Integrated Display Driver TFT Layout for High-Resolution Panels
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Solution Overview
Problem
The increasing number of gate and signal lines in display devices leads to higher manufacturing costs due to difficulties in mounting IC chips and increased contact resistance, which can distort input signals and complicate the process with more contact holes and a larger area occupied by the driver circuit.
Innovation Solution
A display device is designed with a pixel portion and driver circuit formed over one substrate, using an inverted staggered thin film transistor with an oxide semiconductor, specifically an InMO3 (ZnO)m film where M denotes metal elements like Ga, Fe, Ni, or Co, to reduce contact resistance and the number of contact holes, and the oxide semiconductor film is formed using a sputtering method at low temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the number of gate lines and signal lines is increased to achieve higher definition display, then the display resolution is improved, but the manufacturing cost increases due to difficulty in mounting IC chips and increased contact resistance
Solution Approach 1:
The patent integrates the driver circuit directly onto the display substrate, merging what were previously separate components (display panel and driver IC) into a single unified structure. This eliminates the need for external IC chip mounting and reduces the number of contact holes required, thereby lowering manufacturing complexity and cost while maintaining high display resolution
Solution Approach 2:
The substrate serves multiple functions: it acts as both the display panel substrate and the driver circuit substrate. By forming both the pixel portion and driver circuit on the same substrate, the design achieves multi-functionality, reducing the need for separate mounting processes and interconnections
2Reliability
If more contact holes are used to connect elements in the driver circuit, then the electrical connections are improved, but the manufacturing process becomes more complex and the area occupied by the driver circuit increases
Solution Approach 1:
The gate electrode of each transistor is directly connected to the source or drain wiring without requiring separate contact holes. This merging of the gate electrode connection with the source/drain wiring structure eliminates the need for additional contact holes, simplifying the manufacturing process while maintaining reliable electrical connections
Solution Approach 2:
The patent removes the unnecessary contact holes from the conventional structure by directly connecting the gate electrode to the source/drain wiring. This extraction of redundant connection elements simplifies the overall structure and reduces manufacturing complexity
3Reliability
If contact resistance between gate wiring and upper wiring is reduced, then the signal distortion is minimized, but the manufacturing process becomes more difficult
Solution Approach 1:
The gate electrode is merged with the source or drain wiring structure, eliminating the need for separate contact interfaces. This direct integration inherently minimizes contact resistance without requiring complex manufacturing controls, as there are no separate contact holes or interfaces to manage
Solution Approach 2:
The patent removes the source of contact resistance by eliminating the contact hole structure between gate wiring and upper wiring. By taking out the intermediate contact layer and directly connecting gate to source/drain wiring, contact resistance is minimized without adding manufacturing difficulty
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 configuration reduces manufacturing costs, achieves high-speed driving of the driver circuit, and provides a display device with excellent electrical properties and high reliability by using n-channel TFTs and a structure that directly connects the gate electrode to the source or drain wiring, minimizing contact resistance and the number of contact holes.
Implementation Method 1
The oxide semiconductor film can be formed by a sputtering method or the like at a temperature lower than or equal to 300° C.
Data Source
AI summary
With an increase in the definition of a display device, the number of pixels is increased, and thus the numbers of gate lines and signal lines are increased. Due to the increase in the numbers of gate lines and signal lines, it is difficult to mount an IC chip having a driver circuit for driving the gate and signal lines by bonding or the like, which causes an increase in manufacturing costs. A pixel portion and a driver circuit for driving the pixel portion are formed over one substrate. At least a part of the driver circuit is formed using an inverted staggered thin film transistor in which an oxide semiconductor is used. The driver circuit as well as the pixel portion is provided over the same substrate, whereby manufacturing costs are reduced.