Grafting design for pattern post-treatment in semiconductor manufacturing

A method for lithography patterning, comprising:

• providing a patterned photoresist layer over a material layer over a substrate, the patterned photoresist layer having an opening;
• coating a grafting solution in the opening, the grafting solution comprising a grafting compound and a solvent, the grafting compound comprising a grafting unit and a linking unit that is chemically bonded to an ester side chain of a polymer backbone, the linking unit comprising an alkyl segment having 1 to 10 carbon atoms, the grafting unit being attachable to the patterned photoresist layer and comprising at least two heteroatoms bridged by a cycloalkyl group and immediately bonded to the cycloalkyl group, the at least two heteroatoms comprising a nitrogen atom and the grafting unit being chemically bonded to the linking unit by way of the nitrogen atom;
• baking the grafting solution at a temperature ranging from 20° C. to 180° C., thereby forming a second layer over a surface of the patterned photoresist layer by attaching a first portion of the grafting compound to the surface of the patterned photoresist layer;
• removing a second portion of the grafting compound that is not attached to the patterned photoresist layer, resulting in a pattern having the patterned photoresist layer and the second layer, a portion of the second layer being on sidewalls of the opening;
• etching the material layer using the pattern as an etch mask;
• and
• removing the pattern.

A method for lithography patterning, comprising:

• providing a patterned photoresist layer over a material layer over a substrate, the patterned photoresist layer having an opening;
• coating a grafting solution in the opening, the grafting solution comprising a grafting compound and a solvent, the grafting compound comprising a grafting unit and a linking unit that is chemically bonded to a polymer backbone, the linking unit comprising an alkyl segment having 1 to 10 carbon atoms, the grafting unit comprising a cycloalkyl group directly bonded to and between two nitrogen (N) atoms, the grafting unit being chemically bonded to the linking unit by way of one of the two nitrogen (N) atoms, and the grafting unit being attachable to the patterned photoresist layer;
• baking the grafting solution at a first temperature for a duration, thereby attaching a first portion of the grafting compound to the patterned photoresist layer, wherein the first temperature and the duration are selected based on a target thickness of the first portion of the grafting compound;
• removing a second portion of the grafting compound that is not attached to the patterned photoresist layer, resulting in a pattern having the patterned photoresist layer and the first portion of the grafting compound;
• and
• etching the material layer using the pattern as an etch mask.