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In this work, we demonstrate a full process for fabricating high aspect ratio diffraction optics for extreme ultraviolet lithography. The transmissive optics consists in nanometer scale tungsten patterns standing on flat, ultrathin (100 nm) and highly transparent (>85% at 13.5 nm) silicon membranes (diameter of 1 mm). These tungsten patterns were achieved using an innovative pseudo-Bosch etching process based on an inductively coupled plasma ignited in a mixture of SF6 and C4F8. Circular ultra-thin Si membranes were fabricated through a state-of-the-art method using direct-bonding with thermal difference. The silicon membranes were sputter-coated with a few hundred nanometers (100–300 nm) of stress-controlled tungsten and a very thin layer of chromium. Nanoscale features were written in a thin resist layer by electron beam lithography and transferred onto tungsten by plasma etching of both the chromium hard mask and the tungsten layer. This etching process results in highly anisotropic tungsten features at room temperature. The homogeneity and the aspect ratio of the advanced pattern transfer on the membranes were characterized with scanning electron microscopy after focus ion beam milling. An aspect ratio of about 6 for 35 nm size pattern is successfully obtained on a 1 mm diameter 100 nm thick Si membrane. The whole fabrication process is fully compatible with standard industrial semiconductor technology. [ABSTRACT FROM AUTHOR]

The CaxBa1[?]xNb2O6 (CBN-x) optical ridge waveguides for electro-optic phase modulation were fabricated on a silicon substrate. The method of waveguide fabrication presented here resulted in a device with a high-quality guiding layer, i.e. with better crystallinity over 140 nm grains of preferred (0 0 1) orientation, high transmission exceeding 94% for 1550 nm wavelength and improved electro-optic coefficient, over 15 pm V[?]1. Pulsed laser deposition of CBN film on a pre-patterned 10 um thick layer of silicon dioxide allows the spatial separation of the guiding CBN layer thus enabling optical signal coupling. A contact layer is introduced on both sides of the waveguides in order to enable electro-optic response testing. [ABSTRACT FROM AUTHOR]