Segmented Susceptor Design for Epitaxial Wafer Uniformity
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Solution Overview
Problem
Existing susceptor designs for epitaxial growth in semiconductor manufacturing lead to wafer contamination, displacement, and non-uniform temperature distribution, resulting in crystal defects and reduced yield due to inadequate support and gas flow management.
Innovation Solution
A susceptor design featuring an annular first portion for peripheral wafer support and a second portion that covers the opening, with strategically placed gaps to prevent contamination and ensure uniform heating, maintaining the wafer's position and promoting even temperature distribution across the substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the wafer is supported only on a narrow peripheral portion of an annular susceptor, then the susceptor structure is simple and easy to manufacture, but the wafer may be contaminated with metal atoms from the heating unit and rotary portion, degrading electrical characteristics
Solution Approach 1:
The susceptor is divided into two distinct portions: an annular first susceptor portion for supporting the wafer periphery and a disc-like second susceptor portion that covers the opening of the first portion. This segmentation prevents contaminants from reaching the wafer while maintaining structural simplicity
Solution Approach 2:
The second susceptor portion acts as an intermediary barrier between the heating unit/rotary portion and the wafer, blocking metal atom contaminants while still allowing thermal energy to reach the wafer through conduction
2Device complexity
If the susceptor is annular in shape with a gap between the wafer and susceptor, then gas flow is simplified, but mixed gas flows through the gap to form an epitaxial film between the wafer and susceptor, causing attachment and crystal defects
Solution Approach 1:
The susceptor is segmented into two portions where the second portion extends to cover the opening, physically blocking the gas flow path that would otherwise allow mixed gas to reach the interface between the wafer and susceptor, preventing unwanted film formation
Solution Approach 2:
The harmful gas flow path through the gap is extracted or eliminated by the second susceptor portion, which blocks the direct path of mixed gas that causes epitaxial film formation and wafer attachment
3Stability of the object's composition
If the entire bottom surface of the wafer is in contact with the susceptor for support, then the wafer is stable and不易 displaced, but the wafer warps concavely upward due to heat, preventing proper film formation
Solution Approach 1:
The susceptor contact area is segmented into two regions: the annular first portion that contacts only the peripheral portion of the wafer to provide stability, and the second portion that covers the opening but does not contact the wafer, allowing the central area to remain free for proper thermal distribution and preventing concave warping
Solution Approach 2:
Different regions of the susceptor have different functions: the annular first portion provides mechanical support and stability, while the central region (covered by the second portion) allows controlled thermal exposure to prevent warping and enable proper film 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
The design effectively reduces wafer attachment to the susceptor, minimizes contamination, and achieves uniform temperature distribution, preventing crystal defects and enhancing the yield of epitaxial films with consistent thickness.
Implementation Method 1
a heating unit for heating the substrate through the susceptor
Implementation Method 2
the mixture of material gas and carrier gas introduced into the reaction chamber flows radially across the top surface of the wafer from the center portion to the peripheral portion of the top surface due to the centrifugal force generated by the rotation of the wafer
Implementation Method 3
the wafer is subjected to epitaxial growth while it is rotated at high speed
Data Source
AI summary
In accordance with the embodiment of the present invention, there is provided a susceptor which includes an annular first susceptor portion for supporting the peripheral portion of a silicon wafer and further includes a second susceptor portion provided in contact with the peripheral portion of the first susceptor portion and covering the opening of the first susceptor portion. The second susceptor portion is disposed so that, when the silicon wafer is supported on the first susceptor portion, a gap of a predetermined size is formed between the silicon wafer and the second susceptor portion, and so that another gap of a size substantially equal to the predetermined size and directly connected to the above gap is formed between the first susceptor portion and the second susceptor portion.