Study of the effect of thermal annealing on high k hafnium oxide thin film structure and electrical properties of MOS and MIM devices
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The effect of rapid thermal annealing on structural and electrical properties of high k HfO2 thin films is investigated. The films were initially deposited at pre-optimized sputtering voltage of 0.8 kV and substrate bias of 80 V in order to get optimized results for oxide charges and leakage current as a MOS device. The film properties were investigated for optimum annealing temperature in oxygen and optimum rapid thermal annealing temperature in nitrogen respectively to get the best electrical results as a MOS device structure. The film thickness, composition and microstructure is studied by Laser Ellipsometry, XRD and AFM and the effect of thermal annealing is shown. The electrical I–V and C–V characteristics of the annealed dielectric film were investigated employing Al-HfO2-Si MOS capacitor structure. The flat-band voltage (V fb) and oxide-charge density (Q ox) were extracted from the high-frequency C–V curve. Dielectric study were further carried out on HfO2 thin films having metal–insulator–metal (MIM) configuration over a wide temperature (300–500 K) and frequency (100 Hz to 1 MHz) range.
KeywordsHfO2 Rapid Thermal Annealing Substrate Bias Oxide Charge Hafnium Oxide
The authors would like to thank the Director CEERI Pilani for providing the facilities for the work. Mr. Vikram Singh and Mr. R. S. Shekhawat are thanked for the experimental support. The authors would like to thank Dr. Shomna Mahajan at SSPL, New Delhi for experiments on Rapid Thermal Annealing. Prof. V. Ramgopal Rao of Electrical Engineering Department, Indian Institute of Technology, Bombay, is specially thanked for useful suggestion and support for electrical characterization. The financial support was provided by CSIR under ES scheme and AICTE, New Delhi under RPS scheme which is thankfully acknowledged.
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