| 摘要 |
A system for dispensing liquid chemicals, such as photoresist, from containers which includes a valve to govern the flow from the containers, a reservoir to intermediately hold the chemicals prior to pumping, and a level detector to monitor the liquid in the reservoir and to control the valve, and an aspirator to remove air from the reservoir. The aspirator is activated in response to signals from the level detector indicating that the reservoir level is low. The increased suction causes liquid to be drawn from the container into the reservoir. If after a period of time the level detector indicates the reservoir level is still low, the valve will cause liquid to be drawn from a different container. The aspirator is deactivated a period of time after the level detector indicates that the reservoir level is normal.
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