Image Sensor Package Substrate Segmentation
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Solution Overview
Problem
Conventional image sensor packages have larger dimensions due to the thickness of both the chip and the carrying substrate, and the conductive layer is prone to damage during fabrication, limiting flexibility in design and fabrication.
Innovation Solution
The image sensor package is designed with a first substrate having a via hole and a driving circuit, and a second substrate with a photosensitive device, where the substrates are thinned to reduce dimensions and the conductive layer is formed on the backside of the first substrate, avoiding damage and allowing for flexible fabrication and design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the chip and carrying substrate are made with certain thicknesses to ensure structural integrity, then the mechanical strength is improved, but the overall package dimensions become larger
Solution Approach 1:
The patent divides the image sensor into separate functional components: a chip containing the driving circuit and a carrying substrate with the photosensitive device. This segmentation allows each component to be optimized independently for both strength and thinness, resolving the contradiction between structural integrity and compact dimensions.
Solution Approach 2:
The patent employs thin film structures for the chip and carrying substrate, achieving minimal thickness while maintaining structural integrity through advanced thin-film fabrication techniques. This enables the package to achieve reduced dimensions without sacrificing the mechanical strength required for reliable operation.
2Reliability
If the conductive layer is formed on the sidewalls of the substrates to provide electrical connection, then the electrical connectivity is improved, but the conductive layer becomes prone to damage during fabrication
Solution Approach 1:
The patent transitions the conductive layer from a sidewall configuration to a planar configuration on the surface of the substrates. This dimensional change eliminates the vulnerability of sidewall conductors to fabrication damage while maintaining effective electrical connectivity between components.
Solution Approach 2:
The conductive layer is formed on the surface of the substrates before final assembly, allowing it to be properly established and protected in advance. This preliminary formation ensures robust electrical connectivity without exposing the conductive layer to damage during subsequent fabrication steps.
3Device complexity
If the driving circuit and photosensitive device are integrated on the same substrate to simplify structure, then the device complexity is reduced, but the fabrication flexibility is limited
Solution Approach 1:
The patent segments the image sensor into a chip with the driving circuit and a carrying substrate with the photosensitive device. This segmentation paradoxically simplifies the overall structure while dramatically increasing fabrication flexibility, as each component can now be manufactured using optimized processes and independently scaled or modified.
Data Source
AI summary
An image sensor package and method for fabricating the same is provided. The image sensor package includes a first substrate comprising a via hole therein, a driving circuit and a first conductive pad thereon. A second substrate comprising a photosensitive device and a second conductive pad thereon is bonded to the first substrate, so that the driving circuit, formed on the first substrate, can electrically connect to and further control the photosensitive device, formed on the second substrate. A solder ball is formed on a backside of the first substrate and electrically connects to the via hole for transmitting a signal from the driving circuit. Because the photosensitive device and the driving circuit are fabricated individually on the different substrates, fabrication and design thereof is more flexible. Moreover, the image sensor package is relatively less thick, thus, the dimensions thereof are reduced.