Method for reducing surface defects on patterned resist features

A method for reducing surface defects in a patterned resist feature, the method comprising:

• providing a substrate with a patterned resist feature having a first dimension and containing surface defects comprising line edge roughness or resist residue defects with convex and concave regions;
• applying an acid solution to the patterned resist feature to form a surface acid layer on the patterned resist feature;
• heat-treating the patterned resist feature, the heat-treating causing acid concentration in the convex regions and acid dispersion in the concave regions;
• and
• exposing the heat-treated patterned resist feature to a developing solution to preferentially remove resist material from the convex regions and form a trimmed patterned resist feature with reduced surface defects, the trimmed patterned resist feature having a trimmed dimension smaller that the first dimension.

A method for trimming a patterned resist feature, the method comprising:

• providing a substrate with a patterned resist feature, the patterned resist feature being characterized by a critical dimension (CD);
• applying an acid solution to the patterned resist feature to form a surface acid layer on the patterned resist feature;
• and
• exposing the patterned resist feature to a developing solution to preferentially remove resist material from the surface acid layer.