MEMS Microphone and Orientation Sensor Assembly Integration
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing microphone and accelerometer designs are structurally incompatible, making it difficult to integrate them on a common substrate while meeting the sensitivity and stability requirements of both applications.
Innovation Solution
A microelectromechanical system (MEMS) design that combines a capacitive microphone and tilt sensors on a common substrate using polysilicon and silicon nitride layers, with asymmetric inertial mass members and electronic circuits to detect inertial loads, allowing for sensitive and stable operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If thick layers of polysilicon are used to form the inertial mass member in accelerometers, then the accelerometer structure is robust and easy to manufacture, but the microphone membrane sensitivity deteriorates because the membrane thickness must be 1 micron or less
Solution Approach 1:
The patent divides the device into two separate substrates: a first substrate containing the accelerometer with thick polysilicon layers, and a second substrate containing the microphone with thin membrane structure. This segmentation allows each component to be optimized independently for its specific manufacturing requirements and performance criteria.
Solution Approach 2:
The patent places the second substrate (microphone) on top of the first substrate (accelerometer), creating a nested configuration where the microphone assembly is positioned over the accelerometer assembly. This nesting allows both devices to occupy the same footprint area while maintaining their respective structural requirements.
2Device complexity
If the microphone and accelerometer are integrated on a common substrate, then device complexity is reduced, but the structural requirements of both applications cannot be satisfied simultaneously
Solution Approach 1:
Instead of integrating both devices on the same two-dimensional substrate plane, the patent transitions to a three-dimensional arrangement by stacking the accelerometer and microphone on separate substrates vertically. This dimensional change allows both devices to coexist without interfering with each other's structural requirements.
Solution Approach 2:
The patent extracts the microphone from the accelerometer substrate and places it on a separate substrate. This extraction allows the accelerometer to maintain its robust thick polysilicon structure while the microphone maintains its sensitive thin membrane structure, resolving the structural incompatibility.
3Productivity
If a single substrate is used for both microphone and accelerometer, then manufacturing process steps are reduced, but the sensitivity and stability requirements of both applications cannot be met
Solution Approach 1:
The patent segments the manufacturing process into two independent fabrication sequences: one for the accelerometer on the first substrate and another for the microphone on the second substrate. Each substrate can be processed according to its specific material and structural requirements, ensuring optimal sensitivity and stability for both devices.
Solution Approach 2:
The patent merges the two separately fabricated substrates into a single integrated assembly by positioning the second substrate (microphone) on the first substrate (accelerometer). This combining step integrates the functions of both devices while preserving the manufacturing advantages of separate fabrication processes.
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
Enables the integration of microphones and orientation sensors on a common substrate, enhancing sensitivity and stability, and enabling applications such as automatic image orientation and power management in devices like smartphones and GPS devices.
Implementation Method 1
A capacitive microphone such as that disclosed in U.S. Pat. No. 6,535,460 to Loeppert et al
Implementation Method 2
These tilt sensors are capacitive devices which are low resolution accelerometers that respond to the force of gravity
Implementation Method 3
with asymmetric inertial mass members and electronic circuits to detect inertial loads
Data Source
AI summary
A microphone and orientation sensor system includes a microphone and an orientation sensor. The microphone has a diaphragm. The orientation sensor includes an inertial load member having a first end and a second end opposite the first end. The sensor also includes at least one electrode positioned adjacent to the inertial load member. The sensor further includes a beam. The inertial load member pivots about the beam, and the pivoting of the load member causes a change in a distance between the first end and the electrode resulting in a change in capacitance between the first end and the electrode. The diaphragm and electrode are formed from a common layer of material.