Stacked Oxide Semiconductor Transistors With Oxygen Diffusion Barriers
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Solution Overview
Problem
Current semiconductor devices face challenges in achieving high integration, low power consumption, and reliable electrical characteristics due to issues with scaling down and maintaining stable oxygen levels in oxide semiconductors during heat treatment processes.
Innovation Solution
A semiconductor device structure is developed with multiple oxide layers and insulators that inhibit oxygen diffusion, ensuring stable oxygen supply to the oxide semiconductor layers, even during heat treatment, using CAAC-OS with c-axis aligned crystallinity and excess oxygen-containing insulators to prevent oxygen vacancies and enhance reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If oxide semiconductor layers are used in transistors to achieve low power consumption, then off-state current is reduced, but oxygen vacancies form during heat treatment leading to unstable electrical characteristics
Solution Approach 1:
An oxygen barrier layer is introduced as an intermediary between the oxide semiconductor layer and the external environment. This barrier layer prevents oxygen diffusion and oxygen vacancy formation during heat treatment, thereby maintaining stable electrical characteristics while preserving the low power consumption benefits of oxide semiconductor transistors
Solution Approach 2:
The oxygen barrier layer is formed in advance before heat treatment processes. This preliminary protective structure ensures that oxygen vacancies do not form during subsequent heating steps, preventing degradation of electrical characteristics before they can occur
2Productivity
If transistor size is scaled down to achieve high integration, then device density increases, but maintaining stable oxygen levels becomes more difficult
Solution Approach 1:
The oxygen barrier layer serves as a protective intermediary that becomes increasingly critical as transistor dimensions shrink. In scaled-down devices, the barrier layer's oxygen-blocking function is essential for maintaining stable oxygen levels in the oxide semiconductor, enabling high integration without sacrificing reliability
3Manufacturing precision
If heat treatment is applied to oxide semiconductors to improve crystallinity, then electrical characteristics improve, but oxygen diffusion causes oxygen vacancies
Solution Approach 1:
The oxygen barrier layer acts as a protective intermediary during heat treatment, allowing the oxide semiconductor to achieve improved crystallinity through controlled heating while preventing oxygen diffusion that would otherwise create oxygen vacancies and degrade electrical characteristics
Solution Approach 2:
The oxygen barrier layer enables modification of thermal processing parameters (temperature, duration) to optimize crystallinity without the harmful side effect of oxygen loss. The barrier layer decouples the beneficial thermal effects from the harmful oxygen diffusion
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 enables the creation of highly integrated, low-power semiconductor devices with improved electrical characteristics and reliability by maintaining stable oxygen levels and reducing oxygen vacancies, leading to enhanced on-state current, frequency performance, and reduced off-state current.
Implementation Method 1
insulators that inhibit oxygen diffusion, ensuring stable oxygen supply to the oxide semiconductor layers
Implementation Method 2
using CAAC-OS with c-axis aligned crystallinity and excess oxygen-containing insulators to prevent oxygen vacancies
Data Source
AI summary
A semiconductor device that can be scaled down or highly integrated is provided. The semiconductor device includes a first layer and a second layer over the first layer. The first layer and the second layer each include a transistor. The transistor in the first layer and the transistor in the second layer each include a first oxide, a first conductor and a second conductor over the first oxide, a first insulator placed to cover the first conductor, the second conductor, and the first oxide, a second insulator over the first insulator, a second oxide placed between the first conductor and the second conductor over the first oxide, a third insulator over the second oxide, a third conductor over the third insulator, and a fourth insulator in contact with a top surface of the second insulator, a top surface of the second oxide, a top surface of the third insulator, and a top surface of the third conductor. The first insulator and the fourth insulator are less likely than the second insulator to allow oxygen to pass through.