Oxide Semiconductor Edge Curvature for Oxygen Vacancy Control
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Solution Overview
Problem
The generation of oxygen vacancies at the side surfaces of oxide semiconductor layers in semiconductor devices leads to increased threshold-voltage variation, unintended current flow, and deterioration of electrical characteristics, resulting in unreliable and power-consuming devices with potential shape defects.
Innovation Solution
A semiconductor device with an oxide semiconductor layer wrapped in a multilayer film having a curvature, where the oxide layer has a higher energy gap and a higher proportion of elements like indium, zinc, and gallium, which strongly bond with oxygen, reducing the likelihood of oxygen vacancy formation and ensuring stable electrical characteristics. This structure includes a base insulating film with stepped regions for improved step coverage and reduced impurity entry.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an oxide semiconductor layer is used for channel formation, then the device can achieve low power consumption and high speed operation, but oxygen vacancies are generated at side surfaces during manufacturing, causing threshold voltage variation and increased off-state current
Solution Approach 1:
An oxide layer is introduced as an intermediary between the oxide semiconductor layer and the environment. This oxide layer contains elements like aluminum, gallium, or zinc that strongly bond with oxygen, acting as a barrier to prevent oxygen vacancy formation at the side surfaces of the oxide semiconductor layer during manufacturing processes.
Solution Approach 2:
The oxide layer is formed in advance before the oxide semiconductor layer is fully processed. By pre-establishing this protective oxide layer with high oxygen affinity elements, the system preemptively counteracts the harmful oxygen vacancy formation that would otherwise occur during subsequent manufacturing steps.
2Ease of manufacture
If the oxide semiconductor layer is exposed at the edges, then the manufacturing process is simpler, but the resistance of the side surface is reduced and unintended current flows between source and drain
Solution Approach 1:
The oxide layer serves as a mediator that covers the exposed edges of the oxide semiconductor layer. This intermediary structure prevents direct exposure of the semiconductor edges to the environment, thereby maintaining side surface resistance and preventing unintended current flow while still allowing for relatively simple manufacturing processes.
3Device complexity
If a flat multilayer film structure is used, then the device structure is simpler, but films may not form evenly and regions with low film density or no film formation occur
Solution Approach 1:
The multilayer film structure incorporates curved surfaces instead of purely flat surfaces. This curvature design improves film formation uniformity by ensuring that subsequent films can deposit evenly across the entire surface, eliminating regions with low film density or complete film absence that occur with flat structures.
4Ease of manufacture
If regions with low film density or no film formation occur, then the device structure is easier to manufacture, but impurity elements enter the multilayer film and deteriorate device characteristics
Solution Approach 1:
The oxide layer acts as an intermediary protective barrier that seals the multilayer film structure. This intermediary layer prevents impurity elements from entering regions that might otherwise have low film density or no film formation, thereby protecting the device characteristics while still allowing for easier manufacturing processes.
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 effectively reduces electrical characteristic variation, enhances the reliability and stability of the semiconductor device, and prevents shape defects by minimizing oxygen vacancy formation and impurity entry, resulting in a semiconductor device with improved productivity and yield.
Implementation Method 1
the oxide layer has a higher energy gap than the oxide semiconductor layer, and the oxide semiconductor layer has a higher proportion of indium... Any of these elements strongly bonds to oxygen and high energy is needed for forming an oxygen vacancy
Data Source
AI summary
A semiconductor device formed using an oxide semiconductor layer and having small electrical characteristic variation is provided. A highly reliable semiconductor device including an oxide semiconductor layer and exhibiting stable electric characteristics is provided. Further, a method for manufacturing the semiconductor device is provided. In the semiconductor device, an oxide semiconductor layer is used for a channel formation region, a multilayer film which includes an oxide layer in which the oxide semiconductor layer is wrapped is provided, and an edge of the multilayer film has a curvature in a cross section.