11 week old baby fights sleep! Help!?

It's not like he just whinges for 5 minutes, he cries hard for maybe 15-20 minutes before he eventually gives in, and then he doesn't even sleep deeply for another 10 minutes at least, and this is with me rocking him in my arms, if I leave him in his cot to go off to sleep himself, he screams until he's hoarse! He wont take a pacifier at all, I've tried every type I an think of! Any mums got tips for me?