Wide Contact Isolation Structure for Image Sensor Crosstalk Reduction
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Solution Overview
Problem
As semiconductor devices scale down, existing manufacturing processes are inadequate in isolating adjacent light sensing regions effectively, leading to issues like cross-talk and blooming, and require additional conductive features that compromise the sensing area and increase capacitance.
Innovation Solution
The formation of an isolation structure in a semiconductor substrate with a wide contact that electrically connects source/drain structures adjacent to it, reducing the need for additional conductive features and allowing for improved isolation and increased sensing area.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If additional conductive features are added to connect source/drain structures, then electrical connection is achieved, but sensing area is reduced and capacitance increases
Solution Approach 1:
The patent merges the isolation structure with the electrical connection function by forming a wide contact that spans across the isolation structure. This single integrated structure replaces what would traditionally require separate conductive features, thereby achieving electrical connection while preserving sensing area and minimizing capacitance.
2Object-affected harmful factors
If isolation structure is made wider to prevent cross-talk, then isolation performance improves, but sensing area is reduced
Solution Approach 1:
The patent combines the isolation function with the electrical connection function in a single wide contact structure. This structure provides sufficient width to prevent cross-talk between adjacent light sensing regions while the contact's conductive nature ensures it serves dual purposes: isolation and electrical connection.
3Reliability
If complex manufacturing processes are implemented to achieve wide contact, then isolation and connection are improved, but device complexity increases
Solution Approach 1:
The wide contact structure serves multiple functions simultaneously: it provides electrical connection between source/drain structures, acts as an isolation structure to prevent cross-talk, and maintains sensing area. This multi-functionality is achieved through a single manufacturing process, avoiding the need for complex additional steps.
Data Source
AI summary
Methods for forming image sensor structures are provided. The method includes forming an isolation structure in a substrate and forming a first light sensing region and a second light sensing region. The method further includes forming a first gate structure and a second gate structure, and the first gate structure and the second gate structure are positioned at a front side of the substrate. The method further includes forming a first source/drain structure adjacent to the first gate structure and a second source/drain structure adjacent to the second gate structure and forming an interlayer dielectric layer over the front side of the substrate. The method further includes forming a contact trench through the interlayer dielectric layer and forming a contact in the contact trench.