Oxide TFT Dual-Channel Protective Layer Oxygen Barrier
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Solution Overview
Problem
Existing thin film transistors (TFTs) using oxide semiconductor layers face challenges with oxygen detachment during manufacturing, leading to lattice defects, increased leakage current, and decreased reliability, particularly due to insufficient heat resistance and hydrogen introduction, which complicates the process and affects transistor characteristics.
Innovation Solution
A thin film transistor structure is developed with a two-layer channel protective layer, where the first layer is made of an oxide insulating material and the second layer is a low oxygen permeable material, preventing oxygen detachment and functioning as a passivation film, simplifying the manufacturing process by forming the source/drain electrode after the channel protective layer, thus maintaining oxygen within the oxide semiconductor layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a channel protective layer and passivation film are formed to prevent oxygen detachment, then oxygen detachment is reduced, but the manufacturing process complexity increases due to additional photolithography steps
Solution Approach 1:
The patent combines the channel protective layer and passivation film into a single integrated structure. The channel protective layer is formed to protect the oxide semiconductor layer, and the passivation film is formed over it to prevent oxygen detachment. This merged structure eliminates the need for separate formation steps while maintaining both protective functions, thereby reducing manufacturing process complexity while preserving reliability.
Solution Approach 2:
The channel protective layer serves multiple functions: it protects the oxide semiconductor layer during manufacturing and acts as a barrier to oxygen detachment. The passivation film similarly provides both mechanical protection and oxygen barrier functionality. This multi-functionality reduces the need for additional specialized layers, simplifying the overall manufacturing process while maintaining effective oxygen prevention.
2Reliability
If multiple high temperature heat steps are performed to form protective films, then oxygen detachment is prevented, but the manufacturing time increases
Solution Approach 1:
The channel protective layer is formed preliminarily before the passivation film to establish initial protection against oxygen detachment. This preliminary action allows subsequent steps to proceed without compromising the oxide semiconductor layer, reducing the need for additional corrective heat treatment steps and thereby decreasing total manufacturing time while maintaining effective oxygen prevention.
Solution Approach 2:
The protective structure is formed continuously through sequential deposition of the channel protective layer and passivation film without interrupting the protective function. This continuous formation process ensures that oxygen prevention is maintained throughout manufacturing, eliminating the need for repeated heat treatment cycles and reducing overall manufacturing time.
3Reliability
If a passivation film with low oxygen permeability is formed, then oxygen detachment is prevented, but oxygen supply to the oxide semiconductor layer is restricted
Solution Approach 1:
The protective structure is segmented into two distinct layers: the channel protective layer in direct contact with the oxide semiconductor layer, and the passivation film on the outer side. This segmentation allows the inner layer to permit necessary oxygen interaction while the outer layer provides robust oxygen barrier protection, thereby maintaining both oxygen detachment prevention and adequate oxygen supply to the oxide semiconductor.
Solution Approach 2:
The channel protective layer acts as an intermediary between the oxide semiconductor layer and the passivation film. It mediates oxygen transport by allowing controlled oxygen interaction with the oxide semiconductor while the passivation film provides the primary oxygen barrier. This intermediary function ensures that oxygen supply needs are met while maintaining effective oxygen detachment prevention.
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 structure effectively inhibits oxygen detachment, reduces leakage current, and enhances the reliability of the TFTs with a simpler manufacturing process, maintaining favorable transistor characteristics by preventing oxygen loss and hydrogen introduction.
Implementation Method 1
a channel protective layer which includes a first channel protective layer on a lower layer side and a second channel protective layer on an upper layer side
Implementation Method 2
one or both of the first channel protective layer and the second channel protective layer is made of a low oxygen permeable material
Data Source
AI summary
A thin film transistor includes: a gate electrode; a gate insulting film formed on the gate electrode; an oxide semiconductor thin film layer forming a channel region corresponding to the gate electrode on the gate insulating film; a channel protective layer that is formed at least in a region corresponding to the channel region on the gate insulating film and the oxide semiconductor thin film layer, and that includes a first channel protective layer on a lower layer side and a second channel protective layer on an upper layer side; and a source/drain electrode that is formed on the channel protective layer and is electrically connected to the oxide semiconductor thin film layer. The first channel protective layer is made of an oxide insulating material, and one or both of the first channel protective layer and the second channel protective layer is made of a low oxygen permeable material.