JPH06144986A - Apparatus and method for production of semiconductor single crystal - Google Patents

Abstract

PURPOSE:To enable the retreat of a radiation screen upward in a chamber at the time of packing and melting raw materials and shortening the time for melting the raw materials in production of a single crystal by a CZ method. CONSTITUTION:The radiation screen is divided to the upper screen 8 and the lower screen 11 and the upper screen 8 is fitted to a support 7. The lower screen 11 is connected to a lifting rod 10. The lower screen 11 is pulled upward in the chamber at the time of packing the raw materials into a quartz crucible 3. The lower screen 11 is then lowered and is joined to the upper screen 8 upon completion of melting of the raw materials. The interference of the raw materials 4 and the lower screen 11 is averted and the prescribed amt. of the raw materials are packed into the crucible by the operation. The upper screen 8 covers the upper part of a heater 5, thereby improving a heat retaining property and shortening the time for melting the raw materials. The melting time is further shortened if the lower screen 11 is gradually lowered according to the progression of the melting of the raw materials.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor single crystal production apparatus having a radiation screen which surrounds a pulled single crystal and is arranged so that its lower end is close to the melt surface, and a semiconductor using the production apparatus. The present invention relates to a single crystal manufacturing method.

[0002]

2. Description of the Related Art The Czochralski method (hereinafter referred to as the CZ method) for pulling a cylindrical single crystal from a raw material melt in a crucible is used as one of methods for producing a silicon single crystal which is a basic material of a semiconductor integrated circuit. Has been. In the CZ method, a crucible installed in a chamber of a single crystal manufacturing apparatus is filled with a polycrystal as a raw material, the raw material is heated and melted by a heater provided on the outer circumference of the crucible, and then a seed crystal attached to a seed chuck is attached. A single crystal is grown by immersing in the melt and pulling up the seed chuck while rotating the seed chuck and the crucible in the same or opposite directions. In such a single crystal manufacturing apparatus, a radiation screen is arranged around the single crystal pulling region as a means for increasing the pulling speed of the single crystal and preventing contamination by impurities to improve dislocation-free single crystal. It has been known. The radiation screen is a heat shield surrounding the single crystal pulling region, and is generally a conical cylinder having a lower end opening diameter smaller than an upper end opening diameter. The radiant screen shuts off the radiant heat applied to the single crystal from the melt, heater, crucible, etc. to accelerate the cooling of the single crystal, accelerate the pulling rate of the single crystal, and pull up the inert gas introduced from above the chamber. By inducing around the crystal and forming a gas flow from the center of the crucible to the lower part of the chamber through the peripheral edge, it inhibits single crystallization, such as silicon oxide generated from the melt or metal vapor generated from the graphite crucible. It has the function of eliminating gas.

However, when the radiant screen is fixed above the crucible, the radiant screen becomes an obstacle when the quartz crystal crucible is filled with the single crystal raw material. Therefore, the raw material is filled more than when the radiant screen is not provided. The quantity will decrease. Therefore, the productivity of the single crystal is lowered and the production cost is increased. It is also known that the oxygen concentration in the single crystal changes greatly depending on the size of the distance between the lower end of the radiation screen and the melt surface. As an example of a technique for solving this problem, a suspension member which is capable of being screwed back and forth in the vertical direction is provided on a chamber upper plate, and a radiation screen is supported in the chamber by the suspension member, as disclosed in Japanese Patent Laid-Open No. 3-279290. Is disclosed in. With this technique, the radiation screen can be retracted upward in the chamber during filling and melting of the raw material, so that the filling amount of the raw material need not be reduced. After the completion of melting the raw materials, the radiation screen can be lowered around the single crystal pulling region, and the distance between the melt surface and the lower end of the radiation screen can be adjusted arbitrarily. Therefore, variations in oxygen concentration in the single crystal can be suppressed.

[0004]

However, in the above-mentioned conventional single crystal manufacturing apparatus, when the raw material is melted, the entire radiant screen is retracted upward in the chamber, so that the heat above the heater easily escapes upward, and the raw material is melted. Time will increase. If the melting power is increased to shorten the material melting time, the quartz crucible is softened and easily deformed, which makes stable crystal growth difficult. Therefore, the manufacturing cost of the product manufactured by this single crystal manufacturing apparatus is increased. The present invention has been made in view of such a conventional problem, and a semiconductor capable of retracting the radiant screen upward in the chamber at the time of filling and melting the raw material and not requiring an extension of the raw material melting time. An object is to provide a single crystal manufacturing apparatus and a semiconductor single crystal manufacturing method.

[0005]

In order to achieve the above object, a semiconductor single crystal manufacturing apparatus according to the present invention comprises a crucible for filling a raw material of a semiconductor single crystal and a raw material in a crucible surrounding the crucible. In a single crystal manufacturing apparatus in which a heater for melting, a pulling mechanism for immersing a seed crystal in a melted raw material to pull up a single crystal, and a radiation screen surrounding the periphery of the single crystal are arranged above the melt, the radiation screen is moved up and down. It is divided into two parts, a joint is provided at the connecting portion between the upper screen and the lower screen, the upper screen is attached at a predetermined position during the production of the single crystal, and a mechanism for raising and lowering the lower screen is provided. In the configuration, the lower screen lifting mechanism may be provided with an upper screen locking mechanism that locks the upper screen to allow vertical movement. Is configured to connect the upper ends of the lower screens to the lower ends of a plurality of vertically movable rods that constitute the lower screen lifting mechanism, and to provide an upper screen hooking mechanism at the lower ends of the rods to be hooked by the hooking mechanism. An upper screen having projections on the upper end surface may be attached at a predetermined position during single crystal production. The method for manufacturing a semiconductor single crystal when using the semiconductor single crystal manufacturing apparatus, when filling the raw material into the crucible, the lower screen is lifted up in the chamber using the lower screen lifting mechanism, after the melting of the raw material is completed, the lifting The lower screen is lowered by driving the mechanism, and the lower screen is joined to the upper screen.Or, when filling the crucible with the raw material, the lower screen lifting mechanism is used to pull the lower screen upward in the chamber to When melting, the lower screen is gradually lowered by driving the elevating mechanism with the lowering of the raw material top, and the lower screen may be joined to the upper screen when the raw material is completely melted, or the raw material to the crucible When filling, use the lower screen lifting mechanism to pull the lower screen up inside the chamber. Upon dissolution of the raw material, with the descent of the raw material top gradually lowers the lower screen by driving the elevating mechanism, causes the engagement of the lower screen in the upper screen when dissolution is complete the material, after pulling the completion of the single crystal,
The lower screen and the upper screen hooked by the elevating mechanism may be pulled upward in the chamber.

[0006]

According to the above construction, the radiation screen is divided into the upper screen and the lower screen, and the mechanism for raising and lowering the lower screen is provided. Therefore, the lower screen can be pulled up into the chamber as needed. Therefore, when the lower screen is pulled up in advance when filling the crucible with the single crystal raw material, the raw material does not interfere with the lower screen and a predetermined amount of the raw material can be easily filled. Since the upper screen is attached at a predetermined position during the production of the single crystal, the upper part of the heater and the crucible is covered with the upper screen, and the heat retaining property of the upper part of the heater is significantly improved. Therefore, the time required for melting can be shortened without increasing the electric power at the time of melting. Further, when the raw material is melted, the elevating mechanism is driven as the raw material top is lowered to gradually lower the lower screen, whereby the heat retaining property of the heater upper part is further improved, and the time required for melting the raw material is further shortened. be able to.

In the semiconductor single crystal manufacturing apparatus according to the second and third aspects, the upper end of the lower screen is connected to the lower ends of a plurality of vertically movable rods constituting the lower screen lifting mechanism, and the upper end is connected to the lower ends of the rods. Since a screen hooking mechanism is provided and a protrusion hooked by the hooking mechanism is provided on the upper end surface of the upper screen to attach it at a predetermined position during the production of a single crystal, the rod is raised to lower the lower screen. When pulled up, the upper screen can be pulled up at the same time. Therefore, after the pulling of the single crystal is completed based on the single crystal manufacturing method of claim 6, the elevating mechanism is driven to pull up the lower screen and the upper screen upward in the chamber to accelerate the cooling of the hot zone parts. You can

[0008]

Embodiments of the semiconductor single crystal manufacturing apparatus according to the present invention will be described below with reference to the drawings. 1 and 2 are partial schematic cross-sectional views of a semiconductor single crystal manufacturing apparatus according to claim 1, FIG. 1 shows a state in which a quartz crucible is filled with a raw material for a single crystal, and FIG. The state where it installed in a predetermined position is shown. In FIG. 1, a quartz crucible 3 is fitted into a graphite crucible 2 installed in a main chamber 1, and the quartz crucible 3 is filled with a raw material 4. Reference numeral 5 is a graphite heater, and 6 is a heat insulating cylinder, all of which are arranged so as to surround the graphite crucible 2.
An upper screen 8 is attached to the upper end of the via a support 7. The upper screen 8 is composed of an annular flange portion and a hollow conical short tube portion connected to the inner edge of the flange portion, and the outer edge of the flange portion is fitted into the support 7. The graphite heater 5 and the upper part of the quartz crucible 3 near the inner circumference are covered with the upper screen 8. An upper chamber 9 is connected to the upper end of the main chamber 1, and a vertically movable rod 10 is mounted on the upper chamber 9. The lower screen 11 is a hollow conical tube, and has a joint portion 11a that is joined to the lower end of the upper screen 8 at the upper end thereof.
It is fixed to the lower end of the elevating rod 10 via 2. The lower screen 11 may be supported on the lower end of the elevating rod 10 via the connecting member 12. In addition, 13 is a crucible shaft.

An example of a single crystal manufacturing method using the semiconductor single crystal manufacturing apparatus will be described. When filling the quartz crucible 3 with the single crystal raw material, the elevating rod 10 is driven as shown in FIG. 1, and the lower screen 11 is previously pulled up to a height close to the inner surface of the upper chamber 9. Since a sufficient distance is secured between the lower end of the upper screen 8 and the upper end of the quartz crucible 3, the raw material 4 does not interfere with the upper screen 8 and the predetermined amount of raw material can be easily filled. it can. Further, the height of the crucible may be adjusted by driving the crucible shaft 13 as needed. After filling the quartz crucible 3 with the raw material 4, the raw material 4 is heated and melted by the graphite heater 5. At this time, the heat dissipated toward the upper chamber 9 is blocked by the upper screen 8 and the heat loss can be reduced, and as a result, the raw materials can be efficiently melted. After the raw material 4 is completely dissolved, the lower screen 11 is lowered as shown in FIG.
Join to the upper screen 8. Then, the seed crystal is dipped in the melt and pulled up while growing a single crystal.

Using this semiconductor single crystal manufacturing apparatus, 80 k
When g of the single crystal raw material was dissolved, the time required for dissolution was 5 hours and 45 minutes on average. When the conventional single crystal manufacturing apparatus for retracting the entire radiation screen upward was used, the average time required for melting was 6 hours and 37 minutes, and this improvement made it possible to reduce the time required for melting by 13% on average. In addition,
By adjusting the distance between the lower end of the lower screen 11 joined to the upper screen 8 and the melt surface by the vertical movement of the crucible, the oxygen concentration in the single crystal could be suppressed within a predetermined range.

Next, an embodiment of the method for producing a single crystal according to claim 5 is shown in FIG. When filling the quartz crucible 3 with the single crystal raw material 4 and at the start of melting, the lifting rod 10 is moved as shown in FIG.
Is driven to raise the lower screen 11 to a height close to the inner surface of the upper chamber 9. As the melting of the raw material 4 progresses, the height of the top of the raw material 4 gradually decreases, so that the lower screen 11 is gradually lowered in response to this change. By this operation, heat dissipation toward the upper chamber 9 can be further prevented. When this method was used, the average time required to dissolve the raw materials was 5 hours and 32 minutes. Therefore,
13 more than when only the upper screen is used to shield heat
The time required for melting the raw materials can be reduced by 3%. Therefore, it is possible to reduce the total melting time by 65 minutes, which is 16%, as compared with the conventional time required for melting the radiation screen.

FIG. 4 shows a state in which the lower screen and the upper screen are simultaneously pulled upward based on the semiconductor single crystal manufacturing apparatus of claim 3 and the semiconductor single crystal manufacturing method of claim 6, and FIG. [Fig. 5] is an enlarged view of a P portion of Fig. 4. Lifting rod 10 for lifting the lower screen 11
A hook claw 14 is axially attached to the lower end of the hook, and the hook claw 14 is rotatable within a range of less than 90 ° from an obliquely upper direction to a horizontal direction. In addition, a cylindrical projection 8a that is hooked by the hook 14 is provided on the upper surface of the flange portion of the upper screen 8.
Is stuck. The operations of filling the quartz crucible 3 with the raw material and melting the raw material are as described above, and the lower screen 11 is gradually lowered as the raw material is melted, and is joined to the upper screen 8 when the melting is completed. At this time, the hook 14
Is a projection 8 of the upper screen 8 in a state of protruding in the horizontal direction.
After coming into contact with a and descending while being pushed up by the protrusion 8a, it again projects horizontally below the protrusion 8a. After the pulling of the single crystal is completed, the lifting mechanism is driven to move the lifting rod 1.
When 0 is raised, the hook 14 comes into contact with the lower surface of the projection 8a and the lower screen 11 and the upper screen 8 are brought together.
Is also pulled upward in the chamber. This operation accelerates the heat dissipation of the hot zone parts and shortens the waiting time for the maintenance in the furnace. By using this method, the time required for cooling the furnace can be shortened by about 60 minutes or 13%.

Without a dedicated radiation screen lifting mechanism,
As shown in FIG. 6, a hanging jig 16 may be attached to the seed crystal holder 15 instead of the seed chuck, and the lower screen 11 may be supported on the hanging jig 16. The hanging jig 1
6 is a shaft 16a fitted to the seed crystal holder 15
A wire cable 16b connected to a drill hole provided at the lower end of the shaft 16a, and a wire cable 16
It consists of three hooks 16c attached to the lower end of b,
By hooking the hook 16c on the lower end of the lower screen 11, the lower screen 11 is lifted.
It is supported by 6. At the time of filling and melting the raw materials, the height of the seed crystal holder 15 is adjusted so that the upper end of the lower screen 11 is close to the inner surface of the upper chamber 9. When the hanging jig 16 is used, since it is necessary to replace the hanging jig 16 attached to the seed crystal holder 15 with the seed chuck after the lower screen 11 is joined to the upper screen 8, an average dissolution is required. The time was 5 hours and 50 minutes. However, the hanging jig is less expensive than the installation cost of the radiation screen elevating mechanism, and even in a single crystal manufacturing apparatus without a radiation screen elevating mechanism, it is possible to shorten the raw material melting time by elevating the lower screen, and to reduce the single crystal. It is possible to reduce the manufacturing cost of.

[0014]

As described above, according to the present invention, the radiation screen surrounding the single crystal pulling region is divided into the upper screen and the lower screen, and the lower screen is used by using the elevating mechanism when filling and melting the single crystal raw material. Since the material is pulled upward in the chamber, it is possible to easily fill the raw material, and it is possible to remarkably improve the heat retaining property of the upper portion of the heater by the upper screen attached at a predetermined position during the production of the single crystal. Therefore, it becomes possible to shorten the time required for melting the raw material without reducing the filling amount of the raw material and without increasing the melting power. Also, when the raw materials are dissolved,
By gradually lowering the lower screen as the top of the raw material descends, the heat retaining property of the upper portion of the heater is further improved, and the time required for melting the raw material can be further shortened. Furthermore, when the upper screen as well as the lower screen is pulled upward in the chamber after the pulling of the single crystal is completed, the time required for cooling in the furnace can be shortened. These improvements make it possible to reduce the manufacturing cost of semiconductor single crystals.

[Brief description of drawings]

FIG. 1 is a partial schematic cross-sectional view of a semiconductor single crystal manufacturing apparatus, showing a state in which a quartz crucible is filled with a single crystal raw material.

FIG. 2 is a partial schematic cross-sectional view of a semiconductor single crystal manufacturing apparatus, showing a state in which a radiation screen is installed at a predetermined position.

FIG. 3 is a partial schematic cross-sectional view of a semiconductor single crystal manufacturing apparatus, showing an embodiment of the single crystal manufacturing method of claim 5;

FIG. 4 is a diagram showing a state in which a lower screen and an upper screen are simultaneously pulled upward based on the semiconductor single crystal manufacturing apparatus of claim 3 and the semiconductor single crystal manufacturing method of claim 6.

FIG. 5 is an enlarged view of a P portion of FIG.

FIG. 6 is a partial schematic cross-sectional view of a semiconductor single crystal manufacturing apparatus, showing a state in which a lower screen is supported by a hanging jig.

[Explanation of symbols]

 1 Main Chamber 2 Graphite Crucible 3 Quartz Crucible 4 Raw Material 8 Upper Screen 8a Protrusion 9 Upper Chamber 10 Elevating Rod 11 Lower Screen 11a Joint 14 Nail Claw

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Noboru Furuichi 2612 Shinomiya, Hiratsuka City, Kanagawa Prefecture Komatsu Electronic Metals Co., Ltd.

Claims (6)

[Claims] 1. A crucible for filling a raw material of a semiconductor single crystal, a heater for melting the raw material in a crucible around the crucible, and a pulling mechanism for pulling the single crystal by immersing the seed crystal in the melted raw material. In a single crystal manufacturing apparatus in which a radiant screen that surrounds the periphery of the single crystal is arranged above the vicinity of the melt, the radiant screen is divided into upper and lower parts, and a joint portion is provided at a connecting portion between the upper screen and the lower screen. An apparatus for producing a semiconductor single crystal, comprising an upper screen attached to a predetermined position during single crystal production and a mechanism for elevating and lowering a lower screen. 2. The apparatus for producing a semiconductor single crystal according to claim 1, wherein the lower screen lifting mechanism is provided with an upper screen locking mechanism that locks the upper screen so as to be lifted and lowered. 3. The lower screen lifting mechanism is connected to the lower ends of a plurality of vertically movable rods, and the upper screen hooking mechanism is provided at the lower ends of the rods. The semiconductor single crystal manufacturing apparatus according to claim 2, wherein an upper screen having a projection to be stopped on an upper end surface is attached at a predetermined position during manufacturing of the single crystal. 4. When filling a crucible with a raw material, a lower screen lifting mechanism is used to pull the lower screen upward in the chamber, and after the raw material is completely melted, the lifting mechanism is driven to lower the lower screen. The method for producing a semiconductor single crystal using the semiconductor single crystal production apparatus according to claim 1, further comprising: 5. When filling a crucible with a raw material, the lower screen is lifted up into the chamber by using a lower screen lifting mechanism, and when the raw material is melted, the lifting mechanism is driven as the raw material top is lowered to drive the lower screen. 2. The method for producing a semiconductor single crystal according to claim 1, wherein the lower screen is joined to the upper screen when the raw material is completely melted. 6. When filling a crucible with a raw material, a lower screen lifting mechanism is used to pull the lower screen upward in the chamber, and when the raw material is melted, the lifting mechanism is driven as the raw material top is lowered to drive the lower screen. Is gradually lowered, and the lower screen is joined to the upper screen when the raw material is completely melted, and after the single crystal is completely pulled, the lower screen and the upper screen hooked by the elevating mechanism are pulled upward in the chamber. A method for producing a semiconductor single crystal using the apparatus for producing a semiconductor single crystal according to claim 2.