Composite Oxide Channel for Mobility and Threshold Voltage Balance
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing semiconductor devices with In--Ga--Zn-based metal oxides face challenges in achieving optimal electrical characteristics, such as high field-effect mobility and low subthreshold swing, due to issues with threshold voltage and subthreshold swing values.
Innovation Solution
A composite oxide with specific regions of In, Zn, and additional elements like Ga, Al, or Si is used as the channel material in transistors, providing an asymmetric X-ray diffraction pattern and improved electrical properties by forming a mosaic pattern with varying band gaps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a two-layer stack of In-Zn oxide and In-Ga-Zn oxide is used as an active layer with 10 nm thickness to achieve high field-effect mobility, then field-effect mobility is improved (μ=62 cm²V⁻¹s⁻¹), but subthreshold swing becomes large (S=0.41 V/decade) and threshold voltage becomes negative (Vth=-2.9 V) indicating normally-on characteristic
Solution Approach 1:
The patent applies local quality by creating a composite oxide with spatially varying composition: one region has In, Zn, and M1 with a specific proportion, while another region has In, Zn, and M2 with a different proportion. This local compositional variation enables different regions to contribute differently to electrical properties, achieving both high mobility and proper threshold voltage control in the same channel layer.
Solution Approach 2:
The patent employs asymmetry by using different third elements (M1 and M2) or different proportions of the same element in different regions of the composite oxide. The asymmetric compositional design creates asymmetric electronic properties that simultaneously enable high carrier mobility in one region and effective threshold voltage control in another region, resolving the contradiction between speed and reliability.
2Adaptability or versatility
If In-Ga-Zn-based metal oxide is used to fabricate transistors, then semiconductor functionality is achieved, but optimal electrical characteristics including low subthreshold swing and appropriate threshold voltage cannot be simultaneously obtained
Solution Approach 1:
The patent uses composite materials by combining In-Zn-M1-oxide and In-Zn-M2-oxide in a single composite oxide structure. This composite approach allows the material to exhibit multiple beneficial properties: the In-Zn base provides semiconductor functionality, while the different M elements (or proportions) in different regions enable tuning of electrical characteristics including subthreshold swing and threshold voltage, achieving both adaptability and reliability.
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 enhances the electrical characteristics of semiconductor devices, achieving high field-effect mobility and reliable switching operations while reducing leakage current and improving the on-state current and off-state current ratios.
Implementation Method 1
In an analysis of the composite oxide by X-ray diffraction, the diffraction pattern result in the X-ray diffraction is asymmetric with the angle at which the peak intensity of X-ray diffraction is detected as the symmetry axis
Data Source
AI summary
A novel material and a transistor using a novel material are provided. A composite oxide includes at least two regions, one of which includes In, Zn and an element M1 (the element M1 is one or more of Al, Ga, Si, B, Y, Ti, Fe, Ni, Ge, Zr, Mo, La, Ce, Nd, Hf, Ta, W, Mg, V, Be, and Cu), and the other of which includes In, Zn, and an element M2 (the element M2 is one or more of Al, Ga, Si, B, Y, Ti, Fe, Ni, Ge, Zr, Mo, La, Ce, Nd, Hf, Ta, W, Mg, V, Be, and Cu). The proportion of the element M1 to In, Zn, and the element M1 in the region including the element M1 is less than that of the element M2 to In, Zn, and the element M2 in the region including the element M2. In an analysis of the composite oxide by X-ray diffraction, the diffraction pattern result in the X-ray diffraction is asymmetric with the angle at which the peak intensity of X-ray diffraction is detected as the symmetry axis.