Sputter Deposition Control for Non-Stoichiometric Metal Compound Layers
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Solution Overview
Problem
The challenge in sputter deposition is controlling the composition of non-stoichiometric metal compound layers, particularly metal oxides, nitrides, and carbides, due to target poisoning and hysteresis effects, which lead to unstable deposition processes and difficulty in achieving precise control over layer properties such as thickness, density, and composition.
Innovation Solution
A method involving sputter deposition with optical transmittance measurement and feedback control to adjust sputtering conditions, using ceramic targets and minimizing target poisoning, allows for precise control of non-stoichiometric metal compound layers by measuring and adapting sputtering parameters based on optical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If metallic targets are used in reactive mode to deposit metal compound layers, then the deposition process can be initiated with readily available targets, but target poisoning occurs leading to reduced sputter yield and unstable composition control
Solution Approach 1:
The patent applies parameter changes by transitioning from metallic targets to ceramic targets with controlled non-stoichiometric composition. Specifically, ceramic targets with oxygen content ranging from 15-40 at% are used to deposit sub-stoichiometric metal oxide layers with controlled oxygen content (10-30 at%). This parameter change in target composition eliminates target poisoning while maintaining deposition stability and enabling precise control over layer composition.
Solution Approach 2:
The patent employs composite material strategy by using ceramic targets that are composite structures of metal and metal oxide. These ceramic targets contain both metallic and oxide phases, where the metal provides electrical conductivity for DC sputtering and the oxide phase controls the oxygen content in the deposited layer. This composite approach resolves the contradiction between target availability and deposition stability.
2Quantity of substance
If reactive gas flow is increased to form compound layers, then metal compound layers can be deposited, but hysteresis effect causes uncontrollable variations in layer properties
Solution Approach 1:
The patent applies preliminary action by pre-configuring the ceramic target with a specific non-stoichiometric composition before the deposition process. The target is manufactured with controlled oxygen content (15-40 at%) and metal content, which serves as a reservoir that releases oxygen during sputtering. This preliminary preparation eliminates the need for high reactive gas flows and prevents hysteresis effects, enabling precise control over the deposited layer composition without uncontrollable transitions.
Solution Approach 2:
The patent extracts the oxygen supply function from the reactive gas environment and transfers it to the ceramic target material itself. The ceramic target contains embedded oxygen that is released during the sputtering process, eliminating the dependency on reactive gas flow for compound layer formation. This extraction of the oxygen source from the gas phase to the solid target phase resolves the hysteresis problem and enables precise composition control.
3Reliability
If ceramic targets are used to avoid target poisoning, then stable operation is achieved, but manufacture and manipulation become difficult due to high melting point and brittleness
Solution Approach 1:
The patent applies parameter changes by optimizing the ceramic target composition to balance stability and manufacturability. Ceramic targets with specific metal oxide content (15-40 at%) and controlled non-stoichiometry are used. This parameter optimization ensures that the targets have sufficient mechanical strength and reduced brittleness compared to fully stoichiometric ceramics, while maintaining deposition stability and avoiding target poisoning.
Solution Approach 2:
The patent uses composite material approach by creating ceramic targets with a dual-phase structure containing both metallic and oxide components. The metallic phase provides ductility and reduces brittleness, making the targets easier to manufacture and manipulate, while the oxide phase ensures stable deposition and prevents target poisoning. This composite structure resolves the contradiction between stability and ease of manufacture.
4Device complexity
If DC power supply is used for sputtering, then simple and cost-effective power control is achieved, but insulating ceramic targets cannot be effectively powered
Solution Approach 1:
The patent applies composite material strategy by designing ceramic targets with embedded conductive metal phases (such as tungsten, nickel, or copper) within the ceramic matrix. These conductive inclusions provide electrical pathways that enable DC power supply to effectively power the otherwise insulating ceramic target. This composite structure maintains DC power supply simplicity while achieving adaptability to ceramic target materials.
Solution Approach 2:
The patent introduces conductive metal inclusions as intermediaries between the DC power supply and the insulating ceramic target material. These intermediary conductive phases facilitate electrical current flow into the target, enabling effective sputtering of ceramic materials while maintaining the simplicity of DC power supply systems. The intermediary conductive network resolves the incompatibility between DC power and insulating ceramics.
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
Enables accurate deposition of non-stoichiometric metal compound layers with controlled composition and density, reducing target poisoning and achieving stable, predictable layer properties without the need for expensive chemical analysis, and allowing for flexible control of layer parameters.
Implementation Method 1
Deposition via magnetron sputtering is a well-known technique using powered targets under the influence of a magnetic field so that gases in a controlled environment form a plasma track on the target. This results in the removal of material from its surface through plasma ion bombardment and the deposition of sputtered atoms onto a substrate.
Implementation Method 2
This results in the removal of material from its surface through plasma ion bombardment and the deposition of sputtered atoms onto a substrate.
Implementation Method 3
Deposition via magnetron sputtering is a well-known technique using powered targets under the influence of a magnetic field so that gases in a controlled environment form a plasma track on the target.
Data Source
AI summary
A method of depositing a layer on a piece by sputter deposition, a coater and a processor for controlling a coater in accordance with the method are provided. The method includes providing deposition of metallic and reactive species simultaneously on a piece for forming a layer under predetermined sputtering conditions, thereby providing a deposited layer on the piece comprising a metal compound. The deposited layer is subsequently irradiated and the optical transmittance is measured. A measured parameter related to the measured radiation is compared with one stored value of that parameter. The sputtering conditions are thereby adapted as a result of the comparison.