Manufacturing method of semiconductor device

A method for manufacturing a semiconductor device comprising the steps of:

• forming an insulating layer;
• etching the insulating layer to form a first region with a first thickness and a second region with a second thickness smaller than the first thickness;
• processing an edge portion of the first region into a curved shape with a radius of curvature of greater than or equal to 20 nm and less than or equal to 60 nm with rare gas plasma treatment;
• forming a semiconductor layer in contact with the first region at least including the edge portion processed into the curved shape and with at least part of the second region;
• forming a source electrode and a drain electrode electrically connected to the semiconductor layer;
• forming a gate insulating layer over the semiconductor layer;
• and
• forming a gate electrode over the gate insulating layer.

A method for manufacturing a semiconductor device comprising the steps of:

• forming an insulating layer;
• forming a metal layer over the insulating layer;
• forming a resist mask over the metal layer;
• patterning the metal layer with the resist mask;
• removing the resist mask after patterning the metal layer;
• etching the insulating layer with the patterned metal layer used as a mask to form a first region with a first thickness and a second region with a second thickness smaller than the first thickness, the first region being below the patterned metal layer;
• removing the patterned metal layer and processing an edge portion of the first region into a curved shape with a radius of curvature of greater than or equal to 20 nm and less than or equal to 60 nm, by dry etching on the patterned metal layer with one or both of a gas containing fluorine and a gas containing chlorine;
• forming a semiconductor layer in contact with the first region at least including the edge portion processed into the curved shape and with at least part of the second region;
• forming a source electrode and a drain electrode electrically connected to the semiconductor layer;
• forming a gate insulating layer over the semiconductor layer;
• and
• forming a gate electrode over the gate insulating layer.

A method for manufacturing a semiconductor device comprising the steps of:

• forming an insulating layer;
• forming a resist mask over the insulating layer;
• performing heat treatment on the resist mask to obtain a resist mask having a curved surface;
• etching the insulating layer with the resist mask having the curved surface to form a first region with a first thickness and a second region with a second thickness smaller than the first thickness, the first region being below the resist mask having the curved surface and having an edge portion processed into a curved shape with a radius of curvature of greater than or equal to 20 nm and less than or equal to 60 nm;
• forming a semiconductor layer in contact with the first region at least including the edge portion processed into the curved shape and with at least part of the second region;
• forming a source electrode and a drain electrode electrically connected to the semiconductor layer;
• forming a gate insulating layer over the semiconductor layer;
• and
• forming a gate electrode over the gate insulating layer.