Oxide Semiconductor Non-Linear Element for Low-Temperature Diode Fabrication
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Solution Overview
Problem
The manufacturing of diodes using silicon carbide faces challenges such as difficulty in obtaining high-quality crystals, high process temperatures, and issues with forming insulating layers due to carbon content, which hinder the achievement of high withstand voltage and small reverse saturation current.
Innovation Solution
A non-linear element with an oxide semiconductor layer, where the area of contact between the drain electrode and the oxide semiconductor layer is made larger or smaller than the area of contact between the source electrode and the oxide semiconductor layer, and the work function of electrodes is optimized to improve current vs. voltage characteristics, allowing for low-temperature processing and enhanced rectification properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If silicon carbide is used to achieve high withstand voltage and small reverse saturation current, then the diode performance is improved, but the manufacturing process temperature becomes excessively high (1500°C or higher)
Solution Approach 1:
The patent changes the semiconductor material from silicon carbide to oxide semiconductor, fundamentally altering the material parameters to enable low-temperature processing while maintaining or improving diode performance characteristics such as withstand voltage and reverse saturation current
Solution Approach 2:
The patent uses oxide semiconductor materials that can be processed at lower temperatures compared to silicon carbide, effectively replacing the high-temperature material with a more manufacturable alternative that achieves the same functional goals
2Reliability
If silicon carbide is used to achieve high withstand voltage, then the reverse saturation current is reduced, but the crystal quality becomes difficult to obtain
Solution Approach 1:
The patent changes the material system from silicon carbide crystals to oxide semiconductor films, transitioning from a crystal-growth-limited process to a film-deposition process that enables better control over material quality and reduces manufacturing difficulties
3Reliability
If silicon carbide is used to achieve high withstand voltage, then the reverse leakage current is reduced, but insulating layer formation becomes problematic due to carbon content
Solution Approach 1:
The patent changes the material composition from carbon-containing silicon carbide to oxide-based semiconductor, eliminating the carbon content that interferes with insulating layer formation and enabling straightforward multi-layer structure fabrication
Solution Approach 2:
The patent extracts or removes the problematic carbon component from the semiconductor material system, replacing it with oxide-based materials that are compatible with standard insulating layer formation processes
4Reliability
If silicon carbide is used to achieve high withstand voltage, then the reverse leakage current is reduced, but the material becomes chemically very stable and difficult to etch
Solution Approach 1:
The patent changes the chemical composition from silicon carbide to oxide semiconductor, fundamentally altering the chemical reactivity and etchability parameters to enable easier fabrication while preserving the electrical performance characteristics
Data Source
AI summary
A non-linear element (such as a diode) which includes an oxide semiconductor and has a favorable rectification property is provided. In a transistor including an oxide semiconductor in which the hydrogen concentration is 5×1019/cm3 or lower, a work function φms of a source electrode in contact with the oxide semiconductor, a work function φmd of a drain electrode in contact with the oxide semiconductor, and electron affinity χ of the oxide semiconductor satisfy φms≦χ<φmd, and an area of contact between the drain electrode and the oxide semiconductor is larger than an area of contact between the source electrode and the oxide semiconductor. By electrically connecting a gate electrode and the drain electrode in the transistor, a non-linear element having a favorable rectification property can be achieved.