Wafer Carrier Ring for Uniform Boundary Layer Thickness
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Solution Overview
Problem
Existing wafer processing systems face challenges in maintaining uniform boundary layer thickness, leading to non-uniform deposition rates and reduced productivity due to limitations in wafer carrier design, which restricts the number and size of wafers that can be processed.
Innovation Solution
The introduction of a ring structure within the reactor chamber that surrounds the wafer carrier, creating a continuous gas flow similar to a larger diameter carrier, allowing wafers to be positioned closer to the periphery and maintaining a uniform boundary layer thickness across the entire carrier surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the wafer carrier diameter is increased to accommodate more wafers or larger wafers, then productivity increases, but the boundary layer thickness becomes non-uniform across the carrier surface
Solution Approach 1:
The gas distribution is segmented into multiple zones: a central gas distribution element and a peripheral ring gas distribution element. This segmentation allows independent control of gas flow to different regions of the carrier, enabling uniform boundary layer thickness across the entire carrier surface even when the carrier diameter is large enough to hold multiple or larger wafers.
Solution Approach 2:
Different regions of the carrier receive tailored gas flow characteristics through the segmented distribution system. The central and peripheral regions have optimized gas flow rates and distribution patterns locally adapted to their specific requirements, ensuring uniform boundary layer thickness across the entire carrier surface while accommodating larger or more wafers.
2Productivity
If the wafer carrier diameter is increased to improve productivity, then more wafers can be processed, but the deposition rate uniformity deteriorates
Solution Approach 1:
The gas distribution system is divided into central and peripheral segments that independently control gas flow to different radial zones of the carrier. This enables uniform deposition rates across the entire carrier surface area, allowing the carrier diameter to be increased for higher productivity without sacrificing deposition uniformity.
Solution Approach 2:
The gas flow parameters (flow rate, distribution pattern) are changed and optimized for different regions of the carrier. By adjusting these parameters locally through the segmented distribution system, uniform deposition rates are maintained across the entire carrier surface even when the carrier size is increased to improve productivity.
3Productivity
If the boundary layer thickness is reduced to increase deposition rate, then processing efficiency improves, but the boundary layer becomes non-uniform across the carrier surface
Solution Approach 1:
The gas distribution is segmented into central and peripheral zones with independently controllable flow rates. This allows the boundary layer thickness to be reduced uniformly across the entire carrier surface by optimizing gas flow in each segment, increasing deposition rate while maintaining boundary layer uniformity through coordinated control of both segments.
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 more efficient processing by ensuring uniform deposition rates across all wafers, increasing the capacity and throughput of the system while maintaining uniformity, and promoting the effective use of expensive treatment gases.
Implementation Method 1
In a chemical vapor deposition process, numerous wafers are held on a device commonly referred to as a wafer carrier so that a top surface of each wafer is exposed at the top surface of the wafer carrier. The wafer carrier is then placed into a reaction chamber and maintained at the desired temperature while the gas mixture flows over the surface of the wafer carrier.
Implementation Method 2
The outwardly-flowing gas forms a boundary layer covering the top surface of the wafer carrier. The used gas flows downwardly around the periphery of the wafer and is evacuated from the reaction chamber through ports disposed below the wafer carrier.
Implementation Method 3
the gas is directed downwardly onto the top surface of the wafer carrier and flows across the top surface toward the periphery of the wafer carrier. The outwardly-flowing gas forms a boundary layer covering the top surface of the wafer carrier.
Implementation Method 4
The wafer carrier is supported on a spindle within the reaction chamber so that the top surface of the wafer carrier having the exposed surfaces of the wafers faces upwardly toward a gas distribution element. While the spindle is rotated, the gas is directed downwardly onto the top surface of the wafer carrier and flows across the top surface toward the periphery of the wafer carrier.
Implementation Method 5
The wafer carrier is maintained at the desired elevated temperature by heating elements, typically electrical resistive heating elements disposed below the bottom surface of the wafer carrier.
Implementation Method 6
The wafer carrier is maintained at the desired elevated temperature by heating elements, typically electrical resistive heating elements disposed below the bottom surface of the wafer carrier.
Implementation Method 7
The ring is movably mounted within the chamber so that it does not impede loading or unloading of carriers. The ring forms an extension of the carrier, so the gas flow is similar to that which would be obtained with a carrier of larger diameter.
Data Source
AI summary
Apparatus for treating wafers using a wafer carrier rotated about an axis is provided with a ring which surrounds the wafer carrier during operation. Treatment gasses directed onto a top surface of the carrier flow outwardly away from the axis over the carrier and over the ring, and pass downstream outside of the ring. The outwardly flowing gasses form a boundary over the carrier and ring. The ring helps to maintain a boundary layer of substantially uniform thickness over the carrier, which promotes uniform treatment of the wafers.