By copolymerization of 2-(2-diazo-3-oxo-3-(4-dimethylaminophenyl)propionyloxy)ethyl methacrylate (DODMAPPEA), methyl methacrylate (MMA) and 2-hydroxyethyl methacrylate (HEMA), a photoactive polymer for negative-tone resist is synthesized and its photolithographic properties are investigated. Since the maximum-absorption wavelength of the photoactive monomer DODMAPPEA is 356nm and it still has a comparatively large absorption at 365nm (I-line), the copolymer poly(DODMAPPEA -co-MMA-co-HEMA) is anticipated to be used in
I-line single component negative-tone resist. Upon irradiaton, the diazoketo groups which are in the side chains of
the copolymers undergo the wolff rearrangement, affording ketenes that react with hydroxyl to provide cross-linking
photoproducts and a negative image is obtained. Besides that, cross-linking agent hexamethoxymethylmelamine (HMMM) is added to the resist system and high sensitivity is expected. This kind of copolymer has great value in I-line non-CARs, TFT-LCD and IC discrete devices processing and the anti-dry etching ability is enhanced by the introduction of the benzene ring. In addition, this copolymer still has potential value in Ultra-violate lithographic plate.
A kind of photoactive polymer with diazoketo groups in its side chains has been reported in SPIE and other related
papers, and this photoactive polymer can be used in deep UV non-CARs (non-chemically amplified resists) system.
Based on the work above, a series of novel photoactive monomers with substituents like phenyl, p-methylphenyl,
p-methoxyphenyl, p-dimethylaminophenyl on the end of the molecule are designed and synthesized. By changing their
substituents, the maximum-absorption wavelength of the photoactive monomers has been moved to 356nm, and it still
has comparatively large absorption at 365nm (I-line). A series of photoactive polymers were obtained by polymerizing
the monomer with methyl methacrylate and 2-hydroxyethyl methacrylate together. Upon irradiaton in the waveleng of
365nm, the diazoketo groups which are in the side chains of the photoactive polymers undergo the wolff rearrangment
and afford ketens that react with water to provide base-soluble photoproducts. Applying this kind of photoactive
polymers to non-CARs, a positive image can be obtained. This kind of photoactive polymers have great value in I-line
non-CARs, TFT-LCD and IC discrete devices processing. And its anti-dry etching ability is enhanced by the introduction
of the benzene ring.