Cubic Boron Nitride Thin Film Transistor Active Layer
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Solution Overview
Problem
The manufacturing process of thin film transistors is complex due to the use of low temperature poly-silicon, which requires processes like dehydrogenating, annealing, and hydrogenating, making it inefficient.
Innovation Solution
The method involves using cubic boron nitride as the active layer material, formed through chemical vapor deposition, omitting the need for dehydrogenating, annealing, and hydrogenating processes, and employing a doping process with ion implantation to simplify the manufacturing process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If low temperature poly-silicon is used as the active layer material, then the transistor can be manufactured with conventional processes, but the manufacturing process becomes complex due to required dehydrogenating, annealing, and hydrogenating steps
Solution Approach 1:
The patent changes the material parameter from low temperature poly-silicon to cubic boron nitride, which fundamentally alters the manufacturing requirements. This material substitution eliminates the need for dehydrogenating, annealing, and hydrogenating processes, directly resolving the technical contradiction by simplifying the manufacturing process while reducing the number of process steps
Solution Approach 2:
The patent extracts and removes the complex processing steps (dehydrogenating, annealing, hydrogenating) from the manufacturing process by using cubic boron nitride material that does not require these treatments. This extraction of unnecessary process steps directly addresses the contradiction between ease of manufacture and device complexity
2Productivity
If multiple processing steps (dehydrogenating, annealing, hydrogenating) are applied to low temperature poly-silicon, then the active layer can be formed, but the production efficiency decreases
Solution Approach 1:
By changing the material parameter from low temperature poly-silicon to cubic boron nitride, the patent eliminates multiple time-consuming processing steps. The cubic boron nitride can be directly deposited and patterned without requiring dehydrogenating, annealing, or hydrogenating, thereby significantly improving production efficiency and reducing manufacturing cycle time
Solution Approach 2:
The patent skips the intermediate processing steps (dehydrogenating, annealing, hydrogenating) that are mandatory for low temperature poly-silicon but unnecessary for cubic boron nitride. This skipping of redundant steps directly improves productivity by reducing the total manufacturing time
3Reliability
If conventional doping processes are used on low temperature poly-silicon, then the active layer can be doped, but the leakage current increases due to lower hole mobility and narrower forbidden band width
Solution Approach 1:
The patent changes the material parameter from low temperature poly-silicon to cubic boron nitride, which inherently possesses superior electrical characteristics including higher hole mobility and wider forbidden band width. This material parameter change improves reliability by reducing leakage current while maintaining ease of manufacture through effective ion implantation doping
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, improves production efficiency, and reduces leakage current due to higher hole mobility and wider forbidden band width of cubic boron nitride, while maintaining effective doping characteristics.
Implementation Method 1
forming an active layer on the substrate, wherein the active layer is made of cubic boron nitride; during the step of forming an active layer on the substrate, the active layer is formed by a chemical vapor deposition method, vapor for forming the active layer include boron chloride, boron hydride, and ammonia
Implementation Method 2
applying a doping process to the active layer includes: applying a first doping treatment to the doping region; forming the first insulating layer on the patterned active layer; forming through holes in the first insulating layer corresponding to the doping region to expose at least a part of the doping region; and applying a second doping treatment to the doping region exposed through the through holes
Data Source
AI summary
The present disclosure provides a method for manufacturing a thin film transistor and a thin film transistor, which includes providing a substrate; forming an active layer on the substrate and patterning the active layer, the active layer is made of cubic boron nitride; and forming a first insulating layer, a gate electrode metal layer, a second insulating layer, a source and drain metal layer and a flat layer on the active layer successively. the method for manufacturing a thin film transistor and the thin film transistor of the present disclosure employ cubic boron nitride instead of polysilicon as active layer materials, CVD process is directly applied to form the active layer with cubic boron nitride.