Metaatom choice considering process variation

Metalenses are flat lenses constructed from thin films using CMOS based manufacturing that operate using phase effects to manipulate light. Metalenses are used in visible and infrared wavelengths for applications ranging from infrared facial recognition for cell phones to telescopic imaging of astronomic objects. Metalenses are useful due to their thin form factor, a few microns thick, which reduces weight and volume for applications such as cell phones and AR/VR/MR headsets. Metalenses are designed with meta-atoms. Meta-atoms are subwavelength features that vary in size and sometimes pitch to manipulate the phase of an incident optical wavefront. Simple meta-atoms include square and circular XY plane shapes. Complex meta-atoms include XY plane shapes with many corners or features such as crosses or stars. Simply shaped meta-atoms tend to perform well for monochromatic lens purposes. However, when multiple operating wavelengths (achromatic designs) are desired, simple meta-atoms generally demonstrate poor performance for at least some of the desired wavelengths. Complex meta-atoms may improve achromatic performance but may be more susceptible to manufacturing variations. Understanding metalens performance response to allowed process variation ranges can aid meta-atom choice. This study will simulate several meta-atoms through manufacturing variations and compare their performance robustness. Process models will be used to vary process conditions such as etch time, photoresist thickness, or patterned material thickness. The study finds that complex meta-atoms demonstrate degraded performance compared to simple circular meta-atoms after simulated manufacturing.