Provided is a pump backstream prevention structure for semiconductor fabrication equipment, including a sensor, an isolation air supply pipe, and a control unit. A time delay from a point in time at which the dry pump starts to malfunction to a point in time at which the isolation valve is closed is reduced, compared to a method of closing the isolation valve by a controller of the semiconductor fabrication equipment. Accordingly, a backstream in which particles move from the pumping pipe to the process chamber before the closing of the isolation valve is prevented.