Substrate Mask Alignment via Reflectance Modification
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Solution Overview
Problem
Conventional methods face challenges in accurately aligning opaque substrates with masks due to similar reflectance, making it difficult to achieve proper alignment, especially when using optical sensors.
Innovation Solution
The method involves forming alignment holes in both the substrate and mask with different widths and creating treatment regions around these holes to modify surface reflectance, allowing for improved optical distinction and alignment using a sensor unit, such as a CCD camera.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If alignment holes are formed in opaque substrate and mask for alignment, then alignment can be performed, but the similar reflectance of opaque substrate and mask reduces visibility of boundary line making accurate alignment difficult
Solution Approach 1:
The patent applies the color changes principle by modifying the surface reflectance of either the substrate or mask around the alignment holes to create treatment regions with different reflectance characteristics. This creates visible contrast between the treatment region and surrounding areas, enabling clear detection of alignment hole positions and boundary lines through optical sensors or visual inspection, thereby resolving the visibility issue while maintaining alignment accuracy
Solution Approach 2:
The patent changes the reflectance parameter of the substrate or mask surface by creating treatment regions with modified optical properties. This parameter change creates distinct visual contrast that allows optical detection systems to clearly identify alignment holes and boundary lines, solving the detection difficulty while preserving manufacturing precision
2Device complexity
If alignment holes of same width are formed in substrate and mask, then alignment is simplified, but optical sensors cannot accurately detect the boundary between substrate and mask
Solution Approach 1:
By creating treatment regions with different reflectance, the patent introduces visual contrast that enables optical sensors to distinguish between substrate and mask areas. This allows the use of simple alignment hole structures while achieving accurate optical detection, thus maintaining low device complexity while improving measurement precision
Solution Approach 2:
The patent applies local quality by creating treatment regions with specific reflectance properties only in localized areas around the alignment holes, rather than changing the entire substrate or mask. This localized modification provides sufficient optical contrast for accurate detection while keeping the overall structure simple and maintaining procedural simplicity
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 approach enables effective and accurate alignment of opaque substrates with masks by creating distinct reflectance differences, facilitating proper visual identification and alignment, even in cases where optical sensors may struggle with similar reflectance.
Implementation Method 1
modifying a surface reflectance around either the first alignment hole or the second alignment hole to form a treatment region
Data Source
AI summary
A method of aligning a substrate includes forming a first alignment hole in the substrate, preparing a mask with a second alignment hole narrower than the first alignment hole, modifying a surface reflectance around either the first alignment hole or the second alignment hole to form a treatment region, positioning the mask below the substrate, such that the first and second alignment holes overlap, and operating a sensor unit above the first alignment hole to examine alignment of the first and second alignment holes.