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Silicon nanowire field-effect transistors (SiNWFETs) have been fabricated with a highly simplified integration scheme to function as Schottky barrier transistors with excellent enhancement-mode characteristics and a high on/off current ratio ∼107. SiNWFETs show significant improvement in the thermal emission leakage (∼6 × 10−13 A µm−1) compared to reference FETs with a larger channel width (∼7 × 10−10 A µm−1). The drain current level depends substantially on the contact metal work function as determined by examining devices with different source/drain contacts of Ti (≈4.33 eV) and Cr (≈4.50 eV). The different conduction mechanisms for accumulation- and inversion-mode operation are discussed and compared with two-dimensional numerical simulation results.

Dual-gated silicon nanowire (SiNW) field-effect transistors (FETs) have been fabricated by using electron-beam lithography. SiNW devices (W approximately 60 nm) exhibit an on/off current ratio greater than 10(6), which is more than 3 orders of magnitude higher than that of control devices prepared simultaneously having a large channel width (approximately 5 microm). In addition, by changing the local energy-band profile of the SiNW channel, the top gate is found to suppress ambipolar conduction effectively, which is one of the factors limiting the use of nanotube or nanowire FETs for complimentary logic applications. Two-dimensional numerical simulations show that the gate-induced electrostatic control is improved as the channel width of the FETs decreases. Therefore, enhanced channel modulations can be achieved in these dual-gated SiNW devices.

The generality of the curvature-enhanced accelerator coverage ͑CEAC͒ model of superconformal electrodeposition is demonstrated through application to superconformal filling of fine trenches during silver deposition from a selenium-catalyzed silver cyanide electrolyte. The CEAC mechanism involves ͑i͒ increase of local metal deposition rate with increasing coverage of a catalytic species adsorbed on the metal/electrolyte interface and ͑ii͒ significant change of local coverage of catalyst ͑and thus local deposition rate͒ in submicrometer features through the changing area of the metal/electrolyte interface. Electrochemical and X-ray photoelectron experiments with planar electrodes ͑substrates͒ are used to identify the catalyst and obtain all kinetic parameters required for the simulations of trench filling. In accord with the model, the electrolyte yields optically shiny, dense films, hysteretic current-voltage curves, and rising current-time transients. Experimental silver deposition in trenches from 350 down to 200 nm wide are presented and compared with simulations based on the CEAC mechanism. All kinetics for the modeling of trench filling come from the studies on planar substrates. The results support the CEAC mechanism as a quantitative formalism for exploring morphological evolution during film growth.Superconformal electrodeposition of copper in the Damascene process for microelectronic fabrication is enabling a new generation of integrated circuits. The use of copper interconnections has permitted faster clock speeds, enhanced reliability, and lower processing cost. Central to the success of the electrodeposition process is its ability to yield void and seam-free filling of high aspect ratio features. Empirically, such superfilling of trenches and vias with copper results from more rapid metal deposition ͑growth͒ at the bottom of the feature than at the sidewalls. Early models of superfilling of copper in trenches assumed location-dependent growth rates derived from diffusion-limited accumulation of only an inhibiting species. 1,2 Such models were unable to predict several key experimental observations. 3-6 Understanding of the superfill phenomena has improved substantially in the past two years. Electrolytes for the study of superconformal electrodeposition of copper have been fully disclosed. 6,7 A correlation between efficacy for superconformal filling of fine features, hysteresis in cyclic current-voltage studies, and recrystallization of deposits has also been demonstrated. 6 In addition, the curvature-enhanced accelerator coverage ͑CEAC͒ mechanism has been used to quantitatively predict superconformal copper deposition in trenches. [8][9][10][11] and vias 12 by electrodeposition as well as by surfactant-catalyzed chemical vapor deposition ͑CVD͒. 13,14 The CEAC mechanism involves the gradual accumulation of a metal-deposition-rate-accelerating species at the surface of the growing metal. If there is a deposition-rate-inhibiting species, it is presumed to be weakly bound and displaced, or altered, by th...

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