A spin-on glass composition includes a solvent, about 3 to about 20
percent by weight of a porogen, and about 3 to about 20 percent by weight
of a silsesquioxane oligomer represented by formula (1), ##STR00001##
where, in the formula (1), Y.sub.1 and Y.sub.2 independently represent a
hydrolyzable alkoxy group, R represents a lower alkyl group, and n and m
independently represent an integer in a range of one to nine both
inclusive.