Wafer Stage Cooling System with Compressor Speed Control
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Solution Overview
Problem
The existing refrigerant supply devices for plasma processing apparatuses face challenges in achieving high cooling capability with low power consumption, particularly due to excessive heat input from high-frequency electric power, leading to inefficient temperature control and increased power consumption.
Innovation Solution
The direct-expansion cooling system optimizes refrigerant circulation by measuring the degree of dryness and controlling the compressor's rotational speed, reducing refrigerant circulation to prevent dry-out and minimize power consumption, thereby improving the coefficient of performance (COP) and achieving uniform temperature distribution across the wafer surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a conventional refrigerant supply device with large heat capacity is used to maintain stable wafer temperature, then temperature stability is improved, but temperature response speed and heat exchange efficiency deteriorate
Solution Approach 1:
The patent applies phase transition of refrigerant (liquid to vapor) in the evaporator to achieve high-efficiency heat exchange. The refrigerant absorbs latent heat during evaporation, providing rapid cooling with high heat exchange efficiency while maintaining temperature stability through controlled phase change rather than relying on large heat capacity materials.
2Productivity
If high-frequency electric power is increased to improve etching rate, then productivity is improved, but wafer temperature rises excessively
Solution Approach 1:
The direct-expansion cooling system utilizes refrigerant phase transition (evaporation) to absorb excessive heat from the wafer stage. The latent heat absorption during phase change provides efficient cooling that can handle the high heat input from increased electric power while maintaining wafer temperature within required limits.
Solution Approach 2:
The system incorporates temperature sensors and control mechanisms that monitor wafer stage temperature and adjust refrigerant flow and compressor operation accordingly. This feedback control ensures that cooling capacity matches the heat input from plasma processing, maintaining temperature stability even at high power levels.
3Loss of energy
If a direct-expansion cooling system is used to achieve high cooling efficiency, then heat exchange efficiency is improved, but power consumption increases
Solution Approach 1:
The system exploits the latent heat of vaporization during refrigerant phase change to achieve high cooling efficiency. This phase transition mechanism provides superior heat exchange efficiency compared to conventional liquid cooling, as the latent heat absorption occurs at constant temperature, maximizing cooling effectiveness per unit of refrigerant.
Solution Approach 2:
The system dynamically adjusts refrigerant flow rate and compressor operation based on real-time temperature measurements and process conditions. This dynamic control optimizes the balance between cooling efficiency and power consumption, ensuring that the direct-expansion system operates at peak efficiency only when high cooling demand exists.
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 cooling capability while reducing power consumption, ensuring efficient temperature control and in-plane temperature uniformity with a higher COP, addressing the limitations of conventional systems.
Implementation Method 1
a refrigerant circulation system evaporates a refrigerant in a refrigerant passage of the wafer stage to cool the wafer stage
Implementation Method 2
The direct-expansion cooling system that uses latent heat generated by refrigerant evaporation exhibits high cooling efficiency
Implementation Method 3
a compressor for applying a high pressure to the refrigerant
Implementation Method 4
a condenser for condensing the high-pressure refrigerant
Implementation Method 5
an expansion valve for expanding the refrigerant
Data Source
AI summary
A plasma processing apparatus includes a processing chamber, a wafer table, a refrigerant passage disposed inside the wafer table in which a refrigerant flows, a refrigeration cycle comprising the refrigerant passage in the wafer table as a first evaporator in which the refrigerant is evaporated as a result of a heat-exchange therein, a compressor, a condenser and an expansion valve, a second evaporator, and a controlling unit which adjusts a number of rotations of the compressor based upon a degree of dryness of the refrigerant at a position on the refrigeration cycle after passing through the first evaporation in a range in which dry-out does not occur in the first evaporator, and the dryness of the refrigerant being determined based upon an amount of a heat exchange during the evaporation of the refrigerant in the second evaporator.