Method for ascertaining the end of a cleaning process for a process chamber of a MOCVD reactor
In a cleaning process for removing parasitic depositions on surfaces of a process chamber of a CVD reactor, a susceptor of the CVD reactor is heated by a heating device, and the susceptor is regulated to a specified temperature or is heated with a constant heat output. Concurrently, an etching gas is supplied to the heated process chamber. The thermal response of at least one object is monitored, in which the thermal response is the temperature of the wide face of a process chamber cover, the wide face facing away from the process chamber. The parasitic depositions influence the emissivity of the surface of the process chamber cover, the emissivity influencing the temperature distribution in the process chamber. The supply of etching gas is terminated when the temperature reaches a comparison value, the temperature changing in response to changes in the surface emissivity during the cleaning process.
1 . A method for removing parasitic depositions from surfaces of a process chamber ( 6 ) of a chemical vapor deposition (CVD) reactor, the method comprising:
performing a coating process;
performing an etching process that includes supplying an etching gas into the process chamber ( 6 ) while heating a susceptor ( 2 ) by a heating device ( 5 );
monitoring during the etching process a thermal response of a first component ( 2 , 3 , 7 , 8 , 11 ) with a first and second surface, the first component ( 2 , 3 , 7 , 8 , 11 ) located in, or adjacent to the process chamber ( 6 ) so as to obtain measured values (Tt), wherein the thermal response comprises a first temperature or an emissivity of the first surface of the first component ( 2 , 3 , 7 , 8 , 11 ), and wherein the first surface of the first component ( 2 , 3 , 7 , 8 , 11 ) remains free of parasitic depositions during the coating process;
when at least one of the measured values (Tt) equals a comparison value (Tv) or falls within a window set about the comparison value (Tv), terminating a supply of the etching gas into the process chamber ( 6 ); and
while the etching gas is being supplied, regulating a temperature control body to a specified temperature (T), or heating the temperature control body with a constant heat output, wherein the first component ( 2 , 3 , 7 , 8 , 11 ) is arranged in a heat transport path between the heating device ( 5 ) and a cooling device ( 11 ), and a parasitic coating on the second surface of the first component ( 2 , 3 , 7 , 8 , 11 ), which is exposed to the etching gas, influences an emissivity of the second surface of the first component ( 2 , 3 , 7 , 8 , 11 ), a change of which changes a heat flux between the heating device ( 5 ) and the cooling device ( 11 ).
2 . The method of claim 1 , further comprising before supplying the etching gas into the process chamber ( 6 ) so as to remove the parasitic depositions, (i) simultaneously depositing one or more crystalline layers on one or more substrates ( 16 ), arranged on one or more storage locations ( 25 ) on the susceptor ( 2 ) bounding the process chamber ( 6 ) on one side, by supplying at least one organometallic compound of an element of the II-, III- or IV-main group, and at least one hydride of an element of the IV-, V- or VI-main group, together with a carrier gas, during which the parasitic depositions to be removed are formed, and (ii) removing the one or more substrates ( 16 ) from the process chamber ( 6 ), wherein the etching gas comprises an element of the VII-main group.
3 . The method of claim 2 , wherein the comparison value (Tv) is a temperature value of a surface of the storage locations ( 25 ) of the one or more substrates ( 16 ), and the measured values (Tt) are temperature values of a surface ( 3 ) of the susceptor ( 6 ) external to the storage locations ( 25 ).
4 . The method of claim 1 , wherein the first component ( 2 , 3 , 7 , 8 ) forms a portion of the process chamber ( 6 ).
5 . The method of claim 1 , wherein the thermal response is measured with an optical measuring device ( 19 ).
6 . The method of claim 1 , wherein the first surface of the first component ( 2 , 3 , 7 , 8 ) is a first wide face ( 8 ) of a process chamber cover ( 7 ) bounding the process chamber ( 6 ), and facing away from the process chamber ( 6 ), and the second surface of the first component ( 2 , 3 , 7 , 8 , 11 ) is a second wide face ( 9 ) of the process chamber cover ( 7 ) facing the process chamber ( 6 ).
7 . The method of claim 1 , wherein at least one of:
the comparison value (Tv) is a second temperature (T) measured on the first component ( 7 ) free of the parasitic depositions in preliminary tests; or
the window is a temperature range about the second temperature (T) measured on the first component ( 7 ) free of the parasitic depositions in the preliminary tests.
8 . The method of claim 1 , wherein the monitored first component is a heating device ( 5 ), and the thermal response is the heat output of the heating device ( 5 ).
9 . The method of claim 1 , wherein the monitored first component is a cooling device ( 11 ), and the thermal response is the cooling performance of the cooling device ( 11 ).
10 . The method of claim 1 , wherein at least one of:
the comparison value (Tv) is a specified value;
the comparison value (Tv) is obtained simultaneously with the measured values (Tt); or
the comparison value (Tv) is continuously adjusted by means of a machine learning algorithm.
11 . The method of claim 1 , wherein the measured values (Tt) are a composition, or a mass flow rate, of a temperature control gas ( 24 ) that is in an intermediate space ( 10 ) between the cooling device ( 11 ) and a process chamber cover ( 7 ).
12 . The method of claim 1 , wherein at least one of:
the etching step is repeatedly executed in succession;
after at least one of the measured values (Tt) equal the comparison value (Tv), or lie in the window, a final etching step (E+) is executed for a specified time; or
the etching step comprises a first cleaning phase (A), in which the etching gas is supplied into the process chamber ( 6 ), which is followed by a first purging phase (B), which is followed by a second cleaning phase (C), in which a cleaning gas is supplied into the process chamber ( 6 ), which is followed by a second purging phase (D).
13 . The method of claim 1 , wherein the comparison value (Tv) is determined during the supply of the etching gas by monitoring a thermal response of a second component ( 2 , 3 , 7 , 8 , 11 ).
14 . The method of claim 13 , wherein the comparison value (Tv) is a difference between a specified constant value and the thermal response of the second component ( 2 , 3 , 7 , 8 , 11 ).
15 . The method of claim 1 , wherein the thermal response further comprises a heat output of the heating device ( 5 ) or a cooling performance of the cooling device ( 11 ).
16 . The method of claim 1 , wherein the supply of the etching gas into the process chamber ( 6 ) is further terminated when an absolute value of a time derivative of a profile of the measured values (Tt) is less than a specified value (Z).
17 . A device, comprising:
a chemical vapor deposition (CVD) reactor with a process chamber ( 6 ) arranged in a housing ( 1 ) of the CVD reactor;
a susceptor ( 2 ) disposed in the process chamber, the susceptor ( 2 ) having a plurality of storage locations ( 25 ), each for storing a substrate ( 16 );
a heating device ( 5 ) for heating the susceptor ( 2 );
a cooling device ( 11 );
a gas inlet unit ( 13 ) for supplying during an etching step an etching gas into the process chamber ( 6 ), and for supplying during a coating step at least one organometallic compound of an element of II-, III- or IV-main group, and at least one hydride of an element of IV-, V- or VI-main group, together with a carrier gas into the process chamber ( 6 );
a measuring device ( 19 ) for determining a thermal response of a component ( 2 , 3 , 7 , 8 , 11 ) with a first and second surface, the component ( 2 , 3 , 7 , 8 , 11 ) located in, or adjacent to the process chamber ( 6 ) so as to obtain measured values (Tt), wherein the thermal response comprises a temperature or an emissivity of the first surface of the component ( 2 , 3 , 7 , 8 , 11 ), wherein the first surface of the first component ( 2 , 3 , 7 , 8 , 11 ) remains free of parasitic depositions during a coating process, and wherein the component ( 2 , 3 , 7 , 8 , 11 ) is arranged in a heat transport path between the heating device ( 5 ) and a cooling device ( 11 ), an emissivity of the second surface ( 3 , 9 ) of the component ( 2 , 3 , 7 , 8 , 11 ) is influenced by a parasitic coating on the second surface ( 3 , 9 ) of the component ( 2 , 3 , 7 , 8 , 11 ), which is exposed to the etching gas, and a change in the emissivity of the second surface ( 3 , 9 ) changes a heat flux between the heating device ( 5 ) and the cooling device ( 11 ); and
a control device ( 23 ) for controlling the supply of the etching gas through the process chamber ( 6 ), wherein the control device ( 23 ) is configured to terminate the supply the etching gas into the process chamber ( 6 ) when at least one of the measured values (Tt) obtained from the thermal response equals a comparison value (Tv) or falls within a window set about the comparison value (Tv).
18 . The device of claim 17 , wherein the component ( 2 , 3 , 7 , 8 ) forms a portion of the process chamber ( 6 ).
19 . The device of claim 18 , wherein the first surface of the component ( 2 , 3 , 7 , 8 ) is a first wide face ( 8 ) of a process chamber cover ( 7 ) bounding the process chamber ( 6 ), and facing away from the process chamber ( 6 ), and the second surface of the first component ( 2 , 3 , 7 , 8 , 11 ) is a second wide face ( 9 ) of the process chamber cover ( 7 ) facing the process chamber ( 6 ).
20 . The device of claim 19 , further comprising means for supplying a temperature control gas ( 24 ) into an intermediate space ( 10 ) between the cooling device ( 11 ) and the process chamber cover ( 7 ), wherein the measuring device ( 19 ) is configured to determine a composition or a mass flow rate of the temperature control gas ( 24 ).