Substrate Processing Liquid Mixing for Precise Dissolved Oxygen Control
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Solution Overview
Problem
Existing substrate processing technologies face challenges in accurately adjusting the dissolved oxygen concentration in processing liquids and preventing contamination from particles or metal ions introduced by concentration measurement parts during the processing of semiconductor substrates.
Innovation Solution
A substrate processing apparatus with dual supply liquid lines, each with its own concentration measurement and filtration system, allows for precise control of dissolved gas concentrations by mixing liquids with different oxygen levels, and includes a control system to adjust flow rates based on measured values, ensuring accurate gas concentration and preventing contamination from measurement-related impurities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a concentration measurement part is provided in the processing liquid circulation path to adjust nitrogen gas concentration, then the nitrogen gas concentration can be controlled, but particles or metal ions from the measurement part contaminate the processing liquid
Solution Approach 1:
The circulation path is divided into two separate loops: a first circulation path that includes the concentration measurement part and a dissolution part for nitrogen gas saturation, and a second circulation path that includes a degassing part and connects back to the processing bath. This segmentation prevents the measurement part from contaminating the main processing liquid while still enabling accurate concentration control.
Solution Approach 2:
The concentration measurement function is extracted from the main processing liquid circulation path and placed in a separate first circulation path. This allows the measurement part to operate independently without introducing contaminants to the processing liquid that contacts the substrate.
2Quantity of substance
If dissolved oxygen concentration is reduced by bubbling nitrogen gas or decompressing, then the etching rate can be controlled, but it is difficult to adjust to an arbitrary set value with high accuracy
Solution Approach 1:
A dissolved oxygen concentration meter provides real-time feedback on the oxygen concentration in the processing liquid. The control unit adjusts the nitrogen gas flow rate or degassing operation based on this feedback to maintain the desired set value, enabling precise control of dissolved oxygen concentration for consistent etching rates.
Solution Approach 2:
The system changes the physical parameters of the processing liquid by controlling nitrogen gas bubbling intensity, degassing pressure, or circulation flow rate to adjust the dissolved oxygen concentration to a specific set value, enabling precise control of etching processes.
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 high-accuracy adjustment of dissolved oxygen concentrations in processing liquids, preventing contamination and ensuring consistent substrate processing quality by isolating and filtering out impurities from the measurement parts, thus enhancing the reliability and efficiency of substrate processing.
Implementation Method 1
a first concentration measurement part provided in the first supply liquid line, for measuring a dissolved concentration of predetermined gas in the first supply liquid
Implementation Method 2
a second concentration measurement part provided in the second supply liquid line, for measuring a dissolved concentration of the gas in the second supply liquid
Implementation Method 3
a mixing part to which the other end of the first branch line and the other end of the second branch line are connected, for mixing the first supply liquid and the second supply liquid
Data Source
AI summary
First and second concentration measurements are provided in lines for first and second supply liquid lines. A dissolved concentration of gas in the second supply liquid is lower than that in the first supply liquid. In the first and second lines, first ends of branch lines are connected upstream of the concentration measurements. The second ends of the branch lines are connected to a mixing part. By mixing the first and second supply liquids, a processing liquid is generated. Respective flow rates in the branch lines are based on the first and second concentration measurements to set the dissolved concentration of the gas in the processing liquid. Thus, particles or the like can be removed from the processing liquid to be supplied to a substrate, and the dissolved concentration of the gas in the processing liquid can be set with high accuracy.