WO2018111998A1

WO2018111998A1 - Methods for laser processing transparent workpieces by forming score lines

Info

Publication number: WO2018111998A1
Application number: PCT/US2017/066013
Authority: WO
Inventors: Robert Stephen Wagner; Kristopher Allen WIELAND
Original assignee: Corning Incorporated
Priority date: 2016-12-13
Filing date: 2017-12-13
Publication date: 2018-06-21
Also published as: TW201831414A

Abstract

A method for laser processing a transparent workpiece includes directing a pulsed laser beam into the transparent workpiece at an impingement location on a first surface of the transparent workpiece such that the pulsed laser beam ablates a portion of material of the transparent workpiece at the impingement location. The laser beam has a pulse energy of from about 5 µJ to about 50 µJ. The method also includes translating the pulsed laser beam relative to the first surface of the transparent workpiece along a desired separation path, thereby ablating additional material of the transparent workpiece to form a score line along the desired separation path, the score line having a score depth of from about 10 µm to about 60 µm.

Description

METHODS FOR LASER PROCESSING TRANSPARENT

WORKPIECES BY FORMING SCORE LINES

BACKGROUND

[0001] This application claims the benefit of priority under 35 U.S.C. § 119 of U. S.

Provisional Application Serial No. 62/433,337 filed on December 13, 2016, the content of which is relied upon and incorporated herein by reference in its entirety.

Field

[0002] The present specification generally relates to apparatuses and methods for laser processing transparent workpieces, and more particularly, to separating transparent workpieces by laser forming a score line in the transparent workpiece and separating the transparent workpiece along the score line.

Technical Background

[0003] The area of laser processing of materials encompasses a wide variety of applications that involve cutting, drilling, milling, welding, melting, etc. of different types of materials. Among these processes, one that is of particular interest is cutting or separating different types of transparent substrates in a process that may be utilized in the production of materials such as glass, sapphire, or fused silica for thin film transistors (TFT) or display materials for electronic devices.

[0004] From process development and cost perspectives there are many opportunities for improvement in cutting and separating glass substrates. It is of great interest to have a faster, cleaner, cheaper, more repeatable, and more reliable method of separating glass substrates than what is currently practiced in the market. Accordingly, a need exists for altemative improved methods for separating glass substrates.

SUMMARY

[0005] According to one embodiment, a method for laser processing a transparent workpiece includes directing a pulsed laser beam into the transparent workpiece at an impingement location on a first surface of the transparent workpiece such that the pulsed laser beam ablates a portion of material of the transparent workpiece at the impingement location. The laser beam has a pulse energy of from about 5 μ] to about 50 μΐ The method also includes translating the pulsed laser beam relative to the first surface of the transparent workpiece along a desired separation path, thereby ablating additional material of the transparent workpiece to form a score line along the desired separation path, the score line having a score depth of from about 10 μιτι to about 60 μπι

[0006] In another embodiment, a separated transparent workpiece includes a first surface opposite a second surface and a separated edge extending between the first surface and the second surface. The separated edge includes a scored surface region extending from the first surface to a score depth line, a cracked surface region extending from the score depth line to the second surface, and one or more hackle features extending from the score depth line toward the second surface along the cracked surface region. The maximum hackle depth of the one or more hackle features is 10 μιτι or less. Further, the separated edge includes an edge deviation distance of 30 μιτι or less. The edge deviation distance is a distance between a first boundary plane of the cracked surface region and a second boundary plane of the cracked surface region.

[0007] In yet another embodiment a method for laser processing a transparent workpiece includes directing a pulsed laser beam into the transparent workpiece at an impingement location on a first surface of the transparent workpiece such that the pulsed laser beam ablates a portion of material of the transparent workpiece at the impingement location. The laser beam has a pulse energy of from about 5 μ] to about 50 μΐ The method also includes translating the pulsed laser beam relative to the first surface of the transparent workpiece along a desired separation path, thereby ablating additional material of the transparent workpiece to form a score line along the desired separation path, and applying stress to the score line of the transparent workpiece to separate at least one separated transparent workpiece from the transparent workpiece along the score line. The at least one separated transparent workpiece includes an unpolished separated edge that extends between a first surface and a second surface of the at least one separated transparent workpiece. The unpolished separated edge further includes a scored surface region extending from the first surface of the at least one separated transparent workpiece to a score depth line, a cracked surface region extending from the score depth line to the second surface of the at least one separated transparent workpiece, and one or more hackle features extending from the score depth line toward the second surface along the cracked surface region. The maximum hackle depth of the one or more hackle features is 10 μηι or less. Further, the unpolished separated edge includes an edge deviation distance of 30 μηι or less. The edge deviation distance is a distance between a first boundary plane of the cracked surface region and a second boundary plane of the cracked surface region.

[0008] Additional features and advantages of the processes and systems described herein will be set forth in the detailed description which follows, and in part will be readily apparent to those skilled in the art from that description or recognized by practicing the embodiments described herein, including the detailed description which follows, the claims, as well as the appended drawings.

[0009] It is to be understood that both the foregoing general description and the following detailed description describe various embodiments and are intended to provide an overview or framework for understanding the nature and character of the claimed subject matter. The accompanying drawings are included to provide a further understanding of the various embodiments, and are incorporated into and constitute a part of this specification. The drawings illustrate the various embodiments described herein, and together with the description serve to explain the principles and operations of the claimed subject matter.

BRIEF DESCRIPTION OF THE DRAWINGS

[0010] The embodiments set forth in the drawings are illustrative and exemplary in nature and not intended to limit the subject matter defined by the claims. The following detailed description of the illustrative embodiments can be understood when read in conjunction with the following drawings, where like structure is indicated with like reference numerals and in which:

[0011] FIG. 1A schematically depicts schematically depicts a perspective view of a laser and a transparent workpiece, according to one or more embodiments shown and described herein;

[0012] FIG. IB schematically depicts a laser beam, according to one or more embodiments shown and described herein; [0013] FIG. 2 schematically depicts a top view of the laser and the transparent workpiece of FIG. 1 A, according to one or more embodiments shown and described herein;

[0014] FIG. 3 schematically depicts a section view along line A-A of FIG. 2, according to one or more embodiments shown and described herein;

[0015] FIG. 4 schematically depicts a section view along line B-B of FIG. 2, according to one or more embodiments shown and described herein;

[0016] FIG. 5 schematically depicts a partial front view of an edge surface of a separated edge of a separated transparent workpiece, according to one or more embodiments shown and described herein;

[0017] FIG. 6 schematically depicts a partial side view of the edge surface of the separated edge of the separated transparent workpiece of FIG. 5, according to one or more embodiments shown and described herein;

[0018] FIG. 7 schematically depicts a partial perspective view of the separated transparent workpiece of FIGS. 5 and 6, according to one or more embodiments shown and described herein; and

[0019] FIG. 8 graphically depicts a relationship between a score depth of a score line formed in first and second transparent workpiece samples and a maximum hackle depth of separated edges of separated transparent workpieces formed after separation of first and second transparent workpiece samples, according to one or more embodiments shown and described herein.

DETAILED DESCRIPTION

[0020] Reference will now be made in detail to embodiments of methods of laser processing a transparent workpiece and subsequently separating the transparent workpiece into a plurality of separated transparent workpieces using a laser, examples of which are illustrated in the accompanying drawings. Whenever possible, the same reference numerals will be used throughout the drawings to refer to the same or like parts. One embodiment of the method of separating the transparent workpiece using the laser is depicted in FIG. 1 A. A laser beam produced by the laser may be directed into a surface of a transparent workpiece and translated relative to the transparent workpiece to ablate the transparent workpiece and create a score line extending into the surface of the transparent workpiece. After forming the score line, stress may be applied to separate the transparent workpiece into two or more separated transparent workpieces each having a separated edge. The depth of the score line prior to separating the transparent workpiece is correlated with the quality of the resultant separated edge. For example, forming a score line with a depth of from about 10 microns (μιη) to about 60 μηι and subsequently separating the transparent workpiece forms two separated transparent workpieces each comprising a separated edge having minimal hackle depth and a minimal edge deviation distance, such that the separated edge is coplanar or nearly coplanar with a crack propagation plane and orthogonal to the surface of the transparent workpiece. Minimizing the hackle depth and the edge deviation distance provide a strong separated edge that may be finely positioned in an end application, for example, when the transparent workpiece is used as a TFT or a display glass for an electronic device. Methods of laser processing transparent workpieces to form separated transparent workpieces having minimal hackle depth and a minimal edge deviation distance will be described in more detail herein with specific reference to the appended drawings.

[0021] As used herein, "laser processing" comprises directing a laser beam, such as a pulsed laser beam into a transparent workpiece and translating the laser beam relative to the transparent workpiece along a desired separation path. Examples of laser processing include using a pulsed laser beam to form a score line extending into a surface of the transparent workpiece, for example, by ablating a surface of the transparent workpiece and/or using an infrared laser beam to heat the transparent workpiece, for example, along the score line. Laser processing may separate the transparent workpiece into a plurality of separated transparent workpieces along one or more desired lines of separation. However, in some embodiments, additional, non-laser steps may be utilized to separate the transparent workpiece along the one or more desired lines of separation.

[0022] The phrase "score line," as used herein, denotes a vent (e.g., a line, a curve, etc.) formed (e.g., ablated) into a surface of the transparent workpiece along a desired separation path along which the transparent workpiece may be separated into multiple separated transparent workpieces upon exposure to the appropriate processing conditions. The score line generally consists of a continuous vent that may comprise a series of overlapping ablated regions introduced into the transparent workpiece using various techniques described herein, for example, formed by ablating the transparent workpiece with a pulsed laser beam. Further, the transparent workpiece may be separated along the score line, for example, using an infrared laser or other laser configured to heat the area of the transparent workpiece along or near the score line by bending, or otherwise mechanically stressing the transparent workpiece.

[0023] The phrase "transparent workpiece," as used herein, means a workpiece formed from glass or glass-ceramic which is transparent, where the term "transparent," as used herein, means that the material has an optical absorption of less than about 20% per mm of material depth, such as less than about 10% per mm of material depth for the specified pulsed laser wavelength, or such as less than about 1% per mm of material depth for the specified pulsed laser wavelength. The transparent workpiece may have a depth (e.g., thickness) of from about 50 μιτι to about 10 mm (such as from about 100 μιτι to about 5 mm, or from about 500 μιτι to about 3 mm, or from about 300 μιτι to about 700 μπι). For example, the transparent workpiece may have a depth of about 500 μιτι, 700 μιτι, 1 mm, or the like. Transparent workpieces may comprise glass workpieces formed from glass compositions, such as borosilicate glass, soda-lime glass, aluminosilicate glass, alkali aluminosilicate glass, alkaline earth aluminosilicate glass, alkaline earth boro-aluminosilicate glass, fused silica, or crystalline materials such as sapphire, silicon, gallium arsenide, or combinations thereof. As non-limiting examples, the transparent workpiece may comprise Corning Gorilla® Glass available from Corning Incorporated of Corning, NY (e.g., code 2318, code 2319, and code 2320). Other example transparent workpieces may comprise EAGLE XG^®, CONTEGO, and CORNING LOTUS™ available from Corning Incorporated of Corning, NY.

[0024] In some embodiments the transparent workpiece may be strengthened via thermal tempering or chemical strengthening (e.g., via ion exchange) before or after laser processing the transparent workpiece. In an ion exchange process, ions in a surface layer of the transparent workpiece are replaced by larger ions having the same valence or oxidation state, for example, by partially or fully submerging the transparent workpiece in an ion exchange bath. Replacing smaller ions with larger ions causes a layer of compressive stress to extend from one or more surfaces of the transparent workpiece to a certain depth within the transparent workpiece, referred to as the depth of layer. The compressive stresses are balanced by a layer of tensile stresses (referred to as central tension) such that the net stress in the glass sheet is zero. The formation of compressive stresses at the surface of the glass sheet makes the glass strong and resistant to mechanical damage and, as such, mitigates catastrophic failure of the glass sheet for flaws which do not extend through the depth of layer. In some embodiments, smaller sodium ions in the surface layer of the transparent workpiece are exchanged with larger potassium ions. In some embodiments, the ions in the surface layer and the larger ions are monovalent alkali metal cations, such as Li+ (when present in the glass), Na+, K+, Rb+, and Cs+. Alternatively, monovalent cations in the surface layer may be replaced with monovalent cations other than alkali metal cations, such as Ag+, T1+, Cu+, or the like. Moreover, in some embodiments the transparent workpiece may be thermally annealed, reducing the residual stress in the transparent workpiece.

[0025] Referring now to FIG. 1A, a transparent workpiece 90 positioned on a translation table 80 is schematically depicted. The transparent workpiece 90 may be substantially in contact with the translation table 80. However, due to variations in the transparent workpiece 90, portions of the transparent workpiece 90 may be spaced apart from the translation table 80. A laser 100 is positioned above the translation table 80 and outputs a pulsed laser beam 102 that may be directed into the transparent workpiece 90. The pulsed laser beam 102 is transverse to a first surface 96 of the transparent workpiece 90 and moves relative to the transparent workpiece 90 in a first direction 82 and/or a second direction 84 to create one or more score lines 92 that extend from the first surface 96 of the transparent workpiece 90 into the bulk of the transparent workpiece 90. Although the pulsed laser beam 102 is illustrated as being orthogonal with respect to the first surface 96 of the transparent workpiece 90, embodiments are not limited thereto and in other embodiments, the pulsed laser beam 102 may be non-orthogonal with respect to the first surface 96 of the transparent workpiece 90. Further, the transparent workpiece 90 may be securely maintained in position on the translation table 80 by the use of mechanical or vacuum chucking. Vacuum chucking may be achieved by a series of vacuum holes spaced some distance apart on a vacuum platen. Mechanical chucking may be achieved by coupling the transparent workpiece 90 to the translation table 80 using a graphite chuck and a combination of alignment pins and adhesive tape.

[0026] In operation, a portion of the score line 92 may be formed by directing the pulsed laser beam 102 into the transparent workpiece 90 at an impingement location 97 on the first surface 96 along a desired separation path 93. The desired separation path 93 is the desired location of the score line 92 prior to formation of the score line 92 and is co-located with the score line 92 upon formation of the score line 92. Further, the full score line 92 may be formed by translating the pulsed laser beam 102 and the transparent workpiece 90 relative to each other along the desired separation path 93. For example, the pulsed laser beam 102 and the transparent workpiece 90 may be translated relative to each other for a single pass along the desired separation path 93 or multiple passes along the desired separation path 93 , for example, from between one to four passes along the desired separation path 93.

[0027] In some embodiments, the laser 100 may be coupled to a gantry (not shown) that translates the laser 100 in the first direction 82 and the second direction 84. In other embodiments, the laser 100 may be stationary and the translation table 80 supporting the transparent workpiece 90 moves in the first direction 82 and the second direction 84. In yet other embodiments, both the laser 100 and the translation table 80 are translatable relative to each other. Relative translation motion between the transparent workpiece 90 and the laser 100 may be from about 10 mm/s to about 200 mm/s, for example 25 mm/s, 50 mm/s, 75 mm/s, 100 mm/s, 125 mm/s, 150 mm/s, 175 mm/s, or the like. Moreover, while the score line 92 illustrated in FIG. 1 A is linear, the score line 92 may also be nonlinear (i.e., having a curvature along the first surface 96). Curved score lines 92 may be produced, for example, by translating either the transparent workpiece 90 or the pulsed laser beam 102 with respect to the other in two dimensions instead of one dimension (e.g., in both the first direction 82 and the second direction 84). While FIG. 1A depicts the transparent workpiece 90 being separated into two rectangular transparent workpieces, it should be understood that any configuration/shape of the separated transparent workpieces of the transparent workpieces 90 may be produced according to the methods disclosed herein based on the required end-user application. For example, the transparent workpiece 90 may be separated into individual glass articles having arbitrary shapes (e.g., curved edges).

[0028] Referring now to FIG. IB, the pulsed laser beam 102 is schematically depicted in greater detail. In some embodiments, the pulsed laser beam 102 is generated by the laser 100 as described above, and then focused by focusing optics, such as a focusing lens 101. It should be understood that the focusing optics may comprise additional lenses or other optical components to focus and condition the pulsed laser beam 102. The pulsed laser beam 102 is focused such that it has a focal area 104 that is determined by the depth of focus of the focused pulsed laser beam 102. The focusing lens 101 may be configured to focus the pulsed laser beam 102 to form a small beam waist BW, which is a portion of the pulsed laser beam 102 having a reduced diameter d. One example focusing lens 101 comprises a focal length of about 100 mm. The beam waist diameter d is smaller than the unfocused portion diameter D. As a non-limiting example, the unfocused portion diameter D may be about 1-10 mm, for example, 3 mm, 5 mm, 7 mm, or the like. As a non-limiting example, diameter d may be about 5-25 μιτι, for example, 8 μιτι, 10 μιτι, 15 μιτι, 20 μιτι, or the like. The beam waist BW has a center C, which is the region of the pulsed laser beam 102 having the smallest diameter d. As described below, the pulsed laser beam 102 may be focused such that the center C of the beam waist BW is located at or near (e.g., above or below) the first surface 96 or the second surface 98 of the transparent workpiece 90. Further, in some embodiments, the beam waist BW may be positioned within the bulk of the transparent workpiece 90 proximate the first surface 96 or the second surface 98 of the transparent workpiece 90. As a non-limiting example, the beam waist BW may be positioned within the transparent workpiece 90 at a distance of about 100 μιτι from the first surface 96.

[0029] The laser 100 is operable to emit the pulsed laser beam 102 having a wavelength suitable for imparting thermal energy to a portion of the transparent workpiece 90. Suitable lasers 100 include a diode-pumped q-switched solid-state Nd³⁺: YAG laser, Nd³⁺: YVO4 laser, or the like. In operation, the laser 100 may output a pulsed laser beam 102 with a wavelength of from about 200 nm to about 1200 nm, for example, from about 200 nm to about 600 nm. In some embodiments, the laser 100 may output a pulsed laser beam 102 comprising a wavelength of for example, 1064 nm, 1030 nm, 532 nm, 530 nm, 355 nm, 343 nm, or 266 nm, or 215 nm. In some embodiments, the laser 100 may output a pulsed laser beam 102 having a wavelength in the visible light range (i.e., from about 380 nanometers to about 619 nanometers), such as, from about 380 to about 570 nanometers, for example at a wavelength of about 532 nanometers.

[0030] In operation, the pulse duration of the laser 100 may be in the range from about 1 nanosecond to about 50 nanoseconds, for example, from about 15 nanoseconds to about 22 nanoseconds. In some embodiments, a pulse duration of the individual pulses of the pulsed laser beam 102 is in a range of from about 1 picosecond to about 100 picoseconds, such as from about 5 picoseconds to about 20 picoseconds, for example, about 10 picoseconds, and the repetition rate of the individual pulses may be in a range from about 1 kHz to 4 MHz, such as in a range from about 10 kHz to about 3 MHz, from about 10 kHz to about 650 kHz, or from about 10 kHz to about 250 kHz. In addition to a single pulse operation at the aforementioned individual pulse repetition rates, the pulses may be produced in bursts of two pulses or more (such as, for example, 3 pulses, 4 pulses, 5 pulses, 10 pulses, 15 pulses, 20 pulses, or more per pulse burst, such as from 1 to 30 pulses per pulse burst, or from 5 to 20 pulses per pulse burst). The pulses within the burst may be separated by a duration that is in a range from about 1 nsec to about 50 nsec, for example, from about 10 nsec to about 30 nsec, such as about 20 nsec. In other embodiments, the pulses within the burst may be separated by a duration of up to 100 psec (for example, 0.1 psec, 5 psec, 10 psec, 15 psec, 18 psec, 20 psec, 22 psec, 25 psec, 30 psec, 50 psec, 75 psec, or any range therebetween). For a given laser, the time separation T_p between adjacent pulses within a single burst may be relatively uniform (e.g., within about 10% of one another).

[0031] The pulse repetition rate may be in the range from about 10 kilohertz to about 200 kilohertz, for example from about 40 kilohertz to about 100 kilohertz. Further, the laser 100 has a laser burst repetition rate is related to the time T_b between the first pulse in a burst to the first pulse in the subsequent burst (laser burst repetition rate = 1/T_b). In some embodiments, the laser burst repetition rate may be in a range of from about 1 kHz to about 4 MHz. In embodiments, the laser burst repetition rate may be, for example, in a range of from about 10 kHz to 650 kHz, for example 200 kHz. The exact timing, pulse duration, and burst repetition rate may vary depending on the laser design, but short pulses (T_d <20 psec and, in some embodiments, T_d≤ 15 psec) of high intensity have been shown to work particularly well. The average laser power per burst measured at the material may be at least about 40 μΐ per mm of thickness of material. For example, in embodiments, the average laser power per burst may be from about 40 uJ/mm to about 2500 uJ/mm, or from about 500 uJ/mm to about 2250 uJ/mm. In a specific example, for a 0.5 mm to 0.7 mm thick Corning EAGLE XG^® transparent workpiece, pulse bursts of from about 300 uJ to about 600 μΐ may cut and/or separate the workpiece, which corresponds to an exemplary range of about 428 μΐ/ηπη to about 1200 μΐ/ηπη (i.e., 300 μ1/0.7ηπη for 0.7 mm EAGLE XG^® glass and 600 μΜ).5ιηιη for a 0.5 mm EAGLE XG^® glass).

[0032] The pulse energy required to modify the transparent workpiece 90 may be described in terms of the burst energy (i.e., the energy contained within a burst where each burst contains a series of pulses), or in terms of the energy contained within a single laser pulse (many of which may comprise a burst). The energy per burst may be from about 25 μΐ to about 750 μΐ e.g., from about 50 μΐ to about 500 μΐ, or from about 50 μΐ to about 250 μΤ For some glass compositions, the energy per burst may be from about 100 μΐ to about 250 μΐ However, for display or TFT glass compositions, the energy per burst may be higher (e.g., from about 300 μ] to about 500 μ J, or from about 400 μ] to about 600 μ], depending on the specific glass composition of the transparent workpiece 90). The use of a pulsed laser beam 102 capable of generating such bursts is advantageous for cutting or modifying transparent materials, for example glass. In contrast with the use of single pulses spaced apart in time by the repetition rate of the single-pulsed laser, the use of a burst sequence that spreads the laser energy over a rapid sequence of pulses within the burst allows access to larger timescales of high intensity interaction with the material than is possible with single-pulse lasers.

[0033] When the laser intensity of the pulsed laser beam 102 directed into the transparent workpiece 90 is above a threshold, the pulsed laser beam 102 may induce absorptive nonlinear optical effects (e.g., multi-photon absorption (MPA), avalanche ionization, and the like). The material of the transparent workpiece 90 may be modified via these absorptive nonlinear effects, for example, at or near the beam waist BW of the pulsed laser beam 102. MPA relies on the response of the transparent workpiece material to a high intensity electromagnetic field generated by the pulsed laser beam 102 that ionizes electrons and leads to optical breakdown and plasma formation. MPA is the simultaneous absorption of two or more photons of identical or different frequencies that excites a molecule from one state (usually the ground state) to a higher energy electronic state (i.e., ionization). The energy difference between the involved lower and upper states of the molecule is equal to the sum of the energies of the involved photons. MPA, also called induced absorption, can be a second- order or third-order process (or higher order), for example, that is several orders of magnitude weaker than linear absorption. It differs from linear absorption in that the strength of second- order induced absorption may be proportional to the square of the light intensity, for example, and thus it is a nonlinear optical process. Because multi-photon absorption is a nonlinear process, the magnitude of its effect varies quickly with the applied optical intensity of the laser pulse. The intensity provides the instantaneous energy flux delivered by the optical pulse through the center C of the beam waist BW. In operation, by translating or scanning the beam waist BW at or below the first surface 96, a portion of the first surface 96 may be ablated by laser ablation to create the defects described in detail below. As used herein "ablation" and "laser ablation" mean the removal of glass material from the glass article by vaporization due to the energy introduced by the pulsed laser beam 102, for example, via absorptive nonlinear optical effects. [0034] Referring now to FIG. 2, the transparent workpiece 90 is depicted undergoing laser ablation along the desired separation path 93. As discussed above, the laser 100 may be positioned such that the pulsed laser beam 102 is orthogonal with respect to the first surface 96 of the transparent workpiece 90. In FIG. 2, the laser 100 and the transparent workpiece 90 are depicted translating relative to one another in the first direction 82 creating the score line 92 positioned along the first direction 82.

[0035] Referring now to FIGS. 3 and 4, sectional views of the transparent workpiece 90 and the score line 92 formed therein are depicted in more detail. FIG. 3 is a sectional view along section A-A of FIG. 2 and FIG. 4 is a sectional view along section B-B of FIG. 2. The score line 92 extends into the transparent workpiece 90 to a score line floor 94. Further, the score line 92 has a score line width W at the first surface 96 of the transparent workpiece 90, as shown in FIG. 4. The score line 92 is formed by laser ablating material at and beneath the first surface 96 of the transparent workpiece 90 as the pulsed laser beam 102 translates relative to the transparent workpiece 90. For example, the pulsed laser beam 102 is focused and positioned such that the center C of the beam waist BW is located at or near the first surface 96 of the transparent workpiece 90 in the illustrated embodiment.

[0036] By focusing the pulsed laser beam 102 such that the center C of the beam waist BW of the pulsed laser beam 102 is positioned at or near the first surface 96 of the transparent workpiece 90, the pulsed laser beam 102 ablates portions of the transparent workpiece 90 at the impingement location 97, extending from the first surface 96 to the score line floor 94. The pulsed laser beam 102 ablates the score line 92 into the transparent workpiece 90 by introducing heat to the transparent workpiece 90, which causes material of the transparent workpiece 90 to ablate along the first surface 96. In other embodiments, the pulsed laser beam 102 may ablate the transparent workpiece 90 at the second surface 98. For example, the pulsed laser beam 102 may be focused into the transparent workpiece 90 such that the beam waist BW is positioned at or near the second surface 98 the transparent workpiece 90. Because the transparent workpiece 90 is substantially transparent at the wavelength of the pulsed laser beam 102, it is possible to position the beam waist BW at or below (outside) the second surface 98 of the transparent workpiece 90 without causing damage within the bulk of the transparent workpiece 90 or at the first surface 96.

[0037] As depicted in FIGS. 3 and 4, the score line 92 extends a score depth 95 into the transparent workpiece 90, which is less than a thickness 91 of the transparent workpiece 90. The score depth 95 may approximately correspond to the focal area 104 of the pulsed laser beam 102 (see FIG. IB) that extends into the thickness 91 of the transparent workpiece 90 when the intensity of the laser beam supports non-linear interaction/absorption. The score depth 95 may also be affected by the traversal speed of the laser 100 relative to the transparent workpiece 90, the composition and thickness of the transparent workpiece 90, laser properties, and other factors, for example, the number of passes of the pulsed laser beam 102 along the score line 92 and the repetition rate of the pulsed laser beam 102. In some embodiments, the score depth 95 may be from about 10 μηι to about 200 μιτι, for example, from about 10 μηι to about 100 μιη, from about 10 μηι to about 60 μιτι, from about 10 μηι to about 35 μηι, or the like. Further, the score depth 95 may be substantially constant along the score line 92. For example, the score depth 95 may deviate by 20% or less along the score line 92, for example, less than 15% or less, 10% or less, 5% or less, 4% or less, 3% or less, 2% or less, 1% or less, or the like.

[0038] The score line 92 macroscopically indicates a weakened region of the transparent workpiece 90 and establishes a path for crack propagation for separation of the transparent workpiece 90 into separate portions along the score line 92. The transparent workpiece 90 may be separated by applying mechanical stress, thermal stress, or both after formation of the score line 92. In some embodiments, the transparent workpiece 90 may be separated along the score line 92 by applying a bending moment (i.e. mechanical stress) to the transparent workpiece 90, for example, using a four point bend apparatus to place the score line 92 of the transparent workpiece 90 in tension.

[0039] Further, the transparent workpiece 90 may be separated along the score line 92 by heating the transparent workpiece 90 (i.e. applying thermal stress), for example, using an infrared laser. Suitable infrared lasers to generate thermal stress in glass would typically have wavelengths that are readily absorbed by glass, (e.g., lasers having wavelengths ranging from 1.2 μιη to 13 μιτι, for example, a range of 4 μηι to 12 μηι). The infrared laser beam may be a laser beam produced by a carbon dioxide laser (a "CO2 laser"), a carbon monoxide laser (a "CO laser"), a solid state laser, a laser diode, or combinations thereof. Such an infrared laser beam may serve as a controlled heat source that rapidly increases the temperature of the transparent workpiece 90 at or near the score line 92. This rapid heating may build compressive stress in the transparent workpiece 90 on or adjacent to the score line 92. Since the area of the heated glass surface is relatively small compared to the overall surface area of the transparent workpiece 90, the heated area cools relatively rapidly. The resultant temperature gradient induces tensile stress in the transparent workpiece 90 sufficient to propagate a crack along the score line 92 and through the thickness 91 of the transparent workpiece 90, resulting in full separation of the transparent workpiece 90 along the score line 92. Without being bound by theory, it is believed that the tensile stress may be caused by expansion of the glass (i.e., changed density) in portions of the workpiece with higher local temperature. Alternatively, the transparent workpiece 90 may be heated by submerging the transparent workpiece 90 in a heated bath.

[0040] Referring now to FIGS. 5-7, once separated, each separated transparent workpiece 190 comprises a separated edge 160 having an edge surface 162. FIG. 5 depicts a partial front view of the separated edge 160. FIG. 6 depicts a partial side view of the separated edge 160. FIG. 7 depicts a partial perspective view of the separated edge 160. The separated edge 160 extends between a first surface 196 and a second surface 198 of the separated transparent workpiece 190. Before separation of the transparent workpiece 90 (FIGS. 1 -4), the first surface 196 of the separated transparent workpiece 190 formed a portion of the first surface 96 of the transparent workpiece 90 and the second surface 198 of the separated transparent workpiece 190 formed a portion of the second surface 98 of the transparent workpiece 90.

[0041] As depicted in FIGS. 5-7, the edge surface 162 of the separated edge 160 comprises a scored surface region 164 and a cracked surface region 163. The scored surface region 164 is formed by laser ablation and corresponds to the score line 92 of the transparent workpiece 90, described above. The scored surface region 164 extends from the first surface 196 of the separated transparent workpiece 190 to a score depth line 166, which corresponds to the score line floor 94 of the transparent workpiece 90, described above. In particular, before separation of the transparent workpiece 90, the scored surface region 164 was a wall of the score line 92 and the score depth line 166 was a portion of the score line floor 94 of the score line 92. Further, the cracked surface region 163 is formed by propagating a crack through the transparent workpiece 90 along the score line 92 to separate the transparent workpiece 90. The cracked surface region 163 of the separated edge 160 extends from the score depth line 166 to the second surface 198 of the separated transparent workpiece 190. In particular, the cracked surface region 163 corresponds to the portion of the transparent workpiece 90 that was separated along the score line 92 by applying stress to the score line 92, as described above. [0042] Referring now to FIGS. 5 and 7, the separated edge 160 may include a hackle region 170 comprising one or more hackle features 172 extending from the score depth line 166 toward the second surface 198 of the separated transparent workpiece 190 along the separated edge 160. As used herein "hackle feature" refers to a feature (e.g. , a line on the crack surface running in the location direction of cracking) that separates non-coplanar portions 165 of the edge surface 162 of the separated edge 160. For example, the non- coplanar portions 165 may be irregularly oriented portions of the edge surface 162 and the hackle features 172 connect these irregularly oriented portions. While not intending to be limited be theory, hackle features result from a localized deviation in the direction of a crack front as a result of, for example, changes in crack front velocity, the stress field driving the crack (for example, a localized variation in the stress field) and material inhomogenieties. Hackle features, generally, comprise component lines that run parallel to the local direction of crack spreading.

[0043] As non-limiting examples, the one or more hackle features 172 may comprise twist hackle, shear hackle, mist hackle, stress intensity hackle, or the like. While not intending to be limited by theory, twist hackle comprises a hackle feature that separates portions of the crack surface, each of which has rotated from the original crack plane in response to a lateral rotation or twist in the axis of principal tension. For example, twist hackle may form when a twist is induced during crack propagation along the score line 92 of the transparent workpiece 90. Twist hackle separates non-coplanar portions 165 of the edge surface 162, each of which may be formed by rotating in response to a lateral rotation or twist in an axis of principle tension (e.g., an axis along the score line 92) during crack propagation. For example, a lateral rotation or twist in an axis of principle tension may be generated by variable stress conditions present within in the transparent workpiece 90.

[0044] Each hackle feature 172 extends from the score depth line 166 toward the second surface 198 of the separated transparent workpiece 190, along the cracked surface region 163. Further, the individual hackle feature 172 of the hackle region 170 that extends the farthest distance from the score depth line 166 toward the second surface 198 defines a maximum hackle depth 174 of the hackle region 170. It is advantageous to minimize the maximum hackle depth 174 of the separated edge 160. Large hackle features 172 may limit the strength of the separated edge 160 and may limit the ability to finely position the separated edge 160 of the separated transparent workpiece 190. In some embodiments, separating the transparent workpiece 90 by laser ablating a score line 92 comprising a score depth 95 of between about 10 μηι and about 60 μηι minimizes the maximum hackle depth 174, for example, such that the maximum hackle depth 174 is about 50 μηι or less, 30 μηι or less, 20 μηι or less, 10 μηι or less, or the like.

[0045] Referring now to FIGS. 6 and 7, in some embodiments, it may be desirous for the cracked surface region 163 of the separated edge 160 (e.g., the portion of the separated edge 160 extending between the score depth line 166 and the second surface 198) to be orthogonal to both the first surface 196 and the second surface 198 of the separated transparent workpiece 190. For example, it may be desirous for the cracked region of the separated edge 160 to be coplanar with a crack propagation plane 195 (FIGS. 1A, 6, and 7). The crack propagation plane 195 is a plane orthogonal to both the first surface 196 and the second surface 198 of the separated transparent workpiece 190. As shown in FIG. 1 , prior to separation of the transparent workpiece 90 into the separated transparent workpiece 190, the crack propagation plane 195 extends approximately along the desired separation path 93 of the transparent workpiece 90. Further, as shown in FIGS. 6 and 7, after separation of the transparent workpiece 90 into the separated transparent workpiece 190, the crack propagation plane 195 extends orthogonal to the first surface 196 and the second surface 198, through the score depth line 166.

[0046] The orthogonality of the separated edge 160 with respect to the first surface 196 may be determined by measuring an edge deviation distance 180 of the cracked surface region 163 of the separated transparent workpiece 190. The edge deviation distance 180 is a distance between a first boundary plane 186 of the cracked surface region 163 and a second boundary plane 188 of the cracked surface region 163. Both the first boundary plane 186 and the second boundary plane 188 are parallel to the crack propagation plane 195 and orthogonal to the first surface 196 and the second surface 198 of the separated transparent workpiece 190. Further, the first boundary plane 186 extends through a first boundary point 182 of the cracked surface region 163 and the second boundary plane extends through a second boundary point 184 of the cracked surface region 163. The first boundary point 182 is the most inward location along the cracked surface region 163 of the separated edge 160 (e.g., inward toward the bulk of the separated transparent workpiece 190) and the second boundary point 184 is the most outward location along the cracked surface region 163 of the separated edge 160 (e.g., outward away from the bulk of the separated transparent workpiece 190). In the example depicted in FIGS. 6 and 7, the first boundary point 182 is located at the second surface 198 of the separated transparent workpiece 190 and the second boundary point 184 is located between the score depth line 166 and the second surface 198. However, it should be understood that the first and second boundary points 182, 184 may be located anywhere along the cracked surface region 163 from the score depth line 166 to the second surface 198. Further, in an embodiment where the edge deviation distance 180 is zero, the first and second boundary planes 186 and 188 are co-planar with the crack propagation plane 195.

[0047] In some embodiments, the edge deviation distance 180 may be about 100 μιτι or less, 75 μιτι or less, 50 μιη or less, 40 μιη or less, 30 μιτι or less, 20 μιτι or less, 10 μιτι or less, or the like. It is advantageous to minimize the edge deviation distance 180 of the separated edge 160. A large edge deviation distance 180 may limit the strength of the separated edge 160 and may limit the ability to finely position the separated edge 160 of the separated transparent workpiece 190. Separating the transparent workpiece 90 by laser ablating a score line 92 comprising a score depth 95 of between about 10 μιτι and about 60 μιτι minimizes the edge deviation distance 180, for example such that the edge deviation distance 180 is about 30 μιτι or less, 20 μιτι or less, 10 μιτι or less, or the like. Further, the maximum hackle depth 174 is correlated with the edge deviation distance 180 such that reducing the maximum hackle depth 174 may reduce the edge deviation distance 180. For example, when the maximum hackle depth 174 is about 10 μιτι or less, the edge deviation distance 180 may be about 20 μιτι or less. While not intending to be limited by theory, the hackle features 172 may be formed by a torque that forces the crack out of the crack propagation plane 195. Thus, hackle features 172 are a good indicator a large edge deviation away from the crack propagation plane 195 (e.g., a large edge deviation distance 180).

[0048] In some embodiments, separating the transparent workpiece 90 by laser ablating a score line 92 comprising a score depth 95 of between about 10 μιτι and about 60 μιτι may also minimize cracks that form in a direction orthogonal to the crack propagation plane 195, for example, cracks that extend into the bulk of the separated transparent workpiece 190, and may minimize the number of crack initiation sites formed when separating the transparent workpiece 90. Moreover, the separated edge 160 described herein may be an unpolished separated edge. Thus, the maximum hackle depths 174 and the edge deviation distances 180 described herein are properties of the separated edge 160 present without polishing or otherwise processing the separated edge 160. [0049] Referring now to FIG. 8, a graph 200 is depicted showing the relationship between the score depth 95 of the score line 92 formed in the first surface 96 of the transparent workpiece 90 (FIGS. 3 and 4) before separation of the transparent workpiece 90 into separated transparent workpieces 190 and the maximum hackle depth 174 of the separated edge 160 of the separated transparent workpiece 190 formed after separation of the transparent workpiece 90. In particular, FIG. 8 depicts this relationship for two samples of transparent workpieces 90: a first transparent workpiece sample 202 and a second transparent workpiece sample 204. As depicted in FIG. 8, the maximum hackle depth 174 is minimized by laser forming the score line 92 to a score depth 95 of from about 10 μιη to about 60 μιη for the first transparent workpiece sample 202 and by laser forming the score line 92 to a score depth 95 of from about 10 μιη to about 35 μιτι for the second transparent workpiece sample 204. While not intending to be limited by theory, when the score depth 95 is too shallow (e.g., less than 10 μιτι) there may not be enough damage in the transparent workpiece 90 to sufficiently guide the crack propagating along the score line 92 (e.g., along the crack propagation plane 195). Further, when the score depth 95 is too deep (e.g., greater than 60 μιτι for the first transparent workpiece sample 202 or greater than 35 μιη for the second transparent workpiece sample 204), crack propagation may start in multiple locations along the score line floor 94, resulting in large hackle features 174. Moreover, it should be understood that transparent workpieces 90 comprising other material compositions may a different ranges of score depth 95.

[0050] In some embodiments, the first transparent workpiece sample 202 may comprise a glass substrate that is substantially free of alkali metals, e.g., the total concentration of the alkali elements Li₂0, Na₂0, and K₂0 is less than about 0.1 mole percent (mol%). Further, the first transparent workpiece sample 202 may comprise, on an oxide basis: 64.0-71.0 mol% of Si0₂, 9.0-12.0 mol% of A1₂0₃, 7.0-12.0 mol% of B₂0₃, 1.0-3.0 mol% of MgO, 6.0-11.5 mol% of CaO, 0-2.3 mol% of SrO (e.g., 0-1.0 mol%), 0-2.3 mol% of BaO (e.g., 0-0.1 mol% or 0-0.05 mol%), 0-0.05 mol% of As₂0₃ (e.g., 0-0.02 mol%), 0-0.05 mol% of Sb₂0₃ (e.g., 0- 0.02 mol%), 0.010-0.033 mol% of Fe₂0₃ (e.g., 0.012-0.024 mol%), and 0.017-0.112 mol% of Sn0₂ (e.g., 0.021-0.107 mol%). In some embodiments, the first transparent workpiece sample 202 may comprise less than or equal to 0.002 mol% of sulfur, less than or equal to 0.4 mol% of a halide such as chlorine, and may comprise an Fe²⁺ to Fe³⁺ ratio that is greater than or equal to 0.5. The first transparent workpiece sample 202 may also be substantially free of barium, arsenic, and antimony, Y2O₃ or I^Ch. It should be understood that the ranges specified above include the end points of the range.

[0051] Further, the first transparent workpiece sample 202 may comprise a density that is less than or equal to 2.41 g/cm³, a strain point that is greater than or equal to 650° C, and a linear coefficient of thermal expansion (CTE) over the temperature range 0-300° C which satisfies the relationship: 28x l0^~7/° C < CTE < 35x l0^~7/° C. Further, the first transparent workpiece sample 202 may satisfy one or more of the following relationships: ∑[RO]/ [Al₂0₃]≥ 1, ∑[RO]/[Al₂0₃] > 1 . 03, ∑[RO]/[Al₂0₃]≤ 1.25, and/or ∑[RO]/[Al₂0₃]≤ 1.12), where [i4Z₂0₃] is the mol% of AI2O3 and is the sum of the mole percents of

MgO, CaO, SrO, and BaO. Moreover, the first transparent workpiece sample 202 may comprise an average gaseous inclusion level of less than 0.05 gaseous inclusions/cm³.

[0052] In some embodiments, the second transparent workpiece sample 204 may comprise a glass substrate that is substantially free of alkali metals, e.g., the total concentration of the alkali elements L12O, Na20, and K2O is less than about 0.1 mol%. Further, the second transparent workpiece sample 204 may comprise, on an oxide basis: 63-75 mol% of S1O2 (e.g., 70.31-72.5 mol%, 64-71 mol%, 68.5-72 mol%, 63-71 mol%, 68-70.5 mol%, 69-72.5 mol% 68-72 mol%, 63-75 mol%, 63-71 mol%, or the like), 11-14.5 mol% of A1₂0₃ (e.g., 11- 13.5 mol%, 11.5-13.5 mol%, 11-14 mol%, 13-14 mol%, 13-14.5 mol%), 0-5 mol% of B₂0₃ (e.g., 1-5 mol%, 1-4.5 mol%, 2-4.5 mol%, 0- 2.5 mol%, 0-3 mol%, 0-2.8 mol%, 0-2 mol%, or the like), 0.9-9 mol% of MgO, (1-6 mol%, 3-5 mol%, 3.5-5 mol%), 4-11 mol% of Ca, (e.g., 4-6.5 mol%, 4-8 mol%, 5-6.5 mol%, 5.25-6.5 mol%, 5.25-11 mol%, or the like), 0-6.5 mol% of SrO (e.g., 0-4.5 mol%, 0-2 mol%, 3-5 mol%, or the like), and 0-9 mol% of BaO (0- 4.5 mol%, 1-9 mol%, 2.5-4.5 mol%, 1.5-5 mol%, or the like). Further, the second transparent workpiece sample 204 may also comprise 0-0.1 mol% of Li₂0, Na₂0, K₂0, or combinations thereof. Further, the transparent workpiece may include 0-0.05 mol% of Sb203, 0-0.005 mol% of As₂0₃ and 0-0.005 mol% of Sb₂0₃. It should be understood that the ranges specified above include the end points of the range.

[0053] In some embodiments, the second transparent workpiece sample 204 may satisfy the following relationship: 1.05 < ([MgO] + [CaO] + [SrO] + [BaO]) / [A1₂0₃] <1.4, where 0.2 < [MgO] / ([MgO] + [CaO] + [SrO] + [BaO]) < 0.35, where 0.65 < ([CaO] + [SrO] + [BaO])/[Al₂0₃] < 0.95, and where [A1₂0₃], [MgO], [CaO], [SrO], [BaO] represent the mole percents of the respective oxide components. In some embodiments, the second transparent workpiece sample 204 may satisfy one or more of the following relationship: ([MgO] + [CaO] + [SrO] + [BaO]) / [A1₂0₃] < 1.6 and 1 < ([MgO] + [CaO] + [SrO] + [BaO]) / [A1₂0₃] < 1.6, where [A1₂0₃], [MgO], [CaO], [SrO], [BaO] represent the mole percents of the respective oxide components. The second transparent workpiece sample 204 may also include one or more chemical fining agents, such as, Fe₂0₃, Ce0₂, Mn0₂ Sn0₂, As₂0₃, Sb₂0₃, F, CI and Br at a total concentration of about 0-0.5 mol%. Further, the second transparent workpiece sample 204 may comprise about 0.005-0.2 mol% of any one of or a combination of Ce0₂, Fe₂03, and Mn0₂, which may introduce color to the second transparent workpiece sample 204 via visible absorptions in their final valence state(s) in the second transparent workpiece sample 204.

[0054] In some embodiments, the second transparent workpiece sample 204, for example, the second transparent workpiece sample 204 may have a high annealing point and high Young's modulus, which may limit or prevent distortion of the second transparent workpiece sample 204 due to compaction/shrinkage during thermal processing subsequent to manufacturing of the second transparent workpiece sample 204 (e.g., during manufacture of a TFT). The annealing point may be greater than or equal to about 765° C, 775° C, 785 °C, 795 °C, 800 °C, or the like. In some embodiments, the Young's modulus may be from about 81 GPa to 88 GPa, for example, from about 81 GPa to 85 GPa, from about 82 GPa to 84.5 GPa. Further, the Young's modulus may be about 81 GPa or more, about 81.2 GPa or more, about 81.5 GPa or more, or the like, about 82 GPa or less. In some embodiments, a density of the second transparent workpiece sample 204 is less than or equal to about 2.7 g/cm³, 2.65 g/cm³, 2.63 g/cm³, 2.62 g/cm³ 2.61 g/cm³, 2.57 g/cm³, 2.55 g/cm³, or the like. In some embodiments, the density may be from about 2.57 g/cm³ to about 2.626 g/cm³.

[0055] The second transparent workpiece sample 204 may also have a high etch rate, which is a measure of how quickly the material (e.g., glass material) of the transparent workpiece 90 can be removed from the transparent workpiece 90. A high etch rate allows for the economical thinning of the transparent workpiece 90, which may be useful in embodiments in which the transparent workpiece 90 is used as display glass. Further, the etch rate of the transparent workpiece 90 may be quantified by an etch index, which is an estimate the etch rate of a glass composition in commercially relevant etching processes (such as, but not limited to, a ten minute soak in a 10% HF/ 5% HC1 solution at 30 °C). The etch index may be mathematically defined by: Etch Index = -54.6147 + (2.50004[ ΖΟ₃]) + (1.3134[fl₂0₃]) + (1.84106[M#O]) + (3.01223 [CaO]) + (3.7248 [SrO]) + (4.13149[fla0])₅ where the oxides are in mol%. For example, in some embodiments, the etch index is greater than or equal to about 21. In various embodiments, the etch index is greater than or equal to about 21.5, 22, 22.5, 23, 23.5, 24, 24.5, 25, 25.5, 26, 26.5, 27, 27.5, 28, 28.5, 29, 29.5, 30, 30.5 or 31.

[0056] In view of the foregoing description, it should be understood that a separated transparent workpiece having a separated edge may be formed by laser ablating a transparent workpiece to form a score line extending into the surface of the transparent workpiece and applying stress to the score line to separate the transparent workpiece into two or more separated transparent workpieces each having a separated edge. Further, laser ablating the score line to a score depth of about 10 μηι to about 60 μηι and subsequently separating the transparent workpiece forms two separated transparent workpieces each comprising a separated edge having minimal hackle depth and a minimal edge deviation distance. Minimizing the hackle depth and the edge deviation distance helps strengthens the separated edge and allows the separated edge of to be finely positioned in an end application of the separated transparent workpiece, for example, when the separated transparent workpiece is used as a TFT or a display glass for an electronic device.

[0057] 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. It 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.

[0058] Directional terms as used herein - for example up, down, right, left, front, back, top, bottom - are made only with reference to the figures as drawn and are not intended to imply absolute orientation.

[0059] Unless otherwise expressly stated, it is in no way intended that any method set forth herein be construed as requiring that its steps be performed in a specific order, nor that with any apparatus specific orientations be required. Accordingly, where a method claim does not actually recite an order to be followed by its steps, or that any apparatus claim does not actually recite an order or orientation to individual components, or it is not otherwise specifically stated in the claims or description that the steps are to be limited to a specific order, or that a specific order or orientation to components of an apparatus is not recited, it is in no way intended that an order or orientation be inferred, in any respect. This holds for any possible non-express basis for interpretation, including: matters of logic with respect to arrangement of steps, operational flow, order of components, or orientation of components; plain meaning derived from grammatical organization or punctuation, and; the number or type of embodiments described in the specification.

[0060] As used herein, the singular forms "a," "an" and "the" include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to "a" component includes aspects having two or more such components, unless the context clearly indicates otherwise.

[0061] It is noted that the term "substantially" may be utilized herein to represent the inherent degree of uncertainty that may be attributed to any quantitative comparison, value, measurement, or other representation. This term is also utilized herein to represent the degree by which a quantitative representation may vary from a stated reference without resulting in a change in the basic function of the subject matter at issue.

[0062] While particular embodiments have been illustrated and described herein, it should be understood that various other changes and modifications may be made without departing from the spirit and scope of the claimed subject matter. Moreover, although various aspects of the claimed subject matter have been described herein, such aspects need not be utilized in combination. It is therefore intended that the appended claims cover all such changes and modifications that are within the scope of the claimed subject matter.

Claims

CLAIMS What is claimed is:

1. A method for laser processing a transparent workpiece, the method comprising:

directing a pulsed laser beam into the transparent workpiece at an impingement location on a first surface of the transparent workpiece such that the pulsed laser beam ablates a portion of material of the transparent workpiece at the impingement location, wherein the pulsed laser beam comprises a pulse energy of from about 5 μ] to about 50 μ]; and

translating the pulsed laser beam relative to the first surface of the transparent workpiece along a desired separation path, thereby ablating additional material of the transparent workpiece to form a score line along the desired separation path, the score line comprising a score depth of from about 10 μιτι to about 60 μιτι.

2. The method of claim 1 , further comprising applying stress to the score line of the transparent workpiece to separate at least one separated transparent workpiece from the transparent workpiece along the score line, wherein the at least one separated transparent workpiece comprises a separated edge.

3. The method of claim 2, wherein the separated edge of the at least one separated transparent workpiece extends between a first surface and a second surface of the at least one separated transparent workpiece and further comprises :

a scored surface region extending from the first surface of the at least one separated transparent workpiece to a score depth line;

a cracked surface region extending from the score depth line to the second surface of the at least one separated transparent workpiece;

one or more hackle features extending from the score depth line toward the second surface along the cracked surface region, wherein a maximum hackle depth of the one or more hackle features is 10 μιτι or less; and

an edge deviation distance of 30 μιτι or less, wherein the edge deviation distance is a distance between a first boundary plane of the cracked surface region and a second boundary plane of the cracked surface region.

4. The method of claim 2, wherein the stress applied to the score line of the transparent workpiece comprises mechanical stress, thermal stress, or a combination thereof.

5. The method of claim 1 , wherein the transparent workpiece comprises a glass substrate that is substantially free of alkali metals and comprises, on an oxide basis: 64.0-71.0 mol% of Si0₂, 9.0-12.0 mol% of A1₂0₃, 7.0-12.0 mol% of B₂0₃, 1.0-3.0 mol% of MgO, 6.0-11.5 mol% of CaO, 0-2.3 mol% of SrO, and 0-2.3 mol% of BaO.

6. The method of claim 5, wherein the glass substrate of the transparent workpiece further comprises, on an oxide basis: 0-0.05 mol% of As₂0₃, 0-0.05 mol% of Sb₂0₃, 0.010-0.033 mol% of Fe₂0₃, and 0.017-0.112 mol% of Sn0₂.

7. The method of claim 5, wherein the glass substrate of the transparent workpiece comprises, on an oxide basis: 1 <∑[#0]/[i4Z₂0₃] < 1.25, wherein [71Z₂0₃] is the mol% of A1₂0₃ and∑[#0] is a sum of the mole percents of MgO, CaO, SrO, and BaO.

8. The method of claim 1 , wherein the transparent workpiece comprises a glass substrate that is substantially free of alkali metals and comprises, on an oxide basis: 63.0-71.0 mol% of Si0₂, 13.0-14.0 mol% of A1₂0₃, 0-3.0 mol% of B₂0₃, 0.9-9.0 mol% of MgO, 5.25-11.0 mol% of CaO, 0-6.0 mol% of SrO, and 1-9.0 mol% of BaO.

9. The method of claim 8, wherein the glass substrate of the transparent workpiece comprises, on an oxide basis∑[β0]/[ΛΖ₂0₃]≤ 1-6, wherein [71Z₂0₃] is the mol% of A1₂0₃ and∑[#0] is a sum of the mole percents of MgO, CaO, SrO, and BaO.

10. The method of claim 8, wherein the glass substrate of the transparent workpiece comprises an etch index greater than or equal to 21, an annealing point greater than or equal to 765 °C, and a Young's modulus of from 81 GPa to 88 GPa.

11. The method of claim 8, wherein the score depth of the score line is from about 10 μηι to about 35 μηι.

12. The method of claim 1, wherein the pulsed laser beam comprises a wavelength of from about 200 nm to about 600 nm and a pulse duration of from about 1 picosecond to about 100 picoseconds.

13. A separated transparent workpiece comprising:

a first surface opposite a second surface; and

a separated edge extending between the first surface and the second surface; wherein the separated edge comprises:

a scored surface region extending from the first surface to a score depth line; a cracked surface region extending from the score depth line to the second surface;

14. The separated transparent workpiece of claim 13, further comprising a thickness extending between the first surface and the second surface, wherein the thickness is from about 300 μιτι to about 700 μιτι.

15. The separated transparent workpiece of claim 13, wherein the score depth line is spaced from the first surface by a distance of from about 10 μιτι to about 60 μπι

16. The separated transparent workpiece of claim 13, further comprising a glass substrate that is substantially free of alkali metals and comprises, on an oxide basis: 64.0-71.0 mol% of Si0₂, 9.0-12.0 mol% of A1₂0₃, 7.0-12.0 mol% of B₂0₃, 1.0-3.0 mol% of MgO, 6.0-11.5 mol% of CaO, 0-2.3 mol% of SrO, 0-2.3 mol% of BaO.

17. The separated transparent workpiece of claim 13, further comprising a glass substrate that is substantially free of alkali metals and comprises, on an oxide basis: 63.0-71.0 mol% of Si0₂, 13.0-14.0 mol% of A1₂0₃, 0-3.0 mol% of B₂0₃, 0.9-9.0 mol% of MgO, 5.25-11.0 mol% of CaO, 0-6.0 mol% of SrO, and 1-9.0 mol% of BaO.

18. A method for laser processing a transparent workpiece, the method comprising: directing a pulsed laser beam into the transparent workpiece at an impingement location on a first surface of the transparent workpiece such that the pulsed laser beam ablates a portion of material of the transparent workpiece at the impingement location wherein the pulsed laser beam comprises a pulse energy of from about 5 μ] to about 50 μ];

translating the pulsed laser beam relative to the first surface of the transparent workpiece along a desired separation path, thereby ablating additional material of the transparent workpiece to form a score line along the desired separation path; and

applying stress to the score line of the transparent workpiece to separate at least one separated transparent workpiece from the transparent workpiece along the score line, wherein the at least one separated transparent workpiece comprises an unpolished separated edge that extends between a first surface and a second surface of the at least one separated transparent workpiece and further comprises:

19. The method of claim 18, wherein the score line comprises a score depth of from about 10 μιτι to about 60 μιη.

20. The method of claim 18, wherein:

the transparent workpiece comprises a glass substrate that is substantially free of alkali metals and comprises, on an oxide basis: 63.0-71.0 mol% of S1O2, 13.0-14.0 mol% of AI2O₃, 0-3.0 mol% of B2O₃, 0.9-9.0 mol% of MgO, 5.25-11.0 mol% of CaO, 0-6.0 mol% of SrO, and 1 -9.0 mol% of BaO; and

the score line comprises a score depth of from about 10 μιτι to about 35 μιτι.