Analysis of Abnormal Upturns in Capacitance-Voltage Characteristics for MOS Devices With High-k Dielectrics

作者：Sohn Chang Woo^*; Sagong Hyun Chul; Jeong Eui Young; Choi Do Young; Park Min Sang; Lee Jeong Soo; Kang Chang Yong; Jammy Raj; Jeong Yoon Ha

来源：IEEE Electron Device Letters, 2011, 32(4): 434-436.

DOI：10.1109/LED.2011.2108257

• Capacitance measurement
• dynamic response
• equivalent circuits
• hafnium oxide
• high-k dielectrics
• radio-frequency measurement
• shallow trap level
• upturns

In this letter, we analyze the nonsaturating upturns of capacitance under strong accumulation bias in MOS capacitors with high-k dielectrics. By comparing the electrical properties of dielectric samples with and without HfO(2) and by varying the ambient temperature, it is found that the conduction through the shallow trap levels in the HfO(2) bulk produces not only a steady-state current but also a dynamic current, which, in turn, causes the upturn in capacitance. The addition of RC shunts to the conventional small-signal model is proposed to consider the dynamic leakage effect. The model's effectiveness is verified by fitting the measured impedance spectrum and the measured capacitance. We suggest that measuring at a high frequency of hundreds of megahertz eliminates the dynamic interaction by shallow trap levels, allowing gate capacitance to be successfully reconstructed.

• 出版日期2011-4