Methods of forming trench/via features in an underlying structure using a process that includes a masking layer formed by a directed self-assembly process

A method, comprising:

• forming a hard mask layer above a layer of material;
• performing a directed self-assembly process to form a DSA masking layer above said hard mask layer, said DSA masking layer having a plurality of features that define a plurality of openings in said DSA masking layer;
• performing at least one process operation to remove at least one of said features of said DSA masking layer so as to thereby define a patterned DSA masking layer with a DSA masking pattern comprised of a plurality of openings in said DSA masking layer;
• performing at least one process operation to form a patterned transfer masking layer on said hard mask layer, said patterned transfer masking layer having a transfer masking pattern comprised of a plurality of features that define a plurality of openings in said transfer masking layer, wherein said transfer masking pattern is the inverse of said DSA masking pattern;
• and
• performing at least one etching process through said patterned transfer masking layer on at least said hard mask layer of material to form a plurality of trench/via features in said hard mask layer.

A method, comprising:

• forming a hard mask layer on a layer of material;
• forming a sacrificial layer of material on said hard mask layer;
• performing a directed self-assembly process to form a DSA masking layer above said sacrificial layer of material, said DSA masking layer being comprised of a plurality of features;
• performing at least one first etching process operation to remove at least one of said features of said DSA masking layer so as to thereby define a patterned DSA masking layer with a DSA masking pattern comprised of a plurality of openings in said DSA masking layer;
• performing at least one first etching process on said sacrificial layer through said patterned DSA masking layer to remove portions of said sacrificial layer of material and define a patterned layer of sacrificial material;
• forming a transfer layer of material above said patterned layer of sacrificial material;
• performing at least one process operation to planarize an upper surface of said transfer layer of material with an upper surface of said patterned layer of sacrificial material;
• performing at least one second etching process to remove said patterned sacrificial layer of material selectively relative to said transfer layer of material and to thereby define a patterned transfer masking layer having a transfer masking pattern comprised of a plurality of features that define a plurality of openings in said transfer masking layer, wherein said transfer masking pattern is the inverse of said DSA masking pattern;
• and
• performing at least one third etching process through said patterned transfer masking layer on at least said hard mask layer of material to form a plurality of trench/via features in said hard mask layer.