CVD Reactor Gas Inlet Thermal Decoupling
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Solution Overview
Problem
In CVD reactors, parasitic growth on cooled gas inlet housing walls leads to undesirable particle formation and clogging, requiring frequent mechanical cleaning, and the decomposition of process gases at the gas outlet plate can cause parasitic reactions, reducing energy efficiency and affecting layer growth due to moisture residues.
Innovation Solution
The gas outlet plate is thermally decoupled from the gas inlet housing wall, with gas lines extending into the outlet plate to maintain 'cold' mouths below decomposition temperature, and a second process gas enters through hotter openings, reducing parasitic reactions and improving energy efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the gas inlet housing wall is cooled to prevent parasitic growth, then particle formation and clogging are reduced, but the gas outlet plate temperature becomes insufficient for effective cleaning
Solution Approach 1:
The gas inlet element is segmented into a cooled gas inlet housing wall and a thermally decoupled gas outlet plate. The gas outlet plate is separated by a clearance space and held only at its outer edge, allowing it to be heated independently by radiation from the susceptor while the gas inlet housing wall remains cooled for parasitic growth prevention.
Solution Approach 2:
The clearance space acts as a thermal intermediary between the cooled gas inlet housing wall and the gas outlet plate. This gap prevents direct thermal conduction, allowing the gas outlet plate to be heated by radiation from the susceptor without being cooled by the cooled gas inlet housing wall.
2Ease of manufacture
If the gas outlet plate is heated to clean parasitic deposits, then cleaning effectiveness is improved, but parasitic reactions occur due to process gas decomposition
Solution Approach 1:
Different regions of the gas inlet element have different thermal properties: the gas inlet housing wall is cooled to prevent parasitic growth, while the gas outlet plate is thermally decoupled and heated by radiation to enable effective cleaning. The gas lines extending into the gas outlet plate maintain lower temperatures at their mouths to prevent process gas decomposition.
Solution Approach 2:
The system dynamically manages temperature distribution through thermal decoupling. The gas outlet plate temperature is controlled by balancing radiative heating from the susceptor with the cooling effect of the clearance space, allowing it to reach cleaning temperatures without causing widespread parasitic reactions.
3Reliability
If mechanical cleaning is performed frequently to remove parasitic growth, then cleaning effectiveness is maintained, but productivity is reduced due to frequent interruptions
Solution Approach 1:
The gas outlet plate is pre-heated by radiation from the susceptor during the deposition process itself, reaching temperatures sufficient for cleaning without requiring separate heating steps. This preliminary heating action during deposition reduces the need for frequent mechanical cleaning interruptions.
Solution Approach 2:
The gas outlet plate performs self-cleaning through thermal decoupling and radiative heating. The clearance space and edge mounting allow the plate to be heated independently to temperatures that prevent or remove parasitic deposits without requiring external mechanical cleaning interventions.
4Ease of manufacture
If the entire reactor housing is opened to clean the gas outlet side, then complete cleaning is achieved, but loss of time and productivity increase
Solution Approach 1:
The gas outlet plate is extracted from the cooled gas inlet housing wall structure through thermal decoupling and clearance space separation. This allows the gas outlet plate to be independently heated and cleaned without opening the entire reactor housing, as the cleaning function is localized to the gas outlet plate itself.
Solution Approach 2:
The gas outlet plate is designed to be self-cleaning through independent thermal control. The clearance space and edge mounting enable the plate to reach cleaning temperatures autonomously during operation, eliminating the need for reactor shutdown and complete housing opening for cleaning.
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 extends cleaning cycles, reduces parasitic reactions, and enhances energy efficiency by maintaining gas lines at lower temperatures and allowing for effective heating of the gas outlet plate for cleaning, while minimizing moisture effects on layer growth.
Implementation Method 1
The gas inlet housing wall is cooled
Implementation Method 2
heated by heat radiation from the susceptor
Implementation Method 3
The gas lines, through which a first process gas is introduced into the process chamber, continue over the gas inlet housing wall
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
The invention relates to a gas inlet member (2) of a CVD reactor, comprising a gas inlet housing which has at least one first gas distribution volume (5) that can be supplied with a first process gas by a first feed line (21) and that has a plurality of gas lines (8), each designed as a tube. Through said gas lines (8), which extend into first openings (16) in a gas outlet plate (14) arranged in front of an inlet housing wall (10), the first process gas enters a process chamber beneath the gas outlet plate (14), a gap (20) being provided between the gas inlet housing wall (10) and the gas outlet plate (14). Adjoining the gas inlet housing wall (10) is a coolant chamber (7), into which a coolant can be fed to cool the gas inlet housing wall (10) and the orifices (8') of the gas lines (8), which are in thermally conductive contact with the cooled gas inlet housing wall (10). The gas outlet plate (14) is thermally decoupled from the gas inlet housing wall (10) such that the gas outlet plate (14), which is impacted by radiant heat from the process chamber (22), is heated up more than the orifices (8') protruding into the openings (16) in the gas outlet plate (14).