Mechanisms for forming patterns

A method for forming patterns in a semiconductor device, comprising:

• providing a substrate and a patterning-target layer over the substrate;
• forming one or more mandrel patterns over the patterning-target layer;
• forming spacers adjacent to sidewalls of the mandrel patterns;
• removing the mandrel patterns to expose the spacers;
• forming an opening in a resist layer by removing a first spacer and removing a portion of the resist layer that covers the first spacer;
• forming a patch pattern over a second spacer and aligned with the opening;
• etching the patterning-target layer using the patch pattern and the second spacer as mask elements to form final patterns;
• and
• removing the patch pattern and the second spacer to expose the final patterns,
• wherein a first final pattern is located at a distance in a range from about (n+0.3) times of a pitch to about (n+0.8) times of the pitch away from an adjacent second final pattern, wherein n is an integer number, and wherein the pitch is a distance between two adjacent spacers plus a width of a spacer.

A method for forming patterns in a semiconductor device, comprising:

• providing a substrate and a patterning-target layer over the substrate;
• forming one or more mandrel patterns over the patterning-target layer;
• forming spacers adjacent to sidewalls of the mandrel patterns;
• forming an opening in a resist layer by removing a first mandrel pattern and a first spacer and removing a portion of the resist layer that covers the first spacer and the first spacer;
• forming a patch pattern over a second spacer and aligned with the opening;
• forming one or more patch spacers adjacent to sidewalls of the patch pattern;
• etching the patterning-target layer using the one or more patch spacers and the second spacer as mask elements to form final patterns;
• and
• removing the one or more patch spacers and the second spacer to expose the final patterns,
• wherein a first final pattern is located at a distance in a range from about (n+0.3) times of a pitch to about (n+0.8) times of the pitch away from an adjacent second final pattern, wherein n is an integer number, and wherein the pitch is a distance between two adjacent spacers plus a width of a spacer.