Back to results
US 2024/0377198 A1Published application
Vibrational mems structure, in particular gyroscope, having spurious mode test structures, test system and method
AssigneeSTMicroelectronics International N.V.
InventorsGabriele GATTERE, Luca GUERINONI
Life of this patent
Estimating the term…
Abstract
Test method of a vibrational MEMS structure wherein, a direct, variable modification voltage is applied to a resonance modification test structure having non-rectilinear electrodes, modifying the resonance frequency of the movable mass and the driving frequency. During the test, the movable mass is verified about stability and, if not stable, the vibrational MEMS structure is rejected.
Claims17
A vibrational MEMS structure, comprising:
- a substrate;
- a movable mass suspended on the substrate and having a resonance frequency;
- a resonance modification test structure including modification fixed electrodes, integral with the substrate, and modification movable electrodes, integral with the movable mass, each modification fixed electrode extending in a length direction and facing at least one respective modification movable electrode, the modification fixed electrodes and the modification movable electrodes being configured so that each modification fixed electrode is placed, at rest, at a distance, from the respective at least one modification movable electrode, which is variable along the length direction and defines an average gap, and wherein:
- the resonance modification test structure is configured to be biased, in a resonance modification test step, to a direct and variable modification voltage such as to cause a modification of the average gap between each modification fixed electrode and a respective modification movable electrode, by modifying the resonance frequency of the movable mass and a driving frequency.
1 more element
A test method, comprising:
- testing a vibrational MEMS structure, the vibrational MEMS structure including:
- a substrate;
- a movable mass suspended on the substrate and having a resonance frequency;
- an elastic system, elastically coupling the movable mass to the substrate thereby allowing the movable mass driving movements, in a driving direction, and sensing movements, in a sensing direction;
- a driving structure, coupled to the movable mass and configured to generate, in use, the driving movements of the movable mass;
- a sensing structure, coupled to the movable mass and configured to sense the sensing movements of the movable mass;
- a resonance modification test structure, comprising modification fixed electrodes, integral with the substrate, and modification movable electrodes, integral with the movable mass, each modification fixed electrode extending in a length direction and facing at least one respective modification movable electrode, the modification fixed electrodes and the modification movable electrodes being configured so that each modification fixed electrode is placed, at rest, at a distance, from the respective at least one modification movable electrode, which is variable along the length direction and defines an average gap, the method comprising:
- applying, to the resonance modification test structure, a direct, variable modification voltage;
- the testing the vibrational MEMS structure including:
- modifying the resonance frequency of the movable mass and the driving frequency;
- operating the driving structure;
- and
- verifying whether the movable mass is stable.
10 more elements
A vibrational MEMS structure, comprising:
- a substrate;
- a movable mass suspended from the substrate, the movable mass including an opening that extends into the movable mass, and the opening being delimited by a first side of the movable mass that delimits the opening and a second side of the movable mass that delimits the opening, the first side being opposite to the second side, and the first side facing the second side;
- a driving structure within the opening of the movable mass, the driving structure including:
- driving fixed electrodes that are coupled to the substrate and are within the opening;
- and
- driving movable electrodes that are coupled to the movable mass and extend into the opening, the driving movable electrodes include a first group that extend into the opening at the first side and a second group extend into the opening at the second side;
- a frequency modification structure including:
- a softening structure including:
- softening fixed electrodes that are coupled to the substrate;
- and
- softening movable electrodes that are coupled to the movable mass and extend into the opening, the softening movable electrodes extend into the opening from the first side;
- a hardening structure including:
- hardening fixed electrodes that are coupled to the substrate;
- and
- hardening movable electrodes that are coupled to the movable mass and extend into the opening, the hardening movable electrodes extend into the opening from the second side.
12 more elements
Dependencies are inferred from the claim text.