Rough Surface UV Window for Wafer Curing Uniformity
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Solution Overview
Problem
Existing UV curing apparatuses for semiconductor wafers suffer from non-uniform UV radiation distribution, leading to inconsistent dielectric film curing and increased 'within wafer' shrinkage, which affects the electrical performance of devices, especially as wafer sizes increase from 300 mm to 450 mm.
Innovation Solution
The apparatus incorporates a UV transparent window with a rough surface and reflectors having alternating rough and smooth zones to scatter and redirect UV radiation, ensuring uniform UV intensity across the wafer surface, thereby mitigating localized shrinkage and improving electrical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a conventional UV curing apparatus uses a standard transparent window and smooth reflectors, then the apparatus structure is simple and easy to manufacture, but the UV radiation distribution is non-uniform causing inconsistent dielectric film curing and increased within wafer shrinkage
Solution Approach 1:
The patent applies local quality by creating specific rough surface zones at defined positions on the transparent window and reflectors. Instead of making the entire surfaces rough, only specific regions (such as the center region of the window and specific zones on reflectors) are textured with controlled roughness parameters (Ra values). This localized texturing scatters UV radiation in specific patterns to achieve uniform distribution across the wafer surface while maintaining simplicity elsewhere in the apparatus structure.
2Productivity
If the wafer size is increased from 300 mm to 450 mm to improve productivity, then the processing capacity increases, but the non-uniformity of UV radiation becomes more pronounced leading to greater shrinkage issues
Solution Approach 1:
The patent addresses the uniformity problem on larger wafers by introducing spatial distribution of roughness across the window and reflector surfaces. The rough surface zones are strategically positioned and sized according to their distance from the UV source and their relationship to the wafer surface, creating a three-dimensional radiation scattering pattern that compensates for the increased wafer area. This dimensional approach to radiation distribution maintains curing uniformity across 450 mm wafers.
3Illumination intensity
If smooth surfaces are used on the transparent window and reflectors, then the manufacturing process is simpler and cleaning is easier, but UV radiation is not scattered adequately resulting in localized high intensity regions and non-uniform curing
Solution Approach 1:
The patent applies parameter changes by controlling the surface roughness parameter (Ra value) of specific zones on the window and reflectors. The roughness parameter is optimized to scatter UV radiation effectively while maintaining manufacturability. By specifying Ra values within certain ranges for different zones, the patent achieves uniform UV intensity distribution without requiring complete surface texturing, thus balancing manufacturing ease with illumination uniformity.
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 uniform UV radiation distribution, reducing localized shrinkage and enhancing the electrical performance of semiconductor devices by scattering UV radiation and maintaining consistent curing across the wafer surface.
Implementation Method 1
a first zone (136-1) having a first rough surface (138-1)... scattering UV radiation
Implementation Method 2
a primary reflector (140) disposed in the UV radiation source (120)... configured to reflect the radiation toward the transparent window (130)
Data Source
AI summary
An apparatus for wafer processing includes a wafer pedestal configured to support a wafer, a radiation source configured to provide an electromagnetic radiation to the wafer, and a transparent window disposed between the wafer pedestal and the radiation source. The transparent window has a first zone having a first rough surface, and an Ra value of the first rough surface is between approximately 0.5 μm and approximately 100 μm. The apparatus for wafer processing further includes a primary reflector disposed in the radiation source, and a secondary reflector disposed between the transparent window and the radiation source. The rough surface can be provided over the transparent window, the primary reflector, and/or the secondary reflector.