CVD Showerhead Segmentation and Purge Gas Flow
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Solution Overview
Problem
Conventional chemical vapor deposition (CVD) systems face issues with unwanted particle deposition on showerheads due to reactive gas reactions, especially with metal-organic compounds having low decomposition temperatures, leading to contamination and reduced film growth rates, particularly in high-integration semiconductor manufacturing.
Innovation Solution
The system employs a showerhead design where each reactive gas is supplied through separate compartments and a purge gas is injected from the bottom to form a concentric flow, preventing backward diffusion and unwanted particle deposition on the showerhead and inner chamber walls, while a reactive gas confining means ensures the gas remains near the substrate, enhancing film growth rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If reactive gases are mixed in the reaction chamber to deposit film on substrate, then film formation is achieved, but homogeneous reactions in gas phase generate contaminant particles
Solution Approach 1:
The showerhead is divided into multiple independent compartments, each supplying a different reactive gas. This segmentation prevents gases from mixing in the showerhead, eliminating homogeneous reactions that generate contaminant particles while still allowing film deposition on the substrate.
Solution Approach 2:
A purge gas is introduced as an intermediary substance between the reactive gases. The purge gas flows in the opposite direction to prevent backward diffusion of reactive gases into each other's compartments, acting as a barrier that maintains gas separation and prevents contaminant formation.
2Device complexity
If reactive gases are supplied through a simple showerhead, then device complexity is reduced, but unwanted particle deposition occurs on showerhead and chamber walls
Solution Approach 1:
The showerhead is segmented into multiple independent compartments, each dedicated to supplying a specific reactive gas. This prevents unwanted particle deposition on the showerhead by eliminating heterogeneous reactions on the showerhead surface that occur when multiple gases mix in a simple showerhead design.
Solution Approach 2:
The invention introduces a third dimension of gas flow by adding purge gas flow in the opposite direction to the reactive gas flow. This bidirectional flow arrangement prevents backward diffusion and particle deposition on the showerhead while maintaining a relatively simple overall structure.
3Device complexity
If reactive gases flow freely in the reaction chamber, then gas distribution is simple, but film growth rate decreases due to gas diffusion away from substrate
Solution Approach 1:
The showerhead compartments are positioned and oriented to deliver reactive gases directly to the substrate surface. This segmented delivery system confines the reactive gases near the substrate, enhancing film growth rates while maintaining a relatively simple structure without requiring complex confinement mechanisms.
4Adaptability or versatility
If metal-organic compounds with low decomposition temperature are used, then diverse film materials can be deposited, but homogeneous reactions generate contaminant particles
Solution Approach 1:
Each metal-organic compound is supplied through a separate compartment in the showerhead, preventing their mixing before reaching the substrate. This segmentation allows the use of diverse metal-organic compounds with low decomposition temperatures to deposit various film materials while preventing homogeneous reactions that would generate contaminant particles.
Solution Approach 2:
Each compartment is dedicated to a specific reactive gas or metal-organic compound, creating localized zones with distinct chemical properties. This local quality control ensures that each substance reaches the substrate without interacting with others in the gas phase, enabling diverse film deposition without contaminant formation.
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 effectively prevents particle deposition and contamination, allowing for uniform film growth and increased productivity by maintaining reactive gases near the substrate, thus addressing the limitations of conventional CVD systems.
Implementation Method 1
each reactive gas is delivered independently through separate compartments
Implementation Method 2
a purge gas injected from the bottom to form a concentric flow, preventing backward diffusion
Implementation Method 3
preventing backward diffusion
Implementation Method 4
chemical vapor deposition (CVD) that can prevent a undesired particle deposition on the showerhead which supplies reactive gases uniformly over a substrate to grow a uniform film on the substrate
Implementation Method 5
a method of simply heating the substrate or atomically exciting the reactive gas, such as making plasma
Implementation Method 6
keeps temperature of the substrate higher than that of surroundings using a substrate heater
Data Source
AI summary
Disclosed is an apparatus for chemical vapor deposition (CVD) with a showerhead through which a source material gas is injected over a substrate to deposit a film on the substrate. The showerhead includes: a plurality of reactive gas showerhead modules having the same number as the kind of reactive gases of the source material gas, each reactive gas showerhead module having inner spaces separated from each other and a plurality of reactive gas flow channels formed on the bottom surface thereof for supplying the reactive gas over the substrate; and a purge gas showerhead module mounted under the reactive gas showerhead modules, having a purge gas supply port for introducing a purge gas of the source material gas thereto, an inner space separated from inner spaces of the reactive gas showerhead modules for being filled with the purge gas only, a plurality of inlets formed on the upper surface thereof for allowing a penetration of the said reactive gas flow channels through the inner space thereof with hermetic sealing at the joints of the said inlets, a plurality of exits for said reactive gas flow channels and a plurality of exits for said purge gas formed on the bottom surface thereof, and said exit for purging gas having a diameter smaller than that of said exit for the reactive gas flow channel, and wherein each reactive gas flow channel of each reactive gas showerhead module placed at upper positions passes through the inside of the other reactive gas showerhead modules placed at lower positions and through the inside of the purge gas showerhead module.