Sputtering Target for High-Mobility Oxide Semiconductor
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Solution Overview
Problem
Current oxide semiconductor thin film transistors using IGZO struggle to achieve mobility exceeding 10 cm2/Vs, necessitating the development of a material with higher mobility for advanced display applications.
Innovation Solution
A sputtering target comprising an oxide sintered body with specific atom ratios of indium, tin, and germanium, along with optional elements like Si, Ti, and Zn, is used to produce an amorphous oxide semiconductor thin film with enhanced mobility and carrier density, achieving transistor characteristics of 10 cm2/Vs or more.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If IGZO is used as the oxide semiconductor material, then the transistor mobility can be improved compared to amorphous silicon, but the mobility cannot exceed 10 cm2/Vs
Solution Approach 1:
The patent changes the compositional parameters of the oxide semiconductor by introducing Ge and Sn elements in specific atom ratios (Ge: 7-40 at%, Sn: 4-60 at%). This parameter change transforms the material properties to achieve mobility exceeding 10 cm2/Vs while maintaining amorphous structure, directly resolving the mobility limit of conventional IGZO
Solution Approach 2:
The patent creates a composite oxide semiconductor material by combining In, Ga, Zn, Ge, and Sn elements. This composite material approach allows synergistic effects where Ge contributes to high mobility and Sn suppresses carrier density, achieving performance beyond what single-component IGZO can provide
2Speed
If the atom ratio of Ge is increased to improve mobility, then the transistor mobility exceeds 10 cm2/Vs, but the crystallinity may change from amorphous to crystalline
Solution Approach 1:
The patent precisely controls the Ge atom ratio within 7-40 at% range. This parameter optimization ensures sufficient Ge content to achieve high mobility while maintaining the amorphous structure by preventing excessive Ge that would induce crystallization. The lower limit (7 at%) ensures amorphous structure stability while the upper limit (40 at%) ensures high mobility
Solution Approach 2:
The patent introduces Sn elements at specific locations and concentrations (4-60 at%) to locally modify the material properties. Sn acts as a carrier suppressor in specific regions, allowing high Ge content for mobility while maintaining overall amorphous structure stability and controlling carrier density
3Quantity of substance
If the atom ratio of Sn is increased to suppress carrier density, then the carrier density decreases to 5×10^19 or less, but the mobility may be affected
Solution Approach 1:
The patent optimizes Sn atom ratio within 4-60 at% range to achieve the right balance. This parameter control ensures sufficient Sn content to suppress carrier density to 5×10^19 or less while maintaining enough Ge content (7-40 at%) to ensure mobility exceeds 10 cm2/Vs, resolving the trade-off between carrier suppression and mobility maintenance
Solution Approach 2:
The patent uses Sn as a localized carrier suppressor in the oxide semiconductor matrix. By distributing Sn at specific concentrations throughout the material, it creates regions with suppressed carrier density while maintaining overall high mobility through the Ge component, achieving both low carrier density and high mobility simultaneously
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
The resulting thin film exhibits high mobility and reliable switching operations with suppressed gate threshold voltage fluctuations, enabling long-term performance in display applications.
Implementation Method 1
a sputtering target and a method of producing a sputtering target
Implementation Method 2
an oxide sintered body including indium, tin, and germanium
Data Source
AI summary
[Object] To provide a sputtering target for producing an oxide semiconductor thin film having high properties, which serves as a substitute for IGZO, and a method of producing the same.[Solving Means] In order to achieve the above-mentioned object, a sputtering target according to an embodiment of the present invention includes: an oxide sintered body including indium, tin, and germanium, in which an atom ratio of germanium with respect to a total of indium, tin, and germanium is 0.07 or more and 0.40 or less, and an atom ratio of tin with respect to the total of indium, tin, and germanium is 0.04 or more and 0.60 or less. As a result, it is possible to achieve transistor characteristics of having mobility of 10 cm2/Vs or more.