Cylindrical Magnetron Target Axial Magnet Oscillation
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Solution Overview
Problem
Cylindrical sputtering targets in magnetron sputtering exhibit uneven erosion patterns, leading to inefficient material utilization and frequent replacement, as the magnet within the target does not rotate uniformly, causing severe erosion at the ends while the central portion retains sputterable material.
Innovation Solution
The magnet is made to oscillate axially within the target, either synchronously or asynchronously with the target's rotation, using a power train comprising a cam and cam follower, or an actuator, to promote uniform wear along the target's length, ensuring no single rotational position corresponds to a single axial position, preventing uneven wear.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the magnet is held stationary while the target rotates, then the magnetic field generation is simple and stable, but the target erosion becomes highly non-uniform with severe wear at the ends
Solution Approach 1:
The magnet is transformed from a stationary component to a dynamically movable one, oscillating axially within the target during rotation. This dynamic positioning allows the magnetic field to scan across different axial positions, distributing erosion uniformly along the target length and preventing end-specific wear patterns
Solution Approach 2:
The magnet executes periodic axial oscillations synchronized with or independent of the target rotation. This periodic movement creates a scanning effect where the magnetic field systematically covers different axial regions over time, ensuring uniform material removal throughout the target's length
2Productivity
If dual magnets with offset ends are used, then some improvement in target utilization is achieved, but severe erosion at target ends still occurs and replacement frequency remains high
Solution Approach 1:
Instead of using multiple static magnets with fixed offset positions, a single magnet is made dynamically movable through axial oscillation. This approach achieves the same benefit of distributed erosion as dual offset magnets but with simpler hardware, while additionally providing continuous scanning coverage that maximizes target utilization and extends operational life
Solution Approach 2:
The axial position of the magnet is changed continuously during operation through oscillation, rather than maintaining fixed positions. By varying the magnet's axial location dynamically, the system achieves uniform erosion distribution and extends target lifespan, directly improving productivity and reducing replacement frequency
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 approach significantly improves the uniformity of target erosion, extending the target's lifespan by ensuring even material utilization and reducing downtime for replacement, as the magnet's asynchronous movement prevents severe erosion near the ends.
Implementation Method 1
a magnet to produce a magnetic field adjacent to the target
Implementation Method 2
the magnet is made to oscillate axially within the target
Data Source
AI summary
In some embodiments, the invention includes a cylindrical cathode target assembly for use in sputtering target material onto a substrate that comprises a generally cylindrical target, means for rotating the target about its axis during a sputtering operation, an elongated magnet carried within the target for generation of a plasma-containing magnetic field exterior to but adjacent the target, a framework for supporting the magnet against rotation within the target, and a power train for causing the magnet to oscillate within and axially of the target in a substantially asynchronous manner to promote generally uniform target utilization along its length, as well as its method of use. In some embodiments, the magnet is oscillated in response to rotation of the target.