DE1544320B1 - Device for the continuous production of a monocrystalline strip of semiconductor material - Google Patents

Description

1 2

The claimed device is based on a dimensions and surface properties of the State of the art from how he tapes obtained by the USA. Patent and is labeled on the achievement 2 927 008 and 3 096 158 is given. limited band thicknesses.

As used herein, "ribbon" means the present device avoids all of the above flat, in a first axis relatively 5 standing mentioned disadvantages by in addition to the long, relatively broad in a second axis from the United States patent 3,096,158 known (wider than long) and a second chamber is provided with an external chamber in a third axis tremendously thin (many times thinner than the width of an opening, the shape and size of which is about the or long) semiconductor crystal. Cross-sectional shape and size of the band die to be formed increasing demands for greater reliability, through which that from the first negligence of semiconductor devices and the per- manently leaking semiconductor material continuously in emde demand for reduced costs have entered the second chamber, and by between the an extensive mechanization of the process of tape and the wall of the opening in the second Kam semiconductor manufacture conditional. Such a mechanic has a built-in cooling gas supply. With this ization is based on the effective utilization of 15 device, one can now also use very thin ribbons produce discs obtained from grown crystals with a thickness of about 0.125 to 1.25 mm, of monocrystalline material and resulted in certain Fig. 1 shows a schematic representation of a Quality improvements and cost savings. Embodiment of the claimed device, The previous techniques were, however, a perspective illustration of the single-batch mode on a FIG Treatment of a large variety of 20 guide restricted to the second chamber and individual discs. Furthermore, in Fig. 3, the embodiment of Fig. 1 is also included Processing of the crystal slices by sawing, additional means for controlling the temperature Lapping, polishing and etching prior to processing to within the device.

Semiconductor devices have a large scrap, so the figures shown in FIG. 1 shown has a gedaß only about 35% of the originally obtained enclosed cylindrical first chamber 10 in which crystalline semiconductor crystals finally to semi- continuously a rod 11 of cleaned semiconductor devices are processed. conductor material, ζ. B. silicon, is introduced through an opening in the floor of the previous techniques attempted a solution of the space. These above problem in that one is semiconductor opening with a suitable gas seal 12 material in the form of a crystalline web lined between 30. A high frequency heating coil 13, the Let dendrites grow. However, this method is arranged approximately in the middle part of the chamber 10, afflicted with many disadvantages. The creation of a melts the end of the crystal rod to form Silicon ribbon between two dendrites causes a molten mass 14, which on the end of the the dendrites from a supercooled melt become rod due to their own surface tension are growing, since dendritic growth is suppressed. Liquid semiconductor material is made from the half of the liquid level in supercooled zones melt 14 is followed by a shaping guide 16. The temperature of the dendritic growth pulled which the liquid semiconductor material too is about 5 to about 15 ° C below normal a thin, liquid ribbon 15 forms. This tape Melting point. When this supercooled zone is then through an opening 18 into the interior of a it must be pulled through a second chamber 17 with an accuracy of 40, the opening 18 from about ± 0.01 ° C working control system to about the cross-sectional dimensions of the one to be formed a substantially constant temperature of the monocrystalline band. The place where the will be. The critical heat gradient in which the crucible band receives its final shape is detailed in and in the covering system, for the upright view of the enlarged view of FIG. 2, tion of the necessary for dendritic growth. 1 cool gas passes through borrowed supercooled zone must be respected; the opening 19 into the first chamber 10. As are intricate and difficult requirements to be met by the arrows in FIG. 1 is displayed, that flows a manufacturing process. Gas between the walls of the second chamber 17 Furthermore, those are attached to the seed crystals, which one and the first chamber 10 down and becomes Set dendritic band growth in motion, to put 50 through the opening 18 into the interior of the second requirements are very critical. Chamber 17 pressed, together with the The finished semiconductor tape must also not contain any denatured tape 15 passing through this opening. third have more, so the cooling gas flowing through the opening 18 results before it is further processed application must be removed and so a controlled solidification of the liquid semiconductor continuous Make procedures impractical. 55 tape to a single crystal semiconductor tape. With It is further from US Pat. No. 3,096,158 the increasing cross-section of the crystal becomes the a device for continuously producing gas flow through the opening decreased, and the degree a single crystal ribbon of semiconductor material transferring heat from the solidifying crystal known, containing a first chamber through which the cooling gas decreases. It follows that the a solid rod made of semiconductor material is automatically reduced axially upwards 60 crystal cross-section for so long is performed, becoming a localized heating until the gas flow increases. The effect is then zone in the first chamber under advancing reversed. The cooling gas can be any gas Melting passes through, and a shaping guide which does not contaminate the semiconductor, for example an opening in the first chamber, the shape of which is helium or argon.

Size approximately the cross-section of the band to be formed 65 The single-crystal semiconductor band 20 is continuously

that corresponds. ierlich in any way, e.g. B. by means of rollers 21,

These electromagnetically operating devices 22 and 23 are withdrawn from the second chamber 17

now has shortcomings in terms of the control of and stored or continuous equipment

ORIGINAL INSPECTiP

3 4

for the manufacture of semiconductor devices pulling mechanism (not shown) can be provided,

leads. to add new bars after the first bar has been used.

It should be noted that the shape and size of the feed without interrupting the process generated crystal ribbon by the shaping guide needs. Because of this continuous supply 16 as well as the shape and size of the hole, the use of an opening in a crucible 18 is determined. The shaping guidance sensitive melt and thus an essential 16 exercises to avoid the source of contaminants due to surface tension forces. Far held together Liquid exerts a pressure, which can conventional heating means, e.g. B. a Hochcher the liquid in the form of a thin liquid- frequency heating, to produce a uniformly keitsbandes forces. Since the semiconductors are used in the through-io heated, molten zone, occurs through the guide 16 is liquid, the shape is In the device can by additional heating of the tape determined by this leadership. The guide and heat reflectors the temperature conditions In tion 16, an isothermal, rectangular plane is to be further influenced.

th through which the liquid semiconductor is so drawn. A preferred embodiment is shown in FIG

that represents the interface between the melt and 15. The device of FIG. 3 corresponds

Solid rectangular and parallel to the plane of the opening of FIG. 1, but also has a wick

tion is 18. The guide 16 can be used to maintain 33, which forms a heat trap which the

processing of the required isothermal rectangular energy of the heating coil 13 on the end of the sta-

Cross-section can be heated or cooled, so that bes 11 to form a molten mass 14

The molten ribbon 20 of semiconductor material concentrates as it is pulled through. The melted

forms. zene mass is aground on the end of the rod

The gas flowing through the opening 18 (FIG. 1) maintains its own surface tension, and 2) provides a further control of the shape of the liquid semiconductor material becomes from the melt Semiconductor tape. Since the tape is not pulled off with the wall 14 by a shaping guide 32, the opening 18 comes into contact, for which the semiconductor material the shape of a thin second chamber 17 z. B. quartz can be used. gives a liquid band. The shaping one When the liquid band 15 is in the opening 18, the guide 32 consists of a circular disk is pulled, that leads between the walls of the opening with a slit or in the middle The gas flowing through the flow and the liquid band has an opening with the shape and size of the heat off the tape and let it crystallize. 3 ° desired cross-sectional dimensions of the belt. the The gas flowing through the opening 18 creates a guide 32 at the bottom in the middle a second isothermal rectangular area, through a recess. This recess is roughly correct which the tape is pulled. This isothermal with the curvature of the surface of the liquid Rectangle will match the solidification point of the semi-mass 14 and supports the introduction of the ladder tape held; this thus crystallizes at 35 liquid material in the slot, its passage through the opening 18 and forms In the vicinity of the liquid band 15 can above then the fixed band 20. The two isothermal guides 32, a heat reflector 34 rectangular planes at 16 and 18 create a structure made of refractory material, regulated temperature zone with a heat gradient in which the maintenance of a uniform which the liquid band from the guide 16 40 supports the temperature gradient even further. Form The tape gradually passes through the opening to its solidification point is cooled. The interface between the melt in the shaping guide 32 is determined; the tem- and solid runs parallel to the rectangular temperature of the liquid belt 15 but must allisothermal planes of the opening in the guide and gradually to achieve a uniform solidification Opening 18. The tape thus solidifies evenly. The reflector 34 touches that to form a monocrystalline ribbon. Fluid band not, rather it is from him

The flow velocity, the thermal conductivity - thermal energy to maintain an equality and the specific heat of the gas are absorbed onto the belt 15 due to the temperature gradient, which radiates and reflects the temperature of the through the opening.

18 affecting the stepping semiconductor band. Gas 50 Additional heaters 31 are located approximately in the upper

mixtures, e.g. B. argon-helium mixtures, can cut the room 10 to maintain a

to achieve the desired specific, uniformly decreasing temperature gradient

Heat and thermal conductivity arranged with each flow the semiconductor ribbon. By gradual

speed can be used. If the belt cools down, distortions and other

Gas can also be used. 55 other disruptive influences of thermal shocks

As you can see, the initial deformation is avoided.

of the strip caused by the guide 16, and a preheater 30 can be used to preheat the semi-additional deformation and solidification is used by the conductor rod 11 before melting, which is through the opening 18 together with the liquid The cooling gas that passes through it produces 60 H to a temperature below its melting point. In this way, thin ribbons can point out sufficient energy. Thereby one achieves single crystal semiconductor material with certain an additional control over the melting thickness of about 0.125 to about 1.25 mm and with the end of the rod, since the different widths of about 2.5 to about 25 mm reaching the melting zone material at a constant temperature kept being produced continuously. 65 turns. The rod 11 can also at its introduction

The use of a rod or rod in the room 10 can be rotated. A twist of the

from the feed material results in a continuous rod 11 ensures uniform growth

borrowed operation. A suitable mechanical conveyor from the molten area 14 and an equal

moderate doping of the tape if a doped rod 11 is used.

Claims (2)

Patent claims: 1. Apparatus for the continuous production of a monocrystalline ribbon made of semiconductor material, containing a first chamber through which a solid rod of semiconductor material is guided axially upwards, creating a localized heating zone in the first chamber passes through a shaping guide opening in the first with progressive melting Chamber, the shape and size of which corresponds approximately to the cross-section of the band to be formed, characterized by a second chamber (17) with an opening (18), the shape of which and Size roughly corresponds to the cross-sectional shape and size of the band to be formed, through which the semiconductor material emerging from the first chamber continuously enters the second chamber, and through a cooling gas supply between the belt and the wall of the opening (18) into the second chamber. 2. Apparatus according to claim 1, characterized by a heat reflector (34) which consists of the liquid band (15) exiting the shaping guide (32) before it enters the opening (18) surrounds with a game. 1 sheet of drawings