BAW Filter MIM Capacitor Layout for Steep Skirts and Low Loss
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing acoustic wave filters face challenges in achieving steep skirts and low insertion loss near band edges, with conventional capacitors being fragile, susceptible to electrostatic discharge, and consuming additional die area.
Innovation Solution
Incorporating a metal-insulator-metal (MIM) capacitor with buried electrodes in a dielectric layer, positioned laterally relative to the acoustic reflector, which enhances electromechanical coupling coefficients and reduces die size by integrating the capacitor without additional process steps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If MIM capacitors with thin electrodes are used, then device area is reduced, but quality factor (Q) decreases and reliability deteriorates due to susceptibility to ESD
Solution Approach 1:
The patent changes the electrode thickness parameter from thin to thick, which simultaneously improves reliability (ESD resistance) and quality factor while accepting increased area. This parameter change resolves the contradiction by prioritizing performance and reliability over minimal area consumption.
Solution Approach 2:
The patent transitions from planar capacitor designs to three-dimensional stacked capacitor structures, utilizing the vertical dimension to achieve higher capacitance density. This allows thick electrodes for reliability while maintaining effective area efficiency through vertical stacking.
2Reliability
If thicker electrodes are used in MIM capacitors, then quality factor (Q) increases, but device area consumption increases
Solution Approach 1:
The patent employs vertical stacking of multiple capacitor layers in the third dimension, allowing thick electrodes for high Q-factor while achieving high capacitance per unit area through the stacked configuration. This resolves the area-Q factor tradeoff by utilizing vertical space.
Solution Approach 2:
The patent uses composite dielectric materials with high permittivity in the MIM capacitor structure, which enables achieving required capacitance values with smaller physical area while maintaining thick electrodes for high quality factor and reliability.
3Area of stationary object
If circuit elements are placed within the resonator footprint, then die area is reduced, but manufacturing complexity increases
Solution Approach 1:
The patent merges the capacitor structure with the resonator footprint by placing circuit elements within the resonator area, creating a compact integrated structure. This is achieved through shared fabrication processes and integrated electrode patterns that combine multiple functions in the same spatial footprint.
Solution Approach 2:
The patent designs multi-functional structures where the same dielectric and electrode layers serve multiple purposes - both as resonator components and as capacitor elements. This universal design approach reduces overall die area while maintaining manufacturability through standardized fabrication processes.
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 MIM capacitor achieves higher quality factor (Q) and steeper filter skirts with reduced die size, providing improved filter performance and robustness against electrostatic discharge.
Implementation Method 1
a piezoelectric layer over the acoustic reflector and between the first electrode and the second electrode
Implementation Method 2
The circuit element includes conductive material buried in a dielectric layer and electrically connected to the terminal
Data Source
AI summary
Aspects of this disclosure relate to a bulk acoustic wave component that includes a bulk acoustic wave resonator, a capacitor, and a circuit element electrically connected to the bulk acoustic wave resonator. The capacitor includes an electrode buried in dielectric material. The circuit element includes conductive material in the dielectric layer. Related filters, multiplexers, radio frequency modules, radio frequency systems, wireless communication devices, and methods are disclosed.