Through Electrode Isolation Structure for BSI CMOS Image Sensors
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Solution Overview
Problem
Backside illumination (BSI) CMOS image sensors face issues with leakage current due to defects in the isolation structure between through electrodes, leading to reliability and yield reduction.
Innovation Solution
A semiconductor device design featuring a through electrode with a surrounding isolation structure comprising multiple patterns that prevent current leakage by dividing the area between electrodes into sub-areas, using a third pattern to connect and separate the first and second patterns, effectively acting as barrier ribs to prevent defects from forming a current leakage path.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a simple isolation structure is used between through electrodes, then the manufacturing process is simple, but leakage current occurs due to defects in the isolation structure
Solution Approach 1:
The isolation structure is divided into multiple patterns (first pattern, second pattern, third pattern) that collectively surround the through electrode. The first pattern is separated into two parts with the second pattern between them, and the third pattern connects these parts. This segmentation ensures that even if one pattern has defects, the other patterns maintain isolation, preventing leakage current while keeping each individual pattern relatively simple to manufacture.
2Reliability
If additional photomasks or process steps are added to improve isolation, then leakage current is prevented, but manufacturing cost increases
Solution Approach 1:
Multiple patterns (first, second, and third patterns) are formed using a single photomask and integrated into one continuous manufacturing process. The patterns are collectively formed in one step rather than requiring separate photomasks for each pattern, thereby improving isolation effectiveness without increasing manufacturing cost.
3Reliability
If a multi-pattern isolation structure is implemented, then current leakage paths are blocked, but the structure becomes more complex
Solution Approach 1:
The isolation structure uses different patterns positioned at different locations around the through electrode, with each pattern serving a specific local isolation function. The first pattern provides primary isolation, the second pattern fills gaps between separated portions of the first pattern, and the third pattern connects these portions. This local quality approach blocks leakage paths effectively while keeping the overall structure manageable.
Data Source
AI summary
A semiconductor device may include a first conductive pattern disposed in a first interlayer insulating film, a second conductive pattern disposed in a second interlayer insulating film positioned on the first interlayer insulating film, a through electrode partially penetrating through the first interlayer insulating film and the second interlayer insulating film. The through electrode electrically connects the first conductive pattern and the second conductive pattern. The device further includes a first pattern completely surrounding side surfaces of the through electrode, and a second pattern between the first pattern and the through electrode. The second pattern is separated from the first pattern and the through electrode. The device includes a third pattern connecting the first pattern and the second pattern.