Inverted Staggered Oxide Semiconductor Transistor for Display Signal Delay
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Solution Overview
Problem
Inverted staggered transistors with oxide semiconductor films face challenges in high-resolution display devices due to signal delay from parasitic capacitance and oxygen vacancies affecting electrical characteristics, leading to degraded image quality and reliability.
Innovation Solution
A staggered transistor structure with a stacked-layer channel region and higher carrier density oxide semiconductor films, including layers with specific atomic proportions of In, Ga, and Zn, to reduce contact resistance and oxygen vacancies, and the use of nitrogen and hydrogen in insulating films to enhance carrier density and reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If an inverted staggered transistor structure is used, then the manufacturing process is simple and manufacturing cost is low, but signal delay due to parasitic capacitance becomes severe and image quality degrades
Solution Approach 1:
The patent inverts the conventional transistor structure by placing the gate electrode at the bottom instead of at the top, creating an inverted staggered structure. This inversion reduces parasitic capacitance between the gate and source/drain electrodes, thereby reducing signal delay while maintaining manufacturing simplicity
Solution Approach 2:
The patent introduces a stacked-layer channel region structure with multiple oxide semiconductor layers having different atomic proportions. This dimensional change in the channel structure reduces parasitic capacitance and improves electrical characteristics, resolving the signal delay issue while keeping the manufacturing process straightforward
2Measurement precision
If the screen size or resolution of display device is increased, then display capability is improved, but signal delay due to parasitic capacitance becomes more severe
Solution Approach 1:
The patent applies local quality by creating oxide semiconductor layers with different atomic proportions at different locations within the channel region. The first oxide semiconductor layer has a first atomic proportion and the second layer has a second atomic proportion, optimizing electrical characteristics locally to reduce parasitic capacitance effects in high-resolution displays
Solution Approach 2:
The patent uses composite oxide semiconductor materials with different compositions (different atomic proportions of In, Ga, Zn, and oxygen) stacked together to form the channel region. This composite structure reduces parasitic capacitance and enables high-resolution display performance
3Ease of manufacture
If oxygen vacancies are present in oxide semiconductor layer, then manufacturing is easier, but electrical characteristics change and reliability decreases
Solution Approach 1:
The patent changes the atomic proportion parameters of oxide semiconductors in the stacked layers, specifically controlling the ratios of In, Ga, Zn, and oxygen. By optimizing these parameters, the patent reduces oxygen vacancies and stabilizes electrical characteristics while maintaining ease of manufacture
Solution Approach 2:
The patent employs composite oxide semiconductor materials where the first oxide semiconductor layer and second oxide semiconductor layer have different compositions. This composite approach allows each layer to compensate for oxygen vacancies, improving electrical characteristics stability without complicating the manufacturing process
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 solution improves the reliability and electrical characteristics of transistors by reducing oxygen vacancies and parasitic capacitance, achieving high on-state current and low off-state current, and enabling low power consumption in display devices.
Implementation Method 1
an insulating layer that releases oxygen by heating to reduce oxygen vacancies in the oxide semiconductor layer
Data Source
AI summary
The reliability of a transistor including an oxide semiconductor is improved. The transistor in a semiconductor device includes a first oxide semiconductor film over a first insulating film, a gate insulating film over the first oxide semiconductor film, a second oxide semiconductor film over the gate insulating film, and a second insulating film over the first oxide semiconductor film and the second oxide semiconductor film. The first oxide semiconductor film includes a channel region overlapping with the second oxide semiconductor film, a source region and a drain region each in contact with the second insulating film. The channel region includes a first layer and a second layer in contact with a top surface of the first layer and covering a side surface of the first layer in the channel width direction. The second oxide semiconductor film has a higher carrier density than the first oxide semiconductor film.