20-04-2012, 03:24 PM
MICROMACHINING
micromachining.pdf (Size: 3.08 MB / Downloads: 283)
Micromachining Basics
• Refers to techniques for fabrication of
3D structures on the micrometer scale
• Applications include MEMS devices
e.g. airbag sensor, medical devices,
micro-dies and molds, etc.
• Most methods use silicon as substrate
material
Photolithography
• Used in
(a)
microelectronics
fabrication
• Used to pattern
oxide/nitride/polysilicon
films on silicon
(b) substrate
• Basic steps
- ©
photoresist development
- Etching
- Resist removal
Wet Etching Process Description
• The wet etching process involves:
– Transport of reactants to the surface
– Surface reaction
– Transport of products from surfaces
• The key ingredients are:
– Oxidizer (e.g. H2O2, HNO3)
– Acid or base to dissolve the oxidized surface
(e.g. H2SO4, NH4OH)
– Dilutent media to transport the products
through (e.g. H2O)
Bulk Micromachining
• Process for producing 3D MEMS
structures – older process
• Uses anisotropic etching of single crystal
silicon
• Example: silicon cantilever beam for
atomic force microscope
Mechanical Micromachining
• Lithography and/or etching methods not
capable of making true 3D structures e.g.
free form surfaces
• Also, limited in range of materials
• Mechanical machining is capable of
making free form surfaces in wide range of
materials
• Can we scale conventional/non-traditional
machining processes down to the micron
level? Yes!
Summary
• Micromachining methods
– IC fabrication based processes
– Mechanical machining based processes
• Applications in MEMS, medical device
fabrication, etc.
• Still evolving field
micromachining.pdf (Size: 3.08 MB / Downloads: 283)
Micromachining Basics
• Refers to techniques for fabrication of
3D structures on the micrometer scale
• Applications include MEMS devices
e.g. airbag sensor, medical devices,
micro-dies and molds, etc.
• Most methods use silicon as substrate
material
Photolithography
• Used in
(a)
microelectronics
fabrication
• Used to pattern
oxide/nitride/polysilicon
films on silicon
(b) substrate
• Basic steps
- ©
photoresist development
- Etching
- Resist removal
Wet Etching Process Description
• The wet etching process involves:
– Transport of reactants to the surface
– Surface reaction
– Transport of products from surfaces
• The key ingredients are:
– Oxidizer (e.g. H2O2, HNO3)
– Acid or base to dissolve the oxidized surface
(e.g. H2SO4, NH4OH)
– Dilutent media to transport the products
through (e.g. H2O)
Bulk Micromachining
• Process for producing 3D MEMS
structures – older process
• Uses anisotropic etching of single crystal
silicon
• Example: silicon cantilever beam for
atomic force microscope
Mechanical Micromachining
• Lithography and/or etching methods not
capable of making true 3D structures e.g.
free form surfaces
• Also, limited in range of materials
• Mechanical machining is capable of
making free form surfaces in wide range of
materials
• Can we scale conventional/non-traditional
machining processes down to the micron
level? Yes!
Summary
• Micromachining methods
– IC fabrication based processes
– Mechanical machining based processes
• Applications in MEMS, medical device
fabrication, etc.
• Still evolving field