Ortho‐nitrobenzyl cholate esters have been successfully used as photosensitive components in solution inhibition deep UV photoresists. The photochemical behavior of a variety of substituted o‐nitrobenzyl cholate derivaties has been examined and resist sensitivity is related to the quantum yield of the reaction. The most efficient system examined is o, o′‐dinitrobenzyl cholate/P(MMA‐MMA), where the quantum yield of photoreaction is 0.2 and resist sensitivity is ca. 150 mJ/cm2 for a 1.5 μm film. The mode of resist behaviour on irradiation and development is also reported.
We have developed a two-component (resin-solution inhibitor) resist system having good photosensitivity in the 230–300 nm range. The resin is an optically transparent methyl methacrylate-methacrylic acid copolymer that is soluble in aqueous alkali. The second component is one of a family of o-nitrobenzyl carboxylates that are initially insoluble in the alkaline developer but are cleaved to soluble components upon irradiation. A number of o-nitrobenzyl alcohol esters have been prepared and examined for use in this two-component system. They have proven useful in the development of sensitive high-resolution short-wavelength photoresists which are described.
Copolymers of methyl methacrylate and acyloximino methacrylate esters have been evaluated as deep u.v. (200–250 nm) resists. Poly (methyl methacrylate‐co‐3‐methacryloyl‐oximino‐2‐butanone) has been found to be ∼5 times faster than PMMA at
λ>240 normalnm
and capable of submicron resolution. It has been found that the acetyl group of the 3‐oximino‐2‐butanone substituent is more effective than the related species containing t‐butyl, phenyl, or benzoyl groups in promoting polymer degradation. The copolymers have also been exposed to 20 kV electron beam radiation and have been found to be about as sensitive as PMMA
false(5×10−5C/cm2false)
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