Circular Lamp Arrays for Uniform Thermal Processing
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Solution Overview
Problem
In semiconductor processing, achieving uniformity in substrate temperature and radiation distribution is challenging due to variations in local substrate temperature, gas flows, and precursor concentrations, which affects the formation of thin material layers with consistent properties.
Innovation Solution
A lamphead apparatus with multiple reflective troughs angled relative to the normal plane, positioned to direct radiation uniformly across the substrate, combined with a substrate support system that minimizes thermal and gas flow non-uniformities, and a controller that adjusts power delivery to lamps based on thermal data from sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If heat lamps are positioned outside the processing chamber to avoid contaminants, then chamber contamination is reduced, but radiation uniformity across the substrate surface deteriorates
Solution Approach 1:
The patent transitions from a single-plane lamp arrangement to a multi-dimensional circular array of lampheads positioned at different radial distances and angles around the substrate. This three-dimensional configuration allows radiation to be delivered from multiple spatial dimensions, achieving uniform coverage while keeping all lamps outside the chamber volume.
Solution Approach 2:
The patent employs asymmetric positioning of lampheads at different radial distances (inner, middle, outer rings) and angles around the substrate. This asymmetric arrangement compensates for the inverse-square law of radiation decay, ensuring that lamps farther from the substrate provide broader coverage while closer lamps provide more intense localized heating, achieving overall uniformity without requiring all lamps to be equidistant.
2Power
If multiple lamps are used to provide sufficient heating power, then thermal processing capability is improved, but radiation uniformity across the substrate deteriorates
Solution Approach 1:
The patent divides the heating system into multiple independent lamphead segments arranged in a circular array. Each lamphead can be individually controlled and positioned at specific radial distances and angles. This segmentation allows the system to provide high total power while maintaining uniformity, as each segment contributes to a different region of the substrate and can be independently optimized.
Solution Approach 2:
The patent implements local quality by positioning lampheads with different characteristics at different locations around the substrate. Inner ring lamps may be positioned closer to provide intense heating for the substrate center, while outer ring lamps are positioned farther away to provide broader coverage for the substrate periphery. Each location has optimized lamp characteristics tailored to its specific heating requirements.
3Device complexity
If simple lamp positioning is used to reduce device complexity, then manufacturing ease is improved, but radiation uniformity and thermal processing capability deteriorate
Solution Approach 1:
The patent employs a circular/spheroidal arrangement of lampheads around the substrate, replacing simple linear or planar positioning. This curved, radial configuration naturally provides more uniform angular distribution of radiation across the substrate surface. The circular geometry also simplifies the mechanical support structure, as all lampheads can be mounted on a rotating or stationary circular framework rather than complex multi-axis positioning mechanisms.
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 ensures improved radiation uniformity and thermal processing, resulting in more consistent film thickness and composition across the substrate surface, enhancing the quality of epitaxial material layers.
Implementation Method 1
A reflective trough may be formed in the body and a focal axis of the trough may be angled relative to an axis normal to the plane defined by the bottom surface
Implementation Method 2
Heat is normally provided by heat lamps positioned outside the vessel
Data Source
AI summary
Embodiments disclosed herein relate to circular lamp arrays for use in a semiconductor processing chamber. Circular lamp arrays utilizing one or more torroidal lamps disposed in a reflective trough and arranged in a concentric circular pattern may provide for improved rapid thermal processing. The reflective troughs, which may house the torroidal lamps, may be disposed at various angles relative to a surface of a substrate being processed.