JP2016041638A - Single crystal growth apparatus and single crystal growth method using the apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a single crystal growth apparatus capable of growing a silicon single crystal having high resistivity, and a single crystal growth method using the apparatus.SOLUTION: A single crystal growth apparatus 1 is provided that includes in a main chamber 5, a silicon thin rod insertion unit 9 capable of inserting each of a plurality of silicon thin rods 8 containing dopant independently into raw material melt 2 and melting the thin rods 8. A silicon single crystal growth method using the single crystal growth apparatus 1 is provided that includes: a sample crystal growth step of growing a sample crystal after melting a raw material in a quartz crucible 3 and of measuring a conductivity type and resistivity of the sample crystal; a determination step for determination of a conductivity type and an insertion amount of the silicon thin rod 8, of determining a conductivity type and an insertion amount of the silicon thin rod 8 to be inserted into the raw material melt 2, based on the measured results; a silicon thin rod melting step of inserting a determined amount of the silicon thin rod 8 of a determined conductivity type into the raw material melt 2, and melting the silicon thin rod 8, thereby adjusting an amount of the dopant in the raw material melt 2 and adjusting the resistivity of a silicon single crystal 6; and a silicon single crystal pulling step.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a single crystal growing apparatus and a single crystal growing method used for growing a single crystal such as a silicon single crystal by the Czochralski method (hereinafter also referred to as CZ method).

RF (high frequency) devices are used for communications such as cellular phones. A compound semiconductor has been used exclusively for this RF device.
In recent years, however, the progress of miniaturization of CMOS processes and the desire to reduce costs have made it possible to realize silicon-based RF devices.

  In an RF device using a silicon single crystal wafer, if the substrate resistivity is low, the loss is large due to high conductivity, and a high resistivity is used. For this reason, there is a demand for 750 Ωcm or more, further 3000 Ωcm or more, and most recently 10,000 Ωcm or more.

  A wafer having a thin oxide film and a thin silicon layer formed on the surface of a silicon substrate called SOI (Silicon on Insulator) may be used. In this case as well, a high resistivity is desired.

  Conventionally, in the CZ method, impurities contained in the quartz crucible are melted out, so that a single crystal having a high resistivity cannot be grown. Therefore, in general, an FZ crystal grown by a floating zone melting method (hereinafter also referred to as FZ method) is often used as a high resistivity single crystal.

  However, in the CZ method, as disclosed in Patent Document 1, a synthetic quartz crucible has been used, and it has become possible to grow a single crystal having a high resistivity of 10,000 Ωcm if it is non-doped.

  Nowadays, hybrid quartz crucibles in which a synthetic quartz layer made of synthetic quartz powder is formed inside a natural quartz crucible have become mainstream, and it has become possible to grow high resistivity single crystals even by the CZ method. .

  On the other hand, dopants such as B and P are also contained as impurities in the silicon polycrystal as a raw material, which is an obstructive factor when growing a high resistivity single crystal. Efforts to reduce these impurities have been made and improved daily.

However, the impurities in the bulk of the quartz crucible and the raw material silicon polycrystal have been reduced, but as the accuracy of the required resistivity has improved, the impurities on the bulk surface have become a problem.
For example, taking the case where the contamination from the environment is B as an example, the B concentration in the bulk is reduced to about 10 ¹¹ units per 1 cm ³ due to improvement of the manufacturing process. However, when the storage state is poor, when the crystal is actually grown by B adhering to the bulk surface, the concentration may reach nearly 10 ¹³ .

  As in the case of B, the impurities on the bulk surface are affected by the state at the time of cleaning and the environment at the time of storage, so it is difficult to predict. After melting the raw material, the crystal must be grown and the resistivity I wasn't sure what to do.

As a method for solving this, Patent Document 2 describes a method in which a crystal is grown in advance and the resistivity is measured, and then a dopant having an opposite polarity is added. However, no specific input method is described.
For example, in order to put the dopant outside the single crystal growth apparatus into the crucible in the single crystal growth apparatus, the atmosphere in the single crystal growth apparatus that has been reduced in pressure to grow the single crystal is once returned to atmospheric pressure, Thereafter, since it is necessary to put the dopant into the crucible in the single crystal growth apparatus and to reduce the pressure in the single crystal growth apparatus again, there is a problem that it takes time and labor.

An example of a dopant injection method that can solve the problem of Patent Document 2 is an apparatus as described in Patent Document 3.
In such an apparatus, a granular dopant is introduced, but it is necessary to increase the power of the heater again in order to dissolve it, and there is a problem that single crystallization becomes difficult due to undissolved residual dopant.

As a method capable of solving the problem of inhibiting this single crystallization, Patent Document 4 discloses a method in which a silicon thin rod containing a dopant is inserted into a raw material melt and dissolved.
According to this method, it is possible to adjust the resistivity of a single crystal grown in a relatively short time and relatively easily without inhibiting single crystallization.

  However, the method as in Patent Document 4 has a problem that the range in which the resistivity of the single crystal to be grown can be adjusted is narrow.

Japanese Patent Laid-Open No. 5-58788 JP 2002-226295 A JP-A-9-227275 Japanese Patent Application Laid-Open No. 6-234592

  The present invention has been made in view of the above-described problems, and has a single crystal growth apparatus that has a wide range in which the resistivity can be adjusted as compared with the conventional case in which only one silicon rod is used. It aims at providing the used single crystal growth method.

In order to achieve the above object, according to the present invention, there is provided a single crystal growth apparatus for growing a silicon single crystal by the Czochralski method,
The apparatus for growing a single crystal includes a main chamber in which a quartz crucible containing a raw material melt and a heater for heating and maintaining the quartz crucible are disposed, and a silicon single crystal grown is connected to the upper portion of the main chamber. And a pulling chamber to be stored
The main chamber includes a silicon rod insertion machine capable of independently inserting and melting a plurality of silicon rods containing dopant into the raw material melt, and growing a single crystal Providing equipment.

  With such a single crystal growth apparatus, a plurality of silicon thin rods containing a dopant can be controlled independently, so that the resistivity can be adjusted as compared with the conventional case of only one silicon thin rod. The possible range can be greatly expanded.

At this time, it is preferable that at least one of the plurality of silicon thin rods includes an N-type dopant, and at least one includes a P-type dopant.
In this way, the conductivity type can be controlled, and when the resistivity of the silicon single crystal is too low, that is, when there are too many dopants, the silicon thin rods containing the dopants of opposite polarity are dissolved in the raw material melt. By inserting it into the liquid, the resistivity of the silicon single crystal can be increased.

At this time, the N-type dopant is any one or more of N, P, As, Bi, and Sb, and the P-type dopant is any one or more of B, Ga, In, and Al. It can be.
As described above, an element generally used as a dopant in a silicon semiconductor can be used.

Further, at this time, it is more preferable that the N-type dopant is P and the P-type dopant is B.
Thus, the resistivity of the silicon single crystal can be more reliably controlled by using P or B as a dopant.

According to the present invention, there is provided a silicon single crystal growth method for growing a silicon single crystal using the single crystal growth apparatus,
A raw material melting step of filling and melting the raw material in the quartz crucible, a sample crystal growth step of growing a sample crystal and measuring a conductivity type and resistivity of the sample crystal;
Alternatively, in the multi-pulling for growing a plurality of the silicon single crystals with the quartz crucible, a multi-pulling step for measuring the conductivity type and resistivity of the previous silicon single crystal,
Based on the measured conductivity type and resistivity, the conductivity type of the silicon rod to be inserted into the raw material melt, and the conductivity type and insertion amount determination step of the silicon rod to determine the insertion amount;
The silicon that is grown from the raw material melt is adjusted by adjusting the amount of dopant in the raw material melt by inserting the molten silicon rod of the determined conductivity type into the raw material melt in a determined amount and melting it. A silicon thin rod melting process to adjust the resistivity of the single crystal;
There is provided a silicon single crystal growth method comprising a silicon single crystal pulling step of pulling a silicon single crystal from the raw material melt.

With such a method, since the single crystal growth apparatus of the present invention that can independently control a plurality of silicon thin rods containing a dopant is used, it is grown as compared with the case of only one silicon thin rod. The range in which the resistivity of the single crystal can be adjusted can be greatly expanded.
Furthermore, the sample crystal is actually grown, and the dopant amount is adjusted based on the measurement result of the conductivity type and resistivity of the grown sample crystal or the previous silicon single crystal, so that the desired conductivity type and resistivity can be adjusted. A silicon single crystal can be manufactured with high accuracy.

At this time, the conductivity type and resistivity of the silicon single crystal to be grown next are estimated from the measured conductivity type and resistivity, and the estimated conductivity type is a desired conductivity type, and the estimated resistivity is desired. If the estimated conductivity type is opposite in polarity to the desired conductivity type, the thin silicon rod having the same conductivity type as the desired conductivity type has the desired resistance value. So as to decide to melt into the raw material melt,
If the estimated conductivity type and resistivity are appropriate for the desired conductivity type and resistivity, determine not to melt the silicon rods;
When the estimated conductivity type is a desired conductivity type and the estimated resistivity is lower than the desired resistivity, the silicon thin rod having a conductivity type opposite in polarity to the desired conductivity type is obtained as the desired conductivity type. It can be determined that the raw material melt is melted so as to have a resistance value of.

  Using such a method, the resistivity of the silicon single crystal to be grown next estimated from the conductivity type and resistivity measured in advance is higher or lower than the desired resistivity. Can be adjusted even when the desired conductivity type and the conductivity type are opposite in polarity.

At this time, the silicon single crystal to be grown can have a resistivity of 750 Ωcm or more.
According to the method for growing a silicon single crystal of the present invention, it is possible to grow a silicon single crystal having a desired conductivity type and a resistivity of 750 Ωcm or more with high accuracy.

Furthermore, at this time, the silicon single crystal to be grown can have a resistivity of 3000 Ωcm or more.
According to the method of the present invention, a silicon single crystal having a resistivity of 3000 Ωcm or more can be grown with high accuracy.

As described above, the single crystal growth apparatus of the present invention can greatly expand the range in which the resistivity can be adjusted as compared with the conventional case where only one silicon rod is used. Control is also possible.
Furthermore, with the single crystal growth method of the present invention, a silicon single crystal having a desired conductivity type and resistivity can be accurately manufactured.

It is the schematic which shows an example of the single crystal growth apparatus in this invention. It is a flowchart which shows an example of the single crystal growth method in this invention. It is a flowchart which shows an example of the conductivity type and insertion amount determination procedure of the silicon | silicone thin stick in this invention.

Hereinafter, although an embodiment is described about the present invention, the present invention is not limited to this.
As described above, the conventional method has a problem that the range in which the resistivity of the single crystal to be grown can be adjusted is narrow.

  Therefore, the present inventors have conducted intensive studies to solve the above-described problems. As a result, in a single crystal growth apparatus, a plurality of thin silicon rods containing a dopant can be independently inserted into the raw material melt and melted, thereby allowing the resistivity to be adjusted as compared with the conventional case. It has been conceived that the conductivity type can be controlled as well as greatly extending the range. And the best form for implementing these was scrutinized and the present invention was completed.

First, the single crystal growth apparatus of the present invention will be described.
As shown in FIG. 1, a single crystal growing apparatus 1 according to the present invention includes a main chamber 5 in which a quartz crucible 3 that contains a raw material melt 2 and a heater 4 that heats and keeps the quartz crucible 3 are disposed. And a pulling chamber 7 which is connected to the upper portion of 5 and in which the grown silicon single crystal 6 is pulled up and stored. The main chamber 5 includes a silicon thin rod insertion machine 9 that can insert and melt a plurality of silicon thin rods 8 containing a dopant into the raw material melt 2 independently.

  An upper portion of the pulling chamber 7 is provided with a wire winding mechanism (not shown) for unwinding or winding the pulling wire 10 for pulling up the silicon single crystal 6. A tip holder 19 for holding the seed crystal 11 is provided at the tip of the pulling wire 10 unwound from the wire winding mechanism, and the seed crystal 11 is locked to the seed holder 19. A silicon single crystal 6 is grown below 11.

  Here, the quartz crucible 3 is supported by a graphite crucible 18, and the graphite crucible 18 is further supported by a support shaft 12 that can be moved up and down by a rotation drive mechanism (not shown) attached to the lower part of the silicon single crystal growing apparatus 1. It is supported. A heat insulating member 13 is provided around the heater 4 disposed around the quartz crucible 3.

  The quartz crucible 3 uses a synthetic quartz crucible to reduce impurities and to control the resistivity of the single crystal grown with higher accuracy, but is not limited to this. Furthermore, as a raw material to be filled in the quartz crucible 3, it is possible to control the resistivity of the single crystal grown with higher accuracy by using a high-purity polycrystal, but it is not limited to this.

  A cylindrical gas purge cylinder 16 is disposed above the surface of the raw material melt 2 so as to surround the silicon single crystal 6 being pulled up. The gas purge cylinder 16 can be made of, for example, a graphite material. The gas purge cylinder 16 is provided so as to extend from the ceiling of the main chamber 5 toward the raw material melt 2. Furthermore, a heat shielding plate 17 is provided on the raw material melt 2 side of the gas purge cylinder 16.

A gas inlet 14 is provided above the pulling chamber 7. A gas outlet 15 is provided below the main chamber 5.
An inert gas such as argon (Ar) gas introduced from the gas inlet 14 into the pulling chamber 7 passes between the silicon single crystal 6 being pulled and the gas purge cylinder 16, and then the raw material melt 2. Then, it is discharged from the gas outlet 15 to the outside of the main chamber 5 together with the evaporated material from the raw material melt 2.

  Since the single crystal growth apparatus 1 as described above can control the insertion of a plurality of silicon thin rods 8 containing a dopant into the raw material melt 2 independently, the conventional single crystal growing rod 1 has only one silicon thin rod 8. Compared to the case, the range in which the resistivity can be adjusted can be greatly expanded.

  The silicon thin rod 8 can be inserted so as to be attached to the tip of a piston-like rod that can move substantially vertically in the main chamber 5 maintained at a reduced pressure. At this time, the piston-like rod is preferably made of a material stable at high temperature such as a carbon material or a quartz material. Since the thin silicon rod 8 is kept in a reduced pressure state, it is preferably mounted first.

  The silicon rod 8 is retracted to a position where it does not come into contact with the raw material melt 2 while dopant adjustment is not necessary. When dopant adjustment is necessary, the desired concentration of dopant in the raw material melt 2 can be adjusted by extruding a desired amount of the thin silicon rod 8 into the raw material melt 2 and melting it. is there.

  Note that the silicon thin rod 8 used in the present invention may be, for example, one cut from a single crystal block by the CZ method or FZ method, or one grown from the beginning as a thin single crystal. For example, if a CZ single crystal block is cut out in a direction transverse to the growth direction, a higher resistivity can be controlled. However, the silicon thin rod 8 is not limited to this, and may be polycrystalline, for example.

  Further, if the resistivity of the silicon thin bar 8 is increased, the accuracy of controlling the resistivity of the silicon single crystal 6 is improved, but the amount to be melted is increased accordingly. On the contrary, if the resistivity of the silicon thin bar 8 is lowered, the amount of melting can be reduced, but the accuracy of controlling the resistivity of the silicon single crystal 6 is lowered.

Further, as the amount of the raw material increases, the amount of the silicon rod 8 to be melted also increases. Furthermore, if the thickness of the thin silicon rod 8 is increased, the insertion amount can be reduced, but the accuracy of the dissolution amount is lowered.
Conversely, if the silicon rod 8 is thin, the accuracy of the amount of dissolution is improved, but a long rod and a long stroke are required.

Accordingly, it is preferable to appropriately select the silicon rod 8 having an appropriate resistivity and size in accordance with the resistivity to be aimed at and the amount of raw material of the silicon single crystal 6 to be grown.
For example, if one is a silicon rod 8 with a relatively low resistivity and the other is a silicon rod 8 with a relatively high resistivity, it can accommodate both large and subtle adjustments in resistivity. Thus, the resistivity adjustable range is greatly expanded as compared with the case of only one.

  Specifically, the resistivity of the silicon rod 8 is about 1 mΩcm to about 1000 Ωcm, the length is about 1 cm to about 100 cm, and the thickness is about 1 mm or 1 mm square to about 100 mm or 100 mm square. it can.

  Further, it can be assumed that at least one of the plurality of silicon rods 8 mounted on the single crystal growth apparatus includes an N-type dopant, and at least one includes a P-type dopant.

  The resistivity in the silicon single crystal 6 is basically determined by subtracting the amount of N-type dopant and the amount of P-type dopant. This is because when the donor and the acceptor coexist, electrons are transferred from the donor level to the acceptor level to be compensated.

If the resistivity is reduced too much using this phenomenon, that is, if there are too many dopants, a dopant of opposite polarity is added to compensate, and the difference in dopant becomes effective as a carrier, thereby increasing the resistivity. be able to. This is called counter dope.
Therefore, by making the polarities of both the N-type silicon rod 8 and the P-type silicon rod 8 insertable, it is possible to increase the resistivity that has been lowered too much.

More specifically, the N-type dopant is any one or more of P, As, Sb, Bi, and N, and the P-type dopant is any one or more of B, Ga, In, and Al. It can be assumed that
As described above, an element generally used as a dopant in a silicon semiconductor can be used.

The dopant contained in the silicon thin rod 8 generally contains one of these elements, but may contain more than one. Furthermore, one silicon rod 8 may contain a dopant having an opposite polarity.
As described above, P and B are mixed due to the environment, and actually have a slightly opposite polarity. Moreover, depending on the content to be controlled, there is a possibility that the opposite polarity is positively included. In such a case, the opposite polarity may be included.

More specifically, it is more preferable to use P as the N-type dopant and B as the P-type dopant.
P and B are relatively easy to obtain and handle compared to other elements, and there is little concern about deterioration of electrical characteristics when included in large quantities, so the resistivity should be controlled more reliably. Can do. .

Next, an example of the single crystal growth method of the present invention will be described with reference to the flowchart of FIG.
In the single crystal growth method of the present invention, the silicon single crystal 6 is grown by the method as described below using the single crystal growth apparatus 1 of the present invention shown in FIG.

(Raw material melting process)
First, the raw material is filled in the quartz crucible 3. Then, the quartz crucible 3 is heated and kept warm by the heater 4 to melt the raw material to obtain the raw material melt 2 (SP1).

(Sample crystal growth process)
Next, a sample crystal is grown, and the conductivity type and resistivity of the sample crystal are measured (SP2). The sample crystal only needs to be able to measure the conductivity type and resistivity. For example, it is sufficient to grow a very small single crystal and use it as the sample crystal.

  Thus, if the sample crystal is grown and its conductivity type and resistivity are measured, the dopant concentration (difference between the N-type dopant and the P-type dopant) in the raw material melt 2 when the sample crystal is grown is determined. You can be sure.

(Multi pulling process)
Or, in multi-pull-up, the conductivity type and resistivity of the previous silicon single crystal 6 are measured (SP3).
Here, the multi-pull-up means that after pulling up the silicon single crystal 6 from the raw material melt 2 accommodated in the quartz crucible 3, the raw material is additionally charged into the raw material melt 2 remaining in the quartz crucible 3 and melted. In this method, the next step of pulling up the silicon single crystal 6 is repeated, and a plurality of silicon single crystals 6 are pulled up with one crucible.

In the case of multiple pulling, it is more preferable to perform the next growth using the same raw material as that used for the previous single crystal growth. In this way, more accurate estimation is possible in SP4 described later.
It is possible to reduce time loss by melting the same raw material as before while preparing and measuring a sample for measuring the conductivity type and resistivity from the previous silicon single crystal 6. is there.

(Silicon rod conductivity type and insertion amount determination process)
Based on the conductivity type and resistivity measured in SP2 or SP3, the conductivity type of the silicon thin rod to be inserted into the raw material melt 2 and the insertion amount are determined (SP4).

Specifically, the determination of the conductivity type and insertion amount of the silicon rod inserted into the raw material melt 2 in the silicon rod conductivity type and insertion amount determination step (SP4) is performed, for example, as shown in FIG. Can be determined.
First, the conductivity type and resistivity of a silicon single crystal 6 to be grown next are estimated from the single crystal conductivity type and resistivity measured in the sample crystal growth step (SP2) or multi-pulling step (SP3) (SP7). .
Next, it is determined whether the estimated conductivity type is a desired conductivity type (SP8).
If the estimated conductivity type is a desired conductivity type, it is next determined whether the estimated resistivity is higher, lower or an appropriate value than the desired resistivity (SP9).

  In SP9, if it is determined to be high, or if the result is negative in SP8, that is, if the estimated conductivity type is the desired conductivity type and the estimated resistivity is higher than the desired resistance value, or the estimated conductivity When the mold has the opposite polarity to the desired conductivity type, it is decided to melt a silicon rod of the same conductivity type as the desired conductivity type into the raw material melt 2 so that the single crystal has the desired resistivity. (SP10).

In SP9, when it is determined that the estimated resistivity is appropriate compared to the desired resistivity, that is, when the estimated conductivity type and resistivity are appropriate for the desired conductivity type and resistivity. Is determined not to melt the silicon rod in the raw material melt 2 (SP11).
Here, the case where the estimated resistivity is appropriate with respect to the desired resistivity is a case where the estimated resistivity falls within this prescribed range with respect to the desired resistivity prescribed range.

  In SP9, when it is determined that the estimated resistivity is lower than the desired resistivity, that is, the estimated conductivity type is the desired conductivity type, and the estimated resistivity is higher than the desired resistivity. If it is low, it is determined to melt the silicon thin rod having a conductivity type opposite to the desired conductivity type into the raw material melt 2 so as to have a desired resistance value (SP12).

  If such a method is used, the dopant concentration in the raw material melt 2 predicted from the resistivity measured in advance can be adjusted even when the dopant concentration is high, low, or even in the opposite polarity. Is possible.

(Silicon rod melting process)
Next, for example, by inserting the silicon thin rod of the conductivity type determined in the silicon thin rod conductivity type and insertion amount determining step (SP4) as described above into the raw material melt 2 in the determined amount and melting it. The dopant amount in the raw material melt 2 is adjusted, and the resistivity of the silicon single crystal 6 grown from the raw material melt 2 is adjusted (see SP5 in FIG. 2).

  The silicon thin rod melting step may be performed during the silicon single crystal pulling step described later. With the silicon single crystal growth apparatus of the present invention, even when a silicon single crystal 6 is grown, the silicon single crystal 6 is dislocated even if a silicon thin rod is inserted into the raw material melt 2 and melted. The possibility of doing is low.

(Silicon single crystal pulling process)
Then, the silicon single crystal 6 is pulled up from the raw material melt 2 whose dopant concentration is adjusted by a silicon thin rod (see SP6 in FIG. 2).

  With the single crystal growth method of the present invention as described above, the silicon single crystal 6 having a desired conductivity type and resistivity can be accurately manufactured.

  At this time, the resistivity of the grown silicon single crystal 6 can be set to 750 Ωcm or more, and further to 3000 Ωcm. According to the present invention, such a high resistivity single crystal can be grown easily and with high accuracy.

The crystal grown by the single crystal growing apparatus or the single crystal growing method described above is useful because the resistivity is controlled with high accuracy.
Thus, a single crystal whose resistivity is controlled with high accuracy is useful in designing a device. In particular, a single crystal whose resistivity is accurately controlled is particularly useful in a high resistivity single crystal in which it is difficult to control the resistivity.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples of the present invention, but the present invention is not limited to these.

Example 1
A silicon thin rod doped with P, the conductivity type being N-type and having a resistivity adjusted to 1 Ωcm, and a silicon thin rod doped with B, having a conductivity type of P-type and a resistivity adjusted to 1 Ωcm were prepared.
The silicon rod has a resistivity of 1Ωcm ± 1.5% for the P type and 1Ωcm ± 4% for the N type, from a silicon single crystal block having a diameter of about 300 mm and a length of about 300 mm. What was cut out as a prism having a length × width × length of 2 cm × 2 cm × 30 cm was used.

  The silicon thin rod thus prepared was mounted on a silicon thin rod insertion machine and installed in the main chamber.

First, a multi-pulling process for growing the previous silicon single crystal was performed by a multi-pull method. Here, the target silicon single crystal is a P-type conductivity type having a resistivity of 750 to 1500 Ωcm, and a dopant B adjusted to have a P-type resistivity of 1450 Ωcm on the top side is made of polycrystalline raw material. A quartz crucible was filled with silicon and heated by a heater to melt.
A silicon single crystal having a diameter of about 206 mm was grown from this raw material melt. In order to measure the resistivity from the previous silicon single crystal, a sample was cut out and the conductivity type and resistivity were measured.

While the sample was measured, the same raw material as used in the previous growth of the silicon single crystal was added to the quartz crucible and melted, and the total weight of the raw material melt was returned to 200 kg.
After melting, the sample resistivity measurement was found. As a result, the conductivity type on the top side of the previous silicon single crystal was P type, the resistivity was about 1100 Ωcm, and the resistivity of the bottom part was about 800 Ωcm, which was slightly lower than the target resistivity.

The B concentration in the raw material melt after growing the silicon single crystal before being estimated from this was 2.2 × 10 ¹³ (atoms / cm ³ ). And it was estimated that B density | concentration in the raw material melt after adding a raw material further to this raw material melt and fuse | melting was 7.3 * 10 < ¹² > (atoms / cm < ³ >). The single crystal grown next from this raw material melt was estimated to have a P-type conductivity and a resistivity of 2300-1700 Ωcm.

The desired conductivity type required for the next single crystal was P-type, and the desired resistivity was 750 to 1500 Ωcm.
The conductivity type of the silicon single crystal to be grown next, which is estimated from the measurement result of the previous silicon single crystal described above in the step of determining the conductivity type and insertion amount of the thin silicon rod, is a desired conductivity type and an estimated resistance. Since the rate is higher than the desired resistivity, it was decided to melt a silicon rod of a desired conductivity type (P type) into the raw material melt so as to have a desired resistance value.

Therefore, the amount of dopant necessary to adjust the resistivity on the top side to about 1450 Ωcm was calculated from the resistivity of the previous single crystal. As a result, the weight of the thin silicon rod whose conductivity type was P-type and whose resistivity was adjusted to 1 Ωcm was 56 g.
Therefore, in the silicon thin rod melting step, a portion of 60 mm corresponding to 56 g of the P-type silicon thin rod was inserted into the raw material melt and melted. Thereafter, a silicon single crystal was grown in a silicon single crystal pulling step.
As a result, it was possible to obtain the desired resistivity of P type conductivity at the top side, 1460 Ωcm at the resistivity, and 1060 Ωcm at the bottom.

(Example 2)
The previous silicon single crystal was grown in the same process as in Example 1. Then, in the same manner as in Example 1, in order to measure the resistivity from the previous silicon single crystal, a sample was cut out, and the conductivity type and resistivity were measured.
As a result of measuring the sample, the conductivity type on the top side was P-type, the resistivity was about 2000 Ωcm, the conductivity type at the bottom part was P-type, and the resistivity was about 1520 Ωcm.

  From this result, it is estimated that the conductivity type and resistivity of the silicon single crystal to be grown next from the melted raw material melt by adding the raw material is P type and resistivity is about 3900-3300 Ωcm. It was.

  The desired conductivity type of the silicon single crystal to be grown next is not questioned, but the desired resistivity was 4000 Ωcm or more.

In this case, if the desired conductivity type is P-type in the step of determining the conductivity type and insertion amount of the silicon rod, the conductivity type estimated from the measurement result is the desired conductivity type and the estimated resistivity. Is lower than the desired resistivity. Therefore, a conductive type having a polarity opposite to the desired conductivity type, that is, a thin silicon rod having an N conductivity type is melted in the raw material melt so as to have a desired resistance value. Can be determined.
Alternatively, if the desired conductivity type is N-type and the desired resistivity is 4000 Ωcm or more, the conductivity type estimated from the measurement result is P-type, so that the conductivity type has the opposite polarity to the desired conductivity type. Therefore, it can be determined that a silicon thin rod having the same conductivity type, that is, the N conductivity type, is melted in the raw material melt so as to have a desired resistance value.

Here, since the desired conductivity type was determined to be P-type, when the amount of dopant necessary for this was calculated from the resistivity of the previous single crystal, the conductivity type was N-type and the resistivity was adjusted to 1 Ωcm. It corresponded to 37g by the weight of the silicon thin rod.
Therefore, in the silicon thin rod melting step, a 43 mm portion corresponding to a slightly larger 40 g was inserted into the raw material melt and melted in the silicon thin rod melting step, and then the silicon single crystal was pulled in the silicon single crystal pulling step. .

  As a result, the top side was P-type 4340 Ωcm, and the lowest resistivity portion was 4090 Ωcm, and the desired resistivity of 4000 Ωcm or more could be obtained.

  In Example 2, unlike Example 1, the desired resistivity of the single crystal to be grown next was higher than the resistance value of the previous single crystal. Even in such a case, since both N-type and P-type silicon rods were attached, a single crystal having a desired resistivity could be grown.

(Example 3)
A silicon thin rod having a conductivity type of P type and a resistivity of 1 Ωcm, and a silicon thin rod having a conductivity type of P type and a resistivity of 10 Ωcm, as shown in FIG. Attached to the inserter.

  The target of the previous silicon single crystal in the multi-pulling process was that the conductivity type was P-type and the resistivity was 5000 Ωcm or more. Therefore, in order to grow the previous silicon single crystal and measure the resistivity from the previous silicon single crystal in the same manner as in Example 1, except that the dopant to be filled in the quartz crucible was changed to a very small amount of P-type dopant. The sample was cut out and the conductivity type and resistivity were measured.

  Then, as in Example 1, while the sample was measured, the same raw material used in the previous growth of the silicon single crystal was added to the quartz crucible and melted, and the total weight of the raw material melt was calculated. It was returned to 200 kg.

  As a result of measuring the sample, the conductivity type on the top side was P-type, the resistivity was about 6200 Ωcm, the conductivity type at the bottom part was P-type, and the resistivity was about 4850 Ωcm.

  From this result, it was estimated that the conductivity type and resistivity of the silicon single crystal to be grown next from the raw material melt that was additionally charged with the material was P-type conductivity and the resistivity was about 12500-11500 Ωcm. .

The desired conductivity type required for the next single crystal was P-type, and the resistivity was 5000 Ωcm or more.
As long as the conductivity type is P type and has a high resistivity, 60 g of a silicon rod having a conductivity type of P type and a resistivity of 10 Ωcm is inserted into the raw material melt for the purpose of introducing a small amount of P-type dopant. And melted to grow a silicon single crystal.

  While measuring the resistivity of this silicon single crystal, the same raw material used in the previous silicon single crystal growth was added to the quartz crucible and melted, and the total weight of the raw material melt was returned to 200 kg. I left it.

  As a result of measuring the resistivity, the resistivity on the top side was about 9700 Ωcm P-type, and the resistivity on the bottom part was about 8300 Ωcm P-type.

The desired conductivity type required for the next single crystal was also P-type, and the resistivity was 5000 Ωcm or more.
From the measurement result of the second single crystal, the conductivity type and resistivity of the silicon single crystal that is subsequently grown from the melted raw material melt by adding the raw material are P-type conductivity and 17000 resistivity. It was estimated to be about -16000 Ωcm, and considering the variation in raw materials, the possibility of inversion to the N-type could not be denied.

  Therefore, in the process of determining the conductivity type and insertion amount of the thin silicon rod, the conductivity type estimated from the above measurement results is the desired conductivity type, and the estimated resistivity is higher than the desired resistivity or desired conductivity. Since the polarity may be opposite to that of the mold, it was decided to melt a silicon thin rod having the same conductivity type as the desired conductivity type into the raw material melt so that the single crystal has a desired resistivity.

Therefore, the amount of dopant necessary to adjust the resistivity on the top side to about 6500 Ωcm was calculated from the resistivity of the previous single crystal.
As a result, in the silicon thin rod melting step, 20 g of a silicon thin rod having a P conductivity type and a resistivity of 1 Ωcm was inserted into the raw material melt and melted. Thereafter, a silicon single crystal was grown in a silicon single crystal pulling step.

As a result, it was possible to obtain the desired conductivity type and resistivity of the P type conductivity on the top side, the resistivity of about 6600 Ωcm, the conductivity type of the bottom portion of P type, and the resistivity of about 5500 Ωcm.
Thus, by controlling the silicon rods having the same conductivity type but different resistivity, the resistivity can be controlled more accurately.

(Comparative example)
A silicon single crystal was grown in the same manner as in Example 1 except that an ordinary single crystal growth apparatus in which a silicon thin rod was not inserted was used.
However, the previous single crystal is grown, a sample for resistivity measurement is cut out from this single crystal, and the work in the single crystal growth apparatus is stopped and waited until the conductivity type and resistivity of the sample are measured. It was.
After the measurement result of the resistivity of the sample is clarified, the total amount of the raw material melt is 200 kg by melting with the raw material additionally charged with a desired dopant so that the conductivity type is P type and the resistivity is 750 to 1500 Ωcm. After returning, the next single crystal was grown.

  The conductivity type and resistivity were as intended, but it took about 8 hours longer than the method of the example. Although the method of the example requires time for melting the silicon thin rod, since the process was advanced without waiting for the measurement of the resistivity, it was possible to reduce the loss time.

  The present invention is not limited to the above embodiment. The above-described embodiment is an exemplification, and the present invention has any configuration that has substantially the same configuration as the technical idea described in the claims of the present invention and that exhibits the same effects. Are included in the technical scope.

DESCRIPTION OF SYMBOLS 1 ... Single crystal growth apparatus, 2 ... Raw material melt, 3 ... Quartz crucible, 4 ... Heater,
5 ... main chamber, 6 ... silicon single crystal, 7 ... pulling chamber,
8 ... Silicon rod, 9 ... Silicon rod insertion machine, 10 ... Pulling wire,
11 ... Seed crystal, 12 ... Support shaft, 13 ... Heat insulation member, 14 ... Gas inlet,
15 ... Gas outlet, 16 ... Gas purge cylinder, 17 ... Heat shield plate,
18 ... Graphite crucible, 19 ... Seed holder.

At this time, the conductivity type and resistivity of the silicon single crystal to be grown next are estimated from the measured conductivity type and resistivity, and the estimated conductivity type is a desired conductivity type, and the estimated resistivity is desired. for higher resistivity, or wherein when the estimated conductivity type is opposite polarity to the desired conductivity type, comprising the silicon thin rod of the same conductivity type as said desired conductivity type in the desired resistivity So as to decide to melt into the raw material melt,
If the estimated conductivity type and resistivity are appropriate for the desired conductivity type and resistivity, determine not to melt the silicon rods;
When the estimated conductivity type is a desired conductivity type and the estimated resistivity is lower than the desired resistivity, the silicon thin rod having a conductivity type opposite in polarity to the desired conductivity type is obtained as the desired conductivity type. so that the resistivity can but decides to melt the raw material melt.

More specifically, it is more preferable to use P as the N-type dopant and B as the P-type dopant.
P and B are relatively easy to obtain and handle compared to other elements, and there is little concern about deterioration of electrical characteristics when included in large quantities, so the resistivity should be controlled more reliably. Can do .

(Multi pulling process)
Or, in multi-pull-up, the conductivity type and resistivity of the previous silicon single crystal 6 are measured (SP3).
Here, the multi-pull-up means that after pulling up the silicon single crystal 6 from the raw material melt 2 accommodated in the quartz crucible 3, the raw material is additionally charged into the raw material melt 2 remaining in the quartz crucible 3 and melted. This is a method of repeatedly pulling up a plurality of silicon single crystals 6 with one quartz crucible by repeating the step of pulling up the next silicon single crystal 6.

In SP9, if it is judged to be high, or if a negative result in SP8, i.e., the estimated conductivity type is at a desired conductivity type, when the estimated resistivity is higher than the desired resistivity, or estimated conductivity When the mold has the opposite polarity to the desired conductivity type, it is decided to melt a silicon rod of the same conductivity type as the desired conductivity type into the raw material melt 2 so that the single crystal has the desired resistivity. (SP10).

In SP9, when it is determined that the estimated resistivity is lower than the desired resistivity, that is, the estimated conductivity type is the desired conductivity type, and the estimated resistivity is higher than the desired resistivity. when low, determines that the desired conductivity type so that the silicon thin rod conductivity type opposite polarity to the desired resistivity, melting the raw material melt 2 (SP 12).

The desired conductivity type required for the next single crystal was P-type, and the desired resistivity was 750 to 1500 Ωcm.
The conductivity type of the silicon single crystal to be grown next, which is estimated from the measurement result of the previous silicon single crystal described above in the step of determining the conductivity type and insertion amount of the thin silicon rod, is a desired conductivity type and an estimated resistance. since the rate is higher than the desired resistivity, the silicon thin rod of a desired conductivity type (P-type), so that a desired resistivity, it was decided to melt the raw material melt.

In this case, if the desired conductivity type is P-type in the step of determining the conductivity type and insertion amount of the silicon rod, the conductivity type estimated from the measurement result is the desired conductivity type and the estimated resistivity. since it is lower than the desired resistivity, melting the desired conductivity type opposite polarity conductivity type and, that the raw material melt so conductivity type is an N-type silicon thin rods into desired resistivity Can be determined.
Alternatively, if the desired conductivity type is N-type and the desired resistivity is 4000 Ωcm or more, the conductivity type estimated from the measurement result is P-type, so that the conductivity type has the opposite polarity to the desired conductivity type. since the can decide to melt the raw material melt so as same as the desired conductivity type, i.e. conductivity type is an N-type silicon thin rod into the desired resistivity.

In Example 2, unlike Example 1, the desired resistivity of the next growing single crystal is, was higher than the resistivity of the previous single crystal. Even in such a case, since both N-type and P-type silicon rods were attached, a single crystal having a desired resistivity could be grown.

Claims (8)

A single crystal growing apparatus for growing a silicon single crystal by the Czochralski method,
The apparatus for growing a single crystal includes a main chamber in which a quartz crucible containing a raw material melt and a heater for heating and maintaining the quartz crucible are disposed, and a silicon single crystal grown is connected to the upper portion of the main chamber. And a pulling chamber to be stored
The main chamber includes a silicon rod insertion machine capable of independently inserting and melting a plurality of silicon rods containing dopant into the raw material melt, and growing a single crystal apparatus.   2. The single crystal growing apparatus according to claim 1, wherein at least one of the plurality of silicon thin rods includes an N-type dopant, and at least one includes a P-type dopant.   The N-type dopant is any one or more of P, As, Sb, Bi, and N, and the P-type dopant is any one or more of B, Ga, In, and Al. The single crystal growing apparatus according to claim 2.   The single crystal growth apparatus according to claim 3, wherein the N-type dopant is P and the P-type dopant is B. A silicon single crystal growth method for growing a silicon single crystal using the single crystal growth apparatus according to any one of claims 1 to 4,
A raw material melting step of filling and melting the raw material in the quartz crucible, a sample crystal growth step of growing a sample crystal and measuring a conductivity type and resistivity of the sample crystal;
Alternatively, in the multi-pulling for growing a plurality of the silicon single crystals with the quartz crucible, a multi-pulling step for measuring the conductivity type and resistivity of the previous silicon single crystal,
Based on the measured conductivity type and resistivity, the conductivity type of the silicon rod to be inserted into the raw material melt, and the conductivity type and insertion amount determination step of the silicon rod to determine the insertion amount;
The silicon that is grown from the raw material melt is adjusted by adjusting the amount of dopant in the raw material melt by inserting the molten silicon rod of the determined conductivity type into the raw material melt in a determined amount and melting it. A silicon thin rod melting process to adjust the resistivity of the single crystal;
And a silicon single crystal pulling step for pulling the silicon single crystal from the raw material melt. In the process of determining the conductivity type and insertion amount of the silicon thin rod,
From the measured conductivity type and resistivity, the conductivity type and resistivity of the silicon single crystal to be grown next are estimated, the estimated conductivity type is a desired conductivity type, and the estimated resistivity is a desired resistance value. If it is higher, or if the estimated conductivity type is opposite in polarity to the desired conductivity type, the silicon rod of the same conductivity type as the desired conductivity type is set to the desired resistance value. Decide to melt into the raw material melt,
If the estimated conductivity type and resistivity are appropriate for the desired conductivity type and resistivity, determine not to melt the silicon rods;
When the estimated conductivity type is a desired conductivity type and the estimated resistivity is lower than the desired resistivity, the silicon thin rod having a conductivity type opposite in polarity to the desired conductivity type is obtained as the desired conductivity type. 6. The method for growing a silicon single crystal according to claim 5, wherein the material melt is determined to be melted so as to have a resistance value of.   The silicon single crystal growth method according to claim 5 or 6, wherein the resistivity of the silicon single crystal to be grown is a silicon single crystal of 750 Ωcm or more.   The silicon single crystal growth method according to any one of claims 5 to 7, wherein a resistivity of the silicon single crystal to be grown is a silicon single crystal of 3000 Ωcm or more.

Images