DE1805971C

DE1805971C - Process for changing the crystalline structure of a tubular starting material, in particular made of semiconductor material, by zone melting

Info

Publication number: DE1805971C
Authority: DE
Inventors: Wolfgang Dr rer nat 8551 Pretzfeld Keller
Original assignee: Siemens AG
Current assignee: Siemens AG
Publication date: 1971-07-01

Description

Beispielsweise für Röntgenspektroskope werden einen Winkel verschieden von 0 und 90°'geneigt istFor example, for X-ray spectroscopes, an angle different from 0 and 90 ° 'is inclined

rohrförmige Einkristalle aus Halbleitermaterial, ins- und mit der kleinen Hauptachse der Ellipse einentubular single crystals made of semiconductor material, in and with the small main axis of the ellipse

besondere aus Silicium, mit einer beachtlichen Lunge Winkel von 90° bildet. .special made of silicon, forms angles of 90 ° with a considerable lung. .

(z. B. 50 cm) und einem beachtlichen Durchmesser Die Erfindung und f» Vorteile seien an Hand(e.g. 50 cm) and a considerable diameter. Let us consider the invention and its advantages

(z. B. 25 cm) sowie einer verhältnismäßig dünnen 5 der Zeichnung an Ausführungsbeispielen naher(z. B. 25 cm) as well as a relatively thin 5 of the drawing closer to exemplary embodiments

Wandstärke (z. B. 10 mm) benötigt. Gegebenenfalls erlHutert: , . , .Wall thickness (e.g. 10 mm) is required. If necessary, explains:,. ,.

sind auch ganz bestimmte Werte für die Konzentra- Fi g. 1 zeigt die Seitenansicht eines rohrförmigenare also very specific values for the concentration. 1 shows the side view of a tubular

tion von in dem rohrförmigen Einkristall enthaltenen Kristalls, durch den eine Schmelzzone hindurchbe-tion of crystal contained in the tubular single crystal, through which a melting zone passes

Fremdstoften erwünscht. wegt wird,Foreign substances desired. is moved away,

Man kann derartige rohrförmige Einkristalle durch io F i g. 2 zeigt die Draufsicht auf einen Schnitt durch mechanische Bearbeitung von zuvor durch tiegelfreies den rohrförmigen Ausgangskristall nach t< ig. l,
Zonenschmelzen gewonnenen stabförmigen Ein- F i g. 3 zeigt eine Abwandlung des Verfahrens nach kristallen herstellen. Hierzu muß eine zentrale OfI- Fig. 1, . , ,
nung in axialer Richtung aus dem stabfönnigen Ein- Fi g. 4 zeigt eine Draufsicht aur die tieizeinnchkristall herausgebohrt werden. Diese Bearbeitung ist 15 tungnach Fig. 3, , , _
insbesondere bei langen und dicken stabförmigen · F i g. 5 und 5 a zeigen eine besondere Heizeinrich-Einkristallen sehr aufwendig und zeitraubend, da die tung für ein Verfahren nach den F1 g. 1 bis i.
Gefahr besteht, daß die Wand des rohrförmigen Ein- Der in F i g. 1 dargestellte rohrförmige Ausgangskristalls unter Ausbildung von Sprüngen platzt. kristall 101 hat kreisringförmigen Querschnitt und Ferner wird der rohrförmige Einkristall durch das ao besteht aus Silicium.Such tubular single crystals can be obtained by io F i g. 2 shows the top view of a section through mechanical processing from previously through crucible-free the tubular starting crystal to t < ig. l,
Rod-shaped inputs obtained from zone melting. 3 shows a modification of the process according to the production of crystals. For this purpose, a central OfI Fig. 1,. ,,
tion in the axial direction from the rod-shaped single figure. 4 shows a plan view of the monocrystals being drilled out. This processing is 15 according to Fig. 3,,, _
especially with long and thick rod-shaped · F i g. 5 and 5 a show a special Heizeinrich single crystals very complex and time consuming, since the device for a method according to the F1 g. 1 to i.
There is a risk that the wall of the tubular inlet in FIG. 1 shown tubular starting crystal bursts with the formation of cracks. crystal 101 has a circular cross section, and further, the tubular single crystal through the ao is made of silicon.

Material des Bohrers und durch die beim Bohren Der Ausgangskristall 101 ist in einer Halterung 102 verwendeten Kühlmittel in unerwünschter Weise ver- mittels dreier Schrauben 103, die untereinandei unreinigt. Außerdem ist der Durchmesser von durch gleichen Winkelabstand haben, befestigt. Der Deuttiegelfreies Zonenschmelzen oder durch Ziehen aus lichkeit halber sind die Halterung 102 und der Auseiner in einem Tiegel befindlichen Schmelzflüssigkeit 35 gangskristall 101 teilweise geschnitten gezeichnet, gewonnenen stabförmigen Einkristallen auf etwa und es sind nur zwei, der drei Schrauben 103 dar-7,5 cm begrenzt. gestellt. „.»... ,Material of the drill and through which the starting crystal 101 is used in a holder 102 coolant in an undesirable manner by means of three screws 103 which are uncleaned among each other. In addition, the diameter is fixed by having the same angular distance. The Deut crucible-free zone melting or by drawing from friendliness half the holder 102 and the ofa in a crucible contained molten liquid 35 gear crystal 101 are drawn partly in section, obtained rod-shaped crystals about and there are only two of the three screws 103 dar-7.5 cm limited . placed. "." ...,

Aus der britischen Patentschrift 1098 696 ist An einem Teil 106 der unteren Stirnfläche des bereits ein Verfahren bekanntgeworden, mit dem ein rohrförmigen Ausgangskristalls 101 ist ein relativ rohrförmiger Einkristall ohne die oben beschriebenen 30 dünner einkristalliner Keimkristall 107 angeschmolmechanischen Bearbeitungsvorgänge hergestellt wer- zen, der in einer Halterung 108 befestigt ist. Der den kann. Bei diesen Verfahren wird von einem rohrförmige Ausgangskristall 101 ist von einer polykristallinen Rohr ausgegangen, an dessen unteres ellipsenförmigen Heizeinrichtung 104 umschlossen, Ende ein einkristalliner, rohrförmiger Impfkristall wie aus dem in F i g. 2 dargestellten Schnitt in Höhe angeschmolzen wird. Die Schmelzzone wird dabei 35 dieser Heizeinrichtung hervorgeht. Diese Heizmittels eines scheibenförmigen Heizkörpers erzeugt. einrichtung 104 kann eine mit hochfrequentem Dieser Heizkörper ist mit öffnungen versehen, durch Wechselstrom gespeiste Spule mit einer einzigen die das schmelzflüssige Material beim Aufwärts- ebenen Windung oder ein elektrisch beheizter Strahbewegen des Heizkörpers hindurchtritt und am Impf- lungsheizer sein. Die Heizeinrichtung 104 beheizt kristall in einkristalliner Form anwächst. Bei diesem 40 eine im rohrförmigen Ausgangskristall 101 erzeugte Verfahren muß also von einem einkristallinen, rohr- Schmelzzone 105, die, wie aus Fig. 5 hervorgeht, förmigen Impfkristall ausgegangen werden. ebenfalls die Form einer Ellipse hat.From British patent specification 1098 696, a method has already become known on a part 106 of the lower end face of the, with which a tubular starting crystal 101 is a relatively tubular single crystal without the above-described 30 thin single crystal seed crystal 107 melted mechanical processing operations Bracket 108 is attached. Who can. In this method, a tubular starting crystal 101 is assumed from a polycrystalline tube, at the lower elliptical heating device 104 of which is enclosed, the end of which is a monocrystalline, tubular seed crystal as from the one in FIG. 2 section shown is melted in height. The melting zone will emerge from this heating device. This heating means produced a disc-shaped radiator. Device 104 can be a high-frequency radiator with openings, an alternating current fed coil with a single coil through which the molten material passes during the upward turn or an electrically heated jet movement of the radiator and be on the inoculation heater. The heating device 104 is heated and grows in a single-crystal form. In this process, which is produced in the tubular starting crystal 101 , a single-crystal, tubular melting zone 105, which, as can be seen from FIG. 5, is shaped as a seed crystal, must be assumed. also has the shape of an ellipse.

Die vorliegende Erfindung bezieht sich auf ein Die ellipsenförinige Schmelzzone 105 liegt in einer Verfahren zum Verändern der kristallinen Struktur Ebene, die zur Achse 109 des rohrförmigen Auseines rohrförmigen Ausgangskristalls, insbesondere 45 gangskristalls 101 weder parallel noch senkrecht ist. aus Halbleitermaterial, durch Anschmelzen eines ein- Sie wird ausgehend von der Anschmelzstelle 106 des kristallinen Keimkristalls am Ende des rohrförmigen stabförmigen Keimkristalls 107 an der unteren Stirn-Ausgangskristalls und Hindurchführen einer fläche des rohrförmigen Ausgangskristalls 101 min-Schmelzzone durch den Ausgangskristall ausgehend destens einmal durch diesen Ausgangskristall 101 von der Anschmelzstelle des Keimkristalls. 50 hindurchbewegt. Soll die KonzentrationsverteilungThe present invention relates to a ellipsenförinige the melt zone 105 is located in a method for altering the crystalline structure plane to the axis 109 of the tubular Auseines tubular starting crystal, in particular 45 crystal gear 101 is neither parallel nor perpendicular. of semiconductor material, by melting a single melting zone through the starting crystal, starting from the melting point 106 of the crystalline seed crystal at the end of the tubular rod-shaped seed crystal 107 at the lower end of the starting crystal and passing a surface of the tubular starting crystal 101 min melting zone through the starting crystal at least once Starting crystal 101 from the melting point of the seed crystal. 50 moved through. Should the concentration distribution

Die der Erfindung zugrunde liegende Aufgabe von im Ausgangskristall 101 enthaltenen Fremdbesteht darin, ein solches Verfahren gegenüber den stoffen verändert werden, so können auch mehrere bisher bekannten Verfahren zu vereinfachen. . Schmelzzonendurchgänge erforderlich sein.The object on which the invention is based for the foreign contained in the starting crystal 101 is to change such a method with respect to the substances, so that several previously known methods can also be simplified. . Melt zone passages may be required.

Die Erfindung besteht darin, daß ein stabförmiger, Zu diesem Zweck wird der rohrförmige Ausgangseinkristalliner Keimkristall an einem Teil einer Stirn- 55 kristall zum Beheizen der Schmelzzone so relativ zur fläche des rohrförmigen Ausgangskristalls ange- Heizeinrichtung 104 mit der Form einer Ellipse in schmolzen und daß ausgehend von der Anschmelz- Richtung des Pfeiles 112 bewegt, daß die Achse des stelle eine ellipsenförmige Schmelzzone durch den Ausgangskristalls gegen die große Hauptachse 110 rohrförmigen Ausgangskristall bewegt wird, die in der Ellipse in einem Winkel verschieden von einer zur Achse des rohrförmigen Ausgangskristalls 60 0 und 90° geneigt ist und mit der kleinen Hauptwederparallelen noch senkrechten Ebene liegt, achse ill der Ellipse in Fig. 2 einen Winkel von The invention consists in that a rod-shaped, For this purpose the tubular starting single crystal seed crystal is melted on part of a front crystal for heating the melting zone so relative to the surface of the tubular starting crystal heating device 104 with the shape of an ellipse and that starting moved from the melting direction of the arrow 112 so that the axis of the point an elliptical melting zone through the starting crystal is moved against the major axis 110 tubular starting crystal, which in the ellipse is at an angle different from one to the axis of the tubular starting crystal 60 0 and 90 ° is inclined and lies with the small main weder parallel nor perpendicular plane, the axis ill of the ellipse in Fig. 2 an angle of

Zum Beheizen der Schmelzzone wird vorzugsweise 90" bildet. Der Neigungswinkel der Achse 109 zurFor heating the melting zone, 90 "is preferably formed. The angle of inclination of the axis 109 to

eine mit hochfrequentem Wechselstrom gespeiste großen Hauptachse 110 der Ellipse liegt vorteilhaft a large main axis 110 of the ellipse fed with high-frequency alternating current is advantageously located

Spule mit einem Querschnitt in der Form einer im Bereich zwischen 25 und 65°. VorzugsweiseCoil with a cross-section in the shape of a in the range between 25 and 65 °. Preferably

Ellipse verwendet, die den rohrförmigen Ausgangs- 65 beträgt er 45".Used ellipse, which is the tubular starting 65 he is 45 ".

kristall umgibt und durch die der rohrförmige Aus- Als Heizeinrichtung 104 kann auch eine mit hoch-crystal surrounds and through which the tubular outlet As the heating device 104 can also be a high-

gangskristall so hindurchbewegt wird, daß seine frequentem Wechselstrom gespeiste Flachspule mitgang crystal is moved through so that its frequented alternating current fed flat coil with

Achse ßegen die große Hauptachse der Ellipse in mehreren in einer Ebene liegenden Windungen undAxis ßegen the major axis of the ellipse in several turns lying in one plane and

Claims

elliptical cross-section or a coil with a multi-electrically heated radiant heater with the shape

reren elliptical turns' in the shape of an ellipse.

oblique cylinder having an elliptical base and deck to be used through the tubular output crystal hinfläche that the tubular off through moving melt zone may surround gear crystal by two, too, the pipes 5 fed with high frequency alternating current coil type starting crystal 101 is so relative to the Coil are heated, of which one moves inside the way that its axis 109 is arranged against the large main tubular starting crystal and the axis of the cross-sectional ellipse of the coil in one the other surrounds this AusgungskristaU outside, angles different from 0 and 90 ° inclined is and with Both coils are preferably one or more of the minor axis of the ellipse forming an angle of 90 ° io windy flat coils with an elliptical cross section. lie in the same plane, the two coils are

Due to this inclination of the axis 109 of the tube in phase opposition one behind the other, that is, they flowed through the axis of the cross-sectional ellipse of the heating device 104 in the opposite direction from the flow through the axis of the cross-sectional ellipse of the heating device 104 against the large main crystal. F i g. 5 shows in the vertical direction from above it ensures that the material seen in the wall is two such antiphase, one behind the other, of the tubular starting crystal 101 when single-turn coils 513 and 514 pass through the melting zone 105 starting from an elliptical cross-section, which lie in one plane the melting point 106 of the monocrystalline seed crystal and between which the tubular starting crystal 107 is uniform and monocrystalline from crystalline crystal 501, the cross section of which has the shape of a circle. ao ringes has, is moved through. The opposite

For heating the melting zone 105 , a current flow in both coils is indicated by the arrows 516

Electron beam or a plasma discharge are suitable. ^and , ⁵¹ ? indicated. For the sake of clarity is

Furthermore, it can be advantageous above and / or only the cross section viewed vertically from above

below the heating device 104 further heating ^de r exactly between the coils 513 and 514 befind-

facilities, e.g. B. with high-frequency alternating * 5 borrowed parts of the starting crystal 501 dashed

current-fed coils or radiant heaters, to be drawn. In the space between the

arrange the tubular starting crystal 101 two coils asked the field strength of the coils

preheat before the passage through the melting zone and / or a maximum of the outgoing electromagnetic field

reheat after the melt zone has passed. Here- ^m alen value. The power supply lines 515 to the im

in particular, the dislocation density 3 ° inside the tubular starting crystal 501 can be

Induction heating coils 514 that are downgraded in the crystallized monocrystalline material are advantageous

set. bent to an elongated U-shaped bracket,

It is advantageous to arrange the heating device 104 in a plane between its legs of the tubular off-horizontal plane, since in this way the single crystal 501 also lies in a horizontal plane during the relative movement during the melting zone 105 , 35 of the melting zone passage. This ensures that the molten liquid stood this U-shaped bracket from the tubular from the melting zone 105 while the melting starting crystal 501 is expediently so large the zone passage does not drip off. chosen so that the brackets are not used as additional heating

To change the wall thickness of the tubular device act. Regarding the inclination of the axis

Starting crystal 101 can be the distance between the ends 4o of the tubular starting crystal 501 opposite

of this starting crystal during the passage ^the main axes of the cross-sectional ellipses of the two

the melting zone can be changed. For thickening ^s P ^{pillars 51?> 514 and} S ^falls in the same g Fi as with. 1

the wall of the tubular starting crystal 101 illustrated method.

The brackets 102 and 108 and thus FIG. 5a shows a perspective view of the ends of the starting crystal 101 during the 45 coils 513 and 514.
Melt zone passage moved towards each other in the axial direction. Accordingly, the pipe claims:
wall is thinned by the holders 102 and 108 and 1. Method for changing the crystalline so that the ends of the tube are moved away from one another in the axial direction of a tubular starting crystal during the passage through the melt zone. in particular made of semiconductor material, by means of

Corresponding to Fig. 3, in the same parts with the melts of a single crystal seed crystal on

same reference numerals as in Fig. 1 b <: w. Fig.

2 end of the tubular starting crystal and

are provided, the tubular starting crystal can pass a melting zone through the

101 also relative to an annular heating device- 55 starting crystal starting from the melting point

device 304 are moved, which at the long power supply point of the seed crystal, thereby identified

Rungen213 attached and inside the tubular one shows that a rod-shaped, monocrystalline

Starting crystal 101 is arranged and with which the seed crystal on a part of an end face of the

Melting zone 105 is heated. tubular starting crystal melted

As can be seen from Fig. 4, the Heizeinrich- 60 and that starting from the melting point has a

device 304 has the shape of an ellipse. With regard to the cUipple-shaped melting zone through the tubular

Inclination of the axis 109 of the starting crystal 101 shaped starting crystal is moved, the 111

to the two main axes 310 and 311 the transverse one to the axis of the tubular output

In the sectional ellipse of the heater 304 , the same crystal applies neither parallel nor perpendicular

as in the case of the heating device 104 according to FIG. I. 65 level is located.

Here, too, the heating device 304 can have a 2. Method according to claim 1, characterized in that

high-frequency alternating current fed flat or indicates that for heating the Schmdz-

7vlindersnulc with an elliptical cross-section or a zone with high-frequency alternating current

1 80δ

fed coil with a cross section in the shape of an ellipse is used, which is the tubular Surrounds the starting crystal and through which the tubular starting crystal is moved that its axis differs at an angle from the major major axis of the ellipse is inclined from 0 and 90 ° and an angle of 90 ° with the minor major axis of the ellipse forms.

3. The method according to claim 1, characterized ge ίο indicates that for heating the melting zone an annular radiant heater with the Shape of an ellipse is used, which surrounds the tubular starting crystal and through the the tubular starting crystal is moved through so that its axis against the large The main axis of the ellipse is inclined at an angle different from 0 and 90 ° and with the small main axis of the ellipse forms an angle of 90 °.

4. The method according to claim 1, characterized in that the melting zone by a coil fed by high-frequency alternating current or a ring-shaped radiant heater is heated, which are located inside the tubular starting crystal.

5. The method according to claim 1, characterized in that the melting zone by two In opposite phase, series-connected coils is heated, one of which is inside and the other is outside the tubular starting crystal.

6. The method according to claim 1, characterized in that the distance between the ends of the tubular starting crystal is changed during the passage of the melting zone.

1 sheet of drawings