Oxide Semiconductor TFT Metal Layer Protection
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Solution Overview
Problem
Hydrofluoric-acid rinsing during the manufacturing of organic EL display devices erodes oxide semiconductor films, leading to manufacturing defects such as deficiency and breaks in the oxide semiconductor pattern.
Innovation Solution
A display device structure where a metal layer is provided to cover the exposed surface of the oxide semiconductor layer within contact holes, preventing direct contact with the hydrofluoric-acid rinsing solution, and a method of manufacturing involving the formation of a metal layer before terminal electrode formation to protect the oxide semiconductor layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If hydrofluoric-acid rinsing is performed to remove surface oxide film from polysilicon semiconductor, then contact resistance is reduced, but oxide semiconductor film is eroded causing manufacturing defects
Solution Approach 1:
The patent divides the semiconductor structure into two separate types: polysilicon-based TFTs and oxide semiconductor-based TFTs, each processed independently. This segmentation allows the polysilicon TFTs to receive hydrofluoric-acid rinsing for oxide removal while the oxide semiconductor TFTs are protected from this harmful process, thus resolving the contradiction between reducing contact resistance and preventing pattern erosion.
Solution Approach 2:
The patent introduces a protective inorganic insulating film as an intermediary layer between the oxide semiconductor and the hydrofluoric-acid rinsing solution. This mediator prevents direct contact between the acid and the oxide semiconductor, allowing the rinsing process to proceed for polysilicon contact resistance reduction without eroding the oxide semiconductor pattern.
2Reliability
If contact holes are formed by dry etching to reach oxide semiconductor layer, then electrical connection is established, but oxide semiconductor pattern breaks occur
Solution Approach 1:
The patent performs preliminary protective actions by forming the inorganic insulating film over the oxide semiconductor layer before contact hole formation. This preliminary protection ensures that subsequent dry etching and hydrofluoric-acid rinsing processes do not cause pattern breaks, while still allowing electrical connection to be established through the contact holes.
Solution Approach 2:
The patent provides beforehand cushioning by introducing a buffer layer between the oxide semiconductor and the contact hole structure. This cushioning layer absorbs the mechanical and chemical stress from contact hole formation and subsequent rinsing, preventing pattern breaks while maintaining electrical connectivity.
3Ease of manufacture
If hydrofluoric-acid rinsing solution contacts oxide semiconductor film, then oxide semiconductor is eroded, but manufacturing defects such as deficiency and breaks occur
Solution Approach 1:
The patent introduces a protective inorganic insulating film as an intermediary barrier that prevents direct contact between the hydrofluoric-acid rinsing solution and the oxide semiconductor film. This mediator allows the rinsing process to be performed for manufacturing purposes while protecting the oxide semiconductor from erosion, thus maintaining pattern quality.
Solution Approach 2:
The patent extracts the harmful effect of hydrofluoric acid from the oxide semiconductor processing by applying it selectively only to polysilicon regions while protecting oxide semiconductor regions. This extraction allows the manufacturing process to proceed while eliminating the erosive effect on oxide semiconductor patterns.
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 effectively prevents erosion of the oxide semiconductor layer during hydrofluoric-acid rinsing, reducing manufacturing defects and ensuring reliable electrical connections in oxide semiconductor-based TFTs.
Implementation Method 1
a metal layer is provided covering an exposed surface of the second semiconductor layer exposed inside the contact hole
Implementation Method 2
The hydrofluoric-acid rinsing solution erodes the oxide semiconductor film
Data Source
AI summary
A second TFT includes: a second semiconductor layer of an oxide semiconductor; a second interlayer insulating film covering the second semiconductor layer; a terminal electrode; and a contact hole exposing at least a part of the second semiconductor layer. A metal layer is provided covering an exposed surface of the second semiconductor layer exposed inside the contact hole. The terminal electrode is electrically connected to the second semiconductor layer via the contact hole and the metal layer.