• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.77-77
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• 2011

These days, a growing demand for memory device is filled up with the flash memory and the dynamic random access memory (DRAM). Although DRAM is a reasonable solution for current demand, the universal novel memory with high density, high speed and nonvolatility, needs to be developed. Among various new memories, the magnetic random access memory (MRAM) device is considered as one of good candidate memories because of excellent features including high density, high speed, low operating power and nonvolatility. The etching of MTJ stack which is composed of magnetic materials and insulator such as MgO is one of the vital process for MRAM. Recently, MgO has attracted great interest in the MTJ stack as tunneling barrier layer for its high tunneling magnetoresistance values. For the successful realization of high density MRAM, the etching process of MgO thin films should be investigated. Until now, there were some works devoted to the investigations on etch characteristics of MgO thin films. Initially, ion milling was applied to the etching of MgO thin films. However, ion milling has many disadvantages such as sidewall redeposition and etching damage. High density plasma etching containing the magnetically enhanced reactive ion etching and high density reactive ion etching have been employed for the improvement of etching process. In this work, inductively coupled plasma reactive ion etching (ICPRIE) system was adopted for the improvement of etching process using MgO thin films and etching gas mixes of $CH_4$/Ar and $CH_4$/$O_2$/Ar have been employed. The etch rates are measured by a surface profilometer and etch profiles are observed using field emission scanning emission microscopy (FESEM). The effects of gas concentration and etch parameters such as coil rf power, dc-bias voltage to substrate, and gas pressure on etch characteristics will be systematically explored.

• Journal of the Semiconductor & Display Technology
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• v.5 no.2 s.15
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• pp.41-46
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• 2006

Wet etching process in recent semiconductor manufacturing is devided into batch and single wafer type. Batch type wet etching process provides more throughput with poor etching uniformity compared to single wafer type process. Single wafer process achieves better etching uniformity by boom-swing injected chemical on rotating wafer. In this study, etching characteristics of $SiO_2$ layer at room and elevated temperature is evaluated and compared. The difference in etching rate and uniformity of each condition is identified, and the temperature profile of injected chemical is theoretically calculated and compared to that of experimental result. Better etching uniformity is observed with single wafer tool with boom-swing injection compared to single wafer process without boom-swing or batch type tool.

• Journal of the Semiconductor & Display Technology
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• v.8 no.4
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• pp.1-5
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• 2009

This investigation is applied Taguchi method and the analysis of variance(ANOVA) to the reactive ion etching(RIE) characteristics of $SiO_2$ film coated on a wafer with Experimental Analysis and Optimization of $CF_4/O_2$ Plasma Etching Process mixture. Plans of experiments via nine experimental runs are based on the orthogonal arrays. A $L_9$ orthogonal array was selected with factors and three levels. The three factors included etching time, RF power, gas mixture ratio. The etching rate of the film were measured as a function of those factors. In this study, the etching thickness mean and uniformity of thickness of the RIE are adopted as the quality targets of the RIE etching process. The partial factorial design of the Taguchi method provides an economical and systematic method for determining the applicable process parameters. The RIE are found to be the most significant factors in both the thickness mean and the uniformity of thickness for a RIE etching process.

• Journal of Electrical Engineering and Technology
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• v.3 no.2
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• pp.271-275
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• 2008

The MAM(Megasonic Agitated Module) has been fabricated for improving the characteristics of wet etching. The characteristics of the MAM are investigated during the wet etching with and without megasonic agitation in this paper. The adoption of the MAM has improved the characteristics of wet etching, such as the etch rate, etch uniformity, and surface roughness. Especially, the etching uniformity on the entire wafer was less than ${\pm}1%$ in both cases of Si and glass. Generally, the initial root-mean-square roughness($R_{rms}$) of the single crystal silicon was 0.23nm. Roughnesses of 566nm and 66nm have been achieved with magnetic stirring and ultrasonic agitation, respectively, by some researchers. In this paper, the roughness of the etched Si surface is less than 60 nm. Wet etching of silicon with megasonic agitation can maintain nearly the original surface roughness during etching. The results verified that megasonic agitation is an effective way to improve etching characteristics of the etch rate, etch uniformity, and surface roughness and that the developed micromachining system is suitable for the fabrication of devices with complex structures.

• Journal of the Korea Safety Management & Science
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• v.17 no.3
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• pp.355-362
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• 2015

There has been an increase of using Bosch Process to fabricate MEMS Device, TSV, Power chip for straight etching profile. Essentially, the interest of TSV technology is rapidly floated, accordingly the demand of Bosch Process is able to hold the prominent position for straight etching of Si or another wafers. Recently, the process to prevent under etching or over etching using EPD equipment is widely used for improvement of mechanical, electrical properties of devices. As an EPD device, the OES is widely used to find accurate end point of etching. However, it is difficult to maintain the light source from view port of chamber because of contamination caused by ion conflict and byproducts in the chamber. In this study, we adapted the SPOES to avoid lose of signal and detect less open ratio under 1 %. We use 12inch Si wafer and execute the through etching 500um of thickness. Furthermore, to get the clear EPD data, we developed an algorithm to only receive the etching part without deposition part. The results showed possible to find End Point of under 1 % of open ratio etching process.

• Journal of the Semiconductor & Display Technology
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• v.16 no.3
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• pp.41-46
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• 2017

This study aims to select suitable co-solvents and to obtain optimal process conditions in order to improve process efficiency and productivity through experimental results obtained under various experimental conditions for the etching and rinsing process using liquid carbon dioxide and supercritical carbon dioxide. Acetone was confirmed to be effective through basic experiments and used as the etching solution for MEMS-wafer etching in this study. In the case of using liquid carbon dioxide as the solvent and acetone as the etching solution, these two components were not mixed well and showed a phase separation. Liquid carbon dioxide in the lower layer interfered with contact between acetone and Mems-wafer during etching, and the results after rinsing and drying were not good. Based on the results obtained under various experimental conditions, the optimum process for treating MEMS-wafer using supercritical CO2 as the solvent, acetone as the etching solution, and methanol as the rinsing solution was set up, and MEMS-wafer without stiction can be obtained by continuous etching, rinsing and drying process. In addition, the amount of the etching solution (acetone) and the cleaning liquid (methanol) compared to the initial experimental values can be greatly reduced through optimization of process conditions.

• Journal of the Korean Institute of Telematics and Electronics
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• v.24 no.1
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• pp.91-96
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• 1987

Plasma etching can obtain less damaged etch surface than reactive ion etching. This study was performed to get anisotropic etching characteristics of Si using two step etching technique with C2CIF5 and SF6 gas mixture. The results show that the etch rate and aspect ratio of silicon was increased with increment of SF6 contents. The bulging phenomenon on trench side wall in the plasma one-step etching technique was eliminated by the two step etching technique. The anisotropy was decreased from 12(at 120m Torr) to 2.2(at 400m Torr) with increasing the chamber pressure. At the low rf power (350 watts) anisotrpy of silicon was obtained 7 lower than that of high rf power (650 watts. A:~9). In Summary we obtained anisotropic etching profiles of silicon with e 6\ulcornerm depth by using the plasma two-step etching technique.

• Journal of the Korean Electrochemical Society
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• v.14 no.4
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• pp.191-195
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• 2011

Wet chemical etching methods were utilized to conduct Si surface texturing, which could enhance photoelectrochemical hydrogen generation rate. Two different etching methods tested, which were anisotropic metal-catalyzed electroless etching and isotropic etching. The Si nano-texture that was fabricated by the anisotropic etching showed ~25% increase in photocurrent for H2 generation. The photocurrent enhancement was attributed to the reduced reflection loss at the nano-textured Si surface, which provided a layer of intermediate density between water and the Si substrate.

• Corrosion Science and Technology
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• v.2 no.5
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• pp.238-242
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• 2003

The characteristics of Ru etching using $O_2/Cl_2$ plasmas were investigated by employing inductively coupled plasma (ICP) etcher. The changes of Ru etch rate, Ru to $SiO_2$ etch selectivity and Ru electrode etching slope with the gas flow ratio, bias power, total gas flow rate, and source power were scrutinized. A high etching slope (${\sim}86^{\circ}$) and a smooth surface after etching was attained using $O_2/Cl_2$ inductively coupled plasma.

• 한국정보디스플레이학회:학술대회논문집
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• 2007.08b
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• pp.1273-1276
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• 2007

We provide a newly developed dry etching process for the fabrication of ZnO-based oxide TFTs. The etching characteristics of ZnO (active layer) and $Al_2O_3$ (gate insulator) thin films were systematically investigated when the etching gas mixtures and their mixing ratios were varied in the heliconplasma etching system.