Semiconductor crystal growth method

Claim 1

A method of growing a semiconductor crystal on a substrate through epitaxial growth of molecular layers, comprising the steps of: heating a substrate within a crystal growth vessel enclosing said substrate; introducing gases containing component elements of a crystal to be grown on said substrate in said vessel from outside sources via nozzles; permitting and stopping the introducing of the gases on said substrate by operating valve means in open and closed positions, said valve means being arranged between said nozzles and said sources; selectively cycling the opening and the closing of said valve means in accordance with a program having data indicative of a number of cycles of opening and closing of the valve means, a time period for introduction of each of the gases, and a time period for exhaustion of each of the gases between introductions of each of the gases, said data being selected based on attaining a desired thickness of the growth layer to be obtained as precise as a single molecular layer; exhausting residuals of the gases by evacuating an interior of said vessel with an ultrahigh vacuum of 10 -7 to 10 -8 Pa even while said control means is selectively cycling the opening and closing of the valve means; tracing and evaluating progress of the semiconductor crystal growth within the vessel, said step of tracing and evaluating including extending a mass analyzer into said vessel for capturing molecules liberated from said substrate; absorbing an excess of the gas being introduced, the step of absorbing including employing a first shroud within said vessel, said first shroud having opening aligned with respective openings of said nozzles, employing a second shroud having a detection opening which is aligned with an end of said mass analyzer, arranging said first and second shrouds for absorbing the excess of the gas to allow said mass analyzer to capture only molecules liberated from said substrate; and cooling both of said first and second shrouds.

Claim 2

A method of growing a semiconductor crystal on a substrate through epitaxial growth of molecular layers, comprising the steps of: heating a substrate within a crystal growth vessel enclosing said substrate; introducing gases containing component elements of a crystal to be grown on said substrate in said vessel from outside sources via nozzles; permitting and stopping the introducing of the gases on said substrate by operating valve means in open and closed positions, said valve means being arranged between said nozzles and said sources; selectively cycling the opening and the closing of said valve means in accordance with a program having data indicative of a number of cycles of opening and closing of the valve means, a time period for introduction of each of the gases, and a time period for exhaustion of each of the gases between introductions of each of the gases, said data being selected based on attaining a desired thickness of the growth layer to be obtained as precise as a single molecular layer; exhausting residuals of the gases by evacuating an interior of said vessel with an ultrahigh vacuum of 10 -7 to 10 -8 Pa even while said control means is selectively cycling the opening and closing of the valve means; tracing and evaluating progress of the semiconductor crystal growth within the vessel, said step of tracing and evaluating including extending a mass analyzer into said vessel for capturing molecules liberated from said substrate; absorbing an excess of the gas being introduced, the step of absorbing including employing a first shroud within said vessel, said first shroud having opening aligned with respective openings of said nozzles, employing a second shroud having a detection opening which is aligned with an end of said mass analyzer, arranging said first and second shrouds for absorbing the excess of the gas to allow said mass analyzer to capture only molecules liberated from said substrate; and cooling both of said first and second shrouds.