Classifications

• • 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
  • C30B1/00—Single-crystal growth directly from the solid state
  • C30B1/02—Single-crystal growth directly from the solid state by thermal treatment, e.g. strain annealing
• • 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
  • C30B23/00—Single-crystal growth by condensing evaporated or sublimed materials
  • C30B23/002—Controlling or regulating
  • C30B23/005—Controlling or regulating flux or flow of depositing species or vapour
• • 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
  • C30B23/00—Single-crystal growth by condensing evaporated or sublimed materials
  • C30B23/02—Epitaxial-layer growth
  • C30B23/025—Epitaxial-layer growth characterised by the substrate
• • 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
  • C30B25/00—Single-crystal growth by chemical reaction of reactive gases, e.g. chemical vapour-deposition growth
  • C30B25/02—Epitaxial-layer growth
  • C30B25/16—Controlling or regulating
  • C30B25/165—Controlling or regulating the flow of the reactive gases
• • 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
  • C30B25/00—Single-crystal growth by chemical reaction of reactive gases, e.g. chemical vapour-deposition growth
  • C30B25/02—Epitaxial-layer growth
  • C30B25/18—Epitaxial-layer growth characterised by the substrate
  • C30B25/183—Epitaxial-layer growth characterised by the substrate being provided with a buffer layer, e.g. a lattice matching layer
• • 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
  • C30B25/00—Single-crystal growth by chemical reaction of reactive gases, e.g. chemical vapour-deposition growth
  • C30B25/02—Epitaxial-layer growth
  • C30B25/18—Epitaxial-layer growth characterised by the substrate
  • C30B25/186—Epitaxial-layer growth characterised by the substrate being specially pre-treated by, e.g. chemical or physical means
• • 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
  • C30B29/10—Inorganic compounds or compositions
  • C30B29/40—AIIIBV compounds wherein A is B, Al, Ga, In or Tl and B is N, P, As, Sb or Bi
  • C30B29/403—AIII-nitrides
• • 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
  • C30B29/10—Inorganic compounds or compositions
  • C30B29/52—Alloys

Definitions

• the example embodiments of the present invention generally pertain to semiconductor materials, methods, and devices, and more particularly to a multilayer substrate structure for epitaxial growth of group III-V compound semiconductors and a system for manufacturing the same.
• Group III-V compound semiconductor such as gallium nitride (GaN), gallium arsenide (GaAs), indium nitride (InN), aluminum nitride (A1N) and gallium phosphide (GaP), are widely used in the manufacture of electronic devices, such as microwave frequency integrated circuits, light-emitting diodes, laser diodes, solar cells, high-power and high-frequency electronics, and opto-electronic devices. To improve throughput and reduce manufacturing cost it is desired to increase size (e.g., diameter) of substrates.
• GaN gallium nitride
• GaAs gallium arsenide
• InN indium nitride
• AlN aluminum nitride
• GaP gallium phosphide
• III-V compound semiconductors of large size is very expensive a great number of foreign materials including metals, metal oxides, metal nitrides as well as semiconductors, such as silicon carbide (SiC), sapphire and silicon, are commonly used as substrates for epitaxial growth of III-V compound semiconductors.
• semiconductors such as silicon carbide (SiC), sapphire and silicon
• group III-V compound semiconductors e.g., GaN
• substrates e.g., sapphire
• crystalline quality e.g., grain boundaries, dislocations and other extended defects, and point defects
• Differences in the coefficient of thermal expansion between the GaN layer and the underlying substrate result in large curvatures across the wafer, resulting during and post processing upon returning to room temperature, and the large mismatch in lattice constants leads to a high dislocation density, unwanted strain and defects propagating into the epitaxial GaN layer.
• stress relaxation strategies are employed, such as growing buffer layers between the GaN layer and the sapphire substrate, or counter balancing compressive and tensile strain by alternating appropriate material layers.
• the dislocation density may remain high and the manufacturing cost and complexity increases significantly because of the use of the same deposition techniques involved in growing the active device layers.
• MBE molecular beam epitaxy
• MOCVD metal organic chemical vapor deposition
• ALD atomic layer deposition
• ALE atomic layer epitaxy
• Zone melt recrystallization While some techniques such as Zone melt recrystallization (ZMR) are designed to improve quality crystalline material they may suffer from the drawback that the temperature generated for melting a portion of the deposited film may exceed the maximum temperature that can be handled by the underlying substrate. To prevent the underlying substrate from being heated to the melting point of the deposited film, the heating time may be shortened. However, shortening the heating time means that while solidifying, the crystal structure may grow in vertical direction rather than in both vertical and lateral directions simultaneously. Hence, epitaxial growth may be dominated in the vertical direction rather than the lateral direction resulting in patches of small grains along the substrate.
• ZMR Zone melt recrystallization
• a multilayer substrate structure comprises a substrate, a thermal matching layer formed on the substrate a lattice matching layer above the thermal matching layer.
• the thermal matching layer includes at least one of molybdenum, molybdenum-copper, mullite, sapphire, graphite, aluminum-oxynitrides, silicon, silicon carbide, zinc oxides, and rare earth oxides.
• the lattice matching layer includes a first chemical element and a second chemical element to form an alloy. The first and second chemical element has similar crystal structures and chemical properties.
• the coefficient thermal expansion of the thermal matching layer is approximately equal to that of a member of group III-V compound semiconductors.
• a method of fabricating a multilayer substrate structure comprises providing a substrate, growing a thermal matching layer on the substrate.
• the thermal matching layer comprises at least one of molybdenum, molybdenum-copper, mullite, sapphire, graphite, aluminum- oxynitrides, silicon, silicon carbide, zinc oxides, and rare earth oxides.
• the method also comprises growing a lattice matching layer above the thermal matching layer.
• the lattice matching layer includes a first chemical element and a second chemical element to form an alloy.
• the first and second chemical element has similar crystal structures and chemical properties.
• the coefficient thermal expansion of the thermal matching layer is approximately equal to that of a member of group III-V compound semiconductors.
• a method of depositing a film on a substrate comprise directing source material from a material source onto a surface of the substrate using a line-of-sight deposition method, blocking a predetermined portion of the substrate with a shutter disposed between the substrate and the source material to create a blocked substrate portion and an unblocked substrate portion to prevent deposition of source material onto the initial blocked portion of the substrate and causing relative movement between the shutter and the substrate such that the blocked substrate portion decreases and the unblocked substrate portion increases, thereby creating a moving lateral growth boundary resulting in lateral epitaxial growth across the substrate.
• a system of depositing a film on a substrate comprises a lateral control shutter.
• the lateral control shutter is disposed between the substrate and a source material and configured to block a portion of the substrate to prevent deposition of source material onto the blocked portion of the substrate.
• One of the lateral control shutter and/or the substrate moves with respect to the other to form a moving lateral growth boundary edge resulting in lateral epitaxial deposition across the substrate and the formation of a crystallographic film across the surface of the substrate with large grain sizes.
• FIGS. 1A-1D illustrate example cross-sectional views of exemplary multilayer substrate structures in accordance with exemplary embodiments
• FIG. 2A illustrates a schematic of a hexagonal close-packed structure
• FIG. 2B illustrates a schematic of a unit cell showing lattice constants
• FIG. 3 illustrates a periodic table
• FIG. 4 illustrates a phase diagram correlation between transition temperature and atomic percentage of constituent elements in accordance with an exemplary embodiment
• FIG. 5 illustrates an example system of depositing a film on a substrate in accordance with an exemplary embodiment
• FIGS. 6A-6C illustrate exemplary angular distributions of vaporized material in a sputtering deposition process
• FIGS. 7A-7D illustrate example methods of growing large extended crystals on the substrate in accordance with exemplary embodiments of the present invention.
• FIG. 1A illustrates an example cross-sectional view of an exemplary multilayer substrate structure 100 in accordance with an exemplary embodiment.
• the multilayer substrate structure 100 may include a substrate 102 and an epitaxial layer 104 epitaxially grown on the substrate 100.
• the substrate 102 may comprise a semiconductor material, a compound semiconductor material, or other type of material such as a metal or a non- metal.
• the material may comprise molybdenum, molybdenum-copper, mullite, sapphire, graphite, aluminum- oxynitrides, silicon, silicon carbide, zinc oxides and rare earth oxides, and/or other suitable material.
• the epitaxial layer 104 may include group III-V compound semiconductors, such as aluminum nitride (A1N), gallium nitride (GaN), indium gallium nitride (InGaN) and indium nitride (InN).
• group III-V compound semiconductors such as aluminum nitride (A1N), gallium nitride (GaN), indium gallium nitride (InGaN) and indium nitride (InN).
• AlN aluminum nitride
• GaN gallium nitride
• InGaN indium gallium nitride
• InN indium nitride
• the lattice matching layer 106 may comprise two or more constituent elements, for example of two constituents, a first chemical element and a second chemical element, to form an alloy.
• the first chemical element is miscible with the second chemical element in this alloy.
• the constituent elements may have similar crystal structures at room temperature, such as hexagonal close-packed structure, as shown in FIG. 2A.
• Each of the constituent elements may have its respective lattice constants including lattice parameters along a-axis, b-axis and c-axis, and lattice parameters of interaxial angles ⁇ , ⁇ and ⁇ , as shown in FIG. 2B.
• the constituent elements may have similar chemical properties.
• the first and second chemical elements may both belong to group four elements (namely, titanium (Ti), zirconium (Zr), hafnium (Hf) and rutherfordium (Rf)) in periodic table illustrated in FIG. 3.
• the alloy may be made from elements Ti and Zr, elements Ti and Hf, and elements Zr and Hf and may have similar crystal structure to the constituent elements at room temperature, or by any combination of 2.
• the alloy may comprise a third chemical element or more elements which have similar crystal structures and similar chemical properties.
• a linear relation may exist between the first and second chemical elements and their associated lattice parameters at constant temperature to allow the lattice constant of the lattice matching layer 106 to be approximately equal to that of the epitaxial layer 104.
• the mole fraction in atomic percentage of the first chemical element to the second chemical element is Pi to (1-Pi).
• the mole fraction may vary from application to application, as the composition will control the resulting lattice parameter value of the alloy.
• atomic percentage P & of Zr may be greater than 75% and less than 90%. For example, P & may be about 86%. It follows that atomic percentage ⁇ of Ti is (1-Pz r ).
• a first lattice parameter of Zr e.g., a-axis lattice parameter ⁇ 3 ⁇ 4 r is 3.23A.
• a second lattice parameter of Ti e.g., a-axis lattice parameter an is 2.951A.
• the atomic percentage of the first chemical element to the second chemical element may be about 43% to 57% or 99% to 1%.
• the constituent elements of the lattice matching layer 106 and/or the mole fractions of the constituent elements may be adjusted to make the lattice constant of the lattice matching layer 106 accommodate that of the epitaxial layer 104.
• the epitaxial layer 104 comprises A1N and the constituent elements of the lattice matching layer 106 are Zr and Ti, the atomic percentage of Zr may be adjusted to be lower than 75% and higher than 50%.
• the atomic percentage of Zr may be greater than 90%.
• the thickness of the epitaxial layer 104 may cause the changes of the selection of the constituent elements as well as mole fraction of the constituent elements to achieve 100% lattice match. Despite the changes of the thickness of the epitaxial layer 104, it may be in a range of 5nm-500nm. In other words, the thickness and the material of the epitaxial layer 104 may determine the selection of the constituent elements and their mole fraction in forming the lattice matching layer 106.
• the epitaxial layer 104 is epitaxially grown on the lattice matching layer 106 to transfer the crystallographic pattern of the lattice matching layer 106 to the epitaxial layer 104.
• the lattice matching layer 106 may be formed on the underlying layer, for example, the substrate 102 using one of deposition techniques, such as vacuum evaporation, sputtering, molecular beam epitaxy and pulsed laser deposition, atmospheric chemical vapor deposition, and atomic layer deposition.
• the epitaxial deposition method such as metal organic chemical vapor deposition and atomic layer deposition and/or any other suitable methods for epitaxial growth, may be performed in a temperature range of 700°C ⁇ 850°C.
• the multilayer substrate structure may be heated by any heating methods/heat sources under the ⁇ - ⁇ phase transition temperature 780°C but greater than 700 °C in an attempt to transfer the crystallographic pattern of the lattice matching layer 106 to the epitaxial layer 104 in a phase, avoiding ⁇ phase transition.
• the temperature for heating the multilayer substrate structure during subsequent MQW growth, along with any additional device layers, can be raised above or lowered below 780 °C since epitaxial layer 104 has been formed and is permanently set in the a phase.
• the temperature may be initially raised above the ⁇ - ⁇ phase transition and then immediately dropped below ⁇ - ⁇ phase transition temperature to invoke generating phase transition free energy to crystallize large lateral areas resulting in single crystal a-phase in the lattice matching layer.
• the lattice matching layer 106 By introducing the lattice matching layer 106, the stresses may be lowered that might otherwise occur in the epitaxial layer 104 developed during the epitaxy growth as a result of difference in lattice constants between the substrate 102 and the epitaxial layer 104, and by doing so, aids in the growth of a high crystalline quality epitaxial layer 104. If such stress is not relieved by the lattice matching layer, the stress may cause defects in the crystalline structure of the epitaxial layer 104. Defects in the crystalline structure of the epitaxial layer 104, in turn, would make it difficult to achieve a high quality crystalline structure in epitaxy for any subsequent device growth.
• the lattice matching layer 106 is also disclosed in U.S. patent application entitled "A Lattice Matching Layer for Use In A Multilayer Substrate Structure.”
• the substrate 102 may comprise a semiconductor material, a compound semiconductor material, or another type of material such as a metal or a non- metal.
• the substrate 102 may be in the form of a polycrystalline solid.
• Polycrystalline substrates may negatively impact the lattice matching layer 106 by making it polycrystalline instead of single crystal, thus enlarging the difference of lattice constants between the lattice matching layer 106 and the epitaxial layer 104 (an average lattice constant over multiple grains and multiple crystalline orientations), and causing extended defects such as threading dislocations or grain boundaries, leading to poor crystalline quality of the epitaxial layer 104.
• an amorphous layer 108 may be introduced between the polycrystalline substrate 102 and the lattice matching layer 106, as shown in FIG. IB.
• the impact of the polycrystalline substrate 102 on the lattice matching layer 106 may be reduced. In this way, only crystallography of the lattice matching layer 106 is transferred to the epitaxial layer 104.
• the amorphous layer 108 may comprise, but not limited to, one of silicon dioxide, silicon nitride, tantalum nitride, boronitride, tungsten nitride, glassy amorphous carbon, silicate glass (e.g., borophosphosilicate glass and phosphosilicate glass) and/or other suitable materials.
• the amorphous layer 108 may have a thickness of 5nm to 100 nm.
• the coefficient of thermal expansion of the substrate 102 may be different than that of the above layers, resulting in large substrate curvatures.
• the coefficient of thermal expansion of the substrate 102 is greater than that of the above layers, biaxial compressive strain arises (e.g. when the substrate comprises sapphire).
• the coefficient of thermal expansion of the substrate is less than that of the above layers, tensile strain arises (e.g. when the substrate comprises silicon).
• the substrate may be used as a thermal matching layer 102a (shown in FIGS.
• the thermal matching layer 102a may comprise molybdenum or its related alloys.
• the coefficient of thermal expansion of molybdenum is about 5.4xl0 "6 / K which is approximately equal to that of some group III-V compound semiconductors, such as GaN.
• the substrate may be fabricated using a variety of methods for growth of metals, crystals, and their alloys.
• Example may include Czochralski, float zone (FZ), directional solidification (DS), zone melt recrystallization (ZMR), sintering, isostatic pressing, electro-chemical plating, plasma torch deposition, and/or other suitable methods.
• the thermal matching layer 102a has a thickness in a range of 5nanometer to 1 millimeter.
• the strain caused by the thermal expansion mismatch and lattice mismatch may be reduced or completely eliminated.
• the dislocation density may be less than 10 2 /cm 2 ( ⁇ 100 dislocations per square centimeter) in the resulting epitaxial layer 104.
• the reduction or elimination of the strain may fulfill requirements to overcome the so-called "green gap.”
• the "green gap” is an industry expression for a droop or decrease in LED light output from MQW LEDs that alloy indium with GaN to fabricate green LED's. This droop in green light outputted occurs for forward currents >50mA in 1 to 5 square millimeter device areas due to defect density resulting from excessive strain from substrates, stress induced extended defects and point defects propagating into active MQW device layers.
• the present embodiment enables high crystalline quality devices grown on layer 104.
• exemplary embodiments of the present invention qualify a cost effective manner of manufacturing a green LED crystalline template. As such, the fulfilling of the "green gap" may enhance the high performance of white light emitting diodes based on mixing light from red, green and blue, having the highest theoretical efficacies over phosphor based down conversion LEDs used today.
• FIG. 5 illustrates a system 500 of depositing a film on a substrate in accordance with an exemplary embodiment
• a lateral control shutter 506 is employed and disposed between the substrate 504 and a material source 508.
• the material source 508 is configured to deposit source material onto substrate surface using a suitable deposition method. Depending on the deposition method employed, the source material may be vaporized from a solid or liquid source in the form of atoms or molecules and transported as a vapor through a vacuum or low- pressure gas or plasma environment to the substrate.
• the vaporized material may be an element, alloy, or compound in various charged states.
• vaporized material has a long mean free path greater than 1 meter and the trajectory of the vaporized material may be considered direct line-of-sight.
• the deposition process employed is therefore defined as light-of-sight deposition.
• Line-of-sight deposition methods may be physical vapor deposition or chemical vapor deposition, including vacuum evaporation, sputtering, pulsed laser deposition, molecular beam epitaxy, atomic layer deposition, atomic layer epitaxy, plasma torch deposition and/or any other suitable methods.
• the chemical vapor deposition may be atmospheric chemical vapor deposition and/or any other suitable chemical vapor deposition methods.
• the vacuum evaporation includes thermal evaporation, laser beam or focused lamp evaporation, arc-discharge evaporation and electron-beam evaporation.
• the sputtering method may comprise one of direct current sputtering, magnetron sputtering, radio frequency sputtering, and pulsed laser sputtering.
• distance LI between the material source 508 and the substrate 504 may be less than the mean free path of the gas molecules thus allowing most of the molecules in a gas to arrive in a collimated manner.
• distance L2 between the lateral control shutter 506 and the substrate surface may be less than the mean free path of the gas molecules.
• the mean free path is defined as the average distance a gas molecule travels before colliding with another gas molecule.
• the substrate 504 may comprise of silicon dioxide, silicon nitride, amorphous boronitride, amorphous tungsten nitride, glassy amorphous carbon, amorphous rare earth oxides, amorphous zinc- oxide, and silicate glass.
• Different deposition processes may have different flux angular distributions at the substrate.
• a collimator may be employed and placed between the substrate and the sputtering target in a magnetron sputtering system.
• the employment of the collimator tends to reduce the non-normal flux from the sputtering target resulting in an increase of the directionality of the deposit.
• the angular distribution of collimated incidence are shown in FIG. 6B.
• a fraction of the sputtered atoms are ionized.
• the overall angular distribution is viewed as a superposition of a cosine and directional angular distribution as shown in FIG. 6C.
• the angle of incidence of evaporated material onto the substrate may affect the film properties, crystal orientation and other
• the vaporized material may be deposited onto the substrate surface at normal angle-of- incidence or off-normal angle-of-incidence.
• the source material may be deposited at angles of incidence of -15° to +15°.
• the mean angle-of-incidence of the depositing atom flux may vary depending on deposition geometry, type of
• the lateral control shutter 506 is employed to control film growth.
• the lateral control shutter 506 may define a lateral boundary (not numbered) of the depositing thin film 502 and cover some predetermined portion of the substrate 504 to prevent deposition of source material onto portions of the substrate surface.
• the lateral boundary of the depositing thin film 502 is moved and controlled to advance the growing edge of the film to facilitate the lateral epitaxial deposition across the substrate.
• the lateral control shutter 506 is moved with respect to the substrate 504 in direction A.
• the lateral control shutter may remain static while the substrate moves with respect to the lateral control shutter.
• both the lateral control shutter and the substrate may move at a different speed to achieve relative movement there between.
• the system 500 may also include a drive system (not shown) to control the relative movement between the lateral control shutter and substrate.
• the system 500 may include a trailing control shutter 512 which is used to help mask any unwanted deposition onto the single crystal being left behind the advancing growing edge of the thin film 502. The latter assists in maintaining uniform film thickness across the thin film 502. If a trailing control shutter is employed, the trailing control shutter 512 can be configured to avoid further epitaxial deposition onto the newly crystallized thin film 502 over the substrate 504.
• the system 500 may include different types of heat sources (e.g., heat source 510 in FIG. 5) to control the temperature of the substrate and/or provide elevated temperatures that may be used in the deposition process.
• heat sources are typically used to thermally evaporate source material, desorb deposited material from target source surfaces, heat substrates for cleaning and subsequent processing, melt source material, and add thermal kinetic energy or to enhance surface mobility of adatoms or molecules participating in the deposition process on the substrate surface. Heat may be generated in the vacuum chamber by a number of different techniques.
• the substrate may be heated by ion bombardment, electrons, optical radiation, inductive heating, or other heating techniques.
• the heat source may be embedded in or external to the system. Exemplary heat sources may include a radiant heater (infrared heating, lasers, and the like), hot wire radiative heating, focused lamp heating, inductive heating, direct metal pedestal heater, or ceramic pedestal heater.
• the epitaxial growth initially occurs in the direction substantially normal to the surface of the substrate, e.g., in a vertical direction, and then proceeds in a direction substantially parallel to the surface of the substrate, e.g., in a parallel direction.
• a lateral crystalline epitaxial growth is illustrated in FIG. 7A.
• the lateral control shutter 706 moves from the left end 712 of the substrate toward the other end of the substrate (not shown), allowing the epitaxial growth to start from the left end 712.
• a plurality of grains at many points on the left end 712 may grow and serve as seed crystals for subsequent crystal growth. Crystals initially grow in a vertical direction. With the movement between the lateral control shutter 706 and the substrate, crystals may grow in the lateral direction and the vertical direction simultaneously.
• Grain size of the deposited film plays an important role in its electrical properties. As the grain size increases, the number of grain boundaries per unit area and the number of boundary interfaces decrease. For example, a high density of grain boundaries, e.g., a small grain size, or extended defects in the crystal structure, tends to decrease the electrical and thermal conductivity of the deposited film. Hence it is desirable to increase grain size where possible. Exemplary embodiments of achieving minimum grain boundaries and minimum number of grains on the substrate are illustrated in FIGS. 7B-7D.
• the lateral control shutter 706 is placed between the substrate (not shown) and the material source (not shown) and covers a portion of the substrate, leaving a region (e.g., region 714) exposed to the material source.
• the region 414 may have a sharp corner or an edge.
• the sharp corner is a corner of the substrate made by adjusting the placement of the lateral control shutter and the substrate.
• a self-selected seed grain 716 may grow at the sharp corner.
• the seed grain serves as a seed crystal to initiate crystallization and to provide a point for the deposition to begin.
• a crystal grows simultaneously in both the vertical and lateral directions across the entire surface of the substrate.
• graphoepitaxy may be employed for creating long-range order during thin film deposition on the substrate surface or during recrystallization of molten material on the substrate surface by patterning a portion of the substrate surface to form a surface relief structure, e.g., surface relief structure 720.
• the surface relief structure 720 may serve as a template for growing a seed grain on the substrate and induce a desired crystallographic orientation in the newly growing thin film.
• the seed grain is then employed to initiate crystallization and to provide a point of origin for the depositing film to begin. Similar to the embodiment illustrated in FIG.
• the surface relief structure 720 may be made by a variety of lithography techniques, such as optical lithography, electron beam lithography, nanoimprint lithography, or focused-ion-beam (FIB) lithography and/or any other suitable lithography techniques.
• the surface relief structure 720 might be transferred or added to the corner or edge of the substrate by laser heating process or ablation.
• the seed grain may extrude out on the substrate plane as the growing edge advances away from the corner.
• a seed crystal 722 may be added to a point of the substrate, for example, a corner of the substrate.
• the seed crystal may be employed to initiate crystallization and to provide a point of origin for the depositing film to begin.
• the added seed crystal may extrude out on the substrate plane as the growing edge advances away from the corner.
• FIG. 7D illustrates a seed grain growing outward laterally beginning at a sharp corner of a region 724 of the substrate with the region exposed to the material source.
• the sharp corner in this embodiment is not made by adjusting the placement of the substrate and the lateral control shutter. Instead the sharp corner is shaped by a shutter having such a shape.
• a seed grain may grow at the sharp corner and serve as a seed crystal to initiate crystallization and to provide a point of origin for the deposition to begin.
• the added advantage of utilizing a triangle as shown, or a crescent with same curvature, is that through grain competition the grain boundaries will grow perpendicular to the shape of the shutter edge.
• the shutter may have various shapes according to different applications.
• the shutter may be in the shape of a polygon or an arc. A portion of the periphery of the polygon defines a shape with a sharp corner at which the seed grain grows.
• the shutter may be in the shape of rectangle, square, circle, triangle, crescent shape, or a "Chevron symbol" shape, and/or any other suitable shapes.
• the shutter can be used for any epitaxial thin film growth allowing crystals grow in lateral and vertical directions simultaneously on a substrate.
• the shutter can be used for growing a lattice matching layer in a multilayer substrate structure.

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• Chemical & Material Sciences (AREA)
• Organic Chemistry (AREA)
• Engineering & Computer Science (AREA)
• Crystallography & Structural Chemistry (AREA)
• Materials Engineering (AREA)
• Metallurgy (AREA)
• General Chemical & Material Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Inorganic Chemistry (AREA)
• Physics & Mathematics (AREA)
• Thermal Sciences (AREA)
• Recrystallisation Techniques (AREA)
• Crystals, And After-Treatments Of Crystals (AREA)
• Physical Vapour Deposition (AREA)
• Physical Deposition Of Substances That Are Components Of Semiconductor Devices (AREA)

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• 2013
  • 2013-06-12 CN CN201380043629.8A patent/CN104781938B/zh not_active Expired - Fee Related
  • 2013-06-12 KR KR1020157000842A patent/KR20150047474A/ko not_active Withdrawn
  • 2013-06-12 WO PCT/US2013/045482 patent/WO2013188574A2/en not_active Ceased
  • 2013-06-12 JP JP2015517401A patent/JP6450675B2/ja not_active Expired - Fee Related
  • 2013-06-12 EP EP13803800.5A patent/EP2862206A4/de not_active Withdrawn
  • 2013-06-14 TW TW102121007A patent/TWI518747B/zh not_active IP Right Cessation

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