• Korean Journal of Materials Research
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• v.11 no.5
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• pp.427-430
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• 2001

We prepared 10cm-diameter Si(100)/500 $\AA$-Si$_3$N$_4$/Si(100) wafer Pairs adopting 500 $\AA$ -thick Si$_3$N$_4$layer as insulating layer between single crystal Si wafers. Si3N, is superior to conventional SiO$_2$ in insulating. We premated a p-type(100) Si wafer and 500 $\AA$ -thick LPCVD Si$_3$N$_4$∥Si (100) wafer in a class 100 clean room. The cremated wafers are separated in two groups. One group is treated to have hydrophobic surface and the other to have hydrophilic. We employed a FLA(fast linear annealing) bonder to enhance the bond strength of cremated wafers at the scan velocity of 0.1mm/sec with varying the heat input at the range of 400~1125W. We measured bonded area using a infrared camera and bonding strength by the razor blade crack opening method. We used high resolution transmission electron microscopy(HRTEM) to probe cross sectional view of bonded wafers. The bonded area of two groups was about 75%. The bonding strength of samples which have hydrophobic surface increased with heat input up to 1577mJ/$m^2$ However, bonding strength of samples which have hydrophilic surface was above 2000mJ/$m^2$regardless of heat input. The HRTEM results showed that the hydrophilic samples have about 25 $\AA$ -thick SiO layer between Si and Si$_3$N$_4$/Si and that maybe lead to increase of bonding strength.

• Journal of the Korean Chemical Society
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• v.33 no.1
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• pp.97-105
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• 1989

This study deals with micellar effects on hydrolyses of p-nitrophenyl carboxylic esters(p-NPCE) mediated by 2-alkylbenzimidazole(R-BI) and sodium 2-alkylbenzimidazole-5-sulfonate(R-BISO$_3$Na) in aqueous and CTABr solutions. The reactions mediated by R-BI and R-BISO$_3$Na in micellar solutions are obviously slower than those by benzimidazole(BI) and sodium benzimidazole-5-sulfonate(BISO$_3$Na) respectively, and the reaction rates were decreased with increase of lengths of alkyl groups. This prestents a striking contrast to the reactions in aqueous solutions without added CTABr, of which the reaction rates are on approximately same levels. It seems due to steric effect of alkyl groups for R-BI and R-BISO$_3$Na in the Stern layer of micelle, and it is supported by measured activation parameters(${\Delta}H^{\neq},\;{\Delta}G^{\neq}\;and\;{\Delta}S^{\neq}$) of the reactions in aqueous and micellar solutions. In addition to nucleophilic ability of benzimidazole(BI) moiety of R-BISO$_3$Na on the reactions, these compounds with long alkyl groups(nonyl to pentadecyl) which form a micelle of themselves increase the reaction rates due to their micellar catalyses in aqueous solutions, not including CTABr. We measured the isotope effects to elucidate the mechanism of hydrolyses of p-nitrophenyl carboxylic esters, and the relative first order rate constant($k'_{H_2O}/k'_{D_2O}$) are on range of 2.5∼3.2. This range is too high to conclude that the hydrolyses of p-NPA mediated by various R-BISO$_3$Na proceed by nucleophilic mechanism. In other words, the reactions are assumed to proceed in part by general basic one, as compared with the reaction catalyzed by imidazole(IM) in aqueous solution.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.31 no.4 s.54
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• pp.337-342
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• 2005

The aim of this study was to evaluate the influence of different skin care ingredient concentrations on the effect of polyols and oils on the human skin moisturization and skin surface roughness. Polyols and oils were essential ingredients to make a skin care formulation. But these were still not understood how much concentration(s) were tested on human skin in the aspect of efficacy and sensory. We studied to examine various concentrations of ingredient by cosmetic companies using noninvasive methods. Polyols were composed of glycerol and butylene glycol (BG) as 1:1 ratio, and oils were hydrogenated polydecene, cetyl ethylhexanoate and pentaerythrityl tetraethylhexanoate (PTO(R), Stearinerie Dubois Fils Co., France) as 1:1:1 ratio. All compounds were tested $0{\sim}27%dml$ Polyols and $0{\sim}35%dml$ oils in O/W emulsions. We investigated the effect of water contents and the effect of stratum corneum roughness in forearm skin after application of compounds. Water contents of the skin measured by skin capacitance and skin surface roughness measured visual scoring of skin surface biopsy through the scanning electron microscopy. Water contents of the skin were highly related to amount of polyols (to 20%) and oils (to 12%). Correlation coefficients were 0.971 and 0.985 respectively (p<0.01), 2 h after application. Skin surface roughness was positively correlated with polyol contents in concentration dependent manner, and depend on oils up to 6%. The ratio of coefficient was 2.5 to 1 (polyol to oils) by regression analysis. Further studies will be conducted with other ingredients such as surfactants, lipids and aqueous materials, and with ether methods for noninvasive measurement.