다중혈관 관상동맥 환자에서 y-문합을 이용하여 양쪽 내흉동맥만을 사용한 우회술의 조기 성적

Introductory Fourier transform spectroscopy

High aspect ratio (HAR) silicon etch is reviewed, including commonly used terms, history, main applications, different technological methods, critical challenges, and main theories of the technologies. Chronologically, HAR silicon etch has been conducted using wet etch in solution, reactive ion etch (RIE) in low density plasma, single-step etch at cryogenic conditions in inductively coupled plasma (ICP) combined with RIE, time-multiplexed deep silicon etch in ICP-RIE configuration reactor, and single-step etch in high density plasma at room or near room temperature. Key specifications are HAR, high etch rate, good trench sidewall profile with smooth surface, low aspect ratio dependent etch, and low etch loading effects. Till now, time-multiplexed etch process is a popular industrial practice but the intrinsic scalloped profile of a time-multiplexed etch process, resulting from alternating between passivation and etch, poses a challenge. Previously, HAR silicon etch was an application associated primarily with microelectromechanical systems. In recent years, through-silicon-via (TSV) etch applications for three-dimensional integrated circuit stacking technology has spurred research and development of this enabling technology. This potential large scale application requires HAR etch with high and stable throughput, controllable profile and surface properties, and low costs.

High aspect ratio silicon etch: A review

An intensive study has been performed to understand and tune deep reactive ion etch (DRIE) processes for optimum results with respect to the silicon etch rate, etch profile and mask etch selectivity (in order of priority) using state-of-the-art dual power source DRIE equipment. The
research compares pulsed-mode DRIE processes (e.g. Bosch technique) and mixed-mode DRIE processes (e.g. cryostat technique). In both techniques, an inhibitor is added to
fluorine-based plasma to achieve directional etching, which is formed out of an oxide-forming (O2) or a fluorocarbon (FC) gas (C4F8 or CHF3). The inhibitor can be introduced together with the etch gas, which is named a mixed-mode DRIE process, or the inhibitor can be added in a
time-multiplexed manner, which will be termed a pulsed-mode DRIE process. Next, the most convenient mode of operation found in this study is highlighted including some remarks to
ensure proper etching (i.e. step synchronization in pulsed-mode operation and heat control of the wafer). First of all, for the fabrication ......
 Enjoy reading . Henri Jansen 18 June 2008

https://iopscience.iop.org/article/10.1088/0960-1317/19/3/033001/pdf

Black silicon method X: a review on high speed and selective plasma etching of silicon with profile control: an in-depth comparison between Bosch and cryostat DRIE processes as a roadmap to next generation equipment

We experimentally demonstrate the high-sensitivity optical monitoring of a micromechanical resonator and its cooling by active control. Coating a low-loss mirror upon the resonator, we have built an optomechanical sensor based on a very high-finesse cavity (30 000). We have measured the thermal noise of the resonator with a quantum-limited sensitivity at the 10(-19) m/sqrt[Hz] level, and cooled the resonator down to 5 K by a cold-damping technique. Applications of our setup range from quantum optics experiments to the experimental demonstration of the quantum ground state of a macroscopic mechanical resonator.

High-sensitivity optical monitoring of a micromechanical resonator with a quantum-limited optomechanical sensor

Advanced etching of silicon based on deep reactive ion etching for silicon high aspect ratio microstructures and three-dimensional micro- and nanostructures

Vertical Bragg grating mirrors are realized by the anisotropic etching of Si using deep reactive ion etching (DRIE), thus producing multiple vertical interfaces between Si and air. The Bragg mirrors are used to realize two optical filter configurations. The first is a tunable Fabry-Peacuterot cavity composed of two mirrors, where tuning is achieved by moving one of the mirrors using silicon-on-insulator (SOI) electrostatic microelectromechanical system (MEMS) actuation. The second is a drop filter, where a tilted Bragg mirror acts as a wavelength selective reflector. The enhanced etching process involving a mix of cryogenic and Bosch DRIE processes is presented. The realized structures, fabrication process, as well as measured performance are also presented

Free-Space Tunable and Drop Optical Filters Using Vertical Bragg Mirrors on Silicon

Miniaturized optical benches process free-space light propagating in-plane with respect to the substrate and have a large variety of applications, including the coupling of light through an optical fiber. High coupling efficiency is usually obtained using assembled micro-optical parts, which considerably increase the system cost and integration effort. In this work, we report a high coupling efficiency, monolithically integrated silicon micromirror with controlled three-dimensional (3D) curvature that is capable of manipulating optical beams propagating in the plane of the silicon substrate. Based on our theoretical modeling, a spherical micromirror with a microscale radius of curvature as small as twice the Gaussian beam Rayleigh range provides a 100% coupling efficiency over a relatively long optical path range. Introducing dimensionless parameters facilitates the elucidation of the role of key design parameters, including the mirror's radii of curvature, independent of the wavelength. A micromachining method is presented for fabricating the 3D micromirror using fluorinated gas plasmas. The measured coupling efficiency was greater than 50% over a 200-μm optical path, compared to less than 10% afforded by a conventional flat micromirror, which was in good agreement with the model. Using the 3D micromirror, an optical cavity was formed with a round-trip diffraction loss of less than 0.4%, resulting in one order of magnitude enhancement in the measured quality factor. A nearly 100% coupling was also estimated when matching the sagittal and tangential radii of curvature of the presented micromirror’s surface. The reported class of 3D micromirrors may be an advantageous replacement for the optical lenses usually assembled in silicon photonics and optical benches by transforming them into real 3D monolithic systems while achieving wideband high coupling efficiency over submillimeter distances. Scientists from France and Egypt have developed spherical micromirrors that can couple optical fibres with almost 100% efficiency. Yasser Sabry and colleagues fabricated their monolithically-integrated mirrors in a silicon platform by a technique incorporating fluorinated gas plasmas and then coating the etched surface with a 100-nm-thick layer of aluminium. The resulting broadband mirrors had curvatures of 30–200 μm and exhibited reflectivities of >92% in the visible and near-infrared spectral regimes. The combination of high reflectivity and almost perfect coupling to optical fibres allows for the creation of miniature integrated optical cavities with a round trip transmission of better than 99.6% multiplied by the mirror reflectivity and an overall Q-factor of around 3000. This performance is an order of magnitude better than that achieved using flat mirrors.

/pdf/silicon-micromirrors-with-three-dimensional-curvature-56dofbmm59.pdf

Silicon micromirrors with three-dimensional curvature enabling lensless efficient coupling of free-space light

In this paper, a novel Mach-Zhender interferometer for spectroscopy applications is presented. The interferometer is fully integrated on an silicon on insulator wafer using deep reactive ion etching technology, the moving mirror is coupled to a comb drive microelectromechanical systems (MEMS) actuator. Optical propagation inside the MEMS structure is modeled and the diffraction effect is studied. Practical results show the complementary nature of the two outputs and a resolution of 25 nm at 1.55 μm is reported when using the interferometer as an Fourier transform infrared spectrometer. The complementary nature of the interferometer can be further used for source noise reduction.

Fully Integrated Mach-Zhender MEMS Interferometer With Two Complementary Outputs

A new beam splitter [1] is proposed to realize a completely integrated Michelson interferometer, where a single medium interface (Si/Air) is used for optical beam splitting. This offers a stable splitting ratio over a very wide spectral range. Using this technique on SOI wafers, with a moving mirror, a highly robust and tunable interferometer is fabricated. The tunable interferometer is tested experimentally by measuring optical interference versus mirror displacement.

Bassam Saadany

Papers

Advanced etching of silicon based on deep reactive ion etching for silicon high aspect ratio microstructures and three-dimensional micro- and nanostructures

Free-Space Tunable and Drop Optical Filters Using Vertical Bragg Mirrors on Silicon

Silicon micromirrors with three-dimensional curvature enabling lensless efficient coupling of free-space light

Fully Integrated Mach-Zhender MEMS Interferometer With Two Complementary Outputs

MEMS tunable Michelson interferometer with robust beam splitting architecture