Nitride-Semiconductor FET Insulating Film Recess Design
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Solution Overview
Problem
Conventional nitride-semiconductor field-effect transistors experience insufficient suppression of collapse under high voltage during switching operations, leading to unstable on-resistance and variations.
Innovation Solution
A nitride semiconductor field-effect transistor design featuring a nitride semiconductor laminate with a recessed surface, a source electrode, a drain electrode partially in the recess, a gate electrode, and insulating films with specific separation distances and compositions to reduce electric field strength and stabilize on-resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a conventional nitride-semiconductor field-effect transistor structure is used with a drain electrode formed over the nitride semiconductor laminate, then the ON withstand voltage is improved by reducing electric field strength at the drain electrode end, but collapse suppression under high voltage during switching operation is insufficient
Solution Approach 1:
An insulating film is introduced as an intermediary layer between the drain electrode and the nitride semiconductor laminate. This insulating film mediates the electric field distribution, reducing the maximum electric field strength at the drain electrode end while providing additional protection against collapse under high voltage switching operations.
Solution Approach 2:
The drain electrode is extended in the vertical dimension by forming it to overlap the nitride semiconductor laminate in the thickness direction. This three-dimensional configuration allows the drain electrode to contact the nitride semiconductor laminate through the insulating film, distributing the electric field over a larger volume and improving both ON withstand voltage and collapse suppression.
2Reliability
If the drain electrode is formed to contact the nitride semiconductor laminate through an insulating film, then collapse under high voltage is suppressed, but on-resistance becomes unstable and shows variation
Solution Approach 1:
The distance between the drain electrode end and the opening edge of the recess is controlled within a specific range (0.1 μm or more and 1.5 μm or less). By optimizing this parameter, the patent achieves a balance between collapse suppression and on-resistance stability, ensuring reliable operation without excessive variation.
Data Source
AI summary
In a nitride-semiconductor field-effect transistor, an end on a recess side of a first insulating film is separated by a distance from an opening edge of the recess and an end on a recess side of a second insulating film is separated by a distance from the end on the recess side of the first insulating film. A part of a drain electrode out of the recess stretches toward a gate electrode side in an eaves shape, is formed over surfaces of the nitride semiconductor laminate, the first insulating film, and the second insulating film from the recess, and contacts the surfaces of the nitride semiconductor laminate, the first insulating film, and the second insulating film.