Method for Forming Semiconductor Device Structure with Fine Line Pitch and Fine End-To-End Space

A method comprising:

• forming a hard mask layer over a dielectric layer;
• forming a bottom layer, a middle layer, and a top layer on the hard mask layer;
• patterning the top layer to form a patterned top layer;
• performing a plasma process on the patterned top layer and the middle layer, wherein the plasma process is performed using a mixed gas comprising hydrogen gas (H2), and wherein performing the plasma process comprises:
• reducing a line width roughness (LWR) of the patterned top layer;
• patterning the middle layer to form a patterned middle layer;
• and
• depositing a protection film on sidewalls of the patterned top layer and sidewalls of the patterned middle layer;
• patterning the bottom layer by using the patterned middle layer as a mask to form a patterned bottom layer;
• and
• patterning the hard mask layer by using the patterned top layer, the patterned middle layer, and the patterned bottom layer as a mask to form a patterned hard mask layer.

A method comprising:

• forming a dielectric layer over a substrate;
• forming a hard mask layer over the dielectric layer;
• forming a bottom layer, a middle layer, and a top layer on the hard mask layer;
• patterning the top layer to form a patterned top layer;
• performing a plasma process on the patterned top layer and the middle layer, wherein the plasma process is performed using a mixed gas comprising hydrogen gas (H2), and wherein performing the plasma process comprises:
• etching the middle layer to form a patterned middle layer;
• increasing an etching selectivity of the middle layer relative to the top layer by controlling a flow rate of the hydrogen gas (H2);
• and
• depositing a protection film on sidewalls of the patterned top layer and sidewalls of the patterned middle layer;
• etching the bottom layer by using the patterned middle layer as a mask to form a patterned bottom layer;
• and
• etching the hard mask layer by using the patterned top layer, the patterned middle layer, and the patterned bottom layer as a mask to form a patterned hard mask layer.