Oxide Semiconductor Channel Layer Composition Gradient
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Solution Overview
Problem
Current semiconductor devices face challenges in enhancing the leakage and channel characteristics of transistors, which are crucial for high integration and performance in miniaturized semiconductor devices.
Innovation Solution
A semiconductor device is designed with a channel layer made of a single-layer oxide semiconductor material comprising indium (In), gallium (Ga), and oxygen (O), with specific concentration gradients in different regions to optimize the leakage and channel characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional single-layer oxide semiconductor material is used without composition variation, then the manufacturing process is simple, but the leakage characteristic and channel characteristic cannot be simultaneously enhanced
Solution Approach 1:
The channel layer is divided into multiple regions with different compositions: a first region with higher Ga concentration near the substrate, a second region with higher In concentration in the middle, and a third region with higher Ga concentration near the gate structure. This local quality variation allows different regions to serve different functions - the Ga-rich regions suppress oxygen vacancies and improve leakage characteristics, while the In-rich region enhances carrier concentration and mobility for better channel characteristics.
2Reliability
If Ga concentration is increased throughout the channel layer to reduce oxygen vacancies, then leakage characteristic improves, but carrier concentration and mobility in the channel decrease
Solution Approach 1:
Instead of uniformly increasing Ga concentration throughout the channel layer, the invention creates localized Ga-rich regions only where needed (first and third regions) while maintaining In-rich composition in the middle region (second region). This localized approach suppresses oxygen vacancies and improves leakage characteristics in specific areas without excessively reducing carrier concentration and mobility in the central channel region.
Solution Approach 2:
The invention changes the compositional parameters (concentrations of In and Ga) at different positions within the channel layer. By varying the In/Ga ratio across different regions, the material properties are optimized locally - with Ga-dominant compositions near the boundaries for leakage control and In-dominant composition in the center for high carrier concentration and mobility.
3Productivity
If In concentration is increased throughout the channel layer to enhance carrier concentration, then channel characteristic improves, but oxygen vacancy reduction and leakage suppression are compromised
Solution Approach 1:
The channel layer is designed with non-uniform In and Ga distributions: the second region has high In concentration to maximize carrier concentration and mobility for excellent channel characteristics, while the first and third regions have high Ga concentration to suppress oxygen vacancies and improve leakage characteristics. This spatial separation of functions resolves the contradiction between channel performance and leakage suppression.
Data Source
AI summary
A semiconductor device includes a channel layer disposed on a substrate and a gate structure formed on or under the channel layer. The channel layer includes a single-layer oxide semiconductor material, the channel layer includes indium (In), gallium (Ga), and oxygen (O), the channel layer includes a first region, a second region, and a third region, the third region contacting the gate structure, a second region between the first region and the third region, the first region is the closer to the substrate than the second region and the third region, each of the first region and the third region has a concentration of Ga higher than a concentration of In, and the second region has a concentration of In higher than a concentration of Ga.