Substrate support device for reaction chamber, reaction chamber, and epitaxial reactor using gas flow rotation

Abstract

The apparatus (420) is for supporting a substrate in a reaction chamber of an epitaxial reactor, the apparatus having a first surface (422A) configured to be positioned above the apparatus (420) when the apparatus (420) is in use, and a second surface (422B) configured to be positioned below the apparatus (420) when the apparatus (420) is in use, a disk-shaped element (422) configured to receive a gas flow (F) and rotate the apparatus (420) about its axis (X), and a substrate (422) integral with the disk-shaped element (422). and preferably comprising a substrate support element (424) adjacent said first surface (422A), and a shaft (426) coaxial with and integral with said disk-shaped element (422) and having a first end (426A) at said second surface (422B), said shaft (426) having at least one protrusion (428A, 428B, 428C) at its second end (426B), the rotation of which is configured to be detected by a pyrometer (430) or a thermographic camera.

Description

Technical Field

[0001] The present invention relates to a substrate support device for a reaction chamber of an epitaxial reactor configured to deposit a semiconductor material on a substrate, as well as a reaction chamber and an epitaxial reactor using such a device.

[0002] Specifically but not limitedly, the present invention relates to a "hot wall type" reaction chamber, that is, in this reaction chamber, the walls are intentionally kept at a high temperature and are often further heated. In contrast, in a "cold wall type" reaction chamber, the walls are intentionally kept at a low temperature, for example, by a cooling gas flow and / or a coolant flow.

[0003] This type of reaction chamber is mainly used for the epitaxial deposition of silicon carbide on a silicon carbide substrate ("homoepitaxial" process) or a substrate made of another material ("heteroepitaxial" process).

Background Art

[0004] In order to make the layer of the deposited material uniform, rotation is often used among others. In the reaction chamber, a device is arranged to support the substrate (directly or indirectly), one or more substrates are placed on the device, and the device is rotated at least during the deposition process.

[0005] The rotation speed of the device, and thus the rotation speed of the substrate, is predetermined at least during the deposition process, and it is important that it is constant over time.

[0006] There is a reaction chamber in which the rotation of the substrate support device is obtained by a gas flow pushing the device (rather than by a rotating shaft mechanically coupled to the device), in particular a "hot wall type" reaction chamber. This type of solution is shown and disclosed, for example, in five international patent applications according to the applicant's International Publication No. WO 2004 / 053187, International Publication No. WO 2004 / 053188, International Publication No. WO 2004 / 053189, International Publication No. WO 2005 / 121417, and International Publication No. WO 2015 / 092525 incorporated herein by reference.

[0007] In this case, that is, in the case of hydrodynamic rotation, the estimated value of the rotation speed of the device based on the flow rate of the gas flow is not accurate and cannot be determined or measured because there are several factors that affect the rotation speed. For example, the rotation speed may be affected by deposits that accumulate over time on the substrate support device and by the positioning and repositioning of the substrate support device.

[0008] Of course, when mechanical rotation is used, that is, when a motor outside the reaction chamber transmits a rotational motion to the substrate support device by a shaft to obtain mechanical rotation, the rotation speed is accurately known and controlled, but this solution becomes more complex both in terms of configuration / structure and assembly / disassembly. SUMMARY OF THE INVENTION

[0009] A general object of the present invention is to overcome such problems, that is, to estimate (specifically, to estimate with high precision, that is, to determine) the rotation speed of the substrate support device in the reaction chamber, particularly using the rotation of the gas flow. The device is in the reaction chamber, precisely in the central zone of the reaction chamber, which zone is at a very high temperature during the process, for example, the temperature is 800 - 1200 °C in the case of silicon epitaxial deposition and can be 1600 - 3000 °C in the case of silicon carbide epitaxial deposition, so such problems are particularly difficult.

[0010] This general and other more specific objects are achieved by the description of the appended claims, which form an essential part of this specification.

[0011] The object of the present invention is a substrate support device, as well as a reaction chamber and an epitaxial reactor using such a device.

[0012] The present invention will become more readily apparent from the following detailed description considered in conjunction with the accompanying drawings.

Brief Description of the Drawings

[0013]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Embodiments for Carrying Out the Invention

[0014] As can be easily understood, there are various ways to actually implement the present invention, and the present invention is defined in its main preferred aspects in the appended claims and is not limited to either the following detailed description or the appended claims.

[0015] The present invention relates to a reaction chamber that specifically uses the rotation of a gas flow, although not limited thereto.

[0016] The present invention relates to a "hot wall type" reaction chamber, although not limited thereto.

[0017] The applicant has already dealt with this type of reaction chamber, for example, the applicant has already filed the above-mentioned five international patent applications incorporated herein by reference.

[0018] An example of this type of reaction chamber 1 is schematically shown in FIGS. 1, 2 and 3, and the reaction chamber 1 extends uniformly along the longitudinal direction. It comprises a susceptor assembly consisting of four susceptor elements 2, 3, 4 and 5, these susceptor elements defining the reaction and deposition zone 10 and being housed in a casing 7 made of heat insulating material, the casing 7 being inserted into a quartz tube 8. The casing 7 consists of a tube 71 (specifically having a circular cross-section) and two caps 72 and 73 (specifically having a circular cross-section as the tube cross-section). Around the tube 8, an inductor 9 is wound, which is configured to heat the elements 2, 3, 4 and 5 made of graphite by electromagnetic induction. The inductor 9 is represented by a dashed line since it is not strictly part of the reaction chamber 1. Elements 4 and 5 are two slats (which can be regarded as the walls of the reaction chamber) and constitute the side walls of the zone 10. Elements 2 and 3 are protruding solids having a cross-section with an arcuate shape and through holes 20 and 30 in the cross-section of the arcuate shape. Thus, they consist of a planar slab 21 and 31 (which can be regarded as the inner wall of the reaction chamber) and a curved slab 22 and 32 (which can be regarded as the outer wall of the reaction chamber), and the planar slabs 21 and 31 respectively constitute the upper and lower walls of the zone 10. The lower wall 31 is configured to house the assembly 6, and this assembly 6 comprises, among other things, a support element 61 (rotatable during the deposition process) configured to support at least one substrate 62 that receives depositions arranged in a recess of the element. According to this example, the support element 61 can be inserted into or removed from the zone 10. The two caps 72 and 73 are shown as if they were closed, but they have openings, specifically an opening for the inlet of the precursor gas in the cap 73 (see the black arrow) and an opening for the outlet of the exhaust gas in the cap 72 (see the black arrow). Also, as will become further apparent hereinafter, there may be openings in tubes configured to flow a rotating gas and in electrical cables configured to transmit electrical signals from, for example, a pyrometer and temperature sensors (inside the reaction chamber).

[0019] Referring to FIGS. 1, 2 and 3, when an alternating current is supplied to the inductor 9, an alternating current is induced in the susceptor elements 2, 3, 4 and 5, in particular elements 2 and 3 (note that all or part of elements 4 and 5 may be made of an electrically insulating material, and thus may contribute less to the heating of the reaction and deposition zone 10). The most common material for manufacturing the susceptor elements is graphite, which may be used in an exposed state or may be used in a coated state, for example, coated with silicon carbide or tantalum carbide.

[0020] The reaction chambers 1 of FIGS. 1, 2 and 3 are suitable for many variations, for example, those having cross-sections of different shapes (polygonal, elliptical, etc.), those having an upper susceptor element without through holes, those having a side susceptor element with through holes, those having a substrate support element configured to directly support a specific number of substrates, and the like.

[0021] In FIGS. 1 and 2, a dashed box associated with reference numeral 428 can be recognized in order to schematically show the presence of the substrate support device according to the present invention.

[0022] Possible forms of the assembly 6 will become apparent from the following description and FIG. 4.

[0023] Note that in FIG. 4, the support element 61 is shown according to its non-limiting embodiment. Conceptually, such an element can be described by a set of parts as follows. This includes a plate portion simply called a "plate" having a circular shape and a support surface configured to support a substrate. Specifically, the support surface has substantially the same shape and size as the substrate and constitutes the bottom of the recess of the element. This further includes a first portion of an edge that completely surrounds the plate and extends axially to form the side wall of the recess of the element. Finally, this includes a second portion of the edge that completely surrounds the first portion of the edge and extends radially, and the second portion of the edge can be described as a flange located around the first portion of the edge. The parts disclosed above in this specification can be joined to form one or more single parts. Each of the parts disclosed above in this specification can be formed by two or more single parts mechanically coupled between them.

[0024] (Except for FIG. 4) Although not emphasized in the figure, the reaction chamber and the epitaxial reactor of the figure perform rotation of the device to support the gas flow substrate.

[0025] As described above, a general object of the present invention is to estimate and further determine the rotational speed of a substrate support device (for example, the device generally indicated by reference numeral 420 in FIG. 4).

[0026] A general idea for achieving this object is to use an opto-thermal device, particularly a thermographic camera, and more preferably a pyrometer (for example, the device indicated by reference numeral 430 in FIG. 4).

[0027] In practice, for example, and specifically, a pyrometer (for example, the element indicated by reference numeral 430 in FIG. 4) can be used to estimate or determine the rotational speed of a substrate support device (for example, the element indicated by reference numeral 420 in FIG. 4) in the reaction chamber of an epitaxial reactor. For such use, While keeping the pyrometer in a fixed direction (e.g., the direction indicated by reference numeral 433 in FIG. 4), the apparatus rotates such that the temperature detected by the pyrometer is affected by periodic variations due to the rotation of the apparatus (see the plots in FIGS. 6-2, 6-3, and 6-4). and Based on the period of the periodic variations, calculate the rotational speed by a processing electronic unit (e.g., the element indicated by reference numeral 490 in FIG. 4) electrically connected to the pyrometer. is included.

[0028] Such an idea is preferably implemented in a reaction chamber using the rotation of a gas flow, specifically a "hot wall" type reaction chamber, and / or by epitaxial deposition of silicon carbide.

[0029] Hereinafter, reference is made to the embodiment of FIG. 4, but such reference should not be considered limiting.

[0030] To utilize such a general idea, the substrate support device 420 in the reaction chamber of the epitaxial reactor is configured in a specific manner. In the embodiment of FIG. 4, the device 420 indirectly supports the substrate by the support element 61. This device specifically includes a first surface 422A configured to be disposed above when the device 420 is in use, and a second surface 422B configured to be disposed below when the device 420 is in use, and a disk-shaped element 422 configured to receive the gas flow F and rotate the device 420 about its axis X, a substrate support element 424 integral with the disk-shaped element 422 and preferably adjacent to the first surface 422A, a shaft 426 coaxial and integral with the disk-shaped element 422 and having a first end 426A on (at least) the second surface 422B, is provided.

[0031] The shaft 426 has at least one protrusion 428A, 428B, 428C at its second end 426B, and its rotation is configured to be detected by a thermometer 430 or a thermographic camera.

[0032] As shown in FIG. 4, the elements 422 and 424 can be integrated to form a single piece (component).

[0033] As shown in FIG. 4, the shaft 426 can be integrated with the elements 422 and 424.

[0034] As shown in FIG. 4, the first end 426A of the shaft 426 is located at both the elements 422 and 424. Further, in the example of FIG. 4, the element 422 consists of a disk with a substantially complete plane and a central hole provided, but as an alternative, the element 422 can have a central protrusion (for example, a cylindrical protrusion) configured to be mechanically coupled to the shaft 426 instead of the central hole. In this case, the first end 426A of the shaft 426 is located at the central protrusion of the element 422.

[0035] As described and illustrated in the above five international patent applications, the disk-shaped element 422 can have a recess on the back configured to receive the gas flow F.

[0036] Preferably, the rotation of at least one protrusion is configured to be detected by the thermometer 430.

[0037] The shaft 426 can have two or three protrusions at its one second end 426B. Preferably, the shaft 426 can have three protrusions 428A, 428B, 428C (specifically, arranged radially at 120° from each other), and their rotations are configured to be detected by a thermometer 430 or a thermographic camera, and such protrusions are preferably equal among them.

[0038] At least one protrusion can be a plate (specifically rectangular and generally substantially flat) extending perpendicular to the axis X of the shaft 426.

[0039] The device 420 can be made entirely of graphite, and in particular, it is preferable that both the element 422 and the element 424 as well as the shaft 426 are made of graphite.

[0040] The shaft 426 can be mechanically and directly fixed to the disk-shaped element 422. For example, such fixation can be performed by screws, tongue-key groove couplings, or snap fits.

[0041] At least one protrusion is mechanically and directly fixed to the shaft 426. For example, at least one protrusion can be inserted into a shaft hole. Alternatively, at least one protrusion can be integrated with an element screwed onto the shaft.

[0042] The device 420 can include a protective socket surrounding a part of the shaft 426 (particularly at the hole in the wall 31 of the reaction chamber). Such a socket functions as a low-friction rotatable guide and can be regarded as a consumable.

[0043] The substrate support device according to the present invention, particularly the device 420 in FIG. 4, is usually a component of the reaction chamber of an epitaxial reactor (i.e., for performing epitaxial deposition of a layer of semiconductor material on a substrate).

[0044] Such an application is particularly advantageous for a reaction chamber provided with a gas rotation system of the substrate support device.

[0045] In this case, the disk-shaped element 422 of the device 420 can be rotatably accommodated in a seat on the wall of the reaction chamber. In the example of FIG. 4, the wall 31 has such a seat, specifically, the slab 414 has such a seat.

[0046] The wall 31 of FIG. 4 comprises a slab 414 and a cover or lining 412. An internal duct 416 is provided within the slab 414 for flowing a rotational gas and guiding it to the rear of element 422, and a temperature measuring device 460 connected to an electric cable 465 is also inserted into the slab 414.

[0047] As shown in FIG. 4, the seat of the wall 31 advantageously has a through-hole through which the shaft 426 of the device 420 passes, whereby at least one projection 428 can be arranged in the hole of the element of the reaction chamber (see, for example, the hole 30 of the element 3 of the reaction chamber 1 in FIGS. 1 and 2).

[0048] Advantageously, the wall for the seat of the substrate support device is an inner wall (see, for example, the wall 31 of the reaction chamber 1 in FIG. 1), i.e., a wall that does not define the outer periphery of the reaction chamber.

[0049] Advantageously, in use, at least one rotatable projection of the shaft 426 of the device 420 is within the cavity of the reaction chamber, specifically between the inner wall (i.e., the wall that does not define the outer periphery of the reaction chamber) and the outer wall (i.e., the wall that at least partially defines the outer periphery of the reaction chamber) of the reaction chamber. In the examples of FIGS. 1 and 4, the inner wall is the wall 31 and the outer wall is the wall 32.

[0050] As described above, the present invention requires a thermographic camera, preferably a pyrometer, oriented to detect the rotation of the shaft of the device, or more effectively the rotation of at least one projection of the shaft, and the thermographic camera or pyrometer (such as that shown by 430 in FIG. 4) can be considered as part of the reaction chamber according to the present invention.

[0051] According to the exemplary embodiment of FIG. 4 (this figure shows some components of the embodiment of the epitaxial reactor according to the present invention), the epitaxial reactor includes a control electronic unit 490 that is electrically connected (see electrical cable 435), and a thermographic camera or preferably a pyrometer 430 of the reaction chamber, and is configured to estimate or determine the rotation speed of the substrate support device 420 of the reaction chamber based on the electrical signal received by the thermographic camera or pyrometer 430. It is worth observing that in FIG. 4, the light rays seem to directly enter and exit the pyrometer 430, but it must not be excluded that the pyrometer or thermographic camera is optically connected to an optical fiber.

[0052] Furthermore, according to the embodiment of FIG. 4, conveniently, the control electronic unit 490 can always be electrically connected to the regulator (controller) of the reaction chamber, specifically the mass flow controller 440 (see electrical cable 445), and the control electronic unit 490 is configured to set the rotational gas flow based on the estimated or determined rotational speed. As can be seen, the regulator, specifically the mass flow controller 440, is fluidly connected to the duct 416, for example, by a pipe 450.

[0053] According to the present invention, in order to determine the rotation speed of the substrate support device, the pyrometer (or in some cases a thermographic camera) must be properly directed towards a rotatable protrusion, or in the case of two or more, a plurality of rotatable protrusions. Referring to FIG. 4, specifically, there are three in number, and the pyrometer 430 must be properly directed towards the rotatable protrusions 428 that are arranged radially at 120° from each other, which is a fixed predetermined direction setting.

[0054] To understand the concept of "properly", FIGS. 5 and 6 can be referred to.

[0055] In FIG. 5, four different directional settings of the pyrometer 430 are illustrated. According to the first directional setting, the pyrometer is directed towards point 51 on the cap 72 of the casing 7, and the straight line (433 in FIG. 4) between the pyrometer 430 and point 51 is not blocked by the protrusion 428. According to the second directional setting, the pyrometer is directed towards point 52 on the cap 72 of the casing 7, and the straight line (433 in FIG. 4) between the pyrometer 430 and point 52 is blocked by the protrusion 428 in its zone (or a very distant zone) from the rotation axis. According to the third directional setting, the pyrometer is directed towards point 53 on the cap 72 of the casing 7, and the straight line (433 in FIG. 4) between the pyrometer 430 and point 53 is blocked by the protrusion 428 in its intermediate zone. According to the fourth directional setting, the pyrometer is directed towards point 54 on the cap 72 of the casing 7, and the straight line (433 in FIG. 4) between the pyrometer 430 and point 54 is blocked by the protrusion 428 in its zone close to (or very close to) the rotation axis.

[0056] In FIG. 6, the temporal trend of the temperature read, i.e., detected, by the pyrometer 430 (e.g., every 10 - 100 mS) is shown for illustrative purposes. It can be assumed that the protrusion 428 is at a high temperature (e.g., 1200 - 1600 °C), and the cap 72 of the casing 7 made of a thermal insulation material is at a low temperature LT (e.g., 400 - 800 °C). FIG. 6 - 1 shows the trend of the temperature over time when the pyrometer follows the first directional setting, which is a horizontal straight line. FIG. 6 - 2 shows the trend of the temperature over time when the pyrometer follows the second directional setting, which is a set of narrow and widely separated peaks. FIG. 6 - 3 shows the trend of the temperature over time when the pyrometer follows the third directional setting, which is a line that appears to be a sine curve with a large width approximately equal to (HT - LT) / 2. FIG. 6 - 4 shows the trend of the temperature over time when the pyrometer follows the fourth directional setting, which is a line that appears to be a sine curve with a small width.

[0057] The rotational speed of the substrate support device 420 can be obtained from the periodic trends of FIGS. 6-2, 6-3, and 6-4, and it can be seen that the rotational speed cannot be estimated or determined in the first direction setting. The ideal direction setting for estimating or determining the rotational speed is the third direction setting, i.e., while the protrusion 428 is rotating, the straight line between the pyrometer 430 and the point 53 is blocked from the intermediate zone between the tip (far from the axis of rotation) and the base (close to the axis of rotation) of the protrusion 428 over a certain time range. Estimating or determining the rotational speed (which can be, for example, from 10 to 100 rpm) involves estimating or determining the period of the temperature time range, which can be done by known methods in the time domain or frequency domain, and by processing the pyrometer signal digitally and / or analogously.

[0058] From the above, it can be seen that in the process of assembling the reaction chamber, the pyrometer preferably needs to adjust its direction setting.

[0059] It should be noted that when a thermographic camera is used instead of a pyrometer, the direction setting may not be as important, but the signal processing can become significantly more complex.

Claims

1. A substrate support device (420) in a reaction chamber of an epitaxial reactor, having a first surface (422A) configured to be disposed upward when the device (420) is in use, and a second surface (422B) configured to be disposed downward when the device (420) is in use, and a disk-shaped element (422) configured to receive a gas flow (F) and rotate the device (420) about its axis (X), a substrate support element (424) integral with the disk-shaped element (422) and preferably adjacent to the first surface (422A), a shaft (426) coaxial and integral with the disk-shaped element (422) and having a first end (426A) on the second surface (422B), comprising, the shaft (426) having at least one protrusion (428A, 428B, 428C) at its second end (426B), and its rotation being configured to be detected by a thermometer (430) or a thermographic camera, a substrate support device (420).

2. The device according to claim 1, wherein the rotation of the at least one protrusion (428A, 428B, 428C) is configured to be detected by the thermometer (430).

3. The device (420) according to claim 1 or claim 2, wherein the shaft has two protrusions, three protrusions (428A, 428B, 428C) or four protrusions at its second end (426B) configured such that their rotation is detected by the thermometer (430) or a thermographic camera, and the protrusions (428A, 428B, 428C) are preferably equidistant from each other.

4. The device (420) according to any one of claims 1 to 3, wherein the at least one protrusion (428A, 428B, 428C) is a plate extending perpendicular to the axis (X) of the shaft (426).

5. The device (420) according to any one of claims 1 to 4, characterized in that it is entirely made of graphite.

6. The device (420) according to any one of claims 1 to 5, wherein the shaft (426) is mechanically fixed to the disk-shaped element (422).

7. The device (420) according to any one of claims 1 to 6, wherein the protrusions (428A, 428B, 428C) are mechanically fixed to the shaft (426).

8. The device (420) according to any one of claims 1 to 7, comprising a protective socket surrounding a part of the shaft (426).

9. A reaction chamber (1) for an epitaxial reactor, comprising the device (420) according to any one of claims 1 to 8.

10. The reaction chamber (1) according to claim 9, comprising a system for gas rotation of the substrate support device (420).

11. The reaction chamber (1) according to claim 9 or claim 10, wherein a disk-shaped element (422) of the device (420) is rotatably received in a seat of a wall (31) of the reaction chamber (1).

12. The reaction chamber (1) according to claim 11, wherein the seat has a through hole through which a shaft (426) of the device (420) passes.

13. The reaction chamber (1) according to claim 11 or claim 12, wherein the wall (31) is an inner wall, and the inner wall is a wall that does not define the outer periphery of the reaction chamber.

14. The reaction chamber (1) according to any one of claims 11 to 13, wherein the wall (31) has an internal duct (416) configured to rotate the device (420) by flowing a gas stream (F).

15. During use, the rotation protrusions (428A, 428B, 428C) of the shaft (426) of the device (420) are within the cavity (30) of the reaction chamber (1), specifically between the inner wall (31) and the outer wall (32) of the reaction chamber (1), the inner wall being a wall that does not define the outer periphery of the reaction chamber, and the outer wall being a wall that at least partially defines the outer periphery of the reaction chamber. The reaction chamber (1) according to any one of claims 9 to 14.

16. The reaction chamber (1) according to any one of claims 9 to 15, comprising a thermographic camera or preferably a pyrometer (430) configured to detect the rotation protrusions (428A, 428B, 428C) of the shaft (426) of the device (420).

17. An epitaxial reactor comprising the reaction chamber (1) according to any one of claims 9 to 16.

18. The epitaxial reactor according to claim 17, comprising a control electronic unit (490) electrically connected to the thermographic camera or preferably the pyrometer (430) of the reaction chamber (1) and configured to estimate or determine the rotation speed of the substrate support device (420) of the reaction chamber (1) based on an electrical signal received from the thermographic camera or the pyrometer (430).

19. The control electronic unit (490) is electrically connected to a regulator of the reaction chamber (1), specifically a mass flow controller (440), and is configured to set a rotational gas flow based on the estimated or determined rotational speed. The epitaxial reactor according to claim 18.

20. Use of a pyrometer (430) for estimating or determining the rotational speed of the device (420) according to any one of claims 1-8, while the device (420) rotates in such a manner that the temperature detected by the pyrometer (430) is affected by periodic variations due to the rotation of the device (420), maintaining the orientation of the pyrometer (430) in a constant direction, wherein the rotational speed is calculated by a processing electronic unit (490) electrically connected to the pyrometer (430) based on the period of the periodic variations, Use of a pyrometer (430).

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