Quartz Susceptor Backside Roughening for Wafer Temperature Uniformity
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Solution Overview
Problem
Conventional heat treatment apparatuses using xenon flash lamps suffer from non-uniform temperature distributions in both radial and circumferential directions of semiconductor wafers, leading to issues like deep ion diffusion and cold spots, which hinder effective device formation.
Innovation Solution
A heat treatment apparatus with a susceptor having a transparent main body and a ground-glass-like backside surface to diffuse light, improving temperature uniformity by reflecting light to peripheral areas and reducing light transmission to the hot plate, thereby enhancing within-wafer uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If xenon flash lamps are used to rapidly heat the semiconductor wafer surface, then ion activation is achieved without deep ion diffusion, but non-uniform temperature distribution occurs in both radial and circumferential directions
Solution Approach 1:
The susceptor is designed with a ground-glass-like roughened surface specifically on its backside (opposite the wafer contact side), creating localized light diffusion properties where needed. This roughened surface structure selectively scatters light in the peripheral regions to improve temperature uniformity without affecting the central heating zone, thus resolving the non-uniform temperature distribution problem while maintaining precise ion activation capability
Solution Approach 2:
The susceptor with ground-glass-like surface acts as an intermediary element between the xenon flash lamps and the semiconductor wafer. It mediates the light energy distribution by diffusing and scattering the intense flash light, particularly redirecting light to peripheral areas that would otherwise be underheated, thereby achieving uniform temperature distribution across the wafer surface
2Productivity
If light transmittance is increased to improve heating efficiency, then rapid temperature rise is achieved, but hot plate damage from excessive light exposure increases
Solution Approach 1:
The ground-glass-like roughened surface of the susceptor converts the potentially harmful excessive light energy into beneficial diffuse reflection. Instead of allowing concentrated light to damage the hot plate, the roughened surface scatters the light in multiple directions, with much of it being reflected back toward the wafer periphery, thus protecting the hot plate while enhancing heating uniformity and efficiency
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 solution achieves improved temperature distribution uniformity, especially in peripheral areas, reducing ion diffusion and cold spots, while minimizing hot plate damage from excessive light exposure.
Implementation Method 1
a susceptor having a frontside surface and a backside surface for holding the substrate on the frontside surface thereof within the chamber, the susceptor being formed of a transparent material, only the backside surface of the susceptor being a ground-glass-like substrate
Implementation Method 2
improving temperature uniformity by reflecting light to peripheral areas
Implementation Method 3
the susceptor being formed of a transparent material
Data Source
AI summary
A susceptor for holding a semiconductor wafer to be flash-heated by a flash of light emitted from flash lamps is formed of transparent quartz. The susceptor has a backside surface only which is roughened by shot blasting to provide a ground-glass-like surface. When a flash of light is emitted, part of the flash of light emitted from the flash lamps and passing by a peripheral portion of the semiconductor wafer held by the susceptor into the susceptor reaches the ground-glass-like backside surface and is diffusely reflected therefrom. Part of the diffusely reflected light impinges on the peripheral portion of the semiconductor wafer held by the susceptor to thereby heat the low temperature regions which have appeared in the peripheral portion of the semiconductor wafer.