Describe the steps in briefly as following: 

Physical evaporation is to heat the substance to volatilize and then deposit its vapor on a predetermined substrate. 

Because the evaporation source must be heated and volatilized and under condition of vacuum, 

it is so called hot or vacuum evaporation.

It can be divided into 3 steps as below: 
(1)  The condensed matter is heated and volatilized into a vapor phase
(2)  Steam moves in the air for a distance to the substrate
(3)  Steam is cooled and condensed into film on the substrate