Cavity Forming Member Strength via Composite Silicon Layers
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Solution Overview
Problem
As electronic devices miniaturize, the mechanical strength of the cavity forming members becomes insufficient, leading to potential failure under mechanical and thermal stress, compromising the reliability of the device.
Innovation Solution
The electronic device incorporates a dielectric layer and multiple layers with specific materials and structures, such as TiN, TaN, Ti, Ta, W, Au, Pt, Co, and Ni, to enhance the mechanical strength of the cavity, including a second layer with a region outside the first layer's outline and through holes for improved adhesion and etching processes, allowing for a strong and reliable cavity formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If the device size is reduced for miniaturization, then the area occupied by the cavity is reduced, but the mechanical strength of the cavity forming member becomes insufficient
Solution Approach 1:
The cavity forming member is constructed as a composite structure comprising a first layer (single crystal silicon layer) and a second layer (amorphous silicon layer) with different material properties. The first layer provides high mechanical strength to support the miniaturized cavity, while the second layer enables effective etching processes. This composite material approach allows the cavity area to be reduced for miniaturization while maintaining sufficient mechanical strength through the reinforced first layer.
2Volume of moving object
If the cavity size is reduced, then the device is miniaturized, but the cavity cannot be maintained under mechanical and thermal stress
Solution Approach 1:
The composite structure of the first layer (single crystal silicon) and second layer (amorphous silicon) provides enhanced mechanical and thermal stability. The single crystal silicon layer offers superior mechanical strength and thermal resistance, enabling the miniaturized cavity to maintain its integrity under mechanical and thermal stress during mounting and operation.
Solution Approach 2:
The first layer is specifically designed with higher mechanical strength properties localized at the cavity forming region. This layer acts as a structural reinforcement that locally supports the miniaturized cavity against external forces, ensuring the cavity can be maintained even at reduced volume under various stress conditions.
3Device complexity
If a single layer structure is used for the cavity lid, then the manufacturing process is simplified, but the mechanical strength against external forces is insufficient
Solution Approach 1:
The cavity lid is formed as a composite structure with a first layer of single crystal silicon and a second layer of amorphous silicon. The single crystal silicon layer provides exceptional mechanical strength to resist external forces such as crushing loads, while the amorphous silicon layer facilitates the etching process. This composite approach maintains relatively simple manufacturing procedures while significantly enhancing the mechanical strength against external forces compared to a single-layer structure.
Data Source
AI summary
An electronic device includes a substrate, a sidewall that is disposed on the substrate and forms a cavity, a first layer that is disposed on the sidewall and covers the cavity, a second layer that is formed on the first layer and has a region disposed outside an outline of the first layer in a plan view, a dielectric layer disposed below the region of the second layer disposed outside the outline of the first layer in a plan view, and a functional element disposed inside the cavity.