Processing Liquid Supply and Recycling for Stable Etch Selectivity
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Solution Overview
Problem
Existing substrate treatment processes face challenges in maintaining the selectivity ratio and uniform properties due to temperature fluctuations and silica concentration imbalances in processing liquids, particularly in single-wafer type substrate processing apparatuses, leading to inefficiencies in etching processes.
Innovation Solution
A processing liquid supply device with separate units for supply and recycling, equipped with adjustment mechanisms to control silica concentration and temperature, allowing for spatially separated and efficient supply and recycling of processing liquids based on substrate conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the temperature of the processing liquid is adjusted to near the boiling point in a tank, then the selectivity ratio and etching rate are improved, but the temperature is lowered when supplied to the substrate for actual processing
Solution Approach 1:
The processing liquid supply system is divided into separate functional units: a heating unit that maintains the processing liquid at high temperature (near boiling point) to achieve optimal selectivity ratio and etching rate, and a separate supply unit that delivers the liquid to the substrate. This segmentation allows the heating and supply functions to be optimized independently, resolving the temperature maintenance issue during supply.
Solution Approach 2:
A temperature control mechanism acts as an intermediary between the heating tank and the supply system. This intermediary component (such as a heated supply line or temperature-controlled valve system) maintains the processing liquid at the required high temperature during transfer from the tank to the substrate, preventing temperature drop and ensuring consistent etching performance.
2Manufacturing precision
If the concentration of silica is increased in the processing liquid, then the etching selectivity ratio is improved, but selective etching cannot be performed properly or filters become clogged
Solution Approach 1:
The system dynamically adjusts the silica concentration parameter in the processing liquid based on real-time monitoring of etching performance and filter condition. By changing the silica concentration parameter within an optimal range (rather than using a fixed high concentration), the system achieves high etching selectivity ratio while preventing filter clogging and maintaining reliable operation.
Solution Approach 2:
A feedback control system monitors the condition of filters and the performance of etching processes, and automatically adjusts the silica concentration in the processing liquid supply. When filters show signs of clogging or etching selectivity deviates from targets, the feedback system modifies the silica concentration to restore optimal performance, preventing both over-concentration (clogging) and under-concentration (poor selectivity).
3Productivity
If a single-wafer type substrate processing apparatus is used, then processing efficiency is improved, but the temperature of processing liquid cannot be maintained near the boiling point during supply
Solution Approach 1:
The single-wafer processing apparatus incorporates a segmented liquid delivery system where the processing liquid path is divided into distinct zones: a heating zone that maintains near-boiling temperature, a transfer zone with thermal insulation or active heating, and a delivery zone to the substrate. This segmentation enables the apparatus to maintain high processing efficiency characteristic of single-wafer systems while preserving the critical temperature of the processing liquid throughout supply.
4Reliability
If the concentration of silica is decreased in the processing liquid, then filter clogging is reduced, but the etching speed of silicon oxide film increases and selectivity ratio is lowered
Solution Approach 1:
The system employs dynamic parameter adjustment of silica concentration, transitioning between different concentration levels based on process requirements. During normal operation, silica concentration is maintained at an optimal level for high selectivity. When filter clogging is detected or prevention is prioritized, the system adjusts the concentration parameter downward, accepting a trade-off in selectivity to ensure reliable filter operation and continuous processing.
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
The solution enhances the selectivity ratio and maintains uniform substrate treatment properties by stabilizing silica content and temperature, enabling continuous and efficient supply and recycling of processing liquids.
Implementation Method 1
a processing liquid such as a phosphoric acid solution is supplied as an etchant to a surface of a substrate on which a silicon nitride film and a silicon oxide film are formed, so that the silicon nitride film is selectively removed
Implementation Method 2
the temperature of the processing liquid such as phosphoric acid solution supplied on the substrate is near the boiling point
Data Source
AI summary
A method for supplying processing liquid is configured to adjust the supply amount of silica by a processing liquid supply unit in order to improve a selectivity ratio in a substrate treatment process through the processing liquid, to mix processing liquid substances, to adjust the concentration and temperature of the processing liquid on the basis of a substrate processing condition to supply the processing liquid to a substrate processing apparatus, to recover the processing liquid through a processing liquid recycling unit spatially separated from a processing liquid supply unit and to adjust the concentration of moisture and temperature of the processing liquid, and to supply the recycled processing liquid.