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In this investigation, the carrier concentration gradient between channel and contact region is achieved to improve the Thin film Transistors (TFT) performance by employing annealing at 350 °C in forming gas (N 2 + 5% H 2 ). The contact region is covered with Mo metal and the channel region is only exposed to forming gas to facilitate the diffusion controlled reaction. The TFT using a-IGZO active layer is fabricated in ambient of Ar:O 2 in ratio 60:40 and the conductivity of the order of 10 −3 S/cm is measured for as-deposited sample. The electrical conductivity of an annealed sample is of the order of 10 2 S/cm. The device performance is determined by measuring merit factors of TFT. The saturation mobility of magnitude 18.5 cm 2 V −1 s −1 has been determined for W/L (20/10) device at 15 V drain bias. The extrapolated field effect mobility for a device with channel width (W) 10 μm is 19.3 cm 2 V −1 s −1 . The on/off current ratio is 10 9 and threshold voltage is in the range between 2 and 3 V. The role of annealing on the electronic property of a-IGZO is carried out using X-ray photoelectron spectroscopy (XPS). The valance band cut-off has been approximately shifted to higher binding energy by 1 eV relative to as-deposited sample. [ABSTRACT FROM AUTHOR]

Abstract: Characteristics of tantalum silicon nitride (TaSiN) thin films have been investigated as an electrode material for Ge2Sb2Te5 chalcogenide phase change material. The films were deposited by co-sputtering system in which the ratio of tantalum nitride to silicon was controlled by the plasma power on each target. The TaSiN films showed tunable resistivity from 260 to 560 μΩ cm with increasing Si content. From the evaluation of PRAM cell structures consisting of the TaSiN and the Ge2Sb2Te5, we found that the SET voltages are nicely correlated with the resistivity of the TaSiN. Moreover, the sensing margin (resistance ratio: R SET/R RESET) turned out to be good for practical application. [Copyright &y& Elsevier]

Abstract: When hafnium oxide (HfO2) is directly deposited on Si by the RF sputtering method, Hf silicide is formed and post-deposition anneal (PDA) at 400°C transforms Hf silicide to Si suboxide plus Hf suboxide. The leakage current density for the 〈aluminum (Al)/HfO2/Si(100)〉 diodes without PDA is high due to the high density interface states near the Fermi level (0.86eV above the Si valence band maximum, VBM) and minute conduction channels. PDA at 400°C eliminates the interface states and the conduction channels, and improves the characteristics of the HfO2 layer, but interface states are newly formed at 0.53eV above the VBM, resulting in still high leakage current density. Silicon nitride (SiN) layers formed by Si nitridation using N2-plasma generated by the low energy electron impact method possess a high nitrogen atomic concentration ratio, N/(N+O) of 0.65. When a 1.0nm SiN layer is inserted between HfO2 and Si, interfacial reaction is completely prevented, resulting in a smaller effective oxide thickness, EOT of 1.4nm. In spite of the smaller EOT, the leakage current density is nearly the same as that with no SiN layer, possibly due to the prevention of the formation of the conduction channels. PDA at 400°C improves HfO2 characteristics without causing the interfacial reaction, leading to a decrease in the leakage current density. [Copyright &y& Elsevier]