Interposer Wafer Alignment for Wafer-Level Camera Packaging
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Solution Overview
Problem
The manufacturing of wafer-level cameras faces challenges due to size reduction of optics and sensors, leading to alignment and bonding issues, which complicate the packaging process and limit performance, particularly in compact devices like mobile devices.
Innovation Solution
A chip-scale packaging process that aligns optics and image sensor components with interposers using photoresist patterns to form transparent regions, allowing for precise bonding and focusing, thereby overcoming alignment and dimension mismatch issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the size of optics and sensors is reduced for compact devices, then the camera can be used in mobile devices with small form factor, but alignment and bonding issues arise that complicate the packaging process and limit performance
Solution Approach 1:
An interposer wafer is introduced as an intermediary component between the optics component and the image sensor. The interposer includes a photoresist pattern that serves as a reference for alignment during bonding processes. This intermediary structure enables precise alignment and bonding of miniaturized components while facilitating the packaging process, thereby resolving the contradiction between small camera size and manufacturing precision requirements
2Volume of moving object
If the size of optics and sensors is reduced, then compact device integration is enabled, but bonding process complexity increases
Solution Approach 1:
The photoresist pattern is formed on the interposer wafer before the bonding processes occur. This preliminary action establishes alignment references in advance, which simplifies subsequent bonding operations. By preparing the alignment structure beforehand, the packaging process complexity is reduced despite the miniaturization of components
3Manufacturing precision
If photoresist pattern is used for alignment, then precise optical alignment is achieved, but additional manufacturing steps are required
Solution Approach 1:
The photoresist pattern formation is merged with the interposer wafer fabrication process. The same photolithography equipment and processes used to create the interposer structure are utilized to form the alignment pattern, thereby combining multiple functions into a single manufacturing sequence. This approach maintains high optical alignment precision while minimizing the addition of separate manufacturing steps
Data Source
AI summary
A chip-scale packaging process for wafer-level camera manufacture includes aligning an optics component wafer with an interposer wafer having a photoresist pattern that forms a plurality of transparent regions, bonding the aligned optics component wafer to the interposer wafer, and dicing the bonded optics component wafer and interposer wafer such that each optics component with interposer has a transparent region. The process further includes dicing an image sensor wafer, aligning the pixel array of each image sensor with the transparent region of a respective optics component with interposer, and bonding each image sensor to its respective optics component with interposer. Each interposer provides alignment between its respective optics component center and its respective pixel array center of the image sensor based on the respective transparent region. The interposer further provides a back focal length for focusing light from the optics component onto a top surface of the pixel array.