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.
We propose a method for the design of a complex optical element for use in lithographic system. It is based on optimization of the intensity point spread function of the lithographic projector. Increase in the depth of focus up to +/- 3micrometers in comparison with unaltered pupil demonstrated. This is achieved without introducing significant undesirable proximity effects, and in such a way, control over the sidelobe level is achieved. The solution is universal, without any reference to the projection of the particular mask layout. The analytical representation of the filter allows for explicit optimization process. Practical realization of the filter based on statistical approach is presented. Limitations of the proposed approach are discussed.
A method for the proximity effects correction in electron beam lithography for layouts with critical dimensions below 180 nm is proposed. A parallel processing system based on an artificial neural networks is suggested as a solution to the problem. The algorithm for the learning vector generation is based on a discrete iterative regularization. Several results of the correction process for different test layouts are presented. Error analysis of the error measure is presented. The difference between the target dose and the doses deposited in each exel after the correction process is smaller than 5 percent. As a hardware implementation of the real time proximity effects corrector the radial basis functions neural system is proposed. Simulations of the Gaussian synapse cell have been done. Results of our simulations assure that our neurocorrector can precompensate for one exel from the layout in less than 60 ns.