IGZO Thin Film Transistor Active Layer Composition Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current semiconductor active layers, such as those made of amorphous silicon or polysilicon, face challenges in mobility and threshold voltage uniformity, while oxide-based semiconductors like IGZO require improved atomic composition control to enhance electrical characteristics in thin film transistors for display devices.
Innovation Solution
A method involving the use of two targets to deposit ions, including In, Ga, and Zn, where the atomic percentage of In in the IGZO layer is adjusted by varying the molar ratio and bias power of the second target, allowing for a compositional range of 45% to 80% In, improving the IGZO active layer's properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a single target is used to deposit IGZO layer, then the manufacturing process is simple, but the atomic composition control is insufficient
Solution Approach 1:
The single target is divided into two separate targets: a first target containing In, Ga, and Zn elements, and a second target containing In and Zn elements. This segmentation allows independent control of deposition rates for each target, enabling precise adjustment of the atomic composition of In in the IGZO layer to be about 45 atomic % to about 80 atomic %, thereby resolving the contradiction between manufacturing precision and device complexity.
2Speed
If amorphous silicon is used as semiconductor layer, then the manufacturing process is simple, but the mobility is low
Solution Approach 1:
The patent changes the material composition parameter by using oxide-based semiconductor (IGZO) with specific atomic composition (In: 45-80 atomic %, Ga: 5-30 atomic %, Zn: 10-30 atomic %) instead of conventional amorphous silicon. This parameter change achieves high carrier mobility while maintaining compatibility with existing thin film transistor manufacturing processes, resolving the contradiction between mobility and ease of manufacture.
3Stability of the object's composition
If polysilicon is used as semiconductor layer, then the mobility is high, but the threshold voltage uniformity is poor
Solution Approach 1:
The patent uses a composite oxide-based semiconductor material (IGZO) combining multiple elements (In, Ga, Zn, O) with specifically controlled atomic ratios. This composite material structure provides both high carrier mobility and uniform threshold voltage characteristics, resolving the contradiction between mobility and threshold voltage uniformity that exists in polysilicon-based devices.
4Object-affected harmful factors
If conventional semiconductor layers are used, then the manufacturing process is established, but leakage current occurs under light illumination
Solution Approach 1:
The patent changes the band gap parameter by using oxide-based semiconductor (IGZO) with a wider band gap compared to conventional amorphous silicon or polysilicon. This wider band gap reduces absorption of visible light energy, thereby minimizing leakage current under light illumination and improving device reliability and stability.
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 approach enhances the mobility and reduces leakage current, achieving better electrical characteristics and stability in thin film transistors, particularly in organic light emitting display devices.
Implementation Method 1
depositing ions including In, Ga, and Zn from a first target
Implementation Method 2
depositing ions including In from a second target having a different atomic composition from the first target
Data Source
AI summary
A method of manufacturing an IGZO active layer includes depositing ions including In, Ga, and Zn from a first target, and depositing ions including In from a second target having a different atomic composition from the first target. The deposition of ions from the second target may be controlled to adjust an atomic % of In in the IGZO layer to be about 45 atomic % to about 80 atomic %.