I had a phone interview a few months after applying online which consisted mainly of behavioral questions and why I'd like that jobs. I was called a month later for an on-site interview - all expenses paid by 3M. They invited all of the candidates together, which is a bit unnerving. They had a rotated schedule between meeting with the bosses of the department, the hiring managers, and a tour of the facility. The people were all very nice, and you can tell that they very much instill the values of 3M.