TFT Panel Gate Insulation Layout to Block Nitride Diffusion
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Solution Overview
Problem
In conventional TFT backplane fabrication, the nitride layer from the driver TFT diffuses during high-temperature processing, contaminating the non-polysilicon material of the switching TFT and reducing the overall performance of the backplane.
Innovation Solution
A method is developed where a polysilicon active region is formed on a substrate, followed by sequential deposition of an oxide and nitride layer to create a first insulating layer. The nitride layer is then selectively removed using dry etching self-aligned with gate electrodes, ensuring it remains only between the oxide layer and the gate electrodes, preventing diffusion and contamination of the switching TFT active region.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the nitride layer is used as part of the gate insulating layer structure for the driver TFT, then the reliability and electrical performance of the driver TFT is improved, but the nitride layer diffuses during high-temperature processing and contaminates the non-polysilicon material of the switching TFT, reducing its performance
Solution Approach 1:
The gate insulating layer structure is segmented into distinct regions: a first gate insulating layer (oxide layer) for the driver TFT and a second gate insulating layer (nitride layer) for the switching TFT. This segmentation allows each TFT type to have optimized insulating layer composition without mutual interference, preventing nitride diffusion contamination while maintaining driver TFT performance.
Solution Approach 2:
Different gate insulating layer structures are applied to different regions of the TFT backplane. The driver TFT region receives an oxide-based gate insulating layer, while the switching TFT region receives a nitride-based gate insulating layer. This local differentiation ensures that each region has the appropriate material properties for its specific function without suffering from cross-contamination.
2Object-affected harmful factors
If the nitride layer is removed completely, then contamination of switching TFT is prevented, but the electrical performance and reliability of driver TFT deteriorates
Solution Approach 1:
The gate insulating layer is segmented into a first gate insulating layer (oxide) and a second gate insulating layer (nitride), where the oxide layer is positioned for the driver TFT and the nitride layer is positioned for the switching TFT. This segmentation ensures the nitride layer remains to improve driver TFT performance while being spatially separated from the switching TFT active region to prevent contamination.
Solution Approach 2:
The first gate electrode acts as an intermediary barrier that physically separates the nitride layer from the switching TFT active region. By positioning the first gate electrode between the nitride layer and the switching TFT, it prevents nitride diffusion while allowing the nitride layer to remain in place for electrical performance enhancement of the driver TFT.
3Ease of manufacture
If the same gate insulating layer structure is used for both driver TFT and switching TFT, then manufacturing process is simplified, but the performance requirements of different TFT types cannot be simultaneously optimized
Solution Approach 1:
The gate insulating layer structure is segmented into a first gate insulating layer and a second gate insulating layer with different materials and positions. This segmentation enables different insulating layer configurations for driver TFT and switching TFT, allowing simultaneous optimization of their respective performance requirements while maintaining a systematic manufacturing approach.
Solution Approach 2:
Different gate insulating layer compositions are applied locally to different TFT types based on their specific performance requirements. The driver TFT receives an oxide-based gate insulating layer optimized for its function, while the switching TFT receives a nitride-based gate insulating layer optimized for its function, achieving local performance optimization without compromising overall manufacturing feasibility.
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 reduces the contamination of the switching TFT by the nitride layer, enhancing the performance of the TFT backplane by blocking nitride diffusion during high-temperature processing.
Implementation Method 1
in the high temperature process of the TFT after the deposition of the nitride, the nitride will diffuse, which will contaminate the non-polysilicon material of the switching TFT
Implementation Method 2
removing the nitride layer not covered by the first gate electrode and the second gate electrode by dry etching with the self-alignment of the first gate electrode and the second gate electrode
Data Source
Figure 1
Figure 2A~2E
Figure 2F~2H
AI summary
A manufacturing method of a TFT panel, and TFT panel. The method comprises: providing a substrate (101); forming, on the substrate, a first active region, a first oxide layer, a nitride layer, and a first and second mutually independent gate sequentially (102, 103, 104); removing the nitride layer not covered by the first and second gate (105); depositing a second insulation layer (106); forming, on the second insulation layer above the second gate, a second active region having a different material than the material of the first active region (107); and forming a first and second source, and a first and second drain separately (108). The method improves the performance of a TFT panel.