Monocrystalline silicon resistivity measurement method

Abstract

The present invention is a method for measuring the resistivity of a single crystal silicon having a resistivity of 100 [Omega] cm or more grown by adding nitrogen by the MCZ method, characterized in that: a substrate cut from the single crystal silicon is subjected to an oxidation heat treatment at a temperature of 1100-1250 DEG C for 90-240 minutes to form a thermal oxide film on the surface of the substrate; after the thermal oxide film is removed from the surface of the substrate, the resistivity of the substrate is measured. As a result, provided is a method for measuring the resistivity of a single crystal silicon with which it is possible to measure the accurate resistivity derived from a dopant on a single crystal silicon having a resistivity of 100 [Omega] cm or more grown by adding nitrogen by the MCZ method.

Description

Technical Field

[0001] The present invention relates to a method for measuring the resistivity of single crystal silicon with a resistivity of 100 Ωcm or more grown by adding nitrogen by the MCZ method. Background Art

[0002] For communication applications such as smartphones, RF (high-frequency) devices are used. Compound semiconductors are mainly used in such RF devices, but in recent years, RF devices based on single crystal silicon have been widely used for reasons such as the advancement of miniaturization of CMOS processes and the desire for low cost in device manufacturing.

[0003] In RF devices using single crystal silicon wafers, if the resistivity of the substrate is low, that is, the dopant concentration becomes high, it becomes highly conductive and the loss increases. Therefore, a substrate with a high resistivity is required, specifically 100 Ωcm or more. Sometimes, a wafer called SOI (Silicon On Insulator), in which a thin oxide film and a thin silicon layer are formed on the surface layer of a silicon substrate, is used. In this case, a high resistivity is also desired. In addition, for power devices, a substrate with a high resistivity is also required for high breakdown voltage applications.

[0004] In RF (high-frequency) devices and power devices, if oxygen donors are present in the silicon substrate, the characteristics deteriorate. Therefore, in order to suppress oxygen donors, single crystal silicon with a low oxygen concentration is required.

[0005] In the CZ method, the raw material melt of silicon is contained in a quartz crucible, and during crystal pulling, oxygen dissolves from the quartz crucible into the raw material melt and is incorporated into the single crystal.

[0006] As a method for obtaining a low-oxygen crystal, for example, Patent Document 1 discloses a method for obtaining a low-oxygen crystal by specifying the crystal rotation speed and the crucible rotation speed under a horizontal magnetic field. In addition, Patent Document 2 discloses a method in which the magnetic field strength of the horizontal magnetic field is set to 2000 G or more, the rotation speed of the quartz crucible is set to 0.2 rpm or less, and the crystal rotation speed is set to 5 rpm or less. Patent Document 3 discloses a method for obtaining a low-oxygen crystal by specifying the position of the magnetic field minimum plane, the position of the liquid surface, and the magnetic field strength at the intersection of the intermediate plane between the upper and lower coils and the inner wall of the quartz crucible under a skew magnetic field.

[0007] Thus, in recent manufacturing of single crystal silicon based on the CZ method, by using magnetic fields such as a horizontal magnetic field and a skew magnetic field, and appropriately optimizing operation parameters such as the crystal rotation speed, the crucible rotation speed, the magnetic field strength, and the excitation method, a low-oxygen crystal can be stably manufactured.

[0008] However, in single-crystalline silicon with low oxygen content, the dislocation fixing effect based on oxygen becomes weaker. As a result, during high-temperature and long-time processes (heat treatments), the occurrence of slip becomes significant. Therefore, when manufacturing RF devices and power devices, the reduction in yield becomes a problem. As a method for improving the slip resistance, there is a method of adding nitrogen to single-crystalline silicon. Nitrogen in single-crystalline silicon has a higher dislocation fixing ability compared to oxygen. Therefore, by making the nitrogen in single-crystalline silicon at a high concentration, the occurrence of slip during high-temperature and long-time device processes can be suppressed.

[0009] However, if nitrogen is added to single-crystalline silicon, nitrogen donors (N-O donors) are formed. These nitrogen donors disappear through high-temperature and long-time processes (heat treatments). Therefore, after the process, there is no change in resistivity. However, at the as-grown time point, the nitrogen donors remain. Especially in high-resistance crystals with a resistivity of 100 Ωcm or more, the change in resistivity becomes significant due to the remaining nitrogen donors, and there is a problem that the deviation from the true resistivity due to dopants becomes larger.

[0010] As a countermeasure against this problem, for example, Patent Document 4 discloses the following method: Nitrogen-doped single-crystalline silicon with a resistivity of 1000 Ωcm or more is produced by the FZ method. After collecting a sample (single-crystalline silicon substrate) for resistivity measurement from the crystal, heat treatment is performed at a temperature of 900 to 1250 °C for 10 to 120 minutes, and then resistivity measurement is performed. In addition, in Patent Document 4, the sample for resistivity measurement is heat-treated in any one of a wet oxygen atmosphere, a dry oxygen atmosphere, and a nitrogen atmosphere, and resistivity measurement is performed in an untreated state after the heat treatment.

[0011] Prior Art Documents

[0012] Patent Documents

[0013] Patent Document 1: Japanese Unexamined Patent Application Publication No. 2009-18984

[0014] Patent Document 2: WO2009 / 025340

[0015] Patent Document 3: Japanese Patent No. 7124938

[0016] Patent Document 4: WO2005 / 010243

[0017] Patent Document 5: Japanese Unexamined Patent Application Publication No. 2007-176725 Summary of the Invention

[0018] (I) Technical Problem to be Solved

[0019] However, if heat treatment is carried out in an oxygen atmosphere, a thermal oxide film is formed on the surface of the sample. If resistivity is measured with the thermal oxide film remaining on the surface of the sample, there is a problem that accurate resistivity derived from the dopant cannot be obtained. In addition, if heat treatment is carried out in a nitrogen atmosphere, outward diffusion of nitrogen in the single crystal silicon and inward diffusion from the nitrogen atmosphere occur simultaneously, and there is a problem that nitrogen donors (N O donors) remain depending on the heat treatment conditions.

[0020] In Patent Document 5, the following method is disclosed: nitrogen-doped single crystal silicon with a resistivity of 1000 Ω·cm or more is produced by the FZ method. After collecting a sample for resistivity measurement from the crystal, heat treatment and neutron ray irradiation are carried out, and then resistivity measurement is carried out. In the technique of Patent Document 5, heat treatment is also carried out on the sample for resistivity measurement in a wet oxygen or dry oxygen atmosphere followed by neutron ray irradiation, and resistivity measurement is carried out after neutron ray irradiation. However, this is also a measurement of resistivity with the thermal oxide film remaining on the surface of the sample, so there is a problem that accurate resistivity derived from the dopant cannot be obtained.

[0021] The present invention is completed to solve the above problems, and an object thereof is to provide a method for measuring the resistivity of single crystal silicon, which can measure accurate resistivity derived from the dopant for single crystal silicon with a resistivity of 100 Ω·cm or more grown by adding nitrogen by the MCZ method.

[0022] (II) Technical Solution

[0023] To solve the above technical problems, the method for measuring the resistivity of single crystal silicon of the present invention measures the resistivity of single crystal silicon with a resistivity of 100 Ω·cm or more grown by adding nitrogen by the MCZ method. Among them, by subjecting a substrate cut from the single crystal silicon to oxidative heat treatment at a temperature of 1100 to 1250 °C for 90 to 240 minutes, a thermal oxide film is formed on the surface of the substrate, and after removing the thermal oxide film from the surface of the substrate, the resistivity of the substrate is measured.

[0024] If it is such a method for measuring the resistivity of single crystal silicon, first, for the nitrogen donors formed on the single crystal silicon grown by adding nitrogen, the nitrogen donors are made to disappear by oxidative heat treatment at a temperature of 1100 to 1250 °C for 90 to 240 minutes, and changes in resistivity caused by the remaining nitrogen donors can be suppressed. Then, the thermal oxide film formed on the surface of the substrate by oxidative heat treatment is removed, whereby the influence of the remaining thermal oxide film on the resistivity can be eliminated. As a result, even for high-resistivity nitrogen-doped single crystal silicon with a resistivity of 100 Ω·cm or more, accurate resistivity derived from the dopant can be measured.

[0025] Further, in the method for measuring the resistivity of single-crystalline silicon according to the present invention, preferably, after removing the thermal oxide film on the surface of the substrate by etching using hydrofluoric acid, the surface of the substrate is ground.

[0026] Etching using hydrofluoric acid is easy and advantageous in terms of cost. Thereafter, the thermal oxide film can be reliably removed by grinding the surface of the substrate.

[0027] Further, in the method for measuring the resistivity of single-crystalline silicon according to the present invention, preferably, the nitrogen concentration of the single-crystalline silicon is set to 3.0×10 14 atoms / cm 3 or more, and the oxygen concentration is set to 8.0×10 17 atoms / cm 3 (ASTM’79) or less.

[0028] In such a method for measuring the resistivity of single-crystalline silicon, first, by setting the oxygen concentration of the single-crystalline silicon to 8.0×10 17 atoms / cm 3 (ASTM’79) or less, not only can the oxygen donor concentration be suppressed, but also the nitrogen donor (NO donor) concentration can be suppressed, and higher-precision resistivity measurement can be performed. However, in single-crystalline silicon with low oxygen, the dislocation fixing effect based on oxygen becomes weak. As a result, in a high-temperature and long-time process (heat treatment), the occurrence of slip becomes significant. Therefore, during device fabrication, a problem of reduced yield occurs. Thus, by setting the nitrogen concentration of the single-crystalline silicon to 3.0×10 14 atoms / cm 3 or more, sufficient slip resistance for high-temperature and long-time processes can be imparted. As a result, a reduction in yield during device fabrication can be prevented, and high-precision resistivity measurement can be achieved.

[0029] (III) Beneficial Effects

[0030] If it is the method for measuring the resistivity of single-crystalline silicon according to the present invention, the resistivity of single-crystalline silicon with a resistivity of 100 Ωcm or more grown by adding nitrogen by the MCZ method can be accurately measured. First, for the nitrogen donors formed on the single-crystalline silicon grown by adding nitrogen, by performing oxidation heat treatment at a temperature of 1100 to 1250 °C for 90 to 240 minutes, the nitrogen donors are made to disappear, and the change in resistivity caused by the remaining nitrogen donors can be suppressed. Then, by removing the thermal oxide film formed on the surface of the substrate by oxidation heat treatment, the influence of the remaining thermal oxide film on the resistivity can be excluded. As a result, even for high-resistivity nitrogen-doped single-crystalline silicon with a resistivity of 100 Ωcm or more, the accurate resistivity derived from the dopant can be measured. Description of the Drawings

[0031] Figure 1This is a flowchart showing an example of the method for measuring the resistivity of single-crystalline silicon according to the present invention.

[0032] Figure 2 This is a diagram illustrating the pulling device of the MCZ method using a horizontal magnetic field used in the present invention.

[0033] Figure 3 This is a diagram illustrating the pulling device of the MCZ method using an intersecting magnetic field used in the present invention. Detailed Description of the Invention

[0034] The present invention will be described in detail below, but the present invention is not limited thereto.

[0035] As described above, in nitrogen-doped single-crystalline silicon, at the as-grown time point, nitrogen donors remain. In particular, in high-resistance crystals with a resistivity of 100 Ωcm or more, the change in resistivity becomes significant due to the remaining nitrogen donors, and the deviation from the true resistivity due to the dopant becomes a problem. As a countermeasure against this problem, methods of measuring resistivity after heat treatment in an oxygen atmosphere or heat treatment in an oxygen atmosphere and neutron irradiation are disclosed in Patent Documents 4 and 5. However, if high-temperature heat treatment is performed in an oxygen atmosphere, a thermal oxide film is formed on the surface of the single-crystalline silicon substrate, and it becomes a problem that accurate resistivity due to the dopant cannot be obtained in a state where the thermal oxide film remains.

[0036] Moreover, a method for measuring the resistivity of single-crystalline silicon is sought, which can measure the accurate resistivity due to the dopant for single-crystalline silicon with a resistivity of 100 Ωcm or more grown by adding nitrogen by the MCZ method.

[0037] The inventors of the present invention repeatedly conducted in-depth research on the above technical problems and found that, first, for the nitrogen donors formed on single-crystalline silicon grown by adding nitrogen, by performing oxidation heat treatment at a temperature of 1100 to 1250 °C for 90 to 240 minutes, a thermal oxide film is formed on the substrate surface to make the nitrogen donors disappear, and the change in resistivity caused by the remaining nitrogen donors can be suppressed. Then, it was confirmed that by removing the thermal oxide film formed on the substrate surface by oxidation heat treatment, the influence of the remaining thermal oxide film on the resistivity can be excluded. As a result, the following method was found: even for high-resistivity nitrogen-doped single-crystalline silicon with a resistivity of 100 Ωcm or more, the accurate resistivity due to the dopant can be measured, and thus the present invention was completed.

[0038] That is, the resistivity measurement method of the single crystal silicon of the present invention measures the resistivity of single crystal silicon with a resistivity of 100 Ωcm or more grown by adding nitrogen by the MCZ method. Among them, after forming a thermal oxide film on the surface of a substrate cut from the single crystal silicon by performing thermal oxidation treatment on the substrate at a temperature of 1100 to 1250 °C for 90 to 240 minutes, the resistivity of the substrate is measured after removing the thermal oxide film from the substrate surface.

[0039] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings of the specification.

[0040] First, with reference to Figure 1 , Figure 2 , Figure 3 an example of the resistivity measurement method of the single crystal silicon according to the embodiment of the present invention will be described.

[0041] In the present invention, nitrogen-added single crystal silicon with a resistivity of 100 Ωcm or more is grown by the magnetic field applied CZ method (MCZ method), but the manner of the magnetic field at this time is not particularly limited, and it can be a horizontal magnetic field or a crucible magnetic field.

[0042] As Figure 2 shown, the single crystal manufacturing apparatus having a horizontal magnetic field includes: a single crystal silicon pulling apparatus (pulling furnace) 1, which is provided with a heater 8 and a heat shield member 12 and has a central axis 10, wherein the heat shield member 12 faces the raw material melt (silicon melt) 5 accommodated in the quartz crucible 7; and a horizontal magnetic field generating apparatus 20, which is disposed around the pulling furnace 1. This single crystal manufacturing apparatus is configured to apply a horizontal magnetic field to the silicon melt 5 by energizing a superconducting coil in the horizontal magnetic field generating apparatus 20 and pull the single crystal silicon 4 in the direction of the central axis 10. The single crystal silicon pulling apparatus 1 further includes a seed crystal 2, a seed crystal holder 3, a graphite crucible 6, a heat insulating member 9, and a cylindrical portion 11.

[0043] As Figure 3 shown, the single crystal manufacturing apparatus having a crucible magnetic field includes: a single crystal silicon pulling apparatus (pulling furnace) 31, which is provided with a heater 38 and a heat shield member 43 and has a central axis 40, wherein the heat shield member 43 faces the raw material melt (silicon melt) 35 accommodated in the quartz crucible 36; and a crucible magnetic field generating apparatus 50, which is disposed around the pulling furnace 31 and has an upper coil (superconducting coil) 50a and a lower coil (superconducting coil) 50b. This single crystal manufacturing apparatus is configured to apply a crucible magnetic field to the silicon melt 35 by energizing the superconducting coils 50a and 50b and pull the single crystal silicon 34 in the direction of the central axis 40. The single crystal silicon pulling apparatus 31 further includes a seed crystal 32, a seed crystal holder 33, a graphite crucible 37, a heat insulating member 39, and a cylindrical portion 42.

[0044] The cruciform magnetic field generating device 50 is provided on a lifting device 50c that can move up and down in the vertical direction. An upper coil 50a and a lower coil 50b are arranged to surround the side surface of the single-crystal silicon pulling device 31. In the cruciform magnetic field, by passing currents in opposite directions through the upper and lower two coils, magnetic lines of force that repel each other up and down are generated. By setting the current values of the upper coil 50a and the lower coil 50b to the same value and passing currents in opposite directions through the upper and lower two coils, a magnetic field distribution that is symmetric up and down and symmetric in the front, back, left, and right is formed. However, at this time, the magnetic field intensity at the magnetic field minimum point 51, which is the intersection of the central axis 40 and the middle plane 41 between the two coils, becomes 0 G (Gauss). For example, by setting the position of the magnetic field minimum point of the cruciform magnetic field to 10 mm downward from the surface of the raw material melt and setting the magnetic field intensity at the intersection of the middle plane 41 between the upper and lower coils and the crucible wall to 1000 G, it is possible to easily manufacture single-crystal silicon with an oxygen concentration of 8.0×10 17 atoms / cm 3 (ASTM’79) or less. In addition, the nitrogen concentration of the single-crystal silicon is preferably 3.0×10 14 atoms / cm 3 or more.

[0045] For such single-crystal silicon, first, by setting the oxygen concentration of the single-crystal silicon to 8.0×10 17 atoms / cm 3 (ASTM’79) or less, not only can the oxygen donor concentration be suppressed, but also the nitrogen donor (NO donor) concentration can be suppressed, and higher-precision resistivity measurement can be performed. However, in single-crystal silicon with low oxygen, the dislocation fixing effect based on oxygen becomes weak. As a result, during a high-temperature and long-time process (heat treatment), the occurrence of slip becomes significant, and thus, during device fabrication, a reduction in the yield rate becomes a problem. Therefore, by setting the nitrogen concentration of the single-crystal silicon to 3.0×10 14 atoms / cm 3 or more, sufficient slip resistance for high-temperature and long-time processes can be imparted. As a result, a reduction in the yield rate during device fabrication can be prevented, and high-precision resistivity measurement can be achieved.

[0046] As described above, by using the MCZ method with a single-crystal silicon pulling device equipped with, for example, a horizontal magnetic field or a cruciform magnetic field, it is possible to grow nitrogen-doped single-crystal silicon with a resistivity of 100 Ωcm or more.

[0047] Next, Figure 1It is a flowchart showing an example of a method for measuring the resistivity of single-crystalline silicon. Specific steps are shown as A to H. After the cultivation of nitrogen-doped single-crystalline silicon with a resistivity of 100 Ωcm or more (step A) is completed, the single-crystalline silicon is subjected to ingot processing (outer diameter grinding) (step B), and then, the single-crystalline silicon is sliced and cut using an inner peripheral blade slicing machine, a wire saw, etc. (step C) to cut out a single-crystalline silicon substrate with a specified thickness. After the grinding and acid etching on the substrate surface (step D) are completed, an oxidation heat treatment for removing nitrogen donors is performed (step E). As the atmosphere during this oxidation heat treatment, a wet oxygen atmosphere or a dry oxygen atmosphere can be set. Then, on the basis of setting it as a dry oxygen atmosphere or a wet oxygen atmosphere, the temperature during the heat treatment is set to 1100 to 1250 °C, and a heat treatment is performed for 90 to 240 minutes while maintaining the above temperature. By performing such an oxidation heat treatment, the nitrogen donors disappear, and it is possible to suppress the change in resistivity caused by the remaining nitrogen donors.

[0048] In addition, if the treatment time of the above heat treatment is set to less than 90 minutes, the remaining nitrogen donors become a problem. If the treatment time of the above heat treatment is set to a time longer than 240 minutes, for example, 250 minutes or more, although the nitrogen donors are completely eliminated, the heater life of the heat treatment furnace is significantly reduced due to the longer treatment time, and the productivity of resistivity measurement deteriorates and becomes a problem. For the above reasons, the treatment time of the above heat treatment is set to 90 to 240 minutes. In addition, regarding the heat treatment furnace used in the heat treatment for removing nitrogen donors, a horizontal furnace or a vertical furnace can be used.

[0049] After the heat treatment for removing nitrogen donors (step E) is completed, the thermal oxide film is removed from the substrate surface. By removing the thermal oxide film, it is possible to eliminate the influence of the remaining thermal oxide film on the resistivity. As a result, even for high-resistivity nitrogen-doped single-crystalline silicon with a resistivity of 100 Ωcm or more, it is possible to measure the accurate resistivity derived from the dopant.

[0050] At this time, for example, etching using hydrofluoric acid (step F) can be performed. Etching using hydrofluoric acid is easy and also advantageous in terms of cost. If the concentration of hydrofluoric acid at this time is 0.1 wt% or more, the thermal oxide film generated by the heat treatment can be removed without any problem.

[0051] After the removal of the oxide film (step F) is completed, it is preferable to further perform grinding on the substrate surface (step G). By grinding the substrate surface, the thermal oxide film can be reliably removed. Preferably, at this time, the grinding is performed using a grinding stone or a grinding pad, and the machining allowance during machining is 5 μm or more. In addition, regarding the grit number of the abrasive grains used in the grinding at this time, it can be rough grinding of about #300 or fine grinding of about #2000.

[0052] As a method for removing the thermal oxide film in this way, if etching and grinding using hydrofluoric acid are carried out, the etching using hydrofluoric acid is easy and advantageous in terms of cost. Thereafter, the thermal oxide film can be reliably removed by grinding the surface of the substrate.

[0053] Then, resistivity measurement is performed (step H). For the measurement, methods such as the four-probe method, the spreading resistance method, and the Hall effect method can be used.

[0054] By using the above conditions, resistivity measurement of the high-resistivity nitrogen-doped single-crystalline silicon with a resistivity of 100 Ωcm or more grown by the MCZ method can be accurately performed.

[0055]

Example

[0056] 360 kg of silicon raw material was added to a quartz crucible with a diameter of 800 mm and melted. A magnetic field was applied, and the pulling of four nitrogen-doped single-crystalline silicon wafers with a diameter of 300 mm and a target resistivity of P-type 2000 Ωcm (dopant: boron) was carried out using four different pulling devices, respectively, for a total of four single-crystalline silicon wafers. For the pulled single-crystalline silicon, ingot processing was performed to produce a single-crystalline silicon substrate, and the produced single-crystalline silicon substrate was heat-treated in an oxygen atmosphere. After the above heat treatment, the thermal oxide film on the surface of the substrate was removed by etching with hydrofluoric acid. After removing the thermal oxide film, grinding was performed using a grindstone with a grit number of #2000, and the resistivity of the silicon substrate was measured using the four-probe method. In addition, in this example and the comparative example, the ratio of the measured resistivity value to the resistivity estimated based on the input amount of the dopant (segregation curve) was defined as "(resistivity_measured value) / (resistivity_estimated value)", and the case where the above ratio was less than 1.05 (less than 5%) was regarded as the case where the resistivity derived from the dopant (boron) could be obtained, and it was assumed that the resistivity could be measured (evaluation ○).

[0057] [Example 1]

[0058] In Example 1, the nitrogen concentration in the single-crystalline silicon was 3.0×10 15 atoms / cm 3 and the oxygen concentration was 1.5×10 17 atoms / cm 3A single-crystalline silicon substrate was fabricated at the position of (ASTM’79), and heat treatment was performed on the single-crystalline substrate in a wet oxygen atmosphere. The combinations of temperature and time during the heat treatment were four types: temperature 1100 °C × time 90 minutes, temperature 1100 °C × time 240 minutes, temperature 1250 °C × time 90 minutes, and temperature 1250 °C × time 240 minutes. After the above heat treatment, the thermal oxide film on the substrate surface was removed by hydrofluoric acid etching, and then grinding was performed with a grindstone having a grit number of #2000, and resistivity measurement was performed by the four-probe method. As a result, in all cases, (measured resistivity) / (estimated resistivity) was 1.00, and it was confirmed that by eliminating nitrogen donors, the resistivity derived from the dopant (boron) was obtained extremely accurately. Table 1 shows the ratio of (measured resistivity) to (estimated resistivity) and whether resistivity measurement can be performed when resistivity measurement is performed under the conditions of Example 1.

[0059] [Table 1]

[0060]

[0061] In addition, resistivity measurement was performed under conditions different from those of Example 1, where the heat treatment for eliminating nitrogen donors was set to a dry oxygen atmosphere and other conditions were the same as those of Example 1. As a result, in all cases, (measured resistivity) / (estimated resistivity) was 1.00, and it was also confirmed that the resistivity derived from the dopant (boron) was obtained extremely accurately. Furthermore, resistivity measurement was performed under conditions different from those of Example 1, where the resistivity in the single crystal was set to 100 Ωcm and other conditions were the same as those of Example 1, and it was also confirmed that the resistivity derived from the dopant (boron) was obtained in all cases.

[0062] [Example 2]

[0063] In Example 2, the oxygen concentration in the single-crystalline silicon was set to 8.0×10 17 atoms / cm 3 (ASTM’79), and other conditions were set to the same conditions as those of Example 1, and resistivity measurement was performed. As a result, in all cases, (measured resistivity) / (estimated resistivity) was 1.01 or less, and it was confirmed that by eliminating nitrogen donors, the resistivity derived from the dopant (boron) was obtained accurately. Table 2 shows the ratio of (measured resistivity) to (estimated resistivity) and whether resistivity measurement can be performed when resistivity measurement is performed under the conditions of Example 2.

[0064] [Table 2]

[0065]

[0066] In addition, different from Example 2, the heat treatment for eliminating nitrogen donors was set to a dry oxygen atmosphere, and resistivity measurements were carried out under the same conditions as in Example 2. As a result, in all cases, (measured resistivity) / (estimated resistivity) was 1.01 or less, and it was also confirmed that the resistivity derived from the dopant (boron) was accurately obtained. In addition, different from Example 2, the resistivity in the single crystal was set to 100 Ωcm, and resistivity measurements were carried out under the same conditions as in Example 2. It was also confirmed that the resistivity derived from the dopant (boron) was obtained in all cases.

[0067] [Example 3]

[0068] In Example 3, the nitrogen concentration in the single-crystalline silicon was set to 3.0×10 14 atoms / cm 3 , and other conditions were set to the same conditions as in Example 1, and resistivity measurements were carried out. As a result, in all cases, (measured resistivity) / (estimated resistivity) was 1.00, and it was confirmed that by eliminating nitrogen donors, the resistivity derived from the dopant (boron) was obtained extremely accurately. Table 3 shows the ratio of (measured resistivity) to (estimated resistivity) and whether resistivity measurement can be carried out when resistivity measurements are carried out under the conditions of Example 3.

[0069] [Table 3]

[0070]

[0071] In addition, different from Example 3, the heat treatment for eliminating nitrogen donors was set to a dry oxygen atmosphere, and resistivity measurements were carried out under the same conditions as in Example 3. As a result, in all cases, (measured resistivity) / (estimated resistivity) was 1.00, and it was also confirmed that the resistivity derived from the dopant (boron) was obtained extremely accurately. In addition, different from Example 3, the resistivity in the single crystal was set to 100 Ωcm, and resistivity measurements were carried out under the same conditions as in Example 3. It was also confirmed that the resistivity derived from the dopant (boron) was obtained in all cases.

[0072] [Example 4]

[0073] In Example 4, the oxygen concentration in the single-crystalline silicon was set to 9.0×10 17 atoms / cm 3(ASTM’79), other conditions were set to the same conditions as in Example 1, and resistivity measurements were carried out. As a result, in all cases, (measured resistivity) / (estimated resistivity) was 1.03 - 1.04, and the resistivity derived from the dopant (boron) was obtained. Comparing this result with the results of Examples 1 and 2, it can be seen that more accurate measurements can be carried out in Examples 1 and 2. Therefore, when the oxygen concentration is set to 8.0×10 17 atoms / cm 3 (ASTM’79) or less, the ratio can be made 1.01 or less, so it can be said that it is more preferable. Table 4 shows the ratio of (measured resistivity) to (estimated resistivity) and whether resistivity measurement can be carried out when resistivity measurement is carried out under the conditions of Example 4.

[0074] [Table 4]

[0075]

[0076] [Comparative Example 1]

[0077] In Comparative Example 1, the combination of temperature and time during heat treatment was set to four types: temperature 900°C × time 90 minutes, temperature 900°C × time 240 minutes, temperature 1000°C × time 90 minutes, and temperature 1000°C × time 240 minutes. Other conditions were set to the same conditions as in Example 1, and resistivity measurements were carried out. As a result, (measured resistivity) / (estimated resistivity) was 1.82 - 3.40, and nitrogen donors remained after heat treatment, resulting in a change in resistivity, and as a result, the accurate resistivity derived from the dopant (boron) could not be obtained. Table 5 shows the ratio of (measured resistivity) to (estimated resistivity) and whether resistivity measurement can be carried out when resistivity measurement is carried out under the conditions of Comparative Example 1.

[0078] [Table 5]

[0079]

[0080] In addition, different from Comparative Example 1, when the temperature and time during heat treatment were changed to temperature 1000°C × time 480 minutes and other conditions were the same as those in Comparative Example 1, resistivity measurement was carried out. As a result, (measured resistivity) / (estimated resistivity) was 1.50, and the accurate resistivity derived from the dopant (boron) could not be obtained.

[0081] [Comparative Example 2]

[0082] In Comparative Example 2, the combinations of temperature and time during heat treatment were set to a total of four types: temperature 1100 °C × time 30 minutes, temperature 1100 °C × time 60 minutes, temperature 1250 °C × time 30 minutes, and temperature 1250 °C × time 60 minutes. Other conditions were set to the same conditions as in Example 1 for resistivity measurement. As a result, (measured resistivity) / (estimated resistivity) was 1.05 to 1.45, and nitrogen donors remained after heat treatment, resulting in a change in resistivity. As a result, an accurate resistivity derived from the dopant (boron) could not be obtained. Table 6 shows the ratio of (measured resistivity) to (estimated resistivity) and whether resistivity measurement could be performed under the conditions of Comparative Example 2.

[0083] [Table 6]

[0084]

[0085] As described above, according to the embodiments of the present invention, for single-crystalline silicon with a resistivity of 100 Ωcm or more grown by adding nitrogen by the MCZ method, by performing oxidative heat treatment at a temperature of 1100 to 1250 °C for 90 to 240 minutes to eliminate nitrogen donors, it is possible to suppress the change in resistivity caused by the remaining nitrogen donors, remove the thermal oxide film formed on the substrate surface by the oxidative heat treatment, and as a result, even for high-resistivity nitrogen-doped single-crystalline silicon with a resistivity of 100 Ωcm or more, an accurate resistivity derived from the dopant can be measured.

[0086] In addition, the present invention is not limited to the above-described embodiments. The above-described embodiments are illustrative, and any solution having a structure substantially the same as the technical idea described in the claims of the present invention and achieving the same effect is included in the technical scope of the present invention.

Claims

1. A method for measuring the resistivity of single crystal silicon, which measures the resistivity of single crystal silicon with a resistivity of 100 Ωcm or more grown by adding nitrogen through the MCZ method, characterized in that, by subjecting a substrate cut from the single crystal silicon to thermal oxidation treatment at a temperature of 1100 to 1250 °C for 90 to 240 minutes to form a thermal oxide film on the surface of the substrate, after removing the thermal oxide film from the surface of the substrate, measuring the resistivity of the substrate.

2. The method for measuring the resistivity of single crystal silicon according to claim 1, characterized in that, after removing the thermal oxide film on the surface of the substrate by etching with hydrofluoric acid, grinding the surface of the substrate.

3. The method for measuring the resistivity of single crystal silicon according to claim 1 or 2, characterized in that, Set the nitrogen concentration of the single-crystalline silicon to 3.0×10 14 atoms / cm 3 or more, and set the oxygen concentration based on ASTM’79 to 8.0×10 17 atoms / cm 3 or less.

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