Vibration Element Mounting on Planarized Insulating Layers
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Solution Overview
Problem
The existing method for manufacturing vibration devices, as described in JP-A-2021-057755, faces issues with the poor planarity of the insulating layer's surface, leading to unstable bonding between the vibration element and the wiring layer.
Innovation Solution
The method involves preparing a base with a semiconductor substrate and a first insulating layer, forming a second insulating layer on the opposite side, planarizing this surface through polishing, forming a mount electrode, and bonding a vibration element to the mount electrode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an insulating layer including a plurality of wiring layers is formed on the base substrate, then the circuit element can be properly insulated and connected, but the surface planarity deteriorates causing unstable bonding
Solution Approach 1:
A planarization layer is formed in advance on the insulating layer before mounting the vibration element. This preliminary planarization action ensures that the bonding surface is sufficiently flat to achieve stable bonding, while the insulating layer with wiring layers remains intact below to provide proper insulation and electrical connections.
Solution Approach 2:
The structure is segmented into distinct functional layers: the insulating layer with wiring layers for electrical functions, and a separate planarization layer for surface flatness. This segmentation allows each layer to independently fulfill its specific function without compromising the other.
2Ease of manufacture
If the vibration element is mounted directly on the insulating layer surface, then the mounting process is simplified, but the bonding becomes unstable due to poor surface planarity
Solution Approach 1:
The planarization layer is prepared in advance on the insulating layer before the vibration element mounting process. This preliminary preparation maintains the simplicity of the mounting process while ensuring the bonding surface has sufficient planarity for stable bonding.
Solution Approach 2:
The planarization layer acts as an intermediary between the insulating layer and the vibration element. It provides a flat bonding surface for reliable mounting while allowing the underlying insulating layer to maintain its electrical functions.
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 ensures a stable and secure electrical coupling between the vibration element and the circuit element by increasing the bonding area and improving the planarity of the insulating layer, thereby enhancing the overall stability of the vibration device.
Implementation Method 1
forming a second insulating layer by depositing an insulator on a surface of the first insulating layer
Implementation Method 2
planarizing at least a part of a surface of the second insulating layer on a side opposite to the base by polishing
Data Source
AI summary
A method for manufacturing a vibration device includes: preparing a base including a semiconductor substrate having a first surface, on which a circuit element is formed, and a second surface, and a first insulating layer disposed on the first surface of the semiconductor substrate and covering the circuit element; forming a second insulating layer by depositing an insulator on a fifth surface of the first insulating layer on a side opposite to the semiconductor substrate; planarizing at least a part of a third surface of the second insulating layer on a side opposite to the base by polishing; forming a mount electrode on the polished third surface of the second insulating layer; and bonding a vibration element to the mount electrode.