Seriously, shurgs will hit the muscles at the back of your neck. I've heard of guys lying on a bench with a weight strapped to their head and doing neck bends. However, my neck has grown just from clenching my teeth while I lift.
Why do you want your neck to be thicker and stronger?
there is a neck machine I'm not sure the name of it I'll try and find out with my coach. BUT I've been doing neck in all 4 different ways like side to side then face down go forward then backwards go back. AND I've been doing this for about 2 months now and the weight has increased 30lbs from what I first used. And my shirt for work which is a collard shirt used to be 16 1/2 now I need a 17. So I've put on about 1/2-3/4 of an inch on my neck just in 2 months of using that machine. You might wanna try it.
I train on it once every two weeks. Maybe if I did it once a week it'd get thicker I might just try it out for a month or two.
I have a neck harness to work the rear and sides. I use a fixed
e-z curl bar gripped in the middle and rest it on my forehead while laying on a bench with my head hanging over the top.
Sorry for the run on sentence. I use a thumb under grip and rest them on my forehead for reps of 8.