Non-Silicon Complementary TFT Same-Layer Structure
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Solution Overview
Problem
The existing silicon semiconductor process for manufacturing complementary thin film transistors (TFTs) faces challenges due to high process temperatures and the need for multiple doping processes, which limits flexibility and increases costs, especially when trying to create bendable or foldable electronic devices.
Innovation Solution
A complementary TFT structure is developed using a non-silicon semiconductor substrate with a low heat resistance temperature, where the first conductive semiconductor layer and the second gate electrode layer are formed in the same layer and from the same material, eliminating the need for N-type and P-type doping processes and reducing the overall number of manufacturing steps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single crystalline silicon semiconductor process is used to manufacture complementary TFT, then the transistor performance is improved, but the process temperature becomes too high for glass or plastic substrates
Solution Approach 1:
The patent changes the material parameter from single crystalline silicon to amorphous silicon, which allows the process temperature to be reduced from high temperatures (unsuitable for glass/plastic substrates) to lower temperatures (compatible with low heat resistance substrates). This material parameter change resolves the contradiction between transistor performance and process temperature requirements.
2Temperature
If a polycrystalline silicon semiconductor process is used, then the process temperature is reduced, but the number of processes increases due to crystallization and doping steps
Solution Approach 1:
The patent extracts and removes the complex crystallization and doping processes from the manufacturing flow by using amorphous silicon instead of polycrystalline silicon. This eliminates the need for high-temperature crystallization steps and multiple doping processes, significantly reducing the total number of manufacturing steps while maintaining low process temperature compatibility.
Solution Approach 2:
The patent uses amorphous silicon, which is easier and cheaper to process than polycrystalline silicon, accepting the lower crystalline order in exchange for simplified manufacturing. The amorphous silicon layer serves as a disposable, easily manufacturable material that eliminates the need for complex thermal processing and doping steps.
3Reliability
If silicon semiconductor process is used, then complementary TFT can be manufactured, but additional post-process is needed to transport the circuit to glass or plastic substrate, increasing cost and process number
Solution Approach 1:
The patent merges the complementary TFT manufacturing process directly onto the glass or plastic substrate by using amorphous silicon, which is compatible with low-temperature processing. This eliminates the need for separate silicon wafer fabrication and subsequent transfer/post-process steps, integrating the entire manufacturing process into a single low-temperature flow that directly produces flexible complementary TFT devices on flexible substrates.
Data Source
AI summary
A complementary thin film transistor (TFT) includes a substrate and a first TFT and a second TFT disposed on the substrate, wherein a first conductive semiconductor layer of the first TFT and a second gate electrode layer of the second TFT are disposed in the same layer and include the same material.