Oxide Semiconductor Contact Hole Protection in Display Devices
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Solution Overview
Problem
The integration of thin film transistors with polycrystalline semiconductor and oxide semiconductor layers on the same substrate is hindered by the deterioration of oxide semiconductor layers due to hydrofluoric acid cleaning processes, which affects the electrical characteristics and reliability of the display device.
Innovation Solution
The use of relay electrodes formed between the oxide semiconductor layer and the insulating substrate, with contact holes designed to avoid direct exposure of the oxide semiconductor layer to hydrofluoric acid, allowing for simultaneous formation of contact holes for both semiconductor layers and reducing processing steps and manufacturing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a cleaning process using hydrofluoric acid is carried out to remove oxide film from polycrystalline semiconductor layer, then the electrical characteristics of polycrystalline transistor are improved, but the oxide semiconductor layer is at least partially vanished and electrical characteristics are deteriorated
Solution Approach 1:
The patent divides the contact holes into two separate types: first contact holes for connecting the polycrystalline semiconductor layer, and second contact holes for connecting the oxide semiconductor layer. This segmentation allows different cleaning processes to be applied to each contact hole type, enabling the polycrystalline semiconductor to receive hydrofluoric acid cleaning while protecting the oxide semiconductor layer from damage
Solution Approach 2:
The patent applies different treatments to different regions: the first contact holes undergo hydrofluoric acid cleaning to remove oxide films from the polycrystalline semiconductor layer, while the second contact holes are specifically designed to avoid hydrofluoric acid exposure to protect the oxide semiconductor layer. This local differentiation of treatment quality resolves the contradiction between cleaning needs and material protection
2Reliability
If separate processing steps are used for polycrystalline and oxide semiconductor contact holes, then electrical characteristics are maintained, but the number of processing steps increases and manufacturing cost increases
Solution Approach 1:
The patent merges the formation of first and second contact holes into a single simultaneous processing step. By designing the contact hole formation process to create both types of contact holes together, the patent maintains the reliability benefits of differentiated treatment while achieving the productivity benefit of reduced processing steps and lower manufacturing costs
Data Source
AI summary
According to one embodiment, a display device includes an insulating substrate, a first transistor including a first semiconductor layer of silicon and a first electrode, a first insulating layer provided above the first semiconductor layer, a second transistor including a second semiconductor layer of an oxide semiconductor, a second electrode and a conductive layer electrically connected to the second semiconductor layer, and a second insulating layer provided above the first insulating layer and the second semiconductor layer, the first electrode being electrically connected to the first semiconductor layer in a first hole, and the second electrode being in contact with the conductive layer in a second hole.