Image Sensor Deep Trench Isolation Alignment
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Solution Overview
Problem
The challenge in the semiconductor industry is to form reliable semiconductor devices, such as image sensor devices, at increasingly smaller sizes due to the difficulty in scaling down fabrication processes while maintaining production efficiency and reducing costs.
Innovation Solution
The process involves forming shallow and deep trench isolation structures using dielectric materials and layers, including a buffer layer, stop layer, and insulating layers, with specific deposition and etching techniques to create light-sensing regions and improve alignment accuracy, thereby enhancing the formation of image sensor devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If feature sizes continue to decrease to increase functional density, then production efficiency increases and costs decrease, but fabrication processes become more difficult and reliability decreases
Solution Approach 1:
The patent divides the isolation structure formation into two separate stages: shallow trench isolation and deep trench isolation. This segmentation allows each trench type to be optimized independently for its specific depth and alignment requirements, thereby maintaining fabrication reliability while enabling continued scaling for higher productivity.
Solution Approach 2:
The patent performs preliminary alignment marker formation and shallow trench isolation before forming the deep trench isolation. This preliminary action establishes a foundation that simplifies subsequent deep trench alignment, reducing the difficulty of fabrication processes at smaller feature sizes while maintaining reliability.
2Device complexity
If deep trench isolation structures are formed without improved alignment methods, then device complexity is reduced, but alignment accuracy between deep and shallow trenches deteriorates
Solution Approach 1:
The patent introduces alignment markers as intermediary reference features that facilitate precise alignment between shallow and deep trench isolation structures. These markers serve as mediators that enable accurate positioning without increasing the fundamental complexity of the isolation structures themselves.
Solution Approach 2:
The patent performs preliminary formation of alignment markers and shallow trench isolation structures before forming deep trenches. This preliminary action establishes reference features that guide subsequent deep trench formation, ensuring high alignment accuracy while maintaining manageable device complexity.
3Device complexity
If conventional isolation structures are used, then device complexity is minimized, but optical crosstalk between adjacent light-sensing regions increases
Solution Approach 1:
The patent segments the isolation into shallow and deep trenches, with the deep trench extending further to provide enhanced optical isolation between light-sensing regions. This segmentation effectively reduces optical crosstalk while maintaining reasonable device complexity through systematic structure division.
Solution Approach 2:
The patent addresses optical crosstalk by extending isolation structures in the depth dimension rather than merely increasing lateral dimensions. The deep trench isolation provides additional vertical separation that effectively blocks optical paths between adjacent regions without significantly increasing planar device complexity.
Data Source
AI summary
An image sensor device is provided. The image sensor device includes a substrate having a first surface, a second surface, and a light-sensing region. The image sensor device includes a first isolation structure in the substrate and adjacent to the first surface. The first isolation structure surrounds the light-sensing region. The image sensor device includes a second isolation structure passing through the first isolation structure and the substrate under the first isolation structure. The second isolation structure surrounds the light-sensing region and a portion of the first isolation structure.