Apparatus for growing epitaxial layers on wafers by chemical vapor deposition

#The present invention relates to making semiconductor components and more particularly relates to devices for growing epitaxial layers on substrates, such as wafers.

#Various industries employ processes to form thin layers on solid substrates. The substrates having deposited thin layers are routinely used in microprocessors, electro-optical devices, communication devices and others. The processes for deposition of thin layers on solid substrates are especially important for the semiconductor industry. In the manufacturing of semiconductors, the coated solid substrates, such as substantially planar wafers made of silicon and silicon carbide, are used to produce semiconductor devices. After the thin firm is deposited, the coated wafers are subjected to well-known further processes to form semiconductor devices such as lasers, transistors, light-emitting diodes, and a variety of other devices. For example, the thin layers deposited on the wafer form the active elements of the light-emitting diodes.

#The materials deposited on solid substrates include silicon carbide, gallium arsenide, complex metal oxides and many others. The thin films of inorganic materials are typically deposited by processes collectively known as chemical vapor deposition (CVD). It is known that the CVD processes, if properly controlled, produce thin films having organized crystal lattices. Especially important are the deposited thin films having the same crystal lattice structures as the underlying solid substrates. The layers by which such thin films grow are called the epitaxial layers.

#A more accurate appreciation of the subject matter of the present invention and the various advantages thereof can be realized by reference to the following detailed description, which makes reference to the accompanying drawings in which:

#FIG. 1 is a highly schematic front cross-sectional view of a CVD reactor of the prior art;

#FIG. 2 is a highly schematic diagram of the wafer-supporting assembly of the present invention, showing the heating filament that also serves as a susceptor, and, optionally, as a wafer carrier;

#The general concept of the invention is shown in FIG. 2. The apparatus of the invention includes a reaction chamber 100, a rotatable spindle 110, a heating filament 120, and rotatable electrodes 130 and 130A. The rotatable electrodes 130 are mounted on the spindle 110 inside the reaction chamber 100. The heating filament 120 is mounted on the rotatable electrodes 130, establishing an electrical contact with the electrodes 130 and 130A. The heating filament 120 has a top surface 121, which includes one or more cavities 140 for retaining wafer(s) 10. During the deposition, electric current is passed through the electrodes 130 and 130A and, by way of the established electrical contact, through the heating filament 120, thereby heating the filament. At the same time, the rotatable spindle 110 may be rotated during the deposition, thereby rotating the electrodes 130 and 130A, and the wafer(s) 10, and enabling the growth of epitaxial layers on the surface of the wafer(s).

#The reactor of the invention may be used for coating a single wafer or a plurality of wafers. Accordingly, the top surface 121 of the heating filament 120 may be adopted either for a single wafer or a plurality of wafers in any manner known in the art. Preferably, the top surface 121 has a plurality of cavities 140 for placing a plurality of wafers 10.

#As seen from a comparison of the highly schematic diagram of the inventive CVD reactor (FIG. 2) with the prior art reactor shown in FIG. 1, the principal difference between them is the elimination of the susceptor 14 and the wafer carrier 12 from the wafer-supporting assembly. In effect, in the reactor of the invention, the wafers 10 are placed directly onto the surface of the heating filament 120, which is designed accordingly to provide a support for the wafers. Therefore, the heating filament 120 simultaneously heats and supports the wafers 10 during the deposition, performing the functions of both the susceptor 14 and the radiant heating assembly 20 of the prior art reactor of FIG. 1.