Aluminum Oxide TFT Passivation Layer Doping for Etching Stop Removal
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Solution Overview
Problem
The manufacturing process of thin film transistors is complex due to the need for an etching stop layer, which increases the number of manufacturing steps and complicates the structure, while existing metal oxide solutions do not fully address the requirement for higher migration rates and resolution in larger displays.
Innovation Solution
A method involving the formation of a first passivation layer from aluminum oxide on source and drain electrodes, with gallium and tin ions doped into regions corresponding to the gate electrode to create an aluminum-gallium-tin oxide active layer, eliminating the need for an etching stop layer and simplifying the process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an etching stop layer is deposited on the IGZO active layer to protect it during etching processes, then the TFT performance is improved, but the number of manufacturing steps increases
Solution Approach 1:
The patent combines the passivation layer and etching stop layer functions into a single aluminum oxide layer. This layer serves dual purposes: protecting the active layer during etching processes and providing passivation functionality, thereby eliminating the need for separate etching stop layer deposition and reducing manufacturing steps while maintaining TFT performance
Solution Approach 2:
The aluminum oxide layer is designed to perform multiple functions simultaneously: it acts as a passivation layer for the active layer, serves as an etching stop layer during source and drain electrode etching, and provides structural support. This multi-functionality reduces the overall number of layers and manufacturing steps required
2Ease of manufacture
If conventional amorphous silicon is used as the channel layer, then the manufacturing process is simpler, but the migration rate is relatively low
Solution Approach 1:
The patent changes the material composition of the active layer from conventional amorphous silicon to aluminum oxide doped with gallium and tin ions. This compositional change dramatically increases the carrier migration rate (by dozens of times) while maintaining compatibility with existing low-temperature manufacturing processes, thus improving speed without sacrificing ease of manufacture
3Speed
If metal oxide such as IGZO is used as the active layer to increase migration rate, then charging/discharging speed is improved, but an additional lithographic process is required to form the etching stop layer
Solution Approach 1:
The patent merges the passivation layer formation and etching stop layer formation into a single aluminum oxide deposition process. This eliminates the need for an additional lithographic process that would otherwise be required to define the etching stop layer, thereby maintaining high charging/discharging speed while reducing device complexity
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 simplifies the manufacturing process, reduces the number of steps, and enhances the performance of thin film transistors by forming a semiconductor metal oxide active layer that improves migration rates and resolution without additional lithographic processes.
Implementation Method 1
forming an active layer by doping with ions a region of the first passivation layer corresponding to a gate electrode of the thin film transistor
Data Source
Figure 1~2b
Figure 2c~2d
Figure 2e~2f
AI summary
A thin film transistor, a pixel structure, an array substrate, a display device, a method for manufacturing a thin film transistor, and a method for manufacturing a pixel structure are disclosed. The thin film transistor includes a gate electrode, a source electrode and a drain electrode, wherein a first passivation layer made from an aluminum oxide material is provided on the source electrode and the drain electrode, and an active layer made from an aluminum oxide material doped with ions is provided in a region of the first passivation layer corresponding to the gate electrode. The ions include gallium ions and tin ions so that the doped aluminum oxide material forms an aluminum-gallium-tin oxide. Since the first passivation layer as insulation material is doped with the ions to form an active layer, the manufacturing process of the thin film transistor is simplified, the etching stop layer may be omitted, thereby simplifying the structure of the thin film transistor.