Conductive Vias for MEMS-IC Integration on Opposing Substrate Surfaces
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Solution Overview
Problem
Current methods for manufacturing semiconductor structures with integrated microelectromechanical systems (MEMS) devices and conductive vias face challenges in efficiently forming high-aspect-ratio conductive vias through substrates, which are crucial for effective electrical coupling between MEMS devices and integrated circuits.
Innovation Solution
The formation of electrically conductive vias extending partially or fully through substrates, coupled with techniques like photolithographic masking and etching, and subsequent thinning of substrates to expose these vias, allowing for the integration of MEMS devices either separately bonded or integrally formed on the substrate, enabling efficient electrical interconnection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high-aspect-ratio conductive vias are formed through substrates to enable electrical coupling between MEMS devices and integrated circuits, then electrical connectivity is improved, but manufacturing complexity and difficulty increase
Solution Approach 1:
The patent applies preliminary action by forming conductive vias through the substrate before bonding the MEMS device. This allows the vias to be created when the substrate is still accessible from both sides, making via formation easier. After bonding, the vias automatically align with contact pads on the MEMS device, eliminating the need for complex post-bonding via formation through the bonded interface.
Solution Approach 2:
The patent segments the electrical connection path into distinct components: conductive vias through the substrate, contact pads on the MEMS device, and interconnect structures. This segmentation allows each component to be optimized independently - vias can be formed using standard techniques on the substrate side, while contact pads are formed on the MEMS device side, simplifying the overall manufacturing process.
2Ease of manufacture
If substrates are thinned to expose conductive vias for MEMS integration, then ease of integration is improved, but structural strength and reliability may deteriorate
Solution Approach 1:
Instead of thinning the substrate to expose vias and then bonding MEMS devices, the patent inverts the sequence by first forming vias through the substrate, then bonding MEMS devices, and finally thinning the substrate. This inversion allows vias to be formed when the substrate is thick and strong, maintaining structural integrity during via formation, while still achieving via exposure after bonding for electrical connection.
Solution Approach 2:
The patent provides beforehand cushioning by maintaining the substrate at its full thickness during the critical via formation and bonding processes. This ensures the substrate has maximum strength and rigidity to withstand manufacturing stresses. Thinning is performed only after bonding is complete, at which point the MEMS device provides additional structural support.
3Adaptability or versatility
If MEMS devices are separately bonded to substrates with pre-formed vias, then manufacturing flexibility is improved, but alignment precision and connection reliability may worsen
Solution Approach 1:
The patent introduces alignment marks as intermediary features that facilitate precise registration between the substrate vias and MEMS device contact pads. These marks are formed on both the substrate and MEMS device before bonding, serving as reference points that guide alignment during the bonding process, thereby ensuring accurate via-to-contact-pad alignment even when devices are separately manufactured.
Data Source
AI summary
Methods of forming semiconductor devices comprising integrated circuits and microelectromechanical system (MEMS) devices operatively coupled with the integrated circuits involve the formation of an electrically conductive via extending at least partially through a substrate from a first major surface of the substrate toward an opposing second major surface of the substrate, and the fabrication of at least a portion of an integrated circuit on the first major surface of the substrate. A MEMS device is provided on the second major surface of the substrate, and the MEMS device is operatively coupled with the integrated circuit using the at least one electrically conductive via. Structures and devices are fabricated using such methods.