Silicon wafer for epitaxial growth and epitaxial wafer

Abstract

The present invention provides a silicon wafer for epitaxial growth, which is formed by the Czochralski method, has an N (Neutral) region that does not contain voids and dislocation clusters on the entire surface, and is configured from a single crystal silicon in which the size and density of oxygen precipitation nuclei are adjusted, and which is characterized in that the density of oxygen precipitation nuclei having a size of 18 nm or more within the silicon wafer is less than 5 * 107 / cm3. As a result, a silicon wafer for epitaxial growth, which suppresses defects and has very good surface layer quality, is provided.

Description

Technical Field

[0001] The present invention relates to a silicon wafer and an epitaxial wafer for epitaxial growth. Background Art

[0002] In recent years, in continuously progressing miniaturized and stacked semiconductor devices (Logic, NAND, DRAM), there are two major technical problems.

[0003] One of the technical problems is that since even a very small defect near the wafer surface can cause device failure, a high-quality wafer with fewer or no defects is required near the surface which is the device operation area.

[0004] Another technical problem is that since metal contamination in the process is an important cause of reducing the yield of the device, it is necessary to sufficiently form BMD (Bulk Micro Defect) which is a gettering site for impurity metals.

[0005] As wafers that meet the requirements for defects near the wafer surface in the former case, there are low / no defect crystals PW manufactured in the N (Neutral) region, epitaxial wafers with a defect-free layer formed on a substrate, and annealed wafers. The N (Neutral) region does not contain any of the following: a V-rich region having COP (Crystal Originated Pit) caused by vacancies, an R-OSF (Ring - Oxidation Induced Stacking Fault) region that generates oxidation-induced stacking faults during thermal oxidation, dislocation loops or dislocation clusters caused by interstitial silicon.

[0006] Among them, for annealed wafers, the post-treatment time required to form a defect-free layer is long, and there are problems such as being unsuitable for mass supply and the cost being likely to increase.

[0007] Compared with low / no defect crystal PW, although epitaxial wafers incur additional costs, due to the good defect level on the surface layer, they are mostly used in advanced logic devices where miniaturization continues, the process becomes complex and time-consuming, and the process cost is high.

[0008] Generally, in epitaxial wafers, since a defect-free layer can be formed by post-treatment in a relatively short time, by adopting a highly productive V-rich crystal that grows crystals at a higher speed than low / no defect crystal PW, the additional cost of the EP reaction process can be offset.

[0009] Furthermore, in order to increase BMD (Bulk Micro Defect) which is a gettering site for impurity metals, nitrogen doping is known to be effective.

[0010] However, in nitrogen-doped V-rich crystallization, in the peripheral part of the wafer, a decrease in BMD density caused by the R-OSF region, EP defect formation, and EP defect formation due to plate-like or rod-like COPs during high-nitrogen concentration doping sometimes become problems.

[0011] To avoid such a situation, there is a method of growing the crystal thicker than the product diameter and removing the portion corresponding to the R-OSF region by cylindrical grinding. However, due to an increase in grinding loss and processing time, the grinding processing cost increases.

[0012] Here, the technical problems in the case of manufacturing epitaxial wafers using substrates with V (vacancy) regions are summarized. When the Voids (vacancies) present in the substrate are exposed on the surface, if the inner wall oxide film of the Voids cannot be removed and rendered harmless by a pre-treatment for the EP reaction, it will lead to the generation of EP defects (stacking faults and dislocations (SF)). In particular, if nitrogen doping is carried out, the Void shape will change from a regular octahedron to a plate-like / rod-like elongated shape, making it difficult to remove and render harmless by the pre-treatment for the EP reaction. Therefore, the generation of EP defects caused by Voids will increase. Further, in nitrogen-doped (100) and (551) substrates, since Voids are formed that extend deeply in a direction orthogonal to the wafer surface, it is more difficult to remove and render harmless by the pre-treatment for the EP reaction than when using (100) substrates, further increasing the generation of EP defects caused by Voids.

[0013] As another method, there is a method of using a crystal in the N (Neutral) region without R-OSF. However, as will be described later, even in a crystal in the N (Neutral) region without R-OSF, oxygen precipitation nuclei present in the N (Neutral) region sometimes cause the generation of EP defects, and it is difficult to achieve an extremely good EP surface defect grade.

[0014] Next, the importance of BMD (bulk microdefects), which are gettering sites for impurity metals that suppress the reduction in device yield due to metal contamination during the process, will be explained.

[0015] In the operation (source / drain current) of a MOSFET, the static capacitance of the gate insulating film (= dielectric constant of the insulating film × gate area / thickness of the insulating film) needs to ensure a necessary amount. However, as miniaturization progresses, the gate length becomes shorter, and the thickness of the gate insulating film is thinned accordingly to compensate for the reduction in the gate area.

[0016] Therefore, in recent devices, the gate insulating film has an extremely thin EOT (equivalent oxide thickness) of about 0.5 nm, and the uniformity of the gate insulating film is an important factor for the reliability of device operation.

[0017] Therefore, various heat treatments of the device process are made low-temperature / short-time to achieve uniformity in the film thickness / film quality of the gate insulating film.

[0018] However, as a drawback of the low-temperature / short-time of the device process, conventionally, in the device process, BMD (bulk microdefects), which are gettering sites for impurity metals, are sufficiently formed in the substrate. In contrast, due to the low-temperature / short-time, the formation of BMD in the device process becomes less, resulting in a reduction in the gettering ability for impurity metals, and sometimes the device yield decreases.

[0019] Due to such problems, for advanced low-temperature / short-time device processes, it is necessary to fabricate a wafer that is more likely to form BMD compared to the prior art and has a high gettering ability even in low-temperature / short-time device processes.

[0020] In contrast, in the epitaxial wafer using the crystal of the previously described N (Neutral) region without R-OSF for the substrate, there is a technical problem that it is difficult to form BMD compared to the epitaxial wafer using the V-rich region as the substrate.

[0021] Next, taking the prior art as an example, these technical problems will be specifically described.

[0022] In Patent Document 1, a technique is disclosed. When the V region that generates Void-type defects is used for the substrate, the number of defects with an opening size of 20 nm or less of the Void-type defects appearing on the wafer surface is set to at most 0.02 defects / cm 2 Hereinafter, the generation of EP defects is suppressed to at most 0.02 defects / cm 2 Hereinafter, however, when converted to a 300 mm wafer, there are also 14 defects. In the case of using a V region substrate with Voids, even if the Void size or density is adjusted, it is difficult to improve the defect level by one level.

[0023] In Patent Document 2, an epitaxial wafer is disclosed that uses an N (Neutral) region substrate doped with nitrogen and carbon and having no secondary defects such as Voids and dislocation clusters. In Patent Document 3, a technique for suppressing the generation of EP defects by doping nitrogen and carbon is disclosed. However, if the defect density is 0.05 defects / cm 2 Hereinafter, when converted to a 300 mm wafer, there are at most 35 defects, which is not a sufficient defect level for advanced logic devices with extremely few allowable defects and high process costs as the process becomes more complex and long-term. In these prior arts, there is no clear superiority in using an N (Neutral) region substrate over a V region substrate.

[0024] In Patent Document 4, single-crystalline silicon with the defect distribution of the crystallized entire surface adjusted to an N (Neutral) region is used for the substrate, whereby the generation of EP defects can be made at most 2 per wafer (0.0028 per cm 2 ) in a 300 mm wafer, showing the effectiveness of using single-crystalline silicon with the defect distribution of the crystallized entire surface adjusted to an N (Neutral) region for the substrate. However, the generation source of EP defects in the N (Neutral) region is not clear, and it is difficult to obtain stable EP surface quality or further improve the EP surface quality only by using a silicon substrate in the N (Neutral) region.

[0025] Prior Art Documents

[0026] Patent Documents

[0027] Patent Document 1: Japanese Patent Application Laid-Open No. 2004-43256

[0028] Patent Document 2: WO2001 / 079593

[0029] Patent Document 3: Japanese Patent Application Laid-Open No. 2007-186376

[0030] Patent Document 4: Japanese Patent Application Laid-Open No. 2019-206451 Summary of the Invention

[0031] (1) Technical Problems to be Solved

[0032] An object of the present invention is to provide a silicon wafer for epitaxial growth that suppresses defects and has very good surface quality.

[0033] (2) Technical Solutions

[0034] The present invention is made to solve the above technical problems, and provides a silicon wafer for epitaxial growth, which is composed of single-crystalline silicon formed by the Czochralski method, having an N (Neutral) region without voids and dislocation clusters on the entire surface and adjusted in the size and density of oxygen precipitation nuclei.

[0035] The density of oxygen precipitation nuclei having a size of 18 nm or more in the silicon wafer is less than 5×10 7 / cm 3 .

[0036] If such a silicon wafer for epitaxial growth is used, the defects in the epitaxial layer can be suppressed by reducing the density of oxygen precipitation nuclei having a large size.

[0037] In addition, the average size of the oxygen precipitation nuclei having a size of 12 nm or more in the silicon wafer is 18.5 nm or less, and the density of the oxygen precipitation nuclei having a size of 12 nm or more is 4×108 / cm 3 as follows.

[0038] If such oxygen precipitation nuclei are present, the defects in the epitaxial layer can be further suppressed.

[0039] In addition, the concentration of nitrogen doped in the single crystal silicon is 2×10 13 atoms / cm 3 ~30×10 13 atoms / cm 3 .

[0040] If such a silicon wafer is used, it has suitable gettering ability.

[0041] In addition, any one of the crystal plane orientations (100), (110), and (551) of the silicon wafer can be applied.

[0042] Not only the crystal plane orientation (100) that has been continuously used in advanced logic devices can suppress the generation of defects, but also the crystal plane orientations (110) and (551) that have been continuously studied in recent years can similarly suppress the generation of defects. This can contribute to the development and performance improvement of future advanced logic devices.

[0043] In addition, it is preferably an epitaxial wafer formed by forming an epitaxial layer on the surface of the silicon wafer for epitaxial growth, and the EP-SF (stacking fault and dislocation) in the epitaxial layer is 0.001 per cm 2 or less.

[0044] If such an epitaxial wafer is used, it becomes an epitaxial wafer with extremely few EP-SF (stacking fault and dislocation) and is very suitable for good advanced devices.

[0045] In addition, the BMD density in the silicon wafer after oxidation heat treatment at 780°C for 3 hours + 1000°C for 16 hours of the epitaxial wafer is 1×10 8 / cm 3 or more, and for the target BMD density, it satisfies the target BMD density ≤ 9.6875×10 8 {exp(Ini.Oi[ppma-ASTM’79]-21.99-5.35)} ˆ0.3961.

[0046] If such an epitaxial wafer is used, a target BMD density of 1×10 8 / cm 3 or more can be obtained. Although it is an N region, it can achieve the same BMD level as the V region and can obtain sufficient gettering ability as the gettering site for impurity metals.

[0047] (III) Beneficial effects

[0048] As described above, in the case of the silicon wafer for epitaxial growth of the present invention, by reducing the density of oxygen precipitate nuclei having a large size, defects in the epitaxial layer can be suppressed. As a result, a silicon wafer for epitaxial growth having a very good surface quality can be obtained, and it can also contribute to suppressing defects in semiconductor devices caused by the progress of miniaturization and stacking.

[0049] In addition, if the BMD density in the silicon wafer after oxidation heat treatment is made within an appropriate range, although it is an N region, a BMD level equivalent to that of the V region can be achieved, and sufficient gettering ability as a gettering site for impurity metals can be obtained. As a result, it is possible to suppress a decrease in the yield of devices due to metal contamination in the process.

[0050] Furthermore, regardless of the crystal plane orientation of the wafer, these good qualities can be obtained, which can contribute to the development and performance improvement of future advanced logic devices. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] Figure 1 It is a diagram showing an embodiment of an apparatus for manufacturing single crystal silicon by the Czochralski method that can be used in the present invention.

[0052] DETAILED DESCRIPTION OF THE EMBODIMENTS

[0053] As described above, there is a demand for developing a silicon wafer for epitaxial growth that suppresses defects and has a very good surface quality.

[0054] In response to this, first, the inventors of the present application deeply investigated and studied the defect generation sources that cause EP defects even in the N (Neutral) region as in Patent Document 4.

[0055] As a result, it was clearly found that in the N (Neutral) region, for the defect generation sources that cause EP defects, oxygen precipitate nuclei having a specified size or more existing in the N (Neutral) region are likely to cause EP-SF (stacking fault and dislocation) formation with a certain probability.

[0056] More specifically, it was found that there is a relationship of EP defect number = A·exp(mean precipitate nucleus size / B) between the oxygen precipitate nuclei and EP-SF (stacking fault and dislocation) in the as-grown N (Neutral) region (without Void (COP)) substrate, and by making the oxygen precipitate nuclei of 18 nm or more less than 5×10 7 / cm 3 , more preferably, the average size of the oxygen precipitate nuclei of 12 nm or more is 18.5 nm or less and the density is 4×10 8 / cm3 Hereinafter, the number of EP defects can be made 0.001 pieces / cm 2 Hereinafter (converted to less than 0.7 pieces per wafer (pieces / wf) in a 300 mm wafer), the generation of EP-SF (stacking faults and dislocations) is made to be less than 1 on average in a 300 mm wafer, achieving a very good grade.

[0057] In addition, in this correlation formula, A corresponds to the frequency factor and is a parameter proportional to the density of oxygen precipitation nuclei, and B is a process parameter that affects the tolerance of oxygen precipitation nuclei in the epitaxial layer formation process.

[0058] In addition, the control of the density and size of oxygen precipitation nuclei in such an as-grown state can only be implemented when the N (Neutral) region is used as the substrate. When a V-region substrate is used, the density and size of oxygen precipitation nuclei strongly depend on the nitrogen concentration and cannot be controlled.

[0059] In addition, in the epitaxial wafer using the crystal of the N (Neutral) region as the substrate, compared with the epitaxial wafer using the V-rich region as the substrate, there is a technical problem that it is difficult to form BMD. However, when doped with nitrogen at 2×10 13 -3×10 14 atoms / cm 3 it is found that in the crystal in which the density and size of the precipitation nuclei in the above-mentioned N (Neutral) region are controlled, compared with the case of using a V-region substrate, by making the substrate oxygen concentration +5.35 [ppma-ASTM’79] high oxygen, the target BMD density ≤9.6875×10 8 {exp(Ini.Oi[ppma - ASTM’79]-21.99 - 5.35)}^0.3961 can be achieved, and thus a BMD grade equivalent to that of the case of using a V-region substrate can be achieved.

[0060] Here, when the V-rich region is used as the substrate, the target BMD density ≤9.6875×10 8 {exp(Ini.Oi[ppma - ASTM’79]-21.99)}^0.3961.

[0061] Furthermore, the epitaxial wafer using the substrate in which the density and size of oxygen precipitation nuclei in the as-grown state are controlled in the N (Neutral) region obtained in the present invention is not limited to the epitaxial wafer with the crystal plane orientation (100) that has been used in advanced logic devices. The crystal plane orientations of the wafer doped with nitrogen, (110) and (551), can also have very good surface quality and BMD quality.

[0062] The present invention has been completed through the in-depth research of the inventors. By using low / no-defect crystals manufactured in the nitrogen-doped N (Neutral) region for the epitaxial wafers of the substrate, and by controlling the density and size of oxygen precipitation nuclei in the as-grown state, it is possible to fabricate epitaxial wafers that have an extremely good EP surface defect grade regardless of the crystal plane orientation of the wafer, and at the same time have a high gettering ability.

[0063] By adopting the present invention, it is possible to fabricate an epitaxial wafer that suppresses EP defects leading to device failures and has an extremely good EP surface defect grade. Therefore, it is possible to manufacture advanced logic devices with a high yield, which have extremely few allowable defects and high process costs as the process becomes more complex and prolonged.

[0064] Hereinafter, with reference to Figure 1 One embodiment of the present invention will be described.

[0065] In the present invention, for the manufacture of single-crystalline silicon, for example, the single-crystalline silicon manufacturing apparatus shown in Figure 1 is used, which can grow single-crystalline silicon (hereinafter, sometimes simply referred to as single crystal or crystal) by the Czochralski method (CZ method) under the condition that the entire crystal surface is an N region. With reference to Figure 1 such a single-crystalline silicon manufacturing apparatus will be described, but the single-crystalline silicon manufacturing apparatus that can be used in the present invention is not limited to this manufacturing apparatus.

[0066] Figure 1 The appearance of the single-crystalline silicon manufacturing apparatus shown in

[0067] is composed of a main chamber 1 and a pulling chamber 2 communicating therewith. Inside the main chamber 1, a graphite crucible 6 and a quartz crucible 5 are provided. A heater 7 is provided so as to surround the graphite crucible 6 and the quartz crucible 5. By the heater 7, the polysilicon raw material accommodated in the quartz crucible 5 is melted to become a raw material melt 4. In addition, a heat insulating material 8 is provided to prevent the radiant heat from the heater 7 from affecting the main chamber 1 and the like.

[0068] Further, during single crystal cultivation, an inert gas such as argon as a purification gas is introduced from the gas inlet 10, passes between the single crystal rod 3 being pulled up and the gas rectifying cylinder 11, then passes between the heat shield 12 and the melt surface of the raw material melt 4, and is discharged from the gas outlet 9. By controlling the flow rate of the introduced gas and the discharge amount of the gas based on a pump or a valve, the pressure inside the chamber during pulling is controlled.

[0069] In addition, when cultivating crystals by the Czochralski method, a magnetic field can also be applied by the magnetic field applying device 13. Such a method of applying a magnetic field is called the MCZ method.

[0070] In the present invention, when growing crystals by such a single crystal pulling device based on the Czochralski method, the ratio of the pulling speed V [mm / min] to the axial temperature gradient G [°C / mm] of the solid-liquid interface is controlled to pull the crystals, whereby the defective region of the cultivated single crystal can be made into an entire surface N region. In addition, the size and density of oxygen precipitation nuclei in the single crystal can be controlled by adjusting the oxygen concentration, nitrogen concentration, and thermal history of the crystal during single crystal cultivation. The oxygen concentration can be controlled, for example, by adjusting the rotation speed of the crucible or the convection of the raw material melt, the nitrogen concentration can be controlled by the N (nitrogen) doping amount of the raw material melt, and the thermal history can be controlled by the pulling speed of the crystal or the furnace structure.

[0071] The silicon wafer for epitaxial growth according to an embodiment of the present invention is a silicon wafer made of single crystal silicon formed by the Czochralski method, having an entire surface as an N (Neutral) region free of voids and dislocation clusters and the size and density of oxygen precipitation nuclei adjusted. The density of oxygen precipitation nuclei having a size of 18 nm or more in the silicon wafer is less than 5×10 7 / cm 3 , more preferably, the average size of oxygen precipitation nuclei having a size of 12 nm or more is 18.5 nm or less, and the density of oxygen precipitation nuclei having a size of 12 nm or more is 4×10 8 / cm 3 or less.

[0072] Thus, by reducing the density of large-sized oxygen precipitation nuclei, the generation of defects in the epitaxial layer can be suppressed. In addition, the upper limit value of the size of oxygen precipitation nuclei having a size of 18 nm or more in the silicon wafer is not particularly limited, and can be, for example, 40 nm or less. The lower limit value of the density of oxygen precipitation nuclei having a size of 18 nm or more is not particularly limited, and can be, for example, 1×10 6 / cm 3In addition, the upper limit value of the size of oxygen precipitation nuclei with a size of 12 nm or more is not particularly limited, and can be, for example, 40 nm or less. The lower limit value of the average size of oxygen precipitation nuclei with a size of 12 nm or more is not particularly limited, and can be, for example, 12 nm or more. The lower limit value of the density of oxygen precipitation nuclei with a size of 12 nm or more is not particularly limited, and can be, for example, 1×10 6 / cm 3 or more.

[0073] In addition, the concentration of nitrogen doped in single-crystalline silicon is preferably 2×10 13 atoms / cm 3 ~30×10 13 atoms / cm 3 .

[0074] If it is such a silicon wafer, the gettering ability is also sufficient, and it can be suitably applied to advanced devices.

[0075] In addition, any one of (100), (110), and (551) of the crystal plane orientation of the silicon wafer can control the size and density of oxygen precipitation nuclei in the entire surface N (Neutral) region of the present invention.

[0076] Not only the crystal plane orientation (100) that has been used in advanced logic devices can suppress the generation of defects, but also the crystal plane orientations (110) and (551) that have been continuously studied in recent years can suppress the generation of defects in the same way. It can contribute to the development and performance improvement of future advanced logic devices.

[0077] In addition, in the present invention, an epitaxial wafer is formed by forming an epitaxial layer on the surface of a silicon wafer for epitaxial growth, and the EP-SF (stacking fault and dislocation) in the epitaxial layer is 0.001 / cm 2 or less.

[0078] If it is such an epitaxial wafer, it is an epitaxial wafer with very few EP-SF (stacking fault and dislocation) and is very good, so it can fully withstand the fabrication of advanced devices. In addition, the lower limit value of the EP-SF (stacking fault and dislocation) in the epitaxial layer is not particularly limited, and can be, for example, 0 / cm 2 or more.

[0079] In addition, the BMD density in the silicon wafer after the oxidation heat treatment of 780 °C for 3 hours + 1000 °C for 16 hours of the epitaxial wafer is 1×10 8 / cm 3 or more, and for the target BMD density, it satisfies the target BMD density ≤ 9.6875×10 8 {exp(Ini.Oi[ppma-ASTM’79]-21.99-5.35)} ˆ0.3961.

[0080] If such an epitaxial wafer is used, a target BMD density of 1×10 8 / cm 3 or higher can be obtained. Although it is the N region, it can achieve the same BMD level as the V region, and thus sufficient gettering ability as gettering sites for impurity metals can be obtained. In addition, the upper limit value of the BMD density in the silicon wafer after oxidation heat treatment is not particularly limited. For example, it can be 10×10 8 / cm 3 or lower. In addition, the target BMD density is not particularly limited. For example, it can be 1×10 8 / cm 3 or higher and 10×10 8 / cm 3 or lower.

[0081] In addition, when the V-rich region is used as the substrate, in order to achieve the target BMD density, by making it satisfy the target BMD density ≤ 9.6875×10 8 {exp(Ini.Oi[ppma - ASTM’79] - 21.99)} ˆ0.3961, a target BMD density of 1×10 8 / cm 3 or higher can be obtained.

[0082] In addition, it is ideal to evaluate the size and density of oxygen precipitation nuclei with an LST (Laser scattering tomography) inspection device. For example, LST-2500 manufactured by Semilab Japan KK or MO441 manufactured by MITSUI MINING&SMELTING CO. can be used.

[0083] Here, when MO441 (manufactured by MITSUI MINING&SMELTING CO.) is used, the detection sensitivity is 18 nm or higher. If the density of oxygen precipitation nuclei to be detected is less than 5×10 7 / cm 3, although it can generally suppress EP defects, since the detection and evaluation are performed at a size close to the limit of the detection sensitivity of MO441, it is preferable to perform the detection and evaluation of the size with higher sensitivity. For example, if it is LST-2500 manufactured by Semilab Japan KK, the detection sensitivity is 12 nm or more, enabling high-sensitivity detection and evaluation. When detecting and evaluating oxygen precipitation nuclei with high sensitivity using LST-2500 manufactured by Semilab Japan KK, by making the average size of oxygen precipitation nuclei with a size of 12 nm or more 18.5 nm or less, and the density of oxygen precipitation nuclei with a size of 12 nm or more is 4×10 8 / cm 3 or less, thereby enabling more reliable suppression and control of EP defects.

[0084] By detecting and evaluating the precipitated nuclei with higher sensitivity and good accuracy, thereby more correctly obtaining the frequency factor A, which is the parameter proportional to the density of oxygen precipitation nuclei in EP defect number = A·exp(average precipitated nucleus size / B), and the process parameter B that affects the tolerance of oxygen precipitation nuclei in the epitaxial layer formation process, enabling more reliable implementation of the suppression and control of EP defects.

[0085] Examples

[0086] Hereinafter, examples and comparative examples of the present invention will be specifically described, but the present invention is not limited to these examples.

[0087] (Comparative Example 1)

[0088] In a 32-inch (diameter 812.8 mm) crucible, 410 kg of silicon raw material was melted, and a transverse magnetic field with a central magnetic field intensity of 4000 G was applied by the MCZ method, and a 300-mm single crystal silicon (undoped with nitrogen) with an axial orientation of <100> was grown by controlling V / G with the crystallization plane as the N (Neutral) region. Wafers were cut from the single crystal silicon thus produced, and lapping, chamfering, and polishing were performed to produce multiple silicon wafers for epitaxial growth with a crystal plane orientation of (100).

[0089] Next, the density and size of oxygen precipitation nuclei present in as-grown were evaluated for this silicon wafer for epitaxial growth using an LST (Laser scattering tomography) inspection device, that is, LST-2500 manufactured by Semilab Japan KK. The results were as follows:

[0090] The density of oxygen precipitation nuclei with a size of 18 nm or more in the wafer center part R0 - 50 mm was 7.5×10 7 / cm 3, the density of oxygen precipitation nuclei above 12 nm is 7.0×10 8 / cm 3 , and the average size is 19.2 nm;

[0091] In R60 - 120 mm, the density of oxygen precipitation nuclei above 18 nm is 4.2×10 7 / cm 3 , the density of oxygen precipitation nuclei above 12 nm is 4.2×10 8 / cm 3 , and the average size is 18.3 nm;

[0092] In R130 - 150 mm, the density of oxygen precipitation nuclei above 18 nm is 5.5×10 7 / cm 3 , the density of oxygen precipitation nuclei above 12 nm is 8.0×10 8 / cm 3 , and the average size is 19.0 nm.

[0093] Using this silicon wafer for epitaxial growth, a 4 - μm epitaxial layer was formed at 1130°C to fabricate 25 epitaxial wafers. The obtained epitaxial wafers were evaluated for defects using the SP3 manufactured by KLA Tencor Corporation with an Oblique mode 32 - nm UP sensitivity.

[0094] As a result, the average EP defect density in each wafer is 0.0019 per cm in R0 - 50 mm 2 , 0.0010 per wafer (per wf) in R60 - 120 mm, and 0.0021 per cm in R130 - 150 mm 2 , and the EP defects on the entire surface of the 300 - mm wafer are 0.99 per wafer (per wf).

[0095] At this time, the oxygen concentration in the single - crystal silicon is 25.2 [ppma - ASTM’79], and the BMD density after oxidation heat treatment at 780°C for 3 hours + 1000°C for 16 hours after EP (epitaxy) is 4.1×10 8 [ / cm 3 .

[0096] (Comparative Example 2)

[0097] Doping nitrogen in the concentration range of 4×10 13 -3×10 14 atoms / cm 3 , and fabricating the silicon wafer for epitaxial growth and the epitaxial wafer under the same conditions as in Comparative Example 1 except for this.

[0098] Similar to Comparative Example 1, the density and size of the oxygen precipitate nuclei present in the as-grown state were evaluated using an LST inspection apparatus. The results were as follows:

[0099] The density of oxygen precipitate nuclei with a size of 18 nm or more in the center part R0-50 mm of the wafer was 9.2×10 7 / cm 3 , the density of oxygen precipitate nuclei with a size of 12 nm or more was 9.0×10 8 / cm 3 , and the average size was 21.0 nm;

[0100] The density of oxygen precipitate nuclei with a size of 18 nm or more in R60-120 mm was 5×10 7 / cm 3 , the density of oxygen precipitate nuclei with a size of 12 nm or more was 5×10 8 / cm 3 , and the average size was 18.7 nm;

[0101] The density of oxygen precipitate nuclei with a size of 18 nm or more in R130-150 mm was 1.1×10 8 / cm 3 , the density of oxygen precipitate nuclei with a size of 12 nm or more was 1.0×10 9 / cm 3 , and the average size was 22.0 nm.

[0102] The average EP defect density in each epitaxial wafer was 0.0029 per cm in R0-50 mm 2 , 0.0013 per wafer in R60-120 mm, and 0.0036 per cm in R130-150 mm 2 , and the EP defects on the entire 300 mm wafer were 1.46 per wafer.

[0103] At this time, the oxygen concentration in the single crystal silicon was 25.5 [ppma-ASTM’79], and the BMD density after the oxidation heat treatment at 780 °C for 3 hours + 1000 °C for 16 hours after EP (epitaxy) was 4.7×10 8 [ / cm 3 .

[0104] (Example 1)

[0105] The density and size of the oxygen precipitate nuclei were adjusted by adjusting the pulling speed. Except for this, the silicon wafers for epitaxial growth and the epitaxial wafers were fabricated under the same conditions as in Comparative Example 1.

[0106] Similar to Comparative Examples 1 and 2, the density and size of the oxygen precipitate nuclei present in the as-grown state were evaluated using an LST inspection apparatus. The results were as follows:

[0107] The density of oxygen precipitation nuclei with a size of 18 nm or more in the central part R0 - 50 mm of the wafer is 3.8×10 7 / cm 3 , the density of oxygen precipitation nuclei with a size of 12 nm or more is 3.6×10 8 / cm 3 , and the average size is 18.2 nm;

[0108] The density of oxygen precipitation nuclei with a size of 18 nm or more in R60 - 120 mm is 2.9×10 7 / cm 3 , the density of oxygen precipitation nuclei with a size of 12 nm or more is 2.6×10 8 / cm 3 , and the average size is 18.1 nm;

[0109] The density of oxygen precipitation nuclei with a size of 18 nm or more in R130 - 150 mm is 3.0×10 7 / cm 3 , the density of oxygen precipitation nuclei with a size of 12 nm or more is 2.7×10 8 / cm 3 , and the average size is 18.3 nm.

[0110] The average EP defect density in each epitaxial wafer is 0.0009 per cm in R0 - 50 mm 2 , 0.0006 per wafer in R60 - 120 mm, and 0.0007 per cm in R130 - 150 mm 2 , and the EP defects on the entire surface of the 300 - mm wafer are 0.46 per wafer.

[0111] At this time, in order to make the target BMD density after the oxidation heat treatment at 780 °C for 3 hours + 1000 °C for 16 hours after EP (epitaxy) be 4×10 8 / cm 3 or more, according to the relationship of [Equation A], it is calculated that the oxygen concentration in the single - crystal silicon must be 25.1 [ppma - ASTM’79] or more. The actual oxygen concentration is 25.2 [ppma - ASTM’79], and the BMD density is 4.2×10 8 [ / cm 3 . The target BMD density ≤ 9.6875×10 8 {exp(Ini.Oi[ppma - ASTM’79] - 21.99 - 5.35)} ˆ0.3961 [Equation A].

[0112] (Example 2)

[0113] The adjustment of the density and size of oxygen precipitation nuclei is implemented by adjusting the pulling speed. Other than that, the silicon wafers for epitaxial growth and the epitaxial wafers are fabricated under the same conditions as in Comparative Example 2.

[0114] Similar to Comparative Examples 1 and 2, the density and size of the as-grown oxygen precipitation nuclei were evaluated with an LST inspection device. The results were as follows:

[0115] The density of oxygen precipitation nuclei with a size of 18 nm or more in the wafer center part R0 - 50 mm was 4.0×10 7 / cm 3 The density of oxygen precipitation nuclei with a size of 12 nm or more was 3.8×10 8 / cm 3 and the average size was 18.4 nm;

[0116] The density of oxygen precipitation nuclei with a size of 18 nm or more in R60 - 120 mm was 3.1×10 7 / cm 3 The density of oxygen precipitation nuclei with a size of 12 nm or more was 2.9×10 8 / cm 3 and the average size was 18.2 nm;

[0117] The density of oxygen precipitation nuclei with a size of 18 nm or more in R130 - 150 mm was 2.8×10 7 / cm 3 The density of oxygen precipitation nuclei with a size of 12 nm or more was 2.5×10 8 / cm 3 and the average size was 18.4 nm.

[0118] The average EP defect density in each epitaxial wafer was 0.0009 per cm in R0 - 50 mm, 0.0007 per wafer in R60 - 120 mm, and 0.0006 per cm in R130 - 150 mm. 2 The EP defects on the entire surface of the 300 mm wafer were 0.49 per wafer. 2 At this time, in order to make the target BMD density after the oxidation heat treatment at 780 °C for 3 hours + 1000 °C for 16 hours after EP (epitaxy) be 4×10

[0119] / cm 8 or more, according to the relationship of [Equation A], it was calculated that the oxygen concentration in the single crystal silicon must be 25.1 [ppma - ASTM’79] or more. The actual oxygen concentration was 25.4 [ppma - ASTM’79], and the BMD density was 4.5×10 3 [ / cm 8 3 .

[0120] (Example 3)

[0121] Set the axial orientation for cultivating crystals to <110> and <551>. Except for this, epitaxial growth silicon wafers and epitaxial wafers with crystal plane orientations (110) and (551) are fabricated under the same conditions as in Example 2.

[0122] For the epitaxial growth silicon wafers made of 300 mm single-crystalline silicon with an axial orientation of <100>, similar to Example 2, the density and size of the oxygen precipitation nuclei existing in the as-grown state are evaluated with an LST inspection device. The results are as follows:

[0123] The density of oxygen precipitation nuclei with a size of 18 nm or more in the wafer center part R0 - 50 mm is 3.9×10 7 / cm 3 , and the density of oxygen precipitation nuclei with a size of 12 nm or more is 3.7×10 8 / cm 3 , and the average size is 18.4 nm;

[0124] The density of oxygen precipitation nuclei with a size of 18 nm or more in R60 - 120 mm is 3.3×10 7 / cm 3 , and the density of oxygen precipitation nuclei with a size of 12 nm or more is 3.0×10 8 / cm 3 , and the average size is 18.2 nm;

[0125] The density of oxygen precipitation nuclei with a size of 18 nm or more in R130 - 150 mm is 2.5×10 7 / cm 3 , and the density of oxygen precipitation nuclei with a size of 12 nm or more is 2.4×10 8 / cm 3 , and the average size is 18.4 nm.

[0126] Cleavage planes cannot be obtained for the epitaxial growth silicon wafers made of 300 mm single-crystalline silicon with an axial orientation of <551>, so LST evaluation cannot be carried out.

[0127] The average EP defect density in each epitaxial wafer is the same as that in Example 2 for both crystal plane orientations (110) and (551).

[0128] At this time, in order to make the target BMD density after oxidation heat treatment at 780 °C for 3 hr + 1000 °C for 16 hr after EP (epitaxy) be 4×10 8 / cm 3As described above, based on the relationship of [Formula A], the oxygen concentration in single-crystalline silicon must be 25.1 [ppma - ASTM’79] or more. In single-crystalline silicon with any one of the axial orientations <110> and <551>, the actual oxygen concentration is 25.1 [ppma - ASTM’79]. In an epitaxial growth silicon wafer made of 300 mm single-crystalline silicon with the axial orientation <110>, the BMD density is 4.0×10 8 [ / cm 3 .

[0129] An epitaxial growth silicon wafer made of single-crystalline silicon with the axial orientation <551> cannot obtain a cleavage plane, and thus the LST evaluation cannot be performed.

[0130] Table 1 shows the conditions of the examples and comparative examples, and the density and average size of oxygen precipitation nuclei, EP defect density, and total number of EP defects of the epitaxial wafers manufactured under each condition.

[0131] [Table 1]

[0132]

[0133] [Results]

[0134] As can be seen from Table 1, compared with Comparative Examples 1 and 2, the EP defect density and the total number of EP defects of Examples 1, 2, and 3 are smaller on any side and are excellent. The EP defect densities of Comparative Examples 1 and 2 are both 0.001 pieces / cm 2 Above, in contrast, those of Examples 1, 2, and 3 are all less than 0.001 pieces / cm 2 ; the total number of EP defects of Comparative Examples 1 and 2 are both 0.5 pieces / sheet or more, and in contrast, those of Examples 1, 2, and 3 are all less than 0.5 pieces / sheet.

[0135] In addition, based on the above results, in the manufacture of an epitaxial wafer using an N (Neutral) region (Void (COP)-free) substrate, a relationship of EP defect number = A·exp(mean precipitate nucleus size / B) was found between the EP defect number and as-grown (native) precipitate nuclei, where A = the density of precipitate nuclei with a size of a×12 nm or more [ / cm 3 , according to Comparative Examples 1, 2, and Example 1, a = 2.80××10 -10 , B = 10.

[0136] As described above, in the manufacture of an epitaxial wafer using an N (Neutral) region (Void (COP)-free) substrate, the relationship between the EP defect number and as-grown (native) precipitate nuclei is clear. For the precipitate nuclei in the wafer, by making the size of 18 nm or more less than 5×10 7 / cm 3, more preferably, the average size is above 12 nm and below 18.5 nm, and the density of the precipitation nuclei above 12 nm is 4×10 8 / cm 3 or less, and it is possible to obtain an epitaxial wafer in which the generation of EP defects is suppressed to 0.001 or less per cm 2 and which has a very good EP surface layer quality. In addition, the effects of the present invention can be obtained regardless of the crystal plane orientation of the wafer.

[0137] In addition, regarding the BMD density after the oxidation heat treatment of 780 °C for 3 hr + 1000 °C for 16 hr of the epitaxial wafer, for the target BMD density, by satisfying the target BMD density ≤ 9.6875×10 8 {exp(Ini.Oi[ppma - ASTM’79] - 21.99 - 5.35)} ˆ 0.3961 (in the case of V-rich: target BMD density ≤ 9.6875×10 8 {exp(Ini.Oi[ppma - ASTM’79] - 21.99)} ˆ 0.3961), it is possible to obtain an epitaxial wafer with a BMD density of 1×10 8 / cm 3 or more, having an in-plane uniform BMD distribution and also having a high gettering ability.

[0138] Thus, according to the present invention, it is possible to manufacture an epitaxial wafer that suppresses EP defects that cause device failures, has an extremely good EP surface layer defect grade, and also has a high gettering ability. Therefore, it is possible to manufacture advanced logic devices with a very low allowable number of defects and a high process cost as the process becomes more complex and longer with a high yield.

[0139] The present invention includes the following aspects.

[0140] [1] A silicon wafer for epitaxial growth, characterized in that

[0141] it is a silicon wafer composed of single crystal silicon formed by the Czochralski method, with the entire surface being an N (Neutral) region free of voids and dislocation clusters and the size and density of oxygen precipitation nuclei being adjusted,

[0142] the density of the oxygen precipitation nuclei with a size of 18 nm or more in the silicon wafer is less than 5×10 7 / cm 3 .

[0143] [2] The silicon wafer for epitaxial growth according to [1] above, wherein the average size of the oxygen precipitation nuclei with a size of 12 nm or more in the silicon wafer is 18.5 nm or less, and the density of the oxygen precipitation nuclei with a size of 12 nm or more is 4×10 8 / cm 3 as follows.

[0144] [3] The silicon wafer for epitaxial growth as described in [1] or [2] above, wherein the concentration of nitrogen doped in the single-crystalline silicon is 2×10 13 atoms / cm 3 ~30×10 13 atoms / cm 3 .

[0145] [4] The silicon wafer for epitaxial growth as described in any one of [1] to [3] above, wherein the crystal plane orientation of the silicon wafer is any one of (100), (110), and (551).

[0146] [5] An epitaxial wafer, characterized in that

[0147] it is formed by forming an epitaxial layer on the surface of the silicon wafer for epitaxial growth as described in any one of [1] to [4] above,

[0148] the EP-SF (stacking fault and dislocation) in the epitaxial layer is 0.001 per cm 2 or less.

[0149] [6] The epitaxial wafer as described in [5], wherein the BMD density in the silicon wafer after the oxidation heat treatment at 780°C for 3 hours + 1000°C for 16 hours of the epitaxial wafer is 1×10 8 / cm 3 or more, and for the target BMD density, it satisfies the target BMD density ≤ 9.6875×10 8 {exp(Ini.Oi[ppma - ASTM’79] - 21.99 - 5.35)} ˆ0.3961.

[0150] In addition, the present invention is not limited to the above embodiments. The above embodiments are illustrative. Technical solutions having the same technical idea as that described in the claims of the present invention and achieving the same effects are all included in the technical scope of the present invention.

Claims

1. A silicon wafer for epitaxial growth, Characterized in that, It is a silicon wafer composed of single-crystal silicon formed by the Czochralski method, with the entire surface being an N (Neutral) region without voids and dislocation clusters and the size and density of oxygen precipitation nuclei being adjusted. The density of the oxygen precipitation nuclei with a size of 18 nm or more in the silicon wafer is less than 5×10 7 / cm 3 .

2. The silicon wafer for epitaxial growth according to claim 1, Characterized in that, The average size of the oxygen precipitation nuclei with a size of 12 nm or more in the silicon wafer is 18.5 nm or less, and the density of the oxygen precipitation nuclei with a size of 12 nm or more is 4×10 8 / cm 3 or less.

3. The silicon wafer for epitaxial growth according to claim 1, Characterized in that, The concentration of nitrogen doped in the single-crystalline silicon is 2×10 13 atoms / cm 3 ~30×10 13 atoms / cm 3 .

4. The silicon wafer for epitaxial growth according to claim 1, Characterized in that, The crystal plane orientation of the silicon wafer is any one of (100), (110), and (551).

5. An epitaxial wafer, Characterized in that, It is formed by forming an epitaxial layer on the surface of the silicon wafer for epitaxial growth according to any one of claims 1 to 4. The EP-SF (stacking fault and dislocation) in the epitaxial layer is 0.001 per cm 2 or less.

6. The epitaxial wafer according to claim 5, Characterized in that, The BMD density in the silicon wafer after oxidation heat treatment of the epitaxial wafer at 780 °C for 3 hours + 1000 °C for 16 hours is 1×10 8 / cm 3 Above, for the target BMD density, the target BMD density ≤ 9.6875×10 8 {exp(Ini.Oi[ppma - ASTM’79] - 21.99 - 5.35)} ˆ0.3961.

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