Wafer-Level BAW Filter Assembly for Mechanical Stability
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Solution Overview
Problem
The existing methods for fabricating Bulk Acoustic Wave (BAW) filters face challenges in achieving mechanical stability during the thinning process of semiconductor wafers, which can lead to warping and cracking, and require additional mechanical support to ensure precise attachment and packaging without electrical interconnects.
Innovation Solution
A wafer level assembly is formed by attaching a second semiconductor wafer with a cavity to a first wafer containing a BAW structure, providing mechanical stability during thinning and allowing for precise positioning and bonding without electrical interconnects, using a controlled environment for attachment and stabilization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If wafer thinning is performed to create thinner BAW filters, then the size and thickness of the filter are reduced, but mechanical stability deteriorates leading to warping and cracking
Solution Approach 1:
A support wafer is attached to the BAW filter wafer before the thinning process begins. This preliminary action provides mechanical stability during subsequent processing steps, preventing warping and cracking that would occur if thinning were performed on the unsupported wafer alone.
Solution Approach 2:
The support wafer acts as an intermediary mechanical support structure between the BAW filter wafer and the processing equipment. It provides the necessary rigidity and stability during thinning and bonding operations, enabling precise attachment and packaging without electrical interconnects.
2Ease of manufacture
If wafer thinning is performed without additional support, then processing simplicity is maintained, but manufacturing precision deteriorates due to warping and cracking
Solution Approach 1:
The support wafer is attached in advance to prevent warping and cracking during thinning, ensuring that the wafer maintains its dimensional stability and flatness throughout subsequent processing steps, thereby achieving precise attachment without complex corrective measures.
Data Source
AI summary
A method of forming a packaged electronic device includes fabricating a MEMS structure, such as a BAW structure, on a first semiconductor wafer substrate; forming a cavity in a second semiconductor wafer substrate; and mounting the second substrate on the first substrate such that the MEMS structure is positioned inside the cavity in the second substrate. A wafer level assembly and an integrated circuit package are also described.