Flow rate control system

Abstract

Abstract PURPOSE:To prevent the production of a defective wafer by recognizing a fault in a system in its early stage, by detecting the flow rate of a fluid or the internal pressure of a treating chamber decreasing below a prescribed value by a controller. CONSTITUTION:For a semiconductor wafer treatment, gas in a treating chamber 3 is discharged by an exhaust pump 1 and pressure in the chamber 3 is detected by a pressure sensor 2, thereby regulating the total flow rate while the ratio of gas A and gas B from inlets 11 and 12 is so held constant that the pressure is constant. To increase or decrease the total flow rate, a controller 6 applies the voltage which corresponds to the flow rate to mass flow controllers 4 and 5 as flowmeters by flow rate setting signals 8 and 9. If the signal 8 or 9 goes beyond a prescribed range, e.g. a range between 10-98% of a maximum flow rate, or if the pressure in the chamber 3 decreases below a prescribed value, the controller 6 detects that and generates a fault signal to give warning of the fault state. Consequently, normal treatment in the chamber are assured and the production of a defective wafer is prevented.

Inventors

• 👤 Kaoru Kanda

Bibliographic Details