DEVELOPMENT OF NITROGEN GAS BUBBLING DEAERATOR MADE OF POLYVINYLIDEN FLUORIDE

It is essentially important to remove the dissolved oxygen (DO) in the ultrapure water for the future ultralarge scale integration (ULSI). W e have found the existence of the big driving force for the oxygen dif fusion through tube materials that increases the DO concentration. The DO concentration through the perfluoro alkoxide (PFA) tube rapidly in creased with decreasing the flow rate of the ultrapure water. On the o ther hand, the DO concentration through the polyvinyliden fluoride (PV DF) tube that is a low oxygen permeability material did not increase w ith decreasing the flow rate. Based on this finding, we have developed the nitrogen gas bubbling deaerator made of PVDF as a point of use pu rifier. In this system, the residual DO concentration reached 0.2 ppb at a gas-liquid ratio of 1.2 m(3)/m(3) at each bubbling tower that is ten times smaller than the previously reported one. Furthermore, other contaminations in the ultrapure water do not increase after this proc ess.