Diamond Film BAW Resonator Structure for Self-Heating Dissipation
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Solution Overview
Problem
The self-heating phenomenon in film bulk acoustic wave resonators due to low thermal conductivity of air leads to reduced power capacity, as Joule heat accumulates and cannot be effectively dissipated, limiting their performance in high-frequency and miniaturized radio frequency front-end devices.
Innovation Solution
A bulk acoustic wave resonator structure comprising a silicon substrate with a first and second diamond film layer, a piezoelectric layer, and strategically formed cavities and electrodes, including through holes for enhanced heat dissipation, allowing for improved thermal management and increased power capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an air cavity is used between the bottom electrode and substrate, then acoustic wave total reflection is achieved, but thermal conductivity becomes approximately zero causing Joule heat accumulation
Solution Approach 1:
The patent changes the physical state and material composition of the cavity from air (zero thermal conductivity) to a controlled atmosphere with specific thermal conductivity parameters (0.026-0.035 W/m·K), transforming the thermal insulation property into a controllable thermal management parameter that enables heat dissipation while maintaining acoustic reflection
Solution Approach 2:
The patent introduces a gas filling the cavity as an intermediary medium that mediates between the acoustic wave reflection requirement and thermal dissipation requirement. The selected gas provides appropriate acoustic impedance for total reflection while having sufficient thermal conductivity to carry heat away from the resonator structure
2Device complexity
If heat can only spread along the substrate surface, then device structure is simple, but self-heating phenomenon seriously reduces power capacity
Solution Approach 1:
The patent transitions heat dissipation from a two-dimensional substrate surface path to a three-dimensional pathway by utilizing the cavity volume and introducing gas convection currents. This adds vertical and circulatory heat transport dimensions, dramatically increasing heat dissipation efficiency without complicating the device structure
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 enhanced heat dissipation performance reduces the resonator's temperature, thereby significantly improving its power capacity by more than 30% compared to conventional designs.
Implementation Method 1
an electrical signal is converted into an acoustic signal through a piezoelectric material
Implementation Method 2
the thermal conductivity of air is approximate to zero, so that Joule heat generated by the resonator will accumulate inside the resonator
Data Source
AI summary
A bulk acoustic wave resonator capable of improving a power capacity includes a substrate, a first diamond film layer, a piezoelectric layer and a second diamond film layer; a first cavity is formed in the first diamond film layer; a bottom electrode is arranged on the first diamond film layer and located in the piezoelectric layer; a second cavity is formed in the second diamond film layer, and a top electrode is arranged in the second cavity on the piezoelectric layer; a first through hole is formed between the top electrode and the bottom electrode, and the first through hole penetrates through the top electrode and the bottom electrode, and communicates with the first cavity and the second cavity; and a second through hole is further formed in the second diamond film layer, and the second through hole communicates with the second cavity and the outside.