Classifications

• • C—CHEMISTRY; METALLURGY
  • C03—GLASS; MINERAL OR SLAG WOOL
  • C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
  • C03C21/00—Treatment of glass, not in the form of fibres or filaments, by diffusing ions or metals in the surface
  • C03C21/001—Treatment of glass, not in the form of fibres or filaments, by diffusing ions or metals in the surface in liquid phase, e.g. molten salts, solutions
  • C03C21/002—Treatment of glass, not in the form of fibres or filaments, by diffusing ions or metals in the surface in liquid phase, e.g. molten salts, solutions to perform ion-exchange between alkali ions
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10P—GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10
  • H10P72/00—Handling or holding of wafers, substrates or devices during manufacture or treatment thereof
  • H10P72/70—Handling or holding of wafers, substrates or devices during manufacture or treatment thereof for supporting or gripping
  • H10P72/74—Handling or holding of wafers, substrates or devices during manufacture or treatment thereof for supporting or gripping using temporarily an auxiliary support
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10W—GENERIC PACKAGES, INTERCONNECTIONS, CONNECTORS OR OTHER CONSTRUCTIONAL DETAILS OF DEVICES COVERED BY CLASS H10
  • H10W74/00—Encapsulations, e.g. protective coatings
  • H10W74/01—Manufacture or treatment
  • H10W74/019—Manufacture or treatment using temporary auxiliary substrates
• • C—CHEMISTRY; METALLURGY
  • C03—GLASS; MINERAL OR SLAG WOOL
  • C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
  • C03C3/00—Glass compositions
  • C03C3/04—Glass compositions containing silica
  • C03C3/076—Glass compositions containing silica with 40% to 90% silica, by weight
  • C03C3/083—Glass compositions containing silica with 40% to 90% silica, by weight containing aluminium oxide or an iron compound
  • C03C3/085—Glass compositions containing silica with 40% to 90% silica, by weight containing aluminium oxide or an iron compound containing an oxide of a divalent metal
  • C03C3/087—Glass compositions containing silica with 40% to 90% silica, by weight containing aluminium oxide or an iron compound containing an oxide of a divalent metal containing calcium oxide, e.g. common sheet or container glass
• • C—CHEMISTRY; METALLURGY
  • C03—GLASS; MINERAL OR SLAG WOOL
  • C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
  • C03C3/00—Glass compositions
  • C03C3/04—Glass compositions containing silica
  • C03C3/076—Glass compositions containing silica with 40% to 90% silica, by weight
  • C03C3/089—Glass compositions containing silica with 40% to 90% silica, by weight containing boron
  • C03C3/091—Glass compositions containing silica with 40% to 90% silica, by weight containing boron containing aluminium
  • C03C3/093—Glass compositions containing silica with 40% to 90% silica, by weight containing boron containing aluminium containing zinc or zirconium
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10P—GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10
  • H10P72/00—Handling or holding of wafers, substrates or devices during manufacture or treatment thereof
  • H10P72/70—Handling or holding of wafers, substrates or devices during manufacture or treatment thereof for supporting or gripping
  • H10P72/74—Handling or holding of wafers, substrates or devices during manufacture or treatment thereof for supporting or gripping using temporarily an auxiliary support
  • H10P72/7424—Handling or holding of wafers, substrates or devices during manufacture or treatment thereof for supporting or gripping using temporarily an auxiliary support used as a support during the manufacture of self-supporting substrates
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10P—GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10
  • H10P72/00—Handling or holding of wafers, substrates or devices during manufacture or treatment thereof
  • H10P72/70—Handling or holding of wafers, substrates or devices during manufacture or treatment thereof for supporting or gripping
  • H10P72/74—Handling or holding of wafers, substrates or devices during manufacture or treatment thereof for supporting or gripping using temporarily an auxiliary support
  • H10P72/7436—Handling or holding of wafers, substrates or devices during manufacture or treatment thereof for supporting or gripping using temporarily an auxiliary support used to support a device or a wafer when forming electrical connections thereto
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10W—GENERIC PACKAGES, INTERCONNECTIONS, CONNECTORS OR OTHER CONSTRUCTIONAL DETAILS OF DEVICES COVERED BY CLASS H10
  • H10W70/00—Package substrates; Interposers; Redistribution layers [RDL]
  • H10W70/01—Manufacture or treatment
  • H10W70/05—Manufacture or treatment of insulating or insulated package substrates, or of interposers, or of redistribution layers
  • H10W70/08—Manufacture or treatment of insulating or insulated package substrates, or of interposers, or of redistribution layers by depositing layers on the chip or wafer, e.g. "chip-first" RDLs
  • H10W70/09—Manufacture or treatment of insulating or insulated package substrates, or of interposers, or of redistribution layers by depositing layers on the chip or wafer, e.g. "chip-first" RDLs extending onto an encapsulation that laterally surrounds the chip or wafer, e.g. fan-out wafer level package [FOWLP] RDLs
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10W—GENERIC PACKAGES, INTERCONNECTIONS, CONNECTORS OR OTHER CONSTRUCTIONAL DETAILS OF DEVICES COVERED BY CLASS H10
  • H10W72/00—Interconnections or connectors in packages
  • H10W72/01—Manufacture or treatment
  • H10W72/0198—Manufacture or treatment batch processes
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10W—GENERIC PACKAGES, INTERCONNECTIONS, CONNECTORS OR OTHER CONSTRUCTIONAL DETAILS OF DEVICES COVERED BY CLASS H10
  • H10W72/00—Interconnections or connectors in packages
  • H10W72/20—Bump connectors, e.g. solder bumps or copper pillars; Dummy bumps; Thermal bumps
  • H10W72/241—Dispositions, e.g. layouts
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10W—GENERIC PACKAGES, INTERCONNECTIONS, CONNECTORS OR OTHER CONSTRUCTIONAL DETAILS OF DEVICES COVERED BY CLASS H10
  • H10W72/00—Interconnections or connectors in packages
  • H10W72/90—Bond pads, in general
  • H10W72/941—Dispositions of bond pads
  • H10W72/9413—Dispositions of bond pads on encapsulations
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10W—GENERIC PACKAGES, INTERCONNECTIONS, CONNECTORS OR OTHER CONSTRUCTIONAL DETAILS OF DEVICES COVERED BY CLASS H10
  • H10W74/00—Encapsulations, e.g. protective coatings
  • H10W74/01—Manufacture or treatment
  • H10W74/014—Manufacture or treatment using batch processing
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10W—GENERIC PACKAGES, INTERCONNECTIONS, CONNECTORS OR OTHER CONSTRUCTIONAL DETAILS OF DEVICES COVERED BY CLASS H10
  • H10W74/00—Encapsulations, e.g. protective coatings
  • H10W74/01—Manufacture or treatment
  • H10W74/016—Manufacture or treatment using moulds

Definitions

• the present specification generally relates to carriers for use in microelectronics fabrication and, more specifically, to carriers for use in microelectronics fabrication comprising strengthened substrates formed from glass or glass-ceramic.
• Carriers are used during the fabrication of microelectronic wafers or panels to support various components as the wafers or panels are“built” layer by layer on the carrier.
• Conventional fabrication techniques such as fan-out wafer level packaging (FOWLP) and fan-out panel level packaging (FOPLP), expose the carrier to mechanical stresses, elevated temperatures, and harsh chemical environments, each of which may degrade the performance of conventional carrier made from silicon, rendering the carrier unsuitable for more than a single use.
• FOWLP fan-out wafer level packaging
• FOPLP fan-out panel level packaging
• a carrier for microelectronics fabrication may include a strengthened substrate formed from glass or glass-ceramic.
• the strengthened substrate may have a first surface, a second surface opposite the first surface and an average thickness between the first surface and the second surface greater than 1.0 mm and less than or equal to 2.0 mm.
• a single-side surface area of the strengthened substrate may be greater than or equal to 70,000 mm 2 .
• the strengthened glass substrate may also include a first compressive stress layer extending inward from the first surface towards a center of the strengthened substrate, the first compressive stress layer having a first depth of layer greater than or equal to 50 pm and less than or equal to 150 pm.
• a second compressive stress layer may extend inward from the second surface towards the center of the strengthened substrate, the second compressive stress layer having a second depth of layer greater than or equal to 50 pm and less than or equal to 150 pm.
• a surface compressive stress at the first surface and the second surface of the strengthened substrate may be greater than or equal to 200 MPa.
• the strengthened substrate may further include a tensile stress region positioned between the first compressive stress layer and the second compressive stress layer, the tensile stress region having a stored elastic energy of less than 40 kJ/m 2 .
• a flat fragmentation factor of the strengthened glass substrate may be less than or equal to 5.
• Another aspect includes the carrier of any of the foregoing aspects, wherein the surface compressive stress at the first surface and the second surface of the strengthened substrate is less than or equal to 700 MPa.
• Another aspect includes the carrier of any of the foregoing aspects, wherein the surface compressive stress at the first surface and the second surface of the strengthened substrate is greater than or equal to 450 MPa and less than or equal to 650 MPa.
• Another aspect includes the carrier of any of the foregoing aspects, wherein the first depth of layer and the second depth of layer are greater than or equal to 60 pm and less than or equal to 100 pm.
• Another aspect includes the carrier of any of the foregoing aspects, wherein the stored elastic energy in the tensile stress region is less than or equal to 38.8 kJ/m 2 .
• Another aspect includes the carrier of any of the foregoing aspects, wherein the stored elastic energy in the tensile stress region is less than or equal to 38 kJ/m 2 .
• Another aspect includes the carrier of any of the foregoing aspects, wherein the strengthened substrate has a flat fragmentation factor of less than or equal to 3.
• Another aspect includes the carrier of any of the foregoing aspects, wherein the first surface has a surface roughness Ra of less than or equal to 1 pm.
• Another aspect includes the carrier of any of the foregoing aspects, wherein the strengthened substrate has a transmittance of greater than or equal to 50% for wavelengths of light greater than or equal to 300 nm and less than or equal to 355 nm.
• Another aspect includes the carrier of any of the foregoing aspects, wherein the strengthened substrate has a transmittance of greater than or equal to 70% for wavelengths of light greater than or equal to 300 nm and less than or equal to 355 nm.
• Another aspect includes the carrier of any of the foregoing aspects, wherein the strengthened substrate has a flexural rigidity greater than or equal to 10 GPa-mm 3 .
• Another aspect includes the carrier of any of the foregoing aspects, wherein the strengthened substrate has a retained strength greater than or equal to 300 MPa after indentation with an indent load of 1 kilogram- force.
• Another aspect includes the carrier of any of the foregoing aspects, wherein the strengthened substrate has a retained strength greater than or equal to 100 MPa after indentation with an indent load of 2 kilogram- force.
• Another aspect includes the carrier of any of the foregoing aspects, wherein the strengthened substrate has a retained strength greater than or equal to 70 MPa after indentation with an indent load of 3 kilogram- force.
• Another aspect includes the carrier of any of the foregoing aspects, wherein the strengthened substrate has a retained strength greater than or equal to 45 MPa after indentation with an indent load of 4 kilogram- force.
• Another aspect includes the carrier of any of the foregoing aspects, wherein the strengthened substrate has an average thickness of less than or equal to 1.8 .
• Another aspect includes the carrier of any of the foregoing aspects, wherein the strengthened substrate has an average thickness of less than or equal to 1.5 .
• Another aspect includes the carrier of any of the foregoing aspects, wherein the strengthened substrate has an average thickness of less than or equal to 1.1 .
• Another aspect includes the carrier of any of the foregoing aspects, wherein the strengthened substrate is an ion exchange strengthened substrate.
• Another aspect includes the carrier of any of the foregoing aspects, wherein the strengthened substrate comprises a coefficient of thermal expansion greater than or equal to 9x10 6 K _1 averaged over a temperature range from 20°C to 300°C.
• Another aspect includes the carrier of any of the foregoing aspects, wherein the strengthened substrate comprises alkali aluminosilicate glass.
• Another aspect includes the carrier of any of the foregoing aspects, wherein the strengthened substrate has an in-process warp of less than or equal to 4,000 pm and greater than or equal to -9,000 pm.
• Another aspect includes the carrier of any of the foregoing aspects, wherein the strengthened substrate has an as-formed warp of greater than or equal to 0 pm and less than or equal to 500 pm.
• a method of forming a carrier for microelectronics fabrication may include immersing a glass or glass-ceramic substrate in a molten salt bath comprising a mixture of from about 90 wt.% to about 98% potassium nitrate and from about 2 wt.% to about 10 wt.% sodium nitrate at a temperature greater than or equal to 380°C and less than or equal to 460°C for greater than or equal to 5 hours and less than or equal to 30 hours.
• the glass or glass-ceramic substrate may include a first surface, a second surface opposite the first surface, a single-side surface area greater than or equal to 70,000 mm 2 , and an average thickness between the first surface and the second surface greater than 1.0 mm and less than or equal to 2.0 mm.
• Another aspect includes the method of any of the foregoing aspects, wherein the molten salt bath comprises a mixture of from about 93 wt.% to about 95 wt.% potassium nitrate and from about 5 wt.% to about 7 wt.% sodium nitrate.
• Another aspect includes the method of any of the foregoing aspects, wherein the glass or glass-ceramic substrate is immersed in the molten salt bath at a temperature of about 450°C for greater than or equal to 6 hours to less than or equal to about 15 hours.
• Another aspect includes the method of any of the foregoing aspects, wherein, after the glass or glass-ceramic substrate is immersed in the molten salt bath, the glass or glass-ceramic substrate includes a first compressive stress layer extending inward from the first surface towards a center of the glass or glass-ceramic substrate, the first compressive stress layer having a first depth of layer greater than or equal to 50 pm and less than or equal to 150 pm.
• the substrate may also include a second compressive stress layer extending inward from the second surface towards the center of the glass or glass-ceramic substrate, the second compressive stress layer having a second depth of layer greater than or equal to 50 pm and less than or equal to 150 pm, wherein a surface compressive stress at the first surface and the second surface of the glass or glass-ceramic substrate is greater than or equal to 200 MPa.
• the substrate may also include a tensile stress region positioned between the first compressive stress layer and the second compressive stress layer, the tensile stress region having a stored elastic energy of less than 40 kJ/m 2 .
• the substrate may also have a flat fragmentation factor less than or equal to 5.
• FIG. 1 schematically depicts a process for fabricating microelectronics on a carrier
• FIG. 2 schematically depicts a top view of a carrier comprising a strengthened substrate formed from glass or glass-ceramic according to one or more embodiments described herein;
• FIG. 3 schematically depicts a cross-sectional view of the carrier of FIG. 2;
• FIG. 4 schematically depicts a cross sectional view of a substrate, such as a strengthened substrate, undergoing indentation with an indenter for purposes of assessing the retained strength of the substrate;
• FIG. 5 schematically depicts a cross sectional view of a substrate, such as a strengthened substrate, in 4-point bending for purposes of assessing the retained strength of the substrate following indentation;
• FIG. 6 schematically depicts a cross sectional view of a substrate, such as a strengthened substrate, with an applied flat fragmentation load for purposes of assessing the flat fragmentation factor of the substrate;
• FIG. 7 depicts a drawing (based on a photograph) of a strengthened substrate after flat fragmentation testing showing that the strengthened substrate fragmented into two primary fragments (i.e., the strengthened substrate had a flat fragmentation factor of 2);
• FIG. 8 depicts a drawing (based on a photograph) of an un-strengthened substrate after flat fragmentation testing showing that the un-strengthened substrate fragmented into four primary fragments (i.e., the un-strengthened substrate had a flat fragmentation factor of 4);
• FIG. 9 graphically depicts the retained strength (Y ordinate, in MPa) as a function of indent load (X ordinate, in kilogram-force) for strengthened substrates and un-strengthened substrates;
• FIG. 10 graphically depicts the in-process warpage (Y ordinate, in pm) as a function of substrate thickness (X ordinate, in millimeters) for substrates of different thicknesses and with different coatings applied.
• the carrier generally includes a strengthened substrate formed from glass or glass-ceramic.
• the strengthened substrate may have a first surface, a second surface opposite the first surface and an average thickness between the first surface and the second surface greater than 1.0 mm and less than or equal to 2.0 mm.
• a single-side surface area of the strengthened substrate may be greater than or equal to 70,000 mm 2 .
• the strengthened glass substrate may also include a first compressive stress layer extending inward from the first surface towards a center of the strengthened substrate, the first compressive stress layer having a first depth of layer greater than or equal to 50 pm and less than or equal to 150 pm.
• a second compressive stress layer may extend inward from the second surface towards the center of the strengthened substrate, the second compressive stress layer having a second depth of layer greater than or equal to 50 pm and less than or equal to 150 pm.
• a surface compressive stress at the first surface and the second surface of the strengthened substrate may be greater than or equal to 200 MPa.
• the strengthened substrate may further include a tensile stress region positioned between the first compressive stress layer and the second compressive stress layer, the tensile stress region having a stored elastic energy of less than 40 kJ/m 2 .
• a flat fragmentation factor of the strengthened glass substrate may be less than or equal to 5.
• ranges can be expressed herein as from“about” one particular value, and/or to“about” another particular value. When such a range is expressed, another embodiment includes from the one particular value and/or to the other particular value. Similarly, when values are expressed as approximations, by use of the antecedent“about,” it will be understood that the particular value forms another embodiment lt will be further understood that the endpoints of each of the ranges are significant both in relation to the other endpoint, and independently of the other endpoint.
• CTE refers to the coefficient of thermal expansion of the substrate averaged over a temperature range from 20°C to 300°C.
• the elastic modulus (also referred to as Young’s modulus) of the substrate is provided in units of gigapascals (GPa).
• the elastic modulus of the substrate is determined by resonant ultrasound spectroscopy on bulk samples of the substrate.
• Compressive stress and depth of layer are determined with a fundamental stress meter (FSM) instrument, such as the FSM-6000, manufactured by Orihara Co., Ltd. (Tokyo, japan), with the compressive stress value based on the measured stress optical coefficient (SOC).
• FSM fundamental stress meter
• the FSM instrument couples light into and out of the birefringent surface of the substrate.
• the measured birefringence is then related to stress through a material constant, the stress-optic or photoelastic coefficient (SOC or PEC) and two parameters are obtained: the maximum surface compressive stress (CS) and the exchanged depth of layer (DOL).
• Axial transmittance (referred to herein as“transmittance”) for wavelengths of ultraviolet light was determined with a Lambda 950 UV/Vis Spectrophotometer manufactured by PerkinElmer Inc. (Waltham, Massachusetts USA).
• the Lambda 950 apparatus was fitted with a 150 mm integrating sphere with operating parameters of 2500 nm to 200 nm.
• the process 10 may be, for example, a fan out process for manufacturing a wafer having microelectronic devices embedded thereon.
• the process 10 generally includes an initial step 12 of laminating a tape 32 to a carrier 34 comprising a substrate.
• the substrate of the carrier is formed from, for example, silicon.
• electronic components 36 are placed on the tape 32.
• a wafer 38 may then be molded over the electronic components 36 in step 16.
• the carrier 34 may be removed (also referred to as“debonded”) from the formed wafer in step 18.
• a ball grid array 40 may be applied to the wafer 38 and, thereafter, the wafer 38 may be diced into discrete microelectronic components 42.
• the substrate of the carrier should also facilitate laser de-bonding of the wafer from the substrate and also be able to withstand the stresses and harsh chemical environment of the microelectronics fabrication process.
• Glass substrates have been identified as a suitable alternative to conventional carrier substrates formed from silicon due to the superior flatness of the glass substrate, optical transparency at certain wavelengths, dimensional stability, and chemical durability. Indeed, with respect to at least dimensional stability and chemical durability, glass substrates present a significant improvement over conventional carrier substrates, allowing for the glass substrates to be reused in the microelectronic process several times before being discarded.
• un-strengthened glass substrates are not without drawbacks. In particular, un-strengthened glass substrates used in carriers for microelectronics fabrication may experience a variety of mechanical stresses as various components are pressed and/or molded on the surface of the substrate.
• the embodiments described herein relate to carriers comprising strengthened substrates for use in microelectronics fabrication.
• the strengthened substrates are formed from glass or glass-ceramic which mitigates the failure of the substrates due to routine mechanical insults that occur during the microelectronics fabrication process.
• the strengthened substrates described herein provide for selective failure of the substrates and also reduce the number of fragments created upon failure of the substrate.
• the carriers 100 described herein include a strengthened substrate 102.
• the carrier 100 may further include additional components including, without limitation, coatings, registration features and the like.
• the strengthened substrate 102 of the carrier 100 is rectangular or square in shape.
• FIG. 2 schematically depicts the strengthened substrate 102 as being rectangular or square in cross section, it should be understood that other shapes for the strengthened substrate are contemplated and possible including, without limitation, regular geometrical shapes such as circles, triangles, octagons, and the like, or irregular geometric shapes.
• the shape of the strengthened substrate may be specifically tailored to provide registration features by which the strengthened substrate can be oriented during microelectronic fabrication processes.
• the strengthened substrate 102 has a first surface 104, a second surface 106 opposite the first surface, and an average thickness T between the first surface 104 and the second surface 106.
• the strengthened substrate 102 may have a relatively large surface area to maximize the number of microelectronic devices fabricated per carrier.
• the single-side surface area i.e., the area of the first surface 104 of the strengthened substrate 102 or the second surface 106 of the strengthened substrate 102
• the single-side surface area of the strengthened substrate 102 may be greater than or equal to 90,000 mm 2 or even greater than or equal to 122,500 mm 2 .
• the single-side surface area of the strengthened substrate 102 may be greater than or equal to 160,000 mm 2 or even greater than or equal to 202,500 mm 2 . In some of these embodiments, the single-side surface area of the strengthened substrate 102 may be greater than or equal to 250,000 mm 2 or even greater than or equal to 302,500 mm 2 . In some of these embodiments, the single-side surface area of the strengthened substrate 102 may be greater than or equal to 360,000 mm 2 or even greater than or equal to 422,500 mm 2 . In some of these embodiments, the single-side surface area of the strengthened substrate 102 may be greater than or equal to 490,000 mm 2 or even greater than or equal to 562,500 mm 2 .
• the single-side surface area of the strengthened substrate 102 may be greater than or equal to 640,000 mm 2 or even greater than or equal to 722,500 mm 2 . In some of these embodiments, the single-side surface area of the strengthened substrate 102 may be greater than or equal to 810,000 mm 2 or even greater than or equal to 902,500 mm 2 . In each of the aforementioned embodiments, the single-side surface area of the strengthened substrate 102 may be less than or equal to 1 m 2 .
• the average thickness T of the strengthened substrate 102 may be greater than 1.0 mm and less than or equal to 2.0 mm. If the strengthened substrate 102 has an average thickness of less than about 1.0 mm, the substrate may warp or bow significantly during the microelectronic fabrication process which may result in unacceptable process variations. If the strengthened substrate 102 has an average thickness of greater than about 2.0 mm, the thickness of the substrate combined with the thickness of the various layers and components deposited on the substrate may be too large for the spatial constraints of the microelectronic fabrication equipment. In the embodiments of the carrier 100 described herein, the average thickness T of the strengthened substrate 102 may be less than or equal to 1.8 mm, less than or equal to 1.5 mm, or even less than or equal to 1.1 mm.
• the strengthened substrates 102 described herein are glass or glass-ceramic and may be formed from a variety of different glass and/or glass-ceramic compositions.
• the strengthened substrate is formed from alkali aluminosilicate glass compositions.
• the strengthened substrate may be formed from an alkali aluminosilicate glass composition which comprises: from about 57 mol.% to about 75 mol.% Si0 2 ; from about 7 mol.% to about 17 mol.% Al 2 0 3 ; 0 mol.% to about 12 mol.% B 2 0 3 ; from about 9 mol.% to about 21 mol.% Na 2 0; 0 mol.% to about 4 mol.% K 2 0; 0 mol.% to about 7 mol.% MgO; and 0 mol.% to about 3 mol.% CaO.
• an alkali aluminosilicate glass composition which comprises: from about 57 mol.% to about 75 mol.% Si0 2 ; from about 7 mol.% to about 17 mol.% Al 2 0 3 ; 0 mol.% to about 12 mol.% B 2 0 3 ; from about 9 mol.% to about 21 mol.% Na 2 0;
• the strengthened substrate may be formed from an alkali aluminosilicate glass composition which comprises: 69.49 mol.% Si0 2 , 8.45 mol.% Al 2 0 3 , 14.01 mol.% Na 2 0, 1.16 mol.% K 2 0, 0.185 mol.% Sn0 2 , 0.507 mol.% CaO, 6.2 mol.% MgO, 0.01 mol.% Zr0 2 , and 0.008 mol.% Fe 2 0 3 .
• the strengthened substrate may be formed from an alkali aluminosilicate glass composition which comprises: 67.55 mol.% Si0 2 , 3.67 mol.% B 2 0 3 , 12.67 mol.% A! 2 0 3 , 13.66 mol.% Na 2 0, 0.014 mol.% K 2 0, 2 33 mol.% MgO, 0 mol.% CaO, 0.008 mol.% Fe 2 0 3 , 0.005 mol.% ZrO , 0.10 mol.% Sn0 2 ).
• the strengthened substrate may be formed from an alkali aluminosilicate glass composition which comprises: from about 57 mol.% to about 75 mol.% Si0 2 ; from about 6 mol.% to about 17 mol.% Al 2 0 3 ; 0 mol.% to about 15 mol.% B 2 0 3 ; 0 mol.% to about 15 mol.
• the strengthened substrate may be formed from an alkali aluminosilicate glass composition which comprises: 66.16% Si0 2 , 10.29% Al 2 0 3 , 14.0% Na 2 0, 2.45% K 2 0, 0.6 mol.% B 2 0 3 , 0.21% Sn0 2 , 0.58 mol.% CaO, 5.7 mol.% MgO, 0.0105 mol.% Zr0 2 , and 0.0081 mol.% Fe 2 0 3 .
• the strengthened substrate may be formed from an alkali aluminosilicate glass composition which comprises: 64.74 mol.% Si0 2 , 5.14 moi.% B ?
• Suitable glass compositions from which the strengthened substrates may be made further include, for example and without limitation: the glass compositions described in U.S. Patent No. 8,969,226 entitled“Glasses Having lmproved Toughness And Scratch Resistance” and assigned to Coming lncorporated; the glass compositions described in U.S. Patent No. 8,586,492 entitled“Crack and Scratch Resistant Glass And Enclosures Made Therefrom” and assigned to Coming lncorporated; and the glass compositions described in U.S. Patent No. 8,951,927 entitled “Zircon Compatible, lon Exchangeable Glass With High Damage Resistance” and assigned to Coming lncorporated.
• the strengthened substrates of the carriers may also be formed from glass-ceramic materials that are amenable to strengthening by ion exchange.
• suitable glass- ceramic compositions include, without limitation, the glass-ceramics disclosed in U.S. Patent Publication No. 2016/0102010 entitled“HIGH STRENGTH GLASS-CERAMICS HAVING PETALITE AND LITHIUM SILICATE STRUCTURES” and assigned to Coming lncorporated.
• compositions and/or composition spaces are described it should be understood that these compositions and/or composition spaces are illustrative and that other glass or glass-ceramic compositions are contemplated and possible.
• the first surface 104 of the strengthened substrate 102 may be the surface upon which microelectronic components are placed during the microelectronic fabrication process while the second surface 106 of the strengthened substrate 102 is an underside of the carrier 100.
• the first surface 104 of the strengthened substrate 102 has a surface roughness Ra of less than or equal to 1 pm or even a surface roughness Ra of less than or equal to 0.5 pm.
• the first surface 104 has a surface roughness Ra of less than or equal to 0.2 pm or even a surface roughness Ra of less than or equal to 0.1 pm.
• the first surface 104 of the strengthened substrate 102 has a surface roughness Ra of less than or equal to 0.01 pm.
• the second surface 106 of the strengthened substrate 102 may have the same surface roughness as the first surface 104 of the strengthened substrate 102. In some other embodiments, the second surface 106 of the strengthened substrate 102 may have a surface roughness that is greater than first surface 104 of the strengthened substrate.
• the strengthened substrates 102 described herein may be substantially transparent to certain wavelengths of electromagnetic radiation to facilitate the de-bonding of microelectronic components from at least one of the first surface 104 and the second surface 106 of the strengthened substrates.
• the strengthened substrates 102 have a transmittance of greater than or equal to 50% for wavelengths of light within the ultraviolet spectrum (i.e., for wavelengths of light from about 10 nm to about 400 nm).
• the strengthened substrates have a transmittance of greater than or equal to 50% or even greater than or equal to 60% for wavelengths of ultraviolet light greater than or equal to 300 nm and less than or equal to 355 nm.
• the transmittance may be greater than or equal to 70% or even greater than or equal to 80% for wavelengths of ultraviolet light greater than or equal to 300 nm and less than or equal to 355 nm.
• the strengthened substrates have a CTE of greater than or equal to Bx KE’IC 1 averaged over a temperature range from 20°C to 300°C or even greater than or equal to 9xlO 6 K _1 averaged over a temperature range from 20°C to 300°C.
• These CTE values reduce the CTE differential between the substrate and coatings and/or components adhered to the substrate during the microelectronics fabrication process, thereby minimizing distortion of the substrate during thermal cychng experienced during the microelectronics fabrication process.
• the phrase “strengthened substrate” means that, during or following formation of the substrate, the substrate is subjected to processing conditions to introduce compressive stress in the surface of the substrate thereby enhancing the resistance of the substrate to failure-inducing damage.
• the strengthened substrates described herein further include first and second compressive stress layers 108, 110 that extend from the first surface 104 and the second surface 106 of the strengthened substrate 102, respectively, towards a center of the strengthened substrate 102 to a depth of layer (DOL).
• DOL depth of layer
• the compressive stress in the first compressive stress layer 108 and the second compressive stress layer 110 is generally a maximum at the first surface 104 and the second surface 106 of the strengthened substrate 102 and decreases towards the center of the strengthened substrate 102 until the compressive stress is zero.
• the depth from the surface at which the compressive stress is zero generally delineates the DOL of the respective first and second compressive stress layers 108, 110.
• the first compressive stress layer 108 and the second compressive stress layer 110 are separated by a tensile region 112 disposed between the first compressive stress layer 108 and the second compressive stress layer 110.
• the compressive stress in the first compressive stress layer 108 and the second compressive stress layer 110 is generally a maximum at the first surface 104 and the second surface 106 of the strengthened substrate 102 and is referred to herein as the surface compressive stress.
• the surface compressive stress is generally greater than or equal to 200 MPa such that the strengthened substrate is able to withstand the mechanical insults of the microelectronic fabrication process with relatively low risk of failure.
• the surface compressive stress in the first compressive stress layer 108 and the second compressive stress layer 110 is greater than or equal to 200 MPa and less than or equal to 700 MPa. In some of these embodiments, the surface compressive stress in the first compressive stress layer 108 and the second compressive stress layer 1 10 is greater than or equal to 450 MPa and less than or equal to 650 MPa.
• the first compressive stress layer 108 and the second compressive stress layer 110 each extend to a DOL that is greater than or equal to 50 pm and less than or equal to 150 pm.
• a DOL of less than 50 pm may not contain the flaws resulting from mechanical insults experienced during the microelectronics fabrication process, thereby leading to failure of the strengthened substrate 102.
• the depth of layer is greater than or equal 60 pm and less than or equal to 100 pm.
• One consequence of the introduction of compressive stress in the strengthened substrate 102 is the complementary buildup of tensile stress in the tensile region 112.
• the amount of stored elastic energy (SEE) in both the first and second compressive stress layers 108, 110 and the tensile region 112 must be equal such that the net stress in strengthened substrate is zero ln most cases, the surface compressive stress at the first and second surfaces 104, 106 is relatively large, and the tensile region 112 has a smaller magnitude tensile stress. That is, the compressive stress in the first and second compressive stress layers 108, 110 is distributed over a relatively shallow depth, while the smaller tensile stress is distributed over a significant portion of a thickness T of the substrate.
• SEE stored elastic energy
• CT CS*DOL/(T -2*DOL)
• the SEE in the tensile region 112 generally dictates the fragmentation behavior of the strengthened substrate upon failure. That is, if the SEE is above a certain threshold value, the strengthened substrate 102 will separate into many small fragments when a flaw (such as a crack, for example) introduced into the strengthened substrate extends through the DOL of the first or second compressive stress layers 108, 110 and into the tensile region 112. As noted herein, it is undesirable for the strengthened substrate to separate into many small fragments because the small fragments foul the microelectronic fabrication equipment and are difficult to remove, causing process downtime, decreasing manufacturing efficiencies, and increasing manufacturing costs.
• a flaw such as a crack, for example
• the strengthened substrate 102 will separate into fewer (and larger) fragments when a flaw (such as a crack, for example) introduced into the strengthened substrate extends through the DOL of the first or second compressive stress layers 108, 110 and into the tensile region 112. These larger fragments can be more readily removed from the microelectronic fabrication equipment reducing process downtime and increasing manufacturing efficiencies.
• a flaw such as a crack, for example
• the SEE of the strengthened substrate 102 is less than or equal to 40 joules per square meter (kJ/m 2 ) such that the strengthened substrate separates into fewer (and larger) fragments when a flaw (such as a crack, for example) introduced into the strengthened substrate extends through the DOL of the first or second compressive stress layers 108, 110 and into the tensile region 112. ln some embodiments, the SEE of the strengthened substrate is less than or equal to 38.8 kJ/m 2 or even less than or equal to 38.0 kJ/m 2 .
• the SEE of the strengthened substrate is less than or equal to 37 kJ/m 2 or even less than or equal to 35.0 kJ/m 2 . ln some embodiments, the SEE of the strengthened substrate is less than or equal to 33 kJ/m 2 or even less than or equal to 30 kJ/m 2 .
• the compressive stress layers 108, 110 may be formed in the strengthened substrate 102 by several different processes or combinations thereof.
• the compressive stress layers 108, 110 may be formed in the strengthened substrate by thermal tempering, chemical tempering by ion exchange, and/or lamination of glasses or glass- ceramics having different moduli and/or coefficients of thermal expansion (CTE).
• CTE moduli and/or coefficients of thermal expansion
• the compressive stress layers 108, 110 are formed through chemical tempering by ion exchange.
• the substrate may be immersed in a molten salt bath comprising alkali metal ions to facilitate exchange of smaller alkali metal ions in the substrate with larger alkali metal ions in the molten salt bath.
• the ion exchange process includes placing the substrate in a molten salt bath comprising NaN0 3 and KN0 3 .
• the concentration of NaN0 3 in the molten salt bath may be from about 2 wt.% to about 10 wt.% or even from about 5 wt.% to about 7 wt.%.
• the concentration of KN0 3 in the molten salt bath may be from about 90 wt.% to about 98 wt.% or even from about 93 wt.% to about 95 wt.%.
• the molten salt bath may be maintained at a temperature from greater than or equal to 380°C and less than or equal to 460°C, or even from greater than or equal to 400°C and less than or equal to 450°C.
• the substrate is positioned in the molten salt bath for a time greater than or equal to 5 hours and less than or equal to 30 hours to achieve the desired stress characteristics. In embodiments, the substrate is positioned in the molten salt bath for a time greater than or equal to 6 hours and less than or equal to 15 hours to achieve the desired stress characteristics.
• the CS, central tension, and DOL of the strengthened substrate facilitate singulation of the strengthened substrate with relatively low forces.
• the strengthened substrates described herein may be singulated by a scribe-and-break technique using conventional hand tools.
• a score line may be formed in the surface of the strengthened substrate with a scribe force of less than or equal to 30 Newtons (N) using a conventional glass cutter, such as a Mitsuboshi glass cutter with a standard Penett® wheel.
• the score line is sufficiently deep that the strengthened substrate can be readily singulated along the score line by applying a bending moment on either side of the score line. Singulation under these conditions occurs without crack bifurcation and, thus, the substrate is cleanly separated along the score line.
• the retained strength of the strengthened substrate is a measure of the resistance of the substrate to failure under an applied load after being subjected to a mechanical insult, such as the introduction of a flaw.
• the retained strength provides an indication of the ability the substrate to withstand the rigors of the microelectronics fabrication process after being subject to a mechanical insult.
• FIGS. 4 and 5 a process for determining the retained strength of a substrate, such as a strengthened substrate, is schematically depicted.
• an indentation 202 (FIG. 5) is formed in the first surface 104 of the strengthened substrate 102 to simulate a mechanical insult, such as a scratch.
• the indentation 202 is formed with a pyramidal indenter 200 having a face angle f of 120°.
• the indenter 200 is pressed into the first surface 104 of the strengthened substrate with an indent load Fi, which, in the embodiments described herein, was varied from 1 kilogram-force to 4 kilogram-force to simulate damage of different severity.
• a bending stress is applied to the strengthened substrate in 4-point bending, as depicted in FIG. 5.
• the strengthened substrate 102 is placed on a pair of support pins 204, 206 such that the support pins contact the second surface 106 of the strengthened substrate 102.
• the support pins 204,206 are spaced apart from one another by a distance di.
• a pair of load pins 208, 210 is brought into contact with the first surface 104 of the strengthened substrate 102 on either side of the indentation 202.
• the load pins 208, 210 are located within the distance di of the support pins 204, 206 but on an opposite side of the strengthened substrate 102 from the support pins 204, 206.
• the load pins 208, 210 are spaced apart from one another by a distance d 2 which is less than the distance di.
• a 4-point bend load F 4B is applied to the load pins 208, 210 and increased at a set rate until the strengthened substrate fails (i.e., fractures) from the indentation 202.
• the 4-point bend load at failure is the retained strength of the substrate for the specific indent load Fi that formed the indentation 202.
• the strengthened substrate has a retained strength of greater than or equal to 300 MPa after indentation with an indent load of 1 kilogram- force (using the method described herein). In embodiments, the strengthened substrate has a retained strength of greater than or equal to 310 MPa or even greater than or equal to 320 MPa after indentation with an indent load of 1 kilogram-force. In some embodiments, the strengthened substrate has a retained strength of greater than or equal to 330 MPa or even greater than or equal to 340 MPa after indentation with an indent load of 1 kilogram-force.
• the strengthened substrate has a retained strength of greater than or equal to 100 MPa after indentation with an indent load of 2 kilogram- force (using the method described herein). In embodiments, the strengthened substrate has a retained strength of greater than or equal to 110 MPa or even greater than or equal to 115 MPa after indentation with an indent load of 2 kilogram-force. In some embodiments, the strengthened substrate has a retained strength of greater than or equal to 120 MPa or even greater than or equal to 130 MPa after indentation with an indent load of 2 kilogram-force. In some embodiments, the strengthened substrate has a retained strength of greater than or equal to 140 MPa or even greater than or equal to 150 MPa after indentation with an indent load of 2 kilogram-force.
• the strengthened substrate has a retained strength of greater than or equal to 70 MPa after indentation with an indent load of 3 kilogram-force (using the method described herein). In embodiments, the strengthened substrate has a retained strength of greater than or equal to 80 MPa or even greater than or equal to 90 MPa after indentation with an indent load of 3 kilogram-force. In some embodiments, the strengthened substrate has a retained strength of greater than or equal to 100 MPa or even greater than or equal to 110 MPa after indentation with an indent load of 3 kilogram- force.
• the strengthened substrate has a retained strength of greater than or equal to 45 MPa after indentation with an indent load of 4 kilogram-force (using the method described herein). In embodiments, the strengthened substrate has a retained strength of greater than or equal to 50 MPa or even greater than or equal to 55 MPa after indentation with an indent load of 4 kilogram-force. In some embodiments, the strengthened substrate has a retained strength of greater than or equal to 60 MPa or even greater than or equal to 65 MPa after indentation with an indent load of 4 kilogram-force. In some embodiments, the strengthened substrate has a retained strength of greater than or equal to 70 MPa or even greater than or equal to 80 MPa after indentation with an indent load of 4 kilogram- force.
• the strengthened substrate has sufficient retained strength to avoid failure during the microelectronics fabrication process due to damage (such as mechanical insults, for example). However, if the strengthened substrate does fail, it is desirable that the strengthened substrate separate into as few primary fragments as possible and that the primary fragments are as large as possible to prevent fouling of the microelectronics fabrication equipment and facilitate easy removal of the fragments from the equipment.
• the term“primary fragments,” as used herein, refers to the largest fragments created upon failure of the substrate, exclusive of smaller fragments and particles created at or near the origin of the failure or crack surfaces. In the embodiments described herein, the primary fragments have single-side surface areas that are greater than or equal to 1/8 of the single-side surface area of the substrate prior to fragmentation.
• a“flat fragmentation factor” is used to describe the fragmentation behavior of the substrates.
• the flat fragmentation factor is the number of primary fragments that the strengthened substrate separates into upon failure (i.e., the number of fragments having a single-side surface area that is greater than or equal to 1/8 of the single-side surface area of the strengthened substrate prior to fragmentation).
• the strengthened substrates described herein have a flat fragmentation factor that is greater than 1 and less than or equal to 5.
• the strengthened substrates have a flat fragmentation factor that is less than or equal to 4 or even less than or equal to 3.
• the strengthened substrates have a flat fragmentation factor of 2.
• FIG. 6 schematically depicts a process for determining the flat fragmentation factor of a glass or glass-ceramic substrate, such as a strengthened substrate 102.
• This process includes contacting the first surface 104 of the strengthened substrate 102 with a fragmentation indenter (such as a sharp carbide tip or other, similar indenter tool) with a flat fragmentation force F FF at the geometric center of the substrate and increasing the flat fragmentation force until the substrate fails. Thereafter, the number of primary fragments (as determined by single-side surface area of the fragments) is counted and the flat fragment factor is determined.
• a fragmentation indenter such as a sharp carbide tip or other, similar indenter tool
• the strengthened substrates 102 are sufficiently rigid such that they resist flexing under the loads applied to the strengthened substrates 102 during the microelectronics fabrication process.
• the strengthened substrates 102 have a flexural rigidity D that is greater than or equal to 10 GPa-mm 3 where D is calculated according to the equation: where E is the elastic modulus of the glass or glass-ceramic, t is the average thickness of the strengthened substrate and v is Poisson’s ratio of the strengthened substrate. If the flexural rigidity is less than 10 GPa-mm 3 , the strengthened substrate 102 may flex or bend during the microelectronic fabrication process, potentially causing the misalignment of components.
• the flexural rigidity D of the strengthened substrate greater than or equal to 15 GPa-mm 3 or even greater than or equal to 20 GPa-mm 3 . In some embodiments, the flexural rigidity D of the strengthened substrate greater than or equal to 25 GPa-mm 3 or even greater than or equal to 30 GPa-mm 3 . In some embodiments, the flexural rigidity D of the strengthened substrate greater than or equal to 35 GPa-mm 3 or even greater than or equal to 40 GPa-mm 3 . In some embodiments, the flexural rigidity D of the strengthened substrate greater than or equal to 45 GPa-mm 3 or even greater than or equal to 50 GPa-mm 3 .
• the strengthened substrates 102 of the carriers 100 have an as-formed warp of greater than or equal to 0 pm and less than or equal to 500 pm.
• the phrase“as-formed warp,” as used herein, refers to the amount of distortion in the strengthened substrate after strengthening but prior to deposition of any other material on the strengthened substrate 102.
• the strengthened substrates 102 have an as-formed warp of greater than or equal to 0 pm and less than or equal to 400 pm or even greater than or equal to 0 pm and less than or equal to 300 pm.
• the strengthened substrates 102 have an as- formed warp of greater than or equal to 0 pm and less than or equal to 200 pm or even greater than or equal to 0 pm and less than or equal to 150 pm. In some embodiments, the strengthened substrates 102 have an as-formed warp of greater than or equal to 0 pm and less than or equal to 100 pm or even greater than or equal to 0 pm and less than or equal to 50 pm. In the embodiments described herein the as-formed warp is measured according to the method described in U.S. Patent No. 9,031,813 entitled“Methods and apparatus for estimating gravity-free shapes.”
• the strengthened substrates 102 of the carriers 100 have an in-process warp of less than or equal to 4,000 pm and greater than or equal to -9,000 pm.
• in-process warp refers to the amount of distortion in the strengthened substrate as layers of various materials, such as layers of dielectric materials, layers of metallic materials (e.g., copper, silver, etc.), epoxy molding materials, and the like are deposited on the strengthened substrate 102 during the microelectronics fabrication process.
• the in-process warp may be caused by, for example, the difference in the coefficient of thermal expansion of the strengthened substrate 102 and the various layers deposited on the strengthened substrate 102 as well as the thickness of the strengthened substrate 102 and the thickness of the various layers deposited on the strengthened substrate 102.
• the in-process warp may also be caused by the cure shrinkage of polymer coating layers.
• the strengthened substrates have an in-process warp of less than or equal to 3,500 pm and greater than or equal to -8,000 pm. In some embodiments, the strengthened substrates have an in-process warp of less than or equal to 3,000 pm and greater than or equal to -7,000 pm.
• the strengthened substrates have an in-process warp of less than or equal to 2,000 pm and greater than or equal to -5,000 pm. In some embodiments, the strengthened substrates have an in- process warp of less than or equal to 1,500 pm and greater than or equal to -4,000 pm In the embodiments described herein the in-process warp is measured according to the method described in U.S. Patent No. 9,031,813 entitled“Methods and apparatus for estimating gravity-free shapes.” Examples
• the effect of ion exchange process conditions (time, temperature, and bath composition) and sample thickness on the stored elastic energy (SEE) was empirically assessed for samples having a thickness of 2.0 mm and 1.8 mm.
• the samples were formed from an alkali aluminosilicate glass composition comprising 69.49 mol.% Si0 2 , 8.45 mol.% Al 2 0 3 , 14.01 mol.% Na 2 0, 1.16 mol.% K 2 0, 0.185 mol.% Sn0 2 , 0.507 mol.% CaO, 6.2 mol.% MgO, 0.01 mol.% Zr0 2 , and 0.008 mol.% Fe 2 0 3 .
• the samples were ion exchanged in a salt bath comprising KN0 3 and NaN0 3 with the time and temperature conditions listed in Table 1 A.
• the fragmentation behavior of un-strengthened substrates and substrates strengthened by ion exchange were compared.
• the substrates were formed from an alkali aluminosilicate glass comprising 69.49 mol.% Si0 2 , 8.45 mol.% Al 2 0 3 , 14.01 mol.% Na 2 0, 1.16 mol.% K 2 0, 0.185 mol.% Sn0 2 , 0.507 mol.% CaO, 6.2 mol.% MgO, 0.01 mol.% Zr0 2 , and 0.008 mol.% Fe 2 0 3 .
• the substrates were square in shape with a length of 500 mm, a width of 500 mm (single-side surface area of 250,000 mm 2 ) and a thickness of 1.8 mm.
• One set of substrates was ion exchange strengthened in a molten salt bath comprising 95 wt.% KN0 3 and 5 wt.% NaN0 3 for 10 hours at a temperature of 450°C.
• the other set of substrates was un-strengthened.
• a flat fragmentation test was performed as described herein with respect to FIG. 6. Specifically, the glass substrates were positioned on a table and an indenter was pressed into the surface of the glass substrate at the geometric center of the substrate under an increasing flat fragmentation force F ff .
• the max fragmentation force F FF and condition (i.e., failed/survived) of the substrates are provided below in Table 2. Photographs of a failed strengthened substrate (FIG. 7, rendered as a line drawing) and a failed un-strengthened substrate (FIG. 8, rendered as a line drawing) were taken. Table 2: Flat Fragmentation
• the strengthened substrate fragmented into two primary fragments and thus had a flat fragmentation factor of 2.
• the un-strengthened substrate F1G. 8 fragmented into four primary fragments and thus had a flat fragmentation factor of 4.
• the empirical results of these tests indicate that the strengthened substrates have a better (i.e., lower) flat fragmentation factor than the un-strengthened substrates and, as such are more suitable for use in a microelectronics fabrication processes where fewer fragments are desired to prevent fouling of the fabrication equipment.
• the max fragmentation force F FF at failure for strengthened glass samples was generally less than the max fragmentation force F FF at failure for un-strengthened samples lt is believed that this is due to the introduction of central tension through ion exchange. That is, strengthening of the glass results in the introduction of compressive stress that extends to a depth of layer DOL as well as a tensile region.
• the glass within the depth of layer is generally resistant to failure from flaws due to the compressive stress in the layer. However, once a flaw penetrates into the tensile region, the tensile stresses in the region will aid in propagating the flaw through the glass, thereby resulting in failure of the glass (i.e., fragmentation).
• the un-strengthened glass substrates are stress-free (or have much lower compressive/tensile stresses relative the strengthened glass substrates). Absent the tensile region, the indenter must penetrate deeper into the glass substrate (compared to the strengthened glass substrate) to initiate failure and fragmentation. This deeper penetration of the indenter into the glass surface requires greater force, hence the greater max fragmentation force F FF for the un strengthened glass substrates.
• the strengthened substrates generally have greater retained strength than un-strengthened substrates (see Example 3). This means that the strengthened substrates are better able to withstand routine mechanical insults (e.g., scratches, nicks, etc.) during the microelectronics fabrication process without failure due to the compressive stress at the surface of the substrate.
• routine mechanical insults e.g., scratches, nicks, etc.
• the tension in the tensile region of the strengthened substrates will cause the strengthened substrates to preferentially fail and fragment relatively early in the microelectronics fabrication process where stresses are lower and the fragments can be easily removed from the fabrication equipment. Failure at this stage of the fabrication process also mitigates the loss of product layered on the strengthened substrate and reduces equipment downtime.
• Two sets of alkali aluminosilicate glass samples were empirically tested to compare the effect of ion exchange on the retained strength of the samples.
• the glass samples had a length of 40 mm, a width of 66 mm, and a thickness of 1.8 mm.
• a first set of samples was left in as- received condition (i.e., not ion exchange strengthened).
• a second set of samples was ion exchange strengthened in a mixed salt bath comprising 5 wt.% NaNCF and 95 wt.% KNO3 for 10 hours at a temperature of 450°C.
• the ion exchange process resulted in a DOL of 73 pm and a surface compressive stress of 540 MPa. Samples of each set were indented as shown in FIG.
• the retained strength of the ion exchange strengthened samples and the un-strengthened samples generally decreased with increasing indent loads.
• the retained strength of the ion exchange strengthened samples was approximately twice that of the un-strengthened samples for all indent loading conditions. This data indicates that the ion exchange strengthened samples are better able to withstand the mechanical insults of the microelectronics fabrication processes without failure compared to the un-strengthened substrate.
• the in-process warp of strengthened substrates with thicknesses of 1.0 mm, 1.5 mm, 2.0 mm, and 3 mm employed in carriers were mathematically modeled.
• the modeled strengthened substrate was formed from an alkali aluminosilicate glass substrate comprising 66.16% Si0 2 , 10.29% Al 2 0 3 , 14.0% Na 2 0, 2.45% K 2 0, 0.6 mol.% B 2 0 3 , 0.21% Sn0 2 , 0.58 mol.% CaO, 5.7 mol.% MgO, 0.0105 mol.% Zr0 2 , and 0.0081 mol.% Fe 2 0 3 .
• the glass substrate was modeled with an elastic modulus of 73.3 GPa, a CTE of 9.4xlO 6 K _1 and a poisson ratio of 0.21.
• the strengthened substrate was modeled with a length of 500 mm and a width of 500 mm.
• the in-process warp of the strengthened substrates was modeled with an applied metal/dielectric coating comprising 8 alternating layers of copper (4 layers, each with a 10 pm thickness) and dielectric material (4 layers, each with a 30 pm thickness).
• the copper was modeled with an elastic modulus of 102.1 GPa, a CTE of 16.5x 1 OGC 1 , and a poisson ratio of 0.34.
• the dielectric material was modeled with an elastic modulus of 3.4 GPa below the glass transition temperature of the material (330°C), an elastic modulus of 0.0034 GPa above the glass transition temperature of the material, a CTE of 35xlO 6 K _1 below the glass transition temperature, a CTE of 50xl0 6 K _1 above the glass transition temperature, and a poisson ratio of 0.35.
• the stress-free temperature of the dielectric material was modeled at its glass transition temperature (330°C) since the curing temperature (375°C) is higher than its glass transition temperature.
• a first epoxy molding compound EMC A was modeled with an elastic modulus of 22 GPa below the glass transition temperature of the material (l65°C), an elastic modulus of 0.022 GPa above the glass transition temperature of the material, a CTE of 7.5x10 6 K _1 below the glass transition temperature, a CTE of 33xl0 6 K _1 above the glass transition temperature, and a poisson ratio of 0.35.
• a second epoxy molding compound (EMC B) was modeled with an elastic modulus of 27 GPa below the glass transition temperature of the material (l75°C), an elastic modulus of 0.027 GPa above the glass transition temperature of the material, a CTE of 7.2xlO 6 K 1 below the glass transition temperature, a CTE of 30xl0 6 K _1 above the glass transition temperature, and a poisson ratio of 0.35.
• the stress-free temperature of EMC A and EMC B were modeled at their post mold curing temperatures (l25°C) since the post mold curing temperatures are lower than their glass transition temperatures.
• FIG. 10 depicts the warpage of a modeled strengthened substrate with only the mctal/diclcctric coating (identified as “No EMC”), the warpage of a modeled strengthened substrate with the metaFdielectric coating and the first epoxy molding compound (identified as“EMC A”), and the warpage of a modeled strengthened substrate with the metaFdielectric coating and the second epoxy molding compound (identified as“EMC B”).
• the “No EMC” model had a warpage of less than zero, specifically from about -9,000 pm to about -2000 pm with the warpage approaching zero with increasing thickness of the strengthened substrate.
• the negative warpage leads to a concave shape in the strengthened substrate. While not wishing to be bound by theory, it is believed that the negative warpage in the“No EMC” model is due to tensile thermal stress within the dielectric material.
• the“EMC B” model had a warpage of greater than zero, specifically from about 3,000 pm to approximately 0 pm with the warpage decreasing with increasing thickness of the strengthened substrate.
• the positive warpage leads to a convex shape in the strengthened substrate. While not wishing to be bound by theory, it is believed that the positive warpage in the “EMC B” model is due to compressive thermal stress from the second epoxy molding compound.
• The“EMC A” model had warpage greater than zero transitioning to warpage of less than 0 with increasing glass thickness. Specifically, the“EMC A” model had a warpage of approximately 1,000 pm at a glass thickness of 1 mm. This warpage decreased to approximately 0 pm at a glass thickness of 0 mm and further decreased to less than 0 pm for glass thicknesses of greater than 1.5 mm. While not wishing to be bound by theory, it is believed that the warpage for glass thicknesses of 1.5 mm or less is due to compressive thermal stresses in the first epoxy molding compound. However, as the thickness of the glass increases, the effects of the compressive thermal stresses in the first epoxy molding compound becomes negligible due to the increased rigidity of the glass. With the diminished effect of the compressive thermal stresses, the tensile thermal stresses in the dielectric material cause negative warpage. This negative warpage approached 0 pm with increasing glass thickness.

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