Gallium Oxide Zinc Oxide Target Composition for Stable Sputtering
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Solution Overview
Problem
Conventional gallium oxide (Ga2O3)/zinc oxide (ZnO) sputtering targets face issues with abnormal electrical discharge and particle generation, leading to unstable plasma and poor film quality, which increases manufacturing costs and reduces productivity, especially in large-area deposition applications.
Innovation Solution
A high-density gallium oxide/zinc oxide sputtering target is developed by adding 20 massppm or greater of zirconium oxide and aluminum oxide, with a total content less than 250 ppm, to inhibit nodule formation and abnormal electrical discharge, achieving a sintered density of 5.45 g/cm3 or higher and a bulk resistance value of 3.0 mΩ or less.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional GZO sputtering targets are used, then the manufacturing cost is reduced compared to ITO, but abnormal electrical discharge and particle generation occur leading to poor film quality
Solution Approach 1:
The patent applies parameter changes by precisely controlling the composition ratios of Ga2O3 (1-7 mass%) and ZnO (93-99 mass%) in the sputtering target, as well as optimizing sintering temperature (1300-1550°C) and oxygen partial pressure during fabrication. These parameter optimizations enable the GZO target to achieve stable plasma discharge and high-quality film deposition, resolving the contradiction between cost-effectiveness and film quality
Solution Approach 2:
The patent uses composite materials by creating a multi-component oxide system combining Ga2O3 and ZnO in specific ratios, rather than using pure ZnO. This composite structure leverages the beneficial properties of both oxides: ZnO provides the base conductivity through oxygen defects, while Ga2O3 addition improves plasma stability and reduces abnormal discharge, thereby achieving both cost reduction and high film quality
2Productivity
If sputtering is performed to form GZO film, then the deposition speed and film thickness can be controlled, but nodules form on the target surface and particles float in the chamber
Solution Approach 1:
The patent applies preliminary anti-action by pre-optimizing the target composition and microstructure before sputtering begins. Specifically, the controlled addition of Ga2O3 to ZnO and the optimized sintering process create a homogeneous, dense target structure that resists nodule formation during sputtering. This preliminary preparation prevents the harmful effects of nodules and particles from occurring during high-speed deposition
Solution Approach 2:
The patent changes physical parameters by optimizing the sintering temperature (1300-1550°C) and oxygen partial pressure during target fabrication, as well as controlling the sputtering power density and gas pressure. These parameter changes create optimal conditions that maintain stable plasma discharge at high deposition speeds while preventing nodule formation and particle generation
3Reliability
If the GZO target composition is adjusted to improve conductivity, then the optical transmission factor may be maintained, but the plasma discharge stability deteriorates
Solution Approach 1:
The patent applies parameter changes by systematically optimizing the Ga2O3 content (1-7 mass%) and ZnO content (93-99 mass%) to find the optimal balance between conductivity and plasma stability. Additionally, the sintering temperature (1300-1550°C) and oxygen partial pressure are adjusted to control the oxygen defect concentration, which simultaneously affects both conductivity and plasma discharge stability. This multi-parameter optimization resolves the contradiction between these two properties
Solution Approach 2:
The patent uses composite materials by combining Ga2O3 and ZnO in specific ratios to create a synergistic effect. The ZnO component provides high conductivity through oxygen defects, while the Ga2O3 component stabilizes the plasma discharge. This composite approach allows both high conductivity and stable plasma discharge to be achieved simultaneously, rather than having to trade one for the other
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 target enables stable deposition of transparent conductive films with improved conductivity and optical transparency, comparable to standard ITO films, while reducing nodule formation and abnormal electrical discharges, thus enhancing the efficiency and quality of the film deposition process.
Implementation Method 1
Formation of a film based on the sputtering method is conducted by physically colliding positive ions such as Ar ions to a target disposed on a negative electrode, using such collision energy to discharge a material for configuring a target, and laminating a film having roughly the same composition as the target material on a substrate on the positive electrode opposite to the target
Implementation Method 2
a zinc oxide sintered target, which is free from abnormal electrical discharge and capable of forming a stable thin film
Data Source
AI summary
Provided is a high-density gallium oxide/zinc oxide sintered sputtering target containing 20 massppm or greater of each zirconium oxide and aluminum oxide, wherein the total content thereof is less than 250 ppm. This gallium oxide (Ga2O3)/zinc oxide (ZnO) sputtering target (GZO target) improves the conductivity and bulk density of the target by adding trace amounts of specific elements. In other words, it is possible to obtain a target capable of increasing the sintered density, inhibiting the formation of nodules, and preventing the generation of abnormal electrical discharge and particles by improving the component composition. Further, provided are a method of forming a transparent conductive film with the use of the target, and a transparent conductive film formed thereby.