BAW Resonator Electrodes Using Mo-Ta Alloy Against Oxidation
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Solution Overview
Problem
Existing bulk acoustic wave resonators face issues with oxidation of molybdenum electrodes, leading to reliability problems and high resistivity, which affects crystal orientation and manufacturing processes, while replacing molybdenum with other metals can lower crystal orientation quality.
Innovation Solution
The use of a molybdenum-tantalum alloy for the electrodes, with a tantalum content of 0.1 to 30 atomic percent, which improves etching resistance, reduces oxidation, and maintains low resistivity, allowing for better crystal orientation and manufacturing reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If molybdenum is used as electrode material, then low resistivity is achieved, but oxidation occurs leading to reliability problems
Solution Approach 1:
The patent uses a molybdenum-tantalum alloy composite material for the electrode, combining Mo and Ta in specific ratios (Mo: 70-99.9 atomic%, Ta: 0.1-30 atomic%). This composite approach leverages the low resistivity of molybdenum while incorporating tantalum's superior oxidation resistance, thereby resolving the contradiction between electrical conductivity and environmental stability.
Solution Approach 2:
The patent optimizes the compositional parameters of the alloy by specifying precise atomic percentage ranges for molybdenum and tantalum. By adjusting the Ta content within 0.1-30 atomic%, the material properties are tuned to achieve both low resistivity and high oxidation resistance, demonstrating parameter change as a solution to the technical contradiction.
2Manufacturing precision
If molybdenum is used as electrode material, then low resistivity is achieved, but crystal orientation quality deteriorates
Solution Approach 1:
The molybdenum-tantalum alloy serves as a composite electrode material that maintains good crystal orientation capability while improving resistivity stability. The specific composition range allows the material to support high-quality crystal growth during manufacturing while providing enhanced reliability through reduced oxidation.
3Object-affected harmful factors
If molybdenum-tantalum alloy is used instead of pure molybdenum, then oxidation resistance improves, but manufacturing complexity increases
Solution Approach 1:
The patent specifies precise compositional parameters (Mo: 70-99.9 atomic%, Ta: 0.1-30 atomic%) to achieve the desired oxidation resistance. By defining clear parameter ranges, the patent simplifies the manufacturing process compared to developing entirely new materials, as existing sputtering and deposition techniques can be adapted to create the alloy with controlled 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 molybdenum-tantalum alloy electrodes enhance environmental reliability by minimizing oxidation, improve crystal orientation, and provide robust etching-resistant properties, resulting in improved performance and stability of bulk acoustic wave resonators.
Implementation Method 1
an electric field is induced in the piezoelectric layer by electrical energy applied to the first and second electrodes, a piezoelectric phenomenon occurs in the piezoelectric layer due to the induced electric field, causing the resonator to vibrate in a predetermined direction. As a result, a bulk acoustic wave is generated
Data Source
AI summary
A bulk acoustic wave resonator includes a substrate; and a resonator including a first electrode, a piezoelectric layer, and a second electrode sequentially disposed on the substrate. Either one or both of the first electrode and the second electrode includes an alloy of molybdenum (Mo) and tantalum (Ta).