JP2009155162A - Fusing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a solid source material fusing device that can stably and continuously supply a melt source to a main crucible of a crystal manufacturing device for manufacturing a semiconductor crystal such as silicon. <P>SOLUTION: The fusing device 1 comprises a solid source supply means 10, a detecting means 14, a control means 15, a sub crucible 21, a heating means 23 and a melt guiding means 25, wherein the detecting means 14 detects a solid source material 2 in an unfused state floating on the surface of a melt source 3 reserved in the sub crucible 21. When the control means 15 judges that the solid source larger than a predetermined amount floats on the melt surface based on a detection result outputted from the detecting means 14, the control means 15 stops the operation of the solid source supply means 10 of supplying the solid source 2 to the sub crucible 21. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a melting apparatus used for heating and melting a supplied solid raw material.

  Semiconductor crystal materials such as silicon are widely used as semiconductor device materials such as IC and LSI.

  Various apparatuses for supplying a solid material or a melt material as needed to a crucible in which a crystal body is manufactured have been proposed in order to continuously manufacture a crystal body in a crystal manufacturing apparatus. In order to continuously produce large-diameter and long-sized crystals, depending on the growth capacity of the crystals pulled up from the crucible, the granular silicon which is a solid material is directed toward the melt material stored in the crucible. An apparatus to be supplied is disclosed in Patent Document 1, for example.

  In the apparatus disclosed in Patent Document 1, a partition wall is arranged in the crucible to divide the melt raw material into inner and outer regions in a state where the melt surface is communicated below the liquid surface. Further, a scattering prevention plate for preventing the melt raw material from scattering from the outer region of the crucible is provided on the partition wall. A raw material supply pipe and a raw material introduction jig for guiding the solid raw material to the crucible are arranged above the crucible. Here, in the apparatus disclosed in Patent Document 1, the solid raw material supplied to the crucible is granular silicon produced by growing granular silicon species by exposure to silane gas or the like.

  When producing a crystal with the apparatus disclosed in Patent Document 1, with the crucible and the seed crystal rotated, the seed crystal is immersed in the melt in the inner region in the crucible divided by the partition wall, and then pulled up. Do. At this time, according to the growth capacity of the crystal pulled up from the crucible, the granular silicon, which is a solid raw material, is divided by the partition through the raw material supply pipe and the raw material introduction jig having a pipe connected to the funnel. Supplied to the inner outer region. The supplied granular silicon solid raw material is melted in a crucible to become a melt, and becomes a melt raw material for producing a crystal. In such an apparatus disclosed in Patent Document 1, it is possible to continuously produce a crystal by supplying a molten silicon raw material stored in a crucible and melting it at any time. It is.

  However, in the apparatus disclosed in Patent Document 1, the solid raw material supplied toward the melt raw material is granular silicon that is produced by exposing granular silicon species to silane gas or the like. Granular silicon is expensive compared to polycrystalline silicon rods produced by the Siemens process. A polycrystalline silicon rod produced by the Siemens method is cleaved to form a bulk silicon raw material, which is used as a solid raw material supplied toward the melt raw material. The polycrystalline silicon rod can be formed into a granular shape by increasing the number of times of cleavage, but the cost is increased due to an increase in the number of steps for cleaving and cleaning the obtained solid raw material. Therefore, in order to reduce costs, it is necessary to use large-sized lump silicon produced with a minimum number of cleavages as a solid material.

  In the apparatus disclosed in Patent Document 1, when large-sized lump silicon is used as a solid material, the lump silicon is supplied toward the melt material through a material supply pipe and a material introduction jig. Therefore, the supply position at which the bulk silicon is supplied toward the raw material supply pipe is higher than the melt surface of the melt raw material to which the bulk silicon is supplied, compared to the case where the raw material supply pipe is not used. Since the potential energy of the bulk silicon at the supply position is larger than when the raw material supply pipe is not used, a large amount and intense splash may occur when the bulk silicon falls on the melt surface of the melt raw material. . If this large amount of splash adheres to the anti-scattering plate provided on the partition wall in the crucible, the anti-scattering plate may be cracked or chipped due to the difference in thermal expansion coefficient between silicon and the anti-scattering plate. .

  Furthermore, if a large amount of splash adheres to the lower end of the raw material supply pipe and closes the opening of the raw material supply pipe, the bulk silicon may not be supplied toward the melt surface.

  Further, when large-sized lump silicon is supplied toward the raw material supply pipe, the inner diameter of the raw material supply pipe is set so that the lump silicon does not form a bridge inside the raw material supply pipe. It is necessary to design about 3 times the size of one lump silicon. In the raw material supply pipe having such a designed pipe inner diameter, the installation area of the raw material supply pipe is increased and the cost is increased. Furthermore, since a large amount of splash adheres to the raw material supply pipe as described above, it is necessary to frequently replace the raw material supply pipe, and the running cost increases.

  In the apparatus disclosed in Patent Document 2, baffle plates are fixed inside the supply pipe for supplying the solid raw material toward the melt surface, for example, alternately at regular intervals, in a state of being inclined downward. Yes. In such an apparatus disclosed in Patent Document 2, when the solid material is supplied toward the melt surface, the falling speed of the solid material passing through the supply pipe is lowered by the baffle plate arranged in the supply pipe. . Therefore, even when a large-sized massive solid material is supplied toward the melt surface, the occurrence of splash can be suppressed.

  In addition, a large-sized solid solid material is difficult to melt because it has a smaller surface area per unit weight than a granular solid material. Therefore, the solid raw material supplied toward the melt surface may float on the melt surface in an unmelted state. If an excessive amount of solid material exceeding the melting capacity is additionally supplied in a state where the unmelted solid material floats more than a predetermined amount on the melt surface, the progress of melting of the solid material may stop.

  The apparatus disclosed in Patent Document 3 is provided with a sampling chamber for collecting a melt raw material so that the state of the melt raw material can be observed. In addition, the apparatus disclosed in Patent Document 4 is provided with a viewing window through which the molten state of the melt raw material in the crucible can be observed.

Japanese Patent Laid-Open No. 2-9790 JP-A-1-119594 JP-A-7-180968 Japanese Utility Model Publication No. 7-22397

  In the devices disclosed in Patent Literature 3 and Patent Literature 4, an operator visually observes the state of the melt raw material to determine whether or not the solid raw material is floating on the melt surface. Then, when the operator determines that the unmelted solid material is floating more than a predetermined amount on the melt surface, the worker stops supplying the solid material. As described above, in the apparatuses disclosed in Patent Document 3 and Patent Document 4, the operator is forced to perform troublesome operations. In addition, for example, when arranging a viewing window, depending on the configuration of the apparatus, it may be difficult to arrange the viewing window at a position where the state of the melt surface can be observed throughout. Insufficient to observe. Therefore, in the state where the unmelted solid material floats on the surface of the melt for a predetermined amount or more, excess solid material exceeding the melting capacity is additionally supplied, and the progress of melting of the solid material is stopped. . Thus, when the progress of melting of the solid raw material is stopped, the solid raw material cannot be supplied at any time, and the crystal cannot be continuously produced.

  Therefore, an object of the present invention is to provide a melting apparatus that melts the supplied solid material, and can determine whether the solid material is floating on the surface of the melt without forcing the operator to perform troublesome operations. Is to provide a device. In addition, it is possible to prevent excessive solid materials exceeding the melting capacity from being supplied, to prevent the progress of melting of solid materials from stopping, and to supply solid materials as needed to continuously melt solid materials. It is to provide a viable melting device.

The present invention is a melting apparatus used for heating and melting a supplied solid raw material,
A crucible for storing a melt obtained by melting a solid raw material;
Heating means for heating the crucible;
Arranged vertically above the opening of the crucible, a discharge port is formed at the lower end in the vertical direction, and an input port is formed at the upper end in the vertical direction at a position shifted in the horizontal direction from the discharge port, A solid raw material supply means for supplying a solid raw material to the crucible, having a guide portion that is formed in an inclined surface that is connected to the discharge port in a horizontal direction as it proceeds vertically downward from the input port;
A melting apparatus comprising: a detecting unit that detects that an unmelted solid raw material is floating on a surface of a melt stored in the crucible.

  According to the present invention, the detecting means detects heat radiated from the surface of the melt stored in the crucible to detect that an unmelted solid material is floating on the melt surface. It is comprised by this.

  According to the present invention, the detecting means measures the temperature of at least one of the positions above the surface of the melt stored in the crucible and below the inlet, and is stored in the crucible. It is characterized by detecting heat radiated from the surface of the melt and detecting that an unmelted solid material is floating on the surface of the melt.

  Further, the present invention is configured such that the detection means detects the brightness of the surface of the melt stored in the crucible and detects that an unmelted solid material is floating on the melt surface. It is characterized by that.

  Further, the present invention compares the detection result output from the detection means with a predetermined output value, and the detection result output from the detection means is within a range set based on the predetermined output value. When there is not, it is characterized by having a control means for judging that more than a predetermined amount of the solid raw material is floating on the melt surface and stopping the operation of supplying the solid raw material to the crucible of the solid raw material supply means.

  In the present invention, the control means determines that more than a predetermined amount of solid material is floating on the melt surface based on a detection result output from the detection means after a predetermined detection start time has elapsed. The solid raw material supply means stops the supply operation of the solid raw material to the crucible.

  In the present invention, the detection start time is set to be equal to or longer than the melting capacity calculation time calculated from the supply amount of the solid raw material supply means supplying the solid raw material to the crucible at a time and the heating capacity of the heating means. It is characterized by that.

  Further, in the present invention, when the control unit determines that more than a predetermined amount of the solid material is floating on the melt surface based on the detection result output from the detection unit, the control unit displays a warning and the solid The solid raw material supply operation to the crucible of the raw material supply means is stopped.

  In the present invention, when the control means determines that more than a predetermined amount of the solid raw material is not floating on the melt surface based on the detection result output from the detection means, the crucible of the solid raw material supply means The solid raw material supply operation is resumed.

  According to the present invention, the detection means detects that an unmelted solid material is floating on the surface of the melt stored in the crucible. Therefore, it is possible to determine whether or not the solid raw material is floating on the melt surface without forcing the operator to perform troublesome operations.

  According to the invention, the detection means detects heat radiated from the surface of the melt stored in the crucible. If an unmelted solid raw material floats on the melt surface, the solid raw material blocks heat radiated from the melt surface. Therefore, when the detection means detects the heat radiated from the melt surface, it is possible to detect that an unmelted solid material is floating on the melt surface.

  According to the invention, the detecting means measures the temperature of at least one position among positions above the surface of the melt stored in the crucible and below the inlet. Therefore, the detection means can detect the heat radiated from the surface of the melt stored in the crucible. Therefore, the detection means can detect that the unmelted solid material is floating on the melt surface.

  According to the invention, the detection means detects the brightness of the surface of the melt stored in the crucible. Since the brightness of the melt is different from that of the solid material, the detection means can detect that the unmelted solid material is floating on the surface of the melt by detecting the brightness of the surface of the melt.

  According to the invention, the control means compares the detection result output from the detection means with a predetermined output value, and the detection result output from the detection means is set based on the predetermined output value. If it is not within the range, if it is determined that more than a predetermined amount of the solid material is floating on the surface of the melt, the operation of supplying the solid material to the crucible of the solid material supply means is stopped. Therefore, it is possible to prevent the solid raw material from being supplied in a state where a larger amount of the solid raw material floats on the surface of the melt, and to prevent the progress of melting of the solid raw material from stopping. Therefore, it is possible to continuously melt the solid material by supplying the solid material to the crucible as needed.

  According to the invention, the control means determines that more than a predetermined amount of the solid material is floating on the melt surface based on the detection result output from the detection means after the predetermined detection start time has elapsed. The solid raw material supply operation to the crucible of the solid raw material supply means is stopped. Therefore, the malfunction of the control means due to the influence of the transient state immediately after the solid raw material is supplied into the crucible can be prevented.

  According to the invention, the detection start time is set to be equal to or longer than the melting capacity calculation time calculated from the supply amount of the solid raw material supply means supplying the solid raw material to the crucible at a time and the heating capacity of the heating means. . Therefore, after the detection start time, since the solid material supplied to the crucible is already melted in a normal state, the control means reliably detects an abnormal state and stops the supply operation of the solid raw material to the crucible. It is possible to prevent the solid raw material from being supplied in a state where a larger amount of the solid raw material floats on the surface of the melt.

  Further, according to the present invention, when the control means determines that more than a predetermined amount of the solid raw material is floating on the melt surface based on the detection result output from the detection means, the control means displays a warning and displays the solid raw material. The supply operation of the solid raw material to the crucible of the supply means is stopped. Thus, by displaying the warning, the operator can take a measure such as forcibly removing the solid material floating on the melt surface based on the warning display.

  Further, according to the present invention, when the control means determines that more than a predetermined amount of the solid raw material is not floating on the melt surface based on the detection result output from the detection means, the control means applies to the crucible of the solid raw material supply means. The supply operation of the solid material is resumed. Therefore, the solid raw material can be supplied to the crucible as needed in a state where the progress of melting of the solid raw material is stopped.

  FIG. 1 is a cross-sectional view showing a configuration of a melting apparatus 1 according to an embodiment of the present invention. The melting apparatus 1 in the present embodiment is an apparatus for supplying a melt raw material to a main crucible of a crystal manufacturing apparatus that manufactures a semiconductor crystal such as silicon. In the present embodiment, melting apparatus 1 supplies a melt raw material made of silicon, which is a raw material for producing a silicon crystal. The melting apparatus 1 includes a solid raw material supply unit 10, a detection unit 14, a control unit 15, a sub crucible 21, a heating unit 23, and a melt introduction unit 25.

  The solid raw material supply means 10 is means for supplying a granular or lump solid raw material to the auxiliary crucible 21. The solid raw material supply means 10 includes a guide part 11, a scattering prevention part 12, and a solid raw material input part 13, and is arranged vertically above the opening of the sub crucible 21.

  The solid raw material input unit 13 is a member that stores the solid raw material 2 and drops the stored solid raw material 2 into an input port 11c of the guide unit 11 described later. The solid raw material charging unit 13 includes a solid raw material container 13a, a shaft, rotating means, and linear motion means. The solid raw material storage container 13a is formed with a recess for storing the solid raw material 2 and has a square opening. The shaft is a rod-like member that is fixed to the side surface of the solid source container 13a. The shaft is fixed to the side surface of the solid material container 13a so that one diagonal line of the square-shaped opening of the solid material container 13a is parallel to the axis of the shaft and the other diagonal line is vertical. The rotating means rotates the solid raw material container 13a through a shaft in a direction around a rotation axis extending in the horizontal direction. A guide part 11 is arranged on one side of the shaft in the axial direction, and a solid material addition part for adding the solid raw material 2 measured in the other side in the axial direction into the solid material container 13a. The linear motion means linearly moves the solid material container 13a through the shaft between the guide portion 11 and the solid material adding portion disposed on both sides of the shaft in the axial direction.

  When the solid raw material 2 is supplied from the solid raw material container 13a to the inlet 11c of the guide unit 11 using the solid raw material charging part 13 as described above, the linear motion means first adds the solid raw material container 13a to the solid raw material addition container 13a. Move to the department. Next, the measured solid raw material 2 is added to the solid raw material storage container 13a in the solid raw material addition unit. Thereafter, the linear motion means moves the solid raw material container 13a upward in the vertical direction of the inlet 11c of the guide portion 11. After that, the rotating means rotates the solid material container 13a through the shaft in the direction around the rotation axis extending in the horizontal direction, and the solid material 2 is charged into the charging port 11c of the guide portion 11. Further, when the solid raw material 2 is charged from the solid raw material container 13a to the charging port 11c of the guide unit 11, the vertical length L3 from the opening of the solid raw material container 13a to the charging port 11c of the guide unit 11 is It is set so that the solid material container 13a and the guide portion 11 do not come into contact with each other.

  The guide unit 11 is a member that guides the solid raw material 2 input from the solid raw material input unit 13 to the auxiliary crucible 21 and is generally formed in a funnel shape. The guide portion 11 is disposed vertically above the opening of the sub crucible 21. The guide portion 11 is formed in a substantially cylindrical shape having openings on both sides in the vertical direction, and a communication space that is open on both sides in the vertical direction is formed. The communication space is formed in a quadrangular pyramid shape that tapers as it progresses downward. The quadrangular pyramid shape is a residual shape from which the tip portion is removed from the quadrangular pyramid. In the present embodiment, the communication space is formed in a shape in which a straight line connecting the lower base of the quadrangular pyramid and the center of the upper base of the quadrangular pyramid is inclined in one horizontal direction as it goes downward in the vertical direction.

  The guide portion 11 has a discharge port 11b formed at the lower end in the vertical direction. The discharge port 11b is an opening formed below the communication space. Further, the guide portion 11 has an upper opening at the upper end in the vertical direction. In a part of the upper side opening, a charging port 11c is formed at a position shifted in the horizontal direction from the discharge port 11b. Further, the guide portion 11 is formed with an inclined surface 11a facing the communication space from below in the vertical direction. The inclined surface 11a progresses in the horizontal direction as it goes downward in the vertical direction from the input port 11c, and continues to the discharge port 11b. Moreover, the guide part 11 is comprised including the side wall surface which faces each in a horizontal direction perpendicular | vertical to the inclination direction of the inclined surface 11a with respect to communication space. The side wall surface is bent from the inclined surface 11a and extends parallel to a plane including the vertical direction and the inclined direction. Moreover, the guide part 11 is formed including the opposing surface which faces a communicating space from the opposite side to the inclined surface 11a. Thus, the communication space is defined by the inclined surface, the two side wall surfaces, and the opposing surface.

  The acute angle θ formed by the inclined surface 11a and the horizontal plane is set so that the solid material can slide down the inclined surface 11a. Further, in the guide portion 11, the vertical length L1 from the inlet 11c to the outlet 11b, the horizontal length L2 from the inlet 25a to the outlet 11b of the melt introduction means 25, and the outlet 11b. The length L4 in the vertical direction to the melt surface of the melt raw material 3 stored in the sub crucible 21 is a space for introducing the solid raw material 2 into the input port 11c, the size of the solid raw material 2 to be introduced, and It is set in consideration of the input amount of the solid raw material 2 and the like.

  Here, when the solid raw material 2 enters the melt raw material 3 stored in the auxiliary crucible 21, a so-called splash is generated in which a part of the melt raw material 3 scatters upward in the vertical direction with respect to the melt surface. In this embodiment, since the guide part 11 is formed with the inclined surface 11a, the guide part 11 guides the solid raw material 2 input from the solid raw material input part 13 and decelerates the falling speed in the vertical direction. To the auxiliary crucible 21. Therefore, the splash generated by the impact of the solid raw material 2 falling on the melt surface can be suppressed.

  The scattering prevention unit 12 is a member that suppresses splashing of the splash generated when the solid raw material 2 is supplied to the sub crucible 21 upward from the communication space. In the present embodiment, the scattering prevention unit 12 is placed on the upper end of the guide unit 11. Specifically, the scattering prevention unit 12 is disposed above the discharge port 11b and above the inclined surface 11a. The scattering prevention part 12 is formed in a shape in which the cross-sectional shape is substantially L-shaped. The scattering prevention part 12 is comprised including the discharge port coating | coated part 12b and the bending part 12a bent upwards from the discharge port coating | coated part 12b. The discharge port covering portion 12b is formed in a plate shape, closes the upper opening except the input port 11c in the communication space, and is disposed above the guide portion 11 outlet 11b in the vertical direction. The bent portion 12a is formed in a plate shape and bends upward from a portion of the discharge port covering portion 12b near the input port 11c.

  The sub crucible 21 is a member that stores the solid raw material 2 supplied from the solid raw material supply means 10 and the melt raw material 3 in which the solid raw material 2 is melted. In the present embodiment, the sub crucible 21 is formed in a cylindrical shape, and a cylindrical recess is formed from the upper surface downward in the vertical direction. A heat insulating member 22 is coated on the side surface and the lower surface of the sub crucible 21. The heat insulating member 22 is a member for suppressing heat radiation from the sub crucible 21 and for efficiently heating the sub crucible 21 by the heating means 23.

  The heating means 23 is a means for heating the auxiliary crucible 21. The heating means 23 is provided so as to surround the periphery of the heat insulating member 22 that covers the side surface of the auxiliary crucible 21. The heating means 23 is realized by induction heating means. In the induction heating means, the auxiliary crucible 21 can be heated by passing an electric current through an induction heating coil provided so as to surround the periphery of the heat insulating member 22 covering the side surface of the auxiliary crucible 21. As the heating means, in addition to the induction heating means, a resistance heating means for heating the auxiliary crucible 21 by passing an electric current through a heat generating member made of carbon or the like may be used. By disposing the heating means 23 on the outer periphery of the auxiliary crucible 21, the solid raw material 2 supplied to the auxiliary crucible 21 is melted, and the melt raw material 3 stored in the auxiliary crucible 21 is maintained in a constantly melted state. be able to.

  The melt introducing means 25 is means for guiding the melt raw material 3 stored in the sub crucible 21 to the main crucible of the crystal manufacturing apparatus. The melt introducing means 25 has a flow path forming portion 25b that is disposed on the side surface of the sub crucible 21 and is inclined downward in the vertical direction from an inlet 25a formed in the side wall of the sub crucible 21. The flow path forming portion 25b is a cylindrical member having a hollow inside. The melt raw material 3 overflowing from the inlet 25a flows through the flow path forming portion 25b and is guided to the main crucible. When the melt raw material 3 stored in the sub crucible 21 is supplied to the main crucible using the melt introduction means 25, the melt surface of the melt raw material 3 in the sub crucible 21 is formed on the side wall of the sub crucible 21. The melt raw material 3 is stored in the auxiliary crucible 21 so as to be lower than the inlet 25 a of the melt introducing means 25. When the solid raw material 2 is supplied to the auxiliary crucible 21 in this state, the melt raw material 3 corresponding to the input amount of the solid raw material 2 overflows from the inlet 25a. The melt raw material 3 overflowing from the introduction port 25a flows through the flow path forming portion 25b of the melt introduction means 25 and is supplied to the main crucible.

  Further, when viewed in a cross section perpendicular to the central axis of the sub crucible 21, the inlet 25a of the melt introducing means 25 and the outlet 11b of the guide portion 11 are respectively arranged at positions that are substantially point-symmetric with respect to the center. The A baffle plate (not shown) is provided inside the sub crucible 21 so that the solid raw material 2 supplied to the sub crucible 21 from the discharge port 11 b of the guide portion 11 does not reach the introduction port 25 a of the melt introduction means 25.

  The detection means 14 detects that the unmelted solid raw material 2 is floating on the surface of the melt raw material 3 stored in the sub crucible 21. In the present embodiment, the solid material 2 and the melt material 3 are made of silicon. In silicon, the specific gravity in the solid state is smaller than the specific gravity in the melt state, so that the unmelted solid material 2 floats on the surface of the melt material 3.

  The detection means 14 may be in any form as long as it can detect the solid raw material 2 floating on the surface of the melt raw material 3, for example, detects heat radiated from the surface of the melt raw material 3. Examples thereof include a heat detection means and a brightness detection means for detecting the brightness of the surface of the melt raw material 3. In the present embodiment, the detection means 14 is a heat detection means. The heat detection means for detecting the heat radiated from the surface of the melt raw material 3 includes a thermocouple 14a and a thermocouple protection tube 14b. The thermocouple protection tube 14 b is formed in a bottomed cylindrical shape, and is disposed on the periphery of the discharge port 11 b above the surface of the melt raw material 3 and below the scattering prevention unit 12. The thermocouple protection tube 14 b absorbs heat radiated from the surface of the melt raw material 3.

  The thermocouple 14a is inserted and arranged in the thermocouple protection tube 14b, converts the temperature of the thermocouple protection tube 14b into an electric signal, and outputs the output value indicating the detection result in the detection means 14 as will be described later. Output to. Further, the thermocouple 14a is not necessarily inserted into the thermocouple protection tube 14b unless there is a problem such as contamination. Further, the thermocouple 14a converts the temperature of the guide part 11 or the scattering prevention part 12 arranged so as to cover the upper surface side of the opening of the sub crucible 21 into an electric signal, and indicates the detection result in the detection means 14. You may comprise so that it may output as an output value.

  FIG. 2 is a graph showing a change in the output value when the solid raw material 2 is supplied to the melt raw material 3 stored in the sub crucible 21. The horizontal axis of the graph shows the elapsed time when the solid raw material 2 is supplied to the melt raw material 3, and the vertical axis of the graph is the output value output from the detection means 14, and the temperature of the thermocouple protection tube 14b is shown. Show. When the solid raw material 2 is supplied to the melt raw material 3 and the solid raw material 2 floats on the surface of the melt, the solid raw material 2 blocks the heat radiated from the melt surface, and the temperature of the thermocouple protection tube 14b decreases. become. Therefore, as shown in FIG. 2, the output value output from the thermocouple 14a becomes smaller at the same time as the solid raw material 2 is supplied. Thereafter, as the supplied solid raw material 2 melts and the solid raw material 2 floating on the surface of the melt decreases, the output value output from the thermocouple 14a increases, and the unmelted solid raw material 2 disappears. At that time, the output value becomes constant at the complete melting output value which is an output value indicating the complete melting state.

  As described above, when the solid raw material 2 is floating on the surface of the melt raw material 3, the solid raw material 2 blocks the heat radiated from the melt surface, and the temperature of the thermocouple protection tube 14b is lowered. Therefore, by measuring the temperature of the thermocouple protection tube 14b, it is possible to detect that the solid material 2 is floating on the surface of the melt material 3.

Further, as a lightness detecting means for detecting the lightness of the surface of the melt raw material 3, a CCD (Charge
Examples include a coupled device (CMOS) camera, a complementary metal-oxide semiconductor (CMOS) camera, a thermoviewer, a pyrometer, and an illuminance sensor. The brightness detection means is attached to the surface of the melt raw material 3 stored in the auxiliary crucible 21 or a peripheral member that reflects the brightness of the surface of the melt raw material 3 to directly or indirectly adjust the brightness of the melt surface. To detect. At this time, the solid raw material 2 floating on the surface of the melt raw material 3 has low brightness, and therefore the solid raw material 2 is floating on the surface of the melt raw material 3 by measuring the lightness of the melt surface. Can be detected. The brightness data measured by the brightness detection means is output to the control means 15 described later as an output value indicating the detection result of the detection means 14.

  The control means 15 is realized by a programmable controller or the like, and controls the solid raw material supply means 10. FIG. 3 is a graph showing a change in the output value when the solid raw material 2 is supplied to the melt raw material 3 stored in the auxiliary crucible 21, and the state in which the progress of melting of the solid raw material 2 is stopped. As shown in FIG. 3, before the solid material 2 in an unmelted state disappears, and before the output value output from the detection means 14 becomes constant at the completely melted output value, the solid material 2 is changed to the melt material 3. When supplied, the output value continues to decrease each time the solid raw material 2 is supplied, and finally the progress of melting of the solid raw material 2 stops and becomes constant. Thus, the phenomenon that the progress of the melting of the solid raw material 2 stops is caused by the fact that the excess solid raw material 2 exceeding the melting ability by the heating means 23 is supplied to the sub crucible 21, etc. This occurs when the solid raw material 2 is clogged, the solid raw material 2 cannot reach the melt raw material 3 stored in the sub crucible 21, and the solid raw material 2 overflows from the sub crucible 21.

  Thus, when the progress of melting of the solid raw material 2 is stopped, the solid raw material 2 cannot be continuously supplied to the auxiliary crucible 21, and the melt raw material 3 is supplied as needed toward the main crucible of the crystal manufacturing apparatus. Can not do. Therefore, in order to continuously supply the solid raw material 2 to the auxiliary crucible 21, it is important to stop the supply operation of the solid raw material 2 when more than a predetermined amount of the solid raw material 2 is floating on the melt surface. It becomes.

  Therefore, in the present invention, if the control means 15 determines that more than a predetermined amount of the solid raw material 2 is floating on the surface of the melt raw material 3 based on the output value output from the detection means 14, the solid raw material The supply operation of the solid raw material 2 to the auxiliary crucible 21 of the supply means 10 is stopped. Specifically, when the control means 15 determines that more than a predetermined amount of the solid raw material 2 is floating on the melt surface, the rotation means and the linear motion means of the solid raw material supply unit 13 included in the solid raw material supply means 10. Is controlled to stop the solid raw material 2 accommodated in the solid raw material container 13a from being fed toward the charging port 11c of the guide portion 11. Accordingly, it is possible to prevent the solid raw material 2 from being supplied in a state where more than a predetermined amount of the solid raw material 2 is floated on the melt surface, thereby preventing the progress of melting of the solid raw material 2 from being stopped. Therefore, the solid raw material 2 can be supplied to the auxiliary crucible 21 as needed, and the melt raw material 3 can be continuously supplied to the main crucible of the crystal manufacturing apparatus.

  In the present embodiment, the upper surface side of the opening of the sub crucible 21 is covered with the guide part 11 and the scattering prevention part 12. For this reason, it is difficult to arrange a viewing window for observing the melt surface state on the upper surface side of the opening of the auxiliary crucible 21 where the state of the entire melt surface can be observed. Even in such a case, if the control means 15 determines that more than a predetermined amount of the solid raw material 2 is floating on the melt surface based on the detection result output from the detection means 14, the solid raw material supply means The operation of supplying the solid raw material 2 to the ten auxiliary crucibles 21 is stopped. Accordingly, it is possible to prevent the solid raw material 2 from being supplied in a state where a larger amount of the solid raw material 2 is floated on the melt surface.

  FIG. 4 is a graph showing a change in the output value when the solid raw material 2 is supplied to the melt raw material 3 when the output value by the detection means 14 becomes the complete melting output value. The horizontal axis of the graph shows the elapsed time when the solid raw material 2 is supplied to the melt raw material 3, and the vertical axis of the graph is the output value output from the detection means 14, and the temperature of the thermocouple protection tube 14b is shown. Show. In the present embodiment, the control unit 15 compares the output value output from the detection unit 14 with a predetermined complete melting output value, and whether or not more than a predetermined amount of the solid raw material 2 is floating on the melt surface. Determine whether. Here, the complete melting output value is an output value indicating that the unmelted solid raw material 2 is not floating on the melt surface as described above. Therefore, in the present embodiment, the predetermined amount is zero, and the control unit 15 compares the output value output from the detection unit 14 with the complete melting output value, and the solid raw material 2 floats on the melt surface. Judge whether or not. At this time, the output value output from the detection means 14 may change due to external factors such as the separation distance between the detection means 14 and the melt surface.

  Therefore, a control range that is a predetermined range based on the complete melting output value is set, and the control unit 15 applies the output value output from the detection unit 14 to the melt surface when the output value is within the range of the control range. When it is determined that the solid raw material 2 is not floating and the operation of supplying the solid raw material 2 to the sub crucible 21 of the solid raw material supply means 10 is continued and the solid raw material 2 is outside the control range, Is determined to be floating, the supply operation of the solid raw material 2 is stopped. Thereby, it is possible to prevent the solid raw material 2 from being supplied in a state where the solid raw material 2 is floated on the surface of the melt, and to prevent the progress of melting of the solid raw material 2 from being stopped. Therefore, the solid raw material 2 can be supplied to the auxiliary crucible 21 at any time, and the melt raw material 3 can be continuously supplied toward the main crucible.

  Here, the output value output from the detection means 14 is changed by an external factor much smaller than when the output value is lowered due to the solid raw material 2 floating on the melt surface. Therefore, the range of the management width in the present embodiment is set to a range from a value 5 to 10% smaller than the complete melting output value to the complete melting output value. Further, the supply amount at which the solid raw material supply means 10 supplies the solid raw material 2 to the melt raw material 3 at a time is determined by the storage capacity that can be stored in the solid raw material storage container 13a.

  Further, when the output value output from the detection means 14 does not recover within the management width even after a predetermined time has elapsed after the solid raw material 2 is supplied into the sub crucible 21, the control means 15 The solid raw material 2 may be determined to be floating on the melt surface, and a warning such as “abnormality” may be displayed on a display unit such as a display panel. Thus, by displaying the warning, the operator forcibly removes the solid raw material 2 floating on the surface of the melt based on the warning display, or the melt raw material 3 to the main crucible of the crystal manufacturing apparatus. It is possible to take measures such as stopping the supply.

  FIG. 5 is a graph showing a change in output value when the solid raw material 2 is supplied to the melt raw material 3 when a predetermined detection start time has elapsed. The horizontal axis of the graph shows the elapsed time when the solid raw material 2 is supplied to the melt raw material 3, and the vertical axis of the graph is the output value output from the detection means 14, and the temperature of the thermocouple protection tube 14b is shown. Show. In this embodiment, the detection means 14 detects the solid raw material 2 floating on the melt surface after a predetermined detection start time has elapsed since the solid raw material supply means 10 supplied the solid raw material 2 to the auxiliary crucible 21. To do. Here, the predetermined detection start time is set to be equal to or longer than the melting capacity calculation time calculated in advance from the supply amount of the solid raw material supply unit 10 supplying the solid raw material 2 to the auxiliary crucible 21 and the heating capability of the heating unit 23. The

  And the control means 15 compares the output value output from the detection means 14 after the said detection start time progresses with a predetermined | prescribed melting | dissolvable allowable value.

  Here, the allowable melting value is set as follows. As described above, when viewed in a cross section perpendicular to the central axis of the sub crucible 21, the discharge port 11 b of the guide portion 11, which is an opening through which the solid raw material 2 is supplied toward the sub crucible 21, and the melt raw material 3 are The inlet 25a of the melt introducing means 25, which is an opening flowing from the sub crucible 21 toward the main crucible of the crystal manufacturing apparatus, is disposed at a position that is substantially point-symmetric with respect to the center. Therefore, the solid raw material 2 that is supplied from the discharge port 11b to the auxiliary crucible 21 and floats on the surface of the melt is melted even during the flow until it reaches the introduction port 25a. The fluid meltable amount that is the amount of the solid raw material 2 that can be melted at the time of fluidization is calculated in advance. An output value when the flowable and meltable solid raw material 2 floats on the surface of the melt is set as an allowable melting value. In this embodiment, the allowable melting value is set to a value that is 10 to 20% smaller than the minimum value of the management width set for the above-described complete melting output value.

  When the output value is equal to or greater than the allowable melting value, the control means 15 determines that the solid raw material 2 that is larger than the predetermined amount that can be melted is not floating on the melt surface, and the solid raw material When the supply operation of the solid raw material 2 to the auxiliary crucible 21 of the supply means 10 is continued and the output value is less than the allowable melting value, the solid raw material 2 that is larger than the predetermined amount of fluid melting is floated on the melt surface. Therefore, the supply operation of the solid raw material 2 is stopped. This prevents the solid raw material 2 from being supplied in a state where a larger amount of the solid raw material 2 than the predetermined amount that can be melted is floated on the surface of the melt, and the progress of melting of the solid raw material 2 is stopped. Can be prevented. Therefore, the solid raw material 2 can be supplied to the auxiliary crucible 21 at any time, and the melt raw material 3 can be continuously supplied toward the main crucible. Moreover, since the control means 15 controls the solid raw material supply means 10 based on the allowable melting value which is a value smaller than the complete melting output value, it is solid compared to the control based on the complete melting output value. The supply amount of the raw material 2 can be increased. Therefore, as the supply amount of the solid raw material 2 increases, the melt supply amount for supplying the melt raw material 3 toward the main crucible of the crystal manufacturing apparatus can be increased.

  In addition, when the output value output from the detection unit 14 after the detection start time is less than the melting allowable value and the control unit 15 stops the supply operation of the solid raw material 2, the output value becomes the complete melting output value. When the recovery is completed, the control unit 15 controls the solid material supply unit 10 to restart the supply operation of the solid material 2.

  Also, when the output value becomes less than the allowable melting value, the control means 15 determines that more than a predetermined amount of the solid raw material 2 is floating on the melt surface, and displays “ A warning such as “abnormality” may be displayed. Further, a warning may be displayed even when the output value does not recover to the fully melted output value even after a predetermined time has elapsed after the output value becomes less than the allowable melting value. Thus, by displaying the warning, the operator forcibly removes the solid raw material 2 floating on the surface of the melt based on the warning display, or the melt raw material 3 to the main crucible of the crystal manufacturing apparatus. It is possible to take measures such as stopping the supply. Furthermore, even when the output value output from the detection means 14 is 10 to 20% or more higher than the complete melting output value, the supply operation of the solid raw material 2 is stopped or the display means such as the display panel is “abnormal”. Such a warning may be displayed. In this case, it is considered that the surface height of the melt raw material 3 in the auxiliary crucible 21 is increased for some reason and is in contact with the thermocouple protection tube 14b, and the supply operation of the solid raw material 2 is stopped to stop the auxiliary crucible 21 An accident that exceeds the capacity of the melt raw material 3 and overflows to the outside of the auxiliary crucible 21 can be prevented.

It is sectional drawing which shows the structure of the melting apparatus 1 which is one Embodiment of this invention. It is a graph which shows the change of an output value when the solid raw material 2 is supplied to the melt raw material 3 stored by the sub crucible 21. FIG. It is a graph which shows a change of the output value when the solid raw material 2 is supplied to the melt raw material 3 stored by the sub crucible 21, and a mode that advancing of melting | dissolving of the solid raw material 2 stops. It is a graph which shows the change of an output value when the solid raw material 2 is supplied with respect to the melt raw material 3, when the output value by the detection means 14 turns into a complete melting output value. It is a graph which shows the change of an output value when the solid raw material 2 is supplied with respect to the melt raw material 3 when predetermined | prescribed detection start time passes.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Melting apparatus 2 Solid raw material 3 Melt raw material 10 Solid raw material supply means 11 Guide part 11a Inclined surface 11b Outlet 11c Inlet 12 Spattering prevention part 12a Bending part 12b Outlet covering part 13 Solid raw material input part 13a Solid raw material container 14 Detection means 14a Thermocouple 14b Thermocouple protection tube 15 Control means 21 Sub crucible 22 Heat insulation member 23 Heating means 25 Melt introduction means 25a Inlet 25b Flow path forming part

Claims (9)

A melting apparatus used for heating and melting a supplied solid raw material,
A crucible for storing a melt obtained by melting a solid raw material;
Heating means for heating the crucible;
Arranged vertically above the opening of the crucible, a discharge port is formed at the lower end in the vertical direction, and an input port is formed at the upper end in the vertical direction at a position shifted in the horizontal direction from the discharge port, A solid raw material supply means for supplying a solid raw material to the crucible, having a guide portion that is formed in an inclined surface that is connected to the discharge port in a horizontal direction as it proceeds vertically downward from the input port;
A melting apparatus comprising: a detecting unit configured to detect that an unmelted solid raw material is floating on a surface of a melt stored in the crucible.   The detection means is configured to detect heat radiated from the surface of the melt stored in the crucible and detect that an unmelted solid material is floating on the melt surface. The melting apparatus according to claim 1.   The detecting means measures the temperature of at least one of the positions above the surface of the melt stored in the crucible and below the inlet, and the surface of the melt stored in the crucible The melting device according to claim 2, wherein the melting device is configured to detect heat radiated from the surface of the melt and detect that an unmelted solid raw material is floating on the surface of the melt.   The detection means is configured to detect the brightness of the surface of the melt stored in the crucible and detect that an unmelted solid raw material is floating on the melt surface. The melting apparatus according to claim 1.   The detection result output from the detection means is compared with a predetermined output value. If the detection result output from the detection means is not within the range set based on the predetermined output value, 5. The apparatus according to claim 1, further comprising a control unit that determines that more than a predetermined amount of the solid material is floating on the liquid surface and stops the supply operation of the solid material to the crucible of the solid material supply unit. The melting apparatus according to any one of the above.   When the control means determines that more than a predetermined amount of solid raw material is floating on the melt surface based on a detection result output from the detection means after a predetermined detection start time has elapsed, the solid raw material supply 6. The melting apparatus according to claim 5, wherein the solid raw material supply operation to the crucible of the means is stopped.   The detection start time is set to be equal to or longer than a melting capacity calculation time calculated from a supply amount at which the solid raw material supply means supplies the solid raw material to the crucible at a time and a heating capacity of the heating means. The melting apparatus according to claim 6.   When the control means determines that more than a predetermined amount of solid raw material is floating on the surface of the melt based on the detection result output from the detection means, the control means displays a warning and the crucible of the solid raw material supply means The melting apparatus according to any one of claims 5 to 7, wherein the supply operation of the solid raw material is stopped.   When the control means determines that more than a predetermined amount of the solid raw material is not suspended on the melt surface based on the detection result output from the detection means, the supply of the solid raw material to the crucible of the solid raw material supply means The melting apparatus according to any one of claims 5 to 8, wherein the operation is resumed.

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