Susceptor Surface Patterning for Wafer Temperature Uniformity
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Solution Overview
Problem
Existing heat treatment apparatuses using xenon flash lamps and halogen lamps suffer from non-uniform in-plane temperature distribution in semiconductor wafers, with conventional solutions like cylindrically shaped louvers and roughened susceptor regions failing to achieve sufficient uniformity.
Innovation Solution
A susceptor with a planar holding plate and substrate support pins, featuring mixed processing and non-processing regions with varying surface roughness, reduces light transmittance to improve temperature uniformity by adjusting light impingement on high-temperature regions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If halogen lamps are arranged in two tiers to preheat the substrate, then the preheating efficiency is improved, but the in-plane temperature distribution becomes non-uniform with the center becoming too hot
Solution Approach 1:
The susceptor surface is divided into different regions with different light transmittance properties. The central region has reduced light transmittance to prevent excessive heating, while the peripheral region maintains higher light transmittance for effective preheating. This local differentiation of optical properties resolves the contradiction between achieving high preheating temperature and maintaining uniform temperature distribution.
2Manufacturing precision
If a cylindrically shaped louver is used to reduce light impingement on the substrate center, then the temperature uniformity is improved, but the device complexity increases
Solution Approach 1:
Instead of adding a separate louver component to control light distribution, the invention extracts the light control function directly into the susceptor structure by creating regions with different light transmittance. This integration eliminates the need for additional complex components while achieving the same temperature uniformity effect.
3Manufacturing precision
If the susceptor is made completely opaque to block light, then the temperature uniformity is improved, but the preheating efficiency decreases
Solution Approach 1:
The susceptor employs spatially varying optical properties where the central region is more opaque to reduce light impingement and the peripheral region is more transparent to maintain preheating efficiency. This local quality differentiation allows the system to achieve both temperature uniformity and adequate preheating speed without making the entire susceptor completely opaque.
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 enhances the uniformity of in-plane temperature distribution by decreasing light impingement on high-temperature regions, thereby improving the overall temperature uniformity of the substrate.
Implementation Method 1
each of the processing regions has a roughened surface... decreases the transmittance of the processing regions to decrease the amount of light impinging on the high-temperature region of the substrate
Implementation Method 2
a susceptor which supports a substrate W when the substrate W is subjected to heating by light irradiation
Data Source
AI summary
Halogen lamps irradiate a semiconductor wafer held by a susceptor with light to preheat the semiconductor wafer, and thereafter flash lamps irradiate the semiconductor wafer with flashes of light. Processing regions and non-processing regions are provided in a mixed manner in a region of a holding plate of the susceptor which is opposed to a high-temperature region of the semiconductor wafer in a temperature distribution occurring in the semiconductor wafer when the semiconductor wafer is irradiated with light. The processing regions and the non-processing regions have annular shapes arranged alternatingly in a concentric pattern. The processing regions are roughened by a sandblasting process, and the non-processing regions are not processed. This decreases the transmittance of the processing regions to decrease the amount of light impinging on the high-temperature region of the semiconductor wafer, thereby improving the uniformity of an in-plane temperature distribution of the semiconductor wafer.