Is it safe to bottle feed a baby in their crib in order to get them to fall asleep?

I have a 3 month old that has a hard time falling asleep on his own. I've tried pacifiers and picking him up after he fusses for a few minutes, but none of that works anymore. The only way he will fall asleep in the crib is when I feed him a couple of ounces from a bottle while he is in the crib. Eventually when he falls asleep I take the bottle out of his mouth, but I need to know if this is safe or not. Any advice would be great because I don't want this to become a habbit for him.