Monolithic Aluminum Alloy Sputtering Target Strain Control
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Solution Overview
Problem
Existing methods for manufacturing monolithic aluminum alloy sputtering targets face challenges such as high costs, complexity, and safety issues due to requirements for complex dies and energy-intensive processes like equal channel angular extrusion and cryogenic rolling, which also result in targets with inadequate mechanical strength and texture.
Innovation Solution
A method involving mechanical working of aluminum workpieces to create circular blanks, followed by recrystallization annealing and subsequent mechanical cold working to achieve desirable grain size and texture, with additional strain applied to the flange area for enhanced mechanical strength, using processes like cold rolling and pressing at temperatures below recrystallization temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If equal channel angular extrusion is used to improve mechanical strength, then mechanical strength is improved, but device complexity and manufacturing cost increase significantly
Solution Approach 1:
The patent replaces expensive, complex equal channel angular extrusion dies with simpler, more affordable cold working dies that can be easily manufactured and replaced. The invention uses conventional cold working equipment rather than specialized extrusion equipment, significantly reducing device complexity and cost while achieving the desired mechanical strength through controlled strain application.
Solution Approach 2:
The patent substitutes the complex mechanical extrusion system with a simpler cold working system. Instead of using equal channel angular extrusion machinery, the invention employs conventional rolling mills and pressing equipment to apply controlled strain to the aluminum alloy blank, achieving similar or better mechanical strength with simpler equipment.
2Strength
If cryogenic rolling is used to improve mechanical strength, then mechanical strength is improved, but safety issues and operational complexity increase
Solution Approach 1:
The patent converts the harmful effect of cryogenic temperatures (safety risks from liquid nitrogen) into a beneficial process by performing cold working at or near room temperature. The controlled strain applied during cold working at ambient conditions achieves the desired mechanical strength without the safety hazards associated with cryogenic materials handling.
Solution Approach 2:
The invention replaces expensive and hazardous cryogenic infrastructure with simple, conventional cold working equipment. By eliminating liquid nitrogen systems, the patent removes safety risks while maintaining the ability to achieve high mechanical strength through controlled plastic deformation at safe temperatures.
3Manufacturing precision
If recrystallization anneal is used to achieve desirable grain size and texture, then grain size and texture are improved, but mechanical strength decreases significantly
Solution Approach 1:
The patent applies cold working strain to the aluminum alloy blank before final annealing or before the target is put into service. By pre-straining the material to introduce dislocations and work hardening, the patent ensures that the material achieves high mechanical strength before any strength-reducing annealing occurs. The sequence is reversed compared to conventional processing: strain is applied first, then annealing is used to restore ductility without completely eliminating the strength benefits.
Solution Approach 2:
The patent applies different strain levels to different regions of the target blank. The flange area receives higher strain (20-60%) to maximize mechanical strength where it is most needed for structural support, while the sputter area receives moderate strain (10-50%) to maintain sputtering performance. This localized quality approach allows different regions to have optimized properties for their specific functions.
4Ease of manufacture
If monolithic structure is used to simplify manufacturing and eliminate debonding issues, then ease of manufacture is improved, but mechanical strength and deflection resistance decrease
Solution Approach 1:
The patent changes the material parameters of the monolithic aluminum alloy blank by controlling the strain level and strain distribution during cold working. By optimizing the strain magnitude (10-50% overall, with 20-60% in the flange area) and strain rate, the patent achieves a monolithic structure that simultaneously maintains manufacturing simplicity and achieves high mechanical strength comparable to bonded targets.
Solution Approach 2:
The patent creates a monolithic target with locally optimized properties: the flange area is heavily strained (20-60%) to maximize mechanical strength and deflection resistance where structural support is needed, while the sputter area is moderately strained (10-50%) to maintain sputtering performance. This local quality differentiation allows the monolithic structure to achieve both ease of manufacture and high mechanical strength.
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
The method produces monolithic aluminum alloy sputtering targets with improved mechanical strength and texture, reducing target deflection and maintaining manufacturing simplicity, while being more cost-effective and safer than prior methods, with yield strengths exceeding conventional targets and maintaining desirable crystallographic attributes.
Implementation Method 1
mechanically working an aluminum workpiece to produce a circular blank of the desired dimensions
Implementation Method 2
The blank is then annealed to recrystallize the blank and achieve desirable grain size and crystallographic texture
Implementation Method 3
a 10-50% strain is applied to the annealed blank via mechanical cold working
Implementation Method 4
After annealing, a 10-50% strain is applied to the annealed blank via mechanical cold working
Implementation Method 5
a strain of 20-60% is provided in a flange area of the target... provided by pressing the blank at a temperature lower than the recrystallization temperature
Data Source
AI summary
Aluminum or aluminum alloy sputter targets and methods of making same are provided. The pure aluminum or aluminum alloy is mechanically worked to produce a circular blank, and then the blank is given a recrystallization anneal to achieve desirable grain size and crystallographic texture. A 10-50% additional strain is provided to the blank step after the annealing to increase the mechanical strength. Further, in a flange area of the target, the strain is greater than in the other target areas with the strain in the flange area being imparted at a rate of about 20-60% strain. The blank is then finished to form a sputtering target with desirable crystallographic texture and adequate mechanical strength.