MASS FLOW RATE CONTROL APPARATUS, ITS CALIBRATION METHOD AND SEMICONDUCTOR-PRODUCING APPARATUS
First Claim
1. A mass flow controller having a path for flowing a fluid, comprising a calibrating valve disposed on the most upstream side of said path for opening or closing said path;
- a mass flow rate control valve mechanism having such a changeable degree of opening that the mass flow rate of said fluid is equal to a set mass flow rate;
a tank provided at said path upstream of said mass flow rate control valve mechanism;
a means for sensing the mass flow rate of said fluid to output a mass flow rate signal;
a means for sensing the pressure of said fluid to output a pressure signal; and
a calibration control means for carrying out mass flow rate calibration using said calibrating valve, said tank, said mass-flow-rate-sensing means and said pressure-sensing means.
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Accused Products
Abstract
A method for calibrating a mass flow controller comprising a calibrating valve disposed on the most upstream side of a path, a mass flow rate control valve mechanism, a tank provided at the path on the upstream side of the mass flow rate control valve mechanism, a mass-flow-rate-sensing means, a pressure-sensing means, a means for controlling the mass flow rate control valve mechanism, and a mass flow rate calibration control means, the method comprising the steps of (1) permitting a fluid at a set mass flow rate to flow through the path, (2) setting the mass flow rate control valve mechanism at a degree of opening that the mass flow rate of the fluid is equal to the set mass flow rate, (3) closing the calibrating valve, (4) measuring the pressure and mass flow rate of the fluid after a fluid flow from the tank is stabilized, (5) determining a variation ratio of the pressure and mass flow rate to reference pressure and mass flow rate measured by the same procedures in an initial state, is and (6) performing calibration depending on the variation ratio.
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Citations
15 Claims
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1. A mass flow controller having a path for flowing a fluid, comprising a calibrating valve disposed on the most upstream side of said path for opening or closing said path;
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a mass flow rate control valve mechanism having such a changeable degree of opening that the mass flow rate of said fluid is equal to a set mass flow rate; a tank provided at said path upstream of said mass flow rate control valve mechanism; a means for sensing the mass flow rate of said fluid to output a mass flow rate signal; a means for sensing the pressure of said fluid to output a pressure signal; and a calibration control means for carrying out mass flow rate calibration using said calibrating valve, said tank, said mass-flow-rate-sensing means and said pressure-sensing means. - View Dependent Claims (2, 3, 4, 5, 6, 7, 15)
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- 8. A method for calibrating a mass flow controller comprising a calibrating valve disposed on the most upstream side of a path, a mass flow rate control valve mechanism, a tank provided at said path on the upstream side of said mass flow rate control valve mechanism, a mass-flow-rate-sensing means, a pressure-sensing means, a means for controlling said mass flow rate control valve mechanism, and a mass flow rate calibration control means, the method comprising the steps of (1) permitting a fluid at a set mass flow rate to flow through said path, (2) setting said mass flow rate control valve mechanism at a degree of opening that the mass flow rate of said fluid is equal to said set mass flow rate, (3) closing said calibrating valve, (4) measuring the pressure and mass flow rate of said fluid after a fluid flow from said tank is stabilized, (5) determining a variation ratio of said pressure and mass flow rate to reference pressure and mass flow rate measured by the same procedures in an initial state, and (6) performing calibration depending on said variation ratio.
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14. A method for calibrating a mass flow controller comprising a calibrating valve disposed on the most upstream side of said path, a mass flow rate control valve mechanism, a tank provided at said path upstream of said mass flow rate control valve mechanism, a mass-flow-rate-sensing means, a pressure-sensing means, a means for controlling said mass flow rate control valve mechanism, and a mass flow rate calibration control means, the method comprising the steps of (1) permitting a fluid at a set mass flow rate to flow through said path, (2) setting said mass flow rate control valve mechanism at a degree of opening that the mass flow rate of said fluid is equal to said set mass flow rate, (3) closing said calibrating valve, (4) measuring the pressure Pf and mass flow rate Rf of said fluid after a fluid flow from said tank is stabilized, (5) determining a calibrating comparator Af represented by a ratio of the product Δ
- Pf×
V of the decrement Δ
Pf of said pressure Pf in a predetermined time period and said tank volume V to an integral value Σ
R of said mass flow rate, or a difference therebetween, (6) determining a calibrating comparator Ai represented by a ratio of the product Δ
Pi×
V of pressure decrement Δ
Pi in a predetermined time period and said tank volume V to an integral value Σ
Ri of the mass flow rate, or difference therebetween, from reference pressure Pi and mass flow rate Ri measured in an initial state in the same way as in said step (1)-(4), and (7) performing calibration depending on a variation ratio H represented by the formula of H=[1−
(Af/Ai)]×
100 (%).
- Pf×
Specification