SiC Trench Diode With Embedded Electrode For Leakage Control
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Solution Overview
Problem
Semiconductor power devices, such as SiC Schottky barrier diodes, face challenges in efficiently controlling current flow and reducing reverse leakage current due to limitations in existing trench structures and conductivity types.
Innovation Solution
A semiconductor device design featuring a trench structure with a second conductivity type layer inside, allowing for ohmic contacts and diverse rectifying operations by varying the bias applied between electrodes, and incorporating a high concentration layer and insulating film to manage electric fields and leakage currents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If a trench structure is formed in the semiconductor layer to define unit cells, then reverse leakage current is reduced, but current flow control efficiency deteriorates
Solution Approach 1:
The patent applies local quality by forming a second conductivity type layer selectively at the inner surface of the trench, creating a localized pn junction structure. This allows the trench region to provide reverse leakage suppression while the embedded portion provides forward current conduction, resolving the contradiction between reducing reverse leakage and maintaining current control efficiency.
Solution Approach 2:
The patent implements nesting by placing the second conductivity type layer inside the trench structure, and further embedding the first electrode's embedded portion into the trench. This nested arrangement enables the trench to serve dual functions: defining unit cell boundaries for reverse leakage reduction while housing the electrode structure for efficient current injection.
2Ease of operation
If a p type layer is formed at the inner surface of a trench in an n type drift layer, then current can be cut off by depletion layer formation, but forward voltage increases
Solution Approach 1:
The patent uses the embedded portion as an intermediary structure that bridges the anode and the p type layer. This embedded portion provides a low-resistance current path that mediates between the external circuit and the pn junction, allowing efficient current injection without requiring high forward voltage to overcome the junction barrier.
Solution Approach 2:
The patent transitions from a planar junction structure to a three-dimensional structure by embedding the electrode portion vertically into the trench. This dimensional change creates a new current path through the embedded portion that reduces the effective forward voltage required to activate the pn junction for current conduction.
3Ease of operation
If the first electrode covers the obverse surface and includes an embedded portion in the trench, then rectifying operation is simplified, but device complexity increases
Solution Approach 1:
The patent applies universality by designing the first electrode to perform multiple functions: the planar portion provides ohmic contact to the obverse surface for current collection, while the embedded portion provides electrical connection to the p type layer for rectifying operation. This multi-functional electrode structure simplifies the overall device operation despite the increased structural complexity.
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
Enables efficient current flow with low forward voltage and reduced reverse leakage current, facilitating simpler rectifying operations and improved performance in power electronics applications.
Implementation Method 1
a first electrode contacting the obverse surface layer and forming an ohmic contact with the obverse surface layer, and a second electrode contacting the reverse surface layer and forming an ohmic contact with the reverse surface layer
Implementation Method 2
A depletion layer formed from the pn junction portion spreads inside the unit cell to cut off the current flowing between the obverse surface layer and the reverse surface layer
Implementation Method 3
the embedded portion may form a Schottky junction with the exposed drift layer
Data Source
AI summary
A semiconductor device according to the present invention includes a semiconductor layer, a trench formed selectively in an obverse surface portion of the semiconductor layer and defining a unit cell of predetermined shape in the obverse surface portion, a second conductivity type layer formed to conform to a portion or an entirety of an inner surface of the trench, an obverse surface layer of a first conductivity type formed so as to be exposed from an obverse surface of the semiconductor layer in the unit cell, a reverse surface layer of the first conductivity type formed so as to be exposed from a reverse surface of the semiconductor layer, a drift layer of the first conductivity type formed between the obverse surface layer and the reverse surface layer of the semiconductor layer and being of lower concentration than the obverse surface layer and the reverse surface layer, a first electrode contacting the obverse surface layer and forming an ohmic contact with the obverse surface layer, and a second electrode contacting the reverse surface layer and forming an ohmic contact with the reverse surface layer.