Due to the importance of errors in lithography scanners, masks, and computational lithography in low-k1 lithography,
application software is used to simultaneously reduce them. We have developed “Masters” application software, which is
all-inclusive term of critical dimension uniformity (CDU), optical proximity effect (OPE), overlay (OVL), lens control
(LNS), tool maintenance (MNT) and source optimization for wide process window (SO), for compensation of the issues
on imaging and overlay.
In this paper, we describe the more accurate and comprehensive solution of OPE-Master, LNS-Master and SO-Master
with functions of analysis, prediction and optimization. Since OPE-Master employed a rigorous simulation, a root cause
of error in OPE matching was found out. From the analysis, we had developed an additional knob and evaluated a proof-of-
concept for the improvement. Influence of thermal issues on projection optics is evaluated with a heating prediction,
and an optimization with scanner knobs on an optimized source taken into account mask 3D effect for obtaining usable
process window. Furthermore, we discuss a possibility of correction for reticle expansion by heating comparing
calculation and measurement.
In this study, we investigate what kind of mask blank material is optimum for the resolution
enhancement techniques (RET) of leading-edge ArF lithography. The source mask optimization (SMO) is
one of the promising RET in 2Xnm-node and it optimizes mask pattern and illumination intensity
distribution simultaneously. We combine SMO with the blank material optimization and explore the truly
This study consists of three phases. In the first phase, we evaluate maximum exposure latitude
(Max.E.L.) and mask error enhancement factor (MEEF) of fictitious materials that have typical real (n)
and imaginary (k) value of refractive index by 3D rigorous simulator as the basic analysis. The simulation
result shows that there are two high lithographic performance combinations of n and k values; one is
low-n/high-k and the other is high-n/low-k.
In the second phase, we select actual blank material that has similar optical parameters with the
result of the previous phase. The lithographic performance of the selected material is investigated more
precisely. We find that the candidate material has good lithographic performance at the semi-dense pitch.
In the final phase, we create a test mask of this candidate blank material and verify simulation
result by experimental assessment. The exposures are performed on NA1.30 immersion scanner (Nikon
NSR-S610C). The experimental result shows the improvement of Max.E.L. in head to head type pattern.
This study will discuss the potential of blank material tuning for the ArF lithography extension.
To improve lithography performance, resolution enhancement technique (RET) such as source mask
optimization (SMO) will be applied to 22 nm node and beyond. We examine if lithography performance is improved
by altering mask 3D topography. In this paper, we report that we have confirmed what topography is effective for
lithography performance improvement in the dense region of 22nm technology node. Since shadowing effect is
strong at the dense region, we focus on sidewall angle that decreases shadowing effect. As a basic analysis, we
evaluate maximum exposure latitude (EL) and mask error enhancement factor (MEEF) of mask 3D topographic
patterns that have various sidewall angles by 3D rigorous simulator. This result shows the increasing of maximum
exposure latitude when changing sidewall angle. As a next step, we fabricate a test mask which has optimized
sidewall angle and the exposure is performed on NA1.30 immersion scanner (Nikon NSR-S610C). Then we compare
wafer printing results and simulation results. These results induce that the optimization of mask 3D topography has a
potential to improve lithographic performance.