Silicon is one of the most common materials used in optical micro-electro-mechanical systems (MEMS). For the
optical applications the surface quality plays a vital role in the performance of elements, so the control of surface
morphology, such as surface smoothing, is very important to produce optical MEMS elements with high reliability and
high quality. The most commonly used etching methods such as reactive ion etching (RIE) always left damage layer on
the etched surface leaving the surface with high roughness. In this paper 2.54GHz micro wave excited plasma was used
to treat the silicon surface, and the different etching conditions of CF4 and O2 mixture were investigated. The surface
quality after this down-stream plasma treatment was studied by atomic force microscopy (AFM) measurement.
We present the fabrication of a kind of hexagonal and triangular cavity mold, which can cast Polymethyl Methacrylate
(PMMA) resonators and couplers. The mold is designed on (111) silicon wafer according to its crystal structure and
anisotropic etching properties in the etchant of ethylene diamine, pyrocatechol, and water (EDP/EPW), forming
sidewalls by six {110} crystal surfaces, which are perpendicular to the (111) plane and constitute precise hexagons and
triangles. The RIE-ICP etching is used to define the depth of the triangle and hexagonal cavities, and the following EDP
etching smoothes the sidewalls of cavities. Only high temperature EDP etching is proved to be able to get smooth
sidewalls. Before etching, the wafer is aligned to the right crystal orientation by pre-etched marks. The etched results of
different geometrical cavities are analyzed and discussed based on the crystal structure.
We report small reflecting mirrors with high reflectance, which are fabricated by using square quartz chips. These quartz mirrors are going to be used in the construction of a miniaturized Fabry Perot Interferometer (FPI) with a commercial ring type PZT from Fuji Ceramic Company. The dimension of quartz substrates is 10×10mm with a thickness of 1mm. The high reflectance of mirrors is obtained by depositing multi-layer thin films on quartz substrates. Magnetron RF sputtering machine is used to ensure that the thickness of dielectric coatings can be precisely controlled. These mirrors are measured by SEM and AFM and the reflectance is detected by a visible light spectrometer. The maximum reflectance of these mirrors is about 99.4% on the designed wavelength 553nm. A small FPI set up by this kind of mirror can have a theoretical finesse of 522, and if a PZT resonator with a length of 7.22mm is used, the resolution of this small interferometer can reach 4.06×10-5nm, in another word, the resolving power is 1.36×107.
Bulk silicon wet etching can be used to fabricate silicon gratings. Wet etching depends on the anisotropic property of monocrystalline silicon. Blazed gratings for different spectral ranges can be fabricated by this method, and facets of grooves are formed by crystallographic planes of the monocrystalline silicon wafer. We develop a method to fabricate blazed gratings using deflecting crystal orientation (111) silicon wafers. The topographies of the samples are measured by SEM and atomic force microscopy (AFM), and the results indicate that the samples have grooves of good uniformity and facets of excellent optical quality.
A modulated continues wave argon ion laser has been used to get lamb waves in silicon membrane. In this report, the basic principle of conversation from optics to thermal then acoustic waves was deduced. The experimental set-up, the analysis of the results and the possible way to obtain a given mode of lamb wave were described.
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