JP2939918B2 - Semiconductor single crystal manufacturing apparatus and manufacturing method - Google Patents

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 manufacturing apparatus having a radiation screen surrounding the pulled single crystal and having a lower end close to the melt surface, and a semiconductor using the manufacturing apparatus. The present invention relates to a method for producing a single crystal.

[0002]

2. Description of the Related Art A Czochralski method (hereinafter referred to as a CZ method) for pulling a columnar single crystal from a raw material melt in a crucible is used as one of the methods for manufacturing a silicon single crystal which is a basic material of a semiconductor integrated circuit. Have 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 periphery of the crucible, and a seed crystal attached to a seed chuck is removed. The single crystal is grown by dipping 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 provided 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 of the 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 smaller in diameter than an upper end opening. The radiant screen cuts off the radiant heat applied to the single crystal from the melt, heater, crucible, etc., thereby promoting the cooling of the single crystal, increasing the pulling speed of the single crystal, and pulling up the inert gas introduced from above the chamber. By guiding the gas around the crystal and forming a gas flow from the center of the crucible to the lower part of the chamber through the periphery, it inhibits single crystallization such as silicon oxide generated from the melt and metal vapor generated from the graphite crucible. It has a function to eliminate gas.

However, when the single crystal raw material is filled in the quartz crucible with the radiation screen fixed above the crucible, the radiation screen hinders the filling, and the raw material is more filled than when no radiation screen is provided. The amount will be small. For this reason, the productivity of the single crystal is reduced, and the production cost is increased. It is also known that the oxygen concentration in a single crystal changes significantly depending on the distance between the lower end of the radiation screen and the melt surface. As an example of a technique for solving this problem, Japanese Unexamined Patent Publication (Kokai) No. 3-279290 discloses a technique in which a suspending member capable of vertically reciprocating is provided on an upper plate of a chamber and a radiation screen is supported in the chamber by the suspending member. Is disclosed. With this technique, the radiant screen can be retracted upward in the chamber during filling and melting of the raw material, so that the raw material filling amount does not need to be reduced. After the melting of the raw material is completed, the radiation screen is lowered around the single crystal pulling region, and the distance between the melt surface and the lower end of the radiation screen can be arbitrarily adjusted. Therefore, variation in the oxygen concentration in the single crystal can be suppressed.

[0004]

However, in the single crystal manufacturing apparatus according to the prior art described above, the entire radiation screen is retracted upward in the chamber when the raw material is melted. The time gets longer. When the melting power is increased to shorten the melting time of the raw material, the quartz crucible is softened and easily deformed, and stable crystal growth becomes difficult. Therefore, the manufacturing cost of a product manufactured by the single crystal manufacturing apparatus is increased. The present invention has been made in view of such conventional problems, and it is possible to retreat a radiation screen upward in a chamber at the time of filling and melting a raw material, and it is not necessary to extend a raw material melting time. It is an object 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 filled with a semiconductor single crystal raw material and 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 and pulling up a single crystal, and a radiation screen surrounding the periphery of the single crystal are arranged above the vicinity of the melt, the radiation screen is moved up and down. And a connecting portion is provided at a connection portion between the upper screen and the lower screen, and the upper screen is attached to a predetermined position at the time of manufacturing a 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 and allows the upper screen to move up and down. Connects the upper end of the lower screen to the lower end of a plurality of vertically movable rods constituting the lower screen elevating mechanism, and provides an upper screen hooking mechanism at the lower end of the rod, and is hooked by this hooking mechanism. An upper screen having a projection on the upper end surface may be attached to a predetermined position at the time of manufacturing a single crystal. The method for manufacturing a semiconductor single crystal using the above-described semiconductor single crystal manufacturing apparatus is characterized in that, when filling the crucible with the raw material, the lower screen is raised upward in the chamber using a lower screen lifting mechanism, and after the melting of the raw material is completed, The lower screen is lowered by driving the mechanism, and the lower screen is joined to the upper screen.Or, at the time of charging the raw material into the crucible, the lower screen is raised upward in the chamber using the lower screen lifting mechanism, and the raw material is removed. During melting, the lower screen may be gradually lowered by driving the elevating mechanism with the lowering of the top of the raw material, and the lower screen may be joined to the upper screen when the melting of the raw material is completed. At the time of filling, the lower screen is pulled up inside the chamber using the lower screen lifting mechanism 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 hung by the elevating mechanism may be lifted upward in the chamber.

[0006]

According to the above construction, the radiation screen is divided into an upper screen and a lower screen, and a mechanism for raising and lowering the lower screen is provided. Therefore, the lower screen can be pulled upward in the chamber as required. Therefore, when the crucible is filled with the single crystal raw material, if the lower screen is raised in advance, 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 portion of the heater and the crucible is covered with the upper screen, and the heat retention of the upper portion of the heater is significantly improved. Therefore, the time required for dissolution can be reduced without increasing the electric power during dissolution. In addition, when the raw material is melted, the lower screen is gradually lowered by driving the elevating mechanism with the lowering of the raw material top, so that the heat retention of the heater upper part is further improved, and the time required for melting the raw material is further reduced. be able to.

According to another aspect of the present invention, the upper end of the lower screen is connected to the lower end of a plurality of vertically movable rods constituting the lower screen elevating mechanism, and the upper end of the rod is connected to the lower end of the rod. A screen locking mechanism is provided, and a projection locked by the locking mechanism is provided on the upper end surface of the upper screen to be attached to a predetermined position at the time of manufacturing a single crystal, so that the rod is raised to lower the lower screen. When lifted, the upper screen can be raised at the same time. Therefore, after the completion of the pulling of the single crystal based on the method of manufacturing a single crystal according to claim 6, the cooling of the hot zone parts is accelerated by driving the lifting / lowering mechanism to pull the lower screen and the upper screen upward in the chamber. Can be.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a 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 single crystal material is filled in a quartz crucible, and FIG. 2 shows a radiation screen after melting of the material is completed. This shows a state where the camera is installed at a predetermined position. In FIG. 1, a quartz crucible 3 is fitted to a graphite crucible 2 installed in a main chamber 1, and a raw material 4 is filled in the quartz crucible 3. 5 is a graphite heater, 6 is a heat insulating cylinder, all of which are disposed so as to surround the graphite crucible 2.
The upper screen 8 is attached to the upper end of the upper surface via a support 7. The upper screen 8 includes an annular flange portion and a short hollow conical tubular portion connected to the inner edge of the flange portion. The outer edge of the flange portion is inserted into the support 7. The upper portion near the inner periphery of the graphite heater 5 and the quartz crucible 3 is 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 lifting rod 10 is attached to the upper chamber 9. The lower screen 11 is a hollow conical cylinder having a joining portion 11a at the upper end thereof for joining with a lower end of the upper screen 8, and a connecting member 1
2 and is fixed to the lower end of the elevating rod 10. The lower screen 11 may be supported by the lower end of the lifting rod 10 via the connecting member 12. In addition, 13 is a crucible shaft.

An embodiment of a method for manufacturing a single crystal using the above-described semiconductor single crystal manufacturing apparatus will be described. When filling the quartz crucible 3 with the single crystal raw material, the lifting rod 10 is driven as shown in FIG. 1 to raise the lower screen 11 to a height close to the inner surface of the upper chamber 9 in advance. 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 a predetermined amount of the raw material can be easily filled. it can. Further, the crucible shaft 13 may be driven as needed to adjust the height of the crucible. After filling the raw material 4 in the quartz crucible 3, 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. As a result, the raw material can be efficiently dissolved. After the dissolution of the raw material 4 is completed, the lower screen 11 is lowered as shown in FIG.
It is joined to the upper screen 8. Thereafter, the seed crystal is immersed in the melt and pulled up while growing the single crystal.

[0010] Using this semiconductor single crystal manufacturing apparatus,
When g of the single crystal raw material was melted, the time required for melting was 5 hours and 45 minutes on average. When a conventional single crystal manufacturing apparatus that retracts the entire radiation screen upward is used, the average value of the melting time is 6 hours and 37 minutes, and the improvement can shorten the melting time 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 moving the crucible up and down, the oxygen concentration in the single crystal could be suppressed to a predetermined range.

Next, an embodiment of the method for producing a single crystal according to claim 5 is shown in FIG. At the time of charging the single crystal raw material 4 into the quartz crucible 3 and at the time of starting melting, 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, the dissipation of heat toward the upper chamber 9 can be further prevented. The average value of the time required for dissolving the raw material when using this method was 5 hours and 32 minutes. Therefore,
13 more than the case where heat is shielded only by the upper screen
The time required for dissolving the raw material by 3% can be shortened. Therefore, a total reduction of 65 minutes, or 16%, is possible with respect to the conventional melting time required for retracting the entire radiation screen upward.

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. FIG. 5 is an enlarged view of a portion P in FIG. 4. Elevating rod 10 for elevating the lower screen 11
A hook claw 14 is pivotally mounted on the lower end of the arm, and is rotatable within a range of less than 90 ° from an obliquely upward direction to a horizontal direction. On the upper surface of the flange portion of the upper screen 8, a cylindrical projection 8a hooked by the hook 14 is provided.
Is fixed. The operation of filling the quartz crucible 3 with the raw material and dissolving the raw material is as described above. 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 protrusion 8 of the upper screen 8 in a state of protruding in the horizontal direction.
a, and descends while being pushed up by the projection 8a, and then projects again below the projection 8a in the horizontal direction. After the pulling of the single crystal is completed, the elevating mechanism is driven to move the elevating rod 1
0, the hooking claw 14 comes into contact with the lower surface of the projection 8a, and together with the lower screen 11, the upper screen 8
Is also pulled upward in the chamber. By this operation, heat dissipation of the hot zone parts is accelerated, and the waiting time for maintenance in the furnace can be reduced. By using this method, the required cooling time in the furnace could be reduced by about 60 minutes and 13%.

[0013] Without providing a dedicated radiation screen lifting mechanism,
As shown in FIG. 6, a suspending jig 16 may be mounted on the seed crystal holder 15 instead of the seed chuck, and the lower screen 11 may be supported by the suspending 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 a lower end of the shaft 16a;
b, consisting of three hooks 16c attached to the lower end,
By hooking the hook 16c on the lower end of the lower screen 11, the lower screen 11
It is supported by 6. At the time of raw material filling and melting, 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 suspending jig 16 is used, after the lower screen 11 is joined to the upper screen 8, it takes time to replace the suspending jig 16 attached to the seed crystal holder 15 with the seed chuck. The time was 5 hours and 50 minutes. However, the hanging jig is inexpensive compared to the installation cost of the radiant screen raising / lowering mechanism. Even in a single crystal manufacturing apparatus without the radiant screen raising / lowering mechanism, the raw material melting time can be reduced by raising and lowering the lower screen, and the single crystal Manufacturing costs can be reduced.

[0014]

As described above, according to the present invention, the radiation screen surrounding the single crystal pulling region is divided into an upper screen and a lower screen, and the lower screen is used by filling and melting the single crystal raw material by using the lifting mechanism. Is lifted upward in the chamber, so that the raw material can be easily filled, and the heat retaining property of the upper portion of the heater can be significantly improved by the upper screen attached at a predetermined position during the production of the single crystal. Therefore, it is possible to shorten the time required for dissolving 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 is lowered, the heat retention of the upper part of the heater is further improved, and the time required for melting the raw material can be further reduced. Further, after the completion of the pulling of the single crystal, if the upper screen is pulled upward in the chamber together with the lower screen, 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 the 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 the semiconductor single crystal manufacturing apparatus, showing a state where 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 according to claim 5;

FIG. 4 is a view 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 portion P in FIG. 4;

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

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Main chamber 2 Graphite crucible 3 Quartz crucible 4 Raw material 8 Upper screen 8a Projection 9 Upper chamber 10 Elevating rod 11 Lower screen 11a Joining part 14 Hanging claw

Continuation of the front page (56) References JP-A-64-18988 (JP, A) JP-A-6-135792 (JP, A) JP-A-6-92772 (JP, A) JP-A-5-339092 (JP, A) , A) JP-A-3-279290 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) C30B 1/00-35/00

Claims (6)

(57) [Claims] 1. A crucible for filling a raw material of a semiconductor single crystal, a heater surrounding the crucible for melting the raw material in the crucible, a pulling mechanism for dipping a seed crystal in the melted raw material and pulling the single crystal. In a single crystal manufacturing apparatus in which a radiation screen surrounding the periphery of the single crystal is disposed above the vicinity of the melt, the radiation screen is divided into upper and lower parts, and a joint is provided at a connection portion between the upper screen and the lower screen, An apparatus for manufacturing a semiconductor single crystal, comprising: a mechanism for mounting an upper screen at a predetermined position when a single crystal is manufactured and a mechanism for raising and lowering the lower screen. 2. The semiconductor single crystal manufacturing apparatus according to claim 1, wherein the lower screen raising / lowering mechanism is provided with an upper screen hooking mechanism which hooks the upper screen to be able to move up and down. 3. An upper screen latching mechanism is provided at a lower end of the lower screen, and an upper screen latching mechanism is provided at a lower end of the plurality of vertically movable rods constituting the lower screen lifting mechanism. 3. 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 to a predetermined position in manufacturing the single crystal. 4. When filling the crucible with a raw material, the lower screen is lifted upward in the chamber by using a lower screen elevating mechanism, and after the melting of the raw material is completed, the elevating mechanism is driven to lower the lower screen. Is joined to an upper screen, the method for manufacturing a semiconductor single crystal performed by using the apparatus for manufacturing a semiconductor single crystal according to claim 1. 5. A lower screen is lifted upward in a chamber by using a lower screen lifting mechanism when filling the raw material into the crucible, and when the raw material is melted, the lower screen is driven by driving the lifting mechanism as the top of the raw material is lowered. 2. The method for manufacturing a semiconductor single crystal according to claim 1, wherein the lower screen is joined to the upper screen when melting of the raw material is completed. 6. A lower screen lifting mechanism is used to lift the lower screen upward in the chamber when filling the crucible with the raw material, and the lower screen is driven by lowering the raw material top as the raw material dissolves. Is gradually lowered, and the lower screen is joined to the upper screen when the dissolution of the raw material is completed. After the pulling of the single crystal is completed, the lower screen and the upper screen hooked by the elevating mechanism are pulled upward in the chamber. A method for manufacturing a semiconductor single crystal using the apparatus for manufacturing a semiconductor single crystal according to claim 2.