Oxide Semiconductor TFT With Copper Wiring and Impurity Barrier Layers
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Solution Overview
Problem
Semiconductor devices face issues with increased wiring resistance, signal delay, and impurity ingress leading to transistor performance degradation, especially in large-sized displays with high-definition requirements, necessitating improved transistor design and materials to enhance on-off current ratio, stability, and reduced power consumption.
Innovation Solution
A semiconductor device design incorporating copper wiring with a highly purified oxide semiconductor having a wide band gap and reduced carrier concentration, sealed by insulating films, and using conductive layers with copper and silicon nitride to reduce resistance and impurity ingress, ensuring stable operation and high on-off current ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If copper wiring is used to reduce wiring resistance, then wiring resistance is reduced, but impurity ingress and transistor performance degradation occur
Solution Approach 1:
A barrier film is introduced as an intermediary layer between the copper wiring and the oxide semiconductor layer. This barrier film prevents impurity ingress from the copper wiring into the transistor while maintaining the low resistance benefits of copper wiring. The barrier film acts as a mediator that allows electrical connection while blocking harmful impurity diffusion.
Solution Approach 2:
The patent employs a composite structure combining copper wiring with a barrier film material. This composite approach allows the system to achieve both low resistance (from copper) and impurity blocking (from the barrier film), resolving the contradiction between electrical performance and contamination prevention.
2Reliability
If oxide semiconductor is highly purified to reduce carrier concentration, then on-off current ratio is enhanced, but manufacturing complexity increases
Solution Approach 1:
The patent achieves high purification by controlling formation conditions parameters such as oxygen partial pressure, temperature, and atmosphere during oxide semiconductor layer formation. By optimizing these parameters, the oxide semiconductor is formed in a highly oxidizing atmosphere that inherently produces low carrier concentration and high purity, avoiding complex post-formation purification steps.
Solution Approach 2:
The purification process is performed preliminarily during the formation of the oxide semiconductor layer itself, rather than as a separate subsequent step. The oxide semiconductor is formed with low carrier concentration from the beginning by controlling the deposition conditions, eliminating the need for additional purification operations.
3Manufacturing precision
If transistor size is increased for high-definition displays, then display quality is improved, but wiring resistance and signal delay increase
Solution Approach 1:
The patent changes the material parameter from conventional semiconductor to oxide semiconductor, which has fundamentally different electrical properties including higher carrier mobility. This parameter change allows for larger transistor sizes needed for high-definition displays while maintaining low resistance and fast signal response, preventing signal delay even as device dimensions increase.
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 solution provides a semiconductor device with reduced wiring resistance, enhanced on-off current ratio, improved stability against impurity ingress, and lower power consumption, ensuring high-speed operation and superior display quality.
Implementation Method 1
highly purified oxide semiconductor having a wide band gap and reduced carrier concentration
Implementation Method 2
reduced wiring resistance, enhanced on-off current ratio
Implementation Method 3
sealed by insulating films, and using conductive layers with copper and silicon nitride to reduce resistance and impurity ingress
Implementation Method 4
An oxide semiconductor film can be formed by a sputtering method or the like
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.