can i back my phone up while disabled

Nope. You will have to erase it using your computer with iTunes. If you haven't backed up the phone it's too late now.

See this link for directions on how to erase your phone to get back in --> If you forgot the passcode on your iPhone, or your iPhone is disabled - Apple Support

No, The time to make a backup is before catastrophe strikes! After is too late. Now you will have to follow the instructions in the blue link above your name on this page. The process will erase the phone.