MEMS Production via Epitaxial Sacrificial Layers
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current methods for producing MEMS/NEMS structures from monocrystalline silicon face challenges such as high costs, poorly controlled stresses, and limitations in pattern resolution and mechanical quality due to the use of SOI, SON, and SCREAM technologies.
Innovation Solution
A method involving the formation of anchoring zones and protective layers on a monocrystalline silicon substrate, allowing for selective etching and release of MEMS/NEMS components, which includes epitaxial growth of protective layers and isotropic etching to access the silicon substrate, enabling the production of high-quality, low-cost MEMS/NEMS structures without additional insulating layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If SOI technology is used to produce MEMS/NEMS structures, then the production cost is high, but the mechanical quality and stress control are improved
Solution Approach 1:
The patent uses a disposable sacrificial layer (silicon dioxide or silicon nitride) deposited on a standard silicon substrate to enable release of monocrystalline silicon structures. This approach avoids the need for expensive SOI substrates while maintaining mechanical quality, as the sacrificial layer is consumed during the release process to create the suspended structure.
Solution Approach 2:
The patent changes the material parameter of the substrate from expensive SOI to standard silicon, and uses chemical etching parameters (selective etchants for silicon vs. sacrificial layer) to achieve the desired structure release. This parameter change maintains mechanical quality while reducing production cost.
2Ease of manufacture
If SON technology is used to produce MEMS/NEMS structures, then the production cost is reduced, but the pattern resolution and mechanical quality are limited
Solution Approach 1:
The patent introduces a sacrificial layer as an intermediary between the standard silicon substrate and the final structure. This sacrificial layer enables precise pattern definition through standard lithography and etching processes, then is selectively removed to release the structure, achieving high pattern resolution without the limitations of direct SiGe etching.
3Ease of manufacture
If SCREAM technology is used to produce MEMS/NEMS structures, then the production cost is reduced, but additional insulating layers and metallisation are required
Solution Approach 1:
The patent extracts and removes the sacrificial layer (silicon dioxide or silicon nitride) after the structure is formed, releasing the monocrystalline silicon component without requiring additional insulating layers or metallisation steps. This simplifies the overall process compared to SCREAM technology by eliminating post-release metallisation and complex insulation schemes.
4Ease of operation
If a sacrificial layer is used to release MEMS/NEMS structures, then the structure can be released, but the sacrificial layer material must be selectively etched
Solution Approach 1:
The patent uses sacrificial layers with different local properties: silicon dioxide for areas requiring high etch selectivity and silicon nitride for areas requiring mechanical strength during processing. This local quality differentiation enables selective etching with high precision while maintaining structural integrity during the release process.
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 method provides a cost-effective, CMOS-compatible approach for producing MEMS/NEMS structures with improved mechanical quality and flexibility in pattern design, reducing mechanical stress and enhancing the quality factor of resonating structures.
Implementation Method 1
forming, on said face of the substrate, a lower protective layer made of material other than silicon and obtained by epitaxy from said face of the substrate
Implementation Method 2
forming, on the lower protective layer, a silicon layer obtained by epitaxy from the lower protective layer
Implementation Method 3
releasing the mechanical component by isotropic etching of the monocrystalline silicon substrate from the access routes to the monocrystalline silicon substrate, this isotropic etching not attacking the lower and upper protective layers and the protective layer of the walls
Data Source
AI summary
A mechanical component production method of a MEMS/NEMS structure from a monocrystalline silicon substrate includes forming anchoring zones in one face of the substrate. A lower protective layer, non-silicon, obtained by epitaxy from the face of the substrate is formed on the face. A silicon layer obtained by epitaxy from the lower protective layer is formed on the lower protective layer. An upper protective layer is formed on the silicon layer. The upper protective, silicon and lower protective layers are etched according to a pattern defining the component, until the substrate is reached, providing access routes to the substrate. A protective layer is formed on the walls formed by the etching in the epitaxied silicon layer. The component is released by isotropic etching of the substrate from the access routes, wherein the isotropic etching does not attack the lower and upper protective layers and the protective layer of the walls.