Heterogeneous CMOS MEMS Integration via Wafer Bonding
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Solution Overview
Problem
Embedding micro-electro-mechanical system (MEMS) infrared (IR) detectors with complementary metal oxide semiconductor (CMOS) integrated circuits poses challenges due to the limited thermal budget available for post-CMOS processes, hindering the development of compact, high-performance CMOS devices integrated with MEMS IR sensors.
Innovation Solution
A method involving the integration of CMOS and MEMS components, where a CMOS substrate with interconnections is bonded to a MEMS substrate, forming an integrated stack, and post-integration processing is performed to complete the CMOS device integrated with the MEMS module, enabling efficient thermal management and compact design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If MEMS IR detectors are embedded with CMOS integrated circuits, then compactness and cost performance are improved, but the limited thermal budget for post CMOS processes deteriorates
Solution Approach 1:
The patent divides the integration process into two separate substrates: a first substrate containing the CMOS integrated circuit and a second substrate containing the MEMS IR detector. This segmentation allows independent processing of each substrate with appropriate thermal budgets, while achieving compact integration through subsequent bonding. The CMOS substrate can be processed with standard thermal budgets, while the MEMS substrate can withstand higher temperatures required for MEMS fabrication.
Solution Approach 2:
The patent transitions from planar integration to three-dimensional stacking by bonding the MEMS substrate to the CMOS substrate. This vertical integration approach reduces the device footprint (area) while maintaining separate thermal processing paths for each substrate layer, effectively resolving the contradiction between compactness and thermal budget constraints.
2Area of stationary object
If MEMS IR detectors are embedded with CMOS integrated circuits, then compact design is improved, but manufacturing complexity increases
Solution Approach 1:
By segmenting the device into separate CMOS and MEMS substrates, each can be manufactured using established, independent process flows. The CMOS substrate is fabricated using standard CMOS processes, while the MEMS substrate is processed using dedicated MEMS fabrication techniques. This segmentation simplifies manufacturing compared to attempting monolithic integration, as each substrate can be optimized for its specific process requirements.
Solution Approach 2:
The patent performs preliminary actions by fabricating and preparing both substrates separately before final integration. The CMOS substrate is fully processed with its bonding interface prepared in advance, and the MEMS substrate is independently fabricated with its structures completed. This preliminary separation and preparation of substrates reduces manufacturing complexity during the final integration stage.
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 the creation of compact, high-performance CMOS devices integrated with MEMS IR sensors, enhancing thermal imaging capabilities and reducing device footprint while optimizing process performance.
Implementation Method 1
bonding the CMOS substrate to the MEMS substrate by bonding the CMOS substrate bonding layer and the MEMS substrate bonding layer together
Data Source
AI summary
A complementary metal oxide semiconductor (CMOS) device integrated with micro-electro-mechanical system (MEMS) components in a MEMS region is disclosed. The MEMS components, for example, are infrared (IR) thermosensors. The MEMS sensors are integrated on the CMOS device heterogeneously. For example, a CMOS wafer with CMOS devices and interconnections as well as partially processed MEMS modules is bonded with a MEMS wafer with MEMS structures, post CMOS compatibility issues are alleviated. Post integration process to complete the devices includes forming contacts for interconnecting the sensors to the CMOS components as well as encapsulating the devices with a cap wafer using wafer-level vacuum packaging.