Thermo-Chemical Vapor Deposition

Thermo-Chemical Vapor Deposition
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Chemical Vapor Deposition (CVD) is one of the processes developed on the basis of vacuum-assisted deposition technology, which could generate coatings from nearly all material family including metals and non-metal, compounds like carbides, nitrides, oxides, intermetallic and many other materials. Chemical vapor deposition is concisely defined as formation and deposition of a solid layer derived from chemical reaction and/or reactions of gaseous species present in a coating chamber.
The resulting solid film could be applied onto the substrate in form of amorphous phase, polycrystalline, and/or single crystals with exceptional properties. So far, the CVD technology has remained without rival in some areas including; Semiconductor and other electronic component manufacturing processes, coating on tools, bearings and other wear and corrosion resistant equipments, and optical and optoelectronic devices.
Like all chemical reactions, CVD processes need an activation energy for triggering reactions. The most common method is use of thermal energy which is currently known as the main one for chemical deposition of metals and ceramics from vapor phase. A thermal chemical vapor deposition (TCVD) apparatus consists of four main components including; a reactant-gas supply system, a deposition chamber called reactor, and an exhaust system. A fourth component that is often used today is a computer-based process control monitor, which is tasked with monitoring and controlling CVD's operational parameters.
The CVD's mechanism, operation and apparatus is in much the same way as PVD's, with one major exception; in PVD processes, unlike CVD, the responsible deposition processes much more deal with physical reactions rather than chemical ones. Conversely, the deposition processes of CVD completely depend on chemical reactions, some of which are; thermal decomposition, reduction, hydrolysis, oxidation, carburization, and nitriding. Theses reactions could occur either singly or in combination. The CVD reactions could be controlled by these factors; chemistry of reactions, thermodynamic (temperature, pressure, and chemical activity), mass transport and kinetic considerations.
Although theoretical consideration before practical tests could be a useful guideline for determination of chemical reaction route and product composition estimation, yet the best theoretical models finally need some practical approaches. Likewise, for the sake of considerations (such as fluid dynamic and chemical equilibrium aspects of reactions) to be reckoned as a way of improving efficiency, the need for trial-and-error-based methods is necessitated. To simulate CVD's processes, many codes entailing fluid dynamic relations have been developed which are now being used to maximize product capability in reactors producing. Such simulating codes could encompass reaction rate theory, thermodynamic equilibrium aspects, and restrictions imposed by the chamber design.
Some of CVD's applications in a variety field of science and technology have been mentioned as follow;
  • Microfabrication processes widely use CVD to deposit materials in various forms, including: monocrystalline, polycrystalline, amorphous, and epitaxial.
  • Artificial diamonds
  • Silicon dioxide synthesis
  • wear and corrosion resistant coatings on tools, bearings and drills
  • photovoltaic devices
  • Integrated circuits (ICs)
  • Polymerization
  • Super-thin coatings
  • Carbon nanotubes
  • MEMS (Micro-Electro-Mechanical Systems)
  • Semiconductor device fabrication
  • optical and optoelectronic devices
TCVD system is a cost efficient and high performance chemical vapor deposition system. More details about the TCVD system have been listed in the Table.
Today, CVD is a basic tool of manufacturing a wide range of material and industrial devices. The other main usage is in microfabrication processes such as production of much of today’s electronics. Besides, CVD has found such applications in some Nanotechnology's domains that remained without rival so far. The best example of such applications is the production of a wide variety of the carbon allotropies including nanofibers, nanotubes, Nano diamond, and graphene.
  • For the operator's convenient, the laboratory must allocate an area at least 25 square meters for the apparatus.
  • The apparatus must be located on the stable, vibration free and horizontally aligned table capable of bearing the load about 400Kg.
  • The vacuum pump must be located near the apparatus and on the vibration damper.
  • The system's gases cylinders must be located near and fastened to the wall.
  • While coating deposition especially after prolonged time, do not touch outer and inner sides of the apparatus.
  • Never use flammable and/or combustible materials, it may cause to fire or explosion. This apparatus contains parts that may explode flammable materials.
  • According to the very high operating temperature, consider the electrical connection of the apparatus to the ground.
  • Before the beginning of every coating session, check all connection of gases cylinders for possible leakage.
  • Use a proper power outlet with an adequate voltage and current capacity (at least 15 A).

Product Standard

  • NanoScale Certification

    Standard Date : 2017/03/08

    Expire Date : 2020/03/07



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