Phosphoric Acid Etch Control Using Reflected Light Feedback
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Solution Overview
Problem
Existing substrate processing methods for selectively etching silicon nitride films relative to silicon oxide films face challenges in maintaining consistent phosphoric acid solution concentration and composition, leading to variations in etching processes.
Innovation Solution
A substrate processing apparatus with a light irradiation and detection system that controls the chemical supply and discharge based on reflected light intensity, ensuring optimal phosphoric acid solution concentration and composition for each etching process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If phosphoric acid solution is partially replaced and reused multiple times, then productivity is improved by reducing chemical consumption, but manufacturing precision deteriorates due to concentration variations affecting etching consistency
Solution Approach 1:
The system uses a light detection part to measure reflected light intensity from the substrate, providing real-time feedback on phosphoric acid solution concentration. The control device adjusts chemical supply based on this feedback, maintaining consistent etching performance while allowing solution reuse. This closed-loop control enables multiple uses of the same chemical solution without sacrificing etching precision.
Solution Approach 2:
The system dynamically adjusts the concentration parameter of the phosphoric acid solution by controlling chemical supply rates based on detected light intensity. By changing the chemical concentration parameter in real-time, the system maintains optimal etching conditions throughout multiple solution reuse cycles, preventing precision degradation.
2Manufacturing precision
If phosphoric acid solution concentration is maintained at optimal levels, then manufacturing precision is improved through consistent etching, but loss of substance increases due to continuous chemical supply and discharge
Solution Approach 1:
The light detection system continuously monitors solution concentration via reflected light intensity, enabling precise control that maintains optimal etching conditions only when necessary. This feedback mechanism prevents unnecessary chemical discharge and supply, reducing substance loss while preserving manufacturing precision.
Solution Approach 2:
Instead of continuously supplying and discharging chemical solutions, the system applies partial actions - supplying chemicals only when concentration drops below thresholds detected by the light measurement system. This approach maintains precision while minimizing unnecessary chemical consumption and waste.
3Manufacturing precision
If light irradiation and detection system is implemented for real-time monitoring, then manufacturing precision is improved through consistent solution state control, but device complexity increases
Solution Approach 1:
The light irradiation and detection system serves multiple functions: monitoring phosphoric acid solution concentration, detecting substrate state during etching, and providing feedback for chemical supply control. This multi-functionality justifies the added complexity by delivering comprehensive process control from a single integrated system.
Solution Approach 2:
The light detection system acts as an intermediary between the chemical solution and the control device, translating chemical concentration into measurable light intensity signals. This intermediary approach enables precise indirect measurement of solution state without requiring direct chemical analysis, simplifying the overall control architecture while maintaining precision.
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 consistent etching processes by adjusting the phosphoric acid solution in real-time, reducing process variations and maintaining the solution's state within predetermined tolerances, thereby improving the efficiency and reliability of silicon nitride film removal.
Implementation Method 1
a light irradiation part configured to irradiate light to the substrate taken out from the processing tank, a light detection part configured to detect reflected light generated from the light being reflected by the substrate
Data Source
AI summary
A substrate processing apparatus according to an embodiment includes a processing tank configured to store a chemical and perform processing by immersing a substrate in the chemical, a holder configured to hold the substrate and having a lifting part, a chemical liquid supply device configured to supply the chemical, a light irradiation part configured to irradiate light to the substrate taken out from the processing tank, the substrate being taken out from the processing tank by the lifting part after immersing the substrate in the chemical, a light detection part configured to detect reflected light generated from the light being reflected by the substrate, and a control device configured to control an amount of chemical supplied by the chemical liquid supply device in response to a detection result of the light detection part.