Rifle or shot gun .... center of the back about at the junction of the front shoulder blades ... pull the trigger and it is a done deal.
Using archery gear, being that close, even the slightest noise of any sort will tense up the deer. At best it will freeze ... at worse , it'll blow out of there altogether. As far as arrow placement, the target area is relatively small compred to the full broadside. The broadhead must cut something vital. On super close broadside shots, the mistake is often aiming too high. If the deer is facing away, be careful to not get too far forward or you'll miss lung/heart area. If the deer is super close and facing you, a good shot placement is between the front shoulder blades. If the arrow blows through, be prepared for a weird blood trail. It'll usually be good at first then dry up to a trickle or less .... because gut or lung tissue plugs the exit hole. (Been there, doen that). If you can sever the spine, then the deer will not go far if anywhere at all. A broken spine too far back can result in a crippled (down in the back legs) deer that drags itself farther than you might expect before it gives out. So if you are going to try the "spine" shot, close to the front sholder blades is better. Miss a wee bit right or left and you should catch plenty of lung and maybe drive the broadhead into the heart area.