@article{lichtenwalner_jur_jha_inoue_chen_misra_kingon_2006, title={High-temperature stability of lanthanum silicate gate dielectric MIS devices with Ta and TaN electrodes}, volume={153}, ISSN={["1945-7111"]}, DOI={10.1149/1.2218757}, abstractNote={The high-temperature stability of lanthanum silicate gate dielectric metal-insulator-semiconductor (MIS) devices with either Ta or TaN electrodes has been studied. After a 1000°C, 10 s rapid thermal annealing (RTA) treatment, devices with Ta gate metal undergo an equivalent oxide thickness (EOT) increase from 0.62 to 1.57 nm or higher, while devices with TaN as the gate electrode experience an EOT increase from 0.62 to only 1.12 nm. An EOT less than 1.0 nm is achieved after a 5 s 1000°C RTA, with a corresponding gate leakage of 0.1 A/cm 2 . Medium-energy ion scattering and X-ray diffraction (XRD) analysis reveal that the Ta gate metal undergoes a phase change due to reaction with N 2 above 800°C, while for TaN no change in the XRD spectrum is detected. Interface state defect densities and leakage currents are reduced after the high-temperature processing. Results reveal the importance of the entire gate stack design and processing in obtaining good device properties.}, number={9}, journal={JOURNAL OF THE ELECTROCHEMICAL SOCIETY}, author={Lichtenwalner, Daniel J. and Jur, Jesse S. and Jha, Rashmi and Inoue, Naoya and Chen, Bei and Misra, Veena and Kingon, Angus I.}, year={2006}, pages={F210–F214} }
 @article{chen_jha_lazar_biswas_lee_lee_wielunski_garfunkel_misra_2006, title={Influence of oxygen diffusion through capping layers of low work function metal gate electrodes}, volume={27}, ISSN={["1558-0563"]}, DOI={10.1109/LED.2006.871184}, abstractNote={This letter evaluates Ru and W capping layers for MoTa metal gate electrodes in MOS capacitor applications. The authors report that the oxygen diffusion from the capping layer plays an important role in determining the MoTa alloy effective work function value on SiO/sub 2/. A MoTa alloy metal gate with Ru capping exhibits stable effective work function up to 900/spl deg/C annealing but is not stable with W capping. Auger electron spectroscopy and Rutherford backscattering spectroscopy analyses show minimal oxygen diffusion into MoTa gate stacks with Ru capping while severe oxygen diffusion into the gate is observed with W capping metal after 900/spl deg/C annealing. Current-voltage analysis also demonstrates different barrier heights of MoTa on SiO/sub 2/ with Ru or W capping layer after 900/spl deg/C annealing, confirming the effective work function value change.}, number={4}, journal={IEEE ELECTRON DEVICE LETTERS}, author={Chen, B and Jha, R and Lazar, H and Biswas, N and Lee, J and Lee, B and Wielunski, L and Garfunkel, E and Misra, V}, year={2006}, month={Apr}, pages={228–230} }
 @article{chen_jha_misra_2006, title={Work function tuning via interface dipole by ultrathin reaction layers using AlTa and AlTaN alloys}, volume={27}, ISSN={["1558-0563"]}, DOI={10.1109/LED.2006.880643}, abstractNote={This letter presents a route for tuning the metal gate effective work function via interface dipoles formed using AlTa and AlTaN alloys. It was found that the AlTa alloy has a higher effective work function (4.45 eV) compared to either Al (~ 4.1 eV) or Ta (4.2 eV) gates on SiO 2 at 400 degC. This increase in effective work function was attributed to interface dipoles formed at the gate electrode and dielectric interface. The origin of this dipole is attributed to a reaction between the AlTa alloy and the dielectric layer. Similar AlTa effective work function tuning was also observed on high-k dielectrics. However, since the AlTa alloy is not thermally stable on SiO2, nitrogen was added to stabilize the electrode. The addition of N stabilizes the equivalent oxide thickness while still allowing for work function tuning under high temperatures. AlTaN alloys were deposited by reactive sputtering and resulted in an effective work function of ~ 5.1 eV after a 1000 degC anneal, making them suitable for PMOS gate applications}, number={9}, journal={IEEE ELECTRON DEVICE LETTERS}, author={Chen, Bei and Jha, Rashmi and Misra, Veena}, year={2006}, month={Sep}, pages={731–733} }
 @article{jha_lee_majhi_misra_2005, title={Investigation of work function tuning using multiple layer metal gate electrodes stacks for complementary metal-oxide-semiconductor applications}, volume={87}, ISSN={["1077-3118"]}, DOI={10.1063/1.2136425}, abstractNote={Metal gate electrodes consisting of three layered stacks of metals are investigated for complementary metal-oxide-semiconductor device applications. It was observed that the effective work function of the entire gate electrode stack was dominated by the work function of the first metal layer (50A of tantalum nitride) contacting the gate dielectric. No significant difference in the effective oxide thickness was observed in devices with and without the initial tantalum nitride layer. The potential reasons for this, based on the penetration of an electron wave function from the gate electrode to the gate dielectric and gate depletion due to longer Debye length of electrons in tantalum nitride, will be discussed.}, number={22}, journal={APPLIED PHYSICS LETTERS}, author={Jha, R and Lee, J and Majhi, P and Misra, V}, year={2005}, month={Nov} }
 @article{kim_choi_jha_lee_misra_lee_2004, title={Reliability of high-k dielectrics and its dependence on gate electrode and interfacial high-k bi-layer structure}, volume={44}, ISSN={["0026-2714"]}, DOI={10.1016/j.microrel.2004.07.049}, abstractNote={In this work, we present the reliability of HfO 2 and how it depends on the barrier height and the nature of the bi-layer structure. We will also discuss how these factors lead to different charge fluence, charge-to-breakdown, and breakdown characteristics. It is found that the lower Weibull slope of high-k dielectrics is partially attributed to high charge fluence by the lower barrier height of high-k dielectrics, and a different nature of bi-layer structure. In addition, it has been found that there is distinct bi-modal defect generation rate for high-k/SiO 2 stack. A two-step breakdown process was clearly observed. Soft breakdown characteristics were dependent on the barrier heights. It is attributed to different charge fluence by different barrier heights. Charge-to-breakdown shows strong barrier height dependence.}, number={9-11}, journal={MICROELECTRONICS RELIABILITY}, author={Kim, YH and Choi, R and Jha, R and Lee, JH and Misra, V and Lee, JC}, year={2004}, pages={1513–1518} }