METHOD FOR GROWING NITROGEN-DOPED SINGLE CRYSTAL SILICON INGOT USING THE CONTINUOUS CZOCHRALSKI METHOD AND SINGLE CRYSTAL SILICON INGOT GROWN BY THIS METHOD - Patent application

Abstract

A method for growing single crystal silicon ingots by the continuous Czochralski method is disclosed. Melt depth and thermal conditions are constant during growth, and the crucible position is fixed, due to the silicon melt being continuously replenished as it is consumed. The critical v / G is determined by the hot zone configuration, and continuous replenishment of silicon to the melt during growth allows for growth of the ingot at a constant pull rate consistent with the critical v / G during growth of a substantial portion of the ingot's body. Continuous replenishment of silicon is achieved by periodic or continuous nitrogen addition, resulting in a nitrogen-doped ingot.

Description

[Technical Field]

[0001] (CROSS-REFERENCE TO RELATED APPLICATIONS) This application claims priority to U.S. Provisional Application Nos. 16 / 569,949 and 16 / 570,010, both filed September 13, 2019, the entire disclosures of which are incorporated herein by reference in their entirety.

[0002] FIELD OF THE DISCLOSURE The field of the disclosure relates to a method for growing a crystalline silicon ingot using a continuous Czochralski process and to a single crystal silicon ingot grown by this method. [Background technology]

[0003] (background) Single-crystal silicon, the starting material for most processes in the fabrication of semiconductor electronic components, is commonly produced by the Czochralski ("Cz") process. In this process, polycrystalline silicon ("polysilicon") is introduced into a crucible and melted. A seed crystal is brought into contact with the molten silicon, and the single crystal is grown by slow extraction. After neck formation is complete, the crystal diameter is expanded, for example, by decreasing the pulling rate and / or melt temperature until the desired or target diameter is reached. The cylindrical body of the crystal, having an approximately constant diameter, is then grown by controlling the pulling rate and melt temperature while compensating for the decrease in melt level. Near the end of the growth process, but before the crucible is emptied of molten silicon, the crystal diameter is typically gradually reduced to form a tail end in the form of an end-cone. The end-cone is usually formed by increasing the crystal pulling rate and the amount of heat supplied to the crucible. The crystals are then separated from the melt when their diameter is small enough.

[0004] Czochralski growth techniques include batch Czochralski and continuous Czochralski. In batch Czochralski, a single polycrystalline charge is loaded into a crucible; the single charge should be sufficient to grow a single crystalline silicon ingot, after which the crucible is substantially depleted of silicon melt. In continuous Czochralski (CCZ) growth, polycrystalline silicon is continuously or periodically added to the molten silicon to replenish the melt during the growth process; thus, multiple ingots can be pulled from a single crucible during the growth process.

[0005] To implement the CCZ process, conventional batch Czochralski growth chambers and equipment are modified to include a means for supplying additional polycrystalline silicon to the melt in a continuous or semi-continuous manner without adversely affecting the properties of the growing ingot. As seed crystals are continuously grown from the melt, solid polycrystalline silicon, such as granular polycrystalline silicon, is added to the melt to replenish the melt. The rate at which the additional solid polycrystalline silicon is added to the melt is typically controlled to maintain process parameters. To reduce the adverse effects of this replenishment activity on the concurrent crystal growth, conventional quartz crucibles are often modified to provide an outer, or annular, melting zone, into which additional material is delivered, in addition to the inner growth zone from which the silicon ingot is pulled. These zones are in fluid communication with each other.

[0006] The continuously shrinking size of modern microelectronic devices imposes challenging restrictions on the quality of silicon substrates, which is substantially determined by the size and distribution of grown-in microdefects. Most microdefects formed in silicon crystals grown by the Czochralski (CZ) and Float Zone (FZ) processes are agglomerates of intrinsic point defects: silicon vacancies and self-interstitials (or simply interstitials).

[0007] A series of studies established that interstitial aggregates exist in two forms: spherical interstitial clusters, named B-swirl defects (or B defects), and dislocation loops, named A-swirl defects (or A defects). Later, the later-discovered vacancy agglomerates, known as D defects, were identified as octahedral spaces (or voids). Voronkov provided a widely accepted explanation for the microdefect distribution observed in silicon crystals based on the crystal growth conditions. According to Voronkov's model or theory, the temperature field near the melt / crystal interface drives the recombination of point defects and provides the driving force for their diffusion from the melt / crystal interface (where point defects exist at their respective equilibrium concentrations) into the crystal bulk. The interplay between point defect transport by both diffusion and convection and their recombination establishes a point defect concentration over a short distance from the interface, named the recombination length. Typically, the difference between the vacancy and interstitial concentrations beyond the recombination length, termed the excess point defect concentration, remains substantially constant away from the sides of the crystal. In rapidly pulled crystals, spatial redistribution of point defects due to their diffusion beyond the recombination length is generally insignificant—with the exception of regions near the sides of the crystal, which act as sinks or sources of point defects. Thus, if the excess point defect concentration beyond the recombination length is positive, vacancies remain in excess and agglomerate to form D defects at lower temperatures. If the excess point defect concentration is negative, interstitials remain the predominant point defect and agglomerate to form A and B defects. If the excess point defect concentration is below some detection threshold, no detectable microdefects are formed. Thus, typically, the type of grown microdefect is simply determined by the excess point defect concentration established beyond the recombination length. The process of establishing excess point defect concentration is termed initial incorporation, and the predominant point defect species is termed incorporated predominant point defect.The type of incorporated point defect is determined by the ratio of the crystal pull rate (v) to the magnitude of the axial temperature gradient (G) near the interface. At higher v / G, the vacancy concentration at the interface is higher than the interstitial concentration, so point defect convection dominates their diffusion, and vacancies remain the dominant incorporated point defect. At lower v / G, diffusion dominates convection, allowing fast-diffusing interstitials to become incorporated as dominant point defects. At v / G near its critical value, both types of point defects are incorporated at very low and comparable concentrations, mutually annihilating each other, thus suppressing the potential formation of any microdefects at lower temperatures. The observed spatial microdefect distribution can typically be explained by the radial nonuniformity of G and the change in v / G caused by the axial change in v. A striking feature of the radial microdefect distribution are oxide particles, which form through oxygen interaction with vacancies in a small range of v / G slightly above the critical v / G in regions of relatively lower incorporated vacancy concentration. These particles form narrow spatial bands that can be revealed by thermal oxidation as OSF (oxidation-induced stacking fault) rings. Quite often, OSF rings mark the boundaries between adjacent vacancy- and interstitial-dominated crystalline regions, known as V / I boundaries.

[0008] However, the microdefect distribution in CZ crystals grown at slower rates in many modern processes is influenced by the diffusion of point defects in the crystal bulk, including diffusion induced by the crystal's lateral surfaces. Therefore, accurate quantification of microdefect distribution in CZ crystals preferably incorporates two-dimensional point defect diffusion in both the axial and radial directions. Quantifying only the point defect concentration field can qualitatively capture the microdefect distribution in CZ crystals, since the type of microdefect formed is thereby directly determined. However, for more accurate quantification of microdefect distribution, it is necessary to capture point defect agglomeration. Traditionally, microdefect distribution is quantified by separating the initial incorporation of point defects and the subsequent formation of microdefects. This approach ignores the diffusion of dominant point defects near the nucleation region from higher temperature regions (where microdefect density is negligible) to lower temperature regions (where microdefects are present in higher densities and consume point defects). Alternatively, accurate numerical simulations based on prediction of the size distribution of the microdefect population at each location in the crystal are numerically expensive.

[0009] The transition between vacancy and interstitial dominated material occurs at a critical value of v / G, which is currently about 2.5×10 -5 cm 2 / sK. If the value of v / G exceeds a critical value, vacancies are the predominant intrinsic point defect, and the concentration of vacancies increases with increasing v / G. If the value of v / G is below the critical value, silicon self-interstitials are the predominant intrinsic point defect, and their concentration increases with decreasing v / G. Therefore, process conditions such as growth rate (which affects v) and hot zone configuration (which affects G) can be controlled to determine whether the intrinsic point defects in single crystal silicon will be predominantly vacancies (v / G is generally greater than the critical value) or self-interstitials (v / G is generally less than the critical value).

[0010] Generally, agglomerated defect formation occurs in two steps. First, defects called "nucleation" occur, which are the result of intrinsic point defects being supersaturated at a given temperature; above this "nucleation threshold" temperature, the intrinsic point defects remain soluble in the silicon lattice. The nucleation temperature for agglomerated intrinsic point defects is greater than about 1000°C.

[0011] Once this "nucleation threshold" temperature is reached, the intrinsic point defects agglomerate; i.e., precipitation of these point defects from the "solid solution" of the silicon lattice occurs. The intrinsic point defects will continue to diffuse through the silicon lattice as long as the temperature of the portion of the ingot in which they reside is maintained above a second threshold temperature (i.e., the "diffusion threshold"). Below this "diffusion threshold" temperature, the intrinsic point defects are no longer mobile within a commercially practical timeframe.

[0012] As long as the ingot remains above the "diffusion threshold" temperature, native point defects, either vacancies or interstitials, diffuse through the silicon lattice to existing sites of agglomerated vacancies or interstitials, respectively, causing a given agglomerated defect to increase in size. Growth occurs as these agglomerated defect sites essentially act as "sinks," attracting and collecting native point defects due to their more favorable energy state for agglomeration.

[0013] Vacancy-type defects are recognized as the origin of such crystalline defects observable as D defects, flow pattern defects (FPDs), gate oxide integrity (GOI) defects, and crystal-origin particle (COP) defects, as well as a class of bulk defects observed by infrared light scattering techniques such as scanning infrared microscopy and laser scanning tomography. Also present in regions of excess vacancies are clusters of oxygen or silicon dioxide. Some of these clusters are small, remain relatively strain-free, and pose virtually no harm to the majority of devices prepared from such silicon. Some of these clusters are large enough to act as nuclei for ring oxidation-induced stacking faults (OISFs). This particular defect is speculated to be promoted by previously nucleated oxygen aggregates catalyzed by the presence of excess vacancies. Oxide clusters form primarily during CZ growth below 1000°C in the presence of moderate vacancy concentrations.

[0014] Self-interstitial related defects have been less studied. They are generally considered to be low densities of interstitial-type dislocation loops or networks. While such defects are not the cause of gate oxide integrity failure, which is a critical wafer performance criterion, they are widely recognized as the cause of other types of device failures, typically related to leakage current problems.

[0015] In this regard, it should be noted that, generally speaking, oxygen in the interstitial form in the silicon lattice is typically considered to be a point defect in silicon rather than an intrinsic point defect, while silicon lattice vacancies and silicon self-interstitials (or simply interstitials) are typically considered to be intrinsic point defects. Thus, substantially all microdefects can be generally considered to be agglomerated point defects, while D defects (or voids), as well as A and B defects (i.e., interstitial defects), can be more specifically considered to be agglomerated intrinsic point defects. Oxygen clusters are formed by the absorption of vacancies; thus, oxygen clusters can be considered to be aggregates of both vacancies and oxygen.

[0016] Furthermore, the density of such vacancies and self-interstitial agglomerated point defects in Czochralski silicon has historically been about 1×10 3 / cm 3 ~Approx. 1×10 7 / cm 3 , while the density of oxygen clusters is approximately 1×10 8 / cm 3 ~1×10 10 / cm 3 It should be noted that agglomerated intrinsic point defects are therefore of rapidly increasing importance to device manufacturers because such defects can significantly impact the yield potential of single crystal silicon materials in the production of complex, advanced integrated circuits.

[0017] In light of the above, in many applications, it is preferable that some or all of the silicon crystals that are subsequently sliced ​​into silicon wafers be substantially free of these agglomerated intrinsic point defects. To date, several approaches for growing substantially defect-free silicon crystals have been reported. Generally speaking, all of these approaches involve controlling the v / G ratio to determine the initial type and concentration of intrinsic point defects present in the growing CZ single crystal silicon crystal. However, such approaches may additionally involve controlling the crystal's subsequent thermal history to allow extended diffusion times to suppress the concentration of intrinsic point defects therein, thus limiting or avoiding the formation of agglomerated intrinsic point defects in some or all of the crystal. (See, e.g., U.S. Patent Nos. 5,111,159; 5,111,159; 5,111,159; and 5,111,159; the entire contents of which are incorporated herein by reference.) Alternatively, however, such approaches may involve a rapidly cooled silicon (RCS) growth process, in which the crystal's subsequent thermal history is then controlled to rapidly cool at least a portion of the crystal through a target nucleation temperature to control the formation of agglomerated intrinsic point defects in that portion. Alternatively, one or both of these approaches may allow at least a portion of the grown crystal to be maintained above the nucleation temperature for an extended period of time, reducing the concentration of intrinsic point defects prior to rapidly cooling this portion of the crystal through the target nucleation temperature, thus substantially limiting or avoiding the formation of agglomerated intrinsic point defects therein. (See, e.g., U.S. Patent No. 6,223,629, the entire disclosure of which is incorporated herein by reference.) Still further, methods have been developed to reduce or eliminate agglomeration of point defects from the center to the edge of the ingot by simultaneous control of the cooling rate of the solidified ingot and the radial variation of the axial temperature gradient near the interface (G). (See, e.g., U.S. Patent No. 6,223,629, the entire disclosure of which is incorporated herein by reference.)

[0018] Polished silicon wafers that meet manufacturers' requirements for the absence of agglomerated point defects, such as crystal-origin pits (COPs), can be referred to as neutral silicon or perfect silicon. Perfect silicon wafers are preferred for many semiconductor applications, for example, as a low-cost polished alternative to wafers with higher epitaxial deposition. Over the past two decades, numerous silicon wafer suppliers have developed defect-free and COP-free wafer products in both 200 mm and 300 mm diameters, primarily for sale to the memory (DRAM / NAND / FLASH) market, which has traditionally been more sensitive to cost pressures within the market. As customer application device nodes have shrunk, industry standards for acceptable defectivity have evolved over this timeframe in terms of acceptable levels of light point scatter (LLS) and gate oxide integrity (GOI). For example, industry COP-free specifications could once be less than a few hundred at sizes below 0.12 μm. More current standards require a COP of less than 20 at sizes 0.026 μm and below to qualify as full silicon. As another example, the previous standard for GOI in MOS transistors was 95% at ≤8 MV (B-mode). Currently, the specification is moving to 99% at 10-12 MV (D-mode). On top of this requirement, the need for improved radial oxygen precipitation across the wafer, traditionally measured by BMD density (bulk microdefects) and BMD size distribution, is required as device nodes shrink to avoid substrate slip during processing or warp, which can impact patterned overlays during device lithography. As these specifications (LLS, GOI, BMD uniformity, etc.) have tightened, the control window for defect- and COP-free silicon growth has shrunk significantly, significantly reducing the crystal throughput of the process. This is because the allowable band structure (which directly translates to the process window of operation) has changed over time.

[0019] This section is intended to inform the reader of various aspects of art that may be related to various aspects of the disclosure, which are described and / or claimed below. This discussion is believed to be helpful in providing the reader with background information to facilitate a better understanding of the various aspects of the disclosure. As such, these statements should not be read as admissions of prior art in this light. [Prior art documents] [Patent documents]

[0020] [Patent Document 1] U.S. Patent No. 6,287,380 [Patent Document 2] U.S. Patent No. 6,254,672 [Patent Document 3] U.S. Patent No. 5,919,302 [Patent Document 4] U.S. Patent No. 6,312,516 [Patent Document 5] U.S. Patent No. 6,328,795 [Patent Document 6] U.S. Patent Application Publication No. 2003 / 0196587 [Patent Document 7] U.S. Patent No. 8,673,248 Summary of the Invention [Means for solving the problem]

[0021] (summary) One embodiment of the present disclosure is directed to a method for producing a single crystal silicon ingot by a continuous Czochralski process, the method including: adding an initial charge of polycrystalline silicon to a crucible, the initial charge further comprising a nitrogen source; heating the crucible containing the initial charge of polycrystalline silicon and the nitrogen source to form a silicon melt in the crucible, wherein the silicon melt comprises an initial volume of molten silicon and has an initial melt elevation level; contacting a silicon seed crystal with the silicon melt; withdrawing the silicon seed crystal to grow a neck, wherein the silicon seed crystal is withdrawn at a neck pull rate during the growth of the neck, and further wherein the neck is formed at a rate of at least about 1×10 13 atoms / cm 3 pulling the silicon seed crystal to grow an outwardly flaring seed-cone adjacent the neck, wherein the silicon seed crystal is pulled at a seed-cone pull rate during growth of the outwardly flaring seed-cone, and further wherein the outwardly flaring seed-cone has a neck nitrogen concentration of at least about 1×10 13 atoms / cm 3 and pulling the silicon seed crystal to grow a main body of the single crystal silicon ingot adjacent to the outwardly extending seed cone, wherein the silicon melt includes a volume of molten silicon and a melt height level during growth of the single crystal silicon ingot body, and further wherein the single crystal silicon body has a nitrogen concentration of at least about 1×10 13 atoms / cm 3wherein the single crystal silicon ingot body is grown at an initial variable body pull rate and a constant body pull rate, and the single crystal silicon ingot body is grown at the initial variable body pull rate for less than about 20% of the single crystal silicon ingot body length and at the constant body pull rate for growth of at least about 30% of the single crystal silicon ingot body length; and further comprising continuously or periodically supplying polycrystalline silicon to a crucible, thereby replenishing a volume of molten silicon in the crucible during growth of the single crystal silicon ingot body, thereby maintaining a melt height level, and continuously or periodically supplying a nitrogen source to the crucible, thereby replenishing the amount of nitrogen.

[0022] In another aspect, the present disclosure is directed to a monocrystalline silicon ingot having a body portion, wherein the body portion has a peripheral edge, a central axis having an axial length parallel to the peripheral edge, and a radius extending from the central axis to the peripheral edge, wherein wafers sliced ​​from any portion of the body spanning at least 60% of the monocrystalline silicon ingot's body axial length, spanning at least 70% of the monocrystalline silicon ingot's body axial length, or spanning at least 80% of the monocrystalline silicon ingot's body axial length are characterized by non-detectable FPD (flow pattern defects by Secco etching technique) and DSOD (direct surface oxide defect particle count after electrical breakdown), and zero I defects (A defects) by Secco etching technique.

[0023] In another aspect, the present disclosure is directed to a single crystal silicon ingot having a body portion, wherein the body portion has a peripheral edge, a central axis having an axial length parallel to the peripheral edge, and a radius extending from the central axis to the peripheral edge, and the body portion comprises interstitial oxygen at a body oxygen concentration that varies by no more than 20% above and no less than 20% below an average body oxygen concentration across at least 40% of the body axis length of the single crystal silicon ingot, across at least 50% of the body axis length of the single crystal silicon ingot, across at least 60% of the body axis length of the single crystal silicon ingot, across at least 70% of the body axis length of the single crystal silicon ingot, or across at least 80% of the body axis length of the single crystal silicon ingot.

[0024] In another aspect, the present disclosure is directed to a single crystal silicon ingot having a body portion, wherein the body portion has a peripheral edge, a central axis having an axial length parallel to the peripheral edge, and a radius extending from the central axis to the peripheral edge, and the body portion comprises nitrogen at a body nitrogen concentration that varies no more than 20% above and more than 20% below an average body nitrogen concentration along at least 40% of the body axial length of the single crystal silicon ingot, along at least 50% of the body axial length of the single crystal silicon ingot, along at least 60% of the body axial length of the single crystal silicon ingot, along at least 70% of the body axial length of the single crystal silicon ingot, or along at least 80% of the body axial length of the single crystal silicon ingot.

[0025] In another aspect, the present disclosure is directed to a single crystal silicon ingot having a body portion, wherein the body portion has a peripheral edge, a central axis having an axial length parallel to the peripheral edge, and a radius extending from the central axis to the peripheral edge, wherein the body portion has a resistivity that varies no more than 20% above and more than 20% below an average body resistivity (or resistivity, or resistivity) over at least 40% of the body axial length of the single crystal silicon ingot, over at least 50% of the body axial length of the single crystal silicon ingot, over at least 60% of the body axial length of the single crystal silicon ingot, over at least 70% of the body axial length of the single crystal silicon ingot, or over at least 80% of the body axial length of the single crystal silicon ingot.

[0026] Various refinements exist for the features noted in connection with the above embodiments of the present disclosure. Additionally, additional features may be incorporated into the above embodiments of the present disclosure as well. These refinements and additional features may exist individually or in any combination. For example, the various features discussed below in connection with any of the illustrated embodiments of the present disclosure may be incorporated, alone or in any combination, into any of the above embodiments of the present disclosure. [Brief explanation of the drawings]

[0027] [Figure 1] Figures 1A (early body growth), 1B (mid-body growth), and 1C (late body growth) show the melt volume or depth and crucible position as a function of crystal length during a typical batch Czochralski process. [Figure 2A] FIG. 2A is a graph showing the constant variation in pull rate required to achieve adequate defectivity control in ingots grown by a typical batch Cz process. [Figure 2B] FIG. 2B is a graph showing the variation of nitrogen dopant concentration due to the segregation coefficient effect in ingots grown by a typical batch Cz process. [Figure 3]FIG. 3 is a graph showing the pull rate profile required to achieve sufficient defectivity control in ingots grown by a typical batch Cz process that includes the application of a magnetic field. [Figure 4A] FIG. 4A is a graph showing the pull rate profile required to achieve adequate defectivity control in an ingot grown by a typical continuous Cz process according to the method of the present disclosure. [Figure 4B] FIG. 4B is a graph comparing nitrogen dopant concentrations between ingots grown by a typical batch Cz process and ingots grown by a typical continuous Cz process according to the method of the present disclosure. [Figure 5] FIG. 5 shows a typical crucible configuration suitable for a typical continuous Cz process according to the method of the present disclosure. [Figure 6] 6A, 6B and 6C show the melt level and ingot growth of a typical continuous Cz process according to the method of the present disclosure. [Figure 7] FIG. 7 is a graph illustrating a nitrogen source addition protocol to the melt for growing a typical continuous Cz process grown ingot according to the method of the present disclosure. [Figure 8] 8A and 8B show a magnetic field applied to a silicon melt during growth of an ingot by a typical continuous Cz process according to the method of the present disclosure.

[0028] Corresponding reference characters indicate corresponding parts throughout the drawings. DETAILED DESCRIPTION OF THE INVENTION

[0029] (Detailed explanation) In the context of this disclosure, "perfect silicon" refers to a Czochralski-grown single crystal silicon ingot or a single crystal silicon wafer sliced ​​from a Czochralski-grown single crystal silicon ingot grown under conditions that meet or exceed the standards of Perfect Silicon® (SunEdison Semiconductor, Ltd.). These standards include ingots or wafers sliced ​​therefrom that meet or exceed industry specifications for agglomerated defects, DSOD (direct surface oxide defects), COP (crystal origin pits or particles), D-defects, and I-defects, etc. For example, a "perfect silicon" wafer may be characterized by no detectable FPD (flow pattern defects by Secco etching technique) and DSOD (direct surface oxide defect particle count after electrical breakdown), and zero I-defects (A-defects) by Secco etching technique. The Secco etch (or etching) involves the application of a dilute aqueous solution of alkali dichromate and hydrofluoric acid to adequately reveal dislocations and other lattice defects in the various crystallographic (100), (111), and (110) planes of silicon. The etch results in both lineages (low angle grain boundaries) and slip lines. The disclosed method enables the growth of perfect silicon, e.g., single crystal silicon ingots, including wafers sliced ​​from such ingots, over at least about 70% of the body length of the single crystal silicon ingot, e.g., over at least about 80% of the body length of the single crystal silicon ingot, or even over at least about 90% of the body length of the single crystal silicon ingot.In some embodiments, wafers sliced ​​from ingots grown over at least about 60% of the body length of the monocrystalline silicon ingot, over at least about 70% of the body length of the monocrystalline silicon ingot, for example, over at least about 80% of the body length of the monocrystalline silicon ingot, or even over at least about 90% of the body length of the monocrystalline silicon ingot, are characterized by no detectable FPD (flow pattern defects by Secco etching technique) and DSOD (direct surface oxide defect particle count after electrical breakdown) and zero I defects (A defects) by Secco etching technique. In some embodiments, wafers sliced ​​from ingots grown over at least about 60% of the body length of the monocrystalline silicon ingot, over at least about 70% of the body length of the monocrystalline silicon ingot, e.g., over at least about 80% of the body length of the monocrystalline silicon ingot, or even over at least about 90% of the body length of the monocrystalline silicon ingot, are characterized by a GOI yield (i.e., non-failure) in MOS transistors of 95% or greater, preferably 99% or greater, at ≦8 MV (B-mode) and / or 95% or greater, preferably 99% or greater, at 10-12 MV (D-mode). In some embodiments, wafers sliced ​​from an ingot grown over at least about 60% of the body length of the monocrystalline silicon ingot, over at least about 70% of the body length of the monocrystalline silicon ingot, such as over at least about 80% of the body length of the monocrystalline silicon ingot, or even over at least about 90% of the body length of the monocrystalline silicon ingot, with less than 20 COPs at 0.026 μm size or less to qualify as whole silicon.

[0030] In the conventional batch Czochralski method for growing single-crystal silicon ingots, both the crystal melt / interface and thermal conditions change continuously as a function of increasing ingot length due to the variability of silicon melt consumption and crucible position during ingot growth. A depiction of melt depletion and crucible movement can be found in Figure 1. Figures 1A (early body growth), 1B (middle body growth), and 1C (late body growth) show the melt level and crucible height as a function of crystal length during the batch Cz process. Because melt conditions, such as mass, height level, and crucible position, are continuously changing during the batch process, the v / G ratio (growth rate V / axial temperature gradient G) required to minimize defectivity continuously changes the crystal length and alters crystal quality. To maintain the desired quality within specifications within the process window, continuous control adjustment of several parameters is required depending on the position. These parameters include crucible rotation rate (C / R), seed rotation rate (S / R), seed lift rate (S / L), heater power, reflector height, etc. See Figure 2A, which is a graph showing the constant variation in pull-up rate required to achieve sufficient defectivity control in ingots grown by a typical batch Cz process. The lines defined by triangles (---▲---) are the ever-changing critical pull-up rates for achieving critical v / G values. The pull-up rate can be varied within the upper critical pull-up rate ("UCL"), indicated by squares (---■---), and the lower critical pull-up rate ("LCL"), indicated by diamonds (---◆---), and still achieve acceptable defectivity control. These three lines represent pull-up rates capable of producing perfect silicon. Within the upper and lower pull-up rate boundaries, perfect silicon with predominant intrinsic point defects can be produced. For example, when the applied pulling rate is controlled between the lines labeled with triangles and squares in FIG. 2A (and FIGS. 3 and 4), vacancy-dominated ("Pv") silicon is produced, and when the applied pulling rate is controlled between the lines labeled with triangles and diamonds in FIG. 2A (and FIGS. 3 and 4), interstitial-dominated ("Pi") silicon is produced.In the example depicted in FIG. 2A (as well as FIGS. 3 and 4), in the early and middle portions of ingot growth, full silicon with vacancy-dominated point defects can be grown, as shown by the representation of the ingot cross-section labeled "Pv." FIG. 2A shows that the ingot is vacancy-dominated from the center to the edge. In the example shown in FIG. 2A, in later growth, the ingot is characterized by regions of vacancy-dominated point defects and interstitial-dominated point defects, as shown in the cross-sectional area region labeled "Pi." For example, an ingot can be grown that is interstitial-dominated from the center to a radial length less than the entire ingot radius, surrounded by a band of vacancy-dominated material to the ingot's edge. Still, in the later region, the cross-sectional area of ​​the ingot shows vacancy-dominated material in the center, surrounded by another band of vacancy-dominated material at the edge. These depictions are merely for illustrative purposes and are not intended to be limiting on the methods of the present disclosure. Perfect silicon, i.e., ingots and their rice wafers free of detectable agglomerated point defects, is due in part to the proper control of excess point defects (vacancies and interstitials) due to the ingot pull rate. Intrinsic point defects, such as vacancies and interstitials, occur in ingots grown by the Czochralski method. The presence of such defects has no impact on whether the silicon is perfect. Rather, perfect silicon is characterized as being free of agglomerated point defects, such as COP, DSOD, and I defects.

[0031] FIG. 2A (and also FIGS. 3 and 4A) shows the agglomerated defects that can occur in ingots as a function of pull-rate outside the upper and lower critical v / G limits at any crystal length. If the upper critical pull-rate is exceeded (v / G is higher than the critical v / G), defects that can occur include DSOD (direct surface oxide defects) or COP (crystal-origin pits or particles). If the pull-rate is below the lower critical pull-rate (v / G is lower than the critical v / G), defects that can occur include I-defects. The bands in which these defects occur are also shown in the ingot cross-section. In regions where the predominant excess point defects are vacancies, agglomeration of vacancy defects forms bulk defects such as COPs and DSOD due to vacancy agglomeration and precipitation during Cz silicon crystal growth and cooling. In regions where the predominant excess point defects are interstitial silicon atoms, they agglomerate to form bulk defects such as I defects due to the agglomeration / precipitation of interstitial silicon atoms, punching out dislocations. Any small deviation in v / G will form defects due to the agglomeration of either vacancies or interstitial silicon atoms.

[0032] In addition to substrate defectivity control, wafer strength is another important variable for certain applications, such as FLASH devices, where higher wafer strength is more advantageous for vertical stacking of devices. In some technologies, wafer strength is provided by manipulation of oxygen deposition (or precipitation) and intrinsic gettering. For example, increasing the oxygen content in the wafer is the predominant method for manipulating oxygen deposition. In addition to or instead of oxygen content manipulation, the melt and the ingot grown therefrom can be doped with impurities such as nitrogen, which can manipulate both COP size and BMD density. Nitrogen doping can also provide a larger full silicon quality window relative to undoped material. Nitrogen doping can segregate axially during growth due to a segregation factor effect. The nitrogen segregation factor is less than unity, approximately 7×10 -4It has been reported that nitrogen does not preferentially partition into the growing ingot, increasing the nitrogen content in the melt during the ingot pulling process and thereby increasing the nitrogen content along the axial length of the growing single-crystal silicon ingot. See Figure 2B, which shows an increase in nitrogen concentration, which can be as much as seven-fold or more from the beginning to the end of ingot growth, along the axial length of a crystal prepared by the batch Czochralski method with melt conditions such as those shown in Figures 1A-1C. Changes in the nitrogen axis due to changes in the position of the growing crystal as polysilicon is consumed, as well as changes in the crystal / melt interface and thermal conditions (see Figures 1A-1C), are obstacles to maintaining good PS quality along the axial direction unless they are compensated for during growth through constant adjustment (or tuning) of the crystal growth conditions. Because of this, v / G continuously changes the crystal length, which can alter the crystal quality.

[0033] magnetic field , e.g., horizontal or Cusp (or Tip : cusp) magnetic field can be applied to alter the melt flow pattern within the crucible and allow for increased control of the shape and height of the crystal / melt interface, thereby enhancing quality control. However, as illustrated in Figure 3, pulling rates and other parameters must still be modified to achieve acceptable defectivity control. Figure 3 shows the effect of an applied magnetic field2B is a graph showing the pull-up rate profile required to achieve sufficient defectivity control in an ingot grown by a typical batch Cz process at 2000 K. The line defined by the triangles (---▲---) is the critical pull-up rate for achieving a critical v / G value, which is continuously varied, if necessary, during the growth of the single crystal silicon ingot. The pull-up rate can be varied within the upper critical pull-up rate ("UCL") indicated by the squares (---■---) and the lower critical pull-up rate ("LCL") indicated by the diamonds (---◆---) and still achieve acceptable defectivity control. The regions of intrinsic point defects and agglomerated point defects in the cross-sectional area of ​​the single crystal silicon ingot are substantially the same as those described above in the description of FIG. 2A.

[0034] According to the method of the present disclosure, single crystal silicon ingots are grown by the continuous Czochralski (CCZ) method under conditions that allow the melt depth (i.e., height level of the molten silicon) and thermal conditions to remain substantially constant during growth, as the melt is continuously replenished as it is consumed. In some embodiments, maintaining a substantially constant height level of the molten silicon allows the crucible to be maintained in a fixed position. Once v / G is fixed with the appropriate hot zone configuration, the process window will be fixed (i.e., no control adjustments) over a substantial portion of the crystal length. Once the process conditions (S / R, power, gas flow and / or pressure, magnetic flux density, Cusp Once the HMCZ MGP position (or HMCZ MGP position) is set, gas flow, chamber pressure, and C / R are used to control the oxygen content. Thus, the disclosed method enables the growth of single crystal silicon ingots by the continuous Czochralski (CCZ) method, where the pull rate is constant throughout the growth of a substantial length of the ingot, and ingots grown by this method have consistent and acceptable defectivity control, O 2 , over a substantial portion of the ingot's axial length. i It has uniformity, BMD uniformity and nitrogen content uniformity.

[0035] After all conditions are set to steady state, the pull rate for producing a single crystal silicon ingot with the desired defectivity control throughout the entire crystal length will be consistent and significantly reduced quality loss due to process control compared to conventional Cz processes. Figure 4A is a graph of pull rate as a function of axial length of a single crystal silicon ingot during an exemplary continuous Czochralski growth method according to the present disclosure. As shown in Figure 4A, a constant pull rate is maintained throughout a substantial portion of the growth of the main body of the single crystal silicon ingot. The line defined by the triangles (---▲---) is the critical pull rate for achieving the critical v / G value, which has an initial varying region followed by a region of constant pull rate throughout a substantial portion of the growth of the main body of the single crystal silicon ingot. The pull rate can be varied within an upper critical pull rate ("UCL") indicated by squares (---■---), and a lower critical pull rate ("LCL") indicated by diamonds (---◆---), and still achieve acceptable defectivity control. The regions of intrinsic point defects and agglomerated point defects in the cross-sectional area of ​​the single crystal silicon ingot are substantially the same as those described above in the description of FIG. 2A.

[0036] In the CCZ process according to the disclosed method, polycrystalline silicon supply is continuous with the growing crystal, thereby maintaining the melt volume substantially similar to the initial input melt depth regardless of the crystal length. Because the melt elevation is controlled by the mass balance between the growing crystal weight and the continuously supplied polycrystalline silicon, the thermal conditions in the melt and the growing crystal remain constant throughout the axial growth. Thereafter, once the desired crystal / melt interface is reached, the melt volume is maintained substantially the same as the initial input melt depth regardless of the crystal length. magnetic field If the parameters such as C / R and S / R, pulling speed, heater power, etc. are determined and fixed, the defect quality and O iControl will be maintained constant throughout the growth of the crystal axis. Furthermore, because the thermal conditions and crystal / melt interface are fixed during crystal growth, a constant pull rate for a given HZ and crystal / melt interface can be used throughout the entire crystal length in guasi-steady state control.

[0037] According to the method of the present disclosure, the thermal conditions suitable for achieving the growth of a single-crystalline silicon ingot that meets the requirements for defect control are established by a hot-zone configuration. This growth method is a continuous Czochralski growth method. Accordingly, the furnace chamber includes a means for continuous supply of polycrystalline silicon, e.g., a feed tube. While chunk polysilicon can be used, the solid polysilicon added to the crucible is typically granular polysilicon, which is fed to the crucible using a polysilicon feeder optimized for granular polysilicon applications. Chunk polysilicon typically has a size of 3 to 45 millimeters (e.g., maximum dimension), while granular polysilicon typically has a size of 400 to 1400 microns. Granular polysilicon has several advantages, including easier and more precise control of the feed rate due to its smaller size. However, the cost of granular polysilicon is typically higher than that of chunk polysilicon due to the chemical vapor deposition process or other manufacturing methods used to produce it. Chunk polysilicon has the advantage of being cheaper and allowing for a higher feed rate given its larger size. Adapt the polysilicon feeder by adjusting the position of the heating unit, the operation of the cooling jacket and the power controls.

[0038] A depiction of a crucible 10 having multiple weirs (20, 30, 40) or fluid barriers that separate the melt into different melt zones is shown in FIG. 5. In the illustrated embodiment, the crucible assembly 10 includes a first weir 20 (broadly, a fluid barrier) that defines an inner melt zone 22 of the silicon melt. The inner melt zone 22 is a growth region in which a single crystal silicon ingot 50 is grown. A second weir 30 defines an intermediate melt zone 32 of the silicon melt. Finally, a third weir 40 defines an outer melt zone 42 of the silicon melt. A feed pipe (not shown) delivers polycrystalline silicon, which may be grains, chunks, or a combination of grains and chunks, to the outer melt zone 42 at a rate sufficient to maintain a substantially constant melt height level and volume during ingot growth. Each of first weir 20, second weir 30, and third weir 40 has a generally annular shape and at least one opening defined therein to allow molten silicon to flow radially inward toward the growth region of inner melt zone 22. The crucible configuration shown in FIG. 5 is exemplary and suitable for carrying out the process of the present disclosure. Other configurations suitable for CCZ may be used without departing from the scope of the present disclosure. For example, crucible 10 may lack second weir 30 and / or may lack third weir 40.

[0039] Typically, the melt from which the ingot is extracted is formed by loading polycrystalline silicon into a crucible to form an initial silicon charge. Typically, the initial charge is about 100 kilograms to about 400 kilograms of polycrystalline silicon, e.g., about 100 kilograms to about 300 kilograms or about 100 kilograms to about 200 kilograms, which can be grains, chunks, or a combination of grains and chunks. The mass of the initial charge depends on the desired crystal diameter and HZ design. Because polycrystalline silicon is continuously supplied during crystal growth, the initial charge does not reflect the crystal length. For example, if polycrystalline silicon is continuously supplied and the chamber height is sufficiently high, the crystal length can extend to 2000 mm, 3000 mm, or even 4000 mm. The crucible can have the configuration shown in FIG. 5 or another configuration suitable for CCZ growth. Polycrystalline silicon from various sources may be used, including, for example, granular polycrystalline silicon produced by the thermal decomposition of silane or halosilane in a fluidized bed reactor, or polycrystalline silicon produced in a Siemens reactor.

[0040] In some embodiments, the melt is further charged with a nitrogen source so that the single crystal silicon ingot grown by the methods of the present disclosure is doped with nitrogen. In some embodiments, the nitrogen source is a solid source of nitrogen, such as silicon nitride. Silicon nitride has the chemical formula Si X N Ywhere X and Y are both 1, or one or both of X and Y are greater than 1. Any form of silicon nitride can be used, with Si3N4 being the most common and stable. The silicon nitride can be in granular or powder form. In some embodiments, the nitrogen source is a silicon wafer having a silicon nitride film on its surface. The silicon nitride film can also be deposited on the silicon wafer by chemical vapor deposition, for example, a 0.5 to 10 micrometer thick film, e.g., about 1 micrometer thick film, on one or both sides of the wafer. The silicon wafer can be added whole or broken into small pieces. In some embodiments, the nitrogen source is silicon oxynitride glass. In some embodiments, nitrogen doping can be achieved by doping with a nitrogen-containing gas, such as nitrogen (N2) gas. To form the initial charge, the nitrogen source can be added directly to the polycrystalline silicon charge if a solid source is used. As the single crystal silicon ingot grows, a nitrogen source is added periodically or continuously to maintain a uniform concentration of nitrogen in each portion of the single crystal silicon ingot.

[0041] The methods of the present disclosure allow for uniform nitrogen concentrations in each portion of the growing single crystal silicon ingot, including the neck, the outwardly extending seed cone, and the body of the single crystal silicon ingot. In some embodiments, the nitrogen concentration in each portion of the growing single crystal silicon ingot is at least about 1×10 13 atoms / cm 3 , for example, about 1 x 10 13 atoms / cm 3 ~Approx. 1×10 15 atoms / cm 3 , or approximately 1 × 10 13 atoms / cm 3 ~Approx. 1.5×10 14 atoms / cm 3 , or about 5 × 10 13 atoms / cm 3 ~Approx. 1×10 14 atoms / cm 3Preferably, the change in nitrogen concentration is not more than about 20% greater than and not less than 20% less than the setpoint or average nitrogen concentration across the axial length of the single crystal silicon ingot. More preferably, the change in nitrogen concentration is not more than about 10% greater than and not more than 10% less than the setpoint or average nitrogen concentration across the axial length of the single crystal silicon ingot. Even more preferably, the change in nitrogen concentration is not more than about 5% greater than and not more than 5% less than the setpoint or average nitrogen concentration across the axial length of the single crystal silicon ingot. For example, when the setpoint, i.e., target, nitrogen concentration is 7×10 13 atoms / cm 3 then, preferably, the concentration of nitrogen throughout the axial length of the single crystal silicon ingot is about 5.67×10 13 atoms / cm 3 ~Approx. 8.47×10 13 atoms / cm 3 , more preferably about 6.3 x 10 13 atoms / cm 3 ~Approx. 7.7×10 13 atoms / cm 3 , and even more preferably about 6.65×10 13 atoms / cm 3 ~Approx. 7.35×10 13 atoms / cm 3See FIG. 4B, which is a graph illustrating the nitrogen concentration uniformity (line defined by open circles ○) that may be achieved by periodic or continuous addition of nitrogen during typical continuous Czochralski growth according to the disclosed method. The uniformity may be compared to the increase in nitrogen concentration observed during batch growth processes (line defined by filled circles ●). See FIG. 2C. Preferably, a uniform nitrogen concentration is achieved during growth of all portions, including the neck, the outwardly extending seed cone, and the body of the ingot. In some embodiments, a uniform nitrogen concentration is achieved during growth of at least 40% of the axial length of the single crystal silicon ingot, at least 50% of the axial length of the single crystal silicon ingot, at least 60% of the axial length of the single crystal silicon ingot, at least 70% of the axial length of the single crystal silicon ingot, or at least 80% of the axial length of the single crystal silicon ingot, or at least 90% of the axial length of the single crystal silicon ingot.

[0042] Once the polycrystalline silicon and nitrogen source are added to the crucible to form a charge, the charge is heated to a temperature above about the melting temperature of silicon (e.g., about 1412°C) to melt the charge, thereby forming a silicon melt comprising molten silicon. The silicon melt has an initial volume of molten silicon and an initial melt height level, these parameters being determined by the size of the initial charge. In some embodiments, the crucible containing the silicon melt is heated to a temperature of at least about 1425°C, at least about 1450°C, or even at least about 1500°C. The silicon melt further comprises a volume of at least about 1×10 13 nitrogen atoms / cm 3 In some embodiments, the silicon melt further comprises a nitrogen source sufficient to provide a nitrogen dopant concentration in the neck of the ingot of about 1×10 13 atoms / cm 3 ~Approx. 1×10 15 atoms / cm 3 , or approximately 1 × 10 13 atoms / cm 3 ~Approx. 1.5×10 14 atoms / cm 3 , or about 5 × 1013 atoms / cm 3 ~Approx. 1×10 14 atoms / cm 3 The nitrogen source is sufficient to provide a nitrogen dopant concentration in the neck of the ingot of 0.1 wt.

[0043] Generally, there is no limit on the resistivity of a single monocrystalline silicon ingot. Therefore, the resistivity of a single monocrystalline silicon ingot is based on the requirements of the end use / application of the structure of the present disclosure. Therefore, the resistivity can vary from sub-milliohms to megaohms or more. In some embodiments, the crucible is doped with a p-type or n-type dopant. Suitable dopants include boron (p-type), gallium (p-type), phosphorus (n-type), antimony (n-type), and arsenic (n-type). The dopant concentration is selected based on the desired resistivity of wafers sliced ​​from the monocrystalline silicon ingot.

[0044] In some embodiments, single crystal silicon ingots pulled by the methods of the present disclosure have a relatively low minimum bulk resistivity, such as less than about 100 ohm-cm, less than about 50 ohm-cm, less than about 1 ohm-cm, less than about 0.1 ohm-cm, or even less than about 0.01 ohm-cm. In some embodiments, single crystal silicon ingots have a relatively low minimum bulk resistivity, such as less than about 100 ohm-cm, or between about 1 ohm-cm and about 100 ohm-cm. Low resistivity wafers can include electrically active dopants, such as boron (p-type), gallium (p-type), phosphorus (n-type), antimony (n-type), and arsenic (n-type). In some embodiments, dopants are added to the initial charge in the crucible, and resistivity uniformity is maintained by continuous or periodic addition of dopants during crystal growth.

[0045] In some embodiments, the single crystal silicon ingot has a relatively high minimum bulk resistivity. Electrically active dopants such as boron (p-type), gallium (p-type), aluminum (p-type), indium (p-type), phosphorus (n-type), antimony (n-type), and arsenic (n-type) can be added to the crucible, typically in very low concentrations. Cz-grown silicon wafers can also be subjected to thermal annealing at temperatures ranging from about 600°C to about 1000°C to annihilate thermal donors caused by oxygen incorporated during crystal growth. In some embodiments, the single crystal silicon ingot has a resistivity of at least 100 ohm-cm, at least about 500 ohm-cm, at least about 1000 ohm-cm, or even at least about 3000 ohm-cm, for example, from about 100 ohm-cm to about 100,000 ohm-cm, or from about 500 ohm-cm to about 100,000 ohm-cm, or from about 1000 ohm-cm to about 100,000 ohm-cm. The monocrystalline silicon ingot may have a minimum bulk resistivity of about 500 ohm-cm to about 10,000 ohm-cm, or about 750 ohm-cm to about 10,000 ohm-cm, about 1000 ohm-cm to about 10,000 ohm-cm, about 2000 ohm-cm to about 10,000 ohm-cm, about 3000 ohm-cm to about 10,000 ohm-cm, or about 3000 ohm-cm to about 5,000 ohm-cm. In some embodiments, the monocrystalline silicon ingot may include a p-type dopant, such as boron, gallium, aluminum, or indium. In some embodiments, the monocrystalline silicon ingot may include an n-type dopant, such as phosphorus, antimony, or arsenic. In some embodiments, dopants are added to the initial charge in the crucible, and resistivity uniformity is maintained by continuous or periodic addition of dopants during crystal growth.For example, in some embodiments, the body portion has a resistivity that varies no more than 20% above and more than 20% below the average body resistivity over at least 40% of the body axis length of the single crystal silicon ingot, over at least 50% of the body axis length of the single crystal silicon ingot, over at least 60% of the body axis length of the single crystal silicon ingot, over at least 70% of the body axis length of the single crystal silicon ingot, or over at least 80% of the body axis length of the single crystal silicon ingot, or over at least 90% of the body axis length of the single crystal silicon ingot. In some embodiments, the body portion has a resistivity that varies no more than 10% above and more than 10% below the average body resistivity over at least 40% of the body axis length of the single crystal silicon ingot, over at least 50% of the body axis length of the single crystal silicon ingot, over at least 60% of the body axis length of the single crystal silicon ingot, over at least 70% of the body axis length of the single crystal silicon ingot, or over at least 80% of the body axis length of the single crystal silicon ingot, or over at least 90% of the body axis length of the single crystal silicon ingot. In some embodiments, the body portion has a resistivity that varies no more than 5% above and no less than 5% below the average body resistivity over at least 40% of the body axis length of the single crystal silicon ingot, over at least 50% of the body axis length of the single crystal silicon ingot, over at least 60% of the body axis length of the single crystal silicon ingot, over at least 70% of the body axis length of the single crystal silicon ingot, or over at least 80% of the body axis length of the single crystal silicon ingot, or over at least 90% of the body axis length of the single crystal silicon ingot.

[0046] Once the charge is liquefied to form a silicon melt containing molten silicon, the silicon seed crystal is lowered into contact with the melt. The silicon seed crystal is then removed from the melt attached thereto (i.e., with reference to FIG. 5 , the seed crystal portion and neck 52), thereby forming a melt / solid interface near or at the surface of the melt. Generally, the initial pulling speed to form the neck is high. In some embodiments, the silicon seed crystal and neck are pulled at a neck pulling speed of at least about 1.0 mm / min, e.g., about 1.5 mm / min to about 6 mm / min, e.g., about 3 mm / min to about 5 mm / min. In some embodiments, the silicon seed crystal and crucible are rotated in opposite directions (i.e., counter-rotation). Counter-rotation achieves convection in the silicon melt. Crystal rotation is primarily used to provide a symmetrical temperature profile, suppress angular variations in impurities, and control the crystal-melt interface shape. In some embodiments, the silicon seed crystal is rotated at a speed of about 5 rpm to about 30 rpm, or about 5 rpm to about 20 rpm, or about 8 rpm to about 20 rpm, or about 10 rpm to about 20 rpm. In some embodiments, the crucible is rotated at a speed of about 0.5 rpm to about 10 rpm, or about 1 rpm to about 10 rpm, or about 4 rpm to about 10 rpm, or about 5 rpm to about 10 rpm. In some embodiments, the seed crystal is rotated at a speed that is faster than the crucible. In some embodiments, the seed crystal is rotated at a speed that is at least 1 rpm higher than the crucible rotation speed, e.g., at least 3 rpm higher, or at least 5 rpm higher. Typically, the crystal rotation speed is higher than the crucible rotation speed to favor good radial uniformity of the dopant concentration in the crystal. In some embodiments, the silicon seed crystal and the crucible are rotated in opposite directions (i.e., counter-rotating).

[0047] Typically, the neck portion has a length of about 10 mm to about 700 mm, about 30 mm to about 700 mm, about 100 mm to about 700 mm, about 200 mm to about 700 mm, or about 300 mm to about 700 mm. In some embodiments, the neck portion has a length of about 10 mm to about 100 mm, e.g., about 20 to about 50 mm. In some embodiments, the neck portion has a length of about 350 mm to about 550 mm. In some embodiments, the neck portion has a length of about 450 mm to about 550 mm. However, the length of the neck can vary outside these ranges. In some embodiments, the neck portion has a diameter of about 1 mm to about 10 mm, about 2.5 mm to about 6.5 mm, e.g., about 3 mm to about 6 mm. Since the silicon melt is doped with nitrogen, the neck portion 52 of the ingot is doped with nitrogen. In some embodiments, the neck portion 52 has a diameter of at least about 1×10 13 atoms / cm 3 In some embodiments, neck portion 52 has a neck nitrogen concentration of about 1×10 13 atoms / cm 3 ~Approx. 1×10 15 atoms / cm 3 , or approximately 1 × 10 13 atoms / cm 3 ~Approx. 1.5×10 14 atoms / cm 3 , or about 5 × 10 13 atoms / cm 3 ~Approx. 1×10 14 atoms / cm 3 Preferably, the change in nitrogen concentration is about 20% or less than the set point or average nitrogen concentration over the axial length of the neck. More preferably, the change in nitrogen concentration is about 10% or less than the set point or average nitrogen concentration over the axial length of the neck. Even more preferably, the change in nitrogen concentration is about 5% or less than the set point or average nitrogen concentration over the axial length of the neck.

[0048] After the formation of the neck, with reference to FIG. 5 , an outwardly flaring seed cone portion 54 adjacent the neck 52 is grown. Generally, the pulling rate is reduced from the neck pulling rate to a rate appropriate for growing the outwardly flaring seed cone portion. For example, the seed cone pulling rate during outwardly flaring seed cone growth is about 0.5 mm / min to about 2.0 mm / min, e.g., about 1.0 mm / min. In some embodiments, the outwardly flaring seed cone has a length of about 100 mm to about 400 mm, e.g., about 150 mm to about 250 mm. The length of the outwardly flaring seed cone 54 can vary outside these ranges. In some embodiments, the outwardly flaring seed cone 54 is grown to a terminal diameter of about 150 mm, at least about 150 mm, about 200 mm, at least about 200 mm, about 300 mm, at least about 300 mm, about 450 mm, or even at least about 450 mm. The end diameter of the outwardly extending seed cone 54 is generally equivalent to the diameter of the constant diameter of the main body of the single crystal silicon ingot. According to the method of the present disclosure, the outwardly extending seed cone 54 of the ingot is doped with nitrogen. In some embodiments, the outwardly extending seed cone 54 has a nitrogen content of at least about 1×10 13 atoms / cm 3 In some embodiments, the outwardly extending seed cone 54 has a nitrogen concentration of about 1×10 13 atoms / cm 3 ~Approx. 1×10 15 atoms / cm 3 , about 1×10 13 atoms / cm 3 ~Approx. 1.5×10 14 atoms / cm 3 , or about 5 × 10 13 atoms / cm 3 ~Approx. 1×10 14 atoms / cm 3Preferably, the variation in nitrogen concentration in the outwardly extending seed cone 54 is about 20% or less than and 20% or more less than the setpoint nitrogen concentration. More preferably, the variation in nitrogen concentration in the outwardly extending seed cone 54 is about 10% or less than and 10% or more less than the setpoint nitrogen concentration. Even more preferably, the variation in nitrogen concentration in the outwardly extending seed cone 54 is about 5% or less than and 5% or more less than the setpoint nitrogen concentration. Again, with reference to FIG. 4B , nitrogen concentration uniformity is preferably achieved by exemplary methods according to the present disclosure during growth of all portions of the ingot, including the outwardly extending seed cone.

[0049] After formation of the neck and outwardly extending seed cone, an ingot body 56 is then grown having a constant diameter adjacent the cone portion. The constant diameter portion of the body 56 has a peripheral edge, a central axis parallel to the peripheral edge, and a radius extending from the central axis to the peripheral edge. The central axis also passes through the cone portion and the neck 52. The diameter of the ingot body can vary, and in some embodiments, the diameter can be about 150 mm, at least about 150 mm, about 200 mm, at least about 200 mm, about 300 mm, at least about 300 mm, about 450 mm, or even at least about 450 mm. In some embodiments, the monocrystalline silicon ingot body is eventually grown to be at least about 1000 millimeters long, e.g., at least 1100 millimeters long, e.g., at least 1200 millimeters long, e.g., at least 1400 millimeters long, e.g., at least 1500 millimeters long, e.g., at least 1700 millimeters long, or at least 1900 millimeters long, or at least 2000 millimeters long, or at least 2200 millimeters long, or at least about 3000 millimeters long, or at least about 4000 millimeters long. According to the methods of the present disclosure, the ingot body 56 is doped with nitrogen. In some embodiments, the body 56 is doped with at least about 1×10 13 atoms / cm 3 In some embodiments, the body 56 has a body nitrogen concentration of about 1×1013 atoms / cm 3 ~Approx. 1×10 15 atoms / cm 3 , or approximately 1 × 10 13 atoms / cm 3 ~Approx. 1.5×10 14 atoms / cm 3 , or about 5 × 10 13 atoms / cm 3 ~Approx. 1×10 14 atoms / cm 3Preferably, the variation in nitrogen concentration in body 56 is about 20% or less than and 20% or more less than the setpoint nitrogen concentration. More preferably, the variation in nitrogen concentration in body 56 is about 10% or less than and 10% or more less than the setpoint nitrogen concentration. Even more preferably, the variation in nitrogen concentration in body 56 is about 5% or less than and 5% or more less than the setpoint nitrogen concentration. Again, with reference to FIG. 4B , nitrogen concentration uniformity is preferably achieved by exemplary methods according to the present disclosure during growth of all portions of the ingot, including the main body portion. In some embodiments, the body comprises nitrogen with a body nitrogen concentration that varies no more than 20% above and more than 20% below the average body nitrogen concentration over at least 40% of the body axial length of the single crystal silicon ingot, over at least 50% of the body axial length of the single crystal silicon ingot, over at least 60% of the body axial length of the single crystal silicon ingot, over at least 70% of the body axial length of the single crystal silicon ingot, or over at least 80% of the body axial length of the single crystal silicon ingot, or over at least 90% of the body axial length of the single crystal silicon ingot. In some embodiments, the body comprises nitrogen with a body nitrogen concentration that varies by no more than 10% above and by more than 10% below the average body nitrogen concentration over at least 40% of the body axial length of the single crystal silicon ingot, over at least 50% of the body axial length of the single crystal silicon ingot, over at least 60% of the body axial length of the single crystal silicon ingot, over at least 70% of the body axial length of the single crystal silicon ingot, or over at least 80% of the body axial length of the single crystal silicon ingot, or over at least 90% of the body axial length of the single crystal silicon ingot.In some embodiments, the body comprises nitrogen with a body nitrogen concentration that varies by no more than 5% above and by no less than 5% below the average body nitrogen concentration over at least 40% of the body axial length of the single crystal silicon ingot, over at least 50% of the body axial length of the single crystal silicon ingot, over at least 60% of the body axial length of the single crystal silicon ingot, over at least 70% of the body axial length of the single crystal silicon ingot, or over at least 80% of the body axial length of the single crystal silicon ingot, or over at least 90% of the body axial length of the single crystal silicon ingot.

[0050] 4A shows a typical, non-limiting pull-rate protocol for pulling a single crystal silicon ingot body according to some embodiments of the disclosed method. As is evident from the typical illustration, the pull-rate decreases from a relatively high pull-rate to a minimum pull-rate and then increases to a constant pull-rate for a significant portion of the growth of the single crystal silicon ingot body. According to the disclosed process, the pull-rate is selected to achieve perfect silicon, i.e., silicon characterized by a lack of detectable agglomerated defects selected from agglomerated defects, DSOD (direct surface oxidation defects), COP (crystal origin pits), D-defects, and I-defects, etc. The initial high pull rate can be about 0.5 mm / min to about 2.0 mm / min, for example, about 1.0 mm / min, then reduced to a pull rate that can be as low as about 0.4 mm / min or as low as about 0.3 mm / min, and then increased to a constant pull rate of about 0.4 mm / min to about 0.8 mm / min, about 0.4 mm / min to about 0.7 mm / min, or about 0.4 mm / min to about 0.65 mm / min.

[0051] Typical, non-limiting examples of hot zone configurations within a furnace chamber 100 suitable for practicing the disclosed method are shown in Figures 6A, 6B, and 6C. Other hot zone configurations are suitable for practicing the disclosed method. The hot zone configuration includes a cooling jacket 102, a reflector 104, a side heater 106, and a bottom heater 108. The growing crystal diameter and meniscus shape and height are monitored by a camera (not depicted) located in the top window. Data obtained from the camera provides feedback to the side heater 106 and bottom heater 108. During crystal growth, the power distribution can be adjusted between the heaters to enable uniformity of the melt / solid interface, i.e., to maintain the desired meniscus shape and height. The reflector 104 will reflect heat flow from the hot parts of the furnace, including the heaters and crucible, to the melt. The reflector 104 reduces heat transfer from the hot section of the furnace to the cooler section (maintained by the cooling jacket 102), thereby maintaining separation between these two regions of the furnace. The reflector helps control the axial and radial temperature gradients that drive the solidification and crystallization of the molten silicon into the growing ingot.

[0052] Figures 6A, 6B, and 6C show the first, second, and third steps, respectively, which correspond to the regions of the pulling rate shown in Figure 4A. That is, the first step shown in Figure 6A corresponds to the region in Figure 4A where the pulling rate is high and decreases to a minimum. The second step shown in Figure 6B corresponds to the region in Figure 4A where the pulling rate is minimum and increases to a constant pulling rate. The third step shown in Figure 6C corresponds to the region of constant pulling rate in Figure 4A. During each step, polycrystalline silicon is continuously supplied to the melt during growth of the ingot 112 (see Figure 5), so that the melt 110 maintains a constant melt volume and melt height level according to embodiments of the present disclosure.

[0053] The initial region for growing the monocrystalline silicon ingot body characterized by a variable pull rate may encompass less than about 20% of the total length of the monocrystalline silicon ingot body. In some embodiments, the variable pull rate regime may encompass about 5% to about 20% of the monocrystalline silicon ingot body length, e.g., about 5% to about 15% of the monocrystalline silicon ingot body length, or about 10% to about 15% of the monocrystalline silicon ingot body length. The percentage of the monocrystalline silicon ingot body length grown under variable pull rate conditions depends in part on the total length of the ingot body. For example, the body length of an ingot pulled under variable rate conditions may vary from about 50 mm to about 200 mm, from about 100 mm to about 200 mm, e.g., from about 150 mm to about 200 mm. If 200 mm is grown under variable rate conditions and the total body length of the ingot is 1400 mm, then about 14% of the body is grown under variable rate conditions, while only about 9% of the body is grown under variable rate conditions for a total body length of 2200 mm.

[0054] After an initial region of the body is grown under variable pull-rate conditions, the remainder of the body is grown under a constant pull-rate. In some embodiments, the ingot body is grown at a constant body pull-rate during growth of at least about 30% of the length of the single crystal silicon ingot, e.g., at least about 50% of the length of the single crystal silicon ingot, at least about 70% of the length of the single crystal silicon ingot, at least about 80% of the length of the single crystal silicon ingot, or even at least about 90% of the length of the single crystal silicon ingot. In some embodiments, the constant body pull-rate is between about 0.4 mm / min and about 0.8 mm / min, between about 0.4 mm / min and about 0.7 mm / min, or between about 0.4 mm / min and about 0.65 mm / min.

[0055] During growth of the main body of the single crystal silicon ingot, polycrystalline silicon, i.e., grains, chunks, or a combination of grains and chunks, is added to the molten silicon to achieve a constant volume of molten silicon and a constant melt height level. According to the method of the present disclosure, maintaining a substantially constant melt volume during growth of a substantial portion of the main axial length of the single crystal silicon ingot allows for the achievement of high ingot quality over a substantial portion of the main axial length of the single crystal silicon ingot at a constant pulling rate. A constant melt volume regardless of crystal length allows for a constant crystal / melt interface, thus allowing for uniform crystal quality over a substantial portion of the main body of the ingot. Thus, in some embodiments, the volume of molten silicon varies by no more than about 1.0 vol.% during growth of at least 90% of the main body of the single crystal silicon ingot, or by no more than about 0.5 vol.% during growth of at least 90% of the main body of the single crystal silicon ingot, or by no more than about 0.1 vol.% during growth of at least 90% of the main body of the single crystal silicon ingot. Stated another way, in some embodiments, the melt height level varies by less than about + / - 0.5 millimeters during the growth of at least 90% of the body of the single crystal silicon ingot.

[0056] During growth of the main body of the single crystal silicon ingot, the melt is further charged with a nitrogen source so that the single crystal silicon ingot grown by the method of the present disclosure is doped with nitrogen. In some embodiments, the nitrogen source is a solid source of nitrogen, such as silicon nitride. The silicon nitride can be in powder form. In some embodiments, the nitrogen source is a silicon wafer having a silicon nitride film on its surface. The silicon nitride film can be deposited on the silicon wafer by chemical vapor deposition to deposit a film, for example, 0.5 to 10 micrometers, e.g., about 1 micrometer, on both sides of the wafer. The silicon wafer can be added whole or broken into small pieces. In some embodiments, the nitrogen source is silicon oxynitride glass. In some embodiments, nitrogen doping can be achieved by doping with a nitrogen-containing gas, such as nitrogen (N) gas. During ingot growth, according to the method of the present disclosure, a nitrogen source can be added to the third weir 40 in addition to the polycrystalline silicon, as shown in FIG. 5.

[0057] The disclosed method is suitable for achieving axially uniform nitrogen concentrations during growth of the neck, seed cone, and body of a single crystal silicon ingot. See FIG. 4B for a depiction of the uniformity that can be achieved by continuous or periodic addition of nitrogen during ingot growth by the disclosed continuous Czochralski technique. Uniformity, which overcomes the segregation typically observed in nitrogen-doped single crystal silicon ingots, is achieved by an automated doping system that continuously or periodically adds a nitrogen source to the melt. The nitrogen source may be added continuously or periodically during growth of the ingot, including each of the neck, seed cone, and body. Also, in some embodiments, for process uniformity and ease, periodic addition of a nitrogen source, for example, every 25 mm, 50 mm, 75 mm, or 100 mm of axial length during ingot growth, is preferred to enhance the achievement of full silicon during ingot axial length growth.

[0058] In some embodiments, the nitrogen source is continuously or periodically supplied to the crucible in an amount of about 1 milligram to about 100 milligrams of nitrogen per 50 mm of axial length of the single crystal silicon ingot body, about 1 milligram to about 25 milligrams of nitrogen per 50 mm of axial length of the single crystal silicon ingot body, or about 2 milligrams to about 15 milligrams of nitrogen per 50 mm of axial length of the single crystal silicon ingot body. In some embodiments, the nitrogen source is silicon nitride, which may be added as a powder. In some embodiments, silicon nitride is continuously or periodically supplied to the crucible during growth of the single crystal silicon ingot body in an amount of about 2.5 milligrams to 250 milligrams of silicon nitride per 50 mm of axial length of the single crystal silicon ingot body, or about 5 milligrams to 100 milligrams of silicon nitride per 50 mm of axial length of the single crystal silicon ingot body, or about 10 milligrams to 50 milligrams of silicon nitride per 50 mm of axial length of the single crystal silicon ingot body. In some exemplary embodiments, about 10 milligrams to about 50 milligrams, e.g., about 25 milligrams of silicon nitride, may be added per 50 mm of axial length of a body having a nominal diameter of about 310 millimeters. The amount of silicon nitride added may be adjusted up or down depending on the nominal diameter of the ingot. For example, about 1 milligram to about 10 milligrams, e.g., about 5 or 6 milligrams, of silicon nitride may be added per 50 mm of axial length for a body having a nominal diameter of about 150 millimeters. In yet another example, about 25 milligrams to about 75 milligrams, e.g., about 45 milligrams to about 60 milligrams, of silicon nitride may be added per 50 mm of axial length for a body having a nominal diameter of about 450 millimeters. A typical feeding protocol displaying total silicon nitride addition as a function of the axial length of a single crystal silicon ingot is shown in Figure 7.

[0059] In some embodiments, a nitrogen source is added during growth to provide about 1×10 13 atoms / cm 3 ~Approx. 1×10 15 atoms / cm3 , or approximately 1 × 10 13 atoms / cm 3 ~Approx. 1.5×10 14 atoms / cm 3 , or about 5 × 10 13 atoms / cm 3 ~Approx. 1×10 14 atoms / cm 3 In some embodiments, a nitrogen source is added during growth to achieve a bulk nitrogen concentration of about 5×10 across at least 40% of the body axial length of the single crystal silicon ingot, across at least 50% of the body axial length of the single crystal silicon ingot, across at least 60% of the body axial length of the single crystal silicon ingot, across at least 70% of the body axial length of the single crystal silicon ingot, or across at least 80% of the body axial length of the single crystal silicon ingot, or across at least 90% of the body axial length of the single crystal silicon ingot, or even across the entire body axial length of the single crystal silicon ingot. 13 atoms / cm 3 ~Approx. 1×10 14 atoms / cm 3 Achieve a nitrogen concentration of

[0060] In some embodiments, a nitrogen source is added during growth to provide about 1×10 13 atoms / cm 3 ~Approx. 1.5×10 14 atoms / cm 3 , or about 5 × 10 13 atoms / cm 3 ~Approx. 1×10 14 atoms / cm 3and further wherein the body nitrogen concentration varies by no more than 20% above and more than 20% below the set point or average body nitrogen concentration over at least 40% of the body axial length of the monocrystalline silicon ingot, over at least 50% of the body axial length of the monocrystalline silicon ingot, over at least 60% of the body axial length of the monocrystalline silicon ingot, over at least 70% of the body axial length of the monocrystalline silicon ingot, or over at least 80% of the body axial length of the monocrystalline silicon ingot, or over at least 90% of the body axial length of the monocrystalline silicon ingot, or even over the entire axial length of the body of the monocrystalline silicon ingot. More preferably, the change in nitrogen concentration in the body 56 is no more than about 10% greater and no less than 10% less than the setpoint nitrogen concentration over at least 40% of the axial length of the single crystal silicon ingot, over at least 50% of the axial length of the single crystal silicon ingot, over at least 60% of the axial length of the single crystal silicon ingot, over at least 70% of the axial length of the single crystal silicon ingot, or over at least 80% of the axial length of the single crystal silicon ingot, over at least 90% of the axial length of the single crystal silicon ingot, or even over the entire axial length of the single crystal silicon ingot body. Even more preferably, the change in nitrogen concentration in the body 56 is no more than about 5% greater and no less than 5% less than the setpoint nitrogen concentration over at least 40% of the axial length of the monocrystalline silicon ingot, over at least 50% of the axial length of the monocrystalline silicon ingot, over at least 60% of the axial length of the monocrystalline silicon ingot, over at least 70% of the axial length of the monocrystalline silicon ingot, or over at least 80% of the axial length of the monocrystalline silicon ingot, or over at least 90% of the axial length of the monocrystalline silicon ingot, or even over the entire axial length of the monocrystalline silicon ingot body.

[0061] In some embodiments, a nitrogen source is added during growth to provide about 5×10 13 atoms / cm 3 ~Approx. 1×10 14 atoms / cm 3and further wherein the body nitrogen concentration varies by no more than 20% above and by more than 20% below the setpoint or average body nitrogen concentration over at least 40% of the body axial length of the single crystal silicon ingot, over at least 50% of the body axial length of the single crystal silicon ingot, over at least 60% of the body axial length of the single crystal silicon ingot, over at least 70% of the body axial length of the single crystal silicon ingot, or over at least 80% of the body axial length of the single crystal silicon ingot. More preferably, the change in nitrogen concentration in the body 56 is no more than about 10% greater and no less than 10% less than the setpoint nitrogen concentration over at least 40% of the axial length of the single crystal silicon ingot, over at least 50% of the axial length of the single crystal silicon ingot, over at least 60% of the axial length of the single crystal silicon ingot, over at least 70% of the axial length of the single crystal silicon ingot, or over at least 80% of the axial length of the single crystal silicon ingot, or over at least 90% of the axial length of the single crystal silicon ingot, or even over the entire axial length of the single crystal silicon ingot body. Even more preferably, the change in nitrogen concentration in the body 56 is no more than about 5% greater and no less than 5% less than the setpoint nitrogen concentration over at least 40% of the axial length of the monocrystalline silicon ingot, over at least 50% of the axial length of the monocrystalline silicon ingot, over at least 60% of the axial length of the monocrystalline silicon ingot, over at least 70% of the axial length of the monocrystalline silicon ingot, or over at least 80% of the axial length of the monocrystalline silicon ingot, or over at least 90% of the axial length of the monocrystalline silicon ingot, or even over the entire axial length of the monocrystalline silicon ingot body.

[0062] Additionally, according to the process of the present disclosure: magnetic field may be applied to a crucible containing silicon melt. Cusp or horizontal magnetic field (or, magnetic fieldA magnet field (magnet field) can be applied to set the appropriate crystal / melt interface, i.e., meniscus, shape and height. magnetic field The desired crystal / melt interface shape and height are first fixed using the oxygen content O i Control of the is a subordinate objective.

[0063] Control of the melt flow and the shape of the melt / solid interface, and therefore the quality of the ingot, depends on the influence of the silicon melt during the growth of the main body of the monocrystalline silicon ingot. magnetic field In some embodiments, the applied magnetic field maintains a substantially constant melt / solid interface profile for at least about 70% of the growth of the body of the single crystal silicon ingot, or between about 70% and about 90% of the growth of the body of the single crystal silicon ingot. magnetic field applies electromagnetic forces that affect the silicon melt flow and therefore the heat transfer in the melt, which changes the crystal / melt interface profile and the temperature at which the crystal grows, which are key control parameters for perfect silicon.

[0064] magnetic field The oxygen source of the ingot is determined by the melting of the quartz crucible wall, evaporation of the melt-free surface (controlled by melt flow dynamics), and the oxygen content and uniformity of the ingot. i O x (g) and from incorporation onto the growing crystal surface. magnetic field can strongly affect the convective melt flow during growth, which in turn can strongly affect oxygen evaporation and incorporation. The change in oxygen incorporation into a single crystal silicon ingot with time increment can be calculated using the following equation:

[0065]

number

[0066] where C is the oxygen concentration of the solidifying silicon, t is time, v is the convection velocity (melt flow velocity), ρ (rho) is the density of the silicon melt, and ∇ is the gradient (d / dx). magnetic field affects the melting rate (v) and the gradient of oxygen concentration in the melt (dC / dx=∇C). magnetic field As a result, a steady state melt flow occurs, and oxygen O i The uptake of oxygen is a time constant, which enhances the radial and axial oxygen concentration uniformity. The term SOURCE refers to the relationship between two parameters: oxygen production (S i (l)+S i O2(s)→S i O x (g)) is quartz (S i O2) melting of the crucible and oxygen (S i O x (g)) is due to evaporation, which is the removal (disappearance) of oxygen (O2). In the batch Cz process, this term SOURCE is not constant. Instead, the SOURCE depends on the crystal length, since the melt mass decreases as the crystal grows. When the ingot grows a substantial portion of its body length, the remaining melt volume is low, and as a result, the amount of silicon melt in contact with the crucible decreases, thus leading to a decrease in the oxygen concentration taken up by the melt from the crucible. Therefore, if other terms (diffusion, convection, evaporation) are constant, the oxygen incorporated into the solidifying silicon crystal decreases. The melt-free surface area (the contact surface between the melt and the gas) is S i O x (g). The small melt mass in the batch Cz process has a relatively smaller surface area due to the crucible geometry shown in Figure 1C. S i O x Less evaporation of (g) means more oxygen incorporation into the solidifying silicon crystal. According to the method of the present disclosure, as polysilicon is added to grow the crystal ingot, the melt mass is kept constant. Therefore, all source terms (S into the melt) i Oxygen generation by crucible melting and S through the melt-free surface i Ox (g) Evaporation of gases is constant. Therefore, the diffusion and convection terms affect the oxygen in the solidifying silicon crystal. magnetic fieldThis makes the melt flow more stable because oxygen incorporation is uniform and stable axially and radially throughout the growth of the ingot (i.e., the melt flow is constant, similar to a time-independent steady-state condition). In some embodiments, interstitial oxygen may be incorporated into the ingot at a concentration of about 4 PPMA to about 18 PPMA. In some embodiments, interstitial oxygen may be incorporated into the ingot at a concentration of about 10 PPMA to about 35 PPMA. In some embodiments, the ingot contains oxygen at a concentration of about 15 PPMA or less, or about 10 PPMA or less. Interstitial oxygen may be measured according to SEMI MF 1188-1105. In some embodiments, the body interstitial oxygen concentration varies by no more than 20% above and by no less than 20% below the average body oxygen concentration over at least 40% of the body axis length of the single crystal silicon ingot, over at least 50% of the body axis length of the single crystal silicon ingot, over at least 60% of the body axis length of the single crystal silicon ingot, over at least 70% of the body axis length of the single crystal silicon ingot, or over at least 80% of the body axis length of the single crystal silicon ingot, or over at least 90% of the body axis length of the single crystal silicon ingot. In some embodiments, the body interstitial oxygen concentration varies by no more than 10% above and by no less than 10% below the average body oxygen concentration over at least 40% of the body axis length of the single crystal silicon ingot, over at least 50% of the body axis length of the single crystal silicon ingot, over at least 60% of the body axis length of the single crystal silicon ingot, over at least 70% of the body axis length of the single crystal silicon ingot, or over at least 80% of the body axis length of the single crystal silicon ingot, or over at least 90% of the body axis length of the single crystal silicon ingot.In some embodiments, the body interstitial oxygen concentration varies by no more than 5% above and by no less than 5% below the average body oxygen concentration over at least 40% of the body axis length of the single crystal silicon ingot, over at least 50% of the body axis length of the single crystal silicon ingot, over at least 60% of the body axis length of the single crystal silicon ingot, over at least 70% of the body axis length of the single crystal silicon ingot, or over at least 80% of the body axis length of the single crystal silicon ingot, or over at least 90% of the body axis length of the single crystal silicon ingot.

[0067] In some embodiments, horizontal magnetic field is applied to the silicon melt during the growth of the body of a single crystal silicon ingot. Such a horizontal field is shown in Figure 8A, which is similar to the horizontal field shown in Figure 5, placed over the crucible and growing ingot. magnetic field This is a depiction of horizontal magnetic field Crystal growth in the presence of a horizontal magnet 200 is achieved by placing a crucible holding the silicon melt between the poles of a conventional electromagnet 200. magnetic field The magnetic flux density in the melt region may be about 0.2 Tesla to about 0.4 Tesla. magnetic field The variation is less than + / - about 0.03 Tesla of a given intensity. magnetic field The application of the force generates a Lorentz force along the axial direction, opposite the direction of the fluid motion and countering the force driving melt convection. Thus, convection in the melt is suppressed, and the axial temperature gradient in the crystal near the interface increases. The melt-crystal interface then shifts upward toward the crystal, accommodating the increased axial temperature gradient in the crystal near the interface, and the contribution from melt convection in the crucible decreases.

[0068] In some embodiments, Cusp magnetic field is applied to the silicon melt during growth of the body of the single crystal silicon ingot. Cusp The field is shown in FIG. 8B, which is placed over the crucible and growing ingot, as shown in FIG. Cusp magnetic field This is a depiction of the following. Cusp magnetic fieldis determined by two control parameters: magnetic flux density and magnetic field It has a shape. Cusp magnetic field is the vertical (axis) in the melt near the axis of the ingot magnetic field and deeper horizontal (radial) at the nearest surface of the combined melt. magnetic field The components are applied. Cusp magnetic field is generated using a pair of Helmholtz coils carrying currents in opposite directions. As a result, two magnetic field At a position midway between the ingot axis, magnetic field cancel each other out, and vertical magnetic field Create a component, for example: Cusp The magnetic flux density in the axial direction is typically about 0 to about 0.2 Tesla. The magnetic flux density in the radial direction is generally higher than the magnetic flux density in the perpendicular direction. For example, Cusp The magnetic flux density is typically about 0 to about 0.6 T at a radial position, depending on the radial position, for example, about 0.2 to about 0.5 T. Cusp magnetic field The radial direction of the melt is suppressed, thereby stabilizing the melt. Cusp magnetic field The application of heat acts as an effective method to induce convection adjacent to the solid-liquid interface where crystal growth occurs and suppress convection in the remaining part of the melt, thereby achieving a uniform oxygen distribution. The melt convection of heat occurs simultaneously at the melt-free surface and at the melt-crucible interface. Cusp magnetic field This allows for control of the oxygen concentration in the growing crystal solely by the magnetic flux density, regardless of the crystal rotation speed. magnetic field In the presence of oxygen, control of the oxygen concentration is achieved through control of the crystal rotation rate. Cusp magnetic field The applied voltage is about 15 PPMA or less, or about 10 PPMA or less. magnetic field This may allow growth on an ingot containing a lower oxygen content than an ingot grown without interstitial oxygen. Interstitial oxygen may be measured by SEMI MF 1188-1105.

[0069] The disclosed method enables the growth of single crystal silicon ingots by the continuous Czochralski process that meets or exceeds industry specifications for perfect silicon. Factors that contribute to the growth of perfect silicon crystals include determining the critical pull rate for growing perfect silicon, maintaining a constant pull rate at the critical rate throughout a substantial portion of the growth of the body of the single crystal silicon ingot, and maintaining the shape and height of the melt / solid interface. magnetic field Once the pulling speed and magnetic field Once the configuration is determined, the pull rate can be maintained at a constant rate by continuously adding polycrystalline silicon to maintain a constant melt volume and melt height level. Thus, unlike conventional methods of growing ingots, the pull rate is constant over a substantial portion of the ingot's growth. In light of the process control enabled by the methods disclosed herein, the methods of the present disclosure enable the growth of single crystal silicon ingots that contain full silicon over at least about 70% of the single crystal silicon ingot's body length, e.g., over at least about 80% of the single crystal silicon ingot's body length, or even over at least about 90% of the single crystal silicon ingot's body length.

[0070] As used herein, the terms "about," "substantially," "essentially," and "approximately," when used in conjunction with a range of dimensions, concentrations, temperatures, or other physical or chemical properties or characteristics, are meant to cover variations that may exist at the upper and / or lower limits of the range of the property or characteristic, including, for example, variations due to rounding, measurement method, or other statistical variations.

[0071] When introducing elements of the disclosure or embodiments thereof, the terms "a," "an," "the," and "the" are intended to mean that there are one or more elements. The terms "comprising," "including," "containing," and "having" are intended to be inclusive and mean that there may be additional elements other than the listed elements. The use of terms indicating a particular orientation (e.g., "top," "bottom," "side," etc.) is for convenience of description and does not require a particular orientation of any of the described items.

[0072] Because various changes can be made in the above-described structures and methods without departing from the scope of the disclosure, it is intended that all matter contained in the above specification and shown in the accompanying drawings be interpreted as illustrative and not in a limiting sense.

Claims

1. 1. A single crystal silicon ingot having a main body portion, a monocrystalline silicon ingot having a body portion with a peripheral edge, a central axis having an axial length parallel to the peripheral edge, and a radius extending from the central axis to the peripheral edge; the monocrystalline silicon ingot body portion being at least about 1000 millimeters long; the monocrystalline silicon ingot body portion having a diameter of at least about 150 millimeters; and wherein wafers sliced ​​from any portion of the monocrystalline silicon ingot body portion spanning at least 60% of the monocrystalline silicon ingot body portion axial length are characterized by no detectable FPD (flow pattern defects by Secco etching technique) and DSOD (direct surface oxide defect particle count after electrical breakdown), and zero I defects (A defects) by Secco etching technique; further comprising nitrogen in a body nitrogen concentration of at least about 1×10 13 atoms / cm 3 , and further wherein the body nitrogen concentration varies no more than 20% above and no more than 20% below the average body nitrogen concentration over at least 60% of the axial length of the body of the single crystal silicon ingot; and wherein wafers sliced ​​from any portion of the body spanning at least 60% of the axial length of the body of the monocrystalline silicon ingot are characterized by fewer than 20 COPs of 0.026 μm or less in size.

2. 10. The single crystal silicon ingot of claim 1, wherein wafers sliced ​​from any portion of the body spanning at least 80% of the axial length of the body of the single crystal silicon ingot are characterized by fewer than 20 COPs of 0.026 μm size or less.

3. 10. The single crystal silicon ingot of claim 1, further comprising interstitial oxygen at a body oxygen concentration of about 10 PPMA to about 35 PPMA, and further wherein the body oxygen concentration varies no more than 20% above and no more than 20% below the average body oxygen concentration over at least 60% of the body axial length of the single crystal silicon ingot.

4. A single crystal silicon ingot as described in claim 1, further comprising a body nitrogen concentration that varies by not more than 10% above and not more than 10% below the average body nitrogen concentration over at least 60% of the axial length of the body of the single crystal silicon ingot.

5. 2. The single crystal silicon ingot of claim 1, wherein the body has a resistivity that varies no more than 20% above and no more than 20% below the average body resistivity over at least 60% of the body axial length of the single crystal silicon ingot.

6. 1. A single crystal silicon ingot having a main body portion, The body has a peripheral edge, a central axis having an axial length parallel to the peripheral edge, and a radius extending from the central axis to the peripheral edge, the body of the single crystal silicon ingot being at least about 1000 millimeters long, the body of the single crystal silicon ingot having a diameter of at least about 150 millimeters, and the body having a density of at least about 1×10 13 atoms / cm 3 and further wherein the body nitrogen concentration varies by no more than 20% above and no more than 20% below the average body nitrogen concentration over at least 60% of the axial length of the body of the single crystal silicon ingot, said body comprising interstitial oxygen at a body oxygen concentration of from about 10 ppma to about 35 ppma, and further wherein the body oxygen concentration varies by no more than 20% above and no more than 20% below the average body oxygen concentration over at least 60% of the axial length of the body of the single crystal silicon ingot, and further wherein wafers sliced ​​from any portion of the body over at least 60% of the axial length of the body of the single crystal silicon ingot are characterized by fewer than 20 COPs of 0.026 μm size or less.

7. A single crystal silicon ingot as described in claim 6, further comprising a body nitrogen concentration that varies by not more than 10% above and not more than 10% below the average body nitrogen concentration over at least 60% of the axial length of the body portion of the single crystal silicon ingot.

8. 7. The single crystal silicon ingot of claim 6, wherein the body has a resistivity that varies no more than 20% above and no more than 20% below the average body resistivity over at least 60% of the body axial length of the single crystal silicon ingot.

9. 7. The monocrystalline silicon ingot of claim 6, wherein wafers sliced ​​from any portion of the body over at least 70% of the axial length of the body of the monocrystalline silicon ingot are characterized by no detectable FPD (flow pattern defects by Secco etching technique) and DSOD (direct surface oxide defect particle count after electrical breakdown), and zero I defects (A defects) by Secco etching technique.

10. 7. The single crystal silicon ingot of claim 6, wherein wafers sliced ​​from any portion of the body spanning at least 70% of the axial length of the body of the single crystal silicon ingot are characterized by fewer than 20 COPs of 0.026 μm size or less.

11. 1. A single crystal silicon ingot having a main body portion, the body has a peripheral edge, a central axis having an axial length parallel to the peripheral edge, and a radius extending from the central axis to the peripheral edge, the body of the single crystal silicon ingot being at least about 1000 millimeters long, the body of the single crystal silicon ingot having a diameter of at least about 150 millimeters, and the body having a thickness of at least about 1×10 １３ atoms / cm ３ wherein the body nitrogen concentration varies no more than 20% above and no more than 20% below the average body nitrogen concentration over at least 60% of the body axial length of the single crystal silicon ingot, and wherein wafers sliced ​​from any portion of the body over at least 60% of the body axial length of the single crystal silicon ingot are characterized by fewer than 20 COPs of 0.026 μm size or less.

12. 12. The single crystal silicon ingot of claim 11, further comprising interstitial oxygen at a body oxygen concentration of about 10 PPMA to about 35 PPMA, and further wherein the body oxygen concentration varies no more than 20% above and no more than 20% below the average body oxygen concentration over at least 70% of the body axial length of the single crystal silicon ingot.

13. 12. The single crystal silicon ingot of claim 11, wherein the body has a resistivity that varies no more than 20% above and no more than 20% below the average body resistivity over at least 60% of the body axial length of the single crystal silicon ingot.

14. 12. The monocrystalline silicon ingot of claim 11, wherein wafers sliced ​​from any portion of the body spanning at least 70% of the axial length of the body of the monocrystalline silicon ingot are characterized by no detectable FPD (flow pattern defects by Secco etching technique) and DSOD (direct surface oxide defect particle count after electrical breakdown), and zero I defects (A defects) by Secco etching technique.

15. 12. The single crystal silicon ingot of claim 11, wherein wafers sliced ​​from any portion of the body spanning at least 70% of the body axial length of the single crystal silicon ingot are characterized by fewer than 20 COPs of 0.026 μm size or less.

16. 1. A single crystal silicon ingot having a main body portion, the body portion has a peripheral edge, a central axis having an axial length parallel to the peripheral edge, and a radius extending from the central axis to the peripheral edge, the body portion of the single crystal silicon ingot being at least about 1000 millimeters long, and the body portion of the single crystal silicon ingot having a diameter of at least about 150 millimeters; further, the body comprises nitrogen in a body nitrogen concentration of at least about 1×10 13 atoms / cm 3 , and further, the body nitrogen concentration varies no more than 20% above and no more than 20% below the average body nitrogen concentration over at least 60% of the body axial length of the single crystal silicon ingot; 1. A monocrystalline silicon ingot, wherein the body portion has a resistivity of from about 1000 ohm-cm to about 100,000 ohm-cm, and further wherein the resistivity varies no more than 20% above and no more than 20% below an average body resistivity over at least 60% of the axial length of the body portion of the monocrystalline silicon ingot, and further wherein wafers sliced ​​from any portion of the body portion over at least 60% of the axial length of the body portion of the monocrystalline silicon ingot are characterized by fewer than 20 COPs of 0.026 μm size or less.

17. 17. The single crystal silicon ingot of claim 16, further comprising interstitial oxygen at a body oxygen concentration of about 10 PPMA to about 35 PPMA, and further wherein the body oxygen concentration varies no more than 20% above and no more than 20% below the average body oxygen concentration over at least 60% of the body axial length of the single crystal silicon ingot.

18. A single crystal silicon ingot as described in claim 16, further comprising a body nitrogen concentration that varies by no more than 10% above and no more than 10% below the average body nitrogen concentration over at least 60% of the axial length of the body portion of the single crystal silicon ingot.

19. 17. The monocrystalline silicon ingot of claim 16, wherein wafers sliced ​​from any portion of the body spanning at least 60% of the axial length of the body of the monocrystalline silicon ingot are characterized by no detectable FPD (flow pattern defects by Secco etching technique) and DSOD (direct surface oxide defect particle count after electrical breakdown), and zero I defects (A defects) by Secco etching technique.

20. 17. The single crystal silicon ingot of claim 16, wherein wafers sliced ​​from any portion of the body spanning at least 70% of the axial length of the body of the single crystal silicon ingot are characterized by fewer than 20 COPs of 0.026 μm size or less.

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