WLP BAW Device Through-Via Interconnect
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Solution Overview
Problem
Conventional Wafer-Level-Packaged (WLP) Bulk Acoustic Wave (BAW) devices face challenges in reducing device size due to space requirements for copper pillar connections, which increase the cross-sectional area, especially when multiple resonators and connections are involved.
Innovation Solution
The WLP BAW device incorporates a piezoelectric layer with a first interface opening and a bottom electrode lead, a WLP enclosure with a first through-WLP via, and an interconnect, allowing for a reduced device size by confining interconnects within the outer wall of the enclosure, eliminating the need for extra space between the enclosure and connections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If copper pillar connections are used for external electrical connections, then reliable electrical connection is achieved, but device cross-sectional area increases
Solution Approach 1:
The patent transitions from planar copper pillar connections to three-dimensional through-WLP vias that extend vertically through the encapsulant. This vertical dimension allows electrical connections to pass through the encapsulant material rather than requiring lateral space, thereby reducing the device's cross-sectional area while maintaining connection reliability.
Solution Approach 2:
The through-WLP vias are nested within the encapsulant material, with the interconnect structures contained inside the encapsulated resonator structure. This nesting approach allows the connection paths to be integrated within the existing device volume rather than requiring additional external space.
2Adaptability or versatility
If multiple BAW resonators and copper pillar connections are included, then functional capability is enhanced, but device size increases
Solution Approach 1:
The through-WLP via structure serves multiple functions simultaneously: it provides electrical connection pathways for multiple resonators, acts as an interconnect structure, and integrates within the encapsulant material. This multi-functional design allows multiple resonators to be connected without proportionally increasing device area.
Solution Approach 2:
The patent combines the encapsulant material with the connection pathway function by making the encapsulant itself transparent to the through-WLP vias. This merging of structural and functional roles eliminates the need for separate connection structures that would increase device area.
3Area of stationary object
If through-WLP vias are used instead of copper pillar connections, then device size is reduced, but manufacturing complexity increases
Solution Approach 1:
The encapsulant material is designed to serve dual purposes: providing mechanical protection and encapsulation while simultaneously serving as the medium through which the through-WLP vias pass. This multi-functionality reduces the need for additional structural elements that would increase manufacturing complexity.
Solution Approach 2:
The patent extracts the connection pathway function from separate copper pillar structures and integrates it directly into the encapsulant material formation process. This extraction simplifies the overall structure by eliminating the need for distinct connection components.
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 design reduces the overall size of the BAW device without compromising external electrical connections, enhancing packaging efficiency and minimizing the device's cross-sectional area.
Implementation Method 1
The transducer 18 includes a piezoelectric layer 20
Implementation Method 2
The reflector 16 is typically formed by a stack of reflector layers (not shown), which alternate in material composition to produce a significant reflection coefficient at the junction of adjacent reflector layers
Data Source
AI summary
The present disclosure relates to a wafer-level packaged (WLP) bulk acoustic wave (BAW) device, which includes a BAW resonator, a WLP enclosure, and an interconnect. The BAW resonator includes a piezoelectric layer with an opening, a bottom electrode lead underneath the opening, and an interface structure extending over the opening and in contact with the bottom electrode lead through the opening. The WLP enclosure includes a cap, an outer wall that extends from the cap toward the piezoelectric layer to form a cavity, and a through-WLP via that extends through the cap and the outer wall and is vertically aligned with the opening of the piezoelectric layer. A portion of the interface structure is exposed to the through-WLP via. The interconnect is formed in the through-WLP via and electrically connected to the interface structure.