WO2014166725A1 - Ébauche en silicium, procédé permettant sa fabrication et utilisation de ladite ébauche - Google Patents

Ébauche en silicium, procédé permettant sa fabrication et utilisation de ladite ébauche Download PDF

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Publication number
WO2014166725A1
WO2014166725A1 PCT/EP2014/055880 EP2014055880W WO2014166725A1 WO 2014166725 A1 WO2014166725 A1 WO 2014166725A1 EP 2014055880 W EP2014055880 W EP 2014055880W WO 2014166725 A1 WO2014166725 A1 WO 2014166725A1
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WIPO (PCT)
Prior art keywords
blank
class
silicon
container
dislocations
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PCT/EP2014/055880
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German (de)
English (en)
Inventor
Andreas Voitsch
Matthias Müller
Dietmar Jockel
Christian KUDLA
Uwe Sahr
Christian Lemke
Albrecht Seidl
Bernhard Birkmann
Ute SAUERBREY
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Schott Ag
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Priority claimed from DE102013107193.7A external-priority patent/DE102013107193A1/de
Priority claimed from PCT/EP2014/055453 external-priority patent/WO2014147094A1/fr
Application filed by Schott Ag filed Critical Schott Ag
Publication of WO2014166725A1 publication Critical patent/WO2014166725A1/fr

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    • C—CHEMISTRY; METALLURGY
    • C30—CRYSTAL GROWTH
    • C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
    • C30B33/00—After-treatment of single crystals or homogeneous polycrystalline material with defined structure
    • C30B33/06—Joining of crystals
    • C—CHEMISTRY; METALLURGY
    • C30—CRYSTAL GROWTH
    • C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
    • C30B11/00—Single-crystal growth by normal freezing or freezing under temperature gradient, e.g. Bridgman-Stockbarger method
    • C30B11/006—Controlling or regulating
    • C—CHEMISTRY; METALLURGY
    • C30—CRYSTAL GROWTH
    • C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
    • C30B11/00—Single-crystal growth by normal freezing or freezing under temperature gradient, e.g. Bridgman-Stockbarger method
    • C30B11/14—Single-crystal growth by normal freezing or freezing under temperature gradient, e.g. Bridgman-Stockbarger method characterised by the seed, e.g. its crystallographic orientation
    • C—CHEMISTRY; METALLURGY
    • C30—CRYSTAL GROWTH
    • C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
    • C30B28/00—Production of homogeneous polycrystalline material with defined structure
    • C30B28/04—Production of homogeneous polycrystalline material with defined structure from liquids
    • C30B28/06—Production of homogeneous polycrystalline material with defined structure from liquids by normal freezing or freezing under temperature gradient
    • C—CHEMISTRY; METALLURGY
    • C30—CRYSTAL GROWTH
    • C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
    • C30B29/00—Single crystals or homogeneous polycrystalline material with defined structure characterised by the material or by their shape
    • C30B29/02—Elements
    • C30B29/06—Silicon

Definitions

  • German Patent Application No. 10 2013 103 488.8 “Blank of silicon, method for its production and use thereof", filed on 08.04.2013
  • German Patent Application No. 10 2013 107 193.7 “Blank made of silicon, process for its production and use thereof”, filed on 08.07.2013
  • German Patent Application No. 10 2014 101 222.4 “Method for producing a silicon ingot and a seed layer therefor", filed on 31.01.2014
  • International Patent Application No. PCT / EP2014 / 055453 "Blank made of silicon, method for its production and use thereof” , registered on 18.03.2014.
  • the invention relates generally to a blank made of so-called quasi-monocrystalline silicon, as defined below, as well as to its production and use, and in particular relates to the use of quasi-monocrystalline silicon, which is produced by the method of directional solidification, in the semiconductor industry Components used for processing semiconductors, in particular for use in etching systems, cleaning systems or coating installations, in particular focus rings, support rings, shield rings or showerheads of plasma etching equipment or other semiconductor processing equipment.
  • medium-resistance silicon components used in the semiconductor industry are currently obtained, without exception, from ingots produced by the Czochralski (CZ) process or the float zone (FZ) process.
  • medium-resistance means the range of the specific resistance of greater than 0.2 ⁇ cm to less than 5 ⁇ cm, and the used range of these ingots is cylindrical.
  • the diameter corresponds to that of ingots which are used for the production of semiconductor wafers, which are used for the production of integrated circuits.
  • the diameters of such ingots are typically limited to 150 mm, 200 mm, 300 mm or 450 mm due to the limitations of the CZ method or FZ method. At the maximum, the CZ process has so far reached diameters of up to 550 mm.
  • various components such as focus ring, support ring, shield ring or showerheads with a specific resistance of less than 2 Qcm are used, which are manufactured from monocrystalline silicon from the CZ process, polycrystalline silicon or columnar solidified multicrystalline silicon. Because of the The risk of increased particle generation during plasma etching is disadvantageous for polycrystalline silicon and multicrystalline silicon. These materials were mainly used in the distant past or only when the CZ process was unable to provide correspondingly large semi-finished products for the manufacture of these rings.
  • the segments are made from columnar solidified multicrystalline silicon ingots by cutting them vertically.
  • This approach solves two problems only inadequately.
  • the size limitation of CZ ingots can be overcome and, on the other hand, the grains of multicrystalline silicon solidified in the vertical direction are horizontal in the plasma etching plant, which reduces the length of the grain boundaries and thus reduces the risk of particle generation. Nevertheless, particles generated in the vicinity of the grain boundaries and deposited on the processed wafer lead to the unusability of affected areas on the wafer for integrated circuit fabrication.
  • Monocrystalline semi-finished products used in the semiconductor industry for processing semiconductors are always specified only because of this limitation, that they can be cut out of the cylindrical CZ silicon ingots from which the semiconductor wafers mentioned above are also produced by default.
  • the cutting takes place in the radial direction, resulting in discs whose end faces correspond crystallographically the growth direction of the crystal (typically (100) or (111)).
  • the maximum possible semifinished diameter corresponds to the ingot diameter.
  • the quality requirements imposed on the above-mentioned components have so far always involved an intrinsic material quality requirement with respect to the content of metallic impurities, nitrogen, oxygen, carbon and electrical resistivity.
  • another type of doping p-type or n-type
  • a certain crystallographic orientation in connection with the format round or square
  • a certain purity eg 7N
  • the invention aims to provide a quasi-monocrystalline silicon crystal material, as defined below, for quasi-monocrystalline silicon semiconductor devices for use in semiconductor processing equipment, which is substantially less expensive to produce than monocrystalline material originating from the CZ and FZ processes, respectively is and that meets only those technical requirements, which are actually mandatory for the application.
  • this term is intended to denote a silicon material which is directionally solidified in a crucible or the like, wherein the bottom of the crucible is integrally formed with one or multi-piece monocrystalline or quasi-monocrystalline seed layer, which originates in particular from a CZ or FZ process is designed, the seed layer are melted and this crystal growth or the directional solidification of the silicon melt their crystallographic orientation on freshly crystallized material
  • the seed plate (s) of the seed layer may also be made of silicon material that already originates from a process as shown in the previous sentence and thus already consists of quasi-monocrystalline material
  • quasi-monocrystalline silicon material in the sense of the present invention consists of a single grain, which may, however, contain dislocation clusters and small-angle grain boundaries with a certain proportion, wherein the grain contains twins contained therein as well Foreign grains, if present, should completely enclose.
  • quadsi-monocrystalline also includes synonymous designations, such as, for example, mono-like, near-monocrystalline silicone, M-grades, U-grades and others, which, however, are specific to the manufacturer only for solar wafer material in this field are known.
  • Examples of functional components in the context of the present application are in particular focus rings, support rings, shield rings or showerheads of plasma etching systems or other semiconductor processing plants.
  • blade refers to a blank or a semi-finished product which is produced from a crude crystal produced after a cultivation in order to be able to evaluate the material quality of this blank on its surface and / or in its interior
  • This blank is a round or square disk or ring of thickness greater than 0.5mm and less than 30mm
  • a blank rated as usable for its intended use undergoes further processing after its evaluation to adjust the final geometry and surface quality of the component
  • the quasi-monocrystalline silicon material according to the invention for medium-resistance functional components is only as good as really required and can therefore be produced more cost-effectively than conventionally, In other words, cost advantages can be realized according to the invention in that only those essential for a satisfactory functional component are absolutely necessary properties are complied with.
  • planar determination of carrier lifetime (or physical quantity correlating therewith) with silicon and other semiconductor materials such as germanium, gallium arsenide and other so-called compound semiconductors is a very simple, fast and nondestructive method to improve tool life
  • the measuring technique actually developed for evaluating the electrical quality of solar silicon or for determining the achievable efficiency of solar cells, can be used with the method described here for evaluating the structural quality or chemical stability of quasi-monocrystalline silicon.
  • the surface of the workpiece to be examined is investigated with the following methods, for example: ⁇ -PCD (mierowa ve-detected Photo-Conductance Decay Measurement), MWT (Microwave Detected Photoconductivity), PL (Photoluminescence), or similar scanning or imaging measurement techniques.
  • ⁇ -PCD mierowa ve-detected Photo-Conductance Decay Measurement
  • MWT Microwave Detected Photoconductivity
  • PL Photoluminescence
  • All these measurement techniques determine a value which is proportional to the charge carrier lifetime in the area of the surface.
  • the spatial resolution of the respective measurement techniques is different; It can range from a few ⁇ to a few mm.
  • the only condition for the material is that no other recombination mechanisms are allowed to superimpose the recombination on the dislocation lines. That is, massive contamination, e.g. with uniformly distributed in volume metallic impurities prevents this type of detection of Versatzungsclustem.
  • transition metals such as Fe, Cr, Co, Ni, Ti and the like should not exceed a concentration of 0.1 ppm.
  • a known grain-based method of directional solidification of silicon for the production of quasi-monocrystalline Si ingots for the photovoltaic industry is modified according to the present invention and supplemented by an allocation and evaluation process such that defines a volume fraction of the resulting ingot and is evaluated so that it can be used for the production of medium-resistance monocrystalline functional components for use in semiconductor processing plants.
  • the monocrystalline volume fraction defined and usable for these groups of components has a specific electrical resistance greater than 0.2 ⁇ cm and less than 5 ⁇ cm.
  • the allotment and evaluation method can also be used for differently manufactured silicon crystal material.
  • Ingotkerns or a horizontally separated from this slice which is the same thickness or thicker than the subsequent blank;
  • test surface with regard to content, distribution and / or quality relevance of at least one of the following: foreign grains, twin boundaries or clusters of dislocations or small-angle grain boundaries; and
  • the crucible bottom of a crucible is covered with one or more mono- or quasi-monocrystalline silicon nuclei.
  • the seed layer can be formed in one piece and completely cover the bottom of the crucible or container.
  • the seed layer can also be formed from a plurality of seed plates, which are arranged directly adjacent to each other (forming as narrow gaps as possible between them) on the bottom of the crucible in order to completely cover it.
  • a method for producing the aforementioned seed layer from a plurality of seed plates can in principle also be produced by a Czochralski method or by a floating zone method.
  • the plurality of germination plates is arranged on a planar seedbed, which is flat by a sawing process or even ground flat.
  • the abutting surfaces or additionally at least one further surface are ground.
  • the abutment surfaces of adjacent germination plates are ground at right angles so that, when using three or more germ plates, the width of the resulting column (viewed from above) is as small as possible. It is of equal importance that even during the melting of the germ plates no column arise. This means that even with a lateral (horizontal) view of the germ plate, the ground abutment surfaces have a right angle.
  • the ground surfaces (in particular the edge surfaces) have a roughness of Rz according to DIN 4762 of less than ⁇ , more preferably less than ⁇ and particularly preferably less than 5 ⁇ and their angularity is considered both vertically and horizontally so good that gaps formed during the laying out of the germination plates and during the melting of the germination plates between immediately adjacent germinal plates are smaller than 1 mm, more preferably less than 0.1 mm, and more preferably less than 0.01 mm, at each point.
  • the silicon material according to the invention as a whole has no twin grains (shock twins) which are formed on germ buds.
  • the crucible is then further filled with silicon raw material with the addition of substantially more dopant than required for the production of solar cells, ie, for example for the above-mentioned range of resistivity from 0.001 to 0.2 and the use of one or more already suitably doped nuclei a large amount of dopant is added, resulting in an initial concentration in the melt of about 1.2 * 10 20 atoms / cm 3 to 1.0 * 10 17 atoms / cm 3 of the dopant boron (B) or about 7 , 4 * 10 19 atoms / cm 3 to 3.1 * 10 16 atoms / cm 3 of the dopant phosphorus (P).
  • the filled crucible is placed in a technically modified system for directional solidification of silicon, in particular a VGF plant. This is followed by melting of the raw materials, melting of the germ or germs without keying the phase boundary, followed by a directional solidification of the liquid silicon to form an ingot. After cooling, removal and demolding of the ingot, the cutting of the ingot soil from the ingot can be followed for preferential reuse as seed material.
  • the quality of the cut makes it possible, if necessary, to visually recognize multicrystalline edge regions on both opposite cut surfaces and, if appropriate, separate them from the germplate.
  • the cutting off of the cladding layer from the ingot can take place in a predetermined thickness or a thickness which is visually recognizable as non-monocrystalline at the cut surface.
  • the remaining ingot can be cut into slices corresponding to the desired thickness in order to produce blanks for medium-resistance components used in semiconductor processing plants.
  • a surface treatment of the wafer surfaces may be carried out to better ensure the visual distinctness of multicrystalline and quasi-monocrystalline regions of the processed surfaces and to mark the quasi-monocrystalline surface region.
  • the marked quasi-monocrystalline surface region (test surface) on the disk or on the ingot can be checked for the presence and the location of detected foreign grains or detected twin boundaries.
  • Examination of a selected quasi-monocrystalline surface area (test surface) of the disk can be made by one of three preferred electrical methods for quantifying the content of this test surface to clusters of dislocations or small angle grain boundaries.
  • it is detected whether and at which location on the test surface pixels with clusters of dislocations or small-angle grain boundaries are present. Subsequently, a determination is made of the percentage of clusters of dislocations or small-angle grain boundaries of adhered pixels on the test surface, as well as a specification of one or more new test surfaces of the disk, in terms of their content with respect to the percentage of clusters of dislocations or small angle grain boundaries
  • Quasi monocrystalline material purposes of this invention contains an average concentration of isolated dislocations of between 10 2 cm “2 to 10 6 cm” 2, typically between 10 3 cm “2 and 10 5 cm” 2.
  • the quasi-monocrystalline silicon material of the present invention differs from the conventional monocrystalline silicon produced, for example, by the Czochralski or floating zone method with the use as a semiconductor wafer for manufacturing microelectronic devices.
  • VGF process Silicon material produced by this process is referred to as VGF mono-silicon. Show it:
  • Figure 1 is a vertical section through a generation 4 Si ingot made by a crystallization process according to the present invention, with exemplary distribution of the material in monocrystalline and multicrystalline and a possible fragmentation of, for example, horizontally cut out slices to obtain blanks for functional components. eg the use of the specified in the figure medium-resistance components for the semiconductor industry
  • Figure 2 is another vertical section through a Generation 5 Si ingot made by a crystallisation process according to the present invention, with an exemplary distribution of the material in monocrystalline and multicrystalline and a possible division of, for example, horizontally excisable slices to obtain blanks for functional components , eg the use of the specified in the figure medium-resistance components for the semiconductor industry
  • Fig. 3 is a photograph of one of such ingot in the middle
  • FIGS. 4a and 4b show PL (left) and ⁇ PCD images (right) of a rough-cut wafer surface of monocrystalline dislocation-free silicon material produced by a CZ process (annular structures are visible);
  • Fig. 4c and 4d corresponding PL (left) and ⁇ PCD images (right) of a sawn
  • Figures 6a and 6b show respective PL and ⁇ PCD images of a rough-cut wafer surface of monocrystalline silicon material originating from a lid-near region of an ingot made by a VGF process according to the present invention, wherein clusters of higher angular grain or small angle grain boundaries Area fraction are visible as in Figures 5 a and 5b;
  • thermocouple off-center at the bottom of a thermocouple
  • thermocouple off-center on the underside of a
  • Crucible standing plate on which a crucible stands for an exemplary method according to the present invention using a seed layer formed of a plurality of seed plates whose edges are ground and worked, and in which the gaps between individual seeds are not drawn to scale;
  • FIG 9 shows an exemplary temperature profile in a method according to the present invention.
  • a ready-to-use crucible inside coated by the crucible manufacturer or a crucible coated by the user himself eg a quartz or fused silica crucible
  • a graphite crucible or a Si 3 N 4 crucible can be used.
  • the crucible base depends on the size of the medium-resistance components to be produced therein for the semiconductor industry. It can be used for square G4 (720 mm x 720 mm), G5 (880 mm x 880 mm)
  • G6 (1050 mm x 1050 mm) or even larger crucibles up to 3000 mm x 3000 mm, round crucibles with a diameter greater than 450 mm or rectangular crucibles with a minimum base edge length of 450 mm or a maximum base edge length of 3000 mm are currently in use.
  • a crucible height of less than 350 mm is just as meaningless as a crucible height (possibly including crucible attachment) of more than 800 mm.
  • Total crucible heights of 450 mm, 550 mm, 650 mm and 780 mm or sizes in between have proved to be very practical.
  • FIG. 8 a shows a schematic cross section through a crucible 2 of a plant 1 for the production of silicon ingots.
  • the container 2 usually a quartz crucible, has a bottom 3 which is vertical extends to the longitudinal direction 5, and at least one side wall 4, which extends in the longitudinal direction 5 and may be formed circumferentially, in particular of four rectangular surfaces may be formed, which specify a total rectangular or preferably square base of the container 2.
  • the bottom 3 may according to further embodiments also have a different cross section, for example, an octagonal, circular or oval cross-section.
  • a seed layer 10 made of silicon is arranged on the bottom 3 of the container 2 as a seed template, which is formed in one piece and completely covers the bottom 3.
  • the seed layer 10 preferably has the same material properties as the silicon ingot to be formed.
  • a planar seed pad 13 is provided on the bottom 3, of which at least the top of a sufficient planarity having. This corresponds at least to the quality of a standard saw cut, the top can also be ground flat. In this way, an orientation of the seed layer is achieved exactly perpendicular to the perpendicular bisector 5 on the bottom 3.
  • the container 2 is shown in FIG. 8a on a crucible setting plate 14 made of a good heat-conducting material, preferably of graphite. This allows, as well as the underlying cooling plate 15, heat of the underlying meandering bottom heater 17 very well to heat the bottom 3.
  • the crucible mounting plate 14 is designed for an exactly vertical arrangement of the container 2.
  • thermocouple 16 having a protective tube is provided off-center in the cooling plate 15 to monitor the temperature during directional solidification. An elaborate and disturbing monitoring of the temperature by means of a measuring tube immersed in the Si melt can thus not be dispensed with according to the invention. More specifically, the thermocouple 15 is arranged at a radial distance from the center of the bottom 3, which corresponds to half the diameter of the container 2, if this is round, or half of an edge length of the container 2, if this has a square base , in particular with a tolerance of + 30mm and -100mm. As explained in more detail below with reference to FIG. 9, in the method, the temperature signal of the thermocouple 15 is controlled.
  • FIG. 8b shows, in a schematic cross-section through a crucible, an alternative embodiment for the production of silicon ingots, in which a seed layer is used, which is formed from a plurality of seed plates 11 whose edges or joints form as narrow gaps as possible 12 directly abut each other and completely cover the bottom 3 of the container 2.
  • the germ plates 11 do not necessarily have a uniform cross section, in particular a rectangular or square cross section, so that the bottom 3 can be completely covered.
  • the Germ plate 11 may be arranged in a mirror-symmetrical arrangement with respect to a perpendicular to the bottom 3 of the container 2 extending center plane (not shown).
  • the shape of the germ plates 11 may also be suitably adapted to the shape of the bottom 3 in other ways.
  • the thicknesses of the seed plates 11 are not necessarily the same, so that a substantially planar surface of the seed layer is formed, however, the bottom and the edges are processed so that all gaps between the germs at each point are extremely low.
  • a planar seed pad 13 is provided in this case on the bottom 3, of which at least the upper side has sufficient planarity having. This corresponds at least to the quality of a standard saw cut, the top can also be ground flat.
  • the germ plates 11 can thus be arranged with exactly uniform orientation on the bottom 3 of the container 2.
  • the surfaces of the germ plates 11 are preferably completely or partially ground.
  • the roughness Rz in accordance with DIN 4762 should be less than ⁇ , more preferably less than ⁇ and more preferably less than 5 ⁇ .
  • the distance between the individual seed plates is preferably small, regardless of whether this is caused by tilting of the seed plates or by non-plane-parallel edges. This distance is less than 1 mm, more preferably less than 0.1 mm and more preferably less than 0.01 mm, so that resulting gaps 12 between immediately adjacent seed plates 11 at any point are of this order of magnitude.
  • a silicon melt 6 is provided in the container 2.
  • lumped silicon can be introduced into the container 2 and melted, for example as disclosed in the applicant's EP 2028292 A2.
  • the silicon melt 6 can also initially be provided in another container (not shown) and transferred into the container 2 in liquid form. The process is carried out in such a way that the seed layer 10, 12, which acts as a seed receiver, is merely melted on, that is to say only partially but not completely melted. Subsequently, the silicon melt 6 is directionally solidified in a conventional manner.
  • the silicon melt 6 to a silicon ingot After solidification of the silicon melt 6 to a silicon ingot it is removed from the container 2 and further processed. For this purpose, this is suitably trimmed, for example by cuts along the longitudinal direction 5 of the silicon ingot. Furthermore, a bottom and a cap of the silicon ingot are removed by cuts perpendicular to the longitudinal direction 5 of the silicon ingot. Depending on the process conditions, a portion of the machined core of the silicon ingot on the periphery may not have the desired material properties. As a germ, a surface germ filling almost the entire inner surface of the crucible is particularly useful. This can be obtained by a bottom cut from a previous ingot.
  • the germ or the germ layer should not be unnecessarily thick, but also not too thin, so that there is no danger of it completely melting in the later germination phase. Seed thicknesses of 15 mm, 30 mm, 45 mm, 50 mm, 70 mm, 80 mm or intermediate sizes have proven useful, with 40 mm or 45 mm being preferred.
  • the orientation of the seeds is rather of minor importance.
  • the (100) orientation of the microorganisms desired in photovoltaics is not mandatory for the production of medium-resistance components for functional components in semiconductor processing plants, it is the preferred microbial orientation for breeding-related considerations. Depending on the objective, however, it can also be bred based on (111) -, (HO) -, or still differently oriented germs.
  • Germs can be worked out quadratically from parts of a surface germ, a round crystal produced according to a CZ method, in the above seed thickness. Germs may also be obtained from longitudinal sections of the desired thickness stated above from a crystal made by a CZ method. Germs can also be cut out vertically from a previously ingame-based directionally solidified ingot as vertical boards or ingots in the desired thickness mentioned above.
  • the nucleus may be undoped, lightly doped corresponding to a resistivity greater than 5 Qcm, heavily doped corresponding to a specific resistance less than 0.2 Qcm, or already suitable for the target resistance of greater than 0.2 Qcm and less than 5 Qcm. Knowing the seed doping and the intended degree of reflow of the seed, the addition amount of dopant to the pure Si raw material is selected to achieve the target resistivity within the desired range of greater than 0.2 ⁇ cm and less than 5 ⁇ cm.
  • the remaining crucible volume is still filled with Si raw material (at least in the purity of solar grade) and dopant.
  • Si raw material at least in the purity of solar grade
  • dopant dopant.
  • the resulting total height is used as possible.
  • a filling height of less than 250 mm is just as meaningless as a filling height (possibly including crucible attachment) of more than 800 mm.
  • Total crucible heights of 350 mm, 450 mm, 550 mm, 650 mm and 780 mm or intermediate sizes have proven feasible.
  • the concentration of the dopant eg, boron
  • the filled crucible is then placed in a Bridgman-type crystal growing facility or in a VGF facility.
  • the latter is equipped with different heater configurations depending on the system type. Commonly used are systems with only ceiling heaters, systems with ceiling and floor heaters, systems only with jacket heaters, systems with ceiling and jacket heaters or systems with ceiling, jacket and bottom heaters.
  • the raw material is melted from above. By a suitable temperature control of the heater with simultaneous cooling of the seed layer is ensured both that the added raw material is completely melted, the germ or the germs are not completely melted, but necessarily melted.
  • each individual area fraction of the seed layer is defined with a size of about 1 cm 2 .
  • Each of these individual surface portions should be melted above a crucible bottom up to a certain height.
  • This height coordinate, up to which the melting of each area fraction takes place, is in the range of 20% to 90% of the thickness of the inserted seed layer.
  • areas are found that are preferred. For example, with a seed thickness of 40 mm, an area of the height coordinate of 35% to 75% of the original seed thickness or, with a seed thickness of 45 mm, a range of the height coordinate of 30%> to 80%> of the original seed thickness is preferred.
  • the measurement of the temperature is not made in the center of symmetry on the underside of the plate, which is referred to as a crucible mounting plate.
  • the measurement of the temperature is made by placing a thermocouple in the graphite crucible setting plate at a radial distance from the center of the crucible bottom which is half the edge length or diameter of the crucible.
  • the location of measurement may be within a ring defined by a positive Tolerance deviation of 30mm and a negative tolerance deviation of 100mm radius range, which corresponds to a nominal half of the crucible edge length.
  • the measurement thus takes place, as shown in FIGS. 8a and 8b, at a point further out which is close to the edge of the crucible and provides representative and accurate measurement results by this layer in order to prevent complete melting of the seed layer near the crucible wall.
  • This danger is due to the fact that the system tends to form heat flows in the direction of the center by means of germ cooling, so that the temperature in the seed layer center is colder than at the edge of the seed layer.
  • Important parameters are cooling capacity and geometry of the cooling arrangement.
  • the cooling capacity must be adjusted to the heater temperatures so that a flat phase boundary is established.
  • the geometry or rather the cooled surface must be about the Area of the crucible.
  • the position of the temperature measuring point must therefore be chosen so that it detects the edge area under the germ, but is not distorted by the cooling.
  • the melting of the seed layer takes place without mechanically touching the position of the phase boundary.
  • the procedure is such that the temperature of the underside of the crucible mounting plate is measured at a defined distance from the center of symmetry of the crucible bottom, specifically at the periphery of the crucible mounting plate of good heat-conducting graphite, by means of a pyrometer or thermocouple.
  • 9 shows a typical time profile of the temperature profile, as measured by the thermocouple 16 shown in FIGS. 8a and 8b.
  • a bottom heater is used (see reference numeral 17 in Figures 8a and 8b), which operates from the beginning of the heating of the silicon until the melting temperature of the silicon is reached.
  • the shutdown of the floor heater takes place on reaching the melting temperature of the silicon at the time ti in FIG. 9 and there is a simultaneous connection of a floor cooler with a cooling capacity of a maximum of lW / cm 2 , with a maximum of 0.65W / cm 2 are preferred.
  • a floor cooler with a cooling capacity of a maximum of lW / cm 2 , with a maximum of 0.65W / cm 2 are preferred.
  • the temperature measured at the location of the thermocouple increases even after the time ti until it finally falls.
  • This temperature drop is shown in FIG. 9.
  • further heating of the container by means of a not shown in Figures 8a and 8b lid and jacket heater, which are designed in the usual way. Due to the gradual melting of the silicon material in the container, the temperature drop according to FIG. 9 is gradually decelerated.
  • the temperature eventually passes through a minium and then begins to rise again due to the heating by the lid and jacket heater.
  • the crystallization phase is shown in FIG. 9 according to the invention at a time t 2 initiated by increasing the cooling capacity of a maximum of at most 1 W / cm 2, preferably of at most 0,65W / cm 2 to a minimum of 2W / cm 2, preferably minimally l, 5W / cm 2 as soon as the temperature measured on the thermocouple at the crucible mounting plate has risen again by a predetermined temperature difference ( ⁇ ) of preferably 5 K to 25 K after passing through the bottom heater cut-off and cooling power switching minimum (as described above) above this minimum ,
  • ⁇ predetermined temperature difference
  • it is thus preferably controlled to the temperature signal of the thermocouple located in the crucible mounting plate, so that it is not necessary to immerse a temperature sensor in the Si melt, which is conventionally complicated and causes a great variety of defects in the Si ingot.
  • thermocouple as an example of a more common temperature sensor, may also be located elsewhere near the crucible of the apparatus of Figures 8a and 8b so long as there is sufficient correlation between the temperature signal of such a temperature sensor and the actual temperature prevailing in the crucible.
  • Correlation can for example be determined in advance on the basis of calibration or reference measurements and stored in the memory of a control device, for example of a processor, in order to achieve a suitable temperature control.
  • a control device for example of a processor
  • it is advantageous to make the phase boundary solid-liquid convex in the crystallization phase in order to curb the propagation of crystal grains of other orientation, which always occur due to foreign nucleation on the crucible wall in the direction of Ingotmitte.
  • the convexity of the phase boundary must not be too large in order not to excite the dislocation formation caused by thermal stress.
  • the finished cultured ingot After the finished cultured ingot has been cooled to a temperature close to room temperature according to a standard program, it is taken out of the crystal growing plant together with the crucible and demoulded. If one intersects such an ingot now parallel to an edge extending and extending through the center of symmetry of the ingot fictitious on, we obtain a fictitious cut surface, which illustrates where the unmelted seed layer is located and where multi and monocrystalline regions are present as are suitable for the production of medium-resistance components for systems for semiconductor processing with the sizes or dimensions exemplified in Figures 1 and 2.
  • Figures 1 and 2 show how such an ingot is used e.g. can be cut open horizontally to obtain blanks for various end products. A photograph of such a horizontal section is shown in FIG. 3, which will be explained in more detail below.
  • FIG. 1 Such a basic cross-section of a generation 4 ingot (630 mm ⁇ 630 mm base and height 430 mm) is shown in FIG. 1 and a generation 5 ingot (780 mm ⁇ 780 mm base and height 430 mm) is shown in FIG. 2.
  • the four side surfaces can be cut to a predefined thickness. Which thickness is necessary results from experience, ie from previous processes, or from whether the bottom of the crucible was designed completely or with the omission of a narrow edge area with germs.
  • the soil layer to be sawn off after this step is slightly smaller in this procedure than in the procedure according to a). Thus, in the case of reuse of the soil layer as a germ in the subsequent process of this does not fill the crucible bottom to 100%.
  • horizontal slices are cut out of the remaining ingot volume, which have a thickness which still has an allowance for the further processing steps for the production of, for example, medium-resistance components for semiconductor processing equipment or other blanks.
  • the determination of the specific resistance is expediently carried out in two steps: First, the resistance at the inner cut surface of a side surface along a vertical line is determined pointwise. This is to check at which height coordinates the ingot reaches the required resistivity for one or more types of final products. After cutting out horizontal slices from the ingot, specimens cut adjacent to the area selected for the final product can additionally determine the resistivity in higher accuracy in the form of a surface scan across the specimen. However, it is also possible to perform a planar raster measurement of the specific resistance over the entire interesting surface area of the slice, in order to specify the mean value and also the fluctuation range of the measured values within the slice. Similar to the latter case, this is also directly on Blank to be delivered possible. In most cases, this effort is not required.
  • the methods or devices that can be used for the measurement differ only in what range of resistance is expected and whether it is necessary to record the measured values over a wide area.
  • the measurement may be e.g. offline and punctiform or scanning in the range up to 30 ⁇ done with an eddy current measuring method (eg with the RT 100 from the company. S emilab / Hungary) or pointwise or raster with a 4-tip measuring method done (eg the Automatic Four-Point Sample, Model 280SI Series from Four Dimensions Inc./ Hayward, CA, USA for measuring previously defined suitable sample geometries or the 4PP system for ingots of the same company).
  • an eddy current measuring method eg with the RT 100 from the company. S emilab / Hungary
  • 4-tip measuring method done eg the Automatic Four-Point Sample, Model 280SI Series from Four Dimensions Inc./ Hayward, CA, USA for measuring previously defined suitable sample geometries or the 4PP system for ingots of the same company.
  • FIG. 3 shows a photograph of the plan view of a slice cut from the ingot in the middle ingot height. Although in this case the side surfaces have already been separated, a multicrystalline region (B) can be seen, which has grown in from the edge in the direction of the monocrystalline center (A) and is separated in this image by a hand-drawn line from the quasi-monocrystalline material region.
  • the monocrystalline center (A) three round blanks of different diameters are exemplarily drawn.
  • the sample shown in FIG. 3 is representative of different sample geometries and sample positions. This can be for the o.g. Resistance measurements, transmission measurements, FTIR measurements or for contamination determination (AAS, GDMS, ICP-MS, ).
  • the quasi-monocrystalline material region must be investigated in more detail whether it is not the position and above all local strong concentrations of clusters of dislocations and small-angle grain boundaries, foreign grains or twin boundaries rendering certain areas unusable for the intended use. As a result of these tests described below, the size and position of the blanks obtainable from a disk must be finally determined.
  • Such disks - especially their quasi-monocrystalline region - are now evaluated for content, distribution and quality relevance of a first group of crystal defects known as “dislocation clusters”, “dislocation agglomerations”, “small angle grain boundary clusters” or the like is referred to in the following text as “clusters of dislocations or small angle grain boundaries” or simply as dislocation clusters or clusters.
  • VGF-mono-silicon material which is produced as a result of the directional solidification containing an average concentration of isolated dislocations between greater than 1 x 10 2 cm "2 and less than 1 x 10 cm", typically between 10 cm “and 10 cm”
  • VGF mono-silicon differs from the ideal monocrystalline silicon, manufactured for example with the Czochralski or the floating zone method. Silicon produced by the latter method is usually below 10 2 cm -2 and is typically even wholly or nearly free of dislocations
  • monocrystalline silicon from the Czochralski or the floating zone method may also have very high concentrations of dislocation multiplication offsets.
  • the local orientation of the crystal lattice is not macroscopically affected by the presence of the dislocations.
  • the optical appearance of a machined, ground or polished workpiece surface of quasi-monocrystalline silicon workpieces of different dislocation concentration does not differ. Transmission and reflection behavior are identical.
  • dislocation clusters may also extend to small angle grain boundaries. The latter then enclose crystal regions which, compared to the rest of the matrix of the workpiece, can have a significant tilt of a few arc minutes to, in the extreme case, a few degrees, so-called subgrains.
  • dislocation clusters of this type have many such small and minute sub-grains tilted adjacent to each other, with distances and dimensions ranging from ⁇ to cm.
  • Areas of greater tilt are comparable in appearance to foreign grains and can be visually recognized with unaided eye and under good lighting on the mechanically machined surface, if they are sufficiently large. They represent a second group of crystal defects in VGF mono-silicon. Also the third group of crystal defects in VGF mono-silicon, the twin boundaries, are visually recognizable like the second group.
  • the angle of incidence of the illumination to the surface to be assessed covers the angle range from 10 ° to 75 ° and the light source rotates azimuthally in 10 ° increments over 360 °.
  • the viewing direction of the area to be assessed by the appraiser must be opposite the Einstrahraum and the same Einstrahlwinkel Scheme from 10 ° to 75 ° sweep.
  • an azimuthal viewing angle range of -90 ° to + 90 ° to the viewing direction must be covered.
  • Sanded surfaces are suitable for this, better are sandblasted surfaces. However, it has been found that a roughly ground surface quality typically achieved by wire-cutting lapping or on a band saw is also sufficient for the evaluation.
  • Class FK1 Silicon material with discrete dislocations in the range of greater than 1 x 10 2 cm “2 to less than 1 x 10 6 cm “ 2 in its quasi-monocrystalline, dislocation cluster or small angle grain boundary-free volume which has no foreign grains on a cut surface through the material.
  • Test surface Visibility in the test surface.
  • the test surface is either the disk surface or the blank surface, which points to final components of small thickness in the direction of stress or chemical attack (functional surface).
  • a small thickness means that the blank or the slice cut out of the ingot has a thickness of at least 5 times less than its largest surface dimension.
  • Class FK2 silicon material with discrete dislocations in the range of greater than 1 x 10 2 cm “2 to less than 1 x 10 6 cm “ 2 in its quasi-monocrystalline, dislocation cluster or small angle grain boundary-free volume which has a maximum of 1 foreign particle per dm on a cut surface through the material 2 in a size smaller than 50 mm 2 has.
  • Test surface is either the disk surface or the blank surface which is at the
  • Final component in the direction of the load or the chemical attack shows (functional area).
  • the direction of loading or chemical attack present at the final component means the side of the component which is exposed to stress such as e.g. the area that is near a plasma or exposed to reactive gases.
  • the quantity "number of foreign particles per dm 2 means the area density of foreign grains on the evaluated surface.
  • Class FK3 silicon material with discrete dislocations in the range of greater than 1 x 10 2 cm 2 to less than 1 x 10 6 cm 2 in its quasi-monocrystalline dislocation cluster or small-angle grain boundary-free volume, which has a maximum of 2 foreign particles per dm 2 in a size smaller than 50 mm 2 on a sectional surface through the material,
  • Determination criterion Visibility in the test surface.
  • the test surface is either the disk surface or in one of the evaluation accessible
  • the blank surface accessible for evaluation is the outer surface of a blank, through which suitable measuring methods give information about a surface quality representative of the volume or the surface quality that can be achieved after final processing.
  • Class FK4 silicon material with discrete dislocations in the range of greater than 1 x 10 2 cm 2 to less than 1 x 10 6 cm 2 in its quasi-monocrystalline, dislocation cluster or small angle grain boundary-free volume which has a maximum of 5 foreign grains per dm 2 in a size smaller than 50 mm 2 has.
  • Determination criterion Visibility in the test surface.
  • the test surface is either the disk surface or blank surface accessible to the evaluation.
  • Class FK5 Silicon material with discrete dislocations in the range of greater than 1 x 10 2 cm “2 to less than 1 x 10 6 cm “ 2 in its quasi-monocrystalline, dislocation cluster or small-angle grain boundary-free volume, on a sectional surface through the material foreign matter but without numerical limitation having a size of less than 50 mm 2 each.
  • Determination criterion Visibility in the test surface.
  • the test surface is either the disk surface or blank surface accessible to the evaluation.
  • twin boundary is defined as a coherent grain boundary, preferably as a ⁇ 3 grain boundary.
  • Class ZI Silicon material with discrete dislocations in the range of greater than 1 x 10 2 cm 2 to smaller l x 10 6 cm 2 in its quasi-monocrystalline, dislocation cluster or small angle grain boundary-free volume which has no twin boundaries on a cut surface through the material
  • Class Z2 silicon material with individual dislocations in the range of greater than 1 x 10 2 cm "2 to less than lx l0 6 cm" 2 in its quasi monocrystalline veröscluster- or small-angle grain boundaries free volume which to a sectional area through the material of a maximum of 4 pieces of twin boundaries of a total length of maximum. 0.5 m per dm 2 .
  • Class Z3 silicon material with individual dislocations in the range of greater than 1 x 10 2 cm "2 to less than lx l0 6 cm" 2 in its quasi monocrystalline ver arrangementscluster- or small-angle grain boundaries free volume which to a sectional area through the material of a maximum of 10 twin boundaries having a Total length of
  • Class Z4 Silicon material with discrete dislocations in the range of greater than 1 x 10 2 cm 2 to smaller l x 10 6 cm 2 in its quasi-monocrystalline, dislocation cluster or small-angle grain boundary-free volume, which is intersected by the
  • Material has a maximum of 100 pieces of twin borders with a total length of 14 m per dm 2 .
  • Class Z5 Single-dislocation silicon material in the range of greater than 1 x 10 2 cm 2 to smaller l x 10 6 cm 2 in its quasi-monocrystalline, dislocation cluster or small angle grain boundary-free volume which has more than 100 twinned boundaries per section through the material dm 2 has.
  • the surface of the workpiece to be examined is examined with the following methods, for example: ⁇ -PCD (microwave ve-detected), MWC (Microwave Detected Photoconductivity), PL (Photoluminescence), or similar scanning or imaging techniques.
  • ⁇ -PCD microwave ve-detected
  • MWC Microwave Detected Photoconductivity
  • PL Photoluminescence
  • scanning or imaging techniques there are already manufacturers of commercial measuring instruments, such as the company Semilab / Hungary, the company Freiberg Instruments / Germany or the company Hennecke / Germany.
  • All these measurement techniques determine a value which is proportional to the charge carrier lifetime in the area of the surface.
  • the spatial resolution of the respective measurement techniques is different; It can range from a few ⁇ to a few mm.
  • the only condition for the material is that no other recombination mechanisms are allowed to superimpose the recombination on the dislocation lines. That is, massive contamination, e.g. with uniformly distributed in volume metallic impurities prevents this type of detection of dislocation clusters.
  • transition metals such as Fe, Cr, Co, Ni, Ti and the like should not exceed a concentration of 0.1 ppm.
  • the evaluation or classification of the examination-accessible side of a cuboidal, round, annular or other shaped blank takes place according to the area fraction of dislocation clusters found.
  • the determination of this area proportion takes place by means of image evaluation of the areal images (raster measurements or camera shots, depending on the measuring technique) of individual sides of the workpiece (under certain circumstances only the last frozen page).
  • the measured values for the carrier lifetime in the region of the dislocation clusters are clearly below the mean of the measured values outside the dislocation clusters.
  • the absolute values and the resolution depend on the selected measuring technique, the type of mechanical surface treatment, the electrical conductivity of the material and the content of metallic impurities, the areas of dislocation clusters are always distinguished by significantly lower measured values from the unloaded areas. It is then possible, for example by means of the definition of a threshold value for the charge carrier lifetime or a measured variable correlated with this charge carrier lifetime, to separate or quantify area proportions with dislocation clusters from those without dislocation clusters.
  • FIGS. 4a and 4c each show PL images
  • FIGS. 4b and 4d respectively show the ⁇ -PCD mapping of a respective rough-cut wafer surface of monocrystalline-dislocation-free CZ material (FIGS. 4a and 4b) and VGF mono-displacement-related Silicon ( Figures 4c and 4d).
  • there are no dislocation clusters (defect area fraction 0%).
  • the materials are very similar.
  • the color gradient in the ⁇ PCD images is due to thickness variations of the wire-trimmed wafer and has nothing to do with quality differences. These pictures are merely intended to demonstrate that the defect type individual dislocation can not be determined with the named measuring methods and this is also not necessary for the quality assessment according to the present invention.
  • FIG. 5a shows a PL recording
  • FIG. 5b shows a ⁇ -PCD mapping of a rough-cut surface of VGF monosilicon material in the geometric shape of a wafer.
  • the sample contains dislocation clusters, which can be evaluated by means of image evaluation with respect to the area fraction. The area occupied by Ver GmbHsclustem and Klemwinkelkomsky area ratio is low in this case.
  • FIG. 6a shows a PL recording
  • FIG. 6b shows a ⁇ -PCD mapping of a VGF monosilicon material in the geometric shape of a wafer.
  • the area occupied by Ver GmbHsclustem and Klemwinkelkomalian surface area is high in this case.
  • FIG. 7 shows a partial surface of an IR blank which has been produced from the VGF monocrystalline region A of an ingot.
  • the entire surface of the quasi-monocrystalline region A or of the blank to be evaluated is either recorded as a full image and evaluated or composed of several individual images (eg surface elements as shown in FIG. 7) and evaluated. If a statement about a concrete blank geometry is to be made in terms of a quality rating in the 5 classes Cl to C5 mentioned below, the or within the composite image, a contour (new inspection surface) within which the area fraction of the total area interspersed by dislocation clusters and small-angle grain boundaries is determined.
  • a contour new inspection surface
  • the charge carrier lifetime or a value correlated with the charge carrier lifetime of the material is always determined for a pixel of the aforementioned rastering or imaging measurement techniques (in the case of medium-ohmic material preferably PL). This is also done for all adjacent pixels in a subarea of the total area to be evaluated. This subarea may be square, rectangular, circular or elliptical. From the pixels completely enclosed in this area with a center pixel (border pixels are not allowed), an averaged image is generated. This can e.g. from an area of 11 x 11 pixels, i. 121 pixels, or an arbitrarily defined number of pixels, e.g. greater than 50 pixels or greater than 100 pixels are obtained.
  • a difference between the average value is formed from the defined number of neighboring pixels and the center pixel measurement value. If this difference exceeds a previously defined amount, the center pixel is evaluated as a bad pixel.
  • This threshold value has to be specified according to the measuring method, the range of the specimen resistivity and the doping (p- or n-type). For medium-resistance material and the measurement method MDP, e.g. a threshold of 0.22 is an appropriate value.
  • the cluster content in% is determined as follows:
  • Contour e.g., the blank surface or new test surface
  • VGF silicon material for functional components in semiconductor processing plants, such as semiconductor devices. Focus rings, shield rings, showerheads, or the like are classified into the following 5 quality classes:
  • Class Cl silicon material with discrete dislocations in the range of greater than 1 x 10 2 cm 2 to smaller l x 10 6 cm 2 in its quasi-monocrystalline, dislocation cluster or small angle grain boundary-free volume, which on a cut surface the material has an area fraction of 0% clusters interspersed with dislocation clusters or small angle grain boundaries.
  • Class C2 silicon material with individual dislocations in the range of greater than 1 x 10 2 cm “2 to less than lx l0 6 cm” 2 in its quasi monocrystalline verskyscluster- or small-angle grain boundaries free volume which to a sectional area through the material of a surface portion of less than or equal 25% interspersed with dislocation clusters and small angle grain boundaries.
  • Class C3 Silicon material with discrete dislocations in the range of greater than 1 x 10 2 cm “2 to smaller lx 10 6 cm “ 2 in its quasi-monocrystalline, dislocation cluster or small angle grain boundary-free volume which has an areal fraction of less than or equal to a sectional surface through the material 50% interspersed with dislocation clusters and small angle grain boundaries.
  • Class C4 silicon material with individual dislocations in the range of greater than 1 x 10 2 cm “2 to less than lx l0 6 cm” 2 in its quasi monocrystalline verskyscluster- or small-angle grain boundaries free volume which to a sectional area through the material of a surface portion of less than or equal 80% interspersed with dislocation clusters and small angle grain boundaries.
  • Class C5 Silicon material that passes through the material on a cut surface
  • the classes FK1 to FK5, ZI to Z5 and Cl to C5 shall be used for the assessment.
  • different material behavior under operating conditions can be observed and therefore material of a particular class must be selected.
  • the flat etching removal per unit time in particular, for example, in plasma etching plants
  • the homogeneity of the etching removal in particular, for example, in plasma etching plants
  • Particle release under conditions of use (in particular e.g.
  • Classes FK comparatively strong negative effect Irrespective of whether a medium-resistance silicon material evaluated according to the present invention was classified into one of the classes Z, C or FK and for the production of functional components in etching systems (with or without plasma support), CVD systems (regardless whether with or without plasma assist) or other equipment for processing semiconductor devices, it has always had better performance characteristics than traditional medium-resistance multicrystalline material.
  • Semi-resistive monocrystalline silicon material from the CZ or FZ process which is suitable for semiconductor production is only weakly superior to the medium-resistance quasi-monocrystalline silicon material according to the present invention with regard to its insertion characteristics.
  • a crucible with crucible attachment with a total height of 760 mm is placed in a G4 furnace.
  • the crucible contains a monocrystalline germ plate with a length x width of 600 mm x 600 mm and a height of 40 mm, crystalline silicon raw material and dopant boron.
  • the total weight is 450 kg.
  • the germination plate is positioned on the crucible bottom in such a way that a uniform gap remains between the germination plate and the crucible wall.
  • the furnace system has three heating zones: ceiling heater, jacket heater and bottom heater.
  • an active cooling arrangement which consists of water-cooled copper plate and an overlying highly heat-conductive graphite block identical geometry shape.
  • the cooling arrangement can be moved vertically by means of a lifting mechanism and contacts the crucible installation plate via the graphite block.
  • the water-cooled copper plate and the graphite each have a hole at the edge through which a pyrometer can see directly from below on the crucible mounting plate. This pyrometer is used to control the germplasm temperature.
  • the cooling plate is in the lower position and all heaters are active.
  • the crystalline silicon is melted from above. From a certain temperature, which corresponds to the melting point of the silicon, the cooling plate is partially moved up and reduces the performance of the bottom heater. At this time, the cooling plate still has no contact with the overlying crucible mounting plate.
  • the bottom heater encloses the graphite cylinder when fully driven upwards.
  • the soil is simultaneously cooled and heated to not completely melt the seed but to minimize heat losses at the edge of the crucible.
  • the cooling capacity must be adjusted to the heater temperatures in such a way that, especially during the seeding process, a flat phase boundary is established.
  • the temperature determined by the pyrometer at the measuring location below the crucible setting plate goes through a minimum in each process, which is determined and stored as an absolute value.
  • the temperature difference between the current temperature value after passing through the minimum and the previously determined minimum is used to determine the height of the seeding point. This corresponds to a temperature difference between measured value and temperature minimum of 20 K. If this difference is reached, the crystallization is initiated.
  • the Ankeimstelle lies with a germ with a height of 40 mm and then in the range of 15-25 mm above the crucible bottom.
  • the cooling plate is fully moved up to the crucible mounting plate.
  • the contact with the crucible mounting plate increases the heat dissipation downward as a result of an increase in the maximum cooling capacity.
  • 0,65W / cm 2 on minimal l, 5W / cm 2 and the phase boundary moves upwards.
  • all heater temperatures are additionally reduced according to a temperature-time profile. Is the Crystallization completed, the cooling phase is initiated.
  • the cooling rates are a maximum of 100 K / h.
  • the ingot is removed from the crystallization unit and removed from the crucible.
  • the ingot is placed on a side surface, and there is a lid cut, which removes the experience according to segregation contaminated with impurities and therefore useless material of appropriate thickness. This shows how large the quasi-monocrystalline region is in the center of the ingot both on the bottom and on the lid.
  • the quasi-monocrystalline center region is now being examined in more detail in which number or at what location within the quasi-monocrystalline matrix foreign or twin boundaries could be present and in which class FK 1 to FK 5 or ZI to Z 5 this center region or correspondingly predetermined Areas thereof, which are suitable for the production of medium-impedance functional components for systems for semiconductor processing, can be grouped.
  • Such medium-impedance functional components for systems for semiconductor processing are, for example, focus rings with the dimensions outside diameter 400mm, inside diameter 295mm, and thickness 5mm, or outside diameter 260mm, inside diameter 196.4mm, thickness 3.5mm, or shield rings with the dimensions outside diameter 410mm, inside diameter 320mm , and thickness 25mm.
  • this center area or corresponding predetermined areas thereof which appear suitable for the production of functional components, examined by means of scanning or imaging measurement techniques (such as MDP, ⁇ -PCD or PL) and divided into the classes Cl to C5. If necessary, a sample is also cut out of the quasi-monocrystalline center region in order to control the resistivity by means of a 4-point measuring station, ie to confirm that it lies within the required range of greater than 0.2 ⁇ and less than 5 ⁇ , for example or the typical value for focus rings of 2 ⁇ met.
  • scanning or imaging measurement techniques such as MDP, ⁇ -PCD or PL
  • a crucible with crucible attachment with a total height of 780 mm is introduced.
  • a planar seed pad made of silicon is introduced, on which a plurality of silicon seed plates are arranged in a layer.
  • the thickness of the seed pad is 5 to 20mm, with 10 to 20mm being preferred.
  • the germplates are cut horizontally from quasi-monocrystalline areas of previous ingots to a thickness of 45mm.
  • the abutting surfaces of the germ plates or additionally at least one further surface are ground. In this case, the abutment surfaces of adjacent germination plates are ground at right angles so that, when using three or more germ plates, the width of the resulting column (viewed from above) is as small as possible.
  • the ground abutment surfaces have a right angle.
  • the ground surfaces (in particular the edge surfaces) have a roughness of Rz according to DIN 4762 of less than ⁇ , more preferably less than ⁇ and particularly preferably less than 5 ⁇ and their angularity is considered both vertically and horizontally so good that gaps formed during the laying out of the germination plates and during the melting of the germination plates between immediately adjacent germinal plates are smaller than 1 mm, more preferably less than 0.1 mm, and more preferably less than 0.01 mm, at each point. Due to this predetermined accuracy of fit, the silicon material to be grown according to the invention does not have any twin grains (shock twins) which are formed on germ buds.
  • Crystalline silicon raw material of a total weight of 700 kg and boron dopant are introduced onto the seed layer.
  • the germ layer is so dimensioned and on the Keimaufstellplatte positioned that around a gap of about 20 mm remains. Their upwards or, if necessary, additionally downwards pointing surface is roughened in a sandblasting process with suitable material.
  • the silicon raw material and the dopant are filled.
  • the Si raw material has at least 7N purity.
  • the kiln plant is a multi-zone kiln plant with a total of four temperature-controlled heating zones: ceiling heaters, overhead heaters, bottom heaters and bottom heaters.
  • Under the crucible mounting plate is an active cooling device.
  • the cooling medium used is gaseous nitrogen.
  • the dimensions of the cooling device (length, width) correspond at least to the dimensions of the crucible mounting plate.
  • the protective tube abuts the overlying graphite plate from below.
  • On top of this graphite plate are the crucible mounting plate made of graphite and above it the crucible.
  • the melting process is designed such that the silicon raw material is melted from above and the silicon germination plate is only partially melted.
  • a temperature profile is set, which typically has a higher temperature on the ceiling heater than on the bottom heater.
  • the bottom heater is in operation only in the heating phase and is switched off at the time t ls reaching the melting temperature of the silicon, in order to prevent melting of the quasi-monocrystalline nucleus.
  • the gas cooling is activated from reaching about 1400 C on the side heater. The cooling capacity must be adjusted to the heater temperatures in such a way that, especially during the seeding process, a flat phase boundary is established.
  • the crystalline silicon raw material continues to melt above the germplate as a result of the ceiling and side heaters, which continue to be held at a predefined temperature value.
  • the temperature at the measuring point below the crucible setting plate goes through a recognizable minimum in each process in Fig. 9, which is determined and stored as an absolute value.
  • the total heating power inevitably decreases continuously in the same period of time.
  • the height of the Ankeimstelle can be determined. In the case of a germ of 45 mm height, the germination site is ideally in the range of 25 mm to 35 mm above the crucible bottom.
  • the crystallization is initiated. It can be several hours between temperature minimum and start of crystallization.
  • the crystallization is initiated on the one hand by increasing the cooling capacity of the gas cooling and on the other hand via a controlled temperature-time profile of the active heater. In this case, the cooling capacity is rapidly increased, for example, from a maximum of 5 kW (specifically, a maximum of 0.65W / cm 2 ) to at least 15 kW (specifically, a maximum of 1.5 W / cm 2 considered ) to prevent melting of the germ.
  • the temperatures of the Heating zones are slowly reduced.
  • the cooling rates are in the range of -0.4 K / h to - 15 K / h.
  • a convex phase boundary is set in the center, which pushes the polycrystalline edge region further outward or supports a vertical columnar growth there.
  • the cooling phase begins.
  • the heaters are controlled by a further temperature-time profile.
  • the cooling rates are -10 K / h to -80 K / h.
  • the ingot is removed from the crystallization unit and removed from the crucible.
  • the ingot soil is separated in a thickness of 45 mm. In this way, a plate is obtained, which can be used again as a germ after a sandblasting process with suitable material and subsequent cleaning. From the remaining ingot side parts are now sawed off so that the resulting ingot base area is reduced to 780 mm x 780 mm.
  • the quasi-monocrystalline center region is now being examined in more detail in which number or at what location within the quasi-monocrystalline matrix foreign or twin boundaries could be present and in which class FK 1 to FK 5 or ZI to Z 5 this center region or correspondingly predetermined Areas thereof, which are suitable for the production of medium-impedance functional components for systems for semiconductor processing, can be grouped.
  • Such medium-impedance functional components for systems for semiconductor processing are, for example, focus rings with the dimensions outside diameter 400mm, inside diameter 295mm, and thickness 5mm, or outside diameter 260mm, inside diameter 196.4mm, thickness 3.5mm, or shield rings with the dimensions outside diameter 410mm, inside diameter 320mm , and thickness 25mm.
  • this center area or corresponding predetermined areas thereof, which appear suitable for the production of components examined by means of scanning or imaging measurement techniques (such as MDP, ⁇ -PCD or PL) and divided into the classes Cl to C5.
  • a sample is also cut out of the quasi-monocrystalline center region to control the resistivity by means of a 4-peak measuring site, i. to confirm that he e.g. is within the required range of greater than 0.2 ⁇ and less than 5 ⁇ or meets the typical value for focus rings of 2 ⁇ .
  • Blank now works out the blanks out of the disc.
  • the blank surface now corresponds to a newly defined test surface for which the classification applies.
  • thermocouple with protective tube 16 thermocouple with protective tube

Landscapes

  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Crystals, And After-Treatments Of Crystals (AREA)
  • Silicon Compounds (AREA)

Abstract

L'invention concerne l'utilisation d'un silicium quasimonocristallin, lequel est fabriqué selon le procédé de solidification dirigée, pour des composants utilisés dans l'industrie des semi-conducteurs pour le traitement des semi-conducteurs ou des composants à semi-conducteur. Les ébauches présentent selon l'invention une concentration de dislocations individuelles dans la plage de 103 à 105 cm-2 dans un volume exempt d'agrégats de dislocation, et donc de joints de grain à faible angle, et/ou une résistance spécifique supérieure à 0,2 Ωcm et inférieure à 5 Ωcm, et peuvent donc être fabriquées de manière plus économique et efficace.
PCT/EP2014/055880 2013-04-08 2014-03-24 Ébauche en silicium, procédé permettant sa fabrication et utilisation de ladite ébauche WO2014166725A1 (fr)

Applications Claiming Priority (8)

Application Number Priority Date Filing Date Title
DE102013103488.8 2013-04-08
DE102013103488 2013-04-08
DE102013107193.7A DE102013107193A1 (de) 2013-04-08 2013-07-08 Rohling aus Silizium, Verfahren zu dessen Herstellung sowie Verwendung desselben
DE102013107193.7 2013-07-08
DE102014101222 2014-01-31
DE102014101222.4 2014-01-31
EPPCT/EP2014/055453 2014-03-18
PCT/EP2014/055453 WO2014147094A1 (fr) 2013-03-18 2014-03-18 Ébauche en silicium, procédé pour la fabriquer et son utilisation

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WO2014166725A1 true WO2014166725A1 (fr) 2014-10-16

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN104711673A (zh) * 2015-03-13 2015-06-17 湖南红太阳光电科技有限公司 一种多晶硅铸锭的制备方法

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE10056726A1 (de) * 2000-11-15 2002-05-23 Solar Gmbh Deutsche Multikristallines Silicium mit einem geringen Anteil an aktiven Korngrenzen
WO2009014961A1 (fr) * 2007-07-20 2009-01-29 Bp Corporation North America Inc. Procédés et appareils destinés à fabriquer du silicium coulé à partir de germes cristallins
WO2009015167A1 (fr) * 2007-07-25 2009-01-29 Bp Corporation North America Inc. Procédés pour la fabrication de matériaux moulés monocristallins ou presque monocristallins
DE102010029741A1 (de) * 2010-06-07 2011-12-08 Solarworld Innovations Gmbh Verfahren zum Herstellen von Silizium-Wafern und Silizium-Solarzelle
US20120175553A1 (en) * 2011-01-12 2012-07-12 Andreas Krause Method for producing a silicon ingot
DE102011075093A1 (de) * 2011-05-02 2012-11-08 Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V. Verfahren zur Herstellung eines Silizium-Ingots

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE10056726A1 (de) * 2000-11-15 2002-05-23 Solar Gmbh Deutsche Multikristallines Silicium mit einem geringen Anteil an aktiven Korngrenzen
WO2009014961A1 (fr) * 2007-07-20 2009-01-29 Bp Corporation North America Inc. Procédés et appareils destinés à fabriquer du silicium coulé à partir de germes cristallins
WO2009015167A1 (fr) * 2007-07-25 2009-01-29 Bp Corporation North America Inc. Procédés pour la fabrication de matériaux moulés monocristallins ou presque monocristallins
DE102010029741A1 (de) * 2010-06-07 2011-12-08 Solarworld Innovations Gmbh Verfahren zum Herstellen von Silizium-Wafern und Silizium-Solarzelle
US20120175553A1 (en) * 2011-01-12 2012-07-12 Andreas Krause Method for producing a silicon ingot
DE102011075093A1 (de) * 2011-05-02 2012-11-08 Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V. Verfahren zur Herstellung eines Silizium-Ingots

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN104711673A (zh) * 2015-03-13 2015-06-17 湖南红太阳光电科技有限公司 一种多晶硅铸锭的制备方法

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