Wafer-Level Optical Sensor Packaging With Silicon Meta-Lenses
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Solution Overview
Problem
Conventional module-level packaging for optical sensors is hindered by the use of large glass lenses, which result in high z-heights, limiting the miniaturization and cost efficiency of optical sensor packages, and are not compatible with CMOS processes.
Innovation Solution
The development of a wafer-level module lens optics package using silicon meta-lenses with high refractive index contrast, replacing traditional glass lenses, and incorporating microlens arrays and module-lens structures with tunable properties, such as numerical aperture, achieved through bonding a device wafer with optical sensing pixels and a circuit wafer, and forming electrical contacts and spacer structures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If traditional glass lenses are used in module-level packaging, then optical performance is maintained, but z-height increases and CMOS compatibility is lost
Solution Approach 1:
The patent changes the material parameter from traditional glass to silicon-based meta-lenses, enabling CMOS compatibility and reducing z-height through high refractive index contrast that allows for thinner lens structures
Solution Approach 2:
The patent uses composite material structures combining silicon meta-lenses with microlens arrays and spacer structures to achieve both reduced z-height and maintained optical performance while enabling CMOS fabrication processes
2Ease of manufacture
If traditional glass lenses are used in optical sensor packages, then optical performance is maintained, but package size increases and cost efficiency decreases
Solution Approach 1:
The patent changes the lens material to silicon-based meta-lenses that can be fabricated using standard CMOS processes, significantly reducing manufacturing cost and enabling smaller package sizes through integrated wafer-level fabrication
Solution Approach 2:
The patent merges the lens fabrication with the sensor array fabrication in a single CMOS process flow, eliminating separate assembly steps and reducing overall package size while improving cost efficiency
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 approach reduces the height of the module lens, enhances IR transmission, allows for tunable optical properties, and achieves cost efficiency while being compatible with CMOS processes, resulting in smaller package sizes and improved performance.
Implementation Method 1
forming a plurality of microlens arrays over the device-wafer surface, where each microlens of the microlens arrays corresponds to a particular optical sensing pixel
Implementation Method 2
using silicon meta-lenses with high refractive index contrast, replacing traditional glass lenses
Implementation Method 3
forming through-silicon-vias (TSV) in the circuit wafer or the device wafer, and forming electrical bond pads over the through-silicon-vias
Data Source
AI summary
A method for manufacturing one or more optical sensor packages includes forming a bonded wafer by bonding (i) a device wafer comprising a plurality of optical sensing pixels and (ii) a circuit wafer comprising application-specific-integrated-circuit configured to operate the optical sensing pixels, where the bonded wafer includes a device-wafer surface and a circuit-wafer surface. The method also includes forming a plurality of microlens arrays over the device-wafer surface, where each microlens of the microlens arrays corresponds to a particular optical sensing pixel. The method also includes forming a plurality of module-lens structures over the plurality of microlens arrays, where each module-lens structure corresponds to a particular microlens array of the plurality of microlens arrays. The method also includes forming electrical contacts over the circuit-wafer surface to establish electrical connections to the plurality of optical sensing pixels and the application-specific-integrated-circuit.