Micromechanical Sensor Stress Decoupling via Gel-Filled Trenches
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Solution Overview
Problem
Micromechanical pressure difference sensors face mechanical stress due to packaging and application-related loads, which are difficult to compensate for during manufacturing, leading to inconsistent performance.
Innovation Solution
The method involves producing a micromechanical sensor by creating rear and front trench regions on a substrate to expose a functional layer, which is then partially filled with a gel to seal and decouple the sensor membrane from stress, allowing for precise stress decoupling and cost-effective construction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the functional layer is exposed on all sides by trenching, then stress decoupling is achieved, but the manufacturing complexity increases
Solution Approach 1:
The substrate is divided into multiple regions: a functional layer region with all-side exposure for stress decoupling, and a support structure region with trenches forming suspension. This segmentation allows different parts of the sensor to have different structural characteristics optimized for their specific functions.
Solution Approach 2:
The patent transitions from conventional planar sensor structures to a three-dimensional architecture where the functional layer is suspended on all sides by trenches etched from both front and back surfaces, creating vertical suspension and all-around exposure that eliminates stress transmission from the substrate.
2Reliability
If gel is used to seal the front from the rear, then stress decoupling is enhanced, but the manufacturing process becomes more complex
Solution Approach 1:
A gel material is introduced as an intermediary substance that fills the trenches and seals the front from the rear, providing stress decoupling while maintaining the structural integrity of the sensor. The gel acts as a compliant material that prevents stress transmission.
Solution Approach 2:
The patent changes the physical state of the sealing material from rigid to gel-like, allowing for stress absorption and decoupling. The gel phase provides both sealing functionality and mechanical compliance to isolate the functional layer from substrate stresses.
3Reliability
If high adhesive thicknesses are used to compensate for stress, then stress compensation is improved, but the manufacturing precision decreases
Solution Approach 1:
The patent extracts the functional layer from the stressed substrate environment by creating all-side exposure through trenching, removing it from the source of mechanical stress. This eliminates the need for compensatory adhesive layers and their associated manufacturing challenges.
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
This approach effectively decouples the functional layer from stress, reducing the need for high adhesive thicknesses and enabling precise stress management, resulting in more consistent sensor performance and cost-effective production.
Implementation Method 1
at least partially filling at least one front-side trench region with a gel to seal the front from the rear
Data Source
Figure 1a~1d
Figure 1e~1h
Figure 2a~2d
AI summary
The invention relates to a method for producing a micromechanical sensor, in particular a pressure difference sensor, comprising the following steps: – producing a functional layer (2) on a substrate (5), – producing at least one rear-side trench region (10, 11, 12, 13, 30) proceeding from a rear side (7) of a substrate (5) for freeing the functional layer (2) for a sensor membrane (2, 20), – producing at least one front-side trench region (19) for forming at least one carrying structure (17), in particular an energy storage structure, preferably in the form of a spring structure, in the substrate (5) as suspension for the sensor membrane (2, 20), and – at least partly filling at least one front-side trench region (19) with a gel (20).