EUV lithography draws increasing attention and its expectation is rising. For instance, replacing a triple patterning with ArF immersion lithography to EUV single patterning may reduce 50% of cost and 25% of cycle time . At the same time, the importance of MPC (Mask Process Correction) is also growing   . It has become no longer possible to handle recent small and complex features using a rule-based bias approach. It is known that EUV lithography masks have a different structural stack so that “short range effect” of EB proximity effect is observed in mask writing . In this paper, we investigated the above short range effect through MPC model calibration. Mask data preparation step of EUV mask case is performed and the Turn-a-around (TAT) is compared with conventional DUV mask case.
Demand for mask process correction (MPC) is growing for leading-edge process nodes. MPC was originally intended to
correct CD linearity for narrow assist features difficult to resolve on a photomask without any correction, but it has been
extended to main features as process nodes have been shrinking.
As past papers have observed, MPC shows improvements in photomask fidelity. Using advanced shape and dose
corrections could give more improvements, especially at line-ends and corners. However, there is a dilemma on using
such advanced corrections on full mask level because it increases data volume and run time. In addition, write time on
variable shaped beam (VSB) writers also increases as the number of shots increases.
Optical proximity correction (OPC) care-area defines circuit design locations that require high mask fidelity under mask
writing process variations such as energy fluctuation. It is useful for MPC to switch its correction strategy and permit the
use of advanced mask correction techniques in those local care-areas where they provide maximum wafer benefits. The
use of mask correction techniques tailored to localized post-OPC design can result in similar desired level of data
volume, run time, and write time. ASML Brion and NCS have jointly developed a method to feedforward the care-area
information from Tachyon LMC to NDE-MPC to provide real benefit for improving both mask writing and wafer
This paper explains the detail of OPC care-area feedforwarding to MPC between ASML Brion and NCS, and shows the
results. In addition, improvements on mask and wafer simulations are also shown. The results indicate that the worst
process variation (PV) bands are reduced up to 37% for a 10nm tech node metal case.
Demand for mask process correction (MPC) is growing facing the 14nm era. We have developed model based MPC and can generate mask contours by using this mask process model. This mask process model consists of EB (development) and etch, which employs a threshold (level set) model and a variable bias model respectively. The model calibration tool accepts both CD measurement results and SEM images. The simulation can generate mask image (contour), runs with distributed computing resources, and has scalable performance. <p> </p>The contour simulation shows the accuracy of the MPC correction visually and provides comprehensive information about hot spots in mask fabrication. Additionally, it is possible to improve lithography simulation quality by providing a simulated mask contour.<p> </p> In this paper, accuracy and computational performance of mask process simulation are shown. The focus is on the difference between the calibration methods using CDs or images.
The Proximity Effect is a critical problem in EB Lithography which is used in Photomask writing. Proximity Effect
means that an electron shot by gun scatters by collided with resist molecule or substrate atom causes CD variation
depending on pattern density . Scattering by collision with resist molecule is called as "forward scattering", that
affects in dozens of nanometer range, and with substrate atom is called as "backward scattering, that affects
approximately 10 micrometer in 50keV acceleration voltage respectively.
In conventional Proximity Effect Correction (PEC) for mask writing, we don't need to think forward scattering effect.
However we should think about forward scattering because of smaller feature size.
We have proposed a PEC software product named "PATACON PC-Cluster", which can concern forward scattering
and calculate optimum dose modulation. In this communication, we explain the PEC processing throughput when the
that takes forward scattering into account. The key technique is to use different processing field size for forward
Additionally, the possibility is shown that effective PEC may be available by connecting forward scattering and
In this communication, we report on our experimental results from the research focused on the application of
the electron beam direct writing in the nanometer range. Special care is taken to analyze the forward scattering spread
and its influence on the pattering fidelity for patterns with the dimensions in the sub-10nm region. We model, simulate
and discuss several different cases of the strategy used in the pattern writing. The sub-pixel address grid is used and the
energy beam distribution is analyzed with 1Å resolution. The pre-compensated energy distribution is analyzed from its
slope cross-sectional point of view. Additionally, the field factor correction (FFC) dose compensation, the correctness of
the built-in FFC compensation for the sub-10nm regime, and its influence on the writing speed is discussed. We map the
pre-compensated energy distribution used for the pattern exposure to the developed resist profile modeled by the spline
approximation of the experimentally acquired resist contrast curve. The newly established development process for the
hydrogen silsesquioxane (HSQ) resist has been tested and applied in its optimal way. Successful sub-10nm patterning
with the dimension controllability better than 5% of the critical dimension (CD) was achieved. The experimental setup
use JBX-9300FS (used @ 100keV) as the exposure tool, and the HSQ (XR-1541) as the resist. The energy intensity distribution (EID) function used for the proximity effects compensation is calculated by CHARIOT simulation engine.
Proc. SPIE. 7271, Alternative Lithographic Technologies
KEYWORDS: Lithography, Electron beam lithography, Point spread functions, Scattering, Molecules, Silicon, Scanning electron microscopy, Data conversion, Electron beam direct write lithography, Semiconducting wafers
Electron Beam Direct Writing (EBDW) has been applied to various applications such as prototyping or small amount production of electronic devices. Originally, proximity effect in EBDW is considered as the problem of the background energy difference caused by the pattern density distribution. However, the critical dimensions of target patterns are getting smaller, we cannot ignore influences of the forward scattering. Theoretically, when the critical dimension is close to 3 or 4 times of forward scattering range, influence cannot be ignored. For example, in case of that corresponds, fabricating 20 nm dimension patterns by Nano Imprint Lithography (NIL) which is significant candidate of next generation lithography technology. Because it requires original dimension (1:1) mold. Therefore proximity effect correction (PEC) system which considers the forward scattering must be important.
We developed simulation-based proximity effect correction system combined with data format conversion, works on Linux PC cluster. And we exposed the patterns which are dose compensated by this system.
Firstly, we have speculated parameters about backward scattering parameters by exposing 100 nm line and space patterns. We got following parameters, beta (backward scattering range) = 32 um, eta (backward scattering coefficient) = 2.5.
Secondary, we have exposed Line and Space patterns whose dimensions are from 20 nm to 100 nm. We found that smaller and dense patterns have trend to be over exposed and bigger.
Experimental specification is following, EB Direct Writing system is JBX-9300FS (100keV acc. Voltage) by JEOL co.ltd, (Japan) , resist is HSQ (FOx 12) by Dow Corning co. (United States), substrate is Si.
Proc. SPIE. 6283, Photomask and Next-Generation Lithography Mask Technology XIII
KEYWORDS: Energy efficiency, Detection and tracking algorithms, Data modeling, Modulation, Scattering, Computing systems, Parallel processing, Control systems, Computer simulations, Electron beam direct write lithography
As pattern size becomes very small, it has been getting difficult to correct an EB proximity effect accurately. We have developed a new proximity effect correction which corrects dose by simulating the energy scattering. It can correct accurately in reasonable computing time. We will explain how to improve efficiency of energy deposit simulation and evaluate the algorithm in this paper.
As pattern size becomes very small, it has been getting difficult to correct an EB proximity effect accurately. We have developed a new proximity effect correction which corrects dose by simulating the pattern width. It can correct accurately a pattern of 100nm and below.