SiC JBS Diode Junction Barrier Optimization for Leakage Control
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Solution Overview
Problem
Schottky diodes using silicon carbide face challenges in maintaining reliability due to defects and foreign particles at the Schottky interface, leading to increased leakage current and reduced yield rates, especially when the active region area is large, which affects the reverse voltage characteristics and overall semiconductor device performance.
Innovation Solution
A semiconductor device structure with a Schottky barrier diode is designed, featuring a silicon carbide substrate with a specific arrangement of p-type semiconductor regions and a guard ring, where the density of defects and the area of the Schottky interface are optimized to satisfy the condition DEP×AS≦223, reducing the Schottky interface area and improving yield rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the active region area is increased to achieve high-current applications, then the current capacity is improved, but the leakage current in the reverse direction increases due to defects at the Schottky interface
Solution Approach 1:
The patent applies local quality by creating junction barrier regions with different impurity concentrations in specific locations. The drift layer has a first impurity concentration in regions adjacent to the Schottky interface and a second (lower) impurity concentration in other regions. This local variation in impurity concentration reduces the electric field at the Schottky interface where defects are present, thereby reducing leakage current while maintaining high current capacity in the active region.
2Reliability
If the Schottky interface area is reduced to minimize defect impact, then the leakage current is reduced, but the forward conduction capability is compromised
Solution Approach 1:
The patent changes the impurity concentration parameter in the drift layer to resolve this contradiction. By setting the first impurity concentration (near Schottky interface) higher than the second impurity concentration (in other regions), the patent achieves two effects: (1) reduced electric field and leakage current at the Schottky interface, and (2) maintained forward conduction capability through optimized impurity distribution. This parameter change allows the Schottky interface area to be sufficiently large for high current while minimizing defect impact.
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 structure enhances the reliability and yield rate of semiconductor devices by minimizing the impact of defects and foreign particles, maintaining effective reverse voltage characteristics and achieving a high yield rate even with larger active regions, essential for high-current applications.
Implementation Method 1
The Schottky diode obtains rectification by using a Schottky barrier which is generated by difference between a work function of a metal and electron affinity of a semiconductor
Implementation Method 2
The JBS diode can reduce the electric field at the Schottky interface because a depletion layer extends from the junction barrier part at the time of application of voltage in the reverse direction
Data Source
AI summary
Reliability of a semiconductor device is improved by suppressing reverse voltage deterioration at the time of reverse bias junction barrier Schottky diode using a substrate containing SiC. In a JBS diode having an active area of 0.1 cm2 or more, an area of a Schottky interface at which a drift layer and a Schottky electrode are contacted can be sufficiently reduced by relatively increasing a ratio of p-type semiconductor region being a junction barrier region in an active region, and thereby deterioration in reverse voltage caused by defects existing in the drift layer is prevented.