Carbon-doped single crystal silicon wafer and method for manufacturing the same

Abstract

The present invention provides a method for manufacturing a carbon-doped single-crystal silicon wafer, which has the following steps: a step of preparing a single-crystal silicon wafer that has not been carbon-doped; a step of performing a first RTA treatment on the single-crystal silicon wafer in an atmosphere containing a carbon atom compound gas; a step of performing a second RTA treatment following the first RTA treatment at a temperature higher than the first RTA treatment; a step of cooling the single-crystal silicon wafer after performing the second RTA treatment; and a step of performing a third RTA treatment after performing the cooling, through which the single-crystal silicon wafer is modified to have a 3C-SiC single crystal layer, a carbon precipitation layer, a diffusion layer of interstitial carbon and silicon, and a diffusion layer of vacancies and carbon in sequence from the surface side. Thus, a carbon-doped single-crystal silicon wafer and a method for manufacturing the same are provided, which can improve the strength of the wafer by setting the carbon concentration of the surface layer of the single-crystal silicon wafer to a high concentration and making the carbon concentration distribution on the surface uniform.

Description

Technical Field

[0001] The invention relates to a carbon-doped single-crystal silicon wafer and a manufacturing method thereof. Background Art

[0002] As a substrate for manufacturing semiconductor devices, single crystal silicon wafers are widely used. In addition, it is known that in order to remove metal impurities mixed in during the manufacturing process of semiconductor devices, single crystal silicon wafers are given gettering ability. However, in recent years, the manufacturing conditions of the most advanced devices have been continuously lowered. Since carbon acts as a gettering site for metal impurities in the manufacturing process, single crystal silicon wafers doped with carbon are gradually being used, which are prone to form BMD (Bulk MicroDefect) due to oxygen precipitation even in low-temperature processes.

[0003] In addition, it is also known that by doping a single crystal silicon wafer with nitrogen or carbon, the wafer strength can be improved. However, since nitrogen diffuses quickly in single crystal silicon, in a nitrogen-doped single crystal silicon wafer, nitrogen diffuses to the outside during the heat treatment used to make the device, making it difficult to obtain a high surface strength. Carbon has a small diffusion coefficient, so in a carbon-doped single crystal silicon wafer, the surface strength can be improved.

[0004] Furthermore, it is known that carbon in a carbon-doped single crystal silicon wafer for a solid-state image sensor suppresses injection of carriers from an electrode, thereby achieving a small dark current and excellent photosensitivity (see Non-Patent Document 1).

[0005] Furthermore, it is also known that carbon in a single crystal silicon wafer has an effect of suppressing the formation of oxygen donors generated during heat treatment (see Patent Document 1).

[0006] Prior art literature

[0007] Patent Literature

[0008] Patent Document 1: Japanese Patent Application Publication No. 2011-54656

[0009] Patent Document 2: Japanese Patent Application Publication No. 2018-190903

[0010] Non-patent literature

[0011] Non-patent document 1: "Structural Elements of Ultrashallow Thermal DonorsFormed in Silicon Crystals" A. Hara, T. Awano, Y. Ohno and I. Yonenaga: Jpn.J.Appl.Phys.49(2010)050203. Summary of the invention

[0012] Technical Problems to be Solved by the Invention

[0013] As methods for improving the wafer strength of single crystal silicon wafers, carbon doping and nitrogen doping of single crystal silicon wafers, methods of making wafers into high oxygen concentration crystals, and methods of causing oxygen to precipitate in wafers are known. However, when carbon or nitrogen is doped into the crystal during the growth of single crystal silicon (single crystal silicon ingot) by the pulling method, the impurity concentration will change due to the position of the crystal after single crystalization due to the segregation phenomenon, resulting in differences in the amount of oxygen precipitation caused by different crystal positions.

[0014] Furthermore, there is a limit to controlling the amount of oxygen precipitation from a single crystal silicon wafer by only relying on the oxygen concentration, and it is difficult to control the amount of oxygen precipitation to a high density without doping with carbon or nitrogen.

[0015] Furthermore, as the above-mentioned recent device process temperature reduction process progresses, oxygen precipitation in single crystal silicon wafers becomes increasingly difficult, and therefore a technology is sought that can control the amount of oxygen precipitation to a desired amount even in such a low-temperature device process.

[0016] On the other hand, a scheme has been proposed to control the BMD to a high density by heat treating a single crystal silicon wafer in a carbon-containing gas atmosphere (see Patent Document 2). However, in Patent Document 2, since the heat treatment is performed by resistance heating, carbon diffuses to the outside during the cooling process, and the carbon concentration on the wafer surface cannot be fully increased, which is not sufficient in terms of wafer strength.

[0017] The present invention is completed in view of the above problems, and its purpose is to provide a carbon-doped single crystal silicon wafer and a manufacturing method thereof that can improve the strength of the wafer by setting the carbon concentration of the surface layer of the single crystal silicon wafer to a high concentration and making the carbon concentration distribution on the surface uniform.

[0018] Technical means to solve technical problems

[0019] In order to achieve the above-mentioned purpose, the present invention provides a method for manufacturing a carbon-doped single crystal silicon wafer, characterized in that the manufacturing method has the following steps: a step of preparing a single crystal silicon wafer that has not been carbon-doped; a step of performing a first RTA treatment on the single crystal silicon wafer in an atmosphere containing a carbon atom-containing compound gas; a step of performing a second RTA treatment subsequent to the first RTA treatment at a temperature higher than the first RTA treatment; a step of cooling the single crystal silicon wafer after performing the second RTA treatment; and a step of performing a third RTA treatment after the cooling, through which the single crystal silicon wafer is modified into a carbon-doped single crystal silicon wafer having, from the surface side, a 3C-SiC single crystal layer, a carbon precipitation layer, a diffusion layer of interstitial carbon and silicon, and a diffusion layer of vacancies and carbon.

[0020] If it is a manufacturing method of this carbon-doped single crystal silicon wafer, it is possible to inject carbon and vacancies together in the RTA (Rapid Thermal Annealing, rapid thermal annealing) processing stage based on rapid heating / rapid cooling, thereby increasing the diffusion coefficient of carbon by utilizing the effect of vacancies without being affected by the position of the crystal that has been crystallized. Therefore, carbon can be diffused uniformly from the surface, and a carbon-doped single crystal silicon wafer having a 3C-SiC single crystal layer, a carbon precipitation layer, a diffusion layer of interstitial carbon and silicon, and a diffusion layer of vacancies and carbon in sequence from the surface side can be made. Since the present invention forms a 3C-SiC single crystal layer on the surface of the carbon-doped single crystal silicon wafer, it is easy to make the carbon concentration of the carbon precipitation layer below it high concentration, and a wafer with high strength can be provided.

[0021] Furthermore, in the method for manufacturing a carbon-doped single crystal silicon wafer of the present invention, preferably, after the step of performing the third RTA treatment, there is further a step of polishing and removing the 3C-SiC single crystal layer.

[0022] In this way, by removing the 3C-SiC single crystal layer on the surface by polishing, there is no need to remove the 3C-SiC single crystal layer again when manufacturing a device.

[0023] Furthermore, at this time, it is preferred that the carbon concentration of the carbon precipitation layer be controlled to be 3×10 17 atoms / cm 3 above.

[0024] By setting the carbon concentration in the surface portion of the wafer in this manner, it is possible to further increase the wafer strength and control the amount of oxygen deposition to a desired amount.

[0025] In addition, it is preferred that the carbon concentration of the diffusion layer of interstitial carbon and silicon is controlled to be 1×10 17 atoms / cm 3 above.

[0026] In addition, it is preferred that the carbon concentration of the vacancy and carbon diffusion layer is controlled to be 1×10 16 atoms / cm 3 above.

[0027] By setting the carbon concentration in the bulk of the wafer in this manner, it is possible to further increase the wafer strength and control the amount of oxygen deposition to a desired amount.

[0028] Furthermore, in the method for manufacturing a carbon-doped single crystal silicon wafer of the present invention, it is preferred that the oxygen concentration of the prepared single crystal silicon wafer be set to 11 ppma or more.

[0029] By setting the oxygen concentration of the prepared wafer to 11 ppma or more, oxygen precipitation in the carbon-doped single crystal silicon wafer becomes easier. In the description of the present invention, the oxygen concentration is expressed in accordance with the JEITA (Japan Electronic and Information Technology Industries Association) standard.

[0030] Furthermore, it is preferable that the prepared single crystal silicon wafer be a single crystal silicon wafer composed of any one of an Nv region, a Ni region, and a V region.

[0031] Since carbon exists in the single crystal silicon wafer manufactured by the method for manufacturing a carbon-doped single crystal silicon wafer of the present invention, oxygen precipitation can be formed regardless of the defect region, and by making the prepared wafer a wafer having such a defect region, oxygen precipitation becomes easier.

[0032] In addition, it is preferable that the atmosphere of the first RTA treatment and the second RTA treatment be a mixed atmosphere containing a hydrocarbon gas and Ar or H 2 , or a mixed atmosphere containing a hydrocarbon gas and Ar and H 2 .

[0033] By performing the heat treatment in such an atmosphere, carbon can be more effectively implanted together with vacancies.

[0034] In addition, it is preferred that: the first RTA treatment is performed by maintaining a temperature of 600°C to 850°C for a time of 5 seconds to 60 seconds, the second RTA treatment is performed by maintaining a temperature of 1100°C to below the melting point of silicon for a time of 10 seconds to 150 seconds, and the third RTA treatment is performed by maintaining a temperature of 1100°C to below the melting point of silicon for a time of 10 seconds to 150 seconds.

[0035] By using such RTA treatment conditions, carbon can be more effectively implanted together with vacancies.

[0036] Furthermore, it is preferred that the third RTA treatment is repeated one or more times.

[0037] By repeating the third RTA treatment one or more times in this manner, vacancies and carbon can be diffused deeper from the surface, and thus the carbon concentration in the bulk can be controlled to a desired value by repeating the third RTA treatment.

[0038] In addition, the present invention provides a carbon-doped single crystal silicon wafer, which is a single crystal silicon wafer doped with carbon, characterized in that it has a carbon precipitation layer, a diffusion layer of interstitial carbon and silicon, and a diffusion layer of vacancies and carbon in sequence from the surface side of the single crystal silicon wafer.

[0039] This carbon-doped single-crystal silicon wafer can achieve high wafer strength.

[0040] In addition, it is preferred that the carbon concentration of the carbon precipitation layer in the range from the surface of the carbon-doped single crystal silicon wafer to 0.14 μm is 3×10 17 atoms / cm 3 above.

[0041] By setting the carbon concentration in the surface portion of the wafer in this manner, it is possible to further increase the wafer strength and control the amount of oxygen deposition to a desired amount.

[0042] In addition, it is preferred that the carbon concentration of the diffusion layer of interstitial carbon and silicon is 1×10 17 atoms / cm 3 above.

[0043] In addition, it is preferred that the carbon concentration of the vacancies and carbon diffusion layer in a region deeper than 1 μm from the surface of the carbon-doped single crystal silicon wafer is 1×10 16 atoms / cm 3 above.

[0044] By setting the carbon concentration in the bulk of the wafer in this manner, it is possible to further increase the wafer strength and control the amount of oxygen deposition to a desired amount.

[0045] In addition, the carbon-doped single crystal silicon wafer of the present invention may further have a 3C-SiC single crystal layer on the carbon precipitation layer.

[0046] Since the wafer having a 3C-SiC single crystal layer, a carbon precipitation layer, a diffusion layer of interstitial carbon and silicon, and a diffusion layer of vacancies and carbon in sequence from the surface side has a 3C-SiC single crystal layer on the surface of the wafer, the carbon concentration of the carbon precipitation layer can be easily made high, thereby providing a wafer with extremely high strength.

[0047] Furthermore, it is preferred that the oxygen concentration of the carbon-doped single crystal silicon wafer is 11 ppma or more.

[0048] At such an oxygen concentration, oxygen precipitation in the carbon-doped single crystal silicon wafer becomes easier.

[0049] Furthermore, it is preferable that the single crystal silicon wafer is composed of any one of an Nv region, a Ni region, and a V region.

[0050] By using a wafer having such a defect region, oxygen deposition can be more easily performed.

[0051] Effects of the Invention

[0052] If it is the manufacturing method of the carbon-doped single crystal silicon wafer of the present invention, it is possible to inject carbon and vacancies together in the RTA processing stage, so as to increase the diffusion coefficient of carbon by utilizing the effect of vacancies without being affected by the crystal position of the single crystal. Therefore, carbon can be uniformly diffused from the surface, and a carbon-doped single crystal silicon wafer having a 3C-SiC single crystal layer, a carbon precipitation layer, a diffusion layer of interstitial carbon and silicon, and a diffusion layer of vacancies and carbon in sequence from the surface side is made. As a result, high wafer strength can be obtained. Since the present invention forms a 3C-SiC single crystal layer on the surface of the carbon-doped single crystal silicon wafer, the carbon concentration of the carbon precipitation layer below it can be easily made high concentration, and a wafer with high strength can be provided. In addition, since the carbon-doped single crystal silicon wafer of the present invention has a carbon precipitation layer, a diffusion layer of interstitial carbon and silicon, and a diffusion layer of vacancies and carbon in sequence from the surface side, high wafer strength can be obtained. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] Figure 1 FIG. 1 is a flow chart showing an example of a method for manufacturing a carbon-doped single crystal silicon wafer according to the present invention.

[0054] Figure 2 This is a graph schematically showing a temperature profile of the RTA process in the method for manufacturing a carbon-doped single crystal silicon wafer according to the present invention.

[0055] Figure 3 This is a graph showing the results of measuring the carbon concentration distribution of the carbon-doped single crystal silicon wafer in the example by SIMS.

[0056] Figure 4 This is a graph showing the results of measuring the carbon concentration distribution of a carbon-doped single crystal silicon wafer in a comparative example by SIMS. DETAILED DESCRIPTION

[0057] As described above, due to the recent advancement of low-temperature processes in device processes, oxygen precipitation in single-crystal silicon wafers has become increasingly difficult, and therefore a technology is sought that can control the amount of oxygen precipitation to a desired amount even in such low-temperature device processes. The inventors of the present application have found that in order to improve wafer strength, it is necessary to dope carbon into single-crystal silicon wafers at a high concentration. In addition, the inventors of the present application have also found that by injecting carbon and vacancies together during the heat treatment stage, the diffusion coefficient of carbon increases due to the effect of vacancies and is not affected by the position of the crystal that has been crystallized, thereby enabling oxygen precipitation to grow uniformly and accelerate, thereby completing the present invention.

[0058] The present invention is a method for manufacturing a carbon-doped single crystal silicon wafer, characterized in that the manufacturing method has the following steps: a step of preparing a single crystal silicon wafer that has not been carbon-doped; a step of performing a first RTA treatment on the single crystal silicon wafer in an atmosphere containing a carbon atom-containing compound gas; a step of performing a second RTA treatment subsequent to the first RTA treatment at a temperature higher than the first RTA treatment; a step of cooling the single crystal silicon wafer after performing the second RTA treatment; and a step of performing a third RTA treatment after the cooling, through which the single crystal silicon wafer is modified into a carbon-doped single crystal silicon wafer having, from the surface side, a 3C-SiC single crystal layer, a carbon precipitation layer, a diffusion layer of interstitial carbon and silicon, and a diffusion layer of vacancies and carbon.

[0059] First, if Figure 1 As shown in (a), a single crystal silicon wafer that is not doped with carbon is prepared (process a). Preferably, the single crystal silicon wafer prepared here is a single crystal silicon wafer made from a single crystal silicon ingot pulled by a pulling method. In addition, "not doped with carbon" in the present invention means that carbon is not intentionally added to the single crystal silicon wafer, and a single crystal silicon wafer containing carbon as an unavoidable impurity that is not intentionally added is included in the "single crystal silicon wafer that is not doped with carbon".

[0060] The non-carbon-doped single crystal silicon wafer prepared here can be prepared, for example, in the following manner. First, a single crystal silicon ingot is pulled by a CZ method. Then, the single crystal silicon ingot is processed into a single crystal silicon wafer (CW processing) by known methods such as slicing, grinding, polishing, and etching.

[0061] It is preferred that the oxygen concentration of the single crystal silicon wafer prepared here is above 11 ppma. The oxygen concentration can be achieved by adjusting the conditions during pulling. In addition, it is preferred that the single crystal silicon wafer prepared here is a single crystal silicon wafer composed of any one of the Nv region, the Ni region and the V region. The single crystal silicon wafer composed of these defect regions can be obtained by adjusting the conditions during pulling, especially by adjusting the pulling speed. In addition, it can be a wafer whose entire surface is composed of the Nv region, a wafer whose entire surface is composed of the Ni region, and a wafer whose entire surface is composed of the V region, but it can also be a wafer in which the above regions are mixed. In addition, the following regions exist in the single crystal silicon pulled by the pulling method: point defects (vacancies, interstitial silicon) are introduced in the crystal manufacturing process, and these point defects are agglomerated to form Grown-in (native) defects (V region, I region); and a complete crystal region (N region) where point defects are not agglomerated, etc. In the N region, although aggregation of point defects does not occur, there are Nv regions dominated by vacancies and Ni regions dominated by interstitial silicon.

[0062] Then, if Figure 1As shown in (b), the single crystal silicon wafer which is not doped with carbon and prepared in the above manner is subjected to a first RTA treatment in an atmosphere containing a carbon atom-containing compound gas (step b).

[0063] Then, if Figure 1 As shown in (c), a second RTA treatment is performed subsequent to the first RTA treatment at a temperature higher than that of the first RTA treatment (step c).

[0064] The atmosphere of the first RTA treatment and the second RTA treatment is preferably a mixed atmosphere containing hydrocarbon gas and Ar or H 2 , or a mixed atmosphere containing hydrocarbon gas and Ar and H 2 . By performing heat treatment in such an atmosphere, carbon and vacancies can be more effectively implanted together.

[0065] Then, if Figure 1 As shown in (d), after the second RTA treatment, the single crystal silicon wafer is cooled (step d). The temperature after cooling can be the same as the carrying-in / carrying-out temperature of the ordinary RTA treatment, and it is not necessary to cool to room temperature. The temperature after cooling can be set to 700°C or less, for example.

[0066] Then, if Figure 1 As shown in (e), after cooling, the third RTA treatment (step e) is performed. The atmosphere at this time is not limited to an atmosphere containing a carbon atom compound gas, and may be, for example, Ar or N2. The third RTA treatment can be performed until the carbon concentration diffused into the body of the wafer reaches a solid solubility at the heat treatment temperature at this time.

[0067] In addition, the third RTA treatment may be repeated more than once. In this case, the operation of temporarily cooling after the third RTA treatment and performing the third RTA treatment again is repeated. By repeating the third RTA treatment, vacancies and carbon can be diffused deeper from the surface, so the carbon concentration in the bulk can be controlled to a desired value by repeating the third RTA treatment.

[0068] The outline of the temperature profile of the RTA treatment for the first RTA treatment, the second RTA treatment, and the third RTA treatment is shown in FIG. Figure 2. Regarding the first RTA treatment, it is preferred to maintain a temperature of 600°C to 850°C for a time of 5 seconds to 60 seconds, thereby allowing the hydrocarbon gas to adhere to the entire surface of the single crystal silicon wafer in a manner that does not carbonize the hydrocarbon gas. In addition, regarding the second RTA treatment following the first RTA treatment, it is preferred to maintain a temperature of 1100°C to 150 seconds to 10 seconds, thereby making the carbon attached to the surface of the single crystal silicon wafer into a 3C-SiC single crystal layer. In addition, regarding the third RTA treatment after cooling, it is preferred to maintain a temperature of 1100°C to 150 seconds to 10 seconds, thereby allowing vacancies and carbon to diffuse inwardly. Carbon and vacancies can be more effectively injected together under the conditions of this RTA treatment.

[0069] Vacancies can be injected into the single crystal silicon wafer and carbon can be doped into the single crystal silicon wafer by the first RTA treatment (process b), the second RTA treatment (process c) and the third RTA treatment (process e). In addition, the present invention can increase the diffusion coefficient of carbon by using the effect of vacancies without being affected by the position of the crystal that has been crystallized by injecting carbon and vacancies together in the RTA treatment stage. As a result, carbon can be diffused uniformly from the surface, and the single crystal silicon wafer can be modified into a carbon-doped single crystal silicon wafer having a 3C-SiC single crystal layer, a carbon precipitation layer, a diffusion layer of interstitial carbon and silicon, and a diffusion layer of vacancies and carbon in sequence from the surface side. Since the present invention forms a 3C-SiC single crystal layer on the surface of the carbon-doped single crystal silicon wafer, it is easy to make the carbon concentration on the surface high, and a wafer with high strength can be provided.

[0070] Furthermore, the method for manufacturing a carbon-doped single crystal silicon wafer of the present invention may further include a step of polishing and removing the 3C-SiC single crystal layer (step f) after the step of performing the third RTA treatment (step e).

[0071] As described above, since a 3C-SiC single crystal layer is formed by the first RTA treatment, the second RTA treatment, and the third RTA treatment, it is preferably removed. This process is an optional process, but by removing the 3C-SiC single crystal layer formed on the surface, there is no need to remove the 3C-SiC single crystal layer again when manufacturing the device.

[0072] Preferably, the carbon concentration of the carbon precipitation layer after removing the 3C-SiC single crystal layer is controlled to be 3×10 17 atoms / cm 3 In this case, higher wafer strength can be obtained.

[0073] In addition, it is preferred that the carbon concentration of the interstitial carbon and silicon diffusion layer after the 3C-SiC single crystal layer is removed be controlled to 1×10 17 atoms / cm 3 In addition, it is preferred that the carbon concentration of the vacancies and the carbon diffusion layer after the 3C-SiC single crystal layer is removed be controlled to 1×10 16 atoms / cm 3 above.

[0074] The reason why this carbon distribution that controls the carbon concentration distribution in the thickness direction of the wafer can be formed is that the diamond structure of single crystal silicon is a structure with many voids and easy for impurities to diffuse. In particular, when vacancies are dominant, carbon is very easy to diffuse through the action of vacancies. Therefore, carbon is first uniformly attached to the surface of the single crystal silicon wafer through the first RTA. In particular, if the first RTA treatment is above 600°C, it is easy to attach carbon to the wafer surface. If the first RTA treatment is below 850°C, carbonization of the wafer surface in the first RTA treatment stage can be prevented, and a 3C-SiC single crystal layer can be easily formed in the subsequent second RTA. In the subsequent second RTA, a 3C-SiC single crystal layer is formed on the surface. In addition, in order to form a 3C-SiC single crystal layer in the second RTA, it is preferably heat treated at a temperature above 1100°C and below the melting point of silicon as described above. It is preferred that the carbon atom concentration in the atmosphere gas at this time is set to be above 0.1%. In addition, as described above, by setting the atmosphere of the first RTA treatment and the second RTA treatment to a mixed atmosphere containing hydrocarbon gas and Ar or H2, or a mixed atmosphere containing hydrocarbon gas and Ar and H2, it is easy to form a single crystal film (3C-SiC single crystal layer) of silicon carbide on the surface of the wafer.

[0075] This carbon-doped single crystal silicon wafer manufactured by the manufacture method of carbon-doped single crystal silicon wafer of the present invention has 3C-SiC single crystal layer, carbon precipitation layer, diffusion layer of interstitial carbon and silicon, and vacancy and diffusion layer of carbon from the surface side successively.In addition, can be by removing 3C-SiC single crystal layer from carbon-doped single crystal silicon wafer, thereby make the carbon-doped single crystal silicon wafer having carbon precipitation layer, diffusion layer of interstitial carbon and silicon, and vacancy and diffusion layer of carbon from the surface side successively.In addition, 3C-SiC single crystal layer, carbon precipitation layer, diffusion layer of interstitial carbon and silicon, and vacancy and diffusion layer of carbon can utilize SIMS or TEM (transmission electron microscope) to distinguish respectively.

[0076] At this time, it is preferred that the carbon concentration of the carbon deposition layer be controlled to 3×10 17 atoms / cm 3In addition, it is preferred that the carbon concentration of the diffusion layer of interstitial carbon and silicon be controlled to 1×10 17 atoms / cm 3 In addition, it is preferred that the carbon concentration of the vacancies and carbon diffusion layer in the region deeper than 1 μm from the surface of the carbon-doped single crystal silicon wafer be controlled to be 1×10 16 atoms / cm 3 above.

[0077] In addition, the present invention only needs to be a carbon-doped single crystal silicon wafer having a carbon precipitation layer, a diffusion layer of interstitial carbon and silicon, and a diffusion layer of vacancies and carbon in order from the surface side. Preferably, the carbon concentration of the carbon precipitation layer in the range from the surface to 0.14 μm satisfies 3×10 17 atoms / cm 3 The carbon concentration of the carbon deposition layer is preferably 3×10 17 atoms / cm 3 above.

[0078] Similarly, the diffusion layer of interstitial carbon and silicon only needs to be closer to the inner side of the wafer than the carbon precipitation layer, and it does not need to be in the range of more than 0.14 μm and less than 1 μm from the surface. For example, the diffusion layer of interstitial carbon and silicon itself may exist in the range of more than 0.1 μm and less than 1.5 μm from the surface of the wafer. In this case, it is preferred that the carbon concentration of 1×10 17 atoms / cm 3 In addition, the diffusion layer of vacancies and carbon only needs to be closer to the inner side of the wafer than the diffusion layer of interstitial carbon and silicon, and it does not need to be a region deeper than 1 μm from the surface. For example, the diffusion layer of vacancies and carbon may also exist in a range deeper than 1.5 μm from the surface. In this case, the carbon concentration in the diffusion layer of vacancies and carbon preferably satisfies 1×10 16 atoms / cm 3 above.

[0079] Furthermore, it is preferred that the oxygen concentration of the carbon-doped single crystal silicon wafer is 11 ppma or more, and it is preferred that the carbon-doped single crystal silicon wafer is composed of any one of an Nv region, a Ni region, and a V region.

[0080] Example

[0081] Hereinafter, the present invention will be specifically described with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples.

[0082] (Example)

[0083] First, a single crystal silicon ingot is pulled up by the Czochralski method and processed into a wafer, thereby preparing a wafer with a diameter of 200 mm, a crystal plane orientation of (100), a P type, a normal resistance, an oxygen concentration of 12 ppma (JEITA), and a carbon concentration of less than 2.5×10 15 atoms / cm 3 , a single crystal silicon wafer whose defective region is the Nv region is treated as a single crystal silicon wafer that has not been carbon-doped (process a).

[0084] Then, the first RTA treatment, the second RTA treatment, and the third RTA treatment were performed in the following manner.

[0085] After the single crystal silicon wafer was placed in the RTA processing apparatus, the temperature was raised from room temperature to 800° C. and then maintained at 800° C. for 20 seconds (step b, first RTA). The atmosphere at this time was CH 4 + H 2 / Ar, and the carbon concentration was set to 2%.

[0086] Then, the temperature was raised to 1200°C and maintained at 1200°C for 10 seconds (step c, second RTA). The atmosphere at this time was CH4+H2 / Ar, which was the same as that of the first RTA, and the carbon concentration was set to 2%. Then, the temperature was lowered to room temperature.

[0087] Then, after cooling (step d), the third RTA treatment is performed (step e). The conditions of the third RTA treatment are the same as those of the second RTA treatment.

[0088] Then, the 3C-SiC single crystal film (about 7 nm) formed on the surface of the single crystal silicon wafer is removed (step f). At this time, in order to ensure the removal of the 3C-SiC single crystal film, polishing is performed with a target machining margin of 0.1 μm.

[0089] Finally, SIMS (Secondary Ion Mass Spectrometry) was used to measure the depth distribution of carbon concentration in the manufactured carbon-doped single crystal silicon wafer. The results are shown in Figure 3 A carbon deposition layer is formed on the surface of the carbon-doped single crystal silicon wafer, and the carbon concentration from the surface to 0.14 μm is 3×10 17 atoms / cm 3 Above, the carbon concentration in the surface is 1×10 21 atoms / cm 3 In addition, a diffusion layer of interstitial carbon and silicon is formed at a position further inside the wafer than the carbon deposition layer. The formation range of this layer is from 0.14 μm to 1.5 μm from the surface. In addition, the carbon concentration in the range from 0.14 μm to 1 μm from the surface is 1×10 17 atoms / cm3 In addition, a diffusion layer of vacancies and carbon is formed at a position further inside the wafer than the diffusion layer of interstitial carbon and silicon. The formation range of this layer is deeper than 1.5 μm from the surface. The carbon concentration of the diffusion layer of vacancies and carbon is 1×10 16 atoms / cm 3 Above, 3×10 16 atoms / cm 3 This carbon concentration is close to the solid solubility of carbon at 1200°C. In addition, the detection limit of carbon concentration obtained by SIMS is about 7×10 15 atoms / cm 3 .

[0090] (Comparative Example)

[0091] First, in the same manner as in the example, a 200 mm diameter, (100) crystal orientation, P-type, ordinary resistor, oxygen concentration of 12 ppma (JEITA), and carbon concentration of less than 2.5×10 15 atoms / cm 3 , a single crystal silicon wafer whose defective area is the Nv area is treated as a single crystal silicon wafer that is not carbon-doped.

[0092] Then, a vertical heat treatment furnace is used to perform carbon doping heat treatment. First, after being placed in a vertical heat treatment furnace at 750°C, the temperature is raised to 1000°C at a heating rate of 10°C / min. Then, the temperature is raised from 1000°C to 1200°C at a heating rate of 3°C / min, and maintained at 1200°C for 60 minutes, and then cooled at a cooling rate of -3°C / min. Then, it is taken out of the vertical heat treatment furnace at 700°C. The gas atmosphere of the entire heat treatment process is set to CO2+Ar with a carbon concentration of 1%.

[0093] Finally, the surface oxide film of the heat-treated wafer was removed and the carbon curve of SIMS was evaluated. The results are shown in Figure 4 The carbon concentration from the surface of the wafer to a depth of 0.1 μm was confirmed to be 2×10 16 atoms / cm 3 The carbon concentration near the depth of 2 μm is close to the solid solubility, which is 3×10 16 atoms / cm 3 , the carbon concentration decreases in the body direction.

[0094] The above embodiments are merely examples, and any technical solution having substantially the same structure and having the same function and effect as the technical concept described in the claims of the present invention is included in the protection scope of the present invention.

Claims

1. A method for manufacturing a carbon-doped single crystal silicon wafer, characterized in that: The manufacturing method comprises the following steps: A process for preparing a single crystal silicon wafer that has not been carbon doped; A step of performing a first RTA treatment on the single crystal silicon wafer in an atmosphere containing a carbon atom-containing compound gas, wherein the first RTA treatment is performed by maintaining a temperature of 600° C. to 850° C. for 5 seconds to 60 seconds; A step of performing a second RTA treatment subsequent to the first RTA treatment at a temperature higher than the first RTA treatment, wherein the second RTA treatment is performed by maintaining a temperature of 1100° C. or higher and below the melting point of silicon for 10 seconds or more and 150 seconds or less; A step of cooling the single crystal silicon wafer after performing the second RTA treatment; and After the cooling, a third RTA treatment is performed, wherein the third RTA treatment is performed by maintaining the temperature at 1100° C. or higher and below the melting point of silicon for 10 seconds or more and 150 seconds or less. Through the above process, the single crystal silicon wafer is modified into a carbon-doped single crystal silicon wafer having, from the surface side, a 3C-SiC single crystal layer, a carbon precipitation layer, an interstitial carbon and silicon diffusion layer, and a vacancy and carbon diffusion layer.

2. The method for manufacturing a carbon-doped single crystal silicon wafer according to claim 1, characterized in that: After the step of performing the third RTA treatment, there is further a step of polishing and removing the 3C-SiC single crystal layer.

3. The method for manufacturing a carbon-doped single crystal silicon wafer according to claim 2, characterized in that: In the range from the surface of the carbon-doped single crystal silicon wafer to 0.14 μm, the carbon concentration of the carbon precipitation layer is controlled to be 3×10 17 atoms / cm 3 above.

4. The method for manufacturing a carbon-doped single crystal silicon wafer according to claim 2, characterized in that: The carbon concentration of the diffusion layer of the interstitial carbon and silicon is controlled to be 1×10 17 atoms / cm 3 above.

5. The method for manufacturing a carbon-doped single crystal silicon wafer according to claim 2, characterized in that: In a region deeper than 1 μm from the surface of the carbon-doped single crystal silicon wafer, the carbon concentration of the vacancy and carbon diffusion layer is controlled to be 1×10 16 atoms / cm 3 above.

6. The method for manufacturing a carbon-doped single crystal silicon wafer according to claim 1, characterized in that: The oxygen concentration of the prepared single crystal silicon wafer is set to 11 ppma or more.

7. The method for manufacturing a carbon-doped single crystal silicon wafer according to claim 1, characterized in that: The prepared single crystal silicon wafer is set to be a single crystal silicon wafer composed of any one of an Nv region, a Ni region, and a V region.

8. The method for manufacturing a carbon-doped single crystal silicon wafer according to claim 1, characterized in that: The atmosphere of the first RTA treatment and the second RTA treatment is set to a mixed atmosphere containing a hydrocarbon gas and Ar or H 2 , or a mixed atmosphere containing a hydrocarbon gas and Ar and H 2 .

9. The method for manufacturing a carbon-doped single crystal silicon wafer according to any one of claims 1 to 8, characterized in that: The third RTA treatment was repeated one more time.

10. A carbon-doped single crystal silicon wafer, which is a single crystal silicon wafer doped with carbon and is manufactured according to the method for manufacturing a carbon-doped single crystal silicon wafer according to claim 1, characterized in that: The single crystal silicon wafer has, in order from the surface side, a carbon precipitation layer, a diffusion layer of interstitial carbon and silicon, and a diffusion layer of vacancies and carbon.

11. The carbon-doped single crystal silicon wafer according to claim 10, characterized in that: In the range from the surface of the carbon-doped single crystal silicon wafer to 0.14 μm, the carbon concentration of the carbon precipitation layer is 3×10 17 atoms / cm 3 above.

12. The carbon-doped single crystal silicon wafer according to claim 10, characterized in that: In the range of more than 0.14 μm and less than 1 μm from the surface of the carbon-doped single crystal silicon wafer, the carbon concentration of the diffusion layer of the interstitial carbon and silicon is 1×10 17 atoms / cm 3 above.

13. The carbon-doped single crystal silicon wafer according to claim 10, characterized in that: In a region deeper than 1 μm from the surface of the carbon-doped single crystal silicon wafer, the carbon concentration of the vacancies and the carbon diffusion layer is 1×10 16 atoms / cm 3 above.

14. The carbon-doped single crystal silicon wafer according to claim 10, characterized in that: A 3C-SiC single crystal layer is further provided on the carbon precipitation layer.

15. The carbon-doped single crystal silicon wafer according to claim 10, characterized in that: The oxygen concentration of the carbon-doped single crystal silicon wafer is greater than 11 ppma.

16. The carbon-doped single crystal silicon wafer according to any one of claims 10 to 15, characterized in that: The single crystal silicon wafer is composed of any one of an Nv region, a Ni region and a V region.

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