Al-Sc Sputtering Targets With Uniform Scandium Stoichiometry
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Solution Overview
Problem
Conventional sputtering targets for manufacturing piezoelectric thin films often suffer from non-uniform chemical stoichiometry, leading to inconsistent piezoelectric properties and device performance issues due to variations in scandium distribution across the surface and through the thickness, which results in product yield loss.
Innovation Solution
The development of aluminum-scandium (Al-Sc) alloys with high scandium content, up to 50 at%, are used to create sputtering targets with uniform chemical stoichiometry through controlled casting and thermomechanical processing, ensuring consistent scandium distribution and minimizing defects like pores and oxygen inclusions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional sputtering targets are used, then manufacturing process is simple, but chemical stoichiometry is non-uniform leading to inconsistent piezoelectric properties
Solution Approach 1:
The patent applies preliminary action by pre-alloying scandium into aluminum to create Al-Sc master alloys with controlled compositions (1-50 at% Sc) before sputtering. This preliminary alloying step ensures uniform scandium distribution at the atomic level in the target material, which then transfers uniformly to the deposited thin film, achieving consistent chemical stoichiometry and piezoelectric properties without requiring complex in-situ composition control during sputtering
Solution Approach 2:
The patent utilizes parameter changes by systematically varying the scandium concentration in the Al-Sc alloy from 1 to 50 at% to optimize the balance between piezoelectric performance and manufacturability. By adjusting this key compositional parameter, the patent achieves uniform chemical stoichiometry in the sputtered film while maintaining practical alloy fabrication complexity
2Reliability
If high scandium content is used, then piezoelectric response is enhanced, but scandium distribution uniformity deteriorates
Solution Approach 1:
The patent applies homogeneity by creating Al-Sc master alloys through controlled melting and mixing processes that ensure uniform atomic distribution of scandium throughout the aluminum matrix. The patent specifies alloys with 1-50 at% Sc where the scandium is homogeneously distributed at the atomic level, which ensures that when sputtered, the thin film receives consistent scandium flux across the entire target surface, maintaining both high piezoelectric response and compositional stability
Solution Approach 2:
The patent utilizes composite materials by creating Al-Sc intermetallic alloys with specific phases and microstructures. The controlled composition range (1-50 at% Sc) produces specific Al-Sc intermetallic compounds that combine the high piezoelectric response of scandium-rich phases with the structural stability of aluminum-based matrices, achieving both enhanced performance and uniform composition
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 resulting sputtering targets exhibit high chemical uniformity and microstructural integrity, enhancing the consistency of piezoelectric properties and reducing defects, thereby improving the reliability and yield of thin film deposition processes.
Implementation Method 1
The sputtering target and the substrate are placed in proximity to one another within the chamber and the target is bombarded with charged particles or ions. The high energy ions cause a portion of the sputtering target to dislodge and be re-deposited on the substrate.
Data Source
AI summary
Disclosed herein are aluminum alloys with scandium as the alloying element. The alloys have a high scandium content, as measured by atomic percentage, and are highly uniform, as described herein. Methods of forming articles from these alloys are also disclosed, such articles including sputtering targets that can be used to form thin films containing high amounts of scandium.