Wafer-Level Image Sensor Packaging With Integrated Light Shielding
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Solution Overview
Problem
The existing image sensor packaging methods result in high costs and larger package sizes due to the use of discrete optical and protection components, which is unfavorable for applications like mobile and medical devices.
Innovation Solution
The method involves forming on-wafer protection and optical components at the wafer level before separating the substrates into discrete dies, including the integration of an on-wafer shield structure and lens directly on the image sensor chips, which simplifies manufacturing, reduces package size, and enhances performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If discrete optical and protection components are used in image sensor packaging, then the image sensor can be protected and optical functions can be achieved, but the package size increases and manufacturing cost increases
Solution Approach 1:
The patent merges discrete optical components (lens, color filter, infrared cut filter) and protection components (cover glass, light shield) into integrated on-wafer structures. The on-wafer lens array is formed directly on the image sensor chip surface, and the on-wafer shield structure is integrated with the cover glass, eliminating the need for separate discrete components and reducing overall package size.
Solution Approach 2:
The patent transitions from three-dimensional discrete component assembly to two-dimensional on-wafer integration. Optical and protection functions are implemented in the planar wafer dimension rather than requiring vertical stacking of discrete components, thereby reducing package height and overall volume.
2Reliability
If discrete optical and protection components are used in image sensor packaging, then the image sensor can be protected and optical functions can be achieved, but the manufacturing cost increases
Solution Approach 1:
Multiple discrete components are merged into integrated on-wafer structures that can be manufactured in a single batch process. The on-wafer lens array, color filter array, and infrared cut filter are formed simultaneously on the image sensor chip, eliminating the need for multiple separate assembly steps and reducing manufacturing cost.
Solution Approach 2:
Optical and protection components are formed preliminarily on the wafer before the image sensor chips are separated. This preliminary formation allows all components to be manufactured in one batch process rather than requiring individual assembly of discrete components after chip separation, significantly reducing manufacturing complexity and cost.
3Reliability
If discrete cover glass and light shield are used, then the image sensor is protected from environmental damage and stray light, but the package height increases
Solution Approach 1:
The cover glass and light shield are merged into a single integrated on-wafer shield structure. This structure provides both environmental protection and stray light blocking functions simultaneously, eliminating the need for separate discrete components and reducing package height.
Solution Approach 2:
The protection and light shielding functions are implemented in the planar wafer dimension rather than requiring vertical extension. The on-wafer shield structure extends laterally to provide light shielding while maintaining a thin profile, thereby reducing package height compared to discrete component stacking.
Data Source
AI summary
A method for forming an image sensor package is provided. An image sensor chip is formed over a package substrate. A protection layer is formed overlying the image sensor chip. The protection layer has a planar top surface and a bottom surface lining and contacting structures under the protection layer. An opening is formed into the protection layer and spaced around a periphery of the image sensor chip. A light shielding material is filled in the opening to form an on-wafer shield structure having a sidewall directly contact the protection layer.