FinFET Device Shallow Trench Isolation Breakdown Voltage
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Solution Overview
Problem
High voltage lateral double-diffused metal-oxide-semiconductor (HV-LDMOS) devices face a trade-off between achieving high breakdown voltage and maintaining device density, as these parameters are conflicting.
Innovation Solution
A FinFET device with a shallow trench isolation structure between the drain and source doped layers, featuring a metal gate aligned with a well junction, which increases the breakdown voltage without reducing device density by widening the distance between the source and drain doped layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a lateral-diffused drift region with low dope concentration and large area is used to increase breakdown voltage, then the breakdown voltage is improved, but the device density decreases
Solution Approach 1:
The patent transitions from a planar LDMOS structure to a FinFET structure with vertical fins extending from the substrate. This dimensional change allows the drift region to extend vertically along the fin structure, increasing the effective breakdown voltage path without proportionally increasing the planar device area, thereby maintaining higher device density while achieving high breakdown voltage.
Solution Approach 2:
The patent implements a nested structure where the drift region is positioned between the source and drain regions within the fin structure. The well region containing the drift region is nested within the fin structure, allowing multiple functional regions to be compactly arranged in a nested configuration that maximizes space utilization and maintains high device density.
2Reliability
If the distance between source and drain doped layers is increased to raise breakdown voltage, then the breakdown voltage is improved, but the device area increases
Solution Approach 1:
The patent utilizes the vertical dimension of the FinFET structure to increase the effective distance between source and drain. The drift region extends vertically along the fin, providing a longer breakdown voltage path without increasing the horizontal device footprint, thus resolving the contradiction between breakdown voltage and device area.
Solution Approach 2:
The patent applies different doping concentrations and material properties to specific regions within the fin structure. The drift region has low dope concentration optimized for high breakdown voltage, while source and drain regions have higher doping for low resistance contacts. This localized optimization allows the device to achieve high breakdown voltage without proportionally increasing overall device area.
Data Source
AI summary
The present invention provides a FinFET device, including at least one fin structure, wherein the fin structure has a first-type well region, and a second-type well region adjacent to the first-type well region, a trench located in the fin structure and disposed between the first-type well region and the second-type well region, an insulating layer disposed in the trench, and a metal gate crossing over and disposed on the insulating layer.