Optical Sensor for Phase Determination in Supercritical Fluids
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Solution Overview
Problem
Accurately determining the phase state of substances, particularly supercritical fluids, in high-temperature and high-pressure environments is challenging due to limitations in existing measurement techniques, which can lead to incomplete cleaning and potential damage to wafer structures during semiconductor wafer cleaning processes.
Innovation Solution
A method and apparatus utilizing an optical sensor to measure the spatial and temporal distributions of the optical index of refraction, allowing for the determination of the phase state of substances by correlating the refractive index with temperature and pressure, using a shaped light beam and detecting the beam centroid position, enabling remote, real-time, and cost-effective measurements within high-temperature and high-pressure chambers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional measurement techniques are used to determine phase state, then device complexity is reduced, but measurement precision deteriorates
Solution Approach 1:
The patent replaces traditional mechanical or electrical measurement systems with an optical measurement system. A light source emits light through the substance in the chamber, and a detector measures the transmitted light intensity. The phase state is determined by analyzing the optical properties (absorption, scattering, refraction) of the substance, which differ characteristically between gas, liquid, and supercritical phases. This optical substitution enables precise phase detection without complex mechanical sensors.
Solution Approach 2:
The patent introduces an optical intermediary (light) as the mediator between the substance and the measurement system. Instead of directly measuring physical parameters like pressure or temperature, the system measures how the substance interacts with light. The light acts as an intermediary carrier that conveys information about the substance's phase state through its optical properties, simplifying the measurement approach while improving accuracy.
2Object-affected harmful factors
If remote measurement is implemented, then object-generated harmful factors are reduced, but measurement precision deteriorates
Solution Approach 1:
The optical measurement system serves multiple functions: it remotely determines phase state, monitors refractive index variations, and detects spatial distributions within the chamber. The same optical path and detector used for remote phase detection also provide precise refractive index measurements by analyzing light intensity variations. This multi-functionality achieves both remote operation (protecting wafer structures) and measurement precision.
Solution Approach 2:
The system creates an optical copy or representation of the substance's properties through light transmission characteristics. Instead of physically interacting with the substance, the light carries information about the substance's phase and refractive index. This optical copying enables remote measurement while preserving measurement accuracy, as the light field replicates the substance's optical properties without physical contact.
3Measurement precision
If spatial distribution measurement is performed, then measurement precision is improved, but use of energy increases
Solution Approach 1:
The measurement chamber is conceptually divided into multiple spatial zones along the optical path. By measuring light intensity at different positions or using multiple detectors arranged spatially, the system reconstructs the refractive index distribution across the chamber. This segmentation approach enables precise spatial mapping of phase states and refractive index variations without requiring excessive energy input.
Solution Approach 2:
The system uses a moderate light intensity that is sufficient for detection but not excessive. The optical detector is designed to sensitively detect small variations in light transmission, allowing accurate spatial distribution measurements with minimal energy input. This partial action principle avoids over-engineering the light source power while achieving the required measurement precision.
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 accurate determination of the phase state of substances, ensuring effective cleaning without residue or damage by providing precise measurements of refractive index variations, ensuring the cleaning process occurs without surface tension forces and capillary effects.
Implementation Method 1
The method is based on the Snell's law: the product of index of refraction n and of sine of the angle of incidence θ remains constant as the beam of light passes from one media/substance to another
Implementation Method 2
n1 sin(θ1)=n2 sin(θ2)
Implementation Method 3
A light source is configured to generate an incident light beam. The incident light beam is directed to the entrance window at a non-zero angle of incidence with respect to a normal of the entrance window. The incident light beam passes through the entrance window, the measurement chamber and the exit window to form an output light beam.
Data Source
AI summary
An apparatus and a method for in-situ phase determination are provided. The apparatus includes a measurement chamber configured to retain a substance, and an entrance window mounted on a side of the measurement chamber. An exit window is mounted on an opposite side of the measurement chamber, and the exit window is parallel with the entrance window. The apparatus further includes a light source configured to generate an incident light beam. The incident light beam is directed to the entrance window at a non-zero angle of incidence with respect to a normal of the entrance window. The incident light beam passes through the entrance window, the measurement chamber and the exit window to form an output light beam. A detector is positioned under the exit window and configured to collect the output light beam passing through the exit window and generate measurement data.