Optical Sensor Package with Recessed Cavity for Compact Integration
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Solution Overview
Problem
Conventional optical sensor packages have a wide footprint or thick profile due to the side-by-side configuration of light-emitting and light-receiving devices, which limits their integration and application in compact electronic devices.
Innovation Solution
A system-in-package (SiP) design featuring an image sensor die with a recessed cavity housing a light-emitting device, where the image sensor die is made of silicon and includes a light transmissive layer to allow infrared light to pass through, and a cap with transparent regions for light emission and reception, reducing the overall package size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If light-emitting device and light-receiving device are arranged side-by-side, then optical signal processing capability is maintained, but footprint area increases
Solution Approach 1:
The light-emitting device is positioned within a cavity formed in the image sensor die, nesting one component inside another. This vertical integration allows the light-emitting device and light-receiving device to occupy the same lateral footprint while maintaining separate optical paths, thus reducing the overall footprint area without sacrificing optical signal processing capability
Solution Approach 2:
The design transitions from a two-dimensional side-by-side arrangement to a three-dimensional configuration by forming a cavity in the image sensor die. This allows the light-emitting device to be positioned below the light-receiving surface, utilizing the vertical dimension to reduce lateral footprint while maintaining functional separation
2Area of moving object
If light-emitting device and light-receiving device are stacked in chip-on-chip configuration, then footprint area is reduced, but package thickness increases
Solution Approach 1:
The light-emitting device is directly integrated into the image sensor die structure by forming a cavity within the die itself, rather than stacking separate chips. This merging of the light-emitting device into the die substrate reduces the overall package thickness compared to traditional chip-on-chip configurations while maintaining the reduced footprint area
3Area of moving object
If cavity is formed in image sensor die to house light-emitting device, then footprint and profile are reduced, but manufacturing complexity increases
Solution Approach 1:
The cavity formation process is divided into discrete manufacturing steps including patterning and etching operations that can be integrated into existing semiconductor fabrication processes. This segmentation of the cavity formation into standard fabrication steps reduces overall manufacturing complexity while achieving the compact footprint and profile
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 design reduces the footprint and profile of optical sensor packages, enabling more compact and efficient integration in electronic devices while maintaining optical signal processing capabilities.
Implementation Method 1
The silicon of the image sensor die is suitably transparent to allow light, such as infrared (IR) light, emitted from the light-emitting device to pass therethrough
Implementation Method 2
The photodiode receives the reflected radiation and generates an electrical signal indicative of the received radiation
Data Source
AI summary
One or more embodiments are directed to system in package (SiP) for optical devices, including proximity sensor packaging. One embodiment is directed to optical sensor that includes a substrate, an image sensor die and a light-emitting device. A first surface of the image sensor die is coupled to the substrate, and a recess is formed extending into the image sensor die from the first surface toward a second surface of the image sensor die. A light transmissive layer is formed in the image sensor die between the recess and the first surface. The optical sensor further includes a light-emitting device that is coupled to the substrate and positioned within the recess formed in the image sensor die.