JP2019182713A - MONITORING METHOD FOR MANUFACTURING DEVICE FOR SiC SINGLE CRYSTAL - Google Patents

Abstract

To provide a monitoring method for a manufacturing device for an SiC single crystal that can detect a seed crystal and an SiC solution being stuck.SOLUTION: There is provided a manufacturing device 10 for SiC single crystal that comprises: an outer crucible 1 which rotates at a first rotating speed V1 while supported rotatably by a lower shaft; an inner crucible 2 which holds an SiC solution while held rotatably inside the outer crucible 1; a lid 3 which closes an opening part 2a of the inner crucible 2; and an upper shaft which holds and rotates a seed crystal at a second rotating speed V2 different from the first rotating speed V1 while penetrating the lid 3, where the lid 3 comprises a cut part 3c, a light emitting element 61 and a light receiving element 62 are arranged across the lid 3. and the rotating speed of the lid 3 is momentarily measured by emitting light L1 from the light emitting element 61 and letting the light receiving element 62 receive the emitted light L1 so as to determine abnormality based upon variation in the measured rotating speed.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a method for monitoring a SiC single crystal production apparatus.

  Patent Document 1 discloses a method for producing an SiC crystal using a solution growth method. Specifically, a seed crystal is provided at the tip of the rotating shaft, and while rotating the rotating shaft, the seed crystal and the SiC solution are brought into contact with each other to grow a crystal on the seed crystal.

Japanese Patent Laid-Open No. 2015-110497

  In such a SiC crystal manufacturing method, the seed crystal and the SiC solution may be fixed during the growth of the SiC crystal. If such sticking occurs, the shaft of the production apparatus is damaged, or the SiC solution overflows from the crucible, which affects the production of crystals, which is not preferable.

  This invention shall detect that a seed crystal and a SiC solution adhere.

The method for monitoring a SiC single crystal production apparatus according to the present invention is as follows:
An outer crucible rotating at a first rotation speed while being rotatably supported by the lower shaft;
An inner crucible for holding the SiC solution while being rotatably held inside the outer crucible;
A lid that closes the opening of the inner crucible;
A monitoring method for monitoring a SiC single crystal manufacturing apparatus comprising: an upper shaft that holds a seed crystal so as to rotate at a second rotation speed different from the first rotation speed while passing through the lid. ,
The lid includes a notch,
The light emitting element and the light receiving element are arranged so as to sandwich the lid,
By emitting light from the light emitting element and causing the light receiving element to receive the emitted light, the rotational speed of the lid is measured every moment, and abnormality is determined based on the change in the measured rotational speed.

  According to such a configuration, when the seed crystal and the SiC solution are not fixed, the lid is integrated with the outer crucible and the inner crucible and rotates at the first rotation speed. On the other hand, when the seed crystal and the SiC solution are fixed, the lid rotates at the second rotation speed integrally with the upper shaft, the seed crystal, the SiC solution, and the inner crucible. Since the second rotation speed is different from the first rotation speed, the rotation speed of the lid changes. In response to this, it is possible to detect whether or not the seed crystal and the SiC solution are fixed.

  The present invention can detect that the seed crystal and the SiC solution are fixed.

1 is a perspective view of a SiC single crystal manufacturing apparatus according to Embodiment 1. FIG. 1 is a cross-sectional view of a SiC single crystal manufacturing apparatus according to a first embodiment. 3 is a top view of the SiC single crystal manufacturing apparatus according to the first embodiment. FIG. FIG. 3 is a schematic diagram showing an operation example of the SiC single crystal manufacturing apparatus according to the first embodiment.

  Hereinafter, specific embodiments to which the present invention is applied will be described in detail with reference to the drawings. However, the present invention is not limited to the following embodiments. In addition, for clarity of explanation, the following description and drawings are simplified as appropriate.

(Embodiment 1)
The SiC single crystal manufacturing apparatus according to the first embodiment will be described with reference to FIGS. 1 is a perspective view of a SiC single crystal manufacturing apparatus according to Embodiment 1. FIG. FIG. 2 is a cross-sectional view of the SiC single crystal manufacturing apparatus according to the first embodiment. FIG. 3 is a top view of the SiC single crystal manufacturing apparatus according to the first embodiment. As a matter of course, the right-handed XYZ coordinates shown in FIG. 1 and other drawings are convenient for explaining the positional relationship of the constituent elements. Usually, the Z-axis plus direction is vertically upward, and the XY plane is a horizontal plane, which is common between the drawings.

  As shown in FIG. 1, the SiC single crystal manufacturing apparatus 10 includes an outer crucible 1, an inner crucible 2, a lid 3, a lower shaft 4, an upper shaft 5, a transmission sensor 6, a seed crystal 7, And a measurement control unit 8.

  The outer crucible 1 is rotatably supported by the lower shaft 4. The outer crucible 1 holds the inner crucible 2. Specifically, the inner crucible 2 is fitted into the outer crucible 1. Therefore, the inner crucible 2 and the outer crucible 1 can rotate around a vertical line (here, a virtual line along the Z axis).

  As shown in FIGS. 1 and 2, the inner crucible 2 holds an SiC solution S1. The inner crucible 2 includes an opening 2a that opens upward. In addition, since SiC solution S1 is high temperature, for example, 2000 degreeC, when crystal-growing SiC, it is difficult for the user of the manufacturing apparatus 10, etc. to observe the inner side of the inner crucible 2 visually.

  As shown in FIGS. 1 to 3, the lid 3 is, for example, a disk-shaped body 3 a, and the disk-shaped body 3 a includes a center hole 3 b and a notch 3 c. The lid 3 is detachably disposed in the opening 2a of the inner crucible 2 and closes the opening 2a. The center hole 3b is provided at the center of the disk-shaped body 3a and penetrates the disk-shaped body 3a. The notch 3c is provided on the outer edge side from the center hole 3b in the disc-like body 3a.

  The lower shaft 4 extends from the lower side of the outer crucible 1 (here, the Z-axis minus side) toward the outer crucible 1 on a vertical line (here, a virtual line parallel to the Z-axis). An end of the lower shaft 4 on the outer crucible 1 side supports the outer crucible 1. The lower shaft 4 is supplied with a driving force from a driving source (not shown) such as a motor and can rotate around the shaft at a first rotational speed V1. The outer crucible 1 can be rotated by the lower shaft 4 at the first rotation speed V1.

  The upper shaft 5 extends on a vertical line (here, a virtual line parallel to the Z axis) toward the SiC solution S1 held in the inner crucible 2. The upper end of the upper shaft 5 (here, the z-axis plus side) is attached to the actuator so that the upper shaft 5 approaches or separates from the SiC solution S1 along the vertical line. Can be moved to. The end of the upper shaft 5 on the SiC solution S1 side holds the seed crystal 7. The upper shaft 5 is supplied with a driving force from a driving source (not shown) such as a motor and can rotate around the shaft at a second rotational speed V2. The second rotation speed V2 may be different from the first rotation speed V1, and is faster than, for example, the first rotation speed V1. The seed crystal 7 can be rotated by the upper shaft 5 at the second rotation speed V2.

  The transmission sensor 6 includes a light emitting element 61 and a light receiving element 62. The light emitting element 61 and the light receiving element 62 are disposed so as to sandwich the lid 3. The light emitting element 61 emits light L1 in a direction crossing the upper axis 5 (here, a direction along the x axis). The light L <b> 1 passes through the notch 3 c of the lid 3 or is blocked by the disk-shaped body 3 a of the lid 3 according to the rotation angle around the upper axis 5 of the lid 3. In the example illustrated in FIGS. 1 to 3, the light L <b> 1 passes through the notch 3 c of the lid 3 and further enters the light receiving element 62.

  The seed crystal 7 is, for example, a substantially disk-shaped body. The seed crystal 7 is brought into contact with the SiC solution S1 to grow a crystal.

  The measurement control unit 8 has, as a hardware configuration, a storage device having, for example, an arithmetic circuit having a CPU (Central Processing Unit), a program memory, a data memory, other RAM (Random Access Memory), a ROM (Read Only Memory), and the like. Etc. may be provided. The measurement control unit 8 acquires data from each component of the SiC single crystal manufacturing apparatus 10 and calculates various data by an arithmetic circuit in accordance with a program stored in the storage device. The measurement control unit 8 may instruct each component of the SiC single crystal manufacturing apparatus 10 according to the calculation result.

  The measurement control unit 8 is electrically connected to the transmission sensor 6 and acquires a signal indicating light reception of the light L1 every moment. The measurement control unit 8 obtains the rotational speed of the lid 3 every moment based on the interval at which the light receiving element 62 detects the light L1.

  The measurement control unit 8 determines that the seed crystal 7 and the SiC solution S1 are not fixed if the calculated rotation speed is a value within a predetermined range at or near the first rotation speed V1. In other words, in such a case, the measurement control unit 8 determines that the operation of the SiC single crystal manufacturing apparatus 10 is normal.

  The measurement control unit 8 determines that the seed crystal 7 and the SiC solution S1 are fixed if the calculated rotation speed is a value within a predetermined range at or near the second rotation speed V2. In other words, in such a case, the measurement control unit 8 determines that the operation of the SiC single crystal manufacturing apparatus 10 is abnormal. Furthermore, the measurement control unit 8 may instruct the drive source described above to stop the rotation of the lower shaft 4 and the upper shaft 5 in an emergency manner. In addition, the measurement control unit 8 may cause a display device (not shown), a sound output device (not shown), or the like to notify the user of the SiC single crystal manufacturing apparatus 10 of the abnormality.

(Monitoring method)
With reference to FIG. 4, the monitoring method of the SiC single crystal manufacturing apparatus according to the first embodiment will be described. A monitoring method will be described as an operation example of the SiC single crystal manufacturing apparatus according to the first embodiment. FIG. 4 is a schematic diagram showing an operation example of the SiC single crystal manufacturing apparatus according to the first embodiment.

  As shown in FIG. 4, the SiC single crystal manufacturing apparatus 10 brings the upper shaft 5 closer to the SiC solution S1 side and brings the seed crystal 7 into contact with the SiC solution S1 (seed crystal transfer step ST1).

  Subsequently, while the seed crystal 7 is in contact with the SiC solution S1, the lower shaft 4 is rotated around the axis at the first rotational speed V1 while the upper shaft 5 is rotated around the axis at the second rotational speed V2. (Crystal growth step ST2). As described above, the inner crucible 2 is disposed inside the outer crucible 1, and the lid 3 is disposed in the opening 2 a of the inner crucible 2. Therefore, the inner crucible 2 and the lid 3 rotate at the first rotation speed V1 as the outer crucible 1 rotates.

  Here, the light L <b> 1 is emitted from the light emitting element 61 and is received by the light receiving element 62. The light L <b> 1 passes through the notch 3 c of the lid 3 or is blocked by the disk-shaped body 3 a of the lid 3 according to the rotation angle around the upper axis 5 of the lid 3. The measurement control unit 8 obtains the rotational speed of the lid 3 every moment based on the interval at which the light receiving element 62 detects the light L1.

  By the way, in the crystal growth step ST2, crystal fixation in which the seed crystal 7 and the SiC solution S1 are fixed may occur (crystal fixation step ST3). For example, the temperature is lowered and the SiC solution S1 is locally hardened. When such crystal fixation occurs, the rotation of the upper shaft 5 is transmitted to the inner crucible 2 and the lid 3 through the seed crystal 7 and the SiC solution S1. Therefore, the inner crucible 2 and the lid 3 rotate at the second rotation speed V <b> 2 that is the same as the rotation speed of the upper shaft 5.

  Subsequently, the measurement control unit 8 obtains the rotation speed of the lid 3 every moment based on the interval at which the light receiving element 62 detects the light L1. Then, the rotation speed of the lid 3 was the first rotation speed V1 in the crystal growth step ST2, but changed to the second rotation speed V2 in the crystal fixing step ST3. By the change in the rotation speed of the lid 3, it is possible to detect adhesion between the seed crystal 7 and the SiC solution S1.

Here, Table 1 shows an example of the rotational speed of each component of the SiC single crystal manufacturing apparatus 10 in each step.

  In the example shown in Table 1, it can be detected that the rotation speed of the lid 3 is 3 rpm in the crystal growth step ST2, but has changed to 5 rpm in the crystal fixing step ST3.

  After determining that an abnormality has occurred, the operations of the upper shaft 5 and the lower shaft 4 may be stopped. Moreover, you may notify the user of the SiC single crystal manufacturing apparatus 10 of the abnormality using a display apparatus (not shown), an audio | voice output apparatus (not shown), etc. Thereby, the user can know the abnormality of the SiC single crystal manufacturing apparatus 10 and can monitor the SiC single crystal manufacturing apparatus 10.

  Note that the present invention is not limited to the above-described embodiment, and can be changed as appropriate without departing from the spirit of the present invention.

DESCRIPTION OF SYMBOLS 10 SiC single crystal manufacturing apparatus 1 Outer crucible 2 Inner crucible 2a Opening part 3 Cover 3a Disk-shaped body 3b Center hole 3c Notch part 4 Lower axis 5 Upper axis 6 Transmission sensor 61 Light emitting element 62 Light receiving element 7 Seed crystal 8 Measurement control Part L1 Light S1 SiC solution ST1 Seed crystal transfer step ST2 Crystal growth step ST3 Crystal fixing step V1, V2 Rotational speed

Claims (1)

An outer crucible rotating at a first rotation speed while being rotatably supported by the lower shaft;
An inner crucible for holding the SiC solution while being rotatably held inside the outer crucible;
A lid that closes the opening of the inner crucible;
A monitoring method for monitoring a SiC single crystal manufacturing apparatus comprising: an upper shaft that holds a seed crystal so as to rotate at a second rotation speed different from the first rotation speed while passing through the lid. ,
The lid includes a notch,
The light emitting element and the light receiving element are arranged so as to sandwich the lid,
By emitting light from the light emitting element, and by causing the light receiving element to receive the emitted light, measure the rotational speed of the lid from moment to moment, and determine abnormality based on the change in the measured rotational speed.
A method for monitoring an apparatus for producing a SiC single crystal.

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