MEMS Enclosure Pressure Control via Outgassing Barrier Layers
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Solution Overview
Problem
Existing MEMS devices face challenges in achieving multiple enclosure pressures within a single chip, as different sensors require varying pressures for optimal performance, such as low pressure for gyroscopes and high pressure for accelerometers.
Innovation Solution
The process involves using outgassing materials with adjustable exposed areas, thickness, and concentration, along with outgassing barrier layers, to create hermetically sealed enclosures with individually set pressures, employing eutectic solder as bonding material and wafer bonding techniques to integrate MEMS devices with CMOS ICs, allowing for optimal performance of multiple sensors within a single package.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple MEMS devices are integrated in a single chip, then device integration and compactness are improved, but the ability to provide different enclosure pressures for each sensor deteriorates
Solution Approach 1:
The patent applies local quality by introducing outgassing barrier layers selectively to specific enclosures. Each enclosure can have different barrier layer configurations (presence, thickness, material) to control the outgassing rate locally, thereby achieving different enclosure pressures within the same chip while maintaining high device integration.
2Manufacturing precision
If outgassing barrier layers are used to control enclosure pressure, then pressure control precision is improved, but device complexity increases
Solution Approach 1:
The patent employs parameter changes by varying the outgassing barrier layer properties (material composition, thickness, presence/absence) to control the outgassing rate and achieve different enclosure pressures. This allows precise pressure control through parameter adjustment rather than complex structural modifications.
3Adaptability or versatility
If different passivation layer configurations are used for different enclosures, then enclosure pressure differentiation is improved, but manufacturing process complexity increases
Solution Approach 1:
The patent applies segmentation by dividing the chip into multiple enclosures, each with independently configured outgassing barrier layers. This allows different passivation layer configurations for different enclosures while using standardized fabrication processes, thereby achieving pressure differentiation without proportionally increasing manufacturing complexity.
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 fabrication of high-performance, multi-axis inertial sensors with improved signal-to-noise ratio and reduced need for external amplification, by allowing each sensor to operate at its optimal pressure, thereby enhancing the functionality and efficiency of integrated MEMS devices.
Implementation Method 1
increasing the enclosure pressure by utilizing outgassing of a material
Implementation Method 2
employing eutectic solder as bonding material and wafer bonding techniques
Data Source
AI summary
Semiconductor manufacturing processes include providing a first substrate having a first passivation layer disposed above a patterned top-level metal layer, and further having a second passivation layer disposed over the first passivation layer; the second passivation layer has a top surface. The processes further include forming an opening in a first portion of the second passivation layer, and the opening exposes a portion of a surface of the first passivation layer. The processes further include patterning the second and first passivation layers to expose portions of the patterned top-level metal layer and bonding a second substrate and the first substrate to each other. The bonding occurs within a temperature range in which at least the exposed portion of the first passivation layer undergoes outgassing.