DK146725B - INDUCTION HEAT COILS FOR DIGEL-FREE ZONE MELDING - Google Patents

Description

(19) DENMARK (^)

(.2) PUBLICATION OF 146725 B

DIRECTORATE OF

THE PATENT AND TRADEMARKET SYSTEM

(21) Patent Application No: 6084/72 (51) lnt.CI.3: C30B 13/20 (22) Filing Date: 06 Dec 1972 (41) Aim. available: 08 Jun 1973 (44) Submitted: 12 Dec 1983 (86) International Application No: - (30) Priority: 07 Dec 1971 DE 2160694 (71) Applicant: 'SIEMENS AKTIENGESELLSCHAFT; Berlin and Munich, 8 Munich 2, DE.

(72) Inventor: Wolfgang 'Keller; THE.

(74) Plenipotentiary: International Patent Office (54) Induction heating coil for crucible zone melting of semiconductor rods

The invention relates to an induction heating coil for crucible-free zone melting of semiconductor rods and which is flowed through cooling water.

In crucible-free zone melting of semiconductor material, a melt zone provided by an induction heating coil is caused to travel through a rod-shaped body of semiconductor material. In this way impurities are carried to one end of the rod.

The method is also often used for single crystal cultivation, with one germ crystal being melted at one end of the semiconductor rod, after which a melting zone is passed through the rod starting from this germ crystal. The rod-shaped body is, for the most part, usually arranged vertically and clamped at the ends of holders.

OQ When drawing semiconductor rods larger than the inner diameter ||} in the induction heating coil, the coil can only be removed from the rod at its end, j ^ | if you pull or break the semiconductor rod at the rod end. This is <0 *

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2 146725 is inconvenient when multiple zone melting passages are to be made, such as e.g. is the case in the manufacture of dislocation-free semiconductor rods.

Here, either an impact piece thinner than the inner diameter of the coil must be melted before the beginning of the draw to the rod end, or a new impact piece must be melted before each zone melt passage. Both methods are very complicated and expensive, especially in the manufacture of semiconductor rods with large diameters, ie. with diameters ranging from 60 to 80 mm or more.

US Patent No. 2,266,176 discloses an apparatus for electrically welding workpieces and with cooling. An inductive heating of various metal objects here serves to achieve a structural change upon sudden cooling, but has nothing to do with zone melting.

The invention is to provide an induction heating coil, which makes it possible to easily produce semiconductor rods with diameters of any desired size.

According to the invention this is achieved by the fact that the induction heating coil consists of at least two parts which are connected to each other by means of screw connections and seals for the cooling.

According to the invention, the coil can be formed as a flat coil with one winding and can be divided into two halves.

According to the invention, the coil can consist of one or more windings formed by a winding part with a cooling ring-shaped inner insert for the center of the coil, where the inner insert is constructed so that it can be split into two parts and removed from the inner winding part.

However, the coil can also according to the invention be designed as one flat, annular coil or have an elongate cross section perpendicular to the plane of the rod axis and can be split into two halves. Hereby the partition for dividing the coil into the two halves can either be perpendicular to the plane of the coil or lie in this plane.

Other details and advantages of the invention are explained in more detail below with reference to the schematic drawing, in which: FIG. 1 is an enlarged perspective view of a coil divided into two parts; FIG. 2 shows the assembled, flat, annular, coil-shaped coil; FIG. 3 shows a coil as shown in FIG. 2, where the separator is in the plane of the coil, FIG. 4 shows one of several coils comprising a removable inner part; FIG. 5 is a sectional view taken along line V-V of FIG. 4 on an enlarged scale; FIG. 6 shows a coil like that shown in FIG. 4, with chilled, water-flowing internal parts, and

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FIG. 7 is a section along line VII-VII of FIG. 6th

In FIG. 1 shows two halves 2 and 3 of a coil or silver flat induction heating coil 1 of copper. In order to more clearly show the connection of the halves, these are arranged one above the other. The coil is constructed so that the two halves in the connected state contact each other along the faces 4 and 5. The references 6, 7 and 8 indicate screw holes in the connecting flanges 32 at the outer edge of the the coil for attaching screws for joining the coil halves. For sealing the cooling water duct 31 provided in the coil halves 2 and 3 there is a rubber ring 9. The inner diameter of the coil is 30 mm and the outer diameter is approx. from 80 to 120 mm. These sizes depend on the desired crystal rod diameter.

FIG. 2 shows the coil in overall condition. The seal for the seal and the joint is perpendicular to the plane of the coil.

FIG. 3 shows another embodiment in which the separator is in the plane of the coil. This joint is designated by the reference 10. Otherwise, the same reference numerals as in FIG. 1 and 2.

FIG. 4 shows an copper or silver induction heating coil 11 consisting of a winding part 12 with three turns and two insert parts 13 and 14. The insert parts are cooled by the intimate metallic contact and, after loosening of screws 15-22, can be removed from the coil 11 from its inner winding part.

FIG. 5 shows a section along the line V-V in FIG. 4. The line 23 shown in the section indicates the partition between the insert parts 13 and 14 and a ring flange 30 fixed to the inner coil winding by soldering 24.

In FIG. 6 shows a coil similar to FIG. 4. The difference is merely that the removable insert parts 13 and 14 are arranged to be water-cooled and that the winding part 12 of the induction heating coil consists of only two turns. The rubber rings 26-29 needed for sealing against the cooling water are shown to be punctured as they cannot be seen in this figure. The flow of water through the winding portion 12 of the coil as well as through the removable insert parts 13 and 14 is indicated by the arrows 25. Furthermore, the same reference numerals as in FIG. 4 and 5.

FIG. 7 shows a section along line VII-VII of FIG. 6, from which the structure of the two water-cooled insert parts 13 and 14 and the water-flowing winding part 12 is clearly shown. Again, the same reference numerals as in FIG. 4-6. The partition 23 for the two insert parts is again perpendicular to the plane of the coil.