121st General Meeting of the KCS

Type Poster Presentation
Area Material Chemistry
Room No. Event Hall
Time 4월 20일 (금요일) 11:00~12:30
Code MAT.P-520
Subject Nitrification Effect on High Temperature Electrical Conductivity of Y2O3- and TiO2 -Doped AlN Ceramics
Authors Eunsil Lee, Jong-Young Kim*
Ceramicware Center, Korea Institute of Ceramic Engineering and Technol, Korea
Abstract Recently, as more semiconductor manufacturing processes have come to require high-resolution lithography, even at high temperatures, there is an increasing need for a ceramic material that can maintain electrostatic force even at high temperatures. Hence, a material that can maintain the electric resistance (> 108 Ω•cm at 500 ℃) and have a high dielectric constant at high temperatures is needed. In this work, urea (CO(NH2)2) and TiO2 were added to AlN, then the microstructural differences according to additives and sintering conditions and the electrical conductivity of AlN ceramics were investigated. When the urea is added to the AlN matrix, the urea reacts directly with the impurity of Al2O3 to convert it to AlN, or the ammonia which is formed due to the decomposition of urea at high temperatures, may cause the nitrification reaction. The reduced Al2O3 content decreases Al vacancies, which are the main carriers, and decreases species with positive charge. It is expected that the activation energy (Ea) will decrease when the nitrification reaction occurs because species, which can be paired with the Al vacancies, decrease. Actually, the calculated Ea of urea added AlN is lower than that of urea-free AlN and as the urea content increases, the Ea decreases. The reduced Ea hinders a sharp decrease in volume resistance at high temperatures. As a result, we can synthesize AlN ceramics with high density and high volume resistance at high temperatures by nitrification using urea as an additive.
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