Amorphous Oxide TFT with Resistance Layer for OFF Current Reduction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Thin film field effect transistors (TFTs) using amorphous oxide semiconductors face challenges such as high OFF current, low ON/OFF ratio, and instability due to contact with resin substrates, and existing solutions like inorganic insulating layers increase process complexity without fully addressing these issues.
Innovation Solution
A TFT structure with an amorphous oxide active layer containing In, Sn, or Zn, and an electric resistance layer containing Ga, Al, Mg, or Si between the active layer and electrodes, separated from a protective resin layer to prevent direct contact and enhance chemical resistance for patterning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If an amorphous oxide semiconductor is used as an active layer to enable low-temperature processing on resin substrates, then the substrate temperature requirement is reduced, but the OFF current increases and ON/OFF ratio decreases
Solution Approach 1:
The patent changes the material composition parameters of the active layer by incorporating specific metal elements (In, Ga, Zn) in controlled ratios. By adjusting the compositional parameters of the amorphous oxide semiconductor, the patent achieves simultaneous improvement in low-temperature processability and electrical characteristics (reduced OFF current and improved ON/OFF ratio).
Solution Approach 2:
The patent creates a composite amorphous oxide semiconductor material combining multiple metal oxides (In-O, Ga-O, Zn-O) in specific proportions. This composite material structure enables the active layer to exhibit both low-temperature processability and superior electrical characteristics that single-component oxides cannot achieve alone.
2Reliability
If the active layer is covered with an inorganic insulating layer to prevent contact with resin, then the contact instability is reduced, but the number of processes increases
Solution Approach 1:
The patent makes the active layer itself serve multiple functions: it acts as both the functional semiconductor layer and its own protective barrier against the resin substrate. By optimizing the amorphous oxide semiconductor's inherent properties, the patent eliminates the need for separate protective insulating layers while maintaining threshold voltage stability.
Solution Approach 2:
The patent extracts and removes the separate inorganic insulating protective layer from the structure. Instead of adding a protective layer, the patent enhances the active layer's own resistance to resin contact through material composition optimization, thereby simplifying the device structure and reducing process steps.
3Reliability
If a protective layer is added to prevent active layer contact with resin, then contact instability is reduced, but patterning difficulty increases
Solution Approach 1:
The patent removes the separate protective layer that complicates patterning. By enhancing the active layer's intrinsic resistance to resin contact through material composition control, the patent eliminates the need for additional protective layers, thereby maintaining ease of patterning while ensuring device stability.
Data Source
AI summary
A thin film field effect transistor includes at least: a substrate; and a gate electrode, a gate insulating layer, an active layer, a source electrode and a drain electrode, and a protective layer provided on the substrate in this order from the substrate side. The active layer is a layer containing an amorphous oxide containing at least one metal selected from the group consisting of In, Sn, Zn and Cd. The thin film field effect transistor further includes, between the active layer and at least one of the source electrode or the drain electrode, an electric resistance layer containing an oxide or nitride containing at least one metal selected from the group consisting of Ga, Al, Mg, Ca and Si.