Method for forming semiconductor structure

A method for forming a semiconductor structure, comprising:

• forming a material layer over a substrate;
• forming a bottom layer over the material layer;
• forming a silicon-containing middle layer over the bottom layer, wherein the middle layer comprises:
• a carbon backbone having a first segment, a second segment and a third segment;
• a first side chain bonded to the first segment, wherein the first side chain is a siloxane-based group;
• a second side chain bonded to the second segment, wherein the second side chain is a crosslinkable group;
• and
• a third side chain bonded to the third segment, wherein the third side chain is a hydrophilic group;
• forming a top layer over the silicon-containing middle layer;
• removing a portion of the top layer to form a patterned top layer;
• removing a portion of the silicon-containing middle layer by using the patterned top layer as a mask to form a patterned silicon-containing middle layer;
• removing a portion of the bottom layer by using the patterned silicon-containing middle layer as a mask to form a patterned bottom layer;
• and
• removing the patterned silicon-containing middle layer by using a base solution, wherein the middle layer is soluble in the base solution.

A method for forming a semiconductor device structure, comprising:

• forming a bottom layer over a substrate;
• forming a silicon-containing middle layer over the bottom layer, wherein the silicon-containing middle layer comprises a carbon backbone and a first side chain bonded to the carbon backbone, and the first side chain has a hydrophilic group;
• patterning the silicon-containing middle layer to form a patterned silicon-containing middle layer;
• patterning the bottom layer by using the patterned silicon-containing middle layer as a mask to form a patterned bottom layer;
• and
• removing the patterned silicon-containing middle layer by using a first etching solution, wherein the patterned silicon-containing middle layer is soluble in the first etching solution by the hydrophilic group;
• and
• removing the patterned bottom layer by using a second etching solution.