Molecular beam epitaxial growth device and molecular beam control method therein for exactly controlling thickness and composition of epitaxial film

Claim 2

A molecular beam epitaxial growth device comprising: a vacuum chamber; at least one molecular beam source cell having a heating means, provided in said vacuum chamber, for heating and evaporating molecular beam source material in each of said molecular beam source cells; a shutter, provided in said vacuum chamber for each of said molecular beam source cells, for controlling the quantity of the molecular beam evaporated from said molecular beam source cell; a cell temperature measurement means, for measuring a temperature T i of each of said molecular beam source cells; a cell temperature control means, connected to said heating means of each of said molecular beam source cells, for controlling the temperature of each molecular beam source cell; a molecular beam intensity measurement means, for measuring an intensity V i of a molecular beam evaporated from each of said molecular beam source cells; a molecular beam intensity conversion means, receiving the molecular beam intensity V i measured by said molecular beam intensity measurement means and the cell temperature T i measured by said cell temperature measurement means, for converting the measured molecular beam intensity V i into a value V io at a reference temperature T 0 by calculating the following equatio, using the measured molecular beam intensity V i and the measured cell temperature T i ; ##EQU20## a memory means, receiving the converted molecular beam intensity V io and a corresponding time t i of each converted molecular beam intensity V io , for successively storing the converted molecular beam intensity V io and the corresponding time t i thereof; a molecular beam intensity estimation means, for successively reading out the estimated molecular beam intensity V io and the corresponding time t i thereof, and for estimating a molecular beam intensity V 0 (t) and a time (t) after the last converted and stored time based on the reference temperature T 0 in accordance with the converted molecular beam intensity V io and the corresponding time t i thereof; and a cell temperature calculation means, for calculating a cell temperature T SP (V SP ), to realize a predetermined molecular beam intensity V SP , given by successively inputting the estimated molecular beam intensity V 0 (t) and a predetermined molecular beam intensity V SP into the following equation, and for successively inputting the calculated cell temperature T SP (V SP ) as an objective temperature into said cell temperature control means; ##EQU21##

Claim 3

A molecular beam epitaxial growth device, as claimed in claim 1, wherein said molecular beam intensity estimation means estimates the molecular beam intensity V 0 (t) corresponding to the time after the last converted and stored time, by successively reading out the estimated molecular beam intensity V io and the corresponding time t i thereof stored in said memory means, by assuming an empirical formula log (V 0 (t))=C 0 +C 1 t, by calculating coefficients C 0 and C 1 by minimizing the sum of square value Σ D i 2 in the difference D i =log (V io -(C 0 +C 1 t i )), and by carrying out the equation V 0 (t)=exp (C 0 +C 1 t).

Claim 4

A molecular beam epitaxial growth device, as claimed in claim 1, wherein said molecular beam intensity estimation means estimates the molecular beam intensity V 0 (t) corresponding to the time after the last converted and stored time, by successively reading out the estimated molecular beam intensity V io and the corresponding time t i thereof stored in said memory means, by assuming an empirical formula V 0 (t)=C 0 '+C 1 't, by calculating coefficients C 0 ' and C 1 ' by minimizing the sum of square value Σ D i ' 2 in the difference D i '=V io -(C 0 '+C 1 't i ), and by carrying out the equation V 0 (t)=C 0 '+C 1 't.

Claim 5

A molecular beam epitaxial growth device comprising: a vacuum chamber; at least one molecular beam source cell having a heating means, provided in said vacuum chamber, for heating and evaporating molecular beam source material in each of said molecular beam source cells; a shutter, provided in said vacuum chamber for each of said molecular beam source cells, for controlling the quantity of the molecular beam evaporated from said molecular beam source cells; a cell temperature measurement means, for measuring a temperature T i of each of said molecular beam source cells; a cell temperature control means, connected to said heating means of each of said molecular beam source cells, for controlling the temperature of each molecular beam source cell; a molecular beam intensity measurement means, for measuring an intensity V i of a molecular beam evaporated from each of said molecular beam source cells; a molecular beam intensity conversion means, receiving the molecular beam intensity V i measured by said molecular beam intensity measurement means and the cell temperature T i measured by said cell temperature measurement means, for converting the measured molecular beam intensity V i into a value V io at a reference temperature T 0 by calculating the following equation using the measured molecular beam intensity V i and the measured cell temperature T i ; ##EQU22## a memory means, receiving the converted molecular beam intensity V io and a corresponding time t i of each converted molecular beam intensity V io , for successively storing the converted molecular beam intensity V io and the corresponding time t i thereof; a molecular beam intensity estimation means, for successively reading out the estimated molecular beam intensity V io and the corresponding time t i thereof, and for estimating a molecular beam intensity V 0 (t) at a time (t) after the last converted and stored time based on the reference temperature T 0 in accordance with the converted molecular beam intensity V io and the corresponding time t i thereof; a molecular beam intensity calculation means, for calculating a molecular beam intensity V SP (T SP ) at a cell temperature T SP in the time (t) of the estimated molecular beam intensity V 0 (t) by successively inputting the estimated molecular beam intensity V 0 (t) and the cell temperature T SP into the following equation; ##EQU23## and a shutter control means, connected to said shutter of each of said molecular beam source cell and received the calculated molecular beam intensity V SP (T SP ), for controlling said shutter in accordance with an integrated value relating to the time factor of the molecular beam intensity V SP (T SP ).

Claim 6

A molecular beam epitaxial growth device comprising: a vacuum chamber; at least one molecular beam source cell having a heating means, provided in said vacuum chamber, for heating and evaporating molecular beam source material in each of said molecular beam source cells; a shutter, provided in said vacuum chamber for each of said molecular beam source cells, for controlling the quantity of the molecular beam evaporated from said molecular beam source cells; a cell temperature measurement means, for measuring a temperature T i of each of said molecular beam source cells; a cell temperature control means, connected to said heating means of each of said molecular beam source cells, for controlling the temperature of each molecular beam source cell; a molecular beam intensity measurement means, for measuring an intensity V i of a molecular beam evaporated from each of said molecular beam source cells; a molecular beam intensity conversion means, receiving the molecular beam intensity V i measured by said molecular beam intensity measurement means and the cell temperature T i measured by said cell temperature measurement means, for converting the measured molecular beam intensity V i into a value V io at a reference temperature T 0 by calculating the following equation using the measured molecular beam intensity V i and the measured cell temperature T i ; ##EQU22## a memory means, receiving the converted molecular beam intensity V io and a corresponding time t i of each converted molecular beam intensity V io , for successively storing the converted molecular beam intensity V io and the corresponding time t i thereof; a molecular beam intensity estimation means, for successively reading out the estimated molecular beam intensity V io and the corresponding time t i thereof, and for estimating a molecular beam intensity V 0 (t) at a time (t) after the last converted and stored time based on the reference temperature T 0 in accordance with the converted molecular beam intensity V io and the corresponding time t i thereof; a molecular beam intensity calculation means, for calculating a molecular beam intensity V SP (T SP ) at a cell temperature T SP in the time (t) of the estimated molecular beam intensity V 0 (t) by successively inputting the estimated molecular beam intensity V 0 (t) and the cell temperature T SP into the following equation; ##EQU23## and a shutter control means, connected to said shutter of each of said molecular beam source cell and received the calculated molecular beam intensity V SP (T SP ), for controlling said shutter in accordance with an integrated value relating to the time factor of the molecular beam intensity V SP (T SP ).

Claim 7

A molecular beam epitaxial growth device, as claimed in claim 4, wherein said molecular beam intensity estimation means estimates the molecular beam intensity V 0 (t) corresponding to the time after the last converted and stored time, by successively reading out the estimated molecular beam intensity V io and the corresponding time t i thereof stored in said memory means, by assuming an empirical formula log (V 0 (t))=C 0 +C 1 t, by calculating coefficients C 0 and C 1 by minimizing the sum of square value Σ D i 2 in the difference D i =log (V io -(C 0 +C 1 t i )), and by carrying out the equation V 0 (t)=exp (C 0 +C 1 t).

Claim 8

A molecular beam epitaxial growth device, as claimed in claim 4, wherein said molecular beam intensity estimation means estimates the molecular beam intensity V 0 (t) corresponding to the time after the last converted and stored time, by successively reading out the estimated molecular beam intensity V io and the corresponding time t i thereof stored in said memory means, by assuming an empirical formula V 0 (t)=C 0 '+C 1 't, by calculating coefficients C 0 ' and C 1 ' by minimizing the sum of square value Σ D i ' 2 in the difference D i '=V io -(C 0 '+C 1 't i ), and by carrying out the equation V 0 (t)=C 0 '+C 1 't.