Specific Process Knowledge/Lithography/EBeamLithography: Difference between revisions
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Even though the electron beam diameter is only a few nm, the feature and pitch resolution in resist is limited by scattering of the electrons in the resist and substrate material. Forward scattering is scattering within the resist layer and it will have a broadening effect of the beam. The magnitude of this effect depends on acceleration voltage, resist composition and thickness of the resist layer. Back scattering is caused by electron-matter interaction in the substrate itself and electrons that are scattered back into the resist layer will provide a secondary (unwanted) exposure of the resist. The scattering distance is highly dependent on acceleration voltage and the substrate material. For a silicon substrate exposed at 100 kV the back scatter range is up to 30 µm and hence it is essential for many designs to account for this effect using PEC software. At DTU Nanolab we primarily use Beamer from GenISys for PEC. The PEC process will result in a dose modulated design file where the relative exposure dose has been modulated to ensure that all parts of the design receives a uniform dose regardless of whether a design feature is in a sparsely populated or a heavily populated area of the design. | Even though the electron beam diameter is only a few nm, the feature and pitch resolution in resist is limited by scattering of the electrons in the resist and substrate material. Forward scattering is scattering within the resist layer and it will have a broadening effect of the beam. The magnitude of this effect depends on acceleration voltage, resist composition and thickness of the resist layer. Back scattering is caused by electron-matter interaction in the substrate itself and electrons that are scattered back into the resist layer will provide a secondary (unwanted) exposure of the resist. The scattering distance is highly dependent on acceleration voltage and the substrate material. For a silicon substrate exposed at 100 kV the back scatter range is up to 30 µm and hence it is essential for many designs to account for this effect using PEC software. At DTU Nanolab we primarily use Beamer from GenISys for PEC. The PEC process will result in a dose modulated design file where the relative exposure dose has been modulated to ensure that all parts of the design receives a uniform dose regardless of whether a design feature is in a sparsely populated or a heavily populated area of the design. | ||
For more information on PEC and use of Beamer please refer to our dedicated [[/BEAMER|Beamer page.]] | For more information on PEC and use of Beamer please refer to our dedicated [[/BEAMER|Beamer & PEC page.]] | ||
= Charging of non-conductive substrates= | = Charging of non-conductive substrates= | ||