Substrate Etching Control via Oxygen Concentration Differential
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Solution Overview
Problem
Conventional substrate processing methods face challenges in controlling the distribution of etching amounts over substrate surfaces due to the interdependence of dissolved oxygen concentrations in processing liquids and atmospheric oxygen levels, leading to non-uniform etching results.
Innovation Solution
A method and apparatus that determine and control the setting dissolved oxygen concentration and atmosphere oxygen concentration in conjunction with each other to achieve the desired etching distribution, using low oxygen gas supply and precise etching liquid delivery to maintain optimal oxygen levels, allowing for uniform or gradient etching patterns without moving the etching liquid's landing position.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the dissolved oxygen concentration of the processing liquid and the oxygen concentration in the atmosphere are minimized, then the etching rate is improved, but the uniformity of the etching is degraded
Solution Approach 1:
The invention changes the oxygen concentration parameter from a single-value minimization approach to a controlled difference approach. By maintaining a specific relationship between dissolved oxygen concentration in the processing liquid and oxygen concentration in the atmosphere (where the difference is controlled within a specific range), the system achieves both high etching rate and uniform etching distribution across the substrate surface.
Solution Approach 2:
The invention implements feedback control by continuously monitoring both the dissolved oxygen concentration in the processing liquid and the oxygen concentration in the atmosphere, then adjusting these parameters to maintain their difference within the optimal range. This feedback mechanism ensures that the etching process maintains both high productivity and manufacturing precision.
2Productivity
If the dissolved oxygen concentration of the processing liquid is reduced to increase etching rate, then the etching speed is improved, but the distribution of etching amount over the substrate surface becomes non-uniform
Solution Approach 1:
The invention transforms the parameter control strategy from independently minimizing dissolved oxygen concentration to controlling the difference between dissolved oxygen concentration and atmospheric oxygen concentration. By maintaining this difference within a specific range, the system achieves uniform etching distribution across the entire substrate surface while preserving high etching speed.
3Productivity
If low oxygen gas is supplied to reduce atmospheric oxygen concentration, then the etching rate is improved, but the control complexity of the processing system increases
Solution Approach 1:
The invention merges the control of dissolved oxygen concentration in the processing liquid with the control of atmospheric oxygen concentration. Instead of treating these as separate control variables, the system controls their difference as a single integrated parameter, thereby reducing control complexity while maintaining high etching rate.
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 enables precise control over the etching distribution, improving the uniformity and flatness of substrate surfaces by adjusting oxygen concentrations, allowing for either uniform etching or forming specific etching patterns like cones or inverted cones, thus enhancing processing efficiency.
Implementation Method 1
causing the low oxygen gas that has flowed into the chamber in the low oxygen gas supply step to be in contact with the etching liquid held on the main surface of the substrate
Data Source
AI summary
One of a setting dissolved oxygen concentration and a setting atmosphere oxygen concentration is determined based on a required etching amount. Thereafter, based on the required etching amount and the one of the determined setting dissolved oxygen concentration and setting atmosphere oxygen concentration, the other of the setting dissolved oxygen concentration and the setting atmosphere oxygen concentration is determined. A low oxygen gas whose oxygen concentration is equal or approached to the determined setting atmosphere oxygen concentration flows into a chamber that houses a substrate. Furthermore, an etching liquid whose dissolved oxygen is reduced such that its dissolved oxygen concentration is equal or approached to the determined setting dissolved oxygen concentration is supplied to the entire region of the upper surface of the substrate held horizontally.