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Mems fabrication
This document discusses various MEMS fabrication techniques, including mask lithography, injection molding, microstereolithography, silicon surface micromachining, and silicon bulk micromachining. Mask lithography uses photo resist layers and multiple steps to build up device structures layer by layer. Injection molding starts with a mask lithography process to create a metal mold form, which is then used for plastic injection molding. Microstereolithography uses an active mask and projected light to selectively harden resin layers into 3D structures in a layer-by-layer build process. Silicon surface micromachining uses sacrificial and structural layers similar to IC fabrication to leave freestanding structures. Silicon bulk micromachining
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Mems fabrication
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- 2. MEMS overview Micronlevel mechanical parts Made from transistor materials and metals
- 3. Fabrication Techniques MaskLithography Injection molding Microstereolithography Silicon Surface Micromachining Silicon Bulk Micromachining
- 4. Mask Lithography Useof photo resist Positive Dissolves under light Negative Hardens under light Both get covered with desired material, then photo resist is dissolved by a solvent Multiple layers – Multiple steps
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- 6. Injection Molding Startswith mask lithography Metal poured over resist Resist gets dissolved Metal form is left for plastic injection molding
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- 8. Microstereolithography Similar principalto mask lithography, but for 3D pieces Uses an “active mask” Not a physical mask Utilizes a photo-reactive acrylic resin Each layer image projected through a DMD(digital mirror device) Projected into the resin Uses lenses Resin that is illuminated, Cross-links and hardens Piece is then covered in a hardened layer
- 9. Microstereolithography Dimensional capabilities Lateraland Vertical resolution: 10μm Maximum field size: 10.24mm x 7.68mm Structural height: up to 5mm
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- 12. Silicon Surface Micromachining Usesthe same process as IC fabrication Needs multiple layers to create structures Cheapest form of Micromachining Similar to lithography Sacrificial material Structural material When sacrificial material is removed, only whole structures are left
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- 16. Silicon Bulk Micromachining Done with Crystalline silicon Constructed using etch stop planes Chemical process Anisotropic Etching Speed dependent – Directional etch in different crystallographic directions at different rates Slower directions create and etch stop plane
- 17. Deep Reactive IonEtching (DRIE) Uses photo resist and a mask to create structures
- 18. Sapphire Etching MetalMask 100µm etch depth .28µm/min etch rate Chlorine etching
- 19. Pressure Sensor Etching Used on silicon Metal mask .81µm etch depth Utilizes Fluorine
- 20. High-Speed Etching Siliconmaterial 1µm/min etch rate Si Mask