Monolithic BAW Resonator Fabrication for Multi-Frequency Integration
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Solution Overview
Problem
Current radio frequency front-end elements, particularly in mobile devices, face challenges in miniaturization and cost-effectiveness due to the need for multiple frequency BAW resonators, which are typically achieved using piezoelectric resonators that require complex and costly photolithography processes.
Innovation Solution
A monolithic integrated BAW resonator production method utilizing an imprint template with varying die heights to create grooves on a substrate, allowing for the sequential stacking of electrode and piezoelectric layers of different thicknesses, enabling the formation of resonators with distinct frequencies on a single chip without the need for extensive photolithography, thus simplifying the process and reducing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If multiple photolithography processes are used to form resonators of different frequencies, then manufacturing precision can be achieved, but device complexity and production costs increase
Solution Approach 1:
The patent segments the resonator formation process by creating separate etch holes for different resonator frequencies. Each etch hole is defined by a mask pattern with specific dimensions, allowing independent control of resonator thickness and frequency characteristics without requiring multiple photolithography steps on the same layer
Solution Approach 2:
The patent transitions from two-dimensional photolithography patterning to three-dimensional structure definition by using varying etch hole depths. Different resonator frequencies are achieved by controlling the depth of etch holes in the substrate, adding a vertical dimension to the patterning process and eliminating the need for multiple photolithography layers
2Manufacturing precision
If multiple photolithography processes are used to form resonators of different frequencies, then manufacturing precision can be achieved, but production costs increase
Solution Approach 1:
The patent merges the patterning of multiple resonator types into a single photolithography step by using a composite mask pattern that defines all etch hole locations and dimensions. This consolidation maintains manufacturing precision while significantly reducing production costs by eliminating redundant photolithography processes
3Volume of moving object
If BAW resonators of multiple frequencies are implemented on a single chip, then miniaturization is achieved, but manufacturing complexity increases
Solution Approach 1:
The patent applies local quality by creating spatially varying etch hole characteristics (different depths, positions, and dimensions) across the substrate to accommodate different resonator frequencies. Each region of the substrate is locally optimized for its specific resonator type while maintaining a unified manufacturing process
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
This method enables the production of miniaturized, multi-band BAW resonators with improved production flexibility and reduced costs by directly defining resonator thicknesses and frequencies using imprinting technology, avoiding the complexity of multiple photolithography steps.
Implementation Method 1
Press the mask material layer in a direction of the substrate by using the imprint template, to form, on the mask material layer through imprinting, a plurality of mask grooves with depths consistent with heights of the imprint dies
Implementation Method 2
Perform plasma etching on the substrate by using the mask material layer as a mask, to form, on a surface of the substrate, grooves that one-to-one correspond to positions of the several mask grooves
Implementation Method 3
Form, in the several grooves, bottom electrode layers, piezoelectric layers, and top electrode layers that are sequentially stacked, to form resonators of different frequencies
Data Source
AI summary
This application provides a monolithic integrated BAW resonator production method, including: preparing an imprint template; forming a mask material layer on a substrate; pressing the mask material layer by using the imprint template in a direction of the substrate, to form a mask groove; performing plasma etching on the substrate by using the mask material layer, as a mask, that is used to form the mask groove, to form, on the substrate, grooves that one-to-one correspond to positions of several mask grooves; and forming, in the several grooves, bottom electrode layers, piezoelectric layers, and top electrode layers that are sequentially stacked, to form resonators of different frequencies.