Photodefinable interlevel dielectrics

A method of selectively forming a patterned polymeric resin on a substrate comprising:

• (a) coating a substrate with a prepolymer which is an oligomeric resin comprising ethers of the oligomeric condensation product of 1 molar proportion of a dialdehyde, with a dialdehyde selected from the group consisting of OHC(CH2)nCHO, where n=0 or an integer from 1 to 6, cyclopentanedione, cyclohexanedione, phthalaldehyde, isophthalaldehyde, terephthalaldehyde, hexahydrophthalaldehyde, cycloheptanedialdehyde, hexahydroisophthalaldehyde, hexahydroterephthalaldehyde, and cyclooctanedialdehyde, with from about 3 to about 4 molar proportions of a phenol of structure R.sub.1 C.sub.6 H.sub.4 OH where R.sub.1 is hydrogen or an alkyl group containing from 1 to about 10 carbon atoms, and where the ether moiety is randomly selected from the group consisting of vinylbenzyl, alkyl moieties containing from 1 to 10 carbon atoms, cycloalkyl moieties of 5 to 10 carbon atoms, and benzyl, with the ratio of vinylbenzyl to other moieties being from 1:1 to about 6:1;
• (b) irradiating the prepolymer coating through a masking pattern so as to selectively crosslink portions of the coating being irradiated;
• (c) selectively dissolving the non-irradiated parts of the prepolymer coating;
• and
• (d) curing the patterned photochemically crosslinked portion of the prepolymer coating by heating said portion at a temperature greater than about 110.degree. C. for a time sufficient to further crosslink said coating and transform the prepolymer to an infusible glassy solid.