US3031403A - Process for producing crystals and the products thereof - Google Patents

Process for producing crystals and the products thereof Download PDF

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US3031403A
US3031403A US844288A US84428859A US3031403A US 3031403 A US3031403 A US 3031403A US 844288 A US844288 A US 844288A US 84428859 A US84428859 A US 84428859A US 3031403 A US3031403 A US 3031403A
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melt
crystal
seed crystal
dendritic
crystals
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US844288A
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Jr Allan I Bennett
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CBS Corp
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Westinghouse Electric Corp
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Priority to NL241834D priority Critical patent/NL241834A/xx
Priority to NL113205D priority patent/NL113205C/xx
Priority to CH7589659A priority patent/CH440226A/de
Priority to GB27537/59A priority patent/GB889058A/en
Priority to DEW26266A priority patent/DE1291320B/de
Priority to FR803725A priority patent/FR1244924A/fr
Priority to US844288A priority patent/US3031403A/en
Application filed by Westinghouse Electric Corp filed Critical Westinghouse Electric Corp
Priority to GB13783/60A priority patent/GB913674A/en
Priority to DEW27847A priority patent/DE1302031B/de
Priority to FR828125A priority patent/FR77774E/fr
Priority to CH1114860A priority patent/CH475014A/de
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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
    • C30B15/00—Single-crystal growth by pulling from a melt, e.g. Czochralski method
    • C30B15/36—Single-crystal growth by pulling from a melt, e.g. Czochralski 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
    • C30B15/00—Single-crystal growth by pulling from a melt, e.g. Czochralski method
    • 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
    • C30B29/60—Single crystals or homogeneous polycrystalline material with defined structure characterised by the material or by their shape characterised by shape
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10S117/00—Single-crystal, oriented-crystal, and epitaxy growth processes; non-coating apparatus therefor
    • Y10S117/901—Levitation, reduced gravity, microgravity, space
    • Y10S117/902—Specified orientation, shape, crystallography, or size of seed or substrate
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10S117/00—Single-crystal, oriented-crystal, and epitaxy growth processes; non-coating apparatus therefor
    • Y10S117/903—Dendrite or web or cage technique
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10S148/00—Metal treatment
    • Y10S148/074—Horizontal melt solidification
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10S148/00—Metal treatment
    • Y10S148/107—Melt

Definitions

  • the object of the present invention is to provide a process for producing crystals of precisely controllable thickness from supercooled melts of solid material.
  • a further object of the invention is to provide for growing fiat dendritic crystals from a supercooled melt of a semiconductor material while maintaining low temperature gradients in the crystals above the melt surface so that-imperfections in the grown crystal are minimized.
  • Another object of the invention is to provide flat dendritic crystals with at least one twin plane extending therethrough of materials having a diamond cubic lattice structure with flat faces having precise (111) surfaces.
  • a further object of the invention is to provide a method for preparing dice from semiconductor materials without mechanical cutting operations by preparing fiat dendri'tic crystals from a supercooled melt of the material and, then, scoring the flat surfaces and breaking the flat crystals along the score lines to produce the desired dice.
  • a still further object of the invention is to provide doped fiat dendritic crystals of solid materials by preparing a melt of a material containing doping impurities in the proportions approaching those desired in the crystals, supercooling the melt and withdrawing therewith 3,031,403 Patented Apr. 24, 1932 dendritic crystals containing doping impurities in thedesired proportions.
  • .FlGURE 1 is a view in elevation partly in section-of a crystal growing apparatus in accordance with the invention.
  • FIG. 2 is a greatly enlarged fragmentary view of a dendritic crystal having a single twin plane
  • FIG. 3 is a greatly enlarged fragmentary view of a dendritic crystal having three twin planes
  • FlG. 4 is a fragmentary view in elevation
  • FIG. 5 is an enlarged plan view of a dendritic crystal.
  • crystals of solid materials may be pre pared as flat dendritic crystals having a closely controllable thickness with relatively precise flat parallel faces.
  • These flat dendritic crystals may be pulled or grown from melts of the material at a relatively high rate of speed of pulling of the order of times and greater than the linear pulling velocity previously employed in the art.
  • the thickness of the crystals may be readily controlled and surface imperfections minimized or reduced by following the teachings of the present invention.
  • a melt of the material to be grown into a flat dendritic crystal is prepared at a temperature slightly above the melting temperature thereof.
  • the surface of the melt is contacted with a previously prepared crystal having at least one twin plane at the interior thereof, the crystal being oriented with the 2l1 direction vertical to the melt surface.
  • Other necessary or desirable crystallographic and physical features of the seed crystal will be pointed out in detail hereinafter.
  • the seed crystal is dipped into the surface of the melt a sufiicient period of time to cause wetting.
  • the melt is supercooled rapidly, following which the seed crystal is withdrawn with respect to the melt at a speed of the order of from one to ten inches a minute.
  • considerably slower pulling speeds than an inch per minute can be employed for example 0.2 inch per minute. Pulling speeds of from 10 to 25 inches per minute have given good results.
  • the degree of supercooling and the rate of pulling can be readily so correlated that the seed crystal withdrawn from the melt comprises solidified melt material thereon of a precisely desired thickness and the desired crystallographic orientation.
  • the present invention is particularly applicable to solid materials crystallizing in the diamond cubic lattice vstructure.
  • examples of such'materials are the elements silicon and germanium.
  • stoichiometric compounds having an average of four valence electrons per atom respond satisfactorily to the crystal growing process.
  • Compounds comprising stoichiometric proportions of group II and group VI elements for example, ZnSe and ZnS, can be processed.
  • diamond cubic lattice structure materials may be intrinsic or they may be doped with one or more impurities to produce n-type or p-type semiconductor materials.
  • the crystal growing process of the present invention may be applied to all of these diiferent materials.
  • FIG. 1 of the drawings wherein there is illustrated apparatus 10 for practicing the process.
  • the apparatus comprises a base 12 carrying a support 14 for a crucible 16 of a suitable refractory material such as graphite to hold a melt of the material from which fiat dendritic crystals are to be drawn.
  • Molten material 18, for example, germanium is maintained withinthe crucible 16 in the molten state by a suitable heating means such, for example, as an induction heating coil 20 disposed about the crucible.
  • Controls are employed to supply an alternating electrical current to the induction coil 20 to maintain a closely controllable temperature in the body of the melt 18.
  • the temperature should be readily controllable to provide a temperature in the melt a few degrees above the melting point and also to reduce heat input so that the temperature drops in a few seconds, for example in to seconds to a temperature at least one degree below the melting temperature and preferably to supercool the melt from 5 to'15 C., or lower.
  • a cover 22 closely fitting the top of the crucible 16 may be provided in order to maintain a low thermal gradient above the top of the melt. Passing through an aperture 24 in the cover 22 is a seed crystal 26, preferably having three twin planes and oriented crystallographically as will be disclosed in detail hereinafter.
  • the crystal 26 is fastened to a pulling rod 28 by means of a screw 39 or the like.
  • the pulling rod 28 is actuated by suitable mechanism to control its upward movement at a desired uniform rate, ordinarily in excess of one inch per minute.
  • a protective enclosure 32 of glass or other suitable material is disposed about the crucible with a cover 34 closing the top thereof except for an aperture 36 through which the pulling rod 28 passes.
  • the protective atmosphere may comprise a noble gas such as helium or argon,'or a reducing gas such as hydrogen or mixtures of hydrogen and nitrogen, or nitrogen or the like or mixtures of two or more gases.
  • the space around the crucible may be evacuated to a high vacuum in order to produce crystals of ma terials free from any gases.
  • a separately heated vessel containing the component may be disposed in the enclosure 32 to maintain therein a vapor of such compound at a partial pressure sufficient to prevent impoverishing the melt or the grown crystals with respect to the component.
  • an atmosphere of arsenic may be provided when crystals of gallium arsenide are being pulled.
  • the enclosure 32 may be suitably heated, for example, by an electrically heated cover, to maintain the walls thereof at a temperature above the temperature of the separately heated vessel containing the arsenic in order to prevent condensation of arsenic thereon.
  • a section of a seed crystal 26 having a single twin plane Such seed crystal may be obtained in various ways, for example, by supercooling a melt of the solid material to a temperature at which a portion thereof solidifies, at which time some dendritic crystals having one or more internaltwin planes will be formed and may be removed from the melt. While these crystals may not be uniform, they are suitable for seed purposes. Also one can cut from a large twinned crys tal a section suitable for use as a seed crystal.
  • the seed crystal 26 comprises two relatively flat parallel faces 55) and 52' with an intermediate interior twin plane 54.
  • the twin plane ordinarily will be precisely midway between the faces 50 and 52. Examination will show that the crystallographic structure of the preferred seed on both faces 50 and 52 is that indicated by the crystallographic direction arrows at the right and left faces, respectively, of the figure. It will be noted that the horizontal directions perpendicular to the fiat faces 50 and 52 and parallel to the melt surfaces are 111 The direction of growth of the dendritic crystal will be in a 211 crystallographic direction.
  • the faces 50 and 52 of the dendritic crystal 26 were to be etched preferentially to the [111] planes, they will both exhibit'equilateral triangular etch pits 56 whose vertices 58 will point upwardly while their bases will be parallel to the surface of the melt. It is an important feature of the preferred embodiment of the present invention that the etch pits on both faces 59 and 52 of seed crystal 26 have their vertices 53 pointing upwardly. A non-twinned crystal or a crystal containing two twin planes or any even number thereof will exhibit triangular etch pits on one face whose vertices will be pointing opposite to the direction of the vertices on the other face.
  • FIG. 3 of the drawing there is illustrated a highly magnified portion of a seed crystal 126 which contains three twin planes 154, 156 and 158 extending across the entire cross-section thereof.
  • the faces 1% and 152 have the same crystal orientation as the faces 50 and 52 of FIG. 2.
  • the spacings or lamellae between the successive adjacent twin planes ordinarily are not uniform.
  • the larnellar spacing, such as A between twin planes 154 and 156, and B between twin planes 156 and 158, is of the order of microns, that is from a fraction of a micron'to 15 to 20 microns or possibly greater.
  • the ratio of A to B as determined from studies of numerous dendritic crystals has varied in the ratio of slightly more than 1 to as much as 18.
  • One of these improved techniques comprises scribing a line transverse of the length of the dendrite, bending the dendrite at the scribed line to bow it away from the scribed line until it fractures thereat, and, without polishing or otherwise working on the fractured face, examining it under a microscope at a magnification of at least x, and preferably 200 to 500x.
  • the fracturing results in relatively flat faces developing at successive lamellae at different angles to each other which stand out distinctly under illumination.
  • preferentially etching of a polished cross-section, preferably cross-sections lapped at an angle to the flat face, so as to selectively distinguish the lamellae from each other, will enable the separate twin planes to be clearly distinguished.
  • Seed crystals having an odd number (other than 1 and 3', thatis', 5, 7- and up to 13' or more) twin planes containing the growth direction may be employed in practicing the process of this invention; due care being had to point the triangular etch pits on the outer faces of the crystal with their vertices upwardly and the bases parallel to the surface of the melt.
  • seed crystals containing an even number of twin planes may be employed for crystal pulling, though as desirable pulled crystals will not be obtainable as with the preferred three twin plane seed crystal as shown in FIG. 3.
  • the pulled dendrite will exhibit the same twin plane structure as the seed crystal exhibits.
  • the dendrite will have three twin planes extending through its entire length if the seed comprises three twin planes.
  • the direction of withdrawal of the seed crystal 26 having an odd numberof twin planes from the melt 18 must be with the direction of the vertices 53 of the etch pits being upward and the bases being substantially parallel to the surface of the melt.
  • the melt will solidify at the bottom of the crystal in a satisfactory prolongation thereof; If the crystal 26 were to be inserted into the melt so that the vertices 58 pointed downwardly, very erratic grown crystals will be produced which are not only of non-uniform dimensions but grow at angles of 120 to the seed and produce very irregular spines, and generally are unsatisfactory.
  • the seed crystal pulling mechanism is energized to pull the crystal from the melt at the desired rates.
  • the initiation of pulling is timed to the appearance and growth of the spikes for best results.
  • the seed crystal is disposed so that one edge is nearer the thermal center of the melt crucible than is the other edge, it is possible to increase briefly either the pulling rate or the temperature of the melt, and under these variations the dendritic crystal furthest away from the thermal center or in a hotter region will usually stop growing and thereafter only a single dendritic crystal will be attached to and grow from the seed. Also, if the double dendritic crystal attached to the original seed crystal is introduced into the same or another melt slightly above the melting temperature and after supercooling the melt, on pulling the double dendritic crystal from appearance.
  • the seed crystal need not be fiat. It may be of any suitable size or shape as long as its orientation corresponds to that shown in FIG. 2. Usually a portion of a previously grown dendritic crystal having twin planes will be quite satisfactory for use as a seed and ordinarily such will be used as the seed crystal.
  • the pulled dendritic crystal need have no direct relation to the seed crystal as far as size is concerned.
  • the pulled dendritic crystal will have a size and shape depending on the pulling conditions.
  • the melts of the materials may be supercooled as much as 30 to 40 be- In practice, however, supercooling of from 5 to 15 C. has given best results with germanium and indium antimonide, for example. A greater degree of supercooling requires higher rates of crystal withdrawal from-the melt as well as requiring more precise control of the speed of pulling.
  • Germanium and indium antimonide dendritic crystals have been satisfactorily pulled at rates of from 4 inches to 12 inches per minute from melts supercooled 5 C. to 15 C. As an example, these crystals have had a highly uniform thickness selected from the range of from 3 to 20 mils and a selected width of from 1 to 4 millimeters. The length of these crystals is limited solely by the pulling apparatus employed. Nodifficulty has been experienced in pulling crystals of, for example, --7 inches in length in a slightly modified crystal pulling furnace as normally used in the art.
  • the pulled dendritic crystals will have a thickness of the order of from 1 to 25 mils and the width across the flat faces may be from 20 mils to 200 mils and even wider.
  • the surface at the flat faces will exhibit essentially perfect (111) orientation.
  • the grown dendritic crystals of this invention will be essentially twinned crystals which are not of single crystal structure. Properly grown crystals will have faces that comprise flat areas on either side which are parallel and planar within a wavelength,*of..sodium light, per centimeter of length.
  • dendritic crystals While the dendritic; crystals will exhibit some degree of edge serration, dendritic crystals have been obtained with fairly uniform edges having a minimum of ragged The serrated edges comprise only a small portion of the crystals and can be readily removed or left intact in dice since they do not affect the properties of the central or main body portion of the dendrites.
  • Such imperfections or dislocations may be minimized or completely eliminated by providing means for decreasing the temperature gradient in the newly drawn dendritic crystals for a distance above the surface of the melt, for example, a distance of the order of 1 cm. to 3 cm. Once the temperature of the crystals, for example, germanium has fallen to 700 C., there is no difiiculty due to cooling temperature gradients.
  • One means for producing such low temperature gradients is the application of a ceramic cap such as 22 to the top of the crucible whereby the heat of the melt is prevented from escaping and is radiated, back for an appreciable distance above the surface of' the melt.
  • T us the radiant heat below the cover 22 in FIG. 1 prohibits the dendritic crystal as from cooling too rapidly or unevenly for an appreciable distance above the melt until the growing dendrite has a chance to cool below the range of plasticity without introducing dislocations and other structure imperfections.
  • an external heating coil or sleeve may be disposed about the lower end of the dendrite crystal and an electrically conductive cap such as graphite applied about the crystal above the melt to be energized by high frequency current to produce a more controllable temperature gradient reducing effect.
  • the fiat dendritic crystals of the present invention are relatively flexible, and crystals of a thickness of 7 mils may be bent on a radius of the order of 4 inches or even less without breaking. Consequently, crystals may be continuously drawn from the melt and Wound on a cylinder of a radius of this order in continuous lengths, as desired. The thinner crystals obviously can be wound to a smaller radius than crystals of greater thickness.
  • FIG. 4 of the drawing there is illustrated a suitable mechanism for pulling a dendritic single crystal of indefinite length.
  • the dendritic crystal 194 being withdrawn from melt 18 is disposed between rotating cylinders 160 and 102 flexibly mounted to grip the dendritic crystal between them and whose speed of rotation is correlated to 104 above the drums 160 and 102 may be coiled on a wide diameter spool or it may be severed from time to time into suitable lengths.
  • Other means for continuously pulling the dendritic crystal from the melt may be employed.
  • the dendritic crystal grows deep in the supercooled melt, and as shown in PEG. 4, probably has a wedge-shaped configuration 1% below the surface'of the melt.
  • the grown dendritic crystals of the present invention have surfaces of such perfection that, in the case of semiconductor materials they may be employed for semiconductor applications simply by applying to the faces thereof desired alloys or solders without any intermediate polishing, lapping or etching. In fact, in general etching results in a degradation of the perfection of the crystal face.
  • the crystal surfaces have a perfect (111) orientationas grown. For making such devices as diodes, transistors, photodiodes and other similar semiconductor devices, the (111) surfaces are a particularly desired orientation.
  • doped crystals particularly from semiconductor materials such as silicon, germanium and stoichiometric compounds of the group III-group V compounds, may be readily prepared.
  • the dopingimpurities may comprise either adonor or acceptor material. Examples of donor impurities are antimony and phosphorus, while examples of suitable acceptor impurities are indium, gallium and aluminum.
  • donor impurities are antimony and phosphorus
  • acceptor impurities are indium, gallium and aluminum.
  • a further advantage of the present invention is that dice for semiconductor and other applications may be prepared from the grown dendritic crystals by a very simple operation which does not require the use of sawing, ultrasonic cavitation, or other involved cutting processes.
  • To prepare a desired convex polygonal shape from a fiat dendritic crystal it is only necessary to score the surface lightly with a diamond, for example, and upon a Y slight flexing, the dendrite will break along the score the supercooling of the melt 13 such that the desired thickness of dendritic crystal is withdrawn continuously. Dendrites in lengths of up to 30 feet have been grown in accordance with the invention. The portion of the crystal mark, thereby leaving the desired shape die.
  • a dendrite crystal 1434 which it is desired to cut into rec tangular dice.
  • the fiat surface is scored lightly with a diamond to provide two parallel transverse grooves 69 and 62 defining therebetween a desired square die 66.
  • the dendrite is placed on a flat surface with the end 64 beyond score mark 6t!v projecting beyond the edge of the surface and flexed lightly by applying a twcezer to the end and the end will break off at the score mark 60.
  • the die 66 is severed from the main body of the dendrite 164.
  • the die 66 has a perfect (111) orientation and may be employed for semiconductor diode or transistor or similar device fabrication without any further mechanical working. it will be appreciated that the proceduresetforth herein will effect substantial econincreasing the pulling rate to 12 inches per minute.
  • the present process enables the growing or pulling of dendritic crystals from a melt at, for example, linear rates of from 100 to 1000 times greater than those employed heretofore. It will be understood that while only a single seed crystal 26 is illustrated in FIG. 1 as being pulled from the melt 18 a number of similar seed crystals may be employed and pulled simultaneously. By correlating the size and thickness of the crystal and the degree of supercooling of the melt with the rate of withdrawal the crystals may be pulled with substantially fiat faces of uniform thickness.
  • Example I In apparatus similar to FIG. 1, a graphite crucible containing a quantity of intrinsic germanium is heated by the induction coil to a temperature several degrees above the melting point of germanium, the temperature being about 938 C., until the entire quantity forms a molten pool.
  • a dendritic seed crystal having at least one interior twin plane extending entirely therethrough and oriented as in FIG. 2 of the drawing, held vertically in a holder is lowered until its lower end touches the surface of the molten germanium. The contact with the molten germanium is maintained until a small portion of the end of the dendritic seed crystal has melted.
  • the temperature of the melt is lowered rapidly in a matter of 5 seconds by reducing current to the coil 20, to a tem perature 8 below the melting point of the germanium so scopic steps ditfering by about 50 angstroms and were of a quality suitable for semiconductor applications.
  • Particularly good results were had where the seed crystals had three interior twin planes separated by distances of 5 microns and 1% microns respectively.
  • the dendrite of course, similarly had three twin planes.
  • the process of this Example I was repeated, except for The dendritic crystal was approximately 3.5 mils in thickness and of a width of about 30 mils. The surface perfection and flatness was exceptional. Thus in a length of an inch there was observed less than a wavelength of light variation in thickness.
  • the faces of the dendritic crystal were of precisely (111) orientation.
  • Example II centrations were introduced into the germanium of this Example IIin lieu of the arsenic, and dendritic germanium crystals were grown therefrom.
  • Doped germanium dendritic crystals with three twin planes and of a resistivity varying from approximately 1 to 30 ohm centimeters were produced in these several instances.
  • a dendritic crystal of a width of 2 millimeters, doped with aluminum and having a resistivity of approximately 15 ohm centimeters was produced in accordance with this Example II. It was scored with a diamond into lengths of between 2 and 3 millimeters, and upon flexing the crystal was severed into substantially rectangular dice. A layer of antimonytin solder was applied to one face of a die and upon fusion a p-n junction diode was obtained. Conductive leads were fastened to the opposite faces. The resulting diode exhibited good rectifying properties, thereby indicating the dendritic crystals were of satisfactory quality for semiconductor device applications.
  • Example III A melt of indium antimonide was prepared following i the procedure of Example I employing apparatus as illustrated in FIG. 1 of the drawing. The indium'antimonide was withdrawn at the rate of 5 inches per minute from ,a melt supercooled 5 C. The resulting fiat dendrite crysthe precision of the orientation of pulled crystals disclosed herein.
  • twin planes being parallel to the 211 direction, the dendritic crystal when etched exhibiting triangular etch pits on both faces with the vertices of the triangular etch pits being directed perpendicularly upward with respect to the melt and the bases of the etch pits being parallel to the melt surface, supercooling the melted material to a selected temperature, and pulling the seed crystal at a rate of the order of at least one inch a minute with respect to the melt surface while maintaining the selected temperature whereby the material from the melt solidifies on the seed crystal and produces an elongated flat dendritic crystal.
  • the steps comprising preparing a molten body of germanium at a temperature slightly above its melting. point, contacting the surface of the molten germanium with a seed crystal of germanium, the seed crystal having a plural odd number of parallel interior twin planes extending entirely through the seed crystal, the seed crystal having a lll direction parallel to the surface of the melt and a 2ll direction perpendicular to the surface of the melt, the twin planes being parallel to the 211 direction the seed crystal when etched exhibiting triangular etch pits on both faces with the vertices" of the triangular pits being directed upwardly and the base of the triangle being parallel to the surface of the melt, rapidly supercooling the molten germanium at least one degree centigrade to a selected temperature, and withdrawing the dendritic seed crysal with respect to the melt at a rate of the order of at least one inch a minute while maintaining the selected supercooled temperature, the rate of withdrawal being correlated to the degree of super
  • the steps comprising preparing a molten body of germanium at a temperature slightly above its melting point, contacting the surface of the molten germanium with a seed crystal of germanium, the seed crystal having a plural odd number of parallel interior twin planes extending entirely through the seed crystal, the crystal having a lll direction perpendicular to the surface of the melt and a 21l direction perpendicular to the surface of the melt, the twin planes being parallel to the 2ll direction, the seed crystal when etched exhibiting triangular etch pits on both faces with the vertices of the triangular pits being directed upwardly and the base of the triangles being parallel to the surface of the melt, rapidly supercooling the molten germanium at least one degree centigrade to a selected temperature, and withdrawing the dendritic seed crystal with respect to the melt at a rate of the order of from one inch to ten inches a minute while maintaining the selected temperature, the rate of withdrawal being correlated to the degree of super
  • the steps comprising preparing a molten body of silicon at a temperature slightly above its melting point, contacting the surface of the molten silicon with a seed crys ml of silicon, the seed crystal having an interior twirl plane extending entirely through the seed crystal, the crystal having a lll direction parallel to the surface of the melt and a 21l direction perpendicular to the surface of the melt, the seed crystal when etched exhibiting triangular etch pits on both faces with the vertex of the triangular pits being directed upwardly, supercooling the molten silicon at least one degree centigrade, and withdrawing the dendritic seed crystal with respect to the melt at a rate of the order. of from one to ten inches a minute, the rate of withdrawal being correlated to the degree of supercooling so that the silicon from the melt solidifies on the seed crystal in the form of a fiat dendritic crystal.
  • the steps comprising preparing a molten body of silicon at a temperature slightly above its'melting point, contacting the surface of the molten silicon with a seed crystal of silicon, the seed crystal having an interior twin plane extending entirely through the seed crystal, the seed crystal having a lll direction parallel to the surface of the melt and a 21l direction perpendicular to the surface of the melt, the seed crystal when etched exhibiting triangular etch pits on both faces with the vertices of the triangular pits being directed upwardly and their bases parallel to the surface of the melt, supercooling the molten silicon at least one degree centigrade, and withdrawing the seed crystal with respect to the melt at a rate of the order of from one to ten inches a minute, the rate of withdrawal being correlated to the degree of supercooling so that the'silicon from the melt solidifies on the seed crystal as a flat dendritic crystal, and applying means to the withdrawn silicon crystal for a short distance above the melt
  • the steps comprising preparing a melted body of the material, adding a doping material to the melted body in proportions relatively closely equal to the proportions desired in the doped crystals, bringing the melt to a temperature slightly above the melting point of the material, contacting a surface of the melted mate'- rialtwith a seed crystal of the material for a period of time to wet the seed crystal with the melted material, the seed crystal having a plural odd number of parallel interior twin planes extending entirely through the seed crystal, the seed crystal having a lll direction parallel to the surface of the melt and a 21l direction perpendicular to the surface of the melt, the twin planes being parallel to the 2ll direction, the seed crystal when etched exhibiting triangular etch pits on both faces with the vertices of the triangular etch pits being directed perpendicularly upwardly with respect to the melt and the bases being parallel to
  • the steps comprising preparing a melted body of the material, bringing the melt to a temperature slightly above the melting point of the material, contacting a surface of the melted material with a flat dendritic seed crystal of the material for a period of time to wet the seed crystal with the melted material, the seed crystal having a plural odd number of parallel interior twin planes extending entirely through the seed crystal, the seed crystal having a l11 direction parallel to the surface of the melt and a 2ll direction perpendicular to the surface of the melt, the twin planes being parallel to the 2l1 direction, the seed crystal when etched exhibiting triangular etch pits onlboth faces with the ver-.
  • tices of the triangular etch pits being directed perpendicularly upwardly with respect to the'melt, supercooling the melted material to a selected temperature, and separating the seed crystal at a rate of the order of from one to ten inches per minute from the melt surface while maintaining the selected melt temperature whereby the material from the melt solidifies thereon and produces an elongated flat dendritic crystal, scoring the surface of the resulting flat dendritic crystal into selected sized areas and breaking the crystal at the score lines to produce the desired dice.
  • the steps comprising melting a quantity of the material, adding a doping material to the melted material, bringing the melt to a temperature slightly above the melting point of the material, contacting a surface of the melted material with a seed crystal of the material for a period of time to wet the seed crystal with the melted material, the seed crystal having a plural odd number of parallel interior twin planes, the crystal being oriented with a 111 direction parallel to the surface of the melt and a 211 direction perpendicular to the surface of the melt, the twin planes being parallel to the 211 direction, the dendritic crystal when etched exhibiting triangular etch pits on both faces with the vertices of the triangular etch pits being directed perpendicularly upward with respect to the melt and the bases of
  • the steps comprising preparing a molten body of silicon at a temperature slightly above its melting point, adding a doping material to the molten silicon, contacting the surface of the molten silicon with a seed crystal of silicon, the seed crystal having a 14 to the surface of the melt, the twin planes being parallel to the 211 direction, the seed crystal when etched exhibiting triangular etch pits on both faces with the vertices of the triangular pits being directed upwardly, and the bases being parallel to the surface of the melt, supercooling the molten silicon at least one degree centigrade, and withdrawing the seed crystal with respect to the melt at a rate of the order of from one to ten inches per minute, the rate of withdrawal being correlated to the degree of supercooling so that the silicon from the melt solidifies on the seed crystal as a flat dendritic doped crystal, scoring the suface of the resulting flat dendritic crystals into selected size areas and breaking the crystal at the score plural
  • An elongated dendritic crystal of silicon having a plural odd number of parallel twin planes extending entirely therethrough and having fiat parallel surfaces of a width of from 20 to 200 mils and of a thickness of from 1 to 25 mils, the surfaces being parallel to, the twin planes and comprising a series of flat faces, the faces having a planarity of the order of a wavelength of light, each face differing from adjacent faces in a step of the order of 50 angstroms, the surface of the material at the faces having essentially perfect (111) orientation, the dendrite being substantially free of imperfections at the flat surfaces throughout its length and being sufficiently uniform forusealong its entire length for semiconductor devices.
  • An elongated dendritic crystal of a solid material crystallizing in the diamond cubic lattice structure the material being doped with an impurity selected from the group consisting of donor and acceptor impurities, the crystal having a plural odd number of parallel interior twin planes, the crystal having a thickness of from 1 to 25'mils,the crystal having flat exterior surfaces parallel to the twin planes and comprising a series of flat faces, the faces of the crystal being substantially fiat and parallel within a wavelength of light, each face differing from adjacent faces in a step of the order of 50 angstroms, the faces having essentially perfect (111) orientation and free from any mechanical working, the dendritic crystal being substantially free of imperfections at the flat surfaces throughout its length and being sufficiently uniform for use along substantially its entire length for semiconductor devices.
  • a dendritic crystal of a solid material crystallizing in the diamond cubic lattice structure selected from the group consisting of silicon, germanium and stoichiometric compounds having an average of four valence electrons per atom, the dendritic crystal being of a thickness of from 1 to 25 mils and a width of from to 200 mils, and having three parallel twin planes extending entirely therethrough, and two fiat exterior surfaces parallel to the twin planes and comprising a series of flat parallel faces having a high degree of'planarity of the order of a wavelength of light, each face differing from adjacent faces in a step of the order of 50 angstroms, the surface of the material at the faces having essentially perfoot (111) orientation, the dendritic crystal being substantially free of imperfections at the flat surfaces throughout its length and being sufficiently uniform for use along substantially its entire length for semiconductor devices.
  • the steps comprising bringing a seed crystal having at least two parallel interior twin planes in the 211 direction extending entirely therethrough in contact with the melt so that it is wetted by the melt, the dendritic crystal when etched exhibiting triangular etch pits on both faces with the vertices of the etch pits directed in the direction of growing of the dendritic crystals, supercooling the melt to a selected temperature and pulling the seed crystal with respectto the melt while maintaining the selected temperature whereby material from the melt solidifies thereon to produce an elongated fiat dendritic crystal.
  • the steps comprising bringing aseed crystal-having a plural odd number of interior twin planes extending entirely therethrough the planes extending in the 2ll direction in contact with the melt so that it is wetted by the melt, the dendritic crystal when etched exhibiting triangular etch pits on both faces with the vertices of the etch pits directed in.
  • the steps comprising bringing a seed crystal having three parallel 1nter1or twin planes extending entirely therethrough in contact with the melt so that it is wetted by the melt, the three twin planes being substantially perpendicular to the surface of the melt, the dendritic crystal when etched exhibiting triangular etch pits on bothfaces with the vertices of the etch pits directed in the direction of pulling of the dendritic crystal, supercooling the melt to a selected temperature and pulling the seed crystal with respect to the melt while maintaining the selected temperature whereby material from the melt solidifies-thereon to produce an elongated flat surfaced dendritic crystal.
  • the steps comprising bringing a seed crystal having three parallel interior twin planes extending entirely therethrough in contact with the melt so that it is wetted by the melt, the dendritic crystal when etched exhibiting triangular etch pits on both faces with with the vertices of the etch pits directed in the direction of pulling of the dendritic crystal, supercooling the melt to a selected temperature and pulling'the seed crystal in a 2l1 direction parallel to the twin planes with respect to the melt while maintaining the selected temperature, whereby material from the melt solidifies thereon to produce an elongated fiat dendritic crystal and maintaining a low temperature gradient of the order of C.
  • the dendritic crystal In the process of producing thin flat crystals of a solid material crystallizingin the diamond cubic lattice structure selected from the group consisting of silicon, germanium, and stoichiometric compounds having an average of four valence electrons per atom, the steps comprising melting a quantity of the material, bringing the melt to a temperature slightly above the melting point of the material, contacting a surface of the melted material with a seed crystal of the material for a period of time to wet the seed crystal with the melted material, the crystal having three parallelinterior twin planes extending entirely through the seed crystal, the twin planes being parallel to 2l-1 direction, the crystal having a l1l direction parallel to the surface of the melt and a 211 direction perpendicular to the surface of the melt, the dendritic crystal
US844288A 1958-08-28 1959-10-05 Process for producing crystals and the products thereof Expired - Lifetime US3031403A (en)

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Application Number Priority Date Filing Date Title
NL241834D NL241834A (de) 1958-08-28
NL113205D NL113205C (de) 1958-08-28
CH7589659A CH440226A (de) 1958-08-28 1959-07-17 Verfahren zum Ziehen von Kristallen aus der Schmelze
GB27537/59A GB889058A (en) 1958-08-28 1959-08-12 Improvements in or relating to the production of crystals
DEW26266A DE1291320B (de) 1958-08-28 1959-08-25 Verfahren zum Ziehen dendritischer Kristalle
FR803725A FR1244924A (fr) 1958-08-28 1959-08-27 Procédé de fabrication de cristaux semi-conducteurs
US844288A US3031403A (en) 1958-08-28 1959-10-05 Process for producing crystals and the products thereof
GB13783/60A GB913674A (en) 1958-08-28 1960-04-20 Improvements in or relating to the production of crystals
DEW27847A DE1302031B (de) 1958-08-28 1960-05-12 Verfahren zum Ziehen dendritischer Kristalle
FR828125A FR77774E (fr) 1958-08-28 1960-05-24 Procédé de fabrication de cristaux semi-conducteurs
CH1114860A CH475014A (de) 1958-08-28 1960-10-04 Verfahren zum Ziehen von Kristallen aus der Schmelze

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US3124452A (en) * 1964-03-10 figure
US3130040A (en) * 1960-03-21 1964-04-21 Westinghouse Electric Corp Dendritic seed crystals having a critical spacing between three interior twin planes
US3144357A (en) * 1959-07-23 1964-08-11 Nat Res Dev Preparation of semiconductor materials
US3152022A (en) * 1962-05-25 1964-10-06 Bell Telephone Labor Inc Epitaxial deposition on the surface of a freshly grown dendrite
US3154384A (en) * 1960-04-13 1964-10-27 Texas Instruments Inc Apparatus for growing compound semiconductor crystal
US3192072A (en) * 1960-12-08 1965-06-29 Slemens & Halske Ag Method of pulling a dendritic crystal from a vapor atmosphere
US3201665A (en) * 1961-11-20 1965-08-17 Union Carbide Corp Solid state devices constructed from semiconductive whishers
US3206406A (en) * 1960-05-09 1965-09-14 Merck & Co Inc Critical cooling rate in vapor deposition process to form bladelike semiconductor compound crystals
US3212858A (en) * 1963-01-28 1965-10-19 Westinghouse Electric Corp Apparatus for producing crystalline semiconductor material
US3243320A (en) * 1963-03-18 1966-03-29 Fujitsu Ltd Method of producing semiconductor dendrites having both planes uniform
US3244486A (en) * 1962-08-23 1966-04-05 Westinghouse Electric Corp Apparatus for producing crystals
US3261671A (en) * 1963-11-29 1966-07-19 Philips Corp Device for treating semi-conductor materials by melting
US3278342A (en) * 1963-10-14 1966-10-11 Westinghouse Electric Corp Method of growing crystalline members completely within the solution melt
US3291571A (en) * 1963-12-23 1966-12-13 Gen Motors Corp Crystal growth
US3293002A (en) * 1965-10-19 1966-12-20 Siemens Ag Process for producing tape-shaped semiconductor bodies
US3341376A (en) * 1960-04-02 1967-09-12 Siemens Ag Method of producing crystalline semiconductor material on a dendritic substrate
US3344002A (en) * 1961-11-24 1967-09-26 Siemens Ag Method of producing epitaxial layers on semiconductor monocrystals
US3427211A (en) * 1965-07-28 1969-02-11 Ibm Process of making gallium phosphide dendritic crystals with grown in p-n light emitting junctions
US3650703A (en) * 1967-09-08 1972-03-21 Tyco Laboratories Inc Method and apparatus for growing inorganic filaments, ribbon from the melt
US3933981A (en) * 1973-11-30 1976-01-20 Texas Instruments Incorporated Tin-lead purification of silicon
DE3100245A1 (de) * 1980-01-07 1982-01-14 Emanuel M. 02178 Belmont Mass. Sachs Verfahren und vorrichtung zum kontinuierlichen zuechten von kristallinen oder halb-kristallinen bandaehnlichen koerpern aus einer schmelze
US6217286B1 (en) * 1998-06-26 2001-04-17 General Electric Company Unidirectionally solidified cast article and method of making
US20040139910A1 (en) * 2002-10-18 2004-07-22 Sachs Emanuel Michael Method and apparatus for crystal growth
US20050051080A1 (en) * 2002-10-30 2005-03-10 Wallace Richard Lee Method and apparatus for growing multiple crystalline ribbons from a single crucible
US20190148422A1 (en) * 2017-11-14 2019-05-16 Taiwan Semiconductor Manufacturing Co., Ltd. High absorption structure for semiconductor device

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BE631688A (de) * 1961-03-27 1900-01-01
DE1257754B (de) * 1963-01-29 1968-01-04 Fuji Tsushinki Seizo Kabushiki Verfahren und Vorrichtung zum Herstellen von Dendriten aus Halbleitermaterial
US4125425A (en) * 1974-03-01 1978-11-14 U.S. Philips Corporation Method of manufacturing flat tapes of crystalline silicon from a silicon melt by drawing a seed crystal of silicon from the melt flowing down the faces of a knife shaped heated element
US4121965A (en) * 1976-07-16 1978-10-24 The United States Of America As Represented By The Administrator Of The National Aeronautics & Space Administration Method of controlling defect orientation in silicon crystal ribbon growth

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GB769426A (en) * 1953-08-05 1957-03-06 Ass Elect Ind Improvements relating to the manufacture of crystalline material

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GB769426A (en) * 1953-08-05 1957-03-06 Ass Elect Ind Improvements relating to the manufacture of crystalline material

Cited By (35)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3124452A (en) * 1964-03-10 figure
US3144357A (en) * 1959-07-23 1964-08-11 Nat Res Dev Preparation of semiconductor materials
US3130040A (en) * 1960-03-21 1964-04-21 Westinghouse Electric Corp Dendritic seed crystals having a critical spacing between three interior twin planes
US3341376A (en) * 1960-04-02 1967-09-12 Siemens Ag Method of producing crystalline semiconductor material on a dendritic substrate
US3154384A (en) * 1960-04-13 1964-10-27 Texas Instruments Inc Apparatus for growing compound semiconductor crystal
US3206406A (en) * 1960-05-09 1965-09-14 Merck & Co Inc Critical cooling rate in vapor deposition process to form bladelike semiconductor compound crystals
US3192072A (en) * 1960-12-08 1965-06-29 Slemens & Halske Ag Method of pulling a dendritic crystal from a vapor atmosphere
US3201665A (en) * 1961-11-20 1965-08-17 Union Carbide Corp Solid state devices constructed from semiconductive whishers
US3344002A (en) * 1961-11-24 1967-09-26 Siemens Ag Method of producing epitaxial layers on semiconductor monocrystals
US3152022A (en) * 1962-05-25 1964-10-06 Bell Telephone Labor Inc Epitaxial deposition on the surface of a freshly grown dendrite
US3244486A (en) * 1962-08-23 1966-04-05 Westinghouse Electric Corp Apparatus for producing crystals
US3212858A (en) * 1963-01-28 1965-10-19 Westinghouse Electric Corp Apparatus for producing crystalline semiconductor material
US3243320A (en) * 1963-03-18 1966-03-29 Fujitsu Ltd Method of producing semiconductor dendrites having both planes uniform
US3278342A (en) * 1963-10-14 1966-10-11 Westinghouse Electric Corp Method of growing crystalline members completely within the solution melt
US3261671A (en) * 1963-11-29 1966-07-19 Philips Corp Device for treating semi-conductor materials by melting
US3291571A (en) * 1963-12-23 1966-12-13 Gen Motors Corp Crystal growth
US3427211A (en) * 1965-07-28 1969-02-11 Ibm Process of making gallium phosphide dendritic crystals with grown in p-n light emitting junctions
US3293002A (en) * 1965-10-19 1966-12-20 Siemens Ag Process for producing tape-shaped semiconductor bodies
US3650703A (en) * 1967-09-08 1972-03-21 Tyco Laboratories Inc Method and apparatus for growing inorganic filaments, ribbon from the melt
US3933981A (en) * 1973-11-30 1976-01-20 Texas Instruments Incorporated Tin-lead purification of silicon
DE3100245A1 (de) * 1980-01-07 1982-01-14 Emanuel M. 02178 Belmont Mass. Sachs Verfahren und vorrichtung zum kontinuierlichen zuechten von kristallinen oder halb-kristallinen bandaehnlichen koerpern aus einer schmelze
US6217286B1 (en) * 1998-06-26 2001-04-17 General Electric Company Unidirectionally solidified cast article and method of making
US20040139910A1 (en) * 2002-10-18 2004-07-22 Sachs Emanuel Michael Method and apparatus for crystal growth
US20060249071A1 (en) * 2002-10-18 2006-11-09 Evergreen Solar, Inc. Method and apparatus for crystal growth
US20080105193A1 (en) * 2002-10-18 2008-05-08 Evergreen Solar, Inc. Method and Apparatus for Crystal Growth
US7407550B2 (en) 2002-10-18 2008-08-05 Evergreen Solar, Inc. Method and apparatus for crystal growth
US7708829B2 (en) 2002-10-18 2010-05-04 Evergreen Solar, Inc. Method and apparatus for crystal growth
US7718003B2 (en) 2002-10-18 2010-05-18 Evergreen Solar, Inc. Method and apparatus for crystal growth
US20050051080A1 (en) * 2002-10-30 2005-03-10 Wallace Richard Lee Method and apparatus for growing multiple crystalline ribbons from a single crucible
US7022180B2 (en) 2002-10-30 2006-04-04 Evergreen Solar, Inc. Method and apparatus for growing multiple crystalline ribbons from a single crucible
US20060191470A1 (en) * 2002-10-30 2006-08-31 Wallace Richard L Jr Method and apparatus for growing multiple crystalline ribbons from a single crucible
US7507291B2 (en) 2002-10-30 2009-03-24 Evergreen Solar, Inc. Method and apparatus for growing multiple crystalline ribbons from a single crucible
US20190148422A1 (en) * 2017-11-14 2019-05-16 Taiwan Semiconductor Manufacturing Co., Ltd. High absorption structure for semiconductor device
US11088189B2 (en) * 2017-11-14 2021-08-10 Taiwan Semiconductor Manufacturing Co., Ltd. High light absorption structure for semiconductor image sensor
US11791358B2 (en) 2017-11-14 2023-10-17 Taiwan Semiconductor Manufacturing Co., Ltd. Method of forming semiconductor device

Also Published As

Publication number Publication date
GB913674A (en) 1962-12-28
GB889058A (en) 1962-02-07
DE1291320B (de) 1969-03-27
DE1302031B (de) 1969-10-16
NL113205C (de) 1900-01-01
FR1244924A (fr) 1960-11-04
CH440226A (de) 1967-07-31
NL241834A (de) 1900-01-01
CH475014A (de) 1969-07-15

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