BSI-CIS Metal Grid Connection Through Buffer Dielectric Openings
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Solution Overview
Problem
Existing BSI-CIS fabrication processes fail to establish an electrical connection between the metal grid in the pixel region and the underlying substrate and deep trench fill structure, limiting the optimization of electrical performance.
Innovation Solution
A method is developed to electrically connect a metal grid layer to an exposed part of the substrate and/or an exposed portion of the trench fill structure by forming openings in a buffer dielectric layer and depositing the metal grid layer to fill these openings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a buffer dielectric layer is formed between the metal grid and the underlying substrate/trench fill structure, then the optical properties of the BSI-CIS are improved, but the electrical connection between the metal grid and the substrate/trench fill structure is lost
Solution Approach 1:
The buffer dielectric layer is segmented by forming openings (first openings and second openings) through it. This allows the metal grid to be electrically connected to the substrate and trench fill structure through these openings while maintaining the dielectric isolation in other areas, thus preserving both optical properties and electrical connection capability
Solution Approach 2:
The buffer dielectric layer is modified locally by forming openings only in specific regions where electrical connection is needed. The metal grid is selectively connected to the substrate and trench fill structure through these localized openings, while the rest of the buffer dielectric layer remains intact to maintain optical performance
2Stability of the object's composition
If the metal grid is physically connected to the substrate and trench fill structure through the buffer dielectric layer, then the structural integrity is maintained, but the electrical performance cannot be optimized
Solution Approach 1:
The buffer dielectric layer is segmented into regions with openings and regions without openings. This segmentation allows the metal grid to have both physical support from the buffer dielectric layer and electrical connection paths through the openings, achieving both structural integrity and optimized electrical performance
Solution Approach 2:
The openings in the buffer dielectric layer serve as intermediaries that allow electrical connection between the metal grid and the substrate/trench fill structure. The buffer dielectric layer itself acts as a mediator that provides both mechanical support and controlled electrical isolation/connection
Data Source
AI summary
A semiconductor device and a method of manufacturing the semiconductor device are disclosed. The method of manufacturing the semiconductor device includes: forming a trench fill structure in a pixel region of a substrate, where a high-k dielectric layer is sandwiched between a side wall of a fill material in the trench fill structure and the substrate; forming a plug structure in a pad region of the substrate; covering a surface of the substrate in the pixel region and the pad region with a buffer dielectric layer; etching the buffer dielectric layer to form first opening exposing at least part of the substrate around a top side wall portion of the trench fill structure and/or at least a top portion of the trench fill structure; and forming a metal grid layer on the buffer dielectric layer in the pixel region.