Rotary Magnetron Magnet Bar for High Target Utilization

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Solution Overview

Problem

Rotary magnetrons suffer from low target utilization due to premature wear at the turnaround portion of the target cylinder, leading to inefficient use of target material and contamination of the deposited film, with existing solutions offering only minimal improvements.

Innovation Solution

A configuration of magnets inside the tubular cathode shifts the erosion zone toward the end of the target cylinder by altering the magnetic field apex, dynamically moving the zone of maximal erosion to the thicker end section, thereby improving target utilization by up to 87%.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If the target cylinder is rotated with a stationary internal magnet bar, then a sputter racetrack is generated for material deposition, but premature wear occurs at the turnaround portion leading to low target utilization of only 60%

Engineering Contradiction:

Improvetarget utilizationVSAvoidtarget material wear

Core Design Contradiction:

ProductivityVSLoss of substance

Solution Approach 1:

The magnet bar is configured to rotate synchronously with the target cylinder, transforming the stationary magnetic field into a dynamic rotating magnetic field. This dynamic configuration ensures that the magnetic field apex continuously tracks the erosion zone as it moves around the racetrack, preventing localized premature wear at turnaround portions and achieving up to 87% target utilization

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The synchronous rotation of the magnet bar creates a feedback mechanism where the magnetic field position automatically adjusts to follow the erosion zone. As the target rotates and material is sputtered away, the rotating magnet bar maintains the magnetic field apex aligned with the current erosion location, dynamically compensating for wear distribution

Inventive Principle:

Principle #23Feedback

2Productivity

If dog-boned targets with added thickness in end regions are used, then target utilization improves, but device complexity and overall target diameter increase

Engineering Contradiction:

Improvetarget utilizationVSAvoidtarget formation complexity

Core Design Contradiction:

ProductivityVSDevice complexity

Solution Approach 1:

The invention replaces the mechanical/geometric solution of dog-boned targets with a magnetic field control solution. Instead of modifying the physical shape and thickness distribution of the target, the synchronous rotation of the magnet bar dynamically controls the magnetic field to achieve uniform wear distribution, eliminating the need for complex target shaping

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The invention changes the operational parameters of the magnetron system by implementing synchronous rotation of the magnet bar. This parameter change transforms the static magnetic field configuration into a dynamic one, allowing the system to adapt to wear patterns without requiring physical modifications to the target structure

Inventive Principle:

Principle #35Parameter changes

3Productivity

If dog-boned targets with larger diameter are used, then target utilization improves, but magnetron energy consumption increases

Engineering Contradiction:

Improvetarget utilizationVSAvoidmagnetron energy consumption

Core Design Contradiction:

ProductivityVSUse of energy by moving object

Solution Approach 1:

The invention replaces the energy-intensive mechanical approach of using larger diameter dog-boned targets with a low-energy magnetic field control approach. The synchronous rotation of the magnet bar requires minimal additional energy while achieving the same target utilization improvement, avoiding the increased separation distance and associated energy losses

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 configuration significantly increases target material utilization by redistributing the erosion zone to the thicker end section, extending the operational lifetime of the target and reducing wastage, while avoiding the complexity and increased energy consumption of dog-boned targets.

Implementation Method 1

The magnetic field generated by the magnet bar is also important in establishing the point of maximal erosion

Methodology Applied

Scientific EffectMagnetic field: Magnetic Field

Implementation Method 2

A tubular target formed of a target material that forms a component of the coating has an end. The target is in proximity to the plasma source for sputtering of the target material

Methodology Applied

Scientific EffectSputtering: Sputtering

Data Source

PatentUS10273570B2Rotary magnetron magnet bar and apparatus containing the same for high target utilization

Publication Date: 2019.04.30 GENERAL PLASMA

AI summary

An apparatus for coating a substrate is provided that includes a racetrack-shaped plasma source having two straight portions and at least one terminal turnaround portion connecting said straight portions. A tubular target formed of a target material that forms a component of the coating has an end. The target is in proximity to the plasma source for sputtering of the target material. The target is secured to a tubular backing cathode, with both being rotatable about a central axis. A set of magnets are arranged inside the cathode to move an erosion zone aligned with the terminal turnaround toward the end of the target as the target is utilized to deposit the coating on the substrate. Target utilization of up to 87 weight percent the initial target weight is achieved.