Substoichiometric Molybdenum Oxide Target for Stable DC Sputtering
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Solution Overview
Problem
Existing molybdenum oxide target materials for cathode atomization in PVD coating plants face challenges in achieving uniform layer thickness and composition, particularly for substoichiometric MoOx layers, due to limitations in oxygen content adjustment and process stability, leading to inhomogeneities and high production costs.
Innovation Solution
An electrically conductive oxidic target material comprising a combination of substoichiometric molybdenum oxide phases, including MoO2 and MoO3-y, with a high relative density, allowing for precise adjustment of oxygen content over a wide range, enabling DC or pulsed DC sputtering processes without additional oxygen, thereby improving layer homogeneity and process stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a metallic molybdenum target is used for reactive sputtering to produce substoichiometric MoOx layers, then the oxygen content can be adjusted to achieve desired layer composition, but the process requires complicated and expensive technology to maintain uniform oxygen concentration, and hysteresis effects occur during oxygen partial pressure changes
Solution Approach 1:
The target material is pre-prepared with a specific substoichiometric composition (MoO2.5 to MoO2.98) before the sputtering process. This preliminary preparation of the target with controlled oxygen content eliminates the need for complex real-time oxygen concentration control during sputtering, while still achieving uniform substoichiometric layers on the substrate
Solution Approach 2:
The invention changes the fundamental parameter of the target material from metallic molybdenum to pre-formed substoichiometric molybdenum oxide. This parameter change transforms the process from reactive sputtering requiring complex oxygen control to direct sputtering of a material that already has the desired oxygen content, thereby reducing process complexity while maintaining layer uniformity
2Manufacturing precision
If oxide-ceramic target materials such as MoO2 or substoichiometric MoOx are used, then the oxygen content is closer to the desired layer composition, but the achievable relative densities are extremely disadvantageous (around 85%), leading to increased risk of arc discharges and particle formation
Solution Approach 1:
The invention changes the density parameter of the target material from the typical 85% relative density of conventional oxide-ceramic targets to a high relative density of at least 95%. This parameter change is achieved through optimized sintering processes and results in improved process stability, reduced arc discharge risk, and decreased particle formation, while maintaining the desired substoichiometric composition
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 material achieves high-quality, uniformly thick molybdenum oxide layers with adjustable oxygen content, reducing the need for additional oxygen introduction and minimizing hysteresis effects, resulting in enhanced process stability and cost-effectiveness.
Implementation Method 1
In this coating process (sputtering process), the layer-forming particles are transferred from the (sputtering) target into the gas phase
Implementation Method 2
a corresponding molybdenum oxide-containing layer is formed on the substrate to be coated by condensation of these particles
Data Source
AI summary
An electrically conductive, oxidic target material includes a proportion of substoichiometric molybdenum oxide phases of at least 60% by volume, an MoO2 phase in a proportion of 2-20% by volume, and optionally an MoO3 phase in a proportion of 0-20% by volume. The substoichiometric molybdenum oxide phase proportion is formed by one or more substoichiometric MoO3-y phase(s), where y is in each case in a range from 0.05 to 0.25. A process for producing the target material and a process for using the target material are also provided.