Mixing Chamber for CVD Liquid Injection
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Solution Overview
Problem
Existing devices for introducing liquid compounds into evaporation chambers in chemical vapor deposition (CVD) face challenges such as insufficient low flow rates, premature evaporation of liquids, injector obstruction, and difficulty in spraying viscous liquids without contact with heated walls, leading to instability and reduced efficiency.
Innovation Solution
A device with a mixing chamber that combines carrier gas and liquid compounds, allowing for controlled injection of a mixture through a single outlet, using proportional valves and flow meters to regulate flow rates and pressures, ensuring efficient atomization and evaporation without wall contact.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the injector flow rate is reduced to achieve lower liquid flow rates, then the liquid flow rate decreases, but the control frequency must be significantly reduced leading to substantial fluctuations in partial pressure
Solution Approach 1:
A mixing chamber is introduced as an intermediary component between the injector and the evaporation chamber. The injector injects liquid into the mixing chamber where it mixes with carrier gas, and this mixture is then introduced into the evaporation chamber. This intermediary mixing chamber allows for better control of liquid flow rates while maintaining stable partial pressures through continuous mixing with the carrier gas.
2Quantity of substance
If the injector is opened frequently to maintain low flow rates, then the liquid flow rate control improves, but premature evaporation of liquid in the supply line occurs
Solution Approach 1:
The mixing chamber serves as an intermediary that receives liquid from the injector and mixes it with carrier gas before introducing it to the evaporation chamber. This allows the liquid to be transported without direct exposure to the heated evaporation chamber walls, preventing premature evaporation while maintaining precise flow rate control.
Solution Approach 2:
Carrier gas is used to transport the liquid from the injector through the mixing chamber to the evaporation chamber. The pneumatic flow of carrier gas carries the liquid droplets or vapor, preventing direct contact with heated surfaces and eliminating premature evaporation issues.
3Quantity of substance
If the liquid injector is used to achieve low flow rates, then the flow rate decreases, but injector obstruction occurs reducing flow over time
Solution Approach 1:
The mixing chamber acts as an intermediary that receives liquid from the injector and immediately mixes it with carrier gas. This prevents liquid from stagnating in the injector, reducing the risk of obstruction. The continuous flow of carrier gas through the mixing chamber helps maintain stable flow conditions and prevents buildup that could lead to injector clogging.
4Temperature
If viscous liquids are sprayed directly into the evaporation chamber, then the evaporation process starts, but contact with heated walls occurs causing instability
Solution Approach 1:
The mixing chamber serves as an intermediary zone where viscous liquids are mixed with carrier gas before entering the evaporation chamber. This mixing process helps atomize the liquid and distribute it uniformly in the gas phase, preventing direct contact with heated chamber walls and ensuring stable evaporation without thermal instability.
Solution Approach 2:
Carrier gas is used to transport and distribute the liquid through the mixing chamber into the evaporation chamber. The pneumatic flow ensures that the liquid is carried as fine droplets or vapor rather than bulk liquid, preventing wall contact and maintaining process stability during evaporation of viscous materials.
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
The solution enables precise control of flow rates and pressures, improving atomization and evaporation kinetics, reducing the risk of wall contact and maintaining stable partial pressures, thus enhancing the efficiency and reliability of the CVD process.
Implementation Method 1
A device with a mixing chamber that combines carrier gas and liquid compounds
Implementation Method 2
A spray, consisting of fine liquid droplets, is then formed by atomisation of the injected liquid
Implementation Method 3
The liquid droplets are then evaporated in the enclosure, which either directly forms the deposition chamber
Data Source
AI summary
The invention relates to a device for introducing a carrier gas and liquid compounds or a liquid solution into an evaporation chamber, comprising a mixing chamber, including at least:—a first inlet for the admission of said compounds or said solution,—a second inlet for the admission of the carrier gas,—and an outlet connected to an inlet of an injector, so that a mixture of carrier gas and droplets of said compounds or of said solution is periodically injected, through a single injector outlet, into the evaporation chamber.