Method of operating drippage prevention system

A drippage prevention system comprising:

• a first automatic control valve (ACV) configured to control a flow of a fluid toward a downstream nozzle;
• a second ACV downstream of the first ACV, wherein the second ACV is configured to control the flow of the fluid toward the downstream nozzle;
• a sensor configured to generate a proxy signal representing an indirect measure of a position of the first ACV;
• and
• a controller electrically connected to the second ACV and the sensor, wherein the controller is configured to cause the second ACV to fully close in response to detection of a failure state based on the proxy signal.

A method of manufacturing a semiconductor device, the method comprising:

• placing a wafer on a table;
• dispensing a fluid from a nozzle onto the wafer;
• generating at least a first proxy signal representing at least a first indirect measure of a position of a first automatic control valve (ACV), wherein the first ACV has positions ranging from fully closed to fully open,
• recognizing, based on at least the first proxy signal, whether a failure state exists in which the first ACV has failed to close;
• and
• causing a second ACV to close when the failure state exists, wherein the second ACV is fluidically connected to the first ACV, the second ACV has positions ranging from fully closed to fully open, and causing the second ACV to close ceases the dispensing of the fluid onto the wafer.