JPS63291389A - Single-turn induction heating coil - Google Patents

Abstract

PURPOSE:To prevent the magnetic field leakage in a gap area, the deterioration of the electromagnetic coupling, and the disturbance of the magnetic field by a feeder tube by providing conductive arc plates in the gap area on the coil peripheral end face so that the gap area can be practically shielded. CONSTITUTION:A pair of symmetrical conductive arc plates 24A, 24B are welded on the bottom side periphery of a coil 20 facing a monocrystal growth zone, and the side of a gap area 23 facing the monocrystal growth zone is practically shielded. The plates 24A, 24B are inclined toward the outer diameter side so as to approach the monocrystal growth zone side. As a result, the electromagnetic coupling between the coil 20 and the monocrystal growth zone is increased, and the crystal growth effect is improved. A feed tube 11 is electromagnetically shielded with the plates 24A, 24B, thus the magnetic field disturbance at the portion can be prevented. The magnetic field leakage in the gap area, the deterioration of the electromagnetic coupling, and the magnetic field disturbance can be thereby prevented.

Description

Detailed Description of the Invention "Field of Industrial Application" The present invention relates to a single-turn induction heating coil used in the floating zone melting method (hereinafter referred to as the FZ method), and in particular to various members attached to the coil such as a feed pipe. This invention relates to a single-turn induction heating coil that is wound around with a predetermined distance between both end faces in the circumferential direction of the coil in order to secure a space for arrangement.

"Prior Art" Equipment for manufacturing semiconductor single crystals, refining semiconductor polycrystals, manufacturing compound semiconductors, etc. using the FZ method has been known. In this method, a rod-shaped raw material polycrystal is held on the upper shaft and a single crystal seed with a small diameter is held on the lower shaft, and one end of the polycrystal is melted by a high-frequency induction heating coil surrounding the raw material polycrystal and fused to the seed crystal. After seeding, the coil and the polycrystal are relatively rotated and relatively moved in the axial direction while the semiconductor rod is made to be dislocated by seed squeezing, and the semiconductor rod is zone-melted to produce a rod-shaped semiconductor single crystal. ing.

Therefore, in this type of equipment, it is necessary to melt the polycrystalline raw material down to the core in a short time in a small region, so it is necessary to be able to apply a magnetic field concentrated in the zone melting zone of the semiconductor rod. In order to stably grow the subsequent semiconductor into a single crystal without variations in impurities, it is necessary to gently dissipate heat from the starting end of the single crystal growth region in contact with the floating zone.In order to satisfy this requirement, Conventionally, a single-turn flat heating coil is used, and its inner diameter, outer diameter, cross-sectional shape, etc. are variously selected to achieve a well-balanced heating of the zone and growth of the single crystal.

However, as the diameter of manufactured single crystals increases, the melting of the zone needs to be concentrated in a narrower area, and the growth of single crystals has become more difficult in order to avoid temperature changes between the window side and the peripheral side. It is necessary to dissipate heat slowly and in a well-balanced manner, and it has become difficult to satisfy such antinomic heating effects with a single heating coil.

Therefore, in the patent application (1) filed concurrently, the present inventor proposed that, for example, as shown in FIGS. 5 and 6, the floating zone 3
A first single-turn heating coil 1 that performs melting surrounding the
0 (hereinafter referred to as the inner coil), a second heating coil 20 (hereinafter referred to as the outer coil) is provided, and while the floating zone 3 is melted by the inner coil 10, the peripheral edge side 4a on the starting end side of the single crystal is We are proposing a technology that suppresses temperature changes between the four cores of the single crystal and the outer circumferential side as much as possible while heating, thereby achieving stable single crystal growth.

"Problems to be Solved by the Invention" However, in the above technology, the inner coil 10 and the outer coil 2
However, if such a configuration is adopted, the inner power supply pipe 11 extending from the outer wall of the inner coil IO becomes an obstacle, as shown in FIG. The gap between both end faces in the circumferential direction of 20 cannot be brought close to each other, so that magnetic field leakage occurs in the gap portion 23 and the degree of electromagnetic coupling is also weakened. Moreover, disturbance of the magnetic field is likely to occur in the inner feed tube 11 existing in the gap portion 23.

Such a drawback exists not only in a heating mechanism using a plurality of coils, but also in a heating mechanism using a tubular single-turn coil 50 as shown in FIG.
A technique has been disclosed (Japanese Patent Laid-Open No. 58-82492) in which a ring-shaped flange 51 is provided in the circumferential direction of the top 50a of the outer periphery. Since it is connected to the outer circumferential top portion 50a, the feeder tube 52 extending outward from both ends of the coil 50 becomes an obstacle, and the both end surfaces 51a of the flange portion 51 cannot be brought close to each other. If a problem occurs and the coil 50 is used to perform zone melting of the raw material polycrystal, variations will occur in the macro and micro resistance distribution of the produced single crystal, making it impossible to produce a high quality single crystal. .

In order to eliminate such drawbacks, the present invention provides a space for arranging various members attached to the coil, such as a feed tube, even when the coil is circulated with a predetermined distance between both end faces in the circumferential direction. It is an object of the present invention to provide a single-turn induction heating coil that does not cause magnetic field leakage in the separated area, decrease in the degree of electromagnetic coupling, or cause disturbance of the magnetic field due to the presence of the feed tube.

"Means for Solving the Problems" In order to achieve the above technical problems, the present invention, as shown in FIGS. 1 to 4, provides the following: or a plurality of conductive arc-shaped plates 24A, 24B are fixed; (2) The arc-shaped plates 24A, 24B are configured to substantially connect the separated area 23 between both end surfaces 2Qb in the circumferential direction of the coil 20; We propose a single-turn induction heating coil as a component.

In this case, the arcuate plates 24A and 24B are connected to the coil 20.
It is preferable to form the curved wheel with a width that is approximately the same as or slightly smaller than the circumferential surface, and being substantially connected by the arcuate plates 24A and 24B means that the pair of conductive arcuate plates 24A and 24B are connected from both ends of the coil. Extending to the separation area 23 side, the separation area 23
Both end surfaces 20b in the circumferential direction may be opposed to each other at the center position via the slit gap 25 (see FIG. 1), and a negative conductive arc plate is extended from one end of the coil to the separation area 23 side,
It may be configured so that the entire area of the separation area 23 is substantially hidden. In addition, the slit gap 25, in other words, the arcuate plate 24
The shapes of both ends 26 where A and 24B face each other in the circumferential direction via the slit gap 25 may be formed to extend in the radial direction (see Fig. 1), or may be formed to be inclined in the circumferential direction. It is possible.

By slanting the arcuate plates 24A and 24B from the inner diameter side of the coil toward the outer diameter side and toward the heated area side, favorable results can be obtained in terms of thermal efficiency and electromagnetic coupling.

"Operation" According to this technical means, in order to secure the arrangement space for various members such as the feed tube 11, both end faces 2O in the circumferential direction of the coil 20 are
Even when the heating area 23 is circulated with a predetermined distance between the areas 24a and 24b, the arcuate plates 24A and 24B make it possible to substantially connect the side of the spaced area 23 facing the heated area 4.
Magnetic field leakage generated in the separation area 23'! , it is possible to prevent a decrease in the degree of magnetic coupling and disturbance of the magnetic field caused by the feed tube 11, and thereby to minimize the adverse effects on the heated area side 4.

Further, according to the present technical means, since the plate thickness and inclination angle of the arcuate plates 24A and 24B can be freely determined, the arcuate plates 24A and 24B can be freely determined.
, 24B, or by arranging them close to the heated area 4 side, the heated area 4 (single crystal growth area)
The degree of electromagnetic coupling between the coils 20 and 20 is improved, which reduces the impedance of the coil 20, making it easier for induced current to flow also on the outer diameter side, improving electrical characteristics.

Furthermore, in conventional single-turn induction heating coils, the current ratio was determined only by the ratio of the inner and outer diameters of the coil, but with the present technical means, the current ratio can be determined by appropriately adjusting the thickness and length of the connecting plates 24A and 24B. , when the electromagnetic field is partially strengthened and, for example, the inner coil 10 is eccentric, it is possible to cancel out the non-uniformity of the electromagnetic field on the circumference of the single crystal start end side peripheral part 4a, and the coils 1o and 20 The degree of freedom in design can be increased.

"Embodiments" Hereinafter, preferred embodiments of the present invention will be described in detail by way of example with reference to the drawings. However, the dimensions, materials, shapes, relative positions, etc. of the components described in this embodiment are within the scope of this invention unless otherwise specified. This is not intended to be limiting, and is merely an illustrative example.

1 to 4 show a heating mechanism consisting of a plurality of heating coils used in a semiconductor single crystal manufacturing apparatus according to an embodiment of the present invention, FIG. 1 is a bottom view, FIG. 2 is a top view, FIG. 3 is a sectional view taken along the line AA' in FIG. 1.

FIG. 4 is a sectional view taken along the line BB' in FIG. 1 showing the positional relationship with the semiconductor rod in the manufacturing state.

This heating mechanism includes a first single-turn flat heating coil (hereinafter referred to as the inner coil 1G) that performs zone melting of the raw material polycrystalline 2, and a first single-turn flat heating coil (hereinafter referred to as the inner coil 1G) that is concentric with the inner coil 10 and extends along its outer periphery along substantially the same plane. A second single-turn flat heating coil (hereinafter referred to as the outer coil 20) is arranged so as to surround the outer wall, and each of these coils 10 and 20 extends outward parallel to the outer wall surface. The coils 10.2 are integrally connected to the support body 41 via two feeder tubes 11.21.
The interval between 0 is maintained.

Next, the configurations of these various members will be explained.

The support body 41 supports the coil to, 20 and the feed tube 11.
．． 21, an opening (not shown) communicating with the power supply pipe 11.21 is provided on the opposite wall surface to which the power supply pipe 11.21 is fixed. A coolant introduction pipe 42 (see Fig. 2) is connected to the opening,
The cooling liquid introduced into the introduction pipe is branched by the support 41 and led out to each power supply pipe 11.21 side, and a high frequency power source 40 is connected to the proximal end side of the introduction pipe to From the power supply 40, the cooling liquid introduction pipe-support body 4
1 - High frequency currents having the same frequency are passed through the inner and outer coils 20 through the feed pipes 11.21, respectively.

Now, the inner coil 10 is formed from a hollow flat body formed into a ring shape with a substantially square cross section through a slit gap 12 along the radial direction, and the outer peripheral walls of both ends facing each other with the slit gap 12 interposed therebetween. After connecting a feed tube 11 (hereinafter referred to as an inner feed tube) to each of the inner feed tubes 11 and extending the inner feed tube 11 along the radial direction to the vicinity of the outer periphery of the outer coil 2o, the tip side thereof is expanded into a U-shape. Its terminal end is attached to the support 41.

The shape of the inner coil 1O will be explained based on FIG. 4.The coil inner diameter 10a is set smaller than the diameter of the raw material polycrystal 2, and the lower surface side is maintained in a horizontal state, and the cross section is directed toward the inner diameter side. While being formed into a tapered shape, the cooling liquid introduced from the power supply pipe 11 into the cavity 13 inside thereof can be circulated.

The inner coil 10 has a ring-shaped flange 15 connected horizontally to the upper edge of the outer circumferential surface of the coil to increase the apparent outer circumferential diameter, and the lower edge of the outer circumferential surface is chamfered to form the outer coil 20 described later. Enables smaller inner diameter. Both end surfaces 20b in the circumferential direction of the ring-shaped flange 15 are arranged so as to be close to each other on the extension line of the slit gap 12 of the inner coil 10 and to face each other with the slit gap 15a interposed therebetween. In addition to providing electromagnetic linkage of the feeder tube 11 extending in the opposite direction, generation of a non-uniform magnetic field in the slit gap 15a is prevented.

As a result, the inner coil 10 has a tapered cross section toward the inner diameter side, and can be formed to have a wider width in the circumferential direction due to the flange 15, so that the inner coil 10 is flattened. Magnetic field concentration in band 3 and band 3
The melting speed per unit time increases, and even when the diameter of the raw material polycrystal 2 is increased, the floating zone 3 can be melted stably and quickly.

On the other hand, the outer coil 20 is formed of a ring having a stool-like cross section and is wound around the bottom circumferential surface of the inner coil, and both circumferential ends thereof are disposed close to the circumferential surface of the inner feed tube 11 . On the outer wall surface of both ends of the coil, an outer power supply pipe 21 is provided which extends parallel to the outer side of the inner power supply pipe 11 in a V-shape, and its terminal end is connected to the support 41.
to be fitted.

As shown in FIG. 4, the outer coil 20 has an inner diameter set to be the same as or slightly larger than the outer diameter of the peripheral edge 4a on the starting end side of the single crystal growth region 4 adjacent to the floating zone 3. The inner coil 1 is formed with a tapered cross section while the lower surface side is
0, and a through hole 22 for introducing a cooling liquid is formed around the outer circumferential side thereof so that the cooling liquid introduced from the power supply pipe 21 can circulate in the through hole 22.

Furthermore, since the inner feed tube 11 extending from the outer wall of the inner coil 10 is present between the circumferential end surfaces 20b of the outer coil 20, the separation areas 23 between the circumferential end surfaces 20b cannot be brought close to each other. Naturally, magnetic field leakage from the separation area 23 and disturbance of the magnetic field due to the presence of the inner feed tube 11 occur.

Therefore, in this embodiment, as shown in FIG. The side facing Growth Area 4 is substantially hidden.

Next, the structure of the arcuate plates 24A, 24B will be explained in detail. The arcuate plates 24A, 24B are made of copper or silver plate members made of the same material as the coil, and are made of copper or silver plate members that are approximately the same as or slightly smaller than the circumferential surface of the coil. After welding the inner edge 26 and chord part 27 to the bottom circumferential surface 20a of the coil, weld the inner edge 26 and chord part 27 to the outer diameter side so as to approach the single crystal growth region 4 side. The arcuate plates 24A and 24B are tilted downward, and both end surfaces 2Ob of the arcuate plates 24A and 24B in the circumferential direction are brought close to each other as much as possible, so that the inner feed tube 11 and the single crystal growth region 4 can be substantially connected to each other.

As a result, the inner edge side of the outer coil 20 can be arranged facing the starting end side peripheral edge side 4a of the single crystal growth region 4, and the arcuate plates 24A, 24B, in other words, the coil 20
Because a part of it approaches the peripheral edge of the single crystal starting edge,
The electromagnetic coupling between the single crystal growth regions 4 is improved, the crystal growth effect is improved, and the melting surface 4b on the starting end side of the single crystal growth region 4 can be made shallower, thereby improving the macro and micro resistance distribution. I can do it.

Furthermore, according to this embodiment, the single crystal growth region 4 of the power supply tube 11
Since electromagnetic connection can be performed on the side, it is possible to prevent magnetic field leakage in that part, and it is possible to prevent non-uniformity in the crystal caused by local changes in the heating temperature on the side of the single crystal growth area 4. .

Furthermore, since the arcuate plates 24A and 24B also function as a cover for concealing the coil separation area 23, the entraining convection 5 of the gas flow shown in FIG. Collision can be prevented, the uniform heating effect of the polycrystals can be improved, and the so-called "gravity ratio" phenomenon in which unmelted parts hang down in an icicle shape from the polycrystal peripheral edge 2a can be prevented.

"Effects of the Invention" As described above, according to the present invention, even when the coil is circulated with a predetermined spacing between both end faces in the circumferential direction, magnetic field leakage occurs in the spaced area, the degree of electromagnetic coupling decreases, and It is possible to obtain a single-turn induction heating coil that does not cause disturbance of the magnetic field due to the presence of the feed tube, and also solves various problems especially when the inner coil and outer coil are arranged on almost the same plane. It is possible to provide a single-turn induction heating coil.

It has various effects such as

[Brief explanation of the drawing]

1 to 4 show a heating mechanism consisting of a plurality of heating coils used in a semiconductor single crystal manufacturing apparatus according to an embodiment of the present invention, FIG. 1 is a bottom view, FIG. 2 is a top view, 3 is a sectional view taken along the line AA' in FIG. 1, and FIG. 4 is a sectional view taken along the line BB' in FIG. 1, showing the relationship between the stirrup and the semiconductor rod in the manufacturing state. 5(A), 5(B), and 6 show the heating mechanism disclosing the problem to be solved by the present invention, FIG. 5(A) is a plan view, and FIG. 5(B) is a bottom view. , FIG. 6 is an explanatory longitudinal cross-sectional view. FIG. 7 is a plan view showing a heating coil according to the prior art. Figure 1 Figure 3 Figure 4vA Teeth Figure 5 (A) CB) Figure 6 Figure 7

Claims (1)

[Claims] 1) In a single-turn induction heating coil used for the floating zone melting method, which is circulated with a predetermined distance between both end faces in the circumferential direction of the coil, at least on the side of the coil circumferential face facing the heated area. 2) A single-turn induction heating coil characterized in that one or more conductive arc-shaped plates are fixedly attached, and the arc-shaped plates are configured to substantially block the separated area. 3) The single-turn induction heating coil according to claim 1 is inclined at a predetermined angle toward the outer diameter side. Claim 1
Single-turn induction heating coil according to item 2 or item 2