Plasma Chamber Temperature Control Using Proportional and Pulsed Valves
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Solution Overview
Problem
Conventional plasma processing systems face challenges in effectively controlling chamber component temperatures due to limitations in heat transfer fluid flow rate modulation and mechanical failures caused by abrupt valve closures, leading to inefficiencies and potential system failures.
Innovation Solution
The use of a combination of proportional and pulsed fluid control valves, where proportional valves provide analog heat transfer fluid flow rate control and digital valves cycle the fluid loop between a heat sink and source, preventing fluid mixing and reducing mechanical stress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If digital valves with pulse wave modulation are used to change duty cycle of heat transfer liquid, then temperature control responsiveness is improved, but valve lifetime is reduced due to frequent actuation
Solution Approach 1:
The patent applies periodic action by using pulse wave modulation to cycle the heat transfer liquid flow in periodic pulses rather than continuous flow. This allows the system to achieve rapid temperature control responsiveness through on/off cycling while reducing the frequency of full valve actuation events, thereby extending valve lifetime.
Solution Approach 2:
The system dynamically adjusts the duty cycle of the pulsed valve operation to optimize between responsiveness and valve wear. By varying the on/off timing and duration dynamically based on temperature feedback, the system achieves fast response when needed while minimizing unnecessary valve actuations that would reduce valve lifetime.
2Manufacturing precision
If digital valves are used to cycle heat transfer liquid between heat sink and source, then temperature control precision is improved, but mechanical failures increase due to abrupt valve closures causing fluid hammer
Solution Approach 1:
The patent implements beforehand cushioning by incorporating gradual valve closure sequences before complete shut-off. This gradual closing reduces the abrupt momentum changes that cause fluid hammer, cushioning the pressure waves before they can build up to dangerous levels that would cause mechanical failures.
Solution Approach 2:
The system uses an intermediary gradual closure phase between the open and fully closed valve states. This intermediary state allows the valve to reduce flow progressively rather than abruptly, mediating the momentum transfer and preventing the pressure surges associated with fluid hammer while maintaining temperature control precision.
3Measurement precision
If heat transfer liquid flow rate is modulated based on temperature control algorithm, then temperature control accuracy is improved, but system complexity increases
Solution Approach 1:
The patent applies feedback control by continuously monitoring the temperature of the chamber component and using this feedback to dynamically adjust the heat transfer liquid flow rate. The temperature sensor provides real-time feedback to the control algorithm, which then modulates the valve duty cycle to maintain the desired temperature setpoint, achieving high accuracy through closed-loop control.
Solution Approach 2:
The system changes the flow rate parameter dynamically based on temperature feedback rather than using fixed flow rates. By modulating the duty cycle parameter of the pulsed valve operation, the system adjusts the average heat transfer liquid flow rate to match the thermal demands of the process, achieving accurate temperature control through parameter optimization.
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
This approach enhances temperature control responsiveness, minimizes overshoot, extends digital valve lifetime, and reduces the risk of mechanical failures by allowing controlled fluid flow and reducing fluid hammer effects.
Implementation Method 1
Proportional control valves having a partially open state may be utilized to provide analog heat transfer fluid flow rate control
Implementation Method 2
digital control valves lacking a partially open state are utilized to cycle or 'pulse' a heat transfer fluid loop between an external heat sink and a heat source
Implementation Method 3
a heat transfer fluid loop thermally coupled to the chamber component is utilized to provide heating and/or cooling power
Data Source
AI summary
Methods and systems for controlling temperatures in plasma processing chamber with a combination of proportional and pulsed fluid control valves. A heat transfer fluid loop is thermally coupled to a chamber component, such as a chuck. The heat transfer fluid loop includes a supply line and a return line to each of hot and cold fluid reservoirs. In an embodiment, an analog valve (e.g., in the supply line) is controlled between any of a closed state, a partially open state, and a fully open state based on a temperature control loop while a digital valve (e.g., in the return line) is controlled to either a closed state and a fully open state.