We report the growth of an ultrathin 1.0 nm ͑equivalent oxide thickness ϭ 0.86 nm) oxynitride gate dielectric by rapid thermal processing ͑RTP͒ in high-N 2 but low-O 2 gas flow ambient. The effect of the changing N 2 /O 2 gas flow ratio on the characteristics of oxynitride films was investigated. High-quality oxynitride film could be formed by RTP in an optimum N 2 /O 2 gas flow ratio of 5/1. Detailed characterization ͑transmission electron microscopy, J-E capacitance-voltage, stress-induced leakage current, charge-trapping properties͒ demonstrated the high quality of the oxynitride dielectric and showed that low leakage current density J g ϭ 0.1 A/cm 2 at 1 V, was 1.85 orders of magnitude lower than that of SiO 2 . These improvements are attributed to the presence of nitrogen at the interface and in the bulk of the oxynitride.Highly reliable and aggressively scaled gate dielectric films ͑equivalent oxide thickness, EOT р 1.0 nm) are necessary for developing complementary metal oxide semiconductor ͑CMOS͒ technologies in the sub-50 nm regime. However, when the thickness of SiO 2 is reduced below 2 nm, as for ultrathin oxides, important concerns of gate leakage and device reliability arise. 1-3 For these reasons, alternative gate dielectrics must be considered. In the course of searching for such an alternative gate dielectric, ultrathin NH 3 -nitride SiO 2 , N 2 O/NO oxynitride, N/O stack, plasma-nitrided SiO 2 , and high-k dielectrics have been widely studied as the promising replacements for thermal oxide as gate dielectrics, while maintaining a low gate leakage and increased capacitance for future sub-50 nm CMOS devices. 4-18 Desirable gate dielectrics should have good uniformity, small defect density, and high dielectric strength; they should endure hot-electron injection for maintaining device reliability. As mentioned above, much work in this field has been focused on the nitridation of SiO 2 . NH 3 -nitrided SiO 2 films can be effectively used to increase the proportion of incorporated N atoms; increasing the fixed charge and interface trap densities is unavoidable, due to the generation of electron traps related to -NH x , -H, and -OH bonds introduced from NH 3 . 4 The NH 3 -nitrided films have also been reported to show degraded mobility due to heavy nitridation and increased electron trapping. 5 N 2 O and NO have been proposed as alternatives without the disadvantages of NH 3 for oxidation and nitridation; the resulting films exhibit favorable electrical characteristics; however they do not have enough nitrogen ͑only ϳ1-2 atom %͒ at the dielectric silicon interface to prevent boron penetration. 6-9 The ultrathin nitride/oxide ͑N/O͒ stack has been investigated as a promising structure for suppressing leakage current and boron penetration, while maintaining the excellent oxide/Si interface. 10,11 The results of such investigations indicate that dielectric films formed by N/O stacks have higher nitrogen concentrations in both the bulk of the film and at the dielectric-silicon interface. However, most of the...

Semiconductor nanowires (NWs) have been extensively investigated and discussed in various fields due to their unique physical properties. In this paper, we successfully produce SiGe NWs biosensor by VLSI technology. We propose the dual plasma technology with CF4 plasma pre-treatment and N2 plasma post-treatment for repairs of defects as well as optimization of SiGe NWs biosensor. The results indicate that sensitivity (S) of the biosensor with dual plasma technology has significantly improved at least 32.8%, suitable for producing industrial SiGe NWs biosensor in the future.

The oxidation caused by Ge condensation increases the Ge fraction in a SiGe-on-insulator (SGOI) and significantly increases the hole mobility. This effect can be exploited to improve the sensitivity of SGOI nanowires. However, previous studies have found that the sensitivity of SGOI nanowires degrades when the Ge fraction exceeds 20%, because a high Ge fraction destabilises the surface state of SiGe. In this work, a top surface passivation plasma-enhanced chemical vapour deposition SiO 2 layer deposited on a Si 0.8 Ge 0.2 nanowire improved its sensitivity by 1.3 times that of the nanowire sample without a top passivation layer.

Si1−xGex nanowire biosensors are attractive for their high sensitivity due to the large surface-to-volume ratio, high carrier mobility, and silicon compatibility. In this work, we study the effect of the thickness of the low-temperature Si (LT-Si) buffer layer on an insulator on the sensitivity of oxidized Si1−xGex nanowire samples with different Ge contents by increasing the Si buffer thickness from 20 to 60 nm. 3-Aminopropyltrimethoxysilane (APTMS) was used as a biochemical reagent. It was demonstrated that, with the proper Ge content and LT-Si buffer thickness, the sensitivity of the Si1−xGex nanowire is high and it can be further improved by Si1−xGex oxidation. This can be attributed to the reduction of the diameter to the nanometer order, which gives rise to an increased surface-to-volume ratio and further enhances the sensitivity of the biosensor.

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