Image Sensor Cover Insulating Layer Adhesive Penetration Barrier
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In the manufacturing of image sensors, the adhesive layer often penetrates into the pixel array region during the bonding process of wafers, which can compromise the integrity and functionality of the sensor.
Innovation Solution
The implementation of a cover insulating layer with a step difference of 3 μm to 15 μm relative to the substrate surface, positioned to prevent the adhesive layer from penetrating into the pixel array region by creating a recess portion and maintaining a separation distance from the outer boundary, thereby blocking the adhesive's flow onto the pixel array region.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a light-transmissive cover is bonded to the substrate using an adhesive layer, then the structural integrity and protection of the pixel array region is improved, but the adhesive layer may penetrate into the pixel array region causing contamination and functional degradation
Solution Approach 1:
A cover insulating layer is introduced as an intermediary element between the adhesive layer and the pixel array region. This cover insulating layer serves as a barrier that prevents the adhesive from directly contacting and penetrating into the pixel array region, while still allowing the adhesive to bond the light-transmissive cover to the substrate. The cover insulating layer thus mediates between the bonding requirement and the contamination prevention requirement.
Solution Approach 2:
The bonding structure is segmented into distinct functional layers: the substrate, the cover insulating layer, the adhesive layer, and the light-transmissive cover. The cover insulating layer is specifically positioned and dimensioned to create a barrier zone that segments the adhesive flow path, preventing it from reaching the pixel array region while maintaining the overall bonding function.
2Device complexity
If the cover insulating layer is positioned close to the pixel array region, then the structural compactness is improved, but the adhesive layer may still penetrate into the pixel array region
Solution Approach 1:
The thickness and horizontal dimensions of the cover insulating layer are optimized within specific parameter ranges to achieve the desired balance. By adjusting these geometric parameters, the cover insulating layer creates an effective barrier against adhesive penetration while maintaining compact overall device dimensions. The parameter optimization ensures both compactness and reliability.
3Reliability
If the cover insulating layer is made thicker to prevent adhesive penetration, then the adhesive blocking effectiveness is improved, but the vertical space and device height increase
Solution Approach 1:
The thickness of the cover insulating layer is optimized within a specific range to provide sufficient adhesive blocking effectiveness while minimizing the increase in device height. This parameter optimization allows the cover insulating layer to be thick enough to prevent adhesive penetration but thin enough to maintain compact device dimensions.
Data Source
AI summary
An image sensor includes a first chip structure, a second chip structure disposed on the first chip structure, and in which pixels which each include a photoelectric conversion element are defined, and a light-transmissive cover bonded to an edge region of the second chip structure by an adhesive layer and having a recess portion covering a region in which the pixels are accommodated, wherein the second chip structure includes a substrate having a first surface and a second surface opposite to each other, color filters disposed on the second surface of the substrate to correspond to the pixels, a cover insulating layer covering the color filters, and accommodated in the recess portion and disposed to be horizontally spaced apart from an outer boundary of the recess portion, and microlenses disposed on the cover insulating layer to correspond to the pixels, respectively. An upper surface of the cover insulating layer is at a higher vertical level than the second surface of the substrate, and has a step difference of 3 μm to 15 μm with respect to the upper surface of the substrate.