JPH085736B2 - Method and apparatus for growing silicon single crystal - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention uses a quartz crucible having a multiple structure to pull and grow a silicon single crystal for a semiconductor device and a solar cell, and at the same time, to grow the same amount of the grown single crystal. The present invention relates to a silicon single crystal growing method and apparatus for continuously supplying raw material silicon into a quartz crucible.

[Conventional technology]

Conventionally, as a method for producing a silicon single crystal by the Czochralski method, a single crystal is pulled up while the silicon melt in a quartz crucible is continuously replenished with raw material silicon, while keeping the amount of sillcon melt constant. Various continuous manufacturing methods have been proposed (see, for example, JP-A-57-1833).
92, JP-A-58-130195, USP-2892739).

[Problems to be solved by the invention]

By the way, during the growth of a silicon single crystal, a part of the surface of the quartz crucible which is in contact with the silicon melt is deteriorated, and further, a phenomenon of peeling frequently occurs. Since this exfoliated piece of quartz has a smaller specific gravity than the silicon melt, it floats on the surface of the silicon melt and eventually adheres to the growing single crystal, causing dislocations from it and causing the silicon single crystal to become polycrystalline. Causes the problem of becoming The phenomenon of the exfoliation of the quartz pieces is most likely to occur in the portion 5 where the quartz crucible 2 supported by the graphite susceptor 1 is in contact with the surface 4 of the silicon melt 3, as shown in FIG. Because this part 5 is solid phase (quartz crucible 2) -liquid phase (silicon melt 3) -gas phase (Si
This is because the reaction is most intense at the three-phase interface of O vapor 6).

In this respect, in the batch type silicon single crystal growing method, the position of the silicon melt surface is relatively lowered with respect to the quartz crucible as the single crystal is grown, and therefore, dislocation of the quartz small pieces causes dislocation in the growing single crystal. It is relatively rare that it will be introduced, and it is not a problem in practice. On the other hand, in the above-described continuous single crystal production method, as a result of intensive studies by the present inventors, the position of the melt surface in the quartz crucible does not change, and therefore the deterioration of quartz at the three-phase interface 5 is caused. Further, it was found that peeling occurred violently and continuous growth of single crystal for a long time was difficult. As one method for solving this problem, even in the above-described single crystal continuous manufacturing method, the position of the melt surface in the quartz crucible is gradually changed without the growth amount of the single crystal and the supply amount of the raw materials being matched. It is possible to make it.
According to this method, the problem of inhibiting single crystal growth due to exfoliation of quartz can be avoided, but the major feature of the single crystal continuous growth method is homogenization of single crystal quality by making the melt amount in the crucible constant. Loss of strength.

The present invention has been made in view of the above circumstances, and an object thereof is to maintain homogenization of single crystal quality,
It is an object of the present invention to provide a method and an apparatus for growing a silicon single crystal capable of preventing the deterioration and peeling of quartz from the three-phase interface of a quartz crucible as much as possible and preventing the polycrystallization of a single crystal.

[Means for solving problems]

In order to achieve the above object, the method of the present invention continuously raises and lowers the innermost container of the quartz crucible having a multiple structure with respect to the surface of the silicon melt during pulling and growing the single crystal.

Further, in the apparatus of the present invention, a support for supporting the inner container of the multi-structured quartz crucible is provided on the outer periphery of the rotatable outer container so as to be vertically movable and rotatable together with the outer container. The supporting body is provided with an elevating mechanism that engages with the supporting body and elevates the supporting body.

[Operation] In the method and apparatus for growing a silicon single crystal of the present invention, when pulling and growing a single crystal, the innermost container of the quartz crucible having a multiple structure is continuously moved up and down with respect to the surface of the silicon melt. The positional relationship between this container and the surface of the silicon melt is continuously changed.

Here, when a single crystal is continuously grown by using a double or triple or more quartz crucible structure, the phenomenon of the exfoliation of quartz pieces due to a constant melt amount is a problem. Only the innermost containment. This is because even if the small quartz pieces are peeled off from the outer container, the inner container serves as a shielding plate and can be prevented from adhering to the grown single crystal. Therefore, only the innermost container of the quartz crucible needs to rise or fall with respect to the melt surface as the single crystal grows.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS.

FIG. 1 shows an example of an apparatus for carrying out the method for growing a silicon single crystal according to the present invention, in which reference numeral 10 is an outer container of a quartz crucible 11. The outer peripheral portion is supported by the graphite susceptor 12 while the central portion of the outer container 10 is deeply formed. In addition, in the outer container 10,
While the silicon melt 13 is held, a cylindrical inner container 14 is inserted in a state of being supported by an elevating mechanism 15 so as to be vertically movable. Further, a raw material supply pipe 17 for supplying the raw material 16 in the form of powder, lumps, or granules is arranged above the edge of the outer container 10.

When performing the method of the present invention using the silicon single crystal growth apparatus configured as described above, first, the polycrystalline silicon in the quartz crucible 11 is filled, after the furnace is replaced with argon gas, The resistance heater is energized to raise the temperature inside the furnace. Then, after the raw material silicon filled is melted,
The liquid temperature is set to a temperature suitable for crystal growth. Then, the seed crystal is made dislocation-free by a conventionally known method of DASH to form a neck portion and a shoulder portion to have a desired thickness. When the desired thickness is reached, the growth rate and liquid temperature are adjusted to grow the straight body of the single crystal 18 having a constant diameter. At this time, the powder, lump, or granular raw material 16 is supplied from the raw material supply pipe 17 between the inner container 14 and the outer container 10 of the quartz crucible 11 in the same amount as the growth amount of the single crystal 18. The inner container 14 is continuously lowered (or raised) by the lifting mechanism 15.

In this way, by continuously moving the inner container 14 up and down, only a fixed part of the inner surface of the inner container 14 does not become a three-phase interface, and even if it is operated for a long time, a part of the quartz is not formed. Does not peel off and does not hinder single crystal growth. Moreover, it became possible to obtain a single crystal of uniform quality while keeping the melt volume constant.

2 and 3 show an example of the silicon single crystal growing apparatus of the present invention. In these figures, the same components as those of the apparatus shown in FIG. And the description is omitted.

2 and 3, reference numeral 20 is a graphite susceptor that supports the outer container 10 of the quartz crucible 11, and four grooves 20a are formed on the outer periphery of the graphite susceptor 20 at equal intervals in the axial direction. Has been done. On the other hand, the inner container 14 loaded in the outer container 10 has a continuous member.
A cylindrical support 22 is connected via 21 and each groove 20 of the graphite susceptor 20 is provided on the inner periphery of the support 22.
Four ridges 22a that fit into a are formed. As a result, the support 22 is configured to be vertically movable with respect to the graphite susceptor 20.

Further, a screw portion 22b is formed on the lower portion of the outer periphery of the support body 22, and an elevating mechanism 23 is engaged with the screw portion 22b. When the outer container 10 and the graphite susceptor 20 rotate, the support 22 rotates and descends (or rises) accordingly.

When performing the method of the present invention using the silicon single crystal growth apparatus configured as described above, in the same manner as the above-mentioned method, the quartz crucible 11 is filled with polycrystalline silicon, and the inside of the furnace is After replacing with argon gas, the polycrystalline silicon is melted by a heater. Then, after bringing the silicon melt to a temperature suitable for crystal growth, soaking the seed crystal,
By pulling up, the neck portion, the shoulder portion, and the straight body portion of the single crystal 18 are sequentially grown. At this time, the raw material 16 is supplied between the inner container 14 and the outer container 10 of the quartz crucible 11 in the same amount as the growth amount of the single crystal 18 to keep the liquid surface of the silicon melt 13 constant. At the same time, by rotating the graphite susceptor 20 together with the outer accommodating body 10, the support body 22 fitted on the outer periphery of the graphite susceptor 20 rotates, but at this time, the support portion 22 has a screw portion 22b at the lower outer periphery thereof. Is a lifting mechanism in a fixed state 2
Since 3 is engaged, with the rotation of the support 22,
The support mechanism 22 descends (or rises) as the elevating mechanism 23 moves along the spiral of the screw portion 22b. As a result,
The same effect as that of the above-described embodiment can be obtained.

〔The invention's effect〕

As described above, in the present invention, when pulling and growing a single crystal, the innermost container of the quartz crucible having a multiple structure is continuously moved up and down with respect to the surface of the silicon melt, and the container and the silicon melt. By continuously changing the positional relationship with the surface of the quartz crucible, the three-phase interface of the quartz crucible is constantly changing without impairing the homogenization of the quality of the single crystal due to the constant amount of silicon melt. It has an excellent effect that the deterioration and peeling of quartz can be prevented as much as possible and the polycrystallization of a single crystal can be prevented.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing one embodiment of the present invention, FIGS. 2 and 3 show another embodiment of the present invention, FIG. 2 is a schematic configuration diagram, and FIG. 3 is a plan view. FIG. 4 and FIG. 4 are explanatory views showing a conventional quartz crucible. 10 ... Outer container, 11 ... Quartz crucible, 13 ... Silicon melt, 14 ... Inner container, 15 ... Elevating mechanism, 16 ... Raw material,
18 …… single crystal, 20 …… graphite susceptor, 22 …… support, 23 …… elevating mechanism, 20a …… groove, 22a …… projection, 22b
...... Screw part.

Claims (2)

[Claims] 1. A method for growing a silicon single crystal in which a silicon single crystal is pulled up and grown by using a quartz crucible having a multiple structure, and at the same time, the same amount of raw material silicon as the grown single crystal is continuously fed into the quartz crucible. , During single crystal pull-up growth,
A method for growing a silicon single crystal, wherein the innermost container of the quartz crucible is continuously moved up and down with respect to the surface of the silicon melt. 2. A silicon single crystal growing apparatus for simultaneously pulling and growing a silicon single crystal by using a quartz crucible having a multi-structure and simultaneously supplying the same amount of raw material silicon as the grown single crystal into the quartz crucible. A support for supporting the inner container of the quartz crucible is provided on the outer periphery of the rotatable outer container so as to be vertically movable and rotatable together with the outer container, while the support is engaged with the support. An apparatus for growing a silicon single crystal, characterized in that an elevating mechanism for elevating and lowering a support is provided.