Devices fabricated by photolithography have some smoothing effects such as corner rounding and loss of small geometric features. For some devices, such as Waveguide Bragg Gratings (WBG), it is critical to predict these photolithography effects since the performance of these devices can be very sensitive to small changes in geometry.
Lumerical offers some capabilities in photolithography simulation. Our model is mainly based on Fraunhofer diffraction at the photomask, where the mask is assumed to be a very thin metal without plasmonic or polarization effects. It allows users to simulate the photolithography effects by defining some key inputs,
- Photomask (the desired geometries)
- Projection NA
- Spatial coherence factor
- Resist threshold
which represent some key elements in a photolithography simulation, such as the illumination optics, photomask, projection optics, and photoresist.
The following steps are used too run a photolithography simulation using Lumerical software
- Create/import the structure, which will be used as the photomask
- Input the photolithography parameters
- Run the script file for photolithography simulation and generate the new structure
The recorded videos below have some more information and instructions on setting up a photolithography simulation and using a litho-simulated device to run an FDTD simulation. The video pages also contain a link to download all the associated files.
Subwavelength Grating Bandstructure