Process temperature dependent high frequency capacitance-voltage response of ZrO2/GeO2/germanium capacitors

ZrO2/GeO2 dielectrics are grown on germanium substrates by Atomic Layer Deposition (ALD) at substrate temperatures of 150, 200, and 250 degrees C, respectively. The impact of the deposition temperature on the electrical and structural properties of MOS capacitors is investigated. A significant influence of the ALD temperature on the high frequency capacitance in inversion can be observed, resulting in a shift of the minority carrier response time from 1.15 to 0.2 mu s. Time-of-flight secondary ion mass spectroscopy investigations indicate a distinctive depletion of interfacial GeO at higher ALD temperatures, which give rise to trap levels near the oxide/Ge interface.