US 9,169,975 B2Granted

Systems and methods for mass flow controller verification

AssigneeASM IP Holding B.V.

InventorsMichael Christopher Sarin, Rafael Mendez, Gregory M. Bartlett, Eric Hill, Keith R. Lawson, Andy Rosser

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Abstract

A method and system are disclosed for verifying the flow rate of gas through a mass flow controller, such as a mass flow controller used with a tool for semiconductor or solar cell fabrication. To verify the mass flow rate measured by the mass flow controller, gas passing through the mass flow controller is also passed through a mass flow meter. The measured flow rate through the mass flow controller is compared to the measured flow rate through the mass flow meter and any difference between the two measured flow rates is determined. Depending upon the magnitude of any difference, the flow of gas to the mass flow controller may be altered.

Claims34

Dependent claims

A method of verifying the flow rate of gas through a mass flow controller, the method comprising the steps of:

(a) measuring a flow of a first gas through a mass flow controller that is calibrated for a second gas,
(b) measuring the actual flow of the first gas through at least three mass flow meters,
wherein each of a first mass flow meter, a second mass flow meter and a third mass flow meter are calibrated for the first gas,
wherein the first flow meter is configured to measure a first actual flow, the second flow meter is configured to measure a second actual flow, and the third flow meter is configured to measure a third actual flow;
(c) comparing the first actual flow, the second actual flow, and the third actual flow to determine a match between at least two of the first actual flow, the second actual flow, and the third actual flow;
(d) determining a control flow based on the comparing;
(e) based on the second gas for which the mass flow controller is calibrated, select a scaling factor to apply to the measured flow of the first gas through the mass flow controller;
(f) scale the measured flow of the first gas through the mass flow controller using the scaling factor to determine a scaled measured flow of the first gas through the mass flow controller;
(g) compare the scaled measured flow of the first gas through the mass flow controller to the control flow;
and
(h) determine the difference between the scaled measured flow of the first gas through the mass flow controller to the control flow,
wherein the first gas and the second gas selectively flow through the mass flow meter or to a tool.

9 more elements

A system for verifying the flow rate of gas through a mass flow controller, the system comprising:

(a) a mass flow controller fluidly coupled to a tool, wherein the mass flow controller is calibrated for a second gas and configured to measure the flow rate for a first gas;
(b) a storage device including one or more scaling factors to scale the flow rate of the second gas to a flow rate of a first gas;
(c) a plurality of mass flow meters configured to measure a first actual flow, a second actual flow, and a third actual flow for the first gas flowing therethrough,
wherein the mass flow controller is interposed between the mass flow meter and the tool;
(d) a controller configured to compare the first actual flow, the second actual flow, and the third actual flow to determine a match between at least two of the first actual flow, the second actual flow, and the third actual flow, the controller configured to determine a control flow based on the match;
and
(e) a valve having a first position wherein gas exiting the mass flow controller is directed through the plurality of mass flow meters and a second position wherein gas exiting the mass flow controller is not directed through the plurality of mass flow meters,
whereby when the valve is in its first position the measured amount of first gas flow rate through the mass flow controller can be verified by utilizing the scaling factor and comparing the control flow from the plurality of mass flow meters.

5 more elements

Dependencies are inferred from the claim text.