Cobalt Sputtering Target Crystal Orientation
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Solution Overview
Problem
Current sputtering targets for magnetron sputtering methods, particularly those using cobalt, face inefficiencies due to weak magnetic flux density on the front surface, leading to reduced sputtering efficiency and non-uniform film deposition.
Innovation Solution
A cobalt sputtering target with a purity of 99.95 wt % or more, featuring a hexagonal close-packed lattice structure with specific X-ray diffraction peak intensity ratios and aligned magnetization easy axes perpendicular to the sputtering surface, along with a production method involving hot forging, hot rolling, vacuum heating, and cold rolling to enhance plasma trapping and magnetic flux density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a ferromagnetic material such as cobalt is applied to a sputtering target, then the deposition rate is improved, but the magnetic flux density on the front surface decreases and sputtering efficiency is significantly reduced
Solution Approach 1:
The invention changes the crystallographic orientation parameters of cobalt from conventional random or (100) orientation to specifically (002) plane orientation with C-axis perpendicular to the sputtering surface. This parameter change in crystal structure fundamentally alters the magnetic permeability characteristics, reducing magnetic flux leakage and enhancing plasma trapping efficiency while maintaining high deposition rates
Solution Approach 2:
The invention creates a composite structure by combining cobalt with specific crystal orientation ((002) plane) and controlled grain structure through hot rolling and heat treatment processes. This composite approach integrates the ferromagnetic properties of cobalt with optimized magnetic flux distribution, achieving both high deposition rate and sustained sputtering efficiency
2Temperature
If the magnetic field leaking from a magnet disposed on the back surface of the target to the front surface of the target is weak, then the magnetic flux density on the front surface of the target decreases, but the sputtering efficiency is significantly reduced
Solution Approach 1:
The invention changes the magnetic permeability parameters by controlling crystal orientation to (002) plane with C-axis perpendicular to the sputtering surface. This reduces the parallel magnetic permeability component, allowing stronger magnetic flux penetration to the front surface and enhancing plasma trapping without sacrificing sputtering efficiency
Solution Approach 2:
The invention transitions the magnetic flux distribution from a two-dimensional surface phenomenon to a three-dimensional volume effect by aligning the C-axis perpendicular to the sputtering surface. This dimensional reorientation allows magnetic flux to penetrate through the target thickness more effectively, increasing flux density at the front surface and improving plasma confinement
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
Significantly improved sputtering efficiency, uniform film thickness distribution, and sheet resistance are achieved, with enhanced magnetic flux density and plasma trapping effects.
Implementation Method 1
the amount of a magnetization easy axis C oriented perpendicular to the sputtering surface of the cobalt target is remarkably high, the effect of trapping plasma in the vicinity of the sputtering surface is enhanced
Implementation Method 2
an intensity ratio (I(002)+I(004))/(I(100)+I(002)+I(101)+I(102)+I(110)+I(103)+I(112)+I(004)) of X-ray diffraction peaks corresponding to a (100) plane, a (002) plane, a (101) plane, a (102) plane, a (110) plane, a (103) plane, a (112) plane, and a (004) plane
Implementation Method 3
the magnetic flux density leaking perpendicular to the sputtering surface significantly increases. As a result, the effect of trapping plasma in the vicinity of the sputtering surface is enhanced
Implementation Method 4
a cobalt plate is formed by performing hot forging and hot rolling on a cobalt ingot
Implementation Method 5
a cobalt plate is formed by performing hot forging and hot rolling on a cobalt ingot
Implementation Method 6
first vacuum heating is performed on the cobalt plate at a temperature higher than a transition temperature, a transition from a hexagonal close-packed lattice structure to a face-centered cubic structure takes place at the transition temperature
Implementation Method 7
vacuum cooling is performed on the cobalt plate so that a temperature of the cobalt plate is lower than the transition temperature
Implementation Method 8
cold rolling is performed on the cobalt plate so that a rolling reduction is 17% or more and 35% or less
Implementation Method 9
the orientations of the magnetization easy axes C are uniformly aligned on the sputtering surface
Implementation Method 10
a magnetron sputtering method with an improved deposition rate is often used
Data Source
AI summary
[Object] To provide a sputtering target with further improved sputtering efficiency, and a method of producing the sputtering target.[Solving Means] In order to achieve the above-mentioned object, a sputtering target according to an embodiment of the present invention is a cobalt target having a sputtering surface and a purity of 99.95 wt % or more. An intensity ratio (I(002)+I(004))/(I(100)+I(002)+I(101)+I(102)+I(110)+I(103)+I(112)+I(004)) of X-ray diffraction peaks corresponding to a (100) plane, a (002) plane, a (101) plane, a (102) plane, a (110) plane, a (103) plane, a (112) plane, and a (004) plane of a hexagonal close-packed lattice structure along the sputtering surface is 0.85 or more.