In this method, a vertical stack is formed on an axis coinciding substantially with the gravity direction and comprising, from top to bottom: the element; the mass in a solid state; and the substrate. The mass is then heated so as to cause it to pass into a liquid state enabling it to spread on the substrate. More particularly, after the stack has been formed, the element is left free to move vertically, and during heating, variation in the vertical position of the element is measured.