Cleaning Endpoint Detection via Pressure Monitoring
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Solution Overview
Problem
Current methods for determining the completion of cleaning processes in semiconductor processing chambers, such as using OES or RGA systems, are expensive and impractical, and there is a need for a more accurate and cost-effective way to ensure optimal cleaning duration without damaging the chamber surfaces.
Innovation Solution
A system that monitors the flow rate of cleaning gas into or out of the processing chamber, using either upstream or downstream pressure control configurations, to detect changes indicative of the completion of the cleaning process, allowing for termination of the process based on reaching a new steady state value.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If OES or RGA systems are used to determine cleaning process completion, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent uses a pressure sensor to monitor gas pressure changes as a proxy indicator for cleaning process completion, rather than directly measuring residual material or halogen gas concentration. This indirect measurement approach achieves sufficient endpoint detection accuracy without requiring complex OES or RGA systems, effectively using a simple pressure reading to represent the cleaning state
Solution Approach 2:
The invention replaces expensive, complex instrumentation (OES and RGA systems) with a simple, inexpensive pressure sensor that can be easily integrated into existing vacuum systems. The pressure sensor provides cost-effective endpoint detection without the high equipment costs and operational complexity of spectroscopic or mass spectrometric systems
2Reliability
If cleaning process duration is extended to remove all residual material, then cleaning effectiveness is improved, but harmful factors increase due to halogen species attacking chamber surfaces
Solution Approach 1:
The system continuously monitors gas pressure during the cleaning process and uses this feedback to determine when to terminate the cleaning cycle. When the pressure reaches a predetermined threshold indicating sufficient cleaning, the system automatically stops the process, preventing over-cleaning that would cause halogen species to attack and damage the chamber surfaces
Solution Approach 2:
The patent establishes predetermined pressure thresholds and termination criteria before the cleaning process begins. By pre-setting the endpoint conditions based on pressure readings, the system is prepared to stop the cleaning process at the optimal moment, ensuring complete residue removal while preventing surface damage from excessive halogen exposure
3Object-affected harmful factors
If cleaning process duration is shortened to prevent chamber surface attack, then harmful factors are reduced, but cleaning effectiveness decreases
Solution Approach 1:
The real-time pressure monitoring provides continuous feedback on the cleaning progress, allowing the system to extend the cleaning duration as needed to achieve complete residue removal. The pressure readings indicate when residual material is being effectively removed, enabling the process to continue long enough for thorough cleaning without relying on fixed time schedules that might be too short
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 effectively determines the completion of the cleaning process without expensive instrumentation, ensuring thorough removal of residual material while preventing damage to the chamber surfaces, and achieves results comparable to OES and RGA systems.
Implementation Method 1
a downstream pendulum valve is used to maintain the pressure within the processing chamber at a predetermined value
Implementation Method 2
a sensor may be used to monitor the pressure within the processing chamber
Implementation Method 3
The halogen species interacts with the residual material to create gaseous materials
Implementation Method 4
gaseous materials, which can be expelled through the vacuum pump
Data Source
AI summary
A system for determining when a cleaning process has completed is disclosed. This system relies on an increase in the amount of gas in the processing chamber that occurs when the cleaning is complete. This increase in the amount of gas may be detected in several ways. In one embodiment, a downstream pendulum valve is used to maintain the pressure within the processing chamber at a predetermined value. An increase in the size of the opening in the pendulum valve is indicative of the amount of gas in the system. In another embodiment, a sensor may be used to monitor the pressure within the processing chamber, while the incoming and outgoing flow rates are held constant. An increase in the pressure is indicative of an increase in the amount of gas in the processing chamber. This increase in the amount of gas is used to terminate the cleaning process.