Chemical vapor deposition

Chemical vapor deposition is a method of putting a thin layer of materials on to a surface using very low heat. It is specially useful for coating thin glass with metal without damaging the glass, using such a thin layer of metal that the glass can be seen through. This technology was invented by the Head of the Chemistry Department of Harvard University, Professor Roy Gordon, in the 1970s and perfected by his team during the 1980s. Chemical vapor deposition has a vast range of uses. Hip replacement joints are coated using chemical vapor deposition to make them lighter, stronger, and longer lasting. TFT displays (flat screen televisions and computer monitors) are made using chemical vapor deposition. This technology is also used to prevent double glazing windows and supermarket freezers from steaming up. Chemical vapor deposition can be used to create synthetic diamonds.

 Types of CVD 
CVD techniques vary by chemical reaction mechanisms and process conditions.

Classification by Pressure:

 Atmospheric Pressure CVD (APCVD): Performed at atmospheric pressure.
 Low-Pressure CVD (LPCVD): Operates under reduced pressure to improve film uniformity and reduce unwanted reactions. Common in current processes.
 Ultrahigh Vacuum CVD (UHVCVD): Conducted at extremely low pressures (~10⁻⁶ Pa or lower).

Classification by Vapor Characteristics:

 Aerosol Assisted CVD (AACVD): Uses aerosolized liquid or gas precursors for fast growth, suitable for low-volatility precursors.
 Direct Liquid Injection CVD (DLICVD): Injects liquid precursors which vaporize and deposit onto substrates. Applicable to both liquid and dissolved solid precursors.

Plasma-Enhanced Techniques:

 Microwave Plasma-Assisted CVD (MPCVD)
 Plasma-Enhanced CVD (PECVD): Increases reaction rates using plasma, enabling low-temperature deposition widely used in semiconductor manufacturing.
 Remote PECVD (RPECVD): Similar to PECVD but wafer is outside plasma region, allowing room temperature processing.

Others:

 Atomic Layer CVD (ALCVD): Sequential atomic-scale deposition for precise thin films.
 Hot Wire CVD (HWCVD): Uses heated filaments to decompose source gases catalytically.
 Metalorganic CVD (MOCVD): Uses metalorganic precursors.
 Hybrid Physical-Chemical Vapor Deposition (HPCVD): Combines chemical decomposition and evaporation from solid sources.
 Rapid Thermal CVD (RTCVD): Quickly heats wafer without heating gases or chamber, reducing unwanted reactions.
 Vapor Phase Epitaxy (VPE)

 Other websites 

 Roy Gordons Glass  in the Harvard Gazette

Category:Technology
Category:Chemical processes