Search

The ability to use photoactivated stress relaxation to improve flaw tolerance in network polymers is demonstrated and specimens with well-defined flaws are fabricated. The phenomena that occur at the multiaxial stress state at the flaw is understood by modeling the photomechanics by using a finite element approach that has described the light propagation, photochemistry, radical-induced network evolution and the mechanical behavior of the material.

The authors review the publications on photomechanical ablation. The topics of interest include the photomechanical stress generation below the ablation threshold, ablation and fracture mechanisms, and photomechanical ablation carried out via transient thermoelastic stress.

The primary cause of greater than unity mask error factor (MEF) is degradation of image integrity. Mathematical description of image formation reveals the gradual loss of image shape control by photomask features as the critical dimension decreases below 0.8([Lambda]/NA). The growing contribution of mask critical dimension error to line-width variation prompts generalization of the conventional two-dimensional (2-D) exposure-defocus window (ED window) to a three-dimensional (3-D) mask-exposure-defocus volume (MED volume), adding mask tolerance to exposure latitude and depth-of-focus as the important parameters of a process. The increase in MEF with feature nesting means that the relative importance of sources of line-width variation changes with pattern pitch. Mask improvement is the most effective means to reduce line-width variation for dense features, but lens quality is the most significant factor affecting line-width control for sparse patterns. The approximately 20% higher MEF of dark-field masks, low MEF of alternating phase-shifting masks, and relatively high MEF of assist features all have ramifications on lithography strategies for printing sparse lines. The MEF does not simply indicate a need for high-quality masks, it also sheds light on the critical areas in which improvements are needed for successful lithography, and the disciplines that need to cooperate for successful device fabrication. Index Terms--Lithography, mask error factor, photomask.

Measurement of the release of substrate from the photolysis of the caged glutamate derivative in aqueous medium, in the microsecond time scale, is presented using Fourier transform infrared of gamma-(alpha-carboxy-2-nitrobenzyl)-L-glutamate.