MEMS Electrical Component Passivation for Chemical Attack Isolation
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Solution Overview
Problem
Existing microelectromechanical systems (MEMS) devices face challenges in providing reliable protection for electrical components from chemical attacks and humidity, leading to potential short circuits and degradation, particularly due to imperfections in passivation and capping layers, which can result in cascading failures and reduced device lifetime.
Innovation Solution
A microelectromechanical systems device with a continuous insulating layer and a discontinuous or recessed passivation layer is used to provide electrical passivation and protection for the electrical components, mitigating defects and chemical attacks while maintaining electrostrictive/piezoelectric performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a continuous passivation layer is used to protect electrical components from chemical attacks and humidity, then reliability is improved, but manufacturing precision deteriorates due to defects such as pinholes and micro-cracks that can still form in the continuous layer
Solution Approach 1:
The passivation layer is segmented into discrete regions overlying each electrical element rather than forming a continuous layer. This segmentation ensures that defects in one region do not propagate to adjacent elements, isolating potential failure points while maintaining protective coverage over each individual element.
Solution Approach 2:
The passivation layer is applied selectively only where needed - specifically overlying each electrical element - rather than continuously across the entire substrate. This local quality approach provides protection precisely where chemical attacks would affect electrical components while avoiding the formation of continuous defect pathways.
2Reliability
If a thick passivation layer is used to ensure complete coverage and protection, then reliability is improved, but device complexity increases due to additional manufacturing steps and potential interference with electrostrictive/piezoelectric performance
Solution Approach 1:
The passivation structure is divided into discrete segmented regions rather than requiring a single thick continuous layer. This segmentation achieves comprehensive protection coverage across all electrical elements while simplifying the manufacturing process by allowing independent formation of each segmented region.
Solution Approach 2:
The passivation layer thickness and presence are optimized locally over each electrical element rather than uniformly across the entire device. This local quality approach ensures adequate protection where needed while minimizing interference with the electrostrictive/piezoelectric performance of the underlying components.
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 configuration enhances the protection of electrical components from chemical attacks, reduces cascading failure mechanisms, and extends device lifetime by ensuring reliable bonding and effective insulation, thereby improving manufacturing yields and component reliability.
Implementation Method 1
The ceramic member is configured to exhibit electrostrictive behaviour
Implementation Method 2
A typical electrical element may have a configuration where a thin film of a ceramic material showing ferroelectric behaviour, for example a piezoelectric material
Data Source
AI summary
The present invention relates to an electrical component for a microelectromechanical systems (MEMS) device, in particular, but not limited to, an electromechanical actuator. In one aspect, the present invention provides an insulated electrical component for a microelectromechanical systems device comprising: i) a substrate layer comprising first and second sides spaced apart in a thickness direction; ii) one or more electrical elements arranged over the first side of the substrate layer, wherein each of the one or more electrical elements comprises: a) a ceramic member; and b) first and second electrodes disposed adjacent the ceramic member such that a potential difference may be established between the first and second electrodes and through the ceramic member during operation; iii) a continuous insulating layer, or laminate of insulating layers, arranged to overlie each of the one or more electrical elements arranged on the first side of the substrate layer; and iv) a passivation layer, or laminate of multiple passivation layers, disposed adjacent to, and at least partially overlying, each of the one or more electrical elements so as to provide electrical passivation between the first and second electrodes of each of the one or more electrical elements; wherein: a) the passivation layer, or at least an innermost layer of the laminate of multiple passivation layers which is disposed adjacent each of the one or more underlying electrical elements, is discontinuous; and/or b) the laminate of multiple passivation layers is recessed at a side which faces away from each of the underlying electrical elements, wherein a recess is provided in a region overlying each of the one or more electrical elements, such that the laminate of passivation layers is thinner in a thickness direction across the recess compared to other non-recessed regions of the laminate of passivation layers.