MEMS Acoustic Sensor Manufacturing via In-Situ Polymerization
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Solution Overview
Problem
The conventional method for manufacturing MEMS acoustic sensors faces challenges with alignment accuracy and yield due to the fragility of the cantilever structure and the inefficiencies in the assembly process.
Innovation Solution
A method involving sequential stacking of structural and piezoelectric material layers, photolithography modeling, and the use of a prefabricated jig to form an arch portion of the polymer layer, which is then deformed and adhered to form a 3D morphology, is employed to improve alignment and yield.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the arch component of the elastic connector is prepared separately in advance and pasted onto the driver surface by mechanical equipment, then the assembly process can be completed, but the alignment accuracy is poor and the yield is extremely low due to the fragility of the cantilever structure
Solution Approach 1:
The patent merges the preparation of the arch component and the driver into a single integrated process. The polymer layer is formed directly on the driver structure through in-situ polymerization, eliminating the need for separate preparation and pasting steps. This integration ensures precise alignment between the arch component and the driver structure, as they are formed as a unified assembly rather than separate parts that require mechanical assembly.
Solution Approach 2:
The patent replaces the mechanical pasting process with a chemical polymerization process. Instead of using mechanical equipment to adhere the arch component to the driver surface, the polymer layer is formed through chemical polymerization directly on the driver structure. This substitution eliminates the mechanical assembly step that caused misalignment and damage to the fragile cantilever structures.
2Ease of manufacture
If the arch component is prepared separately and pasted onto the driver surface, then the assembly can be completed, but the pasted surface becomes extremely fragile and cannot withstand adhesion force, resulting in extremely low yield
Solution Approach 1:
The patent combines the arch component and driver into a single integrated structure formed through in-situ polymerization. This merging eliminates the interface between separately prepared components, removing the source of fragility that occurred at the pasted surface. The unified structure distributes mechanical stresses more evenly and eliminates weak points at assembly interfaces.
Solution Approach 2:
The patent replaces the mechanical pasting process with chemical polymerization, which creates strong chemical bonds throughout the polymer layer rather than relying on surface adhesion. This chemical bonding process creates a robust, integrated structure that can withstand mechanical stresses during subsequent processing and operation, dramatically improving yield compared to mechanically assembled structures.
3Ease of manufacture
If traditional mechanical equipment is used to paste the thin film onto the driver surface, then the assembly process can be completed, but the alignment accuracy is not desirable due to the limitations of traditional mechanical equipment
Solution Approach 1:
The patent replaces traditional mechanical assembly equipment with an in-situ polymerization process. The polymer layer is formed directly on the driver structure through chemical polymerization, eliminating the need for mechanical positioning and pasting equipment. This approach achieves high alignment accuracy by forming the arch component and driver as a unified structure rather than assembling separate components.
Solution Approach 2:
The patent uses the driver structure itself as the substrate for polymer formation. The driver structure serves as the intermediary that guides the polymerization process, ensuring precise alignment. The polymer layer forms directly on the driver structure's geometry, inheriting its precise dimensional characteristics without requiring separate alignment procedures.
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 method enhances alignment accuracy, increases yield, and simplifies the process, resulting in a more reliable and cost-effective manufacturing of MEMS acoustic sensors.
Implementation Method 1
heating the jig, the substrate, the piezoelectric material layer, and the polymer layer together to a first temperature to enable the polymer layer to be in a rubbery state, where a first ventilation hole penetrating through the first part is further defined on the first part, the first ventilation hole is in communication with the arch groove and outside, and the first temperature is a glassy transition temperature of the polymer layer
Implementation Method 2
introducing air at a predetermined pressure into the cavity and controlling a pressure inside the cavity to reach a predetermined value, to enable a part of the polymer layer opposite to the arch groove to deform and adhere to an inner wall of the arch groove to form an arch portion
Implementation Method 3
maintaining an atmospheric pressure load of the air and cooling the air to below the first temperature, to enable the polymer layer to be in a glassy state
Data Source
AI summary
Provided is a method for manufacturing a MEMS acoustic sensor. A structural layer and a piezoelectric material layer are stacked on the substrate. Photolithography modeling is performed on the piezoelectric material layer and the structural layer. A polymer layer is stacked on the piezoelectric material layer. The substrate is etched to form a cavity. A first part of a jig is stacked on the polymer layer. The jig, the substrate, the piezoelectric material layer, and the polymer layer are heated. Air is introduced into the cavity and a pressure inside the cavity is controlled. An atmospheric pressure load of the air is maintained and the air is cooled. The pressure inside the cavity is stopped to be controlled and the pressure inside the cavity is reduced, the jig is disassembled, and a wafer is cut to obtain the MEMS acoustic sensor, to effectively improve the accuracy and reliability in processing.