Wow, I guess the only way to stop them is a solid fence that they can't dig under. They will keep coming back as long as they have success getting food. You could let the chickens run free on days when someone can be there to protect them, or you might think about a guard dog, but they have to be raised around chickens and learn not to hurt them. Coyotes have become pretty brazen and have almost no predictors. They just keep multiplying, and now are moving into residential areas as well. You might check with your local county officials and see if they might put a bounty on them to start thinning the population.
