The deposition of organometallic compounds from the gas phase ( English Metalorganic chemical vapor deposition ) is a method of chemical deposition from the gas phase by thermal decomposition ( pyrolysis ) of organometallic compounds to obtain materials ( metals and semiconductors ), including by epitaxial growth. For example, gallium arsenide is grown using trimethyl gallium ((CH 3 ) 3 Ga) and triphenyl arsenic (C 6 H 5 ) 3 As). The term itself was proposed by the founder of the method Harold Manasevit in 1968. [1] In contrast to molecular beam epitaxy (MBE, the term " molecular beam epitaxy ", MPE is also used), growth is carried out not in a high vacuum, but from a vapor-gas mixture of reduced or atmospheric pressure (from 2 to 101 kPa ).
Content
MOS hydride epitaxy system components
- A reactor is a chamber in which epitaxial growth occurs directly. It is made of materials chemically inert with respect to the chemical compounds used at high temperatures (400-1300 ° C). The main structural materials are stainless steel , quartz and graphite . The substrates are located on a heated substrate holder with temperature control. It is also made of materials that are resistant to chemicals used in the process (often they use graphite , sometimes with special coatings, and also some parts of the substrate holder are made of quartz). To heat the substrate holder and the reactor chamber to an epitaxial growth temperature, resistive or tube heaters, as well as RF inductors, are used.
- Gas circuit. The starting materials, which are under normal conditions in a gaseous state, are supplied to the reactor from cylinders through gas flow regulators . If, under normal conditions, the starting materials are liquids or solids (mainly all organometallic compounds used), so-called bubbler evaporators are used (eng. 'Bubbler'). In a bubbler evaporator, a carrier gas (usually nitrogen or hydrogen ) is blown through the bed of the starting chemical compound and carries away part of the organometallic vapors, transporting them to the reactor. The concentration of the starting chemical substance in the carrier gas stream at the outlet of the evaporator depends on the carrier gas stream passing through the bubbler evaporator, the pressure of the carrier gas in the evaporator and the temperature of the bubbler evaporator.
- The system for maintaining pressure in the reactor chamber (in the case of epitaxy at reduced pressure, the Roots vacuum pump or the rotary vane pump and the flap valve).
- The system of absorption of toxic gases and vapors. Toxic waste products must be transferred to the liquid or solid phase for subsequent reuse or disposal.
Starting materials
List of chemical compounds used as sources for the growth of semiconductors using the MOCVD method:
- Aluminum
- Trimethylaluminium CAS 75-24-1 Al (CH 3 ) 3
- Triethylaluminium CAS 97-93-8 Al (C 2 H 5 ) 3
- Gallium
- Trimethylgallium Ga (CH 3 ) 3
- Triethyl gallium Ga (C 2 H 5 ) 3
- Three ( iso- propyl) gallium Ga (C 3 H 7 ) 3
- Indium
- Trimethylindium In (CH 3 ) 3
- Triethylindium In (C 2 H 5 ) 3
- Nitrogen
- Phenylhydrazine
- Dimethylhydrazine
- Ammonia NH 3
- Phosphorus
- Phosphine PH 3
- Arsenic
- Arsine AsH 3
- Phenylarsin
- Antimony
- Trimethyl Antimony
- Triethyl Antimony
- Stibin SbH 3
- Cadmium
- Dimethyl cadmium
- Tellurium
- Dimethyltellur
- Diethtellur
- Di (isopropyl) tellurium
- Silicon
- Monosilane SiH 4
- Disilan Si 2 H 6
- Zinc
- Diethyl Zinc Zn (C 2 H 5 ) 2
MOCVD-grown semiconductors
III — V Semiconductors
- Gallium Arsenide ( GaAs )
- Indium Phosphide ( InP )
- InGaAs
- Inalas
- InGaAlAs
- InGaAsP
- InGaAsN
- AlGaAs
- InGaAs
- AlGaP
- InGaP
- Inalp
- Inalp
- Gallium Nitride ( GaN )
- InGaN
- InGaAlN
- Indium Antimonide ( InSb )
II — VI Semiconductors
- Zinc Selenide (ZnSe)
- CMT (HgCdTe)
See also
- Thin film spraying
- Chemical vapor deposition
- Gas phase epitaxy
Notes
- ↑ Manasevit HM Single-Crystal Gallium Arsenide on Insulating Substrates Appl. Phys. Lett. 12 , 156 (1968) DOI : 10.1063 / 1.1651934