Oxide Semiconductor Device with Heat Treatment for Stability
Solution Overview
Problem
Transistors using oxide semiconductors face reliability issues due to sensitivity to impurities and oxygen vacancies, leading to unstable electrical characteristics and low reliability.
Innovation Solution
A semiconductor device structure incorporating specific layers and materials, including a conductor, insulators, and oxides with controlled atomic ratios and crystallinity, along with heat treatment processes to minimize impurity diffusion and enhance oxygen supply, resulting in improved electrical characteristics and reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a transistor is formed using an oxide semiconductor as an active layer, then the transistor can be fabricated with oxide semiconductor materials, but the electrical characteristics are easily changed by impurities and oxygen vacancies leading to low reliability
Solution Approach 1:
Heat treatment is performed before forming the oxide semiconductor layer to preliminarily prepare the substrate and underlying layers, creating an environment that reduces impurity incorporation and oxygen vacancies during subsequent fabrication steps
Solution Approach 2:
The heat treatment process changes the temperature parameter of the substrate to an appropriate range (e.g., 400-700°C) to optimize the physical and chemical properties of the underlying layers, reducing their ability to generate impurities and oxygen vacancies that would harm the oxide semiconductor
2Reliability
If heat treatment is performed to enhance oxygen supply and minimize impurity diffusion, then electrical characteristics and reliability are improved, but additional process steps are required
Solution Approach 1:
Multiple functions are merged into a single heat treatment step: oxygen supply to the oxide semiconductor, impurity diffusion control, and substrate preparation are all achieved through one integrated thermal processing step rather than separate operations
Solution Approach 2:
The heat treatment process serves multiple purposes simultaneously: it acts as an oxygen source, controls impurity distribution, prepares the substrate surface, and stabilizes the underlying layers, making the process universally beneficial for oxide semiconductor fabrication
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 semiconductor device achieves stable electrical characteristics, high reliability, and enhanced data retention and writing speed, while allowing for miniaturization and integration, with reduced power consumption and increased design flexibility.
Implementation Method 1
heat treatment processes to minimize impurity diffusion and enhance oxygen supply
Data Source
AI summary
A semiconductor device includes a first conductor; a first insulator thereover; a first oxide thereover; a second oxide thereover; a second conductor and a third conductor that are separate from each other thereover; a third oxide over the first insulator, the second oxide, the second conductor, and the third conductor; a second insulator thereover; a fourth conductor thereover; and a third insulator over the first insulator, the second insulator, and the fourth conductor. The second oxide includes a region where the energy of the conduction band minimum of an energy band is low and a region where the energy of the conduction band minimum of the energy band is high. The energy of the conduction band minimum of the third oxide is higher than that of the region of the second oxide where the energy of the conduction band minimum is low. Side surfaces of the first oxide and the second oxide are covered with the third oxide.