Susceptor Gas Release Grooves Prevent Wafer Skidding
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Solution Overview
Problem
Existing susceptor designs for vapor phase epitaxial growth devices often result in wafer skidding during loading due to uneven gas release, especially with high-accuracy wafer pockets and large diameter wafers, leading to non-uniform epitaxial film thickness and reduced wafer flatness.
Innovation Solution
A susceptor design featuring a wafer pocket with a sloping support plane, a ring-shaped groove on the outer circumference, and gas release openings with a controlled opening area ratio and shape to ensure even gas release and prevent skidding, allowing for precise loading and uniform film deposition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If through holes with large diameter or high ratio of opening area are used to release gases during wafer loading, then gas release capability is improved, but wafer skidding occurs due to unbalanced gas release
Solution Approach 1:
The patent applies local quality by creating different regions with different gas release characteristics. The ring-shaped groove provides concentrated gas release at the outer circumference, while the center region maintains minimal gas release. This localized differentiation allows efficient gas evacuation without causing wafer skidding, as the gas release is strategically positioned rather than uniformly distributed.
Solution Approach 2:
The gas release function is segmented into two distinct components: the ring-shaped groove structure and the through holes. The ring-shaped groove handles the primary gas release function at the outer circumference, while through holes provide supplementary release. This segmentation allows each component to perform its specific function optimally without interfering with wafer stability.
2Reliability
If a flat loading surface with through holes is used to prevent wafer skidding, then gas release is improved, but uniformity of epitaxial film thickness on wafer back surface deteriorates
Solution Approach 1:
The invention applies local quality by positioning the ring-shaped groove at the outer circumference of the wafer pocket, creating a localized gas release region. This prevents gas accumulation at the wafer back surface that would occur with widespread through holes, thereby maintaining uniform epitaxial film thickness while still preventing wafer skidding through controlled gas release at the periphery.
3Measurement precision
If high accuracy wafer pocket is manufactured to ensure precise wafer positioning, then positioning precision is improved, but minute clearance for gas release becomes insufficient
Solution Approach 1:
The patent resolves this contradiction by transitioning from a two-dimensional through-hole approach to a three-dimensional ring-shaped groove structure. The groove provides volumetric gas release capacity without compromising the precision of wafer positioning, as it operates in the circumferential dimension rather than interfering with the central positioning interface between wafer and pocket.
4Productivity
If Bernoulli chuck is used to drop large diameter wafer with super flatness, then loading efficiency is improved, but wafer skidding occurs due to insufficient gas release through through holes
Solution Approach 1:
The gas release function is segmented between the ring-shaped groove (primary release path) and through holes (secondary release path). This segmentation enables efficient gas evacuation during high-speed Bernoulli chuck loading, preventing wafer skidding while maintaining loading productivity. The ring-shaped groove provides sufficient gas release capacity without requiring excessive through hole area.
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
The susceptor design effectively prevents wafer skidding and ensures uniform epitaxial film thickness across the wafer surface, improving the flatness and reducing slip defects caused by temperature differences, while maintaining stable gas flow and pressure balance.
Implementation Method 1
a plurality of gas release openings extending from the ring-shaped groove to penetrate to the back surface of the susceptor, each having an opening area of 2.0 to 3.0 mm2 and having a ratio of opening areas to the bottom surface of 0.25 to 0.5%
Data Source
AI summary
There is provided a susceptor for a vapor phase epitaxial growth device, by which skidding at the time of loading a silicon wafer is prevented and the wafer can be loaded at a fixed position of the susceptor: wherein a ring-shaped groove having sloping planes widening toward a surface of the susceptor are formed on the outermost circumference of the bottom surface; and gas release openings penetrating through to the back surface of the susceptor are formed, each having a sectional area of 2.0 to 3.0 mm2 and a ratio of all opening areas is 0.25 to 0.5% on the bottom surface.