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Economic analysis of waste recycle process in perhydropolysiloxazane synthesis
Huichan Yun,양대륙,Seungjong Yeom 한국화학공학회 2014 Korean Journal of Chemical Engineering Vol.31 No.5
The perhydropolysiloxazane (PHPS) solution has been widely used in the spin-on-dielectric (SOD) processto form silicon oxide layer on a wafer in semiconductor industries. To reduce the whole semiconductor manufacturingcost, the process of PHPS solution production requires high productivity as well as low production cost. A largeportion of the PHPS solution production cost is attributed to the large usage of solvents (pyridine and xylene), becausemore than 20 times of solvents in mass are required to produce a unit mass of high purity PHPS solution. Therefore,we suggest several plausible solvent regeneration processes of organic solvent waste from the PHPS solution production,and their economics is evaluated for comparison.
Dae Ryook Yang,Seungjong Yeom,Huichan Yun 한국화학공학회 2013 Korean Journal of Chemical Engineering Vol.30 No.10
L-glutamic acid can be crystallized as metastable α-form and stable β-form crystal. The α-form is desired because of its prismatic shape. Production of α-form of L-glutamic acid by cooling crystallization is not well-defined and α-form solid is commercially not available. In this study, an optimal cooling strategy to selectively produce large and narrowly distributed α-crystals is found by modeling and optimizing the crystallization and polymorphic transformation of L-glutamic acid. The optimal temperature profile is found to be cooling-heating-cooling concept where short nucleation period is followed by growth period in metastable zone. The obtained α-form of L-glutamic acid by optimal strategy had improved mean size, distribution, and purity compared to constant cooling.