Quartz Light Diffusion Plate for Uniform Wafer Flash Heating
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing heat treatment apparatuses for semiconductor wafers face challenges in achieving uniform in-plane illuminance distribution due to non-uniform light irradiation from xenon flash lamps, leading to variations in temperature distribution and inefficient energy use.
Innovation Solution
The apparatus incorporates a light diffusion plate with a size smaller than the substrate, positioned between the holder and the light irradiation part, featuring recessed or protruding curved surfaces. This design diffuses part of the light toward the peripheral portion of the substrate, enhancing in-plane uniformity without wastefully consuming light.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If flash lamps are disposed in a region considerably larger than the area of a semiconductor wafer, then the illuminance of the peripheral portion of the semiconductor wafer becomes lower than that of the central portion, causing nonuniform illuminance distribution
Solution Approach 1:
A light diffusion plate is introduced as an intermediary component between the flash lamps and the semiconductor wafer. This plate diffuses the light from the lamps, redistributing it to achieve more uniform illuminance across the wafer surface, particularly enhancing light distribution to the peripheral regions while maintaining central region illumination.
2Illumination intensity
If the illuminance distribution is adjusted by contriving the power balance of flash lamps, light emission density, lamp layout, reflectors and the like, then the in-plane uniformity of illuminance distribution can be improved, but the adjustment becomes significantly difficult and requires adjustment of a large number of parts and set values
Solution Approach 1:
The light diffusion plate serves as a passive intermediary that automatically achieves illuminance uniformity without requiring active adjustment of multiple lamp parameters. The plate's optical properties inherently redistribute light to achieve uniform illumination, eliminating the need for complex power balance adjustments of multiple lamps, reflectors, and other components.
Solution Approach 2:
Instead of adjusting multiple operational parameters (lamp power, emission density, layout positions, reflector angles), the invention changes the physical parameter of the light diffusion plate itself - its optical diffusion characteristics. This single parameter change achieves the same effect as coordinating multiple parameter adjustments across numerous components.
3Illumination intensity
If an illuminance adjustment plate smaller than a semiconductor wafer is provided between flash lamps and a semiconductor wafer, then the in-plane uniformity of illuminance distribution is improved, but part of flashes of light emitted from the flash lamps are wasted
Solution Approach 1:
The light diffusion plate is designed with specific optical parameters - its size, material properties, and surface characteristics - that enable it to diffuse light effectively across the entire wafer area. The plate's diffusion efficiency and area are optimized to minimize light waste while achieving uniform illuminance distribution.
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 effectively increases the in-plane uniformity of the illuminance distribution on the substrate, ensuring a uniform temperature distribution and improving energy efficiency by preventing wasteful consumption of light.
Implementation Method 1
a light diffusion plate provided between the holder and the light irradiation part and having a size smaller than that of the substrate as seen in plan view
Implementation Method 2
The xenon flash lamps have a spectral distribution of radiation ranging from ultraviolet to near-infrared regions. The wavelength of light emitted from the xenon flash lamps is shorter than that of light emitted from conventional halogen lamps, and approximately coincides with a fundamental absorption band of a silicon semiconductor wafer. Thus, when a semiconductor wafer is irradiated with a flash of light emitted from the xenon flash lamps, the temperature of the semiconductor wafer can be raised rapidly
Data Source
AI summary
A light diffusion plate made of quartz and provided with a plurality of recessed spherical surfaces is placed on an upper chamber window so as to be in opposed relation to a central portion of a semiconductor wafer. Flashes of light emitted from flash lamps and passing by the side of the light diffusion plate impinge upon a peripheral portion of the semiconductor wafer. On the other hand, flashes of light emitted from the flash lamps and entering the light diffusion plate are diverged by the recessed spherical surfaces. Part of the light entering the light diffusion plate is diffused toward the peripheral portion of the semiconductor wafer. As a result, this increases the amount of light impinging upon the peripheral portion of the semiconductor wafer, and decreases the amount of light impinging upon the central portion of the semiconductor wafer.