Coating apparatus – Immersion or work-confined pool type – Work-confined pool
Patent
1984-06-29
1986-07-29
McIntosh, John P.
Coating apparatus
Immersion or work-confined pool type
Work-confined pool
118415, H01L 21208
Patent
active
046025928
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to apparatus for carrying out liquid phase epitaxy growth where, a predetermined number of melts are heated in a first step and where, in a second step a substrate is moved into successive contact with the melts for growing a number of epitaxial layers on the substrate corresponding to the number of melts.
BACKGROUND
A method and apparatus for liquid phase epitaxy growth is known, e.g. from the Swedish Patent Specification 363 986. In the apparatus illustrated in FIG. 8 and FIG. 9 in this specification the very severe purity demands placed on the grown epitaxial layers which are to be used in lasers and optical detectors are not fulfilled. In moving the substrate between the melts, drops of melt can fasten on the edges of the substrate or in certain defects, e.g. crystalline holes, on the substrate and be transferred to the next melt which thus becomes contaminated.
In the process described in the above-mentioned Swedish Patent Specification, the substrate is adjacent the melt holder during the entire time required for heating the melts, which causes thermal erosion in the substrate.
In the illustrated apparatus, the substrate holder with the substrate cannot be drawn back, after completed growth of all the desired layers, for beginning the growth of a new substrate, and it is necessary to wait until these melts in the melt holder have solidified so as not to contaminate the melts.
SUMMARY OF THE INVENTION
The object of the present invention is to provide an apparatus for liquid phase epitaxy in which the very severe purity demands on the epitaxial layers for lasers and optical detectors are fulfilled, while at the same time the growth of a new substrate can be started directly after the growth of the preceding substrate has been terminated.
This is achieved by the apparatus in accordance with the invention comprising a melt holder having a predetermined number of cells, each for receiving a melt, for growing on a horizontally disposed substrate a number of epitaxial layers corresponding to the number of melts, a displaceable substrate holder disposed under the melt holder and supporting said substrate to bring the substrate successively in contact with respective melts, a melt filler disposed above said melt holder and having a number of compartments corresponding to the number of cells of the melt holder, said compartments being of greater volume than that of the cells for storing batches in the compartments corresponding to several melts in the cells, a perforated plate disposed between the melt filler and the melt holder for controlling communication between said compartment and the respective cells, said plate being displaceable to a position to bring its perforations into communication with said compartments and with said cells for filling of said cells from said compartments, and a melt collector under said melt holder, said melt collector including a number of compartments corresponding to the number of cells in said holder for receiving melt from said cells, said melt holder and perforated plate being disposed between said melt filler and said melt collector, said melt holder including a bottom which is displaceable by said substrate holder, said compartments in said melt collector being of greater volume than that of said cells for collecting several melts from respective cells, said substrate holder being displaceable forwardly to bring the substrate successively into contact with the respective melts and also being displaceable backwardly a distance, after growth has taken place in contact with each melt, to form an intermediate space between said substrate holder and said displaceable bottom of the melt holder through which space the respective melt can flow into the associated compartment in said melt collector before the substrate holder is displaced forwardly to bring the substrate under the next melt in the melt holder, said melt filler and melt collector being substantially identical so that after the melt filler is emptied, it c
REFERENCES:
patent: 4028148 (1977-06-01), Horikoshi
patent: 4338877 (1982-07-01), Yamanaka et al.
patent: 4357897 (1982-11-01), Leswin
Blum et al., Liquid Phase Epitaxy Growth of DH Laser Arrays, IBM Technical Disclosure Bulletin, vol. 15, No. 7 Dec. 1972, p. 2091.
McIntosh John P.
Telefonaktiebolaget LM Ericsson
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