Acoustic Wave Structure With Resistive Silicon Layers Against ESD
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Solution Overview
Problem
Acoustic wave devices with silicon support substrates and sealing members are prone to electrostatic discharge damage due to electric charge flow, leading to operation failures and breakages of functional electrodes.
Innovation Solution
The acoustic wave device incorporates a silicon support substrate with a higher electric resistance than the silicon cover layer, featuring a support layer made of insulating material and a piezoelectric body laminated on the substrate, which reduces the likelihood of electrostatic discharge by directing electric charges away from the functional electrode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a silicon support substrate and silicon sealing member are used to form a hollow space structure, then the device structure is simplified and manufacturing is easier, but electrostatic discharge damage occurs to the functional electrode due to electric charge flow into the silicon substrate
Solution Approach 1:
The patent applies local quality by creating a heterogeneous electrical resistance structure where the silicon support substrate has high electrical resistance in specific regions (under the functional electrode) and low electrical resistance in other regions. This is achieved through selective formation of conductive layers or doping patterns, allowing the substrate to provide mechanical support while preventing electrostatic discharge damage to the functional electrode by directing charge flow away from sensitive areas.
2Reliability
If the silicon support substrate has low electric resistance to dissipate charges, then electrostatic discharge damage is reduced, but electric charge flows into the functional electrode causing operation failure or breakage
Solution Approach 1:
The patent introduces an intermediary structure between the silicon support substrate and the functional electrode, such as a dielectric layer with controlled electrical properties or a patterned conductive layer. This intermediary acts as a charge diversion path that captures and redirects electrostatic charges away from the functional electrode, preventing direct charge flow while still allowing the silicon substrate to provide its mechanical support function.
3Reliability
If a support layer made of insulating material is added between the silicon support substrate and the functional electrode, then electrostatic discharge damage is prevented, but the device structure becomes more complex
Solution Approach 1:
The patent achieves multi-functionality by designing the support layer to serve multiple purposes simultaneously: it provides mechanical support to the functional electrode, acts as an electrical insulator to prevent charge flow into the silicon substrate, and serves as a platform for subsequent layer deposition. This consolidates multiple functions into a single structural element, reducing overall device complexity while maintaining reliability.
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 effectively minimizes electrostatic discharge damage to the functional electrode, enhancing the operational reliability and longevity of the acoustic wave device by ensuring electric charges flow to the lower-resistance cover layer, thus preventing damage.
Implementation Method 1
an electric resistance of the silicon support substrate is higher than an electric resistance of the silicon cover layer
Implementation Method 2
a piezoelectric body that is directly or indirectly laminated on the silicon support substrate
Data Source
AI summary
In an acoustic wave device, a piezoelectric body is directly or indirectly laminated on a silicon support substrate, and a functional electrode is provided on the piezoelectric body. A support layer is directly or indirectly laminated on the silicon support substrate, and the support layer is located outside the functional electrode when viewed in plan view. A silicon cover layer is provided on the support layer that includes an insulating material, and a space A is defined by the silicon support substrate, the support layer, and the silicon cover layer. The electric resistance of the silicon support substrate is higher than the electric resistance of the silicon cover layer.