| AVS 60th International Symposium and Exhibition | |
| Nanometer-scale Science and Technology | Wednesday Sessions |
| Session NS+BI+EM-WeA |
| Session: | Nanopatterning and Nanolithography |
| Presenter: | J. Laukkanen, University of Eastern Finland |
| Authors: | J. Laukkanen, University of Eastern Finland S. Tonchev, CNRS, France Y. Jourlin, CNRS, France S. Reynaud, CNRS, France H. Hirshy, Cardiff University, UK S.G. Scholz, Cardiff University, UK O. Parriaux, CNRS, France |
| Correspondent: | Click to Email |
We demonstrate a production chain for making submicron gratings on the wall of a cylinder. Gratings of this kind can be used, for example, in rotation sensors. We have converted a conventional 2D interference lithography setup into 3D setup by using a circularly symmetrical planar high index phase mask [1]. With this method, a lot smaller period is achieved than with CNC tools, which are commonly used for similar structures.
A planar phase mask was made in CVD-grown silicon nitride (Si3N4) on top of a quartz mask plate using electron beam lithography and reactive ion etching. Silicon nitride was chosen as a grating material because of its high refractive index and therefore ability to cancel zeroth order transmission [2]. In photolithography, a specially made glass cylinder was used as a substrate and it was coated with photoresist by dip coating. The phase mask was illuminated with radially polarized light in oblique incidence creating an interferogram on the resist coated wall of a cylinder. The produced stitchingless grating lines were over one millimeter long.
In order to be able to mass produce these cylindrical gratings a nickel mold was done using electroforming like in LIGA process [3]. The nickel mold can then be used in injection molding. With this fabrication method, we can control the exact number of lines and spaces and have a constant period over the whole round of the cylinder, which is crucial for high precision rotation sensors.
[1] S. Tonchev, Y. Jourlin, C. Veillas, S. Reynaud, N. Lyndin, O. Parriaux, J. Laukkanen, and M. Kuittinen,” Subwavelength cylindrical grating by holistic phase-mask coordinate transform,” Optics Express, 20, 7946-7953 (2012).
[2] E. Gamet, A. V. Tishchenko, and O. Parriaux, “Cancellation of the zeroth order in a phase mask by mode interplay in a high index contrast binary grating,” Applied Optics, 46, 6719–6726 (2007).
[3] W. Bacher, W. Menz, J. Mohr, "The LIGA technique and its potential for microsystems-a survey," Industrial Electronics, IEEE Transactions on, 42, 431 (1995).