Device and method for treating a substrate

Abstract

The invention relates to a device for thermally treating a substrate (3) with a heating apparatus (4) arranged in a reactor housing (1) to heat the substrate (3), wherein during heating of the device, a flow of heat (8) flows from a heating apparatus (4) to a substrate (3) and during cooling a flow of heat (7) flows from the substrate (3) to a cold region (2). To minimise the heating and cooling time, a shielding apparatus (5) for influencing the flow of heat (7) is proposed that can be adjusted between a first and a second operating position, wherein the shielding apparatus (5) has several shielding elements (6, 6') that can be moved relative to one another.

Description

Description Device and method for treating a substrate field of technology

[0001] The invention relates to a device for the thermal treatment of a substrate with a heating device arranged in a reactor housing for heating the substrate, wherein a cold region is arranged in the reactor housing such that a heat flow flows from the heated substrate along a heat transfer path to the cold region, and with a shielding device arranged in the heat transfer path, which is adjustable between a first and a second operating position, wherein the shielding device exerts a greater shielding effect on the heat flow in the first operating position than in the second operating position.

[0002] The invention further relates to a method for treating a substrate in such a device. State of the art

[0003] Such a device is used in particular for the deposition of SiC. In a method according to the invention, substrates to be coated with a SiC layer are introduced, for example, through a loading and unloading opening of a reactor housing into the reactor housing, where a process chamber is located which has a susceptor onto which at least one substrate is placed. This can take place at a moderately elevated temperature, but also at temperatures up to 1000°C. The loading and unloading opening is closed. The process chamber is heated to a process temperature using a heating device. At this process temperature, after any preparatory process steps, one or more layers are deposited onto the Substrate is deposited. The process chamber, and in particular the susceptor on which the substrate lies, or the substrate itself if it is held freely in the process chamber, is then cooled to a moderately elevated temperature before being removed from the process chamber through the loading and unloading opening. The process can then be repeated with another substrate. In order to minimize the cycle time, which includes not only the process steps but also the heating and cooling steps, US Pat. No. 8,430,965 B2 proposes a shielding device having a highly reflective surface that, during heating, is placed in a heat transfer path via which heat is transferred from the substrate to a cold area of ​​the reactor housing. This reduces the heat flow from the substrate. As the substrate cools, the shielding device is removed from the heat transfer path, thus increasing the heat flow from the substrate.

[0004] Shielding devices which are used for other purposes in CVD reactors or the like are known in particular from DE 102010 000447 A1 or DE 102017103 055 A1, which discloses a shielding plate consisting of several partial plates.

[0005] DE 10 2009049954 A1 describes a device for tempering substrates with a shielding device which has a plurality of adjustable shielding elements. Summary of the invention

[0006] The invention is based on the object of providing a shielding device which can be moved from a first to a second operating position using simple means and which is arranged in a space-saving manner.

[0007] The problem is solved by the invention specified in the claims. The subclaims represent not only advantageous developments of the invention specified in the subordinate claims, but also independent solutions to the problem.

[0008] The shielding device according to the invention has a plurality of shielding elements that can be moved relative to one another. It can be advantageous if these shielding elements remain within a heat transfer chamber through which the heat flow flows during the displacement of the shielding device between the first and second operating positions. The shielding elements can have different surface sections that can be selectively aligned with the direction of the heat flow. However, it is also possible for the shielding device to consist of just one shielding element that is rotated when adjusted between the two operating positions. It can have a large-area surface section that exerts a strong shielding effect on the heat flow in the first operating position. It can have a small-area surface section that exerts a small shielding effect on the heat flow in the second operating position.For example, it can be provided that one or more shielding elements are flat, in particular rectangular strips, which have a broad side surface and a narrow side surface. The shielding elements can be rotated about an axis of rotation such that in the first operating position they oppose the heat flow with their broad side surface and in the second operating position their narrow side surface. The axis of rotation of the one or more shielding elements can have a directional component which runs perpendicular to the direction of the heat flow. Preferably, however, the axis of rotation itself runs perpendicular to the direction of the heat flow or at least substantially perpendicular to it. Between the two operating positions, the shielding elements can pivot by 90 degrees, for example. The shielding elements. can also be pivoted through other, for example smaller or larger angles, whereby this angle can also be in a range between 45 and 90 degrees. According to a variant of the invention, it can be provided that at least two screen elements can be moved against one another so that in the first operating position they lie essentially next to one another and in the second operating position they overlap at least partially or completely. The screen elements can each be assigned to a screen element carrier. The screen element carrier can have a rectangular floor plan or a circular floor plan. A screen element carrier which has a rectangular floor plan can have a plurality of narrow rectangular screen elements arranged parallel to one another and extending in one plane, between which a free space extends which has approximately the same surface area as the screen elements.By relatively shifting the shield element supports, which are arranged in different but parallel planes, the shield elements can be brought into an overlapping position in which heat flow can pass through the free spaces. In the overlapping position, the shield elements lie one above the other, overlapping one another. The shielding effect then depends on the degree of overlap. In the first operating position, the shield elements are offset from one another in such a way that they close off the free spaces of the other shield element support. Alternatively, the shield elements can also be circular sectors. The two then circular shield element supports can be rotated relative to one another about an axis of rotation so that either the free spaces are closed or the shield elements overlap. One of the two shield element supports can be firmly connected to the reactor casing.The other shield element carrier can be rotated about a rotation axis. The rotation axis preferably extends parallel to the direction of heat flow. One or more heating devices can be provided. A process chamber. can be arranged between two heating devices, so that the process chamber is heated, for example, from below or from above. A process chamber can also be arranged within a heating device, as is shown, for example, by the above-mentioned prior art, in which a coil extends around the process chamber, generating a high-frequency electromagnetic alternating field. Bodies made of electrically conductive material can be present within the process chamber. For example, the walls of the process chamber can be made of graphite. However, it is also possible for the process chamber to have a graphite susceptor. Eddy currents are generated in these electrically conductive bodies, which heat the bodies.

[0009] The eddy currents are generated inductively by alternating electromagnetic fields. The alternating electromagnetic fields are generated by a heating element. However, the heating element can also form a cold zone, for example, if it is formed by a cooled coil.

[0010] However, it is also possible to heat the walls of the process chamber or the susceptor by thermal radiation. Furthermore, a coil, which may be a helical coil or a spiral coil, may have a cavity through which a coolant flows to cool the coil. The coil then not only has the function of providing an energy flow with which a susceptor or a substrate is heated, but also forms a heat sink. In such an arrangement, the shielding device can be arranged between the coil and the susceptor or the substrate. If the coil is arranged above a process chamber ceiling, the shielding device can be arranged between a ceiling plate and the heating device, for example the coil. In such a configuration, it is advantageous if the shielding device is designed to protect against alternating electromagnetic fields in the range of 10 kHz. The arrangement of the heating device can be selected such that the energy flow it generates to the substrate or to the susceptor flows through the same space through which the heat that the substrate or the susceptor releases to the cold area, for example to an actively cooled zone of the reactor housing, also flows. The shielding elements preferably have at least one surface that has a high reflectance or a low absorbance. The reflectance for thermal radiation should preferably be greater than 0.6. However, it can also be greater than 0.7 or 0.8. The absorbance for thermal radiation should preferably be less than 0.4. However, it can also be less than 0.3 or less than 0.2. The surface is, in particular, highly reflective. The reflectance of the shielding element is, in particular, greater than the reflectance of the cold area. The shielding elements should be opaque to thermal radiation.It is advantageous if the shielding elements are also adjustable independently of one another. However, it is also provided that the shielding elements are coupled to one another or that at least some of the shielding elements are coupled to one another so that they can be moved by a common drive. The device can be designed as a CVD reactor. The CVD reactor can be a horizontal reactor with a cylindrical coil. This can be an IR heater as already described above. The substrate or a susceptor holding the substrate can also be resistance heated. The coil can be arranged inside the reactor housing but outside a process chamber housing. The shielding elements can be in the form of flat diaphragms that are driven for rotation about their longitudinal axes or that can be moved parallel to their longitudinal axes.It is considered advantageous if the shielding elements remain within a heat transfer chamber during all phases of device operation, through which heat is transferred from the substrate or susceptor to the cold region. Such a heat transfer chamber. is defined, in particular, on one side by the heated surface of the susceptor, which must be cooled for changing the substrate, and, on the other side, by a cooled surface, in particular opposite the substrate or the susceptor. The two surfaces can be of equal size, so that the heat transfer chamber is a cylinder, which can have either a circular cross-sectional area or a polygonal cross-sectional area. However, the heat transfer chamber can also have the shape of a truncated cone or a truncated pyramid. In a preferred embodiment, it can be provided that the shielding device forms a heat shield arrangement having an active area that is at least twice as large during the heating of the substrate or the susceptor as an active area during the cooling of the substrate or the susceptor. The device can be a warm-wall reactor, a planetary reactor, or a showerhead reactor.

[0011] According to the method according to the invention, a previously described device is first heated from a first moderate temperature, which can be between 50°C and 200°C, for example, at which the device has been loaded with a substrate, to an elevated temperature, which can be over 1000°C. During this heating phase, the shielding elements are operated in the first operating position so that they provide maximum shielding effect against the heat flow from the substrate to the cold area. Thermal radiation emitted by the substrate is reflected by the particularly highly reflective surface of the shielding elements. During the process phase, which can also take place at temperatures above 1000°C, the shielding elements are held in the first operating position. However, it can also be provided that the shielding elements are moved to an intermediate position during the process phase so that the heat flow from the substrate is increased.This allows you to adjust the umbrella elements. the substrate temperature varies. It can also be provided that during the process phase only some of the shielding elements are adjusted locally so that the heat flow from the substrate can be increased zone by zone and thus the substrate temperature or the susceptor temperature can be influenced zone by zone. For this purpose, several sets of shielding elements can be provided which can be moved back and forth between the operating positions, whereby the shielding elements of different sets can assume different operating positions. The sets of the different shielding elements can be arranged one behind the other in the flow direction of a process gas through the process chamber. However, they can also be arranged next to one another in the flow direction. Furthermore, it can be provided that the different sets of shielding elements are arranged around a common center.In such an arrangement there can be a central zone in which shielding elements are arranged whose operating position can be changed independently of one or more radially outer zones. After the end of the process phase the shielding elements are moved to the second operating position in which they exert their minimum shielding effect so that the heat flow from the substrate to the cold area is maximum. This makes it possible to reduce cycle times. The installation space can also be reduced because the shielding elements do not leave the heat transfer chamber when adjusted but are located between the cold area and the hot area to be cooled in both operating positions. A regulating device or a control device can be provided with which the operating positions of the shielding elements can be changed. The control device can interact with a sensor, in particular a temperature sensor, e.g. with a pyrometer.However, it is also envisaged that a control device interacts with one or more sensors to regulate the surface temperature of a susceptor or the substrate to a constant value. Temperature control. is achieved by adjusting the shielding elements of one or more zones or sets of shielding elements. If the sensor is a pyrometer, an opening is provided, particularly in the housing cover, which can be purged with an inert gas and / or is closed with a window. An optical path to the susceptor or substrate leads through this opening. The optical path can pass through a shielding element. The shielding element can have an opening there through which the optical path passes. The opening can be a slit. Short description of the drawings

[0012] The invention is explained in more detail below using exemplary embodiments. They show: Fig. 1 schematically shows a first embodiment of the invention in the form of a vertical section through a reactor housing of a CVD reactor, wherein shielding elements 6 pivotable about axes 9 assume their first operating position in which they exert a maximum shielding effect on a heat flow 7 from a susceptor 13 to a cooling device 2, Fig. 2 shows the section approximately along the line II-II in Figure 1, Fig. 3 is a representation according to Figure 1, wherein the shielding elements 6 assume their second operating position in which they exert a minimal shielding effect on the heat flow 7, Fig. 4 is a view according to Figure 1, wherein the screen elements 6 assume an intermediate position, Fig. 5 shows a second embodiment in a representation according to Figure 1, wherein screen elements 6' which are displaceable in a horizontal plane are arranged in the area between gaps between screen elements 6 and thus exert a maximum screen effect, Fig. 6 shows the second embodiment in a representation according to Figure 3, wherein the shielding elements 6' are brought into a complete overlapping position with the shielding elements 6 and thus exert a minimal shielding effect, Fig. 7 shows the second embodiment in a representation according to Figure 4, wherein the screen elements 6' are in an intermediate position, Fig. 8 shows the section approximately along the line VIII-VIII in Figure 7, Fig. 9 shows a third embodiment of the invention in a plan view, wherein the shielding elements 6, 6' are formed by sector-shaped sections of a circular disk-shaped shielding element carrier 23, Fig. 9a shows a variant of the third embodiment, in which the shielding elements 6, 6' are arranged over two zones extending concentrically to a center 9 and the Screen elements 6, 6' of the different zones can be individually adjusted, Fig. 10 shows the section along the line XX in Figure 9, wherein the movable screen elements 6' are arranged in the area of ​​gaps between fixed screen elements 6, fill them and thus exert a maximum screen effect, Fig. 11 is a representation according to Figure 10, wherein the shielding elements 6' are brought into a complete overlapping position with the shielding elements 6 and thus exert a minimal shielding effect, Fig. 12 is a representation according to Figure 10, wherein the screen elements 6' assume an intermediate position, Fig. 13 shows a fourth embodiment of the invention in the form of a single horizontal reactor for depositing SiC layers on substrates 3, which are arranged in a process chamber 11 which can be heated from all four circumferential sides by a heating device 4, wherein a shielding device 5 consisting of several shielding elements 6 is arranged between a lower heating device 4 and a lower cold region 2 and between an upper heating device 4 and an upper cold region 2, Fig. 14 shows a fifth embodiment, wherein, unlike in the fourth embodiment, the shielding device 5 is arranged between an upper wall of the process chamber 11 and the upper heating device 4 and is arranged between a lower wall of the process chamber 11 and a lower heating device 4, Fig. 15 shows a sixth embodiment of the invention, wherein a susceptor 13 carries a plurality of substrates arranged around a central gas inlet element 14, the susceptor 13 can be rotated and the substrates 3 can lie on rotatable plates and a shielding device 5 is arranged between a heating device 4, which is arranged below the susceptor 13 and is arranged in a cooled area 2, Fig. 16 shows a seventh embodiment of the invention, in which the gas inlet member 14 is designed as a showerhead and the heating device 4 and the shielding device 5 are arranged as in the sixth embodiment, Fig. 17 shows an eighth embodiment in which the heating device 4 is a resistance heater or a lamp heater, with which the substrate 3 lying on a transparent susceptor 13 is heated directly by thermal radiation and a shielding device 5 is arranged between the heating device 4 and a cooled region 2, Fig. 18 shows a perspective and partially broken away view of a ninth embodiment of the invention, in which the screen elements 6 of an upper screen device 5 and a lower screen device 5 are each provided with a ceiling plate or a base plate of a reactor housing 1, wherein the shielding elements 6 are pivotable, Fig. 19 the section along the line XIX-XIX in Figure 18, Fig. 20 enlarges the section XX in Figure 19, wherein the shielding elements 6, which are coupled to one another by a coupling rod 17, assume their second operating position in which they extend parallel to the heat flow 7, Fig. 21 shows the section XX in Figure 19, but with shielding elements 6 in the first operating position, in which a highly reflective surface of an insert 22 of the shielding element 6 points away from the cold area 2, Fig. 22 shows a perspective view of four strip-shaped screen elements 6 coupled with a coupling rod 17 in the second operating position, Fig. 23 the shielding elements 6 shown in Figure 23 in the first operating position and Fig. 24 is a view similar to Figure 19, wherein a control device 29 is capable of controlling an actuator 30 for the shielding elements 6, 6' and interacts with optical sensors 27 with which the surface temperature of the susceptor 13 or the substrate 3 can be measured. Description of the embodiments

[0013] Figures 1 to 12 essentially show schematically examples of applications and embodiments of shielding devices 5 according to the invention on a CVD reactor.

[0014] In a reactor housing 1, which can be made of stainless steel and is evacuatable, a gas supply line (not shown) opens into a gas inlet element 14, which is only shown in some figures. The gas inlet element 14 feeds process gases into a process chamber 11. The process chamber 11 contains a substrate 3 which is to be coated in a thermal treatment step. For example, silicon carbide can be deposited on the substrate 3 by simultaneously feeding in silane and methane or another silicon compound or carbon compound. A susceptor 13 carrying the substrate 3 is brought to a process temperature of over 1000°C using a heating device 4, for example an IR heating device. At this process temperature, the process gases react with one another and with the substrate 3 in such a way that a silicon carbide layer is deposited on the surface of the substrate 3.Gaseous reaction products are removed through a gas outlet device (not shown). However, the device can also be used to deposit III-V layers using gases and elements from main groups III and IV.

[0015] During heating, a power designated by the reference number 8 flows from the heating device 4 to the susceptor 13 and a heat flow 7 from the susceptor 13 or from the substrate 3 resting on the susceptor 3 away from the susceptor 13 towards a cold region 2 of the reactor housing 1. The cold region 2 can be a cooled wall of the reactor housing 1. In order to influence this heat flow, several Shielding elements 6, which together form a shielding device 5. Figures 2 to 12 show various shielding devices 5. In a first operating position, as shown in Figures 1, 5, and 10, these shielding devices 5 are intended to shield the heat flow 7 flowing from the susceptor 13 toward the cold region 2 and, if possible, reflect it, so that the greatest possible heat return flow 7' is achieved from the shielding elements 6 to the substrate 3 or susceptor 13. This minimizes the heating phase and consumes less energy.

[0016] In the second operating position shown in Figures 3, 6, and 11, the shielding elements 6 are positioned within the heat transfer path in such a way that the heat return flow 7' from the shielding elements 6 to the substrate 3 or to the susceptor 13 is minimized. This shortens the cooling phase.

[0017] In an intermediate position, as shown in Figures 4, 7, 8, and 12, the shielding elements 6 exert a reduced shielding effect. While the shielding elements 6 form a highly reflective surface that is as closed as possible in the first operating position and leave as large a surface area as possible free between them in the second operating position, the reflective surface can be changed in various intermediate positions. This allows the heat flow from the substrate or susceptor to be influenced and thus, in turn, the substrate temperature or susceptor temperature. All shielding elements 6 can be coupled to one another. However, they can also be coupled to one another in zones or be individually adjustable, so that the effect on the temperature can be limited locally.

[0018] In the embodiment shown in Figures 1 to 3, the screen elements are narrow strips which are highly reflective on at least one side. are designed to be reflective. In the first operating position (see Figure 1), this highly reflective surface faces the substrate 3 or susceptor 13. In the longitudinal center of the shielding element 6 extends an axis of rotation about which the shielding element 6 can be pivoted by 90 degrees between the positions shown in Figures 1 and 3. In the position shown in Figure 3, a narrow side of the shielding element 6 points in the direction of the substrate 3 or the susceptor 13. The axis of rotation 9 here runs in a plane parallel to the plane of extension of the substrate 3 or the susceptor 13. The axes of rotation 9 of all shielding elements 6 run parallel to one another.

[0019] In the embodiments shown in Figures 5 to 8, the shielding elements 6, 6' are displaceable in a plane that extends parallel to the plane of the substrate 3 or the susceptor 13. There are two sets of shielding elements. The shielding elements 6 form a first set, which is arranged in a first horizontal plane. The shielding elements 6 are spaced apart from one another in the vertical direction by the amount of their width. In the gaps between the shielding elements 6 there are shielding elements 6' of a second set, which is arranged in a second horizontal plane that is slightly offset from the first horizontal plane. These shielding elements 6' can also be spaced apart from one another by the amount of their width. The shielding elements 6, 6' are otherwise identical.The two sets of shielding elements 6, 6' can be shifted relative to one another so that the shielding elements 6, 6' can be moved from a position adjacent to one another, in which they fill the respective gaps between the other shielding elements 6, 6', into an overlapping position in which the shielding elements 6 lie above the shielding elements 6' and the gaps between the shielding elements 6, 6' are free for the passage of heat radiation.

[0020] The embodiment shown in Figures 9 to 12 has sector-shaped screen elements 6, 6'. As in the previously described embodiment, screen elements 6 belong to a first screen element carrier 23 and screen elements 6' belong to a second screen element carrier 23'. The two screen element carriers 23, 23' are of identical design and have sector-shaped screen elements 6, 6' arranged around a center point, between which free spaces 24, 24' extend, the area of ​​which corresponds to the area of ​​the screen elements 6, 6'. By relatively rotating the two screen element carriers 23, 23' about a vertical axis 9, the free spaces 24, 24' can be closed, completely open, or partially closed in an intermediate position.

[0021] Figure 9a shows a variant of the embodiment illustrated in Figure 9. First shielding elements 6, 6' are located in an inner zone 32 extending around the axis 9. The shielding elements 6, 6' are mounted between a central ring element 34 and a central element 33 and can be displaced circumferentially around the axis 9 such that they can be moved from a juxtaposed position to an overlapped position. However, it is also possible to pivot the shielding elements 6, 6' in the radial direction relative to the axis 9.

[0022] The radially inner zone 32 is surrounded by a radially outer zone 31. In the radially outer zone 31, the shielding elements 6, 6' are located between an outer ring element 35 and the middle ring element 34. The shielding elements 6, 6' arranged in the radially outer zone 31 can be displaced independently of the shielding elements 6, 6' arranged in the inner zone 32. The shielding elements 6, 6' of the outer zone 31 can be displaced back and forth between a side-by-side position and an overlapped position. However, they can also be displaced by an amount in the plane of extension of the shielding elements. Arrangement lying, radial to the axis 9 extending swivel axes are pivoted.

[0023] A preferred embodiment is shown in Figure 13. A process chamber 11 is located within a reactor housing 1 between two cooled walls that form cold regions 2. The process chamber 11 can have a solid housing wall. A gas inlet element (not shown) opens into the process chamber 11. A gas outlet element (not shown) is also provided. Within the process chamber 11 is a susceptor 13 that supports a single substrate 3. Reference numeral 12 represents an upper and a lower wall that is transparent to alternating electromagnetic fields. The process chamber 11 can be encased. The casing formed by the walls 12 can be tubular. It can be a tube with a circular cross-section or a rectangular cross-section.

[0024] A heating device 4 can be arranged around this casing 12. The heating device 4 can be a helical coil that surrounds the walls 12. The coil of the heating device 4 can generate an alternating electromagnetic field that generates eddy currents within the susceptor 13 and thus heats the susceptor 13. However, it is also possible to manufacture the casing 12 from an electrically conductive material, so that the walls 12 are heated by eddy currents induced therein.

[0025] Alternatively, the two heating devices 4, 5 can also be designed as spiral-shaped coils extending in a plane, with which a heating effect is generated only in the area of ​​two opposite walls 12.

[0026] A shielding device 5 is provided below the heating device 4 and above the heating device 4. The shielding device 5 can have a configuration as described above.

[0027] The fifth embodiment shown in Figure 14 differs from the embodiment shown in Figure 13 essentially only in that the shielding device 5 is not arranged between the heating device 4 and the cold area, but between the process chamber 11 and the heating device 4.

[0028] The heating device can be a coil formed by a tube. A coolant can flow through the tube so that the heating device 4 can cool the cold B

[0029] While in the embodiment shown in Figure 13 the shielding elements 6 can be made of metal, in the embodiment shown in Figure 14 the shielding elements 6 must be made of a material that is transparent to high-frequency electromagnetic alternating fields.

[0030] Figure 15 shows a sixth embodiment in which a gas inlet element 14 opens into the center of a horizontal reactor in which a plurality of substrates 3 are arranged in a ring around the center on a susceptor 13, which can be rotated about a rotational axis (not shown). The substrates 13 can in turn be located on substrate carriers, which can also be rotated about rotational axes. In this embodiment, the susceptor 13 can also be heated with an IR heater 4. A process chamber ceiling 12 can here be either cooled or heated. The shielding device 5 is arranged here between a housing 1 formed cold area 2, which can be actively cooled, and the heating device 4.

[0031] Figure 16 shows an embodiment similar to Figure 15. Instead of a central gas inlet member 14, a showerhead extending over the entire surface of the susceptor 13 is provided as the gas inlet member 14, which showerhead has a gas outlet surface extending over the entire surface of the susceptor 13 with a plurality of uniformly arranged gas outlet openings.

[0032] While in the previously described embodiments, the substrate 3 rests on a heated susceptor 13 and is heated by heat conduction from the heated susceptor 13, the embodiment shown in Figure 17 features heating devices 4 that directly heat the substrate 3. The substrate 3 can, for example, rest on a carrier 13 that is transparent to thermal radiation. The heating device 4 can be a lamp heater that directly heats the substrate 3 by thermal radiation. A showerhead is shown here as the gas inlet device 14. However, other gas inlet devices 14 can also be used. The shielding device 5 is arranged here between the lamp heater 4 and the cold process chamber floor 2.

[0033] Figures 18 to 23 show a preferred embodiment for depositing SiC. A process gas is fed into a process chamber 11, shown only in dashed lines, which, as in the embodiment shown in Figure 13, may be tubular and surrounded by a cylindrical heating coil 4, by means of a gas inlet element 14, which is also only indicated, chemically reacting in the process chamber 11, so that a silicon carbide layer is deposited on a substrate 3. Reaction products can be removed through a gas outlet device indicated by reference numeral 15. The substrate can be introduced into the process chamber 11 or removed therefrom via a loading opening 16.

[0034] Figure 24 shows a representation similar to Figure 19. Optical sensors 27, particularly in the form of pyrometers, are provided, with which the surface temperature of the substrate 3 or the susceptor 13 can be measured at at least one point. The optical path 28 runs through an opening 25 in the housing cover. The opening 25 can be closed with a window and purged with an inert gas. The optical path 28 runs between the opening 25 and the surface of the substrate 3 or the susceptor 13. A shielding element 6, which is located directly below the opening 25, can have an opening through which the optical path 28 passes even when the shielding element 6 is exerting its greatest shielding effect. The optical path 28 runs, in particular, through a slot 26 arranged in the shielding element 6.

[0035] The shielding elements 6 can be moved between their operating positions using an actuator 30. Figure 24 shows only one actuator 30. Several sets of shielding elements 6 are arranged on the floor of the reactor housing and on the ceiling of the reactor housing, with the shielding elements 6 of each set being able to be moved independently of the shielding elements of another set by a respective actuator 30.

[0036] With a control device 29, which may include a control circuit, the shielding elements 6 of the different sets can be adjusted in such a way that the individually adjusted shielding effects Temperature of the surface of the substrate 3 or the susceptor 13 can be regulated against a set value.

[0037] In this embodiment, the shielding elements 6 are designed as strips pivotable about an axis 9, with the pivot bearings arranged directly on the floor or ceiling of the reactor housing 1. Both the floor and the ceiling form cold areas 2, which can also be formed by an active cooling device.

[0038] A plurality of strip-shaped shielding elements 6 are articulated by means of a coupling rod 17 via an axis 18 to a short arm of a shielding element 6, so that a linear displacement of the coupling rod 17 leads to a simultaneous pivoting displacement of a plurality of shielding elements 6. The shielding elements 6 can thus be pivoted zone by zone between a first operating position shown in Figure 21, in which they exert a high shielding effect, and a second operating position shown in Figure 20, in which they exert a low shielding effect.

[0039] The shielding elements 6 can be attached to the floor or ceiling of the reactor housing 1 by a support 19, which can be formed by a strip. The support 19 can be located in a groove. In the first operating position, the shielding elements can rest with a rear broad side surface against a surface of the floor or the cover.

[0040] The shielding element 6 can have a shielding body 21 with a recess in which an insert 22 is inserted. In the first operating position shown in Figure 21, a surface of the insert 22, which is designed to be highly reflective, faces the process chamber 11.

[0041] In the second operating position shown in Figure 20, the shielding elements 6 protrude substantially vertically from the floor or ceiling.

[0042] Bearing blocks 20 can be provided at both ends of the screen elements 6, with which the screen elements 6 are attached to the floor or ceiling.

[0043] In summary: The invention relates to a device for the thermal treatment of a substrate 3, comprising a heating device 4 arranged in a reactor housing 1 for heating the substrate 3. During heating of the device, a power or heat flow 8 flows from a heating device 4 to a substrate 3, and during cooling, a heat flow 7 flows from the substrate 3 to a cold region 2. To minimize the heating and cooling times, a shielding device 5 for influencing the heat flow 7 is proposed, which is adjustable between a first and a second operating position, wherein the shielding device 5 has a plurality of shielding elements 6, 6' that are movable relative to one another.

[0044] The invention particularly relates to a device in which the substrate 3 or a susceptor 13 supporting the substrate 3 is heated by a cooled heating device 4, which generates an alternating electromagnetic field that forms eddy currents in the substrate 3 or the susceptor 13. The shielding elements 6, 6' can be used to modulate heat flow from the substrate 3 or the susceptor 13 to the heating device 4.

[0045] The above statements serve to explain the inventions covered by the application as a whole, which constitute the state of the art. at least through the following combinations of features, whereby two, several or all of these combinations of features can also be combined, namely:

[0046] A device characterized in that the shielding elements (6, 6') are permeable to the alternating electromagnetic fields.

[0047] A device characterized in that the shielding elements 6, 6 Z are arranged between the heating device 4 and the substrate 3.

[0048] A device characterized in that the pivot axis 18 runs in the region of a longitudinal edge of the shielding element 6 and is arranged close to the floor or ceiling of the reactor housing 1.

[0049] A device which is characterized in that the shielding elements 6 are fastened to the reactor housing 1 by means of bearing blocks 20 arranged in the region of the narrow edges of the shielding elements 6, wherein the pivot axes 18 run through the bearing blocks 20.

[0050] A device which is characterized in that a plurality of shielding elements 6 which are adjustably arranged on the floor or on the ceiling of the reactor housing are coupled to one another by means of a coupling rod 17, wherein a linear displacement of the coupling rod 17 leads to a simultaneous pivoting displacement of a plurality of shielding elements 6.

[0051] A device which is characterized in that the screen device 5 has a plurality of screen elements 6, 6' which are movable relative to one another.

[0052] A device which is characterized in that at least one shielding element 6 of the shielding device 5 is rotatable about an axis of rotation 6 which has a directional component perpendicular to the direction of the heat flow 7 and which is rotated about the axis of rotation 6 to change the operating position.

[0053] A device characterized in that at least two shielding elements 6, 6' are arranged such that they at least partially overlap in the second operating position.

[0054] A device characterized in that a second heat flow 8 or power flow from the heating device 4 to the substrate 3 flows through a different or the same heat transfer space through which the first heat flow 7 flows.

[0055] A device characterized in that the axes of rotation 6 of several or all of the shielding elements 6 run perpendicular to the direction of the heat flow 7 and extend parallel to one another.

[0056] A device which is characterized in that the shielding elements 6 form a closed shielding surface in the first operating position and are rotated in particular by 90 degrees relative to the first operating position in the second operating position.

[0057] A device which is characterized in that two shielding element supports 23, 23' form shielding elements 6, 6' which are displaceable in two planes arranged parallel to one another, wherein the shielding element supports 23, 23' are rotatable relative to one another about an axis of rotation 9 which is perpendicular to the planes or are displaceable relative to one another in the planes and wherein between the shielding elements 6, 6' of the shielding element supports 23, 23' there is arranged a free space 24, 24', the surface area of ​​which corresponds to the surface area of ​​the adjacent shielding element 6, 6'.

[0058] A device characterized in that the shielding elements 6, 6' are narrow, rectangular strips or circular sectors and / or that the shielding elements 6, 6' have a surface facing the substrate 3 which has a reflection factor greater than 0.6 or an absorption factor less than 0.4 and / or that the one or more shielding elements 6, 6' are independently adjustable and / or that the shielding elements 6, 6' are transparent to high-frequency electromagnetic alternating fields.

[0059] A method for treating a substrate in an apparatus according to any one of the preceding claims, wherein the shielding device 5 assumes its first operating position during heating of the substrate and its second operating position during cooling of the substrate.

[0060] A method which is characterized in that at least one or more of the shielding elements 6, 6' of the shielding device 5 assume an intermediate position between the first and second operating positions during a substrate treatment step.

[0061] A method which is characterized in that a temperature of the substrate 3 or a susceptor 13 is regulated against a desired value by means of a control device 29 by adjusting the shielding elements 6, 6' of the shielding device 5.

[0062] A method which is characterized in that screen elements 6, 6' assigned to different zones are individually adjusted by a respective actuator 30.

[0063] All disclosed features are essential to the invention (individually, but also in combination with one another). The disclosure of the application hereby fully incorporates the disclosure content of the associated / attached priority documents (copy of the prior application), also for the purpose of incorporating features of these documents into claims of the present application. The subclaims characterize, even without the features of a referenced claim, independent inventive developments of the prior art with their features, in particular for filing divisional applications based on these claims. The invention specified in each claim may additionally comprise one or more of the features provided in the above description, in particular with reference numbers, and / or specified in the list of reference numbers.The invention also relates to designs in which individual features mentioned in the above description are not implemented, in particular insofar as they are clearly unnecessary for the respective intended use or can be replaced by other technically equivalent means. List of reference symbols 1 reactor casing 23' shielding element carrier 2 cold area, cooling device 24 free space 24' free space 3 Substrate 25 Opening 4 Heating device 26 Slot 5 Shielding device 27 Pyrometer 6 shielding element 28 optical path 6' shield element 29 control device 7 first heat flow 30 actuator 8 second heat flow 31 outer zone 8' heat return 32 inner zone 9 Axis 33 Central element 10 Drive 34 middle ring element 11 Process chamber 35 outer ring element 12 Wall 13 Susceptor 14 Gas inlet 15 Gas outlet 16 Loading opening 17 Coupling rod 18 Axis 19 carriers 20 bearing block 21 umbrella body 22 Insert 23 umbrella element supports

Claims

Claims:

1. Apparatus for the thermal treatment of a substrate (3), comprising a heating device (4) arranged in a reactor housing (1) and generating alternating electromagnetic fields for heating a hot region in which the substrate (3) is located, wherein a shielding device (5) having a plurality of shielding elements (6, 6') which are movable relative to one another and are designed to be reflective or insulating against a heat flow (7) is arranged in a radiant heat transfer path between the hot region and a cold region (2), wherein the shielding elements (6, 6') are adjustable between a first operating position and a second operating position, wherein the shielding device (5) exerts a greater shielding effect on the heat flow (7) in the first operating position than in the second operating position, characterized in that the shielding elements (6, 6') are permeable to the alternating electromagnetic fields.

2. Device according to claim 1, characterized in that the shielding elements (6, 6 Z ) are arranged between the heating device (4) and the substrate (3).

3. Device for the thermal treatment of a substrate (3) with a heating device (4) arranged in a reactor housing (1) for heating a hot area in which the substrate (3) is located, wherein in a radiation heat transfer path between the hot area and a cold area (2) a shielding device (5) is arranged, which has a plurality of shielding elements (6, 6') which are movable relative to one another and are designed to be reflective and / or insulated against a heat flow, wherein the shielding elements formed by narrow strips Shielding elements (6, 6') are pivotable between a first operating position and a second operating position about a pivot axis (18), wherein the shielding device (5) exerts a greater shielding effect on the heat flow (7) in the first operating position than in the second operating position, characterized in that the pivot axis (18) runs in the region of a longitudinal edge of the shielding element (6) and is arranged close to the floor or ceiling of the reactor housing (1). Device according to claim 2, characterized in that the shielding elements (6) are fastened to the reactor housing (1) by means of bearing blocks (20) arranged in the region of the narrow edges of the shielding elements (6), wherein the pivot axes (18) run through the bearing blocks (20). Device for the thermal treatment of a substrate (3) with a heating device (4) arranged in a reactor housing (1) for heating a hot area in which the substrate (3) is located,wherein a shielding device (5) is arranged in a radiation heat transfer path between the hot region and a cold region (2), said shielding device having a plurality of shielding elements (6, 6') which are movable relative to one another and are designed to be reflective and / or insulated against a heat flow, wherein the shielding elements (6, 6') are pivotable about a pivot axis (18) between a first operating position and a second operating position, wherein the shielding device (5) exerts a greater shielding effect on the heat flow (7) in the first operating position than in the second operating position, characterized in that a plurality of shielding elements (6) which are adjustably arranged on the floor or on the ceiling of the reactor housing are coupled to one another by means of a coupling rod (17), wherein a linear displacement, mounting of the coupling rod (17) leads to a simultaneous pivoting displacement of several shielding elements (6). Device for the thermal treatment of a substrate (3) with a heating device (4) arranged in a reactor housing (1) for heating a hot region in which the substrate (3) is located, wherein a shielding device (5) having several shielding elements (6, 6') that are movable relative to one another and designed to be reflective and / or insulating against heat flow is arranged in a radiant heat transfer path between the hot region and a cold region (2), wherein the shielding elements (6, 6') are pivotable between a first operating position and a second operating position about a pivot axis (18), wherein the shielding device (5) exerts a greater shielding effect on the heat flow (7) in the first operating position than in the second operating position, characterized in that two shielding element supports (23,23') form displaceable shielding elements (6, 6') in two mutually parallel planes, wherein the shielding element supports (23, 23') are rotatable relative to one another about a rotation axis (9) perpendicular to the planes or displaceable relative to one another in the planes, and wherein a free space (24, 24') is arranged between the shielding elements (6, 6') of the shielding element supports (23, 23'). Device according to claim 6, characterized in that the surface area of ​​the free space corresponds to the surface area of ​​the adjacent shielding element (6, 6'). Device according to claim 6 or 7, characterized in that the shielding elements (6, 6') are narrow, rectangular strips or circular sectors. Device according to one of the preceding claims, characterized in that the shielding elements (6, 6') have a surface facing the substrate (3) which has a reflectance > 0.6 and an absorbance < 0.

4. Device according to one of the preceding claims, characterized by a susceptor (13) supporting the substrate (3), which can be heated by the heating device (4) to temperatures above 1,000 °C. Device according to one of the preceding claims, characterized in that the heating device (4) is a coil surrounding the process chamber (11) having the susceptor (13), wherein the shielding elements (6, 6') are arranged inside or outside the coil.Device according to one of the preceding claims, characterized in that a shielding element (6), in particular fastened to a ceiling of the reactor housing (1), forms a slot (26) aligned with an opening (25) through which an optical path (28) of a pyrometer (27) extends. A method for treating a substrate in a device according to one of the preceding claims. wherein the shielding device (5) assumes its first operating position during heating of the substrate and its second operating position during cooling of the substrate. Method according to claim 13, characterized in that at least one or more of the shielding elements (6, 6') of the shielding device (5) assume an intermediate position between the first and second operating positions during a substrate treatment step. Method according to claim 13 or 14, characterized in that a temperature of the substrate (3) or of a susceptor (13) is regulated against a target value by means of a control device (29) by adjusting the shielding elements (6, 6') of the shielding device (5). Method according to one of claims 12 to 15, characterized in that shielding elements (6, 6') assigned to different zones are individually adjusted by a respective actuator (30).Apparatus or method characterized by one or more of the characterizing features of any of the preceding claims.

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