JP5184431B2 - MOCVD equipment - Google Patents

Description

  The present invention relates to an MOCVD apparatus for crystal growth using a gas on a substrate such as a semiconductor wafer, and more particularly to an MOCVD apparatus equipped with a measuring device capable of measuring the shape of a substrate in a reaction chamber during crystal growth.

  For the production of compound semiconductors such as semiconductor laser elements and LED (Light Emitting Diode) elements, MOCVD (Metal Organic Chemical Vapor Deposition) apparatus or MBE (Molecular Beam Epitaxy method; Molecular Beam) Epitaxy) devices are widely used.

  In particular, the MOCVD apparatus is an apparatus for crystal growth using an organic metal or other gas, and since it has better productivity and maintainability than the MBE apparatus, it is generally used when mass-producing elements industrially. An MOCVD apparatus is used.

  For example, FIG. 6 is a schematic configuration diagram showing an example of a conventional MOCVD apparatus. This MOCVD apparatus is generally called a horizontal MOCVD apparatus because the source gas 12 flows horizontally in the flow path.

  As shown in FIG. 6, the horizontal MOCVD apparatus 1 includes a reaction chamber 2 and a flow path of a source gas 12 that passes through the reaction chamber 2. The flow path is provided with a gas outlet 11 at one end and a discharge path 14 at the other end. In addition, an opening is formed in a substantially central portion of the flow path, and a mounting plate 5 is installed in the opening. The mounting plate 5 includes a substrate 3 or a substrate holding member that holds the substrate 3. Yes. A heater 8 for heating the substrate 3 is installed below the mounting plate 5.

  The source gas 12 is supplied from the gas outlet 11 as a crystal film source, passes through the substrate 3 mounted on the mounting plate 5 and heated by the heater 8, and then exhausted from the exhaust path 14. . As a result, desired crystal growth is performed on the substrate 3 by performing a desired chemical reaction in the vicinity of the substrate 3.

  In addition, the mounting plate 5 may be rotated by a rotation mechanism. In addition, a substantially parallel partition wall 10 that separates the space inside the reaction chamber 2 is provided around the mounting plate 5.

  Such an MOCVD apparatus 1 has a small number of substrates capable of crystal growth at the same time, about 1 to 3. However, the structure of the apparatus is simple and the scale is small, and the uniformity of the flow of the source gas 12 can be easily obtained. Widely used from purpose to production of high quality crystals.

  FIG. 7 is a schematic configuration diagram showing another example of a conventional MOCVD apparatus. In this MOCVD apparatus 1 ′, as shown in FIG. 8, a plurality of (six in this example) substrates 3 are provided in the reaction chamber 2 and a plurality of mounting plates 5 provided on the upper surface of the turntable 4. It is put on.

  As shown in FIG. 7, the turntable 4 is supported on the upper end of the rotating shaft 6, and the rotating shaft 6 is rotated by a motor 7. In addition, the plurality of mounting plates 5 provided on the upper surface of the turntable 4 are each configured to rotate.

  As a mechanism in which the mounting plate 5 rotates, there is a method of rotating in synchronization with the rotation of the turntable 4 by meshing gears as described in Patent Document 1, or a mounting plate 5 as described in Patent Document 2. There is a method of floating and rotating the mounting plate 5 by supplying a rotation driving gas from below. Therefore, the substrate 3 placed on the mounting plate 5 rotates and revolves due to the rotation of the turntable 4 and the rotation of the mounting plate 5.

  The mechanism for rotating and revolving the substrate 3 is provided to improve the uniformity of the crystal growth layer. During the crystal growth, the substrate 3 is rotated and revolved by this to grow a crystal growth layer ( The uniformity of the film can be improved.

  Furthermore, a heater 8 is disposed below the turntable 4, and the substrate 3 is heated by the heater 8. Above the turntable 4, a substantially parallel partition wall 10 that separates the space inside the reaction chamber 2 is provided.

  A supply pipe 9 is connected to the upper part of the reaction chamber 2. One end of the supply pipe 9 is connected to the gas supply device 13, and the other end is disposed between the turntable 4 and the partition wall 10 and serves as a gas outlet 11. Therefore, the source gas 12 is supplied as a raw material for the crystal film radially from the rotation axis of the turntable 4 along the surface of the turntable 4.

  The raw material gas 12 supplied from the gas supplier 13 via the supply pipe 9 was placed on the mounting plate 5 and passed on the substrate 3 heated by the heater 8, and then provided on the outer periphery of the turntable 4. Exhaust from the exhaust path 14. As a result, desired crystal growth is performed on the substrate 3 by performing a desired chemical reaction in the vicinity of the substrate 3.

  The MOCVD apparatus 1 ′ includes an apparatus having a mechanism for rotation and revolution, an apparatus having only a mechanism for rotation, an apparatus having only a mechanism for rotation, and an apparatus for which neither mechanism exists. There is also an apparatus in which the partition wall 10 does not exist.

  The MOCVD apparatus 1 ′ is spreading to production sites as the number of substrates that can grow crystals at the same time is increasing. However, the MOCVD apparatus 1 ′ has problems in uniformity of material gas and temperature as compared with the MOCVD apparatus 1. is there.

  Further, in the MOCVD apparatus, when the substrate 3 is heated and a crystal film is grown on the surface of the substrate 3, the substrate 3 may be warped due to a difference in thermal expansion or lattice mismatch between the crystal growth layer and the substrate. .

  In particular, it is known that the substrate is warped in the film formation of a group III nitride centering on a GaN-based compound semiconductor. For example, Patent Document 3 describes a problem that occurs when a substrate is warped and a method for solving the problem.

  However, Patent Document 3 pays attention only to the warp of the substrate after crystal growth and the problems associated therewith, and the warp of the substrate during crystal growth inside the MOCVD apparatus and the problems associated therewith are described (focused). Not.

  If the substrate warpage is measured in a normal environment after crystal growth, a method using the principle of triangulation using laser light can be used as described in Patent Document 4, for example.

  As a method using the principle of triangulation, FIG. 9 shows a schematic diagram of the arrangement of each device when it is considered to measure the warpage of the substrate in the reaction chamber 2.

  As shown in FIG. 9, the measurement laser light 17 emitted from the laser oscillator 16 enters the reaction chamber 2 through a window 18 provided in the reaction chamber 2 and serves as a gas rectifying plate that suppresses gas turbulence. The substrate 3 placed on the placement plate 5 is irradiated through a hole 19 provided in the substrate 10. The measurement laser light 17 irradiated on the substrate 3 is reflected by the surface of the substrate 3 and reaches the light receiving element 20 through the hole 19 and the window 18.

  The method using the principle of triangulation is widely used for various applications because high-precision measurement is possible and it is easy to obtain a measuring instrument. However, the measurement requires “an optically transparent region in which laser light can reciprocate”. That is, in FIG. 9, the hole 19 and the window 18 correspond to “an optically transparent region in which laser light can reciprocate”.

  As another measuring means, for example, the “optical lever method” described in Patent Document 5 (particularly FIG. 1) and Patent Document 6 (particularly FIG. 5) can be considered.

Further, FIG. 10 is a diagram for explaining the principle of measuring the warpage state of the substrate using a conventional measuring instrument. That is, it is a method of measuring the warpage state of the substrate by making parallel laser light incident on the substrate, measuring the laser spot reflected from the substrate with a measuring instrument, and detecting the distance displacement between the laser spots. As shown in FIGS. 10A to 10C, when the distance between the parallel laser beams irradiated on the substrate is ΔX ₀ and the distance between the laser beams reflected from the substrate is ΔX _D , ΔX ₀ And the measured ΔX _D can be compared to determine the warpage state of the substrate.

Japanese Patent Laid-Open No. 2002-175992 (released on June 21, 2002) Special Table 2004-513243 Publication (Announced April 30, 2004) JP 2005-72561 A (published March 17, 2005) JP-A-10-267648 (released on October 9, 1998) JP 2007-191761 A (released on August 2, 2007) US 7,374,960 (Released on May 29, 2008, registered on May 20, 2008)

  However, triangulation using laser light as described in Patent Document 4 requires the provision of the above-mentioned “optically transparent region where laser light can reciprocate” in the flow path through which the source gas flows. In the triangulation using light, the forward path and the return path of the laser light are different, so it is necessary to provide a large window 18 in the reaction chamber 2 through which both of them can pass, and in the case of an MOCVD apparatus having the partition 10, the partition 10 needs to be provided with a large hole 19. Accordingly, since a large hole is formed in the partition wall 10 serving as a gas rectifying plate, the gas flow is disturbed, and adverse effects such as changes in gas components or viewport contamination occur.

  On the other hand, the MOCVD equipment has already mentioned that gas is used as a raw material, but it is known that the composition distribution and flow velocity distribution of the raw material gas have a large effect on the crystal characteristics, and these distributions are used as much as possible for stable production. You must not disturb.

  In addition, for example, a method of closing the hole 19 of the partition wall 10 in FIG. 9 with a transparent substance (transparent member) such as quartz, or a method of eliminating the partition wall 10 itself can be considered, but in an actual crystal growth process, It is known that an opaque film is formed on the inner surface of the partition wall 10, and even if the hole 19 is blocked with a transparent material, the transparent material becomes opaque immediately. There is a problem that the “transparent area” is lost.

  Furthermore, as shown in FIG. 9, purge gas 28 such as nitrogen gas is removed from the inside of the reaction chamber 2 so that the partition wall 10 is eliminated and the product does not adhere to the transparent member that is a component of the window 18 by the action of the raw material gas 12. A method of spraying a transparent member on the transparent member can also be considered. However, the flow of the raw material gas 12 is disturbed by the purge gas 28, and a new problem arises that adversely affects the result of crystal growth.

  Similarly to the method using the principle of triangulation, the methods described in Patent Documents 5 and 6 also need to provide “an optically transparent region in which laser light can reciprocate”, and the distance from each other. However, it is necessary to irradiate the substrate with a plurality of laser beams that are clearly defined. Further, like the method using the principle of triangulation, it is necessary to provide a large window 18 in the reaction chamber 2, and in the case of an MOCVD apparatus having the partition wall 10, it is necessary to provide a large hole 19 in the partition wall 10. There is a problem.

  Both of the above two measuring means are methods for measuring the return position of the return light of the laser light applied to the substrate, and for measuring the return position of the return light, a CCD (Charge Coupled Device). ) Or 2 (4) split light detector, PSD (Position Sensitive Detector).

  However, since these sensors basically measure light intensity, when measuring a high-temperature object such as a substrate during crystal growth, temperature radiation from the substrate acts as base noise. For this reason, the S / N ratio of the measurement signal is lowered, and there is a problem that accurate measurement becomes difficult.

  Further, as shown in FIG. 10, when the warpage state of the substrate is measured by irradiating a laser to detect the interval variation of the reflected light, fluctuation due to the source gas may occur, and the measurement error may increase. .

  Thus, although the existence of the problem of substrate warpage that occurs during crystal growth has been known so far, there has been no effective means for measuring the warpage of the substrate that occurs during crystal growth. From the subsequent results, only a method of suppressing the warpage of the substrate by trial and error has been practically performed.

  The present invention has been made to solve the above-mentioned problems, and enables measurement of the warpage of the substrate generated during crystal growth and measurement of the shape of the substrate using the Doppler effect without disturbing the flow of the source gas. It is an object of the present invention to provide an apparatus and an MOCVD apparatus equipped with the measurement apparatus.

  In order to achieve the above object, the MOCVD apparatus of the present application is a MOCVD apparatus having a reaction chamber for supplying a source gas to grow a crystal on a processing surface of a processing substrate. The wall of the reaction chamber facing the surface has at least one window that can face the central portion of the surface to be processed, and is provided on the reaction chamber, and is a movable table on which the substrate to be processed can be placed and moved And irradiating the processing surface of the substrate to be processed, which is moved by the moving table, vertically with the laser beam through the window, and receiving the laser beam reflected from the processing surface through the window. The first speed measuring means for measuring the moving speed in the normal direction with respect to the surface to be processed of the substrate to be processed using the Doppler effect, and the measurement result by the first speed measuring means is processed to process the substrate to be processed. Output shape information It is characterized in that it comprises a processing means adapted to earthenware pots.

  According to the above configuration, since the first velocity measurement means using the Doppler effect by the laser beam is used, measurement is possible even if the forward path and the return path of the laser beam coincide with each other. The size of the window formed so as to face the surface to be processed can be reduced to, for example, several mm or less (smaller than the conventional size). Therefore, in the MOCVD apparatus, in order to prevent an opaque film from adhering to, for example, a transparent member, which is a component of the window, due to the action of the source gas, a mechanism is required in which the reaction chamber side of the window is set to a purge gas atmosphere. According to the above configuration, the amount of purge gas blown from the inside of the reaction chamber to the transparent member of the window can be minimized. Therefore, the shape of the substrate to be processed can be measured without disturbing the flow of the source gas flowing in the MOCVD apparatus due to the influence of the purge gas.

  In addition, since the frequency shift, not the light intensity, is measured using the Doppler effect due to the laser beam, it is not easily affected by radiation due to the temperature of the substrate to be processed. The shape can be accurately measured.

  The MOCVD apparatus includes a partition that divides an upper space on the processing surface side of the substrate to be processed in the reaction chamber into a space on the processing substrate side and a space on the inner wall side of the reaction chamber, and the partition is formed in the reaction chamber. It is preferable to have at least one opening so that the central portion of the surface to be processed can be seen from the window of the wall.

  According to the above configuration, since the reaction chamber window and the substrate to be processed can be separated by the partition wall, the amount of the source gas that adversely affects, for example, the transparent member that is a component of the window is extremely small. When the light forward path and the return path are coincident, the size of the partition hole can be reduced to, for example, several mm or less (smaller than the conventional one). Therefore, the shape of the substrate to be processed can be measured without disturbing the flow of the source gas flowing in the MOCVD apparatus.

  The MOCVD apparatus includes a second speed measuring unit that measures a moving speed of a moving table, and the processing unit processes a measurement result by the first speed measuring unit with a measurement result by the second speed measuring unit. By doing so, it is preferable to output the shape information of the substrate to be processed.

  According to the above configuration, it is possible to eliminate the influence of the movement speed variation of the movable table on the measurement result of the shape of the substrate to be processed.

  In the MOCVD apparatus, the moving table can rotate the substrate to be processed around a rotation axis perpendicular to the surface to be processed that avoids the center of the surface to be processed of the substrate to be processed. It is preferable.

  According to the above configuration, when the source gas is introduced into the processing surface of the substrate to be processed by the MOCVD apparatus and a crystal is grown, the desired thin film is formed more stably, and the film thickness and film thickness of the thin film are increased. The composition can be made uniform.

  Preferably, the MOCVD apparatus is configured to change control parameters for controlling the operation of the apparatus based on the shape information output from the processing means.

  The control parameters preferably include, for example, a substrate temperature to be processed, a raw material gas flow rate, a raw material gas temperature, a substrate rotation speed to be processed, or a combination thereof.

  According to the above configuration, since the control parameters of the MOCVD apparatus are changed based on the shape information output from the processing means, the recovery processing is performed before an unrecoverable situation such as breakage of the target substrate occurs. Since it is possible to avoid unrecoverable damage, it is possible to reduce costs. Further, as described above, the control parameters to be changed are easy to measure, control and manage, and can perform crystal growth with good reproducibility.

  As a result, since the shape of the substrate to be processed can be measured during crystal growth, the crystal growth conditions for suppressing warpage can be controlled while measuring the amount of warpage. By finding it, it becomes possible to perform high-quality crystal growth.

  According to the present invention, since the first velocity measuring means using the Doppler effect by the laser beam is used, measurement is possible even if the forward path and the backward path of the laser beam coincide with each other. The size of the window formed facing the surface to be processed can be reduced to, for example, several mm or less. Therefore, the amount of purge gas blown from the inside of the reaction chamber to the transparent member of the window can be minimized. Therefore, the shape of the substrate to be processed can be measured without disturbing the flow of the source gas flowing in the MOCVD apparatus due to the influence of the purge gas. That is, the shape of the substrate to be processed during crystal growth, which could not be measured because the window through which the laser beam passes cannot be reduced in the prior art, can be accurately measured.

  In addition, since the frequency shift, not the light intensity, is measured using the Doppler effect due to the laser beam, it is not easily affected by radiation due to the temperature of the substrate to be processed. The shape can be accurately measured.

  Furthermore, according to the present invention, recovery can be performed before an irrecoverable situation such as damage to the substrate to be processed, so that irreparable damage to the substrate to be processed can be avoided, thereby reducing costs. be able to.

FIG. 1 is a configuration diagram showing an example of an MOCVD apparatus according to the first embodiment of the present invention. FIG. 2 is a configuration diagram showing a modification of the MOCVD apparatus according to the first embodiment of the present invention. FIG. 3 is a plan view showing a state in which the substrate to be processed is installed on the turntable in the MOCVD apparatus according to the first embodiment of the present invention. FIG. 4 is a block diagram showing an example of an MOCVD apparatus according to the second embodiment of the present invention. FIG. 5 is a block diagram showing an example of an MOCVD apparatus according to the third embodiment of the present invention. FIG. 6 is a schematic configuration diagram showing an example of a MOCVD apparatus according to the prior art. FIG. 7 is a schematic configuration diagram showing another example of the MOCVD apparatus according to the prior art. FIG. 8 is a plan view showing a state in which the substrate to be processed is installed on the turntable in the MOCVD apparatus according to the prior art. FIG. 9 is an explanatory diagram for explaining a configuration when the MOCVD apparatus according to the prior art measures the warpage of the substrate by a method using the principle of triangulation using laser light. FIG. 10 is an explanatory diagram for explaining the principle of measuring the warpage state of the substrate in the prior art.

  Hereinafter, embodiments of the present invention will be described in detail.

(1) 1st Embodiment First, with reference to FIGS. 1-3, the structure of the MOCVD apparatus in 1st Embodiment of this invention is demonstrated.

  As shown in FIG. 1 showing a schematic configuration of an MOCVD apparatus, an MOCVD apparatus 100 according to this embodiment includes a reaction apparatus that performs crystal growth on a surface to be processed of a substrate (substrate to be processed), and a measurement laser in the reaction apparatus. And a measuring device that irradiates light and measures the warpage of the substrate of the reaction apparatus during crystal growth.

  The reaction apparatus includes a reaction chamber 30 serving as a container for supplying a source gas to grow crystals on a surface to be processed of a substrate, a turntable (moving stand) 31 disposed inside the reaction chamber 30, A plurality of mounting plates 32 mounted on the upper surface, a heater 34 disposed below the rotating table 31 as a heating means, a rotating shaft 35 connected to the lower side of the rotating table 31, and a motor for driving the rotating shaft 35 36, a gas supply means 38 for supplying the source gas 38a to the inside of the reaction chamber 30 via the supply pipe 37, an exhaust means (not shown) for exhausting the inside of the reaction chamber 30, and the like. The substrate 33 is arranged on the upper surface of the mounting plate 32.

  The reaction chamber 30 is connected to an air supply port (gas blowing port) 30a that serves as an inlet for the source gas 38a necessary for crystal growth supplied from the gas supply unit 38, and an exhaust unit (not shown). An exhaust port 30b for discharging the raw material gas and the like inside 30 and a window 30c through which the measurement laser light emitted from the measurement device can be transmitted are formed. The air supply port 30 a is formed in the wall of the reaction chamber 30 facing the processing surface of the substrate 33 so that the source gas 38 a can be blown out toward the processing surface of the substrate 33.

  One end of the supply pipe 37 is connected to the gas supply means 38, and the other end is inserted into the interior of the reaction chamber 30 through the air supply port 30 a. The inserted tip is located between the upper wall of the reaction chamber 30 and the turntable 31, and serves as a gas outlet 37a. Therefore, the source gas 38 a supplied from the gas supply means 38 is supplied as a crystal film source radially from the rotation axis of the turntable 31 along the surface of the turntable 31 via the supply pipe 37. The gas after reaction (raw material gas or the like) is discharged from the reaction chamber 30 to the outside through an exhaust pipe (not shown) connected to the exhaust port 30b.

  The window 30c irradiates the surface to be processed of the substrate 33 so that the measurement laser light can irradiate the surface to be processed of the substrate 33 perpendicularly (including the case where it can be considered to be substantially vertical). It is formed on the wall of the reaction chamber 30 so as to be able to face the central portion of the surface to be processed (including the vicinity portion that can be regarded as being substantially the central portion). The exhaust port 30 b is formed on the opposite side of the air supply port 30 a when viewed from the substrate 33. The window 30c is a place where the measurement laser beam is irradiated toward the inside of the reaction chamber 30, so that a transparent substance (transparent member) such as quartz is used so that the measurement laser beam can pass therethrough. It consists of

  The heater 34 is installed below the turntable 31 as a heating means for heating the substrate 33. In the present embodiment, the heater 34 is installed in the reaction chamber 30 as the heating means. However, the present invention is not limited to this. For example, a heating means such as a heater or a coil is used to heat the reaction chamber 30 as a whole. You may install in the outer peripheral part of 30.

  In order to prevent the product (opaque film) from adhering to the reaction chamber 30 due to the action of the raw material gas 38a on the transparent member that is a component of the window 30c, a purge gas such as nitrogen gas is supplied from the inside of the reaction chamber 30. A purge device (not shown) for spraying a transparent member on the transparent member (with the inside of the reaction chamber 30 being a purge gas atmosphere) can be installed as necessary. Since the configuration of the purge device is known, its description is omitted.

  The turntable 31 is formed in a disk shape, can be rotated by a rotating shaft 35 connected to the lower side, and is installed inside the reaction chamber 30. The turntable 31 rotates at an arbitrary speed when the motor 36 drives the rotation shaft 35.

  The rotary shaft 35 is connected to the bottom center of the turntable 31. The rotating shaft 35 rotates (revolves) the substrate 33 disposed on the upper surface of the mounting plate 32 by rotating the rotating table 31 by driving a motor 36 provided at the lower end. In the present embodiment, the motor 36 provided at the lower end of the rotating shaft 35 is disposed outside the reaction chamber 30, but the present invention is not limited thereto, and may be disposed inside the reaction chamber 30. Further, the mounting plate 32 includes a rotation mechanism (not shown) so that the substrate 33 can be rotated (rotated). Therefore, the substrate 33 rotates and revolves when a crystal is grown on the surface to be processed. As a result, when the source gas 38a is introduced into the surface to be processed of the substrate 33 to grow a crystal, a desired thin film can be formed more stably, and the thickness and composition of the thin film can be made uniform. it can.

  As shown in FIG. 3, a plurality of mounting plates 32 are arranged at equal intervals on a concentric circle of the rotating table 31 on the outer peripheral portion of the upper surface of the rotating table 31, and a substrate is placed on the upper surface of each mounting plate 32. 33 is arranged. That is, a plurality of (six in the present embodiment) mounting plates 32 on which the substrates 33 are respectively installed on the turntable 31 are arranged on a constant circumference (concentric circles) at regular intervals through the gap Sp. Are listed. Therefore, when the turntable 31 is rotated, the centers 33a of the six substrates 33 follow the locus Lp.

  In addition to the case where the substrate 33 is directly disposed on the upper surface of the mounting plate 32, a substrate holder (not shown) formed of, for example, quartz or boron nitride is not directly disposed on the upper surface of the mounting plate 32. It may be arranged via. At least the surface to be processed on which the crystal 33 is grown is made of, for example, GaAs, InP, GaN, or sapphire.

  In addition, since the specific process (manufacturing method) for making a crystal grow on the to-be-processed surface of the board | substrate 33 using the MOCVD apparatus 100 is well-known, the description is abbreviate | omitted.

  As shown in FIG. 1, the measuring apparatus includes a first speed measuring means 40 for measuring a moving speed in a normal direction with respect to the surface to be processed of the substrate 33 in the reaction apparatus, and a first speed measuring means 40. And processing means 41 for processing the measurement result by the above-described processing method and outputting the shape information of the substrate 33 (information such as the warpage state). In addition, the MOCVD apparatus 100 includes control means (not shown) adapted to change control parameters for controlling the operation of the reaction apparatus based on the shape information output from the processing means 41. Yes.

  The first speed measuring means 40 is a speed measuring means using the principle of the Doppler effect by laser light. The speed measurement means using the principle of the Doppler effect by the laser light means that the object is irradiated with the measurement laser light and the return light reflected by the object is received, and the frequency of the return light depends on the speed of the object. Velocity measurement that measures the velocity of an object (in this case, the difference in velocity slightly changing between the central portion and the peripheral portion of the object depending on the warping state of the object) using the Doppler effect that shifts (changes) Means.

  The first velocity measuring means 40 transmits the return light 40b that the irradiated measurement laser light 40a passes through the window 30c and reaches the substrate 33 inside the reaction chamber 30, and is reflected by the substrate 33 and transmitted through the window 30c. Is disposed at a position where the light can be received. More specifically, the first velocity measuring means 40 is configured so that the measurement laser beam 40a is perpendicular (substantially perpendicular) to one point on the locus Lp shown in FIG. 3 (that is, the center 33a of the six substrates 33). (Including the case where it can be regarded as).

  Accordingly, when the turntable 31 is rotated, the measurement laser light 40a is sequentially irradiated to one point on the locus Lp on the processing target surface of the plurality of substrates 33, and the return light 40b is received. The warping state for each of the plurality of substrates 33 is sequentially measured as a measurement result such as speed information by the measuring means 40.

  The processing unit 41 is a unit that processes the measurement result input from the first speed measurement unit 40 and outputs the shape information (information such as the warpage state) of the substrate 33. That is, the processing means 41 integrates the measurement results such as the speed information input from the first speed measuring means 40 with time to change the position information into the shape information (warp) of the substrate 33 in the reaction apparatus. Status information) and output to the control means.

  As described above, since the first velocity measuring means 40 using the Doppler effect by the laser light is used, measurement is possible even if the optical paths (outward path and backward path) of the measurement laser light 40a and the return light 40b coincide. Therefore, the size of the window 30c formed facing the surface to be processed of the substrate 33 in the reaction chamber 30 can be reduced to, for example, several mm or less (smaller than the conventional one). Therefore, in the MOCVD apparatus 100, the amount of purge gas supplied from the purge apparatus can be minimized. Therefore, the shape of the substrate 33 can be measured without disturbing the flow of the source gas 38a flowing in the reaction apparatus due to the influence of the purge gas. Further, good crystal growth can be realized on the surface to be processed of the substrate 33.

  In addition, since the frequency shift rather than the light intensity is measured using the Doppler effect by the laser beam, it is difficult to be affected by the radiation due to the temperature of the substrate 33. Therefore, the shape of the substrate 33 is changed during crystal growth. Can be measured with high accuracy.

  In place of the MOCVD apparatus 100, as shown in FIG. 2, between the wall of the reaction chamber 30 and the surface to be processed of the substrate 30, that is, between the wall of the reaction chamber 30 and the turntable 31. It is also possible to use an MOCVD apparatus 100 ′ in which a partition wall 39 having at least one hole 39a through which the laser beam can pass is formed.

  The partition wall 39 is made of a member having low gas permeability, and is formed in parallel to the upper wall of the reaction chamber 30 and the turntable 31 (including the case where it can be considered to be substantially parallel). It arrange | positions so that the space inside 30 may be separated up and down. That is, the partition 39 divides the upper space on the processing surface side of the substrate 33 into a space on the substrate 33 side and a space on the inner wall side of the reaction chamber 30.

  Further, the hole 39a is located at a position corresponding to the window 30c of the reaction chamber 30, that is, the central portion of the processing surface of the substrate 33 from the window 30c so that the measurement laser beam 40a and the return beam 40b can be transmitted. It is formed at a position where it can face. Further, the gas blowing port 37 a is disposed between the partition wall 39 and the turntable 31. Therefore, the raw material gas 38 a supplied from the gas supply means 38 radiates along the surface of the turntable 31 from the rotation axis of the turntable 31 via the supply pipe 37 between the partition wall 39 and the turntable 31. And supplied as a raw material for the crystal film.

  In the above configuration, the size of the hole 39a of the partition wall 39 can be reduced to, for example, several mm or less (smaller than the conventional size). Therefore, in the MOCVD apparatus 100 ′, the amount of purge gas supplied from the purge apparatus can be minimized. Therefore, the shape of the substrate 33 can be measured without disturbing the flow of the source gas 38a flowing in the reaction apparatus due to the influence of the purge gas. Further, good crystal growth can be realized on the surface to be processed of the substrate 33.

(2) Second Embodiment Next, the configuration of the MOCVD apparatus 200 in the second embodiment of the present invention will be described with reference to FIG. Here, since the reaction apparatus of the MOCVD apparatus 200 has basically the same configuration as the reaction apparatus of the MOCVD apparatus 100 ′ in the first embodiment, a description thereof will be omitted.

  As shown in FIG. 4, the measuring apparatus of the MOCVD apparatus 200 according to the present embodiment is a first speed measuring means 40 for measuring the moving speed in the normal direction with respect to the surface to be processed of the substrate 33 in the reaction apparatus. A second speed measuring means 42 for measuring the rotation (movement) speed of the rotating shaft 35, and a processing method in which measurement results by the first speed measuring means 40 and the second speed measuring means 42 are set in advance. And processing means 41 for outputting the shape information of the substrate 33 (information such as the warpage state). Further, the MOCVD apparatus 200 includes control means (not shown) adapted to change control parameters for controlling the operation of the reaction apparatus based on the shape information output from the processing means 41. Yes. The second speed measuring means 42 can be installed at an arbitrary position on the rotary shaft 35 or the rotary base 31.

  The second speed measuring means 42 is installed to measure a slight fluctuation in the rotational speed of the turntable 31. That is, when the rotary table 31 is rotated by the rotation of the rotary shaft 35, a slight rotational fluctuation occurs in the rotary base 31, and this rotational fluctuation is the rotational speed of the substrate 33 disposed on the rotary base 31. It has some influence on the measurement. Accordingly, when the processing means 41 obtains the shape information (warp state information, etc.) of the substrate 33, the measurement result of the rotational fluctuation of the turntable 31 by the second speed measurement means 42 is also taken into consideration, so that the turntable 31 It is possible to avoid measurement errors caused by fluctuations in rotation and to perform accurate measurement.

  In the present embodiment, a preset processing method performed by the processing unit 41 includes a process of dividing the measurement result by the first speed measurement unit 40 by the measurement result by the second speed measurement unit 42. That is, the processing unit 41 calculates the measurement data by dividing the measurement result such as the speed information input from the first speed measurement unit 40 by the rotation fluctuation measurement result input from the second speed measurement unit 42. After that, the measurement data is time-integrated and changed to position information, thereby obtaining shape information (information such as a warpage state) of each substrate 33 in the reaction apparatus and outputting it to the control means.

  The second speed measuring means may be configured by a combination of a rotation angle measuring means such as an encoder and a differential processing means for differentiating the data input from the rotation angle measuring means with respect to time. Further, the differential processing means may be provided in the processing means 41 instead of being provided in the second speed measurement means.

  According to the above configuration, it is possible to eliminate the influence of the rotation variation of the turntable 31 on the measurement result of the shape of the substrate 33, and therefore it is possible to perform highly accurate measurement.

(3) Third Embodiment Next, the configuration of an MOCVD apparatus 300 according to a third embodiment of the present invention will be described with reference to FIG. Here, the reaction apparatus of the MOCVD apparatus 300 has basically the same configuration as the reaction apparatus of the MOCVD apparatus 200 in the second embodiment, and thus the description thereof is omitted.

  As shown in FIG. 5, the measurement apparatus of the MOCVD apparatus 300 according to the present embodiment is a control parameter for controlling the operation of the reaction apparatus based on the shape information (signal) of the substrate 33 input from the processing means 41. The control means 43 which changes 43a is provided. The control means 43 controls the reaction apparatus via the gas supply means 38, the heater 34, the motor 36, and the like.

  The control parameter 43 a is stored in the control means 43. Examples of the control parameter 43a include a substrate temperature, a raw material gas flow rate, a raw material gas temperature, a substrate rotational speed, or a combination thereof. These control parameters 43a are easy to measure, control, and manage, and therefore can perform crystal growth with good reproducibility.

  The type and number of the control parameters 43a are determined as appropriate in consideration of the influence on the crystal growth, factors causing the warp state of the substrate, various timings such as the supply of the source gas, etc. In the present embodiment, the control parameters 43a The case where is the substrate temperature and the raw material gas flow rate will be described as an example. In this case, the amount of warpage of the substrate can be controlled by the balance between the substrate cooling effect by the source gas and the substrate heating effect by the heater. Therefore, before the amount of warpage of the substrate causes an unrecoverable situation such as breakage of the substrate, the substrate can be cooled by the source gas, and recovery can be performed.

  That is, the measurement apparatus of the MOCVD apparatus 300 uses the processing information 41 to process the shape information (signal) of the substrate 33 obtained by processing the measurement results input from the first speed measurement means 40 and the second speed measurement means 42. Input to the control means 43, and the control parameter 43a in the control means 43 is changed in accordance with the input signal. Based on the changed control parameter 43a, the control unit 43 adjusts the substrate temperature and the raw material gas flow rate to control the reaction apparatus, and as a result, can control the warpage amount of the substrate 33. ing.

  That is, according to the above configuration, the degree of warpage (the shape of the substrate) of the substrate 33 can be measured by the changed control parameter 43a during the crystal growth, so that it is not possible to recover from damage to the substrate. Since recovery measures can be taken before a possible situation occurs, irreparable damage to the substrate can be avoided, thereby reducing costs. In addition, crystal growth conditions for suppressing warpage of the substrate can be controlled while measuring the amount of warpage, and high quality crystal growth can be performed by finding appropriate conditions.

  Since the first speed measurement means 40 in the measurement apparatus according to the first to third embodiments is a speed measurement means using the Doppler effect by the laser light, the optical path of the measurement laser light 40a irradiated on the substrate 33 and Even if the optical path of the return light 40b from the substrate 33 coincides with the optical path, it can be measured. For this reason, in the reaction apparatus, the size of the window 30c and the hole 39a that need to be provided in the optical path through which the laser light passes can be made extremely small (less than several mm). Specifically, for example, the diameter of the window 30c can be about 30 mm, and the diameter of the hole 39a can be about 1 mm. Of course, the size of the window 30c and the hole 39a is not limited to this value, and appropriate values are selected according to the design of the reactor.

  Therefore, since the size of the window 30c and the hole 39a can be reduced (smaller than the conventional size), the amount of purge gas supplied from the purge device can be minimized. Therefore, the shape of the substrate 33 can be measured without disturbing the flow of the source gas 38a flowing in the reaction apparatus due to the influence of the purge gas. Further, good crystal growth can be realized on the surface to be processed of the substrate 33.

  Moreover, in the said 1st-3rd embodiment, although measuring the shape of the board | substrate when the board | substrate 33 which is a to-be-processed substrate exists in a rotation (spinning and revolution) state was demonstrated as an example, the board | substrate 33 is, for example Even when crystal growth is realized by performing movement other than rotation together with the turntable (moving table) 31, the shape of the substrate can be measured by the MOCVD apparatus according to the present invention.

  The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope shown in the claims, and embodiments obtained by appropriately combining technical means disclosed in different embodiments. Is also included in the technical scope of the present invention.

  The present invention can be suitably applied to an MOCVD apparatus for crystal growth using a gas on a substrate such as a semiconductor wafer.

30 reaction chamber 30a air supply port 30b exhaust port 30c window 31 turntable (moving table)
32 Mounting plate 33 Substrate (substrate to be processed)
34 heater 35 rotating shaft 36 motor 37 supply pipe 38 gas supply means 38a raw material gas 39 partition wall 39a hole 40 first speed measurement means 41 processing means 42 second speed measurement means 43 control means 43a control parameters 100, 100 ', 200,300 MOCVD equipment

Claims (6)

In an MOCVD apparatus equipped with a reaction chamber for supplying a source gas to grow a crystal on a surface to be processed of a substrate to be processed,
The wall of the reaction chamber facing the surface to be processed of the substrate to be processed has at least one window that can face the center of the surface to be processed.
A moving table provided in the reaction chamber, on which a substrate to be processed can be placed and moved;
The surface to be processed of the substrate to be processed that is moved by the moving table is vertically irradiated with laser light through the window, and the laser light reflected from the surface to be processed is received through the window, and Doppler is received. First speed measuring means for measuring a moving speed in a normal direction with respect to the processing surface of the substrate to be processed using the effect;
A MOCVD apparatus comprising: a processing unit configured to process a measurement result of the first speed measuring unit and output shape information of a substrate to be processed. A partition that divides the upper space on the processing surface side of the substrate to be processed in the reaction chamber into a space on the processing substrate side and a space on the inner wall side of the reaction chamber;
2. The MOCVD apparatus according to claim 1, wherein the partition wall has at least one opening so that a central portion of the surface to be processed can be seen from a window on a wall of the reaction chamber. A second speed measuring means for measuring the moving speed of the moving table;
The processing means outputs the shape information of the substrate to be processed by processing the measurement result by the first speed measurement means with the measurement result by the second speed measurement means. The MOCVD apparatus according to claim 1 or 2.   The moving table is characterized in that the substrate to be processed can be rotated about a rotation axis perpendicular to the surface to be processed avoiding the central portion of the surface to be processed of the substrate to be processed. The MOCVD apparatus according to claim 1, 2, or 3.   5. The control device according to claim 1, further comprising a control unit configured to change a control parameter for controlling operation of the apparatus based on the shape information output from the processing unit. The MOCVD apparatus described in 1.   6. The MOCVD apparatus according to claim 5, wherein the control parameter includes a substrate temperature to be processed, a raw material gas flow rate, a raw material gas temperature, a rotational speed of the substrate to be processed, or a combination thereof.

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