Metal Oxynitride Thin Film Transistor Single Patterning
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Solution Overview
Problem
Conventional thin film transistors, particularly those using amorphous silicon and polysilicon, face challenges such as high manufacturing costs, complex fabrication processes, low reliability, and low aperture ratio, which are exacerbated by the need for multiple patterning processes and the use of backlighting in display panels, making them unsuitable for large-size displays and high-performance circuits.
Innovation Solution
A method for fabricating thin film transistors that involves forming a semiconductor material layer with a conductive metal layer and an etch stop layer, allowing for the reduction of patterning steps to a single process, using a doped semiconductor material resistant to hydrogen peroxide etching, and optimizing the structure to simplify manufacturing and reduce costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional amorphous silicon or polysilicon is used for thin film transistors, then the transistors can be manufactured with established processes, but the manufacturing costs are high and the fabrication processes are complex
Solution Approach 1:
The patent changes the material parameter from conventional amorphous silicon or polysilicon to metal oxynitride (such as In-Ga-Zn-O), which fundamentally alters the fabrication process requirements. This material substitution enables simpler manufacturing processes while maintaining or improving transistor performance characteristics
Solution Approach 2:
The patent employs composite material structures including metal oxynitride semiconductor layers combined with specific etch stop layers and conductive layers. This composite approach allows for simplified processing while achieving the desired device performance and reliability
2Manufacturing precision
If multiple patterning processes are used for manufacturing thin film transistors, then the transistor structures can be precisely formed, but the manufacturing costs increase and production efficiency decreases
Solution Approach 1:
The patent merges multiple patterning operations into a single patterning process by using the metal oxynitride material's unique properties. The single patterning step forms the active layer, source electrode, and drain electrode simultaneously, eliminating the need for sequential patterning steps and thereby improving productivity while maintaining manufacturing precision
Solution Approach 2:
The metal oxynitride semiconductor layer serves multiple functions: it acts as the active layer, provides etch resistance, and enables direct patterning of multiple transistor components in one step. This multi-functionality reduces the number of processing steps required while maintaining structural precision
3Ease of manufacture
If metal oxynitride is used as semiconductor material, then manufacturing costs are reduced and transmittance is improved, but the material requires specific etching resistance properties that complicate the etching process
Solution Approach 1:
The patent introduces an etch stop layer as an intermediary between the metal oxynitride active layer and the etching process. This etch stop layer provides the necessary etching resistance, allowing the metal oxynitride to be etched selectively without requiring the metal oxynitride itself to have high etch resistance, thereby simplifying the overall etching process
Solution Approach 2:
The patent replaces the need for complex etching control of metal oxynitride with a chemical solution approach using specific etchants that selectively etch the etch stop layer while leaving the metal oxynitride intact. This substitution simplifies the etching process by using chemical selectivity rather than relying on mechanical or physical etching resistance properties
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 fabrication process, reduces manufacturing costs, and enhances the performance of thin film transistors by enabling the formation of active layers, etch stop layers, and electrodes in a single patterning step, improving the efficiency and reliability of the transistors.
Implementation Method 1
doping a first portion of the semiconductor material layer in a region corresponding to the channel region with a dopant thereby forming the etch stop layer
Implementation Method 2
the etch stop layer being substantially resistant to an etchant for etching a metal material; wherein the etchant is hydrogen peroxide
Data Source
Figure 1
Figure 2A~2B
Figure 2C~2E
AI summary
A thin film transistor includes a base substrate(100); an active layer(200') on the base substrate having a channel region, a source electrode contact region, and a drain electrode contact region; an etch stop layer(600) on a side of the channel region distal to the base substrate covering the channel region; a source electrode(300') on a side of the source electrode contact region distal to the base substrate; and a drain electrode (300') on a side of the drain electrode contact region distal to the base substrate. A thickness of the active layer in the source electrode contact region and the drain electrode contact region is substantially the same as a combined thickness of the active layer in the channel region and the etch stop layer.