Patent Number: 
Section: claims

1. A gas treatment system for supplying a treatment gas into a vacuum vessel to carry out a predetermined treatment for a substrate to be treated, said system comprising: electron adding means for emitting electrons to said treatment gas extracted from said vacuum vessel and for causing electrons to adhere to particles in said treatment gas for generating negative ions of said particles;  mass spectrometry means for determining the kind of negative ions of said particles, to which electrons adhere, by said electron adding means;  density estimating means for estimating the density of said particles in said treatment gas corresponding to the determined negative ions, on the basis of the measured value of the number of said negative ions determined by said mass spectrometry means; and  a control part for controlling a process condition, which influences the state of said treatment gas in said vacuum vessel, on the basis of the estimated result of the density of said particles estimated by said density estimating means. 2. A gas treatment system as set forth in  claim 1 , wherein said density estimating means varies the magnitude of electron energy emitted from said electron adding means, to derive the variation in measured value of said negative ions of said particles, to use data corresponding to the peak value of the measured value as said estimated result of said density of said particles. claim 1 3. A gas treatment system as set forth in  claim 1 , wherein said mass spectrometry means has a gas extracting port which is movable in said vacuum vessel. claim 1 4. A gas treatment system as set forth in  claim 1 , wherein said electron adding means is connected to said vacuum vessel via a bellows which is retractable with respect to said vacuum vessel. claim 1 5. A gas treatment system as set forth in  claim 1 , wherein said process condition is at least one of the magnitude of energy applied to said treatment gas, the pressure in said vacuum vessel, and the flow rate of said treatment gas. claim 1 6. A gas treatment system as set forth in  claim 1 , wherein said particles in said treatment gas, to which electrons adhere, are radicals, molecules or atoms. claim 1 7. A gas treatment system as set forth in  claim 1 , wherein said control part carries out a feedback in real time on the basis of the estimated result of the density of said particles estimated by said density estimating means, to control said process condition. claim 1 8. A gas treatment system as set forth in  claim 1 , wherein said control part sets and controls said process condition with respect to a subsequent product substrate to be treated, on the basis of the estimated result of the density of said particles estimated by said density estimating means with respect to a test substrate to be treated. claim 1 9. A gas treatment method for supplying a treatment gas into a vacuum vessel to carry out a predetermined treatment for a substrate to be treated, said method comprising the steps of: extracting said treatment gas, and causing electron adding means to emit electrons to the extracted treatment gas to cause electrons to adhere to particles in said treatment gas;  causing mass spectrometry means to determine the kind of negative ions of said particles, to which electrons adhere, by said electron adding means;  causing density estimating means to estimate the density of said particles in said treatment gas corresponding to the determined negative ions, on the basis of the measured value of the number of said negative ions determined by said mass spectrometry means; and  causing a control part to control a process condition, which influences the state of said treatment gas in said vacuum vessel, on the basis of the estimated result of the density of said particles estimated by said density estimating means. 10. A gas treatment method as set forth in  claim 9 , wherein said density estimating means varies the magnitude of electron energy emitted from said electron adding means, to derive the variation in measured value of said negative ions of said particles, to use data corresponding to the peak value of the measured value as said estimated result of said density of said particles. claim 9 11. A gas treatment method as set forth in  claim 9 , wherein said mass spectrometry means has a gas extracting port which is movable in said vacuum vessel. claim 9 12. A gas treatment method as set forth in  claim 9 , wherein said electron adding means is connected to said vacuum vessel via a bellows which is retractable with respect to said vacuum vessel. claim 9 13. A gas treatment method as set forth in  claim 9 , wherein said process condition is at least one of the magnitude of energy applied to said treatment gas, the pressure in said vacuum vessel, and the flow rate of said treatment gas. claim 9 14. A gas treatment method as set forth in  claim 9 , wherein said particles in said treatment gas, to which electrons adhere, are radicals, molecules or atoms. claim 9 15. A gas treatment method as set forth in  claim 9 , wherein said control part carries out a feedback in real time on the basis of the estimated result of the density of said particles estimated by said density estimating means, to control said process condition. claim 9 16. A gas treatment method as set forth in  claim 9 , wherein said control part sets and controls said process condition with respect to a subsequent product substrate to be treated, on the basis of the estimated result of the density of said particles estimated by said density estimating means with respect to a test substrate to be treated. claim 9