• Transactions of the Society of Information Storage Systems
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• v.3 no.3
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• pp.118-122
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• 2007

Phase-change wet-etching technology using GeSbTe phase-change films is developed. Selective etching between an amorphous and a crystalline phase can be carried out with an alkaline etchant of NaOH. Etching selectivity is dependent not only on the concentration of the alkaline etchant but also on the film structure. Specifically, metal films for heat control cause marked effects on the etching properties of GeSbTe film. Surviving amorphous pits can be obtained with Al metal layer, however etched amorphous pits are seen with Ag metal layer. An opposite selective etching behavior can be observed between samples with two different metal layers.

• Transactions of the Society of Information Storage Systems
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• v.2 no.3
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• pp.196-200
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• 2006

We are developing a phase change etching technology using an inorganic photoresist of GeSbTe film which is the recording material of the phase change disc. A selective etching phenomenon between amorphous and crystalline states can be utilized with an alkaline etchant. Phase-change pits could be formed using this technique, in which the etching selectivity is strongly dependent on the concentration of the etchant. The degree of etching was investigated by the transmittance between crystalline and amorphous films after the wet-etching. The pits patterned on the disc could be observed by AFM after wet-etching.

• Proceedings of the IEEK Conference
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• 2001.06b
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• pp.237-240
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• 2001

In this paper, we have presented processing technique about wet etching for silicon membrane construction formation. In order to make selective etching of backside silicon wafer, we used Si$_3$N$_4$ layer by PECVD(Plasma Enhanced Chemical Vapor Deposition). We have measured the surface thickness in backside silicon wafer after anisortropic wet etching with KOH:distilled water solutions. Through this experiment, we acquired the etching rate for 1.29${\mu}{\textrm}{m}$/min. The average rough of Si-membrane frontside and backside was 0.26${\mu}{\textrm}{m}$, 0.90${\mu}{\textrm}{m}$, respectively.

• Journal of the Korean Society for Precision Engineering
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• v.24 no.5
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• pp.104-109
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• 2007

Photochemical patterning of self-assembled mono layers (SAMs) has been performed by diode pumped solid state (DPSS) 3rd harmonic Nd:$YVO_4$ laser with wavelength of 355 nm. SAMs patternings of parallel lines have subsequently been used either to generate compositional chemical patterns or fabricate microstructures by a wet etching. This paper describes a selective etching process with patterned SAMs of alkanetiolate molecules on the surface of gold. SAMs formed by the adsorption of alkanethiols onto gold substrate employs as very thin photoresists. In this paper, the influence of the interaction between the functional group of SAMs and the etching solution is studied with optimal laser irradiation conditions. The results show that hydrophobic functional groups of SAMs are more effective for selective chemical etching than the hydrophilic ones.

• Journal of the Korean Society of Industry Convergence
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• v.26 no.4_1
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• pp.517-527
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• 2023

Many techniques have been proposed and investigated for microlens array manufacturing in three-dimensional (3D) structures. We present fabricating a microlens array using selective laser etching and a CO₂ laser. The femtosecond laser was employed to produce multiple micro-cracks that comprise the predesigned 3D structure. Subsequently, the wet etching process with a KOH solution was used to produce the primary microlens array structures. To polish the nonoptical surface to the optical surface, we performed reflow postprocessing using a CO₂ laser. We confirmed that the micro lens array can be manufactured in three primary shapes (cone, pyramid and hemisphere). Compared to our previous study, the processing time required for laser processing was reduced from approximately 1 hour to less than 30 seconds using the proposed processing method. Therefore, micro lens arrays can be manufactured using our processing method and can be applied to mass productionon large surface areas.

• JSTS:Journal of Semiconductor Technology and Science
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• v.13 no.6
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• pp.668-675
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• 2013

We investigate the effect of the ageing time and etching time on the etching rate of SiGe mixed etching solution, namely 1 vp HF (6%), 2 vp $H_2O_2$ (30%) and 3 vp $CH_3COOH$ (99.8%). For this etching solution, we found that the etch rate of SiGe layer is saturated after the ageing time of 72 hours, and the selectivity of $Si_{0.8}Ge_{0.2}$ layer and Si layer is 20:1 at ageing time of 72 hours. The collapse was appeared at the etching time of 9min with etching solution of after saturation ageing time.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.24 no.1
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• pp.7-11
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• 2011

Sapphire substrate was patterned by a selective chemical wet etching technique, and GaN/InGaN structures were grown on this substrate by MOVPE (Metal Organic Vapor Phase Epitaxy). The surface of grown GaN on patterned sapphire substrate (PSS) has good morphology and uniformity. The patterned sapphire substrate LED showed better light output than conventional LED that improvement 50%. We think these results come from enhancement of internal quantum efficiency by decrease of threading dislocation and increase of light extraction efficiency. Also these LED showed more uniform emission distribution in angle than conventional LED.

• ETRI Journal
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• v.27 no.5
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• pp.484-490
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• 2005

We fabricated 40 Gb/s front-end optical receivers using spot-size converter integrated waveguide photodiodes (SSC-WGPDs). The fabricated SSC-WGPD chips showed a high responsivity of approximately 0.8 A/W and a 3 dB bandwidth of approximately 40 GHz. A selective wet-etching method was first adopted to realize the required width and depth of a tapered waveguide. Two types of electrical pre-amplifier chips were used in our study. One has higher gain and the other has a broader bandwidth. The 3 dB bandwidths of the higher gain and broader bandwidth modules were about 32 and 42 GHz, respectively. Clear 40 Gb/s non-return-to-zero (NRZ) eye diagrams showed good system applicability of these modules.

• Proceedings of the Korean Vacuum Society Conference
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• 1997.02a
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• pp.54-55
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• 1997

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.24 no.5
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• pp.196-201
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• 2014

We investigated defects and surface polarity in AlN and GaN by using wet chemical etching. Therefore, the effectiveness and reliability of estimating the single crystals by defect selective etching in NaOH/KOH eutectic alloy have been successfully demonstrated. High-quality AlN and GaN single crystals were etched in molten NaOH/KOH eutectic alloy. The etching characteristics and surface morphologies were carried out by scanning electron microscope (SEM) and atomic force microscope (AFM). The etch rates of AlN and GaN surface were calculated by etching depth as a function of etching time. As a result, two-types of etch pits with different sizes were revealed on AlN and GaN surface, respectively. Etching produced hexagonal pits on the metal-face (Al, Ga) (0001) plane, while hexagonal hillocks formed on the N-face. On etching rate calibration, it was found that N-face had approximately 109 and 15 times higher etch rate than the metal-face of AlN and GaN, respectively. The size of etch pits increased with an increase of the etching time and they tend to merge together with a neighbouring etch pits. Also, the chemical mechanism of each etching process was discussed. It was found that hydroxide ion ($OH^-$) and the dangling bond of nitrogen play an important role in the selective etching of the metal-face and N-face.