Micro and Nano Processing | Introduction to Thin Film Deposition Process


What is thin film deposition (coating)?

Thin film deposition (Plating) is the process of forming and depositing a thin film coating on the substrate material.Deposition of thin films of various materials on substrates is one of the important means of micro and nano processing.Films have many different properties that can be used to modify or improve certain elements of a substrate's performance. For example, transparent, durable and scratch resistant; increase or decrease electrical conductivity or signal transmission, etc.Thin film deposition thicknesses range from the nanometer to the micron scale.
Thin film deposition is an important manufacturing step in the production of many optoelectronic, solid-state and medical devices and products, including consumer electronics, semiconductor lasers, fiber lasers, LED displays, filters, compound semiconductors, precision optics, microscope and microanalysis sample slides and medical implants.

Comparison of thin film deposition process types and advantages and disadvantages

The most common thin film deposition processes used in micro and nano processing arePhysical Vapor Deposition (PVD)withChemical Vapor Deposition (CVD).

Physical vapor deposition (PVD) is a method of growing thin films on a substrate by heating the source material under vacuum to allow atoms or molecules to escape from the surface of the source material.The main methods of physical vapor deposition are vacuum electron beam or resistance vapor deposition, sputtering coating, arc plasma coating, ion coating, and molecular beam epitaxy, etc. The electron beam evaporation system and sputtering system of AEMD are both physical vapor deposition.

ThingsPhysical Vapor Deposition (PVD) can be divided into two main categories, thermal evaporation deposition and plasma sputtering deposition.Thermal evaporation deposition:Resistance evaporation deposition, ,Electron beam evaporation deposition;.Plasma sputtering deposition: TheDC sputtering, RF sputtering, magnetron sputtering, ionized PVD.


Chemical Vapor Deposition (CVD) is a process that causes a gaseous substance to react chemically on the surface of a solid and deposit on that surface to form a stable solid film.There are four main important stages: 1) diffusion of the reaction gas to the substrate surface; 2) adsorption of the reaction gas to the substrate surface; 3) detachment of the gas phase by-products generated on the substrate surface from the surface; and 4) formation of a cladding layer from the reactants left behind. The use of techniques such as plasma and laser assistance can significantly facilitate the chemical reactions so that deposition can take place at lower temperatures.

Chemical Vapor Deposition (CVD)Including low pressure type (LPCVD), atmospheric pressure type (APCVD), atomic layer deposition (ALD), plasma enhanced type (PECVD) and metal organic compound type (MOCVD), etc.


Atomic Layer Deposition (ALD)It is a type of chemical vapor deposition (CVD) method, which is a method that allows a substance to be plated on the surface of a substrate in the form of a single atomic film layer by layer. Atomic layer deposition has similarities with ordinary chemical deposition. However, during atomic layer deposition, the chemical reaction of a new layer of atomic film is directly associated with the previous layer, allowing this method to deposit only one layer of atoms per reaction.

Comparison of the advantages and disadvantages of various thin film deposition methods
CraftsmanshipAtomic layer deposition
Physical Vapor Deposition
Chemical Vapor Deposition
Low Pressure Chemical Vapor Deposition
(LPCVD furnace tube)
Deposition principleChemical surface saturation
Evaporation-ConsolidationGas phase reaction - depositionLow Pressure Chemical Vapor Deposition
(Stove and tube type)
Deposition processLaminar growthNucleation growthNucleation growthNucleation growth
Step coverageExcellentGeneralGoodGood
Deposition rateslowQuickQuickslower
Deposition temperatureLow(<500℃)LowHighHigher
0.07 - 0.1nm
About 5nm
0.5 - 2nm


Thickness controlNumber of reaction cyclesDeposition timeDeposition time
Gas phase partial pressure
Deposition time
Gas ratio
IngredientsUniformity with few impuritiesNo impuritiesEasy to contain impuritiesNo impurities


Film types and application scenarios

Film TypeClassificationThin film deposition materialsApplications
SemiconductorsPolysiliconSiH4 (silane)Gates of MOS, high value resistors, etc.
Monocrystalline siliconSiH₂Cl₂(Dichlorosilane; DCS)Single crystal epitaxial layer for power devices, etc.
SiHCl3 (trichlorosilane; TCS)
SiCl4 (Silicon chloride; Siltet)
Amorphous SiliconSiH4 (silane)Alpha-Si solar cell, source/drain trench area, etc.
Dielectric qualitySi02 (silicon dioxide)SiH4, O2
SiH4, N20
Si(OC2H5)4 (tetraethoxysilane), O2/O3
Most widely used dielectric films, STI, gate oxide, sidewall, PMD, IMD, barrier, hard mask, etc.
Si3N4/SiN (Silicon Nitride)SiH4, N2O, N2, NH3
C8H22N2Si [ Bis(tert-butylamino)silane ]
Etch stop layer, hard mask, passivation layer, etc.
SiON (Silicon Nitride)SiH4, N2O, N2, NH3Anti-reflective layer, oxide layer, hard mask, etc.
(Phosphorsilicate / Borosilicate glass)
Silane, borane, phosphorane, etc.PMD, passivation layer, etc.
Low- K (low dielectric) materialsPolyimide (PI), etc.Replacement of SiO2 in PMD
High-K (high dielectric) materialsHf, O2, SiO2, etc.Replacement of SiO2 in the grid media layer
Metal compounds
W (Tungsten)WF6 (tungsten hexafluoride), SiH4, H2Electrical films, optical films, hard films, corrosion-resistant films, contact holes, through-holes, gates, etc.
WF6, silane, etc.Silicide layer on source/drain/gate
TiNTi[N(CH3)2]4 [ tetrakis(dimethylamino)titanium ]Barrier layer, metal grille, etc.
TiTiCl4 (titanium chloride)
Au/Al/Cu Metal layers, metal grids, etc.


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