BAW Resonator Connection Layer Around Cavity for Thermal Stress
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Solution Overview
Problem
In 5G bulk-acoustic wave (BAW) filters, the increase in signal strength and power leads to elevated temperatures in the resonator, which current designs struggle to effectively dissipate, resulting in potential defects and performance issues due to thermal expansion differences between materials.
Innovation Solution
A bulk-acoustic wave resonator design featuring a connection layer made of high thermal conductivity materials like aluminum (Al), copper (Cu), or tungsten (W), with a barrier layer and seed layers, that surrounds a cavity and is connected to electrodes, serving as a heat transfer path to dissipate heat effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If high power is used to increase signal strength, then communication performance is improved, but temperature increases and heat dissipation becomes insufficient
Solution Approach 1:
The patent introduces a connection layer made of high thermal conductivity material (aluminum, copper, or tungsten) as an intermediary heat transfer path between the resonator structure and the external environment. This connection layer acts as a thermal mediator that conducts heat away from the resonator, enabling high power operation while maintaining temperature control.
Solution Approach 2:
The patent changes the thermal conductivity parameter of the connection structure by selecting materials with high thermal conductivity (aluminum, copper, or tungsten) and optimizing their thickness (50-200 nm). This parameter change enables efficient heat dissipation while maintaining the electrical connection function.
2Device complexity
If conventional connection structures are used, then device simplicity is maintained, but thermal stress causes swelling and structural integrity deteriorates
Solution Approach 1:
The patent employs a composite structure consisting of multiple layers: a barrier layer (5-20 nm thick) made of materials like titanium nitride, tantalum nitride, or aluminum oxide, and a connection layer made of high thermal conductivity materials. This composite structure provides both thermal management and mechanical stability, preventing swelling caused by thermal stress while maintaining electrical connection.
Solution Approach 2:
The patent applies different material properties to different parts of the connection structure: the barrier layer provides thermal stress resistance and adhesion, while the connection layer provides high thermal conductivity. This local differentiation of material qualities allows each layer to perform its specific function optimally, ensuring overall structural integrity under thermal load.
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 design prevents swelling of external connection electrodes and enhances heat dissipation, improving the reliability and performance of the resonator by managing thermal stress and maintaining structural integrity under high power conditions.
Implementation Method 1
a connection layer disposed on a substrate... the connection layer is disposed to surround a cavity, and is disposed to be connected to at least one of the first electrode and the second electrode
Implementation Method 2
a piezoelectric layer disposed to cover at least a portion of the first electrode... a second electrode disposed to cover at least a portion of the piezoelectric layer
Data Source
AI summary
A bulk-acoustic wave resonator is provided. The bulk-acoustic wave resonator comprises a substrate comprising an external connection electrode; a connection layer connected to the external connection electrode and disposed on the substrate; a first electrode disposed to cover at least a portion of the connection layer; a piezoelectric layer disposed to cover at least a portion of the first electrode; and a second electrode disposed to cover at least a portion of the piezoelectric layer. The connection layer may be disposed to surround a cavity and may be connected to the first electrode and the second electrode.