Method and Structure for Mandrel and Spacer Patterning

A method, comprising:

• forming first mandrels and second mandrels over a substrate, wherein each of the first and second mandrels has a loop structure;
• forming first spacers on sidewalls of the first mandrels and second spacers on sidewalls of the second mandrels, wherein each of the first and second spacers has an inner loop structure inside the respective mandrel and an outer loop structure outside the respective mandrel, wherein each of the inner and outer loop structures has two curvy ends connected by two walls;
• removing the first and second mandrels;
• and
• partially removing walls of each second spacer, resulting in two adjacent wall segments from each second spacer, wherein the two adjacent wall segments are not connected to remaining portions of the respective second spacer.

A method, comprising:

• forming first lines and second lines over a substrate by a first patterning process;
• forming first spacers on sidewalls of the first lines and second spacers on sidewalls of the second lines, each of the first and second spacers having a loop structure with two curvy portions connected by two straight portions;
• removing the first and second lines by an etching process;
• and
• performing a cut process, thereby removing the curvy portions from each of the first spacers without removing the curvy portions from any of the second spacers.