SESHA 2011 Symposium / SIA IHTESH 2011 --- Abstract

SF6 Massive-Scale Decomposition Technology and Clean Development Mechanism Project in TFT-LCD Industry, South Korea.

Choi, Junghyun
(KDIA)

South Korean LCD industry has been investing new generation LCD fab since early 2000s, thus it has the line up from 2nd generation to 8th generation of LCD fab. As production expanded, greenhouse gas emission also has been increased. Within the greenhouse gas, SF6 gas is the major gas, which is used as an etching agent in dry etching process and its global warming potential is over 20,000 times higher than CO2. SF6 abatement technology was already developed, which can treat about 1 cubic meter of exhaust per minute. However, as the LCD generation increasing, the amount of process exhaust has been increasing sharply. In this circumstance, to abate SF6 gas, several small-scaled abatements should be installed in point-of-use (POU), i.e. right after each process chamber of dry etchers. Thus, there are two major problems for SF6 abatement; firstly, decomposition efficiency is difficult to be verified, secondly, huge area is needed to install enormous POU type scrubbers. To solve these obstacles, Korean LCD industry has started to develop a massive-scale decomposition facility by itself since 2005. However, the technology development was quite risky, because of 3 reasons as bellows; 1) Static pressure in dry etchers should be secured. 2) Various acidic and corrosive substances from dry etching processes should be treated before SF6 gas decomposing unit. 3) In SF6 gas decomposing unit, SF6 gas should be destructed more than 90% steadily. 4) HF and other by-products, which comes from SF6 gas decomposing, should be treated after SF6 gas decomposing unit. In order to hedge these risks, Korean LCD industry utilized CDM projects, for hiring enhanced technology and funding investment. As a result of various actions, new CDM methodology approved as AM0078 by UNFCCC in February 2009, the massive-scale decomposition facilities were developed and installed in 2009, and finally SF6 decomposition in LCD industry CDM projects were registered in UNFCCC. The developed facilities are able to decompose more than 90% of SF6 gas steadily and the capacity is 40 times larger than conventional abatement facility.