Image Sensor Alignment Marks With Light-Absorbing Dummy Patterns
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Solution Overview
Problem
Existing image sensing devices face challenges in forming alignment marks freely without being limited by the positions of lower patterns, leading to potential alignment failures during the fabrication process due to optical reflections or scattering by lower patterns.
Innovation Solution
The introduction of alignment dummy patterns, including upper and lower dummy patterns in different layers of the insulation layer, which absorb laser beams used to measure light reception alignment marks, allowing these marks to be positioned freely without overlapping with lower patterns, thereby preventing alignment failures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If alignment marks are positioned freely on the upper substrate, then positioning flexibility of light reception elements is improved, but alignment failures may occur due to optical reflections or scattering by lower patterns
Solution Approach 1:
An alignment dummy pattern is introduced as an intermediary element between the lower pattern and the light reception alignment mark. This dummy pattern absorbs laser light used for alignment measurement, preventing optical reflections or scattering from the lower pattern from interfering with the alignment process. The dummy pattern acts as a mediator that blocks harmful optical paths while allowing the alignment mark to be positioned freely on the upper substrate without overlapping constraints
Solution Approach 2:
The invention converts the potentially harmful effect of optical reflections and scattering from lower patterns into a beneficial solution by placing light-absorbing dummy patterns at strategic locations. These dummy patterns intentionally absorb the laser light that would otherwise cause alignment failures, transforming the optical interference problem into a controlled absorption mechanism that ensures reliable alignment measurement
2Ease of manufacture
If alignment marks overlap with lower patterns, then manufacturing process is simplified, but optical interference occurs during alignment measurement
Solution Approach 1:
The alignment dummy pattern serves as an intermediary that absorbs laser light in the region where alignment marks might overlap with lower patterns. This allows the alignment mark to be placed freely without avoiding lower patterns, simplifying the manufacturing process. The dummy pattern mediates between the overlapping structures by absorbing the measurement laser, preventing optical interference while maintaining placement flexibility
Solution Approach 2:
The alignment dummy pattern is formed in advance during the manufacturing process, before the alignment measurement step. By pre-positioning these light-absorbing patterns in the insulation layer, the system prepares the optical environment beforehand to prevent interference during the subsequent alignment measurement, ensuring that no optical interference occurs when alignment marks are positioned freely
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 design enhances the flexibility and accuracy of alignment mark placement, reducing the likelihood of optical interference and improving the spatial alignment of light reception elements with their corresponding photoelectric conversion elements during fabrication.
Implementation Method 1
an alignment pattern disposed between the first peripheral region and the second peripheral region and in the insulation layer. The alignment pattern is configured to absorb light used to measure the light reception alignment mark
Data Source
AI summary
An image sensing device includes an upper substrate configured to include a pixel region and a first peripheral region located outside the pixel region, a lower substrate configured to include a logic region and a second peripheral region located outside the logic region, the logic region configured to generate an image based on the electrical signals from the unit pixels, light reception elements disposed over the upper substrate and configured to transmit the incident light to the pixel region, an insulation layer disposed between the upper substrate and the lower substrate, a light reception alignment mark disposed in the first peripheral region and configured to assist positioning of the light reception elements, and an alignment pattern disposed between the first peripheral region and the second peripheral region and in the insulation layer. The alignment pattern is configured to absorb light used to measure the light reception alignment mark.