SiC Trench Schottky Diode Self-Aligned Polysilicon Electrode
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Solution Overview
Problem
Existing silicon-carbide trench Schottky barrier diodes face challenges in achieving both low turn-on voltage and good reverse characteristics due to inefficient space utilization caused by alignment margins during electrode formation, leading to spatial losses and suboptimal performance.
Innovation Solution
A method involving the sequential formation of an epitaxial layer, polysilicon layer, oxide film, and photoresist film on a silicon carbide substrate, with self-aligned etching processes to form trenches and electrodes, utilizing metals like platinum, nickel, gold, and palladium to improve diode characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a trench structure is formed first and an electrode is formed subsequently, then the Schottky barrier diode can be manufactured, but an alignment margin must be provided resulting in inefficient space utilization
Solution Approach 1:
The electrode pattern is formed in advance on the substrate before the trench structure is created. This preliminary formation of the electrode allows subsequent self-aligned trench etching without requiring additional alignment margins, thereby maximizing space utilization while maintaining manufacturability
Solution Approach 2:
The process utilizes self-aligned etching where the previously formed electrode pattern serves as the alignment reference for trench formation. The electrode structure itself provides the alignment feature, eliminating the need for separate alignment margins and achieving automatic self-alignment between components
2Productivity
If a single metal such as titanium is used for the Schottky barrier, then the forward characteristic is improved, but a good reverse characteristic cannot be obtained
Solution Approach 1:
The invention employs a composite metal structure consisting of a first metal layer (such as titanium with low work function) and a second metal layer (such as nickel or platinum with high work function). This composite structure combines the advantages of both metals: the first metal provides low turn-on voltage for good forward characteristics, while the second metal provides high Schottky barrier height for excellent reverse characteristics
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
The approach results in a silicon-carbide trench Schottky barrier diode with reduced turn-on voltage and enhanced reverse characteristics by eliminating alignment margins and improving both forward and reverse diode performance through efficient space utilization and effective metal layer deposition.
Implementation Method 1
a third step of etching the polysilicon layer using the oxide film pattern as an etching mask to form a polysilicon pattern
Implementation Method 2
a fourth step of etching the epitaxial layer down to a predetermined depth using the oxide film pattern as an etching mask
Implementation Method 3
utilizing metals like platinum, nickel, gold, and palladium to improve diode characteristics
Data Source
AI summary
The present invention relates to a silicon carbide trench Schottky barrier diode using polysilicon and a method of manufacturing same. The diode has a low turn-on voltage and an improved reverse characteristic. The method includes sequentially forming an epitaxial layer, a polysilicon layer, an oxide film, and a photoresist film on a silicon carbide substrate, patterning the photoresist to form a photoresist pattern, etching the oxide film using the photoresist pattern as an etching mask to form an oxide film pattern, etching the polysilicon layer using the oxide film pattern as an etching mask to form a polysilicon pattern, removing the photoresist pattern, forming an epitaxial pattern by etching the epitaxial layer down to a predetermined depth using the oxide film pattern as an etching mask, and removing the oxide film pattern to produce a trench.