PiezoMEMS Electrodes with Barrier Layer for Low Surface Roughness
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Solution Overview
Problem
The existing manufacturing methods for piezoMEMS microphones result in non-uniform electrode layers due to oxidation during the patterning process, leading to increased surface roughness and reduced sensitivity to sound waves.
Innovation Solution
A method involving the deposition of a barrier layer to prevent oxidation during the patterning of electrode layers, ensuring uniform thickness and low surface roughness, which enhances the piezoelectric effect by using a hard mask layer to protect the electrodes from oxygen plasma ashing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If oxidation protection is not applied during patterning, then the patterning process can be completed, but the electrode layer becomes non-uniform with increased surface roughness
Solution Approach 1:
A barrier layer is deposited over the electrode layer before the patterning process begins. This preliminary protective action prevents oxidation during subsequent plasma ashing and etching steps, ensuring the electrode layer maintains its uniform thickness and low surface roughness throughout the manufacturing process.
Solution Approach 2:
The barrier layer acts as an intermediary between the electrode layer and the oxygen plasma environment. This intermediate layer blocks oxygen from reaching and oxidizing the electrode material during patterning, thereby preserving electrode uniformity without requiring changes to the electrode deposition process itself.
2Manufacturing precision
If a barrier layer is deposited to prevent oxidation, then electrode layer uniformity is maintained, but the manufacturing process becomes more complex
Solution Approach 1:
The barrier layer is deposited in advance before any patterning operations. This preliminary protective measure ensures that when oxygen plasma ashing and etching are performed later, the electrode layer is already protected, maintaining smooth surfaces and uniform thickness without requiring post-processing corrections.
Solution Approach 2:
The barrier layer serves as a protective intermediary that isolates the electrode layer from harmful oxygen exposure during manufacturing. This simple addition of one layer protects against oxidation without fundamentally changing other manufacturing steps, balancing the trade-off between process complexity and manufacturing precision.
3Productivity
If the electrode layer is exposed to oxygen plasma during patterning, then the patterning can be completed, but the piezoelectric effect is reduced due to oxidation
Solution Approach 1:
The barrier layer is applied before the oxygen plasma patterning step. This preliminary protection allows the patterning process to proceed normally with full productivity, while simultaneously preventing oxidation that would degrade the piezoelectric effect, thus maintaining both manufacturing efficiency and device reliability.
Solution Approach 2:
The barrier layer acts as a protective intermediary during the oxygen plasma exposure. It allows the plasma processing to occur for pattern formation while blocking the oxygen from reaching and oxidizing the electrode layer, thereby preserving the piezoelectric material's sensitivity and ensuring reliable device performance.
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 solution achieves a more uniform crystalline lattice in the piezoelectric structure, resulting in enhanced sensitivity and reliability of the piezoMEMS microphones by maintaining low surface roughness and uniform sheet resistance.
Implementation Method 1
depositing a barrier layer to prevent oxidation during the patterning of electrode layers
Implementation Method 2
PiezoMEMS microphones utilize a piezoelectric structure that converts mechanical strain into an electrical signal
Data Source
AI summary
In some embodiments, the present disclosure relates to a piezomicroelectromechanical system (piezoMEMS) device that includes a second piezoelectric layer arranged over the first electrode layer. A second electrode layer is arranged over the second piezoelectric layer. A first contact is arranged over and extends through the second electrode layer and the second piezoelectric layer to contact the first electrode layer. A dielectric liner layer is arranged directly between the first contact and inner sidewalls of the second electrode layer and the second piezoelectric layer. A second contact is arranged over and electrically coupled to the second electrode layer, wherein the second contact is electrically isolated from the first contact.