JPH05270966A - Device for measuring distribution of heat emission of heating coil in fz process - Google Patents

Abstract

PURPOSE:To obtain a device for measuring the distribution of the heat formed in a floating zone type heating coil and enabling the direct reflection of the results to the production of silicon single crystal by making the geometry of the substrate to be heated close to the actual one of the molten zone and fitting a plurality of temperature detectors on the surface of the substrate to be heated with high-frequency induction heating coils. CONSTITUTION:The substrate to be heated 14 is made close in the geometry to the actual molten zone, and a plurality of temperature detectors such as thermocouples 18,..., are fitted to the surface 16 on the coil side of the substrate 14 which is of symmetry of rotation and arranged coaxially with the high-frequency induction heating coil and opposing to each other in the close position. When grooves 17 are formed so as to surround the thermocouple 18 on the substrate surface 16 and an insulating material 19 such as a ceramic is embedded in the groove 17, the heat generated on the surface of the substrate does not dissipate in the sideways direction and the precise exothermic temperature can be measured.

Description

Detailed Description of the Invention

[0001]

This invention can effectively measure the actual heat distribution of a high-frequency induction heating coil for partially heating and melting a raw material silicon polycrystalline rod by the FZ method (floating zone melting method). The present invention relates to a heat generation distribution measuring tool for an FZ method heating coil.

[0002]

2. Description of the Related Art Conventionally, when a silicon single crystal is manufactured by the FZ method, a polycrystalline rod holder attached to the lower end of an upper drive shaft having a vertical movement function and located in a chamber, and a vertical movement function. A polycrystalline rod holder is provided which uses a device having a seed crystal holder attached to the upper end of a lower drive shaft and located in the chamber, and a high frequency induction heating coil provided in an intermediate portion of the chamber. To hold the raw material silicon polycrystal rod, and to hold the seed of the silicon single crystal in the seed crystal holder, melt one end of the silicon polycrystal rod by the high frequency induction heating coil, fused to the seed crystal and seeded After that, the high-frequency induction heating coil and the silicon polycrystalline rod are relatively rotated and relatively moved in the axial direction so that the polycrystalline silicon rod is not zone-melted in the axial direction in sequence. To produce the Luo silicon single crystal ingot it is generally performed.

By the way, when a part of a silicon polycrystalline rod is heated and melted by a high frequency induction heating coil, it is not known whether or not it is in an appropriate heating distribution state, and if it is melted by a defective high frequency induction heating coil, it becomes uniform. In addition to failing to obtain a good single crystallization, there are cases in which the FZ operation cannot be continued.

[0004]

To solve this problem, the cross-sectional resistivity distribution of the silicon single crystal ingot can be predicted by making it possible to measure the heat generation temperature distribution of the high frequency induction heating coil in advance. Therefore, it seems that a thermocouple may be arranged above or below the high frequency induction heating coil and the thermoelectromotive force generated in the thermocouple may be measured, but there are two major drawbacks in the method of arranging only the thermocouple. There is. First, since the conductor coupled to the high-frequency magnetic field formed by the high-frequency induction heating coil is only a thermocouple, the high-frequency magnetic field is far from the shape of the magnetic field during crystal growth. As a result, it becomes very difficult to reflect the measured heat generation distribution in the production of single crystals. Secondly, due to the spatial expansion of the high-frequency magnetic field formed by the high-frequency induction heating coil, the parts of the thermocouple other than the high-temperature contact are also heated, and the temperature at the high-temperature contact cannot be obtained accurately. Therefore, the above method cannot achieve the above object.

Therefore, an object of the present invention is to provide a measuring tool for measuring the heat generation temperature distribution of a high frequency induction heating coil that can be directly reflected in the production of a silicon single crystal.

[0006]

In order to solve the above-mentioned problems, the present invention provides a coil-side surface of a rotationally symmetrical object to be heated which is coaxial with the coil to be heated by a high-frequency induction heating coil and which is arranged in a close confrontation position. The heat generation distribution measuring tool of the FZ method heating coil is provided with a plurality of temperature detecting means in its part.

A thermocouple or the like is preferably used as the temperature detecting means, but the present invention is not limited to this, and means for accurately detecting the temperature of the surface portion of the heated object to be heated. Of course, it is good if it is. Also, if the structure around the thermocouple is insulated, the generated heat will not escape laterally,
This is preferable because the heat generation state can be measured accurately.

The temperature detecting means is preferably arranged so that the heat generation distribution of the high frequency induction heating coil can be measured uniformly and evenly. For example, one-letter shape, cross shape, ring shape, spiral shape, etc. , Including all sequences.

It is preferable that the surface to be heated of the object to be heated is inclined so as to form a mountain shape toward the high-frequency induction heating coil, and the inclination angle is the melting zone of the silicon polycrystalline rod. An angle close to the inclination angle of is preferable. In particular, if the central portion of the object to be heated is projected so as to be located between the high frequency induction heating coils,
This is preferable because the state is close to that of actual production of a single crystal by the FZ method.

The material of the object to be heated may be any material having physical properties that are close to the melting zone of the raw material polycrystalline silicon rod, such as stainless steel. On the contrary, examples that are not suitable are those having extremely high thermal conductivity such as copper and insulators such as ceramics. In the former case, there is a drawback that the heat generation distribution is averaged because of high thermal conductivity. Further, in the latter case, since the inductive coupling is not performed, a high frequency magnetic field is transmitted and there is a drawback that a required magnetic field shape cannot be obtained.

[0011]

The high frequency magnetic field generated by the high frequency induction heating coil (12) interacts with the object to be heated (14), and as a result, the surface part (16) of the object to be heated is heated and the surface of the object to be heated is heated. The heat distribution state of the high frequency induction heating coil (12) can be measured by knowing the temperature distribution state of the surface part (16) to be heated by the plurality of thermocouples (18) arranged in the part (16). it can. Here, when the temperature fluctuation rate indicated by each thermocouple becomes, for example, 0.5% or less, it is considered that the measurement system has almost reached thermal equilibrium, and the heat generation temperature distribution can be obtained.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail based on the embodiments shown in the accompanying drawings. 1 and 2 are a schematic cross-sectional view and a top view showing one embodiment of a heat distribution measuring tool (10) according to the present invention.

In the figure, (12) is a high frequency induction heating coil for generating a high frequency magnetic field. Reference numeral (14) is a body to be heated which is heated by the high frequency magnetic field, and has a rotationally symmetric shape which is coaxial with the high frequency induction heating coil (12) and is arranged in a close-to-face position. The material of the object to be heated (14) may be any material having physical properties such that the electrical conductivity and the thermal conductivity are close to the melting zone of the raw material polycrystalline silicon rod.
Stainless steel or the like is preferable.

The object to be heated (14) is arranged below the high frequency induction heating coil (12), and a gentle mountain is formed so that the center of the surface portion (16) facing the high frequency induction heating coil (12) is high. It has a slanted shape.
As this inclination angle, an angle close to the inclination angle of the melting zone of the polycrystalline silicon rod is preferable, and due to this shape, the high frequency magnetic field generated by the high frequency induction heating coil (12) causes the surface portion (16) of the body to be heated to be heated. The magnetic field passes outward from the center of the magnetic field and the magnetic field flows in a state close to that during the actual FZ. The high frequency magnetic field is applied to the surface part (1
Only the portion near 6) is transmitted, and as a result, it is heated in the portion near the surface portion (16) of the body to be heated.

Reference numeral (18) is a thermocouple which is a temperature detecting means, and is welded (20) so that its tip reaches the surface (16) of the object to be heated and embedded in the object (14) to be heated. Has been done. Since it is necessary to know whether or not the heating distribution state of the high frequency induction heating coil (12) is uniform, a plurality of thermocouples (18) are arranged instead of a single one.

It is preferable that a plurality of the thermocouples (18) are arranged symmetrically with respect to the central portion of the surface portion (16) of the body to be heated. The temperature detection distribution state need not be biased so much. For example, the temperature detection distribution state may be a cross shape as shown in FIG. 2, a single letter shape, a ring shape, or any other arrangement state. It is a waste. Further, if the object to be heated (14) is rotationally moved around an axis perpendicular to the bottom surface of the high frequency induction heating coil (12) for measurement, higher density measurement is possible.

As shown in FIG. 3, the surface portion (1
If a groove (17) is formed in 6) so as to surround the periphery of the thermocouple (18) and a heat insulating material (19) such as ceramic powder is embedded in the groove (17), the surface of the heated object The generated heat does not escape laterally, and the accurate heat generation temperature can be measured.

By configuring the measuring tool (10) in this way, the high-frequency magnetic field generated by the high-frequency induction heating coil (12) interacts with the object to be heated (14), and as a result, the object to be heated is heated. The body surface portion (16) is heated, and high-frequency induction heating is performed by knowing the temperature distribution state of the body surface portion (16) to be heated by the thermocouple (18) arranged on the body surface portion (16) to be heated. The heat generation distribution state of the coil (12) can be measured. Reference numeral (22) is a support base for the body to be heated (14), and reference numeral (24) is a support rod thereof.

FIG. 4 is a schematic cross-sectional view of a heat distribution measuring tool (10) showing another embodiment of the object to be heated (14), showing an example close to the actual heating state of a silicon polycrystalline rod. ..

That is, in order to match the shape of the lower half of the melting zone of the silicon polycrystalline rod in the FZ, the object to be heated (1
The protrusion (26) is formed so that the central portion of the surface portion (16) of 4) is located between the high frequency induction heating coils (12).

Therefore, the flow of the high-frequency magnetic field generated from the high-frequency induction heating coil (12) becomes very similar to the actual flow of the high-frequency magnetic field in the FZ, and the actual heat generation distribution measured by the high-frequency induction heating coil (12) can be measured. can get. In this way, for various shapes of the high-frequency induction heating coil (12), as a result of zone melting, for example, the melting method at the lower end peripheral portion of the raw material polycrystalline rod, the crystallinity of the grown crystal, and the heat generation distribution of the present invention are compared. As a result, the ideal heat generation distribution can be obtained, so that the high frequency induction heating coil (1
In addition to the process control of 2), when designing a new coil such as a double coil or a different shape of the coil conductive section,
New coil conditions can be obtained without specific zone melting.

In the above embodiments, the object to be heated (1
4) is located below the high frequency induction heating coil (12), the present invention is not limited to this, and as shown in FIG.
Even if the object to be heated (14) is placed on the upper side of 2) and the measurement is performed, the same effect can be obtained.

Next, an example in which the temperature distribution of the high frequency induction heating coil (12) is actually measured using the object to be heated (14) according to the present invention will be shown. What is important here is that when setting the heated object (14) for measuring heat distribution, all the high-frequency induction heating coils (12) to be measured and the heated object (14) should have the same distance and arrangement. It is to fix.

Measurement Example 1 A high frequency induction heating coil (12) having a flat upper surface as shown in FIG. 6 is prepared by using a heated body (14) having a size as shown in FIG. The temperature distribution was measured by the arrangement. The results are shown in the graph of FIG. According to this graph, the temperature distribution of the high frequency induction heating coil (12) having a flat upper surface is such that the temperature decreases toward the periphery of the coil (12). Therefore, it is expected that the raw material polycrystalline silicon rod cannot be melted sufficiently and the FZ operation cannot be continued. In fact, when the raw material polycrystalline rod is melted using the high frequency induction heating coil (12) having a flat upper surface, the peripheral portion of the raw material polycrystalline rod is hard to melt as shown in FIG. I have come into contact with 12).

Measurement Example 2 Next, using the same object (14) to be heated, the pancake type high frequency induction heating coil (12) as shown in FIG. 9 was arranged in the temperature distribution as shown in FIG. Was measured. The results are shown in the graph of FIG. According to this graph, the temperature distribution of the pancake type high frequency induction heating coil (12) was different from that in Measurement Example 1 and did not decrease sharply in the peripheral direction. Therefore, it is expected that the raw material polycrystalline rod can be sufficiently melted and the operation by the FZ method can be performed. Actually, when the raw material polycrystalline rod is melted by using the pancake type high frequency induction heating coil (12), the raw material polycrystalline rod is smoothly melted as shown in FIG. 11, and the FZ operation can be continued without any trouble. I was able to.

[0026]

As described above, according to the present invention, the shape of the object to be heated is brought into a state close to the shape of the actual melting zone in the FZ, and the surface portion of the object to be heated which is heated by the high frequency induction heating coil. Since the temperature detecting means composed of a plurality of thermocouples and the like is arranged in the above, the heat generation distribution state of the high frequency induction heating coil at the time of actual FZ can be measured in advance, which also serves as a certification of the high frequency induction heating coil.
The effect peculiar to the present invention that the cross-sectional resistivity distribution of the silicon single crystal ingot can be predicted can be obtained.

[Brief description of drawings]

FIG. 1 is a schematic sectional view showing an embodiment of a heat generation distribution measuring instrument according to the present invention.

FIG. 2 is a top view of the heat generation distribution measuring tool viewed from the line II-II in FIG.

FIG. 3 is a detailed cross-sectional view showing an example of a structure in which the periphery of a thermocouple is thermally insulated.

FIG. 4 is a schematic cross-sectional view showing another embodiment of a heat generation distribution measuring tool in which the shape of the object to be heated is changed.

FIG. 5 is a schematic cross-sectional view of the heat generation distribution measuring tool with the object to be heated positioned above the high frequency induction heating coil.

FIG. 6 is a layout diagram for measuring a temperature distribution of a high frequency induction heating coil having a flat upper surface using the object to be heated of the present invention.

7 is a graph showing the measurement result of the temperature distribution according to FIG.

FIG. 8 is a schematic view of a raw material polycrystalline rod melted using a high-frequency induction heating coil having a flat upper surface.

FIG. 9 is an arrangement view for measuring a temperature distribution of a pancake type high frequency induction heating coil using the object to be heated of the present invention.

10 is a graph showing the measurement results of the temperature distribution according to FIG.

FIG. 11 is a schematic view of a raw material polycrystalline rod melted using a pancake type high frequency induction heating coil.

[Explanation of symbols]

 10 Heat Generation Distribution Measuring Tool 12 High Frequency Induction Heating Coil 14 Heated Body 16 Surface of Heated Body 17 Groove 18 Thermocouple 19 Heat Insulating Material 20 Welding Part 24 Supporting Rod 26 Projecting Part

Claims (6)

[Claims] 1. A plurality of temperature detecting means is provided on a coil-side surface portion of a rotationally symmetrical object to be heated, which is coaxially arranged with the high-frequency induction heating coil and is disposed at a position close to and facing the coil. Characteristic tool for measuring heat distribution of FZ heating coil. 2. The heat generation distribution measuring tool for the FZ method heating coil according to claim 1, wherein the temperature detecting means is a thermocouple. 3. The FZ method according to claim 2, wherein a groove is formed in the surface portion of the object to be heated according to claim 1 around the thermocouple, and a heat insulating material is embedded in the groove. Measuring tool for heat distribution of heating coil. 4. The heat generation distribution of the FZ method heating coil according to claim 1, 2 or 3, wherein a surface portion of the object to be heated facing the high frequency induction heating coil is inclined in a mountain shape. Measuring tool. 5. The heat generation distribution measuring tool for the FZ method heating coil according to claim 1, 2 or 3, wherein a central portion of the object to be heated is projected so as to be located between the high frequency induction heating coils. .. 6. The heat generation distribution measuring tool according to any one of claims 1 to 5 is positioned above or below a high frequency induction heating coil to measure the heat generation distribution of the high frequency induction heating coil. FZ method A method for measuring the heat distribution of a heating coil.