Stacked 2D and Depth Sensor Layout for Pixel Alignment
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Solution Overview
Problem
Existing image acquisition devices struggle to capture both a 2D image and a depth image without misalignment and bulkiness, as separate sensors or integrated pixels with different dimensions and power supply voltages complicate integration.
Innovation Solution
A device comprising a first sensor with 2D image pixels and transmissive windows on a semiconductor substrate, stacked with a second sensor containing depth pixels, where amorphous silicon regions and dielectric materials ensure alignment and power insulation, and an antireflection stack enhances light transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If separate image sensors are used to capture 2D image and depth image, then both images can be captured simultaneously, but the sensors will have different viewpoints resulting in misalignment between corresponding pixels
Solution Approach 1:
The patent combines 2D image pixels and depth pixels into a single integrated sensor array where both types of pixels share the same substrate and optical path. This merging ensures that both pixel types have identical viewpoints and optical centers, eliminating misalignment issues while maintaining the ability to capture both 2D and depth images simultaneously
2Manufacturing precision
If depth pixels and 2D image pixels are integrated in the same detector array, then alignment is improved, but depth pixels require significantly larger dimensions and higher power supply voltages which complicates integration
Solution Approach 1:
The patent applies local quality by providing different structural configurations for different pixel types within the same array. Depth pixels are equipped with larger dimensions and higher voltage power supply structures where needed, while 2D image pixels use standard configurations. This localized differentiation allows each pixel type to have its required properties without imposing complexity on the entire sensor array
Solution Approach 2:
The sensor array is segmented into distinct regions with different structural characteristics. Depth pixel regions have larger dimensions and dedicated high-voltage power supply structures, while 2D image pixel regions use standard low-voltage configurations. This segmentation allows independent optimization of each pixel type without compromising the other
3Measurement precision
If depth pixels have larger dimensions than 2D image pixels, then depth detection capability is improved, but the device bulk increases
Solution Approach 1:
The patent transitions from a planar arrangement to a three-dimensional stacked architecture. Depth pixels with larger dimensions are positioned in a different spatial layer or region within the sensor array, allowing them to achieve required detection capability while the overall device footprint remains compact through vertical integration and efficient space utilization
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
The solution allows for aligned 2D and depth image capture with reduced bulk and cost, maintaining high resolution and minimizing parasitic light activation of depth pixels, while enabling separate control and power supply for each sensor type.
Implementation Method 1
the amorphous silicon region is laterally delimited, all over its periphery and along its entire height, by a dielectric material having a refraction index smaller than that of amorphous silicon
Implementation Method 2
an alternation of dielectric layers having distinct refraction indices, forming an antireflection stack for light rays crossing said transmissive window towards said depth pixel
Implementation Method 3
By the time-of-flight calculation of the light signal, the distance between the acquisition device and objects in the scene can be estimated
Implementation Method 4
the first sensor comprising a plurality of 2D image pixels
Data Source
AI summary
A device of acquisition of a 2D image and of a depth image, including: first sensor formed inside and on top of a first semiconductor substrate including a front surface and a rear surface, the first sensor including a plurality of 2D image pixels and a plurality of transmissive windows, each transmissive window including a portion of the first substrate and an amorphous silicon region in contact with the rear surface of said portion of the first substrate; and against the first sensor on the rear surface side of the first substrate, a second sensor formed inside and on top of a second semiconductor substrate and including a plurality of depth pixels arranged opposite the transmissive windows of the first sensor.