Image Sensor Device With Segmented Light-Blocking Isolation
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Solution Overview
Problem
The challenge in forming reliable image sensor devices at smaller sizes due to the increasing complexity and difficulty of fabrication processes as feature sizes decrease, affecting the performance and reliability of image sensor devices.
Innovation Solution
The process involves forming a substrate with a light-receiving region and a device region, using isolation structures and light-blocking layers to prevent incident light from affecting the device region, and employing specific materials and structures like high-k gate dielectric layers and metal gate electrodes to enhance the performance of transistors and light-sensing structures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If feature sizes are reduced to increase functional density, then the number of interconnected devices per chip area increases, but fabrication processes become more difficult and reliability decreases
Solution Approach 1:
The substrate is divided into distinct light-receiving region and device region with isolation structures, separating photodetector functions from transistor circuits. This segmentation allows each region to be optimized independently for its specific function while maintaining overall device reliability despite reduced feature sizes
Solution Approach 2:
Isolation structures and light-blocking layers are introduced as intermediary elements between the light-receiving region and device region. These intermediaries prevent harmful light interference from reaching transistors while allowing continued miniaturization of functional components
2Quantity of substance
If feature sizes are reduced to increase functional density, then more devices fit per chip area, but fabrication process complexity increases
Solution Approach 1:
By segmenting the substrate into distinct functional regions early in the fabrication process, the patent simplifies subsequent processing steps. Each region can be fabricated with appropriate materials and structures without requiring complex multi-step processes across the entire chip
Solution Approach 2:
Isolation structures and light-blocking layers are formed preliminarily during the fabrication process before final device assembly. This preliminary action prevents light interference issues from arising later, simplifying the overall fabrication workflow despite reduced feature sizes
3Reliability
If light-blocking structures are added to prevent light interference with device region, then device reliability improves, but device complexity increases
Solution Approach 1:
The light-blocking layer is merged with the isolation structure to form a single integrated component that performs both light blocking and electrical isolation functions. This merging reduces the number of separate structures needed, thereby reducing overall device complexity while maintaining reliability
Solution Approach 2:
The isolation structure is designed to serve multiple functions: electrical isolation between regions, mechanical support, and light blocking. This multi-functionality eliminates the need for separate dedicated light-blocking structures, reducing device complexity while improving reliability
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 improves the reliability and performance of image sensor devices by preventing light interference with the device region and optimizing transistor and light-sensing structure functionality, enabling effective light detection and image capture.
Implementation Method 1
forming a light-blocking layer over the back surface to cover a first source/drain structure formed in the semiconductor substrate
Implementation Method 2
forming an isolation structure extending from the back surface into the semiconductor substrate and surrounding the first source/drain structure
Implementation Method 3
The pixel array responds to the light by accumulating a charge. The higher the light intensity, the greater the charge that is accumulated in the pixel array
Data Source
AI summary
A method for forming an image sensor device is provided. The method includes providing a substrate. The substrate has a front surface and a back surface, and the substrate has a light-receiving region and a device region. The method includes forming a first transistor and a first source/drain structure respectively in the light-receiving region and the device region. The first transistor includes a first gate structure, a light-sensing structure, a second source/drain structure, the first gate structure is over the front surface, the light-sensing structure and the second source/drain structure are formed in the substrate and are respectively located at opposite first sides of the first gate structure, the first source/drain structure is formed in the substrate, and the first source/drain structure is electrically connected to the second source/drain structure. The method includes forming a light-blocking layer over the back surface.