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WO2015172014A1 - Substrats de saphir de haute qualité et procédé de fabrication desdits substrats de saphir - Google Patents

Substrats de saphir de haute qualité et procédé de fabrication desdits substrats de saphir Download PDF

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Publication number
WO2015172014A1
WO2015172014A1 PCT/US2015/029875 US2015029875W WO2015172014A1 WO 2015172014 A1 WO2015172014 A1 WO 2015172014A1 US 2015029875 W US2015029875 W US 2015029875W WO 2015172014 A1 WO2015172014 A1 WO 2015172014A1
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Prior art keywords
μηι
substrate
μιη
item
μγη
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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PCT/US2015/029875
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English (en)
Inventor
Maureen A. BROSNAN
Tigran DOLUKHANYAN
Christopher D. Jones
Haykaz Garegin PAPOYAN
Ramanujam Vedantham
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Saint Gobain Ceramics and Plastics Inc
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Saint Gobain Ceramics and Plastics Inc
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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B24—GRINDING; POLISHING
    • B24B—MACHINES, DEVICES, OR PROCESSES FOR GRINDING OR POLISHING; DRESSING OR CONDITIONING OF ABRADING SURFACES; FEEDING OF GRINDING, POLISHING, OR LAPPING AGENTS
    • B24B9/00—Machines or devices designed for grinding edges or bevels on work or for removing burrs; Accessories therefor
    • B24B9/02—Machines or devices designed for grinding edges or bevels on work or for removing burrs; Accessories therefor characterised by a special design with respect to properties of materials specific to articles to be ground
    • B24B9/06—Machines or devices designed for grinding edges or bevels on work or for removing burrs; Accessories therefor characterised by a special design with respect to properties of materials specific to articles to be ground of non-metallic inorganic material, e.g. stone, ceramics, porcelain
    • B24B9/065—Machines or devices designed for grinding edges or bevels on work or for removing burrs; Accessories therefor characterised by a special design with respect to properties of materials specific to articles to be ground of non-metallic inorganic material, e.g. stone, ceramics, porcelain of thin, brittle parts, e.g. semiconductors, wafers
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B24—GRINDING; POLISHING
    • B24B—MACHINES, DEVICES, OR PROCESSES FOR GRINDING OR POLISHING; DRESSING OR CONDITIONING OF ABRADING SURFACES; FEEDING OF GRINDING, POLISHING, OR LAPPING AGENTS
    • B24B37/00—Lapping machines or devices; Accessories
    • B24B37/04—Lapping machines or devices; Accessories designed for working plane surfaces
    • B24B37/07—Lapping machines or devices; Accessories designed for working plane surfaces characterised by the movement of the work or lapping tool
    • B24B37/08—Lapping machines or devices; Accessories designed for working plane surfaces characterised by the movement of the work or lapping tool for double side lapping
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B24—GRINDING; POLISHING
    • B24B—MACHINES, DEVICES, OR PROCESSES FOR GRINDING OR POLISHING; DRESSING OR CONDITIONING OF ABRADING SURFACES; FEEDING OF GRINDING, POLISHING, OR LAPPING AGENTS
    • B24B37/00—Lapping machines or devices; Accessories
    • B24B37/11—Lapping tools
    • B24B37/20—Lapping pads for working plane surfaces
    • B24B37/24—Lapping pads for working plane surfaces characterised by the composition or properties of the pad materials
    • B24B37/245—Pads with fixed abrasives
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B24—GRINDING; POLISHING
    • B24B—MACHINES, DEVICES, OR PROCESSES FOR GRINDING OR POLISHING; DRESSING OR CONDITIONING OF ABRADING SURFACES; FEEDING OF GRINDING, POLISHING, OR LAPPING AGENTS
    • B24B7/00—Machines or devices designed for grinding plane surfaces on work, including polishing plane glass surfaces; Accessories therefor
    • B24B7/20—Machines or devices designed for grinding plane surfaces on work, including polishing plane glass surfaces; Accessories therefor characterised by a special design with respect to properties of the material of non-metallic articles to be ground
    • B24B7/22—Machines or devices designed for grinding plane surfaces on work, including polishing plane glass surfaces; Accessories therefor characterised by a special design with respect to properties of the material of non-metallic articles to be ground for grinding inorganic material, e.g. stone, ceramics, porcelain
    • B24B7/228—Machines or devices designed for grinding plane surfaces on work, including polishing plane glass surfaces; Accessories therefor characterised by a special design with respect to properties of the material of non-metallic articles to be ground for grinding inorganic material, e.g. stone, ceramics, porcelain for grinding thin, brittle parts, e.g. semiconductors, wafers
    • H10P14/2921—
    • H10P14/2925—
    • H10P14/3416—

Definitions

  • the present disclosure relates to sapphire substrates, such as sapphire substrates with superior dimensional and shape qualities.
  • Semiconducting components based on single crystal nitride materials of Group-Ill and Group- V elements are ideal for devices such as light-emitting diodes (LED), laser diodes (LD), displays, transistors and detectors.
  • semiconductor elements utilizing Group-Ill and Group-V nitride compounds are useful for light emitting devices in the UV and blue/green wavelength regions.
  • gallium nitride (GaN) and related materials such as AlGaN, InGaN and combinations thereof, are the most common examples of nitride semiconductor materials in high demand.
  • nitride semiconducting materials have proven difficult for a multitude of reasons. Accordingly, epitaxial growth of nitride semiconducting materials on foreign substrate materials is considered a viable alternative.
  • Substrates including SiC (silicon carbide), AI 2 O 3 (sapphire or corundum), and MgAl 2 0 4 (spinel) are common foreign substrate materials.
  • Such foreign substrates have a different crystal lattice structure than nitride semiconducting materials, particularly GaN, and thus have a lattice mismatch.
  • nitride semiconducting materials particularly GaN
  • lattice mismatch Despite such mismatch and attendant problems such as stresses and defectivity in the overlying semiconductor materials layer, the industry demands large surface area, high quality substrates, particularly sapphire substrates.
  • challenges remain with the production of high quality substrates in larger sizes.
  • a substrate comprising a body including alumina wherein the body comprises at least one of the substrate characteristics selected from the group of:
  • SFQR site frontside least squares focal plane range
  • NSFQR normalized site frontside least squares focal plane range
  • GFLR global frontside least squares focal plane range
  • NTFLR normalized global frontside least squares focal plane range
  • each substrate of the batch comprises a body including alumina and wherein the batch comprises a batch characteristic selected from the group of:
  • NSFQRb normalized site frontside least squares focal plane range
  • NTFLRb normalized global frontside least squares focal plane range
  • a method of forming a finished substrate comprising: removing material from the upper surface of the substrate preform using a bonded abrasive after conducting a double- sided material removing process, wherein the bonded abrasive is angled relative to the substrate preform; polishing the substrate preform to form a finished substrate comprising at least one of the substrate characteristics selected from the group of: i) an site frontside least squares focal plane range (SFQR) of not greater than about 2.2 ⁇ ; ii) a normalized site frontside least squares focal plane range (NSFQR) of not greater than about 0.08 ⁇ /cm 2 ; iii) a global frontside least squares focal plane range (GFLR) of not greater than about 3.7 ⁇ ; iv) a normalized global frontside least squares focal plane range (NGFLR) of not greater than about 0.15 ⁇ /cm 2 ; v) an average roll off amount (ROA) of not greater than about 0.6 ⁇ ;
  • FIG. 1 is a flow chart illustrating a method of forming a substrate from a pre-finished substrate according to one embodiment.
  • FIG. 2A is an illustration of the site frontside least squares focal plane range (SFQR) on a sapphire substrate according to an embodiment.
  • SFQR site frontside least squares focal plane range
  • FIG. 2B is an illustration of the global frontside least squares focal plane range (GFLR) on a sapphire substrate according to an embodiment.
  • GFLR global frontside least squares focal plane range
  • FIG. 3 is an illustration of the roll off amount (ROA) for a sapphire substrate according to an embodiment.
  • FIG. 4 is an illustration of a polishing apparatus according to one embodiment.
  • FIG. 5 is a graph demonstrating subsurface damage (SSD) after top side grinding and annealing of the sapphire substrate at the center and at the edge location according to one embodiment.
  • SSD subsurface damage
  • FIG. 6 is an illustration of double sided substrate grinding using an abrasive slurry.
  • FIG. 7 is an illustration of a substrate with an added grid pattern to demonstrate the SFQR measuring points throughout the substrate surface according to one embodiment.
  • the terms “comprises,” “comprising,” “includes,” “including,” “has,” “having” or any other variation thereof, are intended to cover a non-exclusive inclusion.
  • a process, method, article, or apparatus that comprises a list of features is not necessarily limited only to those features but may include other features not expressly listed or inherent to such process, method, article, or apparatus.
  • wafer and substrate are used synonymously to refer to sectioned sapphire material that is being formed or processed to be used, e.g., as a substrate for epitaxial growth of semiconductor layers. Oftentimes it is common to refer to an unfinished sapphire piece as a wafer and a finished sapphire piece as a substrate, however, as used herein, these terms do not necessarily imply this distinction.
  • edge exclusion is a defined area at the edge of the substrate, where no surface measurements are conducted.
  • the edge exclusion in commercial substrate manufacturing is typically an area of 1.0 to 3.0 mm from the edge of the substrate, regardless of the substrate diameter.
  • the edge exclusion during the surface measurements of SFQR, GFLR, and TTV was mostly measured by excluding only 0.5 mm from the edge of the substrate. If the edge exclusion of reported SFQR, GFLR, and TTV data in this disclosure is not specifically defined, all data in the present disclosure relate to measurements made with 0.5 mm edge exclusion.
  • flatness is used to characterize i) "local flatness” and/or ii) "global flatness” of a substrate.
  • the term "local flatness" relates to a limited area of the substrate
  • SFQR site frontside least squares focal plane range
  • NSFQR normalized site frontside least squares focal plane range
  • global flatness relates to the flatness of the entire substrate, except the area of the edge exclusion.
  • the global flatness is also expressed as "global frontside least square focal plane range” (GFLR), and is the difference between the highest point above and the lowest point below the least square fit focal plane (see Figure 2B). The least square fit is made across the entire measurement surface.
  • GFLR global frontside least square focal plane range
  • normalized global frontside least square focal plane range relates to the largest GFLR value measured for a substrate normalized over the entire surface area of the substrate, except the area of the edge exclusion.
  • exclusion zone is defined as an area on the edges of the substrate, where devices may not be properly placed and used on the wafer.
  • the wafers of the present disclosure have an exclusion zone not reaching further than 0.5 mm from the edges of the wafers.
  • exclusion zone factor is defined by the equation (W ex / W rx ) x 100%, with W ex representing the average width of the exclusion zone on the surface of the substrate and W r represents the average radius of the substrate at the surface.
  • the term "roll off amount” relates to a parameter which characterizes the near edge geometry of a wafer.
  • the ROA is defined as the vertical distance (z-direction) between an extrapolated horizontal surface line and the wafer top surface at a defined measuring point close to the wafer edge.
  • the position of the measuring point is typically 1 mm away from the wafer edge in radial direction to the center of the wafer (see Figure 3), but it may also vary according to specific needs.
  • total thickness variation is defined as the maximum variation in the substrate thickness.
  • normalized total thickness variation relates to the measured TTV normalized to an area of the entire substrate, except the edge exclusion.
  • the present disclosure relates to a method of making a high quality sapphire substrate with superior geometric surface properties.
  • the method is characterized by a specific sequence of process steps that also allows for the formation of sapphire substrates with improved dimensional and shape characteristics.
  • references herein is made to sapphire substrates, which may have a Mohs hardness of approximately 9. It will be appreciated that the process disclosed herein may be suitable for other materials, such as inorganic materials, and more particularly oxides, carbides, nitrides, borides, oxycarbides, oxynitrides, and a combination thereof. Such inorganic materials may have a range of hardnesses.
  • Non-limiting examples of other substrate materials that may be suitable for the disclosed method are gallium arsenide (Mohs hardness about 4.5), silicon (Mohs hardness about 6.5), silicon dioxide (Mohs hardness about 7), silicon nitride (Mohs hardness about 9), or gallium nitride (Mohs hardness about 9).
  • a substrate which in some instances, can have a substantially circular two-dimension shape as viewed top-down.
  • the substrates may have one or more reference flats.
  • the present application is not limited to substrates having a substantially circular two-dimensional shape, and can include substrates having a polygonal two dimensional shape (e.g., quadrilateral, triangular, pentagonal, etc.).
  • the unfinished single crystal sapphire substrate used as starting material in the process of the present disclosure is a coarse grinded sapphire wafer that can be obtained by using various techniques known in the art, including but not limited to, Czochalski method, Edge-Defined Film Fed Growth (EFG), Kyropoulos Method, or other techniques depending upon the size and shape of the boule or blank, and the orientation of the crystal.
  • the method of the present disclosure may include the following steps: 1) orientation adjustment 101; 2) double sided fixed abrasive lapping (FAL) 102; 3) top side grinding 103; 4) edge grinding 104; 5) annealing 105; and 6) polishing 106.
  • the unfinished sapphire substrate is first subjected to an orientation adjustment process 101, followed by double sided fixed abrasive lapping (FAL) 102.
  • FAL double sided fixed abrasive lapping
  • the amount of material removed from both front and back sides of the sapphire substrate during double sided FAL 102 can be at least about 30 ⁇ , such as at least about 50 ⁇ , at least about 80 ⁇ , or at least about 100 ⁇ . In another embodiment, the amount of material removed may be not more than about 250 ⁇ , such as not more than about 200 ⁇ , not more than about 180 ⁇ or not more than about 150 ⁇ .
  • the amount of sapphire material removed from the upper surface and back surface during fixed abrasive doubled-sided lapping can be within a range between any of the minimum and maximum values noted above, such as, between about 30 ⁇ to about 250 ⁇ , between about 50 ⁇ to about 200 ⁇ , or between about 60 ⁇ to about 150 ⁇ .
  • the double sided FAL process 102 can utilize a bonded abrasive having coarse abrasive grains fixed in a bond material matrix.
  • the abrasive grains can include conventional abrasive grains such as crystalline materials or ceramic materials including alumina, silica, silicon carbide, zirconia- alumina and the like.
  • the abrasive grains can include superabrasive grains, including diamond, and cubic boron nitride, or mixtures thereof.
  • Embodiments using superabrasive grains may include non-superabrasive ceramic materials as filler materials, such as those noted above.
  • the abrasive grains of the bonded abrasive bodies used in double-sided FAL can have an average size of not greater than about 300 ⁇ , such as not greater than about 200 ⁇ , or even not greater than about 150 ⁇ .
  • the grain size may be at least about 2.0 ⁇ , such as at least about 5.0 ⁇ , at least about 10.0 ⁇ or at least about 20.0 ⁇ .
  • the abrasive grain size of the fixed abrasive used during double sided FAL can be within a range between any of the minimum and maximum values noted above, such as between about 2.0 ⁇ to about 300 ⁇ , between about 5.0 ⁇ to about 200 ⁇ , or between about 10 ⁇ to about 150 ⁇ .
  • the bond material matrix of the bonded abrasive used for double sided FAL can include an inorganic material, an organic material, or a combination thereof.
  • an inorganic material may include metals, glass, glass-ceramics, or a combination thereof. Suitable metals can include iron, aluminum, titanium, bronze, nickel, silver, zirconium, and alloys thereof.
  • Organic materials for the use as bond material may include, for example, thermoset and thermoplastic resins, for example, phenolic resin, epoxy resin, polyester, cyanate ester, shellac, polyurethane, polyimide or a combination thereof.
  • the bonded abrasive used for double-sided FAL 102 may have a porosity not less than about 20 vol%, such as not less than about 30 vol%; in another embodiment the porosity can be not larger than 70 vol%, such as not larger than 60 vol% or not larger than 50 vol%. It will be appreciated that the porosity of the fixed abrasive used during double sided FAL can be within a range between any of the minimum and maximum values noted above, such as between about 30 vol% to about 80 vol%, between about 35 vol% to about 75 vol%, or between about 35 vol% to about 70 vol%.
  • the porosity of the bonded abrasive can be open or closed.
  • the porosity is open, interconnected pores.
  • the size of the pores can generally be within a range of sizes between about 25 ⁇ to about 500 ⁇ , such as between about 150 ⁇ to about 500 ⁇ .
  • the foregoing pore -related values and those described herein are made in connection with various components pre-machining or pre-grinding.
  • the bonded abrasive of step 102 may utilize a particular grain content, such as not greater than about 50 vol %, such as not greater than 40 vol %, not greater than 30 vol %, not greater than about 20 vol %, or even not greater than about 10 vol % coarse abrasive grains based on the total amount of the coarse abrasive.
  • the content of coarse abrasive grains may be not less than about 0.5 vol %, such as not less than 1.0 vol% or not less than 5 vol%.
  • the abrasive grain content of the abrasive used during double sided FAL can be within a range between any of the minimum and maximum values noted above, such as, between about 0.5 vol% to about 25 vol %, between about 1.0 vol % and about 15 vol %, or between about 2.0 vol % and about 10 vol %, based on the total volume amount of the coarse abrasive.
  • the substrates typically can have on the upper surface and the rear surface an average surface roughness R a of less than about 1.2 ⁇ .
  • the average surface roughness Ra of the substrate after double sided FAL can be not larger than about 1.0 ⁇ , not larger than 0.8 ⁇ , not larger than 0.7 ⁇ , or not larger than 0.6 ⁇ .
  • the process of double-sided fixed abrasive lapping may be controlled in combination with other processes to facilitate formation of substrates having the features of the embodiments herein.
  • the duration of double-sided FAL can be less than 60 minutes, such as less than 50 minutes, less than 40 minutes, less than 30 minutes, or less than 20 minutes.
  • the process of forming the sapphire substrates can continue with a top side grinding process 103.
  • the top side grinding process can include a fixed abrasive grinding process on the upper surface of the sapphire substrate.
  • the top side grinding process may be utilized to further finish the upper surface of the sapphire substrate, including providing certain dimensional features and reducing subsurface damage
  • the amount of material removed from the upper surface of the sapphire substrate during the top side grinding process 103 may be at least about 10 ⁇ , such as at least about 15 ⁇ , or at least about 20 ⁇ .
  • the amount of material removal may be not larger than about 50 ⁇ , such as not larger than about 40 ⁇ , not larger than about 35 ⁇ , or not larger than about 30 ⁇ .
  • the amount of sapphire material removed from the upper substrate surface can be within a range between any of the minimum and maximum values noted above, such as, between about 5 ⁇ to about 50 ⁇ , between about 10 ⁇ to about 40 ⁇ , or between about 20 ⁇ to about 30 ⁇ .
  • the top side grinding process 103 may utilize a fixed abrasive having a finer abrasive grain size as compared to the double-sided FAL process of step 102.
  • the fixed abrasive used for the top side grinding may be a bonded abrasive body including fine abrasive grains in a bond material matrix.
  • the fine abrasive grains can include abrasive grains such as crystalline materials or ceramic materials including alumina, silica, silicon carbide, zirconia-alumina, or superabrasive grains such as diamond and cubic boron nitride, or mixtures thereof.
  • Those embodiments utilizing superabrasive grains can utilize non-superabrasive ceramic materials such as those noted above as a filler material.
  • the fixed abrasive used for top side grinding 103 may contain fine abrasive grains in an amount of not greater than about 50 vol%, such as not greater than 40 vol%, not greater than 30 vol%, not greater than about 20 vol %, or not greater than about 10 vol % based on the total weight of the abrasive.
  • the amount of fine abrasive grains may be not less than about 0.5 vol%, such as not less than 1.0 vol% or not less than 2.0 vol%.
  • the amount of abrasive grains in the fixed abrasive for top side grinding can be within a range between any of the minimum and maximum values noted above, such as, between 1.0 vol % to about 50 vol %, between about 2.0 vol% to 30 vol%, or between about 2.0 vol% to about 15 vol% based on the total weight of the fixed abrasive.
  • the abrasive grains used for top side grinding 103 can have an average particle size of not greater than about 100 ⁇ , such as not greater than about 75 ⁇ , not greater than about 50 ⁇ , or not greater than about 25 ⁇ .
  • the average abrasive grain size can be at least about 1 ⁇ , such as at lest about 2.0 ⁇ , at least about 5.0 ⁇ or at least about 10.0 ⁇ . It will be appreciated that the average particle size of the fine abrasive grains can be within a range between any of the minimum and maximum values noted above.
  • the fine abrasive grain size can be within a range between about 1.0 ⁇ to about 100 ⁇ , such as between about 2.0 ⁇ to about 50 ⁇ , or between about 5 ⁇ to about 25 ⁇ .
  • the bond material matrix of the fixed abrasive used in step 103 can include an inorganic material, an organic material, or a combination thereof.
  • an inorganic material may include metals, glass, glass-ceramics, or a combination thereof. Suitable metals can include iron, aluminum, titanium, bronze, nickel, silver, zirconium, and alloys thereof.
  • Organic materials for the use as bond material may include, for example, thermoset and thermoplastic resins, for example, phenolic resin, epoxy resin, polyester, cyanate ester, shellac, polyurethane, polyimide or a combination thereof.
  • the fixed abrasive used for top side grinding may include an amount of bond material of not greater than about 70 vol%, such as not greater than about 60 vol%, not greater than about 50 vol%, or not greater than about 40 vol% based on the total weight of the fixed abrasive.
  • an amount of bond material may be not less than about 10 vol%, not less than 15 vol%, or not less than 20 vol%. It will be appreciated that the amount of bond material of the fixed abrasive used during top side grinding can be within a range between any of the minimum and maximum values noted above, such as, between about 10 vol% to about 70 vol%, between about 15 vol% to about 65 vol%, or between about 20 vol% to about 55 vol%.
  • the fine abrasive may be a self-sharpening bonded abrasive wheel comprising diamond abrasive particles contained within a metal bond matrix material.
  • the fixed abrasive of step 103 may include a degree of porosity.
  • the fixed abrasive may have a porosity of not less than about 20 vol%, such as not less than about 30 vol%, or not less than 40 vol% based on the total volume of the fixed abrasive.
  • the porosity of the fixed abrasive may be not greater than 80 vol%, such as not greater than 75 vol% or not greater than 70 vol%.
  • the porosity of the fixed abrasive can be within a range between any of the minimum and maximum values noted above, such as, between about 25 vol % to about 80 vol%, between about 40 vol% to about 80 vol%, between about 30 vol% to about 70 vol%, or between about 50 vol% to 70 vol% based on the total volume of the fixed abrasive. It will be further appreciated that the porosity can be open or closed, and in fixed abrasives that have a greater percentage of porosity, generally the pore structure are open, interconnected pores. The size of the pores can generally be within a range of between about 25 ⁇ to about 500 ⁇ , such as between about 150 ⁇ to about 500 ⁇ .
  • the top side grinding 103 includes an apparatus and process similar to the process described above in conjunction with the double sided FAL process 102. That is, generally, providing an unfinished sapphire substrate on a holder and rotating the sapphire substrate relative to an abrasive surface, typically an abrasive wheel, having a substantially circular segmented abrasive rim around a perimeter of an inner wheel.
  • an abrasive surface typically an abrasive wheel, having a substantially circular segmented abrasive rim around a perimeter of an inner wheel.
  • the fine grinding process includes rotating the abrasive wheel at a speed of at least about 1500 revolutions per minute (rpm), such as at least about 2000 rpm.
  • the speed of the abrasive wheel is not greater than about 5000 rpm, such as not greater than about 4000 rpm, or not greater than about 3000 rpm.
  • the rotating abrasive wheel of the fine grinding process can have a speed in a range of any of the maximum and minimum values described above, such as, from about 1500 rpm to about 5000 rpm, from about 2000 rpm to about 4000 rpm, or from about 2000 rpm to about 3000 rpm.
  • the top side fine grinding 103 can be conducted with a Koyo grinder.
  • the Koyo grinder includes the option that the head of the grinder may be angled of tilted, whereby such tilting of the head may lead to an improvement of the TTV in comparison to not tilting the head.
  • the substrates after the top side grinding 103 of the unfinished sapphire substrates, the substrates typically can have an average surface roughness Ra of less than about 130 nm, such as less than about 110 nm, less than about 90 nm, less than about 70 nm, less than about 50 nm, or less than about 40 nm.
  • the subsurface damage (SSD) after top side grinding 103 of the substrate is less than about 8 ⁇ , such as less than about 7 ⁇ , less than about 6 ⁇ , or less than about 5 ⁇ .
  • the required run-time to achieve a set target thickness of the sapphire substrate during top side grinding can be generally about 60 seconds or less.
  • the sapphire substrates can be subjected to edge grinding 104 and annealing 105.
  • a bevel may be cut at a 45 degree angle to the top side and to the rear side of the substrate.
  • the length of the bevel may be at least about 10 ⁇ , such as at last about 30 ⁇ , or at least about 50 ⁇ .
  • the length of the bevel may be not greater than about 250 ⁇ , such as not greater than about 200 ⁇ , or not greater than about 100 ⁇ .
  • the length of the bevel can be within a range between any of the minimum and maximum values noted above, such as from about 10 ⁇ to about 250 ⁇ , from about 30 ⁇ to about 200 ⁇ , or from about 50 ⁇ to about 150 ⁇ .
  • the annealing 105 is conducted to provide stress relief in the sapphire substrate.
  • the annealing may be conducted under vacuum at a temperature within about 1300°C to about 1550°C for up to 20 hours.
  • an etching step may be optionally included.
  • the final polishing step 106 may utilize an abrasive slurry in combination with a fibrous pad.
  • the pad is designed to take up the abrasive particles of the slurry and to evenly distribute the abrasive particles under pressure throughout the wafer surface, and thereby removing substrate material.
  • the slurry is provided between the surface of the substrate and the pad, and the substrate and the pad can be moved relative to each other to carry out the polishing operation.
  • the polishing using a slurry may fall into the category of chemical-mechanical polishing (CMP).
  • CMP chemical-mechanical polishing
  • the slurry typically includes loose abrasive particles suspended in a liquid medium to facilitate removal of a precise amount of material from the substrate.
  • the polishing process 106 can include CMP using a slurry containing an abrasive and an additive compound, which may function to enhance or moderate material removal.
  • the chemical component may, for example, be a phosphorus compound. Effectively, the abrasive provides the mechanical component, and the additive provides the chemically active component.
  • the loose abrasive is generally nanosized, and can have an average secondary particle diameter less than 1 ⁇ , typically less than 300 nanometers.
  • the primary particle size can be within a narrower range, such as within a range between about 10 nm to about 100 nm.
  • an average secondary particle size of lower than about 1 ⁇ generally denotes a polishing process, corresponding to the subject matter herein below, in which a fine surface finish is provided by carrying out the machining operation at low material removal rates.
  • the machining operation is characterized as a lapping operation.
  • a particularly useful loose abrasive for the polishing process 106 may be alumina, such as in the form of polycrystalline or monocrystalline gamma alumina.
  • the slurry may contain at least one optional additive.
  • the additive may be present at a concentration within a range of between about 0.05 to about 5.0 wt% based on the total weight of the slurry, such as within a range of between about 0.10 wt% to about 3.0 wt%, or of about 0.10 wt% to about 2.0 wt% based on the total weight of the slurry.
  • the slurry may contain a phosphorus additive.
  • the phosphorus compound may contain oxygen, wherein oxygen is bonded to the phosphorus element.
  • This class of materials is known as oxophosphorus materials.
  • the oxophosphorus compound may contain phosphorus in valency state of one, three or five, and in particular embodiments, effective machining may be carried out by utilizing an oxophosphorus compound in which the phosphorus is in a valency state of five.
  • the phosphorus can be bonded to carbon in addition to oxygen, which generally denotes organic phosphorus compounds known as phosphonates.
  • organic phosphorus compounds include phosphates, pyrophosphates, hypophosphates, subphosphates, phosphites, pyrophosphites, hypophosphites and phosphonium compounds.
  • Particular species of phosphorus compounds include potassium phosphate, sodium hexametaphosphate, hydroxy phosphono acetic acid (Belcor 575) and aminotri-(methylenephosphonicacid) (Mayoquest 1320).
  • the abrasive slurry used for the polishing 106 may be of aqueous nature, i.e., water- based.
  • the slurry may have a basic pH, such as a pH greater than about 8.0, or greater than about 8.5.
  • the pH of the slurry may range up to a value of about twelve.
  • FIG 4 illustrates a schematic of the basic structure of a polishing apparatus according to one embodiment.
  • the apparatus 401 includes a machine tool, which includes a polishing pad 410 and a platen, wherein the platen supports the polishing pad.
  • the polishing pad 410 and the platen are of essentially the same diameter (wherefore the platen is not shown in Figure 4).
  • the platen is rotatable about a central axis, along a direction of rotation as illustrated by the arrow.
  • a template 412 has a plurality of circular indentations which respectively receive sapphire substrates 414, the substrates 414 being sandwiched between the polishing pad 410 and the template 412.
  • the template 412 carrying the substrates 414, rotates about its central axis, wherein r p represents the radius from the center of rotation of the polishing pad to the center of the template 412, whereas r t represents the radius from an individual substrate to the center of rotation of the template.
  • the configuration of apparatus 401 is a commonly employed configuration for polishing operations, although different configurations may be utilized.
  • the number of substrates may be any number between 1 and 8.
  • the polishing pad may be a soft pad or a hard pad.
  • soft pads have a larger contact area and lower effective pressure, whereas hard pads are more stiff and have a smaller contact area and a higher effective pressure. Accordingly, the material removal rate (MRR) of soft pads is typically much higher in comparison to hard pads.
  • MRR material removal rate
  • hard pads often have a better polishing result, i.e., a smoother surface, and allow the shape of the edges being maintained, while soft pads generally cause a rounding of the edges. The decision if a hard or soft pad should be employed for polishing mainly depends on the amount of the subsurface damage that needs to be removed from the wafer surface.
  • the hard pad selected for polishing may contain, for example, fiber based polymer mixtures, such as a polyester fiber / polyurethane resin mixtures, like MHS15A, from Eminess.
  • the process of the present disclosure may be expressed by a first time relationship of T p / T t x 100% being not greater than 92%, with T p representing the time needed for polishing step 106 and T t representing the total time for removing material from the upper surface of the substrate preform, i.e., steps 102, 103, and 106.
  • the first time relationship may be not greater than 90%, or not greater than 88% (see also Table 3).
  • the process of the present disclosure may be expressed by a second time relationship ( ⁇ ⁇ / ⁇ 3 ) being not greater than about 15%, with T p representing the time needed for polishing step 106 and T ba representing the time for removing material from the upper surface of the substrate preform, i.e., steps 102 and 103, except the time for polishing 106 (see also Table 3).
  • a high quality sapphire substrate may be produced with superior dimensional and shape properties, specifically with regard to local flatness (SFQR), global flatness (GFLR), and roll-off amount (ROA).
  • SFQR local flatness
  • GFLR global flatness
  • ROA roll-off amount
  • the substrate of the present disclosure may be manufactured in a batch of at least 10 substrates.
  • the following characterization of the substrate of the present disclosure may apply to a single substrate, as well as to all substrates of a manufactured batch.
  • the substrate of the present disclosure may comprise a body including alumina.
  • the alumina including substrate body may comprise a single crystalline material.
  • the substrate body may consist essentially of sapphire.
  • At least a portion of a crystalline plane of the substrate can intersect the upper surface, wherein the crystalline plane may be a C-plane, a R-plane, a M-plane, or an A-plane.
  • the substrate body may further comprise a reference indicium which may be a reference flat or a reference notch.
  • the substrate body may comprises a diameter of at least about 5 cm, at least about 6 cm, at least about 7 cm, at least about 8 cm, at least about 9 cm, at least about 10 cm, at least about 12 cm, at least about 15 cm, at least about 18 cm, or at least about 20 cm.
  • the substrate body may comprise a diameter of not greater than about 50 cm, not greater than about 45 cm, not greater than about 40 cm, or not greater than about 30 cm. It will be appreciated that the substrate body can have a diameter within a range between any of the minimum and maximum values noted above, such as, between about 5 cm to 50 cm, between about 10 cm to 45 cm or between about 15 cm to about 35 cm.
  • the substrate body may comprises an upper surface having an area of at least about 24 cm 2 , at least about 26 cm 2 , at least about 30 cm 2 , at least about 35 cm 2 , at least about 40 cm 2 , at least about 45 cm 2 , at least about 50 cm 2 , at least about 70 cm 2 , at least about 100 cm 2 , at least about 125 cm 2 , at least about 150 cm 2 , or at least about 175 cm 2 .
  • the area of the upper surface may be not greater than about 1000 cm 2 , not greater than about 800 cm 2 , not greater than about 600 cm 2 , not greater than about 400 cm 2 , not greater than about 300 cm 2 , not greater than about 200 cm 2 , or not greater than about 190 cm 2 .
  • the substrate body can have an upper surface area within a range between any of the minimum and maximum values noted above, such as, between about 24 cm 2 to about 900 cm 2 , between about 30 cm 2 to about 700 cm 2 or between about 50 cm 2 to about 500 cm 2 .
  • the substrate body may have a site frontside least squares focal plane range (SFQR) of not greater than about 2.2 ⁇ , such as not greater than about 2.1 ⁇ , not greater than about 2.0 ⁇ , not greater than about 1.9 ⁇ , not greater than about 1.8 ⁇ , not greater than about 1.7 ⁇ , not greater than about 1.6 ⁇ , not greater than about 1.5 ⁇ , not greater than about 1.4 ⁇ , not greater than about 1.3 ⁇ , not greater than about 1.2 ⁇ , not greater than about 1.1 ⁇ , not greater than about 1 ⁇ , not greater than about 0.95 ⁇ , not greater than about 0.90 ⁇ , not greater than about 0.85 ⁇ , not greater than about 0.80 ⁇ , not greater than about 0.75 ⁇ , not greater than about 0.70 ⁇ , not greater than about 0.65 ⁇ , not greater than about 0.60 ⁇ , not greater than about 0.55 ⁇ , not greater than about 0.50 ⁇ , not greater than about 0.45 ⁇ , not greater than about 0.40 ⁇ , not greater than about 0.
  • the SFQR is at least about 0.01 ⁇ , at least about 0.02 ⁇ , at least about 0.05 ⁇ , or at least about 0.07 ⁇ . It will be appreciated that the SFQR can be within a range between any of the minimum and maximum values noted above, such as, between about 0.01 ⁇ to 2.2 ⁇ , between about 0.04 ⁇ to about 1.5 ⁇ , or between about 0.07 ⁇ to about 1.2 ⁇ .
  • the normalized site frontside least squares focal plane range (NSFQR) of the sapphire substrate may be not greater than about 0.08 ⁇ /cm 2 , such as not greater than about 0.075 ⁇ /cm 2 , not greater than about 0.07 ⁇ /cm 2 , not greater than about 0.068 ⁇ /cm 2 , not greater than about 0.065 ⁇ / ⁇ 2 , not greater than about 0.063 ⁇ /cm 2 , not greater than about 0.060 ⁇ /cm 2 , not greater than about 0.058 ⁇ / ⁇ 2 , not greater than about 0.055 ⁇ /cm 2 , not greater than about 0.053 ⁇ / ⁇ 2 , not greater than about 0.050 ⁇ / ⁇ 2 , not greater than about 0.048 ⁇ /cm 2 , not greater than about 0.045 ⁇ / ⁇ 2 , not greater than about 0.043 ⁇ /cm 2 , not greater than about 0.040 ⁇ /cm 2 , not greater than about 0.08 ⁇
  • the NSFQR may be at least about 0.0001 ⁇ /cm 2 , at least about 0.001 ⁇ / ⁇ 2 , or at least about 0.0002 ⁇ / ⁇ 2 .
  • the substrate body can have an NSFQR within a range between any of the minimum and maximum values noted above, such as, between about 0.001 ⁇ about 0.075 ⁇ /cm 2 , between about 0.002 ⁇ : ⁇ 2 ⁇ about 0.06 ⁇ /cm 2 or between about 0.002 ⁇ /cm 2 to about 0.052 ⁇ /cm 2 .
  • the global frontside least squares focal plane range (GFLR) of the sapphire substrate may be not greater than about 3.7 ⁇ , such as not greater than not greater than about 3.6 ⁇ , not greater than about 3.5 ⁇ , not greater than about 3.4 ⁇ , not greater than about 3.3 ⁇ , not greater than about 3.2 ⁇ , not greater than about 3.0 ⁇ , not greater than about 2.9 ⁇ , not greater than about 2.8 ⁇ , not greater than about 2.7 ⁇ , not greater than about 2.6 ⁇ , not greater than about 2.5 ⁇ , not greater than about 2.4 ⁇ , not greater than about 2.3 ⁇ , not greater than about 2.2 ⁇ , not greater than about 2.1 ⁇ , not greater than about 2.0 ⁇ , not greater than about 1.9 ⁇ , not greater than about 1.8 ⁇ , not greater than about 1.7 ⁇ , not greater than about 1.6 ⁇ , not greater than about 1.5 ⁇ , not greater than about 1.4 ⁇ , not greater than about 1.3 ⁇ , not greater than about 1.2 ⁇ ,
  • the GFLR may be at least about 0.01 ⁇ , at least about 0.1 ⁇ . It will be appreciated that the GFLR can be within a range between any of the minimum and maximum values noted above, such as, between about 0.01 ⁇ to about 3.6 ⁇ , between about 0.1 ⁇ to about 3.0 ⁇ , or between about 0.1 ⁇ to about 2.2 ⁇ .
  • the normalized global frontside least squares focal plane range (NGFLR) of the sapphire substrate may be not greater than about 0.15 ⁇ /cm 2 , such as not greater than about 0.14 ⁇ /cm 2 , not greater than about 0.13 ⁇ /cm 2 , not greater than about 0.12 ⁇ /cm 2 , not greater than about 0.11 ⁇ /cm 2 , not greater than about 0.10 ⁇ /cm 2 , not greater than about 0.09 ⁇ /cm 2 , not greater than about 0.08 ⁇ /cm 2 , not greater than about 0.07 ⁇ /cm 2 , not greater than about 0.06 ⁇ /cm 2 , not greater than about 0.05 ⁇ /cm 2 , not greater than about 0.04 ⁇ /cm 2 , not greater than about 0.03 ⁇ /cm 2 , not greater than about 0.02 ⁇ /cm 2 , not greater than about 0.01 ⁇ /cm 2 , not greater than about 0.009 ⁇ /cm 2
  • the NGFLR may be at least about 0.0001 ⁇ /cm 2 or at least about 0.001 ⁇ /cm 2 . It will be appreciated that the NGFLR can be within a range between any of the minimum and maximum values noted above, such as, between about 0.001 ⁇ 0.14 ⁇ /cm 2 , between about 0.001 ⁇ /cm 2 to about 0.10 ⁇ /cm 2 , or between about 0.001 ⁇ /cm 2 to about 0.07 ⁇ /cm 2 .
  • the EZF is not greater than about 0.65%, such as not greater than about 0.63%, not greater than about 0.6%, not greater than about 0.58%, not greater than about 0.55%, not greater than about 0.53%, not greater than about 0.5%, not greater than about 0.48%, not greater than about 0.45%, not greater than about 0.43%, not greater than about 0.4%, not greater than about 0.38%, not greater than about 0.35%, not greater than about 0.33%, not greater than about 0.3%, not greater than about 0.28%, not greater than about 0.25%, not greater than about 0.23%, not greater than about 0.2%, not greater than about 0.18%, not greater than about 0.15%, not greater than about 0.13%, not greater than about 0.1 %, not greater than about 0.09%, not greater than about 0.08%, not greater than about 0.07%, not greater than about 0.06%, not greater than about 0.05%, not greater than about 0.04%, not greater than about 0.03%, or not greater than about 0.02%.
  • an average roll off amount (ROA) measured at a 1mm distance from the wafer edge (see Figure 3) of the sapphire substrate may be not greater than about 0.6 ⁇ , not greater than about 0.58 ⁇ , not greater than about 0.55 ⁇ , not greater than about 0.53 ⁇ , not greater than about 0.5 ⁇ , not greater than about 0.48 ⁇ , not greater than about 0.45 ⁇ , not greater than about 0.43 ⁇ , not greater than about 0.4 ⁇ , or not greater than about 0.37 ⁇ .
  • the ROA is at least about 0.001 ⁇ or at least about 0.005 ⁇ .
  • the ROA can be within a range between any of the minimum and maximum values noted above, such as, between about 0.001 ⁇ to about 0.57 ⁇ , between about 0.005 ⁇ to about 0.51 ⁇ , or between about 0.005 ⁇ to about 0.42 ⁇ .
  • the sapphire substrate obtained by the process of the present disclosure is further characterized by a low surface roughness R a .
  • the upper surface of the substrate may have an average surface roughness R a of not greater than about 5 A, not greater than about 4.5 A, not greater than about 4.3 A, not greater than about 4.0 A, not greater than about 3.8 A , not greater than about 3.5 A, not greater than about 3.0 A, not greater than about 2.8 A, not greater than about 2.5 A, not greater than about 2.3 A, not greater than about 2.0 A, not greater than about 1.8 A, not greater than about 1.5 A, not greater than about 1.3 A, not greater than about 1.0 A, not greater than about 0.8 A, not greater than about 0.5 A, not greater than about 0.3 A, not greater than about 0.2 A, or not greater than about 0.1 A.
  • the average surface roughness Ra of the upper surface may be at least about 0.01 Angstroms or at least about 0.05 Angstroms. It will be appreciated that the surface roughness R a of the sapphire substrate can be within a range between any of the minimum and maximum values noted above, such as, between about 0.01 Angstroms to about 5 A, between about 0.05 Angstrom to about 3.7 A, or between about 0.005 nm to about 3.0 A.
  • the substrate body may comprise an average thickness of not greater than about 2000 ⁇ , such as not greater than about 1800 ⁇ , not greater than about 1600 ⁇ , 1400 ⁇ , not greater than about 1380 ⁇ , not greater than about 1350 ⁇ , not greater than about 1320 ⁇ , not greater than about 1300 ⁇ , or not greater than about 1280 ⁇ .
  • the average thickness of the substrate body may be at least about 200 ⁇ , at least about 500 ⁇ , or at least about 700 ⁇ .
  • the average thickness of the sapphire substrate can be within a range between any of the minimum and maximum values noted above, such as, between about 400 ⁇ to about 1900 ⁇ , between about 500 ⁇ to about 1500 ⁇ , or between about 700 ⁇ to about 1350 ⁇ .
  • the substrate body may comprise a thickness/diameter ratio of at least about 0.005, such as at least about 0.006, or at least about 0.007.
  • the substrate body may comprise a thickness/diameter ratio of at least about 0.005, such as at least about 0.006, or at least about 0.007.
  • thickness/diameter ratio may not be greater than about 0.05, such as not greater than about 0.03, or not greater than about 0.01. It will be appreciated that the thickness/diameter ratio can be within a range between any of the minimum and maximum values noted above, such as, between about 0.005 to about 0.01 or between about 0.006 to about 0.05.
  • the total thickness variation (TTV) of the substrate body may be not greater than about 6.5 ⁇ , such as not greater than about 6.3 ⁇ , not greater than about 6.0 ⁇ , not greater than about 5.7 ⁇ , not greater than about 5.3 ⁇ , not greater than about 5.0 ⁇ , not greater than about 4.7 ⁇ , not greater than about 4.5 ⁇ , not greater than about 4.3 ⁇ , not greater than about 4.0 ⁇ , not greater than about 3.7 ⁇ , not greater than about 3.5 ⁇ , not greater than about 3.3 ⁇ , not greater than about 3.0 ⁇ , not greater than about 2.7 ⁇ , not greater than about 2.3 ⁇ , not greater than about 2.5 ⁇ , not greater than about 2.3 ⁇ , or not greater than about 2.0 ⁇ .
  • the TTV of the substrate body is at least 0.01 ⁇ , such as at least 0.05 ⁇ , at least 0.1 ⁇ or at least 0.15 ⁇ . It will be appreciated that the TTV can be within a range between any of the minimum and maximum values noted above, such as, between about 6.5 ⁇ to about 0.05 ⁇ , or between about 5.0 ⁇ to about 0.15 ⁇ .
  • the substrate body may comprise a normalized total thickness variation (NTTV) of not greater than about 0.4 ⁇ /cm 2 , not greater than about 0.38 ⁇ /cm 2 , not greater than about 0.35 ⁇ /cm 2 , not greater than about 0.33 ⁇ /cm 2 , not greater than about 0.3 ⁇ /cm 2 , not greater than about 0.28 ⁇ /cm 2 , not greater than about 0.25 ⁇ /cm 2 , not greater than about 0.23 ⁇ /cm 2 , not greater than about 0.2 ⁇ /cm 2 , not greater than about 0.18 ⁇ /cm 2 , not greater than about 0.15 ⁇ /cm 2 , not greater than about 0.13 ⁇ /cm 2 , not greater than about 0.1 ⁇ /cm 2 , not greater than about 0.08 ⁇ /cm 2 , not greater than about 0.05 ⁇ /cm 2 , not greater than about 0.03 ⁇ /cm 2 , not greater than about 0.02
  • NTTV normalized
  • the NTTV is at least about 0.001 ⁇ /cm 2 or at least about 0.005 ⁇ /cm 2 . It will be appreciated that the NTTV of the substrate body can be within a range between any of the minimum and maximum values noted above, such as, between about 0.001 ⁇ /cm 2 to about 0.4 ⁇ /cm 2 , between about 0.005 ⁇ /cm 2 to about 0.29 ⁇ /cm 2 , or between about 0.005 ⁇ : ⁇ 2 ⁇ about 0.16 ⁇ /cm 2 .
  • the substrate body may comprise an average bow of not greater than about 3.5 ⁇ , not greater than about 3.0 ⁇ , not greater than about 2.8 ⁇ , not greater than about 2.5 ⁇ , not greater than about 2.2 ⁇ , not greater than about 2 ⁇ , not greater than about 1.8 ⁇ .
  • the substrate body comprises an average bow of at least about 0.001 ⁇ . It will be appreciated that the average bow of the substrate body can be within a range between any of the minimum and maximum values noted above, such as, between about 0.001 ⁇ to about 3.3 ⁇ , between about 0.001 ⁇ to about 2.4 ⁇ , or between about 0.001 ⁇ to about 1.9 ⁇ .
  • the substrate body may comprise a negative bow defining a concave substrate, wherein a midpoint of an upper surface of the body is lower than the peripheral edges of the substrate, and wherein the negative bow is at least about 0.001 ⁇ , at least about 0.1 ⁇ , at least about 0.5 ⁇ , at least about 0.8 ⁇ , at least about 1 micron, wherein the body comprises a positive bow defining a convex substrate, wherein a midpoint of an upper surface of the body is higher than a peripheral edge and wherein the positive bow is at least about 0.001 ⁇ , at least about 0.1 ⁇ , at least about 0.5 ⁇ , at least about 0.8 ⁇ , or at least about 1 micron.
  • the present embodiments provide notable advantages.
  • sapphire substrates with an exceptional surface geometry can be obtained, having a very low local flatness (SFQR) in the center and in the edge locations of the substrate, up to an edge exclusion of 0.5 mm (see experimental part, Table 5, and Figure 7).
  • SFQR local flatness
  • reasons for obtaining a superior flatness of the substrate after polishing may be a low and evenly distributed subsurface damage (SSD) of the substrate after top side grinding and annealing.
  • SSD subsurface damage
  • the SSD is evenly distributed throughout the sapphire substrate, varying mainly between 4 and 6 ⁇ at the center and at the edges of the substrate.
  • This small SSD layer may be removed with a polishing pad material having a higher hardness and lower removal rate in comparison to standard pads for polishing. Thereby, the original shape of the substrate can be maintained, while softer pad materials, which are commonly employed to remove much larger SSD layers, always lead to a rounding of the substrate edges.
  • the sapphire substrates of the present disclosure are further characterized by having a low local flatness (SFQR) in combination with a very low surface roughness.
  • SFQR low local flatness
  • a wafer loses flatness during the final polishing step, especially if still large amounts of material need to be removed.
  • sapphire substrates that may have a superior local flatness SFQR and a surface roughness Ra not greater than 3 A.
  • the substrate body can consist essentially of sapphire and can have a surface roughness of not greater than 3 A and an SFQR not greater than 1.5 ⁇ .
  • the substrate body can consist essentially of sapphire and can have a surface roughness of not greater than 3 A and at least 65% of the substrate surface located in the center region of the substrate body can have an SFQR not greater than 0.5 ⁇ , as demonstrated in Figure 7.
  • Embodiments of the present disclosure further show that it is possible to limit the final polishing time in comparison to conventional polishing time dramatically, up to 50%.
  • Item 1 A substrate comprising a body including alumina wherein the body comprising at least one of the substrate characteristics selected from the group of:
  • SFQR site frontside least squares focal plane range
  • NSFQR normalized site frontside least squares focal plane range
  • GFLR global frontside least squares focal plane range
  • NTFLR normalized global frontside least squares focal plane range
  • ROA average roll off amount
  • Item 2 The substrate of item 1, wherein the body comprises a single crystalline material.
  • Item 3 The substrate of item 1, wherein the body comprises sapphire.
  • Item 4 The substrate of item 1, wherein the body consists essentially of alumina.
  • Item 5 The substrate of item 1, wherein the body consists essentially of sapphire.
  • Item 6 The substrate of item 1, wherein the body comprises a diameter of at least about 5 cm, at least about 6 cm, at least about 7 cm, at least about 8 cm, at least about 9 cm, at least about 10 cm, at least about 12 cm, at least about 15 cm, at least about 18 cm, at least about 20 cm.
  • Item 7 The substrate of item 1, wherein the body comprises a diameter of not greater than about 50 cm, not greater than about 45 cm, not greater than about 40 cm, or not greater than about 30 cm.
  • Item 8 The substrate of item 1, wherein the body comprises an upper surface having an area of at least about 24 cm 2 , at least about 26 cm 2 , at least about 30 cm 2 , at least about 35 cm 2 , at least about 40 cm 2 , at least about 45 cm 2 , at least about 50 cm 2 , at least about 70 cm 2 , at least about 100 cm 2 , at least about 125 cm 2 , at least about 150 cm 2 , at least about 175 cm 2 .
  • Item 9 Item 9.
  • Item 10 The substrate of item 1, wherein the SFQR is not greater than about 2.1 ⁇ , not greater than about 2.0 ⁇ , not greater than about 1.9 ⁇ , not greater than about 1.8 ⁇ , not greater than about 1.7 ⁇ , not greater than about 1.6 ⁇ , not greater than about 1.5 ⁇ , not greater than about 1.4 ⁇ , not greater than about 1.3 ⁇ , not greater than about 1.2 ⁇ , not greater than about 1.1 ⁇ , not greater than about 1 ⁇ , not greater than about 0.95 ⁇ , not greater than about 0.90 ⁇ , not greater than about 0.85 ⁇ , not greater than about 0.80 ⁇ , not greater than about 0.75 ⁇ , not greater than about 0.70 ⁇ , not greater than about 0.65 ⁇ , not greater than about 0.60 ⁇ , not greater than about 0.55 ⁇ , not greater than about 0.50 ⁇ , not greater than about 0.45 ⁇ , not greater than about 0.40 ⁇ , not greater than about 0.35 ⁇ , not greater than about 0.30 ⁇ , not greater than about 0.25
  • Item 11 The substrate of item 1, wherein the SFQR is at least about 0.01 ⁇ , at least about 0.02 ⁇ , at least about 0.05 ⁇ , at least about 0.07 ⁇ .
  • Item 12 The substrate of item 1, wherein the body comprises an average bow of not greater than about 3.5 ⁇ , not greater than about 3.0 ⁇ , not greater than about 2.8 ⁇ , not greater than about 2.5 ⁇ , not greater than about 2.2 ⁇ , not greater than about 2 ⁇ , not greater than about 1.8 ⁇ .
  • Item 13 The substrate of item 1, wherein the body comprises an average bow of at least about 0.001 ⁇ .
  • Item 14 The substrate of item 1, wherein the body comprises a negative bow defining a concave substrate, wherein a midpoint of an upper surface of the body is lower than the peripheral edges of the substrate, and wherein the negative bow is at least about 0.001 ⁇ , at least about 0.1 ⁇ , at least about 0.5 ⁇ , at least about 0.8 ⁇ , at least about 1 micron, wherein the body comprises a positive bow defining a convex substrate, wherein a midpoint of an upper surface of the body is higher than a peripheral edge and wherein the positive bow is at least about 0.001 ⁇ , at least about 0.1 ⁇ , at least about 0.5 ⁇ , at least about 0.8 ⁇ , at least about 1 micron.
  • Item 15 The substrate of item 1, wherein the body comprises a normalized site frontside least squares focal plane range (NSFQR) of not greater than about 0.075 ⁇ /cm 2 , not greater than about 0.07 ⁇ /cm 2 , not greater than about 0.068 ⁇ /cm 2 , not greater than about 0.065 ⁇ /cm 2 , not greater than about 0.063 ⁇ /cm 2 , not greater than about 0.060 ⁇ /cm 2 , not greater than about 0.058 ⁇ /cm 2 , not greater than about 0.055 ⁇ /cm 2 , not greater than about 0.053 ⁇ /cm 2 , not greater than about
  • NSFQR normalized site frontside least squares focal plane range
  • Item 16 The substrate of item 1, wherein the body comprises a normalized site frontside least squares focal plane range (NSFQR) of at least about 0.0001 ⁇ /cm 2 , at least about 0.001 ⁇ /cm 2 , at least about 0.0002 ⁇ /cm 2 .
  • NSFQR normalized site frontside least squares focal plane range
  • Item 17 The substrate of item 1, wherein the body comprises an average global frontside least squares focal plane range (GFLR) of not greater than about 3.6 ⁇ , not greater than about 3.5 ⁇ , not greater than about 3.4 ⁇ , not greater than about 3.3 ⁇ , not greater than about 3.2 ⁇ , not greater than about 3.0 ⁇ , not greater than about 2.9 ⁇ , not greater than about 2.8 ⁇ , not greater than about 2.7 ⁇ , not greater than about 2.6 ⁇ , not greater than about 2.5 ⁇ , not greater than about 2.4 ⁇ , not greater than about 2.3 ⁇ , not greater than about 2.2 ⁇ , not greater than about 2.1 ⁇ , not greater than about 2.0 ⁇ , not greater than about 1.9 ⁇ , not greater than about 1.8 ⁇ , not greater than about 1.7 ⁇ , not greater than about 1.6 ⁇ , not greater than about 1.5 ⁇ , not greater than about 1.4 ⁇ , not greater than about 1.3 ⁇ , not greater than about 1.2 ⁇ , not greater than about 1.1 ⁇ , not greater than
  • Item 18 The substrate of item 1, wherein the GFLR is at least about 0.01 ⁇ , at least about
  • Item 19 The substrate of item 1, wherein the body comprises a normalized average global frontside least squares focal plane range (NGFLR) of not greater than about 0.14 ⁇ /cm 2 , not greater than about 0.13 ⁇ /cm 2 , not greater than about 0.12 ⁇ /cm 2 , not greater than about 0.11 ⁇ /cm 2 , not greater than about 0.10 ⁇ /cm 2 , not greater than about 0.09 ⁇ /cm 2 , not greater than about 0.08 ⁇ /cm 2 , not greater than about 0.07 ⁇ /cm 2 , not greater than about 0.06 ⁇ /cm 2 , not greater than about 0.05 ⁇ /cm 2 , not greater than about 0.04 ⁇ /cm 2 , not greater than about 0.03 ⁇ /cm 2 , not greater than about 0.02 ⁇ /cm 2 , not greater than about 0.01 ⁇ /cm 2 , not greater than about 0.009 ⁇ /cm 2 , not greater than about 0.008 ⁇ /
  • Item 20 The substrate of item 1, wherein the body comprises a normalized average global frontside least squares focal plane range (NGFLR) of at least about 0.0001 ⁇ /cm 2 , at least about Item 21.
  • the substrate of item 1, wherein the average roll off amount (ROA) of the body is not greater than about 0.58 ⁇ , not greater than about 0.55 ⁇ , not greater than about 0.53 ⁇ , not greater than about 0.5 ⁇ , not greater than about 0.48 ⁇ , not greater than about 0.45 ⁇ , not greater than about 0.43 ⁇ , not greater than about 0.4 ⁇ , not greater than about 0.38 ⁇ , not greater than about 0.35 ⁇ , and wherein the ROA is at least about 0.001 ⁇ , at least about 0.005 ⁇ .
  • NTFLR normalized average global frontside least squares focal plane range
  • Item 22 The substrate of item 1, wherein a ratio of the ROA to a wafer diameter is not greater than 0.12 ⁇ /cm, not greater than about 0.1 ⁇ /cm, not greater than about 0.07 ⁇ /cm, not greater than about 0.05 ⁇ /cm, not greater than about 0.012 ⁇ /cm, not greater than about 0.001 ⁇ /cm, and wherein the ratio of ROA to wafer diameter is at least 0.02 nm/cm, at least 0.1 nm/cm.
  • Item 23 The substrate of item 1, wherein the body comprises an upper surface having an average surface roughness R a of not greater than about 5 A, not greater than about 4.5 A, not greater than about 4.3 A, not greater than about 4.0 A, not greater than about 3.8 A , not greater than about 3.5 A, not greater than about 3.0 A, not greater than about 2.8 A, not greater than about 2.5 A, not greater than about 2.3 A, not greater than about 2.0 A, not greater than about 1.8 A, not greater than about 1.5 A, not greater than about 1.3 A, not greater than about 1.0 A, not greater than about 0.8 A, not greater than about 0.5 A, not greater than about 0.3 A, not greater than about 0.2 A, not greater than about 0.1 A.
  • R a average surface roughness R a of not greater than about 5 A, not greater than about 4.5 A, not greater than about 4.3 A, not greater than about 4.0 A, not greater than about 3.8 A , not greater than about 3.5 A, not greater than about 3.0 A, not greater
  • Item 24 The substrate of item 1, wherein the body comprises an upper surface having an average surface roughness Ra of at least about 0.01 A, at least about 0.05 A.
  • Item 25 The substrate of item 1, wherein the body comprises a reference indicium selected from the group consisting of a reference flat and a reference notch.
  • Item 26 The substrate of item 1, wherein the body comprises an upper surface and wherein at least a portion of a crystalline plane intersects the upper surface, wherein the crystalline plane is selected from the group consisting of a C-plane, a R-plane, a M-plane, and an A-plane.
  • Item 27 The substrate of item 1, wherein the body comprises an average thickness of not greater than about 2000 ⁇ , not greater than about 1800 ⁇ , not greater than about 1600 ⁇ , 1400 ⁇ , not greater than about 1380 ⁇ , not greater than about 1350 ⁇ , not greater than about 1320 ⁇ , not greater than about 1300 ⁇ , not greater than about 1280.
  • Item 28 The substrate of item 1, wherein the body comprises an average thickness of at least about 200 ⁇ , at least about 500 ⁇ , at least about 700 ⁇ .
  • Item 29 The substrate of item 1, wherein the body comprises a thickness/diameter ratio of at least about 0.005, at least about 0.006, at least about 0.007, and wherein the body comprises a thickness/diameter of not greater than about 0.05, not greater than about 0.03, not greater than about 0.01.
  • Item 30 The substrate of item 1, wherein the body comprises a total thickness variation
  • TTV TTV of not greater than about 6.5 ⁇ , such as not greater than about 6.3 ⁇ , not greater than about 6.0 ⁇ , not greater than about 5.7 ⁇ , not greater than about 5.3 ⁇ , not greater than about 5.0 ⁇ , not greater than about 4.7 ⁇ , not greater than about 4.5 ⁇ , not greater than about 4.3 ⁇ , not greater than about 4.0 ⁇ , not greater than about 3.7 ⁇ , not greater than about 3.5 ⁇ , not greater than about 3.3 ⁇ , not greater than about 3.0 ⁇ , not greater than about 2.7 ⁇ , not greater than about 2.3 ⁇ , not greater than about 2.5 ⁇ , not greater than about 2.3 ⁇ , or not greater than about 2.0 ⁇ .
  • Item 31 The substrate of item 1, wherein the body comprises a total thickness variation (TTV) of at least 0.01 ⁇ , such as at least 0.05 ⁇ , at least 0.1 ⁇ or at least 0.15 ⁇ .
  • TTV total thickness variation
  • Item 32 The substrate of item 1, wherein the body comprises a normalized total thickness variation (NTTV) of not greater than about 0.4 ⁇ /cm 2 , not greater than about 0.38 ⁇ /cm 2 , not greater than about 0.35 ⁇ /cm 2 , not greater than about 0.33 ⁇ /cm 2 , not greater than about 0.3 ⁇ /cm 2 , not greater than about 0.28 ⁇ /cm 2 , not greater than about 0.25 ⁇ /cm 2 , not greater than about 0.23 ⁇ /cm 2 , not greater than about 0.2 ⁇ /cm 2 , not greater than about 0.18 ⁇ /cm 2 , not greater than about 0.15 ⁇ /cm 2 , not greater than about 0.13 ⁇ /cm 2 , not greater than about 0.1 ⁇ /cm 2 , not greater than about 0.08 ⁇ /cm 2 , not greater than about 0.05 ⁇ /cm 2 , not greater than about 0.03 ⁇ /cm 2 , not greater than about 0.
  • Item 33 The substrate of item 1, wherein the NTTV is at least about 0.001 ⁇ /cm 2 , at least about 0.005 ⁇ /cm 2 .
  • Item 34 A batch of at least about 10 substrates, wherein each substrate of the batch comprises a body including alumina and wherein the batch comprises a batch characteristic selected from the group of:
  • NSFQRb normalized site frontside least squares focal plane range
  • NTFLRb normalized global frontside least squares focal plane range
  • Item 35 The batch of item 34, wherein each substrate of the batch comprises a body including a single crystalline material.
  • Item 36 The batch of item 34, wherein each substrate of the batch comprises a body including alumina.
  • Item 37 The batch of item 36, wherein each substrate of the batch comprises a body including sapphire.
  • each substrate of the batch comprises a body consisting essentially of sapphire.
  • the batch of item 34, wherein each substrate of the batch comprises a body having a diameter of at last about 5 cm, at least about 6 cm, at least about 7 cm, at least about 8 cm, at least about 9 cm, at least about 10 cm.
  • Item 40 The batch of item 34, wherein each substrate of the batch comprises a body having a diameter of not greater than about 50 cm, not greater than about 40 cm, not greater than about 30 cm.
  • each substrate of the batch comprises a body having an upper surface including an area of at least about 24 cm 2 , at least about 26 cm 2 , at least about 30 cm 2 , at least about 35 cm 2 , at least about 40 cm 2 , at least about 45 cm 2 , at least about 50 cm 2 , at least about 70 cm 2 , at least about 100 cm 2 , at least about 125 cm 2 , at least about 150 cm 2 , at least about 175 cm 2 .
  • Item 42 The batch of item 34, wherein the area is not greater than about 1000 cm 2 , not greater than about 800 cm 2 , not greater than about 600 cm 2 , not greater than about 400 cm 2 , not greater than about 300 cm 2 , not greater than about 200 cm 2 , not greater than about 190 cm 2 .
  • Item 43 The batch of item 34, wherein the NSFQRb is not greater than about 0.085 ⁇ /cm 2 , not greater than about 0.08 ⁇ /cm 2 , not greater than about 0.075 ⁇ /cm 2 , not greater than about 0.07 ⁇ /cm 2 , not greater than about 0.068 ⁇ /cm 2 , not greater than about 0.065 ⁇ /cm 2 , not greater than about 0.063 ⁇ /cm 2 , not greater than about 0.060 ⁇ /cm 2 , not greater than about 0.058 ⁇ /cm 2 , not greater than about 0.055 ⁇ /cm 2 , not greater than about 0.053 ⁇ /cm 2 , not greater than about 0.050 ⁇ /cm 2 , not greater than about 0.048 ⁇ /cm 2 , not greater than about 0.045 ⁇ /cm 2 , not greater than about 0.043 ⁇ /cm 2 , not greater than about 0.040 ⁇ /cm 2
  • Item 44 The batch of item 34, wherein the NSFQRb is at least about 0.0001 ⁇ /cm 2 , at least about 0.005 ⁇ /cm 2 , at least about 0.001 ⁇ /cm 2 , at least about 0.0015 ⁇ /cm 2 .
  • Item 45 The batch of item 36, further comprising an average bow of not greater than about 3.5 ⁇ , not greater than about 3.0 ⁇ , not greater than about 2.8 ⁇ , not greater than about 2.5 ⁇ , not greater than about 2.2 ⁇ , not greater than about 2 ⁇ , not greater than about 1.8 ⁇ .
  • Item 46 The batch of item 45, wherein the average bow is at least about 0.001 ⁇ .
  • Item 47 The batch of item 45, wherein the body comprises a negative bow defining a concave substrate wherein a midpoint of an upper surface of the body is lower than the peripheral edges of the substrate, and wherein the negative bow is at least about 0.001 ⁇ , at least about 0.1 ⁇ , at least about 0.5 ⁇ , at least about 0.8 ⁇ , at least about 1 micron, wherein the body comprises a positive bow defining a convex substrate, wherein a midpoint of an upper surface of the body is higher than a peripheral edge and wherein the positive bow is at least about 0.001 ⁇ , at least about 0.1 ⁇ , at least about 0.5 ⁇ , at least about 0.8 ⁇ , at least about 1 micron.
  • Item 48 The batch of item 34, wherein the NGFLRb is not greater than about 0.185 ⁇ /cm 2 , not greater than about 0.183 ⁇ /cm 2 , not greater than about 0.18 ⁇ /cm 2 , not greater than about
  • Item 49 The batch of item 34, wherein the NGFLRb is at least about 0.001 ⁇ /cm 2 , at least about 0.005 ⁇ /cm 2 .
  • Item 50 The batch of item 34, wherein the average roll off amount (ROAb) is not greater than about 0.58 ⁇ , not greater than about 0.55 ⁇ , not greater than about 0.53 ⁇ , not greater than about 0.5 ⁇ , not greater than about 0.48 ⁇ , not greater than about 0.45 ⁇ , not greater than about 0.43 ⁇ , not greater than about 0.4 ⁇ , not greater than about 0.38 ⁇ , not greater than about 0.35 ⁇ , and wherein the ROA is at least about 0.001 ⁇ , at least about 0.005 ⁇ .
  • ROAb average roll off amount
  • Item 51 The batch of item 50, wherein a ratio of the ROAb to a wafer diameter is not greater than 0.12 ⁇ /cm, not greater than about 0.1 ⁇ /cm, not greater than about 0.07 ⁇ /cm, not greater than about 0.05 ⁇ /cm, not greater than about 0.012 ⁇ /cm, not greater than about 0.001 ⁇ /cm, and wherein the ratio of ROA to wafer diameter is at least 0.02 nm/cm, at least 0.1 nm/cm.
  • Item 52 The batch of item 34, wherein an upper surface of each substrate of the batch has an average surface roughness R a of not greater than about 5 A, not greater than about 4.5 A, not greater than about 4.3 A, not greater than about 4.0 A, not greater than about 3.8 A , not greater than about 3.5 A, not greater than about 3.0 A, not greater than about 2.8 A, not greater than about 2.5 A, not greater than about 2.3 A, not greater than about 2.0 A, not greater than about 1.8 A, not greater than about 1.5 A, not greater than about 1.3 A, not greater than about 1.0 A, not greater than about 0.8 A, not greater than about 0.5 A, not greater than about 0.3 A, not greater than about 0.2 A, or not greater than about 0.1 A.
  • each substrate of the batch comprises a reference indicium selected from the group consisting of a reference flat and a reference notch.
  • each substrate of the batch comprises a body having an upper surface, wherein at least a portion of a crystalline plane intersects the upper surface, and wherein the crystalline plane is selected from the group consisting of a C -plane, a R-plane, a M-plane, and an A-plane.
  • Item 56 The batch of item 34, wherein the batch comprises an average thickness of not greater than about 2000 ⁇ , not greater than about 1800 ⁇ , not greater than about 1600 ⁇ , not greater than about 1400 ⁇ , not greater than about 1380 ⁇ , not greater than about 1350 ⁇ , not greater than about 1320 ⁇ , not greater than about 1300 ⁇ .
  • Item 57 The batch of item 34, wherein the batch comprises an average thickness of at least about 200 ⁇ , at least about 500 ⁇ , at least about 700 ⁇ .
  • Item 58 The batch of item 36, further comprising a batch normalized total thickness variation (NTTVb) of not greater than about 0.4 ⁇ /cm 2 , not greater than about 0.38 ⁇ /cm 2 , not greater than about 0.35 ⁇ /cm 2 , not greater than about 0.33 ⁇ /cm 2 , not greater than about 0.3 ⁇ /cm 2 , not greater than about 0.28 ⁇ /cm 2 , not greater than about 0.25 ⁇ /cm 2 , not greater than about 0.23 ⁇ /cm 2 , not greater than about 0.2 ⁇ /cm 2 , not greater than about 0.18 ⁇ /cm 2 , not greater than about 0.15 ⁇ /cm 2 , not greater than about 0.13 ⁇ /cm 2 , not greater than about 0.1 ⁇ /cm 2 , not greater than about 0.08 ⁇ /cm 2 , not greater than about 0.05 ⁇ /cm 2 , not greater than about 0.03 ⁇ /cm 2 , not greater than
  • Item 59 The batch of item 34, wherein the NTTVb is at least about 0.001 ⁇ /cm 2 , at least about 0.005 ⁇ /cm 2 , at least about 0.01 ⁇ /cm 2 .
  • Item 60 A method of forming a finished substrate comprising:
  • SFQR focal plane range
  • NSFQR normalized site frontside least squares focal plane range
  • GFLR global frontside least squares focal plane range
  • NTFLR normalized global frontside least squares focal plane range
  • ROA average roll off amount
  • Item 61 The method of item 60, wherein the double sided material removing process is a double-sided lapping process and removing material from an upper surface and a back surface of the substrate preform.
  • Item 62 The method of item 61, wherein conducting the double-sided lapping process is completed before removing material from the upper surface of the substrate preform using the bonded abrasive.
  • Item 63 The method of item 60, further comprising a first polishing time percentage (Tp/Tt)xl00% of not greater than about 92%, wherein Tp represents the time polishing for the entire process and Tt represents the total time of removing material from the upper surface of the substrate pre-form to form the finished substrate.
  • Tp/Tt first polishing time percentage
  • Item 64 The method of item 60, further comprising a second polishing time relationship (Tp/Tba) of not greater than about 15 , wherein Tp represents the time polishing for the entire process and Tba represents the time for removing material from the upper surface of the substrate preform except the time for polishing.
  • Tp/Tba polishing time relationship
  • Item 65 The method of item 60, wherein the bonded abrasive comprises a self-sharpening bonded abrasive wheel comprising diamond abrasive particles contained within a metal bond matrix material
  • Item 66 The method of item 60, wherein the midpoint-to periphery differential damage to the upper surface before polishing is not greater than about 2 ⁇ .
  • Item 67 The method of item 60, wherein the processes of removing material and polishing are conducted on a batch of at least 10 preform substrates to form a batch of finished substrates having a batch characteristic selected from the group of:
  • NSFQRb normalized site frontside least squares focal plane range
  • NTFLRb normalized global frontside least squares focal plane range
  • ROAb average roll off amount
  • Item 68 The method of item 60, further comprising cleaning a platform surface for processing the substrate preform prior to removing material from a surface of the substrate preform.
  • Item 69 The method of item 60, wherein the substrate includes sapphire.
  • Item 70 The batch of item 69, wherein the substrate consists essentially of sapphire.
  • Example 1 Unfinished round sapphire wafers with a diameter size of 150.6 mm have been prepared by Edge-Defined Film Fed Growth (EFG) followed by a coarse grinding procedure to remove the growth skin. At the unfinished stage, the sapphire wafers were about 2.0 mm thick with a surface roughness of about 0.7 to 0.9 ⁇ .
  • ESG Edge-Defined Film Fed Growth
  • the unfinished sapphire wafers were first subjected to an orientation adjustment based on x- ray measurements with an EFG diffractometer. During orientation adjustment, front-side and backside of the substrate were ground until the angle correction was completed, the top and bottom surfaces are parallel and a desired thickness reached.
  • the sapphire substrates were subjected to a double sided FAL using a diamond containing lapping plate from Gator Diamond with a diamond size of 230/270 mesh with a mean particle size of 73.8 ⁇ . Furthermore, the plate was dressed with alumina dressing stones having a grit of 220. A desired material removal amount of between about 100 to about 140 ⁇ was reached in less than about 20 minutes. The machine was programmed to stop when a specific thickness target has been reached.
  • the sapphire substrates were subjected to top side grinding in a Koyo grinder, using a commercial grinding wheel having an 800 grit (wheel specification FINE#4-17-XL073 from Saint Gobain Abrasives, Inc).
  • the amount of sapphire material removed during fine top side grinding was between about 20 to 30 ⁇ , in a grinding time of about 3.5 minutes.
  • the surface roughness R a after the fine top side grinding was less than 130 nm.
  • Table 2 Top side fine grinding conditions (Koyo grinder)
  • the sapphire substrates were subjected to edge grinding and annealing.
  • edge grinding a bevel was cut with a 45 degree angle on the top and bottom edges of the substrate, thereby removing about 300 ⁇ off the edges.
  • the sapphire substrates were subjected to annealing under vacuum at a temperature of 1500°C for 12 hours.
  • the sapphire substrates were polished using the combination of a hard pad and an alumina slurry.
  • the hard pad was a waffle grooved MH S15A pad of polyester fiber / polyurethane resin material.
  • the alumina slurry contained fine alumina particles with a secondary particle size of about 200 nm.
  • about 10 ⁇ sapphire substrate material was removed from the substrate surface in a time of about 3 hours. A removal amount of only 10 ⁇ was required since the subsurface damage of the substrates after fine grinding was only 5-7 ⁇ .
  • Unfinished EFG manufactured sapphire substrates as used in Example 1 have been coarse ground via double sided lapping using a free moving aqueous abrasive slurry containing boron carbide (B4C) with a 320 grit size in an amount of 23.3 wt%, see Figure 6.
  • the removal amount during coarse grinding was about 110-130 ⁇ .
  • the sapphire substrates were subjected to edge grinding and annealing as described in Example 1. After annealing, the sapphire substrates had a subsurface damage (SSD) of 28 ⁇ .
  • SSD subsurface damage
  • the sapphire substrates were subjected to polishing.
  • a grinding time of about 5-6 hours was required, for which a soft grinding pad (ceiba) together with an alumina abrasive slurry was used.
  • the SFQR was measured in a Tropel UltraSort Wafer Flatness Analysis System shape metrology tool. An amount of 80 measuring sites per substrate throughout the surface were measured, with an edge exclusion of 0.5 mm; the measured surface area at each measuring point was 15 x 15 mm. From the multitude of measuring points throughout a substrate, the SFQR value with the highest value has always been selected (see Figure 2A). The SFQR measurement was further conducted in compliance with SEMI Ml-1111 and SEMI MF1530-0707.
  • Figure 7 shows a representative wafer according to one embodiment.
  • the wafer is divided into a grid of squares of 15x15 mm size and shows the SFQR values for 80 measuring points throughout the wafer surface. It can be seen that the SFQR throughout the wafer is very low, such as not larger than 0.5 ⁇ , and only the measuring points close to the edge regions have an SFQR upto about 1.3 ⁇ . There are no locations in the center region of the wafer that show a sudden SFQR change which would negatively influence the wafer quality.
  • the GFLR was also measured with the Tropel UltraSort Wafer Flatness Analysis system. For the GFLR, the entire substrate surface area was measured with an edge exclusion of 0.5 mm (see Figure 2B). The GFLR measurement was further conducted in compliance with SEMI Ml-1111 and SEMI MF1530-0707. Measurement of Total Thickness Variation (TTV)
  • the TTV (also called GBIR) was measured with the Tropel UltraSort Wafer Flatness Analysis system. For the TTV, the entire substrate surface area was measured with an edge exclusion of 0.5 mm. The TTV measurement was further conducted in compliance with SEMI Ml-1111 and SEMI MF1530-0707.
  • the ROA was measured with a Bruker Dektak XT Stylus Profilometer.
  • ROA is measured according to the diagram shown in Figure 3, at a distance (31) of 1 mm from the substrate edge (32).
  • the stylus travels radially in the outer region of the substrate towards the substrate's edge (32), probing the top polished surface of the substrate, and locating the substrate edge (32).
  • the substrate edge (32) is defined as the meeting point of top bevel (33) and the top polished surface (see Figure 3).
  • the ROA is the distance between an extended line (34) that goes through points (35) and (36) of the polished top surface, and the upper surface of the polished wafer at a position of 1 mm away from the substrate edge (32), wherein point (35) of the extended line has a distance of 3 mm to the substrate edge (32), and point (36) has a distance of 5 mm to the substrate edge (32).
  • the ROA measurement was further conducted in compliance with SEMI M77-1110.
  • the exclusion zone corresponds to an area close to the edge of the wafer where SFQR, GFLR, ROA and TTV are not complying to desired quality standards anymore. As shown in Table 5, it could be demonstrated that an edge exclusion of 0.5 mm still provides acceptable values for SFQR, GFLR, and TTV, although the values with decreasing edge exclusion become clearly higher. The data shown in Table 5 allowed the conclusion that an exclusion zone exist only in the area below 0.5 mm distance from the edge of the sapphire substrate.
  • Table 5 demonstrates how the parameters SFQR, GFLR and TTV vary by limiting the edge exclusion of the substrate testing from 5 mm to 0.5 mm.
  • the subsurface damage (SSD) was determined by measuring the difference in the wafer thickness before and after removal of the SSD in a series of lapping and polishing steps.
  • the investigation of the wafer surface to evaluate SSD was made with an optical microscope using a magnification to cover the field of view of 180 ⁇ x 135 ⁇ .
  • Table 6 demonstrates that SSD throughout the sapphire substrate before the final polishing step 106 was very low between 4 to 6 ⁇ and evenly distributed.
  • the SSD in the edge area was measured at a distance of 3 mm from the edge in an area of 3 ⁇ 4 of an inch.
  • the low SSD before polishing allowed the use of a hard pad (MHS15A from Eminess) for polishing, since only a low amount of surface substance needed to be removed.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Chemical & Material Sciences (AREA)
  • Ceramic Engineering (AREA)
  • Inorganic Chemistry (AREA)
  • Mechanical Treatment Of Semiconductor (AREA)

Abstract

Cette invention concerne des substrats de saphir appropriés pour la fabrication de semi-conducteurs, caractérisés par des caractéristiques dimensionnelles et de forme supérieures. Lesdits substrats de saphir sont spécifiquement caractérisés en ce qu'ils présentent une très faible planéité locale et gobale (SFQR et GFLR) et un faible coefficient de déviation par rapport au plan (ROA). L'invention concerne en outre un procédé de fabrication de substrats de saphir présentant de très faibles coefficients GFLR SFQR et ROA, ledit procédé étant économe en temps.
PCT/US2015/029875 2014-05-09 2015-05-08 Substrats de saphir de haute qualité et procédé de fabrication desdits substrats de saphir Ceased WO2015172014A1 (fr)

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CN109290853A (zh) * 2017-07-24 2019-02-01 蓝思科技（长沙）有限公司 一种超薄蓝宝石片的制备方法

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CN109290853B (zh) * 2017-07-24 2021-06-04 蓝思科技（长沙）有限公司 一种超薄蓝宝石片的制备方法

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