Cylindrical TiOx Sputtering Target with Plasma Sprayed Undercoat
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Solution Overview
Problem
Conventional cylindrical sputtering targets with sub-stoichiometric TiOx layers face limitations in maximum thickness due to cracking and peeling issues at high power levels, restricting their use in high-power applications and limiting production runs.
Innovation Solution
A process involving plasma spraying of ceramic TiOy powder with a higher sub-stoichiometric grade (1.45<x<1.65) onto a cylindrical substrate, using a substrate with a suitable undercoat layer for improved bonding and thermal expansion matching, to achieve a target layer thickness of at least 12 mm with enhanced conductivity and reduced susceptibility to cracking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the target layer thickness is increased to improve productivity and deposition speed, then the production run duration is extended, but cracking and peeling occur at high power levels
Solution Approach 1:
The patent applies parameter changes by optimizing the sub-stoichiometric composition range of TiOx (specifically controlling the oxygen deficiency parameter x) and adjusting the plasma spraying process parameters. By precisely controlling the composition parameter x within a specific range and using controlled plasma spraying conditions, the target layer achieves both increased thickness (improving productivity) and enhanced resistance to cracking and peeling (improving reliability) at high power levels.
Solution Approach 2:
The patent employs composite material principles by creating a multi-layer structure consisting of an undercoat layer and a target layer with specific compositional gradients. The undercoat layer provides a bonding interface, while the target layer has a controlled sub-stoichiometric composition that creates a composite structure with improved mechanical properties, allowing thicker layers without cracking or peeling.
2Quantity of substance
If a thicker target layer is used to extend production runs, then the quantity of target material is increased, but the structural integrity deteriorates due to cracking
Solution Approach 1:
The patent changes the compositional parameter of the target material by controlling the sub-stoichiometric ratio x in TiOx within a specific range. This parameter change allows the material to achieve both increased thickness (more quantity) and maintained structural integrity (strength) by optimizing the oxygen deficiency level that affects mechanical properties.
Solution Approach 2:
The patent applies preliminary action by depositing an undercoat layer before the main target layer, and by pre-controlling the composition of the target material during the plasma spraying process. This preliminary preparation ensures that when the thick target layer is formed, it has the necessary structural integrity from the beginning, preventing cracking during subsequent high-power operation.
3Productivity
If high power levels are applied to increase deposition speed, then the productivity is improved, but the target layer becomes more susceptible to cracking and peeling
Solution Approach 1:
The patent changes the material parameter by optimizing the sub-stoichiometric composition x of TiOx, which fundamentally alters the material's resistance to cracking and peeling. This parameter change allows the system to withstand high power levels (improving productivity) without suffering from cracking and peeling (reducing harmful factors).
Solution Approach 2:
The patent converts the potential harm of high power levels (which cause cracking and peeling) into a benefit by using the high power plasma spraying process to deposit the target layer, then utilizing the optimized composition to resist the same high power levels during sputtering operation. The harmful high-power condition is transformed into a beneficial deposition method when combined with the right material 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 process enables the production of large-sized cylindrical sputtering targets with increased power handling capability and extended production runs, maintaining target material composition and electrical conductivity, while minimizing cracking and peeling, thus achieving higher deposition speeds and productivity.
Implementation Method 1
forming a ceramic layer on the substrate by plasma spraying, wherein said ceramic powder is made in a semi-molten state in a high temperature plasma gas
Implementation Method 2
it is transported and deposited onto the substrate by the plasma gas
Data Source
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AI summary
Known cylindrical sputtering targets comprise a substrate and a target material that forms a layer on the substrate, said layer has a thickness d, wherein the target material comprises TiOx as the main component, and x is within a range of 1<x<2. Starting therefrom and in order to provide large-sized cylindrical sputtering targets with a thick target layer comprising sub-stoichiometric TiO2 it is proposed that x is within a range of 1.45<x<1.7 that allows a target layer thickness d which is larger than 10 mm.