Abstract: This disclosure relates to mass flow verification systems for and methods of measuring and verifying the mass flow through a mass flow delivery/measurement device such as a mass flow controller. A mass flow verification system comprises a preset volume, a temperature sensor, and a pressure sensor. The measured verified flow determined by the mass flow verification system can be adjusted to compensate for errors resulting from a dead volume within the mass flow measurement device.

Abstract: This disclosure relates to mass flow verification systems for and methods of measuring and verifying the mass flow through a mass flow delivery/measurement device such as a mass flow controller. A mass flow verification system comprises a preset volume, a temperature sensor, and a pressure sensor. The measured verified flow determined by the mass flow verification system can be adjusted to compensate for errors resulting from a dead volume within the mass flow measurement device.

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: 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: 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.

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: 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 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.