Oxide Semiconductor Device Oxygen Supply Barrier
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Solution Overview
Problem
Transistors using oxide semiconductors face reliability issues due to sensitivity to impurities and oxygen vacancies, leading to unstable electrical characteristics and low reliability.
Innovation Solution
The semiconductor device reduces impurity concentration and oxygen vacancies by supplying excess oxygen to the oxide semiconductor from an oxide insulator, and uses a barrier insulator to prevent hydrogen and water from entering, while also employing dehydration and dehydrogenation treatments to enhance the barrier properties against impurities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If oxide semiconductor is used as active layer, then device functionality is achieved, but electrical characteristics become unstable due to impurities and oxygen vacancies
Solution Approach 1:
The oxide insulator is pre-formed with excess oxygen content before the oxide semiconductor is introduced. This preliminary preparation of the insulator creates a reservoir of oxygen that will later diffuse to fill vacancies in the semiconductor, preventing instability before it occurs.
Solution Approach 2:
The oxide insulator acts as an intermediary medium between the external environment and the oxide semiconductor. It serves as both a barrier to impurities and a source of oxygen, mediating the interaction between the semiconductor and its surroundings to maintain electrical stability.
2Productivity
If oxide semiconductor transistor is manufactured, then device integration is achieved, but threshold voltage changes after bias temperature stress test
Solution Approach 1:
The oxide insulator is prepared in advance with excess oxygen through specific formation conditions (such as using In-Ga-Zn-O target with oxygen-rich composition). This preliminary oxygen enrichment ensures that when the device undergoes bias temperature stress testing, oxygen can diffuse from the insulator to maintain threshold voltage stability.
3Ease of manufacture
If conventional oxide semiconductor structure is used, then manufacturing simplicity is maintained, but impurity concentration remains high
Solution Approach 1:
The invention uses a composite structure combining oxide semiconductor with oxide insulator having specific barrier properties. This composite approach allows the insulator to provide impurity blocking and oxygen supply functions while maintaining compatibility with conventional manufacturing processes like sputtering.
Solution Approach 2:
The insulator is formed with specific parameters (thickness of 50-200 nm, oxygen-rich composition, specific dielectric constant range) that optimize its ability to block impurities while supplying oxygen. These parameter changes enable precise control of impurity concentration without complicating the overall manufacturing process.
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 approach results in improved reliability, stable electrical characteristics, reduced power consumption, and the ability to miniaturize or highly integrate semiconductor devices with increased producibility.
Implementation Method 1
supplying excess oxygen to the oxide semiconductor from an oxide insulator in the vicinity of the oxide semiconductor
Implementation Method 2
dehydration and dehydrogenation by heat treatment or the like to prevent impurities such as water or hydrogen from entering an oxide semiconductor
Data Source
AI summary
A highly reliable semiconductor device includes a first insulator, a second insulator, a first conductor, a third insulator, an oxide semiconductor, second and third conductors, a fourth insulator, a fourth conductor overlapping with a region between the second and third conductors, a fifth insulator, and a sixth insulator in this order. The fourth insulator is in contact with top and side surfaces of the oxide semiconductor, and a top surface of the third insulator. The fifth insulator is in contact with the side surface of the oxide semiconductor and the top surface of the third insulator so as to cover the oxide semiconductor, the second to fourth conductors, and the fourth insulator. The first, second, fifth, and sixth insulators have low permeability for hydrogen, water, and oxygen. The first and sixth insulators have a thinner thickness than the second and sixth insulators, respectively.