Stresses in the InP/Ti/Pt and InP/SiO2/Ti/Pt multilayer systems

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Abstract
The contact metallization of 1000 Å Ti followed by 1500 Å Pt deposited by rf diode sputtering onto InP is found to be of very low stress, as has previously been reported for this metallization on GaAs. This is due to the effect of compressive stress in the Ti film being compensated by tensile stress in the Pt film. However, when Ti is deposited onto SiO2 coated InP, its stress changes sign, becoming highly tensile, of magnitude ∼1×1010 dyne cm−2. Thus its effect becomes additive to that of the Pt film, producing an effective stress in the Ti/Pt bilayer of ∼7×109 dyne cm−2 tensile. Due to moderately low compressive stress in the SiO2, the effective resultant stress for the multilayer of (3000 Å SiO2/Å Ti/1500 Å Pt) on InP(100) remains tensile, of magnitude 1.7×109 dyne cm−2. The origin of the stress reversal in the Ti film appears to be its mode of nucleation and growth, as opposed to the formation of a highly stressed interfacial compound layer.