• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.628-631
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• 2003

This study describes a new mastless nano-fabrication technique of Pyrex 7740 glass using the combination of nanomachining by nano-indenter XP and HF wet etching. First, the surface of a Pyrex 7740 glass specimen was machined by using the nano-machining system, which utilizes the mechanism of the nano-indenter XP. Next, the specimen was etched by HF solution. After the etching process, the convex structure or deeper hole is made because of masking or promotion effect of the affected layer generated by nano-machining. On the basis of this interesting fact. some sample structures were fabricated.

• Journal of the Microelectronics and Packaging Society
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• v.16 no.4
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• pp.55-60
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• 2009

Porous silicon film is fabricated by electrochemical etching in a chemical mixture of HF and ethanol. Effects of Si type, Si resistivity, ultrasonic frequency, current density and etching time on surface morphology of PS film were studied. Electrochemical etching in ultrasonic bath promotes the uniformity of porous layer of Si. Frequency of ultrasonic was increased from 40 kHz to 130 kHz to obtain uniform pores on the Si surface. When current density was higher, the sizes of pores were larger. The new etching cell using back contact metal and current shield help to overcome nonhomogeneity and current crowding effect, and then leads to fabricate uniform pores on the Si surface. The distribution of pore size shows no notable tendency with etching time.

• Journal of the Korean institute of surface engineering
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• v.41 no.5
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• pp.199-204
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• 2008

Indium tin oxide (ITO) has been commonly used as an anode for organic light emitting diode (OLED), because of its relatively high work function, high transmittance, and low resistance. The ITO was mostly deposited by capacitive type DC or RF sputtering. In this study we introduced a new facing target sputtering method. On applying this new sputtering method, the effect of fundamental deposition parameters such as substrate heating and post etching were investigated in relation to the resultant I-V-L characteristics of OLED. Three kinds of ITOs deposited at room temperature, at $400^{\circ}C$ and at $400^{\circ}C$ with after surface modification by $O_2$ plasma etching were compared. The OLED on ITO deposited with substrate heating and followed by etching showed better I-V-L characteristics, which starts to emit light at 4 volts and has luminescence of $65\;cd/m^2$ at 9 volts. The better I-V-L characteristics were ascribed to the relevant surface roughness with uniform micro-extrusions and to the equi-axed micromorphology of ITO surface.

• Journal of the Korean Vacuum Society
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• v.15 no.4
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• pp.387-394
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• 2006

In this study, the effect of using a neutral beam formed by low-angle forward reflection of a reactive ion beam on aspect-ratio-dependent etching (ARDE) has been investigated. When a SF6 Inductively Coupled Plasma and $SF_6$ ion beam etching are used to etch poly-Si, ARDE is observed and the etching of poly-Si on $SiO_2$ shows a higher ARDE effect than the etching of poly-Si on Si. However, by using neutral beam etching with neutral beam directionality higher than 70 %, ARDE during poly-Si etching by $SF_6$ can be effectively removed, regardless of the sample conditions. The mechanism for the removal of ARDE via a directional neutral beam has been demonstrated through a computer simulation of different nanoscale features by using the two-dimensional XOOPIC code and the TRIM code.

• Transactions of Materials Processing
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• v.13 no.4
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• pp.326-333
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• 2004

The nanoprobe based on lithography, mainly represented by SPM based technologies, has been recognized as a potential application to fabricate the surface nanosctructures because of its operational versatility and simplicity. However, nanoprobe based on lithography itself is not suitable for mass production because it is time a consuming method and not economical for commercial applications. One solution is to fabricate a mold that will be used for mass production processes such as nanoimprint, PDMS casting, and others. The objective of this study is to fabricate the silicon stamper for PDMS casting process by a mastless fabrication technique using the combination of nano/micro machining by Nanoindenter XP and KOH wet etching. Effect of the Berkovich tip alignment on the deformation was investigated. Grooves were machined on a silicon surface, which has native oxide on it, by constant load scratch (CLS), and they were etched in KOH solutions to investigate chemical characteristics of the machined silicon surface. After the etching process, the convex structures was made because of the etch mask effect of the mechanically affected layer generated by nanoscratch. On the basis of this fact, some line patterns with convex structures were fabricated. Achieved groove and convex structures were used as a stamper for PDMS casting process.

• The Journal of Korean Academy of Prosthodontics
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• v.29 no.2
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• pp.117-127
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• 1991

The purpose of this study was to evaluate the effect of surface treatment of fractured metal-ceramic crown on bond strength of porcelain repair resin. The specimens were divided into two groups for metal specimens add five groups for porcelain specimens by surface treatment methods. the metal specimens were treated by 2 methods. : micro-sandblasting with $50{\mu}m$ aluminum oxide and grinding with diamond bur. The porcelain specimens were treated by 5 methods : micro-sandblasting with $50{\mu}m$ aluminum oxide, grinding with diamond bur, etching with porcelain etching agent, combination of micro-sandblasting and etching procedure, and combination of grinding and etching procedure. After surface treatment, each specimen was bonded with composite resin and the bond strength was measured and the surface texture was observed by scanning electromicroscope(SEM). The results were as follows : 1. There was significant difference in shear bond strength between metal specimen and prorcelain specimen. 2. Bood strength of metal specimens treated with diamond bur was higher than that treated with $50{\mu}m$ aluminum oxide sandblasting. 3. Bond strength of porcelain specimen treated with diamond bur was higher than that treated with $50{\mu}m$ aluminum oxide sandblasting and porcelain etching agent. 4. There was no significant difference in shear bond strength between the group treated with diamond bur and combined treatment groups respectively. 5. The large undercuts were observed in group treated with diamond bur by SEM.

• The Journal of Advanced Prosthodontics
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• v.10 no.4
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• pp.259-264
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• 2018

PURPOSE. The purpose of this study was to evaluate the effect of the zirconia surface architecturing technique (ZSAT) on the bond strength between veneering porcelain and zirconia ceramic. MATERIALS AND METHODS. 20 sintered zirconia ceramic specimens were used to determine the optimal surface treatment time, and were randomly divided into 4 groups based on treatment times of 0, 1, 2, and 3 hours. After etching with a special solution, the surface was observed under scanning electron microscope, and then the porcelain was veneered for scratch testing. Sixty 3 mol% yttria-stabilized tetragonal zirconia polycrystal ceramic blocks were used for tensile strength testing; 30 of these blocks were surface treated and the rest were not. Statistical analysis was performed using ANOVA, the Tukey post-hoc test, and independent t-test, and the level of significance was set at ${\alpha}=.05$. RESULTS. The surface treatment of the zirconia using ZSAT increased the surface roughness, and tensile strength test results showed that the ZSAT group significantly increased the bond strength between zirconia and veneering porcelain compared to the untreated group (36 MPa vs. 30 MPa). Optimal etching time was determined to be 2 hours based on the scratch test results. CONCLUSION. ZSAT increases the surface roughness of zirconia, and this might contribute to the increased interfacial bond strength between zirconia and veneering porcelain.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.284-284
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• 2011

Recently, the increasing degree of device integration in the fabrication of Si semiconductor devices, etching processes of nano-scale materials and high aspect-ratio (HAR) structures become more important. Due to this reason, etch selectivity control during etching of HAR contact holes and trenches is very important. In this study, The etch selectivity and etch rate of TEOS oxide layer using ACL (amorphous carbon layer) mask are investigated various process parameters in CH2F2/C4F8/O2/Ar plasma during etching TEOS oxide layer using ArF/BARC/SiOx/ACL multilevel resist (MLR) structures. The deformation and etch characteristics of TEOS oxide layer using ACL hard mask was investigated in a dual-frequency superimposed capacitively coupled plasma (DFS-CCP) etcher by different fHF/ fLF combinations by varying the CH2F2/ C4F8 gas flow ratio plasmas. The etch characteristics were measured by on scanning electron microscopy (SEM) And X-ray photoelectron spectroscopy (XPS) analyses and Fourier transform infrared spectroscopy (FT-IR). A process window for very high selective etching of TEOS oxide using ACL mask could be determined by controlling the process parameters and in turn degree of polymerization. Mechanisms for high etch selectivity will discussed in detail.

• The korean journal of orthodontics
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• v.43 no.1
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• pp.23-28
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• 2013

Objective: The purpose of this study was to evaluate the effect of casein phosphopeptide amorphous calcium phosphate (CPP-ACP) on the shear bond strength (SBS) of brackets bonded to non-demineralized teeth with either phosphoric acid etching or self-etching primer. Methods: Sixty human premolars were randomly assigned to 1 of 4 treatment groups (n = 15 each): phosphoric acid etching (group 1); self-etching primer (group 2); CPP-ACP for 2 weeks + phosphoric acid etching (group 3), and CPP-ACP for 2 weeks + self-etching primer (group 4). After bonding of the maxillary premolar metal brackets, specimens were subjected to shear forces in a testing machine. Scanning electron microscopy was used to observe etching patterns on the enamel surfaces of all teeth. A 2-way analysis of variance was used to test for effects of CPP-ACP and etching system on SBS. Results: Significantly higher mean SBSs were observed in groups subjected to phosphoric acid etching (i.e., groups 1 and 3; p < 0.05). On the other hand, SBSs did not appear to be influenced by CPP-ACP (i.e., groups 3 and 4; p > 0.05). We observed a uniform and clear etched pattern on the enamel surface of the phosphoric acid etching groups. Conclusions: CPP-ACP does not significantly affect the SBS of orthodontic brackets bonded to non-demineralized teeth, regardless of which adhesive method is used to bond the brackets.

• Journal of the korean academy of Pediatric Dentistry
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• v.25 no.4
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• pp.761-771
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• 1998

In this study, attempt has been made to evaluate the effect of $CO_2$ laser irradiation on enamel surface structure and the bond strength of sealant material. Conventional acid etching was used as a control technic for comparison. The results obtained from this experiment were as follows; 1. The highest mean shear bond strength value was observed in samples of Group I (acid-etching) with the statistical significance(p<.05) between all the other groups. 2. The shear bond strength in Group IV was the lowest among laser etching groups. but there were no significant difference between them(p>.05). 3. Scanning electron microscopic observation showed that the rough and irregular surface was created by $CO_2$ laser treatment with the formation of numerous pores, micro-cracks, and small bubble-like inclusion. Increasing the energy density induced localized surface melt with a thin smooth glaze-like appearance. 4. In acid-etched control specimen cohesive failure predominated, whereas adhesive failure was the main mode in laser-treated group. Based upon the above-mentioned results, it can be assumed that the $CO_2$ laser is not an adequate substitute for the acid-etch technique in enamel preconditioning. More studies are required to explore the effective condition of laser irradiation which could attain the better bond strength of restorative materials.