Rotary Sputtering Target Bonding Assembly
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Solution Overview
Problem
Rotary sputtering targets with soft or malleable materials face issues such as flexing and breaking during rotation, and existing attachment methods to backing tubes often result in inadequate thermal contact and difficult removal, leading to inefficiencies in cooling and target reuse.
Innovation Solution
A bonding method using a jig to apply adhesive only at the ends of the rotary sputtering target and backing tube, with a perforated backing tube for improved thermal transfer, and a heating plug and variable temperature band for controlled bonding, allowing for repeatable and reliable attachment and easy removal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If adhesive is applied continuously along the entire length of the target-backing tube interface, then bonding strength is improved, but target removal becomes difficult and thermal contact is reduced
Solution Approach 1:
The adhesive bonding interface is segmented into discrete regions rather than being continuous. Adhesive is applied only at specific locations (e.g., at the ends of the target or at spaced intervals) rather than along the entire length, creating distinct bonded zones separated by unbonded regions. This segmentation allows the target to be removed more easily while maintaining sufficient bonding strength at the adhesive locations.
Solution Approach 2:
Different regions of the target-backing tube interface have different bonding characteristics. The ends or specific localized regions have adhesive bonding for strength, while other regions remain unbonded to facilitate removal and maintain thermal contact. This creates local quality variations where bonding strength and removal ease are optimized at different locations.
2Temperature
If backing tube material has high thermal conductivity, then cooling efficiency is improved, but target material may overheat and melt
Solution Approach 1:
The thermal conductivity parameter of the backing tube material is carefully selected and optimized. Instead of using materials with maximum thermal conductivity, the invention uses materials with moderate thermal conductivity that provide sufficient cooling without causing excessive thermal gain that would lead to target material melting. This parameter optimization balances cooling efficiency with thermal protection.
3Strength
If target material is cast directly onto backing tube, then structural rigidity is improved, but porosity and grain size variability increase
Solution Approach 1:
The target structure is divided into separately manufactured components (target material and backing tube) that are subsequently bonded together, rather than being cast as a single integrated structure. This segmentation allows each component to be manufactured with optimal properties and then joined, avoiding the porosity and grain size variability inherent in direct casting while still achieving structural rigidity through the bonded assembly.
4Strength
If mechanical sleeves are used for attachment, then target support is improved, but thermal contact is lost due to thermal expansion
Solution Approach 1:
An adhesive material serves as an intermediary substance between the target and backing tube, replacing mechanical sleeves. The adhesive creates a continuous bonding interface that maintains thermal contact while providing mechanical support. Unlike mechanical sleeves that can lose contact due to thermal expansion, the adhesive bond accommodates thermal expansion while maintaining intimate contact and thermal conductivity.
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
This solution enhances thermal transfer and facilitates easy removal of the target material, improving the sputtering process by maintaining effective contact and reducing thermal expansion issues, while allowing for efficient cooling and increased target material yield.
Implementation Method 1
bonding material is applied only proximate the ends of the rotary sputtering target and is of a thickness to otherwise form a gap between the rotary sputtering target and the backing tube
Implementation Method 2
backing tube having perforations to allow improved thermal transfer of cooling properties to the rotary sputtering target
Implementation Method 3
heating plug and variable temperature band for controlled bonding
Data Source
AI summary
A rotary sputtering target bonded to a backing tube such that the bonding material is applied only proximate the ends of the rotary sputtering target and is also between the target and the backing tube to form a gap between the rotary sputtering target and the backing tube and a device for bonding a rotary sputtering target to a backing tube.