JPH0859388A - Device for producing single crystal - Google Patents

Abstract

PURPOSE: To obtain a high-quality single crystal by detecting the heat radiated from a melt in a crucible with a temp. detecting means arranged on a radiating screen and adjusting the level of the melt to keep the detected temp. constant. CONSTITUTION: The heat radiated from molten Si in a crucible 5 is detected with a temp. detecting means consisting of a first thermocouple 35a fixed to the lower end of the inclined wall 30b of a funnel shaped board 30 functioning as a radiating screen and a second thermocouple 35b fixed to the upper end, a rotating shaft 4 is rotated by a driving device 40 to keep the detected temp. constant, and the level of the melt is adjusted by lifting the crucible 5 up and down. Meanwhile, an inert gas such as Ar is introduced from a gas inlet 12 provided to the storage part 3b of a chamber 2b in accordance with the difference between the radiated heat detected by both thermocouples, allowed to flow clown toward the crucible 5 in the lifting direction to cool an Si single crystal S to an optimum temp. and discharged from a gas outlet 13 along with gaseous SiO generated when Si is melted, and 3 high-quality Si single crystal is obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for producing a single crystal by the Czochralski method (CZ method), which is capable of producing a high quality single crystal.

[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. An example of an apparatus using this method is an apparatus as shown in FIG. 5 (see Japanese Patent Publication No. 4-44215).

An apparatus 1 shown in FIG. 5 mainly comprises a heating chamber 2a in which a structure for melting silicon is housed and a pulling chamber 2 in which a silicon crystal S to be pulled is housed.
In the heating chamber 2a, a crucible 5 and a heater 6 arranged so as to mainly surround the side surface portion of the crucible 5 are provided. The crucible 5 contains the silicon melted by the heater 6. The crucible 5 is connected to a driving device (not shown) by a rotary shaft 4, and is rotated at a predetermined speed by the driving device. Further, this driving device also has a function of raising and lowering the crucible 5. Usually, the crucible 5 is a quartz crucible 5a and a graphite crucible 5 for protecting it.
b and.

On the other hand, the pull-up chamber 2b has a ceiling portion 3a which closes the opening of the heating chamber 2a and the ceiling portion 3a.
Is located in the central portion of and is mainly composed of an accommodating portion 3b for accommodating the growing silicon single crystal S. In the pulling chamber 2b, a pulling wire 7 that is hung down through the top wall is provided, and a chuck 9 that holds a seed crystal 8 is provided at the lower end of the pulling wire 7. The upper end side of the pulling wire 7 is wound around the wire hoisting machine 10 so that the silicon crystal body S being grown can be pulled up at a predetermined speed. A heat insulating member 11 is provided on the side of the heating chamber 2a of the heater 6 shown, and a board 30 having a V-shaped cross section is attached to the heat insulating member 11. A concentric flat portion 30a is formed on the board 30, and an inclined wall 30b inclined from the inner peripheral end of the flat portion 30a toward the melting surface of the crucible 5 extends in the melt direction while being reduced in diameter. . This inclined wall 30b
Is located near the aforementioned solid-liquid interface. The opening diameter of the opening near the solid-liquid interface formed by the inclined wall 30b is sized so that the camera 27 can image the state of the solid-liquid interface as shown in the drawing.
The heat insulating member 11 has a role of supporting the board 30 and preventing heat from the heater 6 from escaping to the outside of the heating chamber 2a.

Inside the chamber 2, there is a pulling chamber 2b.
Argon gas is introduced from the gas introduction port 12 formed in the heating chamber 2a from the gas introduction port 12 through the inside of the housing portion 3b as shown in the drawing. And is discharged from the gas discharge port 13. The reason why the argon gas is circulated in this way is to cool the silicon single crystal body S being grown and to discharge the SiO gas generated in the chamber 2 due to the melting of silicon to the outside of the system.

In the apparatus for producing a single crystal body having the above-mentioned structure, controlling the position of the melt surface by controlling the elevation of the crucible, that is, the melt position, is the same as the control of the temperature. Since it is very important for growth, the melt position is controlled to be always constant.

Also in the conventional apparatus shown in FIG. 5, a measurement reference point is provided on the board 30 arranged around the pulling region of the single crystal body, and the reference point and the reflection image of the reference point with respect to the melt position are used for the light intensity. It is captured by a linear sensor that emits a signal in accordance with the above, and the melt position is controlled to be constant by the signal from here.

[0008]

However, in the conventional apparatus for producing a single crystal body having such a structure, the melt position is controlled according to the intensity of light. The position will change according to the change in the gloss of the melt in the crucible 5 at the reference point, that is, the melt. Since the gloss of the melt changes discontinuously with time or periodically, it is very difficult to adjust the melt position stably over a long period of time.

If the melt position is not accurately controlled in this manner, the quality of the single crystal body produced will be adversely affected. Therefore, in the present invention, in order to obtain a single crystal body of good quality, A first object of the present invention is to provide an apparatus for producing a single crystal body capable of performing extremely precise control so that the melt position is maintained at a constant position.

Since the quality of a single crystal is greatly affected by the thermal history traced when it is cooled, not only the melt position control but also the amount of inert gas supplied is adjusted. By doing so, it becomes possible to obtain a single crystal body of higher quality.

Therefore, according to the present invention, in order to obtain a high-quality single crystal body, a single crystal body manufacturing apparatus having a function of optimally adjusting the supply amount of the inert gas for directly cooling the single crystal body is provided. The second purpose is provision.

[0012]

A first structure of the present invention for achieving the above object is a crucible supported by a drive device so as to be movable up and down, and a crucible that is pulled up from a melt. A radiant screen provided along the peripheral surface of the single crystal body, a temperature detecting means arranged in the radiant screen to detect radiant heat from the melt, and from the melt detected by the temperature detecting means Liquid level adjusting means for adjusting the liquid level position of the melt surface of the crucible by controlling the driving device so as to keep the radiant heat of the crucible constant.

A second structure for achieving the above object is that a radiant screen is provided along the periphery of a single crystal body pulled up from a melt contained in a crucible, and the radiation screen is provided by an inert gas supply means. A manufacturing apparatus for a single crystal body, wherein the single crystal body is cooled by flowing down an inert gas from the pulling direction side toward the crucible side, wherein the fusion is performed at the upper end portion and the lower end portion of the radiation screen. Temperature detecting means respectively provided to detect radiant heat from the liquid, and the inert gas supply amount from the inert gas supplying means is controlled according to the difference between the radiant heat detected by the temperature measuring means and the temperature detecting means. And an inert gas supply amount control means.

[0014]

The single crystal body manufacturing apparatus of the present invention having the above-described structure functions as follows.

First, in the first construction, the radiant heat of the melt melted in the crucible is detected by the temperature detecting means arranged in the radiant screen, and the detected temperature is constant. The liquid surface position of the melt surface of the crucible is adjusted by the liquid surface position adjusting means so that

Next, in the second structure, the radiant heat of the melt melted in the crucible is detected by the temperature measuring means provided at the upper end and the lower end of the radiant screen. The inert gas supply amount control means controls the supply amount of the inert gas to the single crystal body in accordance with the difference in temperature detected by the temperature detecting means provided at the upper end portion or the lower end portion.

With the apparatus for producing a single crystal body having the first structure or the second structure as described above, the melt position is always kept constant, or the optimum amount of the inert gas is supplied. It becomes possible to manufacture a high-quality single crystal body.

[0018]

Embodiments of the present invention will now be described in detail with reference to the drawings. FIG. 1 is a schematic configuration diagram of an apparatus for producing a single crystal body according to the present invention. This single crystal body manufacturing apparatus 1
Has a member for melting silicon, a mechanism for pulling up crystallized silicon, and the like, and the member for melting silicon is housed in the heating chamber 2a. Lifting chamber 2 separable from 2a by a separating mechanism
It is provided inside and outside b.

A crucible 5 for containing molten silicon is provided in the heating chamber 2a, and the crucible 5 is supported by a drive unit 40 by a rotating shaft 4 so as to be rotatable and vertically movable. The driving device 40 raises the crucible 5 by the amount corresponding to the liquid level lowering to compensate for the liquid level lowering accompanying the pulling of the silicon single crystal S, and also keeps the crucible 5 at a predetermined rotation speed for stirring the silicon melt. Rotate with. The drive device 40 functions as a liquid surface position adjusting means. Although the rotating shaft 4 penetrates the heating chamber 2a, it keeps the inside and outside of the chamber 2 airtight, and since it is used under extremely bad temperature conditions, it is held by a special bearing (not shown). is there. The crucible 5 is a quartz crucible 5a and a graphite crucible 5 for protecting the same as in the conventional case.
b and.

A heater 6 for melting silicon is arranged on the side wall portion of the crucible 5 so as to surround the periphery thereof. A heat insulating member 11 that prevents heat from the heater 6 from directly radiating to the heating chamber 2a is provided outside the heater 6 so as to surround the periphery thereof. A funnel-shaped board 30 that functions as a radiation screen is attached to the heat insulating member 11. A concentric flat portion 30a is formed on the board 30, and an inclined wall 30b inclined from the inner peripheral end of the flat portion 30a toward the melting surface of the crucible 5 extends in the melt direction while being reduced in diameter. . The end of the inclined wall 30b is located near the solid-liquid interface described above. At the lower end and the upper end of the inclined wall 30b, a first thermocouple 35a as temperature detecting means for detecting the radiant heat of the melt of the crucible 5 instead of the temperature.
And the second thermocouple 35b are attached respectively.
Since the first thermocouple 35a is provided at a position extremely close to the melting surface of the silicon single crystal S and the crucible 5, strictly speaking, it cannot be said that only the radiant heat from the melt is detected. However, since the radiant heat from the melt is much larger than the radiant heat from the others, the radiant heat of the melt can be detected approximately. That is, the radiant heat from the melt can be detected as the temperature of the lower end of the inclined wall 30b.

The same applies to the second thermocouple 35b. That is, also in the second thermocouple 35b, the radiant heat of the melt is detected as the temperature of the upper end of the inclined wall 30b. These thermocouples 35a, 35b
The signal from is input to the control device described later.

The heater 6 and the heat insulating member 11 described above are attached to a support base 24. The support base 24 is manufactured using a material having a very high thermal resistance, and prevents heat from the heater 6 from escaping from the chamber 2.

One end of the wire hoisting machine 10 is attached to the lifting chamber 2b.
A pulling wire 7 that is hung down through the top wall of the housing portion 3b is provided, and a chuck 9 that holds a seed crystal 8 is attached to the lower end of the pulling wire 7. The wire hoisting machine 10 pulls up the silicon single crystal S that gradually grows on the lower end side of the seed crystal 8 according to its growth rate, and at the same time, always rotates the crucible 5 in the opposite direction to the rotation direction.

Also, the housing portion 3b of the lifting chamber 2b
Is provided with a gas inlet 12 for introducing the argon gas into the chamber 2. From the gas inlet 12, the argon gas discharged from the argon gas supply device 45 functioning as an inert gas supply means is supplied. The introduced argon gas flows into the pulling chamber 2b to cool the silicon single crystal S, and then flows into the heating chamber 2a from near the solid-liquid interface and is discharged from the gas outlet 13. ing. The argon gas is circulated in this way in order to rapidly cool the silicon single crystal body S to an optimum temperature and to discharge the SiO 2 gas generated in the chamber 2 with the melting of silicon to the outside of the system. Because of the reason.

At a part of the ceiling portion 3a of the pulling chamber 2b, a state of a solid-liquid interface which is a boundary surface between the melt melted in the crucible 5 and the outer peripheral surface of the silicon single crystal body S pulled from here. A peephole 26 for observing is displayed. A camera (not shown) for observing the diameter and for observing the state of the solid-liquid interface is installed in the peephole 26, and the wire hoisting machine pulls up a silicon single crystal having a desired diameter based on a signal from the camera. The pulling rate of 10 is adjusted.

FIG. 2 is a block diagram showing a schematic configuration of a control system for controlling the melt position adjustment and the argon gas supply amount adjustment in the apparatus for producing a single crystal body according to the present invention.

In the figure, the first thermocouple 35a and the second thermocouple 35b are the funnel-shaped board 3 as shown in FIG.
0 is attached to the lower end and the upper end of the inclined wall 30b. These thermocouples 35a,
35b is for detecting the radiant heat from the melt melted in the crucible 5 instead of the temperature of the board 30.

The argon gas supply device 45 is used in the chamber 2
The supply amount of the argon gas supplied to the inside is adjusted based on a command from the control device 50, and the thermal history of the silicon single crystal body S being pulled up is adjusted. The algo gas supply device 45 has a built-in memory that stores data relating to the argon gas supply amount corresponding to a signal from the control device 50.

The driving device 40 adjusts the height of the crucible 5 according to a command from the control device 50 in order to make the melt surface in the crucible 5 which is lowered with the growth of the silicon single crystal body S constant. It is a thing. The drive unit 40 has a built-in memory that stores data regarding the height of the crucible 5 corresponding to a signal from the control unit 50.

The control device 50 inputs the temperature detected by the first thermocouple 35a and the second thermocouple 35b, and
The first thermocouple 3 outputs a signal for controlling the height of the crucible 5 based on the temperature detected by the thermocouple 35a.
The supply amount of the argon gas is controlled based on the detected temperature difference between the 5a and the second thermocouple 35b. The control device 50 includes a memory that stores data on the relationship between the temperature detected by the first thermocouple 35a and the height of the crucible 5.
It has a built-in memory that stores the relationship between the temperature difference between the temperatures detected by the first thermocouple 35a and the second thermocouple 35b and the supply amount of argon gas.

The apparatus for producing a single crystal body according to the present invention is configured as shown in FIGS. 1 and 2, and the operation of the drive unit 40 is as shown in the flow chart of FIG. The operation of the gas supply device 45 is controlled as shown in the flowchart of FIG.

First, the drive unit 4 for controlling the height of the crucible.
The operation of 0 will be described.

The controller 50 inputs the detected temperature T1 of the first thermocouple 35a (S1), and the detected temperature T1 and the set temperature T0 preset as a reference value in the memory of the controller 50. And are compared (S2). In this comparison, when it is determined that the detected temperature T1 is equal to the set temperature T0, the control device 50 directs the drive device 40 to
It outputs a signal to keep the crucible 5 at the current height. The drive device 40 receiving this signal maintains the crucible 5 at the current height (S4).

On the other hand, in the comparison in the step S2, when the detected temperature T1 is not equal to the set temperature T0, the control device 50 causes the crucible 5 corresponding to the detected temperature T1.
The height of the crucible 5 is selected by looking up the data in the memory, and the data regarding the height of the selected crucible 5 is output as a signal to the driving device 40 (S5).
The drive device 40 which has received this signal reads the current height from the memory and sets the crucible 5 up and down by the difference between the two heights in order to set the crucible 5 to this commanded height (S6).

The above processing is for one scan of the control device 50, and this processing is repeated, for example, every 0.1 msec. By performing such a treatment, the distance between the melt surface of the crucible 5 and the first thermocouple 35a can be maintained at a constant distance with extremely high accuracy. Therefore, as a result, the melt position can be kept constant, which contributes to the improvement of the quality of the manufactured silicon single crystal body. This is effective for quality improvement because it has been proved by experiments that the melt position can be estimated with extremely high accuracy by the temperature detected by the first thermocouple 35a.

In order to effectively bring out the effect of the present invention, it is required that the temperature of the melt is constant, and therefore it is required to use a temperature control device which can perform this temperature control with high precision. It Further, since the relationship between the melt position and the detected temperature is very important, the most reliable data among the data obtained by the repeated experiments is stored in the control device 50. Since the temperature of the melt is much higher than the outside air temperature, there is no need to compensate because a slight change in the outside air temperature does not affect the detected temperature.
Especially when highly accurate control is required, the correction value for correcting the influence of the detected temperature due to the change in the outside air temperature may be stored in the memory and the outside air temperature may be corrected.

Next, the operation of the argon gas supply device for controlling the supply amount of argon gas will be described.

The controller 50 inputs the detected temperature T1 of the first thermocouple 35a and the detected temperature T2 of the second thermocouple 35b (S11, S12), and calculates the temperature difference t between these detected temperatures (S13). . The controller 50 outputs the temperature difference t as a signal to the argon gas supply device 45. Upon receiving this signal, the argon gas supply device 45 looks up and selects the data regarding the supply amount of the argon gas corresponding to this temperature difference t (S14), and discharges the specified supply amount of the argon gas into the chamber 2 ( S15).

The above processing corresponds to one scan of the control device 50, similarly to the control of the crucible position, but this processing is repeated every 0.1 msec, for example. By carrying out such a treatment, it becomes possible to give a desired temperature distribution to the silicon single crystal S, and it becomes possible to improve the quality of the silicon single crystal.

In order to effectively bring out the effect of the present invention, it is necessary to keep a constant temperature distribution at all times. Therefore, the relationship between the supply amount of argon gas and the temperature distribution is accurately determined based on experimental data. Need to figure out. Since this relationship also varies depending on the diameter of the silicon single crystal S to be grown, the relationship between the argon gas supply amount and the temperature distribution is stored in the memory of the argon gas supply device 45 for each diameter.

Incidentally, it is needless to say that the quality of the silicon single crystal S can be improved by adopting either the method of adjusting the crucible position or the method of adjusting the supply amount of the argon gas. However, if both methods are used in combination, the quality of the silicon single crystal body S can be further improved.

[0042]

As described above, according to the first structure of the present invention, the position of the melt surface can be always kept constant,
It becomes possible to obtain a very stable and high quality single crystal.

Further, according to the second structure of the present invention, the single crystal body can be cooled with a desired temperature distribution, so that the generation of crystal defect nuclei can be suppressed and a high quality can be obtained. A single crystal body can be manufactured.

[Brief description of drawings]

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

FIG. 2 is a block diagram showing a control system of an apparatus for producing a single crystal body according to the present invention.

FIG. 3 is a flowchart showing the operation of the apparatus for producing a single crystal body according to the present invention.

FIG. 4 is a flow chart showing the operation of the apparatus for producing a single crystal body according to the present invention.

FIG. 5 is a schematic configuration diagram of a conventional apparatus for producing a single crystal body.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Single crystal body manufacturing apparatus, 2 ... Chamber, 2a
... Heating chamber, 2b ... Lifting chamber, 5 ... Crucible, 6 ... Heater, 7 ... Lifting wire,
8 ... Seed crystal, 10 ... Wire hoist, 12 ... Gas inlet, 30 ... Funnel-shaped board, 30a ... Flat part,
30b ... Inclined wall, 35a ... 1st thermocouple, 35b
... Second thermocouple, 40 ... Drive device, 45 ... Argon gas supply device, 50 ... Control device.

Continuation of the front page (72) Inventor Kiyo Kishima 3434 Shimada, Hikari City, Yamaguchi Prefecture Nittetsu Electronic Co., Ltd.

Claims (2)

[Claims] 1. A crucible (5) supported by a driving device (40) so as to be vertically movable, and a crucible (5) provided along the peripheral surface of a single crystal body (S) pulled up from a melt contained in the crucible. Radiation screen (3
0), temperature detecting means (35a) arranged on the radiant screen to detect radiant heat from the melt, and to maintain constant radiant heat from the melt detected by the temperature detecting means. Liquid level adjusting means for controlling the drive unit to adjust the liquid level of the melt surface of the crucible
An apparatus for producing a single crystal body having (40, 50). 2. A radiant screen along the periphery of a single crystal body (S) pulled up from a melt contained in a crucible (5).
(30) is provided, and the inert gas supply means (45) is used to cool the single crystal body by flowing down the inert gas from the pulling direction side toward the crucible side. In the device, the temperature detection means (35a, 35b) respectively provided to detect radiant heat from the melt at the upper end and the lower end of the radiant screen, and the temperature detected by the both temperature measuring means, respectively. Inert gas supply amount control means (45, 5) for controlling the inert gas supply amount from the inert gas supply means according to the difference in radiant heat
0) and a single crystal body manufacturing apparatus.