Piezoelectric Element Seed Layer for Reliable Through-Electrode Contact
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Solution Overview
Problem
The connection between the electrode coating film and the through electrode in piezoelectric elements is weakened due to a decline in crystallinity, leading to potential etching and reduced reliability.
Innovation Solution
Incorporating a seed layer with a lattice constant closer to the piezoelectric film, which self-aligns and prevents crystallinity loss in the electrode coating film and through electrode, enhancing the connection reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a through electrode is connected to an electrode coating film on a piezoelectric film, then electrical connection is achieved, but the connection reliability is weakened due to decline in crystallinity
Solution Approach 1:
A buffer layer is introduced as an intermediary between the piezoelectric film and the electrode coating film. This buffer layer has a lattice constant closer to the piezoelectric film than the electrode coating film, serving as a crystalline bridge that maintains lattice matching and prevents crystallinity loss in the electrode coating film, thereby ensuring reliable electrical connection
Solution Approach 2:
The invention changes the lattice constant parameter of the buffer layer to be closer to that of the piezoelectric film rather than matching the electrode coating film. This parameter adjustment creates optimal lattice matching conditions that prevent crystallinity degradation and maintain connection reliability
2Ease of manufacture
If the electrode coating film loses crystallinity, then manufacturing process is simplified, but etching occurs and connection reliability is reduced
Solution Approach 1:
The buffer layer acts as a protective intermediary that prevents etching from reaching the piezoelectric film. By maintaining crystallinity in the electrode coating film through the buffer layer's lattice matching, the structure becomes more resistant to etching damage while preserving manufacturing feasibility
3Stability of the object's composition
If the lattice constant of the buffer layer is closer to the piezoelectric film, then crystallinity is maintained, but device structure becomes more complex
Solution Approach 1:
The buffer layer is strategically positioned only where needed - between the piezoelectric film and electrode coating film at the connection region. This localized application maintains crystallinity where it matters most for electrical connection while minimizing overall device complexity and avoiding unnecessary layers in other regions
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
The seed layer maintains the crystallinity of the electrode coating film and through electrode, thereby improving the connection reliability and reducing manufacturing complexity and yield loss.
Implementation Method 1
a seed layer made of material having a lattice constant closer to the piezoelectric film than the insulation film or material easier to cause the piezoelectric film to be self-aligned than the insulation film
Data Source
AI summary
A piezoelectric element includes a support member, a vibrator, a through electrode and a seed layer. The vibrator is disposed on an insulation film of the support member, and includes a piezoelectric film and an electrode coating film electrically connected to the piezoelectric film. The vibrator has a support region and a vibration region. The through electrode is electrically connected to the electrode coating film at the support region, and is disposed in a stacking direction of the support member and the vibrator. Between the piezoelectric film and the insulation film, the seed layer is disposed at a portion of the electrode coating film facing another portion of the electrode coating film connected to the through electrode in the stacking direction. The seed layer is made of material having a lattice constant closer to the piezoelectric film or material easier to cause the piezoelectric film to be self-aligned.