Rotatable Sputter Target Assembly for Uniform Long-Span Deposition
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Solution Overview
Problem
Rotatable sputtering targets used in PVD processes face challenges in maintaining uniformity and deposition rate, especially when scaling up to larger substrates like solar panels and architectural glass, due to surface erosion and inefficiencies in material utilization, requiring innovative methods for manufacturing longer targets with enhanced operational energies.
Innovation Solution
The development of rotatable sputtering targets assembled from stacked and bonded sputtering material cylinders, using a conductive backing tube with a thermally and electrically conductive bonding material, such as indium, and a woven wire mesh to ensure radial symmetry and efficient heat transfer, allowing for longer target lengths and improved bonding integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If rotatable sputtering targets are used for large surface area substrates, then productivity is improved, but manufacturing precision deteriorates due to surface erosion and non-uniform deposition
Solution Approach 1:
The sputtering target is divided into multiple cylindrical segments stacked along the backing tube. Each segment can be independently manufactured with precise dimensions and then assembled, allowing for better control of material uniformity while achieving the required long length for large substrate coverage
Solution Approach 2:
The patent changes the physical and chemical parameters of the bonding material (using thermally and electrically conductive materials with specific melting points and conductivity properties) to ensure uniform heat and electricity distribution across the target, maintaining deposition uniformity while enabling extended target length for higher productivity
2Productivity
If target length is increased to coat larger substrates, then productivity is improved, but reliability deteriorates due to bonding integrity issues
Solution Approach 1:
The patent employs composite bonding structures combining thermally conductive materials (for heat dissipation) and electrically conductive materials (for electrical continuity) in the bonding layers between segments and to the backing tube. This composite approach ensures both mechanical integrity and functional performance over extended target lengths
Solution Approach 2:
The bonding material acts as an intermediary between the cylindrical segments and the backing tube, providing thermal and electrical pathways that maintain structural reliability. The intermediary material compensates for potential mismatches in thermal expansion and electrical conductivity between different target components
3Productivity
If operational energy is increased to enhance deposition rate, then productivity is improved, but loss of substance worsens due to accelerated surface erosion
Solution Approach 1:
By segmenting the target into multiple replaceable cylindrical units, the patent enables selective replacement of eroded segments without replacing the entire target assembly. This reduces overall material loss and extends the effective operational life of the target system while maintaining high deposition rates
Solution Approach 2:
The segmented design allows for discarding only the worn cylindrical segments while retaining the backing tube and intact segments. This recovery approach minimizes material waste and reduces the frequency of complete target replacements, improving productivity while managing substance loss
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 enables the creation of sputtering targets over a meter long, with enhanced bonding integrity and thermal conductivity, resulting in higher manufacturing efficiencies and extended operational life, as demonstrated by successful tests running up to 19 kW/m for 136 hours without failure.
Implementation Method 1
The annular space is occupied by a thermally conductive bonding material and a thermally and electrically conductive element
Implementation Method 2
The annular space is occupied by a thermally conductive bonding material and a thermally and electrically conductive element
Implementation Method 3
Sputtering is a manufacturing process used to create thin films by depositing a material in a vacuum from a 'target' onto the surface of a desired substrate
Data Source
AI summary
A rotatable sputtering target is provided for use in a sputtering system having a plurality of hollow sleeves of sputtering material arranged on a hollow e backing tube so as to form an annular space that is occupied by a bonding agent and a thermally conductive element which is a woven metal mesh.