Deep Trench Isolation Through Field Oxide Without STI
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Solution Overview
Problem
Deep trench isolation (DTI) in semiconductor fabrication often requires additional processing steps and increased complexity due to the need for shallow trench isolation (STI) structures, which adds manufacturing cost and complexity, especially when STI structures are not necessary.
Innovation Solution
A semiconductor device and method that incorporates a deep trench isolation structure formed through field oxide without STI structures, using a trench that extends through the semiconductor surface layer and into the substrate, filled with polysilicon and a dielectric liner, which facilitates electrical isolation between components or circuits without the need for an additional STI mask or processing steps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If deep trench isolation is combined with shallow trench isolation loop during fabrication, then electrical isolation between adjacent semiconductor device components is improved, but manufacturing cost and device complexity increase due to additional STI mask and processing steps
Solution Approach 1:
The patent extracts and removes the unnecessary shallow trench isolation (STI) loop from the deep trench isolation (DTI) fabrication process. By eliminating the STI mask and associated processing steps while maintaining the DTI structure, the invention achieves electrical isolation without the added complexity and cost of the STI loop, directly resolving the contradiction between isolation effectiveness and manufacturing simplicity
Solution Approach 2:
The patent makes the deep trench isolation structure universally applicable for electrical isolation without requiring the additional shallow trench isolation loop. The DTI structure itself is enhanced to provide sufficient lateral device isolation, making the process universally applicable to circuit designs that do not require STI structures elsewhere, thereby reducing overall manufacturing complexity while maintaining isolation reliability
2Reliability
If deep trench isolation is combined with shallow trench isolation loop during fabrication, then electrical isolation between adjacent semiconductor device components is improved, but manufacturing cost increases due to additional STI mask and processing steps
Solution Approach 1:
The patent extracts and removes the unnecessary shallow trench isolation (STI) loop from the deep trench isolation (DTI) fabrication process. By eliminating the STI mask and associated processing steps while maintaining the DTI structure, the invention achieves electrical isolation without the added complexity and cost of the STI loop, directly resolving the contradiction between isolation effectiveness and manufacturing simplicity
Solution Approach 2:
The patent discards the redundant STI loop components (mask and processing steps) that do not contribute to the essential electrical isolation function. By eliminating these unnecessary elements while preserving the core DTI isolation mechanism, the invention reduces manufacturing cost without compromising isolation reliability
Data Source
AI summary
An electronic device comprises a semiconductor substrate including majority carrier dopants of a first conductivity type, a semiconductor surface layer including majority carrier dopants of a second conductivity type, field oxide that extends on the semiconductor surface layer, and an isolation structure. The isolation structure includes a trench that extends through the semiconductor surface layer and into one of the semiconductor substrate and a buried layer of the semiconductor substrate, and polysilicon including majority carrier dopants of the second conductivity type, the polysilicon fills the trench to a side of the semiconductor surface layer.