Gallium Oxide Schottky Diode Trench Structure for Breakdown Control
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Solution Overview
Problem
Conventional Schottky barrier diodes with trenches are prone to dielectric breakdown due to electric field concentration at the outer peripheral bottom portion of the outermost peripheral trench when a backward voltage is applied.
Innovation Solution
A Schottky barrier diode design featuring a semiconductor substrate and drift layer made of gallium oxide, with a ring-shaped outer peripheral trench and center trench, where the anode electrode is embedded through an insulating film, and the insulating film thickness increases towards the outside, causing the outer peripheral wall of the anode electrode to curve vertically, thereby relaxing the electric field.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If trenches are formed in the drift layer to reduce leak current, then backward withstand voltage is improved, but electric field concentrates at the outer peripheral bottom portion causing dielectric breakdown
Solution Approach 1:
The insulating film is designed with non-uniform thickness, being thicker at the outer peripheral bottom portion of the trench where electric field concentrates. This local modification of the insulating film structure addresses the specific problem area without changing the overall trench configuration, thereby reducing electric field concentration and preventing dielectric breakdown while maintaining the leak current reduction benefit.
Solution Approach 2:
The insulating film thickness is made asymmetric with respect to the trench structure, being specifically increased at the outer peripheral bottom portion rather than uniformly throughout. This asymmetric design targets the specific location of electric field concentration, effectively relaxing the electric field in the critical area while maintaining other functional requirements.
2Reliability
If the insulating film thickness is increased at the outer peripheral bottom portion, then dielectric breakdown is prevented, but manufacturing complexity increases
Solution Approach 1:
The insulating film thickness parameter is varied spatially across the trench structure, being thicker at the outer peripheral bottom portion and thinner elsewhere. This parameter change approach allows the insulating film to provide enhanced protection where needed while maintaining manufacturability through controlled deposition processes that can achieve non-uniform thickness profiles.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This design effectively prevents dielectric breakdown by distributing the electric field, ensuring reliable pinching off of the mesa region and reducing leak current.
Implementation Method 1
an electric field concentrates on the outer peripheral bottom portion of an outermost peripheral trench upon application of a backward voltage, so that dielectric breakdown is likely to occur at this portion
Implementation Method 2
A Schottky barrier diode is a rectifying element utilizing a Schottky barrier generated due to bonding between metal and a semiconductor
Data Source
AI summary
To prevent dielectric breakdown of a Schottky barrier diode using gallium oxide. A Schottky barrier diode has a drift layer provided on a semiconductor substrate, an anode electrode, and a cathode electrode. A part of the anode electrode is embedded in an outer peripheral trench and a center trench through an insulating film. The insulating film is formed such that the thickness thereof in the depth direction of the outer peripheral trench becomes larger toward the outside, whereby an outer peripheral wall S1 of the anode electrode embedded in the outer peripheral trench is curved so as to approach vertical toward the outside. This results in relaxation of an electric field which occurs at the outer peripheral bottom portion of the outer peripheral trench upon application of a backward voltage.