@article{suh_lazar_chen_lee_misra_2005, title={Electrical characteristics of HfO2 dielectrics with Ru metal gate electrodes}, volume={152}, ISSN={["1945-7111"]}, DOI={10.1149/1.1992467}, abstractNote={Hafnium dioxide, HfO 2 , thin films were prepared by radio frequency magnetron sputtering of thin hafnium layers, followed by an oxidation process. Ru was deposited on the HfO 2 as the gate electrode. An equivalent oxide thickness of 12.5 A was obtained in Ru/HfO 2 /n-Si metal oxide semiconductor (MOS) capacitor with a low leakage current density of 1.7 × 10 - 2 A/cm 2 at Vg - V F B = 1 V in accumulation. The work function of Ru gate extracted from capacitance-voltage analysis was 5.02 eV, suggesting Ru has the appropriate work function for p-MOSFETs. Using the conductance method, a high interface state density of 1.3 X 10 1 3 eV - 1 cm - 2 from the conduction band edge to the near midgap of Si was obtained in Ru/HfO 2 /n-Si MOS, compared to low interface density level of ∼ 10 1 1 eV - 1 cm - 2 in p + poly Si/SiO 2 /n-Si MOS. To evaluate the thermal stability, the samples were subjected to a rapid thermal anneal in an argon ambient up to 900°C. The electrical characteristics of Ru/HfO 2 /n-Si MOS capacitor are discussed in detail with post-metal annealing temperatures.}, number={9}, journal={JOURNAL OF THE ELECTROCHEMICAL SOCIETY}, author={Suh, YS and Lazar, H and Chen, B and Lee, JH and Misra, V}, year={2005}, pages={F138–F141} }
 @article{chen_suh_lee_gurganus_misra_cabral_2005, title={Physical and electrical analysis of RuxYy alloys for gate electrode applications}, volume={86}, ISSN={["1077-3118"]}, DOI={10.1063/1.1857093}, abstractNote={This letter describes RuxYy as a potential candidate for dual metal complementary metal–oxide–semiconductor applications. The characterization of RuY alloys indicate that the effective work function can be controlled from 3.9to5.0eV as the yttrium composition in the RuxYy is decreased in film for both PMOS and NMOS application. From x-ray photoelectron spectroscopy analysis, it was found that the Ru3d peaks do not change as the Y composition is changed, indicating the Ru–Y bonding is very weak or undetectable in RuxYy film. However, it was also found that Y reacts with the underlying SiO2 to form yttrium silicate. In addition, in situ x-ray diffraction results did not detect the presence of Ru–Y compound in the RuxYy films. Capacitance–voltage (C–V) characterization indicated that the oxide thickness decreased as the Y composition increased. We extracted the effective barrier height of RuxYy at the metal–oxide interface via Fowler–Nordheim current analysis. The barrier height decreases as the Y compositio...}, number={5}, journal={APPLIED PHYSICS LETTERS}, author={Chen, B and Suh, Y and Lee, J and Gurganus, J and Misra, V and Cabral, C}, year={2005}, month={Jan} }
 @article{suh_heuss_misra_2004, title={Characteristics of TaSixNy thin films as gate electrodes for dual gate Si-complementary metal-oxide-semiconductor devices}, volume={22}, ISSN={["2166-2746"]}, DOI={10.1116/1.1640398}, abstractNote={Reactively sputtered TaSixNy films have been investigated as gate electrodes for dual gate Si-complementary metal-oxide-semiconductor devices. The as-deposited TaSixNy films were amorphous over a wide range of compositions. After annealing at 1000 °C, Ta30Si33N37 film became crystalline, however Ta26Si28N52 film remained amorphous. The x-ray photoelectron spectroscopy shows a significant increase of Si–N bonding in the TaSixNy films with increasing N content. The presence of Si–N bonds is attributed to cause the amorphous nature of the high N containing TaSixNy films. The work functions of TaSixNy films were extracted by capacitance–voltage analysis. The work function values for TaSixNy films with varying N contents range from 4.26 to 4.35 eV after forming gas annealing at 400 °C for 30 min, suggesting that TaSixNy films have work functions appropriate for n-type metal-oxide-semiconductor devices. However, it was observed, after 1000 °C anneals, that the work function of TaSixNy films increased to ∼4.8 eV. We believe that the mechanism that causes the work function to increase is the formation of a Ta-disilicide layer at the interface of the electrode and the dielectric. Current–voltage characteristics of the TaSixNy gates showed lower gate leakage compared to the TaSix gates, due to the retarding formation of an interface layer in the TaSixNy/SiO2/p-Si structures.}, number={1}, journal={JOURNAL OF VACUUM SCIENCE & TECHNOLOGY B}, author={Suh, YS and Heuss, G and Misra, V}, year={2004}, pages={175–179} }
 @article{suh_park_jang_2004, title={Investigation of stress behaviors and mechanism of void formation in sputtered TiSix films}, volume={450}, ISSN={["0040-6090"]}, DOI={10.1016/j.tsf.2003.11.165}, abstractNote={We have investigated the stress behaviors and a mechanism of void formation in TiSix films during annealing. TiSix thin films were prepared by DC magnetron sputtering using a TiSi2.1 target in the substrate temperature range of 200–500 °C. The as-deposited TiSix films at low substrate temperature (<300 °C) have an amorphous structure with low stress of ∼1×108 dynes/cm2. When the substrate temperature increases to 500 °C, the as-deposited TiSix film has a mixture of C49 and C54 TiSi2 phase with stress of ∼8×109 dynes/cm2. No void was observed in the as-deposited TiSix film. Amorphous TiSix film transforms to C54 TiSi2 phase with a random orientation of (311) and (040) after annealing at 750 °C. The C49 and C54 TiSi2 mixture phase transforms to (040) preferred C54 TiSi2 phase after annealing over 650 °C. By increasing substrate temperature, the transformation temperature for C54 TiSi2 can be reduced, resulting in relieved stress of TiSi2 film. The easy nucleation of the C54 phase was attributed to an avoidance of amorphous TiSix phase. We found that amorphous TiSix→C54 TiSi2 transformation caused higher tensile stress of 2×1010 dynes/cm2, resulting in more voids in the films, than C49→C54 transformation. It was observed that void formation was increased with thermal treatment. The high tensile stress caused by volume decreases in the silicide must be relieved to retard voids and cracks during C54 TiSi2 formation.}, number={2}, journal={THIN SOLID FILMS}, author={Suh, YS and Park, DG and Jang, SA}, year={2004}, month={Mar}, pages={341–345} }
 @article{suh_heuss_lee_misra_2003, title={Effect of the composition on the electrical properties of TaSixNy metal gate electrodes}, volume={24}, ISSN={["1558-0563"]}, DOI={10.1109/LED.2003.814009}, abstractNote={In this letter, the effect of silicon and nitrogen on the electrical properties of TaSi/sub x/N/sub y/ gate electrode were investigated. The TaSi/sub x/N/sub y/ films were deposited on SiO/sub 2/ using reactive cosputtering of Ta and Si target in Ar and N/sub 2/ ambient. The thermal stability of TaSi/sub x/N/sub y//SiO/sub 2//p-type Si stacks was evaluated by measuring the flatband voltage and equivalent oxide thickness at 400/spl deg/C and 900/spl deg/C in Ar. It was found that under high temperature anneals, Si-rich TaSi/sub x/N/sub y/ films increased and this was attributed to the formation of a reaction layer at the electrode-dielectric interface. Reducing the Si content alone did not prevent the formation of this reaction layer while removing Si completely by utilizing TaN resulted in work functions that were too high. The presence of both Si and N was deemed necessary and their content was critical in obtaining optimized TaSi/sub x/N/sub y/ gates that are suitable for NMOS devices.}, number={7}, journal={IEEE ELECTRON DEVICE LETTERS}, author={Suh, YS and Heuss, GP and Lee, JH and Misra, V}, year={2003}, month={Jul}, pages={439–441} }
 @article{suh_heuss_misra_park_limb_2003, title={Thermal stability of TaSixNy films deposited by reactive sputtering on SiO2}, volume={150}, ISSN={["1945-7111"]}, DOI={10.1149/1.1562599}, abstractNote={The thermal stability of /p-type Si metal-insulator-semiconductor structure has been evaluated by measuring equivalent oxide thickness (EOT) from capacitance-voltage curves and gate leakage current as a function of annealing temperatures. films were deposited using reactive sputtering from a target, varying the nitrogen/argon flow ratio. A reaction between and was observed after a 1000°C anneal, resulting in the increase of interfacial roughness and oxide thickness in the structures. Cross-sectional transmission electron microscopy shows no indication of an interfacial reaction or crystallization in on up to 1000°C as manifested by the negligible change in EOT and the stable leakage currents density A/cm2 at V). The presence of Si-N bonds is attributed to cause the amorphous nature of the high N-containing films. This may retard the formation of an interface layer and improve the chemical-thermal stability of the gate electrode/dielectric interface and oxygen diffusion barrier properties under high-temperature annealing. © 2003 The Electrochemical Society. All rights reserved.}, number={5}, journal={JOURNAL OF THE ELECTROCHEMICAL SOCIETY}, author={Suh, YS and Heuss, GP and Misra, V and Park, DG and Limb, KY}, year={2003}, month={May}, pages={F79–F82} }
 @article{suh_heuss_misra_2002, title={Electrical characteristics of TaSixNy/SO2/Si structures by Fowler-Nordheim current analysis}, volume={80}, ISSN={["0003-6951"]}, DOI={10.1063/1.1453478}, abstractNote={In this letter, the Fowler–Nordheim tunneling in TaSixNy/SiO2/p-Si structures has been analyzed. The effective barrier height at the metal–oxide interface was extracted by Fowler–Nordheim current analysis. The barrier height was found to increase with increased annealing temperature. The barrier height was correlated with the extracted work function from capacitance–voltage analysis. This indicated that the work function of TaSixNy films changes under high temperature annealing from 4.2∼4.3 eV after 400 °C anneals to ∼4.8 eV after 900 °C anneals. We believe that the mechanism that causes the work function to increase is the formation of a Ta-disilicide layer at the interface between the electrode and the dielectric.}, number={8}, journal={APPLIED PHYSICS LETTERS}, author={Suh, YS and Heuss, GP and Misra, V}, year={2002}, month={Feb}, pages={1403–1405} }