Oxide Semiconductor Gate Stack for Oxygen Vacancy Repair
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Solution Overview
Problem
Existing semiconductor devices using oxide semiconductors for channels face challenges in supplying sufficient oxygen to the layer while minimizing defects, leading to unstable operation and variations in characteristics due to oxygen vacancies, particularly when high indium content is used.
Innovation Solution
A manufacturing method involving the formation of a first metal oxide layer, an oxide semiconductor layer, a gate insulating layer, and a second metal oxide layer, followed by a heat treatment and removal of the second layer, which helps in supplying oxygen to the oxide semiconductor layer while minimizing defects by using aluminum oxide layers to block hydrogen and oxygen diffusion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an insulating layer with more oxygen is used to supply oxygen to the oxide semiconductor layer, then oxygen vacancies in the oxide semiconductor layer are reduced, but the insulating layer contains more defects causing electron-trapping and variation in characteristics
Solution Approach 1:
The insulating layer is divided into two distinct layers: a first insulating layer formed with fewer defects (lower oxygen content) and a second insulating layer formed with more oxygen. This segmentation allows each layer to fulfill different functions - the first layer provides structural integrity with fewer defects, while the second layer supplies oxygen to reduce vacancies in the oxide semiconductor layer, thereby resolving the contradiction between reliability and manufacturing precision.
Solution Approach 2:
Different regions of the insulating structure are assigned different oxygen contents and defect densities. The first insulating layer has lower oxygen content and fewer defects, while the second insulating layer has higher oxygen content. This local differentiation enables the system to simultaneously achieve low defect density in critical regions and high oxygen supply in regions adjacent to the oxide semiconductor layer.
2Speed
If the ratio of indium in the oxide semiconductor layer is increased to achieve high mobility, then mobility is improved, but oxygen vacancies are more likely to be formed
Solution Approach 1:
The second insulating layer is formed with high oxygen content before the oxide semiconductor layer is fully operational, creating a reservoir of oxygen that can diffuse into the oxide semiconductor layer during subsequent heat treatment. This preliminary oxygen supply prevents oxygen vacancies from forming in the high-indium oxide semiconductor layer, thereby maintaining both high mobility and operational stability.
Solution Approach 2:
The second insulating layer acts as an intermediary oxygen source between the external environment and the oxide semiconductor layer. It provides a controlled oxygen supply to the high-indium oxide semiconductor layer, preventing oxygen vacancy formation while allowing the high indium content necessary for achieving high mobility.
3Device complexity
If a single insulating layer is used to cover the oxide semiconductor layer, then the structure is simple, but it cannot simultaneously reduce defects and supply sufficient oxygen
Solution Approach 1:
The insulating layer is segmented into two functional layers with different oxygen contents and defect densities. The first insulating layer provides a low-defect foundation, while the second insulating layer provides oxygen supply capability. This segmentation resolves the contradiction by distributing different functions across multiple layers rather than attempting to achieve both functions in a single layer.
Solution Approach 2:
The two-layer insulating structure provides multi-functionality: the first layer provides structural stability and low defect density, while the second layer provides oxygen supply. Together, they create a comprehensive insulating system that addresses multiple requirements simultaneously, overcoming the limitations of a single-layer design.
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 method enables the production of a highly reliable semiconductor device with high mobility by uniformly repairing oxygen vacancies and reducing defects, thereby improving both initial characteristics and reliability test results.
Implementation Method 1
aluminum oxide layers to block hydrogen and oxygen diffusion
Implementation Method 2
performing a heat treatment in a state where the second metal oxide layer is formed above the gate insulating layer
Data Source
AI summary
A method for manufacturing semiconductor device according to an embodiment includes: forming a first metal oxide layer containing aluminum as a main component above a substrate; forming an oxide semiconductor layer above the first metal oxide layer; forming a gate insulating layer above the oxide semiconductor layer; forming a second metal oxide layer containing aluminum as a main component above the gate insulating layer; performing a heat treatment in a state where the second metal oxide layer is formed above the gate insulating layer; removing the second metal oxide layer after the heat treatment; and forming a gate electrode above the gate insulating layer.