Wet process for developing styrene polymer resists for submicron lithography

A process for preparing negative resists on a substrate which includes bonding polymer resins to a siliceous substrate and lithographically preparing a patterned resist in said substrate, which process comprises:

• A. forming an article consisting essentially of:
• (1) a siliceous substrate;
• (2) a layer of silane on a surface of said substrate, which silane is:
• R.sup.i --(O).sub.0-1 --(R.sup.ii).sub.0-1 --Si(R.sup.iii).sub.3 or the hydrolysis products thereof and wherein one or more of the R.sup.iii groups are replaced by OH;
• where:
• R.sup.i is acryloyl, methacryloyl, or vinyl, and when R.sup.i is vinyl, then the moiety "(O).sub.0-1 " is absent;
• R.sup.ii is alkylene having 2-6 carbon atoms, or R.sup.iv --NH--R.sup.v where R.sup.iv is hydroxyalkylene having 2-6 carbon atoms and R.sup.v is alkylene having 2-6 carbon atoms, and when R.sup.i is vinyl, R.sup.ii is absent;
• R.sup.iii is halo, or alkoxy having 1-6 carbon atoms, or alkoxyalkoxy having at least 3-6 carbon atoms, or alkanoyloxy having a total of 2-5 carbon atoms, or an alkyl having 1-6 carbon atoms, where the number of said alkyl groups present is not more than 2, and mixtures thereof;
• and
• (3) a polymer resin overlaying said silane, which resin affords free radicals when subjected to radiation and is selected from the group consisting of:
• (a) polystyrene;
• (b) halogenated polystryrene, and
• (c) substituted styrene polymer, where the substituted monomer has at least one substituent selected from the group consisting of alkyl having 1-4 carbon atoms, halo, haloalkyl having 1-4 carbon atoms and at least one halo;
• and
• (d) mixtures thereof;
• B. applying said layer of silane to the siliceous substrate, heating the silane-coated surface of the substrate to form a bond between the silane and the substrate, then applying the polymer resin overlay to the silane coated surface, and irradiating the polymer-overlaid surface (1) to generate free radicals at the polymer-silane interface so as to form a bond between the silane and the polymer overlay, so that a substantially unitary article is obtained, and (2) to form a negative pattern image therein;
• and
• C. developing said image by:
• (i) dissolving away unexposed polymer with a developer solvent, and
• (ii) multiply rinsing said wet developed resist with solvent/nonsolvent rinses, such that a series on consecutive rinses utilizing sucessively weaker solvents is employed, and maintaining the resist in a wetted condition throughout the consecutive rinses, so as to substantially eliminate any snakiness of the developed resist pattern image and to shrink any swelling of the developed resist profile, so that the developed resist image is substantially the same shape and height as the initial exposed image prior to development,
• where said developer solvent//rinse nonsolvents combination are selected from the following schedule, wherein (d/s) is developer solvent and (r//ns) represents the rinse nonsolvent series which beings with (a) or a mixture of (a) and (b) which is rich in (a) and progresses toward only (b), and where the series of rinses encompasses a minimum of two rinses:
• ______________________________________ Schedule 2 ______________________________________ A. (d/s) R.sub.2 --(OCH.sub.2 CH.sub.2).sub.m --O--H (r/ns) (a) R.sub.5 --(OCH.sub.2 --CH.sub.2).sub.m --OH (b) R--OH B. (d/s) R.sub.7 --(OCH.sub.2 CH.sub.2).sub.m --O--R.sub.7 (r/ns) (a) R.sub.5 --(OCH.sub.2 CH.sub.2).sub.m --OH (b) R--OH C. (d/s) R--CO--(OCH.sub.2 CH.sub.2).sub.p --O--(OC).sub.0-1 --R (r/ns) (a) R.sub.5 --(OCH.sub.2 CH.sub.2).sub.m --OH (b) R--OH D. (d/s) R.sub.2 --(OCH.sub.2 CH.sub.2).sub.m --OH, mixed with R.sub.2 OH (r/ns) (a) R.sub.2 --OH (b) R--OH ______________________________________
• where:
• R is alkyl having 1-4 carbon atoms,
• R.sub.2 is alkyl having 4-8 carbon atoms,
• R.sub.5 is H, methyl or ethyl,
• R.sub.7 is alkyl having 1-8 carbon atoms,
• m is an integer equal to 1-4, and
• p is an integer equal to 1-2.