Coated Through-Hole Substrate for Precise Micro-Optical Alignment
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Solution Overview
Problem
In microsystem technology, particularly in micro-optical systems, alignment of wafers or substrates is challenging due to parallax errors from near-surface markings and low contrast through-hole markers, leading to misalignment of lenses and unwanted reflections, ghosting, and contrast reduction.
Innovation Solution
A structured substrate with through-holes having light-absorbing and/or light-reflecting coatings on the inner walls, designed with precise angles and dimensions, is used to enhance alignment and reduce stray light, featuring coatings that absorb or reflect specific wavelengths to improve pattern recognition and reduce disturbances.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If near-surface markings are used for alignment, then alignment marks are visible, but parallax errors occur reducing alignment precision
Solution Approach 1:
The patent moves the alignment marking from a 2D near-surface location to a 3D through-hole structure that extends through the entire substrate thickness. This dimensional transition eliminates parallax errors by providing alignment references at multiple depths, ensuring accurate alignment regardless of viewing angle.
2Measurement precision
If through-holes are used as alignment marks, then alignment references are provided, but pattern recognition is challenging due to low contrast
Solution Approach 1:
The patent applies different optical properties (light-absorbing and light-reflecting coatings) to the inner walls of through-holes to create high-contrast visual patterns. This enhances the detectability of through-holes during alignment by making them stand out clearly against the substrate background.
3Reliability
If flat spacer wafers with through-holes are used, then distances between functional layers are maintained, but stray light and reflections cause disturbances
Solution Approach 1:
The patent applies different coatings to different regions of the through-hole inner walls. Light-absorbing coatings are applied to surfaces where stray light reflection would be harmful, while light-reflecting coatings are applied where enhanced visibility or light redirection is beneficial. This localized differentiation eliminates disturbances while maintaining structural function.
4Measurement precision
If through-holes are used for alignment, then alignment marks are provided, but misalignment occurs due to low contrast markers
Solution Approach 1:
The patent enhances the optical contrast of through-holes by applying light-absorbing and light-reflecting coatings to the inner walls. This creates high-visibility alignment markers that are easily detectable by pattern recognition systems, thereby improving alignment accuracy and preventing misalignment during assembly.
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 structured substrate improves alignment accuracy, reduces stray light and reflections, and enhances contrast by optimizing the assembly of microsystems, particularly in micro-optical devices.
Implementation Method 1
the coating is light absorbing and/or light reflecting
Implementation Method 2
the coating is light absorbing and/or light reflecting
Data Source
AI summary
The invention relates to a structured substrate, preferably for applications in micro systems technology, such as for micro optical systems, comprising: a planar substrate, preferably comprising glass material, and having two opposing planar surfaces, at least one through-hole extending through the material of the planar substrate forming an inner wall surface surrounding the through-hole and connecting the two opposing planar surfaces, and a light absorbing and/or reflecting coating covering at least some areas of the inner wall surface of the through-hole. The invention further relates to method of manufacturing said structured substrate and to use of said structured substrate.