MEMS Sensor Cavity Segmentation for Getter Particle Sorption
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Solution Overview
Problem
Conventional MEMS rotation rate sensors face limitations in mechanical quality due to friction between residual gas and the mechanical oscillating structure, which restricts the achievable internal pressure and quality of the MEMS element, and existing methods struggle to maintain low internal pressure without affecting the sensor element.
Innovation Solution
A micromechanical component design that includes a structure between the sensor element and the getter, allowing desorbed particles to be sorbed into a separate area, thereby preventing interaction with the sensor element and enabling effective binding of residual gas molecules by the getter without compromising sensor properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stress or pressure
If a getter is used in the cavity to reduce internal pressure, then the internal pressure is reduced and held constant, but particles desorbed by the getter may interact with and degrade the sensor element
Solution Approach 1:
The cavity is segmented into a first cavity containing the sensor element and a second cavity containing the getter. This spatial segmentation prevents direct interaction between particles desorbed by the getter and the sensor element, while still allowing the getter to function in reducing internal pressure. The partition wall between the cavities enables separate functional zones.
Solution Approach 2:
A partition wall acts as an intermediary structure between the getter and the sensor element. This intermediary physically separates the getter's desorption process from the sensor element, preventing harmful particle interactions while maintaining the pressure-reducing function of the getter through the partition.
2Reliability
If the sensor wafer and cap wafer are bonded in a chamber to achieve low internal pressure, then high mechanical quality is achieved, but residual gas and outgassing from surfaces limit the achievable minimum internal pressure
Solution Approach 1:
The getter provides self-service by continuously absorbing residual gas and outgassing products from the cavity surfaces. This self-service mechanism actively maintains low internal pressure without requiring external intervention, overcoming the limitations imposed by residual gas and surface outgassing that would otherwise prevent achieving ultra-low pressures.
3Object-affected harmful factors
If a structure is added between the sensor element and getter to prevent particle interaction, then sensor protection is achieved, but device complexity increases
Solution Approach 1:
The cavity is divided into two separate cavities using a partition wall, creating distinct functional zones. This segmentation approach protects the sensor element from particle interaction while maintaining a relatively simple overall structure. The partition wall serves multiple functions: physical separation, structural support, and cavity definition.
Solution Approach 2:
The partition wall structure serves multiple functions simultaneously: it separates the getter from the sensor element to prevent particle interaction, provides structural support for the cavity configuration, and defines the boundaries of both cavities. This multi-functionality reduces the need for additional protective structures.
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 allows for targeted and cost-effective setting of internal pressure in MEMS components, achieving low pressures below 1 mbar while maintaining sensor quality and enabling separate pressure settings for rotation rate and acceleration sensors.
Implementation Method 1
a getter that acts particularly effectively and efficiently is thus made possible which binds residual gas molecules in the cavity
Implementation Method 2
a particle that is desorbed by the getter is sorbed onto and/or into an area of the micromechanical component
Implementation Method 3
a particle that is desorbed by the getter is sorbed onto and/or into an area of the micromechanical component that is spaced apart from the sensor element
Data Source
AI summary
A micromechanical component is provided, the micromechanical component enclosing a cavity, the micromechanical component including a sensor element situated in the cavity, and the micromechanical component including a getter situated in the cavity. The micromechanical component includes a structure, situated between the sensor element and the getter, which is designed in such a way that a particle that is desorbed by the getter is sorbed onto and/or into an area of the micromechanical component that is spaced apart from the sensor element.