After an analysis of the factors that causes critical dimension (CD) variation in the lithography process of the LLE
(Litho-Litho-Etch) double-patterning technology that employs the freezing process, an optimum process for freezing the
resist patterns to reduce the CD variation, which occurs after the 2<sup>nd</sup> litho process, was achieved. By optimizing the track
parameters of freezing process, CD variation is likely to be reduced not only in the 1<sup>st</sup> resist pattern but also in the 2<sup>nd</sup>
The optimum conditions were adopted to form patterns of 40 nm resist lines and spaces in the evaluations conducted in
this paper. The formation result showed improvement of 3 sigma of the within-wafer CD uniformity of both the 1<sup>st</sup> resist
pattern and the 2<sup>nd</sup> resist pattern, by about 13% and 46% respectively.
Printing random Contact Holes (C/H) is one of the most difficult tasks in current low-k1 lithography. Different
approaches have been proposed and demonstrated successfully. One approach is the use of extensive Resolution
Enhancement Technique such as sub-resolution assisting features, focus drilling and interference mapping lithography in
combination with strong off-axis illumination. These techniques often lead to enhanced complexity at the OPC and mask
making side. In order to keep the complexity low, soft illumination modes have been proposed like Soft-Annular (bull'seye)
and Soft-Quasar type illumination . It has been shown that the minimum k<sub>1</sub> for the latter route is k<sub>1</sub>=0.41 using
experimental results up to 0.93 NA. In this paper we demonstrate that the latter route can be extended to 45nm C/H at a
minimum pitch of 120nm when using 1.35 NA. In order to achieve this we additionally applied a CD sizing technique to
create the very small C/H.