HR person contacted me first by phone. That was pretty straight forward HR related questions. Second interview was on phone with a Senior Scientist. That lasted for over an hour and it was mostly about previous research and a bit of technical know how. The last step was an onsite interview where i met a senior scientist followed by the guy in charge of that facility and the HR contact was also listening in through the conference call. The on site only lasted ~2 hours.

Phone screen involves talking to HR first to get a sense of who you are and also what the company does. Second round involves technical presentation to the group you'll be working in and questions about your research. There were also questions to make sure you have a baseline knowledge of organic chemistry.