[extropy-chat] diffraction limit

[Dan Clemmensen]

scerir wrote:

>From: "Dan Clemmensen" 
>
>>
>>4) There is a lower bound on the length at which a classical model can 
>>be used at all.
>>    
>>
>>I really don't know where these bounds are. The existence of (4) makes 
>>me very skeptical of nano-electronics.
>>    
>>
>
>I've read that in MPU applications the gate physical thickness
>will reach 1 nm in 2006! Is it true? With such thickness, 
>tunneling leakage current becomes relevant, unless they
>introduce a higher dielectric constant material.
>
>  
>
HI-K dielectrics are important, but not precisely for this reason. Gate 
"thickness" is at best loosely related to photolithographic dimensions. 
The latter are what we have been discussing. Thickness has to do with 
material depositions, and can already be controlled to within a very few 
atomic layers.(by analogy, you can easily paint a very thin and uniform 
thickness of paint with a spraygun, but you cannot paint a narrow sharp 
line.)  In general, tunneling seems to be designed in and/or accounted 
for in the vertical dimension. The big problem in this dimension will be 
when tunneling establishes paths between layers that are not supposed to 
be there. In the horizontal dimension, as features get smaller, we will 
reach the point where the same thing happens in this dimension. My 
uneducated guess is that this imposes a lower bound on feature 
separation. Consider the "simple" case of two copper paths , or two 
nanowires, that are supposed to be electrically separate. If you place 
them close enough together, a tunnel current will flow between them.