Corundum Oxide Crystal Composition for Stable Ohmic Electrodes
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Solution Overview
Problem
Existing semiconductor devices using gallium oxide (Ga2O3) face challenges with electrode application, particularly with α-Ga2O3, where Ti/Au electrodes fail to provide satisfactory Ohmic properties and Schottky characteristics, leading to deterioration of electrical properties due to diffusion issues.
Innovation Solution
A crystal structure incorporating corundum structured crystalline oxides with gallium and/or indium, and a metal from Group 4 of the periodic table, such as titanium, zirconium, or hafnium, is used to enhance Ohmic characteristics and electrical properties in semiconductor elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If Ti/Au electrode is used on α-Ga2O3 semiconductor, then adhesion between electrode and semiconductor is improved, but Ohmic properties deteriorate due to Ti diffusion into semiconductor layer
Solution Approach 1:
The patent introduces an intermediary layer (Ni, Pd, or Pt) between the Ti layer and α-Ga2O3 semiconductor. This intermediary layer acts as a diffusion barrier that prevents Ti atoms from migrating into the semiconductor lattice, thereby maintaining Ohmic properties while allowing the Ti outer layer to provide good adhesion. The intermediary layer mediates between the conflicting requirements of adhesion and electrical performance.
Solution Approach 2:
The electrode is designed as a composite multi-layer structure (Ti/intermediary/Au) rather than a simple Ti/Au bilayer. This composite structure combines the advantages of each layer: Ti provides adhesion, the intermediary layer prevents diffusion, and Au provides electrical conductivity and corrosion resistance. The composite structure resolves the contradiction by distributing different functions across multiple layers.
2Reliability
If Ni layer is inserted between Ti and Au to prevent Ti diffusion, then Ohmic properties are improved, but oxygen from oxide semiconductor diffuses into Ohmic electrode causing property deterioration
Solution Approach 1:
The patent positions the Ni layer as an intermediary diffusion barrier that blocks Ti migration into the semiconductor. However, it recognizes that this same Ni layer is vulnerable to oxygen diffusion from the semiconductor. The structure accepts this trade-off while mitigating the damage through the protective Au outer layer that reduces oxygen exposure to the Ni intermediate layer.
Solution Approach 2:
The patent optimizes the thickness parameters of each layer to balance the competing diffusion processes. By controlling the thickness of the Ni intermediate layer and the protective Au layer, the design minimizes oxygen diffusion into the Ni layer while maintaining effective Ti diffusion blocking. Parameter optimization allows the system to achieve acceptable performance despite the inherent vulnerability.
3Ease of manufacture
If conventional electrodes are applied to α-Ga2O3, then manufacturing process is simplified, but electrode functionality fails (not functioning as Schottky or ohmic electrode)
Solution Approach 1:
The patent modifies the electrode structure from a simple two-layer Ti/Au configuration to a three-layer Ti/intermediary/Au configuration. This structural parameter change enables the electrode to simultaneously achieve good adhesion, prevent Ti diffusion, and maintain Ohmic properties, thereby resolving the functionality failure while remaining compatible with standard semiconductor manufacturing processes.
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 proposed crystal structure improves the electrical characteristics of semiconductor devices, providing enhanced Ohmic properties and stability, effectively addressing the issues of electrode adhesion and diffusion-related property deterioration.
Implementation Method 1
Ti is diffused into a semiconductor layer that causes a deterioration of electrical properties
Implementation Method 2
Ti/Au has a good adhesion between Ohmic electrode and the semiconductor
Data Source
AI summary
A crystal that is useful for semiconductor element and a semiconductor element that has enhanced electrical properties are provided. A crystal, including: a corundum structured crystalline oxide, the crystalline oxide including gallium and/or indium, and the crystalline oxide further including a metal of Group 4 of the periodic table. The crystal is used to make a semiconductor element, and the obtained semiconductor element is used to make a semiconductor device such as a power card. Also, the semiconductor element and the semiconductor device are used to make a semiconductor system.