Piezo Valve Position Control for Reproducible Flow Ratios
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional flow ratio control systems in substrate processing face challenges such as limited adjustability, high cost, space inefficiency, sensor deterioration due to corrosive environments, and reactive control leading to hysteresis and reproducibility issues, resulting in incorrect flow ratios and substrate defects.
Innovation Solution
Implementing piezo position control with a fluid conductance map to proactively set valve positions based on recipe requirements, using displacement devices and sensors outside the wetted flow path to avoid sensor degradation and improve throughput.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional flow ratio control systems are used, then flow control is achieved, but the system suffers from limited adjustability, high cost, and space inefficiency
Solution Approach 1:
The patent replaces conventional mechanical flow control systems with a piezoelectric-based control system. The piezoelectric actuator converts electrical signals directly into mechanical displacement to control valve positions, eliminating the need for complex mechanical linkages and providing precise, programmable flow ratio control with improved adaptability and reduced device complexity.
Solution Approach 2:
The system uses piezoelectric materials that change their physical dimensions (expand or contract) in response to applied voltage. This parameter change allows dynamic adjustment of valve opening positions, enabling continuous and precise control of flow ratios without mechanical reconfiguration, thereby improving adaptability while simplifying the overall system architecture.
2Measurement precision
If sensors are placed in the wetted flow path for feedback control, then measurement is achieved, but sensor deterioration occurs due to corrosive environments
Solution Approach 1:
The patent extracts the measurement function from the corrosive wetted environment by placing sensors in a non-wetted location. The system uses a piezoelectric actuator with integrated displacement sensing that measures valve position without requiring sensors to be in direct contact with the process fluid, thereby maintaining measurement precision while eliminating sensor deterioration from corrosive exposure.
Solution Approach 2:
The patent introduces an intermediary measurement approach where the piezoelectric actuator's own displacement is measured to infer flow control status, rather than directly measuring flow parameters in the corrosive environment. This intermediary measurement method protects sensors from corrosive damage while maintaining the ability to achieve precise flow ratio control through feedback.
3Speed
If reactive control is used, then response to flow changes is achieved, but hysteresis and reproducibility issues occur
Solution Approach 1:
The patent implements proactive control by using the fluid conductance map to pre-determine the required valve positions for desired flow ratios before the process begins. The piezoelectric actuator is commanded to these pre-calculated positions based on recipe requirements, eliminating the hysteresis and reproducibility issues associated with reactive control while maintaining fast response speed.
Solution Approach 2:
The system employs feedback control where the actual valve position, measured by the displacement sensor on the piezoelectric actuator, is continuously monitored and compared against the target position from the fluid conductance map. This closed-loop feedback ensures high flow ratio reproducibility by correcting any deviations, while the piezoelectric system's inherent fast response capability maintains high speed performance.
4Device complexity
If passive control or fixed orifice systems are used, then simple control is achieved, but applicability is limited
Solution Approach 1:
The patent transforms the static, fixed orifice control system into a dynamic system using piezoelectric actuators that can continuously adjust valve opening positions. This dynamic capability allows the system to adapt to different recipe requirements and process conditions, significantly expanding applicability while maintaining relative simplicity through electronic control compared to multiple fixed orifice configurations.
Solution Approach 2:
The piezoelectric-based flow control system serves multiple functions: it can control flow ratios for different recipes, adapt to varying process conditions, and provide both proactive positioning and feedback control. This multi-functionality replaces the need for multiple specialized control systems, increasing versatility while keeping the overall device complexity manageable through a unified control architecture.
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 throughput by accurately anticipating flow ratios, reducing maintenance and substrate defects, and increasing the system's applicability beyond passive and fixed orifice systems.
Implementation Method 1
causing, by a processing device based on a recipe and the fluid conductance map, the first valve to be in a first valve position and the second valve to be in a second valve position
Data Source
AI summary
A flow ratio controller (FRC) valve includes a displacement device configured to control fluid flow through the FRC valve, a displacement sensor coupled to the displacement device, and a processing device. The processing device is to: identify an input signal indicative of a first setpoint to preposition the displacement device for a process of a recipe; commence, based on the input signal, adjustment of physical displacement of the displacement device; determine, based on a feedback signal received from the displacement sensor during the adjustment, whether the physical displacement of the displacement device matches the first setpoint; and responsive to determining that the physical displacement of the displacement device matches the first setpoint, stop the adjustment of the physical displacement of the displacement device.