Oxide Semiconductor Device Oxygen Vacancy Stabilization
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Solution Overview
Problem
Semiconductor devices using oxide semiconductors face issues with oxygen vacancies and impurities like hydrogen, silicon, and carbon, which lead to unstable electrical characteristics, such as increased leakage current and shifted threshold voltage.
Innovation Solution
A semiconductor device structure is implemented where oxygen is supplied from base and gate insulating layers to fill oxygen vacancies, and oxide layers with specific metal elements are used to reduce impurities, forming a protective barrier to maintain stable electrical characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If oxygen is supplied from base and gate insulating layers to fill oxygen vacancies, then electrical characteristics stability is improved, but device structure complexity increases
Solution Approach 1:
The insulating layer is segmented into a base insulating layer and a gate insulating layer, with the base insulating layer positioned to supply oxygen to the oxide semiconductor layer. This segmentation allows targeted oxygen supply to fill vacancies without requiring complete restructuring of the entire device.
Solution Approach 2:
The base insulating layer is pre-configured with oxygen-rich materials (such as silicon oxide or silicon oxynitride) before device operation. This preliminary oxygen reservoir enables passive, continuous oxygen supply to the oxide semiconductor layer during normal device operation, stabilizing electrical characteristics without active control mechanisms.
2Manufacturing precision
If oxide layers with specific metal elements are used to reduce impurities, then purity of oxide semiconductor layer is improved, but manufacturing process complexity increases
Solution Approach 1:
Oxide layers containing specific metal elements (such as aluminum, gallium, or indium) are strategically positioned adjacent to the oxide semiconductor layer. These oxide layers locally provide oxygen and suppress impurity diffusion only where needed, maintaining high purity in the semiconductor layer without requiring purification throughout the entire structure.
Solution Approach 2:
The oxide layers act as intermediary barrier layers between the oxide semiconductor layer and surrounding materials. These intermediary layers prevent impurity diffusion from source regions while maintaining oxygen supply, effectively purifying the semiconductor layer through controlled material placement rather than complex purification processes.
3Reliability
If protective insulating layer with low hydrogen content is formed over gate electrode layer, then oxygen vacancies are filled and electrical characteristics are stabilized, but device structure complexity increases
Solution Approach 1:
A protective insulating layer with low hydrogen content (such as silicon nitride or silicon oxynitride) is formed over the gate electrode layer to create an inert, oxygen-rich environment. This layer prevents hydrogen contamination and oxygen loss from the oxide semiconductor layer, stabilizing electrical characteristics through passive environmental control.
Solution Approach 2:
The protective insulating layer is formed in advance during the manufacturing process to preemptively protect the oxide semiconductor layer from hydrogen contamination and oxygen loss. This beforehand cushioning prevents future degradation of electrical characteristics without requiring corrective measures during device operation.
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 structure achieves stable and reliable electrical characteristics by reducing oxygen vacancies and impurity concentrations, resulting in improved carrier mobility and reduced threshold voltage fluctuations.
Implementation Method 1
oxygen is supplied from a base insulating layer provided below an oxide semiconductor layer and a gate insulating layer provided over the oxide semiconductor layer to a region where a channel is formed, whereby oxygen vacancies which might be generated in the channel are filled
Implementation Method 2
a protective insulating layer serving as a barrier layer having a low hydrogen content and a low oxygen-transmitting property over a gate electrode layer is formed, so that oxygen is effectively supplied to the region where a channel is formed while desorption of oxygen from the gate insulating layer and/or the base insulating layer is suppressed
Data Source
AI summary
To provide a highly reliable semiconductor device including an oxide semiconductor by suppression of change in its electrical characteristics. Oxygen is supplied from a base insulating layer provided below an oxide semiconductor layer and a gate insulating layer provided over the oxide semiconductor layer to a region where a channel is formed, whereby oxygen vacancies which might be generated in the channel are filled. Further, extraction of oxygen from the oxide semiconductor layer by a source electrode layer or a drain electrode layer in the vicinity of the channel formed in the oxide semiconductor layer is suppressed, whereby oxygen vacancies which might be generated in a channel are suppressed.