MEMS Device Top Metal Segmentation for Thermal Stability
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Solution Overview
Problem
Prior MEMS devices suffer from structural weakness due to temperature changes, leading to deformation and instability, which affects signal transmission performance and is exacerbated by manufacturing-induced stiction issues.
Innovation Solution
The MEMS device features a top metal layer with non-connected segments supported by pillars and a continuous lowest metal layer without disconnection areas above the signal transmission structure, along with a recess forming a buffer space, enhancing structural strength and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the second metal layer has a disconnection area above the signal transmission structure to prevent stiction and avoid electric field interference, then the signal transmission performance is improved, but the structural strength is weakened
Solution Approach 1:
The top metal layer is divided into multiple disconnected metal segments instead of a continuous layer. This segmentation allows the metal layer to maintain electrical functionality while reducing stiction risks and avoiding electric field interference, thereby improving signal transmission performance without requiring large disconnection areas that would weaken the overall structure.
Solution Approach 2:
The patent applies different structural configurations to different regions: the top metal layer has localized segments with gaps above the signal transmission structure to prevent stiction and electric field interference, while other regions maintain continuous metal structures to preserve structural strength. This local differentiation resolves the contradiction between signal transmission performance and structural strength.
2Strength
If the top metal layer has a continuous structure to maintain structural strength, then the structural stability is improved, but stiction occurs and signal transmission is affected by electric fields
Solution Approach 1:
The top metal layer is segmented into multiple disconnected segments rather than forming a continuous layer. This segmentation prevents stiction by reducing contact area and avoids electric field interference above the signal transmission structure, while the segments are positioned and sized to maintain adequate structural strength.
Solution Approach 2:
The patent addresses the contradiction by transitioning from a two-dimensional continuous metal layer to a three-dimensional segmented structure with controlled gaps. The segments are arranged in specific positions and orientations to simultaneously achieve stiction prevention, electric field shielding, and structural strength maintenance.
3Adaptability or versatility
If the MEMS structure is exposed to temperature increases, then the operational capability is maintained, but thermal deformation occurs affecting performance and stability
Solution Approach 1:
The patent modifies the structural parameters of the metal layers, specifically creating segmented top metal layers with controlled gaps and adjusting the thickness and material composition of different metal layers. These parameter changes reduce thermal stress accumulation and minimize thermal deformation, allowing the device to maintain operational capability under temperature increases while preserving structural stability.
Solution Approach 2:
The patent employs multiple metal layers with different material properties and thicknesses (e.g., tungsten, copper, aluminum) to create a composite structure. This composite approach balances thermal expansion coefficients and mechanical properties, reducing overall thermal deformation while maintaining operational capability across temperature variations.
Data Source
AI summary
The invention provides a MEMS device with enhanced structural strength. The MEMS device includes a plurality of metal layers, including a top metal layer with a plurality of metal segments. The metal segments are individually connected to an adjacent metal layer immediately under the top metal layer through at least one supporting pillar, and there is no dielectric layer between the metal segments and the adjacent metal layer immediately under the top metal layer. The metal layers except the top metal layer are respectively connected to their adjacent metal layers through at least one supporting pillar and a dielectric layer filling in between.