Floating Diffusion Island Shallow Trench Isolation for High Voltage Transistors
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Solution Overview
Problem
High voltage and high power transistor devices face challenges in achieving high breakdown voltage and low turn-on-resistance due to limitations in existing semiconductor technologies.
Innovation Solution
A transistor device with a shallow trench isolation structure incorporating a floating diffusion island, where the electric type of the floating diffusion island can be different from or the same as the drain, is used to enhance breakdown voltage and reduce turn-on-resistance, along with a manufacturing method that forms the floating diffusion islands within the shallow trench isolation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional shallow trench isolation structure is used, then manufacturing process is simple, but breakdown voltage is low and turn-on-resistance is high
Solution Approach 1:
The patent embeds floating diffusion islands within the shallow trench isolation structure, creating a nested configuration where the isolation structure contains additional functional elements. This nesting approach increases breakdown voltage by utilizing the floating diffusion islands to extend the depletion region, while the islands are formed using standard photolithography and doping processes that integrate into existing manufacturing workflows
Solution Approach 2:
The shallow trench isolation structure serves multiple functions: it provides electrical isolation between devices, acts as a mechanical support structure, and contains floating diffusion islands that contribute to breakdown voltage enhancement. The floating diffusion islands are formed using the same doping processes as other device regions, making the structure multi-functional without requiring entirely separate manufacturing steps
2Object-affected harmful factors
If conventional shallow trench isolation structure is used, then manufacturing process is simple, but turn-on-resistance is high
Solution Approach 1:
The floating diffusion islands are nested within the shallow trench isolation, creating additional conductive paths that reduce turn-on-resistance. The islands are positioned to provide low-resistance connections while maintaining the isolation function, and are formed through integrated doping steps that add functionality without requiring separate manufacturing cycles
Solution Approach 2:
The floating diffusion islands act as intermediary conductive elements between the source/drain regions and the substrate, providing additional current paths that reduce turn-on-resistance. These islands mediate the electrical connection by offering low-resistance shunt paths while the shallow trench isolation maintains its primary isolation function
Data Source
AI summary
A transistor device and a manufacturing method thereof are provided. The transistor device includes a substrate, a first well, a second well, a shallow trench isolation (STI), a source, a drain and a gate. The first well is disposed in the substrate. The second well is disposed in the substrate. The STI is disposed in the second well. The STI has at least one floating diffusion island. The source is disposed in the first well. The drain is disposed in the second well. The electric type of the floating diffusion island is different from or the same with that of the drain. The gate is disposed above the first well and the second well, and partially overlaps the first well and the second well.