MEMS-CMOS Integration via Bonding and Composite Structures
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Solution Overview
Problem
Current MEMS fabrication methods face challenges in reducing manufacturing and packaging costs while integrating micromechanical devices and electronic circuits, such as CMOS devices, in a single process, and in addressing issues like stiction during the release of MEMS devices.
Innovation Solution
The integration of MEMS and CMOS devices is achieved through bonding techniques like eutectic bonding, fusion bonding, and thermo-compression bonding, with intermediate layers and processes like oxide deposition, polysilicon layer formation, and vapor HF stop layers to facilitate the formation of MEMS structures and improve bonding strength and reduce stiction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If MEMS devices and CMOS devices are fabricated separately and then bonded, then device functionality is maintained, but manufacturing cost and process complexity increase
Solution Approach 1:
The patent combines MEMS device fabrication and CMOS device fabrication into a single integrated process flow. Both device types are manufactured on the same substrate simultaneously, eliminating the need for separate fabrication and bonding processes. This merging of processes directly reduces manufacturing cost and simplifies the overall production complexity while maintaining the functional integrity of both MEMS and CMOS components.
2Reliability
If bonding techniques are used to integrate MEMS and CMOS devices, then electrical connectivity is improved, but manufacturing complexity increases
Solution Approach 1:
The patent incorporates electrical interconnection structures and bonding interfaces directly into the fabrication process before the devices are fully assembled. By preparing the bonding surfaces and electrical contacts in advance during the same fabrication process, the need for complex post-fabrication bonding operations is eliminated. This preliminary action ensures reliable electrical connectivity while avoiding the complexity of separate bonding steps.
3Productivity
If thin structure layers are formed to enhance mechanical movement, then MEMS performance is improved, but structural stability may be compromised
Solution Approach 1:
The patent employs composite material structures where thin MEMS layers are integrated with thicker CMOS support structures on the same substrate. The thin layers provide the necessary mechanical movement capability for MEMS functionality, while the composite integration with the substrate and CMOS layers provides the structural stability and mechanical support needed to prevent failure. This composite approach allows both thin-layer performance and overall structural integrity.
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 allows for cost-effective manufacturing of MEMS devices with improved bonding strength and reduced stiction, enabling efficient integration of mechanical and electronic functionalities in a single process.
Implementation Method 1
bonding techniques such as eutectic bonding
Implementation Method 2
bonding techniques such as eutectic bonding, fusion bonding
Implementation Method 3
bonding techniques such as eutectic bonding, fusion bonding, and thermo-compression bonding
Data Source
AI summary
A device includes a carrier having a plurality of cavities, a micro-electro-mechanical system (MEMS) substrate bonded on the carrier, wherein the MEMS substrate comprises a first side bonded on the carrier, a moving element over a bottom electrode, wherein the bottom electrode is formed of polysilicon and a second side having a plurality of bonding pads and a semiconductor substrate bonded on the MEMS substrate, wherein the semiconductor substrate comprises a top electrode and the first moving element is between the top electrode and the bottom electrode.