TFT Substrate Barrier Layer Design for Oxide Diffusion Control
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Solution Overview
Problem
Current thin film transistor (TFT) substrates face challenges in reducing mutual diffusion and contact resistance between oxide active layer patterns and data wiring, which affects the electrical properties and reliability of liquid crystal displays.
Innovation Solution
A TFT substrate design that includes gate wiring, oxide active layer patterns, and barrier layer patterns, where the data wiring is formed with a single layered structure comprising a low resistivity metal and a third substance oxide, and the barrier layers cover the top, bottom, and lateral surfaces of the data wiring to prevent mutual diffusion and reduce contact resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If data wiring is formed with low resistivity metal to reduce resistance, then electrical conductivity is improved, but mutual diffusion between oxide active layer and data wiring increases causing reliability degradation
Solution Approach 1:
A barrier layer comprising TiN is introduced between the oxide active layer pattern and the data wiring. This intermediary layer prevents mutual diffusion between the oxide active layer and data wiring while maintaining low contact resistance, thereby resolving the contradiction between improving electrical conductivity and preventing harmful diffusion.
Solution Approach 2:
The data wiring is constructed as a composite structure with multiple layers including Cu, TiN, and Mo. This composite material approach allows the Cu layer to provide low resistivity for electrical conductivity while the TiN and Mo layers prevent mutual diffusion, simultaneously achieving both improved conductivity and enhanced reliability.
2Object-generated harmful factors
If barrier layer is introduced to prevent mutual diffusion, then reliability is improved, but contact resistance increases
Solution Approach 1:
The barrier layer uses TiN as an intermediary material that provides both diffusion prevention and low contact resistance properties. TiN serves as an effective mediator that blocks mutual diffusion between oxide and metal while maintaining good electrical contact, thus improving reliability without significantly increasing contact resistance.
Solution Approach 2:
The barrier layer parameters are optimized with a thickness of 50-200 nm and specific material composition (TiN). By adjusting these parameters, the layer achieves the optimal balance between preventing mutual diffusion and maintaining low contact resistance, thereby improving overall device reliability.
3Device complexity
If data wiring uses single layered structure for simplicity, then manufacturing complexity is reduced, but resistance between oxide active layer and data wiring increases
Solution Approach 1:
The data wiring employs a composite multi-layer structure consisting of Cu, TiN, and Mo layers. This composite structure achieves low resistance and improved electrical properties by combining materials with complementary characteristics, while the systematic fabrication process keeps manufacturing complexity manageable.
Solution Approach 2:
The barrier layer (TiN) is formed preliminarily before the data wiring metal layers are deposited. This preliminary action of creating the diffusion barrier first ensures that subsequent metal deposition does not cause mutual diffusion, while the established process sequence maintains manufacturing simplicity despite the multi-layer structure.
Data Source
AI summary
A thin film transistor (TFT) substrate and a method of fabricating the same are provided. The thin film transistor substrate may have low resistance characteristics and may have reduced mutual diffusion and contact resistance between an active layer pattern and data wiring. The thin film transistor substrate may include gate wiring formed on an insulating substrate. Oxide active layer patterns may be formed on the gate wiring and may include a first substance. Data wiring may be formed on the oxide active layer patterns to cross the gate wiring and may include a second substance. Barrier layer patterns may be disposed between the oxide active layer patterns and the data wiring and may include a third substance.