@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{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} }