Vapour Deposition Techniques

   

                                                                                                                                                                           Guide:Prof.Madhuri Deshpande Mam

 Blog Presented by :

                 Gaurav Matetwar 29 

                 Pranav Shinde 40

                 Atul Shingade 49

                 Atharva Taware 66

                 Niraj Deshmukh 70

Vapor deposition :

Vapor deposition techniques have been used for producing different types of materials, including fibers, nanotube, powders, thin films and graded composition deposits, for many years. Different categories of advanced materials, including nanocrystalline and amorphous metal, have been produced in the form of thin films, with thickness in the range between few nanometers and thousands of nanometers . There are two strategies of producing thin films via vapor deposition technique, known as (i) PVD and (ii) CVD.

PVD process :

PVD and EBPVD processes are atomistic deposition processes in which material is vaporized from a solid or liquid source in the form of atoms or molecules, transported in the form of a vapor through a vacuum or low-pressure gaseous (or plasma) environment to the substrate where it condenses . There are many ways for film depositions via PVD process, such as sputtering deposition, arc vapor deposition, and ion plating.

•Physical Vapour Deposition (PVD) is fundamentally a vaporization coating technique, involving transfer of material on an atomic level.

• It is an alternative process to electroplating.

•The process is similar to chemical vapour deposition (CVD) except that the raw materials/precursors.

•i.e. the material that is going to be deposited starts out in solid form, whereas in CVD, the precursors are introduced to the reaction chamber in the gaseous state.

Working Concept:

PVD processes are carried out under vacuum conditions.

 The process involved four steps:

1.Evaporation

2.Transportation

3.Reaction

4.Deposition

VARIENTS OF PVD

Evaporative Deposition In which

the material to be deposited is

 heated to a high vapor pressure by electrically resistive heating in "high“ Vacuum.

ELECTRON BEAM PHYSICAL
VAPOR DEPOSITION:

In which the material to be deposited is heated to a high vapor pressure by electron bombardment in"high" vacuum.

SPUTTER DEPOSITION:

In which a glow plasma discharge (usually localized around the "target" by a magnet) bombards the material sputtering some away as a vapor.

Importance of PVD Coatings:

• PVD coatings are deposited for numerous reasons

       Some of the main ones are:

• Improved hardness and wear resistance.

•Reduced friction.

• Improved Oxidation resistance.

•The use of such coatings is aimed at improving

      efficiency through improved performance and longer component life.

• They may also allow coated components to operate in environments that the uncoated component would not otherwise have been able to perform.

Applications:

• PVD coatings are generally used to improve

      Hardness, Wear Resistance And Oxidation Resistance.

•Thus, such coatings use in a wide range of

applications such as:

• Aerospace

•Automotive

• Surgical/Medical

• Dies and moulds for all manner of material

•Processing

• Cutting tools

• Fire arms  2626

CHEMICAL VAPOUR DEPOSITION

CVD is the formation of a non-volatile solid film

on a substrate by the reaction of vapor phase

chemicals (reactants) that contain the required

constituents.The reactant gases are

introduced into a reaction chamber and are decomposed and

reacted at a heated surface to form the thin film.

Steps involved in a CVD process (schematic):

Transport of reactants by forced convection to the deposition region.

Transport of reactants by diffusion from the main gas stream through the boundary layer to the wafer surface.

               

Adsorption of reactants on the wafer surface.

Surface processes, including chemical decomposition

    or reaction, surface migration to attachment sites (such as atomic-level ledges and kinks), site incorporation, and other surface reactions.

Desorption of byproducts from the surface.

Transport of byproducts by diffusion through the

     boundary layer and back to the main gas stream.

Transport of byproducts by forced convection away

    from the deposition region.

APPLICATION :

Coatings –

• Such as wear resistance

•Corrosion resistance,

• High temperature protection,

• Erosion protection and

• Combinations thereof.

 Semiconductors and related devices –

•Integrated circuits,

• Sensors and

• Optoelectronic devices.