FBAR Loading Element Tuning Through Sealing Layer Vent Holes
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Solution Overview
Problem
Tuning Film Bulk Acoustic Resonator (FBAR) devices at the wafer level during CMOS processing is challenging due to fabrication scale limitations on monolithic devices, making it difficult to adjust their frequency effectively.
Innovation Solution
Modifying the thickness of the loading element of an FBAR device by adding or removing material through a vent hole in the sealing layer, which is then plugged to adjust the resonant frequency, allowing for late-stage tuning during the CMOS manufacturing process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If FBAR devices are tuned at the wafer level during CMOS processing, then manufacturing integration is improved, but frequency adjustment precision deteriorates due to fabrication scale limitations
Solution Approach 1:
The patent divides the tuning process into two stages: wafer-level integration during CMOS processing and individual device tuning after fabrication. This segmentation allows the FBAR devices to be manufactured efficiently at the wafer level while enabling precise frequency adjustment to be performed individually on each device or small batches, thus resolving the contradiction between manufacturing integration and frequency adjustment precision.
Solution Approach 2:
The patent performs preliminary actions during CMOS processing by forming the FBAR devices and integrating them into the circuit board at the wafer level. The actual frequency tuning is then performed as a subsequent preliminary action before final device operation. This allows the manufacturing integration to be established early while leaving room for precise frequency adjustments to be made later through controlled material addition or removal.
2Manufacturing precision
If material is added or removed from the loading element to adjust frequency, then frequency matching is improved, but device structure complexity increases
Solution Approach 1:
The patent introduces an intermediary approach by using the vent hole as a controlled access point for material deposition or removal. Instead of directly modifying the loading element structure, the process uses the existing vent hole infrastructure as a mediator to deliver precise material adjustments. This intermediary mechanism enables frequency matching without requiring complex additional structures, as the vent hole serves dual purposes: manufacturing assistance and tuning access.
Solution Approach 2:
The patent achieves frequency matching by changing the physical parameters of the loading element, specifically its mass or thickness, through controlled material addition or removal. By adjusting these physical parameters rather than redesigning the overall device structure, the patent achieves precise frequency control while minimizing increases in device structure complexity. The changes are localized to the loading element parameters rather than the entire device architecture.
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
Enables precise adjustment of the FBAR device frequency, ensuring it matches the target frequency without altering the vibration characteristics caused by subsequent processing steps, thus improving the manufacturing efficiency and accuracy.
Implementation Method 1
FBAR devices including Bulk Acoustic Wave (BAW) filters may be formed and subsequently attached to a substrate or circuit board using, e.g., flip chip techniques. Alternatively, FBAR devices, including BAW filters, may be incorporated into an integrated circuit (IC) chip at the wafer level
Implementation Method 2
Modifying the thickness of the loading element of an FBAR device by adding or removing material through a vent hole in the sealing layer, which is then plugged to adjust the resonant frequency
Data Source
AI summary
Manufacturing a semiconductor structure including modifying a frequency of a Film Bulk Acoustic Resonator (FBAR) device though a vent hole of a sealing layer surrounding the FBAR device.