High speed e-beam writing for large area photonic nanostructures—a choice of parameters

This work is supported by Ministry of Science and Technology of China (2016YFA0301300), Guangzhou science and technology projects (201607010044, 201607020023), Natural Science Foundation of Guangdong (2016A030312012), National Natural Science Foundation of China (11674402), Open research project of the State Key Laboratory of Optoelectronic Materials and Technologies, Sun Yat-sen University of China (OEMT-2015-KF-12, OEMT-2015-KF-13), the Fundamental Research Funds for the Central Universities, EPSRC of U.K. under Grant EP/J01771X/1 (Structured Light) and the São Paulo Research Foundation (FAPESP #2016/05809-0). Kezheng Li is also supported by the aboard exchange scholar and international doctoral cooperative project of Sun Yat-sen university.Photonic nanostructures are used for many optical systems and applications. However, some high-end applications require the use of electron-beam lithography (EBL) to generate such nanostructures. An important technological bottleneck is the exposure time of the EBL systems, which can exceed 24 hours per 1 cm2. Here, we have developed a method based on a target function to systematically increase the writing speed of EBL. As an example, we use as the target function the fidelity of the Fourier Transform spectra of nanostructures that are designed for thin film light trapping applications, and optimize the full parameter space of the lithography process. Finally, we are able to reduce the exposure time by a factor of 5.5 without loss of photonic performance. We show that the performances of the fastest written structures are identical to the original ones within experimental error. As the target function can be varied according to different purposes, the method is also applicable to guided mode resonant grating and many other areas. These findings contribute to the advancement of EBL and point towards making the technology more attractive for commercial applications.Publisher PDFPeer reviewe