Method for Controlling Donor Concentration in Single-Crystalline Silicon Substrate

Abstract

The present invention is a method for controlling the donor concentration in a single-crystalline silicon substrate, characterized in that, based on the obtained correlation, the oxygen concentration and carbon concentration of the single-crystalline silicon substrate for controlling the donor concentration prepared in the preparation process are adjusted so that the donor concentration in the single-crystalline silicon substrate for controlling the donor concentration after the second heat treatment process becomes a target value. Thereby, a method for controlling the donor concentration in a single-crystalline silicon substrate is provided, which can reduce the deviation of the donor concentration caused by the single-crystalline silicon substrate and can control the donor concentration with high precision.

Description

Technical Field

[0001] The present invention relates to a method for controlling the donor concentration in a single-crystalline silicon substrate. Background Art

[0002] In an IGBT (Insulated Gate Bipolor Transistor) and a diode of a switching element, for high speed and low loss, a structure in which a field stop layer (or a buffer layer) is formed on the back side of a thin wafer is used (Patent Document 1). Further, in order to also have a soft recovery characteristic, a structure in which a wide buffer layer is formed near the center in the wafer thickness direction has been proposed (Patent Document 2).

[0003] As a method for forming the above buffer layer and wide buffer layer, there is a method of forming a donor by proton irradiation and heat treatment. For example, in Patent Document 1, a method is disclosed in which after thinning the wafer, proton irradiation is performed and heat treatment (for example, 300°C to 500°C) is carried out to form a buffer layer. Further, in Patent Document 2, a method is disclosed in which the dose of protons at the time of proton irradiation is 1×10 11 atoms / cm 2 or more and 1×10 14 atoms / cm 2 or less, and by performing heat treatment at 250°C or more and 500°C or less, a wide buffer layer is formed.

[0004] In the method of forming a buffer layer by proton irradiation and heat treatment, compared with the case of forming a buffer layer by ion implantation of a normal dopant and activation heat treatment, there are the following advantages: Since a wide buffer layer can be formed even in a deeper region, improvement in device characteristics can be expected. Further, since a donor can be formed by heat treatment at a lower temperature, problems such as cracks and scratches in the process after thinning the wafer can be reduced.

[0005] On the other hand, it is known that the concentration of donors formed by proton irradiation and heat treatment is affected by the concentration of light element impurities, i.e., oxygen and carbon, in the single-crystalline silicon substrate. For example, in Patent Document 2, it is described that the concentration of oxygen atoms in the region where a wide buffer layer is formed by proton irradiation and heat treatment is preferably 1×10 16 atoms / cm 3 or more.

[0006] Further, in Patent Document 3, it is described that in order to form a high-concentration region of donors, the semiconductor substrate may be an MCZ (Magnetic Field Applied Czochralski) substrate, or the average oxygen concentration in the semiconductor substrate may be 1.0×10 16 / cm3 Above, 1.0×10 18 / cm 3 Below, the average carbon concentration in the semiconductor substrate can be 1.0×10 14 / cm 3 Above, 3.0×10 15 / cm 3 Below.

[0007] In addition, in Non-Patent Document 1, it is shown that the integral donor concentration of the field blocking layer formed by proton irradiation and heat treatment has the following tendency: the higher the oxygen concentration, the higher it is, and the higher the carbon concentration, the higher it is.

[0008] Thus, since the concentration of donors formed by proton irradiation and heat treatment is affected by the oxygen concentration and carbon concentration in the single-crystalline silicon substrate, there is a case where the donor concentration deviates due to differences in the single-crystalline silicon substrate.

[0009] Prior Art Documents

[0010] Patent Documents

[0011] Patent Document 1: Japanese Patent No. 3684962 Gazette

[0012] Patent Document 2: Japanese Patent No. 5104314 Gazette

[0013] Patent Document 3: Japanese Patent No. 6311840 Gazette

[0014] Non-Patent Documents

[0015] Non-Patent Document 1: H.J. Schulze et.al, Proceedings of the 2016 28 th International Symposium on Power Semiconductor Devices and ICs (ISPSD, International Conference on Power Semiconductor Devices and Integrated Circuits), p. 355. Summary of the Invention

[0016] (1) Technical Problem to be Solved

[0017] The method of forming donors by proton irradiation and heat treatment is an effective method for improving device characteristics and reducing process load, but the state of donors becomes complicated due to the influence of light elements, so it is difficult to strictly control the donor concentration.

[0018] In the known art, it is disclosed that if the oxygen concentration is above a certain value, the donorization rate of protons increases; the higher the oxygen concentration or the carbon concentration, the more the donor concentration increases, but this is not always the case, and it is difficult to control the donor concentration only by the oxygen concentration or the carbon concentration, and there is a problem that the donor concentration sometimes deviates.

[0019] The present invention has been completed in view of the above problems, and an object thereof is to provide a method for controlling the donor concentration in a single-crystalline silicon substrate, which can reduce the deviation of the donor concentration caused by the single-crystalline silicon substrate and can control the donor concentration with high precision in the manufacturing process of a device for controlling the donor concentration by proton irradiation and heat treatment.

[0020] (II) Technical solution

[0021] The present invention has been completed to solve the above problems, and provides a method for controlling the donor concentration in a single-crystalline silicon substrate, which controls the donor concentration by performing the following steps: a preparation step of preparing a single-crystalline silicon substrate for controlling the donor concentration; a second proton irradiation step of irradiating protons on the prepared single-crystalline silicon substrate; and a second heat treatment step of performing heat treatment on the single-crystalline silicon substrate after the second proton irradiation step, having: a first proton irradiation step of pre-irradiating protons on a plurality of test single-crystalline silicon substrates having different oxygen concentrations and carbon concentrations before performing the preparation step; a first heat treatment step of performing heat treatment on the plurality of test silicon substrates after the first proton irradiation step; a measurement step of measuring the increase in donors generated in the plurality of test single-crystalline silicon substrates after the first heat treatment step; and a correlation acquisition step of acquiring the correlation between the measured increase in donors and the product of the oxygen concentration and the carbon concentration of the plurality of test silicon substrates, and based on the obtained correlation, adjusting the oxygen concentration and the carbon concentration of the single-crystalline silicon substrate for controlling the donor concentration prepared in the preparation step so that the donor concentration in the single-crystalline silicon substrate for controlling the donor concentration after the second heat treatment step becomes a target value.

[0022] According to such a method for controlling the donor concentration in a single-crystalline silicon substrate, if the oxygen concentration and the carbon concentration of the single-crystalline silicon substrate for controlling the donor concentration are adjusted based on the correlation between the increase in donors in the plurality of test single-crystalline silicon substrates after the first heat treatment step and the product of the oxygen concentration and the carbon concentration obtained in advance from the test single-crystalline silicon substrates to control the donor concentration, the deviation of the donor concentration caused by the single-crystalline silicon substrate can be reduced, and the donor concentration can be controlled with high precision.

[0023] At this time, preferably, the product of the oxygen concentration and the carbon concentration of the single-crystalline silicon substrate for controlling the donor concentration prepared in the preparation step is 1×10 32 [(atoms / cm 3 )]2 Hereinafter, in the second heat treatment step, the heat treatment temperature is 300 to 400 °C.

[0024] Thus, if the product of the oxygen concentration and the carbon concentration is 1×10 32 [(atoms / cm 3 )] 2 Hereinafter, when the temperature of the second heat treatment is 300 to 400 °C, a strong negative correlation is obtained between the product of the oxygen concentration and the carbon concentration and the increase in donors. Therefore, if the oxygen concentration and the carbon concentration of the single crystal silicon substrate for controlling the donor concentration are adjusted based on the correlation between the increase in donors and the product of the oxygen concentration and the carbon concentration in the multiple test single crystal silicon substrates after the first heat treatment step obtained in advance from multiple test single crystal silicon substrates, the deviation of the donor concentration caused by the single crystal silicon substrate can be further reduced, and the donor concentration can be controlled with higher precision. The lower limit of the product of the oxygen concentration and the carbon concentration is not particularly limited, and is preferably 1×10 28 [(atoms / cm 3 )] 2 or so.

[0025] In addition, at this time, preferably, the product of the oxygen concentration and the carbon concentration of the single crystal silicon substrate for controlling the donor concentration prepared in the preparation step is 2×10 33 [(atoms / cm 3 )] 2 Hereinafter, in the second heat treatment step, the heat treatment temperature is 425 to 500 °C.

[0026] Thus, if the product of the oxygen concentration and the carbon concentration is 2×10 33 [(atoms / cm 3 )] 2 Hereinafter, when the heat treatment temperature in the second heat treatment step is 425 to 500 °C, a strong positive correlation is obtained between the product of the oxygen concentration and the carbon concentration and the increase in donors. Therefore, if the oxygen concentration and the carbon concentration of the single crystal silicon substrate for controlling the donor concentration are adjusted based on the correlation between the increase in donors and the product of the oxygen concentration and the carbon concentration in the multiple test single crystal silicon substrates after the first heat treatment step obtained in advance from multiple test single crystal silicon substrates, the deviation of the donor concentration caused by the single crystal silicon substrate can be further reduced, and the donor concentration can be controlled with higher precision.

[0027] In addition, if the oxygen concentration becomes high, there may be a problem that the resistivity changes due to the generation of oxygen-related thermal donors in the region where protons are not irradiated in addition to the donors formed by proton irradiation and heat treatment. Therefore, it is preferable that the product of the oxygen concentration and the carbon concentration is 2×1033 [(atoms / cm 3 )] 2 as follows.

[0028] In addition, even when the product of the oxygen concentration and the carbon concentration exceeds 2×10 33 [(atoms / cm 3 )², a positive correlation is obtained between the product of the oxygen concentration and the carbon concentration and the increase in the donor concentration.

[0029] In the second heat treatment step, when the heat treatment temperature is 400 to 425 °C, a correlation intermediate between the cases where the heat treatment temperature is 300 to 400 °C and 425 to 500 °C is obtained.

[0030] (III) Advantageous Effects

[0031] As described above, according to the method for controlling the donor concentration in the single crystal silicon substrate of the present invention, by adjusting the oxygen concentration and the carbon concentration of the single crystal silicon substrate, the deviation of the donor concentration caused by the single crystal silicon substrate can be reduced, and thus the donor concentration can be controlled with high precision. In addition, when the present invention controls the donor concentration in the FZ single crystal silicon substrate capable of reducing the product of the oxygen concentration and the carbon concentration, the donor concentration can be controlled with high precision, and thus it is particularly suitable for using the float zone (FZ) single crystal silicon substrate in power devices. Description of the Drawings

[0032] Figure 1 is a diagram showing an example of the method for controlling the donor concentration in the single crystal silicon substrate of the present invention.

[0033] Figure 2 is a diagram showing the depth direction distribution of the increase in the donor concentration measured by performing the treatment with the heat treatment temperature set to 350 °C in Experimental Example 1 (the ○ mark represents Substrate A, and the △ mark represents Substrate B).

[0034] Figure 3 is a diagram showing the depth direction distribution of the increase in the donor concentration measured by performing the treatment with the heat treatment temperature set to 450 °C in Experimental Example 1 (the ○ mark represents Substrate A, and the △ mark represents Substrate B).

[0035] Figure 4 is a diagram showing the relationship between the integrated donor increase amount and the heat treatment temperature measured in Experimental Example 1 (the ○ mark represents Substrate A, and the △ mark represents Substrate B).

[0036] Figure 5 is a diagram showing the relationship between the integrated donor increase amount and the nitrogen concentration measured in Experimental Example 2.

[0037] Figure 6It is a graph showing the relationship between the integral donor increase measured in Experimental Example 2 and the oxygen concentration.

[0038] Figure 7 It is a graph showing the relationship between the integral donor increase measured in Experimental Example 2 and the carbon concentration.

[0039] Figure 8 It is a graph showing the relationship between the integral donor increase measured in Experimental Example 2 and Example 1, and the product of the oxygen concentration and the carbon concentration.

[0040] Figure 9 It is a graph showing the relationship between the integral donor increase measured in Experimental Example 3 and the nitrogen concentration.

[0041] Figure 10 It is a graph showing the relationship between the integral donor increase measured in Experimental Example 3 and the oxygen concentration (the ○ mark represents the FZ single-crystalline silicon substrate, and the □ mark represents the MCZ single-crystalline silicon substrate).

[0042] Figure 11 It is a graph showing the relationship between the integral donor increase measured in Experimental Example 3 and the carbon concentration (the ○ mark represents the FZ single-crystalline silicon substrate, and the □ mark represents the MCZ single-crystalline silicon substrate).

[0043] Figure 12 It is a graph showing the relationship between the integral donor increase measured in Experimental Example 3 and Example 2, and the product of the oxygen concentration and the carbon concentration (the ○ mark represents the FZ single-crystalline silicon substrate, and the □ mark represents the MCZ single-crystalline silicon substrate).

[0044] Figure 13 It is a graph showing the relationship between the integral donor increase measured in Experimental Example 4 and the oxygen concentration (the ○ mark represents the FZ single-crystalline silicon substrate, and the □ mark represents the MCZ single-crystalline silicon substrate).

[0045] Figure 14 It is a graph showing the relationship between the integral donor increase measured in Experimental Example 4 and the carbon concentration (the ○ mark represents the FZ single-crystalline silicon substrate, and the □ mark represents the MCZ single-crystalline silicon substrate).

[0046] Figure 15 It is a graph showing the relationship between the integral donor increase measured in Experimental Example 4 and the product of the oxygen concentration and the carbon concentration (the ○ mark represents the FZ single-crystalline silicon substrate, and the □ mark represents the MCZ single-crystalline silicon substrate). Detailed implementation mode

[0047] The present invention will be described in detail below, but the present invention is not limited thereto.

[0048] As described above, in the prior art, the donor concentration is controlled by proton irradiation and heat treatment. However, even when the conditions of proton irradiation and heat treatment are set to be the same, there is a problem of donor concentration deviation due to the single-crystalline silicon substrate. In addition, it has been disclosed that: regarding the concentration of donors formed by proton irradiation and heat treatment, the higher the oxygen concentration in the single-crystalline silicon substrate, the higher it is, and the higher the carbon concentration, the higher it is.

[0049] After repeated and in-depth research, the present inventors have found that there is also a situation where the relationship between the increase in donors in the case of performing proton irradiation and heat treatment on a single-crystalline silicon substrate and the oxygen concentration and carbon concentration in the single-crystalline silicon substrate is not a positive correlation as considered in the prior art. Moreover, it has been found that there is a strong correlation between the product of the oxygen concentration and the carbon concentration and the donor concentration, and the present invention has been completed.

[0050] Hereinafter, a method for controlling the donor concentration in the single-crystalline silicon substrate of the present invention will be described with reference to the accompanying drawings. In addition, Figure 1 the single-crystalline silicon substrate in the parentheses represents the single-crystalline silicon substrate processed in each process.

[0051] First, prepare a plurality of test single-crystalline silicon substrates. The oxygen concentration and carbon concentration of each of the plurality of test single-crystalline silicon substrates prepared here are different. In addition, the conditions other than the oxygen concentration and carbon concentration can be the same as those of the single-crystalline silicon substrate (control object single-crystalline silicon substrate) that actually controls the donor concentration.

[0052] In addition, the method for preparing the test single-crystalline silicon substrate is not particularly limited in the present invention. For example, a silicon wafer is cut out from a single-crystalline silicon, and after chemical etching treatment of the silicon wafer to remove cutting damage, mechanical chemical polishing is performed, thereby enabling the preparation of a test single-crystalline silicon substrate.

[0053] [First Proton Irradiation Step S1]

[0054] Next, irradiate protons on the plurality of test single-crystalline silicon substrates (first proton irradiation step). At this time, an oxide film or the like can be formed on the single-crystalline silicon substrate before irradiating protons. It is desired that the conditions of proton irradiation conform to the proton irradiation conditions of the second proton irradiation step ( Figure 1 S6) of the semiconductor device manufacturing process, which is the control object described in detail later. In addition, when an absorber is used to adjust the range of protons, it is desired that its material and thickness also conform to the second proton irradiation step ( Figure 1 S6).

[0055] [First Heat Treatment Step S2]

[0056] Next, a first heat treatment step is performed in which multiple test silicon substrates after the first proton irradiation are heat-treated. It is desired that the heat treatment conditions conform to the heat treatment conditions of the second heat treatment step ([S7] of Figure 1 ), which is the control object described in detail later, of the manufacturing process of the semiconductor device.

[0057] [Measurement step S3]

[0058] Next, in the measurement step, the donor concentration (donor increase amount) generated in multiple test single-crystalline silicon substrates after the first heat treatment step is measured. There is no particular limitation on the method for measuring the donor concentration. For example, the spreading resistance measurement method (SR method) can be used.

[0059] For example, in the SR method, two probes are brought into contact with the polished surface of a sample that has been subjected to inclined polishing, the spreading resistance between the probes is measured, the resistivity is calculated based on the measured spreading resistance and using a calibration curve, and furthermore, based on the relationship between the existing resistivity and the donor concentration and according to the calculated resistivity above, the donor concentration is obtained, thereby obtaining the depth direction distribution of the donor concentration.

[0060] Next, the donor concentration (N D (x)) at each measured depth x is subtracted from the donor concentration in the substrate (a deeper region where the donor concentration is substantially constant), and the donor increase amount (ΔN D (x)) at each depth x is obtained. Moreover, taking the donor increase amount as a band characteristic value, and by integrating the donor increase amount in the depth direction, the integrated donor increase amount can be obtained. Alternatively, taking the donor increase amount as a band characteristic value, the maximum donor increase amount at the depth position where the donor increase amount is the largest in the depth direction can be obtained.

[0061] [Correlation acquisition step S4]

[0062] Next, a correlation acquisition step (S4 of Figure 1 ) is performed. In the correlation acquisition step, the donor increase amount measured in the measurement step (S3 of Figure 1 ) is made to correspond to the product of the oxygen concentration and the carbon concentration of multiple test single-crystalline silicon substrates, thereby obtaining the correlation between the product of the oxygen concentration and the carbon concentration and the donor increase amount.

[0063] [Preparation step S5]

[0064] Next, based on the correlation obtained as described above, the oxygen concentration and the carbon concentration of the single-crystalline silicon substrate prepared in the preparation step are adjusted so that the donor concentration of the single-crystalline silicon substrate after the heat treatment step becomes the target value (S5 of Figure 1 ).

[0065] At this time, when the heat treatment temperature in the second heat treatment process described later is 300 to 400 °C, it is desirable that the product of the oxygen concentration and the carbon concentration of the test single crystal silicon substrate is 1×10 32 [(atoms / cm 3 )] 2 or less. The lower limit of the product of the oxygen concentration and the carbon concentration is not particularly limited, and it is preferably 1×10 28 [(atoms / cm 3 )] 2 or so under the current technology.

[0066] In addition, at this time, when the heat treatment temperature in the second heat treatment process described later is 425 to 500 °C, it is desirable that the product of the oxygen concentration and the carbon concentration of the test single crystal silicon substrate is 2×10 33 [(atoms / cm 3 )] 2 or less. The lower limit of the product of the oxygen concentration and the carbon concentration is not particularly limited, and it is preferably 1×10 28 [(atoms / cm 3 )] 2 or so under the current technology.

[0067] The method for adjusting the oxygen concentration and the carbon concentration of the single crystal silicon substrate, which is the control object to be prepared, is not particularly limited in the present invention. For example, a method of adjusting the raw materials and cultivation conditions when cultivating single crystal silicon can be used. In addition, by performing heat treatment on the single crystal silicon substrate, oxygen and carbon diffuse inward in the single crystal silicon substrate, so that the oxygen concentration and carbon concentration of the single crystal silicon substrate can be adjusted. In addition, by ion-implanting oxygen and carbon from the surface of the single crystal silicon substrate, the oxygen concentration and carbon concentration of the single crystal silicon substrate can be adjusted.

[0068] [Second proton irradiation process S6]

[0069] Next, the prepared control object single crystal silicon substrate is subjected to a second proton irradiation process ( Figure 1 S6). The conditions for proton irradiation performed here are preferably the same as those of the first proton irradiation process ( Figure 1 S1). For example, the acceleration voltage in proton irradiation can be made 8 MV, and for example, the proton dose can be made 2×10 14 atoms / cm 2 .

[0070] [Second heat treatment process S7]

[0071] Next, the single crystal silicon substrate of the control object irradiated with protons is subjected to a second heat treatment process ( Figure 1 S7). The conditions for heat treatment performed here are preferably the same as those of the first heat treatment process ( Figure 1S2) The same conditions. Regarding the heat treatment conditions, for example, the treatment time can be set to 20 minutes to 3 hours and carried out in an atmosphere such as nitrogen, oxygen, or hydrogen.

[0072] If it is the above-described method for controlling the donor concentration of the present invention, the deviation of the donor concentration caused by the single-crystalline silicon substrate can be reduced, and the donor concentration can be controlled with high precision.

[0073] In the present invention, in order to reduce the deviation of the donor concentration caused by the single-crystalline silicon substrate and control the donor concentration with high precision, the reason for using the above-described method for controlling the donor concentration of the single-crystalline silicon substrate is the insight obtained from the following experiment.

[0074] (Experimental Example 1)

[0075] Two FZ single-crystalline silicon substrates (substrate A and substrate B) made of single-crystalline silicon grown by the floating zone method (FZ method) were prepared. Each substrate is a phosphorus-doped N-type, and the dopant concentration is 7×10 13 ~8×10 13 atoms / cm 3 .

[0076] Substrate A is a substrate made of single-crystalline silicon grown by the FZ method using a normal polysilicon ingot as a raw material. The oxygen concentration is 2.0×10 15 atoms / cm 3 , the carbon concentration is 8.9×10 14 atoms / cm 3 , and the nitrogen concentration is 1.2×10 15 atoms / cm 3 .

[0077] Substrate B is a substrate made of single-crystalline silicon grown by the FZ method using a single-crystalline silicon ingot grown by the CZ method as a raw material. The oxygen concentration is 1.2×10 16 atoms / cm 3 , the carbon concentration is 1.0×10 15 atoms / cm 3 , and the nitrogen concentration is 1.5×10 15 atoms / cm 3 .

[0078] The oxygen concentration was measured by the infrared absorption method (using the conversion coefficient specified by JEIDA), and the carbon concentration and nitrogen concentration were measured by secondary ion mass spectrometry (SIMS).

[0079] Next, the prepared single-crystalline silicon substrates were irradiated with protons. At this time, the proton dose was 2×10 14 atoms / cm 2, the acceleration voltage of the proton is 8 MV. In addition, in order to make the range of the proton be about 15 μm, when irradiating the proton, a plurality of aluminum foils with a total thickness of about 410 μm are provided as an absorber on the upstream side of the single-crystalline silicon substrate.

[0080] Next, heat treatment was performed on the single-crystalline silicon substrate after proton irradiation. At this time, the heat treatment conditions were set as follows: the temperature varied in the range of 300 to 550 °C, the time was 60 minutes, and the atmosphere was a nitrogen atmosphere.

[0081] Next, the depth-direction distribution of the donor concentration was measured on the heat-treated single-crystalline silicon substrate by the spreading resistance method (SR method).

[0082] The conditions in Experimental Example 1 are shown in Table 1.

[0083] [Table 1]

[0084]

[0085] Next, the donor increase amount (ΔN D (x)) at each depth x measured above was obtained by subtracting the donor concentration in the substrate (the average value of the donor concentration at a depth of about 60 to 70 μm, where the donor concentration is substantially constant) from the donor concentration (N D (x)) at each depth x.

[0086] In Figure 2 and Figure 3 , examples of the depth-direction distribution of the donor increase amount thus obtained are shown. Figure 2 is the case where the heat treatment temperature is 350 °C, Figure 3 is the case where the heat treatment temperature is 450 °C. In Figure 2 and Figure 3 , the different markings represent different substrates. 〇 represents the case of substrate A, and △ represents the case of substrate B.

[0087] Next, the integrated donor increase amount was obtained by integrating the donor increase amount in the depth direction. In Figure 4 , the relationship between the obtained integrated donor increase amount and the heat treatment temperature is shown. Figure 4 In

[0088] According to Figure 4From the results, it can be seen that in the range of heat treatment temperatures from 300 to 525 °C, the integral donor concentration increases. In addition, since peaks are observed near 375 °C and 475 °C, it is considered that at least two types of donors are formed corresponding to the heat treatment temperature. Moreover, regarding the increase in the integral donor, in the range of heat treatment temperatures from 300 to 400 °C, the increase in the integral donor of substrate A is higher, and in the range of heat treatment temperatures from 425 to 500 °C, the increase in the integral donor of substrate B is higher. Thus, it can be seen that the difference in the increase in the donor caused by the difference in the single-crystalline silicon substrate varies according to the heat treatment temperature.

[0089] (Experimental Example 2)

[0090] Multiple FZ single-crystalline silicon substrates with different oxygen concentrations and carbon concentrations were prepared. The multiple FZ single-crystalline silicon substrates include: a substrate made of single-crystalline silicon grown by the FZ method using a normal polysilicon ingot as a raw material; and a substrate made of single-crystalline silicon grown by the FZ method using a single-crystalline silicon ingot grown by the CZ method as a raw material. The dopant type, dopant concentration, oxygen concentration, carbon concentration, nitrogen concentration, diameter, and crystal plane orientation are as follows.

[0091] Dopant type / concentration: phosphorus / 6.0×10 13 ~8.7×10 13 atoms / cm 3 、

[0092] Oxygen concentration: 2.0×10 15 ~2.1×10 16 atoms / cm 3 、

[0093] Carbon concentration: 6.4×10 14 ~4.8×10 15 atoms / cm 3 、

[0094] Nitrogen concentration: 3.6×10 14 ~3.5×10 15 atoms / cm 3 、

[0095] Diameter: 200 mm,

[0096] Crystal plane orientation: (100).

[0097] The oxygen concentration was measured by the infrared absorption method (using the conversion coefficient specified by JEIDA), and the carbon concentration and nitrogen concentration were measured by secondary ion mass spectrometry (SIMS).

[0098] Next, the prepared single-crystalline silicon substrates were irradiated with protons. At this time, the dose of protons was 2×10 14atoms / cm 2 , the acceleration voltage of the protons was 8 MV. In addition, in order to make the range of the protons be about 15 μm, when irradiating the protons, a plurality of aluminum foils with a total thickness of about 410 μm were provided as absorbers on the upstream side of the single-crystalline silicon substrate.

[0099] Next, heat treatment was performed on the single-crystalline silicon substrate after proton irradiation. At this time, the heat treatment conditions were set as follows: the temperature was 350 °C, the time was 60 minutes, and the atmosphere was a nitrogen atmosphere.

[0100] Next, the depth-direction distribution of the donor concentration was measured on the heat-treated single-crystalline silicon substrate by the spreading resistance method (SR method).

[0101] The conditions in Experimental Example 2 are shown in Table 2.

[0102] [Table 2]

[0103] Substrate cultivation method FZ method Dopant type Phosphorus <![CDATA[Dopant concentration [atoms / cm 3 > <![CDATA[6.0×10 13 ~8.7×10 13 > Raw material silicon Polycrystalline silicon ingot, single crystal silicon ingot grown by CZ method <![CDATA[Oxygen concentration [atoms / cm 3 > <![CDATA[2.0×10 15 ~2.1×10 16 > <![CDATA[Carbon concentration [atoms / cm 3 > <![CDATA[6.4×10 14 ~4.8×10 15 > <![CDATA[Nitrogen concentration [atoms / cm 3 > <![CDATA[3.6×10 14 ~3.5×10 15 > Diameter [mm] 200 Crystal orientation (100) <![CDATA[Proton dose [atoms / cm 2 > <![CDATA[2×10 14 > Accelerating voltage [MV] 8 Range of protons [μm] Approximately 15 Absorber substrate Aluminum foil Total thickness of absorber [μm] Approximately 410 Heat treatment temperature [°C] 350 Heat treatment time [minutes] 60 Atmosphere Nitrogen atmosphere Measurement of depth direction distribution of donor concentration Spreading resistance measurement method (SR method)

[0104] Next, from the donor concentration (N D ( x )) measured at each depth x above, the donor concentration in the substrate (a deeper region where the donor concentration is substantially constant) (the average value of the donor concentration at a depth of about 60 to 70 μm) was subtracted to obtain the donor increase amount (ΔN D (x)) at each depth x.

[0105] Next, by integrating the donor increase amount in the depth direction, the integrated donor increase amount was obtained, and the relationships with the nitrogen concentration, oxygen concentration, and carbon concentration in the single-crystalline silicon substrate were investigated.

[0106] In Figure 5 , the relationship between the integrated donor increase amount and the nitrogen concentration is shown, in Figure 6 , the relationship between the integrated donor increase amount and the oxygen concentration is shown, in Figure 7 , the relationship between the integrated donor increase amount and the carbon concentration is shown, and in Figure 8 , the relationship between the integrated donor increase amount and the product of the oxygen concentration and the carbon concentration is shown.

[0107] According to Figure 5 , the result shows that the integrated donor increase amount does not depend on the nitrogen concentration. In addition, according to Figure 6 and Figure 7 , the result shows that the integrated donor increase amount has the following tendency: the higher the oxygen concentration, the lower it is, the higher the carbon concentration, the lower it is, and the deviation is relatively large. Moreover, as Figure 8 shows, the integrated donor increase amount has a strong negative correlation with the product of the oxygen concentration and the carbon concentration. That is, as will be described later Figure 12The case where the heat treatment temperature is 450 °C shows an inverse correlation.

[0108] From Figure 4 the results, the range of the heat treatment temperature where the product of the oxygen concentration and the carbon concentration (substrate A < substrate B) and the increase in the integral donor (substrate A > substrate B) have a negative correlation is 300 - 400 °C. Therefore, according to Figure 4 and Figure 8 the results, for the increase in the donor amount in the case of a heat treatment temperature of 300 - 400 °C, when the product of the oxygen concentration and the carbon concentration is at least 1×10 32 [(atoms / cm 3 )] 2 or less, the increase in the donor amount has a strong negative correlation with the product of the oxygen concentration and the carbon concentration. By adjusting the oxygen concentration and the carbon concentration in the single crystal silicon substrate based on this correlation, the donor concentration can be controlled with high precision.

[0109] (Experimental Example 3)

[0110] FZ single crystal silicon substrates similar to those in Experimental Example 2 were prepared. In addition, multiple MCZ single crystal silicon substrates with different oxygen concentrations and carbon concentrations were also prepared. The multiple MCZ single crystal silicon substrates are substrates made of single crystal silicon grown by the magnetic field applied Czochralski method (MCZ method), and the dopant type, dopant concentration, oxygen concentration, carbon concentration, diameter, and crystal plane orientation are as described below and do not contain nitrogen.

[0111] Dopant type / concentration: phosphorus / 7.4×10 13 -1.4×10 14 atoms / cm 3 ,

[0112] Oxygen concentration: 8.8×10 16 -5.5×10 17 atoms / cm 3 ,

[0113] Carbon concentration: 4.4×10 14 -3.1×10 15 atoms / cm 3 ,

[0114] Diameter: 200 mm,

[0115] Crystal plane orientation: (100).

[0116] The oxygen concentration was measured by the infrared absorption method (using the conversion coefficient specified by JEIDA), and the carbon concentration was measured by secondary ion mass spectrometry (SIMS).

[0117] Next, the prepared single-crystalline silicon substrate was irradiated with protons. At this time, the dose of protons was 2×10 14 atoms / cm 2 , and the acceleration voltage of the protons was 8 MV. In addition, in order to make the range of the protons about 15 μm, when irradiating the protons, a plurality of aluminum foils with a total thickness of about 410 μm were set as absorbers on the upstream side of the single-crystalline silicon substrate.

[0118] Next, heat treatment was performed on the single-crystalline silicon substrate after proton irradiation. At this time, the heat treatment conditions were set as follows: the temperature was 450 °C, the time was 60 minutes, and the atmosphere was a nitrogen atmosphere.

[0119] Next, the depth-direction distribution of the donor concentration was measured on the heat-treated single-crystalline silicon substrate by the spreading resistance measurement method (SR method).

[0120] The conditions of Experimental Example 3 and the conditions of the same FZ single-crystalline silicon substrate as in Experimental Example 2 are shown together in Table 3.

[0121] [Table 3]

[0122]

[0123] Next, the donor concentration (N D (x)) at each measured depth x was subtracted from the donor concentration in the substrate (the average value of the donor concentration at a depth of about 60 to 70 μm where the donor concentration is substantially constant) to obtain the donor increase amount (ΔN D (x)) at each depth x.

[0124] Next, the integrated donor increase amount was obtained by integrating the donor increase amount in the depth direction, and the relationships with the nitrogen concentration, oxygen concentration, and carbon concentration in the single-crystalline silicon substrate were investigated.

[0125] The relationship between the integrated donor increase amount and the nitrogen concentration is shown in Figure 9 , the relationship between the integrated donor increase amount and the oxygen concentration is shown in Figure 10 , the relationship between the integrated donor increase amount and the carbon concentration is shown in Figure 11 , and the relationship between the integrated donor increase amount and the product of the oxygen concentration and the carbon concentration is shown in Figure 12 . In Figures 10 - 12 , different markings indicate different substrate varieties. 〇 represents the case of an FZ single-crystalline silicon substrate, and □ represents the case of an MCZ single-crystalline silicon substrate.

[0126] According to Figure 9 's results, it can be seen that the integrated donor increase amount does not depend on the nitrogen concentration. In addition, according to Figure 10 and Figure 11From the results, the tendency of the increase in integral donors is as follows: the higher the oxygen concentration, the higher it is; the higher the carbon concentration, the higher it is, and the deviation is relatively large. Moreover, as Figure 12 shown, there is a positive correlation between the increase in integral donors and the product of oxygen concentration and carbon concentration. That is, it has an inverse correlation with the case where the heat treatment temperature shown in Figure 8 is 350 °C.

[0127] From Figure 4 the results, the range of heat treatment temperature where the product of oxygen concentration and carbon concentration (substrate A < substrate B) has a positive correlation with the increase in integral donors (substrate A < substrate B) is 425 - 500 °C. Therefore, according to Figure 4 and Figure 12 the results, for the increase in donors in the case of a heat treatment temperature of 425 - 500 °C, when the product of oxygen concentration and carbon concentration is at least 2×10 33 [(atoms / cm 3 )] 2 or less, the increase in donors has a positive correlation with the product of oxygen concentration and carbon concentration. By adjusting the oxygen concentration and carbon concentration in the single-crystalline silicon substrate based on this correlation, the donor concentration can be controlled with high precision.

[0128] (Experimental Example 4)

[0129] Multiple MCZ single-crystalline silicon substrates with different oxygen concentrations and carbon concentrations were prepared. The multiple MCZ single-crystalline silicon substrates are substrates manufactured from single-crystalline silicon ingots grown by the magnetic field-applied Czochralski method (MCZ method), and the dopant type, dopant concentration, oxygen concentration, carbon concentration, diameter, and crystal plane orientation are as follows.

[0130] Dopant type / concentration: phosphorus / 7.4×10 13 -1.4×10 14 atoms / cm 3 ,

[0131] Oxygen concentration: 8.8×10 16 -5.5×10 17 atoms / cm 3 ,

[0132] Carbon concentration: 4.4×10 14 -3.1×10 15 atoms / cm 3 ,

[0133] Diameter: 200 mm,

[0134] Crystal plane orientation: (100).

[0135] The oxygen concentration was measured by infrared absorption method (using the conversion coefficient specified by JEIDA), and the carbon concentration was measured by secondary ion mass spectrometry (SIMS).

[0136] Next, protons were irradiated onto the prepared single-crystalline silicon substrate. At this time, the dose of protons was 2×10 14 atoms / cm 2 , and the acceleration voltage of protons was 8 MV. In addition, in order to make the range of protons be about 15 μm, when irradiating protons, a plurality of aluminum foils with a total thickness of about 410 μm were set as absorbers on the upstream side of the single-crystalline silicon substrate.

[0137] Next, heat treatment was performed on the single-crystalline silicon substrate after proton irradiation. At this time, the heat treatment conditions were set as follows: the temperature was 350 °C, the time was 60 minutes, and the atmosphere was a nitrogen atmosphere.

[0138] Next, the depth-direction distribution of the donor concentration was measured on the heat-treated single-crystalline silicon substrate by the spreading resistance measurement method (SR method).

[0139] The conditions in Experimental Example 4 are shown in Table 4.

[0140] [Table 4]

[0141]

[0142]

[0143] Next, the donor concentration increase amount (ΔN D (x)) at each depth x measured above was obtained by subtracting the donor concentration in the substrate (the average value of the donor concentration at a depth of about 60 - 70 μm, where the donor concentration is substantially constant) from the donor concentration (N D (x)) at each depth x.

[0144] Next, the integrated donor concentration increase amount was obtained by integrating the donor concentration increase amount in the depth direction, and the relationships with the oxygen concentration and carbon concentration in the single-crystalline silicon substrate were investigated.

[0145] In Figure 13 , the relationship between the integrated donor concentration increase amount and the oxygen concentration is shown. In Figure 14 , the relationship between the integrated donor concentration increase amount and the carbon concentration is shown. In Figure 15 , the relationship between the integrated donor concentration increase amount and the product of the oxygen concentration and carbon concentration is shown. In Figures 13 - 15 also includes the data shown in Figures 6 - 8 respectively. In Figures 13 - 15 , different markings indicate different substrate varieties. 〇 represents the case of an FZ single-crystalline silicon substrate, and □ represents the case of an MCZ single-crystalline silicon substrate.

[0146] According to Figure 15 the results, when the heat treatment temperature is 350 °C, with the product of the oxygen concentration and the carbon concentration being 1×10 32 [(atoms / cm 3 )] 2 as the boundary, the correlation between the product of the oxygen concentration and the carbon concentration and the increase in the integral donor is different. Additionally, according to Figure 13 the comparison with Figure 15 , it can be seen that if the product of the oxygen concentration and the carbon concentration exceeds 1×10 32 [(atoms / cm 3 )] 2 , then the correlation between the increase in the integral donor and the oxygen concentration is stronger than the correlation with the product of the oxygen concentration and the carbon concentration.

[0147] As described above, the increase in the donor in the case of proton irradiation and heat treatment has a complex relationship with the oxygen concentration and the carbon concentration in the single-crystalline silicon substrate. Moreover, the reason for the change in this correlation according to the heat treatment temperature is not clear, but consider the following situation.

[0148] Regarding the mechanism of forming donors through proton irradiation and heat treatment, consider it as follows. When proton irradiating a single-crystalline silicon substrate, while introducing hydrogen, silicon atoms at lattice positions are ejected, and interstitial silicon (hereinafter referred to as I) and vacancies (hereinafter referred to as V) as its empty shells are generated. Excessively generated I and V are unstable in the elemental state, so they recombine (V + I → 0) or I and I, V and V cluster, and react with light element impurities such as oxygen and carbon contained in the single-crystalline silicon substrate to form complexes. Moreover, it is considered that donors are formed by bonding hydrogen to the clusters of I and V, and the complexes of I, V and light element impurities. Thus, it is considered that there are various donors formed through proton irradiation and heat treatment, and their types and concentrations vary according to the concentrations of light element impurities in the single-crystalline silicon substrate and the heat treatment temperature.

[0149] In addition, if irradiation damage from proton irradiation remains after heat treatment, it may inertize the dopant and decrease the carrier mobility, resulting in a reduction in the effective donor concentration. Regarding the irradiation damage of proton irradiation, it is difficult to recover if the heat treatment temperature is low, and it is also difficult to recover if the oxygen concentration and the carbon concentration of the single-crystalline silicon substrate are high. In the case where the heat treatment temperature after proton irradiation is low, if the oxygen concentration and the carbon concentration of the single-crystalline silicon substrate are high, the effective donor concentration decreases due to the remaining irradiation damage, but the donor concentration associated with oxygen or carbon formed through proton irradiation and heat treatment becomes high.

[0150] Therefore, as Figure 15 shown, regarding the correlation between the product of the oxygen concentration and the carbon concentration and the increase in the integral donor, when the product of the oxygen concentration and the carbon concentration is 1×1032 [(atoms / cm 3 )] 2 When it is below, the decrease in the effective donor concentration caused by the residual irradiation damage is dominant, so it is a negative correlation. When the product of the oxygen concentration and the carbon concentration exceeds 1×10 32 [(atoms / cm 3 )] 2 , the donor concentration affected by oxygen or carbon formed by proton irradiation and heat treatment is dominant, so it is a positive correlation. It is considered that when the heat treatment temperature after proton irradiation is high, the irradiation damage of proton irradiation is easy to recover, the decrease in the effective donor concentration caused by the residual irradiation damage can be suppressed, and the donor concentration affected by oxygen or carbon is dominant. Therefore, it is a positive correlation in a wide concentration range of oxygen and carbon.

[0151] Examples

[0152] The present invention will be described more specifically below using examples and comparative examples, but the present invention is not limited thereto.

[0153] (Example 1)

[0154] By Figure 1 The method for controlling the donor concentration of the present invention shown was used to control the donor concentration in a single-crystalline silicon substrate. At this time, when the integrated donor increase amount was measured in the same manner as in the experimental example as the target value of the donor concentration in the single-crystalline silicon substrate for controlling the donor concentration, the target was to control the integrated donor increase amount to about 8×10 11 / cm 2 .

[0155] [First proton irradiation step S1 to measurement step S3]

[0156] First, after irradiating a plurality of test single-crystalline silicon substrates with different oxygen concentrations and carbon concentrations with protons, heat treatment was performed, and the integrated donor increase amounts of the plurality of test single-crystalline silicon substrates were measured. The test single-crystalline silicon substrates were substrates made of single-crystalline silicon grown by the FZ method.

[0157] At this time, the dose of protons was 2×10 14 atoms / cm 2 , and the acceleration voltage was 8 MV. In addition, in order to make the range of protons about 15 μm, when irradiating protons, a plurality of aluminum foils with a total thickness of about 410 μm were set as absorbers on the upstream side of the single-crystalline silicon substrate. In addition, at this time, the temperature of the heat treatment was 350°C, the time was 60 minutes, and the atmosphere was a nitrogen atmosphere. In addition, at this time, the integrated donor increase amount was measured using the same process as in the experimental example.

[0158] [Correlation acquisition step S4]

[0159] Next, in the correlation acquisition process, a correlation between the product of oxygen concentration and carbon concentration and the integral donor increase amount, which is approximately the same as Figure 8 that, is acquired.

[0160] [Preparation Process S5]

[0161] Next, based on the above correlation, the oxygen concentration and carbon concentration of the single crystal silicon substrate (control target substrate) prepared in the preparation process are adjusted so that the integral donor increase amount of the single crystal silicon substrate after the second heat treatment process becomes the target value (about 8×10 11 / cm 2 ). At this time, the prepared single crystal silicon substrate is a substrate made of single crystal silicon grown by the FZ method using a single crystal silicon ingot grown by the CZ method as a raw material, and is adjusted to an oxygen concentration of 1.2×10 16 atoms / cm 3 , and a carbon concentration of 1.0×10 15 atoms / cm 3 .

[0162] [Second Proton Irradiation Process S6 - Second Heat Treatment Process S7]

[0163] After that, protons are irradiated onto the single crystal silicon substrate prepared in the preparation process (second proton irradiation process). At this time, the dose of protons is 2×10 14 atoms / cm 2 , and the acceleration voltage of protons is 8 MV. In addition, in order to make the range of protons about 15 μm, when irradiating protons, multiple aluminum foils with a total thickness of about 410 μm are set as absorbers on the upstream side of the single crystal silicon substrate.

[0164] Next, heat treatment is performed on the single crystal silicon substrate after proton irradiation (second heat treatment process). At this time, the heat treatment temperature is 350°C, the time is 60 minutes, and the atmosphere is a nitrogen atmosphere.

[0165] The integral donor increase amount after heat treatment is measured, and as a result, the integral donor increase amount of the single crystal silicon substrate is 8.4×10 11 / cm 2 . In this way, in Example 1, it can be confirmed that the target donor concentration can be obtained by adjusting the oxygen concentration and carbon concentration of the single crystal silicon substrate.

[0166] (Example 2)

[0167] By Figure 1The control method of the donor concentration of the present invention shown above controls the donor concentration in a single-crystalline silicon substrate. At this time, when the integrated donor increase amount was measured in the same manner as in the experimental example as the target value of the donor concentration in the single-crystalline silicon substrate for controlling the donor concentration, the target was to control the integrated donor increase amount to about 1.2×10 12 / cm 2 .

[0168] [First proton irradiation step S1 to measurement step S3]

[0169] First, after irradiating protons to a plurality of test single-crystalline silicon substrates having different oxygen concentrations and carbon concentrations, heat treatment was performed, and the integrated donor increase amounts of the plurality of test single-crystalline silicon substrates were measured. Among the plurality of test single-crystalline silicon substrates, there were FZ single-crystalline silicon substrates and MCZ single-crystalline silicon substrates.

[0170] At this time, the dose of protons was 2×10 14 atoms / cm 2 , and the acceleration voltage was 8 MV. In addition, in order to make the range of protons about 15 μm, when irradiating protons, a plurality of aluminum foils with a total thickness of about 410 μm were provided as absorbers on the upstream side of the single-crystalline silicon substrate. In addition, at this time, the temperature of the heat treatment was 450 °C, the time was 60 minutes, and the atmosphere was a nitrogen atmosphere. In addition, at this time, the integrated donor increase amount was measured using the same process as in the experimental example.

[0171] [Correlation acquisition step S4]

[0172] Next, in the correlation acquisition step, a correlation between the product of the oxygen concentration and the carbon concentration, which is substantially the same as Figure 12 , and the integrated donor increase amount was obtained.

[0173] [Preparation step S5]

[0174] Next, based on the above correlation, the oxygen concentration and the carbon concentration of the single-crystalline silicon substrate prepared in the preparation step were adjusted so that the integrated donor increase amount of the single-crystalline silicon substrate (control target substrate) after the second heat treatment step became the target value (about 1.2×10 12 / cm 2 ). At this time, the prepared single-crystalline silicon substrate was a substrate made of single-crystalline silicon grown by the MCZ method, and the oxygen concentration was adjusted to 1.9×10 17 atoms / cm 3 , and the carbon concentration was 6.7×10 14 atoms / cm 3 .

[0175] [Second proton irradiation step S6 to second heat treatment step S7]

[0176] Thereafter, the single-crystalline silicon substrate prepared in the preparation process is irradiated with protons (second proton irradiation process). At this time, the dose of protons is 2×10 14 atoms / cm 2 , and the acceleration voltage of the protons is 8 MV. In addition, in order to make the range of the protons about 15 μm, when irradiating the protons, a plurality of aluminum foils with a total thickness of about 410 μm are provided as absorbers on the upstream side of the single-crystalline silicon substrate.

[0177] Next, heat treatment is performed on the single-crystalline silicon substrate after proton irradiation (second heat treatment process). At this time, the heat treatment temperature is 450 °C, the time is 60 minutes, and the atmosphere is a nitrogen atmosphere.

[0178] The integrated donor increase amount after heat treatment is measured. As a result, the integrated donor increase amount of the single-crystalline silicon substrate is 1.2×10 12 / cm 2 . Thus, in Example 2, it can be confirmed that the target donor concentration can be obtained by adjusting the oxygen concentration and carbon concentration of the single-crystalline silicon substrate.

[0179] (Comparative Example 1)

[0180] Except that the test single-crystalline silicon substrate was not used and the oxygen concentration and carbon concentration of the prepared single-crystalline silicon substrate (control object substrate) were adjusted based on the above relevant relationship, the donor concentration of the single-crystalline silicon substrate was controlled under the same conditions as in Example 1.

[0181] At this time, the prepared single-crystalline silicon substrate is a substrate made of single-crystalline silicon grown by the FZ method using a normal polysilicon ingot as a raw material, and the oxygen concentration is adjusted to 2.0×10 15 atoms / cm 3 , and the carbon concentration is 9.8×10 14 atoms / cm 3 .

[0182] For the above-prepared single-crystalline silicon substrate, proton irradiation and heat treatment are performed under the same conditions as in Example 1, and the integrated donor increase amount is measured using the same process as in Example 1. As a result, the integrated donor increase amount is 1.2×10 12 / cm 2 .

[0183] Thus, in Comparative Example 1, it was confirmed that although the proton irradiation conditions and heat treatment conditions were the same as those in Example 1, the integrated donor increase amount of the single-crystalline silicon substrate deviated far from the target value, that is, about 8×10 11 / cm 2 .

[0184] (Comparative Example 2)

[0185] Except for not using the test single-crystalline silicon substrate and adjusting the oxygen concentration and carbon concentration of the prepared single-crystalline silicon substrate (substrate to be controlled) based on the above-mentioned correlation, the donor concentration of the single-crystalline silicon substrate was controlled under the same conditions as in Example 2.

[0186] At this time, the prepared single-crystalline silicon substrate was a substrate made of single-crystalline silicon grown by the MCZ method, and the oxygen concentration was adjusted to 5.2×10 17 atoms / cm 3 and the carbon concentration was 1.1×10 15 atoms / cm 3 .

[0187] For the above-prepared single-crystalline silicon substrate, proton irradiation and heat treatment were performed under the same conditions as in Example 2, and the integrated donor increase amount was measured using the same process as in Example 2. As a result, the integrated donor increase amount was 1.6×10 12 / cm 2 .

[0188] In this way, in Comparative Example 2, it was confirmed that although the proton irradiation conditions and heat treatment conditions were the same as those in Example 2, the integrated donor increase amount of the single-crystalline silicon substrate deviated far from the target value of about 1.2×10 12 / cm 2 .

[0189] The conditions and results of Example 1 and Comparative Example 1 are shown in Table 5, and the conditions and results of Example 2 and Comparative Example 2 are shown in Table 6.

[0190] [Table 5]

[0191]

[0192] [Table 6]

[0193]

[0194] In Comparative Example 1 and Comparative Example 2, since the correlation between the product of the oxygen concentration and carbon concentration in the test silicon substrate and the integrated donor increase amount was not based on, the value of the integrated donor increase amount in the substrate to be controlled deviated far from the target value.

[0195] On the other hand, in Examples 1 and 2 which are embodiments of the method for controlling the donor concentration in the single-crystalline silicon substrate of the present invention, by adjusting the oxygen concentration and carbon concentration of the single-crystalline silicon substrate (substrate to be controlled) prepared in the preparation process based on the correlation between the product of the oxygen concentration and carbon concentration in the test silicon substrate and the integral donor increase amount, so that the integral donor increase amount of the single-crystalline silicon substrate (substrate to be controlled) after the second heat treatment process becomes the target value, it is possible to reduce the deviation of the donor concentration caused by the single-crystalline silicon substrate and to control the donor concentration with high precision.

[0196] 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 function and effect is included in the technical scope of the present invention.

Claims

1. A method for controlling the donor concentration in a single-crystalline silicon substrate, which controls the donor concentration by performing the following steps: A preparation step of preparing a single-crystalline silicon substrate for controlling the donor concentration; A second proton irradiation step of irradiating protons to the prepared single-crystalline silicon substrate; and A second heat treatment step of performing a heat treatment on the single-crystalline silicon substrate after the second proton irradiation step, It is characterized in that comprising: A first proton irradiation step of pre-irradiating protons to a plurality of test single-crystalline silicon substrates having different oxygen concentrations and carbon concentrations before performing the preparation step; A first heat treatment step of performing a heat treatment on the plurality of test silicon substrates after the first proton irradiation step; A measurement step of measuring the spreading resistance in the plurality of test single-crystalline silicon substrates after the first heat treatment step and calculating the resistivity, and based on the existing relationship between the resistivity and the donor concentration, obtaining the depth-direction distribution of the donor concentration according to the calculated resistivity, and measuring the donor increase amount generated in the plurality of test single-crystalline silicon substrates after the first heat treatment step based on the obtained depth-direction distribution of the donor concentration; and A correlation obtaining step of obtaining the correlation between the measured donor increase amount and the product of the oxygen concentration and the carbon concentration of the plurality of test silicon substrates, Based on the obtained correlation, adjusting the oxygen concentration and the carbon concentration of the single-crystalline silicon substrate for controlling the donor concentration prepared in the preparation step so that the donor concentration in the single-crystalline silicon substrate for controlling the donor concentration after the second heat treatment step becomes a target value.

2. The method for controlling the donor concentration in a single-crystalline silicon substrate according to claim 1, wherein The product of the oxygen concentration and the carbon concentration of the single-crystalline silicon substrate for controlling the donor concentration prepared in the preparation process is 1×10 32 [(atoms / cm 3 )] 2 Hereinafter, in the second heat treatment process, the heat treatment temperature is 300 to 400 °C.

3. The method for controlling the donor concentration in a single-crystalline silicon substrate according to claim 1, wherein The product of the oxygen concentration and the carbon concentration of the single-crystalline silicon substrate whose dopant concentration is controlled and which is prepared in the preparation process is 2×10 33 [(atoms / cm 3 )] 2 Hereinafter, in the second heat treatment process, the heat treatment temperature is 425 to 500 °C.

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