Abstract: A high accuracy mass flow verifier (HAMFV) which provides high measurement accuracy over a wide flow verification range with low inlet pressures is disclosed for verifying flow measurement by a fluid delivery device. The HAMFV includes a chamber defining a plurality N of inlets with upstream valves, an outlet with a downstream valve, a pressure sensor and a temperature sensor configured to measure the pressure and the temperature of the fluid within the chamber, respectively. A plurality N of critical flow nozzles is located adjacent to the corresponding upstream valve. The HAMFV further includes a controller configured to activate one of the plurality N of critical flow nozzles based on the desired flow verification range and the fluid type by opening the corresponding upstream valve and closing all other upstream valves. At least two of the plurality N of critical flow nozzles have different cross-sectional areas.

Abstract: A flow verifier for verifying measurement by a fluid delivery device under test (DUT) includes a chamber configured to receive a flow of the fluid from the DUT, at least one temperature sensor to provide gas temperature in the chamber, at least one pressure transducer to provide gas pressure in the chamber, and a critical flow nozzle located upstream of the chamber along a flow path of the fluid from the DUT to the chamber. The critical flow nozzle and the flow verification process are configured to maintain the flow rate of the fluid through the nozzle at the critical flow condition such that the flow rate through the nozzle is substantially constant and substantially insensitive to any variation in pressure within the chamber downstream of the nozzle.

Abstract: A thermal mass flow controller for controlling flow rate of a fluid includes a conduit configured to receive the fluid, a pressure sensor that measures the pressure of the fluid as the fluid flows within the conduit, a temperature sensor that measures the ambient temperature of the fluid, and a thermal sensor that generates an output representative of the flow rate of the fluid. The thermal mass flow controller further includes a control system configured to monitor the output from the thermal sensor, the pressure measured by the pressure sensor, and the ambient temperature measured by the temperature sensor, to regulate flow of the fluid within the conduit so as to compensate for a shift in the thermal sensor output caused by thermal siphoning.

Abstract: Embodiments of the present disclosure are directed to systems, methods, and apparatus, including software implementation, useful for high-precision measurement of mass flow rate over a large range of flows by using multiple volumes, each having a different and selected size. Use of a single manometer can facilitate reduced cost, and the use of multiple chamber volumes that are sized according to sub-flow ranges within the overall range of the mass flow verifier, or a related device under test, can provide high accuracy while reducing deleterious effects of noise in the flow measurement.

Abstract: A mass flow device comprises an inlet and an outlet; a bypass and a laminar flow element disposed within the bypass. The device also includes a sensor constructed so as to provide an output signal representative of the flow rate through the mass flow device, the sensor including a tube in fluid communication with the inlet and the laminar flow element at an upstream connection location, and the outlet and the laminar flow element at a downstream connection location. A flow equalizer is disposed between the inlet and the upstream connection location, wherein the flow equalizer includes a porous medium constructed with an interconnected porosity so as to greatly reduce the flow disturbance to the sensor with an approximate equalized flow pattern exiting the equalizer.

Abstract: An integrated pressure and flow ratio control system includes N mass flow controllers MFCi (i=1, . . . , N) that each control the flow rate of a fluid Fi (i=1, . . . , N) flowing into a processing chamber. These N mass flow controllers are linked together by a digital communication network. One of the mass flow controllers is a master MFC, and the remaining N-1 MFCs are slave MFCs. The master MFC receives a pressure set point and a plurality N of flow ratio set points from a host controller, and communicates these set points to all the slave MFCs. In this way, the pressure in the chamber is maintained at the pressure set point and the flow ratios Qi/QT are maintained at the flow ratio set points, where Qi is flow rate of the i-th fluid Fi, and QT=Q1+Q2+ . . . QN is the sum of all N flow rates.

Abstract: A mass flow controller having a feedback controller gain, comprises: a sensor configured so as to sense the flow of fluid through controller; a valve arranged so as to adjust the flow of fluid through the controller; and a processor configured so as to controlling the valve as a function of the flow of fluid sensed by the sensor. The sensor and valve are arranged within a feedback system, and the processor updates the feedback controller gain in real time based on the ratio of at least one calibration gas parameter to at least one operating gas parameter, such that the closed loop transfer function of the feedback system remains substantially constant regardless of operating conditions so as to have a consistent control performance at different operation conditions from the calibration condition.

Abstract: A thermal mass flow meter for measuring flow rate of a fluid includes a conduit that is configured to receive the fluid and that defines a primary flow path between an inlet and an outlet of the conduit. The conduit is bound at least in part by a sensor receiving surface. A thermal sensor tube has a thermal sensing portion that is mounted relative to the sensor receiving surface in a direction substantially perpendicular to both the primary flow path and the sensor receiving surface. When the thermal mass flow meter is mounted in a vertical direction so that fluid within the conduit flows in the vertical direction along the primary flow path, fluid within the sensor tube flows in a horizontal direction so as to substantially prevent thermal siphoning when the sensor tube is heated.

Abstract: A system for dividing a single mass flow into a plurality N of secondary flows includes an inlet configured to receive the single mass flow, a master FRC (flow ratio controller), and one or more slave FRCs. Each FRC is connected to the inlet and including at least one flow channel. The master FRC and the slave FRCs include in combination a total of N flow channels. Each flow channel i (i=1, . . . , N) is connected to carry a corresponding one of the N secondary flows. In response to preselected ratio setpoints received from a host controller, the master FRC and the slave FRCs maintain ratios Qi/QT (i=1, . . . , N) between individual flow rates Qi (i=1, . . . , N) and a total flow rate QT at the preselected ratio set points.

Abstract: The multiple antisymmetric optimal (MAO) control algorithm is disclosed for a gas delivery system including a flow ratio controller for dividing a single mass flow into multiple flow lines. In the MAO control algorithm, each flow line is provided with a flow sensor and a valve actively controlled by a SISO feedback controller combined with a linear saturator to achieve the targeted flow ratio set point. For optimal control performance, these SISO controller and linear saturators are substantial identical. It is proved that each valve control command is multiple antisymmetric to the summation of all other valve control commands. Therefore, the MAO control algorithm guarantees that there exists at least one valve at the allowable maximum open position at any moment, which achieves the optimal solution in terms of the maximum total valve conductance for a given set of flow ratio set points.

Abstract: A thermal mass flow controller for controlling flow rate of a fluid includes a conduit configured to receive the fluid, a pressure sensor that measures the pressure of the fluid as the fluid flows within the conduit, a temperature sensor that measures the ambient temperature of the fluid, and a thermal sensor that generates an output representative of the flow rate of the fluid. The thermal mass flow controller further includes a control system configured to monitor the output from the thermal sensor, the pressure measured by the pressure sensor, and the ambient temperature measured by the temperature sensor, to regulate flow of the fluid within the conduit so as to compensate for a shift in the thermal sensor output caused by thermal siphoning.

Abstract: A thermal mass flow meter for measuring flow rate of a fluid includes a conduit that is configured to receive the fluid and that defines a primary flow path between an inlet and an outlet of the conduit. The conduit is bound at least in part by a sensor receiving surface. A thermal sensor tube has a thermal sensing portion that is mounted relative to the sensor receiving surface in a direction substantially perpendicular to both the primary flow path and the sensor receiving surface. When the thermal mass flow meter is mounted in a vertical direction so that fluid within the conduit flows in the vertical direction along the primary flow path, fluid within the sensor tube flows in a horizontal direction so as to substantially prevent thermal siphoning when the sensor tube is heated.

Abstract: A flow verifier for verifying measurement by a fluid delivery device under test (DUT) includes a chamber configured to receive a flow of the fluid from the DUT, at least one temperature sensor to provide gas temperature in the chamber, at least one pressure transducer to provide gas pressure in the chamber, and a critical flow nozzle located upstream of the chamber along a flow path of the fluid from the DUT to the chamber. The critical flow nozzle and the flow verification process are configured to maintain the flow rate of the fluid through the nozzle at the critical flow condition such that the flow rate through the nozzle is substantially constant and substantially insensitive to any variation in pressure within the chamber downstream of the nozzle.

Abstract: The antisymmetric optimal control algorithm is disclosed for a gas delivery system including a flow ratio controller for dividing a single mass flow into at least two flow lines. Each flow line includes a flow meter and a valve. Both valves of the flow ratio controller are controlled through a ratio feedback loop by the antisymmetric optimal controller which includes a single input single output SISO controller, an inverter and two linear saturators. The output of the SISO controller is split and modified before being applied to the two valves. The two valve control commands are virtually antisymmetric to the maximum allowable valve conductance position.