Any etched layer suffers from undercut, s. e.g.dinesh hegde said:But why thicker metal suffers from under-etching? Dinesh
With pure wet (i.e. isotropic) etch, wouldn't it shrink by 2*2.6µm ?Colbhaidh said:...
The wet chemical etch etches isotropically so it etches sideways the same rate as vertically.
So a 2.6um thick metal feature will shring in size by about 2.6um.
So fabs use a combination of wet and plasma etches to reduce the dimensional loss.
Right.dinesh hegde said:One more observation is that via on wider metal also needs a more via overlap of metal.
No. It's due to insufficient OPC accomplishment, s. e.g.dinesh hegde said:Is this to take care of EM?
I guess it's the other way round. Otherwise all the semiconductor fabs' DR's would be wrongdinesh hegde said:But in OPC case, a metal with lesser width should get more affected than metal with more width.
erikl said:I guess it's the other way round. Otherwise all the semiconductor fabs' DR's would be wrongdinesh hegde said:But in OPC case, a metal with lesser width should get more affected than metal with more width.
dinesh hegde said:But in OPC case, a metal with lesser width should get more affected than metal with more width.
erikl said:I guess it's the other way round. Otherwise all the semiconductor fabs' DR's would be wrong
Guys,sandeep_torgal said:For lesser width metals even a small change makes a lot of % change and hence as Dinesh says the metal with lesser width should get affected more.
sandeep_torgal said:Since the metal is thicker and teh etch is isotopic, ...
Regards,
Sandeep
I tried to give a short explanation on the effect of OPC above; the algorithms behind it are quite complex, and I can't explain them better, nor do I own documents about OPC. If you're interested enough in it, I suggest you search for papers on OPC and study them.sandeep_torgal said:If the metals heights are same and the width varying, i still dont understand how the cutback of edges is proportional to the width of the structures... Let me know if you find any document online...
Regards,
Sandeep
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