A new approach to determine development model parameters by employing the isotropy of the development process

- Fitting of contrast curves leads to ambiguity of resist development parameters.
- Lateral resist development is used to improve parameters values.
- Test pattern consists of lines applied with varying fore- and background doses.
- More data points compared to a contrast curve are incorporated.
- Variability of parameter values is decreased.

There is an increasing demand for high-resolution three-dimensional (3D) structures as for instance micro-optical lenses or blazed gratings. The fabrication of these requires electron beam lithography for patterning. 3D structure shapes can be predicted by using simulation tools to reduce cost and development effort. For this, different resist models have been presented. However, currently available methods to determine the corresponding parameters are either time-consuming and, thus, costly or lead to ambiguous parameter values. This can lead to inaccurate simulation results in particular for 3D structures realised by greyscale lithography. In this paper, we introduce a novel and straightforward approach to determine improved resist model parameters. For this purpose, lateral resist erosion due to the isotropy of the development process is employed. By the example of the development model according to C. Mack for negative tone resists it is shown that our newly introduced test pattern is suitable to adjust model parameters.

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