A merck employee encouraged me to apply. I had a first phone interview with someone who had the position I was applying for, and then a second with the hiring manager, who would be the boss. Both were relatively relaxed interviews, and during the second the hiring manager told me they wanted to have me out for a visit. About a month later I had the interview onsite, I gave a talk and met with ~ 8 people including an HR rep, and various team members I would work with. Most were friendly, and excited about the work they were doing there. Some had serious questions, but nothing that was trying to trip me up.