Capacitive Microphone Diaphragm Fabrication via Silicon Spacers
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Solution Overview
Problem
Conventional capacitive microphone devices with plastic diaphragms suffer from poor yield and uniformity, and the assembly process is costly and time-consuming.
Innovation Solution
A method involving a substrate with a dielectric layer, silicon spacers, and a diaphragm layer formed using silicon, with planarization and etching processes to create uniform diaphragm structures for improved reliability and accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If plastic diaphragm is formed by stamping, then manufacturing process is simple, but uniformity and yield are poor
Solution Approach 1:
The patent replaces the mechanical stamping process with a semiconductor fabrication process involving deposition and etching. The diaphragm layer is formed by depositing material over silicon spacers and then etching through the substrate, which provides better control over thickness and uniformity compared to mechanical stamping.
Solution Approach 2:
The patent changes the material parameter from plastic to silicon-based materials and modifies the formation process parameters by using controlled deposition and etching processes. This allows for precise control of diaphragm thickness and uniformity, resolving the contradiction between simple manufacturing and high precision.
2Device complexity
If diaphragm is assembled with spacers after device fabrication, then diaphragm structure is achieved, but cost increases and cycle time extends
Solution Approach 1:
The patent merges the diaphragm formation process with the substrate fabrication process. The diaphragm layer is formed on the substrate along with the silicon spacers in the same fabrication sequence, eliminating the need for separate assembly steps and reducing both cost and cycle time.
Solution Approach 2:
The silicon spacers are formed preliminarily on the substrate before the diaphragm layer is deposited. This preliminary action allows the diaphragm to be formed in the correct position and structure during the main fabrication process, eliminating post-fabrication assembly operations.
3Ease of manufacture
If conventional stamping method is used, then production cost is low, but yield and uniformity are poor
Solution Approach 1:
The patent replaces the low-cost but low-yield mechanical stamping process with a semiconductor fabrication process. Although the fabrication process is more complex, it provides superior yield and uniformity through controlled deposition and etching, making it economically viable for high-volume production of quality microphones.
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 method achieves high uniformity and reliability in diaphragm fabrication, allowing for thinner diaphragms with broader applications and reduced production costs.
Implementation Method 1
a dielectric layer on a first surface of the substrate is formed
Implementation Method 2
a second surface of the substrate is etched to form a plurality of openings corresponding to the diaphragm layer
Data Source
AI summary
A method of fabricating a diaphragm of a capacitive microphone device. First, a substrate is provided, and a dielectric layer on a first surface of the substrate is formed. Than, a plurality of silicon spacers are formed on a surface of the dielectric layer, and a diaphragm layer is formed on a surface of the silicon spacers and the surface of the dielectric layer. Subsequently, a planarization layer is formed on the diaphragm layer, and a second surface of the substrate is etched to form a plurality of openings corresponding to the diaphragm layer disposed on the surface of the dielectric layer. Thereafter, the dielectric layer exposed through the openings is removed, and planarization layer is removed.