JP2013087008A - N-type silicon single crystal and method of manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an n-type silicon single crystal having little variation in resistivity, and to provide a method of manufacturing the same.SOLUTION: A method of manufacturing an n-type silicon single crystal has the following steps: step S1 in which a silicon melt to which phosphorus as a main dopant, a first sub dopant which is a p-type impurity and smaller in segregation coefficient than phosphorus, and a second sub dopant which is an n-type impurity and smaller in segregation coefficient than phosphorus have been added, is prepared; step S2 in which a silicon single crystal is grown from the silicon melt by a Czochralski method; and step S3 in which after growing a straight body part up to a prescribed length, a crucible is lowered, to thereby cut a silicon single crystal from the silicon melt.

Description

  The present invention relates to an n-type silicon single crystal and a method for producing the same, and more particularly to an n-type silicon single crystal produced by the Czochralski method and a method for producing the same.

  Silicon single crystals used as semiconductor substrates are mainly manufactured by the Czochralski method (CZ method). When producing an n-type silicon single crystal, a silicon melt to which phosphorus, arsenic or the like is added as a dopant is used as a raw material. Since the segregation coefficient of phosphorus or arsenic used as a dopant with respect to the silicon single crystal is smaller than 1, when the silicon single crystal is grown by the CZ method, the dopant concentration in the silicon melt increases. For this reason, the dopant concentration of the pulled silicon single crystal changes in the pulling axis direction, and as a result, the specific resistance of the silicon single crystal changes in the pulling axis direction, making it difficult to control the specific resistance.

  Regarding a method for controlling the specific resistance of an n-type silicon single crystal, for example, Japanese Patent Application Laid-Open No. 2004-307305 (Patent Document 1) describes a method for growing a phosphorus-doped n-type silicon single crystal grown by the CZ method. Yes. According to this method, an n-type silicon single crystal is grown using a raw material melt to which gallium, indium or aluminum as a sub-dopant is added in addition to phosphorus as a main dopant.

Japanese Patent Laid-Open No. 2004-307305

  In the method described in Patent Document 1, phosphorus is used as a main dopant added to the silicon melt, and gallium, indium, or aluminum having a segregation coefficient with respect to a silicon single crystal smaller than that of phosphorus is used as a sub-dopant. The segregation coefficient of these sub-dopants is one or more orders of magnitude smaller than the segregation coefficient of phosphorus as the main dopant. For this reason, as the n-type silicon single crystal is grown by the CZ method, the concentration of the sub-dopant into the silicon melt rapidly proceeds.

  As a result, the subdopant is rapidly taken into the silicon single crystal at a high solidification rate. Since the main dopant phosphorus is an n-type impurity and the sub-dopants gallium, indium and aluminum are p-type impurities, when the sub-dopant is incorporated into the silicon single crystal, the carrier of the main dopant is canceled. Therefore, the carrier concentration in the silicon crystal decreases at a high solidification rate, and the specific resistance of the silicon single crystal increases rapidly. Therefore, the variation in specific resistance of the n-type silicon single crystal grown by the conventional method was very large.

  The present invention has been made in view of the above-described problems, and an object thereof is to provide an n-type silicon single crystal having a small variation in specific resistance and a method for manufacturing the same.

  The method for producing an n-type silicon single crystal according to the present invention includes the following steps. Phosphorus as a main dopant, a first sub-dopant that is a p-type impurity and has a segregation coefficient smaller than that of phosphorus, and a second sub-dopant that is an n-type impurity and has a segregation coefficient smaller than that of phosphorus. An added silicon melt is prepared. A silicon single crystal is grown from the silicon melt by the Czochralski method. Here, the segregation coefficient is a segregation coefficient for a silicon single crystal.

  As described above, the first sub-dopant suppresses the change in the specific resistance of the n-type silicon single crystal due to the main dopant, and the second sub-dopant suppresses the specific resistance of the n-type silicon single crystal due to the first sub-dopant. Suppresses rapid rise in As a result, an n-type silicon single crystal with small variations in specific resistance can be obtained.

  In the above method for producing an n-type silicon single crystal, preferably, the first sub-dopant is aluminum and the second sub-dopant is antimony. When the concentration of the first subdopant in the silicon melt is divided by the concentration of the main dopant in the silicon melt, the first concentration ratio is 100 to 2000, and the second subdopant silicon melt The second concentration ratio when the concentration inside is divided by the concentration in the silicon melt of the main dopant is 0.5 or more and 172 or less. Here, the concentration in the silicon melt is the concentration in the initial silicon melt before the silicon single crystal is pulled.

  In the above method for producing an n-type silicon single crystal, preferably, the first sub-dopant is gallium and the second sub-dopant is antimony. When the concentration of the first sub-dopant in the silicon melt is divided by the concentration of the main dopant in the silicon melt, the first concentration ratio is 25.5 to 190, and the second sub-dopant silicon The second concentration ratio when the concentration in the melt is divided by the concentration of the main dopant in the silicon melt is 1.4 or more and 60 or less.

  In the above method for producing an n-type silicon single crystal, preferably, the first sub-dopant is indium and the second sub-dopant is antimony. When the concentration of the first subdopant in the silicon melt is divided by the concentration of the main dopant in the silicon melt, the first concentration ratio is 500 or more and 3300 or less, and the second subdopant silicon melt The second concentration ratio when the concentration inside is divided by the concentration of the main dopant in the silicon melt is 1.4 or more and 51.6 or less.

  In the above method for producing an n-type silicon single crystal, preferably, the first sub-dopant is aluminum and the second sub-dopant is antimony. When the concentration of the first sub-dopant in the silicon melt is divided by the concentration of the main dopant in the silicon melt, the first concentration ratio is 198 or more and 202 or less, and the second sub-dopant silicon melt The second concentration ratio is 9.9 or more and 10.2 or less when the concentration inside is divided by the concentration of the main dopant in the silicon melt.

  In the above method for producing an n-type silicon single crystal, preferably, the first sub-dopant is gallium and the second sub-dopant is antimony. The first concentration ratio when the concentration of the first sub-dopant in the silicon melt is divided by the concentration of the main dopant in the silicon melt is 49.5 or more and 50.5 or less, and the second sub-dopant When the concentration in the silicon melt is divided by the concentration of the main dopant in the silicon melt, the second concentration ratio is 9.7 or more and 10.0 or less.

  The n-type silicon single crystal according to the present invention has phosphorus as a main dopant, a first sub-dopant, and a second sub-dopant. The first sub-dopant is a p-type impurity and has a segregation coefficient smaller than that of phosphorus. The second sub-dopant is an n-type impurity and has a segregation coefficient smaller than that of phosphorus.

  As described above, the first sub-dopant suppresses the change in the specific resistance of the n-type silicon single crystal due to the main dopant, and the second sub-dopant suppresses the specific resistance of the n-type silicon single crystal due to the first sub-dopant. Suppresses rapid rise in As a result, an n-type silicon single crystal with small variations in specific resistance can be obtained.

  Preferably, in the n-type silicon single crystal, the first sub-dopant is aluminum and the second sub-dopant is antimony. When the concentration of the first subdopant in the silicon melt is divided by the concentration of the main dopant in the silicon melt, the first concentration ratio is 100 to 2000, and the second subdopant silicon melt The second concentration ratio when the concentration inside is divided by the concentration in the silicon melt of the main dopant is 0.5 or more and 172 or less.

  Preferably, in the n-type silicon single crystal, the first sub-dopant is gallium and the second sub-dopant is antimony. When the concentration of the first sub-dopant in the silicon melt is divided by the concentration of the main dopant in the silicon melt, the first concentration ratio is 25.5 to 190, and the second sub-dopant silicon The second concentration ratio when the concentration in the melt is divided by the concentration of the main dopant in the silicon melt is 1.4 or more and 60 or less.

  Preferably, in the n-type silicon single crystal, the first sub-dopant is indium and the second sub-dopant is antimony. When the concentration of the first subdopant in the silicon melt is divided by the concentration of the main dopant in the silicon melt, the first concentration ratio is 500 or more and 3300 or less, and the second subdopant silicon melt The second concentration ratio when the concentration inside is divided by the concentration of the main dopant in the silicon melt is 1.4 or more and 51.6 or less.

  Preferably, in the n-type silicon single crystal, the first sub-dopant is aluminum and the second sub-dopant is antimony. When the concentration of the first sub-dopant in the silicon melt is divided by the concentration of the main dopant in the silicon melt, the first concentration ratio is 198 or more and 202 or less, and the second sub-dopant silicon melt The second concentration ratio is 9.9 or more and 10.2 or less when the concentration inside is divided by the concentration of the main dopant in the silicon melt.

  Preferably, in the n-type silicon single crystal, the first sub-dopant is gallium and the second sub-dopant is antimony. The first concentration ratio when the concentration of the first sub-dopant in the silicon melt is divided by the concentration of the main dopant in the silicon melt is 49.5 or more and 50.5 or less, and the second sub-dopant When the concentration in the silicon melt is divided by the concentration of the main dopant in the silicon melt, the second concentration ratio is 9.7 or more and 10.0 or less.

  According to the present invention, an n-type silicon single crystal having a small variation in specific resistance can be obtained.

It is a schematic block diagram which shows the manufacturing apparatus of the n-type silicon single crystal of this Embodiment. It is a flowchart which shows the manufacturing method of the n-type silicon single crystal of this Embodiment. It is a figure which shows the relationship between the specific resistance of an n-type silicon single crystal, and a solidification rate.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following drawings, the same or corresponding parts are denoted by the same reference numerals, and description thereof will not be repeated.

  First, a manufacturing apparatus for manufacturing the n-type silicon single crystal of the present embodiment will be described with reference to FIG.

  As shown in FIG. 1, the silicon single crystal manufacturing apparatus 10 mainly has a chamber 2, a heater 6, a crucible 8, a crucible support shaft 13, and a pulling wire 14. A heat insulating material 3 is provided on the inner wall of the chamber 2. An air supply port 4 for introducing an inert gas such as argon (Ar) is provided at the top of the chamber 2, and an exhaust port 5 for exhausting the gas in the chamber 2 is provided at the bottom of the chamber 2. Is provided. The crucible 8 is filled with a silicon melt 7 as a raw material. The heater 6 is provided in the periphery of the crucible 8, and the silicon melt 7 can be produced by melting the silicon raw material. The crucible support shaft 13 extends from the lower end of the crucible 8 toward the bottom of the chamber, and is supported rotatably by the crucible support shaft drive device 12. The pulling wire 14 is for pulling up the silicon single crystal 1, and can be moved up and down by the pulling wire driving device 15.

  Next, a method for manufacturing the n-type silicon single crystal of the present embodiment will be described with reference to FIGS.

  As shown in FIG. 2, the n-type silicon single crystal according to the present embodiment is a silicon single crystal manufactured by the Czochralski method, and includes a silicon melt preparation step S1, a silicon single crystal growth step S2, and The silicon single crystal cutting step S3 is mainly included.

  In the silicon melt preparation step S <b> 1, the silicon raw material is filled in the crucible 8 and heated by the heater 6 to melt the silicon raw material. Three types of dopants, a main dopant, a first sub-dopant, and a second sub-dopant, are added to the silicon raw material. The main dopant is phosphorus (P) which is an n-type impurity. The first sub-dopant is an impurity having a segregation coefficient of silicon single crystal smaller than that of phosphorus (P) as the main dopant and a conductivity type of p-type. The first sub-dopant is a Group III element such as aluminum (Al), gallium (Ga), indium (In), and the like. The second sub-dopant is an impurity having a smaller segregation coefficient with respect to the silicon single crystal than phosphorus (P), which is the main dopant, and an n-type conductivity. The second sub-dopant is, for example, a group V element such as antimony (Sb).

  In the present embodiment, semiconductor grade silicon is used as the silicon raw material. Semiconductor grade silicon is a silicon raw material having a lower impurity concentration (ie, higher silicon purity) than metal grade silicon. The silicon purity of the semiconductor grade silicon is, for example, 99.99999999999% (11N).

  Three main dopants, the first sub-dopant, and the second sub-dopant added to the silicon raw material may be added simultaneously to the silicon melt, or each dopant may be added separately. For example, first, the main dopant may be added to the silicon melt 7, and then the first sub-dopant and then the second sub-dopant may be added.

  In the silicon single crystal growth step S <b> 2, first, the seed crystal 17 attached to the seed chuck 16 is lowered and immersed on the surface of the silicon melt 7. Thereafter, the pulling wire 14 is taken up by the pulling wire driving device 15 to pull up the silicon single crystal 1.

  After the silicon single crystal 1 reaches the target diameter through the growth of the cone part (expansion part), the straight body part 11 is grown to a predetermined length.

  In the silicon single crystal cutting step S3, first, the straight body 11 is grown to a predetermined length, and then the winding of the pulling wire 14 is stopped. Thereafter, the silicon single crystal 1 is cut from the silicon melt 7 by lowering the crucible 8. A silicon wafer is obtained by slicing the silicon single crystal 1 along a plane perpendicular to the pulling-up axis direction of the silicon single crystal 1.

  Next, the simulation result of the relationship between the specific resistance and the solidification rate of the silicon single crystal will be described with reference to FIG.

  The horizontal axis in FIG. 3 represents the solidification rate. The solidification rate refers to the ratio of the mass of crystallized silicon to the total mass of raw material silicon contained in the silicon melt. The vertical axis in FIG. 3 represents the ratio of specific resistance in the pulling axis D direction of the silicon single crystal 1. Here, the specific resistance is a specific resistance at the center of the silicon single crystal (that is, the pulling axis). The specific resistance ratio is a value obtained by standardizing a specific resistance at a certain solidification rate with a specific resistance at a solidification rate of 0.

In FIG. 3, a sample 101 is obtained from a silicon melt to which phosphorus (P) as a main dopant, aluminum (Al) as a first sub-dopant, and antimony (Sb) as a second sub-dopant are added. Is an n-type silicon single crystal containing three types of dopants formed by The boron concentration in the silicon melt is 3.4 × 10 ¹⁵ atoms / cm ³ . The concentration ratio (first concentration ratio) when the aluminum concentration in the silicon melt is divided by the phosphorus concentration is 112, and the concentration ratio when the antimony concentration in the silicon melt is divided by the phosphorus concentration. The (second density ratio) is 1.7.

On the other hand, the sample 102 is an n-type silicon single crystal containing two types of dopants formed by a Czochralski method from a silicon melt to which phosphorus (P) as a main dopant and aluminum (Al) as a sub-dopant are added. is there. The boron concentration in the silicon melt is 2.9 × 10 ¹⁴ atoms / cm ³ . The concentration ratio (first concentration ratio) is 112 when the concentration of aluminum in the silicon melt is divided by the concentration of phosphorus.

  As can be seen from FIG. 3, in the sample 102 containing two kinds of dopants, the resistivity ratio increases rapidly when the solidification rate becomes higher than about 0.5. However, the sample 101 containing three kinds of dopants has a small change (α) in the ratio of resistivity when the solidification rate is in the range of about 0 to 0.7. When the solidification rate is in the range from 0 to 0.7, the variation in the specific resistance in the pulling axis direction of the silicon single crystal sample 101 is as small as about 14.6% or less. The variation in specific resistance is a value defined by Equation 1. Here, the maximum value of the specific resistance is the maximum value of the specific resistance of the silicon single crystal in the pulling axis direction, and the minimum value of the specific resistance is the minimum value of the specific resistance of the silicon single crystal in the pulling axis direction.

  In particular, a substrate used for a power device such as an IGBT is required to have a high specific resistance and a small specific resistance variation. Specifically, the specific resistance of the n-type silicon single crystal is desirably 6 Ωcm or more, preferably 50 Ωcm or more, and more preferably 100 Ωcm or more. Further, the variation in specific resistance of the n-type silicon single crystal is desirably about 50% or less, preferably 20% or less, more preferably 15% or less, and further preferably, within the range of the solidification rate of 0 to 0.7. 12% or less.

  Next, a mechanism for reducing the variation in specific resistance of the silicon single crystal of the present embodiment will be described.

  When only phosphorus (main dopant) is added to the silicon melt, the phosphorus concentration in the silicon single crystal increases as the silicon single crystal grows (that is, the solidification rate increases). Therefore, the specific resistance is reduced on the bottom side of the silicon single crystal.

  This is because the segregation coefficient of phosphorus with respect to the silicon single crystal is about 0.38 and is less than 1, so that the concentration of phosphorus in the silicon melt increases as the silicon single crystal grows. As a result, the ratio of phosphorus taken into the silicon single crystal increases, and the specific resistance decreases.

  Similarly, when aluminum is added to the silicon melt, the aluminum concentration in the silicon single crystal increases as the silicon single crystal grows. Therefore, the specific resistance is reduced on the bottom side of the silicon single crystal. The segregation coefficient of aluminum with respect to a silicon single crystal is about 0.002, which is smaller than that of phosphorus. Therefore, the rate of concentration of aluminum in the silicon melt accompanying the growth of the silicon single crystal is faster than the rate of concentration of phosphorus. Therefore, the rate of decrease of the specific resistance accompanying the growth of the silicon single crystal is faster when aluminum is added than when phosphorus is added.

  When phosphorus (main dopant) and aluminum (first sub-dopant) are added to the silicon melt, phosphorus is an n-type impurity and aluminum is a p-type impurity. The carriers of the conductivity type are canceled out. Therefore, by adding aluminum together with phosphorus to a silicon single crystal, the density of n-type carriers can be reduced and the specific resistance can be increased. Further, the rate of increase in impurity concentration accompanying the growth of the silicon single crystal is greater when aluminum is added than when phosphorus is added. Therefore, the increase in the n-type carrier density due to the increase in the phosphorus concentration accompanying the growth of the silicon single crystal is canceled by the increase in the p-type carrier density due to the increase in the aluminum concentration, thereby reducing the specific resistance accompanying the growth of the silicon single crystal. The rate of reduction can be reduced.

  When the solidification rate is small, the rate of decrease in specific resistance accompanying the growth of the silicon single crystal can be reduced. However, as the solidification rate increases, the increase in the p-type carrier density due to the increase in the aluminum concentration becomes dominant. As the silicon single crystal grows, the specific resistance increases.

  When antimony (second sub-dopant) having a segregation coefficient smaller than phosphorus (main dopant) is added to the silicon melt, almost no n-type carrier due to antimony is taken into the silicon single crystal when the solidification rate is low. . However, as the solidification rate increases, antimony is gradually taken into the silicon single crystal, increasing n-type carriers. As a result, the specific resistance gradually decreases. Therefore, the addition of antimony can suppress an increase in specific resistance of the silicon single crystal at a high solidification rate. As a result, it is possible to reduce variation in specific resistance in the pulling axis direction of the silicon single crystal.

  As described above, by adding the second sub-dopant which is an n-type impurity and has a segregation coefficient smaller than that of the main dopant to the silicon melt, the specific resistance of the silicon single crystal rapidly increases when the solidification rate is high. You can slow down. Therefore, even if the solidification rate is a large value, the specific resistance of the silicon single crystal does not increase too much, so that a desired specific resistance can be maintained in a wide range of solidification rates, and the yield of the silicon single crystal can be improved. .

  (Embodiment 1)

Table 1 shows the case where phosphorus (P) is used as the main dopant added to the silicon melt, aluminum (Al) is used as the first sub-dopant, and antimony (Sb) is used as the second sub-dopant. A value obtained by dividing the concentration of the subdopant in the silicon melt by the concentration in the silicon melt of the main dopant (first concentration ratio) is changed in the range of about 100 or more and about 2100 or less, and the second subdopant When the value obtained by dividing the concentration of silicon in the silicon melt by the concentration of the main dopant in the silicon melt (second concentration ratio) is changed within a range of about 0.5 or more and about 181 or less, the silicon single crystal The simulation result of the dispersion | variation in the specific value of the maximum value of the specific resistance of this, minimum value, and a pulling-up axis direction is shown. In this case, the boron concentration is about 5.09 × 10 ¹³ atoms / cm ³ or more and about 3.48 × 10 ¹⁵ atoms / cm ³ or less.

  In this case, the maximum value of the specific resistance is about 7.5 Ωcm or more and about 186.5 Ωcm or less, and the minimum value of the specific resistance is about 6.4 Ωcm or more and about 158.4 Ωcm or less. An n-type silicon single crystal having a variation of about 50.4% or less can be obtained.

More preferably, a value (first concentration ratio) obtained by dividing the concentration of the first sub-dopant in the silicon melt by the concentration of the main dopant in the silicon melt is in the range of about 100 or more and about 2000 or less. In addition, a value (second concentration ratio) obtained by dividing the concentration of the second subdopant in the silicon melt by the concentration of the main dopant in the silicon melt is in the range of about 0.5 or more and about 172 or less. In this case, the boron concentration is about 7.25 × 10 ¹³ atoms / cm ³ or more and about 3.48 × 10 ¹⁵ atoms / cm ³ or less.

  In this case, the maximum value of the specific resistance is about 7.5 Ωcm or more and about 186.1 Ωcm or less, the minimum value of the specific resistance is about 6.4 Ωcm or more and about 158.4 Ωcm or less, and the specific resistance in the pulling axis direction is An n-type silicon single crystal having a variation of about 50.4% or less can be obtained.

More preferably, a value (first concentration ratio) obtained by dividing the concentration of the first sub-dopant in the silicon melt by the concentration of the main dopant in the silicon melt is in a range of about 198 or more and about 202 or less. And the value obtained by dividing the concentration of the second sub-dopant in the silicon melt by the concentration of the main dopant in the silicon melt (second concentration ratio) is in the range of about 9.9 or more and about 10.2 or less. is there. In this case, the boron concentration is about 2.37 × 10 ¹⁴ atoms / cm ³ or more and about 4.28 × 10 ¹⁴ atoms / cm ³ or less.

  In this case, the maximum value of the specific resistance is about 50.0 Ωcm or more and about 97.3 Ωcm or less, and the minimum value of the specific resistance is about 44.2 Ωcm or more and about 84.1 Ωcm or less. An n-type silicon single crystal having a variation of about 14.8% or less can be obtained.

  (Embodiment 2)

Table 2 shows the case where phosphorus (P) is used as the main dopant added to the silicon melt, gallium (Ga) is used as the first sub-dopant, and antimony (Sb) is used as the second sub-dopant. A value (first concentration ratio) obtained by dividing the concentration of the subdopant in the silicon melt by the concentration in the silicon melt of the main dopant is changed within a range of about 20.0 or more and about 200 or less, and the second Silicon when the value (second concentration ratio) obtained by dividing the concentration of the subdopant in the silicon melt by the concentration in the silicon melt of the main dopant is changed in the range of about 0.5 to about 63. The simulation result of the dispersion | variation in the maximum value of the specific resistance of a single crystal, minimum value, and the specific resistance of a pulling-up axis line is shown. In this case, the boron concentration is about 9.56 × 10 ¹³ atoms / cm ³ or more and about 2.61 × 10 ¹⁵ atoms / cm ³ or less.

  In this case, the maximum value of the specific resistance is about 8.5 Ωcm or more and about 191.5 Ωcm or less, and the minimum value of the specific resistance is about 6.3 Ωcm or more and about 162.6 Ωcm or less. An n-type silicon single crystal having a variation of about 38.5% or less can be obtained.

More preferably, the value obtained by dividing the concentration of the first sub-dopant in the silicon melt by the concentration of the main dopant in the silicon melt (first concentration ratio) is in the range of about 25.5 or more and about 190 or less. And the value obtained by dividing the concentration of the second sub-dopant in the silicon melt by the concentration of the main dopant in the silicon melt (second concentration ratio) is in the range of about 1.4 or more and about 60 or less. is there. In this case, the boron concentration is about 9.56 × 10 ¹³ atoms / cm ³ or more and about 2.61 × 10 ¹⁵ atoms / cm ³ or less.

  In this case, the maximum value of the specific resistance is about 8.5 Ωcm or more and about 180.0 Ωcm or less, and the minimum value of the specific resistance is about 7.2 Ωcm or more and about 155.8 Ωcm or less. An n-type silicon single crystal having a variation of about 38.5% or less can be obtained.

More preferably, a value obtained by dividing the concentration of the first sub-dopant in the silicon melt by the concentration of the main dopant in the silicon melt (first concentration ratio) is about 49.5 or more and about 50.5 or less. The value obtained by dividing the concentration of the second sub-dopant in the silicon melt by the concentration of the main dopant in the silicon melt (second concentration ratio) is about 9.7 or more and 10.0 or less. The range of the degree. In this case, the boron concentration is about 1.58 × 10 ¹⁴ atoms / cm ³ or more and about 2.21 × 10 ¹⁴ atoms / cm ³ or less.

  In this case, the maximum value of the specific resistance is about 100.2 Ωcm or more and about 149.6 Ωcm or less, and the minimum value of the specific resistance is about 89.4 Ωcm or more and about 129.1 Ωcm or less. An n-type silicon single crystal having a variation of about 14.7% or less can be obtained.

  (Embodiment 3)

Table 3 shows the case where phosphorus (P) is used as the main dopant added to the silicon melt, indium (In) is used as the first sub-dopant, and antimony (Sb) is used as the second sub-dopant. A value obtained by dividing the concentration of the subdopant in the silicon melt by the concentration in the silicon melt of the main dopant (first concentration ratio) is changed in the range of about 450 to about 3400, and the second subdopant When the value obtained by dividing the concentration of silicon in the silicon melt by the concentration of the main dopant in the silicon melt (second concentration ratio) is changed within the range of about 0.6 or more and about 54 or less, the silicon single crystal The simulation result of the dispersion | variation in the specific value of the maximum value of the specific resistance of this, minimum value, and a pulling-up axis direction is shown. In this case, the boron concentration is about 1.00 × 10 ¹⁴ atoms / cm ³ or more and about 3.06 × 10 ¹⁵ atoms / cm ³ or less.

  In this case, the maximum value of the specific resistance is about 7.5 Ωcm or more and about 150.0 Ωcm or less, and the minimum value of the specific resistance is about 6.3 Ωcm or more and about 131.9 Ωcm or less. An n-type silicon single crystal having a variation of about 35.0% or less can be obtained.

More preferably, a value (first concentration ratio) obtained by dividing the concentration of the first sub-dopant in the silicon melt by the concentration of the main dopant in the silicon melt is in the range of about 500 or more and about 3300 or less. And a value obtained by dividing the concentration of the second sub-dopant in the silicon melt by the concentration of the main dopant in the silicon melt (second concentration ratio) is in the range of about 1.4 or more and about 51.6 or less. is there. In this case, the boron concentration is about 1.00 × 10 ¹⁴ atoms / cm ³ or more and about 3.06 × 10 ¹⁵ atoms / cm ³ or less.

  In this case, the maximum value of the specific resistance is about 7.5 Ωcm or more and about 150.0 Ωcm or less, and the minimum value of the specific resistance is about 6.4 Ωcm or more and about 131.9 Ωcm or less. An n-type silicon single crystal having a variation of about 35.0% or less can be obtained.

  As described above, phosphorus (main dopant), a p-type impurity, a first sub-dopant having a segregation coefficient smaller than phosphorus, and an n-type impurity having a segregation coefficient smaller than that of main dopant phosphorus. The n-type silicon single crystal grown by the Czochralski method from the initial silicon melt to which the second sub-dopant is added is phosphorus (main dopant), p-type impurity, and is the main dopant. It includes a first sub-dopant having a segregation coefficient smaller than that of phosphorus and a second sub-dopant which is an n-type impurity and has a segregation coefficient smaller than that of phosphorus as a main dopant. Then, the first concentration ratio when the concentration of the first sub-dopant in the silicon melt is divided by the concentration of the main dopant in the silicon melt and the concentration of the second sub-dopant in the silicon melt are mainly used. If the second concentration ratio when the dopant is divided by the concentration in the silicon melt is in the range described in the first to third embodiments, it is the first concentration ratio and the second concentration ratio in that range. An n-type silicon single crystal containing a main dopant, a first sub-dopant, and a second sub-dopant can be obtained.

  Next, a method for measuring the dopant concentration contained in the silicon single crystal 1 will be described. The concentration of elements such as phosphorus, aluminum, gallium, indium, and antimony in the silicon single crystal 1 as a dopant can be measured by a known method such as SIMS (Secondary Ion Mass Spectroscopy).

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is shown not by the embodiments and examples described above but by the scope of claims for patent, and is intended to include all modifications within the meaning and scope equivalent to the scope of claims for patent.

  DESCRIPTION OF SYMBOLS 1 Silicon single crystal, 2 chamber, 3 heat insulating material, 4 air supply port, 5 exhaust port, 6 heater, 7 silicon melt, 8 crucible, 10 silicon single crystal manufacturing apparatus, 11 straight body part, 12 crucible support shaft drive device , 13 crucible support shaft, 14 pulling wire, 15 pulling wire driving device, 16 seed chuck, 17 seed crystal.

As shown in FIG. 2, the method for manufacturing an n-type silicon single crystal according to the present embodiment is a method for manufacturing a silicon single crystal by the Czochralski method , and includes a silicon melt preparation step S1 and silicon single crystal growth. It mainly includes a step S2 and a silicon single crystal cutting step S3.

In FIG. 3, a sample 101 is obtained from a silicon melt to which phosphorus (P) as a main dopant, aluminum (Al) as a first sub-dopant, and antimony (Sb) as a second sub-dopant are added. Is an n-type silicon single crystal containing three types of dopants formed by The phosphorus (P) concentration in the silicon melt is 3.4 × 10 ¹⁵ atoms / cm ³ . The concentration ratio (first concentration ratio) when the aluminum concentration in the silicon melt is divided by the phosphorus concentration is 112, and the concentration ratio when the antimony concentration in the silicon melt is divided by the phosphorus concentration. The (second density ratio) is 1.7.

On the other hand, the sample 102 is an n-type silicon single crystal containing two types of dopants formed by a Czochralski method from a silicon melt to which phosphorus (P) as a main dopant and aluminum (Al) as a sub-dopant are added. is there. The phosphorus (P) concentration in the silicon melt is 2.9 × 10 ¹⁴ atoms / cm ³ . The concentration ratio (first concentration ratio) is 112 when the concentration of aluminum in the silicon melt is divided by the concentration of phosphorus.

Table 1 shows the case where phosphorus (P) is used as the main dopant added to the silicon melt, aluminum (Al) is used as the first sub-dopant, and antimony (Sb) is used as the second sub-dopant. A value obtained by dividing the concentration of the subdopant in the silicon melt by the concentration in the silicon melt of the main dopant (first concentration ratio) is changed in the range of about 100 or more and about 2100 or less, and the second subdopant When the value obtained by dividing the concentration of silicon in the silicon melt by the concentration of the main dopant in the silicon melt (second concentration ratio) is changed within a range of about 0.5 or more and about 181 or less, the silicon single crystal The simulation result of the dispersion | variation in the specific value of the maximum value of the specific resistance of this, minimum value, and a pulling-up axis direction is shown. In this case, the phosphorus (P) concentration is about 5.09 × 10 ¹³ atoms / cm ³ or more and about 3.48 × 10 ¹⁵ atoms / cm ³ or less.

More preferably, a value (first concentration ratio) obtained by dividing the concentration of the first sub-dopant in the silicon melt by the concentration of the main dopant in the silicon melt is in the range of about 100 or more and about 2000 or less. In addition, a value (second concentration ratio) obtained by dividing the concentration of the second subdopant in the silicon melt by the concentration of the main dopant in the silicon melt is in the range of about 0.5 or more and about 172 or less. In this case, the phosphorus (P) concentration is about 7.25 × 10 ¹³ atoms / cm ³ or more and about 3.48 × 10 ¹⁵ atoms / cm ³ or less.

More preferably, a value (first concentration ratio) obtained by dividing the concentration of the first sub-dopant in the silicon melt by the concentration of the main dopant in the silicon melt is in a range of about 198 or more and about 202 or less. And the value obtained by dividing the concentration of the second sub-dopant in the silicon melt by the concentration of the main dopant in the silicon melt (second concentration ratio) is in the range of about 9.9 or more and about 10.2 or less. is there. In this case, the phosphorus (P) concentration is about 2.37 × 10 ¹⁴ atoms / cm ³ or more and about 4.28 × 10 ¹⁴ atoms / cm ³ or less.

Table 2 shows the case where phosphorus (P) is used as the main dopant added to the silicon melt, gallium (Ga) is used as the first sub-dopant, and antimony (Sb) is used as the second sub-dopant. A value (first concentration ratio) obtained by dividing the concentration of the subdopant in the silicon melt by the concentration in the silicon melt of the main dopant is changed within a range of about 20.0 or more and about 200 or less, and the second Silicon when the value (second concentration ratio) obtained by dividing the concentration of the subdopant in the silicon melt by the concentration in the silicon melt of the main dopant is changed in the range of about 0.5 to about 63. The simulation result of the dispersion | variation in the maximum value of the specific resistance of a single crystal, minimum value, and the specific resistance of a pulling-up axis line is shown. In this case, the phosphorus (P) concentration is about 9.56 × 10 ¹³ atoms / cm ³ or more and about 2.61 × 10 ¹⁵ atoms / cm ³ or less.

More preferably, the value obtained by dividing the concentration of the first sub-dopant in the silicon melt by the concentration of the main dopant in the silicon melt (first concentration ratio) is in the range of about 25.5 or more and about 190 or less. And the value obtained by dividing the concentration of the second sub-dopant in the silicon melt by the concentration of the main dopant in the silicon melt (second concentration ratio) is in the range of about 1.4 or more and about 60 or less. is there. In this case, the phosphorus (P) concentration is about 9.56 × 10 ¹³ atoms / cm ³ or more and about 2.61 × 10 ¹⁵ atoms / cm ³ or less.

More preferably, a value obtained by dividing the concentration of the first sub-dopant in the silicon melt by the concentration of the main dopant in the silicon melt (first concentration ratio) is about 49.5 or more and about 50.5 or less. The value obtained by dividing the concentration of the second sub-dopant in the silicon melt by the concentration of the main dopant in the silicon melt (second concentration ratio) is about 9.7 or more and 10.0 or less. The range of the degree. In this case, the phosphorus (P) concentration is about 1.58 × 10 ¹⁴ atoms / cm ³ or more and about 2.21 × 10 ¹⁴ atoms / cm ³ or less.

Table 3 shows the case where phosphorus (P) is used as the main dopant added to the silicon melt, indium (In) is used as the first sub-dopant, and antimony (Sb) is used as the second sub-dopant. A value obtained by dividing the concentration of the subdopant in the silicon melt by the concentration in the silicon melt of the main dopant (first concentration ratio) is changed in the range of about 450 to about 3400, and the second subdopant When the value obtained by dividing the concentration of silicon in the silicon melt by the concentration of the main dopant in the silicon melt (second concentration ratio) is changed within the range of about 0.6 or more and about 54 or less, the silicon single crystal The simulation result of the dispersion | variation in the specific value of the maximum value of the specific resistance of this, minimum value, and a pulling-up axis direction is shown. In this case, the phosphorus (P) concentration is about 1.00 × 10 ¹⁴ atoms / cm ³ or more and about 3.06 × 10 ¹⁵ atoms / cm ³ or less.

More preferably, a value (first concentration ratio) obtained by dividing the concentration of the first sub-dopant in the silicon melt by the concentration of the main dopant in the silicon melt is in the range of about 500 or more and about 3300 or less. And a value obtained by dividing the concentration of the second sub-dopant in the silicon melt by the concentration of the main dopant in the silicon melt (second concentration ratio) is in the range of about 1.4 or more and about 51.6 or less. is there. In this case, the phosphorus (P) concentration is about 1.00 × 10 ¹⁴ atoms / cm ³ or more and about 3.06 × 10 ¹⁵ atoms / cm ³ or less.

Claims (12)

Phosphorus as a main dopant, a p-type impurity, a first sub-dopant having a segregation coefficient smaller than that of the phosphorus, and an n-type impurity, a second sub-dopant having a segregation coefficient smaller than that of the phosphorus A step of preparing a silicon melt to which is added,
And a step of growing a silicon single crystal from the silicon melt by a Czochralski method. The first sub-dopant is aluminum and the second sub-dopant is antimony;
The first concentration ratio when the concentration of the first sub-dopant in the silicon melt is divided by the concentration of the main dopant in the silicon melt is not less than 100 and not more than 2000, and the second sub-dopant 2. The n-type silicon according to claim 1, wherein the second concentration ratio when the concentration of the dopant in the silicon melt is divided by the concentration of the main dopant in the silicon melt is 0.5 or more and 172 or less. A method for producing a single crystal. The first sub-dopant is gallium and the second sub-dopant is antimony;
The first concentration ratio when the concentration of the first sub-dopant in the silicon melt is divided by the concentration of the main dopant in the silicon melt is 25.5 or more and 190 or less, and the second 2. The n concentration according to claim 1, wherein the second concentration ratio when the concentration of the sub-dopant in the silicon melt is divided by the concentration of the main dopant in the silicon melt is 1.4 or more and 60 or less. Type silicon single crystal manufacturing method. The first sub-dopant is indium and the second sub-dopant is antimony;
The first concentration ratio when the concentration of the first sub-dopant in the silicon melt is divided by the concentration of the main dopant in the silicon melt is 500 to 3300, and the second sub-dopant 2. The n concentration according to claim 1, wherein the second concentration ratio when the concentration of the dopant in the silicon melt is divided by the concentration of the main dopant in the silicon melt is 1.4 or more and 51.6 or less. Type silicon single crystal manufacturing method. The first sub-dopant is aluminum and the second sub-dopant is antimony;
The first concentration ratio when the concentration of the first sub-dopant in the silicon melt is divided by the concentration of the main dopant in the silicon melt is 198 or more and 202 or less, and the second sub-dopant 2. The n according to claim 1, wherein the second concentration ratio when the concentration of the dopant in the silicon melt is divided by the concentration of the main dopant in the silicon melt is 9.9 or more and 10.2 or less. Type silicon single crystal manufacturing method. The first sub-dopant is gallium and the second sub-dopant is antimony;
The first concentration ratio when the concentration of the first sub-dopant in the silicon melt is divided by the concentration of the main dopant in the silicon melt is 49.5 or more and 50.5 or less, and The second concentration ratio when the concentration of the second sub-dopant in the silicon melt is divided by the concentration of the main dopant in the silicon melt is 9.7 or more and 10.0 or less. A method for producing an n-type silicon single crystal according to 1. Phosphorus as a main dopant and a p-type impurity, a first subdopant having a segregation coefficient smaller than that of the phosphorus,
An n-type silicon single crystal comprising a second sub-dopant which is an n-type impurity and has a segregation coefficient smaller than that of phosphorus. The first sub-dopant is aluminum and the second sub-dopant is antimony;
The first concentration ratio when the concentration of the first sub-dopant in the silicon melt is divided by the concentration of the main dopant in the silicon melt is not less than 100 and not more than 2000, and the second sub-dopant The n-type silicon according to claim 7, wherein the second concentration ratio when the concentration of the dopant in the silicon melt is divided by the concentration of the main dopant in the silicon melt is 0.5 or more and 172 or less. Single crystal. The first sub-dopant is gallium and the second sub-dopant is antimony;
The first concentration ratio when the concentration of the first sub-dopant in the silicon melt is divided by the concentration of the main dopant in the silicon melt is 25.5 or more and 190 or less, and the second 8. The n concentration according to claim 7, wherein the second concentration ratio when the concentration of the sub-dopant in the silicon melt is divided by the concentration of the main dopant in the silicon melt is 1.4 or more and 60 or less. Type silicon single crystal. The first sub-dopant is indium and the second sub-dopant is antimony;
The first concentration ratio when the concentration of the first sub-dopant in the silicon melt is divided by the concentration of the main dopant in the silicon melt is 500 to 3300, and the second sub-dopant The n concentration according to claim 7, wherein the second concentration ratio when the concentration of the dopant in the silicon melt is divided by the concentration of the main dopant in the silicon melt is 1.4 or more and 51.6 or less. Type silicon single crystal. The first sub-dopant is aluminum and the second sub-dopant is antimony;
The first concentration ratio when the concentration of the first sub-dopant in the silicon melt is divided by the concentration of the main dopant in the silicon melt is 198 or more and 202 or less, and the second sub-dopant The n concentration according to claim 7, wherein the second concentration ratio when the concentration of the dopant in the silicon melt is divided by the concentration of the main dopant in the silicon melt is 9.9 or more and 10.2 or less. Type silicon single crystal. The first sub-dopant is gallium and the second sub-dopant is antimony;
The first concentration ratio when the concentration of the first sub-dopant in the silicon melt is divided by the concentration of the main dopant in the silicon melt is 49.5 or more and 50.5 or less, and The second concentration ratio when the concentration of the second sub-dopant in the silicon melt is divided by the concentration of the main dopant in the silicon melt is 9.7 or more and 10.0 or less. The n-type silicon single crystal described in 1.

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