LNA input pad shielding

Hi all ,

I want to know why the lna input pad need to be shielded? And I don't know if in rescent RF cmos process the substrate resistivity is very small, so the substrate res from a large distance is also very small?

If the substrate resistivity is very small , is the lna input pad needed to be shielded?

I did not understood.
shielding means covering with a lid or so. I don not know about this method. Will you please explain more?

yes . you do need to shield this pad.
metal 1 is a good choice.