Free spice Model to simulate integrated circuits design
If you're just looking for a rough model, then there are two sources of IC models that are free and readily available. The first is ASU's Predictive Technology Models, which allow you to download models that should be representative of a particular process node. These models let you go way down in feature size (e.g. 7nm), but they are predictions of what that process node looks like. The newer models use BSIM4, and I'm not sure if that is supported with LTSpice. The other is the post-run SPICE measured date provided by MOSIS on some processes. This will give you measured parameters for an actual IC run, but it is only available on some of their older(est) processes.