45 research outputs found
Comparison of positive tone versus negative tone resist pattern collapse behavior
© 2010 American Vacuum Society. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Vacuum Society. The electronic version of this article is the complete one and can be found at: http://dx.doi.org/10.1116/1.3518136In this work, e-beam lithography patterns have been specifically designed and fabricated which provide the opportunity to probe the collapse behavior of both positive and negative tone systems. The pattern layout includes adjacent parallel line structures that both vary in the line size and also in the distance by which they are separated by the space between them. This type of structure allows for the control and modulation of the capillary forces, and ultimately the stresses, experienced by the photoresist line pairs during the final rinse and drying steps of the development process. Using such structures, it is possible to determine the critical stress, i.e., the maximum stress experienced by the photoresist lines before collapse, as a function of a variety of parameters including: material type, substrate preparation conditions, resist film thickness, and resist feature width. In this article, such a modular approach has been used to compare the pattern collapse behavior of a prototypical positive tone resist formulated using a protected hydroxystyrene-based copolymer and a prototypical negative tone epoxide-based molecular photoresist (4-EP). It was found that the critical stress at the point of pattern collapse decreased both as the thickness and the feature width of the resist lines decreased, though this trend was observed to a much lesser extent in the negative tone 4-EP material. It is observed that the negative tone resist, whose imaging mechanism involves cross-linking, shows far superior pattern collapse performance as compared to the positive tone deprotection based resist and is in general able to achieve significantly higher aspect ratio patterning at equivalent feature linewidths. (C) 2010 American Vacuum Society
Fundamentals of carbanion photochemistry
Issued as Progress report, and Final report, Project no. G-33-66
Bio-oxidation of arylalkyl hydrocarbons
Issued as Progress report summary, Project no. G-33-666 (continued by G-33-614
Charge distribution in photoexcited molecules
Issued as Progress reports [nos. 1-2], and Final report, Project G-33-63
It's All in the Interpretation
We often see disparate interpretations in language and politics, but the same is true in science expriments. This is particularly true in chemistry where one cannot see the molecules directly. Laren Tolbert of the Georgia Tech School of Chemistry & Biochemistry joins us to discusses challenges in interpreting such experiments
Excited-State Proton Transfer in Gas-Expanded Liquids: The Roles of Pressure and Composition in Supercritical CO2/Methanol Mixtures
Excited-state proton transfer from 5,8-dicyano-2-naphthol to methanol takes place in CO2/methanol mixtures, in the pressure and temperature ranges of supercritical CO2. The efficiency of the proton-transfer step decreases with the pressure. This is assigned to the perturbation of the methanol clusters solvating the naphthol