FAQs E-Beam Resists

1. What are e-beam resists composed of, and how do they work?

E-beam resists (electron beam resists) are designed for electron beam and deep UV applications for the fabrication of highly integrated circuits, mainly for mask fabrication. They are employed in electron beam direct writing and multilayer processes.
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2. For how long are e-beam resists stable, and what are the optimal storage conditions?

PMMA- and copolymer e-beam resists are not light-sensitive in the visible UV range, they consequently don’t react to light exposure (no safe yellow light required) and are substantially less temperature-
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3. What is the optimal pre-treatment of substrates for e-beam resist application

If new and clean substrates (wafers) are used, a bake at approximately 200 °C for a few minutes is sufficient in order to dry the substrates, which however then have to be processed quickly.
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4. How high is the adhesion strength of e-beam resists to different wafers?

Adhesion between substrate and coating is a sensitive feature of a resists, which is also true for e-beam resists. PMMA- and copolymer resists are however significantly less prone for adhesion problems than e-
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5. How are e-beam resists exposed, and how can the optimum exposure dose be determined?

With the use of very short-wavelength electrons for resist exposure, an excellent resolution of up to 2 nm can be achieved (single spot exposure). The exposure is performed with standard equipments for electron beam lithography and is based on the principle of direct writing or raster scan shaped beam procedures.
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6. Which developers are optimal for e-beam resists, and how do factors like developer concentration and temperature influence the result?

During development, a positive tone resist film is patterned by a removal of exposed areas, while unexposed areas are removed when negative resists are used. To achieve reproducible results,
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7. How can e-beam resist films be removed again?

For the removal of all e-beam resist coatings baked at lower temperatures (softbake), polar solvents may be used such as e.g. the recommended thinner AR 300-12 or AR 600-01, 600-07,
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8. Which resolutions do e-beam resists achieve?

With respect to the achievable resolution, purely academic resolution values and industrially utilisable values represent two quite different aspects. Theoretically, resolutions of 2 nm are possible (single electron spot)
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9. How high is the plasma etch resistance of e-beam resists?

Electron beam resists of the AR 6000 and AR 7000 production line display quite different etch resistance features in dry etch processes such as e.g. argon sputter and CF 4 . Novolak-
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10. How high is the etch resistance of e-beam resists in the presence of strong acids?

Concentrated oxidising acids (sulphuric acid, nitric acid, aqua regia 1) , piranha 2) ) attack resist films already at room temperatures and are often used as remover for persistent resist structures.
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