Source/Drain Electrode Structure for Display Panel Wiring Resistance
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Solution Overview
Problem
Larger screen sizes in display panel devices lead to increased wiring resistance, degrading image quality, and the residue from partition walls on source/drain electrodes reduces semiconductor layer crystallinity and increases contact resistance, affecting TFT characteristics.
Innovation Solution
A display panel device with a source/drain electrode structure featuring a high-density film in the lower layer and a low-density film in the upper layer, where the low-density film is easily soluble to remove residue and oxide films, reducing wiring resistance and improving contact with pixel electrodes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the source/drain electrode is extended to function as wiring in larger screen displays, then the wiring length increases, but the wiring resistance increases causing lower display image quality
Solution Approach 1:
The source/drain electrode is divided into two distinct layers: a lower layer source/drain electrode and an upper layer source/drain electrode. This segmentation allows each layer to perform different functions - the lower layer provides mechanical support and basic conductivity, while the upper layer serves as the primary wiring path with optimized conductivity, thereby reducing overall wiring resistance in large-screen displays.
Solution Approach 2:
The patent employs a composite electrode structure where the lower layer source/drain electrode and upper layer source/drain electrode are made of different materials or have different structural properties. This composite approach combines the advantages of both layers to achieve low resistance wiring while maintaining mechanical integrity, solving the wiring resistance problem in large-screen displays.
2Manufacturing precision
If the partition wall part is formed to define the semiconductor layer, then the semiconductor layer is properly positioned, but residue of the partition wall part remains on the source/drain electrode surface degrading semiconductor layer crystallinity
Solution Approach 1:
The harmful residue of the partition wall part is extracted and removed from the source/drain electrode surface through a dedicated cleaning step. This extraction process eliminates the contaminant that would otherwise degrade semiconductor layer crystallinity, while the semiconductor layer positioning is maintained through the partition wall structure itself.
Solution Approach 2:
The cleaning step is performed preliminarily before forming the semiconductor layer. By removing the partition wall residue in advance, the surface of the source/drain electrode is prepared in a clean state, ensuring that the subsequently formed semiconductor layer achieves optimal crystallinity without contamination from partition wall materials.
3Shape
If the insulation layer is burned to planarize the drive circuit part, then the surface is planarized, but oxide film is formed on the source/drain electrode surface increasing contact resistance
Solution Approach 1:
The oxidation that occurs during insulation layer burning is converted into a beneficial process by selectively removing the formed oxide film from the source/drain electrode surface. The oxide film is allowed to form temporarily and then removed through a selective cleaning step, transforming the harmful oxidation effect into a controlled process that can be reversed to achieve low contact resistance while maintaining surface planarity.
Solution Approach 2:
The cleaning process is applied locally and selectively only to the source/drain electrode surface where contact resistance is critical, while leaving the insulation layer planarization intact. This localized treatment removes oxide films from the electrode contact areas without compromising the overall surface planarity achieved by the insulation layer burning process.
4Device complexity
If a single-layer source/drain electrode is used, then the structure is simple, but the wiring resistance is high and contact characteristics are insufficient
Solution Approach 1:
The source/drain electrode is segmented into two layers with different materials or properties. The lower layer provides mechanical support and baseline conductivity, while the upper layer is optimized for low resistance and good contact characteristics. This segmentation resolves the contradiction by achieving low wiring resistance and excellent contact properties while maintaining reasonable structural complexity.
Data Source
AI summary
A display panel device includes: a gate electrode above a substrate; a gate insulator above the gate electrode; a first source electrode and a first drain electrode above the gate insulator; a second source electrode and a second drain electrode above the first source electrode and the first drain electrode respectively; a first partition wall part having an opening in which the second source electrode and the second drain electrode are exposed; a semiconductor layer in the opening; an insulation layer above the semiconductor layer; a lower electrode above the insulation layer; and a contact hole in the insulation layer, for connecting the lower electrode and the second drain electrode or the second source electrode, wherein a film structure of each of the second source electrode and the second drain electrode is sparser than a film structure of each of the first source electrode and the first drain electrode.