Oxide TFT with Intermediate Layer for Stable Patterning
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Solution Overview
Problem
Amorphous oxide semiconductor layers in thin film field-effect transistors are prone to oxygen defects, fluctuate with atmospheric conditions, and are susceptible to corrosion by acidic etchants, making it difficult to achieve stable performance and refined patterning, especially when used on flexible substrates.
Innovation Solution
Incorporating a resistance layer with lower electric conductivity than the active layer and an intermediate layer with an oxide having stronger oxygen bonding properties between the active layer and the resistance layer, which helps stabilize the semiconductor characteristics and prevent corrosion during patterning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If an amorphous oxide semiconductor layer is used as the active layer, then low-temperature film formation is achieved, but oxygen defects occur and semiconductor characteristics fluctuate
Solution Approach 1:
The patent applies inert atmosphere by performing film formation and heat treatment in a nitrogen atmosphere. The nitrogen environment prevents oxidation and stabilizes the amorphous oxide semiconductor layer, reducing oxygen defects and characteristic fluctuations while maintaining low-temperature processing capability
Solution Approach 2:
The patent implements preliminary action by conducting heat treatment in a nitrogen atmosphere before final device assembly. This pre-treatment stabilizes the semiconductor characteristics and reduces oxygen defects in advance, ensuring reliable performance throughout device operation
2Temperature
If an amorphous oxide semiconductor layer is used, then low-temperature processing is enabled, but the layer is corroded by acidic etchants during patterning
Solution Approach 1:
The patent introduces an intermediary protective layer between the amorphous oxide semiconductor layer and acidic etchants. This protective layer acts as a barrier during patterning processes, preventing etchant contact and corrosion of the semiconductor layer while allowing low-temperature processing to proceed
Solution Approach 2:
The patent applies preliminary anti-action by forming a protective coating on the amorphous oxide semiconductor layer before patterning. This pre-formed protection counteracts the harmful effect of acidic etchants, enabling safe pattern formation without compromising the semiconductor layer
3Reliability
If oxygen concentration is controlled in deposition, then oxygen defects are suppressed, but manufacturing complexity increases
Solution Approach 1:
The patent applies parameter changes by optimizing the oxygen partial pressure during deposition and heat treatment processes. By controlling these parameters within specific ranges in a nitrogen atmosphere, oxygen defects are suppressed while maintaining manageable manufacturing complexity through standardized process parameters
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
This configuration enhances field-effect mobility, improves the ON/OFF ratio, and allows for stable and high-resolution patterning, addressing the issues of oxygen defects and etchant resistance, while maintaining flexibility and low-temperature processing.
Implementation Method 1
an intermediate layer with an oxide having stronger oxygen bonding properties between the active layer and the resistance layer
Implementation Method 2
a resistance layer having an electric conductivity that is lower than an electric conductivity of the active layer is provided between the active layer and at least one of the source electrode or the drain electrode
Data Source
Figure 1
Figure 4A~4E
Figure 5A~5F
AI summary
The present invention provides a thin film field-effect transistor comprising a substrate having thereon at least a gate electrode, a gate insulating film, an active layer, a source electrode, and a drain electrode, wherein the active layer is an oxide semiconductor layer, a resistance layer having an electric conductivity that is lower than an electric conductivity of the active layer is provided between the active layer and at least one of the source electrode or the drain electrode, and an intermediate layer comprising an oxide comprising an element having a stronger bonding force with respect to oxygen than that of the oxide semiconductor in the active layer is provided between the active layer and the resistance layer.