Substrate Liquid Film Imaging for Precise Flow Rate Estimation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional methods for measuring the flow rate of processing liquid supplied to substrates, such as semiconductor wafers, are operator-dependent and prone to deviations, lacking a reliable and skill-independent measurement technique.
Innovation Solution
A method that involves supplying processing liquid to a position off-center of the substrate while rotating it, imaging the liquid film formed by diffusion using an imaging unit, calculating characteristic amounts from the imaging results, and applying these to a correlation function to estimate the flow rate accurately.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional operator-dependent methods are used to measure flow rate, then measurement can be performed with simple equipment, but measurement precision and reliability deteriorate due to operator skill variations
Solution Approach 1:
The patent replaces manual operator-based measurement methods with an automated imaging and calculation system. The imaging unit captures images of the liquid film, and a control unit automatically calculates flow rate based on image analysis, eliminating operator skill variations and improving measurement precision while maintaining manageable system complexity through automation
Solution Approach 2:
The patent uses optical imaging to create a visual copy of the liquid film state on the substrate. By capturing images of the liquid film distribution and using image analysis to derive flow rate characteristics, the system transforms physical liquid flow into measurable visual data, enabling precise and objective measurement without direct operator intervention
2Measurement precision
If processing liquid is supplied to the center of the substrate, then liquid distribution is symmetric and simple to control, but diffusion state cannot be properly observed for flow rate estimation
Solution Approach 1:
The patent deliberately supplies processing liquid to a position apart from the center of the substrate, creating an asymmetric liquid distribution pattern. This asymmetric supply enables the liquid film to diffuse in a observable manner across the substrate surface, allowing the imaging unit to capture meaningful diffusion states that correlate with flow rate, thereby improving measurement precision
Solution Approach 2:
The patent transitions from considering only the supply position to analyzing the two-dimensional diffusion pattern of the liquid film across the substrate surface. By imaging the spatial distribution and diffusion extent of the liquid film, the system extracts flow rate information from the diffusion state, adding a dimensional aspect to flow rate measurement
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
Enables precise and operator-independent estimation of the flow rate, reducing measurement deviations and improving the reliability of flow rate measurements in substrate processing systems.
Implementation Method 1
a liquid film formed by diffusion of the processing liquid on the surface of the substrate
Implementation Method 2
imaging a liquid film formed by diffusion of the processing liquid on the surface of the substrate utilizing an imaging unit
Data Source
AI summary
A flow rate estimating method includes a supply process, an image process, and an estimate process. The supply process supplies processing liquid from a processing-liquid supplying unit to a position that is apart from the center of the substrate while rotating the substrate utilizing a substrate holding unit that rotatably holds the substrate. The image process images a liquid film formed by diffusion of the processing liquid on the surface of the substrate utilizing an imaging unit. The estimate process calculates a characteristic amount that indicates a state of the diffusion of the processing liquid from an imaging result of the imaging unit, and estimates the flow rate by applying the calculated characteristic amount to a correlation function that indicates the correlation between the characteristic amount and the flow rate of the processing liquid supplied to the substrate from the processing-liquid supplying unit.