The Fabrication and Characterization of Terbium Nitride Metal Gate with Hafnium Oxide High-k Material MOS Field-effect Transistors

• Main Authors: Ching-Cheng Cheng, 鄭慶誠
• Other Authors: Shui-Jinn Wang
• Format: Others
• Language: zh-TW
• Published: 2006
• Online Access: http://ndltd.ncl.edu.tw/handle/14410401633402005239

碩士 === 國立成功大學 === 微電子工程研究所碩博士班 === 94 === The continuous CMOS scaling has resulted in a continuous improving of the speed, power consumption, packing density and performance of integrated circuits. However, shrinkage in gate oxide thickness in tackling short channel effects has now been limited by gate leakage currents. In addition, the poly-Si gate which suffers from depletion effect has become intolerable in deep submicron technology. High-κ materials and metal gate are then urgently required in future CMOS technology. In this thesis, terbium nitride (TbN) and hafnium oxide (HfO2) were proposed to serve as gate metal and gate insulator for future CMOS technology, respectively. Both these two films were sputtering deposited and thermally annealed. The physical properties and compositions of TbN film were analyzed using XRD, ESCA, and AES. It is found that the composition of TbN films was very difficult modified by the combination of the sputtering gas, which is solely determined by the target material. Experimental results shows that TbN films with relatively stronger binding energy could be obtained from a RF sputtering with a power of 160 W and the main phase of the film is (111). MOS capacitances with TbN/HfO2/p-Si structure and n-FETs based on the same MOS structure were fabricated and characterized. C-V and leakage current for the MOS capacitances as well as IDS-VDS and IDS-VGS characteristics of MOSFETs were measured and analyzed. According to C-V curves and TEM images, the HfO2 high-k films prepared in this work were with a k-value of 25 and a minimum EOT around 1.7 nm has been realized. Typical values of Ion/Ioff ratio, threshold voltage, and subthreshold swing (SS) obtained form the fabricated MOSFETs with TbN(40 nm)/HfO2(10.6 nm)/p-Si (3 1015 cm-3) MOS structure were 105, -0.1 V, and 192.04 mV/decade, respectively. Though further investigations are still required, our preliminary experimental results suggest that the sputtering deposited TbN and HfO2 films might work well for future MOSFETs.