Semiconductor Device With Insulating Island Barrier
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Solution Overview
Problem
Current semiconductor devices face challenges in achieving favorable electrical characteristics and miniaturization while maintaining high reliability, particularly due to issues with oxygen vacancies and impurity diffusion in oxide semiconductor transistors.
Innovation Solution
The semiconductor device incorporates an island-shaped semiconductor layer with a gate electrode and insulating layers, including a projecting portion in the insulating layer, and oxide layers containing metal elements, which reduces oxygen vacancies and enhances electrical characteristics by improving the channel formation region and preventing impurity entry.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If oxide semiconductor transistors are miniaturized to increase integration density, then productivity and device density improve, but electrical characteristics deteriorate due to increased oxygen vacancies and impurity diffusion
Solution Approach 1:
A barrier layer is introduced as an intermediary between the oxide semiconductor layer and the gate insulating layer. This barrier layer prevents oxygen vacancies and impurities from diffusing into the oxide semiconductor layer during heat treatment, thereby maintaining electrical characteristics while enabling device miniaturization and high-density integration
Solution Approach 2:
The barrier layer is formed in advance before the gate insulating layer, creating a protective interface that prevents oxygen vacancy generation and impurity diffusion during subsequent heat treatment processes. This preliminary protective action ensures electrical characteristics are maintained even as devices are miniaturized
2Reliability
If heat treatment is performed to reduce oxygen vacancies in oxide semiconductor layers, then electrical characteristics improve, but impurity diffusion increases causing reliability degradation
Solution Approach 1:
The barrier layer serves as a mediator that allows beneficial oxygen vacancy reduction through heat treatment while blocking harmful impurity diffusion. The barrier layer is positioned between the oxide semiconductor layer and external environment, enabling selective permeability during thermal processing
3Ease of manufacture
If conventional transistor structures are used without barrier layers, then manufacturing simplicity is maintained, but oxygen vacancies and impurity diffusion cause poor electrical characteristics
Solution Approach 1:
The barrier layer is introduced as a thin intermediary film that can be integrated into existing manufacturing processes. Although it adds a layer, the barrier layer uses standard materials and formation techniques, minimizing manufacturing complexity while dramatically improving electrical characteristics by preventing oxygen vacancies and impurity diffusion
Data Source
AI summary
To give favorable electrical characteristics to a semiconductor device. The semiconductor device includes an insulating layer, a semiconductor layer over the insulating layer, a pair of electrodes over the semiconductor layer and each electrically connected to the semiconductor layer, a gate electrode over the semiconductor layer, and a gate insulating layer between the semiconductor layer and the gate electrode. The insulating layer includes an island-shaped projecting portion. A top surface of the projecting portion of the insulating layer is in contact with a bottom surface of the semiconductor layer, and is positioned on an inner side of the semiconductor layer when seen from above. The pair of electrodes covers part of a top surface and part of side surfaces of the semiconductor layer. Furthermore, the gate electrode and the gate insulating layer cover side surfaces of the projecting portion of the insulating layer.