Pattern forming method

A pattern forming method comprising:

• forming a first mask film above a processing target;
• forming an opening pattern in a predetermined area of the first mask film;
• conformally forming a second mask film of a material different from that of the first mask film above the processing target above which the opening pattern is formed;
• performing etch-back of the second mask films until an upper surface of the first mask film is exposed so that the second mask film remains on a side surface of the first mask film;
• forming a third mask film formed of the same material as the first mask film above the processing target after the second mask film remains on the side surface of the first mask film;
• planarizing an upper surface of the third mask film by using the second mask film as a stopper;
• forming line-and-space-shaped first core patterns, that are made of a first core film and in which widths of line patterns have smaller than a width of the second mask film remaining on the side surface of the first mask film, in an area other than an area forming the opening pattern of the processing target after the third mask film is planarized;
• conformally forming a first sidewall film above the processing target above which the first core patterns are formed;
• performing etch-back of the first sidewall film so that upper surfaces of the first core patterns are exposed;
• forming first sidewall patterns made of the first sidewall film by removing the first core patterns;
• forming mask patterns by etching the first mask film and the third mask film using the first sidewall patterns;
• and
• patterning the processing target by using the second mask film and the mask patterns as masks.

A pattern forming method comprising:

• forming a core film above a processing target;
• forming core patterns including line-and-space shaped patterns by processing the core film;
• conformally forming a first sidewall film above the processing target above which the core patterns are formed;
• performing etch-back of the first sidewall film so that upper surfaces of the core patterns are exposed;
• forming first sidewall patterns made of the first sidewall film above the processing target by removing the core patterns;
• conformally forming a mask film above the processing target above which the first sidewall patterns are formed, so as to embed portions between the adjacent first sidewall patterns formed in an area forming the line-and-space shaped patterns;
• performing etch-back of the mask film until upper surfaces of the first sidewall patterns are exposed so that the mask film formed on side surfaces of the first sidewall patterns of end portions without being embedded between the adjacent first sidewall patterns remains;
• forming mask patterns that include line-and-space shaped first patterns corresponding to the mask film embedded between the adjacent first sidewall patterns and a second pattern corresponding to the mask film remaining on the side surfaces of the first sidewall patterns of the end portions, by removing the first sidewall patterns;
• and
• patterning the processing target by using the mask patterns.