Reflective Deposition Rings for Substrate Temperature Uniformity
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Solution Overview
Problem
Space constraints in semiconductor reflow chambers limit the area of reflective surfaces, leading to non-uniform temperature distribution across semiconductor substrates during thermal treatment, which affects the reflow and conformal distribution of deposited materials.
Innovation Solution
An annular deposition ring with a reflective surface area of 5 to 50 percent of its total surface area is used to direct heat energy toward the central axis, combined with a radiant energy source and reflector to enhance temperature uniformity by irradiating the less reflective backside of the substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a reflective surface is used to direct radiation toward the backside of the substrate, then temperature uniformity is improved, but the area of the reflective surface is limited by space constraints
Solution Approach 1:
The reflective surface is segmented into multiple discrete reflective elements (reflectors) positioned at different locations around the substrate. Instead of requiring one large continuous reflective surface, the system uses multiple smaller reflective surfaces that collectively direct radiation onto the substrate backside, overcoming space constraints within the chamber.
Solution Approach 2:
The reflective surfaces are positioned in three-dimensional space around the substrate at various angular orientations rather than forming a single planar surface. This spatial arrangement allows radiation to be directed onto the substrate from multiple angles, achieving temperature uniformity without requiring a large single-area reflective surface.
2Manufacturing precision
If the front side of the substrate is highly reflective, then deposition quality is maintained, but heating efficiency is reduced
Solution Approach 1:
The substrate has different surface properties on different sides: the front side maintains high reflectivity for quality deposition, while the backside has lower reflectivity (higher absorptivity) for efficient heating. This local differentiation of surface properties allows each side to optimize its function without compromising the other.
Solution Approach 2:
Instead of heating the substrate through its highly reflective front side, the system inverts the approach by heating through the backside which has opposite optical properties (lower reflectivity, higher absorptivity). This inversion allows efficient energy absorption while preserving front-side deposition quality.
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 improves temperature uniformity across the substrate, enhances energy efficiency by reducing reflectivity on the front side, and allows for efficient thermal processing without removing the substrate from the chamber, facilitating a reflow process that reduces material overhang in substrate features.
Implementation Method 1
the first surface includes at least one reflective portion configured to reflect heat energy toward a central axis of the annular body
Implementation Method 2
a radiant energy source positioned at a peripheral region of the substrate processing chamber
Data Source
AI summary
Apparatus for improving temperature uniformity across a substrate are provided herein. In some embodiments, a deposition ring for use in a substrate processing system to process a substrate may include an annular body having a first surface, an opposing second surface, and a central opening passing through the first and second surfaces, wherein the second surface is configured to be disposed over a substrate support having a support surface to support a substrate having a given width, and wherein the opening is sized to expose a predominant portion of the support surface; and wherein the first surface includes at least one reflective portion configured to reflect heat energy toward a central axis of the annular body, wherein the at least one reflective portion has a surface area that is about 5 to about 50 percent of a total surface area of the first surface.