Hydrophobic Semiconductor Layer for MEMS Adhesion
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Solution Overview
Problem
The bonding process of Micro-Electro-Mechanical Systems (MEMS) devices with a cap substrate often results in adhesion failures, leading to poor reliability due to the use of hydrophobic compounds that generate byproducts like water, which act as outgassing sources.
Innovation Solution
A hydrophobic semiconductor layer made of germanium (Ge), silicon (Si), or their combination is applied to the surfaces facing the MEMS devices, which reduces adhesion and is formed through a recrystallization process to achieve a high water contact angle, eliminating the need for hydrophobic compounds and their byproducts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If hydrophobic compounds are used to reduce adhesion, then adhesion resistance is improved, but harmful byproducts like water are generated causing outgassing
Solution Approach 1:
The patent extracts and eliminates the harmful hydrophobic compound layer entirely, replacing it with a hydrophobic semiconductor layer made of intrinsic semiconductor materials (silicon, germanium, or their alloys). This extraction removes the source of harmful byproducts while preserving the essential adhesion resistance function through the inherent hydrophobic properties of the semiconductor material itself.
Solution Approach 2:
The patent changes the material parameter from organic hydrophobic compounds to inorganic hydrophobic semiconductor materials. This parameter change transforms the system from one that generates harmful byproducts to one that provides adhesion resistance through the inherent properties of the semiconductor material, eliminating outgassing while maintaining reliability.
2Reliability
If hydrophobic compounds are applied to surfaces, then adhesion is reduced, but the bonding process reliability deteriorates due to byproduct generation
Solution Approach 1:
The patent converts the harmful effect of byproduct generation into a benefit by using a material (hydrophobic semiconductor layer) that provides the desired adhesion resistance function without generating harmful byproducts. The inherent hydrophobicity of the semiconductor material serves the protective function while the material's stability ensures no harmful emissions during bonding or operation.
3Ease of manufacture
If conventional bonding processes are used, then manufacturing is simplified, but adhesion failures occur reducing reliability
Solution Approach 1:
The patent applies preliminary action by forming the hydrophobic semiconductor layer on the substrate surfaces before the bonding process. This preliminary coating prepares the surfaces to inherently resist adhesion during subsequent bonding operations, preventing adhesion failures while maintaining manufacturing simplicity through a straightforward deposition and recrystallization sequence.
Solution Approach 2:
The patent changes the surface property parameter by depositing a hydrophobic semiconductor layer with specific crystalline structure and orientation. This parameter change creates surfaces that naturally resist adhesion to other surfaces, preventing bonding failures while requiring only standard semiconductor fabrication processes, thus maintaining ease of manufacture.
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 hydrophobic semiconductor layer effectively reduces adhesion between the MEMS devices and surrounding surfaces, enhancing the reliability of the bonding process by preventing the issues associated with hydrophobic compound byproducts.
Implementation Method 1
A hydrophobic semiconductor layer made of germanium (Ge), silicon (Si), or their combination is applied to the surfaces facing the MEMS devices, which reduces adhesion and is formed through a recrystallization process to achieve a high water contact angle
Implementation Method 2
A hydrophobic semiconductor layer made of germanium (Ge), silicon (Si), or their combination is applied to the surfaces facing the MEMS devices, which reduces adhesion and is formed through a recrystallization process to achieve a high water contact angle
Data Source
AI summary
A micro electro mechanical system (MEMS) structure is provided, which includes a first substrate, a second substrate, a MEMS device and a hydrophobic semiconductor layer. The first substrate has a first portion. The second substrate is substantially parallel to the first substrate and has a second portion substantially aligned with the first portion. The MEMS device is between the first portion and the second portion. The hydrophobic semiconductor layer is made of germanium (Ge), silicon (Si) or a combination thereof on the first portion, the second portion or the first portion and the second portion and faces toward the MEMS device. A cap substrate for a MEMS device and a method of fabricating the same are also provided.