for noticeable inter diffusion above 475oC annealing as well as variation in H factor after 200 gm. At 500 gm load, the thin film started peeling off. The pure and the annealed samples on oxide substrate have shown very less variation of resistivity ρ, with temperature in the range RT to 200oC. But variation of ρ on Si substrate was faster and more for different annealed temperatures. This is due to the mobility variation, development of voids (as confirmed by SEM) and/or inter diffusion of Si with the other metals. The investigations confirm that resistive layers on Oxide substrate are more stable with less loss.
Keywords: Multi layers; Micro hardness; Resistivity.