Method of etching a semiconductor device by etching initial mask structures at a region having an extension direction different from the extension direction of the initial mask structures

A method for fabricating a semiconductor structure, comprising:

• providing a material layer over a substrate,
• forming a plurality of initial mask structures on the material layer, wherein the plurality of initial mask structures extends along a length direction and is arranged along a width direction, wherein the substrate includes:
• a first region including a central region and edge regions sandwiching the central region, all extending along the width direction of the initial mask structures, and
• a second region extending along the length direction of the initial mask structures;
• removing portions of the plurality of initial mask structures at the edge regions of the first region and exposing edge-region-openings extending along the width direction of the initial mask structures over a surface of the material layer, thereby leaving a plurality of mask structures, wherein
• the plurality of initial mask structures are etched at the edge regions along an extending direction in the width direction, which is perpendicular to an extending direction of the plurality of initial mask structures along the length direction to keep distances between adjacent initial mask structures maintained along the width direction;
• using the plurality of mask structures as a mask, forming a plurality of material-layer structures over the substrate by:
• removing portions of the material layer from the edge-region-openings along the width direction of the mask structures, and
• simultaneously removing another portions of the material layer between adjacent mask structures along the length direction of the mask structures;
• and
• after forming the plurality of material-layer structures, further comprising:
• removing portions of the plurality of material-layer structures from the central region along the width direction, and
• simultaneously removing portions of the plurality of material-layer structures from the second region along the length direction.