Electret Element Aluminum Oxide ALD Coating Charge Stability
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Solution Overview
Problem
Electret elements with high aspect ratio comb-tooth structures face challenges in achieving good charge stability due to limitations in water-repellent treatments, such as HMDS, which fail to provide effective moisture resistance and charge retention.
Innovation Solution
An electret element comprising a silicon oxide film with alkali ions and a protective aluminum oxide film formed through atomic layer deposition, applied over the electret film and electrodes, enhancing moisture resistance and charge stability by inducing electric polarization with heat and voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If HMDS treatment is applied to improve charge stability, then water-repellent properties are enhanced, but the treatment cannot effectively cover high aspect ratio comb-tooth structures
Solution Approach 1:
The patent changes the material parameter from organic HMDS coating to inorganic aluminum oxide film, and changes the deposition method parameter to atomic layer deposition, enabling effective coverage of high aspect ratio structures while providing superior moisture resistance and charge stability
Solution Approach 2:
The patent replaces the chemical vapor deposition method with atomic layer deposition, which provides better step coverage and conformal coating on three-dimensional comb-tooth structures with high aspect ratios, ensuring uniform protective film formation
2Quantity of substance
If three-dimensional comb-tooth electrodes with high aspect ratio are used to increase capacitance, then compact conversion elements are achieved, but full effect of water-repellent treatment cannot be realized
Solution Approach 1:
The patent replaces conventional deposition methods with atomic layer deposition, which enables uniform film coverage on high aspect ratio comb-tooth structures by providing excellent step coverage and conformal deposition, thus protecting the entire surface including deep crevices
Solution Approach 2:
The patent uses aluminum oxide as an inorganic protective material that forms a composite structure with the electret film, providing enhanced moisture barrier properties and charge stability that complement the functional electret layer
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 provides improved moisture resistance and charge stability in electret elements with high aspect ratio comb-tooth structures and simple flat-plane structures, ensuring stable electrical charge retention beyond 10 hours, outperforming HMDS-treated electret elements.
Implementation Method 1
a protective film formed over the electret film and constituted of aluminum oxide deposited through an atomic layer deposition method
Implementation Method 2
the electret element is obtained through application of heat and a voltage
Implementation Method 3
inducing electric polarization by causing the alkali ions to move through a voltage application while heating the substrate
Implementation Method 4
an element that includes an electret will be referred to as an electret element
Implementation Method 5
a conversion element that converts vibrational energy to electrical energy
Data Source
AI summary
An electret element includes: an electret film that contains silicon oxide; and a protective film formed over the electret film and constituted of aluminum oxide deposited through an atomic layer deposition method.