Wafer-Bonded Image Sensor Stacking for Pixel Density and Dynamic Range
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Solution Overview
Problem
Current image sensor technologies face challenges in achieving high dynamic range and efficient light capture due to the integration of photodetectors and sensing circuitry, leading to limitations in pixel size, light sensitivity, and image quality, especially in scenes with both bright and dark areas.
Innovation Solution
The use of layer transfer technology to monolithically stack photodetectors and read-out circuits, allowing for parallel data collection and the integration of multiple image sensor arrays with distinct distances from the lens, enabling improved light sensitivity and dynamic range through the combination of small and large light-sensitive areas and the use of isolation layers and conducting vias.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If photodetectors and sensing circuitry are integrated on the same chip, then device complexity is reduced, but pixel size and light sensitivity deteriorate due to area consumption by sensing circuits
Solution Approach 1:
The patent transitions from planar integration to three-dimensional stacking, placing photodetectors and sensing circuitry on separate chips in vertical layers. This dimensional change allows both components to occupy full pixel areas without lateral interference, resolving the contradiction between integration and pixel size.
Solution Approach 2:
The integrated sensor is divided into separate functional modules: photodetector layer and sensing circuitry layer, fabricated on different chips then stacked. This segmentation allows each component to be optimized independently for its specific function while maintaining overall system integration.
2Device complexity
If photodetectors and sensing circuitry are integrated on the same chip, then device complexity is reduced, but light sensitivity deteriorates due to area consumption by sensing circuits
Solution Approach 1:
By stacking photodetectors and sensing circuitry in vertical layers rather than placing them side-by-side in the same plane, the invention maximizes the light-sensitive area of each pixel. The photodetector layer captures light without obstruction from circuit elements, directly improving light sensitivity.
3Adaptability or versatility
If multiple image sensor arrays with distinct distances from the lens are integrated, then dynamic range is improved, but device complexity increases
Solution Approach 1:
Multiple image sensor arrays with different focal distances are combined into a single stacked sensor module. The first and second image sensor arrays are positioned at different distances from the lens, enabling simultaneous capture of objects at various depths and expanding dynamic range while maintaining a compact integrated structure.
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 enhances image sensor performance by allowing simultaneous capture of both bright and dark areas without loss of detail, improving pixel density and dynamic range, and enabling more efficient data processing and storage.
Implementation Method 1
a first image sensor array and a second image sensor array... allowing simultaneous capture of both bright and dark areas
Implementation Method 2
wherein the first image sensor array is bonded to the second image sensor array, and wherein the bonded comprises an oxide to oxide bond
Data Source
AI summary
An integrated device, the device including: a first level including a first mono-crystal layer, the first mono-crystal layer including a plurality of single crystal transistors; an overlying oxide disposed on top of the first level; a second level including a second mono-crystal layer, the second level overlaying the oxide, where the second mono-crystal layer includes a plurality of image sensors, where the second level is bonded to the first level, where the bonded includes an oxide to oxide bond; and a plurality of pixel control circuits, where each of the plurality of image sensors is directly connected to at least one of the plurality of pixel control circuits, and where the integrated device includes a plurality of memory circuits.