| Summary: | 碩士 === 中國醫藥大學 === 職業安全與衛生學系碩士在職專班 === 101 === Because of the continuous evolution of the semiconductor manufacturing process, chemicals, processes and equipment were continue renewed, and that create some hazards, such as, creating of stench after process change. In this study, the actual cases of stench creation after introducing new dry etching process was investigated. First, investigate the change of devices and chemical, and sampling and analyze gas and solid residue, in order to find out the source of the stench. Then plan a more economical and effective improvement project based on harmful substances escaping, SOP of before machine maintenance.
The results showed that this case involving three changes in process, in addition to the change of reaction chamber, the use of argon gas was halted, and replacing dichlorodifluoromethane with trifluoromethane and the quantities of usage was increased. New process used tetrafluoromethane, trifluoromethane, to etch the underlying tungsten wafer, however, the old process used tetrafluoromethane, difluoromethane, in dry etching in two steps. The new process do not use argon dilution, it provides a better choice and more WF6 product attached to the reaction chamber and parts, which is not easily to be removed by nitrogen cycling purge and pumped drawn. WF6 react with moisture in the air (43%) (WF6 + 3H2O-->6HF + WO3) and produce hydrogen fluoride and pungent stench, when maintenance personnel open reaction chamber. The environmental sampling analysis indicated that the concentration of HF is up to 23 ppm.
A local exhaust ventilation system was suggested to be the most suitable engineering control of workplace hazards in improving the environment. 28 similar process machine were also improved by setting the local exhaust ventilation system. Consider the possibility of shared machine and convenience, and finally set a total of 16 local exhaust ventilation system. After the improvement, no HF was detected by the environmental sampling and analysis. The operation of local exhaust ventilation system, personnel protective equipment requirements was written in standard operating procedures.
Keywords：Process change；Engineering control of workplace hazards；Stench；Etch
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