Amorphous Silicon Beam BAW Filter CMOS Integration
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Solution Overview
Problem
The integration of Bulk Acoustic Wave (BAW) filters and Bulk Acoustic Resonators (BAR) with CMOS processes is hindered by manufacturing complexities, leading to higher costs and increased processing due to their fabrication as standalone devices rather than integrated structures.
Innovation Solution
A method involving the formation of amorphous silicon beams with insulator materials and sacrificial layers to create upper and lower cavities, allowing for the integration of BAW filters or BARs within CMOS structures, utilizing a sacrificial material venting process to form cavities around the amorphous silicon beams, thereby reducing manufacturing complexity and cost.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If BAW filters and BARs are fabricated as standalone devices, then manufacturing precision and device performance are maintained, but manufacturing cost increases and fabrication processing complexity increases
Solution Approach 1:
The patent combines BAW filters and BARs with CMOS devices into a single integrated structure. The BAW filter and BAR share common components including the amorphous silicon beam, insulator layers, and cavity structures, allowing both acoustic devices and CMOS electronics to be fabricated together on the same substrate, thereby reducing manufacturing cost and simplifying fabrication processing
2Ease of manufacture
If BAW filters and BARs are integrated with CMOS structures, then manufacturing cost decreases and fabrication processing simplifies, but manufacturing precision may be compromised
Solution Approach 1:
The patent segments the fabrication process into distinct stages: first forming the amorphous silicon beam with precise thickness control (50-200 nm) through separate deposition, then forming the cavity structure, and finally integrating with CMOS devices. This segmentation allows each component to be optimized independently while maintaining overall integration benefits
Solution Approach 2:
The patent uses insulator materials (such as silicon dioxide) as intermediary layers between the amorphous silicon beam and the cavity structure, and between the acoustic devices and CMOS components. These intermediary layers provide mechanical support, electrical isolation, and stress management, ensuring manufacturing precision is maintained during integration
3Reliability
If cavities are formed around the amorphous silicon beam, then acoustic wave performance is improved, but the risk of beam damage during cavity formation increases
Solution Approach 1:
The patent forms the insulator material layer over the amorphous silicon beam before creating the cavity structure. This preliminary action provides a protective barrier that prevents direct exposure of the beam to harsh etching conditions during cavity formation, thereby reducing beam damage risk while still allowing the cavity to be formed for optimal acoustic wave performance
Data Source
AI summary
Bulk acoustic wave filters and/or bulk acoustic resonators integrated with CMOS processes, methods of manufacture and design structures are disclosed. The method includes forming at least one beam comprising amorphous silicon material and providing an insulator material over and adjacent to the amorphous silicon beam. The method further includes forming a via through the insulator material and exposing a material underlying the amorphous silicon beam. The method further includes providing a sacrificial material in the via and over the amorphous silicon beam. The method further includes providing a lid on the sacrificial material and over the insulator material. The method further includes venting, through the lid, the sacrificial material and the underlying material to form an upper cavity above the amorphous silicon beam and a lower cavity below the amorphous silicon beam, respectively.