Oxide Semiconductor Layer Structure for Low Leakage and High On-Current
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Solution Overview
Problem
Existing semiconductor devices face challenges in miniaturization, high integration, achieving excellent electrical characteristics, high on-state current, and frequency characteristics, while also requiring high reliability and productivity.
Innovation Solution
A semiconductor device is designed with a specific layered structure including multiple insulators and conductors, with oxide layers having varying conductivity and crystallinity, to enhance electrical performance and reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If oxide semiconductors are used as alternative materials to silicon-based semiconductor materials, then devices with extremely low off-state current can be achieved, but challenges remain in miniaturization, high integration, and achieving high on-state current
Solution Approach 1:
The oxide semiconductor layer is divided into multiple regions with different crystallinity: a first region with higher crystallinity and a second region with lower crystallinity. This segmentation allows each region to fulfill different functional requirements - the highly crystalline region provides low off-state current, while the less crystalline region facilitates carrier conduction for high on-state current, resolving the contradiction between reliability and device performance
Solution Approach 2:
Different regions of the oxide semiconductor layer are given different local properties - the first region has higher crystallinity for low leakage current, while the second region has lower crystallinity for better carrier mobility. This local differentiation of material properties enables simultaneous achievement of low off-state current and high on-state current without requiring complete device miniaturization
2Reliability
If oxide semiconductors are used, then transistors with extremely low off-state current can be achieved, but high on-state current and frequency characteristics are difficult to achieve simultaneously
Solution Approach 1:
The oxide semiconductor layer is divided into multiple regions with different crystallinity: a first region with higher crystallinity and a second region with lower crystallinity. This segmentation allows each region to fulfill different functional requirements - the highly crystalline region provides low off-state current, while the less crystalline region facilitates carrier conduction for high on-state current, resolving the contradiction between reliability and device performance
Solution Approach 2:
Different regions of the oxide semiconductor layer are given different local properties - the first region has higher crystallinity for low leakage current, while the second region has lower crystallinity for better carrier mobility. This local differentiation of material properties enables simultaneous achievement of low off-state current and high on-state current
3Ease of manufacture
If conventional semiconductor structures are used, then manufacturing simplicity is maintained, but electrical characteristics and frequency performance are insufficient
Solution Approach 1:
The patent applies preliminary heat treatment to the oxide semiconductor layer before transistor formation to control crystallinity distribution. This preliminary action creates the desired mixed crystalline structure in advance, ensuring both ease of manufacture through standard thermal processing and superior electrical characteristics without complex additional fabrication steps
Data Source
AI summary
A semiconductor device including: a first insulator in which an opening is formed; a first conductor positioned in the opening; a first oxide over the first insulator; a second oxide over the first oxide; a third oxide and a fourth oxide over the second oxide; a second conductor over the third oxide and the first conductor; a third conductor over the fourth oxide; a fifth oxide over the second oxide; a second insulator over the fifth oxide; and a fourth conductor positioned over the second insulator and overlapping with the fifth oxide. The fifth oxide is in contact with each of a side surface of the third oxide and a side surface of the fourth oxide. The conductivity of the third oxide is higher than the conductivity of the second oxide. The second conductor is in contact with the top surface of the first conductor.