Stacked Image Sensor with Removed Substrate for Global Shutter
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Solution Overview
Problem
Current image sensors face challenges in simplifying the manufacturing process and implementing global shutter operation and High Dynamic Range (HDR) functions while maintaining performance.
Innovation Solution
The image sensor design involves forming a pixel array, logic circuits, and storage devices in separate stacked layers, with a semiconductor substrate removed from the middle layer, allowing for simplified manufacturing and enabling global shutter operation and HDR functionality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If pixel array, logic circuit, and storage devices are formed in separate stacked layers with middle substrate removed, then global shutter operation and HDR function are enabled, but manufacturing process complexity increases
Solution Approach 1:
The image sensor is divided into three separate layers: first layer with pixel array and first logic circuit, second layer with second logic circuit, and third layer with storage devices. Each layer can be manufactured independently on separate substrates, then bonded together, enabling global shutter and HDR functions while managing manufacturing complexity through modular fabrication
Solution Approach 2:
The patent transitions from planar integration to three-dimensional stacked architecture. By stacking layers vertically and removing the substrate from the middle layer (third layer), the design achieves higher integration density and enables advanced functions (global shutter, HDR) that require separation of pixel, logic, and storage components in the vertical dimension
2Adaptability or versatility
If multiple separate layers are stacked with substrate removal, then functionality is enhanced, but manufacturing precision requirements increase
Solution Approach 1:
Alignment marks are formed on each layer before stacking, and the layers are bonded together with precise alignment to these marks. This preliminary preparation of alignment features ensures that the complex multi-layer stacking achieves the required precision for global shutter and HDR functionality without requiring ultra-precise positioning during assembly
3Ease of manufacture
If logic vias extend through third layer without penetrating semiconductor material, then manufacturing is simplified, but electrical connection reliability may be affected
Solution Approach 1:
The semiconductor substrate is removed from the third layer, and logic vias are formed to extend through the third layer without penetrating remaining semiconductor material. This extraction of the substrate allows vias to be formed more easily through the insulating layer, simplifying the manufacturing process while maintaining electrical connection reliability through proper via design and bonding
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 simplifies the manufacturing process and enhances the image sensor's ability to perform global shutter operations and provide HDR functions, improving its overall performance and functionality.
Implementation Method 1
Each of the pixels includes at least one photodiode configured to generate a charge in response to light
Data Source
AI summary
An image sensor includes a first layer including pixels in a pixel array, and a first logic circuit configured to control the pixel array. Each of the pixels include at least one photodiode configured to generate a charge in response to light, and a pixel circuit configured to generate a pixel signal corresponding to the charge. A second layer includes a second logic circuit that is connected to the pixel array and the first logic circuit and is on the first layer. A third layer includes storage elements that are electrically connected to at least one of the pixels or the first logic circuit and an insulating layer on the storage elements. A lower surface of the insulating layer is attached to an upper portion of the first layer, and an upper surface of the insulating layer is attached to a lower portion of the second layer.