Gallium Oxide Schottky Diode Trench Width Mitigation
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Solution Overview
Problem
Schottky barrier diodes using gallium oxide experience dielectric breakdown due to electric field concentration at the end portion of the anode electrode, particularly in the trenches, when high voltages are applied.
Innovation Solution
The trenches at the end portion of the Schottky barrier diode are selectively widened, increasing the curvature radius of their bottom portion, which mitigates the electric field concentration, and an insulating film covers the inner walls of the trenches to further reduce electric field intensity, potentially incorporating a field plate structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If trenches are formed to reduce leak current, then backward voltage withstand capability is improved, but electric field concentration occurs at the end portion of the anode electrode causing dielectric breakdown
Solution Approach 1:
The patent applies local quality by differentiating the trench width at the end portion from the regular trenches. Specifically, a first trench at the end portion of the anode electrode has a width different from (larger than) the second trenches positioned elsewhere, creating localized structural variation that addresses electric field concentration at the critical end region while maintaining the leak current reduction function of the regular trenches
Solution Approach 2:
The patent implements preliminary action by forming the insulating film on the inner wall of the first trench at the end portion before applying high voltage. This pre-established insulating layer prevents dielectric breakdown by mitigating electric field concentration in advance, rather than attempting to address the problem after breakdown occurs
2Ease of manufacture
If standard width trenches are used throughout, then manufacturing simplicity is maintained, but dielectric breakdown occurs at the end portion under high voltage
Solution Approach 1:
The patent modifies the uniform trench structure by making the first trench at the end portion have a different width than the second trenches. This localized structural differentiation maintains relatively simple manufacturing (all trenches can be formed in the same process) while significantly improving high voltage withstand capability by reducing electric field concentration at the critical end region
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 configuration significantly reduces the likelihood of dielectric breakdown, ensuring the Schottky barrier diode can withstand required voltages without failure, as demonstrated by simulations showing electric field strengths within safe limits for gallium oxide.
Implementation Method 1
A Schottky barrier diode is a rectifying element utilizing a Schottky barrier generated due to bonding between metal and a semiconductor
Implementation Method 2
an electric field concentrates on the end portion of the anode electrode, so that when a high voltage is applied, dielectric breakdown occurs in this portion
Data Source
AI summary
A Schottky barrier diode includes a semiconductor substrate made of gallium oxide, a drift layer made of gallium oxide and provided on the semiconductor substrate, an anode electrode brought into Schottky contact with the drift layer, and a cathode electrode brought into ohmic contact with the semiconductor substrate. The drift layer has a plurality of trenches formed in a position overlapping the anode electrode in a plan view. Among the plurality of trenches, a trench positioned at the end portion has a selectively increased width. Thus, the curvature radius of the bottom portion of the trench is increased, or an edge part constituted by the bottom portion as viewed in a cross section is divided into two parts. As a result, an electric field to be applied to the bottom portion of the trench positioned at the end portion is mitigated, making dielectric breakdown less likely to occur.