• Journal of the Microelectronics and Packaging Society
• /
• v.12 no.4 s.37
• /
• pp.275-280
• /
• 2005

We propose a new approach to greatly simplify the fabrication of conventional nanoimprint lithography (NIL) by combined nanoimprint and photolithography (CNP). We introduce a hybrid mask mold (HMM) made from UV transparent material with a UV-blocking Cr metal layer placed on top of the mold protrusions. We used a negative tone photo resist (PR) with higher selectivity to substrate the CNP process instead of the UV curable monomer and thermal plastic polymer that has been commonly used in NIL. Self-assembled monolayer (SAM) on HMM plays a reliable role for pattern transfer when the HMM is separated from the transfer layer. Hydrophilic $SiO_2$ thin film was deposited on all parts of the HMM, which improved the formation of SAM. This $SiO_2$ film made a sub-10nm formation without any pattern damage. In the CNP technique with HMM, the 'residual layer' of the PR was chemically removed by the conventional developing process. Thus, it was possible to simplify the process by eliminating the dry etching process, which was essential in the conventional NIL method.

• Korean Journal of Materials Research
• /
• v.19 no.3
• /
• pp.132-136
• /
• 2009

This study investigates GaAs dry etching in capacitively coupled $BCl_3/N_2$ plasma at a low vacuum pressure (>100 mTorr). The applied etch process parameters were a RIE chuck power ranging from $100{\sim}200W$ on the electrodes and a $N_2$ composition ranging from $0{\sim}100%$ in $BCl_3/N_2$ plasma mixtures. After the etch process, the etch rates, RMS roughness and etch selectivity of the GaAs over a photoresist was investigated. Surface profilometry and field emission-scanning electron microscopy were used to analyze the etch characteristics of the GaAs substrate. It was found that the highest etch rate of GaAs was $0.4{\mu}m/min$ at a 20 % $N_2$ composition in $BCl_3/N_2$ (i.e., 16 sccm $BCl_3/4$ sccm $N_2$). It was also noted that the etch rate of GaAs was $0.22{\mu}m/min$ at 20 sccm $BCl_3$ (100 % $BCl_3$). Therefore, there was a clear catalytic effect of $N_2$ during the $BCl_3/N_2$ plasma etching process. The RMS roughness of GaAs after etching was very low (${\sim}3nm$) when the percentage of $N_2$ was 20 %. However, the surface roughness became rougher with higher percentages of $N_2$.

• The Korean Journal of Pesticide Science
• /
• v.7 no.2
• /
• pp.108-116
• /
• 2003

A series of new quinclorac family, herbicidal 3-phenyl-5-(3,7-dichloro-8-quinolinyl)-1,2,4-oxadiazole derivatives as substrate were synthesized and their growth inhibition activity $(pI_{50})$ against root and shoot of rice plant (Oryza sativa L.) and barnyard grass (Echinochloa crus-galli) were determined. And then comparative molecular field analysis (CoMFA) and molecular holographic quantitative structure- activity relationship (HQSAR) were compared in terms of their potential for predictiability. The statistical results were suggested that HQSAR based model had better predictability than CoMFA model. The selective factors to remove barnyard grass take electron withdrawing groups which can be created positive charge and steric bulky on the phenyl ring. Results revealed that the unknown 2,6-dichloro-substituent, U5 and 2,4,6-trichloro-substituent, U6(${\Delta}pI_{50}$=CoMFA: 1.18 & HQSAR: 1.82) were predicted as compound with higher activity and selectivity.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2008.06a
• /
• pp.477-477
• /
• 2008

For more than three decades, the gate dielectrics in CMOS devices are $SiO_2$ because of its blocking properties of current in insulated gate FET channels. As the dimensions of feature size have been scaled down (width and the thickness is reduced down to 50 urn and 2 urn or less), gate leakage current is increased and reliability of $SiO_2$ is reduced. Many metal oxides such as $TiO_2$, $Ta_2O_4$, $SrTiO_3$, $Al_2O_3$, $HfO_2$ and $ZrO_2$ have been challenged for memory devices. These materials posses relatively high dielectric constant, but $HfO_2$ and $Al_2O_3$ did not provide sufficient advantages over $SiO_2$ or $Si_3N_4$ because of reaction with Si substrate. Recently, $HfO_2$ have been attracted attention because Hf forms the most stable oxide with the highest heat of formation. In addition, Hf can reduce the native oxide layer by creating $HfO_2$. However, new gate oxide candidates must satisfy a standard CMOS process. In order to fabricate high density memories with small feature size, the plasma etch process should be developed by well understanding and optimizing plasma behaviors. Therefore, it is necessary that the etch behavior of $HfO_2$ and plasma parameters are systematically investigated as functions of process parameters including gas mixing ratio, rf power, pressure and temperature to determine the mechanism of plasma induced damage. However, there is few studies on the the etch mechanism and the surface reactions in $BCl_3$ based plasma to etch $HfO_2$ thin films. In this work, the samples of $HfO_2$ were prepared on Si wafer with using atomic layer deposition. In our previous work, the maximum etch rate of $BCl_3$/Ar were obtained 20% $BCl_3$/ 80% Ar. Over 20% $BCl_3$ addition, the etch rate of $HfO_2$ decreased. The etching rate of $HfO_2$ and selectivity of $HfO_2$ to Si were investigated with using in inductively coupled plasma etching system (ICP) and $BCl_3/Cl_2$/Ar plasma. The change of volume densities of radical and atoms were monitored with using optical emission spectroscopy analysis (OES). The variations of components of etched surfaces for $HfO_2$ was investigated with using x-ray photo electron spectroscopy (XPS). In order to investigate the accumulation of etch by products during etch process, the exposed surface of $HfO_2$ in $BCl_3/Cl_2$/Ar plasma was compared with surface of as-doped $HfO_2$ and all the surfaces of samples were examined with field emission scanning electron microscopy and atomic force microscope (AFM).

• Korean Journal of Food Science and Technology
• /
• v.7 no.4
• /
• pp.221-228
• /
• 1975

Meat tenderness is one of the most important factors in meat products because it plays a major role in the palatability of meat. To get information on the role of commercial meat tenderizer, the tenderizing ability of commercial meat tenderizer was measured with various substrates. The results obtained are as follows. 1. Content of crude protein in a commercial meat tenderizer was 4.9%. 2. Optimum temperature for proteolytic activity of meat tenderizer was $60{\sim}70^{\circ}C$. 3. Maximal activity of proteinase was obtained at pH $6{\sim}7$. 4. Proteolytic enzyme was activated by KCN, NaCN, EDTA. Thus, it was concluded that protease system of commercial meat tenderizer composed of plant origin proteinases. 5. Proteinase activity was completely inhibited by 10mM of N-Ethylmaleimide. 6. Commercial meat tenderizer showed stronger proteolytic activity on casein than on the water soluble fraction of meat protein, whereas it hydrolyzed the myofibrillar protein less efficiently.

• Applied Chemistry for Engineering
• /
• v.34 no.3
• /
• pp.258-263
• /
• 2023

In this study, conductive polymers and the enzyme tyrosinase (Tyr) were deposited on the surface of a screen printed carbon electrode (SPCE), which can be fabricated as a disposable sensor chip, and applied to the detection of bisphenol F (BPF), an endocrine disruptor with proven links to male diseases and thyroid disorders, using electrochemical methods. On the surface of the SPCE working electrode, which was negatively charged by oxygen plasma treatment, a positively charged conductive polymer, poly(diallyldimethyl ammonium chloride) (PDDA), a negatively charged polymer compound, poly(sodium 4-styrenesulfonate) (PSS), and another layer of PDDA were layered by electrostatic attraction in the order of PDDA, PSS, and finally PDDA. Then, a layer of Tyr, which was negatively charged due to pH adjustment to 7.0, was added to create a PDDA-PSS-PDDA-Tyr sensor for BPF. When the electrode sensor is exposed to a BPF solution, which is the substrate and target analyte, 4,4'-methylenebis(cyclohexa-3,5-diene-1,2-dione) is generated by an oxidation reaction with the Tyr enzyme on the electrode surface. The reduction process of the product at 0.1 V (vs. Ag/AgCl) generating 4,4'-methylenebis(benzene-1,2-diol) was measured using cyclic and differential pulse voltammetries, resulting in a change in the peak current with respect to the concentration of BPF. In addition, we compared the detection performance of BPF using an ionic liquid electrolyte as an alternative to phosphate-buffered saline, which has been used in many previous sensing studies. Furthermore, the selectivity of bisphenol S, which acts as an interfering substance with a similar structure to BPF, was investigated. Finally, we demonstrated the practical applicability of the sensor by applying it to analyze the concentration of BPF in real samples prepared in the laboratory.