MEMS Electroacoustic Module Assembly With Pitch-Decoupled Interconnects
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Solution Overview
Problem
Current manufacturing processes for ultrasonic sensors with MEMS devices face challenges in flexibility, testing capabilities, and pitch alignment of electrical connection pads, leading to difficulties in managing thousands of connections and achieving efficient amplification of echo signals.
Innovation Solution
A manufacturing process that involves forming a reconstructed wafer with integrated circuits and transducers using a redistribution structure with microbumps and through-mold vias, allowing for decoupling of pitch and enabling high parallelization and thin membrane production, along with the use of different technologies for transducers and dice.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If transducers are arranged as close as possible to electronic circuitry to increase amplification performance, then echo signal amplification is improved, but the complexity of managing thousands of connections between transducers and ASICs increases
Solution Approach 1:
The system is divided into modular units where each ASIC handles a specific group of transducers. The wafer is segmented into multiple regions, each region containing a subset of transducers connected to dedicated ASICs. This segmentation reduces the connection complexity for each individual ASIC while maintaining close proximity for signal amplification.
Solution Approach 2:
A wafer-level interconnection structure acts as an intermediary between the transducer array and ASICs. This intermediary layer provides organized routing and connection management, reducing the complexity of directly connecting thousands of transducers to multiple ASICs while maintaining short signal paths for effective amplification.
2Ease of manufacture
If a single manufacturing technology is used for both driving circuits and reception circuits, then manufacturing process is simplified, but flexibility and adaptability of the system are reduced
Solution Approach 1:
The wafer fabrication process is designed to be universal and can accommodate different types of circuits (driving circuits and reception circuits) on the same wafer. The manufacturing methodology supports multiple functions and technologies, allowing flexibility in circuit design while maintaining a unified manufacturing approach.
Solution Approach 2:
The manufacturing process is made dynamic and adaptable, allowing the same wafer fabrication line to produce different types of circuits as needed. The process can be reconfigured to manufacture driving circuits, reception circuits, or mixed configurations, providing manufacturing flexibility without requiring separate dedicated production lines.
3Ease of manufacture
If pitch of electrical-connection pads in first wafer and second wafer are made the same, then alignment is simplified, but the ability to optimize each wafer independently is lost
Solution Approach 1:
A redistribution structure or adapter layer is introduced as an intermediary between the two wafers with different pitches. This intermediary layer performs pitch transformation and alignment, allowing each wafer to maintain its optimized pitch while still achieving proper alignment through the mediating structure.
Solution Approach 2:
The pitch parameter is changed or transformed between the two wafers using a redistribution structure. The first wafer can have one pitch optimized for transducer connections, while the second wafer has a different pitch optimized for ASIC connections, and the redistribution structure performs the parameter transformation between them.
4Ease of manufacture
If ASICs are tested only after the complete manufacturing process, then manufacturing flow is simplified, but reliability and defect detection capability are reduced
Solution Approach 1:
Testing is performed as a preliminary action during the manufacturing process, specifically after the wafer-level interconnection is completed but before final assembly. This preliminary testing allows defect detection early in the process, enabling rework or replacement before committing to final assembly, thereby improving reliability while maintaining manufacturing efficiency.
Data Source
AI summary
A process for manufacturing MEMS devices, includes forming a first assembly, which comprises: a dielectric region; a redistribution region; and a plurality of unit portions. Each unit portion of the first assembly includes: a die arranged in the dielectric region; and a plurality of first and second connection elements, which extend to opposite faces of the redistribution region and are connected together by paths that extend in the redistribution region, the first connection elements being coupled to the die. The process further includes: forming a second assembly which comprises a plurality of respective unit portions, each of which includes a semiconductor portion and third connection elements; mechanically coupling the first and second assemblies so as to connect the third connection elements to corresponding second connection elements; and then removing at least part of the semiconductor portion of each unit portion of the second assembly, thus forming corresponding membranes.