LTPS TFT Fabrication via Metal Ion Diffusion
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Solution Overview
Problem
The conventional method of forming low temperature polysilicon thin film transistors (LTPS TFTs) is complex and costly due to the requirement for ion implantation equipment and processes, particularly for defining source and drain contact areas.
Innovation Solution
A method involving the deposition of an insulation metal oxide layer on the LTPS TFT substrate, followed by annealing to drive metal ions (such as Cu2+, Al3+, Mg2+, Zn2+, and Ni2+) into the source and drain contact areas, eliminating the need for ion implantation and simplifying the fabrication process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If ion implantation is used to form source and drain contact areas, then the LTPS TFT can be fabricated with proper doping, but the manufacturing cost and process complexity increase significantly
Solution Approach 1:
The patent extracts and removes the ion implantation step from the conventional LTPS TFT fabrication process. Instead of using ion implantation equipment to dope the source and drain contact areas, the invention uses a different approach where the doping is achieved through subsequent processing steps, thereby eliminating the need for complex ion implantation equipment and processes while maintaining the necessary doping quality for device operation
Solution Approach 2:
The patent inverts the conventional sequence and method of doping. Rather than doping first through ion implantation and then forming contact areas, the invention forms the contact areas first and achieves doping through alternative means during subsequent processing, fundamentally changing the order and method of operations to simplify the overall process
2Manufacturing precision
If ion implantation equipment is used for defining source and drain contact areas, then precise doping can be achieved, but the manufacturing cost increases
Solution Approach 1:
The patent replaces expensive ion implantation equipment with more economical alternative processing methods. The invention uses standard semiconductor processing equipment and materials that are more readily available and cost-effective, achieving the necessary doping precision through chemical and thermal processes rather than requiring costly ion implantation facilities
Solution Approach 2:
The patent changes the processing parameters and methods from physical ion implantation to chemical and thermal processes. By altering the doping approach from high-energy ion bombardment to controlled chemical deposition and thermal diffusion, the invention achieves comparable doping precision using less expensive equipment and processes
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 significantly simplifies the manufacturing process and reduces costs by forming ohmic contacts through metal ion diffusion, thereby omitting the need for p-type ion implantation.
Implementation Method 1
annealing to drive metal ions (such as Cu2+, Al3+, Mg2+, Zn2+, and Ni2+) into the source and drain contact areas
Implementation Method 2
after an annealing procedure
Data Source
AI summary
A LTPS TFT comprises a substrate, and a buffer layer, a low temperature polysilicon layer, a source contact area, a drain contact area, a gate insulating layer, a gate layer, a dielectric layer, a source and a drain disposed on the substrate successively. The source contact area and the drain contact area are doped with metal ions individually. The source and the drain are connecting with the source and drain contact areas separately through the dielectric layer. The metal ions include at least one of Cu2+, Al3+, Mg2+, Zn2+ and Ni2+. A method of fabricating the LTPS TFT is also provided. An annealing is performed for driving individually metal ions of the insulation metal oxide layer into the source contact area and the drain contact area. Thus, the step of implanting p-type ions can be omitted, the procedure can be significantly simplified, and the manufacturing cost can be reduced.