Patterning process of a semiconductor structure with a wet strippable middle layer

A lithography method, comprising:

• forming an under layer of a polymeric material on a substrate;
• forming a silicon-containing middle layer on the under layer, wherein the silicon-containing middle layer has a silicon concentration in weight percentage less than 20% and is wet strippable;
• forming a patterned photosensitive layer on the silicon-containing middle layer;
• performing a first etching process to transfer a pattern of the patterned photosensitive layer to the silicon-containing middle layer;
• performing a second etching process to transfer the pattern to the under layer using a mixture of sulfur-containing gas and oxygen (O2);
• performing a plasma treatment to the silicon-containing middle layer using a gas containing nitrogen (N2) and hydrogen (H2);
• and
• performing a wet stripping process to remove the silicon-containing middle layer and the under layer.

A lithography method, comprising:

• forming a silicon-containing middle layer on a semiconductor substrate;
• and
• performing a baking process to the silicon-containing middle layer, wherein the silicon-containing middle layer has a silicon concentration in weight percentage less than 20% and is wet strippable, wherein the silicon-containing middle layer includes a chemical structure as
• wherein O and Si represent oxygen and silicon, respectively;
• a, b and c represent weight percentage of O—Si groups, respectively;
• X represents a first organic group that provides cross-linking sites;
• D represents an aromatic group designed to tune extinction coefficient and index of refraction;
• and
• R represents a second organic group that enhances etching resistance and adhesion of the photosensitive layer.