JP3151322B2 - Method and apparatus for producing single crystal - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for producing a single crystal used as a material of a single crystal substrate for manufacturing a semiconductor circuit, and more particularly, to a method for reducing the amount of oxygen precipitated from a single crystal. The present invention relates to a method and an apparatus for producing a single crystal body which is made uniform regardless of the above.

[0002]

2. Description of the Related Art In the field of semiconductor manufacturing, the Czochralski method has been generally used as a method for growing a silicon single crystal. As an example of an apparatus using this method, for example, an apparatus as shown in FIG. 4 (JP-A-63-319293) and FIG. 5 (JP-A-64-65086) can be exemplified.

An apparatus 1 shown in FIG. 4 comprises a heating chamber 2a for mainly containing a structure for melting silicon and a pulling chamber 2 for storing a silicon crystal S to be pulled.
The crucible 5 and the heater 6 arranged so as to surround mainly the side surface of the crucible 5 are provided in the heating chamber 2a. The crucible 5 contains the silicon melted by the heater 6. The crucible 5 is connected to a driving device (not shown) by the rotating shaft 4, and is rotated at a predetermined speed by the driving device. Usually, the crucible 5 includes a quartz crucible 5a and a graphite crucible 5b for protecting the quartz crucible 5a.

On the other hand, a pull-up wire 7 is provided in the pull-up chamber 2b and penetrated through the top wall, and a chuck 9 for holding a seed crystal 8 is provided at a lower end of the pull-up wire 7. The upper end side of the pulling wire 7 is wound around a wire hoist 10 so as to pull up the silicon crystal S at a predetermined speed. The heat insulating member 11 is provided on the heating chamber 2a side of the illustrated heater 6 in order to prevent heat from the heater 6 from escaping to the outside of the heating chamber 2a.

In the chamber 2, a lifting chamber 2b
Argon gas is introduced from the gas inlet 12 formed in the heating chamber 2a, and flows through the heating chamber 2a evenly as shown in FIG. The reason why the argon gas is made to flow in this way is to prevent carbon dioxide gas generated in the chamber 2 due to the melting of silicon from being mixed into the silicon melt. In the pulling chamber 2b, the portion above the silicon crystal to be pulled (temperature is lower than 1000 ° C.) is rapidly cooled, while the portion near the solid-liquid interface of the silicon melt (temperature is higher than 1000 ° C.) is gradually cooled. The cooling control member 14 which functions is mounted. The portion of the cooling control member 14 in contact with the lifting chamber 2b is configured to promote cooling of the silicon crystal.
The portion extending in a cone shape in b is configured to reflect the radiant heat from the molten silicon to the silicon crystal body S side. By the action of the cooling control member 14,
The temperature history of the growing silicon single crystal is made uniform so that the thermal history of the silicon crystal becomes closer to the ideal, and in particular, the amount of precipitated oxygen in the silicon crystal can be reduced.

The device having the structure shown in FIG. 5 is also similar to the device shown in FIG. 4 in that the gas flow is improved so that the silicon crystal S is given an ideal thermal history. Since most parts of the configuration shown in this figure are the same as those shown in FIG. 4, the same members are denoted by the same reference numerals. The only difference from the configuration of the apparatus shown in FIG. 4 is that a cylinder 15 extending from the heating chamber 2a to the vicinity of the solid-liquid interface is attached, and an inverted conical collar 16 is attached to the tip.

The presence of the cylinder 15 ensures that the argon gas supplied from the gas inlet 12 always passes through the cylinder 15 and is introduced into the chamber 2 from the solid-liquid interface. The side will be quenched. The collar 16 blocks molten silicon and radiant heat from the heater 6, thereby making it possible to adjust the thermal history of the silicon crystal S being pulled up over a wide range.

[0008]

However, in the conventional single-crystal body manufacturing apparatus capable of obtaining an ideal heat history, the heat history is controlled by the heater 6 or the silicon melt. Since the radiant heat from the above is simply used, the control of the heat history has a certain limit.

Therefore, although the amount of precipitated oxygen is certainly suppressed, its effect is not sufficient, and it has not been possible to completely prevent the yield in the integrated circuit manufacturing process from lowering.

Further, when a quality index called an oxide film breakdown voltage, which is said to correspond well to the yield in the integrated circuit manufacturing process, was examined, no significant improvement was found although it was somewhat better than the conventional method.

Further, when the amount of precipitated oxygen of the single crystal produced by the apparatus shown in FIG. 4 is examined, as shown in FIG. 6, the amount of precipitated oxygen is not large at the top and bottom sides of the crystal. You can see that it is uniform. When the amount of precipitated oxygen is not uniform, there is a problem that the yield when manufacturing a semiconductor integrated circuit using the silicon single crystal thus produced is reduced. In order to prevent this, conventionally, the length of the silicon single crystal is limited to a short length, and when the crystal is completed, the crystal is prevented from plunging into the upper chamber 2c, the amount of oxygen precipitation is suppressed to a small level, and the uniformity is maintained. Keeping has been done.

However, in this method, the straight portion that can be processed on the wafer is shortened, and the ratio of the head to the tail is increased. This not only reduces the yield but also lowers the productivity. there were.

SUMMARY OF THE INVENTION The present invention has been made in view of such conventional problems, and a high-frequency coil capable of selectively generating heat at an arbitrary portion and absorbing heat at portions other than the heat generating portion is provided. It is an object of the present invention to provide a method for producing a single crystal having a uniform oxygen precipitation amount while realizing an ideal heat history by positively adjusting the temperature of the single crystal and a device therefor.

[0014]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a single crystal in which a seed crystal is brought into contact with a melt melted in a crucible and a single crystal is grown by gradually pulling the seed crystal. In the method for manufacturing a crystal, a hollow metal tube through which a coolant flows is spirally wound, and a high-frequency coil that can partially generate heat is pulled up in a pulling path of the single crystal. The single crystal body is disposed at a position near the outer peripheral surface of the body so as to surround the single crystal body, heats a desired portion of the high-frequency coil, gradually cools the outer peripheral surface of the single crystal body to be pulled up, and the inside of the high-frequency coil. And cooling the outer peripheral surface of a portion of the single crystal body requiring cooling to be rapidly cooled.

Further, in a method of manufacturing a single crystal in which a single crystal is grown by bringing a seed crystal into contact with a melt melted in a crucible and gradually pulling up the seed crystal, a hollow through which a coolant flows is provided. A metal tube is spirally wound and surrounds the high-frequency coil, which can partially generate heat, at a position near the outer peripheral surface of the single crystal to be pulled in the pulling path of the single crystal. So that
Until the single crystal is pulled up a predetermined distance, a desired portion of the high-frequency coil is heated to gradually cool the outer peripheral surface of the single crystal to be pulled up, and a coolant is allowed to flow through the high-frequency coil. The outer peripheral surface of the portion requiring cooling of the single crystal body is quenched, and thereafter, the degree of gradual cooling of the outer peripheral surface of the single crystal body is reduced by reducing the calorific value of the high-frequency coil in a state where the coolant is circulated. It is characterized by being weakened.

Further, in a single crystal production apparatus for pulling and growing a single crystal from a melt melted in a crucible,
A hollow metal tube through which the coolant flows is spirally wound, and surrounds the single crystal body at a position near the outer peripheral surface of the single crystal body to be pulled during the pulling path of the single crystal body. A high-frequency coil that can partially generate heat, a coolant supply unit that circulates a coolant through the high-frequency coil, and selectively supplies high-frequency power to a desired portion of the high-frequency coil, A heating value adjusting means configured to adjust a heating value in accordance with a pull-up distance of the single crystal body.

[0017]

When manufactured by the above-described process, the portion of the single crystal which is considered to be preferably cooled gradually is preferably heated by a heater in terms of quality. The part which seems to be more preferable will be quenched, and the degree of heating varies depending on the part of the single crystal body,
The thermal history can be made closer to the ideal one, and a single crystal having extremely high quality can be manufactured.

Further, with the above-described configuration, the heat generating portion of the high-frequency coil can be set to some extent freely in accordance with the heat history required for the single crystal body, and the heat generation amount of the high-frequency coil can be reduced. The amount can be adjusted according to the pulling distance of the single crystal body by the amount adjusting means. By optimizing this adjustment in accordance with the pulling of the single crystal, a very ideal thermal history can be realized.

[0019]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a schematic configuration diagram of an apparatus for producing a single crystal according to the present invention, and FIG. 2 is a detailed configuration diagram of a high-frequency heater provided in the apparatus shown in FIG.

The single crystal manufacturing apparatus 1 has a member for melting silicon, a mechanism for pulling up crystallized silicon, and the like. The member for melting silicon is housed in a heating chamber 2a. The mechanism for pulling the silicon single crystal is provided inside and outside the pulling chamber 2b which can be separated from the heating chamber 2a by the separating mechanism 20.

A crucible 5 for accommodating molten silicon is provided in the heating chamber 2a. The crucible 5 is supported by a driving device 22 by a rotating shaft 4 so as to be rotatable and vertically movable. The driving device 22 raises the crucible 5 by an amount corresponding to the lowering of the liquid level to compensate for the lowering of the liquid level due to the pulling of the silicon single crystal S, and constantly rotates the crucible 5 at a predetermined rotational speed for stirring the silicon melt. Rotate with. Rotary axis 4
Penetrates through the heating chamber 2a, but is held by a special bearing 23 in order to maintain airtightness inside and outside the chamber and to be used under extremely poor temperature conditions. The crucible 5 comprises a quartz crucible 5a and a graphite crucible 5b for protecting the same as in the prior art.

A heater 6 for melting silicon is arranged on the side wall of the crucible 5 so as to surround the periphery thereof. Outside the heater 6, a heat insulating member 11 for preventing heat from the heater 6 from being directly radiated to the heating chamber 2a is provided so as to surround the periphery thereof. Note that the heater 6 and the heat insulating member 11 are attached to a support 24. The support 24 is manufactured using a material having a very large thermal resistivity.

One end of the wire hoisting machine 10 is attached to the lifting chamber 2b.
A pull-up wire 7 is provided which is hung down through the top wall of the pull-up wire 7, and a chuck 9 for holding a seed crystal 8 is attached to a lower end of the pull-up wire 7. The wire hoist 10 pulls up the silicon single crystal S that gradually grows on the lower end side of the seed crystal 8 in accordance with the growth rate or the like, and at the same time, constantly rotates the crucible 5 in the direction opposite to the rotation direction.

In the chamber 2, a lifting chamber 2b
Argon gas is introduced from the gas inlet port 12 formed in the heating chamber 2a, and flows through the heating chamber 2a evenly and is discharged from the gas outlet port 13. The flow of the argon gas in this manner is to prevent the SiO 2 gas generated in the chamber 2 due to the melting of the silicon from being mixed into the silicon melt.

The lifting chamber 2b is provided with a high-frequency coil 30 formed by spirally winding a hollow copper tube. The arrangement position of the high-frequency coil 30 is such that slow cooling and rapid cooling can be performed on a desired portion of the silicon single crystal body S to be pulled up.
Specifically, the temperature of the silicon single crystal body S from which the heat-generating portion of the high-frequency coil 30 is pulled is raised from 900 ° C. to 11 ° C.
The position where the portion exhibits 00 ° C. is optimal.

As will be described later, this high-frequency coil 30
It is configured to be able to generate heat in a predetermined part,
This embodiment is configured so that heat can be selectively generated at three different portions. Therefore, it can be said that this arrangement may not be so strict.However, in each device, how long it is arranged from the silicon melt surface, how long the winding length of the high frequency coil is, Further, it is preferable to appropriately determine how much the capacity of the coil is set so as to obtain an optimum thermal history for the silicon single crystal. The high-frequency coil 30 is connected to a high-frequency heating device 40 functioning as a heating value adjusting means, and a predetermined portion of the high-frequency coil 30 is heated by high-frequency power supplied from the device.
The high-frequency heating device 40 can selectively supply high-frequency power to a predetermined portion of the high-frequency coil 30 and is configured to be able to freely adjust the supplied power. The flexibility of these power supply parts and power supply amounts
The silicon single crystal can be arbitrarily used depending on the diameter and the conductivity type (P type, N type).

The high-frequency coil 30 is composed of a hollow copper tube 41, into which cooling water is supplied from a water supply device 45 functioning as a coolant supply means. The cooling water is constantly circulated from the upper side to the lower side of the high-frequency coil 30 as shown in the figure to enable rapid cooling of a predetermined portion of the silicon single crystal S. In this embodiment, water is exemplified as the coolant, but the present invention is not limited to this, and other liquids and gases can be used.

FIG. 2 is a diagram showing a specific configuration of the high-frequency coil 30. As shown in the drawing, the high-frequency coil 30 is formed by spirally winding a hollow copper tube 31. The high-frequency coil 30 is provided at a predetermined interval in the high-frequency heating control device 40. Are connected to the power supply lines 41A to 41D, respectively. Therefore, the power supply line 4
When high-frequency power is supplied to 1A and 41B, the portion X in the figure generates heat, and this portion functions as a heat generating portion. In addition, since the cooling water is constantly supplied to the copper tube 31 from the water supply device 45, the Y and Z portions other than the heated X portion function as a heat absorbing portion. When the Y portion functions as a heating section, the power supply lines 41B and 41C
In the case where the Z portion functions as a heating unit, high-frequency power is supplied to the power supply lines 41C and 41D, respectively. It goes without saying that the part of the high-frequency coil 30 other than functioning as a heat generating part functions as a cooling part.

As described above, only a part of the high-frequency coil 30 is made to function as a heating part, and the other part is made to function as a cooling part. Since cooling can be performed, heat history can be adjusted widely. Further, when it is necessary to heat different parts in order to change the heat history, it is only necessary to switch the energized part of the high-frequency coil 30 by the high-frequency heating control device 40. For example, the power supply lines 41A and 41A
If high-frequency power is supplied to B and B, the 1100 ° C. region of the silicon single crystal body S being pulled up can be gradually cooled, and high-frequency power can be supplied to 41B and 41C. If this is the case, the 1000 ° C. region of the silicon single crystal body S can be gradually cooled. Similarly, if high-frequency power is supplied to 41C and 41D, the region of 900 ° C. can be gradually cooled. Since the power supply lines 41A to 41D connected to the high-frequency coil 30 are exposed to considerable heat, it is necessary to use electric wires having excellent heat resistance.

Next, the operation of the apparatus of the present invention configured as described above and the method of the present invention realized by the apparatus will be described in detail.

First, in manufacturing a silicon single crystal, the pulling chamber 2b is separated from the heating chamber 2a by the separation mechanism 20, and a crude silicon crystal as a raw material and a very small amount of impurities are charged into the crucible 5; The lifting chamber 2b is attached to the heating chamber 2a by the separation mechanism 20. In this state, the heater 6 is heated to wait for the silicon in the crucible 5 to be melted. When the silicon is in a molten state, the wire hoist 10 is operated to pull down the wire 7 so that the seed crystal attached to the chuck 9 is in contact with the silicon melt surface. In this state, when the silicon crystal begins to grow on the seed crystal, the wire hoist 10 is pulled up at a predetermined speed to grow the silicon crystal S as shown in FIG. Along with this lifting, a predetermined portion of the high-frequency coil 30 is heated by the high-frequency heating control device 40. The high-frequency coil 30 includes a portion selected in advance (for example, a portion X in FIG. 2).
Although electric power is supplied from the heating control device 40, approximately 7 Kw of electric power is supplied from the start of the pulling to the raising of a predetermined distance, and the heating portion of the high-frequency coil 30 is kept at a relatively high temperature. Thus, the quenched state of the silicon single crystal body S that is being pulled up is changed to a gradually cooled state.

FIG. 3 shows how the power supply to the high-frequency coil 30 is changed. As shown in FIG.
The power supply to 0 is set relatively high while the top side of the ingot passes through the high-frequency coil 30 in general,
Otherwise, set it lower. The reason is as follows.

The upper side of the ingot is the upper chamber 2c.
It cools down slowly enough. On the other hand, in a high temperature region of 1100 ° C. or more, many defect nuclei are formed, and oxygen is diffused and coagulated into the defect nuclei during cooling sufficiently slowly in the upper chamber 2c, and many oxygen precipitate nuclei are formed. It is formed. Therefore, the amount of precipitated oxygen increases. However, 1
In the range of 100 ° C. to 900 ° C., a phenomenon occurs in which the defect nuclei formed in the high temperature range of 1100 ° C. or more disappear.
Therefore, a part corresponding to this temperature is set to the high-frequency coil 3.
When heated by 0, the defect nuclei disappear and the upper chamber 2
Even if cooled slowly in c, the amount of precipitated oxygen does not increase.

Further, the existence of the non-power supply section (cooling section) of the high-frequency coil 30 is from 1100 ° C. to 900 ° C.
It has the effect of rapidly cooling the temperature range other than the above, so that the diffusion and coagulation of oxygen and the formation of oxygen precipitation nuclei can be more completely suppressed, and as a result, a factor that reduces the yield in the integrated circuit manufacturing process. It has the effect of being able to eradicate outbreaks.

On the other hand, the bottom side of the ingot is immediately wound up in the upper chamber 2c after the formation of the crystal tail, so that it is rapidly cooled. Therefore, diffusion aggregation of oxygen and oxygen precipitation nuclei are hardly formed, and the amount of precipitated oxygen tends to be reduced. Therefore, from 1100 ° C to 90
The degree to which the temperature is gradually cooled in the range of 0 ° C. should be warmed as compared to the top side of the ingot. Therefore, the power supplied to the annular heater 30 is set lower. The effect of quenching a temperature other than 1100 ° C. to 900 ° C. is described in the same manner as the ingot top side.

As described above, according to the present invention, the portion to be heated and the portion to be cooled can be clearly distinguished, and the heating and cooling portions matching the respective portions such as the top side and the bottom side of the ingot. Since control is possible, it becomes possible to efficiently produce a high-quality silicon single crystal in which the amount of precipitated oxygen is strictly controlled, which was impossible with the prior art.

In order to confirm this, an experiment was conducted to compare the amount of precipitated oxygen, the OSF, and the withstand voltage of the oxide film of the single crystal body manufactured based on the apparatus and method of this embodiment with those of the prior art. In this experiment, the high-frequency coil 30 was arranged at about 200 to 300 mm from the silicon melt surface, and power was supplied to a portion of the single crystal body located at around 900 ° C. so that the single crystal body became a heating unit. Around 900 ° C. was gradually cooled. The single crystal to be compared was manufactured using the apparatus shown in FIG.

The OSF was evaluated by the area density of etch pits after heat treatment at 1100 ° C. in a wet oxygen atmosphere for 60 minutes. With respect to the oxide film breakdown voltage, a polysilicon MOS diode was formed on a wafer, the dielectric breakdown characteristics of the oxide film when a voltage was applied thereto was examined, and the average breakdown voltage was used as the oxide film breakdown voltage.

[0039]

[Table 1]

As can be seen from the above results, when the method of the present invention is carried out using the apparatus of the present invention, all parts of the single crystal are as shown in the above table and also as shown in FIG. In addition, a uniform amount of precipitated oxygen is exhibited. Further, the withstand voltage of the oxide film can be improved.

[0041]

As described above, according to the present invention, a portion requiring slow cooling is heated at an arbitrary temperature by a high-frequency coil when pulling up a single crystal body. The film withstand voltage can be improved, and the amount of precipitated oxygen can be made uniform regardless of the location of the ingot.

Further, since the heat generating portion of the high-frequency coil and the heat generation amount thereof can be arbitrarily adjusted by the heat generation amount control means, the heat history of the single crystal can be positively adjusted.

In addition, since it is possible to produce a uniform crystal irrespective of the length of the single crystal body by appropriate use of the present invention, a pulling method for producing a long crystal such as a continuous feed can be used. Is very effective.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of an apparatus for producing a single crystal according to the present invention.

FIG. 2 is a detailed view of the high-frequency coil shown in FIG.

FIG. 3 is a diagram provided for describing an effect of the present invention.

FIG. 4 is a schematic configuration diagram of a conventional single crystal manufacturing apparatus.

FIG. 5 is a schematic configuration diagram of a conventional single crystal manufacturing apparatus.

FIG. 6 is a diagram showing the amount of oxygen precipitated in a single crystal produced by a conventional apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Single crystal manufacturing apparatus 2 ... Chamber 2a ... Heating chamber 2c ... Upper chamber 2b ... Pulling chamber 5 ... Crucible 6 ... Heater 7 ... Pulling wire 8 ... Seed crystal 30 ... High frequency coil 31 ... Support member 40 ... High frequency heating Control device (heat generation amount adjusting means) 45 ... water supply device (coolant supply means) S ... silicon single crystal (single crystal)

Continuation of front page (72) Inventor Katsuhiko Nakai 3434 Shimada, Hikari-shi, Yamaguchi Prefecture Inside Nippon Steel Corporation Hikari Works (56) References JP-A-59-8696 (JP, A) JP-A-56- 45894 (JP, A) JP-A-4-16589 (JP, A) JP-A-57-205397 (JP, A) JP-B-56-28872 (JP, B2) JP-B-62-3918 (JP, Y2) (58) Field surveyed (Int. Cl. ⁷ , DB name) C30B 1/00-35/00

Claims (3)

(57) [Claims] 1. A method for producing a single crystal in which a seed crystal is brought into contact with a melt to be melted in a crucible and a single crystal is grown by gradually pulling up the seed crystal. A metal tube is spirally wound and surrounds the high-frequency coil, which can partially generate heat, at a position near the outer peripheral surface of the single crystal to be pulled in the pulling path of the single crystal. It is necessary to cool the outer peripheral surface of the single crystal body that is pulled up by causing a desired portion of the high-frequency coil to generate heat, and to flow a coolant inside the high-frequency coil to cool the single crystal body. A method for producing a single crystal, wherein an outer peripheral surface of a portion is rapidly cooled. 2. A method for producing a single crystal in which a seed crystal is brought into contact with a melt melted in a crucible and a single crystal is grown by gradually pulling up the seed crystal. A metal tube is spirally wound and surrounds the high-frequency coil, which can partially generate heat, at a position near the outer peripheral surface of the single crystal to be pulled in the pulling path of the single crystal. Until the single crystal is pulled up by a predetermined distance, a desired portion of the high-frequency coil is heated to gradually cool the outer peripheral surface of the single crystal to be pulled and a coolant is provided inside the high-frequency coil. To quench the outer peripheral surface of the portion requiring cooling of the single crystal body, and then reduce the calorific value of the high-frequency coil in a state where the cooling material is circulated to reduce the outer peripheral surface of the single crystal body. Xu Method for producing a single crystal body, characterized in that it has to weaken the degree of. 3. A single crystal manufacturing apparatus for pulling and growing a single crystal from a melt melted in a crucible, wherein a hollow metal tube through which a coolant flows is spirally wound, and A high-frequency coil that can partially generate heat and that is arranged so as to surround the single crystal at a position near the outer peripheral surface of the single crystal to be pulled during the crystal pulling path; Material supply means, while selectively supplying high-frequency power to a desired portion of the high-frequency coil, and adjusting the heat generation from the high-frequency coil in accordance with the pull-up distance of the single crystal body. And a means for producing a single crystal.