Gap-filling method

A method comprising:

• (a) providing a semiconductor device substrate having a relief image on a surface of the substrate, the relief image having a plurality of gaps to be filled;
• (b) applying a coating composition to the relief image and filling the gaps to provide a coating layer, wherein the coating composition comprises (i) a polyarylene oligomer comprising as polymerized units one or more first monomers having two or more cyclopentadienone moieties and one or more second monomers having an aromatic moiety and two or more alkynyl moieties;
• wherein the polyarylene oligomer has a Mw of 1000 to 6000 Da, a polydispersity index (PDI) of 1 to 2, and a molar ratio of total first monomers to total second monomers of 1:>1;
• and (ii) one or more organic solvents;
• (c) curing the coating layer to form a polyarylene film;
• (d) disposing a layer of an inorganic hardmask on the polyarylene film;
• (e) disposing a layer of a photoresist on the inorganic hardmask layer;
• (f) patterning the photoresist layer;
• (g) transferring the pattern from the photoresist layer to the polyarylene film;
• and (h) then transferring the pattern to the semiconductor device substrate.