Papers by Keyword: Wet Etching

Abstract: Fabricating silicon-beam through the wet etching has been developed for many years, there are a lot of advantages during the wet etching, low cost, easy to obtain and so on. However the design and fabrication of silicon-beam with polygon section has been confined during the process of wet etching; In order to fabricate more kinds of silicon-beam with the advantages of the wet etching, a novel method to fabricate silicon-beam with polygon section is proposed. The fabricating process has been designed by taking advantage of the protection effect of the SiO₂ layer.

Abstract: Simplex wet etching method to fabricate silicon-beam has limited the categories of silicon-beam, it has confined the design and fabrication of silicon-beam with polygon section. Moreover, due to the side-etching of sidewalls and arris during the process of wet etching, the sections of the fabricated silicon-beam are not identical, which will induce the mechanics characters of silicon-beam to be altered, depressing the quality of silicon-beam; In order to avoid the shortages above, a novel method to fabricate silicon-beam with polygon section based on thermal oxidation layer technique is proposed, thermal oxidation SiO₂ layer is utilized as the protection layer of the sidewalls of the silicon-beam instead of the mask layer as usual for the first time. Combining the wet etching technique with the thermal oxidation technique innovatively, several varieties of silicon-beam with polygon section, which can hardly be obtained only by the use of wet etching technique, can be manufactured, respectively. Based on such an innovative method, this paper proposes and develops five varieties of silicon-beam with novel structure by means of adjustable mask layer, extending the application field of wet etching. The subsequent fabrication experiment of silicon-beam with hexagonal section has been taken as an example to validate the technique principle. The dimension parameters of silicon-beam have been tested precisely and the arris angle error between the theoretic value and the experimental measurement is less than 1.5%; The SEM photos with the amplifier of 100 and 250 have been obtained through HITACHI S-4800 field emission scanning electron microscope (FE-SEM), the SEM results have demonstrated the clear sidewall arris without undercut. Through this fabrication method, the sidewall arris of silicon-beam can be maintained due to the protection layer of thermal oxidation SiO₂. In this manner, the arris disfigurement of the silicon-beam decreases dramatically, the process of etching can be controlled precisely, and the quality of the silicon-beam has been improved greatly.

Abstract: The micro/nanocomposite structure on silicon surface was formed by a simple 2-step chemical etching with a potassium hydroxide anisotropic etching and a stain etching in order to obtain a superhydrophobic silicon surface. Micro-sized pyramids structure was formed in a mixture of 3 wt.% potassium hydroxide with 8 vol.% isopropyl alcohol solution at 80C for 60 min. The formation of the nanosized structure was performed by stain etching at room temperature using nitric acid (HNO₃) / hydrofluoric acid (HF) aqueous solutions. The silicon surface had the superhydrophobic surface. The contact angle was measured and the maximum value was 167^o for the condition of second etching with HF : HNO₃ : H₂O = 11 : 1 : 3.

Abstract: In the process of deep etching of silicon, the metal film or the oxide film served as silicon protective layer needed to be etched before using plasma etching technology. In order to solve the etch rates variance of different aperture sizes and different pitchs periodic patterns, by controlling the water bath temperature and etching time, the etch rates of different aperture sizes and different pitchs periodic patterns at 50 degree centigrade had been developed. Also we contrasted the etching results at different bath temperatures and got the controllable and suitable wet etching bath temperature 50 degree centigrade. At last, the paper further explores the effects of feature size and the wet etching bath temperature on etch rate.

Abstract: We investigated the wet-etching properties of SiCN films using chemical agents. Our results show that sodium hydroxide, potassium hydroxide and phosphoric acid etch SiCN films, while hydrochloric acid, sulfuric acid, acetic acid, ammonium chloride and sodium chloride cannot etch SiCN films.

Abstract: In this paper, a simple and facile technique for manufacturing glass-based microfluidic chips was developed. Instead of using expensive dry etching technology, the standard UV lithography and wet chemical etching technique was used to fabricate microchannels on a K9 glass substrate. The fabrication process of microfluidic chip including vacuum evaporation, annealing, lithography, and BHF (HF-NH4F-H2O) wet etching were investigated. Through series experiments, we found that anneal was the critical factor for chip quality. As a representative example, a microfluidic channel with 20 m of depth, and 80 m of width was successfully prepared, and the channel surfaces are quite smooth. These results present a simple, low cost, flexible and easy way to fabricate glass-based microfluidic chips.

Abstract: In order to understand dislocations in GaN grown on silicon using metal organic chemical vapor deposition (MOCVD), two samples with different film thickness were grown. The distribution of dislocations and its influence on epitaxial layer were studied. Wet etching can effectively reveal the dislocations in GaN, and the hexagonal etch pits are the emergence of dislocations. After etching in the aqueous KOH: H2O =3:20 (m:m), there are more pits with longer etch time. SEM shows that there are more hexagonal etch pits near the micro-cracks because many dislocations are induced by micro-cracks. In the experiment, ribbon slopes in the two sides of the pits are observed, and they are paralleled to each other. If the growth time prolonged, the ribbon slopes would disappear and the surface become flat, and this mechanism is discussed in this paper.

Abstract: Amorphous InGaZnO (a-IGZO) films are deposited on the glass substrate by RF sputtering and the influence of wet etching of a-IGZO films, etching rate, over etching features and TFT structure chose are investigated. The results show that Oxalic acid is best chose for IGZO film etching for side etching is about 0.1um , etching rate is 7.42 A/s which is easy to control and taper angle is acute. The traditional G-I-D type structure has been confirmed is not fit for the condition where the IGZO based TFT manufacture. G-D-I structure is tested and can be used in the TFT array manufacture.

Abstract: A capacitive accelerometer with triangle cross-section beam fabricated by anisotropic wet etching of (100) silicon is presented in this paper. The feature of this accelerometer is that eight suspension beams with triangle cross-section are formed by anisotropic wet etching of (100) silicon in TMAH solution, without heavy boron doping or Si-Si bonding. When the width of beam is decided, the beam’s geometry is determinate. The formation procedure of the triangle cross-section beam is analyzed in detail. Through this beam-fabrication approach, the beam’s thickness can be well controlled by beam’s width and intrinsic stress in the beams is minimized. Accelerometers with different sensitivities can be easily fabricated by varying the width of the beams. For a device with 23 μm width beams, the resonance frequency and the quality factor are 644 Hz and 32, respectively. The sensitivity of accelerometer is measured as 2 V•g-1.

Abstract: Optical tapered fiber is one of the most high efficiency evanescent wave coupler for coupling light into and out the optical microcavity. We fabricated the tapered fiber with etching method in a designed groove with HF solution. This method was low cost, readily, and controllable. An etching groove had an oval in the middle and small V-shape towards both sides. HF solution was injected into the oval groove, while the deioned water was injected into the two V-grooves. Because of the solution diffusion, the etching rate was fast in the mid and decreased gradually towards both sides,the tapered fiber was fabricated. The optical power meter was monitoring the fiber transmission during the etching process. The transmission of the tapered fiber was 98%. We proposed a mathematics model to depict the etching process, containing the relationship between the diameter of tapered fiber and the concentration of the HF solution, the etching time, humidity, temperature. We supervised the optical intensity to deduce the tapered fiber diameter. Surface morphology with AFM was detected, the roughness of the tapered fiber surface is less than 1nm. As an evanescent coupler, we used the tapered fiber to transmit 980nm pump laser to couple to Er³⁺ doped microsphere to stimulate 1557nm laser.