Susceptor Surface Structures for Wafer Temperature Uniformity
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing susceptors for semiconductor substrates during thermal processing, such as epitaxy, face challenges in maintaining uniform temperature across the substrate, leading to undesirable temperature profiles near the edges and center, which affects the quality of deposited layers.
Innovation Solution
The susceptor design includes an outer rim surrounding an inner dish with features like wedges and bumps to reduce the contacting surface area between the substrate and the susceptor, utilizing gaps and insulating separators to minimize conductive heat transfer, while maintaining radiative heat transfer, thereby improving thermal uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the susceptor uses a platter or dish-shaped upper surface to support the substrate, then the substrate is supported from below around the edges, but temperature non-uniformities persist across the upper surface of the substrate
Solution Approach 1:
The susceptor surface is segmented into multiple elevated structures (wedges, ridges, bumps) distributed across the inner dish surface, creating discrete contact points rather than a continuous surface. This segmentation reduces the total contacting surface area between substrate and susceptor, minimizing conductive heat transfer zones that cause temperature non-uniformities.
Solution Approach 2:
The elevated structures are strategically positioned at specific locations on the inner dish surface, including near the inner edge of the outer rim and at other predetermined positions. This local placement creates zones of reduced thermal interaction at critical areas where temperature non-uniformities typically occur, such as near substrate edges and center regions.
2Measurement precision
If heating lamps are disposed below the susceptor with precise control, then the susceptor can be heated within very strict tolerances, but temperature non-uniformities still occur near the edges and center of the substrate
Solution Approach 1:
The elevated structures on the susceptor surface act as thermal intermediaries that modulate the heat transfer between the heated susceptor and the substrate. By creating gaps and reducing contact areas, these structures prevent excessive conductive heat transfer at specific locations, allowing the radiative heating from lamps to dominate and produce more uniform temperature profiles across the substrate surface.
3Temperature
If the susceptor transfers heat to the substrate primarily by radiation, then temperature control is improved, but conductive heat transfer through the contacting surface area creates hotspots
Solution Approach 1:
The design extracts or removes portions of the contacting surface area between the susceptor and substrate by creating elevated structures and gaps. This reduction in contact area removes the harmful conductive heat transfer pathways that generate hotspots, allowing the beneficial radiative heat transfer to dominate the thermal interaction.
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 design enhances thermal uniformity by reducing conductive heat transfer, preventing hotspots, and ensuring higher quality layer deposition by increasing the radiant heat transfer percentage, thus improving the overall temperature control during thermal processing.
Implementation Method 1
The heated susceptor can then transfer heat to the substrate, primarily by radiation emitted by the susceptor
Implementation Method 2
one or more structures for reducing a contacting surface area between a substrate and the susceptor when the substrate is supported by the susceptor
Data Source
AI summary
In one embodiment, a susceptor for thermal processing is provided. The susceptor includes an outer rim surrounding and coupled to an inner dish, the outer rim having an inner edge and an outer edge. The susceptor further includes one or more structures for reducing a contacting surface area between a substrate and the susceptor when the substrate is supported by the susceptor. At least one of the one or more structures is coupled to the inner dish proximate the inner edge of the outer rim.