Oxide Semiconductor Transistor Layer Structure for High On-State Current
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Solution Overview
Problem
Existing semiconductor devices face challenges in achieving high on-state current, high frequency characteristics, reliability, scalability, favorable electrical characteristics, and high productivity.
Innovation Solution
A semiconductor device with a transistor structure that includes a stacked-layer structure of oxides and conductors, where the third oxide has a higher crystallinity than the first oxide, and the atomic ratio of In to the element M in the second layer is lower than in the first layer, enhancing the channel formation region with improved oxygen supply and impurity inhibition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If oxide semiconductor transistors are used, then off-state current is reduced, but on-state current is insufficient
Solution Approach 1:
The patent applies local quality by creating a multi-layer oxide semiconductor structure where different layers have different compositions and functions. The first oxide layer (In-Ga-Zn-O) provides low off-state current, while the second oxide layer (In-Al-Zn-O with lower In content) enhances on-state current. This local differentiation of material properties within the semiconductor layer resolves the contradiction between low off-state current and high on-state current.
Solution Approach 2:
The patent uses composite materials by combining multiple oxide semiconductor layers with different compositions. The first layer contains In-Ga-Zn-O and the second layer contains In-Al-Zn-O with specific atomic ratios. This composite structure leverages the advantageous properties of each material combination to simultaneously achieve low off-state current and high on-state current.
2Reliability
If oxide semiconductor transistors are used, then transistor characteristics are improved, but manufacturing complexity increases
Solution Approach 1:
The patent applies parameter changes by systematically varying the atomic ratios of metal elements (In, Ga, Al, Zn) between layers and controlling oxygen content through specific heat treatment parameters. By optimizing these compositional and thermal parameters, the patent achieves improved transistor characteristics while maintaining manufacturability through controlled variation rather than structural complexity.
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 semiconductor device achieves high on-state current, improved frequency characteristics, increased reliability, and enhanced scalability, while maintaining favorable electrical characteristics and high productivity.
Implementation Method 1
the oxide in contact with the gate electrode supplies oxygen to the channel formation region
Implementation Method 2
a crystalline oxide semiconductor layer which is not a single crystal
Data Source
AI summary
A semiconductor device includes a transistor including, a first to fifth insulator, a first to third oxide, a first to third conductor. An opening reaching the second oxide is provided in the fourth insulator and the fifth insulator. The third oxide, the third insulator, and the third conductor are arranged sequentially from the inner wall side of the opening so as to fill the opening. In the channel length direction of the transistor, at least part of the fourth insulator in a region where the fourth insulator and the second oxide do not overlap with each other is in contact with the first insulator. In the channel width direction of the transistor, at least part of the third oxide in a region where the third oxide and the second oxide do not overlap with each other is in contact with the first insulator.