Combined MEMS Device Pressure Control via Getter Extraction
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Solution Overview
Problem
Conventional combined MEMS devices face challenges in controlling pressure set-points and process spread due to the complexity of manufacturing processes, particularly when using getter regions or access channels to adjust pressures within microelectromechanical structures.
Innovation Solution
A manufacturing process for combined MEMS devices involves forming first and second microelectromechanical structures on a semiconductor die, bonding a cap with a bonding region to define cavities for each structure, and creating an access channel through the cap to control pressure in one cavity while maintaining hermetic sealing in the other.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a getter region is introduced into one of the structures to adjust pressure, then the pressure control capability is improved, but the manufacturing complexity increases
Solution Approach 1:
The patent extracts the pressure adjustment function from the device structure by introducing a getter region that is physically separated from the main microelectromechanical structures. The getter region is placed in a dedicated cavity that is hermetically sealed, allowing independent pressure control without interfering with the operation of the accelerometers or gyroscopes. This extraction resolves the contradiction by providing pressure control capability while maintaining manufacturing simplicity through modular integration.
2Manufacturing precision
If an access channel is created through a structure to adjust pressure, then the pressure adjustment capability is improved, but the hermetic sealing complexity and manufacturing costs increase
Solution Approach 1:
The patent eliminates the need for access channels by extracting the pressure adjustment mechanism into a separate hermetically sealed cavity containing a getter region. Instead of creating channels through the device structure that require complex laser melting and hermetic sealing operations, the pressure is adjusted in an isolated cavity. This approach resolves the contradiction by providing pressure adjustment capability while avoiding the manufacturing complexity associated with hermetic sealing of access channels.
Solution Approach 2:
The getter region acts as an intermediary element that enables pressure adjustment without requiring direct access channels to the sensor cavities. The getter is contained within a separate cavity that can be independently processed and sealed, serving as a mediator between the external environment and the internal sensor cavities. This intermediary approach resolves the contradiction by providing pressure control while maintaining the hermetic integrity of the sensor structures.
3Manufacturing precision
If getter regions are integrated into the manufacturing process, then the pressure control capability is improved, but the manufacturing time and costs increase
Solution Approach 1:
The patent merges the getter integration process with the existing manufacturing流程 by forming the getter region and its hermetic cavity using the same batch processing techniques as the main device structures. The getter material is deposited, patterned, and sealed in the same fabrication run as the accelerometers and gyroscopes, eliminating the need for separate manufacturing steps. This merging resolves the contradiction by providing pressure control capability while avoiding additional manufacturing time and costs through integrated processing.
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 process allows for efficient and cost-effective manufacturing of combined MEMS devices with distinct pressure settings for each microelectromechanical structure, reducing manufacturing complexity and avoiding the need for additional complex processing steps.
Implementation Method 1
bonding a cap with a bonding region to define cavities for each structure
Implementation Method 2
creating an access channel through the cap to control pressure in one cavity
Implementation Method 3
the bonding including implementing, prior to forming said access channel (22), a first bonding phase, at a controlled pressure having a first value (P1), being a function of the pressure value inside said second cavity (20b), implementing, after forming said access channel (22), a second bonding phase, at a respective controlled pressure having a second value (P2), being a function of the pressure value inside said first cavity (20a), wherein, due to said second bonding phase, the bonding region (14) deforms to hermetically close said first cavity (20a) with respect to said access channel (22)
Data Source
AI summary
A process for manufacturing a combined microelectromechanical device includes forming, in a die of semiconductor material, at least a first and a second microelectromechanical structure, performing a first bonding phase to bond a cap to the die via a bonding region or adhesive to define at least a first and a second cavity at the first and, respectively, second microelectromechanical structures, the cavities being at a controlled pressure, forming an access channel through the cap in fluidic communication with the first cavity to control the pressure value inside the first cavity in a distinct manner with respect to a respective pressure value inside the second cavity, and performing a second bonding phase, after which the bonding region deforms to hermetically close the first cavity with respect to the access channel.