JP2005225741A - Apparatus for manufacturing single crystal - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide such an apparatus for manufacturing a single crystal as having a wire changeable at an appropriate time and is excellent in the safety and productivity. <P>SOLUTION: The apparatus is such an apparatus that an eddy current examining sensor 20 for detecting the abnormality (such as the breaking of an element wire) in a wire 12 to be wound up or wound down with a winch 11 is arranged at the neighborhood of the winch 11. This apparatus makes a non-destructive test for the wire 12 at a time of the loading or unloading using the above eddy current examining sensor 20 and sends an alarm signal on the basis of a detective signal level of the above sensor 20. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a single crystal manufacturing apparatus for pulling up with a wire while growing a single crystal ingot using a seed crystal from a raw material melt contained in a quartz crucible or the like.

  High-purity single crystal ingots used in the manufacture of semiconductor wafers are generally manufactured by the Choralsky method (CZ method) in which a seed crystal is grown as a nucleus from a silicon melt of a quartz crucible and pulled up with a wire. (See, for example, Patent Document 1). An example of an apparatus for producing a single crystal by this CZ method is shown in FIG.

  The apparatus shown in FIG. 5 has a rotary box 10 connected to the upper end of a vertically long airtight chamber 1. A quartz crucible 2 is disposed at the lower part of the chamber 1 so as to be rotatable and vertically movable, and a heater 3 is disposed around the crucible 2. Installed. A winch 11 is installed in the rotating box 10, and a wire 12 wound around the winch 11 passes through the bottom of the rotating box 10 and is suspended in the chamber 1. The wire 12 is a highly heat-resistant stranded wire made of a metal wire such as a stainless wire or a tungsten wire, and the chuck 13 is fixed to the lower end portion of the wire 12 suspended in the chamber 1. The rotating box 10 is connected to the chamber 1 so as to be rotatable in the horizontal direction. When the winch 11 is rotated forward in the wire feeding direction, the wire 12 descends in the chamber 1 with the chuck 13 suspended, and the winch 11 is reversed. When rotated, the wire 12 is wound around the winch 11 and moves up with the chuck 13 in the chamber 1.

The single crystal manufacturing apparatus of FIG. 5 operates as follows. First, the wire 12 is wound up by the winch 11 and a seed crystal is attached to the lower end of the chuck 13. The chamber 1 is evacuated or an inert gas atmosphere, and the silicon single crystal or polycrystalline raw material in the crucible 2 is heated and melted by the heater 3. The winch 11 is rotated forward to feed the wire 12 and the chuck 13 is lowered toward the silicon melt 4 in the crucible 2. The seed crystal at the lower end of the chuck 13 is brought into contact with the surface of the silicon melt 4 to grow a single crystal around the seed crystal, and the winch 11 is rotated in the reverse direction at a low speed to pull up the chuck 13 with the wire 12. With this pulling, a single crystal ingot 5 having a desired diameter is grown from the silicon melt 4 while being pulled by the wire 12. When the single crystal ingot 5 grows to a predetermined length and is pulled up to the upper part in the chamber 1, the winch 11 stops rotating and the crystal ingot 5 is taken out.
JP 2003-176199 A

  The wire in the chamber is not only exposed to a high-temperature melt exceeding 1600 ° C., but the use conditions are becoming more severe as the weight of the pulled ingot increases (larger diameter, longer length). In addition, the wire is twisted while pulling up the single crystal ingot and is repeatedly wound up while being bent into the winch, so that the metal fatigue is likely to progress. For this reason, at the current single crystal manufacturing site, the wires are regularly replaced with new ones at an early stage so as to avoid the occurrence of troubles due to wire damage during use and the worst case of wire breakage. .

  On the other hand, in terms of manufacturing a high-purity ingot, it is desired to use the same wire without exchanging wires for as long as possible from the viewpoint of productivity and cost. However, if it is used continuously with some of the wires in the wire being damaged or broken, it may cause contamination of the growing crystal, resulting in a stable high purity ingot. Not only is it difficult to manufacture, but in the worst case, there is a possibility of wire breakage and ingot dropping when pulling up. For this reason, wire replacement should be performed periodically by predicting a time when there is a high probability of occurrence of abnormality such as wire damage based on experience, and setting a replacement time with a sufficient allowance from the predicted time. I have to.

  However, the operation of the single crystal production equipment must be stopped during the wire exchange, and if the wire exchange is performed frequently in a short period of time, the operation rate of the production equipment decreases and the productivity deteriorates. Production costs increase. Moreover, even if the wires are replaced in a short period of time, it cannot always be said that there is no danger of unexpected wire disconnection, and there is a problem in ensuring safety.

  An object of the present invention is to provide a single crystal manufacturing apparatus excellent in safety, in which wire replacement can always be carried out economically in an appropriate period.

  In order to achieve the above object, the present invention comprises a crucible containing a raw material melt of a single crystal ingot, and a winch disposed above the crucible and wound with a wire having a seed crystal attached to the lower end thereof. In the single crystal manufacturing apparatus in which the seed crystal is brought into contact with the surface of the raw material melt and the single crystal ingot is grown while being pulled up by the wire, a sensor for detecting an abnormality of the wire is disposed in the vicinity of the winch. And

  Here, the abnormality of the wire detected by the sensor includes not only changes in the shape of the metal wire constituting the stranded wire, but also changes in the shape of the wire surface such as extreme bending and dents, as well as internal changes such as metal fatigue. If it is left as it is, it is a defect / defect portion that causes wire breakage and contamination of foreign matter in the single crystal ingot. The sensor is a non-destructive flaw detector that detects whether there is an abnormality in the moving wire that moves up and down by winding and unwinding the winch, or the stationary wire supported by the stopped winch, the degree of abnormality, the location of the abnormality, etc. Specifically, for example, an electromagnetic flaw detection sensor or an optical flaw detection sensor corresponding to the type of wire. The sensor basically detects the abnormalities of the wire in the loading state while raising the single crystal ingot, but it can also detect the abnormality of the unloaded wire during the descent or stationary while preparing for the ingot pulling . By fixing the position of the sensor and relatively moving the wire, the entire length of the wire is inspected. Further, it is possible to determine an appropriate time for wire replacement based on the detection result of the wire abnormality of the sensor. In this way, the wire exchange is not performed regularly and uniformly based on experience, but is performed at a reasonable time based on the detection result of each sensor for each wire, resulting in the conventional regular wire exchange. Various problems such as a reduction in operating rate and safety of manufacturing equipment are solved.

  In the present invention, an alarm can be issued based on the output signal of the sensor. For example, whether an inspection monitoring unit that sends an alarm signal when a sensor detection signal level exceeds a preset reference level threshold is attached to a single crystal manufacturing apparatus, and the sensor detects a high-risk abnormality from the wire. The inspection monitoring unit constantly monitors whether or not, and when a sensor detects a high-risk abnormality, an alarm lamp or alarm buzzer is activated.

  The inspection monitoring unit is electrically connected to a sensor in the vicinity of the winch to perform a wire abnormality detection operation. The inspection monitoring unit has an inspection circuit unit that obtains an output signal of a level corresponding to the degree of abnormality of the wire by processing the detection signal output from the sensor, and displays the detection signal level of the inspection circuit unit in a meter, and The alarm circuit unit may be configured to activate an alarm buzzer or an alarm lamp by transmitting an alarm signal based on a comparison result with a predetermined reference level. The inspection circuit unit can be installed in the vicinity of the winch and the sensor inside the single crystal manufacturing apparatus, and the alarm circuit unit can be installed outside the single crystal manufacturing apparatus. As a signal transmission method between the inspection circuit unit and the alarm circuit unit, a wired method using a slip ring or the like can be used in addition to the wireless method. The alarm buzzer and the alarm lamp are operated by the alarm circuit unit, so that it is understood that it is time to replace the wire. Therefore, it becomes possible to always perform wire exchange at an appropriate time, and the problem of wire exchange in a shorter time than necessary is eliminated. In addition, the wire before the alarm is issued has no abnormality such as a broken wire, and even if there is an abnormality, the wire is of a low level that does not cause any wire breakage, so safety is always guaranteed.

  Moreover, in this invention, the electromagnetic flaw detection sensor provided with the transmission coil and receiving coil which were arrange | positioned close to the vertical part of the wire near a winch can be applied to the sensor. This electromagnetic flaw detection sensor is an eddy current flaw detection sensor or a leakage magnetic flux flaw detection sensor. A magnetic flux generated by a transmission coil (excitation coil) is continuously applied to a wire, and the eddy current or leakage magnetic flux in the wire generated by this magnetic flux is detected. The change is detected by a receiving coil (detection coil). By relatively moving the wire in the axial direction with respect to the electromagnetic flaw detection sensor, almost the entire length of the wire is continuously noncontacted and nondestructively inspected.

  According to the present invention, when the single crystal manufacturing apparatus is in operation or when the operation is stopped, the presence or absence and degree of abnormality of the wire can be detected by the sensor, and the reasonable replacement time of the wire can be determined based on the detection result of the sensor. It is possible to provide a single crystal manufacturing apparatus excellent in safety that can always be used under safe conditions. Further, since the same wire can be used safely for as long as possible, there is an effect that the operating rate of the single crystal manufacturing apparatus can be improved, the productivity can be improved, and the production cost of the single crystal ingot can be reduced.

  Hereinafter, embodiments of the present invention will be described with reference to FIGS. This embodiment is applied to the single crystal manufacturing apparatus shown in FIG. 5, and the same or corresponding parts as those in FIG.

  As shown in FIG. 1, the apparatus of the present invention has an abnormality of a wire 12 wound and unwound by a winch 11 in a rotating box 10 (such as a change in shape due to a broken wire wire, bending, dent, damage, etc., metal fatigue, etc. A sensor 20 for detecting (change) is disposed, and an inspection monitoring unit 30 for transmitting an alarm signal or the like based on a detection signal of the sensor 20 is disposed inside and outside the manufacturing apparatus. The wire 12 is a stranded wire formed by twisting a strand of stainless steel wire or tungsten wire, for example. The sensor 20 is an eddy current flaw detection sensor installed at a predetermined position in the rotary box 10 and is arranged close to the wire 12 that moves up and down in the vertical direction. Hereinafter, the sensor 20 is referred to as an eddy current flaw detection sensor 20 as necessary. For example, as shown in FIG. 4, the inspection monitoring unit 30 includes an inspection circuit unit 30 a installed in the rotating box 10 together with the eddy current flaw detection sensor 20 (or leakage magnetic flux flaw detection sensor), and a monitoring circuit unit installed outside the rotating box 10. 30b, and signal transmission means 30c arranged between the inspection circuit unit 30a and the monitoring circuit unit 30b.

  A structural example and operation principle diagram of the eddy current flaw detection sensor 20 are shown in FIGS. The eddy current flaw detection sensor 20 in FIG. 2 performs non-destructive inspection of the ascending / descending wire 12 in a non-contact manner, and includes a cylindrical bobbin 21 through which the wire 12 penetrates vertically without contact, and upper and lower portions on the inner periphery of the bobbin 21. And two receiving coils 24 and 23 mounted on the inner periphery of the bobbin 21. Although the illustrated transmission coils 22 and 23 have a through-coil structure, a half-coil or a U-shaped coil structure may be used.

  When a sinusoidal excitation current of about 2000 KHz is passed from the AC transmitter 25 to the transmission coils 22 and 23, a magnetic flux is generated in the axial direction in the bobbin 21 as shown by a chain line in FIG. 3, and the wire 12 passes through this magnetic flux region. As a result, an eddy current is generated in the wire 12. If there is an abnormality in the wire 12, this eddy current changes according to the abnormality. The eddy current change is detected by the receiving coil 24 as an impedance change or an induced voltage change and output to the inspection circuit unit 30 a of the inspection monitoring unit 30. The inspection circuit unit 30a removes a noise component from the detection signal s of the impedance change from the receiving coil 24 or the induced voltage change, amplifies it, and transmits it to the signal transmission means 30c. The signal transmission means 30c is, for example, a wireless transmission means provided with a transmission antenna installed in the rotary box 10 and a reception antenna installed in the monitoring circuit unit 30b, or a slip ring installed in the rotary box 10, and an electrical connection to the slip ring. It can be constituted by a wired transmission means provided with a touching element.

  The monitor circuit unit 30b includes a display 31 for displaying the degree of wire abnormality in an analog or digital manner from the detection signal s received by the reception antenna, and a memory circuit 32 for storing the detection signal s and used for wire management or the like. And an abnormality determination circuit 33 that appropriately outputs an alarm signal t based on a comparison result between the signal level of the detection signal s and a predetermined threshold value. An alarm lamp 34 and each drive (not shown) of the alarm buzzer 35 are connected to the output side of the abnormality determination circuit 33.

  Next, the operation of the above embodiment will be described.

  As shown in FIG. 1, the winch 11 is reversely rotated (right-turned), and the wire 12 that suspends the single crystal ingot 5 is moved up through the eddy current flaw detection sensor 20 that is fixedly arranged at a predetermined height position. Thereby, the abnormality detection of the wire 12 is continuously performed by the eddy current flaw detection sensor 20. During this time, the detection signal s from the eddy current flaw detection sensor 20 is transmitted to the inspection circuit unit 30a of the inspection monitoring unit 30, and the presence / absence of the wire abnormality and the degree of abnormality are digitized on the display 31 of the monitoring circuit unit 30b, in analog or digital form. Is displayed. When the operator visually recognizes this display, it is determined which level, number, and type of abnormality has occurred when the currently used wire 12 is an abnormal wire or an abnormal wire. If these wire abnormalities are of such a small level that they do not pose a problem even if left untreated, the alarm signal is set so that the detection signal s for this small level of abnormality does not exceed the threshold set in the abnormality determination circuit 33. Can be avoided. The detection signal s is stored in the memory circuit 32 for later analysis. When the abnormality of the wire is a large level abnormality that can cause an accident such as a wire breakage, the detection signal s for the large level abnormality exceeds the threshold value of the abnormality determination circuit 33, and the abnormality determination circuit 33 The alarm signal t is output, the alarm lamp 34 blinks, the alarm buzzer 35 sounds, and the surrounding workers are notified.

  This large-level abnormality is, for example, one or several breaks in the multiple strands 12 'constituting the wire 12 shown in FIG. The disconnection of the stranded wire 12 has a high probability of being generated by leaving one or several strands 12 ′ undisturbed. Such a disconnection of the strand 12 ′ is caused by an eddy current flowing through the wire 12. Since it appears as a large change, this disconnection abnormality is detected with high accuracy by the eddy current flaw detection sensor 20 even if one strand 12 ′ is disconnected.

  In FIG. 1, the wire abnormality detection by the eddy current flaw detection sensor 20 is continuously performed until the pulling of the single crystal ingot 5 is finished, and when the chuck 13 is raised to the height position of the eddy current flaw detection sensor 20, the pulling is finished. Non-destructive inspection is performed on the entire length of the portion of the wire 12 that is suspended from the winch 11 and becomes vertical. If the inspection monitoring unit 30 never gives an alarm in this inspection process, it is determined that there is no abnormality in the wire 12 or that the wire 12 can be used sufficiently even if there is an abnormality. Will continue to be used for the next single crystal production. In addition, when the inspection monitoring unit 30 issues an alarm in the above inspection process, it is determined that there is a large level of abnormality in the wire 12, and if this is left unattended and the wire 12 is used again and again, the risk of wire breakage increases. The In this case, after one inspection process is completed, the time for replacing the wire 12 with a new one is determined based on experience.

  It should be noted that the present invention is not limited to the above-described embodiment, and it is needless to say that various modifications can be made without departing from the gist of the present invention. For example, although the single crystal manufacturing apparatus in FIG. 1 has a sensor arranged in a rotating box on the chamber, the sensor may be arranged in the upper part of the chamber depending on the chamber structure. It is also possible to detect an abnormality with a sensor for the wire wound on the peripheral surface of the winch that winds and unwinds the wire.

It is a side view which shows the outline | summary of the single-crystal manufacturing apparatus based on this invention. It is an expanded sectional view showing the outline of the sensor in the device of FIG. FIG. 3 is an operation principle diagram of the sensor of FIG. 2. It is a block diagram of the inspection monitoring unit in the apparatus of FIG. It is a side view which shows the outline | summary of the conventional single crystal manufacturing apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Chamber 2 Crucible 3 Heater 4 Raw material melt 5 Single crystal ingot 10 Rotating box 11 Winch 12 Wire 13 Chuck 20 Sensor, Eddy current flaw detection sensor 21 Bobbin 22, 23 Transmitting coil 24 Reception coil 25 AC transmitter 30 Inspection monitoring unit 30a Inspection circuit Section 30b Monitoring circuit section 30c Signal transmission means 31 Display 32 Memory circuit 33 Abnormality judgment circuit 34 Alarm lamp 35 Alarm buzzer s Detection signal t Alarm signal

Claims (3)

A crucible containing a raw material melt of a single crystal ingot; and a winch disposed above the crucible and having a seed crystal attached to a lower end thereof for winding and unwinding, the seed on the surface of the raw material melt in the crucible In a single crystal manufacturing apparatus in which a single crystal ingot is grown by bringing a crystal into contact with the crystal while pulling up with the wire,
A single crystal manufacturing apparatus, wherein a sensor for detecting an abnormality of the wire is disposed in the vicinity of the winch.   2. The single crystal manufacturing apparatus according to claim 1, wherein an alarm is issued based on a detection signal of the sensor.   The single crystal manufacturing apparatus according to claim 1, wherein the sensor is an electromagnetic flaw detection sensor including a transmission coil and a reception coil that are disposed in proximity to a vertical portion of a wire near the winch.

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