Composite Oxide Semiconductor Structure for High-Mobility Transistors
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Solution Overview
Problem
The formation of a spinel crystal structure in In--Ga--Zn-based oxide semiconductors can adversely affect the electrical characteristics and reliability of semiconductor devices, such as transistors, leading to suboptimal performance.
Innovation Solution
A composite oxide semiconductor is developed with a structure comprising a first region and multiple second regions, where the first region contains indium, an element M (such as Al, Ga, or Sn), and zinc, and the second regions have a higher indium concentration and conductivity, with specific atomic ratios and thicknesses, to enhance carrier mobility and switching characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the composition is adjusted to achieve higher carrier mobility, then electrical conductivity improves, but spinel crystal structure formation increases which adversely affects reliability
Solution Approach 1:
The patent applies local quality by creating a composite oxide semiconductor with spatially varying composition: a first region with lower indium content (In:M:Zn atomic ratio 1:1:1 to 3:1:3) and second regions with higher indium content (In:M:Zn atomic ratio 5:1:6 to 10:1:12). This local compositional variation allows the high-indium regions to provide high carrier mobility while the low-indium regions suppress spinel crystal structure formation, thereby resolving the contradiction between electrical conductivity and reliability
Solution Approach 2:
The patent employs composite materials by forming a composite oxide semiconductor consisting of multiple regions with different compositions. The first region contains indium, element M (Al, Ga, or Sn), and zinc, while the second regions contain indium and zinc with higher indium concentration. This composite structure combines the benefits of high conductivity regions with the stability of low-spinel regions, achieving both high carrier mobility and device reliability
2Reliability
If indium concentration is increased to improve carrier mobility, then electrical characteristics improve, but the risk of forming spinel crystal structure increases
Solution Approach 1:
The patent implements local quality through distinct compositional zones: the first region uses a controlled In:M:Zn ratio (1:1:1 to 3:1:3) to maintain structural stability, while the second regions use higher In:Zn ratios (5:1:6 to 10:1:12) to maximize carrier mobility. This localized compositional strategy achieves superior electrical characteristics without requiring complex uniform composition control throughout the entire semiconductor layer
Solution Approach 2:
The composite oxide semiconductor structure combines regions with different indium concentrations, allowing the system to achieve high overall carrier mobility while the lower-indium first region acts as a stabilizing matrix that prevents excessive spinel formation. This composite approach simplifies compositional control compared to attempting uniform high-indium composition throughout
3Productivity
If uniform composition is used throughout the oxide semiconductor, then manufacturing is simpler, but carrier mobility is limited
Solution Approach 1:
The patent applies segmentation by dividing the oxide semiconductor into a first region and multiple second regions with different compositions. The first region serves as a base layer with controlled In:M:Zn ratio, while the second regions are dispersed within it to provide high-indium zones for enhanced carrier mobility. This segmented structure achieves superior electrical performance while maintaining relatively simple manufacturing through a single-layer deposition process with controlled composition gradients
Solution Approach 2:
Through local quality variation, the patent creates high-indium second regions embedded in a lower-indium first region matrix. This allows the semiconductor to achieve high carrier mobility in critical areas without requiring uniform high-indium composition throughout, thus maintaining manufacturing simplicity while enhancing performance
Data Source
AI summary
A novel material is provided. A composite oxide semiconductor in which a first region and a plurality of second regions are mixed is provided. Note that the first region contains at least indium, an element M (the element M is one or more of Al, Ga, Y, and Sn), and zinc, and the plurality of second regions contain indium and zinc. Since the plurality of second regions have a higher concentration of indium than the first region, the plurality of second regions have a higher conductivity than the first region. An end portion of one of the plurality of second regions overlaps with an end portion of another one of the plurality of second regions. The plurality of second regions are three-dimensionally surrounded with the first region.