Copper-Wired Oxide TFT Structure for Low-Resistance Display Circuits
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Solution Overview
Problem
Existing semiconductor devices face issues with high wiring resistance, signal delay, voltage drop, and impurity ingress leading to transistor defects and increased power consumption, especially in large-sized display devices with high-definition screens.
Innovation Solution
A semiconductor device design using copper for low-resistance wiring connected to a highly purified oxide semiconductor with a wide band gap, sealed by insulating films, and a manufacturing process involving specific heat treatments to enhance stability and reduce off-current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional wiring materials are used, then manufacturing is simpler, but wiring resistance is high causing signal delay and voltage drop
Solution Approach 1:
The patent changes the material parameter of wiring from conventional materials to copper, achieving low wiring resistance and high conductivity. This resolves the contradiction by prioritizing electrical performance parameters over manufacturing simplicity, as copper's superior conductivity directly addresses signal delay and voltage drop issues in large-sized display devices.
2Reliability
If oxide semiconductor is used without purification, then manufacturing is easier, but impurity ingress causes transistor defects and increased off-current
Solution Approach 1:
The patent applies preliminary purification treatment to the oxide semiconductor layer before transistor fabrication. By removing impurities in advance through specific heat treatments and atmospheric control during manufacturing, the patent prevents future transistor defects and off-current issues, resolving the contradiction between reliability and device complexity.
Solution Approach 2:
The patent uses an inert atmosphere (nitrogen or rare gas) during oxide semiconductor formation and heat treatment to prevent impurity ingress. This creates a controlled environment that protects the semiconductor material from contamination, achieving high transistor stability without requiring overly complex purification processes.
3Reliability
If standard heat treatment is applied, then manufacturing is simpler, but off-current remains high and transistor characteristics are unstable
Solution Approach 1:
The patent optimizes heat treatment parameters including temperature (400-700°C), atmosphere (oxygen or inert gas), and duration to achieve stable transistor characteristics and low off-current. By precisely controlling these parameters, the patent resolves the contradiction between reliability and manufacturing simplicity, as the optimized heat treatment process becomes a standardized step rather than a complex procedure.
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 design achieves reduced wiring resistance, stable transistor operation, high on-current to off-current ratio, and lower power consumption, preventing defects and ensuring high display quality and reliability.
Implementation Method 1
heating the substrate over which the oxide semiconductor layer is provided in a nitrogen atmosphere to a temperature equal to or higher than 350° C. and equal to or lower than 700° C.
Implementation Method 2
cooling the substrate over which the oxide semiconductor layer is provided in a dry air containing oxygen after the heating
Data Source
AI summary
Disclosed is a semiconductor device comprising a thin film transistor and wirings connected to the thin film transistor, in which the thin film transistor has a channel formation region in an oxide semiconductor layer, and a copper metal is used for at least one of a gate electrode, a source electrode, a drain electrode, a gate wiring, a source wiring, and a drain wiring. The extremely low off current of the transistor with the oxide semiconductor layer contributes to reduction in power consumption of the semiconductor device. Additionally, the use of the copper metal allows the combination of the semiconductor device with a display element to provide a display device with high display quality and negligible defects, which results from the low electrical resistance of the wirings and electrodes formed with the copper metal.