PROCEDURE AND DEVICE FOR MELTING IN ZONES, WITHOUT A CRUCIBLE, A ROD OF CRYSTALLINE SEMICONDUCTOR MATERIAL TO WHOSE LOWER END IS FUSED A MERMINATION CRYSTAL.

Description

'· -ίφ 25 / 78 / ε. S1UHS0 CGK-SUlEH7.À Mll UIBUMMSLAIiO-Piazzu Castolio, 2 Description of the invention entitled "Method and device for melting in zones, without a crucible, a rod of crystalline semiconductor material to whose lower end a germination crystal is attached by melting" by the firm SIEMENS AKTDSNGESELLSCIiAFT with registered offices in Berlin and Munich (Germany) 16 FEB. 1978 filed on 2 0273 A / 78 The invention concerns a process and a device for melting in zones, without a crucible, j I a rod of crystalline semiconductor material, which at its lower end is provided with the crystal- 1 Λ I | germination thread, joined by fusion, and is supported j II | vertically at both ends, where the end j of the rod containing the germination crystal ! ii The crystal is supported, after passing through the molten zone, in the conical area of ​​the rod above the germination crystal or in which a system of rods is used for support, which is coupled with the support of the germination crystal, but in such a way as to be movable with respect to the support, and is brought at least partially into contact with the conical area of ​​the rod above the germination crystal. A device of this type is known from the West German patent application published 25°50, MILAN-Piazza I ί In this device, according to an example of particularly convenient construction, a frame is used to support the conical area of ​​the rod above the twinning crystal. This frame is rigidly connected to the twinning crystal support and on which at least three hinges are applied, which are provided with orientable arms. The support occurs by lifting, by means of deflecting rollers, the orientable arms located on the hinges, until the orientable arms fall on the cone of the rod. In particular, the The swivel arms are made of light metal and are S-shaped in order to enlarge their support surfaces on the rod cone. The problem addressed by the present invention consists in a further improvement of the stability of the support of very long and thick dislocation-free silicon single crystals during melting. I i zones without a crucible. j ! According to the invention, this problem is solved by using a rod system, which is made up of three orientable arms, which are arranged symmetrically and can be operated by hinges, and in which the support on the rod cone is caused by a solid connection between the rod cone and the support surfaces of the orientable arms. Sftr.!0 CD'niUHIA BSEV0FTI JMtMAKH f.-ilLAÌJO· Piazza Castello. 2 I to the cone of the rod, within the scope of the invention,......! I i ! . | the support, can be caused by electromagnetic forces. i C.nn a support, of this kind, it is guaranteed that, independently of the. radiant heat still persisting at the point of support, a safe support can be achieved on the cone of the rod and the formation of vibrations can be safely prevented, ............ . . i . ....... .. .. the overturning of the arms oriented towards the cone of the rod can be achieved by means of a ring, which can be moved in the axial direction and concentrically surrounds the system of rods, moving, I .the ring upwards,, or by means of the actuation, of , jj | A traction spring connected to a pulley. The action and therefore the tilting of the orientable arms, the cone of the rod, occur in small steps, in an electromagnetic way, through an electromagnetic brake which is fixed to a shaft and receives a continuous impulsive current. With the gradual lifting of the arms THE The .o.rie ut ab c li by means of the electromagnetic brake are si-........ I ! .purely avoid excessive kinetic energy, which could lead to violent and unwanted shaking of the support arms and the rod to be supported and therefore to vibrations of the rod itself, with the risk of drops falling from the...molten mass. Within the scope of the invention, the apppg= STUDIO cdnjuìehzà brevetti jawm MILANO'Piazza Castello, 2 -jgi.o can however also be caused by contact pads which are applied on the support surfaces of the The orientable jbrtf.cci and are made of a substance that adheres to the rod, .. . ; The invention is explained in greater detail below, taking into consideration possible embodiments and making reference to figures 1 to 2. Figure 1 shows a device, in perspective, during the support phase, i ! : _j_ .......figure k shows the arrangement of the swivel arm before the support, where a traction spring and an electromagnetic brake are used to operate the swivel arms and ; ] figure p shows a device, I | in which easily meltable contact pads are used for support. j In figure 1 a germination crystal ί , ' ........... | ! is fixed | J J single crystal silicon rod h ^ in a support 5*. The germination crystal b is joined to the lower end of the silicon rod ?. After the junction has melted, a so-called bottleneck constriction is formed by moving the supports of the rod apart from each other in the axial direction at a relatively high speed. This constriction a .;i ; The bottleneck 3 causes a single crystal growth without dislocations. Since both the silicon rod A and the germination crystal A rotate around their axis (cf. rotation arrow 15), There is a danger that the end of the silicon rod 2, connected to the bottle-neck constriction 3, begins to oscillate when the molten zone (not shown in the figure) has moved too far from the junction between the germination crystal A and the silicon rod 2 and the weight bearing on the bottle-neck constriction becomes too large. In the case of... bottlenecks... Silicon chips with a diameter of A or rarely this occurs at... ......... - for example, when the molten zone has a distance of 70... from the bottleneck 3" the width of the I ' 1 *, the zones often become so large that the zone melting process must be performed. This necessity is avoided by the rod system . .16.. reproduced in figure _1, which is made up of three orientable arms .11 arranged symmetrically, and operated by hinges A, and rigidly connected to the support of the crystal of... I nation .5. ...On the extension of the orientable arms 1.,... !preferably made of silicon, a metal blade 7 is applied, . which, in its resting position, is located in the air gap 19 of an electromagnetic coil 9,. which is; - 6 - $R!D|0 CGMSiiLErￃﾬZA ￎﾕ:,ￎﾯￎﾯￎﾠￏﾊￎﾯ UUMMNMILANO-Piazza Castrilo, 2 -, provided with a hinged anchor 10 and a premanent spring 11 and acts as a brake. The electromagnetic coils -9·· They are electrically connected in series, where one pole is located on the collector ring 12, isolated on the rotation axis 1.4 of the support of the twinning crystal 5, i ^ H while the other pole is connected to the ground. .With .1;» a sliding contact is indicated; the rotation axis 1^. also provides for the closing of the electric circuit. ............... . ì [ ......... ... . When support is required on the . center, ^. through a mechanism that can be operated outside the zone melting chamber (see the double arrow 1?).. and .through 1.' a.» ..in 16, ..which.....surrounds. the..rod system .16,. by moving .. , · »· the ring upwards, the orientable arms...1 are, re = ........... tipped from their..position, represented in the drawing. .... ! The J.cor dash and dot lines towards the rod cone ............ . (2). By.....the contact of the orientable arms 1, which. .. . are made, for example, of silicon, and are stopped electromagnetically, with the rod cone 2, an optimal support effect is achieved simultaneously at three points of the rod cone. 2. ... ....., i................................................ Spring .figure ? is. represented another form, of ...realization according to the concept of li1 invea-...... tion. for greater clarity, in..this figure | only one of the three supports has been reproduced.In the present case, the tilting of the support arms towards the rod cone occurs by means of a. elastic force ..27· c the retention--.Inuta against the .cone of the rod occurs by means of an electromagnetic .brake 20, .During the tilting, .the electromagnetic brake 20 is .activated..in periodic node,-so that the orientable arms 1 act as support levers_ <gio . ei ribaltano .a .piccoli passi ..ve reo la bacchetta, da apn.^poggiare. Anche nella posiziono zero {posizione, iniziale)jdel braccio di appoggio 1, rappresentata..nella figura 1', _i2il_ braccio viene trattenuto, con .11 azionanontc del freno.. . .jele.ttroEiagnetico 20, in antagonismo. alla forza della molla [ ..idi-trazione 27,.. che. tende a provocare una rotazione., .versoi _ -illaD to, tramite la carrucola .26, .la molla di-trazione 27 ., .. ! ] -ie se reità un . momento . di rotazione 30 sdii'asso .2h» ...Nella.,Jfor&a rappresentata, nel disegno, il freno elettromagnetico.220- è costituito dalla bobina 21, dal nucleo., di ferro. 22.. e,Jdall'àncora a cerniera . 31, la quale ,, allorché...la bobina vie _,ne .percorsa da ..una .corrente , trattiene... il. disco .a . membrana ! -Ì23 e quindi anche il .braccio .di appoggio ..1 montato sullo ,; i ;ste.sso asse Zk. su ..cui. «...montate il disco.Naturally, an electromagnetic brake can also be used, with an internal winding, which, in this case, can be diopoetocossar* 1 --. Mind on axis 2i,.... After... the. tilting of the.....support arms. 1 direction., the silicon rod ». the arms are.held, in the.,support position. by_a flow of permanent brake current and the tt romagne tic P....20. and in. this ·<φ BUiVtlìt J«rfK CONSULTING STUDIO Mn-ANO-P'p-W-aCiìuUfiii),? . They also stabilize very heavy rods. After having completed the zone melting process and after having j Once the single crystal is turned, the arms are rotated backwards to the zero position, where they are held electromagnetically again. As in the form of real ratios, using figure 1, the electrical connections, 2δ or 2.9, of the coil and magnetic field 21 are located on the rotation axis of the support of the germination crystal (not shown in the figure). In figure 2, the germination crystal of single crystal silicon, the support of the germination crystal. the spare silicon rod .....—..........'4P.J1 so-called bottleneck constriction are - —......1-indicated with. the same reference numbers as in ................-.figure 1. ....................................................... .................... .....With the rod system 35 reproduced in figure .3 the formation of oscillations above the bottleneck 2 is prevented. This system of rods consists of a support plate .36, ..which is rigidly connected to the support of the germination cylinder ....but in such a way that it can be lifted from its base, and on which are &p* Piicete .symmetrically ..three hinges hGì made up of J took the support ttjL_39 and. axes *+0, to which are attached ! | adjustable arms. 3.8 acting as support arms. I ì 1} I - _ or _ SlUDiO ΜΙϋίΙΜΪΛ PATENTS JAiliAAUM . Fv! i !_ / » NO ” w<_ÌOvdOj '2é -.............— j.......- When support on the cone is required, by means of....... ......; Mechanism operated outside the firing chamber;........... ----------- -----j zoned ring (see... the double arrow A?) and by means of the tilting ring A2, which surrounds the support plate ..... .. - ...... - * 36,* by moving the tilting ring A 2 upwards, . - ......... ..... i ..the driving elements Λ1.. are touched, bent - .[ .towards the outside., and applied to the swivel arms. 3C. .and its-........ *." 1 . ..j..cassively., .after, a further, lifting of the ring........ •..........[.of .tipping Al', the orientable arms $8 .are, re- - .............: .tat:. from their position, represented in the .drawing..with... . ..ￂﾷ￢ﾖﾺ￢ﾙﾦ. l ' ￂﾻ i = : [..line and dotted line towards the cone of the rod (1)* -............| By means of the silver chloride pellets A3, which..... ....... . ,·. ? i - ........ _.....j_s.Qao applied., to the silicon pins AA at the ends of the orientable arms 36 .and melt at 1- ........... ..............j.upon contact with the hot cone of the rod (A), i -------- ----------; .and an optimal support effect is achieved...contemporaneously= ._ _______ ....................... _ . simultaneously at three points of the cone of the rod.......As the melting process proceeds, in zones, these contact points. ....................i solidify and establish a solid connection with .......... ..... ... the cone of the rod*. ......1......... . .............. of chloride. use ............Instead of contact tablets. of silver fluxing at Ay-p^C, you can also use contact tablets of silver iodide. Melting point: 33.6,.8°C) copper chloride (melting point 1.22°C) or caustic (melting point: ^60^0)1 | i -..........- 1 lt l · | · »

Claims

1. - 10 SMINO C0N$tiUtￃﾌ7ￂﾫ ￎﾲ-'1 MILAN* P'~h'zi. ￂﾫ .XL_sl.oi￢ﾀﾙuro. by a.rgcn.tp , ha. the merit, .of not dosopiporei even ....ￂﾩeight Inaction.of a Face, temperature. With j>v ('indicated...... ..jUfttc-e. of rotation. dpl...,epstcgno .de 1 germination crystal- . I jsixwe· ....... ..... . ..... ..... ..... j __j........... ..........Kivendications . . Procedure for.... the preparation of a crucible, without a crucible, a bowl of crystalline semi-conductor material, which at its lower end is provided with the germination crystal, joined by fusion, or is supported vertically at the two ends, in which the end of the rod containing the germination crystal is supported,..... .dpPP ...the Landscape of the fused zone, in the COHÌCO zone of the rod above the germination crystal and in which a system of rods, the i ..which is coupled with the support of the germination crystal..), but in such a way as to be movable ...with respect to the support, and is brought, at least partially, into contact with the conical area of ​​the rod above the germinoi crystal characterized by the fact that a system of doors is used,.....which ...is made up of three orientable arms, which are arranged symmetrically and can be operated by hinges, or in which the support on the cone of the rod is caused by a solid connection ;;between the cone of the rod and the support surfaces of the orientable arms on the cone of the rod. 11 $ￎﾠￎﾦￎﾙ9 COHStUMA B&YtHI IhniMMlLANO-Pk-.TOi Castello, 2 .1.2.ￂﾷ:. Method according to claim 1, characterized by the fact that the support is caused by electromagnetic forces. Method according to claim 2, characterized by the fact that the.the tilting of the orientable arms towards the rod cone is carried out by means of a ring, which is movable in the axial direction and concentrically surrounds the rod system, by moving the ring upwards, i..Jir.— Method according to claim 2, characterized in that the tilting of the orientable arms towards the rod cone is carried out by actuating a tension spring placed with a ring, ......5.— Method according to claim 2, characterized in that Zfit.c cìal fact .that the vernier tilting of the orientable arms .......νρχΕ.0 the cone..of., rod occurs in small steps, electromagnetically, by means of an electromagnetic brake, i .............. .....~ I ._.which is fixed to a shaft and receives a direct current; irne .lsiva....... ! ' ' ' ......_ " ' .............. . 6.- Method according to claim 2, characterized by the fact that instead of a small-step overturning, a slow approach is implemented by braking the movement using an eddy current brake. 2.- Method according to claim 1, characterized by the fact that the support is caused by means of contact pads, i.e. cones applied to the support surfaces of the orientable arms and are made of an adhesive substance or of a substance that fuses together with the cone of the rod. 8.- Process according to claim 7, characterized by the use of contact pads made of silver chloride (AgCl), silver iodide (Agl), copper chloride (CuCl) or solid alkaline hydroxides. 9.- Device for carrying out the process according to claims 1 to 3, characterized by a rod system consisting of three symmetrically arranged orientable arms operated by hinges, by a ring concentrically surrounding the rod system and movable from the outside in an axial direction, by electromagnetic brakes coupled with the hinges and the orientable arms and electrically connected in series or in parallel, as well as by rotatable electrical connections applied to the rotation axis of the germination crystal support, 10.- Device for carrying out the method according to claims 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 20, 21, 22, 23, 24, 25, 26, 27, 28, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, 100, 101, 102, 103, 104, 105, 106, 107, 108, 109, 110, 111, 112, 113, 114, 115, 116, 117, 118, 119, 120, 121, 122, 123, 124, 11,- Device according to claim 9> characterised in that the orientable arms, at least at the end facing the cone of the rod, are made of silicon.

12. Device for carrying out the process according to claim 1, characterised in that a support plate is provided as a rod system, rigidly connected to the support of the germination crystal, for at least three symmetrically arranged hinges, and in that orientable arms are fixed to the hinges, which are operated, by means of drag elements, by means of a ring surrounding the support plate and movable in the axial direction, and furthermore in that the ends of the orientable arms, which face the cone of the rod, are provided with pins of inert material having support surfaces made of an adhesive substance or of a substance which fuses with the cone of the rod.

13. - Device according to claim 12, characterized in that the pins, which carry the supporting surfaces, are made of silicon or quartz and the supporting surfaces themselves are made of silver chloride, silver iodide, copper chloride or solid alkaline hydroxides. τ ........ ..... · · ..... ......_ ......- I 1^.- Device according to claim 12, characterized in that the orientable arms and the driving elements, applied to these arms and curved in a semicircle towards the outside, are made of light metal sheets, ..........

15. Device according to claims 12 to 14, characterized in that the ring, which actuates the orientable arms, can be moved in the axial direction by means applied to the outside of the zone melting device. PATENT CONSULTATION STUDY ........................ -......-