BAW RF Filter Topologies Using Single-Crystal Thin Films
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current bulk acoustic wave resonators using polycrystalline piezoelectric thin films degrade quickly at thicknesses below 0.5 um, limiting their performance at frequencies above 5 GHz, while single crystalline films maintain quality down to 0.4 um but pose challenges in manufacturing and transfer processes.
Innovation Solution
The development of manufacturing processes and structures for high-quality bulk acoustic wave resonators using single crystalline or epitaxial piezoelectric thin films, employing techniques like thin film transfer and sacrificial layers to enhance the quality factor and electro-mechanical coupling for high-frequency applications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If polycrystalline piezoelectric thin films are used in bulk acoustic wave resonators, then manufacturing is easier and cost is lower, but quality factor degrades quickly when thickness decreases below 0.5 um, limiting performance at frequencies above 5 GHz
Solution Approach 1:
The patent changes the material parameter from polycrystalline to single crystalline piezoelectric thin films, which fundamentally alters the quality factor characteristics. Single crystalline films maintain high quality factor even at thicknesses below 0.5 um, enabling operation at frequencies above 5 GHz while preserving manufacturing feasibility through established thin film deposition techniques
Solution Approach 2:
The patent employs composite material structures by integrating single crystalline piezoelectric thin films with appropriate substrate and electrode materials. This composite approach allows the resonator to achieve both high quality factor and electro-mechanical coupling while maintaining compatibility with existing manufacturing processes
2Reliability
If single crystalline piezoelectric thin films are used to maintain quality at thin thicknesses, then quality factor and electro-mechanical coupling improve, but manufacturing and transfer processes become more challenging
Solution Approach 1:
The patent applies preliminary action by pre-growing single crystalline piezoelectric thin films on sacrificial substrate layers before transfer. This preliminary crystalline growth ensures high quality factor and electro-mechanical coupling are achieved before the films are integrated into the final resonator structure, simplifying the overall manufacturing process
Solution Approach 2:
The patent uses sacrificial substrate layers as intermediary materials that facilitate the transfer of single crystalline piezoelectric thin films from growth substrates to final device substrates. These intermediary layers enable complex single crystalline film integration while maintaining manufacturing feasibility through standardized transfer 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
These processes enable the production of resonators with improved performance and cost-efficiency, capable of meeting the demands of high-frequency data communication requirements, such as 5G applications, with enhanced quality factor and reduced insertion loss.
Implementation Method 1
Bulk acoustic wave resonators (BAWR) using crystalline piezoelectric thin films are leading candidates for meeting such demands
Implementation Method 2
Single crystalline or epitaxial piezoelectric thin films grown on compatible crystalline substrates exhibit good crystalline quality and high piezoelectric performance even down to very thin thicknesses
Data Source
AI summary
An RF circuit device using modified lattice, lattice, and ladder circuit topologies. The devices can include four resonator devices and four shunt resonator devices. In the ladder topology, the resonator devices are connected in series from an input port to an output port while shunt resonator devices are coupled the nodes between the resonator devices. In the lattice topology, a top and a bottom serial configurations each includes a pair of resonator devices that are coupled to differential input and output ports. A pair of shunt resonators is cross-coupled between each pair of a top serial configuration resonator and a bottom serial configuration resonator. The modified lattice topology adds baluns or inductor devices between top and bottom nodes of the top and bottom serial configurations of the lattice configuration. These topologies may be applied using single crystal or polycrystalline bulk acoustic wave (BAW) resonators.