There is a fancy foam target that is designed for broadheads that can be purchased at most archery shops. My brother-in-law has one and I've used it......it works well for steel broadheads.
My own personal favorite target for hunting arrows is a cardboard box stuffed with the kind of foam they use for cushions and such. It's about 1-1/2" thick and has a flat side and a bumpy side. The foam stops arrows quickly but is very gentle on the arrow heads. Doesn't work too good for barbed tips, though. A big pile of dry, loose dirt probably works better.