• Journal of the Korean Crystal Growth and Crystal Technology
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• v.11 no.5
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• pp.231-237
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• 2001

Etch rates up to 120 nm/min for $Ta_{2}O_{5}$ were achieved in both $SF_{6}/Ar$ and $Cl_{2}/Ar$ discharges. The effect of ultraviolet (UV) light illumination during ICP etching on $Ta_{2}O_{5}$ etch rate in those plasma chemistries was examined and UV illumination was found to produce significant enhancements in $Ta_{2}O_{5}$ etch rates most likely due to photoassisted desorption of the etch products. The effects of ion flux, ion energy, and plasma composition on (Ba, Sr)$TiO_3$ etch rate were examined and maximum etch rate ~90 nm/min was achieved in $Cl_{2}/Ar$ ICP discharges while $CH_{4}/H_{2}/Ar$ chemistry produced extremely low etch rates (${\leq}10\;nm/min$) under all conditions.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.17 no.4
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• pp.373-377
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• 2004

We have investigated the electrical characterization of metal-oxide-semiconductor (MOS) capacitors formed on the inductively coupled plasma (ICP) etch-damaged both n- and p-type 4H-SiC. We found that there was an effect of a sacrificial oxidation treatment on the etch-damaged surfaces. Current-voltage and capacitance-voltage measurements of these MOS capacitors were used and referenced to those of prepared control samples without etch damage. It has been found that a sacrificial oxidation treatment can improve the electrical characteristics of MOS capacitors on etch-damaged 4H-SiC since the effective interface density and fixed oxide charges of etch-damaged samples have been found to increase while the breakdown field strength of the oxide decreased and the barrier height at the SiC-SiO$_2$ interface decreased for MOS capacitors on etch-damaged surfaces.

• Proceedings of the IEEK Conference
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• 1999.11a
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• pp.887-890
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• 1999

The etch characteristics of E-ICP and ICP are compared for the improvement of SiO$_2$ etch Process. Etch rate and etch pattern profile are measured by $\alpha$ -step surface profiler and SEM, respectively. The E-ICP provides improved characteristics on etch rate and surface profile in comparison to ICP process.

• Proceedings of the Korean Vacuum Society Conference
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• 2015.08a
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• pp.92.2-92.2
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• 2015

Negative-AND (NAND) flash의 대용량 및 소형화로 인해 10 nm급 공정을 도입한 128 Gb NAND flash가 개발된 이래, 공정이 미세화되면서 셀이 작이지고 간격이 좁아지게 되었다. 이로 인해 전자가 누설되는 간섭현상이 심화되게 된다. 이러한 문제를 해결하기 위해 기존 NAND의 평면 구조를 수직으로 적층하는 3D NAND 기술이 개발되었으며 차세대 소자를 위한 필수 기술로 각광받고 있다. 3D NAND에서 channel hole etching시 고 선택 비의 중요도가 증가하여 증착막 보호 역할을 하는 hardmask의 두께가 증가하게 되었으며 기존 하드마스크 대비 내식각성이 2배 이상 향상된 hard material 개발이 필요한 실정이다. 본 연구에서는 dopant에 따른 amorphous carbon layer (ACL)의 etch rate의 변화량을 Raman spectroscopy등의 측정장비를 이용하여 비교분석 하였다. dopant의 각각 유량별에 대한 etch rate 변화의 영향성을 비교하였다. dopant의 유량에 따라 etch rate이 변화하는 것을 관찰할 수 있었으며, 2000 sccm 이후에는 etch rate이 급격히 감소하는 경향을 보였다. Raman 측정결과, etch rate의 감소에 따라 G-peak의 red shift가 발생하였으며 두 peak 간의 차이 값이 etch rate의 변화율과 유사한 경향을 보이는 것을 확인하였다.

• Progress in Superconductivity
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• v.12 no.2
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• pp.114-117
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• 2011

We report our efforts on the development of Nb-based non-hysteretic Josephson junction fabrication process for quantu device applications. By adopting and modifying the existing Nb-aluminum oxide tunnel junction process, we develop a process for non-hysteretic Josephson junction circuits using metal-silicide as metallic barrier material. We use sputter deposition of Nb and $MoSi_2$, PECVD deposition of silicon oxide as insulator material, and ICP-RIE for metal and oxide etch. The advantage of the metal-silicide barrier in the Nb junction process is that it can be etched in $SF_6$ RIE together with Nb electrode. In order to define a junction area precisely and uniformly, end-point detection for the RIE process is critical. In this paper, we employed thin Al layer for the etch stop, and optimized the etch condition. We have successfully demonstrated that the etch stop properties of the inserted Al layer give a uniform etch profile and a precise thickness control of the base electrode in Nb trilayer junctions.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.05b
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• pp.7-12
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• 2000

This paper presents the electrochemical etch-stop characteristics of single-crystal silicon in a tetramethyl ammonium hydroxide(TMAH):isopropyl alcohol(IPA):pyrazine solution. Addition of pyrazine to a TMAH:IPA etchant increases the etch-rate of (100) silicon, thus the elapsed time for etch-stop was shortened. The current-voltage (I-V) characteristics of n- and p-type silicon in a TMAH:IPA:pyrazine solution were obtained, respectively. Open circuit potential(OCP) and passivation potential(PP) of n- and p-type silicon, respectively, were obtained and applied potential was selected between n- and p-type silicon PP. The electrochemical etch-stop is applied to the fabrication of 801 microdiaphragms having $20{\mu}m$ thickness on a 5-inch silicon wafer. The averge thicknesses of 801 microdiaphragms fabricated on the one wafer were $20.03{\mu}m$ and standard deviation was ${\pm}0.26{\mu}m$. The silicon surface of the etch-stopped microdiaphragm was extremely flat without noticeable taper or other nonuniformities. The benefits of the electrochemical etch-stop in a TMAH:IPA:pyrazine solution become apparent when reproducibility in the microdiaphragm thickness for mass production is considered. These results indicate that the electrochemical etch-stop in a TMAH:IPA:pyrazine solution provides a powerful and versatile alternative process for fabricating high-yield silicon microdiaphragms.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.08a
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• pp.124-124
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• 2010

Currently, extreme ultraviolet lithography (EUVL) is being investigated for next generation lithography. EUVL is one of competitive lithographic technologies for sub-22nm fabrication of nano-scale Si devices that can possibly replace the conventional photolithography used to make today's microcircuits. Among the core EUVL technologies, mask fabrication is of considerable importance due to the use of new reflective optics having a completely different configuration compared to those of conventional photolithography. Therefore, new materials and new mask fabrication process are required for high performance EUVL mask fabrication. This study investigated the etching properties of SnO2 (Tin Oxide) as a new absorber material for EUVL binary mask. The EUVL mask structure used for etching is SnO2 (absorber layer) / Ru (capping / etch stop layer) / Mo-Si multilayer (reflective layer) / Si (substrate). Since the Ru etch stop layer should not be etched, infinitely high selectivity of SnO2 layer to Ru ESL is required. To obtain infinitely high etch selectivity and very low LER (line edge roughness) values, etch parameters of gas flow ratio, top electrode power, dc self - bias voltage (Vdc), and etch time were varied in inductively coupled Cl2/Ar plasmas. For certain process window, infinitely high etch selectivity of SnO2 to Ru ESL could be obtained by optimizing the process parameters. Etch characteristics were measured by on scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) analyses. Detailed mechanisms for ultra-high etch selectivity will be discussed.

• Restorative Dentistry and Endodontics
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• v.43 no.3
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• pp.29.1-29.13
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• 2018

Objectives: The aims of this study were to conduct a systematic review of the microtensile bond strength (${\mu}TBS$) of multi-mode adhesives to dentin and to perform a meta-analysis to assess the significance of differences in the ${\mu}TBS$ of one of the most commonly used universal adhesives (Scotchbond Universal, 3M ESPE) depending on whether the etch-and-rinse or self-etch mode was used. Materials and Methods: An electronic search was performed of MEDLINE/PubMed, ScienceDirect, and EBSCOhost. Laboratory studies that evaluated the ${\mu}TBS$ of multi-mode adhesives to dentin using either the etch-and-rinse or self-etch mode were selected. A meta-analysis was conducted of the reviewed studies to quantify the differences in the ${\mu}TBS$ of Scotchbond Universal adhesive. Results: Only 10 studies fulfilled the inclusion criteria for the systematic review. Extensive variation was found in the restorative materials, testing methodologies, and failure mode in the reviewed articles. Furthermore, variation was also observed in the dimensions of the microtensile testing beams. The meta-analysis showed no statistically significant difference between the etch-and-rinse and self-etch modes for Scotchbond Universal adhesive (p > 0.05). Conclusions: Multi-mode 'universal' adhesives can achieve substantial bonding to dentin, regardless of the used modes (either etch-and-rinse or self-etch).

• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.167-167
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• 2011

Magnetic random access memory (MRAM) is one of the prospective semiconductor memories for next generation. It has the excellent features including nonvolatility, fast access time, unlimited read/write endurance, low operating voltage, and high storage density. MRAM consists of magnetic tunnel junction (MTJ) stack and complementary metal-oxide semiconductor (CMOS). The MTJ stack is composed of various magnetic materials, metals, and a tunneling barrier layer. For the successful realization of high density MRAM, the etching process of magnetic materials should be developed. Among various magnetic materials, FePt has been used for pinned layer of MTJ stack. The previous etch study of FePt magnetic thin films was carried out using $CH_4/O_2/NH_3$. It reported only the etch characteristics with respect to the variation of RF bias powers. In this study, the etch characteristics of FePt thin films have been investigated using an inductively coupled plasma reactive ion etcher in various etch chemistries containing $CH_4$/Ar and $CH_4/O_2/Ar$ gas mixes. TiN thin film was employed as a hard mask. FePt thin films are etched by varying the gas concentration. The etch characteristics have been investigated in terms of etch rate, etch selectivity and etch profile. Furthermore, x-ray photoelectron spectroscopy is applied to elucidate the etch mechanism of FePt thin films in $CH_4$/Ar and $CH_4/O_2/Ar$ chemistries.

• Journal of the Korean institute of surface engineering
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• v.32 no.3
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• pp.416-422
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• 1999

The characteristics of inductively coupled Cl$_2$/BCl$_3$ plasmas during the GaN etching were studied using plasma mass spectrometry by measuring the relative amounts of reactive ions, neutrals, and etch products. GaN etch rates increased with the increase of pressure and showed a maximum near 25mTorr for the pure $Cl_2$ and near 30mTorr for $Cl_2$$BCl_3$. The addition of$ BCl_3$ to $Cl_2$ also was increased GaN etch rates until 50%BCl$_3$ was mixed to $Cl_2$. The GaN etching with pure $Cl Cl_2$ appears to be related to the combination of Cl$_2^{+}$ ion bombardment and the chemical reaction of Cl radicals. In the case of the GaN etching with Cl$_2$/BCl$_3$, in addition to the combined effect of$_2^{ +}$ ions and Cl radicals, $_BCl2^{+ }$ ions appear to be responsible for some of GaN etching even though they do not have significant effect on the GaN etching compared to $Cl_2^{+}$ and Cl. $Ga^{+ }$ , $GaCl^{+}$ , $GaCl_2^{+}$ , and $N_2^{+}$ were observed as the positive ions of etch products, and the intensities of these etch products showed the same trends as those of GaN etch rate. Among the etch products, Ga and $N_2$ appear to be the main etch products.