T-Shaped Gas Flow Cell for Mirror Particle Deposition
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Solution Overview
Problem
In optical gas-analysis systems, particulate matter deposition on mirrors and optical windows reduces the effective reflection capability, leading to decreased sensitivity and inaccurate gas analysis, particularly in semiconductor manufacturing processes where particles are easily generated and deposited during sample gas introduction and exhaust.
Innovation Solution
The design of a gas flow cell with a T-shaped or cross-shaped configuration for the sample-gas introduction and exhaust ports, positioned at the center of the cell body orthogonal to the long axis, minimizes particle deposition on mirrors by reducing the likelihood of particles reaching the reflection surfaces, maintaining high sensitivity and accuracy in gas analysis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If sample-gas introduction port and exhaust port are arranged in diagonal direction or at both ends of cell body, then gas exchange efficiency is improved, but particle deposition on mirrors increases
Solution Approach 1:
The patent positions the sample-gas introduction port and exhaust port at asymmetric locations relative to the mirror surfaces. Specifically, the ports are arranged such that their connecting line does not pass through the mirror surfaces, creating an asymmetric flow path that directs gas flow away from the mirrors. This asymmetric configuration maintains efficient gas exchange while preventing particle-laden flow from directly contacting the mirror surfaces.
Solution Approach 2:
The patent solves the contradiction by transitioning from a two-dimensional arrangement (ports at ends or diagonals of a plane) to a three-dimensional spatial configuration. The ports are positioned at specific heights and lateral positions creating a three-dimensional flow path that bypasses the mirror surfaces. This dimensional change allows the gas flow to exchange efficiently at the ports while the particles are directed along a path that does not intersect with the mirror surfaces.
2Measurement precision
If multiple-reflection configuration is used, then sensitivity of gas analysis is improved, but particle deposition on mirrors causes greater drop in sensitivity
Solution Approach 1:
The patent extracts the harmful effect of particle deposition from the system by designing the port configuration to exclude particles from reaching the mirror surfaces. The introduction port and exhaust port are positioned and oriented such that the gas flow path is separated from the mirror surfaces, effectively removing the contamination pathway while preserving the multiple-reflection configuration for high sensitivity.
Solution Approach 2:
The patent applies preliminary anti-action by pre-configuring the port positions and orientations to prevent particle deposition before it can occur. The asymmetric arrangement of ports creates a flow pattern that inherently directs particles away from the mirrors, establishing a protective configuration in advance that maintains reflection capability and sensitivity stability over time.
3Device complexity
If branched tube for port is closely located to mirrors, then compact design is achieved, but particle deposition on mirrors is facilitated
Solution Approach 1:
The patent applies local quality by creating different spatial zones within the cell body. The region near the ports has a different flow characteristic and particle concentration compared to the region near the mirrors. By positioning ports asymmetrically, the patent creates a localized flow path that keeps high particle concentration zones away from the mirror surfaces, allowing compact design while protecting mirrors through localized flow management.
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 configuration effectively prevents particle contamination on the mirrors and optical windows, ensuring continuous high-sensitivity gas analysis by maintaining the effective reflection capability and accurate monitoring of sample gases within the process chamber.
Implementation Method 1
particles are easily deposited on surfaces of the first cell mirror 41 and the second cell mirror 42
Implementation Method 2
the light is multiple-reflected between two of the first cell mirror 41 and second cell mirror 42
Implementation Method 3
another gas-analysis system of absorption-spectrophotometry, such as a gas-analysis system of White multiple-reflection absorption-spectrophotometry
Data Source
AI summary
A gas flow cell for an optical gas-analysis system, including a cylindrical cell body; and a single sample-gas introduction port configured to introduce sample-gas. The single sample-gas introduction port is provided at a location at a substantial center of the cell body with respect to a long axis direction of the cell body, and the single sample-gas introduction port is aligned along a direction orthogonal to the long axis direction so that the cylindrical cell body and the single sample-gas introduction port together form a shape of a character T.