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Micro/Nano Solids
Monash Uni Course
Question | Answer |
---|---|
Describe the Oxidation process | Individual atoms from surrounding environment penetrate the surface of the substrate and a thin layer is formed |
What temperatures do oxidation processes operate at? | 700 degrees |
Oxidation depends on which rates? | Chemical reaction at the interface, & diffusion of the oxidant through existing oxide layer |
Types of Chemical Vapour Deposition? | Low Pressure CVD (LPCVD), Plasma Enhanced (PECVD) |
Physical Deposition (Sputtering) | atoms ejected from a solid due to bombardment, high pressure |
Physical Deposition (Evaporation) | Metal source heated to melting, atoms transported with the vapor to the substrate, 1nm/min |
Chemical Deposition Process | Reactant comes to surface, adsorption at surface, reaction, desorption, transport of by product |
LPCVD Benefits | Control unwanted gas-phase reactions, improve film uniformity,minimise diffusion effects |
LPCVD Downsides | Can take 3hrs for 15nm, only 3 mins for deposition but the rest for controlling temperature and pressure |
PECVD Benefits | Faster than LPCVD,Lower temps are good for components with low melting temp. |
PECVD Downsides | Film quality is not as good |
Stress in deposited films is caused by | Lattice mismatch, differences in thermal expansion coefficients |
Photolithography - Preperation before coating | Clean wafer, apply primer, rotate, soft bake, exposure and post bake |
Photolithography - Exposure Methods | Contact, Proximity, Projection |
Types of Etching | Physical (plasma etching), Chemical (wet etching) |
Wet etchant to remove Si isotropically | KOH or TMAH (tetra methyl amonium hydroxide) |
Wet etchant to remove SiN (but not Si or SiO2) | H3PO4 |
Isotropically etch SiO2? | HF |