The use of solution processes-as opposed to conventional vacuum processes and vapour-phase deposition-for the fabrication of electronic devices has received considerable attention for a wide range of applications, with a view to reducing processing costs. In particular, the ability to print semiconductor devices using liquid-phase materials could prove essential for some envisaged applications, such as large-area flexible displays. Recent research in this area has largely been focused on organic semiconductors, some of which have mobilities comparable to that of amorphous silicon (a-Si); but issues of reliability remain. Solution processing of metal chalcogenide semiconductors to fabricate stable and high-performance transistors has also been reported. This class of materials is being explored as a possible substitute for silicon, given the complex and expensive manufacturing processes required to fabricate devices from the latter. However, if high-quality silicon films could be prepared by a solution process, this situation might change drastically. Here we demonstrate the solution processing of silicon thin-film transistors (TFTs) using a silane-based liquid precursor. Using this precursor, we have prepared polycrystalline silicon (poly-Si) films by both spin-coating and ink-jet printing, from which we fabricate TFTs with mobilities of 108 cm2 V(-1) s(-1) and 6.5 cm2 V(-1) s(-1), respectively. Although the processing conditions have yet to be optimized, these mobilities are already greater than those that have been achieved in solution-processed organic TFTs, and they exceed those of a-Si TFTs (< or = 1 cm2 V(-1) s(-1)).
We have developed a liquid precursor that can be used in a solution process to form n-type doped silicon films. This precursor is based on phosphorus-doped hydrogenated polysilane synthesized by photo-copolymerizing cyclopentasilane and white phosphorus. By spin-coating this precursor, we have prepared n-type amorphous silicon films and polycrystalline silicon films with resistivities of 6.5–27 Ω·cm and 2.0–10 mΩ·cm, respectively.
Siloxane/silsesquioxane (SSQ) and fluorocarbon` materials have been identified to be relatively transparent at 157 nm. While the main stream of material research effort has been focused on the synthesis of fluorocarbon polymers, we have made significant progress on developing silsesquioxane polymers for 157 nm photoresist application. Our current SSQ based photoresists (a, s, and 8 type shown in this paper) have absorbance value ranging from 3.4 to 2.5 µm"' . With a 1200 A thickness, a type has demonstrated 60nm L/S using a 0.85 NA F2 Exitech tool with an alt-PSM and c and 6 type have demonstrated 75nm L/S using a 0.60 NA tool. a type resist patterns (L/S) have been successfully transferred down to underlying spin-on carbon hard mask (HM) using N2/02 RIE. Progress also has been made on reducing the absorbance of SSQ polymers. A new ?. type SSQ polymer showed absorbance value of 1.66 µm'. The design concept and physical properties of synthesized SSQ polymers are presented. Lithographic performance of SSQ based resists is also discussed.
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