Oxide Semiconductor Memory Stack for Hydrogen and Oxygen Vacancy Control
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Solution Overview
Problem
Current semiconductor devices face challenges in achieving favorable electrical characteristics, such as normally-off operation, high on-state current, and low power consumption, while also requiring high reliability and miniaturization, due to issues with impurity diffusion and oxygen vacancies in oxide semiconductor transistors.
Innovation Solution
The semiconductor device incorporates an oxide semiconductor with a stacked-layer structure of insulators, including excess oxygen and hydrogen-trapping layers, such as aluminum oxide and silicon nitride, to control impurity diffusion and oxygen vacancies, ensuring a highly purified intrinsic state and improved electrical performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If oxide semiconductor transistors are used to achieve low leakage current and low power consumption, then power consumption is reduced, but impurity diffusion and oxygen vacancies degrade electrical characteristics
Solution Approach 1:
A silicon nitride layer is introduced as an intermediary barrier between the oxide semiconductor and surrounding structures. This layer mediates by blocking hydrogen diffusion into the oxide semiconductor while also preventing oxygen escape, thereby maintaining the low leakage current characteristic essential for low power consumption while ensuring electrical stability
Solution Approach 2:
The patent employs a composite structure combining silicon nitride and aluminum oxide layers. The silicon nitride provides hydrogen blocking while the aluminum oxide contributes additional barrier properties and structural stability. This composite approach addresses multiple degradation mechanisms simultaneously, maintaining both low power consumption and reliable electrical characteristics
2Volume of moving object
If miniaturization is pursued to increase integration density, then device size is reduced, but impurity diffusion becomes more severe
Solution Approach 1:
The silicon nitride layer serves as a diffusion barrier intermediary that becomes increasingly critical as device dimensions shrink. In miniaturized devices, the relative impact of impurity diffusion from surrounding structures is magnified, and the silicon nitride layer provides essential protection against hydrogen and other impurity ingress, enabling high-density integration without sacrificing device reliability
Solution Approach 2:
The patent applies the silicon nitride barrier layer specifically at critical interfaces where impurity diffusion is most problematic, such as between the oxide semiconductor and metal electrodes or surrounding dielectric structures. This localized application of barrier material provides targeted protection against impurity diffusion while maintaining overall device miniaturization
3Reliability
If hydrogen is removed from oxide semiconductor to achieve normally-off characteristics, then electrical characteristics improve, but hydrogen removal process complexity increases
Solution Approach 1:
The silicon nitride layer is formed prior to subsequent processing steps that might introduce hydrogen. By establishing the barrier layer in advance, the patent prevents hydrogen ingress during manufacturing processes such as sputtering, CVD, or plasma treatments, thereby achieving normally-off characteristics without requiring complex post-processing hydrogen removal steps
Solution Approach 2:
The patent converts the potential harm of hydrogen introduction during manufacturing into a benefit by using the silicon nitride layer to trap or reflect hydrogen away from the oxide semiconductor. The layer that might otherwise be seen as adding process complexity actually simplifies the overall approach to achieving normally-off characteristics by preventing the problem at its source rather than requiring complex remediation
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 configuration enables semiconductor devices with stable electrical characteristics, high on-state current, low power consumption, and enhanced reliability, facilitating miniaturization and integration while maintaining low impurity concentrations and oxygen vacancies.
Implementation Method 1
Hydrogen in the oxide semiconductor is bonded to the excess oxygen. The hydrogen bonded to the excess oxygen passes through the first insulator and is trapped or fixed in the second insulator.
Implementation Method 2
The hydrogen bonded to the excess oxygen passes through the first insulator and is trapped or fixed in the second insulator.
Data Source
AI summary
A semiconductor device having favorable electrical characteristics is provided. The semiconductor device includes an oxide semiconductor, a first insulator in contact with the oxide semiconductor, and a second insulator in contact with the first insulator. The first insulator includes excess oxygen. The second insulator has a function of trapping or fixing hydrogen. Hydrogen in the oxide semiconductor is bonded to the excess oxygen. The hydrogen bonded to the excess oxygen passes through the first insulator and is trapped or fixed in the second insulator. The excess oxygen bonded to the hydrogen remains in the first insulator as the excess oxygen.