| Summary: | 碩士 === 國立交通大學 === 工學院半導體材料與製程設備學程 === 106 === Double patterning technology (DPT) is en extended optical photolithography technology for half pitch patterns of sub-30 nm nodes. DPT can be regarded as a bridging technology between Immersion and EUV lithographies. Integrated with self-alignement processes, self-aligned double patterning (SADP) technique can reduce process failure and continue the Moore’s Law. It is essential to properly select the hard mask core material for SADP process. In general, severe pattern deformation (wiggling) occurs easily for patterns with a size smaller than 30 nm, thus preventing correct pattern transfer. In this study, we used amorphous carbon as the core film material, and found that pattern wiggling was a result of serious chemical side-etch during the dry etch process. We evaluated the extent of pattern wiggling in terms of the ratio of the line width roughness to the line edge roughness (LWR/LER). In order to increase the etch selectivity and reduce the etch rate of the amorphous carbon core film, the film requires a higher composition of diamond like bonds (i.e., sp3 bonding). We optimized the core etch process to maximize the sp3 /sp2 ratio so that the LWR/LER can be as low as 1.8 nm/2.4 nm, and the process has been successfully implemented in the 28nm technology.
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