Thin-Film Transistor Passivation Using Silicon Carbide Layers
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Solution Overview
Problem
Conventional transistors face reliability issues due to the failure of silicon dioxide passivation structures at high temperatures and their hydrophilic nature, which allows moisture and oxygen to diffuse into the active layer, degrading the transistor performance.
Innovation Solution
The use of oxygen-doped silicon carbide (ODC) and nitrogen-doped silicon carbide (NDC) as materials for the passivation structure, which are hydrophobic and have higher film density than silicon dioxide, effectively preventing moisture and oxygen diffusion and maintaining integrity at high temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If silicon dioxide is used as passivation material, then the process is conventional and easy to manufacture, but the passivation structure fails at high temperatures and allows moisture diffusion
Solution Approach 1:
The patent changes the material parameters by substituting silicon dioxide with silicon carbide, which has fundamentally different properties including higher thermal stability and hydrophobicity. This material parameter change resolves the contradiction by providing both high-temperature reliability and resistance to moisture diffusion while remaining compatible with conventional manufacturing processes
Solution Approach 2:
The patent employs composite passivation structures that may include multiple layers combining different materials such as silicon carbide with other dielectric materials. This composite approach allows optimization of both manufacturing ease and reliability by combining the advantages of different materials while mitigating their individual weaknesses
2Device complexity
If silicon dioxide passivation is used, then the structure is simple, but moisture and oxygen diffuse into the active layer degrading performance
Solution Approach 1:
The patent changes the chemical composition parameter from silicon dioxide to silicon carbide, which fundamentally alters the material's interaction with moisture. Silicon carbide's hydrophobic nature prevents moisture and oxygen diffusion into the active layer, directly addressing the harmful factor while maintaining structural simplicity
Solution Approach 2:
The patent uses silicon carbide which can be deposited using conventional PECVD equipment, providing a cost-effective solution that replaces the failed silicon dioxide passivation layer. The material provides long-lasting protection against environmental degradation
3Ease of manufacture
If silicon dioxide passivation is used, then the processing is conventional, but the passivation structure degrades at high temperatures
Solution Approach 1:
The patent changes the thermal stability parameter by selecting silicon carbide as the passivation material. Silicon carbide maintains its structural integrity and protective function at high temperatures where silicon dioxide would degrade, while still being processable using conventional semiconductor manufacturing equipment and techniques
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 ODC and NDC passivation structures enhance the longevity and reliability of transistors by preventing environmental damage, allowing for integration into high-temperature processing without compromising performance.
Implementation Method 1
The use of oxygen-doped silicon carbide (ODC) and nitrogen-doped silicon carbide (NDC) as materials for the passivation structure, which are hydrophobic and have higher film density than silicon dioxide, effectively preventing moisture and oxygen diffusion
Data Source
AI summary
In some embodiments, the present disclosure relates to a device. The device includes an active layer arranged over a substrate. A gate electrode is arranged on a first side of the active layer and spaced apart from the active layer by a gate dielectric layer. A passivation structure is arranged on the active layer. A source contact extends through the passivation structure to contact the active layer and a drain contact extends through the passivation structure to contact the active layer. An upper portion of the passivation structure includes silicon carbide.