MEMS CMOS Integration Thermal Stability Layer
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Solution Overview
Problem
The integration of microelectromechanical systems (MEMS) with complementary metal-oxide semiconductor (CMOS) devices is challenging due to the higher growth temperature of MEMS materials, which can damage the electrical performance of CMOS devices during high-temperature manufacturing processes.
Innovation Solution
A MEMS structure is fabricated with a thermal stability layer having a higher growth temperature than the conductive and interconnection layers, positioned between them, using materials like polysilicon, low-pressure silicon nitride, or amorphous silicon, and bonding substrates with fusion bonding to ensure reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a thermal stability material with higher growth temperature is used in the MEMS device, then thermal stability is improved, but the electrical performance of the CMOS device is damaged
Solution Approach 1:
The patent divides the device into two separate substrates: a first substrate for the CMOS device and a second substrate for the MEMS device. This segmentation allows the CMOS device to be fabricated at lower temperatures while the MEMS device can utilize high-temperature thermal stability materials, thus resolving the contradiction between thermal stability and electrical performance preservation
Solution Approach 2:
The patent introduces a bonding interface between the first substrate (CMOS) and second substrate (MEMS) as an intermediary connection. This allows the two devices with different temperature requirements to be integrated without directly exposing the CMOS device to high-temperature processing, thereby maintaining electrical performance while achieving thermal stability in the MEMS portion
2Adaptability or versatility
If the MEMS device is formed after the CMOS device using conventional integration, then integration is achieved, but the high growth temperature damages the CMOS device
Solution Approach 1:
The patent performs preliminary fabrication of the CMOS device on the first substrate before integrating the MEMS device. By completing the CMOS fabrication first at lower temperatures and then adding the MEMS structure with thermal stability material on a separate second substrate, the harmful thermal effects are avoided while achieving successful integration
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 configuration provides good thermal stability and reliability for the MEMS structure by isolating the high-temperature thermal stability layer from the lower-temperature CMOS components, preventing damage during high-temperature processing.
Implementation Method 1
the thermal stability layer is located in between the conductive layer and the interconnection structure. A growth temperature of a material of the thermal stability layer is higher than a growth temperature of a material of the conductive layer and a growth temperature of a material of the interconnection structure
Implementation Method 2
bonding substrates with fusion bonding to ensure reliability
Data Source
AI summary
A microelectromechanical system structure and a method for fabricating the same are provided. A method for fabricating a MEMS structure includes the following steps. A first substrate is provided, wherein a transistor, a first dielectric layer and an interconnection structure are formed thereon. A second substrate is provided, wherein a second dielectric layer and a thermal stability layer are formed on the second substrate. The first substrate is bonded to the second substrate, and the second substrate removed. A conductive layer is formed within the second dielectric layer and electrically connected to the interconnection structure. The thermal stability layer is located between the conductive layer and the interconnection structure. A growth temperature of a material of the thermal stability layer is higher than a growth temperature of a material of the conductive layer and a growth temperature of a material of the interconnection structure.