FinFET Trench Field Plate Reduces On-Resistance
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Solution Overview
Problem
Conventional FinFET devices face limitations in reducing on-resistance due to channel density and doping concentration in the drift region, which hinders the miniaturization and speed enhancement of semiconductor devices.
Innovation Solution
The FinFET device incorporates a trench field plate structure, where a trench is formed through the pad layer interface between the body and drift regions, with a gate and dielectric material, and a field plate embedded in the dielectric, allowing for reduced channel and drift region resistances through a simplified process with a reduced mask count.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional FinFET structure is used, then manufacturing process is simpler, but on-resistance cannot be reduced sufficiently
Solution Approach 1:
The field plate is embedded within the dielectric material in the trench, creating a nested structure where the field plate is contained within the dielectric, which is contained within the trench. This nested configuration reduces on-resistance by providing an additional field control mechanism without requiring separate external structures.
Solution Approach 2:
The field plate extends in the vertical dimension within the trench structure, providing field control in a third dimension beyond the conventional planar gate. This vertical extension allows for reduced on-resistance by controlling the electric field distribution through the drift region without increasing lateral device footprint.
2Reliability
If channel density and doping concentration are increased to reduce on-resistance, then device complexity increases, but this complicates the manufacturing process
Solution Approach 1:
The device structure is segmented into distinct functional regions: the conventional FinFET channel region and the trench field plate region. This segmentation allows the field plate to be formed as a separate structure with its own trench and dielectric filling process, independent of the main FinFET fabrication steps, thereby simplifying the overall manufacturing process while achieving reduced on-resistance.
3Area of moving object
If FinFET size is shrunk to improve areal density, then gate control improves, but on-resistance reduction becomes more difficult
Solution Approach 1:
The field plate acts as an intermediary structure between the gate and the drift region, providing additional field control that mediates the trade-off between device miniaturization and on-resistance. By introducing this intermediate field control element, the device achieves reduced on-resistance without requiring larger device dimensions, thus maintaining areal density improvements.
Data Source
AI summary
An integrated circuit device includes a pad layer having a body portion with a first doping type laterally adjacent to a drift region portion with a second doping type, a trench formed in the pad layer, the trench extending through an interface of the body portion and the drift region portion, a gate formed in the trench and over a top surface of the pad layer along the interface of the body portion and the drift region portion, an oxide formed in the trench on opposing sides of the gate, and a field plate embedded in the oxide on each of the opposing sides of the gate.