Cylindrical Magnetron Target Gap Design for Thermal Stress Reduction
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Solution Overview
Problem
Cylindrical magnetron sputtering devices face issues with target cracking and nodule formation during the deposition of transparent conductive coatings like ITO and AZO, leading to production yield loss and throughput reduction, and require costly bonding of targets to backing tubes for heat management.
Innovation Solution
A cylindrical target assembly with a hollow mandrel and a target portion spaced away from it, creating a gap to allow uniform heating and prevent direct heat transfer, eliminating the need for bonding and enhancing operational power levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the target is bonded to the backing tube for heat management, then heat transfer is improved, but target cracking and nodule formation occur
Solution Approach 1:
The target assembly is segmented into distinct components: the target material is separated from the backing tube by a gap, allowing independent thermal management. The target can expand and contract independently without being bonded to the backing tube, eliminating the thermal stress that causes cracking and nodules while maintaining effective heat transfer through the gap design.
2Stability of the object's composition
If the target is bonded to the backing tube, then structural stability is improved, but production yield is reduced due to target cracking and nodules
Solution Approach 1:
The target is segmented from the backing tube structure, allowing the target material to maintain its integrity without being constrained by thermal expansion mismatches. This segmentation eliminates the root cause of target cracking and nodule formation, thereby maintaining structural stability while improving production yield and reducing defects.
3Temperature
If bonding is used to manage heat, then heat transfer is improved, but operational power levels are limited
Solution Approach 1:
By segmenting the target from the backing tube and eliminating the bonded interface, the system can operate at higher power levels without the thermal stress constraints that limit bonded configurations. The gap allows for better thermal management through radiation and convection, enabling increased operational power while maintaining heat transfer efficiency.
4Temperature
If the target is bonded to the backing tube, then heat management is improved, but target changes become complex and costly
Solution Approach 1:
The target is designed as a separate, unbonded component that can be independently installed and removed. This segmentation simplifies target changes by eliminating the need for bonding processes, allowing for quick replacement of targets without complex manufacturing steps, thereby improving ease of manufacture and reducing costs.
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 solution enables increased production rates, reduced nodule formation, and simplified target changes, allowing the magnetron to operate at higher power levels and maintain film quality without additional heating, thus improving efficiency and reducing costs.
Implementation Method 1
allows the target portion to heat up uniformly and expand
Implementation Method 2
The ions are accelerated and retained within a magnetic field formed over the target
Implementation Method 3
Upon striking the target, the ions dislodge target atoms from the target, which are then deposited upon the substrate
Data Source
AI summary
A rotatable cylindrical magnetron sputtering device that includes a cathode body defining a magnet receiving chamber and a cylindrical target assembly surrounding the cathode body, wherein the cylindrical target assembly is rotatable around the cathode body. The cylindrical target assembly includes a hollow mandrel and a target portion mounted around and spaced away from the hollow mandrel portion so as to create a space gap between the hollow mandrel and the target portion, wherein the space gap may be greater than 0.002 inch and less than 0.020 inch.