Patent ID: 8445592

Claim:
A method of etching a substrate, comprising: preparing a solution comprising an azido-functionalized random graft copolymer by: reacting a reaction mixture comprising p-chloromethylstyrene monomers to form a p-chloromethylstyrene homopolymer comprising chloromethyl moieties and repeating units derived from p-chloromethylstyrene; reacting the p-chloromethylstyrene homopolymer with one or more oligomers or polymers of poly(ethylene oxide) to form a graft copolymer comprising chloromethyl moieties, wherein the poly(ethylene oxide) has only one nucleophilic end; and reacting the graft copolymer comprising chloromethyl moieties with an azide compound to displace chlorine atoms of the chloromethyl moieties to form azidomethyl moieties on the graft copolymer, wherein the azide compound is selected from the group consisting of sodium azide and R(N 3 ) x , where R is a metal atom other than sodium, hydrogen or ammonium, and x is greater than zero; applying the solution comprising the azido-functionalized random graft copolymer to a floor of a trench within a substrate, the trench having sidewalls, a width, and a length; crosslinking the azido-functionalized random graft copolymer; forming a polymer material comprising a poly(styrene-b-ethylene oxide) block copolymer within the trench; annealing the polymer material to form a material comprising self-assembled polymer domains registered to the sidewalls and extending the length of the trench; selectively removing a first polymer domain to form an etch mask comprising an array of openings separated by a second polymer domain; and etching the substrate through the openings of the etch mask.