Shower Plate Gas Distribution for MOCVD Film Uniformity
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Solution Overview
Problem
Existing vapor phase growth apparatuses face challenges in achieving uniform film thickness and quality, particularly in the vicinity of the rotation center of the substrate, due to non-uniform gas composition and flow distribution during epitaxial growth processes like MOCVD for GaN-based semiconductor films.
Innovation Solution
The apparatus features a shower plate with multiple lateral and longitudinal gas passages and ejection holes, including a center passage above the rotation center, allowing independent control of gas flow and composition, which increases the arrangement density of gas ejection holes and equalizes flow amount distribution, thereby enhancing film uniformity and quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a conventional shower plate with uniform gas passages is used, then the gas flow distribution is simple and easy to manufacture, but the film thickness and quality uniformity near the rotation center is poor
Solution Approach 1:
The shower plate is segmented into multiple independent gas passage systems: first lateral gas passages, second lateral gas passages, center lateral gas passage, first longitudinal gas passages, second longitudinal gas passages, and center longitudinal gas passages. Each system can be independently controlled through separate gas supply lines and flow amount adjustment units, allowing precise control of gas distribution to different regions of the substrate to achieve uniform film formation.
Solution Approach 2:
Different regions of the shower plate are provided with different gas passage configurations tailored to local requirements. The center lateral gas passage and center longitudinal gas passages are specifically positioned above the rotation center to address the unique gas distribution needs of the central region, while lateral and longitudinal passages serve peripheral areas, ensuring optimal gas flow and film uniformity across the entire substrate surface.
2Manufacturing precision
If multiple independent gas supply lines and flow adjustment units are added, then the gas composition and flow can be independently controlled, but the device complexity increases
Solution Approach 1:
The gas supply control system is segmented into multiple independent control units: first gas supply line with first flow amount adjustment unit, second gas supply line with second flow amount adjustment unit, and center gas supply line with center flow amount adjustment unit. Each unit independently controls the gas flow to its corresponding passage system, enabling precise adjustment of gas composition and flow distribution to achieve uniform film quality across the substrate.
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 enables the growth of films with excellent uniformity in film thickness and quality by stabilizing the flow of process gases and independently controlling the gas composition near the rotation center, improving the overall film formation process.
Implementation Method 1
a plurality of first lateral gas passages disposed within a first horizontal plane, the first lateral gas passages extending in parallel to each other, a plurality of first longitudinal gas passages connected to the first lateral gas passages, the first longitudinal gas passages extending in a longitudinal direction
Implementation Method 2
a process gas such as a source gas as a raw material for a film formation process is supplied from, for example, a shower plate of an upper portion of the reaction chamber to the surface of the wafer while heating the wafer. Thus, a thermal reaction of the source gas occurs on the surface of the wafer
Implementation Method 3
there is known an epitaxial growth technique of growing a single-crystal film on a substrate such as a wafer by the vapor phase growth
Implementation Method 4
different gases are separated in different gas diffusion chambers until the source gas is introduced into the reaction chamber in order to appropriately mix the different gases
Data Source
AI summary
A vapor phase growth apparatus of an embodiment includes: a reaction chamber; a shower plate disposed in the upper portion of the reaction chamber to supply a gas into the reaction chamber; and a support portion disposed below the shower plate inside the reaction chamber to place a substrate thereon. Then, the shower plate includes a plurality of first and second lateral gas passages disposed within different horizontal planes and first and second gas ejection holes connected to the first and second lateral gas passages. Further, the shower plate includes a center lateral gas passage that passes through a position directly above the rotation center of the support portion and third gas ejection holes connected to the center lateral gas passage. Then, the gases ejected from the first and second gas ejection holes and the center gas ejection holes are independently controllable.