Cylindrical Sputtering Target Grinding Angle Optimization
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Solution Overview
Problem
Cylindrical sputtering targets used in magnetron rotary cathode sputtering apparatuses face significant cracking issues due to thermal expansion differences between the target material and the backing tube, leading to poor film quality and reduced target utilization.
Innovation Solution
The solution involves using ceramic materials like ITO or AZO with a relative density of at least 90% and optimizing the grinding direction on the cylindrical target's outer surface to minimize stress-induced cracking, specifically by adjusting the grinding angle between the grinding direction and the cylindrical axis to reduce perpendicular stress, and maintaining a surface roughness of no more than 3 µm to mitigate both parallel and perpendicular stresses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If ceramic materials like ITO or AZO are used as cylindrical target material, then high film deposition rate and target utilization ratio can be achieved, but cracking occurs due to thermal expansion difference with the metal backing tube
Solution Approach 1:
The invention changes the physical parameters of the ceramic target material by controlling its relative density to be 90% or more, and by optimizing the surface roughness through controlled grinding. These parameter changes reduce thermal stress accumulation and prevent cracking while maintaining high deposition rates
Solution Approach 2:
The invention creates a composite structure by bonding ceramic target material to a metal backing tube, where the ceramic provides high deposition rate and the metal provides thermal conductivity. The interface design and stress management in this composite structure prevent cracking despite thermal expansion differences
2Reliability
If the cylindrical target material is ground to reduce surface stress, then cracking can be reduced, but manufacturing complexity increases due to specific grinding direction requirements
Solution Approach 1:
The invention applies different surface treatments to different regions of the cylindrical target. Specifically, the outer peripheral surface is ground at specific angles (45°≤θ1≤90° and tanθ2>πR/L) while maintaining controlled roughness (Ra≤3μm), creating local quality variations that optimize stress distribution without requiring complex overall processing
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 reduces cracking during sputtering, ensuring high target utilization and film quality by effectively managing thermal expansion stresses through precise grinding techniques and high-density ceramic materials.
Implementation Method 1
cracking of the cylindrical target material attributable to the difference in the thermal expansion between the cylindrical target material and the cylindrical backing tube during sputtering
Data Source
AI summary
To provide a cylindrical sputtering target, whereby cracking during sputtering can be remarkably reduced. A cylindrical sputtering target, wherein a cylindrical target material made of ITO or AZO has a relative density of at least 90%; the angle between the grinding direction on its outer circumferential surface and a straight line parallel with its cylindrical axis (out of such angles, θ represents an angle between 0° and 90°) satisfies 45°<θ≦90° or tanθ>πR/L (where R is an outside diameter of the cylindrical target material, and L is the length of the cylindrical target material); and the surface roughness Ra of the outer circumferential surface of the cylindrical target material is at most 3 µm.