Variable-Orifice Mass Flow Verification Using Pressure Rate-of-Rise
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Solution Overview
Problem
Conventional methods for verifying and calibrating Mass Flow Controllers (MFCs) in semiconductor manufacturing are inaccurate due to drift and miscalibration, leading to defects and inefficiencies, and lack mobility and accurate replication of process pressure conditions.
Innovation Solution
A system and method for variably choked pressure rate-of-rise mass flow verification using a controller and mass flow verifier with a rate-of-rise volume, variable orifice, and pressure sensors to establish a choked pressure regime, allowing for precise flow rate measurements and corrections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional methods are used for verifying and calibrating Mass Flow Controllers, then the verification process is simple, but the accuracy of flow rate measurements deteriorates due to drift and miscalibration
Solution Approach 1:
The verification system is segmented into distinct functional modules: a mass flow controller for gas delivery, a variable orifice for pressure regime control, pressure sensors for measurement, and a controller for coordination. This segmentation allows each component to be optimized independently while maintaining overall system accuracy and reducing the complexity of the verification process.
Solution Approach 2:
The system changes the pressure parameter by establishing a choked pressure regime (where upstream pressure is at least two times downstream pressure) through the variable orifice. This parameter change enables accurate flow rate verification by creating controlled conditions that eliminate drift and miscalibration errors affecting conventional methods.
2Adaptability or versatility
If a fixed verification system is used, then the system structure is simple, but the adaptability to different chambers and flow rates deteriorates
Solution Approach 1:
The verification system is designed with universal components that can be applied across different semiconductor manufacturing chambers. The mass flow controller, variable orifice, and pressure sensors form a modular assembly that can be adapted to various chamber types and flow rate requirements, enabling the same system to verify multiple MFCs under different operating conditions.
Solution Approach 2:
The variable orifice provides dynamic control over the pressure regime, allowing the system to adapt to different flow rates and chamber conditions. The controller dynamically adjusts the orifice opening to maintain the choked pressure regime (upstream pressure at least two times downstream pressure) across varying operating parameters, ensuring accurate verification regardless of the specific chamber or flow rate being tested.
3Reliability
If conventional verification methods are used, then the equipment is simple, but the replication of process pressure conditions deteriorates
Solution Approach 1:
The system actively controls and replicates process pressure conditions by establishing a choked pressure regime through the variable orifice. By maintaining upstream pressure at least two times downstream pressure, the system recreates the pressure differential conditions found in actual semiconductor manufacturing processes, ensuring that MFC verification reflects real operating conditions and improving reliability.
Solution Approach 2:
The variable orifice acts as an intermediary component that mediates between the gas source and the chamber, enabling precise control over pressure conditions. This intermediary element allows the verification system to replicate process pressure conditions by creating the appropriate pressure differential, ensuring accurate MFC verification under conditions that match actual manufacturing processes.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enhances accuracy of flow rate measurements, supports a broad range of testable flow rates, replicates process pressure conditions, and facilitates easy transfer between chambers, reducing defects and improving production efficiency.
Implementation Method 1
actuating an opening of the variable orifice to establish a choked pressure regime within the chamber, where the choked pressure regime is achieved by causing a first pressure upstream of the variable orifice to be at least two times a second pressure downstream of the variable orifice
Implementation Method 2
subsequently determining a pressure rate-of-rise by measuring a pressure rate-of-rise within the chamber
Data Source
AI summary
A method includes opening a flow path from a gas stick through a variable orifice, a chamber, and an outlet isolation valve of the chamber. The method further includes causing a gas to flow through the flow path at a flow rate setpoint. The method further includes actuating an opening of the variable orifice to establish a choked pressure regime within the chamber, the choked pressure regime being achieved by causing a first pressure upstream of the variable orifice to be at least two times a second pressure downstream of the variable orifice. The method further includes closing the outlet isolation valve to cause the chamber to be filled with the gas from the gas stick. The method further includes measuring a pressure rate-of-rise within the chamber. The method further includes determining one or more flow measurements based at least in part on the pressure rate-of-rise.