Double patterning techniques are one of the dominant method to achieve the 32 nm node and beyond and Litho-Litho-
Etch (LLE) process is a strong candidate for double patterning method. Contact hole resolution is limited by the low
image contrast using dark field masks. Cross-line contact hole process using LLE process is applicable to image fined
contact holes. Contact hole patterns are formed by first line and space patterns and orthogonal second line and space
patterns. Furthermore LLE process flow should be simple as possible as it can for cost reduction. Thus LLE process
without freezing process is ideal one.
In this paper, we examine the process performance using latest material for freezing free LLE process, exposure tool
and novel coater/developer system. The latest resist materials can form cross-line contact hole with good pattern fidelity
and CD uniformity. It will be shown that novel coater/developer hardware is effective on enhancement of lithography
performance like CD control and defect control toward double Patterning technology for 193-nm immersion lithography.
Double patterning with 193nm immersion lithography becomes to most promising candidate for 32nm half pitch node
and possibly below 32nm half pitch. Several double patterning methods have been suggested such as LELE (Litho-Etch
-Litho-Etch), LLE (Litho-Litho-Etch) and Spacer defined process, however, LLE process is pointed out as low cost
double patterning technique because of its simplicity. But LLE process needs new method to maintain 1st lithography
pattern and additional freezing processes have been suggested
In SPIE Advanced Lithography 2009, freezing free "Posi/Posi" process was introduced as candidate for LLE process.
This is LLE process that uses two different positive tone photoresists without freezing process. The resist for 2nd
lithography contains a specific solvent to prevent the mixing of two resists and there is an activation energy gap
between 1st and 2nd resists to maintain 1st lithography pattern. The double patterning can be successfully processed by
these specific resists without freezing process.
In this study, the performance of this freezing free "Posi/Posi" process is investigated for pitch splitting pattern using
1.35 NA exposure tool. The imaging results including CD control capability, and etching results are collected for 32nm
half pitch and below. Additionally the two-dimensional pattern imaging is also obtained for 76nm minimum pitch.
Double patterning with 193nm immersion lithography is generally recognized as a candidate for 32nm hp node and
possibly beyond with recent progress. LLE (Litho-Litho-Etch) could be good candidate for double patterning method
because of its simplicity but the good solution hasn't been proposed yet.
In last year, freezing free Posi/Nega process was introduced as candidate for LLE process. But that had an issue that the
resolution of negative tone resist was little bit poor for 1L/3S pattern compared with positive tone. Thus it's better to
choose positive tone as 2nd resist for this reason. And then Posi/Posi process without any freezing material has been
investigated and successfully established to image double patterning.
Posi/Posi process without any freezing material has successfully achieved to image below 32nm hp. Furthermore contact
hole imaging was succeeded by using cross-line method and image reverse method.
We present the productivity study of freezing free Posi/Posi process on Cross-lined contact hole, critical resolution for
pitch splitting and reverse imaging for contact hole.
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