Oxide Semiconductor Driver Circuit for Threshold Voltage Stability
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing display devices using transistors with oxide semiconductor layers face challenges in achieving favorable electric characteristics and high reliability, particularly in terms of threshold voltage stability over long-term use.
Innovation Solution
A display device is designed with a transistor that includes an oxide semiconductor layer, where the oxide semiconductor layer undergoes heat treatment for dehydration or dehydrogenation, followed by the formation of a protective insulating layer using an inorganic material containing oxygen. This process helps in stabilizing the carrier concentration and improving the reliability of the transistor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If heat treatment for dehydration or dehydrogenation is applied to the oxide semiconductor layer, then carrier concentration stability is improved, but manufacturing process complexity increases
Solution Approach 1:
Heat treatment for dehydration or dehydrogenation is performed on the oxide semiconductor layer before forming the protective insulating layer. This preliminary action removes water and hydrogen from the oxide semiconductor layer in advance, stabilizing the carrier concentration and threshold voltage before the transistor is put into operation, thereby improving reliability without requiring complex post-manufacturing adjustments
Solution Approach 2:
The heat treatment process changes the physical and chemical parameters of the oxide semiconductor layer by removing water and hydrogen, which directly affects the carrier concentration. This parameter change stabilizes the electrical characteristics of the transistor, particularly the threshold voltage, making it more reliable over time
2Stability of the object's composition
If a protective insulating layer containing oxygen is formed after heat treatment, then oxide semiconductor layer stability is improved, but manufacturing steps increase
Solution Approach 1:
A protective insulating layer containing oxygen is formed over the oxide semiconductor layer after heat treatment. This protective layer acts as a barrier that prevents water and hydrogen from entering the oxide semiconductor layer during subsequent manufacturing steps and operation, maintaining the stability of the oxide semiconductor layer's composition and electrical characteristics
Solution Approach 2:
The protective insulating layer serves as an intermediary between the oxide semiconductor layer and the external environment. It mediates the interaction by blocking harmful substances (water and hydrogen) from reaching the oxide semiconductor layer, thereby protecting its stability without requiring direct intervention in the oxide semiconductor layer itself
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
The proposed solution enables the manufacture of transistors with improved electric characteristics, including stable threshold voltage over time, which enhances the reliability of the display device, especially in the driver circuit portion.
Implementation Method 1
the oxide semiconductor layer is subjected to heat treatment for dehydration or dehydrogenation
Implementation Method 2
a protective insulating layer is formed using an insulating inorganic material containing oxygen so as to cover the oxide semiconductor layer
Data Source
AI summary
An object is to provide a display device which operates stably with use of a transistor having stable electric characteristics. In manufacture of a display device using transistors in which an oxide semiconductor layer is used for a channel formation region, a gate electrode is further provided over at least a transistor which is applied to a driver circuit. In manufacture of a transistor in which an oxide semiconductor layer is used for a channel formation region, the oxide semiconductor layer is subjected to heat treatment so as to be dehydrated or dehydrogenated; thus, impurities such as moisture existing in an interface between the oxide semiconductor layer and the gate insulating layer provided below and in contact with the oxide semiconductor layer and an interface between the oxide semiconductor layer and a protective insulating layer provided on and in contact with the oxide semiconductor layer can be reduced.