I think it may be a bit over the top to say that 90% scientists in certain scientific fields are atheists. Everything I've read shows about 50% being non-religious (which in itself is far larger then the average population in most countries and is quite remarkable). In a few books I've read it also seems to be that the scientests that are considered the most accomplished and recognised by their peers (which in the books was the people that were accepted into the Royal societies in England and other equivalent organisations across the world) had even high levels of non-religion (athiesm, agnosticism and deism etc, with rough breakdowns I can't remember).
Being a scientist doesn't mean you have to be an athiest, but it certainly seems more likely then in the normal population by a large margin.
And even if a scientist does believe in some kind of God or life force or something, it seems likely that it would be a very different one to the one people think of in the street, it'd be more abstract and probably far less anthropic and less interventionist. Or it would probably be some kind of pantheistic notion. Just speculating here of course.
Sorry for the lack of sources, its all in books that I can't find atm since I'm still unpacking from a move.
