Chapter Extra-2 Micro-fabrication process. Si wafer fabrication IC fabrication Deposition Spin coating PVD – physical vapor deposition CVD – chemical vapor deposition Lithography (Pattern transfer) Removal (mostly etching process) Wet/Dry etching Plasma etching
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ChipsProcess flow of IC & MEMS fabrication
Czochralski process: widely-used to make single crystal Si
CMP is used.. Why?
Smart cutting process?
-Physical Vapor Deposition - Sputtering
Mechanism: Physical process by impact of ions (plasma state)
(1) impacting target surface with accelerated ions (Ar+)
(2) knocking out atoms from the target surface
(3) transporting atoms to the substrate for deposition
(4) spin the substrate to achieve uniform thickness
SiCl4+ H2Chemical Vapor Deposition - CVD
Isotropic vs. Anisotropic etching
Anisotropic etching of Si
Principle : Plasma is struck in the gas mixture and ions
accelerated toward the substrate
Reaction occurs on the surface (chemical)
Impact of ion is similar to sputter etching (physical)
Controlling balance between chemical and physical
Physical : Anisotropic
Chemical : Isotropic
Deep RIE (DRIE) : altering two gas compositions
High aspect ratio of 50:1, High etching rate
Example of Bad Luck !!
DRIE and LIGA:
for high aspect ratio products
but different process
Think of SCALE-BRIDGING concept
Think of applying your major to micro-scale !