How can we get a double gate FET or FINFET in Virtuoso Analog Design Environment for RF design??? do we want to go for some additional library files for extracting the cell??? If so, can you specify the path needed for the same???
I believe IC 6.1.5 supports FINFET devices. We are using them.
This is essential a function of what your design kit provides. There are some specific layout features related to FinFETs in ICADV12.1 (which is the IC release for 20nm and below, including double patterning support, etc), but in terms of PDK support, you should contact your foundry.
There's no specific component for FINFET in analogLib; as I said, this would normally be provided by a PDK provider.
You could of course create your own symbol, and define the CDF to have suitable parameters; not sure which model you're using (maybe bsimcmg?). There are countless posts (and a blog from Tawna) explaining how to reference an external spectre model.