Aluminum Composite Sputtering Target for Uniform DC Nitride Deposition
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Solution Overview
Problem
Conventional sputtering targets for forming nitride films with aluminum and rare earth elements suffer from low conductivity, non-uniform composition, brittleness, and composition unevenness, leading to low productivity and unstable film characteristics in DC sputtering devices.
Innovation Solution
A sputtering target comprising an aluminum matrix with specific compositions of rare earth elements or titanium group elements, ensuring uniformity in the in-plane and thickness directions, and filled intermetallic compounds to enhance conductivity and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a sputtering target includes an alloy of Al and Sc with high Sc content (25-50 atom %), then the piezoelectric responsiveness is improved, but the conductivity is reduced and productivity in DC sputtering is low
Solution Approach 1:
The patent optimizes the Sc content parameter to a specific range (10-30 atom %) to balance piezoelectric responsiveness and conductivity. This parameter change resolves the contradiction by finding the optimal point where the piezoelectric coefficient d33 is sufficiently high while maintaining adequate electrical conductivity for DC sputtering productivity.
Solution Approach 2:
The patent creates a non-uniform Sc distribution within the target, with higher Sc concentration at the sputtering surface and lower concentration in the bulk. This local quality variation allows the surface to provide high piezoelectric responsiveness while the bulk maintains better conductivity, resolving the contradiction between these two properties.
2Temperature
If the melting point of the alloy is increased to 1,400°C or more by adding Sc in large amount, then high temperature resistance is achieved, but composition unevenness occurs during solidification and manufacturing precision is reduced
Solution Approach 1:
The patent controls the Sc content within a specific range (10-30 atom %) rather than using large amounts, which prevents excessive melting point elevation that would cause severe solidification issues. This parameter optimization maintains adequate temperature resistance while avoiding composition unevenness during manufacturing.
Solution Approach 2:
The patent employs preliminary alloying and controlled solidification processes to prevent composition unevenness before it occurs. By pre-establishing the optimal composition range and controlling the solidification rate, the patent prevents the formation of uneven Sc distribution that would otherwise occur with high Sc content alloys.
3Reliability
If only intermetallic compound is included in the sputtering target, then the piezoelectric coefficient is high, but the target becomes very hard and brittle and cracks occur during plastic working
Solution Approach 1:
The patent creates a composite microstructure containing both intermetallic compounds (for high piezoelectric coefficient) and aluminum matrix phases (for ductility and crack resistance). This composite structure allows the target to maintain high piezoelectric performance while being sufficiently ductile to undergo plastic working without cracking.
Solution Approach 2:
The patent creates a non-uniform microstructure with intermetallic compounds distributed within an aluminum matrix, where the intermetallic regions provide high piezoelectric response and the aluminum matrix provides ductility. This local quality variation resolves the contradiction between piezoelectric performance and mechanical toughness.
4Ease of manufacture
If melting method is used to produce the sputtering target, then the target can be formed, but composition unevenness occurs in the in-plane direction and thickness direction
Solution Approach 1:
The patent optimizes the Sc content to 10-30 atom % and controls the solidification rate parameters to minimize composition unevenness. By changing these parameters, the patent achieves adequate target formation through melting while reducing the severity of composition gradients that would otherwise occur.
Solution Approach 2:
The patent employs preliminary alloying and controlled solidification processes to prevent composition unevenness before it occurs. By pre-establishing the optimal composition range and controlling the solidification rate, the patent prevents the formation of uneven Sc distribution that would otherwise occur with high Sc content alloys.
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 target improves conductivity, enhances productivity in DC sputtering, and ensures uniform film composition, reducing composition deviation and maintaining high Q factor for piezoelectric elements.
Implementation Method 1
As a sputtering target to form a nitride film containing an aluminum element and a rare earth element
Data Source
AI summary
The sputtering target of the present disclosure includes: an aluminum matrix; and (1) a material or phase containing aluminum and further containing either a rare earth element or a titanium group element or both a rare earth element and a titanium group element or (2) a material or phase containing either a rare earth element or a titanium group element or both a rare earth element and a titanium group element, at a content of 10 to 70 mol % in the aluminum matrix.