Methods for determining a target thickness of a conformal film with reduced uncertainty, and an integrated circuit (IC) chip having a conformal film of the target thickness are provided. In an embodiment, a first critical dimension of a structure disposed on a wafer is measured. Said structure has at least one vertical surface. A first conformal film is deposited over the structure covering each of a horizontal and the vertical surface of the structure. A second critical dimension of the covered structure is then measured. The target thickness of the conformal film is determined based on difference between the first CD measured on the structure and the second CD measured on the covered structure.