CVD Evaporation Source with Feedback Gas Concentration Control
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Solution Overview
Problem
Existing CVD reactor systems face challenges in precisely controlling the mass flow and maintaining constant pressure and concentration of process gases, particularly when using multiple sources with varying feedstock concentrations, which affects the deposition quality of semiconductor layers.
Innovation Solution
A gas supply arrangement with a pressure regulator and mass flow controllers that maintain constant total pressure and concentration by injecting compensating gases, combined with a measuring device to adjust the mass flow and partial pressure, allowing for precise control of process gases into multiple CVD reactors through multiple inlet points.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple gas sources with varying feedstock concentrations are used, then the versatility of the CVD system is improved, but the manufacturing precision of semiconductor layers deteriorates due to concentration fluctuations
Solution Approach 1:
A measuring device (such as an acoustic sensor) is integrated into the process gas supply line to continuously monitor the concentration or partial pressure of feedstock vapor. The measured value is fed back to a control device that adjusts the mass flow of carrier gas or compensating gas to maintain a predetermined concentration, thereby resolving the contradiction between using multiple gas sources and maintaining manufacturing precision
Solution Approach 2:
The system dynamically adjusts gas flow parameters (mass flow rates of carrier gas and compensating gas) based on measured concentration values. By changing these parameters in real-time, the system maintains constant feedstock concentration despite using multiple gas sources with varying concentrations, thus preserving manufacturing precision while maintaining versatility
2Productivity
If the mass flow of process gas is increased, then the productivity of the CVD reactor is improved, but the manufacturing precision deteriorates due to pressure fluctuations affecting deposition quality
Solution Approach 1:
A pressure sensor is placed in the process gas supply line to continuously monitor the total pressure. The measured pressure value is fed back to a control device that adjusts the mass flow of compensating gas to maintain a predetermined total pressure, allowing high mass flows (high productivity) while maintaining the pressure stability required for manufacturing precision
Solution Approach 2:
A compensating gas (such as nitrogen or hydrogen) is introduced as an intermediary substance to balance pressure fluctuations. This compensating gas acts as a mediator that absorbs pressure variations caused by high process gas flows, thereby maintaining stable deposition conditions even at high productivity levels
3Manufacturing precision
If a measuring device is added to monitor feedstock concentration, then the manufacturing precision is improved, but the device complexity increases
Solution Approach 1:
Traditional mechanical measurement methods are replaced with acoustic measurement technology. An acoustic sensor measures feedstock concentration by detecting sound propagation characteristics in the gas stream, providing precise concentration monitoring without complex mechanical moving parts, thus improving manufacturing precision while minimizing the increase in device complexity
4Manufacturing precision
If the total pressure in the process gas supply line is maintained constant using a pressure regulator, then the manufacturing precision is improved, but the device complexity increases due to additional control components
Solution Approach 1:
A pressure sensor continuously monitors the total pressure in the process gas supply line and feeds this information back to a control device. The control device adjusts the mass flow of compensating gas to maintain a predetermined total pressure, providing precise pressure control through feedback rather than complex mechanical pressure regulation systems
Solution Approach 2:
The system dynamically adjusts the mass flow parameter of compensating gas based on measured pressure values to maintain constant total pressure. This parameter adjustment approach provides precise pressure control while avoiding the need for complex mechanical pressure regulators with multiple moving parts
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
Ensures stable and precise delivery of process gases with consistent concentration and pressure, improving the deposition quality of semiconductor layers in CVD reactors by minimizing fluctuations.
Implementation Method 1
the total pressure in the process gas supply line is maintained or can be maintained at a predetermined value by feeding in a compensating gas flow of a carrier gas with a pressure regulator
Implementation Method 2
A gas supply arrangement with a pressure regulator and mass flow controllers that maintain constant total pressure and concentration by injecting compensating gases
Implementation Method 3
measuring devices are used in particular that generate a sound signal, especially an ultrasonic signal, and measure the sound transit time or speed of sound within the process gas
Implementation Method 4
a source can be used in which a solid or liquid feedstock is vaporized and the vapor is conveyed by a carrier gas to one or more CVD reactors
Implementation Method 5
A semiconductor layer of these elements is then deposited onto a substrate located in the process chamber and heated to a process temperature
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
The invention relates to an assembly for providing a process gas for use in a CVD reactor (1, 1', 1''), comprising an input mass-flow controller (10), (11) for providing a carrier gas flow which flows into an evaporation device (2, 2', 2''), the carrier gas flow conveying the vapor of a starting material (3), which starting material is stored in a container (4) of the evaporation device (2, 2', 2''), through a process gas feed line (9, 9', 9'') to the CVD reactor (1, 1', 1''), wherein the total pressure in the process gas feed line (9, 9', 9'') can be held at a predefined value by means of a pressure controller (8). In order to hold the mass flow of the starting material (3), which mass flow is to be fed into the CVD reactor, sufficiently constant over time, the gas stream flowing through the process gas feed lines (9, 9', 9'') is controlled by means of a mass-flow controller, and the concentration of the starting material in the process gas feed line (9, 9', 9'') at a predefined total pressure is measured.