Oxide Semiconductor Insulator Stack for Oxygen Vacancy Control
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Solution Overview
Problem
Current semiconductor devices face challenges in achieving high on-state current, favorable S-value, high frequency characteristics, reliability, miniaturization, and low power consumption, particularly in oxide semiconductor transistors with In—Ga—Zn oxide (IGZO) materials, where maintaining low off-state current and stable electrical characteristics is difficult due to oxygen vacancies and impurity effects.
Innovation Solution
A semiconductor device structure is developed with a specific insulator configuration, including a thinner third insulator with lower oxygen permeability than the fourth insulator, and a fifth insulator with varying regions for controlled oxygen supply, using aluminum oxide and incorporating In, Ga, Y, or Sn elements, to enhance carrier density and reduce oxygen vacancies, thereby improving on-state current and reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional insulator configuration is used in oxide semiconductor transistors, then manufacturing is simpler, but oxygen vacancies and impurity effects cause unstable electrical characteristics and high off-state current
Solution Approach 1:
The insulator layer is divided into multiple distinct insulators (first insulator, second insulator, third insulator) with different oxygen permeability characteristics. Each insulator serves a specific function: the first insulator provides oxygen supply, the second insulator acts as a barrier, and the third insulator maintains stability. This segmentation allows precise control of oxygen distribution to eliminate oxygen vacancies while maintaining manufacturability.
Solution Approach 2:
Different regions of the insulator structure are assigned different oxygen permeability properties. The first insulator has high oxygen permeability to supply oxygen to the oxide semiconductor, while the second insulator has low oxygen permeability to prevent oxygen loss. This local differentiation of material properties enables stable electrical characteristics by addressing oxygen vacancy issues specifically where they occur.
2Length of moving object
If the insulator is made thinner to reduce device size, then miniaturization is achieved, but oxygen supply control becomes difficult leading to increased oxygen vacancies
Solution Approach 1:
The insulator structure is segmented into multiple thin layers rather than using a single thick insulator. This allows each layer to be optimized for specific functions (oxygen supply, oxygen barrier, stability) while maintaining overall compact dimensions. The segmented approach enables effective oxygen control even in miniaturized devices.
Solution Approach 2:
The insulator structure uses composite material configuration with different insulator materials having complementary properties. The combination of high-permeability and low-permeability insulators creates a composite system that maintains oxygen vacancy control despite reduced overall thickness, enabling both miniaturization and reliability.
3Reliability
If oxygen permeability is increased to supply more oxygen, then oxygen vacancies are reduced, but off-state current increases due to impurity effects
Solution Approach 1:
The oxygen supply function is segmented and localized to specific insulator regions rather than being uniformly distributed. The first insulator with high oxygen permeability supplies oxygen precisely where needed in the oxide semiconductor, while the second insulator with low permeability prevents excessive oxygen diffusion that would cause impurity effects and increase off-state current.
Solution Approach 2:
Different insulator regions are assigned different oxygen permeability qualities based on local requirements. The first insulator region has high permeability to fill oxygen vacancies, while the second insulator region has low permeability to prevent oxygen excess. This local quality differentiation resolves the contradiction between reducing oxygen vacancies and preventing off-state current increase.
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 configuration results in a semiconductor device with increased on-state current, improved frequency characteristics, and enhanced reliability by reducing oxygen vacancies and impurity effects, leading to stable electrical performance and low power consumption.
Implementation Method 1
The third insulator has a lower oxygen permeability than the fourth insulator
Implementation Method 2
to enhance carrier density and reduce oxygen vacancies
Data Source
AI summary
A semiconductor device with a high on-state current is provided. The semiconductor device includes a first insulator over a substrate, an oxide over the first insulator, a second insulator over the oxide, a conductor overlapping with the oxide with the second insulator therebetween, a third insulator in contact with a top surface of the oxide, a fourth insulator in contact with a top surface of the third insulator, a side surface of the second insulator, and a side surface of the conductor, and a fifth insulator in contact with a side surface of the fourth insulator, a side surface of the third insulator, and the top surface of the oxide. The third insulator has a lower oxygen permeability than the fourth insulator.