Thank you Jürgen Weippert for sharing your knowledge. But I'm much interested to know this phenomenon of thin film deposition in detail (with an explanation).
Well, then you have to ask a more precise question. There are whole textbooks on the topic of PVD, so you can't expect people to write a novel just building on a guess what you want.
Jürgen is more than right! I even suggest that you put more work into it by doing a detailed literature search and even go into the library and open some books. It also helps to carefully set up the question in the detail you require. Doing this may help to find the answer yourself.