In this paper, we experimentally address the effect of a wide range of parameters on the high-field transport of inversion-layer electrons and holes. The studied parameters include substrate doping level, surface micro-roughness, vertical field strength, nitridation of the gate oxide, and device channel length. We employ special test structures built on Silicon-On-Insulator (SOI) and bulk wafers to accurately measure the high-field drift velocity of inversion-layer carriers. Our findings point to electron velocity overshoot at room temperature, dependence of electron and hole saturation velocities on nitridation of the gate oxide, dependence of the high-field drift velocity on the effective vertical field, and relative insensitivity of electron and hole mobility and saturation velocity to moderate surface roughness.

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This paper introduces a novel concept, "comeless phase-shifting', that eliminates the need for the use of chrome to form patterns in optical lithography. Chromeless phase-shifting uses 180° phaseshifters on transparent glass to define patterns. The method relies on the destructive interference between phase-shifters and clear areas at the edges of the phase-shifters to define dark or opaque areas on the mask. Gratings sufficiently small will produce sufficient interference to completely inhibit the transmission of light (these gratings are thus named dark-field gratings). The combination of these effects makes it possible to form a wide range of patterns, from line-space patterns to isolated bright or dark areas.In this study, the lithography simulators SPLAT and SAMPLE were used to understand the principles behind this new scheme, and to verify various pattern designs. Simulation and experimental results are presented to demonstrate the concept. tional chrome mask. A phase-shift layer delays the light from a pattern so that it arrives 1800 out of phase with the light through a clear area. By careful placement of the phase-shifting material, the light from the phase-shifted and non-phase-shifted areas can be made to interact coherently, thus producing a

Resists for optical electron beam, and x-ray lithographies that operate on the principles of chemical amplification are entering into widespread use in laboratories. They offer an attractive alternative to conventional positive Novolac photoresists and we may soon see similar use in manufacturing environments. One class of resists within this family is based on acid-hardening chemistry. We have characterized one such resist (Shipley ECX-1033) for illumination by excimer laser deep ultraviolet sources and also by x-ray radiation. A matrix of post exposure bake (PEB) conditions and development conditions was used to examine resist sensitivity and contrast. For all exposure sources we found that contrast is independent of PEB processing and that sensitivity obeys an Arrhenius dependence. Contrast increases with increasing development time while exposed resist loss is minor. A simple kinetic model was developed to explain the observed variations of apparent resist sensitivity with PEB time and temperature. The generality of this model suggests that it is widely applicable to other chemical amplification resists that require a post exposure bake. Together with aerial image calculations for different light sources, the model makes it possible to predict the dependence of line width on PEE conditions. In other words, we can anticipate the PEB process control required to achieve a specified critical dimension control. Electrical linewidth measurements of submicron features and their temperature dependence are compared with the predictions of the model.

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