Two level light sensitive system with radiation de-polymerisable coat - with light sensitive top coat forming mask, giving resist with good contrast

摘要

Light-sensitive object with 2 levels has (a) a substrate; (b) a radiation-depolymerisable coating; and (c) a light-sensitive top coat. Coating (b) contains a copolymer (I) of ca. 10-90 mole-% maleimide units, ca. 10-90 mole-% units of a styrene cpd., i.e. styrene, alpha-methylstyrene, 4-(1-5C alkyl)-styrene or 2,4-di-(1-5C alkyl)-styrene, or an (alkyl)acrylonitrile or alkyl (alkyl)acrylate monomer of the formula CH2=CRaM (Ra = H or 1-5C alkyl; M = CN or -CO2Rb; Rb = 1-5C alkyl); and 0-90 mole-% N-(1-5C alkyl)-maleimide units. (I) has a mol.wt. of ca. 5000-2000000. Coating (c) contains a water-insol. binder resin (II), which dissolves or swells in aq. alkali, in an amt. giving a homogeneous mixt. and enough light-sensitive component(s) (III) to impart photosensitivity, (III) being an o-quinone diazide or a combination of a cpd. forming a strong acid on exposure and a cpd. contg. acid-hydrolysable C-O-C linkage(s). The material may also have (d) a barrier layer between (b) and (c), to prevent these mixing. (d) pref. consists of a polysulphone polymer, PVA or glass. (I) has a mol.wt. of ca. 5000-100000, esp. 10000-90000. (II) is a novolak or polyvinyl phenol; and (III) a naphthoquinone-(1,2)-diazide-4- or -5-sulphonyl chloride condensed with a hydroxybenzophenone or hydroxyalkylphenol. In particular, (II) is a cresol-HCHO novolak and (III) naphtho-quinone-(1,2)-diazide-4- or -5-sulphonyl chloride condensed with a trihydroxybenzophenone. Coating (c) may also contain a colourant, streaking inhibitor, plasticiser, adhesion promoter, accelerator, solvent, crosslinker and/or surfactant. The solvent pref. is propylene glycol monoalkyl ether acetate and/or propylene glycol monoalkyl ether. USE/ADVANTAGE - The photoresist gives good image contrast. It is useful Si, Al, polymer resin, (doped) SiO2, Si3N4, Ta, Cu, polysilocone, poly-Si, ceramics, Al/Cu mixts., GaAs and/or gp. III/V cpd. substrates.