JPS61174188A - Pull up device for dendrite web from silicon melt - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an apparatus for raising a silicon dendrite web from a silicon melt, and more particularly to a quartz crucible melter barrier that has been improved to permit continuous replenishment of the melt.

A susceptor is heated by induction and houses a crucible.
In connection with the growth process of silicon dendrite webs using melting equipment (including ptor), melt replenishment has been emphasized as a means of reducing costs and increasing crystal quality. In such devices, particles or pellets are added to one or both ends of the crucible in parallel with the growth of the web crystal;
Heat is absorbed in the region where the melting of the supply material occurs, resulting in a significant temperature imbalance in the region of origin of web pulling.

The ideal temperature condition is that the area where the pellets etc. are being refilled is hot and other parts of the crucible are unaffected by the material replenishment. One approach known to those skilled in the art is to use one or more barriers within the crucible to isolate the relatively hot melt replenishment region from the dendrite web pulling region.

Furthermore, various methods have been attempted to adjust the temperature conditions by changing the heat insulation effect or by moving the induction heating coil. However, such temperature regulation tends to generate linear temperature gradients between the melt zone and the growth zone, resulting in undesirable crystalline properties. Also,
The flow of molten silicon from the melt supply through the barrier opening disrupts the melt in the growth chamber.

To overcome these problems, the present invention provides an elongated quartz crucible means having a closed bottom, a side wall member rising from the bottom and an at least partially open top, and an elongate quartz crucible means disposed laterally within said crucible means and having a sidewall member rising from the bottom and an at least partially open top. quartz barrier means defining a silicon melt replenishment section and a dendrite web pulling section; and heating the bottom and sides of said crucible means to melt the silicon in the crucible and depositing the silicon in said web pulling section of said crucible means in a molten state. heating means for maintaining silicon at a predetermined level; means for pulling a silicon dendrite web at a predetermined speed from a molten surface of silicon held in a web pulling section of the crucible means; and replenishing the silicon melt in the crucible means. and a silicon replenishment means for replenishing unmolten silicon at a predetermined rate to the silicon melt, wherein the quartz barrier means includes bottom edge means, side edge means and top edge means. having a predetermined shape, the bottom edge means of said quartz barrier means engages in sealing relationship with the bottom of said crucible means, and a portion of the side edge means of said quartz barrier means is in sealing relationship with side wall means of said crucible means. and a top edge means of said barrier means is accommodated in said crucible means to form an opening of predetermined dimensions with a portion of a side wall of said crucible means, said opening means of,
The silicon that first melts near the bottom and sides of the crucible stays at the heated bottom of the silicon supply section of the crucible, and the molten silicon remains until the amount of stay reaches a predetermined depth.

The dendrite web is placed a predetermined distance above the bottom of the crucible so that the dendrite web does not directly flow into the dendrite web pulling section, and the unmolten silicon supported on the molten silicon in the crucible is pulled up from the silicon melt supply section of the crucible. The opening means formed in the barrier means is arranged a predetermined distance below a predetermined level of molten silicon in the silicon melt supply portion of the crucible so as to prevent the silicon melt from flowing into the silicon melt supply portion of the crucible. By setting the opening means of the barrier means to a size that allows the liquid to flow into the web pulling section, and arranging the opening means of the barrier means near the side of the crucible means, the web pulling section is set near the side wall of the crucible where molten silicon is heated. Provided is an apparatus for pulling up a dendrite web from a silicon melt, characterized in that silicon flows into the silicon melt and reaches a temperature suitable for pulling up a silicon dendrite web.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a detailed description of the present invention will be made clear by describing preferred embodiments along with the accompanying drawings.

1 and 2, 20 is an elongated quartz crucible means having a closed bottom 22 and a side wall member 24 extending upwardly from the bottom, the top of the crucible being at least partially open. As shown in cross-section in FIG. 2, quartz barriers 26 are disposed on the left and right sides of the crucible 20 to define a silicon melt supply section 28 and a dendrite web pulling section 30 separated therefrom. As an alternative embodiment, a crucible 32 shown in FIG. 3 uses only one barrier 26 to form one dendrite web puller 30 and one silicon melt replenisher 28. In this embodiment, the side walls 34 of crucible 32 are also vertical.

4-6 are elevation views of conventional quartz barrier members. The barrier member 36 of FIG. 4 has a cutout 38 at its bottom.
Equipped with. In this embodiment, the silicon that begins to melt near the bottom of the crucible directly flows into the web pulling section, resulting in an undesirable temperature gradient in the web pulling section.

Another known embodiment 40 shown in FIG.
It is a four-piece barrier including two small uprights 42. In this embodiment, significant flow occurs through the center point of the opening 44 defined by the four pieces, and the inflow of silicon through the openings on both sides and through the central opening creates a temperature gradient in the web lift. . Further, the fusion welded portion of the upright portion 42 is likely to be damaged quickly.

FIG. 6 shows yet another conventional barrier embodiment 46, which has only one rectangular opening 48 formed slightly above the bottom of the crucible. This embodiment allows the silicon to pass only through the middle of the barrier, resulting in some physical disruption and thermal problems, and the cost of manufacturing such an embodiment is extremely high.

FIG. 7 shows the barrier means 50 of the present invention.

The barrier means has a predetermined shape comprising bottom edge means 52, side edge means 54 and top edge means 56. The bottom edge engages the bottom 22 of the crucible 20 in a sealing relationship, as seen in FIGS. 1 and 2. Part of the side a54 is the side wall member 2 of the crucible
4 and engages said side wall member 24 in a sealing relationship. The top edge 56 of the barrier is elevated above the level of molten silicon contained within the quartz crucible 20.

In the present invention, the opening means 58 constituted by a cutout.
By providing the side edge 54 with a portion of the side wall 24 of the crucible 20, an opening of a predetermined size is formed, as is clear from FIGS. The opening means 58 allows the silicon that first melts near the bottom and sides of the crucible 20 to accumulate at the heated bottom of the silicon replenishment section 28 (FIGS. 1 and 2) of the crucible, and the amount of accumulation reaches a predetermined depth. The molten silicon is placed a predetermined distance above the bottom of the crucible so that molten silicon does not directly flow into the dendrite web pulling section 30 until it reaches the bottom of the crucible. The opening means 58 also prevents the unmolten silicon supported on the molten silicon in the crucible from flowing from the silicon melt supply of the crucible into the web pulling section. It is placed a predetermined distance below the level.

The dimensions of the opening 58 formed in the barrier are set such that at least a predetermined flow rate of silicon flows into the web pulling section to supply a sufficient flow rate of molten silicon to the web pulling section, and the barrier opening is used as a crucible. 20, the molten silicon flows into the web pulling section near the high temperature side wall of the crucible.
The silicon has reached a temperature suitable for pulling the silicon dendrite web.

The barrier may be manufactured from rectangular or trapezoidal quartz blocks of the same width and height as the finished barrier, but thicker than a single plate barrier. The notches on the side edges of the barrier may be machined in the form of grooves into the side of the quartz block, and then the barriers may be sliced one by one from the block using a saw or the like.

In the embodiment 50a of FIG. 8, the barrier side edges 54a are vertical;
It is almost the same as that shown in FIG. 7, except that it is incorporated into the vase shown in FIG.

As a specific example, the crucible is 8.0 inches long (20.3 cm
m), 2.5 inches (6,4 am) wide and 0.6 inches (1,5 cm) deep to accommodate molten silicon, the cross-sectional area of each opening 58 is 0.059 in2 (0,38 cm).
2).

FIG. 9 is a perspective view of a known susceptor 62 that cooperates with the improved barrier crucible of the present invention. The crucible fits into the opening 64 in the top of the susceptor. A quartz crucible installed in a susceptor 62 is shown in perspective view in FIG. 10 with a silicon dendrite web 66 pulled up through a cover member 68 of the susceptor 62. In addition, member 7
0 is an end wall heat insulating means, member 72 is a side wall heat insulating means, and the cover has a heat insulating means 74 underneath. When working with this embodiment, two improved barrier members of the present invention are used, melt replenishers are provided at both ends of the crucible, and all cover members have openings for supplying replenishing silicon. form 76.

FIG. 11 is a sectional view showing details of the pulling operation, and the susceptor 62 is heated by induction by the coil 78. Preferably, the susceptor is made entirely of molybdenum, which is the material of its top cover 68. It should be noted that this apparatus is of almost all conventional construction except for an improved crucible/barrier arrangement.

FIG. 12 is a cross-sectional view showing another embodiment of the apparatus of the present invention, in which a top cover member 80 forming a part of a growth chamber 82 is connected to the top of the growth chamber 82 through a supply pipe 86 and an opening 76 from a tank 84. An opening for supplying unmolten silicon to the silicon replenishing section 28 is provided. silicon web 6
6 was pulled up seamlessly, and extremely long webs could be pulled up using the configuration of the present invention. As is conventional, growth chamber 82 contains an inert atmosphere at slightly above atmospheric pressure, such as argon.

[Brief explanation of drawings]

FIG. 1 is a plan view of a quartz crucible; FIG. 2 is a cross-sectional view taken along line 2-2 as indicated by the arrow in FIG. 1; FIG. 3 is a quartz crucible with vertical side walls and incorporating only a single barrier. 4 is an elevational view of a conventional barrier, FIG. 5 is an elevational view of another embodiment of a conventional barrier, and FIG. 6 is an elevational view of another conventional barrier. Elevation view showing one embodiment of other embodiments, No. 8
9 is an elevational view showing another embodiment of the quartz barrier of the present invention, FIG. 9 is a perspective view of a susceptor used in combination with a lifting device, and FIG.
Figure 11 is a perspective view of the susceptor in operation showing the silicon dendrite web being pulled up in phantom;
FIG. 12 is a cross-sectional view taken along line 6--6 of the figure, showing the apparatus in operation along with the unmolten silicon replenishment system. 50... Barrier 52... Bottom edge 54... Side edge 58... Notch 66... Dendrite web FIG, 5 FIG, 8 Procedure amendment (method) Showa 61 years 2
February 17, 2, Title of the Invention Apparatus for Lifting Dendrite Web from Silicon Melt 3, Relationship to the Amended Person's Case Address of Patent Applicant Pittsburgh, Pennsylvania, United States of America. Gateway Center (no street address) Name (711) Westinghouse Electric Corporation Representative Theodore Stern Nationality United States 4, Agent

Claims (1)

Claims: 1. Elongated quartz crucible means having a closed bottom, sidewall members rising from the bottom, and an at least partially open top; and a silicon melt disposed laterally within the crucible means. quartz barrier means defining a liquid replenishment section and a dendrite web lifting section, and heating the bottom and sides of said crucible means to melt the silicon in the crucible and depositing molten silicon into said web lifting section of said crucible means. heating means for maintaining a predetermined level; means for pulling up a silicon dendrite web at a predetermined speed from a molten surface of silicon held in a web pulling section of the crucible means; silicon replenishment means for replenishing unmolten silicon at a rate of a bottom edge means of said quartz barrier means is in sealing engagement with a bottom of said crucible means, and a portion of a side edge means of said quartz barrier means is in sealing engagement with a side wall means of said crucible means. and the top edge means of the barrier means are located above the level of molten silicon contained in the crucible means, and the side edge means of the barrier are provided with opening means constituted by cutouts. forming an opening of predetermined dimensions with a portion of the side wall of the crucible means;
Silicon, which first melts near the bottom and sides of the crucible, stays at the heated bottom of the silicon supply section of the crucible, and prevents molten silicon from directly flowing into the dendrite web pulling section until the amount of accumulation reaches a predetermined depth. The silicon melt replenishment part of the crucible is disposed a predetermined distance above the bottom of the crucible and prevents the unmolten silicon supported on the molten silicon in the crucible from flowing from the silicon melt replenishment part of the crucible to the web pulling part. said opening means formed in said barrier means is disposed a predetermined distance below a predetermined level of molten silicon in said section, and said opening means formed in said barrier means is sized to permit at least a sufficient flow of silicon to flow into said web pulling section; By arranging the opening means of the barrier means near the side of the crucible means, molten silicon flows into the web pulling section near the heated side wall of the crucible, making the silicon suitable for pulling the silicon dendrite web. An apparatus for pulling a dendrite web from a silicon melt, characterized in that the dendrite web is pulled up from a silicon melt. 2. Apparatus according to claim 1, characterized in that one web lift and one melt replenishment are defined in the crucible means using only one quartz barrier. 3. A patent characterized in that two quartz barriers are used to define one web pulling section near the center within the crucible means and two silicon melt supply sections, one near each end. Apparatus according to claim 1. 4. The apparatus according to claim 1, 2 or 3, characterized in that the apparatus is surrounded by a growth chamber containing an inert gas atmosphere.