Effect of nitridation on Al/HfO 2 /Ge MIS capacitors
01 Dec 2007-pp 194-197
TL;DR: In this article, the performance of IS capacitors on nitrided and non-nitrided Ge substrates with HfO2 as the dielectric have been studied.
Abstract: MIS capacitors on nitrided and non-nitrided Ge substrates with HfO2 as the dielectric have been studied Effective oxide thickness is found to be reduced after nitridation Significant improvements in the electrical characteristics are observed for the devices fabricated on nitrided substrates The value of density of interface states is found to be lower for nitrided device when compared to non-nitrided device Leakage current is drastically reduced for the nitrided device The Breakdown field strength is improved from 113 MV/cm for the non-nitrided device to 1589 MV/cm for the nitrided device
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TL;DR: In this paper, a review of the literature in the area of alternate gate dielectrics is given, based on reported results and fundamental considerations, the pseudobinary materials systems offer large flexibility and show the most promise toward success.
Abstract: Many materials systems are currently under consideration as potential replacements for SiO2 as the gate dielectric material for sub-0.1 μm complementary metal–oxide–semiconductor (CMOS) technology. A systematic consideration of the required properties of gate dielectrics indicates that the key guidelines for selecting an alternative gate dielectric are (a) permittivity, band gap, and band alignment to silicon, (b) thermodynamic stability, (c) film morphology, (d) interface quality, (e) compatibility with the current or expected materials to be used in processing for CMOS devices, (f) process compatibility, and (g) reliability. Many dielectrics appear favorable in some of these areas, but very few materials are promising with respect to all of these guidelines. A review of current work and literature in the area of alternate gate dielectrics is given. Based on reported results and fundamental considerations, the pseudobinary materials systems offer large flexibility and show the most promise toward success...
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TL;DR: In situ and ex- situ oxidation studies are carried out on Ge(100) and Ge(111) employing techniques of ultraviolet and X-ray photoelectron spectroscopy (UPS and XPS) as mentioned in this paper.
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TL;DR: In this paper, a 1.5 nm direct-tunneling gate oxide was used to achieve a transconductance of more than 1,000 mS/mm at a gate length of 0.09 /spl mu/m at room temperature.
Abstract: In this paper, normal operation of a MOSFET with an ultra-thin direct-tunneling gate oxide is reported for the first time. These high current drive n-MOSFET's were fabricated with a 1.5 nm direct-tunneling gate oxide. They operate well at gate lengths of around 0.1 /spl mu/m, because the gate leakage current falls in proportional to the gate length, while the drain current increases in inverse proportion. A current drive of more than 1.0 mA//spl mu/m and a transconductance of more than 1,000 mS/mm were obtained at a gate length of 0.09 /spl mu/m at room temperature. These are the highest values ever obtained with Si MOSFET's at room temperature. Further, hot-carrier reliability is shown to improve as the thickness of the gate oxide is reduced, even in the 1.5 nm case. This work clarifies that excellent performance-a transconductance of over 1,000 mS/mm at room temperature-can be obtained with Si MOSFET's if a high-capacitance gate insulator is used.
331 citations
TL;DR: In this article, a surface annealing step in NH3 ambient before the HfO2 deposition could result in significant improvement in both gate leakage current and the equivalent oxide thickness (EOT).
Abstract: Metal-oxide-semiconductor capacitors were fabricated on germanium substrates by using metalorganic-chemical-vapor-deposited HfO2 as the dielectric and TaN as the metal gate electrode. It is demonstrated that a surface annealing step in NH3 ambient before the HfO2 deposition could result in significant improvement in both gate leakage current and the equivalent oxide thickness (EOT). It was possible to achieve a capacitor with an EOT of 10.5 A and a leakage current of 5.02×10−5 A/cm2 at 1 V gate bias. X-ray photoelectron spectroscopy analysis indicates the formation of GeON during surface NH3 anneal. The presence of Ge was also detected within the HfO2 films. This may be due to Ge diffusion at the high temperature (∼400 °C) used in the chemical-vapor deposition process.
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TL;DR: In this paper, the microstructural and electrical properties of Ge-based metal-oxide-semiconductor capacitors containing high-k gate dielectric layers were investigated with and without the presence of a GeOxNy interface layer.
Abstract: The microstructural and electrical properties of Ge-based metal–oxide–semiconductor capacitors containing high-k gate dielectric layers were investigated with and without the presence of a GeOxNy interface layer. The effect of this nitrided layer on thermal stability of the metal oxide/Ge structures was probed by medium energy ion energy spectroscopy (MEIS). Atomic-layer deposited HfO2 on a chemical oxide-terminated Ge (100) surface exhibited poor capacitance–voltage behavior; however, direct substrate surface nitridation at 600°C in NH3 ambient before HfO2 deposition improved the carrier trapping characteristics. Diffusion of metal impurities (including Hf) into the interfacial oxide/Ge-substrate may be an important source of the measured degradation of electrical properties. MEIS results suggested that the GeOxNy interface layer may inhibit Hf diffusion into the underlying semiconductor at the temperatures investigated.
131 citations