JP7006636B2 - Silicon single crystal manufacturing equipment - Google Patents

Description

The present invention relates to a silicon single crystal manufacturing apparatus.

To pull up a silicon single crystal by the Czochralski method (CZ method), a crucible is installed in the main chamber, and the silicon put into the crucible is heated to make it into a melt state, and the seed crystal is implanted in the silicon melt. It is done by pulling the seed crystal upward with a pulling wire. The pulled-up silicon single crystal is housed in a pull chamber provided in the upper part of the main chamber, the main chamber is sealed by a gate valve, and then the pull chamber is moved and taken out from the pull-up device.

The temperature of the silicon melt surface in the crucible is one of the important parameters when pulling up the silicon single crystal, and the quality of the silicon single crystal is precisely controlled by accurately measuring the temperature of the melt surface. It becomes possible to do.
Conventionally, in Patent Document 1, a radiation thermometer and a two-dimensional thermometer are arranged above the pull chamber.
A technique for measuring the temperature of the surface of a silicon melt using these two thermometers is disclosed.

Japanese Unexamined Patent Publication No. 2014-218402

However, in the technique described in Patent Document 1, the measurement distance from the surface of the silicon melt to the thermometer becomes large. In particular, the radiation thermometer has a problem that when the measurement distance is long, the diameter of the measurement spot that can be measured becomes large and the average temperature in the spot is displayed, so that the measured value fluctuates.
Further, when the measurement distance becomes long, the radiation thermometer picks up disturbances such as radiant heat diffusely reflected in the main chamber and the pull chamber, and there is a problem that the temperature of the silicon melt surface cannot be accurately measured.

An object of the present invention is to provide a silicon single crystal manufacturing apparatus capable of controlling the quality of a silicon single crystal with high accuracy.

The silicon single crystal manufacturing apparatus of the present invention includes a main chamber, a gate valve, a pull chamber, and a melt surface temperature measuring unit for measuring the temperature of the silicon melt surface in a pit arranged in the main chamber. The melt surface temperature measuring unit is arranged between the gate valve and the pull chamber, and is composed of a tubular portion having an opening formed on the outer peripheral surface and a material that transmits radiant heat, and the opening of the tubular portion. A heat guiding portion that is arranged inside the tubular portion and guides radiant heat radiated from the surface of the silicon melt to the window portion, and is arranged outside the tubular portion. It is characterized by including a radiation thermometer that measures the radiant heat guided from the heat guide portion via the window portion.

According to the present invention, a melt surface temperature measuring unit is arranged between the main chamber and the pull chamber. Therefore, as compared with the technique described in Patent Document 1 described above, the measurement distance of the radiation thermometer can be shortened, the measurement spot diameter can be reduced, and the temperature of the silicon melt surface can be accurately measured. Then, based on this temperature measurement result, the quality of the silicon single crystal can be controlled with high accuracy.

In the silicon single crystal manufacturing apparatus of the present invention, it is preferable that the heat conductive portion is inserted into the tubular portion and supported by a support member that is movable in the insertion direction.

According to the present invention, the heat guiding portion can be moved in the radial direction of the tubular portion by advancing and retreating the support member in the insertion direction thereof. Therefore, by moving the measurement spot on the surface of the silicon melt, the temperature distribution in the crucible radial direction can be easily measured. In addition, the temperature at any position can be measured in the radial direction.

In the silicon single crystal manufacturing apparatus of the present invention, a plurality of openings are formed on the outer peripheral surface of the tubular portion along the outer peripheral direction of the tubular portion, and the plurality of openings are the window portion and the heat guiding portion. It is preferable that the radiation thermometer is detachably arranged and the openings other than the opening provided with the window portion are closed by the lid portion.

According to the present invention, the window portion, the heat guide portion and the radiation thermometer can be moved to any of a plurality of openings, and the temperature at a desired position on the surface of the silicon melt can be measured. Further, since the opening to which the window portion is not provided is closed by the lid portion, the radiant heat in the main chamber can be suppressed from leaking to the outside, and the temperature of the silicon melt surface can be measured more accurately.

The vertical sectional view which shows the schematic structure of the silicon single crystal manufacturing apparatus which concerns on one Embodiment of this invention. The cross-sectional view of the gate valve constituting the silicon single crystal manufacturing apparatus. The vertical sectional view of the melt surface temperature measuring part constituting the silicon single crystal manufacturing apparatus. The cross-sectional view of the melt surface temperature measuring part.

[Embodiment]
Hereinafter, an embodiment of the present invention will be described.
[Structure of silicon single crystal manufacturing equipment]
As shown in FIG. 1, the silicon single crystal manufacturing apparatus 1 is an apparatus used in the MCZ (Magnetic field applied Czochralski) method. The silicon single crystal manufacturing apparatus 1 includes a main chamber 2, a gate valve 3, a melt surface temperature measuring unit 4, and a pull chamber 5.

Inside the main chamber 2, a crucible 21, a heater 22, a heat shield 23, a cooling cylinder 24, and the like are arranged. The silicon melt M is housed in the crucible 21. A pair of electromagnetic coils 25 are provided outside the main chamber 2.

The gate valve 3 is provided at the upper end of the main chamber 2. As shown in FIG. 2, the gate valve 3 includes a valve box 31, a valve body 32, a swivel shaft 33, a connecting member 34, and a swivel drive unit 35.
The valve box 31 is configured to accommodate the valve body 32 inside. The valve box 31 is detachably fixed to the upper end of the main chamber 2. The valve box 31 includes an upper opening 311 located on the upper side and a lower opening 312 located on the lower side when fixed to the main chamber 2.
The valve body 32 is formed in a disk shape capable of closing the lower opening 312. The swivel shaft 33 is rotatably provided in the valve box 31 so that a part thereof is located in the valve box 31.
The connecting member 34 connects the upper portion of the valve body 32 and the swivel shaft 33. The swivel drive unit 35 is arranged outside the valve box 31.
The swivel drive unit 35 is connected to a portion of the swivel shaft 33 located outside the valve box 31, and by rotating the swivel shaft 33, a closed position that closes the upper part of the main chamber 2 as shown by a solid line in FIG. And the open position where the upper part of the main chamber 2 is opened as shown by the alternate long and short dash line, the valve body 32 is swiveled.

As shown in FIGS. 1, 3 and 4, the melt surface temperature measuring unit 4 includes an annular disk portion 41, a tubular portion 42, a measuring unit 43, and a lid portion 44.

The annular disk portion 41 is provided at the upper end of the tubular portion 42, and the tubular portion 42 is provided at the upper end of the gate valve 3. The annular disk portion 41 is made of a metal such as stainless steel. The annular disk portion 41 has a circular outer shape, and has an opening having the same shape as the inner shape of the lower end thereof.

The tubular portion 42 has a hexadecagonal outer shape in a plan view and a circular inner shape. The tubular portion 42 is made of the same material as, for example, the annular disk portion 41. Eight straight portions of the tubular portion 42 that are not adjacent to each other in a plan view are provided with openings 421 that penetrate the inside and outside of the tubular portion 42.

The measuring unit 43 includes a closing member 431, a mounting table 432, a window portion 433, a mirror 434 as a heat guiding portion, a support member 435, a moving drive portion 436, and a radiation thermometer 437.
The opening 421 of the tubular portion 42 is provided with a closing member 431 that closes the opening. The closing member 431 is detachably fixed to any one or a plurality of of the eight openings 421. The closing member 431 is made of, for example, the same material as the tubular portion 42. The closing member 431 is provided with two through holes arranged one above the other. A guide cylinder member 438 is provided in the lower through hole. The guide cylinder member 438 is provided so that its central axis is parallel to the horizontal plane.
The mounting table 432 is formed in a plate shape and is fixed so as to extend outward from the lower part of the tubular portion 42.
The window portion 433 is made of a material that transmits the radiant heat H of the silicon melt M. For example, the window portion 433 is made of quartz. The window portion 433 is fixed so as to close the through hole on the upper side of the closing member 431.

The mirror 434 is made of a material that reflects radiant heat H. The mirror 434 is composed of, for example, a silicon mirror.
The support member 435 includes a rod-shaped portion 435A and a mirror holding portion 435B. The rod-shaped portion 435A has an outer shape formed in the same shape as the inner shape of the guide cylinder member 438, and is slidably inserted into the guide cylinder member 438. The mirror holding portion 435B is provided at the inner end portion of the cylindrical portion 42 in the rod-shaped portion 435A. The mirror 434 is fixed to the mirror holding portion 435B so that the angle formed by the horizontal plane and the reflecting surface 434A of the mirror 434 is 45 °.

The moving drive unit 436 is fixed on the mounting table 432 at a position that does not overlap with the rod-shaped portion 435A of the support member 435 in a plan view. The moving drive unit 436 is fixed to the outer end of the cylindrical portion 42 in the rod-shaped portion 435A via the connecting member 436A. The movement drive unit 436 moves the mirror 434 via the rod-shaped portion 435A.
The radiation thermometer 437 is fixed at a position on the mounting table 432 on the outside of the tubular portion 42 so as not to overlap with the moving drive portion 436 in a plan view. The radiation thermometer 437 measures the radiant heat H reflected by the reflecting surface 434A of the mirror 434.

The lid portion 44 is made of the same material as the tubular portion 42. The lid portion 44 has the same shape as the closing member 431, but does not have a through hole like the closing member 431. The lid portion 44 is detachably fixed to the opening 421 in which the measuring unit 43 is not provided among the eight openings 421 of the tubular portion 42, and closes the opening 421.

The pull chamber 5 is provided above the annular disk portion 41 of the melt surface temperature measuring portion 4. The pull chamber 5 is provided with an introduction section (not shown) for introducing an inert gas such as Ar gas into the main chamber 2, a pull-up drive section (not shown) for raising / lowering and rotating the cable 51 for pulling up the silicon single crystal S, and the like. ing.

[Manufacturing method of silicon single crystal using a melt surface temperature measuring unit]
Next, a method for manufacturing the silicon single crystal S using the melt surface temperature measuring unit 4 will be described. In this embodiment, a case where a silicon single crystal S having a diameter of a straight body portion S2 after peripheral grinding is manufactured is illustrated, but a silicon single crystal S having a diameter of 200 mm, 450 mm, or another size is manufactured. May be good. Further, a dopant for adjusting the resistivity may or may not be added to the silicon melt M.

First, with the mirror 434 present at the position shown by the solid line in FIG. 1, a control unit (not shown) maintains the inside of the main chamber 2 in an inert gas atmosphere under reduced pressure, rotates the crucible 21, and rotates the crucible. A solid raw material such as polycrystalline silicon filled in 21 is melted by heating the heater 22 to generate a silicon melt M.
After the generation of the silicon melt M, first, the radiation thermometer 437 measures the temperature of the first measurement point P1 on the surface of the silicon melt M. After that, the control unit drives the moving drive unit 436, and the mirror 434 is sequentially moved to the two positions shown by the two-dot chain line in FIG. 1, while the radiation thermometer 437 makes a second measurement on the surface of the silicon melt M. The temperature of the point P2 and the temperature of the third measurement point P3 are measured. At this time, the temperature of only one of the second measurement point P2 and the third measurement point P3 may be measured. Further, between the first measurement point P1 and the second measurement point P2, between the second measurement point P2 and the third measurement point P3, or on the right side of the third measurement point P3 in FIG. The temperature at any position of may be measured.
Then, the control unit detects the temperature distribution on the surface of the silicon melt M based on the measurement results of the first to third measurement points P1 to P3. The control unit controls the heater 22 so as to have a desired temperature distribution, then measures the temperatures of the first to third measurement points P1 to P3 again, and keeps the heater 22 until the desired temperature distribution is reached. The control and the temperature measurement of the first to third measurement points P1 to P3 are repeated.

When the surface of the silicon melt M has a desired temperature distribution, the control unit controls the electromagnetic coil 25 to apply a magnetic field to the silicon melt M. After that, the control unit is a silicon single crystal having a shoulder portion S1, a straight body portion S2, and a tail portion (not shown) while the mirror 434 is present at the position shown by the solid line in FIG. Raise S.
At the time of this pulling up, the radiation thermometer 437 measures the temperature of the first measurement point P1 at a predetermined timing. Based on this temperature measurement result, the control unit controls the heater 22 so that the temperature of the silicon melt M becomes a temperature suitable for forming the shoulder portion S1, the straight body portion S2, and the tail portion.

When the silicon single crystal S is separated from the silicon melt M, the control unit stops applying the magnetic field to the silicon melt M and controls the heater 22 so as to cool the silicon single crystal S. When the entire silicon single crystal S is housed in the pull chamber 5, the control unit controls the swivel drive unit 35 of the gate valve 3 to move the valve body 32 to the closed position. Then, the silicon single crystal S is taken out from the pull chamber 5.

[Action and effect of the embodiment]
According to the above embodiment, since the melt surface temperature measuring unit 4 is arranged between the main chamber 2 and the pull chamber 5, the measuring distance of the radiation thermometer 437 can be shortened. Therefore, the diameter of the measurement spot can be reduced to reduce the variation in temperature measurement on the surface of the silicon melt, and the quality of the silicon single crystal S can be controlled with high accuracy based on the accurate temperature measurement result.
Since the diameter of the measurement spot becomes smaller, it is possible to suppress the field loss due to the interference of the measurement field of view, which limits the measurement position, and it is possible to expand the measurement position in the radial direction of the crucible 21. Therefore, a wider range of temperature distributions can be measured.
Further, since a plurality of openings 421 are formed in the tubular portion 42, the arrangement position of the measurement unit 43 is changed according to the position of the surface of the silicon melt M to be measured, for example, as shown by the alternate long and short dash line in FIG. Or can be added.
Further, since the measurement unit 43 has a unit structure, it is easy to change the measurement position.

[Modification example]
The present invention is not limited to the above embodiment, and various improvements and design changes can be made without departing from the gist of the present invention.

For example, only one opening 421 may be provided in the cylindrical portion 42. In this case, the measuring unit 43 may be fixed to one opening 421 in a detachable manner, or may be fixed in a detachable manner.
The mirror 434 may be immovably fixed to the closing member 431 or the window portion 433.
A plurality of measuring units 43 may be simultaneously arranged in each of the plurality of openings 421, and the temperature may be measured by each radiation thermometer 437.
The pull chamber 5 may be directly fixed on the tubular portion 42 without providing the annular disk portion 41.
In the above embodiment, the temperature was measured at all timings before the magnetic field was applied to the silicon melt M, when the shoulder portion S1 was formed, when the straight body portion S2 was formed, and when the tail portion was formed, but one or more and three or less were measured. It may be done at the timing of. The temperature of only one measurement point may be measured before the magnetic field is applied to the silicon melt M.
The present invention may be applied to the production of a silicon single crystal S by the so-called CZ method, which does not have an electromagnetic coil 25.

1 ... Silicon single crystal manufacturing equipment, 2 ... Main chamber, 3 ... Gate valve, 4 ... Melt surface temperature measuring unit, 5 ... Pull chamber, 21 ... Radiation, 42 ... Cylindrical part, 421 ... Opening, 433 ... Window part, 434 ... Mirror (heat conducting part), 435 ... Support member, 437 ... Radiation thermometer, H ... Radiant heat, M ... Silicon melt, S ... Silicon single crystal.

Claims (3)

With the main chamber
With a gate valve
With a pull chamber,
It is provided with a melt surface temperature measuring unit for measuring the temperature of the silicon melt surface in the crucible arranged in the main chamber.
The melt surface temperature measuring unit is
A cylindrical portion arranged between the gate valve and the pull chamber and having an opening formed on the outer peripheral surface,
A window portion made of a material that transmits radiant heat and provided at the opening of the cylindrical portion, and a window portion.
A heat guiding portion that is arranged inside the tubular portion and guides radiant heat radiated from the surface of the silicon melt to the window portion.
A silicon single crystal manufacturing apparatus, which is arranged outside the tubular portion and includes a radiation thermometer for measuring radiant heat guided from the heat guide portion through the window portion. In the silicon single crystal manufacturing apparatus according to claim 1,
A silicon single crystal manufacturing apparatus, wherein the heat conducting portion is inserted through the tubular portion and supported by a support member that is movable in the insertion direction. In the silicon single crystal manufacturing apparatus according to claim 1 or 2.
A plurality of openings are formed on the outer peripheral surface of the tubular portion along the outer peripheral direction of the tubular portion.
The plurality of openings are configured so that the window portion, the heat guide portion, and the radiation thermometer can be detachably arranged.
A silicon single crystal manufacturing apparatus characterized in that an opening other than the opening provided with the window portion is closed by a lid portion.

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