Total process function in electron beam lithography

• A three-step method to calculate the total process function in e-beam lithography is proposed.
• 1st step: Monte Carlo simulation provides the energy deposition of a point beam.
• 2nd and 3rd step: 2d-convolutions include beam blur and process effects.
• Convolution kernel parameters are obtained by fitting to experimental data.
• The method is validated with measured total process functions from literature.

Proximity effect correction software in electron beam lithography needs the pattern layout and the total process function (TPF) as an input. This function is determined by electron scattering in resist layer and substrate, the beam blur and diffusion effects during development and post processing. Measuring the TPF is difficult. A three-step method is therefore suggested to calculate the TPF for thin resist layers: Monte Carlo simulation of electron scattering followed by 2d-convolutions with the beam blur and a diffusion function. The convolution algorithm will be described in detail. Experimental data taken from literature are used to verify this calculation method. The method is also useful to assess the quality of the lithographic process.

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