Method for forming film

A method for forming film comprising following steps of:

• performing a desublimation process, the desublimation process includes following steps of:
• providing a workpiece into a chamber device;
• providing a gaseous state sacrificial material into the chamber device, wherein the gaseous state sacrificial material is composed of iodine;
• and
• controlling a temperature of the workpiece within a desublimation temperature range, so that the gaseous state sacrificial material desublimates into solid state on a surface of the workpiece to form a solid state sacrificial material layer on the surface of the workpiece, wherein during the desublimation process, the desublimation temperature range is smaller than or equal to 110° C., and a pressure in the chamber device is greater than or equal to 1 atm;
• and
• performing a sublimation and deposition process, the sublimation and deposition process includes following steps of:
• controlling the pressure in the chamber device within a sublimation deposition pressure range, and controlling the temperature of the workpiece in the chamber device within a sublimation deposition temperature range, so that the solid state sacrificial material layer on the surface of the workpiece starts gradually sublimating into gaseous state;
• and
• providing a plurality of reactive polymer monomers into the chamber device, so that the plurality of reactive polymer monomers starts being deposited on the solid state sacrificial material layer on the surface of the workpiece through an adsorption process, and a polymerization reaction of the plurality of reactive polymer monomers is initiated, at the same time, the solid state sacrificial material layer continues gradually sublimating into gaseous state;
• until the solid state sacrificial material layer completely sublimates into gaseous state, and the plurality of reactive polymer monomers forms a polymer layer deposited on the surface of the workpiece after the polymerization reaction.