A single crystal silicon wafer and a method for preparing the same
By lifting and growing single crystal silicon rods in a crystal pulling furnace and strictly controlling growth parameters, the problems of insufficient defect density, oxygen content and resistivity uniformity in large-size manufacturing of single crystal silicon wafers are solved, and a single crystal silicon wafer preparation that is more in line with the needs is achieved.
Patent Information
- Application Number
- CN202411852610.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-13
- Publication Date
- 2025-04-04
AI Technical Summary
When the prior art grows single crystal silicon wafers of 200 mm or above, there are problems such as insufficient defect density, oxygen content and resistivity uniformity, which is difficult to meet the market demand for 300 mm manufacturing.
By lifting and growing the single crystal silicon rod in a crystal pulling furnace, the separation distance between the heat screen device and the liquid surface, the strength of the transverse magnetic field, the flow rate and pressure of the inert gas, and the rotation speed of the crucible and the single crystal silicon rod are strictly controlled to control the uniformity of oxygen content, defect density and resistivity.
The goal of having less than 90nm hollow micro defects in single crystal silicon wafers is less than the preset number, gap oxygen content is less than 6 ppma, oxygen concentration gradient is less than 50% and resistivity gradient is less than 10%, meeting the preparation needs of IGBT devices.
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Figure CN119753812A_ABST
Abstract
Description
Technical Field
[0001] The present application relates to the technical field of semiconductor substrates, and in particular to a single crystal silicon wafer and a method for preparing the same. Background Art
[0002] At present, the insulated gate bipolar transistor (IGBT) is a power semiconductor device widely used in power electronic systems. It has the characteristics of high frequency, high voltage, large current and easy switching. It is praised by the industry as the CPU of power converters and is mainly used in electric vehicles, smart grids, rail transportation, renewable energy and other fields. Monocrystalline silicon wafers are one of the most commonly used materials for IGBT products. The current methods for growing silicon wafers for IGBT include the melting zone method (FZ) and the direct pull method (CZ). Due to the limitations of the manufacturing process, the FZ method can only achieve 200mm monocrystalline silicon growth. Therefore, when facing the preparation of monocrystalline silicon wafers with larger diameters, the direct pull method is often used to prepare the wafers.
[0003] In the related technology, wafers produced by the direct-pull method still have deficiencies in the parameters of defect density, oxygen content and resistivity uniformity, making it difficult to meet the market demand for the evolution from 200mm manufacturing to 300mm manufacturing. Summary of the invention
[0004] The present application is proposed to solve the above-mentioned problems. According to one aspect of the present application, a single crystal silicon wafer is provided, wherein the number of void-type micro-defects greater than or equal to 90 nm in the single crystal silicon wafer is less than a preset number, the interstitial oxygen content is less than or equal to 6 ppma, the oxygen concentration gradient is less than 50%, and the resistivity gradient is less than 10%.
[0005] Exemplarily, the number of void-type defects greater than or equal to 37 nm in the single crystal silicon wafer is less than the preset number, where the preset number is 10.
[0006] Exemplarily, the number of void-type micro defects greater than or equal to 15 nm in the single crystal silicon wafer is less than the preset number.
[0007] According to another aspect of the present application, a method for preparing a single crystal silicon wafer is provided, the method comprising: providing a crystal pulling furnace, melting silicon material in a crucible of the crystal pulling furnace, and forming a single crystal silicon rod by continuous straight pulling, wherein a heat shield device is movably provided in the crystal pulling furnace; adjusting the spacing distance between the heat shield device and the silicon material liquid level to control the temperature gradient, wherein the spacing distance is within a preset distance range; applying a transverse magnetic field to the silicon material to control the oxygen content and radial resistivity of the single crystal silicon rod, wherein the magnetic field strength of the transverse magnetic field is within a preset field strength range; introducing an inert gas into the crystal pulling furnace, maintaining the flow rate of the inert gas within a preset flow rate range, and maintaining the pressure of the inert gas within a preset pressure range, so as to control the oxygen content of the single crystal silicon rod; rotating the single crystal silicon rod and the crucible, wherein the rotation speed of the crucible and the rotation speed of the single crystal silicon rod are respectively within a first speed range and a second speed range; after the single crystal silicon rod is formed, the single crystal silicon wafer is obtained by further processing the single crystal silicon rod.
[0008] Exemplarily, the magnetic flux lines of the transverse magnetic field are parallel to the silicon material liquid surface, and the center of the transverse magnetic field is located below the silicon material liquid surface and the distance between the center and the silicon material liquid surface is a preset value.
[0009] Exemplarily, the preset field strength range of the transverse magnetic field is 1000-5000 guass.
[0010] Exemplarily, the preset value is 50mm-150mm.
[0011] Exemplarily, the heat shield device includes a guide tube, and the preset distance range between the guide tube and the silicon material liquid surface is 30-80 mm.
[0012] Exemplarily, the inert gas includes argon gas, and the preset flow rate range of the argon gas flow rate is 50-250 standard liters per minute; the pressure range of the argon gas is 50-150 mTorr.
[0013] Exemplarily, the first speed range of the crucible rotation speed is 0-0.5 rpm / min, and the second speed range of the single crystal silicon rod rotation speed is 0-6 rpm / min.
[0014] Exemplarily, when the single crystal silicon rod is formed by continuous straight pulling, the speed of pulling the single crystal silicon rod is 0.3-1.5 mm / min.
[0015] The single crystal silicon wafer in the present application limits various parameters such as void-type micro-defects, interstitial oxygen content, oxygen concentration gradient, resistivity gradient, etc., so that it can better meet the needs of preparing effective IGBT devices. The preparation method of the single crystal silicon wafer in the present application strictly controls the following parameters during the pulling and growth of the single crystal silicon rod by a crystal pulling furnace: the distance between the heat shield device and the liquid surface, the strength of the transverse magnetic field, the flow rate and pressure of the inert gas, and the rotation speed of the crucible and the single crystal silicon rod. Therefore, in the process of direct pulling growth, single crystal silicon rods and wafers with oxygen content, defect density and resistivity uniformity that better meet the requirements can be obtained. BRIEF DESCRIPTION OF THE DRAWINGS
[0016] By describing the embodiments of the present application in more detail in conjunction with the accompanying drawings, the above and other purposes, features and advantages of the present application will become more apparent. The accompanying drawings are used to provide a further understanding of the embodiments of the present application and constitute a part of the specification. Together with the embodiments of the present application, they are used to explain the present application and do not constitute a limitation of the present application. In the accompanying drawings, the same reference numerals generally represent the same components or steps.
[0017] Figure 1 The schematic diagram of the process of the preparation method in Example 1 is shown.
[0018] Figure 2 A schematic diagram of a crystal pulling furnace for preparing single crystal silicon rods in Example 1 is shown.
[0019] Figure 3 A comparison chart of various parameters of the preparation process in Example 1 and silicon rod parameters is shown.
[0020] Figure 4 The corresponding relationship between the single crystal silicon ingot and the resistivity in the first embodiment is shown.
[0021] Figure 5(a)-Figure 5(b) A schematic diagram of a wafer in the related art and the present application is shown.
[0022] Figure 6 A comparison chart of single crystal silicon wafer parameters and device performance in Example 2 is shown.
[0023] Figure 7(a)-Figure 7(b) A schematic diagram showing the change in oxygen content of a single crystal silicon rod in Example 2 is shown.
[0024] Figure 8(a)-Figure 8(b) A schematic diagram showing the change in resistivity of a single crystal silicon rod in Example 2 is shown. DETAILED DESCRIPTION
[0025] In order to make the purpose, technical solutions and advantages of the present application more obvious, the example embodiments according to the present application will be described in detail with reference to the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments of the present application, and it should be understood that the present application is not limited to the example embodiments described herein. Based on the embodiments of the present application described in the present application, all other embodiments obtained by those skilled in the art without creative work should fall within the scope of protection of the present application.
[0026] Embodiment 1
[0027] like Figure 1 As shown, the embodiment of the present application provides a method for preparing a single crystal silicon wafer, comprising the following steps:
[0028] S110, providing a crystal pulling furnace, melting silicon material in a crucible of the crystal pulling furnace, and forming a single crystal silicon rod by continuous straight pulling, wherein a heat shield device is movably provided in the crystal pulling furnace.
[0029] S120, adjusting the distance between the heat shield device and the silicon material liquid surface to control the temperature gradient, wherein the distance is within a preset distance range.
[0030] S130, applying a transverse magnetic field to the silicon material to control the oxygen content and radial resistivity of the single crystal silicon rod, wherein the magnetic field strength of the transverse magnetic field is within a preset field strength range.
[0031] S140, introducing an inert gas into the crystal pulling furnace, maintaining the flow rate of the inert gas within a preset flow rate range, and maintaining the pressure of the inert gas within a preset pressure range, so as to control the oxygen content of the single crystal silicon rod.
[0032] S150, rotating the single crystal silicon rod and the crucible, wherein the rotation speed of the crucible and the rotation speed of the single crystal silicon rod are respectively within a first speed range and a second speed range.
[0033] S160: After the single crystal silicon rod is formed, the single crystal silicon wafer is obtained by further processing the single crystal silicon rod.
[0034] In the method for preparing single crystal silicon wafers in the embodiment of the present application, during the process of pulling and growing single crystal silicon rods through a crystal pulling furnace, the following parameters are strictly controlled: the spacing distance between the heat shield device and the liquid surface, the strength of the transverse magnetic field, the flow rate and pressure of the inert gas, and the rotation speed of the crucible and the single crystal silicon rod. Therefore, during the direct pulling growth process, single crystal silicon rods and wafers with oxygen content, defect density and resistivity uniformity that better meet the requirements can be obtained.
[0035] like Figure 2As shown, it is a schematic diagram of a crystal pulling furnace for preparing a single crystal silicon rod in an embodiment of the present application. Exemplarily, the crystal pulling furnace can be a quartz crucible, and polycrystalline silicon is placed in the quartz crucible for dissolution to form a molten silicon material. A heat shield device can be movably provided on the quartz crucible, wherein the heat shield device can be a guide tube, and the guide tube can be moved vertically along the quartz crucible, so as to adjust the gap between the bottom of the heat shield device and the liquid surface. When the airflow convects between the guide tube and the liquid surface, the gap between the heat shield device and the liquid surface will also affect the convection speed of the gas and the molten silicon material. The convection speed can be controlled by the gap (melt gap, referred to as MG) between the bottom of the heat shield device and the liquid surface, thereby controlling the oxygen content of the crystal.
[0036] like Figure 2 As shown in the figure, during the growth of the single crystal silicon rod, the quartz crucible and the single crystal silicon rod will rotate, and the convection speed of the molten silicon material will also change during the rotation, thereby controlling the oxygen content. In addition, inert gas will be introduced during the growth of the single crystal silicon rod, and the flow rate and pressure of the inert gas will also change the convection speed of the molten silicon material and thus affect the oxygen content.
[0037] like Figure 3 As shown, it shows the influence of various parameters on the single crystal silicon rod and wafer parameters during the growth of single crystal silicon rod. RRG in the figure represents the radial resistivity gradient of the wafer (single crystal silicon rod), which is used to represent the resistivity uniformity of the wafer (single crystal silicon rod). OI represents the oxygen content of the wafer (single crystal silicon rod). ORG represents the oxygen radial gradient of the wafer (single crystal silicon rod), which is used to represent the oxygen content uniformity of the wafer (single crystal silicon rod).
[0038] Figure 3The direction of the arrow in the figure indicates the increase or decrease of the parameter. When the arrow directions between the two parameters are the same, it indicates that there is a positive correlation between the two. Otherwise, it indicates a negative correlation between the two. The SeedRotation in the figure is the rotation speed of the single crystal silicon rod. The radial resistivity gradient and oxygen content of the single crystal silicon rod are positively correlated with the rotation speed of the single crystal silicon rod, and the oxygen radial gradient is negatively correlated with the rotation speed of the single crystal silicon rod. The Magnetic Position in the figure indicates the position of the transverse magnetic field, specifically the distance between the center of the transverse magnetic field and the liquid surface of the molten silicon material, which is used to indicate the position of the transverse magnetic field. The position of the transverse magnetic field affects the radial resistivity gradient and oxygen content of the single crystal silicon rod. The Melt Gap in the figure indicates the interval between the bottom of the heat shield device (guide tube) and the liquid surface. The size of this interval mainly affects the oxygen content of the single crystal silicon rod. The Magnetic strength in the figure indicates the magnetic field strength of the transverse magnetic field, because the molten silicon material will convect under the action of the transverse magnetic field, and the size of the transverse magnetic field will affect the speed of convection. The radial resistivity gradient and oxygen radial gradient of the single crystal silicon rod are positively correlated with the size of the transverse magnetic field, and the oxygen content is negatively correlated with the size of the transverse magnetic field. Arflow and Pressure represent the flow rate and pressure of the inert gas. The radial resistivity gradient of the single crystal silicon rod is positively correlated with the flow rate and pressure of the inert gas, while the oxygen content and oxygen radial gradient are negatively correlated with them.
[0039] Because in the preparation process of radial single crystal silicon wafers, the above-mentioned multiple parameters will affect the final resistivity uniformity, oxygen content and oxygen radial gradient of the wafer. Therefore, multiple parameters need to be restricted in the preparation process so that the final prepared wafer meets actual needs.
[0040] Exemplarily, when a transverse magnetic field is applied to the silicon material, the magnetic flux lines of the transverse magnetic field are parallel to the silicon material liquid surface, and the center of the transverse magnetic field is located below the silicon material liquid surface and the distance between the silicon material liquid surface is a preset value. Among them, the preset field strength range of the transverse magnetic field is 1000-5000 guass (gauss), and in some embodiments, the magnetic field strength of the transverse magnetic field is preferably 1500-4000 guass. The preset value of the distance between the center of the transverse magnetic field and the silicon material liquid surface is 50mm-150mm, preferably 80mm-100mm, and in some embodiments, the distance between the center of the transverse magnetic field and the silicon material liquid surface is 90mm. Because the center position of the transverse magnetic field and the magnetic field strength of the transverse magnetic field will affect the radial resistivity gradient, oxygen content and oxygen radial gradient after the single crystal silicon rod is formed, the center position of the transverse magnetic field and the magnetic field strength of the transverse magnetic field will be limited during the preparation process.
[0041] Exemplarily, the heat shield device is a guide tube movably installed on the crystal pulling furnace. By moving to the position of the guide tube, the gap (MG) between the guide tube and the silicon material liquid surface can be changed, and the oxygen content of the single crystal silicon rod finally formed can be changed by changing the size of MG. Among them, the preset distance range between the guide tube and the silicon material liquid surface is 30-80mm, preferably 50-60mm. In addition, the size of the MG of the heat shield device will also affect the temperature gradient and free liquid surface oxygen volatilization, and the temperature gradient in the single crystal silicon rod preparation process will also affect the crystal defects of the single crystal silicon rod. By controlling the size of MG, a single crystal silicon rod with fewer defects can be obtained.
[0042] The inert gas in the embodiment of the present application adopts argon. In some embodiments, the specific type of inert gas can also be selected according to actual conditions. Among them, the preset flow rate range of the pressure flow rate is 50-250slm (standard liters per minute). The pressure range of argon is 50-150torr. When argon passes above the silicon material liquid surface, the flow of the inert gas will drive the silicon material to convect. By controlling the pressure and flow rate of argon, the convection process of the silicon material can be better controlled, thereby controlling the radial resistivity gradient, oxygen content and oxygen radial gradient of the single crystal silicon rod finally formed.
[0043] Exemplarily, the crucible and the single crystal silicon rod in the present application rotate in opposite directions respectively, the rotation speed of the crucible is within a first speed range, and the rotation speed of the single crystal silicon rod is within a second speed range. The first speed range is 0-0.5rpm / min, preferably 0-0.3rpm / min, and more preferably 0-0.1rpm / min. The first speed range corresponding to the single crystal silicon rod is less than or equal to 6rpm / min, preferably less than or equal to 3rpm / min, more preferably less than or equal to 2rpm / min, and most preferably less than or equal to 1rpm / min. Because the relative flow between the single crystal silicon rod and the crucible can control the convection of the silicon material, it is possible to control the radial uniformity of oxygen and resistivity of the generated single crystal silicon rod.
[0044] Exemplarily, when a single crystal silicon rod is formed by continuous straight pulling, the speed of pulling the single crystal silicon rod is 0.3-0.8 mm / min. Preferably, the speed of pulling the single crystal silicon rod is 0.3-0.5 mm / min.
[0045] like Figure 4As shown, it is the corresponding relationship between the single crystal silicon rod and the resistivity in the embodiment of the present application. Exemplarily, the polycrystalline silicon material in the present application is doped with N-type dopants, specifically including P, As, etc., and the available resistivity of the single crystal silicon rod can be increased by adding N-type dopants. The available range of resistivity should be between the target lower limit of resistivity and the target upper limit of resistivity. By doping with N-type dopants, the available range of resistivity can be effectively improved, so that when preparing larger crystal rods, the resistivity requirements can also be met. In some embodiments, the available resistivity of the single crystal silicon rod can also be increased by doping with P-type dopants (such as boron, etc.), which can be selected according to actual conditions and is not limited in the embodiments of the present application.
[0046] After the above-mentioned single crystal silicon rod is obtained by the Czochralski method, the above-mentioned single crystal silicon rod is subjected to rolling, segmenting, slicing, chamfering, grinding, polishing and other mid- and late-stage processes to obtain a single crystal silicon wafer that meets the requirements.
[0047] In the method for preparing single crystal silicon wafers in the embodiment of the present application, during the process of pulling and growing single crystal silicon rods through a crystal pulling furnace, the following parameters are strictly controlled: the spacing distance between the heat shield device and the liquid surface, the strength of the transverse magnetic field, the flow rate and pressure of the inert gas, and the rotation speed of the crucible and the single crystal silicon rod. Therefore, during the direct pulling growth process, single crystal silicon rods and wafers with oxygen content, defect density and resistivity uniformity that better meet the requirements can be obtained.
[0048] Embodiment 2
[0049] The embodiment of the present application provides a single crystal silicon wafer, which is prepared by the above method, wherein the number of void-type micro defects greater than or equal to 90 nm in the single crystal silicon wafer is less than a preset number, the interstitial oxygen content is less than or equal to 6 ppma, the oxygen concentration gradient is less than 50%, and the resistivity gradient is less than 10%. The diameter of the single crystal silicon wafer is 300 mm, and it is used to prepare IGBT devices.
[0050] Since void-type micro-defects (COPs) in silicon wafers can damage the gate oxide layer of devices, limiting the COPs in single-crystal silicon wafers to a preset number can effectively improve their performance; illustratively, the preset number in the embodiment of the present application is 10, that is, there are less than 10 void-type micro-defects (COPs) greater than or equal to 90nm in single-crystal silicon wafers. Furthermore, there are less than 10 COPs greater than or equal to 65nm in single-crystal silicon wafers, preferably less than 10 COPs greater than or equal to 37nm, and optimally less than 10 COPs greater than or equal to 15nm.
[0051] Among them, the void type micro defect uses the equivalent size of the defect (latex sphere equivalent, referred to as LSE size) provided by the surface light scattering instrument. The wafer defect range is the Pv area, and the number of Pv defects (the number detected by the surface scattering instrument) is less than 10,000.
[0052] For example, the interstitial oxygen elements in the monocrystalline silicon wafer will form thermal donors due to the donor effect to reduce the resistivity of the wafer, so it is necessary to control the interstitial oxygen content, wherein the interstitial oxygen content of the wafer is preferably less than 4ppma, more preferably less than 3ppma. The oxygen concentration gradient (ORG) of the wafer is preferably less than 30%, more preferably less than 10%. The radial resistivity gradient (RRG) of the wafer is preferably less than 6%, more preferably RRG is less than 3%. To ensure the yield of device preparation in the wafer.
[0053] As shown in Figures 5(a) and 5(b), they are the defect distribution diagrams of single crystal silicon wafers obtained in the methods of the related art and the embodiments of the present application, respectively. A surface light scatterer is used to characterize the type and quantity of crystal defects in silicon. Among them, when confirming the internal defects of the silicon wafer, the surface light scatterer is used to detect (wafer defects greater than or equal to 37nm can be detected). It can be seen from the figure that compared with the preparation method in the related art, the present application can effectively reduce the defects of the wafer.
[0054] The present application adopts the above method to prepare the single crystal silicon wafer in the embodiment of the present application, and makes the single crystal silicon wafer meet the above parameter range, so as to make the single crystal silicon wafer better applicable to IGBT devices. Figure 6 As shown, it is a comparison chart of wafer parameters and formed device performance. It can be seen from the figure that when the oxygen content (Oi) of the wafer is less than or equal to 6ppma, the oxygen concentration gradient (ORG) is less than 50%, the radial resistivity gradient (RRG) is less than 10%, and there are less than 10 COPs greater than or equal to 90nm in the wafer, the IGBT device is effective, otherwise it fails. Therefore, in order to meet the needs of preparing effective IGBT devices, it is necessary to control the various parameters of the single crystal silicon wafer. Through the above-mentioned single crystal silicon wafer preparation method, the obtained wafer parameters can be controlled within a reasonable range.
[0055] As shown in Figure 7(a) and Figure 7(b), they are the oxygen content distribution in the axial direction of the crystal rod and the oxygen content distribution in the radial direction of the wafer, respectively. By way of example, the oxygen content of the crystal rod is measured by the diffusion resistance distribution method (SBS), and the oxygen concentration in the gap of the silicon wafer is detected by the Fourier transform infrared spectrometer (FTIR). The percentage of the crystal rod length can represent the position of the currently detected area in the axial direction of the crystal rod. It can be seen from the figure that the oxygen content in the silicon wafer reaches the maximum in the central area of the silicon wafer and the minimum at the edge. And the oxygen content in the gaps of each region of the entire wafer is less than 5ppma, and the radial gradient of the oxygen concentration is less than 50% (its variation along the gap is less than 50%).
[0056] As shown in Figure 8(a) and Figure 8(b), it is a schematic diagram of the change of resistivity in the axial and radial directions of the crystal rod. First, referring to Figure 8(a), the figure shows the change of radial resistivity gradient (RRG) with the percentage of crystal rod length, where RRG = (ρ max -ρ min ) / ρ min , where ρ max is the maximum resistivity on the wafer, ρ min is the maximum resistivity on the wafer. It can be seen from the figure that at different length positions of the crystal rod, the radial resistivity gradient is always maintained within a small range (less than 6%). As shown in Figure 8(b), the change of resistivity percentage in the radial direction of the wafer is shown, where resistivity percentage = (ρ i -ρ min ) / ρ min *100%, where ρ i is the resistivity of position i on the wafer, ρ max is the maximum resistivity on the wafer, ρ min is the maximum resistivity on the wafer. It can be seen from the figure that at different radial positions of the wafer, the resistivity percentage is always maintained in a low range.
[0057] In summary, the wafer in the embodiment of the present application is prepared by the above-mentioned single crystal silicon wafer preparation method. During the pulling and growth process of the single crystal silicon rod by the crystal pulling furnace, the following parameters are strictly controlled: the spacing distance between the heat shield device and the liquid surface, the strength of the transverse magnetic field, the flow rate and pressure of the inert gas, the rotation speed of the crucible and the single crystal silicon rod. Therefore, the wafer finally obtained is more in line with the requirements of IGBT device preparation in terms of parameters such as oxygen content, defect density and resistivity uniformity.
[0058] Although example embodiments have been described herein with reference to the accompanying drawings, it should be understood that the above example embodiments are merely exemplary and are not intended to limit the scope of the present application to this. Those of ordinary skill in the art may make various changes and modifications therein without departing from the scope and spirit of the present application. All these changes and modifications are intended to be included within the scope of the present application as required by the appended claims.
[0059] In the description provided herein, a large number of specific details are described. However, it is understood that the embodiments of the present application can be practiced without these specific details. In some instances, well-known methods, structures and techniques are not shown in detail so as not to obscure the understanding of this description.
[0060] Similarly, it should be understood that in order to streamline the present application and help understand one or more of the various inventive aspects, in the description of the exemplary embodiments of the present application, the various features of the present application are sometimes grouped together into a single embodiment, figure, or description thereof. However, the method of the present application should not be interpreted as reflecting the following intention: the claimed application requires more features than the features clearly stated in each claim. More specifically, as reflected in the corresponding claims, the inventive point is that the corresponding technical problem can be solved with features less than all the features of a single disclosed embodiment. Therefore, the claims following the specific embodiment are hereby explicitly incorporated into the specific embodiment, wherein each claim itself serves as a separate embodiment of the present application.
[0061] It will be understood by those skilled in the art that, except for mutually exclusive features, all features disclosed in this specification (including the accompanying claims, abstracts and drawings) and all processes or units of any method or device disclosed in this specification may be combined in any combination. Unless otherwise expressly stated, each feature disclosed in this specification (including the accompanying claims, abstracts and drawings) may be replaced by an alternative feature that provides the same, equivalent or similar purpose.
[0062] In addition, those skilled in the art will appreciate that, although some embodiments herein include certain features included in other embodiments but not other features, the combination of features of different embodiments is meant to be within the scope of the present application and form different embodiments. For example, in the claims, any one of the claimed embodiments may be used in any combination.
[0063] The above is only a specific implementation or description of a specific implementation of the present application, and the protection scope of the present application is not limited thereto. Any technician familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed in the present application, which should be included in the protection scope of the present application. The protection scope of the present application shall be based on the protection scope of the claims.
Claims
1. A single crystal silicon wafer, characterized in that: The number of void-type micro defects greater than or equal to 90 nm in the single crystal silicon wafer is less than a preset number, the interstitial oxygen content is less than or equal to 6 ppma, the oxygen concentration gradient is less than 50%, and the resistivity gradient is less than 10%.
2. The single crystal silicon wafer according to claim 1, characterized in that: The number of void defects greater than or equal to 37 nm in the single crystal silicon wafer is less than the preset number, where the preset number is 10.
3. The single crystal silicon wafer according to claim 2, characterized in that: The number of void-type micro defects greater than or equal to 15 nm in the single crystal silicon wafer is less than the preset number.
4. A method for preparing a single crystal silicon wafer, for preparing the single crystal silicon wafer according to any one of claims 1 to 3, characterized in that: The method comprises: A crystal pulling furnace is provided, in which silicon materials are melted in a crucible of the crystal pulling furnace, and single crystal silicon rods are formed by continuous straight pulling, wherein a heat shield device is movably provided in the crystal pulling furnace; The temperature gradient is controlled by adjusting the distance between the heat shield device and the silicon material liquid surface, wherein the distance is within a preset distance range; Applying a transverse magnetic field to the silicon material to control the oxygen content and radial resistivity of the single crystal silicon rod, wherein the magnetic field strength of the transverse magnetic field is within a preset field strength range; Introducing an inert gas into the crystal pulling furnace, maintaining the flow rate of the inert gas within a preset flow rate range, and maintaining the pressure of the inert gas within a preset pressure range, so as to control the oxygen content of the single crystal silicon rod; Rotating the single crystal silicon rod and the crucible, wherein the rotation speed of the crucible and the rotation speed of the single crystal silicon rod are respectively within a first speed range and a second speed range; After the single crystal silicon rod is formed, the single crystal silicon wafer is obtained by further processing the single crystal silicon rod.
5. The method according to claim 4, characterized in that The magnetic flux lines of the transverse magnetic field are parallel to the silicon material liquid surface, and the center of the transverse magnetic field is located below the silicon material liquid surface and the distance between the center and the silicon material liquid surface is a preset value.
6. The method according to claim 5, characterized in that The preset field strength range of the transverse magnetic field is 1000-5000 guass.
7. The method according to claim 5, characterized in that The size of the preset value is 50mm-150mm.
8. The method according to claim 4, characterized in that The heat shield device comprises a guide tube, and the preset distance range between the guide tube and the silicon material liquid surface is 30-80 mm.
9. The method according to claim 4, characterized in that The inert gas includes argon gas, and the preset flow rate range of the argon gas flow rate is 50-250 standard liters per minute; the pressure range of the argon gas is 50-150 mTorr.
10. The method according to claim 4, characterized in that The first speed range of the crucible rotation speed is 0-0.5 rpm / min, and the second speed range of the single crystal silicon rod rotation speed is 0-6 rpm / min.
11. The method according to claim 4, characterized in that When the single crystal silicon rod is formed by continuous straight pulling, the speed of pulling the single crystal silicon rod is 0.3-1.5 mm / min.