Multi-Substrate Bonding with Bottom-Referenced Optical Alignment
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current methods for stacking optical elements suffer from propagation of alignment errors, leading to significant deviations in optical path and disrupted imaging in complex optical systems, particularly in miniaturized devices like smartphones.
Innovation Solution
A method involving a substrate holder with precise Z-positioning and alignment marks, where each subsequent substrate is aligned with the bottom substrate rather than the previous one, minimizing error propagation through collinear alignment of optical axes and using vacuum fixations for secure positioning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If substrates are stacked by aligning each subsequent substrate to the previous one, then the bonding process is simple and sequential, but alignment errors propagate across the entire stack leading to significant deviations
Solution Approach 1:
The patent introduces a reference substrate that serves as a common mediator for aligning all substrates in the stack. Instead of sequentially aligning each substrate to the previous one, all substrates are aligned to this single reference substrate, which acts as an intermediary reference frame. This eliminates error propagation while maintaining process simplicity.
Solution Approach 2:
The reference substrate is prepared in advance with precise alignment marks before the stacking process begins. By establishing this reference framework preliminarily, subsequent substrates can be directly aligned to it without accumulating errors from sequential bonding operations.
2Adaptability or versatility
If the number of substrates in the stack is increased to create complex optical systems, then the system functionality is improved, but alignment errors accumulate and disrupt the optical path
Solution Approach 1:
The reference substrate serves as a stable intermediary reference that remains constant regardless of how many substrates are added to the stack. This allows the system to become more complex and versatile while maintaining reliable alignment, as each new substrate is independently aligned to the reference rather than to previous substrates that may have accumulated errors.
3Ease of operation
If traditional sequential alignment methods are used, then the bonding process is straightforward, but even small alignment errors have a direct impact on the optical path and imaging quality
Solution Approach 1:
The reference substrate with its precise alignment marks serves as a mediator that simplifies the alignment operation while simultaneously improving accuracy. Operators align each substrate to the reference marks rather than performing complex sequential alignments, making the process both simpler and more accurate.
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 minimizes alignment errors, enhances imaging quality, and allows for the production of highly complex optical systems with small deviations, improving the precision and reliability of miniaturized optical systems.
Implementation Method 1
using vacuum fixations for secure positioning
Data Source
Figure 1a~1b
Figure 2a~2b
Figure 2c~2d
AI summary
The invention relates to a method for bonding at least three substrates (4ο,4υ, 4, 4', 4'', 4"', 4ο') to form a substrate stack (9, 9', 9"), wherein the substrate stack (9,9',9'') has at least one lowermost substrate (4u, 4), an intermediate substrate (4o, 4') and an upper substrate (4o', 4"), comprising the following steps: aligning the intermediate substrate (4ο,4') with the lowermost substrate (4u, 4) and bonding the intermediate substrate (4o, 4') to the lowermost substrate (4u, 4); then aligning the upper substrate (4o', 4") and bonding the upper substrate (4o', 4") to the intermediate substrate (4o, 4), characterised in that the upper substrate (4o', 4") is aligned with the lowermost substrate (4u, 4).