Frequency dependent dielectric properties and electrical conductivity of platinum silicide/Si contact structures with diffusion barrier

摘要

Unlike a conventional metal-Si compounds/Si structure, a thin film TiW alloy was deposited on PtSi/n-Si to form a diffusion barrier between aluminum (Al) and PtSi/n-Si. Dielectric properties and electrical conductivity of contact structures have been investigated in detail by using experimental C-Vand G-V measurements in the frequency range of 3 kHz-5 MHz and voltage range of -2-4 V. Experimental results indicate that the values of ε' show a steep decrease with increasing frequency for each voltage. On the other hand, the values of ε" versus voltage curves show a jump, and ε" decreases with decreasing voltage and increasing frequency.The weak increasing of the ac electrical conductivity (σ_(ac)) on frequency is observed. The real part of electric modulus (M') increases with increasing frequency. Also, the imaginary part of electric modulus (M") shows a peak and the peak position shifts to higher frequency with increasing applied voltage. The energy loss tan δ versus frequency has a weak wide peak at 300 kHz for each voltage. It can be concluded that the interfacial polarization can be more easily occurred at low frequencies, and the majority of interface states at metal semiconductor interface, contributes to deviation of dielectric properties of Al-TiW-PtSi/n-Si structures.