Oxide Semiconductor Transistor Wiring with Copper Barrier
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Solution Overview
Problem
Thin film transistors using oxide semiconductors face issues with parasitic resistance, off current, and impurity contamination, leading to decreased display quality and increased power consumption due to high wiring resistance, especially in large and high-definition display devices.
Innovation Solution
A semiconductor device with a storage capacitor structure where insulating layers sandwich a conductive layer, including copper, to reduce parasitic resistance and prevent copper diffusion, combined with an oxide semiconductor layer containing indium, gallium, and zinc, and conductive layers made from elements like tungsten, tantalum, or titanium to enhance reliability and operation speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If copper is used to form low-resistance wiring layers, then wiring resistance is reduced, but copper diffusion into the oxide semiconductor layer occurs causing instability
Solution Approach 1:
A barrier layer comprising a nitride film or oxide nitride film is introduced between the copper wiring layer and the oxide semiconductor layer. This intermediary layer prevents copper diffusion into the semiconductor while maintaining low electrical resistance for signal transmission, thus resolving the contradiction between reducing wiring resistance and preventing copper diffusion.
Solution Approach 2:
The wiring structure uses a composite material approach by combining copper (for low resistance) with a nitride/oxide nitride barrier layer (for diffusion prevention). This composite structure allows the system to simultaneously achieve low wiring resistance and prevent harmful copper diffusion into the oxide semiconductor.
2Ease of manufacture
If oxide semiconductor layers are used to simplify manufacturing, then processing temperature is reduced, but parasitic resistance at metal-oxide interfaces increases
Solution Approach 1:
The patent applies local quality by using different materials at different locations: titanium nitride or tungsten nitride is used specifically at the contact regions where metal electrodes meet the oxide semiconductor layer. These materials have superior electrical conductivity and form low-resistance interfaces, while the rest of the oxide semiconductor layer maintains its low-processing-temperature advantage. This localized material optimization reduces parasitic resistance without sacrificing the manufacturing simplicity of oxide semiconductors.
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 results in a semiconductor device with improved display quality, reduced power consumption, and increased reliability by minimizing wiring resistance and copper diffusion, enabling stable high-speed operation and high-yield production.
Implementation Method 1
An oxide semiconductor film can be formed at a temperature of 300 °C or lower by a sputtering method
Data Source
Figure 1A~1B
Figure 2A~2C
Figure 3
AI summary
It is an object to provide a semiconductor device typified by a display device having a favorable display quality, in which parasitic resistance generated in a connection portion between a semiconductor layer and an electrode is suppressed and an adverse effect such as voltage drop, a defect in signal wiring to a pixel, a defect in grayscale, and the like due to wiring resistance are prevented. In order to achieve the above object, a semiconductor device according to the present invention may have a structure where a wiring with low resistance is connected to a thin film transistor in which a source electrode and a drain electrode that include metal with high oxygen affinity are connected to an oxide semiconductor layer with a suppressed impurity concentration. In addition, the thin film transistor including the oxide semiconductor may be surrounded by insulating films to be sealed.