Vapor Delivery System for Real-Time Precursor Volume Monitoring
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Solution Overview
Problem
Existing methods for determining the amount of precursor chemicals remaining in metal organic chemical vapor deposition (MOCVD) bubblers are inefficient, especially for solid precursors, as they require breaking seals, are expensive, or cannot accurately measure fill levels.
Innovation Solution
An integrated vapor delivery system that uses a flow controller and pressure controller to measure gas flow and pressure changes over time, calculating the volume of precursor consumed based on pressurization rate curves, allowing for continuous and real-time monitoring of material consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional weighing methods are used to determine precursor remaining in bubbler, then measurement accuracy is improved, but system reliability deteriorates due to seal breaking and air contamination
Solution Approach 1:
The patent replaces the mechanical weighing system (which requires removing and opening the bubbler) with a pressure-based sensing system that measures precursor levels through sealed walls using capacitance or ultrasonic methods, eliminating the need to break seals and maintain gas line integrity
Solution Approach 2:
The patent introduces an intermediary sensing mechanism (capacitance probe or ultrasonic transducer) that can measure precursor levels through the bubbler wall without direct contact with the precursor or gas lines, thus maintaining system sealing while achieving accurate measurement
2Measurement precision
If fiber optic or capacitance probing techniques are used, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent employs relatively simple and inexpensive sensors (capacitance probes or ultrasonic transducers) that can be easily integrated into the bubbler design, avoiding the need for complex fiber optic systems while achieving reliable measurement functionality
Solution Approach 2:
The patent designs a multi-functional bubbler system where the same structure serves both as a containment vessel and as an integrated sensing platform, with the sensor serving multiple measurement purposes (level detection, consumption tracking) without requiring separate complex systems
3Measurement precision
If ultrasonic or capacitance methods are applied, then measurement accuracy is improved, but adaptability deteriorates as these methods are not easily applied to solid precursors
Solution Approach 1:
The patent employs a universal sensing approach using capacitance or ultrasonic methods that can detect changes in the bubbler environment regardless of whether the precursor is liquid or solid, enabling the same system to handle different precursor types without modification
Solution Approach 2:
The patent utilizes changes in physical parameters (capacitance values or ultrasonic wave properties) that occur when precursors are consumed, which are independent of the precursor's physical state (liquid or solid), allowing consistent measurement across different precursor types
4Manufacturing precision
If instrument-based vapor concentration measurement is used, then gas mixture control is improved, but the ability to determine bubbler fill level deteriorates
Solution Approach 1:
The patent separates the measurement functions into distinct components: one system (instrument) measures vapor concentration in the gas stream for process control, while another system (capacitance or ultrasonic sensor) measures the physical fill level in the bubbler, allowing both measurements to coexist without interference
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 method provides efficient and accurate determination of precursor chemical volume in bubblers, reducing the need for seal-breaking and costly equipment, and effectively measures fill levels for both liquid and solid precursors.
Implementation Method 1
A pressure controller measures pressure in the bubbler
Implementation Method 2
A flow controller controls gas flow through a bubbler
Implementation Method 3
A pressurization rate processor calculates first and second pressurization rate curves at first and second time instants
Data Source
AI summary
One disclosed feature of the embodiments is a control processor in a vapor delivery system for chemical vapor deposition precursors. A pressurization rate processor calculates first and second pressurization rate curves at first and second time instants. A volume calculator computes consumed volume based on first and second volumes at the respective first and second time instants. The first and second volumes are computed using slopes of lines fitting the first and second pressurization rate curves.