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What are differences between Si(111), Si(110) and Si(100) ?
Posted: Wed Apr 09, 2014 8:56 pm
What are differences between Si(111), Si(110) and Si(100) ? Does they means that they are different wafers with different orientation or they are same wafers with all these orientation containing in a single wafer.? If they are different wafers then how can we explain the Anisotropic Etching of Silicon.
Re: What are differences between Si(111), Si(110) and Si(100
Posted: Thu Apr 10, 2014 10:50 am
In Anisotropic Etching we say that etch rate in one orientation say (100) is higher than etch rate in another orientation say (111) i.e. we get
less etching in (111) plane and more etching in (100) plane and we are able to form V -shape etched surface in Silicon wafers.
It means both (100) plane and (111) planes are in a single Silicon wafer.
If they are same wafers with all (111)planes, (110)planes and (100) planes inside one wafer then
how can we explain the use of (100) Silicon Wafers for MOSFETs and (111) Silicon Wafers for BJTs.
In MOSFET we use Si(100) wafers because they have less broken bonds on surface than Si(111) and we want clean surface for MOSFET.
In BJT we use Si(111) wafers because they offers high oxidation rates and it helps in reducing time for oxidation process.
It means Si(100) and Si(111) wafers are different wafers.
Also Silicon has more atomic density for Si(111) than Si(100).
Does it means that atomic density of Silicon for Si(111) wafers are more than atomic density of Silicon for Si(100) wafers where Si(100) and Si(111) are separate wafers.