Semiconductor crystal growth apparatus

Abstract

A substrate is heated in a crystal growth vessel evacuated to a ultrahigh vacuum, and gases containing component elements of a crystal to be grown on the substrate are introduced into the vessel under predetermined conditions to cause successive epitaxial growth of single molecular layers, the number of growth cycles being automatically controlled. A mass analyzer is disposed opposite to the substrate in the vessel so that the progress of crystal growth can be incessantly traced and evaluated for each of the molecular layers. An etchant gas introduction nozzle extends into the vessel to make etching treatment of the surface of the substrate in the evacuated vessel prior to the crystal growth.

What is claimed is:  
     
         1 . A semiconductor crystal growth apparatus comprising a crystal growth vessel for accommodating a substrate, heating means for heating said substrate, evacuating means for evacuating said crystal growth vessel to a ultrahigh vacuum, nozzle means for introducing gases containing component elements of a crystal to be grown on the substrate into said crystal growth vessel from outside, valve means provided between said nozzle means and sources of said gases, and control means for controlling the opening and closing of said valve means according to a preset open-close time chart and a preset number of cycles of valve opening and closing, whereby an epitaxial growth layer having a predetermined thickness grows automatically with precision as precise as a single molecular layer.  
     
     
         2 . A semiconductor crystal growth apparatus according to    claim 1   , wherein said nozzle means includes at least two nozzles.  
     
     
         3 . A semiconductor crystal growth apparatus according to    claim 1   , which further comprises a mechanism for irradiating said substrate with radiation directed from the outside of said crystal growth vessel.  
     
     
         4 . A semiconductor crystal growth apparatus comprising a crystal growth vessel for accommodating a substrate, heating means for heating said accommodated substrate, evacuating means for evacuating said crystal growth vessel to a ultrahigh vacuum, nozzle means for introducing gases containing component elements of a crystal to be grown on said substrate into said crystal growth vessel from outside, and a mass analyzer disposed opposite to said accommodated substrate, whereby the progress of a crystal is incessantly traced and evaluated so that an epitaxial growth layer having a desired thickness is formed with precision as precise as a single molecular layer.  
     
     
         5 . A semiconductor crystal growth apparatus according to    claim 4   , wherein the detecting section of said mass analyzer and the opening of said gas introduction nozzle means are surrounded by shroud means provided with cooling means.  
     
     
         6 . A semiconductor crystal growth apparatus comprising a crystal growth vessel for accommodating a substrate, heating means for heating said accommodated substrate, evacuating means for evacuating said crystal growth vessel to a ultrahigh vacuum, nozzle means for introducing gases containing component elements of a crystal to be grown on said substrate, and another nozzle means for introducing an etchant gas, whereby the surface of said substrate is treated by vapor phase etching prior to the epitaxial growth of a crystal.  
     
     
         7 . A semiconductor crystal growth apparatus according to    claim 6   , which further comprises a mechanism for irradiating said substrate with radiation.  
     
     
         8 . A semiconductor crystal growth apparatus according to    claim 6   , wherein a high frequency coil or electrodes are provided in the neighborhood of at least part of said etchant gas introduction nozzle means.  
     
     
         9 . A semiconductor crystal growth apparatus according to    claim 7   , wherein at least part of said etchant gas introduction nozzle means is irradiated with radiation.  
     
     
         10 . A semiconductor crystal growth apparatus according to    claim 9   , wherein at least part of said etchant gas introduction nozzle means is optically transparent.