Open AccessSelf-organized formation of a Blazed-grating-like structure on Si(100) induced by focused ion-beam scanning
Author(s) -
Yong Qing Fu,
Ngoi Kok Ann Bryan,
Wei Zhou
Publication year - 2004
Publication title -
optics express
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.394
H-Index - 271
ISSN - 1094-4087
DOI - 10.1364/opex.12.000227
Subject(s) - materials science , optics , diffraction efficiency , ion beam , scanning electron microscope , focused ion beam , wafer , grating , diffraction , optoelectronics , raster scan , silicon , blazed grating , diffraction grating , ion , beam (structure) , chemistry , physics , organic chemistry , composite material
A new one-step method, which has been named self-organized formation, for microfabrication of blazed-grating-like structures after bombardment with a focused ion beam (FIB) with an ion energy of 50 keV and a beam current of 0.5 nA is presented. The structure is fabricated by the FIB by raster scanning (not by patterned scanning) upon a substrate of a silicon wafer, Si(100), with total scanning time of 14 min. With this method the parameters are unchanged during the whole process, unlike for the point-by-point direct writing technique, in which the exposure intensity or the electron- or ion-beam dose is changed for each point. The surface roughness of the structure, Ra, is 2.5 nm over an area of 1 mum X 1 mum. To evaluate the performance of this method we carried out a simulation, using the PCGrate program. The simulated diffraction efficiency, of diffraction order -3 working in the reflection mode, can be as much as 79.1% for the violet wavelength of 400 nm. Using a He-Ne laser as the light source produced a measured diffraction efficiency of the order of -2 of 70.4%, which is near the simulated value of 76.9% at a wavelength of 600 nm. The depth and the period of the structure can be controlled by process parameters of the FIB, such as ion energy and ion flux.