41
Figure 3.6 Fig 3.6: Applied Materials Centura Epi RPCVD schematic
Fig 3.6 shows the schematic of the Epi reactor. It is a multi-chamber system. Wafers
are loaded into the vacuum load lock, which is then pumped to 80 torr. A wafer is then
transferred into the transfer chamber before being moved into the deposition chamber.
The wafer is put on a rotating support plate in the deposition chamber. Gas comes in
from an injector on one side of the deposition chamber and is evacuated on the other
side. The carrier gas and reactant gases flow across the
rotating wafer during the
deposition.
42
Figure 3.7: Schematic diagram of the Centura gas flow control system
The schematic of the gas control panel is shown in Fig. 3.7.
The reacting gases
include silane (SiH
4
) and dichlorosilane (DCS) for Si, germane (GeH
4
) for Ge and for
SiGe alloy growth. Different concentrations of diborane (B
2
H
6
), arsine (AsH
3
), and
phosphine (PH
3
) are used as dopants. The carrier gases are hydrogen and nitrogen, and
the etching gas is HCl. The diluted dopant can be injected directly into the main gas
stream or further diluted to obtain a wide range of different doping concentrations.
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