MEMS Microphone Parasitic Capacitance Reduction
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Solution Overview
Problem
MEMS microphones suffer from signal attenuation due to parasitic capacitance in the acoustically inactive section, which deteriorates their performance, and existing manufacturing processes struggle to maintain mechanical stability while minimizing this capacitance.
Innovation Solution
A MEMS microphone design featuring a protection film that covers the backplate and anchor element in the rim region, utilizing a photo-sensitive polymer film resistant to VHF etching, and an additional backplate with a ring-shaped isolation element to reduce parasitic capacitance without compromising mechanical stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the backplate's rim section width is increased to protect the anchor element during manufacturing, then mechanical stability is improved, but parasitic capacitance increases and signal quality deteriorates
Solution Approach 1:
The backplate is segmented into an active region and a rim region, with the rim region's backplate material selectively removed to reduce parasitic capacitance while preserving the anchor element through protective measures
Solution Approach 2:
A protection film is introduced as an intermediary element to protect the anchor element during manufacturing processes, allowing the backplate's rim section to be removed without compromising mechanical stability
2Object-generated harmful factors
If the backplate's inactive section area is reduced to minimize parasitic capacitance, then signal quality is improved, but mechanical stability of the anchor element is compromised
Solution Approach 1:
The protection film is applied in advance before manufacturing steps that would otherwise require a wider backplate rim section, enabling subsequent removal of the backplate's inactive section while maintaining anchor element stability
3Object-generated harmful factors
If the capacitor's acoustically inactive section is minimized, then parasitic capacitance is reduced and signal quality improves, but mechanical connection stability is compromised
Solution Approach 1:
The capacitor structure is segmented into active and inactive sections, with the inactive section's backplate material selectively removed while preserving the anchor element's connection function through protective filming
Solution Approach 2:
The backplate material in the rim region is extracted/removed to reduce parasitic capacitance, while the anchor element is preserved through protection film to maintain mechanical connection stability
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 effectively minimizes parasitic capacitance, enhancing signal quality and mechanical stability by protecting the anchor element during manufacturing and isolating unwanted capacitances, thereby improving the overall performance of the microphone.
Implementation Method 1
utilizing a photo-sensitive polymer film resistant to VHF etching
Implementation Method 2
the anchor element spatially separates the backplate from the membrane preventing an electric short circuit
Implementation Method 3
When a bias voltage is applied to the electrodes, oscillations of the membrane caused by received acoustic signals are converted into electrical signals
Data Source
AI summary
A MEMS microphone with reduced parasitic capacitance is provided. A microphone includes a protection film covering a rim-sided area of the backplate.