Sub-40-nm half-pitch double patterning with resist freezing process

Double patterning based on existing ArF lithography technology is one of the most promising candidates for sub-40nm half-pitch devices. Several variation of double patterning processes have been reported by research groups, including a dual-trench process (litho-etch-litho-etch) and a dual-line process (litho-litho-etch). Between these, the dual-line process is attracting the most attention because it is a simple process that achieves high throughput. However, there is concern that the second lithographic process damages the first litho patterns in the dual-line process. Therefore, new technology must be developed to keep the configuration of first litho patterns during the second lithographic step for this patterning process to be practical. Recently, we have succeeded in forming sub-40nm half-pitch litho patterns by the introduction of a new "freezing" step to this process. This step involves covering the first litho pattern with chemical freezing materials to prevent damage by the second litho pattern creating a dual-line process composed of litho-"freezing"-litho-etch processes. In this paper, the details of dual-line process including a "freezing" step are explained and sub-40nm half-pitch litho patterns by this process are shown.