Plasma Stage Refrigerant Isolation for Wafer Cooling Maintenance
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Solution Overview
Problem
Current plasma processing apparatuses face challenges in quickly and accurately controlling wafer surface temperatures during etching, especially with larger wafers and higher etching rates, leading to excessive temperature rises and non-uniformity, and existing maintenance methods require refrigerant disposal, increasing downtime, cost, and environmental burden.
Innovation Solution
A plasma processing apparatus with a direct expansion refrigerating system and a maintenance method that separates refrigerant flow paths to temporarily store refrigerant during maintenance, allowing for reuse without refrigerant discharge, and includes a check valve and control unit to manage the refrigerating cycle components, reducing the amount of refrigerant discharged and enabling maintenance of components other than the sample stage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a direct expansion refrigerating system is used for quick temperature control, then temperature control speed and efficiency are improved, but maintenance becomes more complex requiring refrigerant handling procedures
Solution Approach 1:
The refrigerant flow path is divided into a first flow path section (from expansion valve through evaporator to check valve) and a second flow path section (from check valve through compressor and condenser to expansion valve), which can be separately isolated and maintained. This segmentation allows maintenance of one section without affecting the other, reducing maintenance complexity while preserving the direct expansion cooling capability.
Solution Approach 2:
A check valve is introduced as an intermediary component between the first and second flow path sections. This check valve enables controlled isolation of the evaporator section from the rest of the refrigerating cycle, allowing refrigerant to be temporarily stored in the second section while the first section is opened for maintenance, thus simplifying the maintenance process.
2Ease of repair
If refrigerant is discharged during maintenance, then maintenance operations are simplified, but environmental burden and refrigerant loss increase
Solution Approach 1:
Instead of discharging refrigerant to the atmosphere during maintenance, the system recovers and temporarily stores the refrigerant in the second flow path section (compressor and condenser side). This allows the evaporator section to be opened for maintenance while preserving the refrigerant for later reuse, eliminating both environmental burden and refrigerant loss.
3Ease of repair
If the refrigerating cycle is opened for maintenance, then component access is improved, but refrigerant discharge becomes necessary
Solution Approach 1:
The refrigerating cycle is segmented into two independently maintainable sections by the check valve. The first section (evaporator side) can be isolated and opened for maintenance while the second section (compressor and condenser side) retains the refrigerant, allowing component access without mandatory refrigerant discharge.
Solution Approach 2:
The check valve acts as an intermediary that enables selective opening of the evaporator section while preventing refrigerant leakage to the atmosphere. It allows the maintenance of components in the first section without requiring the entire refrigerating cycle to be opened or the refrigerant to be discharged.
4Productivity
If larger power is applied for higher etching rates, then productivity is improved, but wafer temperature control difficulty increases
Solution Approach 1:
The direct expansion refrigerating system utilizes the phase transition of refrigerant from liquid to vapor in the evaporator to provide efficient cooling. This phase change process absorbs large amounts of latent heat, enabling effective temperature control even under high power conditions, thus maintaining wafer temperature uniformity during high-rate etching 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
This approach allows for efficient and quick temperature control of wafers during etching, reduces apparatus downtime and maintenance costs, and minimizes environmental impact by avoiding refrigerant disposal, while enabling maintenance of the refrigerating cycle components without altering the refrigerant amount.
Implementation Method 1
the sample stage is cooled by evaporating the refrigerant in a refrigerant flow path formed in the sample stage
Implementation Method 2
a direct expansion refrigerating system makes use of the latent heat of refrigerant vaporization, its cooling efficiency is high
Implementation Method 3
a condenser for condensing the compressed refrigerant
Data Source
AI summary
In a plasma processing apparatus, a check valve is installed close to a refrigerant inlet of a compressor. When performing maintenance of a sample stage, refrigerant collected from a refrigerant flow path is temporarily stored in a flow path section extending from an expansion valve to the check valve, making it possible to perform the maintenance without changing the amount of refrigerant in the refrigerating cycle. With a refrigerant storage tank, a refrigerant supply valve, and a refrigerant discharge valve included in the refrigerating cycle, when maintenance of the compressor, a condenser, or the expansion valve is performed, the refrigerant collected from the refrigerating cycle can be put in use again.