Resist underlayer composition and process of producing integrated circuit devices using the same

A resist underlayer composition, comprising:

• a solvent;
• and
• an organosilane condensation polymerization product, the organosilane condensation polymerization product including about 40 to about 80 mol % of a structural unit represented by the following Chemical Formula 1,
• wherein, in Chemical Formula 1,
• ORG is selected from the group of:
• a C6 to C30 functional group including a substituted or unsubstituted aromatic ring,
• a C1 to C12 alkyl group, and
• —Y—{Si(OR)3}a, wherein Y is a linear or branched substituted or unsubstituted C1 to C20 alkylene group, a C1 to C20 alkylene group including, in a main chain of the alkylene group, a group selected from the group of an alkenylene group, an alkynylene group, an arylene group, a heterocyclic group, a urea group, an isocyanurate group, and a combination thereof, or a substituted or unsubstituted C6 to C30 arylene group, R is a C1 to C6 alkyl group, and a is 1 or 2, and
• Z is selected from the group of hydrogen and a C1 to C6 alkyl group.