JP5437565B2 - Semiconductor single crystal manufacturing equipment - Google Patents

Description

The present invention relates to a single crystal pulling apparatus and a single crystal manufacturing method for pulling a single crystal semiconductor such as a silicon single crystal using a CZ method (Czochralski method) or the like.

(Conventional technology)
In the CZ method (Czochralski method), a melt is stored in a crucible in a CZ furnace, a dopant is supplied to the melt, and a silicon single crystal to which the dopant is added is pulled from the melt by a pulling mechanism and grown. It is to let you.

In order to give N-type electrical characteristics to a silicon single crystal, arsenic As, phosphorus P, antimony S
An n-type dopant (impurity) such as b is added to the silicon single crystal. Among these dopants, arsenic As and phosphorus P are sublimable dopants and sublimate from the solid phase to the gas phase at a relatively low temperature. Therefore, the containment chamber containing the sublimable dopant is lowered from above the CZ furnace to a predetermined position above the melt, and the dopant in the containment chamber is heated and sublimated by radiant heat radiated from the melt. Conventionally, a dopant supply method of adding a dopant to a silicon crystal by introducing a dopant that has been sublimated into a gas into a melt from a storage chamber has been conventionally performed. In one of these dopant charging methods, the opening end of the supply pipe is positioned at a predetermined position above the melt, and an inert gas such as argon gas is used as a carrier gas for transport, and the melt is supplied from the supply pipe. There is a spraying method in which a dopant is introduced into a melt by a carrier gas by spraying a carrier gas toward the surface. As another charging method, there is a dipping method in which a supply pipe is immersed in the melt, and the dopant is sublimated from the supply pipe into a gas and charged into the melt.

(Prior art found in Patent Document 1)
In Patent Document 1, the impurity supply pipe assembly is attached to the seed chuck of the pulling mechanism, and the impurity supply pipe assembly is moved until the dopant containing portion of the impurity supply pipe assembly is positioned approximately 285 mm above the melt surface by the pulling mechanism. The arsenic in the container is heated and sublimated by radiant heat radiated from the melt at that position.

Further, the impurity supply pipe assembly is lowered to a position where the supply pipe of the impurity supply pipe assembly contacts the melt by a pulling mechanism, and arsenic vapor is introduced into the melt from the supply pipe. Here, the position for sublimating the dopant (about 285 mm from the melt surface)
The upper position is obtained in advance from the analysis result of the thermal model.

(Prior art found in Patent Document 2)
In Patent Document 2, the dopant storage container is arranged at a position where it does not interfere with the pulling mechanism, the storage container is lowered from above the CZ furnace to a position above the upper surface of the quartz crucible, and radiated from the melt at that position. The dopant in the container is dissolved by the radiant heat.

Then, the container is further lowered to a position where the container is immersed in the melt, and the dissolved dopant is introduced into the melt from the open surface of the container.
Japanese translation of PCT publication No. 2003-532611 JP 2005-336020 A

The efficiency of the introduction of the dopant into the melt (absorption efficiency) is determined by the rate at which the dopant is sublimated. The optimum sublimation rate maximizes the input efficiency and minimizes dopant loss.

The sublimation rate is determined by the amount of heat given to the dopant. Therefore, the charging efficiency can be maximized by heating the dopant with an optimal amount of heat.

According to the conventional implementation technique described above and the technique shown in Patent Document 1, the radiant heat given to the dopant varies depending on the position of the dopant containing portion lowered above the melt, and the sublimation speed is accordingly changed. Fluctuates. If the dopant accommodating portion is far from the melt, the sublimation speed becomes slow or the sublimation itself becomes difficult. On the other hand, if the dopant accommodating part is close to the melt, the sublimation speed is increased. When the sublimation speed fluctuates, the efficiency and amount of the dopant introduced into the melt fluctuate, which affects the dopant concentration and resistance value of the silicon single crystal. Therefore, if the sublimation speed varies, the intended dopant concentration and resistance cannot be achieved.

However, the dopant containing part is lowered to the optimum position, the optimum amount of radiant heat is added to the dopant, the sublimation rate is optimized and the charging efficiency is maximized, the dopant concentration of the silicon single crystal,
It is not easy to set the resistance value to a desired value.

That is, as seen in Patent Document 1, even if the optimal lowering position is obtained in advance from simulations and experimental results, the temporal change of the thermal environment in the CZ furnace, that is, the temporal change of the in-furnace parts,
Due to component deterioration or the like, the lowered position may not be optimal and the sublimation speed may fluctuate. For example, a heater for heating a quartz crucible is made of a carbon material, but the carbon material deteriorates with time. When such a change with time of the heater occurs, even if the dopant accommodating portion is lowered to the same position, the amount of radiant heat absorbed by the dopant fluctuates with time and the sublimation rate fluctuates.
As described above, sublimation due to radiant heat is easily affected by changes over time in the in-furnace parts (hot zone), and it is extremely difficult to control the sublimation speed.

Further, the present inventors have found that when an N ++ type silicon single crystal having a low resistivity is pulled up and grown by adding a dopant to the silicon single crystal at a high concentration, the crystal tends to collapse. In order not to cause crystal breakage, the sublimation rate of a sublimable dopant such as arsenic As and phosphorus P, which gives N-type electrical characteristics to the silicon single crystal, is accurately controlled, so that the dopant in the silicon single crystal It is necessary to control the concentration accurately.

The present invention has been made in view of such circumstances, and it is an object of the present invention to make it possible to accurately control the sublimation rate of the dopant without being affected by the temporal change of the thermal environment in the furnace. is there.

The first invention provides a semiconductor single crystal in which a dopant is supplied to a melt stored in a crucible in a furnace, and the semiconductor single crystal to which the dopant is added from the melt is pulled up by a pulling mechanism to grow the semiconductor single crystal. In the device
A dopant supply device including a storage chamber containing a sublimable dopant, and a supply pipe for guiding the sublimated dopant to the melt when the dopant in the storage chamber is sublimated;
Heating means for heating the dopant in the accommodation chamber of the dopant supply device;
And a control means for controlling the amount of heating by the heating means so that the dopant is sublimated at a desired sublimation rate.

The second invention is the first invention,
The dopant supply device is characterized in that it is disposed at a position that does not interfere with the semiconductor single crystal and the pulling mechanism.

The third invention is the first invention or the second invention,
The dopant supply device is disposed at a position where the supply pipe is not immersed in the melt,
The sublimated dopant is blown onto the melt from the supply pipe to guide the sublimated dopant into the melt.

4th invention is 1st invention or 2nd invention or 3rd invention,
The control means feeds back the actual sublimation rate of the dopant during the dopant supply,
The heating amount is controlled so that the actual sublimation speed matches the target sublimation speed.

The fifth invention is the first invention, the second invention or the third invention,
The said control means controls the heating amount in this batch according to the sublimation speed and heating amount in the last batch.

The sixth invention is the first invention, the second invention or the third invention,
A relationship between the sublimation speed and the heating amount is obtained in advance, and the control means controls the heating amount according to the previously obtained relationship.

The seventh invention
In the method for producing a semiconductor single crystal, the dopant is supplied to the melt stored in the crucible in the furnace, and the semiconductor single crystal to which the dopant is added from the melt is pulled to grow the semiconductor single crystal.
The sublimable dopant is heated by a heating means to be sublimated at a desired sublimation rate, and the sublimated dopant is led to the melt.

In an eighth aspect based on the seventh aspect,
It is characterized in that the sublimated dopant is introduced into the melt while pulling up the semiconductor single crystal.

According to the first invention, as shown in FIG. 1, a dopant supply device 20 including a storage chamber 21 and a supply pipe 22 is provided. In the storage chamber 21, a sublimable dopant 23 is stored.

The supply pipe 22 guides the sublimated dopant 23 to the melt 5 when the dopant 23 in the storage chamber 21 is sublimated. The heating means 30 heats the dopant 23 in the accommodation chamber 21 of the dopant supply device 20. The control means 40 controls the heating amount by the heating means 30 so that the dopant 23 is sublimated at a desired sublimation rate.

For this reason, the heating amount by the heating means 30 is controlled, and the dopant 23 in the storage chamber 21 is sublimated at a desired sublimation rate. When the dopant 23 in the storage chamber 21 is sublimated, the sublimated dopant 23 is guided to the melt 5 through the supply pipe 22 and is introduced into the melt 5.

According to the present invention, not the radiant heat from the melt 5 but the heat adjusted by the heating means 30 and controlled by the control means 40 is given to the dopant 23 and the dopant 23 is sublimated. Therefore, unlike sublimation due to radiant heat, it is not affected by changes over time in the furnace components (hot zones). This makes it possible to control the sublimation speed very accurately. Therefore, since it becomes possible to apply a stable and optimum amount of heat to the dopant 23 without any variation, the sublimation rate is optimized, the efficiency of introducing the dopant into the melt 5 is maximized, and the dopant concentration and resistance of the silicon single crystal are maximized. The value can be accurately controlled to a desired value.

Also, as described above, a low resistivity N ++ by adding a high concentration of dopant to a silicon single crystal.
When pulling and growing a single-type silicon crystal, the crystal is likely to collapse. However, according to the present invention, the sublimation rate of a sublimable dopant such as arsenic As or phosphorus P that gives N-type electrical characteristics to the silicon single crystal. Therefore, it is possible to accurately control the dopant concentration in the silicon single crystal, so that the crystal can be accurately adjusted so as not to cause crystal collapse. In this specification, “low resistivity N ++ type silicon single crystal” means 0.01
An N-type silicon single crystal having a specific resistance value smaller than Ω · cm is assumed.

In the second invention, as shown in FIG. 1, the dopant supply device 20 is disposed at a position where it does not interfere with the semiconductor single crystal 6 and the pulling mechanism 4. This makes it possible to guide the sublimated dopant 23 to the melt 5 while pulling up the semiconductor single crystal 6, and to perform doping during the pulling with extremely high accuracy when performing additional doping.

In the third invention, the dopant supply device 20 is arranged at a position where the supply pipe 22 is not immersed in the melt 5, and the sublimated dopant 23 is sprayed from the supply pipe 22 onto the melt 5.
The sublimated dopant 23 is guided to the melt 5. According to the third invention, the dopant 23 is introduced into the melt 5 by the above-mentioned spraying method.

In the fourth invention, as shown in FIG. 1, the control means 40 controls the dopant 2 during the dopant supply.
3 is fed back, and the heating amount is controlled so that the actual sublimation speed matches the target sublimation speed.

In the fifth invention, as shown in FIG. 3, the control means 40 controls the heating amount in the current batch according to the sublimation speed and the heating amount in the previous batch.

In the sixth invention, as shown in FIG. 4, the relationship between the sublimation speed and the heating amount is obtained in advance, and the control means 40 controls the heating amount according to this previously obtained relationship.

The seventh invention is a method invention corresponding to the device invention of the first invention. The eighth invention is the second invention.
It is a method invention corresponding to the device invention of the invention.

  Hereinafter, an apparatus according to an embodiment will be described with reference to the drawings.

(First embodiment)
FIG. 1 is a side view of the configuration of the apparatus according to the first embodiment.

As shown in FIG. 1, a single crystal pulling apparatus 1 of the first embodiment includes a CZ furnace (chamber) 2 as a single crystal pulling vessel.

In the CZ furnace 2, a crucible 3 for melting a polycrystalline silicon (Si) raw material and storing it as a melt 5 is provided. The crucible 3 is made of quartz, for example. Around the crucible 3,
A heater 9 for heating and melting the raw material in the crucible 3 is provided.

  A heat insulating cylinder 13 is provided between the heater 9 and the inner wall of the CZ furnace 2.

A pulling mechanism 4 is provided above the crucible 3. The pulling mechanism 4 includes a pulling cable 4a and a seed crystal holder 4b at the tip of the pulling cable 4a. The seed crystal is gripped by the seed crystal holder 4b.

The raw material is heated and melted in the crucible 3. When the melting is stabilized, the pulling mechanism 4 operates and the silicon single crystal (silicon single crystal ingot) 6 is pulled from the melt 5 by the CZ method. That is, the pulling cable 4 a is lowered and the seed crystal held by the seed crystal holder 4 b at the tip of the pulling cable 4 a is immersed in the melt 5. After the seed crystal is adjusted to the melt 5, the pulling cable 4a rises. As the seed crystal held by the seed crystal holder 4b rises, the silicon single crystal 6 grows. When pulling up, the crucible 3 is rotated by the rotary shaft 10. The pulling cable 4a of the pulling mechanism 4 rotates in the opposite direction or the same direction as the rotating shaft 10. Further, the rotary shaft 10 can be driven in the vertical direction, and the crucible 3 can be moved up and down to be positioned at an arbitrary upward position.

By shutting off the outside air from the CZ furnace 2, the inside of the furnace 2 is maintained in a vacuum (for example, about several tens of Torr). That is, argon gas 7 as an inert gas is supplied to the CZ furnace 2 and is exhausted from the exhaust port of the CZ furnace 2 by a pump. Thereby, the inside of the furnace 2 is depressurized to a predetermined pressure.

  Various evaporants are generated in the CZ furnace 2 during the single crystal pulling process (one batch).

Therefore, the argon gas 7 is supplied to the CZ furnace 2 and exhausted together with the evaporated substance outside the CZ furnace 2 to remove the evaporated substance from the CZ furnace 2 and clean it. The supply flow rate of the argon gas 7 is set for each process in one batch.

As the silicon single crystal 6 is pulled up, the melt 5 decreases. As the melt 5 decreases, the area of contact between the melt 5 and the crucible 3 changes, and the amount of oxygen dissolved from the crucible 3 changes. This change affects the oxygen concentration distribution in the pulled silicon single crystal 6.

A heat shielding plate 8 (gas rectifying cylinder) is provided above the crucible 3 and around the silicon single crystal 6. The heat shielding plate 8 guides an argon gas 7 as a carrier gas supplied from above into the CZ furnace 2 to the center of the melt surface 5a, and further passes through the melt surface 5a so that the peripheral portion of the melt surface 5a. Lead to. And the argon gas 7 together with the gas evaporated from the melt 5,
It is discharged from an exhaust port provided in the lower part of the CZ furnace 2. For this reason, the gas flow rate on the liquid surface can be stabilized, and the oxygen evaporated from the melt 5 can be maintained in a stable state.

Further, the heat shielding plate 8 is composed of a seed crystal and a silicon single crystal 6 grown by the seed crystal.
Heat insulation and shielding are performed from radiant heat generated in high-temperature parts such as the crucible 3, the melt 5 and the heater 9. Further, the heat shield plate 8 is formed of impurities (for example, silicon oxide) generated in the silicon single crystal 6 in the furnace.
And the like to prevent the single crystal growth from being hindered. The lower end of the heat shielding plate 8 and the melt surface 5a
The distance D can be adjusted by raising and lowering the rotary shaft 10 and changing the vertical position of the crucible 3. Further, the distance D may be adjusted by moving the heat shielding plate 8 in the vertical direction by the lifting device.

Next, the configuration of the dopant supply apparatus of the apparatus of this embodiment will be described.

In this embodiment, arsenic As or phosphorus P is added to the silicon single crystal 6 as an N-type dopant (impurity) in order to give the silicon single crystal 6 N-type electrical characteristics. These dopants arsenic As and phosphorus P are sublimable dopants, and sublimate from the solid phase to the gas phase at a relatively low temperature.

As shown in FIG. 1, the dopant supply apparatus 20 includes a storage chamber 21, a supply pipe 22, a carrier gas introduction pipe 24, and a flow rate adjustment apparatus 25. In the storage chamber 21, a sublimable dopant 23 is stored. The supply pipe 22 communicates with the storage chamber 21, and guides the sublimated dopant 23 to the melt 5 when the dopant 23 in the storage chamber 21 is sublimated. The introduction pipe 24 is
A carrier gas 17 for transporting dopants, which is in communication with the storage chamber 21 and is supplied from a gas supply source (not shown), is introduced into the storage chamber 21. The carrier gas 17 is a sublimated dopant 2
3 is prevented from staying in the storage chamber 21, and the sublimated dopant 23 is efficiently guided to the melt 5 through the supply pipe 22.

The accommodation chamber 21, the supply pipe 22, and the carrier gas introduction pipe 24 of the dopant supply device 20 are made of, for example, quartz.

The flow rate adjusting device 25 passes through the introduction pipe 24 and is introduced into the storage chamber 21, and the supply pipe 22 is connected to the melt 5
The flow rate (mass flow rate) of the carrier gas 17 heading toward is adjusted. The flow rate is adjusted by adjusting the opening area of the valve. The carrier gas 17 is an inert gas such as argon gas.

FIG. 2 is a cross-sectional view taken along line AA of the storage chamber 21 of the dopant supply apparatus 20 shown in FIG.

The heater 30 as a heating means is formed in an annular shape so as to surround the housing chamber 21, and heats the dopant 23 in the housing chamber 21. As the heater 30, for example, a resistance heating type heater is used.

The storage chamber 21 is provided with a load cell 26 as a scale for detecting the weight of the dopant 23. The sublimation speed of the dopant 23 can be captured as a change in the weight of the dopant 23 in the storage chamber 21 that changes as the dopant 23 evaporates. For this reason, the sublimation speed is measured from the detection result of the load cell 26.

The controller 40 as a control means controls the heating amount by the heater 30 so that the dopant 23 is sublimated at a desired sublimation speed.

While the sublimated dopant 23 is supplied to the melt 5, the controller 40 monitors the weight of the dopant 23 in the storage chamber 21 detected by the load cell 26, and the amount of change in the dopant weight is actually measured for the dopant 23. The sublimation speed of the heater 30 is fed back, and the electric power applied to the heater 30 is adjusted so that the actual sublimation speed fed back matches the target sublimation speed to control the amount of dopant heating by the heater 30, and the flow rate adjustment device 25 The flow rate of the carrier gas 17 is controlled by adjusting the opening area of the valve. Control is performed so that the power applied to the heater 30 is reduced and the flow rate of the carrier gas 17 is reduced as the weight change of the dopant 23 in the storage chamber 21 is increased. The flow rate of the carrier gas 17 may be maintained at a constant value.

As shown in FIG. 1, the dopant supply device 20 includes a silicon single crystal 6 and a pulling mechanism 4.
It is arranged at a position where it does not interfere with. For this reason, it is possible to guide the sublimated dopant 23 to the melt 5 while pulling up the silicon single crystal 6.

The dopant supply device 20 is disposed at a position where the supply pipe 22 is not immersed in the melt 5.

For this reason, the sublimated dopant 23 is sprayed from the supply pipe 22 onto the melt 5.
The sublimated dopant 23 is guided to the melt 5. That is, in this embodiment, the dopant 23 is introduced into the melt 5 by the above-described spraying method.

In the CZ furnace 2, the dopant supply device 20 is configured so that the dopant 23 in the storage chamber 21 is not affected by radiant heat from the melt 5 or the like, and the dopant 23 is blown from the supply pipe 22 to the melt 5. It arrange | positions in the position where the dopant injection | throwing-in efficiency in the melt 5 becomes the maximum. The distance between the open end 22a of the supply pipe 22 and the melt 5 is desirably 10 mm or less.

Hereinafter, the control content of the dopant supply amount from the growth start to the growth end of the silicon single crystal 6 will be described.

(Initial doping into melt 5)
In the present embodiment, it is assumed that, for example, a dopant 23 is added to the silicon single crystal 6 in a high concentration to grow a low resistivity N ++ type silicon single crystal.

When dopant 23 is added to silicon single crystal 6 at a high concentration and an N ++ type silicon single crystal having a low resistivity is to be pulled and grown, a large amount of dopant 2 necessary for the high concentration is obtained.
It has been clarified by the present inventors that when the crystal is pulled up after 3 is introduced into the melt 5, the crystal is liable to collapse. In order not to cause crystal collapse, the dopant 23 is added at a low concentration or the dopant 23 is not added until the first half of the straight body portion of the silicon single crystal 6 is formed. After the first half of the straight body of the silicon single crystal 6 is formed,
It has been clarified by the present inventor that the dopant may be supplied to the melt so that the dopant 23 is added at a desired high concentration. This is considered to be because abnormal growth occurred due to local variations in dopant concentration in the melt 5 by introducing a large amount of dopant 23 into the melt 5 before crystal growth.

Therefore, in this embodiment, a low concentration dopant 23 is added to the melt 5 in advance before the silicon single crystal 6 is pulled up. The addition method of the dopant 23 to the melt 5 performed before the silicon single crystal 6 is pulled may be a conventional addition method that does not use the dopant supply device 20 of the present embodiment, and the dopant supply device of the present embodiment. 20 may be used.

Here, the low concentration means that the concentration of the dopant 23 in the silicon single crystal 6 is 1.6E19 atoms /
The concentration is equal to or lower than cm 3, and the specific resistance value of the silicon single crystal 6 is equal to or lower than 4 mΩ-cm.

In this way, the melt 5 is doped with the low-concentration dopant 23, and the silicon single crystal 6
Is pulled, the dopant concentration until the first half of the straight body portion of the silicon single crystal 6 is formed becomes low.

(Second half doping to melt 5)
When the first half of the straight body portion of the silicon single crystal 6 is formed, it is melted by using the dopant supply device 20 of this embodiment so that the dopant 23 is added at a desired high concentration thereafter. The dopant 23 sublimated in the liquid 5 is further doped.

The controller 40 starts control of the heater 30 and the flow rate adjusting device 25 from the middle of the pulling so that the dopant 23 is additionally doped into the melt 5 from the middle of the pulling of the silicon single crystal 6.

When a power command is given to the heater 30 from the controller 40, the heater 30 is supplied with power according to the power command and generates heat. When the heater 30 generates heat, the dopant 23 in the storage chamber 21 absorbs heat, and the dopant 23 in the storage chamber 21 is sublimated and evaporated.

When a flow rate command is given from the controller 40 to the flow rate adjusting device 25, the carrier gas 17
Flows from the introduction pipe 24 through the storage chamber 21 through the supply pipe 22 at a flow rate corresponding to the flow rate command, and the supply pipe 2
A carrier gas 17 is sprayed from 2 toward the melt 5.

For this reason, the gaseous dopant 23 sublimated in the storage chamber 21 is conveyed by the carrier gas 17 and sprayed from the supply pipe 22 toward the melt, and the dopant 23 is introduced into the melt 5.

While the dopant 23 is being supplied to the melt 5, the controller 40 loads the load cell 26.
The weight of the dopant 23 detected in step S1 is monitored, the amount of change in the dopant weight is fed back as the actual sublimation speed of the dopant 23, and applied to the heater 30 so that the actual sublimation speed fed back matches the target sublimation speed. The flow rate of the carrier gas 17 is controlled by adjusting the electric power to be controlled to control the dopant heating amount by the heater 30 and adjusting the opening area of the valve of the flow rate adjusting device 25.

In this way, the dopant 23 is sublimated at a desired sublimation rate, and a desired concentration of the dopant 23 is further doped into the melt 5. Thereby, each part of the crystal after the first half part of the straight body part of the silicon single crystal 6 is formed is in a state in which the dopant 23 is added at a desired high concentration.

As described above, according to this embodiment, not the radiant heat from the melt 5 or the like, but the heat adjusted by the heater 30 and controlled by the controller 40 is given to the dopant 23 in the storage chamber 21, and the dopant 23 is sublimated. To do. Therefore, unlike sublimation due to radiant heat, it is not affected by changes over time in the furnace components (hot zones). This makes it possible to control the sublimation speed very accurately. Therefore, the optimum amount of heat that is always stable without variation is provided.
3, the sublimation rate is optimized, the efficiency of introducing the dopant into the melt 5 is maximized, and the dopant concentration and resistance value of the silicon single crystal 6 are set to a desired high concentration,
It becomes possible to accurately control the low resistance value.

Further, when the N ++ type silicon single crystal 6 having a low resistivity is added to the silicon single crystal 6 at a high concentration to cause the crystal to break up, the crystal is likely to collapse.
It is possible to accurately control the concentration of the dopant in the silicon single crystal 6 by accurately controlling the sublimation rate of the sublimable dopant 23 such as arsenic As and phosphorus P that gives the silicon single crystal 6 N-type electrical characteristics. Therefore, it can be adjusted accurately so as not to cause crystal collapse.

Further, the dopant supply device 20 is arranged at a position where it does not interfere with the silicon single crystal 6 and the pulling mechanism 4. This makes it possible to guide the sublimated dopant 23 to the melt 5 while pulling up the silicon single crystal 6, and to perform doping during pulling with extremely high accuracy when performing additional doping.

In this embodiment, the dopant supply device 20 is disposed at a position where the supply pipe 22 is not immersed in the melt 5, and the sublimated dopant 23 is sprayed from the supply pipe 22 onto the melt 5, thereby being sublimated. The dopant 23 is guided to the melt 5. Such a spraying method is less likely to cause crystal collapse than a dipping method and can stably grow a single crystal. This is because when the supply pipe 22 is immersed in the melt 5, liquid vibration occurs in the melt 5, the liquid temperature decreases, or a change in the convection of the melt 5 occurs. This is thought to be because it becomes difficult to inhibit the single crystallization rate of the crystal and to stably grow the single crystal. Therefore, the spraying method is suitable for application when pulling and growing a high-concentration, low-resistivity N ++ type silicon single crystal 6 that is prone to crystal collapse in the first place as compared with the dipping method.

(Second embodiment)
In the first embodiment described above, the actual sublimation rate of the dopant 23 (the amount of change in the weight of the dopant 23) is fed back during the supply of the dopant, and the heating amount by the heater 30 so that the actual sublimation rate matches the target sublimation rate. However, this control is only an example, and another control device as shown in FIG. 3 may be used.

Hereinafter, description of the same components as those in the first embodiment will be omitted as appropriate, and different components will be described.

In the control device shown in FIG. 3, the controller 40 adjusts the heating amount in the current batch according to the sublimation speed and the heating amount in the previous batch.

That is, an experiment is performed in advance, and the relationship between the electric power (heating amount) applied to the heater 30 and the sublimation speed is stored in the storage device 41.

The controller 40 reads out the data stored in the storage device 41 and gives a power command to the heater 30 so as to obtain a power corresponding to a desired sublimation speed for one batch, and adjusts the power applied to the heater 30. To do. Note that the flow rate of the carrier gas 17 is maintained at a constant value during one batch. During one batch, the weight of dopant 23 is monitored at load cell 26,
The actual sublimation speed for one batch is stored in the storage device 42, and the actual power (heating amount) applied to the heater 30 is stored in the storage device 42.

In the next batch, the controller 40 reads the actual sublimation speed and the actual power (heating amount) in the previous batch stored in the storage device 42, and these and the sublimation speed and power (heating) stored in the storage device 41. The power applied to the heater 30 is corrected by comparing the corresponding relationship with the amount), and the corrected power is applied to the heater 30. If the actual sublimation speed in the current batch is faster than the actual sublimation speed in the previous batch, the electric power applied to the heater 30 is decreased accordingly.

In this way, the dopant 23 is sublimated at a desired sublimation rate, and a desired concentration of the dopant 23 is further doped into the melt 5.

(Third embodiment)
In the second embodiment described above, the actual sublimation speed of the previous batch is fed back to the current batch to control the power applied to the heater 30, but the sublimation speed and the heater power value obtained in advance in the experiment are controlled. May be controlled so that a fixed electric power corresponding to a desired sublimation speed is applied to the heater 30.

Hereinafter, the same components as those in the first embodiment and the second embodiment will not be described as appropriate, and different components will be described.

In the control device shown in FIG. 4, the controller 40 obtains the relationship between the sublimation speed and the heating amount (electric power) in advance, and controls the heating amount (electric power) according to the previously obtained relationship.

That is, an experiment is performed in advance, and the relationship between the electric power (heating amount) applied to the heater 30 and the sublimation speed is stored in the storage device 41.

The controller 40 reads out the data stored in the storage device 41 and gives a power command to the heater 30 so as to obtain a power corresponding to a desired sublimation speed for one batch, and adjusts the power applied to the heater 30. To do. Note that the flow rate of the carrier gas 17 is maintained at a constant value during one batch.

In this way, the dopant 23 is sublimated at a desired sublimation rate, and a desired concentration of the dopant 23 is further doped into the melt 5.

In each of the above-described embodiments, the dopant 23 is supplied to the melt 5 by a spraying method, but the dopant 23 may be supplied to the melt 5 using an immersion method. Even when the dipping method is used, the accommodation chamber 21 needs to be arranged at a position that is not easily affected by the radiant heat from the melt 5.

Further, in the present embodiment, the dopant supply device 20 is disposed at a position where it does not interfere with the silicon single crystal 6 and the pulling mechanism 4, and the sublimated dopant 23 is added while pulling up the silicon single crystal 6 when performing additional doping. Although it guide | induces to the melt 5, you may arrange | position the dopant supply apparatus 20 in the position where the silicon single crystal 6 and the pulling mechanism 4 are arrange | positioned.

For example, before the crystal growth, the dopant supply device 20 is arranged at the place where the pulling mechanism 4 is arranged, and the dopant 23 is introduced into the melt 5 by the dopant supply device 20.
Thereafter, it is possible to remove the dopant supply device 20 and place the pulling mechanism 4 at the place where the dopant supply device 20 is arranged to pull up and grow the silicon single crystal 6.

Further, in the present embodiment, silicon is assumed as the semiconductor element assuming that the silicon single crystal 6 is pulled up, but the semiconductor single crystal to be pulled up may be a semiconductor single crystal other than the silicon single crystal.

FIG. 1 is a side view showing the apparatus configuration of the first embodiment. 2 is a cross-sectional view showing a cross section of the dopant supply apparatus shown in FIG. FIG. 3 is a side view showing the apparatus configuration of the second embodiment. FIG. 4 is a side view showing a device configuration of the third embodiment.

Explanation of symbols

1 Single crystal pulling device, 2 CZ furnace, 3 crucible, 5 melt, 20 dopant supply device, 23 dopant, 30 heater, 40 controller

Claims (6)

In a semiconductor single crystal manufacturing apparatus in which a dopant is supplied to a melt stored in a crucible in a furnace, and a semiconductor single crystal to which a dopant is added from the melt is pulled by a pulling mechanism to grow a semiconductor single crystal.
A dopant supply device including a storage chamber containing a sublimable dopant, and a supply pipe for guiding the sublimated dopant to the melt when the dopant in the storage chamber is sublimated;
Heating means for heating the dopant in the accommodation chamber of the dopant supply device;
A control means for controlling the heating amount by the heating means so that the dopant is sublimated at a desired sublimation rate,
The control means feeds back the actual sublimation rate of the dopant during the supply of the dopant, and controls the heating amount so that the actual sublimation rate matches the target sublimation rate. 2. The apparatus for producing a semiconductor single crystal according to claim 1, wherein the dopant supply device is arranged at a position where the dopant supply device does not interfere with the semiconductor single crystal and the pulling mechanism. The dopant supply device is disposed at a position where the supply pipe is not immersed in the melt,
The apparatus for producing a semiconductor single crystal according to claim 1 or 2, wherein the sublimated dopant is guided to the melt by spraying the sublimated dopant from the supply pipe onto the melt. In a semiconductor single crystal manufacturing apparatus in which a dopant is supplied to a melt stored in a crucible in a furnace, and a semiconductor single crystal to which a dopant is added from the melt is pulled by a pulling mechanism to grow a semiconductor single crystal.
A dopant supply device including a storage chamber containing a sublimable dopant, and a supply pipe for guiding the sublimated dopant to the melt when the dopant in the storage chamber is sublimated;
Heating means for heating the dopant in the accommodation chamber of the dopant supply device;
Control means for controlling the heating amount by the heating means so that the dopant is sublimated at a desired sublimation rate,
Find the correspondence between the desired sublimation speed and heating amount in advance,
For each batch, measure the actual sublimation rate and the actual heating amount,
When obtaining the desired sublimation speed in the current batch, the control means compares the sublimation speed and the heating amount measured in the previous batch with the correspondence relationship between the desired sublimation speed and the heating amount obtained in advance. Thus, the semiconductor single crystal manufacturing apparatus is characterized by correcting the heating amount corresponding to the desired sublimation rate in the current batch and controlling to obtain the corrected heating amount. 5. The apparatus for producing a semiconductor single crystal according to claim 4, wherein the dopant supply device is arranged at a position that does not interfere with the semiconductor single crystal and the pulling mechanism. The dopant supply device is disposed at a position where the supply pipe is not immersed in the melt, and the sublimated dopant is blown to the melt from the supply pipe to guide the sublimated dopant to the melt. The apparatus for producing a semiconductor single crystal according to claim 4 or 5.

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