Acid-Labile, Chain-Scission Polymer Systems Used as Positive-Tone Photoresists Developable in Supercritical CO₂

Abstract

A new type of acid-catalyzed, chain-scission polymeric system is reported based on main-chain acetal linkages and designed for solubility selectivity in supercritical (sc) CO2. These low-molecular-weight polymer segments, formed by the stepwise polymerization of divinyl ethers and dihydroxy-based monomers, are linked together to render these individually soluble components insoluble in scCO2. Upon exposure to an acid, the linkages are cleaved and result in a system soluble in both aqueous base and scCO2, two widely disparate solvents. This fact is utilized to make a positive-tone photoresist system developable in scCO2 as well as aqueous developer. This represents to the best of our knowledge the first known report of an intrinsically positive-tone photoresist developable in pure scCO2. Excellent solubility contrasts are shown and feature sizes below 200 nm can be obtained with this system.

Doping–Dedoping Interplay to Realize Patterned/Stacked All-Polymer Optoelectronic Devices

“…As previously mentioned, there have been many reports on patterning a single component polymer semiconductor, including the DISC method. − ,, However, patterning polymer–polymer BHJ by DISC or other methods has not yet been demonstrated. In this case, because the active layer consists of both donor and acceptor semiconductors, both oxidizing and reducing dopants need to be employed for pattern developing.…”

“…This is primarily due to the incompatibility of polymer semiconductors with conventional photolithography. There have been many successful research demonstrations of fine-patterning methods of polymer semiconductors, such as the modified photolithography method that uses fluorinated photoresist or a supercritical carbon dioxide (CO 2 ) photoresist, , the stamping method that uses polydimethylsiloxane (PDMS) as a mold, − scanning probe lithography, , and the doping-induced solubility control (DISC) method . The patterning methods described above have their own advantages and disadvantages in terms of pattern precision, pattern spacing, and throughput.…”

Positive‐tone photoresist consisting of a multifunctional acrylate resin that can be patterned after photo‐crosslinking

“…To this aim, various materials with the ability to decompose via heat or light have been proposed. [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20] Multi-functional (meth)acrylates with structures such as tertiary ester, 2-7,10-16 acetal, 8,9,[17][18][19] and carbonate, 20 which experience bond cleavage in acid, have been reported. The research group of Osaka Prefecture University has developed a radically curable tri-functional methacrylate resin with a decomposition function.…”

A Study on Positive Photosensitive Epoxy Resins Using Reaction Development Patterning (RDP)

“…The photoresists have been generally prepared by introducing chromophore units in main chains, on side chains, and/or at the chain ends of polymers. Positive and negative patterns are formed in photolithographic processes using solubility differences of the photoresists to developers between UV exposed and unexposed areas [1][2][3][4][5][6][7][8]. In contrast, Fukushima et al have proposed a new RDP (Reaction Development Pattering) method to easily obtain fine patterns from non-photosensitive plastics such as polyimides, polycarbonates and vinyl polymers that have no chromophore units [9a].…”