BAW Frequency Adjustment Layer Bonding to Prevent Delamination
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Solution Overview
Problem
Existing bulk acoustic wave (BAW) devices face challenges with unreliable frequency adjustment due to insufficient bonding strength between the second electrode and the frequency adjustment layer, leading to delamination and reduced manufacturing yield.
Innovation Solution
Incorporating a bonding layer between the second electrode and the frequency adjustment layer in BAW devices, with a thickness ranging from 1 nanometer to 20 nanometers, and using materials such as piezoelectric materials, aluminum nitride, or doped piezoelectric materials to enhance bonding strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a frequency adjustment layer is directly deposited on the second electrode, then frequency adjustment is achieved, but bonding strength is insufficient leading to delamination
Solution Approach 1:
A bonding layer is introduced as an intermediary between the second electrode and the frequency adjustment layer. This bonding layer comprises a piezoelectric material that chemically or physically bonds to both the second electrode and the frequency adjustment layer, creating a strong triangular bonding structure that prevents delamination while maintaining device functionality.
Solution Approach 2:
The bonding layer utilizes composite material structure where a piezoelectric material is specifically selected to provide both mechanical bonding strength and acoustic wave transmission properties. The piezoelectric material in the bonding layer serves dual purposes: strengthening the bond between layers and maintaining the acoustic wave propagation path from the second electrode through the frequency adjustment layer.
2Reliability
If the bonding layer is made thicker, then bonding strength increases, but acoustic wave transmission is degraded
Solution Approach 1:
The thickness of the bonding layer is precisely controlled within a specific range (1-20 nanometers) to optimize both bonding strength and acoustic wave transmission. This parameter optimization ensures that the bonding layer is thick enough to provide sufficient mechanical strength and chemical bonding, yet thin enough to allow acoustic waves to pass through with minimal attenuation and maintain frequency adjustment precision.
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 bonding layer significantly increases the bonding strength between the second electrode and the frequency adjustment layer, ensuring reliable frequency adjustment and improving manufacturing yield by preventing delamination.
Implementation Method 1
a bonding layer between the second electrode and the frequency adjustment layer, a bonding strength between the second electrode and the frequency adjustment layer with the bonding layer being greater than a bonding strength between the second electrode and the frequency adjustment layer without the bonding layer
Implementation Method 2
A bulk acoustic wave resonator can include a set of metal electrodes deposited on opposite surfaces of a piezoelectric material, generating a bulk acoustic wave within the volume of the piezoelectric material. The interaction between the electrodes and the piezoelectric material results in the formation and propagation of a bulk acoustic wave.
Data Source
AI summary
A bulk acoustic wave device and a method of forming the same is disclosed. The bulk acoustic wave device can include a piezoelectric layer positioned between a first electrode and a second electrode. The bulk acoustic wave device can include a frequency adjustment layer over the second electrode. The bulk acoustic wave device can include a bonding layer between the second electrode and the frequency adjustment layer. A bonding strength between the second electrode and the frequency adjustment layer with the bonding layer is greater than a bonding strength between the second electrode and the frequency adjustment layer without the bonding layer. The bonding layer can have a thickness in a range between 1 nanometer and 20 nanometers.