Development and study of nano-imprint and electron beam lithography materials for semiconductor devices.

摘要

Step and Flash Imprint Lithography (SFIL) is a next generation lithography option that has become increasingly attractive in recent years. Elimination of the costly light sources and optical elements in current exposure tools makes SFIL a serious candidate for large-scale commercial patterning of sub-50 nm features. The imprint resist material is one of the key components in the SFIL process, and it has several design requirements, including low viscosity, low volatility, rapid reaction rate, high mechanical strength, low adhesion to the template, high adhesion to substrate, and high oxygen etch resistance. It is quite challenging to find materials that meet all the material requirements.; Traditionally, acrylates have been the monomers of choice for use for Step and Flash Imprint Lithography (SFIL) etch barrier formulations, in part because of the commercial availability of silicon-containing acrylates (necessary for etch resistance), together with their low viscosities and capability for rapid photopolymerization. However, despite many desirable properties, the polymerization of acrylates via radical chain propagation causes some potential issues in the SFIL process as a result of the inhibition of these processes by oxygen. Vinyl ethers are prime candidates to replace acrylates. Their curing proceeds by a cationic mechanism that is insensitive to oxygen and very rapid, while the vinyl ether group contribution to viscosity is significantly lower than that of an acrylate. Silicon-containing vinyl ethers are not widely commercially available and so were synthesized for this study. As expected, formulations based on these vinyl ethers were lower viscosity and faster curing than the acrylate etch barrier formulations presently employed, while the tensile strength of cured vinyl ether formulations were found to be higher than their acrylate counterparts.; The throughput of SFIL can be improved by lowering the viscosity of the imprint material and reducing the drop size. Decreasing viscosity generally increases the volatility of a material, and decreasing drop size increases the area available for evaporation. The rate of evaporation can be predicted based on the methods of Lee-Kesler and Joback-Reid that employ group contributions. These predictions were used to explore the effect of drop size (200 nl, 1 nl, 80 pl) on evaporation rate at 20 °C for various acrylate and vinyl ether monomers. The predicted rates correlate well with experimental values. (Abstract shortened by UMI.)