CVD reactor having means for locally influencing the susceptor temperature
In the thermal treatment of substrates, a susceptor is used to hold at least one substrate. The susceptor can be heated with a heater and driven in rotation about a rotation axis by a rotary drive. Means are provided to influence the heat transfer to or from the susceptor in a locally limited manner, synchronized with the rotary movement of the susceptor, to equalize local temperature differences on the rotating susceptor. In particular, a temperature control gas with changing heat conduction properties is periodically fed in a pulsed manner through a feed opening into a gap between the susceptor and a cooling unit.
1 . A device for a thermal treatment of substrates, the device comprising:
a housing ( 1 );
a radio frequency (RF) heater ( 13 ) being located in the housing ( 1 );
a rotary drive ( 20 );
a susceptor ( 5 ) that is heated by the RF heater ( 13 ), and is rotated about a first axis of rotation (A) by the rotary drive ( 20 ) with respect to the housing ( 1 );
a rotary encoder configured to determine an angular position of the susceptor ( 5 );
a control unit configured to receive the angular position from the rotary encoder;
at least one substrate holder ( 7 ) disposed on the susceptor ( 5 ), the at least one substrate holder ( 7 ) for holding at least one substrate; and
means ( 14 , 14 ′) for influencing a temperature of a first region of the susceptor ( 5 ), wherein the control unit is configured to control the means ( 14 , 14 ′) to influence a heat transfer from the susceptor ( 5 ) to a cooling unit ( 30 ) by altering, in a pulsed manner synchronized with a rotation of the susceptor ( 5 ), a thermal conductivity of a medium arranged between the susceptor ( 5 ) and the cooling unit ( 30 ) in a thermal influence zone ( 17 ), and wherein the thermal influence zone ( 17 ) is locally fixed in location with respect to the housing ( 1 ).
2 . A device for a thermal treatment of substrates, the device comprising:
a housing ( 1 );
a heater ( 13 ) being located in the housing ( 1 );
a rotary drive ( 20 );
a susceptor ( 5 ) that is heated by the heater ( 13 ) and is rotated about a first axis of rotation (A) by the rotary drive ( 20 ) with respect to the housing ( 1 );
a cooling unit ( 30 ) arranged below the susceptor ( 5 );
a rotary encoder configured to determine an angular position of the susceptor ( 5 );
a control unit configured to receive the angular position from the rotary encoder;
at least one substrate holder ( 7 ), arranged eccentrically with respect to the first axis of rotation (A) on the susceptor ( 5 ), and which is rotated about a second axis of rotation (B) offset from the first axis of rotation (A), the at least one substrate holder ( 7 ) for holding at least one substrate; and
means ( 14 , 14 ′) being controlled by the control unit for influencing a heat transfer from the susceptor ( 5 ) to the cooling unit ( 30 ) by altering a thermal conductivity of a medium in a first thermal influence zone ( 17 ) disposed radially inwards from, or outwards from, or on, an orbital path of the second axis of rotation (B) about the first axis of rotation (A), wherein the medium is arranged between the susceptor ( 5 ) and the cooling unit ( 30 ), and wherein the first thermal influence zone ( 17 ) is locally fixed in location with respect to the housing ( 1 ).
3 . The device of claim 1 , wherein the RF heater ( 13 ) comprises an RF induction coil ( 13 ), wherein the cooling unit ( 30 ) is formed by a cooling channel of the RF induction coil ( 13 ), and wherein an electromagnetic alternating field is generated with the RF induction coil ( 13 ), which field induces eddy currents in the susceptor ( 5 ), made of an electrically conductive material, for purposes of heating the susceptor ( 5 ).
4 . The device of claim 2 , wherein the first thermal influence zone ( 17 ) is part of a plurality of thermal influence zones ( 17 ), in which heat is periodically supplied or removed in the pulsed manner synchronized with the rotation of the susceptor ( 5 ), and wherein the plurality of thermal influence zones ( 17 ) are arranged at azimuthal angles that differ from one another, with respect to a center of the susceptor ( 5 ), and/or are arranged at different radial distances, with respect to the center of the susceptor ( 5 ).
5 . The device of claim 2 , wherein the first thermal influence zone ( 17 ), in which heat is periodically supplied or removed in the pulsed manner synchronized with the rotation of the susceptor ( 5 ), is arranged in a peripheral region of the susceptor ( 5 ), in which a plurality of substrate holders ( 7 ) are located.
6 . The device of claim 2 , wherein the first thermal influence zone ( 17 ) is limited to an angular range about the first axis of rotation (A) of a maximum of 90 degrees.
7 . The device of claim 2 , further comprising temperature measurement points ( 31 , 31 ′) arranged radially outwards from, and/or radially inwards from, the first thermal influence zone ( 17 ), for purposes of measuring a temperature of a surface of the susceptor ( 5 ).
8 . The device of claim 2 , wherein the heater ( 13 ) comprises a radio frequency (RF) induction coil ( 13 ), wherein the cooling unit ( 30 ) is formed by a cooling channel of the RF induction coil ( 13 ), and wherein an electromagnetic alternating field is generated with the RF induction coil ( 13 ), which field induces eddy currents in the susceptor ( 5 ), made of an electrically conductive material, for purposes of heating the susceptor ( 5 ).
9 . The device of claim 1 , further comprising:
a sealing plate ( 8 ) disposed between the RF heater ( 13 ) and the susceptor ( 5 ); and
a gap ( 10 ) between the sealing plate ( 8 ) and the susceptor ( 5 ),
wherein the medium is a gas that is flowed into the gap ( 10 ).
10 . The device of claim 2 , further comprising:
a sealing plate ( 8 ) disposed between the heater ( 13 ) and the susceptor ( 5 ); and
a gap ( 10 ) between the sealing plate ( 8 ) and the susceptor ( 5 ),
wherein the medium is a gas that is flowed into the gap ( 10 ).
11 . The device of claim 9 , further comprising:
a sealing plate ( 8 ) disposed between the susceptor ( 5 ) and the cooling unit ( 30 ),
wherein the sealing plate ( 8 ) extends over a portion of a radial length of the susceptor ( 5 ),
wherein a diffusion barrier is located within the gap ( 10 ), the diffusion barrier extending from radially inwards over an entire length of the gap ( 10 ) to a gas outlet unit ( 9 ), and
wherein the diffusion barrier is formed by a first gas flow (S 1 ) with a first thermal conductivity which flows from radially inwards over the entire length of the gap ( 10 ) to the gas outlet unit ( 9 ).
12 . The device of claim 11 ,
wherein a radially outer edge of the sealing plate ( 8 ) is supported on a step ( 19 ) of the gas outlet unit ( 9 ) so that the gas flowing through the gap ( 10 ) is prevented from entering a region of the housing ( 1 ) below the sealing plate ( 8 ), and
wherein in at least one peripheral position, radially inwards from a peripheral zone in which the at least one substrate holder ( 7 ) is located, the sealing plate ( 8 ) has at least one feed opening ( 14 ′) into which a gas line ( 14 ) opens, with which a second gas flow (S 2 ) having a second thermal conductivity, which is different from the first conductivity, is fed into the gap ( 10 ).
13 . The device of claim 12 , wherein the control unit is configured to control the first gas flow (S 1 ) and the second gas flow (S 2 ) in such a way that the thermal conductivity of the medium in a portion of the thermal influence zone ( 17 ) extending within the gap ( 10 ), between the at least one feed opening ( 14 ′) and the gas outlet unit ( 9 ), changes in the pulsed manner synchronized with the rotation of the susceptor ( 5 ).