RF MEMS Switch Pooling Electrode Reduces Driving Voltage
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Solution Overview
Problem
MEMS switch devices face challenges with high driving voltage requirements and stiction issues due to electrostatic attraction and adhesion between electrodes, which affect their on/off characteristics and insulating properties.
Innovation Solution
The RF MEMS switch device incorporates a pooling electrode and pooling line, formed with high resistance conductive materials like SiCr or TiW, to increase capacitance and reduce driving voltage while preventing stiction by maintaining a constant distance between electrodes, thereby improving on/off characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the distance between counter electrodes is increased, then the insulating characteristics when off are improved, but the electrostatic attraction decreases and driving voltage increases
Solution Approach 1:
The patent introduces a pooling electrode that extends in the longitudinal direction of the membrane electrode, adding a dimensional aspect to the electrostatic attraction. This pooling electrode creates an additional area for electrostatic force generation without increasing the gap distance, thereby maintaining low driving voltage while ensuring proper insulation when off.
Solution Approach 2:
The patent combines the signal electrode and pooling electrode into a integrated electrode structure. The pooling electrode is formed to overlap with the membrane electrode in addition to the signal electrode's overlap, effectively merging their functions to provide both insulation and electrostatic attraction without requiring increased voltage.
2Use of energy by moving object
If the intersected area between membrane electrode and signal electrode is increased, then the electrostatic attraction is improved and driving voltage is reduced, but stiction phenomenon is intensified
Solution Approach 1:
The patent segments the electrode interaction area into two distinct components: the signal electrode intersected area and the pooling electrode overlap area. The signal electrode provides controlled intersection for necessary electrostatic force, while the pooling electrode provides additional overlap area for capacitance enhancement without intensifying stiction, as it is positioned to overlap with the membrane electrode without direct contact.
Solution Approach 2:
The dielectric layer serves as an intermediary between the pooling electrode and the membrane electrode. This dielectric layer allows the pooling electrode to overlap with the membrane electrode and contribute to capacitance and electrostatic attraction while preventing direct contact that would cause stiction, thus mediating between the need for large intersected area and the need to avoid adhesion.
3Force
If the intersected area between membrane electrode and signal electrode is increased, then the electrostatic attraction is improved, but the insulating characteristics when off are lowered
Solution Approach 1:
The patent extends the electrostatic attraction in the longitudinal direction through the pooling electrode, which overlaps with the membrane electrode along its length. This dimensional extension provides additional electrostatic force without increasing the lateral intersected area between signal electrode and membrane electrode, thus maintaining insulation characteristics while improving attraction.
Solution Approach 2:
The patent separates the functions of electrostatic attraction and insulation by using two different electrode configurations: the signal electrode with controlled intersection for insulation, and the pooling electrode with extended overlap for electrostatic attraction. This segmentation allows each electrode to optimize its specific function without compromising the other.
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 reduces driving voltage requirements and prevents stiction, enhancing the on/off performance and insulating characteristics of the RF MEMS switch device by increasing capacitance and maintaining a constant distance between electrodes.
Implementation Method 1
at least one pooling electrode formed to be overlapped with the membrane electrode and having the dielectric layer be interposed therebetween
Implementation Method 2
because an electrostatic attraction is proportional to the inverse of the distance between counter electrodes
Data Source
AI summary
The present invention relates to an RF MEMS switch device comprising: a substrate; a bias electrode positioned on the substrate and supplying bias voltage; a pair of signal electrodes positioned to be spaced-apart each other on the substrate and transmitting an RF signal from one side to the other side; a dielectric layer formed on upper part of the pair of signal electrodes to be overlapped with the pair of signal electrodes; a membrane electrode formed on the dielectric layer to be overlapped with the pair of signal electrodes and the dielectric layer; a bias line connecting between the membrane electrode and the bias electrode; at least one pooling electrode formed to be overlapped with the membrane electrode and having the dielectric layer be interposed therebetween; and a pooling line connecting any one of the pair of signal electrodes and the pooling electrode, and manufacturing method thereof.