JP2000226293A - Apparatus for producing semiconductor single crystal - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress the deposition and accumulation of an amorphous material on the inner surface of an observing window of a purification chamber at the time of purification of a semiconductor single crystal to retard the progress of the decrease of transparency of the window. SOLUTION: An inert gas-blowing port 29 is installed in the region of an observing window 18 in a purification chamber 1 for melting a part of a polycrystal material 6 by heating the material 6 by a high-frequency induction heating coil 7, and moving a floating molten zone 9 in the perpendicular direction to purify a single crystal 8. A heating coil 30 is installed in a gas- introducing tube 29b of the inert gas-blowing port 29. An inert gas introduced through the inert gas-blowing port 29 is heated by the heating coil 30 and blown out from a nozzle part 29a into the region of the observing window 18. The heated inert blown gas blows off an amorphous material floating to the observing window 18 side in the purification chamber 1 to prevent the amorphous material from attaching to and depositing on the inner surface of the window 18.

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 for refining a semiconductor single crystal from a polycrystalline semiconductor.

[0002]

2. Description of the Related Art As a method for purifying a semiconductor single crystal using a polycrystalline semiconductor as a material, an FZ method and a CZ method are generally known. FIG. 8 shows a typical example of a semiconductor single crystal manufacturing apparatus using the FZ method. Have been. In the figure, a seed crystal holder 3 connected to the upper end of a lower shaft 2 is arranged on the bottom wall side in the purification chamber 1, and connected to the lower end of an upper shaft 4 on the upper wall side in the purification chamber 1. A material holder 5 is arranged.

The seed crystal holder 3 holds a rod-shaped seed crystal, and the material holder 5 holds and suspends a semiconductor polycrystalline material 6. The polycrystalline material 6 has a columnar shape, and has a taper 6a tapering downward at the lower end as shown in FIG. After the polycrystalline material 6 is charged, the inside of the purification chamber 1 is made to be an atmosphere of an inert gas such as argon or the like, and the lower end of the polycrystalline material 6 is partially melted by heating the high-frequency induction heating coil 7 and fused to the seed crystal. Seeding is done by doing. Then, the polycrystal material 6 is removed while dislocation-free by seed drawing.
And the single crystal 8 are rotated in opposite directions, and the floating melting zone 9 of the polycrystalline material 6 is moved along the vertical direction, thereby purifying the target semiconductor single crystal.

[0004] As a method of moving the floating melting zone 9, a method of moving the polycrystalline material 6 and the single crystal 8 side with respect to the high frequency induction heating coil 7, and a method of moving the floating melting zone 9 with the high frequency There is a system in which the induction heating coil 7 is moved. FIG. 8A shows the former system, and FIG. 8B shows the latter system. That is, in the apparatus shown in FIG. 8A, the high-frequency induction heating coil 7 is fixed, and the upper shaft 4 and the lower shaft 2 are driven by the rotation of the upper shaft and the feed mechanism 10 and the rotation of the lower shaft and the feed mechanism 11.
Have a mechanism for moving the upper shaft 4 and the lower shaft 2 vertically and vertically relative to the high-frequency induction heating coil 7 while rotating the shafts in directions opposite to each other.

The apparatus shown in FIG. 8 (b) is provided with an upper shaft rotating mechanism 12 that only drives the upper shaft 4 to rotate and a lower shaft rotating mechanism 13 that only drives the lower shaft 2 to rotate. The coil 7 is connected to a connection feeder feed mechanism 15 via a connection feeder 14.
To move the high-frequency induction heating coil 7 vertically and vertically relative to the polycrystalline material 6 and the single crystal 8. However, at least one of the upper shaft rotating mechanism 12 and the lower shaft rotating mechanism 13 is provided with a shaft feeding mechanism for the operation of fusing the polycrystalline material 6 to the rod-shaped seed crystal.

In FIG. 8, reference numeral 16 denotes an inert gas introduction port.
Argon gas for introducing an inert gas atmosphere into the inside is introduced. Reference numeral 17 denotes an inert gas outlet port for discharging argon gas in the purification chamber 1. A new argon gas corresponding to the amount discharged from the inert gas outlet port 17 is supplied from the inert gas introduction port 16 into the purification chamber 1. During the purification of the semiconductor single crystal, the introduction and discharge of the argon gas are repeatedly performed, and the inside of the purification chamber 1 is controlled so as to always have a fresh argon gas atmosphere.

The wall of the purification chamber 1 is provided with an observation window 18 made of transparent quartz or the like which is airtightly partitioned from the outside.
The operator visually observes the floating melting zone from the observation window 18 over a process from the start of the fusion of the polycrystalline material 6 to the seed crystal to the separation of the polycrystalline material 6 and the single crystal after the purification of the single crystal. By observing the state of No. 9, the semiconductor single crystal was purified by manipulating the purification conditions.

[0008]

However, when the polycrystalline material 6 is melted by heating the high-frequency induction heating coil 7, a part of the polycrystalline material 6 floats in the refining chamber 1 as amorphous, Fine powder adheres to the wall surface, the surface of the high-frequency induction heating coil 7, the inner surface of the observation window 18, and the like. In particular, the attached amount increases in the process of cooling (natural air cooling) the inside of the purification chamber 1 in order to take out the purified single crystal from the purification chamber 1 after the purification of the semiconductor single crystal.

If the fine powder, which is an amorphous precipitate, adheres to and accumulates on the inner surface of the observation window 18, it is impossible to accurately determine the purification state of the semiconductor single crystal through the observation window 18. Thus, there is a problem that it is difficult to form a single crystal. Therefore, in general, after the purification of the semiconductor single crystal and before the next purification of the single crystal (loading of the polycrystalline material 6), the portion where the amorphous fine powder is adhered is wiped off with a clean gauze, or the gas is purified using a gas. Attempts have been made to remove adhered fine powder by blowing inside.

[0010] However, it is difficult to completely remove the fine powder even if such an operation of removing the attached fine powder is performed.
Amorphous fine powder adheres and accumulates on the inner surface of No. 8. As a result, the transparency of the observation window 18 decreases, and the state of the floating melting zone 9 at the time of refining the single crystal cannot be correctly recognized. Therefore, the observation window 18 is removed from the purification chamber 1 and polished and washed with abrasive grains or aqueous ammonia. Therefore, it is necessary to remove the amorphous fine powder adhered and accumulated.

The work of removing the amorphous fine powder by removing the observation window 18 has to be performed relatively frequently, and when the maintenance work of removing the amorphous fine powder is performed, the manufacturing apparatus is stopped. This has the disadvantage that the production efficiency of semiconductor single crystal refining decreases.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned conventional problems, and an object of the present invention is to extend the maintenance cycle for removing amorphous fine powder to increase the production efficiency of semiconductor single crystal purification. An object of the present invention is to provide a single crystal manufacturing apparatus.

[0013]

Means for Solving the Problems The present invention is a means for solving the problems by taking the following means to achieve the above object. That is, in the first invention, an observation window for observing the interior of the semiconductor single crystal refining chamber is hermetically mounted on the wall of the refining chamber, and an inert gas is supplied to the region of the observation window in the refining chamber. This is a means for solving the problem with a configuration in which an inert gas blowing means for blowing is provided.

According to a second aspect of the present invention, there is provided the apparatus according to the first aspect, further comprising an inert gas heating means for heating the inert gas for jetting from the inert gas jetting means. The problem is solved by a configuration in which the inert gas heated by the inert gas heating means is jetted from the inert gas jetting means to the region of the observation window.

Further, the third invention is characterized in that the first or the second
In order to solve the problem, the exhaust port for exhausting the inert gas ejected from the inert gas ejecting means to the outside is arranged in an area where the observation window is arranged in the purification chamber. Means.

According to a fourth aspect of the present invention, in the apparatus according to the third aspect of the present invention, the inert gas ejection part of the inert gas ejection means and the exhaust inlet of the exhaust port are provided on a window surface with the observation window interposed therebetween. The inert gas ejected from the inert gas ejecting portion is arranged opposite to each end of the observation window, flows along the inner surface of the observation window, and is received by the exhaust gas inlet, thereby solving the problem.

Further, the fifth invention is directed to the third or fourth embodiment.
The present invention provides a means for solving the problem by providing an exhaust pump for performing forced exhaust in an exhaust passage of an exhaust port.

According to a sixth aspect of the present invention, in accordance with the fifth aspect of the present invention, there is provided a filter according to the fifth aspect, wherein a filter is provided in the exhaust passage of the exhaust port for capturing amorphous generated during the purification of the semiconductor single crystal. Is a means to solve the problem.

Further, the seventh invention is directed to the second to sixth embodiments.
In the apparatus having the configuration according to any one of the above, after cooling of the refining chamber is started after completion of the purification of the semiconductor single crystal, a direct or indirect method is set in advance in which amorphous floating in the refining chamber is almost completely precipitated. This is a means to solve the problem by providing a configuration in which an inert gas extension jetting means is provided which continuously blows the inert gas heated from the inert gas jetting means to the observation window area in the purification chamber until the temperature reaches the precipitation completion cooling temperature. .

Further, an eighth aspect of the present invention relates to the first to seventh aspects.
Wherein the observation window covers the window opening provided on the wall surface of the purification chamber with a window body, and the window body is airtightly attached to the wall surface of the purification chamber via packing. A cooling water flow passage for cooling the packing is formed in a region of the observation window near the packing arrangement as means for solving the problem.

Further, a ninth invention is directed to the first to eighth embodiments.
The semiconductor single crystal is refined by heating the high frequency induction heating coil to form a floating melting zone at a joint boundary between the single crystal and the polycrystalline material. The high frequency induction heating coil is provided with a structure in which a gas doping tube for doping a dopant gas in the floating melting zone is attached to the high frequency induction heating coil.

In the present invention, during the purification of the semiconductor single crystal, the inert gas is blown from the inert gas blowing means to the region of the observation window, so that the amorphous floating in the purification chamber will reach the inner surface of the observation window. Even so, the amorphous is blown off and the deposition on the observation window is suppressed. In particular, even if the amorphous gas reaches the inner surface of the observation window, the inert gas heated by the inert gas heating means is blown from the inert gas ejection means to the area of the observation window, so that the heated inert gas is touched. This suppresses precipitation and minimizes the attachment of the amorphous fine powder to the inner surface of the observation window.

In the cooling period after refining the semiconductor single crystal, after the cooling is started, the amorphous deposition proceeds in the refining chamber as the cooling proceeds, but the temperature at which the amorphous deposition is completed (the refining chamber) The heated inert gas is blown to the region of the observation window until the temperature reaches the temperature of the observation window, whereby amorphous deposition on the inner surface of the observation window is effectively suppressed.

As described above, in the present invention, in the purification process of the semiconductor single crystal and the cooling process after the purification, the adhesion of the fine powder to the observation window due to the precipitation of amorphous is suppressed, so that the transparency of the observation window is reduced. As a result, the maintenance cycle from removal of the observation window to polishing and cleaning can be extended, and the production efficiency of semiconductor single crystal refining can be greatly increased.

[0025]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following description of each embodiment, the same parts as those of the conventional example described with reference to FIG. 8 are denoted by the same reference numerals, and the description thereof will be omitted or simplified. FIG. 1 shows a first embodiment of a semiconductor single crystal manufacturing apparatus according to the present invention. The apparatus of the first embodiment is an apparatus for refining a semiconductor single crystal by the FZ method as shown in FIG.
The single crystal refining mechanism is a mechanism shown in FIG. 8A (the high-frequency induction heating coil 7 is fixed, and the lower shaft 2 and the upper shaft 4 are fed and moved with rotation. And a mechanism for vertically moving the floating melting zone 9 by relatively moving the polycrystalline material 6 and the single crystal 8 up and down, but of course, the mechanism shown in FIG. 1 may be included.

In the apparatus according to the present embodiment, as shown in FIG.
Are integrally attached, and the tip of the gas dope tube 19 faces the floating melting zone 9. The gas doping tube 19 is for doping a dopant gas such as a phosphine gas or a diborane gas into the floating melting zone 9. The n-type single crystal is purified by doping the phosphine gas, and the p-type single crystal is doped by diborane gas. Is to be purified.

FIG. 1B shows the details of the observation window 18. The observation window 18 hermetically closes the window opening 20 provided on the wall surface 1 a of the purification chamber 1. And a window 21 attached to the wall surface 1a in the form. The window body 21 is formed by holding a peripheral edge of a window plate 22 made of transparent quartz or the like with a window holder 23. In the illustrated example, the window holder 23 includes a holder portion 23a and a holder portion 23b, and the window plate 22 is hermetically sealed by the holder portions 23a and 23b via a packing 24 made of, for example, a fluororesin-based elastomer (O-ring). In this held state, the window holder 23 is in contact with the wall surface 1a of the purification chamber 1 via a similar packing 25, and is airtightly attached to the wall surface 1a using the mounting screw 26.

A water jacket 27 is provided on the holder portion 23b, which is a region near the arrangement of the packings 24 and 25.
Are mounted in a buried state, and the inside of the water jacket 27 forms a cooling water flow passage 28, and the packings 24 and 25 are cooled by water passing through the cooling water flow passage 28.

A feature of this embodiment is that an inert gas jetting means for blowing an inert gas into the region of the observation window 18 is provided in the purification chamber 1.
In the example of FIG. 1, the inert gas blowing means is constituted by one or more inert gas blowing ports 29, and the gas introduction pipe 29b of the inert gas blowing port 29 passes through the wall surface 1a of the purification chamber 1 in an airtight manner. Then, it is led out of the purification chamber 1 and connected to an inert gas supply source (not shown). The tip side of the inert gas blowing port 29 is a nozzle portion 29a.
The nozzle of the nozzle portion 29a faces the inner surface of the observation window 18 (the inner surface of the window plate 22), and the inert gas supplied from the inert gas supply source to the inert gas blowing port 29 is supplied. It is configured to blow out toward the observation window 18.

As the gas species of the inert gas, nitrogen gas,
Although an appropriate gas such as argon gas can be used, in the present embodiment, the same kind of argon gas as the inert gas introduced into the purification chamber 1 from the inert gas introduction port 16 is used.

In the present embodiment, a heating coil as a heating means is connected to the gas introduction pipe 29b of the inert gas blowing port 29 in order to eject heated inert gas from the nozzle portion 29a toward the observation window 18. 30 are provided. The heating coil 30 is driven to be heated by a drive unit 31, and the heating temperature is controlled by an inert gas heating control unit 32. That is, the temperature sensor 33 is attached to the gas introduction pipe 29 b at a position downstream of the heating coil 30, and the inert gas heating control unit 32 detects the data of the preset temperature and the temperature sensor 33. The temperature data is compared, and the drive output of the drive unit 31 (drive power to the heating coil 30) is controlled in a direction in which the detected temperature matches the set temperature.

The set temperature of the heating of the inert gas is set at a temperature at which the precipitation of the floating amorphous material during the purification of the semiconductor single crystal can be suppressed. In theory, the melting point temperature of the polycrystalline material 6 (normally 1400 ° C) is ideal, but in practice, there are various restrictions to such a high temperature. In this embodiment, therefore, the ambient temperature in the refining chamber 1 during refining of the semiconductor single crystal is substantially equal to the ambient temperature. The temperature is set to be equal (or equivalent or more) (for example, 200 ° C.).

The present embodiment is provided with a system for automatically observing the state of the floating melting zone 9 during the purification of a semiconductor single crystal and automatically controlling the purification conditions. FIG. 2 is a block diagram of the system configuration. It is shown. This system includes a CCD camera 34, an image processing device 35, a computer 36, an actuator 37, and a voltage supply unit 38.
And is configured. The CCD camera 34 is an observation window 18 that is used for both viewing and observation or a separate observation window 18 for viewing.
The state near the floating melting zone 9 is photographed through the observation window 18, and the image is sent to the image processing device 35.

The image processing unit 35 processes the image sent from the CCD camera 34, obtains desired data such as the diameter of the single crystal 8 and the diameter of the polycrystalline material 6 in the floating melting zone 9 and obtains the data. It is supplied to the computer 36. The computer 36 obtains the optimum conditions of the semiconductor single crystal refining from time to time based on the data sent from the image processing device 35 according to a given process program, and supplies corresponding control data to the actuator 37 and the voltage supply unit 38. I do.

The actuator 37 (in the example of FIG. 1, the upper shaft rotation and feed mechanism 10 and the lower shaft rotation and feed mechanism 1
1) drives the rotation and the feed movement of the lower shaft 2 and the upper shaft 4 so as to obtain the optimum refining conditions based on the control data from the computer 36. Similarly, the voltage supply unit 38 supplies and drives a voltage (high-frequency oscillation voltage) to the high-frequency induction heating coil 7 based on the control data from the computer 36 so that the optimum refining conditions are obtained.

The present embodiment is configured as described above, and its operation will be described below. In the refining chamber 1, the polycrystalline material 6 and the single crystal 8 are rotated and fed in an inert gas atmosphere of argon introduced from an inert gas introduction port 16 as in the conventional example, while the high frequency induction A high-frequency oscillation voltage is applied to the heating coil 7, and the semiconductor single crystal is refined by controlling the movement of the floating melting zone 9.
In the purification process of this single crystal, the state of the floating melting zone 9 is visually observed through the observation window 18, and the state near the floating melting zone 9 is photographed by the CCD camera 34 through the observation window 18, and the image processing device The image processing of the photographed image by the computer 35, the calculation of the optimum refining condition control data by the computer 36, and the control driving of the actuator 37 and the voltage supply unit 38 based on the control data automatically purify the single crystal according to the process control program. Go.

In the process of purifying the single crystal, the heating coil 3 is controlled by the heating control of the inert gas heating controller 32.
Inert gas heated to the set temperature at 0 (argon gas)
Is introduced through the inert gas blowing port 29 and is continuously blown from the nozzle portion 29a to the region of the observation window 18, and the amorphous floating in the purification chamber 1 reaches the inner surface of the observation window 18 during the single crystal purification. Precipitation in the form of fine powder is prevented. In the process of purifying the single crystal, the cooling water flow passage 2 of the water jacket 27 is used.
8, cooling water is passed through the packings 24, 2 of the observation window 18.
5 is performed.

According to this embodiment, since the cooling water is always passed through the cooling water flow passage 28 during the single crystal refining process, the packings 24 and 25 are effectively cooled. Thus, thermal deterioration of the packings 24 and 25 can be prevented, and the packing can be stably used for a long period of time.

Further, since the gas dope tube 19 is formed as a unit with the high-frequency induction heating coil 7, a mechanism for exclusively holding the gas dope tube 19 separately from the high-frequency induction heating coil 7 is not required, and the handling is simplified. Simplification of the device configuration can be achieved.

Further, the inert gas blown from the nozzle portion 29a of the inert gas blowing port 29 to the observation window 18 is supplied from the inert gas introduction port 16 to the inside of the purification chamber 1 in order to make the inside of the purification chamber 1 an inert gas atmosphere. Since the same gas species as that of the inert gas (argon gas in the above example) introduced into the nozzle is used, the conditions for refining the single crystal are not affected by the inert gas blown out from the nozzle portion 29a, and Reliability can be ensured.

Further, during the process of refining the single crystal, the inert gas heated to the set temperature is always blown from the nozzle portion 29a of the inert gas blowing port 29 to the region of the observation window 18 in the purification chamber 1. Even if the amorphous material floating in the purification chamber 1 approaches the observation window 18 and is blown off by the inert gas, it cannot be approached.
Since it is heated to the ambient temperature (for example, 200 ° C.) in the inside, the amorphous is prevented from becoming a fine powder and precipitated, so that it adheres to the inner surface of the observation window 18 (the inner surface of the window plate 22). It is possible to reduce the amount of fine powder to be formed.

Therefore, after the purification of the semiconductor single crystal is completed, a minute amount of fine powder adhering to the inner surface of the observation window 18 can be removed by wiping with a clean gauze or by gas blowing. Therefore, even if the purification of the semiconductor single crystal is repeatedly performed,
The amount of the amorphous fine powder adhering and accumulating on the inner surface of the observation window 18 is reduced, and as a result, the observation window 18 is removed,
The maintenance cycle of polishing and cleaning is extended, and accordingly, the production efficiency of semiconductor single crystal refining can be improved.

FIG. 5 shows the effect of the embodiment of the present invention verified by experiments in comparison with the conventional example.
Shows a conventional example, and (b) shows an example of the present embodiment. In this comparative experiment, two observation windows 18 were attached to the wall surface of the purification chamber 1 symmetrical with respect to the high-frequency induction heating coil 7 in the purification chamber 1, and one observation window 18 was attached to one of the observation windows 18. An active gas blowing port 29 is provided to provide the configuration of the above embodiment, and the other observation window 18 is provided with a conventional configuration in which the inert gas blowing port 29 is not provided, and a CCD camera 34 is attached to each observation window 18. Figure 2
(1) Automatic operation of single crystal refining by using the measurement control system of the CCD camera 34 attached to the observation window 18 side of the conventional example at the 200th operation of the apparatus. And 2
The 01 th time is C attached to the observation window 18 side of this embodiment.
The automatic operation of the single crystal purification is performed by the measurement control system of the CD camera 34, and the polycrystal material 6 at the time of the single crystal purification is
, The diameter of the single crystal 8, and the data of the application of the oscillation voltage were measured and compared. Since the respective observation windows 18 are arranged symmetrically with respect to the high-frequency induction heating coil 7, the amount of amorphous floating around both observation windows 18 may be considered to be equal.

The horizontal axis of the graph data shown in FIG. 5 indicates the length of the single crystal, the left vertical axis indicates the oscillation voltage, and the right vertical axis indicates the diameters of the polycrystalline material 6 and the single crystal 8, respectively. The diameter of the polycrystalline material 6 and the diameter of the single crystal 8 were obtained by image processing using an image processing device 35. These data indicate that the portion of the taper 6a of the polycrystalline material 6 (see FIG. 9) is on the tip side. 2 shows the process of melting from the end to the taper end side.

In the data of the conventional example shown in FIG. 5A, the diameter of the taper 6a of the polycrystalline material 6 is not accurately measured.
The measured value fluctuates up and down randomly and increases with an increase in the diameter of the taper 6a, indicating that the inner surface of the observation window 18 is heavily contaminated with the amorphous fine powder. Since the diameter of the taper 6a is originally formed so as to monotonically increase, measurement data should be obtained as monotonically increasing data. However, since the inner surface of the observation window 18 is contaminated by accumulation of the amorphous fine powder, the transparency is low. It is obtained as data of a random fluctuation with a decrease and variation. Due to the random fluctuation, the oscillation voltage (the oscillation voltage is largely controlled to increase the melting amount as the diameter of the polycrystalline material 6 increases. Conversely, as the diameter of the polycrystalline material 6 becomes smaller, the amount of melting is controlled to be small to reduce the amount of melting). It can be seen that the diameter of the undulation also increased.

On the other hand, in the case of this embodiment shown in FIG. 5B, the inert gas is blown into the observation window 18 from the nozzle portion 29a of the inert gas blow port 29 every time the single crystal is refined. As a result, the inner surface of the observation window 18 is not contaminated yet, and clean monotonically increasing graph data in which the diameter of the taper 6a of the polycrystalline material 6 increases linearly from the taper tip to the taper end is obtained. Since accurate data of the measured diameter of the polycrystalline material 6 without such random fluctuations is obtained, the oscillation voltage also increases with the increase of the taper diameter of the polycrystalline material 6 with normal data without random fluctuations. It can be seen that fine normal data is obtained in which the diameter of the single crystal to be purified also monotonically increases linearly as the taper diameter of the polycrystalline material 6 increases.

The fact that random fluctuation data of the polycrystalline material 6 as shown in FIG. 5A is obtained means that amorphous fine powder accumulates on the inner surface of the observation window 18 and the transparency of the window is greatly reduced. Means that the operator visually observes the state of the floating melting zone 9 through the observation window 18 and operates the single crystal refining conditions, and also captures the image by the CCD camera 34 through the observation window 18. Even when the condition image of the floating melting zone 9 is processed and the single crystal refining conditions are automatically controlled, the diameter of the polycrystalline material 6 cannot be accurately grasped, and the taper 6a of the polycrystalline material 6 is melted to melt the semiconductor single crystal. During the process of purifying the tapered portion of the crystal, the high-frequency induction heating coil 7 is used.
It is not possible to apply an appropriate oscillation voltage to
Semiconductor single crystal purification becomes impossible.

In such a case, the observation window 18 must be removed, and the observation window 18 must be polished and cleaned to perform maintenance for removing the accumulated amorphous fine powder. In the case of the present embodiment, the measurement data as shown in FIG.
The maintenance cycle can be extended more than three times by blowing the inert gas heated from the nozzle portion 29a to the region of the observation window 18 during the purification of the semiconductor single crystal as in the present embodiment as in the present embodiment. It was confirmed that the production efficiency could be improved.

Next, a second embodiment of the present invention will be described. In the first embodiment, the inert gas is blown from the nozzle portion 29a to the region of the observation window 18 only during the purification of the semiconductor single crystal. However, the second embodiment is, of course, performed during the purification of the single crystal. That is, even after the purification of the semiconductor single crystal, there is provided an inert gas extension jetting means for extending the inert gas heated from the nozzle portion 29a to the region of the observation window 18 while extending over the natural cooling period in the purification chamber 1. The other features are the same as those of the first embodiment.

The inert gas extension jetting means is, for example,
As shown in FIG. 1, the cooling temperature detecting means in the refining chamber 1 is provided with a set temperature memory 39 and a comparison judging unit 40 added to the inert gas heating control unit 32. The cooling temperature detecting means is constituted by an indoor temperature detecting sensor 41 installed at an appropriate position in the purification chamber 1,
The indoor temperature detection sensor 41 detects the temperature inside the purification chamber 1,
The information on the detected room temperature is added to the comparison determination unit 40. In the set temperature memory 39, after the single crystal purification, data of the temperature at which the amorphous in the purification chamber 1 becomes a fine powder due to the progress of natural cooling and almost or completely completes the precipitation is stored and set as the precipitation completion cooling temperature. I have. Since the precipitation completion cooling temperature varies depending on the specifications of the refining chamber 1, data suitable for each apparatus of each specification is obtained by an experiment or the like, and is stored and set in the set temperature memory 39.

The comparison judging section 40 compares the temperature detected by the indoor temperature detecting sensor 41 with the precipitation completion cooling temperature set in the set temperature memory 39, and when the detected temperature falls below the precipitation completion cooling temperature. , A stop signal is applied to the inert gas heating controller 32. Upon receiving the stop signal, the inert gas heating control unit 32 stops the driving of the heating coil 30 by the driving unit 31 and closes a valve (not shown) of the gas introduction pipe 29b to stop the supply of the inert gas. I do.

According to the second embodiment, over the cooling period after the purification of the single crystal in which the amorphous material floating in the purification chamber 1 is most likely to precipitate, the nozzle portion is maintained until the amorphous material is completely precipitated in the purification chamber 1. Since the heated inert gas is continuously blown out from the region 29a into the region of the observation window 18, it is possible to more effectively suppress the deposition of the amorphous substance on the inner surface of the observation window 18, which is more effective than the first embodiment. Further, the contamination of the observation window 18 can be prevented, the maintenance cycle of the observation window 18 can be further extended, and the production efficiency of semiconductor single crystal purification can be further improved.

In the second embodiment, the value (data) of the precipitation completion cooling temperature is set as direct temperature data in the set temperature memory 39, and the room temperature detection sensor 4
1, the temperature inside the refining chamber 1 is directly detected. However, unlike the above, the cooling temperature at the completion of the deposition is set in the set temperature memory 39 with the value of the indirect temperature data, and the same inert gas extension jetting means is used. Can also be configured. in this case,
For example, a clock means such as a timer is provided in place of the room temperature detection sensor 41, and the set temperature memory 39 almost or completely becomes amorphous in the purification chamber 1 with the progress of cooling from the start of cooling after semiconductor single crystal purification. The time until the completion of the precipitation is determined by an experiment or the like, and is stored and set as indirect precipitation completion cooling temperature data. Then, the comparison / determination unit 40 captures information on the elapsed time from the start of cooling from the clock means, and outputs a stop signal when the elapsed time exceeds the time given to the set temperature memory 39.
, It is possible to perform the extended ejection operation of the inert gas in the same manner as in the case of the above embodiment in which the precipitation completion cooling temperature is directly set.

FIG. 4 shows a third embodiment of the present invention. The feature of the third embodiment that is different from the first and second embodiments is that an interval between the nozzle portion 29a of the inert gas spraying port 29 and the nozzle 29a in the region of the observation window 18 in the purification chamber 1 is different. The other configuration is the same as that of each of the first and second embodiments. The exhaust port 42 discharges the inert gas blown from the nozzle portion 29a of the inert gas blowing port 29 to the outside.

In this embodiment, the pressure in the purification chamber 1 is
The semiconductor single crystal is purified at a predetermined pressure in the range of 300 mmAq to +300 mmAq, and when the single crystal is purified by setting the pressure in the purification chamber 1 to a pressure higher than the atmospheric pressure, the purification in the purification chamber 1 is performed. The inert gas can be discharged from the refining chamber 1 to the outside by using the pressure difference between the pressure and the atmospheric pressure, and the means for forced exhaust is not necessarily provided in the exhaust passage 42a of the exhaust port 42. In the device shown in a), an exhaust pump 43 is provided in the exhaust passage 42a for forcibly discharging the inert gas ejected from the nozzle portion 29a.
A filter 44 is provided in the exhaust passage 42a on the upstream side of the exhaust pump 43 for trapping amorphous in the purification chamber 1 in exhaust gas.

In the third embodiment, since the exhaust port 42 of the forced exhaust type is provided, the amorphous gas blown off by the inert gas blown out from the nozzle portion 29a can be sucked and discharged to the outside. Can be more effectively prevented from adhering, and the amorphous glass blown off by the inert gas can be used as the observation window 1.
8 can be suppressed from adhering to the wall surface 1a or the like of the purification chamber 1 other than 8, and the effect that the amount of the amorphous fine powder deposited on the wall surface 1a or the like can be reduced.

Further, by providing the filter 44,
Since the amorphous can be captured, clogging of the exhaust passage 42a can be prevented. Further, the filter 44 is
3, it is possible to prevent the problem that the amorphous fine powder adheres and accumulates in the exhaust pump 43.

FIG. 6 shows a main configuration of a fourth embodiment of the present invention. In the fourth embodiment, a blowing guide 45 is provided on the tip side of the inert gas blowing port 29 to form a blowing section, and the exhaust intake port of the exhaust port 42 is formed by a guide 46. The other configuration is the same as that of the third embodiment.

The blowing guide 45 and the receiving guide 46
The width of the observation window 18 in the direction perpendicular to the plane of FIG. 6 is substantially equal to the width of the observation window 18 in the same direction.
Outlet is squeezed to form a blowing nozzle,
The inert gas blown out from the outlet flows along the entire inner surface of the observation window 18 in parallel with the window surface, and an inert gas flow blocking layer (gas flow blocking curtain) is formed in front of the window surface. It has a configuration. On the other hand, the receiving guide 46 has a receiving port formed to be expanded and formed so as to entirely receive a laminar flow of the inert gas blown out from the blowing guide 45 and flow out to the exhaust port 42.

In the fourth embodiment, the flow of the inert gas from the blowing guide 45 toward the receiving guide 46 forms an inert gas blocking layer covering the entire inner surface of the window. The amorphous gas can be almost completely prevented from floating and adhering to the inner surface of the window, and since the inert gas is heated by the heating coil 30, even if the amorphous material floats on the inner surface of the window, the amorphous gas may not adhere to the inner surface of the window. Precipitation is suppressed, and contamination of the window inner surface with the amorphous fine powder can be extremely effectively suppressed.

Further, since the amorphous blown off by the inert gas blown out from the blowout guide 45 is received by the receiving guide 46 and discharged by riding on the flow of the inert gas, the amorphous blown out by the inert gas is removed. Diffusion into the purification chamber 1 is prevented, and adhesion to the wall 1a of the purification chamber 1 other than the observation window 18 is also effectively suppressed. The effect of reducing the accumulated contamination amount of the amorphous fine powder can be obtained.

The present invention can adopt various embodiments without being limited to the above embodiments. For example, in each embodiment described above, the window holder 23 is
3b, the window plate 22 is held between the holder portions 23a and 23b, but as shown in FIG.
The water jacket 27 may be provided on the window plate receiving portion 47 of the purification chamber 1 by pressing and fixing the water jacket 2 to the window plate receiving portion 47 of the window opening 20 of the purification chamber 1.

Further, the refining mechanism of the semiconductor single crystal constructed in the refining chamber 1 is not necessarily limited to the FZ type mechanism as shown in FIGS. 8A and 8B. The present invention is often applied to various types of semiconductor single crystal manufacturing apparatuses which need to suppress the contamination when the floating components cause contamination of the inner surface of the observation window 18 during purification of the single crystal. .

Further, in the configuration of each of the above embodiments, a means for automatically checking the maintenance timing of the observation window 18 may be added to improve the function. This case can be realized by connecting a self-check mechanism 48 to the computer 36 as shown by a broken line in FIG.
For example, the value of the determination reference width of the random fluctuation range in the diameter measurement graph of the polycrystalline material 6 in FIG.
The computer 36 is provided with a calculation unit for calculating the random fluctuation width of the diameter of the polycrystalline material 6 based on the image processing data of the image processing device 35, and the self-checking mechanism 48 determines the random fluctuation width obtained by the computer 36. Compared with the reference width, when the calculated value of the random fluctuation width exceeds the value of the determination reference width, it is determined that the contamination of the observation window 18 has reached the limit, and the arrival of maintenance is determined by an appropriate buzzer, lamp display, or the like. The operator may be notified according to the notification mode.

Further, in each of the above embodiments, the observation window 1
The heated inert gas was blown out from the nozzle portion 29a in order to suppress the deposition of the amorphous material on the inner surface of the window 8; however, a transparent heating sheet was formed on the inner surface of the observation window 18 instead of the inert gas blowing means. May be attached, and furthermore, a transparent heat generating sheet may be attached to the inner surface of the observation window 18, and the inert gas ejection means of each of the above embodiments may be provided.
The contamination of the amorphous fine powder on the inner surface of the observation window may be suppressed by using the heat generating sheet and the inert gas ejecting means in combination.

Further, in each of the above embodiments, the inert gas blown from the nozzle portion 29a is heated by the heating coil 30. However, the inert gas heating means is omitted, and the inert gas which is not heated is removed from the nozzle portion 29a. It is also possible to blow out from 29a. Even when an inert gas that is not heated is ejected from the nozzle portion 29a, the amorphous gas floating toward the observation window 18 is blown off to remove the inert gas.
As a result, it is possible to obtain an effect of suppressing contamination of the inner surface of the observation window 18 as compared with a conventional example having no configuration for blowing out an inert gas. However, by ejecting the heated inert gas from the nozzle portion 29a as in each of the above embodiments, the effect of suppressing the deposition of amorphous is sufficiently achieved, and the effect of further preventing contamination of the inner surface of the observation window 18 is obtained. Therefore, it is preferable that the heated inert gas be ejected from the nozzle 29a.

Further, in the first embodiment, the inert gas is ejected from the nozzle portion 29a to the region of the observation window 18 only during the purification of the semiconductor single crystal. If the inert gas is continuously ejected (blown) until the operation switch is manually turned off after the start of the purification of the single crystal, the desired period from the purification of the semiconductor single crystal to the cooling period after the purification can be achieved. , The inert gas ejection time can be freely selected over the period
It is convenient for use.

Further, in the second embodiment, during the cooling period after refining the semiconductor single crystal, the nozzle unit is automatically automatically adjusted until the room temperature in the refining chamber 1 directly or indirectly reaches the set precipitation completion cooling temperature. The heated inert gas is blown from 29a into the region of the observation window 18, but this heated inert gas is blown out until the purified semiconductor single crystal is taken out by opening the lid of the purification chamber 1. May be
Alternatively, the inert gas may be blown out until the conditions set by the operator such as the cooling temperature in the purification chamber 1 set by the operator (variable setting) or the time from the start of cooling are satisfied. It is.

Further, in the case where the heated inert gas is blown from during the purification of the semiconductor single crystal to the cooling period after the purification,
The temperature of the inert gas blown during the semiconductor single crystal refining and the temperature of the inert gas blown over the cooling period after the refining may be different, for example, the temperature of the inert gas blown during the semiconductor single crystal refining may be higher than the temperature of the inert gas blown during the semiconductor single crystal refining. The temperature of the inert gas which is blown out during the subsequent cooling period may be increased to suppress as much as possible the amorphous deposition during the cooling period, which is an environment in which amorphous is likely to precipitate.

[0070]

According to the present invention, since the inert gas blowing means for blowing the inert gas is provided in the region of the observation window in the semiconductor single crystal refining chamber, the amorphous floating in the refining chamber at the time of refining the semiconductor single crystal. When floating toward the observation window, the amorphous can be blown away so as not to approach the window surface. As a result, the amount of amorphous floating around the observation window can be reduced, which can suppress the phenomenon that amorphous deposits and accumulates on the inner surface of the observation window and lowers the transparency of the window. Can be extended to extend the maintenance cycle of polishing and cleaning the inner surface of the window, thereby increasing the production efficiency of semiconductor single crystal refining.

In particular, since the heated inert gas is ejected from the inert gas ejecting means, even if the amorphous material in the purification chamber floats on the inner surface of the observation window, the floating amorphous material is heated to the heated temperature. Since the deposition is suppressed by touching a high inert gas, the accumulation of amorphous fine powder on the inner surface of the window can be more effectively suppressed, and the maintenance cycle can be further extended to improve the production efficiency of semiconductor single crystal purification. It is possible to further improve.

The inert gas heated during the cooling period (cooling period in the refining chamber) after the refining as well as during the refining of the semiconductor single crystal is supplied to the region of the observation window in the refining chamber through the inert gas jetting means. By spraying on
Even during the cooling period during which the floating amorphous material in the purification chamber is most likely to precipitate, the amorphous material can be prevented from being deposited on the observation window. Can be further extended to significantly improve the production efficiency of semiconductor single crystal refining.

Furthermore, by providing an exhaust port in the region of the observation window in the purification chamber, the amorphous gas blown out by the inert gas jetting means can be taken in together with the jetted inert gas and discharged to the outside. And the effect of preventing the blown-off amorphous particles from adhering to the walls of the purification chamber other than the observation window can be obtained.In particular, an exhaust pump is provided in the exhaust passage of the exhaust port. By forcibly discharging the amorphous gas blown out by the inert gas jetting means from the exhaust port, the effect can be further enhanced.

Further, the inert gas ejecting portion of the inert gas ejecting means and the exhaust inlet of the exhaust port are arranged to face each other on both ends of the inner surface of the observation window, and the inert gas ejected from the inert gas ejecting portion is supplied to the window. By flowing along the surface and receiving and exhausting at the exhaust inlet, an inert gas flow blocking layer is formed in front of the inner surface of the window of the observation window, so that the amorphous inside the purification chamber The floating can be almost completely blocked by the inert gas flow blocking layer, and furthermore, the amorphous floating on the window side can be sucked into the inert gas flow and forcedly discharged. Therefore, the effect of preventing the contamination of the inner surface of the window due to the accumulation of the amorphous fine powder is extremely large, the maintenance cycle of the observation window can be further extended, and the production efficiency of semiconductor single crystal refining can be remarkably increased. It is what becomes.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of an apparatus including a configuration of each of first and second embodiments of the present invention.

FIG. 2 is a diagram of an embodiment of a system configuration for automatically controlling semiconductor single crystal purification by processing a captured image near a floating melting zone during single crystal purification.

FIG. 3 is an explanatory view of this embodiment in which a gas dope tube 19 is integrally mounted on the high-frequency induction heating coil 7 and the high-frequency induction heating coil 7 and the gas dope tube 19 are configured as a unit.

FIG. 4 is a configuration explanatory view of a third embodiment of the present invention.

FIG. 5 is a graph data diagram showing the degree of contamination of the observation window due to a difference in configuration between the case of the present embodiment and the case of the conventional example in a comparative state.

FIG. 6 is an explanatory diagram showing a main configuration of a fourth embodiment of the present invention.

FIG. 7 is an explanatory diagram of another configuration example of the observation window 18;

FIG. 8 is an explanatory view of a conventional example of a semiconductor single crystal manufacturing apparatus.

FIG. 9 is a diagram illustrating the form of a polycrystalline material 6;

[Explanation of symbols]

 Reference Signs List 1 Refining room 6 Polycrystalline material 8 Single crystal 9 Floating melting zone 18 Observation window 29 Inert gas blowing port 30 Heating coil 42 Exhaust port

Claims (9)

[Claims] An observation window for observing the interior of a room for purifying a semiconductor single crystal is hermetically attached to the wall of the purification chamber.
An apparatus for producing a semiconductor single crystal, characterized in that an inert gas blowing means for blowing an inert gas into a region of the observation window is provided in the purification chamber. 2. An inert gas heating means for heating an inert gas for jetting from the inert gas jetting means is provided.
2. The semiconductor single crystal manufacturing apparatus according to claim 1, wherein the inert gas heated by the inert gas heating means is jetted from the inert gas jetting means to a region of the observation window. 3. An exhaust port for exhausting the inert gas ejected from the inert gas ejecting means to the outside in an area where the observation window is arranged in the purification chamber. 3. The semiconductor single crystal manufacturing apparatus according to 2. 4. An inert gas ejecting portion of an inert gas ejecting means and an exhaust inlet of an exhaust port are disposed opposite to each other on both ends of a window surface with an observation window interposed therebetween, and inert gas ejected from the inert gas ejecting portion is provided. 4. The semiconductor single crystal manufacturing apparatus according to claim 3, wherein the gas flows along the inner surface of the observation window and is received by the exhaust inlet. 5. The semiconductor single crystal manufacturing apparatus according to claim 3, wherein an exhaust pump for performing forced exhaust is provided in an exhaust passage of the exhaust port. 6. The semiconductor single crystal manufacturing apparatus according to claim 5, wherein a filter is provided in an exhaust passage of the exhaust port to capture amorphous generated during purification of the semiconductor single crystal. 7. After the cooling of the refining chamber is started after the completion of the semiconductor single crystal refining, the temperature of the amorphous or the floating in the refining chamber is not changed until it reaches a predetermined direct or indirect precipitating cooling temperature at which it is determined that the precipitation is almost completed. 7. An apparatus according to claim 2, further comprising an inert gas extension jetting means for continuously blowing the inert gas heated from the active gas jetting means into an observation window area in the purification chamber. Semiconductor single crystal manufacturing apparatus according to the above. 8. The observation window covers the window opening provided on the wall surface of the purification chamber with a window body, and the window body is air-tightly attached to the wall surface of the purification chamber via a packing. The semiconductor single crystal manufacturing apparatus according to any one of claims 1 to 7, wherein a cooling water flow passage for packing cooling is formed in the region. 9. The semiconductor single crystal is purified by a FZ method in which a floating melting zone is formed at a junction between the single crystal and the polycrystalline material by heating a high-frequency induction heating coil. 9. The semiconductor single crystal manufacturing apparatus according to claim 1, wherein a gas doping tube for doping a dopant gas is attached to the floating melting zone.