AlN Dopant Composition for BAW Filter Spurious Wave Suppression
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Acoustic wave filters, particularly bulk acoustic wave (BAW) filters, face issues with spurious acoustic waves due to non-zero Poisson's ratio in piezoelectric materials, leading to degraded frequency response and undesirable signal interference.
Innovation Solution
Doping aluminum nitride (AlN) with elements like beryllium (Be), magnesium (Mg), zinc (Zn), calcium (Ca), strontium (Sr), lithium (Li), and sodium (Na) to enhance the performance of acoustic wave resonators, which are then used in BAW filters, including film bulk acoustic wave resonators, Lamb wave resonators, and surface mounted resonators, to improve coupling factor and quality factor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If aluminum nitride is used as piezoelectric material in BAW filters, then the filter can operate at radio frequencies, but spurious acoustic waves are generated due to non-zero Poisson's ratio, degrading frequency response and causing signal interference
Solution Approach 1:
The patent applies parameter changes by doping aluminum nitride with specific elements (Sc, Y, In, Ga) to modify the material's Poisson's ratio. This changes the physical parameters of the piezoelectric material to reduce spurious acoustic wave generation while maintaining the desired frequency response characteristics of the BAW filter
Solution Approach 2:
The patent uses composite materials by creating doped aluminum nitride compounds where aluminum nitride is combined with dopant elements (Sc, Y, In, Ga). These composite piezoelectric materials exhibit improved properties that reduce harmful spurious waves while maintaining operational reliability at radio frequencies
2Reliability
If aluminum nitride is doped with multiple elements to reduce spurious waves, then frequency response improves, but manufacturing complexity increases
Solution Approach 1:
The patent simplifies the doping process by focusing on changing a single key parameter (Poisson's ratio) through doping with specific elements. This approach reduces manufacturing complexity compared to attempting to optimize multiple material properties simultaneously, while still achieving improved frequency response
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 doped AlN materials reduce spurious acoustic waves, enhancing the frequency response and operational characteristics of BAW filters by creating a barrier that scatters and suppresses transverse waves, thereby improving the overall performance of acoustic wave filters.
Implementation Method 1
The doped AlN materials reduce spurious acoustic waves, enhancing the frequency response and operational characteristics of BAW filters by creating a barrier that scatters and suppresses transverse waves
Implementation Method 2
An acoustic wave resonator can include a piezoelectric material
Data Source
AI summary
Disclosed is an acoustic wave resonator comprising a substrate material formed of aluminum nitride (AlN) doped with one or more of beryllium (Be), strontium (Sr), and sodium (Na) to enhance performance of the acoustic wave resonator.