MEMS Pressure Sensor and Microphone Through-Via Interconnects
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Solution Overview
Problem
Integrating MEMS pressure sensor, microphone, and motion sensor devices into the same integrated circuit manufacturing process poses unique challenges due to difficulties in electrically interconnecting these devices effectively.
Innovation Solution
The process involves forming MEMS devices using a substrate with dielectric layers, conductive polysilicon layers, and through-vias, allowing for the integration of pressure sensors, microphones, and motion sensors within the same IC manufacturing process through techniques like eutectic bonding and selective etching, enabling the creation of sealed cavities and electrical connections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If MEMS devices are integrated into the same IC manufacturing process, then chip density and functionality are enhanced, but electrical interconnection difficulties arise
Solution Approach 1:
The patent segments the electrical interconnection problem by creating separate through-vias for different device types (pressure sensor vias, microphone vias, motion sensor vias) that extend through different depths of the substrate. This allows each MEMS device type to have its own dedicated interconnection path, simplifying the overall integration while maintaining high chip density.
Solution Approach 2:
The patent transitions from planar electrical interconnection to three-dimensional through-via interconnection. By extending conductive vias vertically through the substrate to reach different MEMS device layers, the patent enables complex electrical routing in the vertical dimension, thereby enhancing chip density without increasing planar complexity.
2Ease of manufacture
If through-vias are formed to enable electrical interconnection, then electrical routing efficiency is improved, but manufacturing process complexity increases
Solution Approach 1:
The patent performs preliminary actions by forming through-vias and depositing conductive materials before final device assembly and bonding. This advance preparation of interconnection paths simplifies subsequent manufacturing steps and enables more efficient electrical routing without significantly increasing overall process complexity.
3Adaptability or versatility
If multiple MEMS device types are integrated, then functionality is enhanced, but interconnection challenges increase
Solution Approach 1:
The patent implements a universal through-via structure that serves multiple functions: pressure sensor vias connect to pressure sensing elements, microphone vias connect to microphone diaphragms, and motion sensor vias connect to accelerometer proof masses. This multi-functional interconnection approach enables integration of diverse MEMS device types while using a unified manufacturing methodology.
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
This approach enables the smooth integration and manufacturing of MEMS devices with pressure sensors, microphones, and motion sensors using known IC techniques, allowing for efficient electrical routing and mechanical structure formation, enhancing chip density and functionality.
Implementation Method 1
through techniques like eutectic bonding and selective etching, enabling the creation of sealed cavities and electrical connections
Data Source
AI summary
A method embodiment includes providing a MEMS wafer. A portion of the MEMS wafer is patterned to provide a first membrane for a microphone device and a second membrane for a pressure sensor device. A carrier wafer is bonded to the MEMS wafer. The carrier wafer is etched to expose the first membrane and a first surface of the second membrane to an ambient environment. A MEMS structure is formed in the MEMS wafer. A cap wafer is bonded to a side of the MEMS wafer opposing the carrier wafer to form a first sealed cavity including the MEMS structure and a second sealed cavity including a second surface of the second membrane for the pressure sensor device. The cap wafer comprises an interconnect structure. A through-via electrically connected to the interconnect structure is formed in the cap wafer.