Wet Etching Control Using Surface Roughness Feedback
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Solution Overview
Problem
The challenge in wet etching processes is the alteration of wet chemistry over time, leading to inconsistent etching results, such as varying surface roughness, which affects the quality and reliability of semiconductor devices, and current methods using average wet chemistry lifetime lead to inefficiencies in processing time and resource consumption.
Innovation Solution
A method that uses measurement data to control wet etching process settings based on actual parameters like material removal, thickness, and surface roughness, allowing for real-time adjustments to maintain consistent quality by adjusting chemical liquid exchange, etching duration, composition, and distribution, using a data processing system to optimize the process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the wet chemistry is exchanged frequently based on average lifetime, then the etching quality consistency is improved, but the processing time increases and resource consumption increases
Solution Approach 1:
The patent implements a feedback mechanism where measurement data from test runs (etch rate, surface roughness, thickness) is continuously collected and used to dynamically adjust the wet chemistry exchange timing. Instead of following a fixed average lifetime schedule, the system monitors actual etching performance and triggers chemistry exchange only when measurement data indicates quality degradation, thereby eliminating unnecessary early exchanges that waste time and resources while maintaining etching consistency.
Solution Approach 2:
The system changes the parameter of chemistry exchange timing from a static value (average lifetime) to a dynamic value based on measured etching parameters. By monitoring etch rate, surface roughness, and thickness variations in real-time, the system adapts the chemistry lifetime parameter to actual process conditions, extending chemistry usage when quality remains stable and triggering earlier exchange only when necessary, thus resolving the contradiction between quality consistency and productivity.
2Manufacturing precision
If the wet chemistry is exchanged frequently based on average lifetime, then the etching quality consistency is improved, but the wet chemistry consumption increases
Solution Approach 1:
The feedback mechanism monitors actual etching performance through measurement data and dynamically determines chemistry exchange timing. By using real-time data on etch rate, surface roughness, and thickness, the system extends chemistry usage beyond the conservative average lifetime as long as quality parameters remain within specifications, thereby reducing chemistry consumption while maintaining etching consistency. Chemistry is exchanged only when measurement data indicates actual degradation.
Solution Approach 2:
The system enables the wet chemistry to 'serve itself' by using measurement data from the etching process to indicate when the chemistry has actually reached the end of its effective life. Instead of imposing an external fixed timeline, the process itself provides feedback through measurement data that signals when chemistry exchange is truly necessary, eliminating premature exchanges and reducing chemistry waste while maintaining quality.
3Manufacturing precision
If the safety margin is chosen high, then the etching quality consistency is improved, but the processing time increases and chemistry consumption increases
Solution Approach 1:
The system replaces fixed safety margins with dynamic feedback from measurement data. Instead of applying a conservative time-based safety margin that extends chemistry exchange intervals uniformly, the system monitors actual etching performance and adjusts exchange timing based on real-time data. This eliminates unnecessary time losses from overly conservative margins while maintaining quality through actual performance monitoring.
Solution Approach 2:
The patent changes the safety margin parameter from a static time-based value to a dynamic value based on measured etching parameters. By monitoring etch rate, surface roughness, and thickness variations, the system adapts the effective safety margin to actual process conditions, reducing time losses when chemistry performance remains stable while maintaining quality protection when degradation is detected.
4Productivity
If the safety margin is chosen low, then the processing time is reduced and chemistry consumption is reduced, but the etching quality consistency deteriorates
Solution Approach 1:
The feedback mechanism compensates for low safety margins by continuously monitoring measurement data from the etching process. Instead of relying on large fixed margins to ensure quality, the system uses real-time data on etch rate, surface roughness, and thickness to detect actual chemistry degradation. This allows the system to maintain high productivity with minimal margins while protecting quality through active monitoring and data-driven exchange decisions.
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 ensures consistent etching quality by minimizing resource waste and processing time, maintaining target surface roughness ranges, and optimizing the wet etching process through real-time adjustments.
Implementation Method 1
Wet etching is an etching process that takes off material from a specimen or, in other words, substrate material from a substrate by using a chemical liquid or, in other words, a liquid chemical, which may comprise one or more chemical etchants.
Data Source
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AI summary
The disclosure relates to a method (200) for controlling a wet etching process (131, 132, 133), the wet etching process (131, 132, 133) using a chemical liquid (18) comprising one or more chemical etchants for etching specimens (1), the method (200) comprising: - obtaining measurement data indicative of a material removal, a thickness and/or a surface roughness of one or more of the specimens (1) etched by the chemical liquid (18); and - obtaining control data for controlling one or more settings of the wet etching process (131, 132, 133) based on the measurement data.