Optical lithography deep in the UV spectrum is the predominate route for high-resolution, high-volume nanoscale pattering. However, state-of-the-art optical lithography tools are exceedingly expensive and this places serious limitations on the applications, technical sectors, and markets where highresolution patterning can be implemented. To date the only substantial market for high-end optical lithography tools has been semiconductor fabrication. Nanoimprint lithography (NIL) has recently emerged as an alternative to optical lithography and combines the potential of sub-fi ve-nanometer patterning resolution with the low cost and simplicity of a stamping process. [1][2][3][4] This has led to signifi cant efforts to implement NIL methods, not only for semiconductor logic devices, but also in fi elds as diverse as the direct patterning of interlayer dielectrics (ILDs) for back-end-of-line (BEOL) interconnect structures, [5][6][7] bitpatterned magnetic media for data storage, [ 8 , 9 ] and high-brightness light-emitting diodes (LEDs). [ 10 ] Some of these are new areas where nanoscale patterning has previously not been considered, and are made possible here by the low cost and simplicity of the NIL stamping processes.NIL and other stamping processes are direct write (1 × ) technologies. There is a one-to-one correlation between the features in the mold and the imprint, meaning that high-quality imprint molds are critical. In fact, one of the biggest impediments to the widespread implementation of NIL is the limited availability of high-quality molds. High-resolution imprint molds are usually fabricated by slow, serial patterning techniques such as electron-beam (e-beam) lithography. While the NIL tools themselves are relatively inexpensive, the fabrication of highresolution 1 × molds can be prohibitive in terms of the fabrication time and cost. Furthermore, the notion of stamping these expensive master templates into contact with a resist material under high-temperature and elevated pressure radiation raises concerns regarding template durability. Ideally they should be cheap, simple, and easy to replace.There are several critical properties, in addition to patternability, that must be achieved when designing NIL molds. In the thermal embossing form of NIL, [ 1 , 2 ] a hard mold is pressed into a molten polymer fi lm at elevated temperature and a squeezefl ow process generates the pattern. The NIL mold material needs to have appropriate mechanical properties to resist deformation under the imprinting conditions and to withstand the elevated temperatures. With the UV forms of NIL, [ 3 , 4 ] a monomeric liquid fl ows into the cavities of the mold and is crosslinked into a rigid pattern upon exposure to the radiation. Here, the mold must not only be mechanically robust, but also UV transparent. In all forms of NIL, a low-energy surface is critical to facilitate the release of the high surface area mold from the imprint; the adhesive forces between mold and the template can become signifi cant.A range of materials ha...

The direct depolymerization of SiO2 to distillable alkoxysilanes has been explored repeatedly without success for 85 years as an alternative to carbothermal reduction (1900 °C) to Si(met) , followed by treatment with ROH. We report herein the base-catalyzed depolymerization of SiO2 with diols to form distillable spirocyclic alkoxysilanes and Si(OEt)4. Thus, 2-methyl-2,4-pentanediol, 2,2,4-trimethyl-1,3-pentanediol, or ethylene glycol (EGH2) react with silica sources, such as rice hull ash, in the presence of NaOH (10%) to form H2O and distillable spirocyclic alkoxysilanes [bis(2-methyl-2,4-pentanediolato) silicate, bis(2,2,4-trimethyl-1,3-pentanediolato) silicate or Si(eg)2 polymer with 5-98% conversion, as governed by surface area/crystallinity. Si(eg)2 or bis(2-methyl-2,4-pentanediolato) silicate reacted with EtOH and catalytic acid to give Si(OEt)4 in 60% yield, thus providing inexpensive routes to high-purity precipitated or fumed silica and compounds with single Si-C bonds.

No abstract

The direct depolymerization of SiO 2 to distillable alkoxysilanes has been explored repeatedly without success for 85 years as an alternative to carbothermal reduction (1900 8 8C) to Si met ,followed by treatment with ROH. We report herein the base-catalyzed depolymerization of SiO 2 with diols to form distillable spirocyclic alkoxysilanes and Si(OEt) 4 .T hus,2methyl-2,4-pentanediol, 2,2,4-trimethyl-1,3-pentanediol, or ethylene glycol (EGH 2 )r eact with silica sources,s uch as rice hull ash, in the presence of NaOH (10 %) to form H 2 Oa nd distillable spirocyclic alkoxysilanes [bis(2-methyl-2,4-pentanediolato) silicate,bis(2,2,4-trimethyl-1,3-pentanediolato) silicate or Si(eg) 2 polymer with 5-98 %c onversion, as governed by surface area/crystallinity.S i(eg) 2 or bis(2-methyl-2,4-pentanediolato) silicate reacted with EtOH and catalytic acid to give Si(OEt) 4 in 60 %y ield, thus providing inexpensive routes to high-purity precipitated or fumed silica and compounds with single SiÀCb onds.

No abstract