EDMOSFET Trench Gate Layout for Higher Drive Current
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Solution Overview
Problem
In modern integrated circuit design, improving drive current in extended drain metal oxide semiconductor field effect transistors (EDMOSFETs) for high voltage and radio frequency applications often results in undesirable increases in area consumption and decreases in breakdown voltage, leading to trade-offs in performance, power scaling, and size scaling.
Innovation Solution
The semiconductor structure incorporates a primary gate structure and one or more discrete trench gate structures, with gate conductor materials separated by gate dielectric material, allowing for independent biasing to enhance drive current while minimizing area consumption and breakdown voltage degradation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If techniques are used to raise the drive current of extended drain MOSFETs, then drive current is improved, but area consumption increases and breakdown voltage decreases
Solution Approach 1:
The gate structure is segmented into a primary gate and one or more trench gates that are physically separated by gate dielectric material. This segmentation allows independent control of different gate regions, enabling drive current enhancement through the trench gates while the primary gate maintains breakdown voltage control, thus avoiding the need to increase device area
Solution Approach 2:
The trench gates extend vertically into the semiconductor substrate, utilizing the depth dimension rather than only lateral expansion. This vertical configuration allows the trench gates to modulate carrier flow in the drift region without increasing the lateral footprint of the device, thereby improving drive current without increasing area consumption
2Power
If techniques are used to raise the drive current of extended drain MOSFETs, then drive current is improved, but breakdown voltage decreases
Solution Approach 1:
The gate structure is segmented into a primary gate and one or more trench gates that are physically separated by gate dielectric material. This segmentation allows independent control of different gate regions, enabling drive current enhancement through the trench gates while the primary gate maintains breakdown voltage control, thus avoiding the need to increase device area
Solution Approach 2:
Gate dielectric material acts as an intermediary that physically separates the primary gate and trench gates, preventing electrical interaction while allowing independent biasing. This intermediary structure enables the trench gates to enhance drive current without compromising the breakdown voltage control function of the primary gate
3Area of stationary object
If device area is reduced for size scaling, then size scaling is improved, but drive current decreases
Solution Approach 1:
The trench gates extend vertically into the semiconductor substrate, utilizing the depth dimension rather than only lateral expansion. This vertical configuration allows the trench gates to modulate carrier flow in the drift region without increasing the lateral footprint of the device, thereby improving drive current without increasing area consumption
Data Source
AI summary
Disclosed are a semiconductor structure and method of forming the structure. The semiconductor structure includes an extended drain metal oxide semiconductor field effect transistor (EDMOSFET). The EDMOSFET includes, in the semiconductor layer, a body well, which has a source region therein, and a drain drift well, which abuts the body well and has a drain region therein. A trench gate structure is within the drain drift well positioned laterally between the body-drain drift junction and an internal shallow trench isolation (STI) region and the internal STI region is between the trench gate structure and the drain region. A primary gate structure is on the top surface of the semiconductor layer traversing the body-drain drift junction and optionally extending over the trench gate structure. Gate dielectric material physically separates gate conductor materials of the primary and trench gate structures. Optionally, the EDMOSFET includes more than one trench gate structure.