KR20140018671A - Method for manufacturing silicon single crystal ingot - Google Patents

Abstract

A method for growing silicon single crystal according to an embodiment of the present invention comprises the steps of: growing silicon single crystal until a solidification rate, which is the rate of polycrystalline silicon solidifying into a single crystal form, is 50%; adjusting the pressure and the argon gas flow ratio in a chamber since the solidification rate is 50% until the solidification rate is 60% by reducing a ratio value which is defined by dividing the pressure value by the argon gas flow; and conducting a tail process after further reducing the pressure or increasing further the argon gas flow compared with the ratio value at the end of the grown ingot after the single crystal growth. The method for growing silicon single crystal including a highly volatile dopant according to another embodiment of the present invention comprises the steps of: growing silicon single crystal until a solidification rate, which is the rate of polycrystalline silicon solidifying into a single crystal form, is 50%; reducing the strength of a magnetic field applied to silicon melt since the solidification rate is 50% until the solidification rate is 60%; and conducting a tail process after further reducing the strength of the magnetic fields compared with the strength of the magnetic field at the end of the grown ingot after single crystal growth. [Reference numerals] (AA) Example; (BB) Comparative example; (CC) Solidification rate (%)

Description

Method for manufacturing silicon single crystal ingot

The present invention relates to a method of growing a silicon single crystal.

      In general, a process for manufacturing a wafer for manufacturing a semiconductor device includes a cutting process for slicing silicon ingots, an edge grinding process for rounding the edges of the sliced wafer, and a rough surface of the wafer due to the cutting process. Lapping process to flatten, edge grinding or cleaning process to remove various contaminants including particles attached to wafer surface during lapping process, surface grinding process to secure the shape and surface suitable for post process and edge polishing process to wafer edge It includes.

      Meanwhile, according to the related art, a material having high electron mobility, for example, a low melting point dopant, is introduced as a dopant during single crystal growth in order to improve electron mobility. In general, materials with high electron mobility are generally highly volatile, and as a result, the volatilization rate is accelerated as the concentration of the dopant in the melt decreases, especially as the amount of melt reduced by the length of growth into a single crystal due to the characteristics of single crystal growth. This reduces the absolute amount of oxygen that enters the growing single crystal because it readily bonds with oxygen and leaves the melt in oxide form.

      Recently, as the demand for power devices increases, the demand for high-volatile silicon single crystals such as antimony, red phosphorus, and arsenic is increasing. However, these products are characterized by low melting point and high volatility to grow silicon single crystals by injecting more dopant than the concentration required in the actual silicon melt. Silicon grown in this way, a process for manufacturing a wafer for manufacturing a semiconductor device generally includes a cutting process for slicing silicon ingots, an edge grinding process for rounding the edges of the sliced wafer, and a wafer due to the cutting process. Lapping process to planarize rough surface of wafer, edge grinding or cleaning process to remove various contaminants including particles attached to wafer surface during lapping process, surface grinding process to secure shape and surface suitable for post process and wafer edge Edge polishing process.

      Meanwhile, according to the related art, a material having high electron mobility, for example, a low melting point dopant, is introduced as a dopant during single crystal growth in order to improve electron mobility. In general, materials with high electron mobility are generally highly volatile, and as a result, the volatilization rate is accelerated as the concentration of the dopant in the melt decreases, especially as the amount of melt reduced by the length of growth into a single crystal due to the characteristics of single crystal growth. As a result, single crystals gradually increase in concentration toward the latter part of the body, causing polycrystallization.

      Referring to Table 1, it can be seen that as the growth of silicon ingot grows to the second half, the compositional subcooling phenomenon increases, and the rate of growth of silicon ingots into polycrystals increases. Here, the solidification rate represents the rate at which the initially introduced polycrystalline silicon solidifies into a single crystal, and can be said to arbitrarily represent the single crystal length of the grown silicon ingot.

   Polycrystallization Rate (S / L%)    20% solidification rate  5.3%    40% solidification rate  0.0%    60% solidification rate 10.5%    80% solidification rate 15.8%     Tail 15.8%

In addition, as the demand for silicon single crystals having a lower specific resistance, that is, a higher concentration has recently occurred, there is a great difficulty in manufacturing them.

      Referring to Japanese Laid-Open Patent Publication No. 2011-057476, while trying to overcome the above problems by controlling the interface height of the silicon melt, the silicon melt interface height is not confirmed in the actual process of growing the silicon single crystal, the vertical sample after the silicon single crystal growth is completed There is a problem that it is difficult to apply directly to the process because the actual confirmation is possible only through the process of sampling, its heat treatment, X-ray transmission and the like.

      In addition, in the case of setting the ratio of pressure and argon (Ar) gas to a value and maintaining it constant, as the silicon ingot grows, it is not possible to completely control the growth completion point and polycrystallization in the tail process. There is a problem.

      Referring to Table 2, when the ratio of the pressure and the argon gas flow rate is made constant, it is shown that the yield of single crystal decreases as the solidification rate increases.

P-value Higher rate (%) Monocrystalline yield 2 20.0 ◎ 2 40.0 ◎ 2 60.0 ○ 2 80.0 × 2 Tail ×

◎: Good ○: Normal ×: Poor

The embodiment controls polycrystallization in the ingot end and tail process during the single crystal growth, especially in the case of using a high volatility dopant, the solidification rate growing at the latter half of the length of the single crystal is 60% or more. An object of the present invention is to provide a method for producing a single crystal ingot capable of increasing the yield of the single crystal.

In the single crystal ingot growth method according to the embodiment, in the method of manufacturing a high volatility silicon single crystal, the pressure and argon gas flow rate values in the chamber are changed so that the ingot tip and tail process of ingot having a solidification rate of 60% or more does not occur. Alternatively, it is possible to grow a high yield of high volatility silicon single crystal by changing the strength of the magnetic field. In addition, the silicon single crystal growth yield can be improved by simultaneously changing the pressure / argon gas flow rate ratio value in the chamber and the strength of the magnetic field.

According to the single crystal ingot manufacturing method according to the embodiment, in particular, it is possible to control the polycrystallization of the silicon ingot corresponding to 60% or more of the solidification rate (solidification) corresponding to the latter half of the length of the single crystal.

The example suggests a ratio of the pressure to the argon (Ar) gas flow rate and can modify the polycrystallization of the silicon ingot through this change.

The embodiment can control the polycrystallization of the silicon ingot by changing the strength of the magnetic field to a process condition of the initial, mid growth level of the silicon ingot at a solidification rate of 60% or more.

In addition, in the tail process at the end of growth, the ratio of pressure and argon (Ar) gas flow rate is changed, or the strength of the magnetic field is changed to prevent the potential from rising in the silicon ingot body portion, thereby producing high quality silicon single crystal. You can grow.

1 is a diagram illustrating growth after a solidification rate of 50% of a silicon single crystal ingot.
2 is a flow chart of a silicon single crystal growth method according to the embodiment.
Figure 3 is an exemplary view of changing the ratio of the pressure and argon gas flow rate at a solidification rate of 50% or more in the single crystal ingot manufacturing method according to the embodiment.
4 is a flow chart of a silicon single crystal growth method according to another embodiment.
Figure 5 is an exemplary view of changing the intensity of the magnetic field at a solidification rate of 60% or more in the single crystal ingot manufacturing method according to another embodiment.

Hereinafter, the present embodiment will be described in detail with reference to the accompanying drawings. It should be understood, however, that the scope of the inventive concept of the present embodiment can be determined from the matters disclosed in the present embodiment, and the spirit of the present invention possessed by the present embodiment is not limited to the embodiments in which addition, Variations. In the following description, the word " comprising " does not exclude the presence of other elements or steps than those listed.

1 is a cross-sectional view of a silicon single crystal growth furnace capable of implementing the silicon single crystal growth method according to the present invention. First, the single crystal growth apparatus 100 to which the single crystal manufacturing method according to the embodiment is applied will be described.

      The silicon single crystal growth apparatus 100 according to the embodiment may include a chamber 110, a crucible 120, a heater 130, a pulling means 150, and the like. For example, the single crystal growth apparatus 100 according to the embodiment is provided in the chamber 110, the inside of the chamber 110, the crucible 120 containing the silicon melt, and the inside of the chamber 110. It is provided in, and may include a pulling means 150 coupled to the heater 130 and the seed crystal 152 to heat the crucible 120. The chamber 110 provides a space in which predetermined processes are performed to grow a single crystal ingot for a silicon wafer used as an electronic component material such as a semiconductor.

      The radiant heat insulator 140 may be installed on the inner wall of the chamber 110 to prevent heat of the heater 130 from being discharged to the side wall of the chamber 110.

      The embodiment may adjust various factors such as pressure conditions inside the rotation of the quartz crucible 120 to control the oxygen concentration during silicon single crystal growth. For example, in order to control the oxygen concentration, an argon gas or the like may be injected into the chamber 110 of the silicon single crystal growth apparatus and discharged downward.

      The crucible 120 is provided inside the chamber 110 to contain a silicon melt, and may be made of quartz. A crucible support (not shown) made of graphite may be provided outside the crucible 120 to support the crucible 120. The crucible support is fixedly installed on a rotating shaft (not shown), and the rotating shaft may be rotated by a driving means (not shown) so that the solid-liquid interface maintains the same height while rotating and elevating the crucible 120.

      The heater 130 may be provided inside the chamber 110 to heat the crucible 120. For example, the heater 130 may be formed in a cylindrical shape surrounding the crucible support. The heater 130 melts a high-purity polycrystalline silicon mass loaded in the crucible 120 into a silicon melt.

      As a manufacturing method for growing a silicon single crystal ingot of the embodiment, the Czochralsk (CZ) method of growing a crystal while immersing a seed crystal 152 which is a single crystal in a silicon melt and pulling it up slowly may be employed. have.

      According to this method, first, after a necking process of growing thin and long crystals from the seed crystals 152, a shouldering process of growing the crystals in the radial direction to a target diameter is performed. After the body growing process to grow into a crystal having a certain diameter, after the body growing by a certain length, a single crystal through a tail process to gradually reduce the diameter of the crystal and separate from the molten silicon The growth is over.

      The embodiment provides a method for producing a single crystal ingot capable of growing a high yield of single crystal without compositional subcooling at a high rate of 60% or more, which is the latter part of the process during single crystal growth, especially when using a highly volatile dopant during single crystal growth. I would like to. The solidification rate indicates the rate at which the initially introduced polycrystalline silicon solidifies into a single crystal, and can be said to arbitrarily indicate the single crystal length of the grown silicon ingot.

      The single crystal ingot manufacturing method according to the embodiment may use a low melting point high-volatile dopant, for example, antimony (Sb), red (Red Phosphorus), germanium (Ge), arsenic (As), etc., below a certain level The lower the resistivity, the lower the oxygen concentration.

      The reason is that as the single crystal grows with the segregation coefficient of these dopants of 1.0 or less, the melt decreases by the length, thereby increasing the concentration of the low melting dopant in the melt. The higher dopant concentration in the melt increases the amount of volatilization on the melt surface, which results in constitutional supercooling during growth, resulting in lower yield of the desired single crystal.

      Compositional supercooling does not occur when the following conditions are met.

  (Equation) T (liquid) / v> (T1-T3) / D

      Where D (diffusivity) is a fixed value that represents the properties of the material, (T1-T3) is the temperature difference from the interface at which solidification occurs, and v is the growth rate.

      In other words, v (growth rate) should be small in order for compositional subcooling not to occur, and (T1-T3) (temperature difference with an interface) becomes larger as it becomes advantageous. However, there is a limit to lowering the growth rate in order to actually grow a high volatile silicon single crystal, and to increase the temperature difference with the silicon melt interface also has a limit in terms of hot zone.

      Thus, this embodiment focuses on controlling polycrystallization in the latter part of the silicon ingot growth process, where the concentration of the ingot is increased.

      The P-value represents the ratio of the pressure to the argon gas, which is a value obtained by dividing the pressure by the argon gas flow rate, which will be described below as a P-value or a ratio value.

      Referring to Table 3, as the solidification rate is increased while changing the P-value or ratio value, the single crystal yield is shown.

P-value Higher rate (%) Silicon single crystal yield 1.5 40.0 ◎ 1.5 60.0 ◎ 1.5 80.0 ○ One 60.0 ◎ One 80.0 ◎ 0.5 60.0 ◎ 0.5 80.0 ◎

                  ◎: Good ○: Normal

       It can be seen that when the P-value is 1.5, the higher the solidification rate, that is, the lower the single crystal yield becomes as the second half of the silicon ingot grows.In the case where the P-value is controlled to 1 or less, the monocrystalline yield is 60% or more. It can always be confirmed that it is good.

      2, a flowchart of a silicon single crystal growth method according to an embodiment is shown. Referring to FIG. 3, in the single crystal ingot manufacturing method according to the embodiment, the ratio value of the pressure and argon gas flow rate is changed at a solidification rate of 60% or more.

      2 and 3, the silicon single crystal growth method according to the embodiment will be described. First, the silicon single crystal 160 is grown using the silicon single crystal furnace 100 (step S1). In this case, silicon single crystal growth may be performed using normal growth conditions as they are.

      The ratio of pressure / argon gas flow rate (P-value) is maintained at 2.0 at the beginning of the process, when the silicon single crystal grows to a certain degree, that is, when 50% of the silicon melt solidifies and grows into a single crystal. . Thereafter, a step of decreasing the ratio value of the pressure / argon gas flow rate is performed after 50% of the solidification rate of the silicon melt (step S2). Thereafter, the silicon single crystal is grown to 1.0 by the time when the solidification rate reaches 60% (step S3). That is, step S3 includes adjusting the ratio value when the solidification rate exceeds 60%, and the ratio value when the solidification rate is greater than 60% is a ratio value before the solidification rate is 50%. Decrease to 1/2.

      Reducing the P-value of the pressure / argon gas flow rate reduces the pressure inside the single crystal growth furnace, increases the flow rate of argon gas, or decreases the pressure and simultaneously increases the argon gas flow rate. It includes, but not limited to, the value of the pressure / argon gas ratio is defined as P-value, it can be any pressure value or the flow rate of argon gas satisfying the P-value. Thus, it is possible to define an optimal ratio of pressure / argon gas flow rates at which silicon single crystals can grow.

      The tail process is the point at which the silicon ingot is grown and has no relation to the quality of the ingot.However, in the latter process of the grown single crystal ingot, when the polycrystallization occurs in the silicon ingot tail portion, the dislocation becomes the center of the silicon ingot. As it propagates up to, it causes the yield of silicon single crystal to decrease. Therefore, the present embodiment proposes an embodiment in which the ratio value of the pressure / argon flow rate is changed not only in the latter part of silicon ingot growth but also in the tail process.

      Compared to the pressure / argon gas flow rate ratio (P-value) of the grown ingot end side, when the tail process was performed by further reducing the ratio value to 60% (step S4), the polycrystallization of the silicon ingot became It is less likely to occur, thereby increasing the yield of silicon single crystal.

      Reducing the P-value in the tail process also includes reducing the pressure in the chamber for growing single crystals, increasing the flow rate of argon gas, or simultaneously increasing the argon gas flow rate while reducing the pressure. Since the value of the pressure / argon gas ratio is defined as P-value, the present invention is not limited thereto, and may be any pressure value or the amount of argon gas satisfying the P-value.

      On the other hand, if the P-value is lowered to a level lower than 60%, as the argon gas (Ar) flow rate is increased, the volatilization of the dopant may be accelerated to produce the silicon ingot with the desired specific resistance band quality. Is generated.

      4, a flowchart of a silicon single crystal growth method according to another embodiment of the present invention.

      Referring to FIG. 5, in the method of manufacturing a single crystal ingot according to the embodiment, the intensity of the magnetic field is changed at a solidification rate of 60% or more.

      Application of a magnetic field to the silicon single crystal has the effect of controlling the amount of oxygen inflow to the silicon single crystal by suppressing convection of the silicon melt to reduce oxygen atoms eluted from the quartz crucible.

      In the present embodiment, in the high volatility single crystal growth process, as the intensity of the magnetic field increases, increasing the diffusion boundary at the silicon melt interface (Diffusion boundary) to play a role in suppressing the volatilization, according to the composition subcooling accordingly In order to prevent this from happening, reducing the strength of the magnetic field was applied in the second half of the silicon growth.

      Referring to FIGS. 4 and 5, the silicon single crystal growth method according to the embodiment will be described. First, the silicon single crystal 160 is grown using the silicon single crystal growth furnace 100 (step M1). In this case, silicon single crystal growth may be performed using normal growth conditions as they are.

      In the present embodiment, M-value is defined as representing the strength of the magnetic field applied to the silicon melt will be described. The single crystal is grown while maintaining the M-value at 100 at the beginning of the process, which is the point when 50% of the silicon melt solidifies and grows into a single crystal, and at the mid-solidification rate 50% (step M1). Then, when the silicon single crystal solidified by 50% or more, the M-value starts to decrease (step M2). The intensity of the magnetic field is reduced to 70% compared to the M1 stage until the late stage of solidification is 60% (step M3). That is, step M3 further includes adjusting the intensity of the magnetic field when the solidification rate exceeds 60%, and the intensity of the magnetic field when the intensity of the magnetic field is greater than 60% is 50%. It means to reduce to 70% of the strength of the magnetic field before reaching.

      Thereafter, compared to the M-value at the end of the grown single crystal ingot, when the tail process was further reduced to 80% of the M-value, the polycrystalline crystallization of the silicon ingot was less likely to increase the yield of the single crystal. This can be seen through.

      The two embodiments of the present disclosure provide pressure, argon gas flow rate, and magnetic field parameters that can maximize the growth conditions of the silicon single crystal by changing the ratio of the pressure / argon gas flow rate in the chamber or changing the strength of the magnetic field applied to the silicon melt. It is about how to find the optimal value for the parameter. Accordingly, the two embodiments can be executed independently, as well as changing the ratio value of the pressure / argon gas flow rate in the chamber as in the embodiment, while simultaneously changing the intensity of the magnetic field applied to the silicon melt as in the embodiment. It is also possible.

      According to the single crystal ingot manufacturing method according to the embodiment, in the case of using a highly volatile dopant, especially during the single crystal growth, by changing the pressure / argon gas flow rate value in accordance with the solidification rate (Solidification) of the silicon to avoid the compositional subcooling phenomenon Single crystal yield can be increased.

      According to the single crystal ingot manufacturing method according to the embodiment, the silicon single crystal yield can be increased by changing the strength of the magnetic field according to the solidification rate during the single crystal growth, in particular when using a high volatility dopant.

      In addition, the embodiment controls the ratio value of the pressure / argon gas flow rate and the magnetic field strength not only in the latter part of the growth of the silicon ingot but also in the tail process at the time when the growth is completed, so that the potential propagates in the body part of the silicon ingot. By preventing it, the yield of a silicon single crystal can be raised.

Although described above with reference to the embodiment, this is merely an example, not to limit the embodiment, those skilled in the art to which the embodiment belongs to the above examples within the scope without departing from the essential characteristics of the embodiment It will be appreciated that various modifications and applications are possible. For example, each component specifically shown in the embodiments can be modified and implemented. And differences relating to such modifications and applications will have to be construed as being included in the scope of the embodiments set forth in the appended claims.

Claims (10)

In the method for producing a silicon single crystal containing a high volatility dopant,
Growing a silicon single crystal until the rate of solidification, which is the rate at which the polycrystalline silicon solidifies into a single crystal, is 50%;
Adjusting the ratio of the pressure in the chamber and the argon gas flow rate from the time when the solidification rate is 50% or more to the time when the solidification rate becomes 60%, the value obtained by dividing the pressure by argon gas is defined as a ratio value, and the ratio value is decreased. Making a; and
After single crystal growth, further reducing the pressure or increasing the flow rate of the argon gas in contrast with the ratio value at the grown ingot end side and then performing a tail process;
Silicon single crystal ingot growth method comprising a.
The method of claim 1,
Reducing the ratio value from the time when the solidification rate is 50% or more to the time when the solidification rate becomes 60%, and then adjusting the ratio value when the solidification rate exceeds 60%,
And the ratio value when the solidification rate is greater than 60% is reduced to 1/2 of the ratio value before the solidification rate reaches 50%.
The method of claim 1,
The step of performing the tail process,
And the ratio value at the end side of the grown ingot is reduced to 60%.
3. The method according to claim 2 or 3,
Reducing the ratio value,
A method for growing a silicon single crystal, characterized by reducing the pressure in the chamber for growing the silicon single crystal.
3. The method according to claim 2 or 3,
Reducing the ratio value,
The silicon single crystal growth method of increasing the flow rate of the argon gas.
3. The method according to claim 2 or 3,
Reducing the ratio value,
Increasing the flow rate of the argon gas while reducing the pressure in the chamber for growing the silicon single crystal.
In the method for producing a silicon single crystal containing a high volatility dopant,
Growing a silicon single crystal until the rate of solidification, which is the rate at which the polycrystalline silicon solidifies into a single crystal, is 50%;
Reducing the intensity of the magnetic field applied to the silicon melt from 50% or more of solidification rate to 60% solidification rate; and
After single crystal growth, further reducing the strength of the magnetic field in comparison with the strength of the magnetic field at the grown ingot end side, and then performing a tail process;
Method of producing a single crystal of the silicon ingot comprising a.
8. The method of claim 7,
And reducing the strength of the magnetic field from the time when the solidification rate is 50% or more to the time when the solidification rate is 60%, and then adjusting the intensity of the magnetic field when the solidification rate exceeds 60%. and,
The strength of the magnetic field when the solidification rate is greater than 60% is reduced so as to be 70% of the strength of the magnetic field before the solidification rate reaches 50%.
8. The method of claim 7,
The step of performing the tail process,
And the strength of the magnetic field at the end side of the grown ingot is reduced to 80%.
In the method for producing a silicon single crystal containing a high volatility dopant,
Growing a silicon single crystal until the rate of solidification, which is the rate at which the polycrystalline silicon solidifies into a single crystal, is 50%;
Adjusting the ratio of the pressure in the chamber and the argon gas flow rate from the time when the solidification rate is 50% or more to the time when the solidification rate is 60%, the value obtained by dividing the pressure by the argon gas flow rate is defined as the ratio value, and the ratio value and Reducing the intensity of the magnetic field applied to the silicon melt; and
After the single crystal growth, further reducing the ratio value of the pressure and argon gas flow rate and the magnetic field relative to the ratio value and the strength of the magnetic field at the end side of the grown ingot, and then performing a tail process;
Method of producing a single crystal of the silicon ingot comprising a.

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