Composite Device Thermal Management via Via Electrodes
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Solution Overview
Problem
In composite devices with a semiconductor and an acoustic wave device on a silicon substrate, heat generated by the semiconductor device degrades the properties of the acoustic wave device, leading to frequency changes and insertion loss changes.
Innovation Solution
A composite device configuration where the acoustic wave device is directly or indirectly on a silicon oxide film on the silicon substrate with a piezoelectric layer, and heat is quickly released through via electrodes, minimizing heat transfer to the semiconductor device, and the use of a resin sealing layer and specific acoustic velocity relationships to confine energy in the piezoelectric layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the acoustic wave device is disposed on the silicon substrate including the semiconductor device, then the device size is reduced, but the acoustic wave device receives heat from the semiconductor device causing frequency change and insertion loss change
Solution Approach 1:
A heat dissipation layer is introduced between the semiconductor device and the acoustic wave device as an intermediary heat dissipation path. This layer includes a via hole extending from the first surface to the second surface of the substrate, allowing heat to be conducted away from the semiconductor device through the via hole to the opposite surface, preventing heat accumulation that would otherwise affect the acoustic wave device properties
Solution Approach 2:
The substrate is segmented into functional regions with distinct thermal management zones. The heat dissipation layer is selectively positioned between the semiconductor device and acoustic wave device, creating a thermal isolation zone that segments the heat flow paths. This allows the acoustic wave device to be disposed close to the semiconductor device for miniaturization while maintaining thermal independence through the segmented heat dissipation structure
2Area of stationary object
If the acoustic wave device is disposed close to the semiconductor device, then the device size is reduced, but heat transfer from the semiconductor device degrades the acoustic wave device performance
Solution Approach 1:
The heat dissipation layer acts as a thermal intermediary that facilitates heat removal from the semiconductor device through the substrate thickness direction. By providing this dedicated heat dissipation pathway, the acoustic wave device can be disposed in close proximity to the semiconductor device for area reduction while the intermediary heat dissipation structure prevents harmful thermal coupling
Solution Approach 2:
The heat dissipation layer is locally positioned between the semiconductor device and acoustic wave device, creating a localized thermal management solution. The via hole and heat dissipation structures are concentrated in the region where thermal interference occurs, providing targeted heat dissipation exactly where needed without affecting other device regions, thus enabling close spacing while maintaining performance
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 configuration prevents degradation of the acoustic wave device properties by efficiently dissipating heat away from the semiconductor device, reducing frequency changes and insertion loss, while allowing for a compact device design.
Implementation Method 1
an acoustic wave device including a silicon oxide film directly or indirectly disposed on the first main surface of the silicon substrate, a piezoelectric layer directly disposed on the silicon oxide film, and an IDT disposed on the piezoelectric layer
Implementation Method 2
the heat generated by the acoustic wave device is quickly released toward the silicon substrate and the outside through the via electrode
Data Source
AI summary
A composite device includes a silicon substrate including first and second main surfaces on opposite sides, a semiconductor device adjacent to at least one of the first and second main surfaces, and an acoustic wave device including a silicon oxide film directly or indirectly disposed on the first main surface of the silicon substrate, a piezoelectric layer directly disposed on the silicon oxide film, and an IDT disposed on the piezoelectric layer. The piezoelectric layer has a thickness of not greater than about 2.5λ where λ is a wavelength defined by an electrode finger pitch of the IDT.