Hybrid Si/SiO2 Platform for Thermal Isolation in MEMS
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Solution Overview
Problem
Current ovenized platforms for microelectromechanical systems (MEMS) inertial measurement units face challenges in achieving high thermal isolation, stability, and compatibility with CMOS and MEMS fabrication processes, particularly due to the high thermal conductivity of silicon and the impracticality of glass substrates for thermal isolation.
Innovation Solution
A hybrid Si/SiO2 platform with alternating layers of silicon and silicon oxide, supported by silicon nitride, and integrated with thin-film electrical interconnects, temperature sensors, and heaters, allowing for precise temperature control and thermal isolation, while being fully compatible with standard CMOS and MEMS fabrication processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If long suspended silicon support structures are used to provide thermal isolation, then thermal isolation is improved, but structural rigidity and shock survival deteriorate
Solution Approach 1:
The patent employs a hybrid Si/SiO2 support structure where silicon provides mechanical strength and silicon oxide provides thermal isolation. This composite approach allows the support to simultaneously achieve rigidity for shock survival and low thermal conductivity for temperature stability, resolving the contradiction between thermal isolation and structural strength.
2Temperature
If glass substrate is used to facilitate thermal isolation, then thermal isolation is improved, but compatibility with CMOS and MEMS fabrication processes deteriorates
Solution Approach 1:
The patent changes the material parameter from glass to silicon oxide deposited on silicon substrates. This material substitution maintains the low thermal conductivity requirement while enabling full compatibility with standard CMOS and MEMS fabrication processes, as silicon oxide is a native material in these processes.
3Temperature
If silicon support structures are made very long to achieve thermal isolation, then thermal isolation is improved, but device complexity and manufacturing difficulty increase
Solution Approach 1:
By using silicon oxide within the silicon support structure, the patent achieves effective thermal isolation without requiring excessive length. The low thermal conductivity of silicon oxide provides thermal blocking capability within compact dimensions, simplifying the overall device design and manufacturing.
4Temperature
If low-conductivity material such as glass is used for platform, then thermal isolation is improved, but temperature gradient control and stress management deteriorate
Solution Approach 1:
The hybrid Si/SiO2 structure combines materials with complementary properties: silicon provides high thermal conductivity for uniform temperature distribution and stress management, while silicon oxide provides thermal isolation. This composite approach enables both effective thermal isolation and controlled temperature gradients.
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
The solution provides unprecedented bias and scale factor stability, high-temperature isolation, and shock tolerance, enabling precise temperature control to 0.01° C or less, suitable for both wafer-level and die-level sensor fabrication and assembly.
Implementation Method 1
alternating layers of silicon and silicon oxide configured to thermally isolate the platform from temperature fluctuations
Implementation Method 2
at least one thin-film electrical interconnect displaced on the top surface of said platform
Data Source
AI summary
The present invention generally relates to an ovenized platform and a fabrication process thereof. Specifically, the invention relates to an ovenized hybrid Si/SiO2 platform compatible with typical CMOS and MEMS fabrication processes and methods of its manufacture. Embodiments of the invention may include support arms, CMOS circuitry, temperature sensors, IMUs, and/or heaters among other elements.