| Summary: | 碩士 === 國立高雄科技大學 === 環境與安全衛生工程系 === 107 === Atomic Layer Deposition(ALD) is a new generation semiconductor manufacturing technology. ALD offers better deposition quality over traditional chemical vapor deposition methods and has been widely used. Hexachlorodisilane (HCDS, Si2Cl6) has a lower deposition temperature, the dissociated silicon can fill into a smaller trench, and thus has been replacing other silane gases as the ALD major silicon precursor gas.
However, HCDS reacts easily with moisture in the air, generating hydrogen chloride, and formed shock sensitive deposits according to past incidents and literatures. In the ALD processes, excess HCDS has high probability to recombine and condense in the exhaust. Shock sensitive deposit may form when contact moisture. These deposits pose significant hazards for maintaining and cleaning the exhaust line.
In this study, HCDS and a small-scale quartz tube were used to simulate the ALD process. The simulated experiments aimed to find out if hazardous or shock sensitive deposit may formed in the exhaust line and also to find out the hazardous properties and hazard suppression method for the deposit.
The results found that light yellow gel may formed in the exhaust line under ambient temperature. Amount of gel increased with increasing deposition time. This gel is found to be non-shock sensitive but became shock sensitive after hydrolysis. Different methods for suppression the hazards were done. It is found that heating to 250℃ and above will eliminate the shock sensitivity of the hydrolyzed gel. Alcoholic solutions of alkaline may dissolve and decompose the hydrolyzed and unhydrolyzed gel.
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