Flat Pocket Susceptor Layout for Uniform Wafer Heating
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Solution Overview
Problem
Existing susceptors cause temperature non-uniformity across semiconductor substrates due to non-uniform heat transfer, leading to reduced quality of deposited layers.
Innovation Solution
A susceptor design with an inner region featuring a pattern of substrate support features separated by venting channels, reducing the contacting surface area between the susceptor and the substrate, and incorporating radial bumps to center the substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the susceptor uses a large contacting surface area to support the substrate, then the substrate is well-supported, but temperature non-uniformity increases due to non-uniform heat transfer
Solution Approach 1:
The susceptor surface is segmented into discrete contact regions (protrusions) rather than a continuous large surface. This segmentation reduces the total contacting surface area while maintaining adequate substrate support, allowing more uniform heat distribution across the substrate by minimizing localized heat transfer variations.
2Use of energy by moving object
If the susceptor contacts the substrate over a large area, then heat transfer is efficient, but temperature non-uniformity and hot spots increase
Solution Approach 1:
The contact area is segmented into multiple small protrusions rather than one large continuous area. This maintains sufficient thermal coupling for efficient heat transfer while distributing the heat transfer paths to reduce temperature non-uniformity and hot spot formation.
Solution Approach 2:
The susceptor surface has different local properties: protrusions with higher thermal contact for efficient heat transfer, and recessed areas with lower thermal contact to reduce hot spots. This local differentiation optimizes both heat transfer efficiency and temperature uniformity.
3Ease of manufacture
If the susceptor has a flat top surface, then manufacturing is simple, but temperature non-uniformity occurs across the substrate
Solution Approach 1:
Instead of a completely flat surface, the susceptor has a segmented top surface with protrusions and recesses. This modification can be achieved through relatively simple processes like casting, molding, or additive manufacturing, maintaining ease of manufacture while significantly improving temperature uniformity.
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 improves thermal uniformity across the substrate by reducing conductive heat transfer and enhancing radiant heat transfer, resulting in better processing results and reduced hot spots.
Implementation Method 1
The susceptor is supported by a support shaft, which is rotatable about a central axis. Precise control over a heating source, such as a plurality of heating lamps disposed below the susceptor, allows a susceptor to be heated within very strict tolerances. The heated susceptor can then transfer heat to the substrate, primarily by radiation emitted by the susceptor.
Implementation Method 2
it has been observed that the susceptor may cause temperature non-uniformity across the substrate due to non-uniform heat transfer between regions of the substrate in contact with the susceptor and regions of the substrate not in contact with the susceptor
Data Source
AI summary
Embodiments of the present disclosure generally relate to a susceptor for thermal processing of semiconductor substrates. In one embodiment, the susceptor includes an inner region having a pattern formed in a top surface thereof, the pattern including a plurality of substrate support features separated by a plurality of venting channels. The susceptor includes a rim surrounding and coupled to the inner region, wherein the inner region is recessed relative to the rim to form a recessed pocket configured to receive a substrate. The susceptor includes a plurality of bumps extending radially inward from an inner diameter of the rim, the plurality of bumps configured to contact an outer edge of a substrate supported by the plurality of substrate support features for positioning the substrate within the recessed pocket.