MEMS Device Sealing with Independent Chamber Pressure Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing manufacturing processes for microelectromechanical devices struggle to achieve optimal operating conditions for devices with different pressure requirements, such as gyroscopes and accelerometers, due to limitations in pressure control and cross-talk between chambers.
Innovation Solution
A manufacturing process that involves forming microelectromechanical structures on a first semiconductor wafer and sealing them in separate chambers within a composite wafer structure. The second chamber is fluidically coupled to an external environment, allowing for independent pressure adjustment and preventing cross-talk.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If different devices are included in a same cavity with compromise pressure level, then device integration is simplified, but operating performance deteriorates due to suboptimal pressure conditions for each device
Solution Approach 1:
The package is divided into multiple sealed chambers, each containing specific microelectromechanical devices and maintaining independent pressure conditions. This segmentation allows each device to operate in its optimal pressure environment while being integrated in the same package, resolving the contradiction between manufacturing simplicity and operating performance.
2Manufacturing precision
If larger amount of getter is used to prevent saturation, then pressure control in low-pressure chamber is improved, but chamber dimensions must be increased beyond what is sufficient for the devices
Solution Approach 1:
The package is divided into multiple sealed chambers, each containing specific microelectromechanical devices and maintaining independent pressure conditions. This segmentation allows each device to operate in its optimal pressure environment while being integrated in the same package, resolving the contradiction between manufacturing simplicity and operating performance.
3Manufacturing precision
If getter is thermally activated during wafer bonding, then pressure reduction in chambers is achieved, but cross-talk occurs causing pressure changes in getter-free chambers and premature saturation
Solution Approach 1:
The getter is thermally activated in a controlled manner after wafer bonding is complete, rather than during the bonding process itself. This timing ensures that chambers are fully sealed before pressure reduction begins, preventing cross-talk and premature saturation while achieving the desired pressure levels in each chamber.
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 enables independent adjustment of operating conditions for each microelectromechanical device, improving performance reliability by eliminating cross-talk and ensuring accurate pressure control within each chamber.
Implementation Method 1
When the second wafer is bonded to the first wafer, for example by glass frit bonding or other wafer bonding technique
Implementation Method 2
the getter is thermally activated in order to absorb the non-noble gases present in the chamber, reducing pressure
Implementation Method 3
fluidically coupling the second chamber to an external environment through the second semiconductor wafer
Data Source
AI summary
A manufacturing process for microelectromechanical devices includes: on a first wafer forming a structural layer and a stop layer; defining a stop pad from the stop layer; forming a first microelectromechanical structure and a second microelectromechanical structure in the structural layer; forming a contact element protruding from a second wafer; sealing, at a first pressure, the first microelectromechanical structure in a first chamber and the second microelectromechanical structure and the stop pad in a second chamber; fluidically coupling the second chamber to an external environment; and sealing the second chamber at a second pressure. Sealing at the first pressure comprises bonding the second wafer to the first wafer so that the contact element rests on the stop pad. Fluidically coupling comprises defining fluidic passages at an interface between the contact element and the stop pad and opening an access hole through the second wafer in communication with the fluidic passages.