In [[chemical vapor deposition]] (CVD), a substrate is typically heated and exposed to one or more gaseous precursors, which decompose and react on the substrate surface to produce the desired thin-film material. CVD can be used to grow high quality and uniform thin films of various materials (mostly insulating or semiconducting).
CVD can be subdivided into classifications based on pressure requirements (atmospheric (APCVD), low-pressure (LPCVD), and ultra-high vacuum (UHCVD)). LPCVD is used in the LNF to deposit silicon dioxide, silicon nitride, and doped and undoped polysilicon. It can also be classified based on the mechanism used to decompose the source gas: plasma-enhanced CVD (PECVD) breaks apart gas molecules by application of ionizing voltage, whereas LPCVD and APCVD use elevated temperatures to cause the source gas to decompose. PECVD is used in the LNF to deposit silicon dioxide, silicon nitride, and amorphous silicon (a-Si:H). Catalytic CVD refers to CVD where the surface reaction is facilitated by the presence of a catalyst material on the substrate, or where the substrate itself is a catalyst for the growth reaction. [[Carbon nanotubes and graphene]] can be grown by catalytic CVD. Another type of CVD is metalorganic CVD, which uses organometallic gas precursors to grow III-V and II-VI compound semiconductors such as InP, GaN, AlGaAs, etc. Other example of CVD is the deposition of Parylene, in this case the solid Parylene dimer is
evaorated and separated into the monomer by heat and deposited in uniform, pin hole free thin films.
<!--The LNF has fourteen [[Low pressure chemical vapor deposition| Low Pressure CVD (LPCVD)]] furnace tubes for growing doped and undoped polysilicon, silicon dioxide, and silicon nitride. It has five [[Plasma enhanced chemical vapor deposition| Plasma Enhanced CVD (PECVD)]] chambers.-->