MEMS Proof Mass and Suspension Beam Layout for Uniform Etching
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Solution Overview
Problem
Existing MEMS devices face challenges in forming a thinner support beam with a uniform pattern and a heavy sense mass, leading to non-uniform patterns and reduced production yield and reliability.
Innovation Solution
The MEMS devices incorporate a suspension beam with a uniform pattern and a precise controlled gap between a proof mass and a stopper, using a bonding dielectric layer to support the proof mass during etching, ensuring no striation at the sidewalls and allowing for flexible gap dimensions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a micromachining process is used to etch the thinned device substrate to form the sense mass and beam, then the MEMS device can be fabricated, but it is difficult to form both a thinner support beam with uniform pattern and a heavy sense mass together, resulting in non-uniform beam pattern and reduced production yield
Solution Approach 1:
The patent divides the substrate into two separate processing regions: a first substrate region for forming the support beam and a second substrate region for forming the sense mass. This segmentation allows independent optimization of etching parameters for each feature type, enabling uniform beam patterns while maintaining heavy sense mass formation, thereby resolving the contradiction between manufacturing precision and productivity
Solution Approach 2:
The patent applies different etching conditions to different regions of the substrate. The first etching process uses parameters optimized for creating uniform, thin support beams in the first substrate region, while the second etching process uses parameters optimized for forming heavy sense masses in the second substrate region. This local quality approach allows each region to achieve its specific manufacturing requirements without compromising the other
2Measurement precision
If the sense mass is made heavy to improve detection sensitivity, then the detection capability is enhanced, but it becomes more difficult to form uniform support beams during the etching process
Solution Approach 1:
By segmenting the substrate into separate regions for support beam formation and sense mass formation, the patent enables independent control of etching parameters. This allows the sense mass to be made heavy for improved detection sensitivity while the support beam region maintains parameters optimized for uniform pattern formation, thus resolving the contradiction between measurement precision and manufacturing precision
Data Source
AI summary
A micro-electro-mechanical system (MEMS) device includes a supporting substrate, a cavity, a stopper, a MEMS structure, and a bonding dielectric layer. The cavity is located at a top surface of the supporting substrate. The stopper is adjacent to the cavity, where a top surface of the stopper and the top surface of the supporting substrate are on the same level in a height. The MEMS structure is disposed on the supporting substrate, where the MEMS structure includes a proof mass and a suspension beam. The proof mass is disposed directly above the stopper, and the suspension beam is disposed directly above the cavity. The bonding dielectric layer is disposed between the top surface of the supporting substrate and a bottom surface of the MEMS structure.