Oxygen Supply Layer for Oxide Semiconductor TFT Reliability
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Solution Overview
Problem
Oxide semiconductor TFTs face issues with oxygen defects during production, leading to unwanted OFF currents and quality fluctuations due to defects in the oxide semiconductor layer or at the interface with insulating layers, which affect TFT characteristics and reliability.
Innovation Solution
Incorporating an oxygen supply layer made of materials containing water (H2O), OR groups, or OH groups, such as silicone resin or acrylic resin, to provide oxygen and reduce defects in the oxide semiconductor layer, improving TFT characteristics and reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an oxide semiconductor layer is formed in a TFT structure, then high-speed switching and low power consumption are achieved, but oxygen defects occur during production leading to unwanted OFF currents and quality fluctuations
Solution Approach 1:
An oxygen supply layer is formed beneath the gate insulating film before the oxide semiconductor layer is deposited. This layer contains oxygen in advance (through materials like silicon oxide, silicon nitride, or oxygen plasma treatment) to prevent oxygen defects during subsequent processing steps such as heating or etching, thereby eliminating unwanted OFF currents before they can occur
Solution Approach 2:
The oxygen supply layer acts as a localized oxygen reservoir that releases oxygen atoms to the oxide semiconductor layer during thermal processing. This accelerated oxygen supply ensures the semiconductor layer maintains its stoichiometry and avoids reduction defects that would otherwise create carrier generation and OFF currents
2Speed
If heat treatment is applied to the oxide semiconductor layer, then crystallization and improved mobility are achieved, but oxygen defects increase leading to deterioration of TFT characteristics
Solution Approach 1:
The oxygen supply layer is prepared in advance containing excess oxygen (through oxidation treatment or oxygen-rich materials) to compensate for oxygen loss during subsequent heat treatment steps. This preliminary oxygen reservoir ensures that even when heating occurs, the oxide semiconductor layer can maintain its oxygen content and avoid defect formation
Solution Approach 2:
The oxygen supply layer serves as a buffer or cushion against oxygen loss during thermal processing. By having this protective layer in place before heat treatment, the system is pre-cushioned against the harmful effects of oxygen deficiency, allowing heat treatment to proceed without deteriorating TFT characteristics
3Reliability
If interface defects between oxide semiconductor layer and insulating layers are reduced, then TFT reliability improves, but additional process steps and device complexity increase
Solution Approach 1:
The oxygen supply layer is designed to serve multiple functions simultaneously: it acts as an oxygen reservoir to prevent defects, serves as an additional gate insulating layer for electrical isolation, and can function as a barrier layer. This multi-functionality reduces the need for separate dedicated oxygen supply structures, thereby limiting the increase in device complexity
Solution Approach 2:
The invention modifies the parameters of existing layers (such as increasing the oxygen content in the gate insulating film through plasma treatment or selecting oxygen-rich materials like silicon nitride) rather than adding completely new complex structures. This parameter-based approach achieves interface defect reduction with minimal increase in device 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
The oxygen supply layer effectively restores defects in the oxide semiconductor layer, resulting in high-performance TFTs with stable characteristics and reduced variations, leading to improved display quality.
Implementation Method 1
an oxygen supply layer, made of a material containing water (H2O), an OR group, or an OH group... to provide oxygen and reduce defects in the oxide semiconductor layer
Data Source
AI summary
A semiconductor device according to the present invention includes: a gate electrode (62) of a thin film transistor (10) and an oxygen supply layer (64), the gate electrode (62) and the oxygen supply layer (64) being formed on a substrate (60); a gate insulating layer (66) formed on the gate electrode (62) and the oxygen supply layer (64); an oxide semiconductor layer (68) of the thin film transistor (10), the oxide semiconductor layer (68) being formed on the gate insulating layer (66); and a source electrode (70S) and a drain electrode (70d) of the thin film transistor (10), the source electrode (70S) and the drain electrode (70d) being formed on the gate insulating layer (66) and the oxide semiconductor layer (68).