Nitride Semiconductor Gate Electrode Capacity Reduction
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Solution Overview
Problem
Current nitride semiconductor devices face challenges in reducing the capacity of the gate electrode, which affects their performance and efficiency.
Innovation Solution
A nitride semiconductor device structure is designed with a nitride semiconductor layer, a first conductivity type source region, a second conductivity type well region, a trench, a first conductivity type impurity region, an insulating film, and a gate insulating film, where the insulating film is thicker than the gate insulating film, and the gate electrode is positioned from the insulating film to the gate insulating film, reducing the gate electrode's capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a conventional trench structure with gate insulating film and gate electrode is provided in the drift region, then the device structure is simplified, but the gate electrode capacity cannot be reduced sufficiently
Solution Approach 1:
The insulating film is segmented into two distinct parts: a gate insulating film on the well region and a thicker insulating film on the trench bottom surface. This segmentation allows each insulating film to serve different functions - the gate insulating film for gate control while the thicker insulating film reduces gate electrode capacity by increasing distance to the drain region.
Solution Approach 2:
Different regions of the device have different insulating film thicknesses optimized for their specific functions. The gate insulating film region maintains appropriate thickness for electrical control, while the trench bottom insulating film region has increased thickness specifically to reduce capacitance. This local quality differentiation resolves the contradiction between maintaining control functionality and reducing unwanted capacitance.
2Quantity of substance
If the insulating film thickness is increased to reduce gate electrode capacity, then the capacity is reduced, but the threshold voltage controllability may be affected
Solution Approach 1:
By segmenting the insulating film into two parts with different thicknesses, the invention maintains thin gate insulating film for good threshold voltage controllability while having a thicker insulating film in the trench region for reduced capacitance. The gate electrode remains effectively coupled to the channel through the thin gate insulating film, ensuring reliable threshold voltage control.
Solution Approach 2:
The gate insulating film acts as an intermediary that maintains the electrical coupling between gate electrode and channel, ensuring threshold voltage controllability. The thicker insulating film on the trench bottom serves as a mediator that reduces the electric field interaction between gate electrode and drain region, thereby reducing capacitance without compromising gate control functionality.
Data Source
AI summary
The nitride semiconductor device includes: a nitride semiconductor layer; a first conductivity type source region provided on a surface of the nitride semiconductor layer; a second conductivity type well region provided in the nitride semiconductor layer and adjacent to the source region in a first direction parallel to the surface and in a second direction intersecting with the first direction; a trench located on the opposite side of the source region with the well region sandwiched therebetween in the first direction; a first conductivity type impurity region located between the well region and the trench; an insulating film provided on a bottom surface of the trench; a gate insulating film provided on the well region; and a gate electrode provided from on the insulating film to on the gate insulating film. A thickness of the insulating film is larger than a thickness of the gate insulating film.