Vacuum coating machineMainly refers to a type of coating that needs to be carried out under high vacuum conditions，Specifically, it includes many types，Including vacuum ion evaporation，Magnetron sputtering，MBEmolecular beam epitaxy，PLDLaser sputtering deposition and many other methods。The main idea is to divide intoevaporationandspattertwo kinds。

The substrate that requires coating is called a substrate，The plated material is called a target material。 The substrate and target material are both in the vacuum chamber。

Evaporative coating is generally achieved by heating the target material to evaporate surface components in the form of atomic groups or ions。And settle on the surface of the substrate，Through the film-forming process(splashed-Island structure-Maze structure-layer growth)Forming a thin film。 For sputtering coatings，It can be simply understood as using electrons or high-energy lasers to bombard the target material，And the surface components are sputtered out in the form of atomic clusters or ions，And ultimately deposited on the surface of the substrate，经历成膜过程，Eventually forming a thin film。

Concept of film uniformity

1.Uniformity in thickness，It can also be understood as roughness，At the scale of optical thin films(i.e.1/10Wavelength as a unit，Approximately100A)，The uniformity of vacuum coating is already quite good，It is easy to control the roughness within the visible light wavelength1/10in range，That is to say, for the optical properties of thin films，Vacuum coating has no obstacles。 But if it refers to the uniformity at the atomic layer scale，That is to say, to achieve10Aeven1AThe surface is flat，Specific control factors will be explained in detail below based on different coatings。

2.Uniformity in chemical composition: That is to say, in the thin film，The atomic components of compounds can easily exhibit non-uniform properties due to their small scale，SiTiO3film，If the coating process is not scientific，So the actual surface components are notSiTiO3，And it could be other proportions，The plated film is not the desired chemical composition of the film，This is also where the technical content of vacuum coating lies。 The specific factors are also given below。

3.Uniformity of lattice order: This determines that the thin film is a single crystal，polycrystalline，Amorphous，It is a hot topic in vacuum coating technology，

There are two main categories for classification: Evaporative deposition coating and sputtering deposition coating，Specifically, it includes many types，Including vacuum ion evaporation，Magnetron sputtering，MBEmolecular beam epitaxy，Sol gel method, etc 。

one、For evaporative coating:

Generally, heating the target material causes surface components to evaporate in the form of atomic clusters or ions。

The uniformity of thickness mainly depends on:

1。The degree of lattice matching between substrate material and target material

2、Surface temperature of substrate

3. Evaporation power，速率

4. vacuum degree

5. Coating time，厚度大小。

compositional homogeneity:

It is not easy to ensure the uniformity of components in evaporative coating，The specific factors that can be regulated are the same as above，However, due to the limitations of the principle，For non single component coating，Poor uniformity of components in evaporative coating。

Uniformity of crystal orientation:

1。Lattice matching degree

2。 substrate temperature

3。evaporativity

Sputtering coating can be divided into many types，Overall，The difference from evaporation coating is that sputtering rate will become one of the main parameters。

Laser Sputtering Coating in Sputtering Coatingpld，Component uniformity is easy to maintain，However, the thickness uniformity at the atomic scale is relatively poor(Because it is pulse sputtering)，crystal orientation(Outer edge)The control of growth is also relatively average