Oxide Semiconductor Device With Island Structure
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Solution Overview
Problem
Current semiconductor devices using oxide semiconductors face challenges in miniaturization, integration, maintaining stable electrical characteristics, preventing leakage current, threshold voltage degradation, and short channel effects.
Innovation Solution
A semiconductor device structure incorporating an island-like oxide semiconductor layer with surrounding insulating layers, multiple oxide layers, and specific electrode layers to enhance electrical characteristics and reliability, including a stacked-layer structure with In-M-Zn oxide layers to suppress oxygen vacancy generation and improve carrier mobility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If oxide semiconductor transistors are miniaturized for high density integration, then device integration density improves, but short channel effects and leakage current increase
Solution Approach 1:
The patent applies local quality by creating an In-M-Zn oxide semiconductor layer with specific compositional gradients and local stoichiometric control. The In-M-Zn oxide structure allows different regions of the semiconductor layer to have optimized properties: the In-rich regions provide high carrier mobility while M-element rich regions suppress oxygen vacancies and reduce leakage current. This local compositional variation enables miniaturization while maintaining reliability by addressing short channel effects through targeted material design rather than uniform structure.
2Length of moving object
If oxide semiconductor layer thickness is reduced for miniaturization, then device size decreases, but electrical characteristics stability deteriorates
Solution Approach 1:
The patent employs composite materials by creating an In-M-Zn oxide semiconductor that combines multiple metal elements (In, M, Zn) in a unified crystal structure. This composite oxide structure provides superior electrical characteristics stability compared to simple oxides because the multiple elements work synergistically: In provides high carrier mobility, Zn stabilizes the oxide structure, and M elements (such as Ga, Al, or Ti) control oxygen vacancy formation. The composite nature allows the thin film to maintain stable electrical characteristics even at reduced thickness by balancing competing requirements through multi-element chemistry.
Solution Approach 2:
The patent applies parameter changes by systematically varying the compositional parameters of the In-M-Zn oxide semiconductor. The M element ratio, In:M:Zn atomic ratios, and oxygen content are precisely controlled to optimize electrical characteristics. By changing these compositional parameters, the patent achieves stable threshold voltage and low leakage current in miniaturized devices. The ability to tune these parameters allows optimization of both device size and electrical stability, resolving the contradiction between miniaturization and characteristics stability.
3Ease of manufacture
If conventional oxide semiconductors are used, then manufacturing simplicity is maintained, but leakage current increases and threshold voltage degrades
Solution Approach 1:
The patent applies parameter changes by modifying the compositional parameters of the oxide semiconductor from conventional single-element or binary oxides to ternary In-M-Zn oxide. This parameter change (adding M elements and optimizing In:M:Zn ratios) enables simultaneous achievement of low leakage current and stable threshold voltage while maintaining compatibility with existing manufacturing processes. The In-M-Zn oxide can be deposited using standard sputtering or MOCVD techniques, so the manufacturing complexity increase is minimal compared to the significant improvement in reliability and leakage current control.
Data Source
AI summary
To provide a semiconductor device which can be miniaturized or highly integrated. To obtain a semiconductor device including an oxide semiconductor, which has favorable electrical characteristics. To provide a highly reliable semiconductor device including an oxide semiconductor, by suppression of a change in its electrical characteristics. The semiconductor device includes an island-like oxide semiconductor layer over an insulating surface; an insulating layer surrounding a side surface of the oxide semiconductor layer; a source electrode layer and a drain electrode layer in contact with top surfaces of the oxide semiconductor layer and the insulating layer; a gate electrode layer overlapping with the oxide semiconductor layer; and a gate insulating layer between the oxide semiconductor layer and the gate electrode layer. The source electrode layer and the drain electrode layer are provided above the top surface of the oxide semiconductor layer. The top surface of the insulating layer is planarized.