Patterning method

A patterning method, comprising:

• providing a substrate having a hard mask layer formed thereon, wherein an array region and peripheral region are defined on the substrate;
• forming a first material layer on the hard mask layer;
• patterning the first material layer to form first array patterns in the array region and first peripheral patterns in the peripheral region;
• performing a first self-aligned reverse patterning (SARP) process to transfer the first array pattern into first spacer patterns;
• forming a planarization layer completely covering the first spacer patterns and the first peripheral patterns;
• forming a second material layer on the planarization layer;
• patterning the second material layer to form second array patterns in the array region and second peripheral patterns in the peripheral region;
• performing a second self-aligned reverse patterning (SARP) process to transfer the second array pattern into second spacer patterns, wherein the second spacer patterns partially vertically overlap the first spacer patterns, wherein the second peripheral patterns do not vertically overlap the first peripheral pattern;
• using the second spacer patterns and the second peripheral patterns as an etching mask to etch the planarization layer until portions of the first spacer patterns not overlapped by the second spacer patterns and the first peripheral patterns are exposed;
• removing the exposed portions of the first spacer patterns to form third array patterns;
• and
• using the third array patterns, the second peripheral patterns and the first peripheral patterns as an etching mask to etch the hard mask layer thereby forming a patterned hard mask layer.