CVD Showerhead Segmented Gas Modules for Velocity Control
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Solution Overview
Problem
In chemical vapor deposition (CVD) processes, reactive gases with low decomposition temperatures or moisture sensitivity can cause unwanted deposits on the showerhead, leading to contamination and reduced film quality, especially when mixed with other reactive gases, and existing systems struggle to control the injection velocities of purge and reactive gases effectively.
Innovation Solution
The apparatus and method involve a showerhead design where each reactive gas is supplied independently through separate modules, with a purge gas injected from the bottom to form a protective curtain, and the injection velocities are regulated by mixing with an inert injection support gas, preventing backward diffusion and ensuring uniform mixing over the substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If reactive gases are mixed in the reaction chamber, then film formation can proceed, but homogeneous reactions in the gas phase occur leading to contaminant particle generation
Solution Approach 1:
The showerhead is divided into multiple independent gas supply channels, each delivering a different reactive gas. This segmentation prevents premature mixing of reactive gases in the showerhead, allowing them to reach the substrate separately and react only on the substrate surface rather than in the gas phase, thereby eliminating contaminant particle generation while maintaining film formation efficiency
Solution Approach 2:
An inert gas is introduced as an intermediary carrier gas that transports the reactive gases through the showerhead without causing unwanted reactions. The inert gas creates a protective atmosphere that prevents homogeneous reactions between reactive gases while still allowing them to reach and react on the substrate surface
2Productivity
If reactive gases with low decomposition temperatures are used, then film growth can occur, but unwanted deposits form on the showerhead and reaction chamber walls
Solution Approach 1:
Each reactive gas is supplied through separate independent channels in the showerhead, preventing concentration buildup and unwanted side reactions that would form deposits. The segmented delivery system ensures that reactive gases only concentrate and react on the substrate surface where they are needed, not on the showerhead surfaces
Solution Approach 2:
An inert gas atmosphere is maintained in the showerhead to prevent unwanted chemical reactions between reactive gases and with the showerhead material. This inert environment allows reactive gases to pass through without decomposing or reacting prematurely, enabling film growth while preventing deposit formation on the showerhead
3Object-generated harmful factors
If purge gas flow rate is increased to prevent deposits, then showerhead contamination is reduced, but injection velocity control of reactive gases becomes difficult
Solution Approach 1:
The gas supply system is segmented into independent channels for each reactive gas and separate purge gas channels. This segmentation allows independent control of each gas flow, enabling precise regulation of reactive gas injection velocities while maintaining effective purge flow rates to prevent deposits without interfering with each other
Solution Approach 2:
The system incorporates dynamic flow control mechanisms that allow real-time adjustment of gas flow rates and injection velocities. This dynamic control enables optimization of both purge gas flow (to prevent deposits) and reactive gas injection velocities (for precise film formation), with each parameter independently可调
4Adaptability or versatility
If multiple reactive gases are supplied through a single showerhead, then film composition can be controlled, but backward diffusion of gases occurs causing contamination
Solution Approach 1:
Multiple reactive gases are supplied through separate independent channels that extend to different locations or have different flow characteristics. This segmentation creates distinct gas delivery paths that prevent backward diffusion and cross-contamination between different reactive gas streams, while still allowing controlled mixing and reaction on the substrate surface to achieve desired film compositions
Solution Approach 2:
The gas delivery system utilizes spatial differentiation in the vertical dimension, with each reactive gas channel positioned at different heights or angles. This dimensional separation prevents backward diffusion by creating staggered delivery zones, while still enabling comprehensive coverage and composition control on the substrate surface through coordinated multi-dimensional gas distribution
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 approach prevents contamination within the reaction chamber, enhances film growth rate, and ensures uniform film composition and thickness by controlling the injection velocities of reactive gases, thereby improving the quality and productivity of the CVD process.
Implementation Method 1
the injection velocities are regulated by mixing with an inert injection support gas, preventing backward diffusion and ensuring uniform mixing over the substrate
Implementation Method 2
a purge gas injected from the bottom to form a protective curtain, preventing backward diffusion
Implementation Method 3
In an apparatus for chemical vapor deposition (CVD), a reactive gas is introduced into a vacuum reaction chamber, flows through a showerhead, and reaches a susceptor or a substrate holder on which a substrate is located. The reactive gas causes chemical reaction on the substrate to form a desired film.
Data Source
AI summary
A showerhead for chemical vapor deposition includes: a plurality of reactive gas showerhead modules separated each other and having the same number as the number of kinds of reactive gases injected from the showerhead, each having a mixing zone in the reactive gas showerhead module to induce a mixing of a reactive gas and an injection support gas used to regulate the injection velocity of the reactive gas and a plurality of reactive gas injection tubes connected to the bottom surface of the reactive gas showerhead module for injecting the reactive gas mixed with the injection support gas over the substrate; and a purge gas showerhead module mounted under the reactive gas showerhead modules, with a purge gas supply port for supplying a purge gas to the purge gas showerhead module.