Material gas concentration control system

A material gas concentration control system that is used for a material evaporation system comprising a tank to accommodate a material, an inlet line to input a carrier gas for evaporating the accommodated material into the tank and an outlet line to output a mixed gas consisting of a material gas formed by the evaporated material and the carrier gas from the tank, and characterized by comprising:

• a first valve arranged in the outlet line,
• a concentration measuring part that comprises a pressure measuring part to measure the pressure in the tank and that measures the concentration of the material gas in the mixed gas,
• a temperature measuring part that measures a temperature in the tank, and
• a concentration control part that controls an open degree of the first valve so as to make the measured concentration of the material gas measured by the concentration measuring part become a previously determined set concentration, wherein
• the concentration control part comprises:
• a total pressure calculating part that calculates the pressure in the tank so as to make the material gas become the set concentration based on a measured temperature measured by the temperature measuring part,
• a set pressure setting part that sets the set pressure as the pressure in the tank calculated by the total pressure calculating part during a predetermined period after the set concentration is changed, while the set pressure setting part that changes the set pressure so as to reduce a deviation between the measured concentration and the set concentration during other periods, and
• a first valve control part that controls an open degree of the first valve so as to make a measured pressure measured by the pressure measuring part become the set pressure.

A material gas concentration control system that is used for a material evaporation system comprising a tank to accommodate a material, an inlet line to input a carrier gas for evaporating the accommodated material into the tank and an outlet line to output a mixed gas consisting of a material gas formed by the evaporated material and the carrier gas from the tank, and characterized by comprising:

• a first valve arranged in the outlet line,
• a concentration measuring part that measures the concentration of the material gas in the mixed gas,
• a pressure measuring part that measures a pressure in the tank,
• a concentration control part that controls an open degree of the first valve so as to make the measured concentration of the material gas measured by the concentration measuring part become a previously determined set concentration, and
• a material amount estimating part that estimates an amount of the material accommodated in the tank, wherein
• the concentration control part comprises:
• a set pressure setting part that changes the set pressure so as to reduce a deviation between the measured concentration and the set concentration, and
• a first valve control part that controls an open degree of the first valve so as to make a measured pressure measured by the pressure measuring part become the set pressure, and
• the material amount estimating part estimates and calculates an amount of the material accommodated in the tank based on the set pressure.