Exclude directory from project but display it in Project window

I have ‘cache’ directory in my PHP project that I don’t want to be indexed by PhpStorm and/or available for searching etc. to avoid unnecessary result entries while performing “Find...” operations etc. But I still want that directory available in Project window to have possibility to chose cached files manually and view them in Editor window. Is it possible to tune up PhpStorm to do so?
Thank you!