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Parameter Optimization of Multi-Level Diffraction Gratings
Matějka, Milan ; Kolařík, Vladimír ; Horáček, Miroslav ; Král, Stanislav
Originally, the e-beam lithography (EBL) is a technique for creating high-resolution black and white masks for the optical lithography. Multi-level relief structures can be also prepared using EBL patterning. Their preparation is based on the image patterning with a gradient of exposure doses. Large-area multi-level structures can be effectively prepared using the electron beam pattern generator with a variable shaped beam. We present several writing strategies. Basically, the main writing strategy uses one stamp (i.e. one elementary exposure of the shaped electron beam) per one elementary area with the same exposure dose. This simple approach is fast and flexible, however it does not guarantee optimal results. The main problem is an imperfection of the stamps (size, shape, and homogeneity). Advanced algorithms are based on multiple\nexposure of the same elementary area, the total local exposure dose is a sum of several different elementary exposures (stamps). Using these algorithms, a smoother surface of the structure can be achieved. On the other hand, the writing speed is considerably decreased. Tradeoff between the achieved parameters and the writing speed is discussed for selected set of writing strategy algorithms.
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E-beam pattern generator BS600 and technology zoom
Kolařík, Vladimír ; Horáček, Miroslav ; Matějka, František ; Matějka, Milan ; Urbánek, Michal ; Krátký, Stanislav ; Král, Stanislav ; Bok, Jan
This contribution deals with an electron beam pattern generator (ELG) working with a rectangular shape variable size electron beam originally developed at Institute of Scientific Instruments (ISI), later on commercialized as a BS600 series by former company Tesla, and recently upgraded by ISI cooperating with several partners. The key issue of this paper is a recently developed exposure mode which is called Technology Zoom (TZ mode) since its original concept until the recent progress. This ELG operating in the TZ mode provides three main advantages when compared to the standard exposure mode: higher exposure speed due to increased beam current density; finer stamp size adjustment and sharper stamp shape due to the stronger size reduction of the shaping aperture. Further, we discussed also some drawbacks and practical issues of the TZ mode. And finally, we summarize some results on real exposure examples. The new exposure mode (together with other recent upgrades) makes the BS600 pattern generator very useful for the nanotechnology patterning tasks and challenges.
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