DE102009021825B3 - Pick-up cone for silicon seed rods - Google Patents

Abstract

The invention relates to a receiving cone for silicon seed rods in reactors for the addition of polysilicon. The invention has for its object to provide a receiving cone for silicon seed rods, which ensures a good contact of the silicon seed rods used and a significant reduction of the heat output is achieved. This is achieved by the fact that the receiving cone consists of a rotationally symmetrical basic body (2) with a one-piece clamping element (3) which can be inserted centrally in this position for receiving the silicon growing rod (1), the basic body (2) being like a pot lid for receiving a Connection bolt (4) is recessed and wherein the edge (5) can be inserted into the current feedthrough in the bottom of the reactor, wherein the items silicon seed rod (1), clamping element (3), base body (2) and receiving part of the current feedthrough and terminal bolt (4 ) are positively and non-positively nestable.

Description

The The invention relates to a receiving cone for silicon seed rods in reactors for addition of polysilicon.

polysilicon is for the most varied applications in large quantities z. B. for manufacturing needed by solar cells. Because polysilicon in the required purity in nature is not or not sufficiently available This must be prepared by a suitable method.

For the production of polysilicon, for example, the so-called Siemens process has been developed, in which a plurality of silicon culture rods, also referred to as Slimrods, introduced into a reactor and there in a vapor deposition Polysilicon attached to these. Prerequisite for this is u. a. a sufficient temperature of the silicon thin rods, which is close to the melting temperature of silicon must lie. To achieve this, the silicon culture rods by means of Resistance heating to the needed Temperature heated up.

To become the silicon seed rods in pairs adjacent to suitable holders in the reactor set up with the silicon thin rods at the upper free end elekt risch connected to each other. As holders for the silicon seed rods are usually Recording cone made of graphite used, either one or more parts accomplished are. The receiving cone serve both the electrical contact, as well as the secure mechanical attachment of the silicon seed rods, the through the layer growth during the Coating process significantly increase in weight. In addition, should the finished silicon rods preferably can be easily removed from the mounting cone.

For the deposition of polysilicon by a chemical vapor deposition (commonly referred to as Chemical Vapor Deposition (CVD)) on the silicon thin rods at 1100 ° C, high purity trichlorosilane (SiHCl ₃ ) is used by disproportionation according to the formula 4SiHCl3 → Si + 3SiCl4 + 2H2 takes place. The thereby released silicon accumulates on the silicon seed rods.

Of the Reactor usually consists of a quartz bell with a protective outer metal bell, including the bottom plate and the necessary current feedthroughs is water cooled.

at the simplest version, d. H. in the one-piece version, become the silicon seed rods in an opening plugged in the cone. It is understood that in this case a sufficiently good electrical contact can only be guaranteed can if the opening in the receiving cone as possible exactly corresponds to the contour of the einzustckenden silicon rod.

at the multipart design consist of the receiving cone of a body and in these usable Bake the clamping, by means of a union nut be braced against the inserted silicon seed rod.

Important is at the receiving cones that the best possible electrical Contact between the current feedthrough through the reactor wall to the receiving cone, the receiving cone and the Silicon seed rods guaranteed becomes. About that In addition, the heat must drain at the interface power feed, Recording cone and silicon rod to be as low as possible. The cited documents meet these requirements Not.

In the DE 600 32 813 T2 which relates to a CVD method and device for depositing polysilicon, with which silicon is deposited on silicon tubes, the above-cited Siemens method is described in more detail. The silicon tubes are held by graphite supports in a reactor device.

A similar graphite holder also goes from the US 3,200,009 A out.

From the DE 12 05 950 B shows a holder in a device for the deposition of semiconductor material from the gas phase on rod-shaped carriers made of semiconductor material of the same lattice structure and a method for their preparation. Again, graphite holders are used for silicon thin rods, which are conical or conical on their front side. The holder can also be designed as a terminal in that it is partially halved at the drilled end such that one half is separated by a vertical axis to the incision incision. Both halves are held together by a graphite ring.

Of the Invention is now based on the object, a receiving cone to create silicon seed rods, in which ensures good contact with the silicon seed rods used and a significant reduction in the heat output is achieved.

The object underlying the invention is at a receiving cone for silicon on breeding rods in reactors for the deposition of polysilicon solved in that the receiving cone consists of a rotationally symmetrical body with a centrally inserted into this at the highest position integral clamping element for receiving the silicon growing rod, the body is pot-like recessed for receiving a connecting bolt and its edge can be used in the current feedthrough in the bottom of the reactor, wherein the items silicon seed rod, clamping element, body and receiving part of the current feedthrough and terminal bolts are positive and non-positive plugged into each other.

The Particularly low-mass construction of the receiving cone with minimal potential Wall thickness connects with the central heat input over the Collet to a significant reduction in heat loss over the Current feedthrough and associated with a reduction of the heat demand when heating the Reactor.

Further allows The insertable into the cone and specially trained collet a safe and simple voltage of the silicon seed rods used, as well after coating, a simple removal of the coated rods. By a change The inner contour of the collet can be adapted to almost all Dimensions of silicon rods, without a change to make the basic structure.

One Another advantage of the invention is that the construction very slim and easy to perform leaves.

to Recording of the clamping element is the basic body with a centric Equipped blind bore.

In a development of the invention, the one-piece clamping element is rotationally symmetrical a jaw like formed and has a continuous, longitudinal receiving bore for the silicon growing rod.

Around the possible easy to reach, is the clamping element from both ends starting with longitudinal the same running non-continuous slots, the alternately emanating from the one or from the other end side.

To are each twice three offset by 120 ° Slots provided in the clamping element, wherein the slots of the a front opposite the slots are offset from the other end face by 60 °.

In Another embodiment of the invention is the clamping element provided at one end with a collar, with the slots, the emanating from the front side of the clamping element on the collar side, extend through the collar. The part adjoining the collar the clamping element corresponds at most the depth of the blind hole.

Around a sufficient adhesion between the inserted silicon rod and the tensioning element, and between the tensioning element and the base element to achieve, rejuvenates the blind hole in the cone-shaped.

The Blind hole should have a cone angle of 0.5-30 °, on the one hand to achieve a sufficient clamping effect and on the other hand Make sure that the clamping element is out of the basic element solve.

Farther is provided that the outer circumferential surface of the clamping element from Collar to the opposite lying front side tapered in the same cone angle, as the blind hole.

In In a further embodiment of the invention, the edge of the pot lid-like base element tapers cone-shaped to the same degree as that corresponding counterpart in the current feedthrough.

Of the Cone angle of the edge and the counterpart in the current feedthrough should be by 4 ° -5 °.

In a special continuation the invention is at least between the inclusion of the current feedthrough and the main body an electrically conductive Separating element arranged, which also formed as a diffusion barrier is and is made of silver.

Around one possible full and large-scale separation to reach, corresponds to the separating element of the negative mold of the inner contour of the basic element and on the underside of the negative-form of the connecting bolt the current feedthrough.

to Facilitating the removal of the grown silicon rod is it is advantageous if at least between the primitive and the grown Silicon rod a release agent is arranged.

This Release agent can be an electrically conductive foil or disc CFC (Carbon Fiber Reinforced Carbon) or another graphite foil and may also extend to the bottom of the blind bore.

The Invention will be explained in more detail below using an exemplary embodiment. In the associated Drawings show:

1 a side view of a receiving cone according to the invention with inserted clamping element and silicon seed rod;

2 : a sectional view of the receiving cone after 1 ;

3 : A variant of the recording cone according to the invention with inserted clamping element and silicon seed rod;

4 : a sectional view of the receiving cone after 3 ;

5 : a side view of the receiving cone after 1 ;

6 : a sectional view of the receiving cone after 5 ;

7 : a perspective view of the receiving cone after 5 ;

8th : a side view of the receiving cone after 3 ;

9 : a sectional view of the receiving cone after 8th ;

10 : a perspective view of the receiving cone after 8th ;

11 : a separating element for resting on the receiving cone 3 . 4 ;

12 : a side view of the separator after 11 ;

13 : A perspective view of the separating element according to 11 ; and

14a -D: details of the tensioning element.

The recording cone according to the invention for silicon seed rods 1 consists of a rotationally symmetrical basic body 2 with a one-piece clamping element which can be inserted centrally in this at the highest position 3 for receiving the silicon culture rod 1 ( 1 . 2 . 5 - 7 ). The main body 2 is pot-like for receiving a connecting bolt 4 recessed a current feedthrough ( 6 ). The edge 5 of the basic body 2 is also used in the current feedthrough in the bottom of the reactor, not shown, with the items silicon seed rod 1 , Clamping element 3 , Basic body 2 and receiving part of the current feedthrough and connecting bolt 4 positive and non-positive are plugged into each other.

The 3 . 4 such as 8th - 10 show a variant of the receiving cone, wherein the main body 2 does not taper down to the top, but is just formed.

For holding the clamping element 3 is the main body 2 with a central blind hole 6 Mistake. The blind hole 6 should have a cone angle of 0.5-30 °, on the one hand to achieve a sufficient clamping effect and on the other hand to ensure that the clamping element 3 back from the main body 2 which can be seen from the following explanations ( 2 . 4 ).

The tensioning element 3 is rotationally symmetrical clamping jaw-like design and has a continuous, longitudinal receiving bore 7 for the silicon growing rod 1 ( 14a d).

To achieve a simple clamping, the clamping element 3 from both ends 8th . 9 starting with longitudinally extending non-continuous slots 10 provided alternately from one or the other end face 8th . 9 out.

There are two times by three slots 120 ° offset from each other 10 in the clamping element 3 provided, with the slots 10 from one end face 8th opposite the slots 10 from the other end 9 offset by 60 ° ( 6a c).

In addition, the tensioning element 3 at one end with a collar 11 provided, with the slots 10 from the front 8th of the clamping element 3 go out on the collar side, through the collar 11 extend. That goes to the collar 11 subsequent part of the clamping element 3 corresponds at most to the depth of the blind hole 6 ,

For a sufficient adhesion between the inserted silicon culture rod 1 and the tensioning element 3 and between the clamping element 3 and the body 2 to reach, the outer circumferential surface of the clamping element tapers 3 behind the collar 11 cone-shaped with the same cone angle as the blind hole 6 , so that a friction pairing arises.

Because the basic element 2 on the one hand safely held in the corresponding counterpart of the current implementation, but on the other hand must be easily removed again, the edge tapers 5 the pot lid-like body 2 in the same measure cone shaped, as the corresponding counterpart in the current feedthrough, forming another friction pair ( 2 . 4 . 6 . 9 ).

The cone angle of the edge 5 and the counterpart in the current feedthrough should be 4 ° -5 °.

The edge 5 can easily be adapted to other installation conditions. Thus, for example, the inside could also be provided with a thread, or be designed to receive a pin or the like.

In order to avoid any diffusion processes during the coating process, which would lead to a significant deterioration in the quality of the grown silicon rods, is between the inclusion of the current feedthrough and the main body 2 an electrically conductive separating element 12 arranged. Suitable for this is a separating element 12 silver ( 1 - 4 ).

In order to achieve a complete and extensive separation, owns the separating element 12 the negative shape of the inner contour of the base element and on the bottom of the negative shape of the connecting bolt 4 the current feedthrough.

To facilitate the removal of the grown silicon rod, it is also possible, at least between the main body 2 and the grown silicon rod another release agent 13 to arrange 11 - 13 ).

This release agent 13 may be an electrically conductive foil or disc of CFC (Carbon Fiber Reinforced Carbon) or other suitable graphite foil and may also extend to the bottom of the blind bore 6 extend.

The particularly low-mass construction of the receiving cone according to the invention with the lowest possible wall thickness leads in conjunction with the central heat input on the collet 3 to a significant reduction in heat loss via the current feedthrough and, consequently, to a significant reduction in the heat demand when heating the reactor.

In addition, the insertable into the cone and specially trained collet ensures 3 a safe and simple voltage of the silicon seed rods used 1 , and after the coating their easy removal. By changing the inner contour of the collet chuck 3 can adapt to almost all dimensions of silicon seed rods 1 done without a change in the basic body 2 having to make, resulting in a significant cost savings.

1

Silicon seed rod

2

body

3

clamping element

4

connecting bolt

5

edge

6

blind hole

7

location hole

8th

front

9

front

10

slot

11

collar

12

separating element

13

release agent

Claims (17)

Receiving cone for silicon seed rods in reactors for the addition of polysilicon, consisting of graphite, characterized in that the receiving cone from a rotationally symmetrical body ( 2 ) with a centrally in this at the highest position insertable one-piece clamping element ( 3 ) for receiving the silicon culture rod ( 1 ), wherein the basic body ( 2 ) pot-lid-like for receiving a connecting bolt ( 4 ) and whose edge ( 5 ) can be used in the current feedthrough in the bottom of the reactor, wherein the items silicon growing rod ( 1 ), Clamping element ( 3 ), Basic body ( 2 ) and receiving part of the current feedthrough and connecting bolts ( 4 ) are positively and non-positively plugged into each other. Mounting cone according to claim 1, characterized in that the basic body ( 2 ) with a central blind bore ( 7 ) for receiving the clamping element ( 3 ) is provided. Mounting cone according to claim 1, characterized in that the one-piece clamping element ( 3 ) is rotationally symmetrical clamping jaw-like and a continuous longitudinal receiving bore ( 7 ) for a silicon culture rod ( 1 ) owns. Mounting cone according to claim 1-3, characterized in that the clamping element ( 3 ) starting from both end faces with non-through slots extending therealong ( 10 ), which alternately from one or the other end face ( 8th ; 9 ) go out. A receiving cone according to claim 4, characterized in that each twice three slots offset by 120 ° ( 10 ) in the clamping element ( 3 ) are provided, wherein the slots ( 10 ) from one end face ( 8th ) opposite the slots ( 10 ) from the other end face ( 9 ) are offset by 60 °. Mounting cone according to one of claims 1 to 5, characterized in that the clamping element ( 3 ) at one end with a collar ( 11 ), wherein the slots ( 10 ), from the front side ( 8th ) of the clamping element ( 3 ) on the collar side, through the collar ( 11 ) and which is attached to the collar ( 11 ) subsequent part of the clamping element ( 3 ) at most the depth of the blind bore ( 6 ) corresponds. Mounting cone according to claim 6, characterized in that the blind bore ( 6 ) tapers conically into the depth. Mounting cone according to claim 7, characterized in that the blind bore ( 6 ) has a cone angle of 0.5-30 °. Mounting cone according to one of claims 1 to 8, characterized in that the outer circumferential surface of the clamping element ( 3 ) from the collar ( 11 ) to the opposite end face ( 9 ) tapers in the same cone angle as the blind bore ( 6 ). Mounting cone according to claim 9, characterized in that the edge ( 5 ) of the pot lid-like base body (10) tapers conically to the same extent as the counterpart in the current leadthrough. A receiving cone according to claim 10, characterized in that the cone angle of the edge ( 5 ) and the counterpart in the current feedthrough by 4 ° -5 °. Mounting cone according to one of claims 1 to 11, characterized in that at least between the receiving the current feedthrough and the base body ( 2 ) an electrically conductive separating element ( 11 ) is arranged. Mounting cone according to claim 12, characterized in that the separating element ( 11 ) is at the same time a diffusion barrier and consists of silver. Mounting cone according to claim 13, characterized in that the separating element ( 11 ) of the negative shape of the inner contour of the base body ( 2 ) and on the underside of the negative form of the connecting bolt ( 4 ) corresponds to the current feedthrough. Mounting cone according to one of claims 1 to 14, characterized in that at least between the base body ( 2 ) and the grown silicon rod, a release agent ( 13 ) is arranged. Mounting cone according to claim 15, characterized in that the release agent ( 13 ) is an electrically conductive foil or disc and consists of CFC (Carbon Fiber Reinforced Carbon) or another graphite foil. Mounting cone according to claim 16, characterized in that the release agent ( 13 ) to the bottom of the blind bore ( 6 ).