Methods for forming fiducial marks on glass-based substrates

Abstract

According to embodiments of the present disclosure, a method for forming a fiducial mark on a glass-based substrate includes irradiating the glass-based substrate with a laser beam to form a plurality of damage tracks that each extend from a first major surface of the glass-based substrate into the glass-based substrate. Each damage track includes a plurality of voids in the glass-based substrate and extends through less than or equal to 90 % of a thickness of the glass-based substrate. The plurality of damage tracks are arranged along a damage track line and are spaced apart by a distance from 1 µm to 150 µm along the first surface of the glass-based substrate. The method further includes contacting the glass-based substrate with an etchant to remove at least a portion of the glass-based substrate along the damage track line to form the fiducial mark.

Description

METHODS FOR FORMING FIDUCIAL MARKS ON GLASS-BASED SUBSTRATESCROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of priority to U.S. Provisional Patent Application No. 63 / 606,646 filed on December 6, 2023, the content of which is incorporated herein by reference in its entirety for all purposes.BACKGROUNDField

[0002] The present specification generally relates to methods for forming fiducial marks on glass-based substrates.Technical Background

[0003] Glass-based substrates may be used as an interposer between electrical components (e.g., printed circuit boards, integrated circuits, and the like). Metalized through-glass vias may provide a path through the glass-based substrate for electrical signals to pass between opposite sides of the glass-based substrate. Fiducial marks may be used to align electrical components with through-glass vias in the glass-based substrate on both the front side and the back side of the glassbased substrate.SUMMARY

[0004] According to one or more embodiments of the present disclosure, a method for forming a fiducial mark on a glass-based substrate comprises irradiating the glass-based substrate with a laser beam to form a plurality of damage tracks that each extend from a first major surface of the glass-based substrate into the glass-based substrate. Each damage track comprises a plurality of voids in the glass-based substrate, and each damage track extends through less than or equal to 90 % of a thickness of the glass-based substrate. The plurality of damage tracks are arranged along a damage track line and are spaced apart by a distance from 1 pm to 150 pm along the first surface of the glass-based substrate. The method further comprises contacting the glass-based substrate with an etchant to remove at least a portion of the glass-based substrate along the damage trackline to form the fiducial mark comprising a linear depression in the first major surface of the glassbased substrate.

[0005] Additional features and advantages 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.

[0006] 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

[0007] FIG. 1 A schematically depicts a cross-sectional view of a process for the formation of a fiducial mark on a glass-based substrate, according to one or more embodiments described herein;

[0008] FIG. IB schematically depicts a bottom view of a process for the formation of a fiducial mark on a glass-based substrate, according to one or more embodiments described herein;

[0009] FIG. 2 schematically depicts a process for irradiating a glass-based substrate with a laser beam, according to one or more embodiments described herein;

[0010] FIG. 3 schematically depicts a bottom view of a glass-based substrate comprising a plurality of damage tracks arranged on a damage track line, according to one or more embodiments described herein;

[0011] FIG. 4 schematically depicts a bottom view of a glass-based substrate comprising a linear depression of a fiducial mark, according to one or more embodiments described herein;

[0012] FIG. 5 schematically depicts a process for irradiating a glass-based substrate with a laser beam, according to one or more embodiments described herein;

[0013] FIG. 6 schematically depicts a cross-sectional view of a glass-based substrate comprising a through-glass via and a fiducial mark, according to one or more embodiments described herein;

[0014] FIG. 7 schematically depicts a process for irradiating a glass-based substrate with a laser beam, according to one or more embodiments described herein;

[0015] FIG. 8 schematically depicts a bottom view of a glass-based substrate comprising a plurality of damage tracks, according to one or more embodiments described herein;

[0016] FIG. 9 schematically depicts a cross-sectional view of a glass-based sbustrate comprising a first fiducial mark and a second fiducial mark, according to one or more embodiments described herein;

[0017] FIG. 10 depicts an optical micrograph of a side view of a glass-based substrate comprising a plurality of damage tracks, according to the embodiment of Example 1;

[0018] FIG. 11A depicts an optical micrograph of a back side of a glass-based substrate comprising a plurality of damage tracks, according to the embodiment of Example 1;

[0019] FIG. 11B depicts an optical micrograph of a back side of a glass-based substrate comprising a plurality of damage tracks, according to the embodiment of Example 1;

[0020] FIG. 12 depicts an optical micrograph of a fiducial mark, according to the embodiment of Example 1 ; and

[0021] FIG. 13 depict a screen capture from software used to recognize a fiducial mark, according to the embodiment of Example 1.DETAILED DESCRIPTION

[0022] Reference will now be made in detail to various embodiments of methods for forming fiducial marks on glass-based substrates. Embodiments of methods for forming fiducialmarks on glass-based substrates may include a step of irradiating the glass-based substrate with a laser beam to form a plurality of damage tracks that each extend from a first major surface of the glass-based substrate into the glass-based substrate. The plurality of damage tracks may be arranged along a damage track line and may be spaced apart by a distance of from 1 pm to 150 pm along the first surface of the glass-based substrate. Then, the glass-based substrate may be contacted with an etchant to remove at least a portion of the glass-based substrate along the damage track line to form the fiducial mark. The fiducial mark may comprise a linear depression in the first major surface of the glass-based substrate.

[0023] Without intending to be bound by theory, using the methods describe herein to form fiducial marks may allow fiducial marks to be formed in glass-based substrates without flipping the glass-based substrates. This may reduce the likelihood of damaging the glass-based substrate relative to processes that require flipping the glass-based substrate. Some conventional methods for forming fiducial marks on the back side of the glass-based substrate may require flipping the glass-based substrate. However, flipping the glass-based substrate to form fiducial marks on the back side of the glass-based substrate may introduce errors into the alignment between features on the front side and the back side of the glass-based substrate. Additionally, flipping the glass-based substrate may damage thin-film masks that may be present on the surface of the glass-based substrate. Accordingly, a need exists for alternative methods for forming fiducial marks on glassbased substrates.

[0024] Additionally, one or more embodiments of the methods described herein may be used to form fiducial marks and through-glass vias in the glass-based substrate in the same processing steps, which may decrease error in alignment between the fiducial marks and the through-glass vias. Furthermore, in one or more embodiments, fiducial marks may be formed on both major surfaces of a glass-based substrate in the same process steps, which may improve the alignment between fiducial marks relative to processes where the fiducial marks on opposite major surfaces of the glass-based substrate are formed in different process steps.

[0025] 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 areexpressed 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.

[0026] 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.

[0027] A method for forming a fiducial mark in a glass-based substrate is schematically depicted in FIGS. 1 A and IB. FIG. 1A depicts a cross-sectional view of the glass-based substrate and FIG. IB depicts a bottom view of the glass-based substrate. In summary, the method depicted in FIGS. 1A and IB comprises step 200 of irradiating the glass-based substrate 100 with a laser beam to form a plurality of damage tracks 120 that extend from a first major surface 102 of the glass-based substrate 100 into the glass-based substrate 100. The plurality of damage tracks 120 may be arranged along a damage track line 112. The method depicted in FIGS. 1A and IB also comprises a step 210 of contacting the glass-based substrate 100 with an etchant to remove at least a portion of the glass-based substrate along the damage track line 112 to from the fiducial mark 130 comprising a linear depression in the first major surface 102 of the glass-based substrate 100.

[0028] In one or more embodiments, a glass-based substrate 100 may have a first major surface 102 and a second major surface 104. In one or more embodiments, the glass-based substrate 100 may have a thickness from 20 pm to 2000 pm. As described herein, a “thickness” of the glass-based substrate 100 refers to an average distance from the first major surface 102 to the second major surface 104 of the glass-based substrate 100. For example, the glass-based substrate 100 may have a thickness from 20 pm to 2000 pm, from 100 pm to 2000 pm, from 300 pm to 2000 pm, from 500 pm to 2000 pm, from 700 pm to 2000 pm, from 800 pm to 2000 pm, from 1100 pm to 2000 pm, from 1300 pm to 2000 pm, from 1500 pm to 2000 pm, from 1700 pm to 2000 pm, from 1900 pm to 2000 pm, from 20 pm to 1800 pm, from 20 pm to 1600 pm, from 20 pm to 1400 pm, from 20 pm to 1200 pm, from 20 pm to 1000 pm, from 20 pm to 800 pm, from20 pm to 600 pm, from 20 pm to 400 pm, from 20 pm to 200 pm, or any range or combination of ranges formed from these endpoints.

[0029] In one or more embodiments, step 200 may comprise irradiating the glass-based substrate with a laser beam to form a plurality of damage tracks 120 that each extend from the first major surface 102 of the glass based substrate 100 into the glass based substrate 100. As described herein, a “damage track” is an area of glass that has been structurally modified by irradiation with a laser. In one or more embodiments, the damage track 120 may have a lower refractive index than the surrounding undamaged glass. In some embodiments, the glass in the damage track 120 may have a lower density than the surrounding undamaged glass. In one or more embodiments, the damage track 120 may comprise a plurality of voids in the glass-based substrate 100.

[0030] In one or more embodiments, each damage track 120 may extend through less than or equal to 90 % of the glass-based substrate. For example, each damage track 120 may extend through less than or equal to 90%, 80%, 70%, 60%, 50%, 40%, 20%, or even 10% of the glassbased substrate. In one or more embodiments, each damage track 120 may extend through from 1% to 90% of the glass-based substrate 100. For example, each damage track 120 may extend through from 1% to 90%, from 5% to 90%, from 15% to 90%, from 25% to 90%, from 35% to 90%, from 45% to 90%, from 55% to 90%, from 65% to 90%, from 75% to 90%, from 85% to 90%, from 1% to 80%, from 1% to 70%, from 1% to 60%, from 1% to 50%, from 1% to 40%, from 1% to 30%, from 1% to 20%, from 1% to 10% of the glass-based substrate, or any range or combination of ranges formed from these endpoints.

[0031] In one or more embodiments, each damage track 120 may be substantially perpendicular to the first major surface 102 of the glass-based substrate 100. As described herein a damage track 120 may be “substantially perpendicular” to the first major surface 102 of the glass based substrate 100 when the damage track extends into the glass-based substrate at an angle that is within 10°, 5°, 3°, or even 1° of normal to the first major surface 102 of the glass based substrate 100.

[0032] The damage tracks 120 described herein may be formed by a variety of laser processes. FIG. 2 depicts an embodiment of process step 200 of irradiating the glass-based substrate 100 with a laser beam 302a to form a damage track 120. Referring now to FIG. 2, thedamage tracks 120 may be formed by a pulsed laser beam 302a that is focused into a laser beam focal line 302b that is positioned through the bulk of the glass-based substrate 100. The laser beam focal line 302b may generate an induced multi-photon absorption within the glass-based substrate 100. The multi-photon absorption produces a material modification within the glass-based substrate 100 along the laser beam focal line 302b, forming damage track 120. The laser beam focal line 302b may be created by optics 306. For example, the optics 306 may include a conical lens (e.g., an axicon). Additional description of methods for generating an using a laser beam focal line for forming damage tracks is provided in U.S. Patent Application Publication No. 2021 / 0269357 and in U.S. Patent No. 9,517,963, the entirety of each of which are incorporated by reference herein.

[0033] The optics 306 may from the laser beam 302a into an extended focus, or quasi-non- diffracting beam resulting in a Bessel-like or a Gauss-Bessel beam. Because of the quasi-non- diffracting nature of the beam, the light may maintain a tight focused intensity over a much longer range than is achieved with more commonly used Gaussian beams, allowing for up to the full thickness of the glass-based substrate 100 to be damaged by a single burst pulse or a closely timed burst train of laser pulses. In one or more embodiments, the laser beam may be focused into a laser beam focal line 302b extending through a portion of the glass-based substrate 100 from the first major surface 102 of the glass-based substrate 100.

[0034] In one or more embodiments, the optics 306 used to form the laser beam focal line 302b may be positioned facing the second major surface 104 of the glass-based substrate 100. The glass-based substrate 100 and the optics 306 may be positioned such that the laser beam focal line 302b extends through only a portion of the glass-based substrate 100 from the first major surface 102 of the glass-based substrate 100. This may allow damage tracks extending from the first major surface 102 of the glass-based substrate 100 to be formed without having to flip the glass-based substrate 100 such that the first major surface 102 faces the optics 306 used to focus the laser beam 302a. Without intending to be bound by theory, removing the need to flip the glass-based substrate 100 may prevent damage to the glass-based substrate 100 that may occur during the process of flipping the glass based substrate. Additionally, this may reduce the number of process steps needed to form the fiducial marks on the first major surface 102 of the glass-based substrate 100.

[0035] To modify the glass-based substrate 100 and create the plurality of damage tracks 120, the wavelength of the pulsed laser beam should be transparent to the glass-based substrate 100. In one or more embodiments, the laser beam may have a wavelength from 300 nm to 2000 nm. For example, the laser beam may have a wavelength from 300 nm to 2000 nm, from 500 nm to 2000 nm, from 700 nm to 2000 nm, from 900 nm to 2000 nm, from 1100 nm to 2000 nm, from 1300 nm to 2000 nm, from 1500 nm to 2000 nm, from 1700 nm to 2000 nm, from 1900 nm to 2000 nm, from 300 nm to 1800 nm, from 300 nm to 1600 nm, from 300 nm to 1400 nm, from 300 nm to 1200 nm, from 300 nm to 1000 nm, from 300 nm to 800 nm, from 300 nm to 600 nm, from 300 nm to 400 nm, or any range or combination of ranges formed from these endpoints.

[0036] In embodiments, the pulse duration and intensity may be short enough to achieve the multi-photon absorption effect described above. Ultra-short pulse lasers may be utilized, such as picosecond or femtosecond laser sources. In one or more embodiments, the laser beam may be formed with a picosecond laser. The operation of such a picosecond laser described herein may create a “pulse burst” sub-pulses. Producing pulse bursts is a type of laser operation where the emission of pulses is not in a uniform and steady stream, but rather in tight clusters of sub-pulses. Each pulse burst contains multiple individual sub-pulses of very short duration. For example, each pulse burst may include at least 2 sub-pulses, at least 3 sub-pulses, at least 4 sub-pulses, or at least 5 sub-pulses of very short duration. That is a pulse burst is a pocket of sub-pulses and the pulse bursts are separated from one another by a longer duration than the separation of individual adjacent pulses within each burst. In one or more embodiments, sub-pulses may have a duration of up to 100 psec. For example, sub-pulses may have a duration of 0.05 psec, 0.1 psec, 5 psec, 10 psec, 15 psec, 18 psec, 20 psec, 22 psec, 25 psec, 30 psec, 50 psec, 75 psec, 100 psec, or any value therebetween. These individual sub-pulses within a single pulse burst are referred to as sub-pulses herein to denote the fact that they occur within a single pulse burst. The energy or intensity of each individual sub-pulse within the pulse burst may not be equal to that of other sub-pulses within the pulse burst, and the intensity distribution of the multiple sub-pulses within a pulse burst often follows an exponential decay in time governed by the laser design.

[0037] In one or more embodiments, each sub-pulse within the pulse burst of the exemplary embodiments described herein is separated in time from the subsequent sub-pulse in the burst by a duration tpfrom 1 nsec to 50 nsec (e.g. 10-50 nsec, or 10-30 nsec, with the time oftengoverned by the laser cavity design). For a given laser, the time separation tpbetween each subpulses (sub-pulse-to-sub-pulse separation) within a pulse burst is relatively uniform (±10%). For example, in some embodiments, each sub-pulse within a pulse burst may be separated in time from the subsequent sub-pulse by approximately 20 nsec (50 MHz). For example, for a laser that produces a sub-pulse separation tpof about 20 nsec, the sub-pulse-to-sub-pulse separation tpwithin a pulse burst is maintained within about ±10%, or is about ±2 nsec.

[0038] Referring again to FIGS. 1A and IB, in one or more embodiments, each damage track 120 may comprise a plurality of voids in the glass-based substrate 100. The plurality of voids may be arranged in a straight line normal to the first major surface 102 of the glass-based substrate 100. In one or more embodiments, each of the plurality of voids of the damage track may have a diameter 122 of less than or equal to 2 pm. For example, each of the plurality of voids of the damage track 120 may have a diameter of less than or equal to 2 pm, 1.75 pm, 1.5 pm, 1 pm, 0.75 pm, or even 0.5 pm.

[0039] In one or more embodiments, the plurality of damage tracks 120 may be arranged along a damage track line 112 on the first major surface 102 of the glass-based substrate 100. In one or more embodiments, the damage track line 112 may comprise one or more straight portions. In some embodiments, the damage track line 112 may comprise one or more curved portions. The damage track line 112 may comprise both one or more curved portions and one or more straight portions. In one or more embodiments, the damage track line 112 may form a closed shape on the first surface of the glass-based substrate 100. As described herein a “closed shape” refers to a shape where each line segment and / or curve forming the shape is connected end to end such that there are no gaps in the perimeter of the shape. For example, the damage track line 112 may form a circle, oval, ellipse, triangle, rectangle, or other polygon, a cross, or any other symmetrical or asymmetrical closed shape. In some embodiments, the damage track line 112 may form a circle or a cross. For example, referring now to FIG. 3, the glass-based substrate 100 may comprise a plurality of damage tracks 120 arranged on a damage track line 112. The damage track line 112 comprises a curved portion, and the damage track line 112 forms a circle on the first major surface 102 of the glass-based substrate 100.

[0040] Referring again to FIG. IB, a distance 124 between adjacent damage tracks 120 on the damage track line 112 may be from 1 gm to 150 gm. As described herein, the distance 124 between adjacent damage tracks 120 on the damage track line 112 may be measured from the center of one damage track 120 to the center of an adjacent damage track 120 on the first major surface 102 of the glass-based substrate 100. For example, a distance 124 between adjacent damage tracks 120 on the damage track line 112 may be from 1 pm to 150 pm, from 10 pm to 150 pm, from 30 pm to 150 pm, from 50 pm to 150 pm, from 70 pm to 150 pm, from 90 pm to 150 pm, from 110 pm to 150 pm, from 130 pm to 150 pm, from 1 pm to 140 pm, from 1 pm to 120 pm, from 1 pm to 100 pm, from 1 pm to 80 pm, from 1 pm to 60 pm, from 1 pm to 40 pm, from 1 pm to 20 pm, or any range or combination of ranges formed from these endpoints. Without intending to be bound by theory, if the distance between adjacent damage tracks 120 on the damage track line 112 is too great, then after the glass-based substrate is etched the linear depression of the fiducial mark may have a cusped or otherwise uneven edge. In some cases, if the distance between adjacent damage tracks 120 on the damage track line 112 is too great, then a linear depression may not form. For example, in such cases, a plurality of discrete circles may form along the damage track line instead of a linear depression.

[0041] In one or more embodiments, step 210 may comprise contacting the glass-based substrate 100 with an etchant to remove at least a portion of the glass-based substrate along the damage track line 112 to form the fiducial mark 130 comprising a linear depression in the first major surface 102 of the glass-based substrate 100. A fiducial mark may be used for alignment purposes. For example, fiducial marks may be used to align electrical components with features on the glass-based substrate, such as through-glass vias. Fiducial marks described herein may be recognized by computerized systems. Without intending to be bound by theory, a computerized vision system may recognize the contrast between the linear depression of the fiducial mark and the surface of the glass-based substrate. Once the computerized system has recognized the fiducial mark, the computerized system may use that fiducial mark as a reference relative to the position of other features on the glass-based substrate. Improving the accuracy of alignment between the fiducial mark and other

[0042] In one or more embodiments, the linear depression of the fiducial mark 130 may comprise one or more straight portions. In one or more embodiments, the linear depression of thefiducial mark 130 may comprise one or more curved portions. In one or more embodiments, the linear depression of the fiducial mark 130 may comprise both one or more curved portions and one or more straight portions. In some embodiments, the linear depression of the fiducial mark 130 may form a closed shape on the first surface 102 of the glass-based substrate 100. For example, the linear depression of the fiducial mark 130 may form a circle, oval, ellipse, triangle, rectangle, or other polygon, a cross, or any other symmetrical or asymmetrical closed shape on the first major surface 102 of the glass-based substrate. In one or more embodiments, the linear depression of the fiducial mark 130 may form a circle or a cross. For example, referring now to FIG. 4, the glass-based substrate 100 may comprise a linear depression of the fiducial mark 130 in first major surface 102. The linear depression of the fiducial mark 130 comprises a curved portion, and the linear depression of the fiducial mark 130 forms a circle.

[0043] Referring again to FIG. IB, in one or more embodiments, the linear depression of the fiducial mark 130 may have a width 136 from 5 pm to 500 pm. As described herein, a “width” of the linear depression of the fiducial mark 130 refers to an average distance between a first edge 132 and a second edge 134 of the linear depression of the fiducial mark 130 at the first surface 102 of the glass-based substrate 100 For example, the linear depression of the fiducial mark 130 may have a width 136 from 5 pm to 500 pm, from 25 pm to 500 pm, from 50 pm to 500 pm, from 75 pm to 500 pm, from 100 pm to 500 pm, from 125 pm to 500 pm, from 150 pm to 500 pm, from 175 pm to 500 pm, from 200 pm to 500 pm, from 225 pm to 500 pm, from 250 pm to 500 pm, from 275 pm to 500 pm, from 300 pm to 500 pm, from 325 pm to 500 pm, from 350 pm to 500 pm, from 375 pm to 500 pm, from 400 pm to 500 pm, from 425 pm to 500 pm, from 450 pm to 500 pm, from 475 pm to 500 pm, from 5 pm to 475 pm, from 5 pm to 450 pm, from 5 pm to 425 pm, from 5 pm to 400 pm, from 5 pm to 375 pm, from 5 pm to 350 pm, from 5 pm to 325 pm, from 5 pm to 300 pm, from 5 pm to 275 pm, from 5 pm to 250 pm, from 5 pm to 225 pm, from 5 pm to 200 pm, from 5 pm to 175 pm, from 5 pm to 150 pm, from 5 pm to 125 pm, from 5 pm to 100 pm, from 5 pm to 75 pm, from 5 pm to 50 pm, from 5 pm to 25 pm, or any range or combination of ranges formed from these endpoints.

[0044] In one or more embodiments, a diameter of the smallest circle circumscribing the fiducial mark 130 may be from 50 pm to 3000 pm. For example, the diameter of the smallest circle circumscribing the fiducial mark 130 may be from 50 pm to 3000 pm, from 200 pm to 3000 pm,from 400 pm to 3000 pm, from 600 pm to 3000 pm, from 800 pm to 3000 pm, from 1000 pm to 3000 pm, from 1200 pm to 3000 pm, from 1400 pm to 3000 pm, from 1600 pm to 3000 pm, from 1800 pm to 3000 pm, from 2000 pm to 3000 pm, from 2200 pm to 3000 pm, from 2400 pm to 3000 pm, from 2600 pm to 3000 pm, from 2800 pm to 3000 pm, from 50 pm to 2900 pm, from 50 pm to 2700 pm, from 50 pm to 2500 pm, from 50 pm to 2300 pm, from 50 pm to 2100 pm, from 50 pm to 1900 pm, from 50 pm to 1700 pm, from 50 pm to 1500 pm, from 50 pm to 1300 pm, from 50 pm to 1100 pm, from 50 pm to 900 pm, from 50 pm to 700 pm, from 50 pm to 500 pm, from 50 pm to 300 pm, from 50 pm to 100 pm, or any range or combination of ranges formed from these endpoints.

[0045] The glass-based substrate 100 may be contacted with the etchant by any suitable means. For example, the etchant may be sprayed onto the glass-based substrate 100 or the glassbased substrate 100 may be immersed in a bath of the etchant. In one or more embodiments, contacting the glass-based substrate 100 with the etchant comprises immersing the glass-based substrate 100 in the etchant. In one or more embodiments, contacting the glass-based substrate 100 with the etchant comprises spraying etchant onto the glass-based substrate 100.

[0046] In one or more embodiments, the etchant may comprise one or more strong acids. For example, the etchant may comprise one or more of hydrofluoric acid (HF), hydrochloric acid (HC1), hydrobromic acid (HBr), and nitric acid (HNO3). In one or more embodiments, the etchant may comprise hydrofluoric acid. In one or more embodiments, the etchant may comprise from 5 vol.% to 20 vol.% of the one or more strong acids based on the total volume of the etchant. For example, the etchant may comprise the one or more strong acids from 5 vol.% to 20 vol.%, from 10 vol.% to 20 vol.%, from 15 vol.% to 20 vol.%, from 5 vol.% to 15 vol.%, from 5 vol.% to 10 vol.%, or any range or combination of ranges formed from these endpoints.

[0047] In one or more embodiments, the etchant may comprise one or more strong bases. For example, the etchant may comprise one or more of lithium hydroxide (LiOH), sodium hydroxide (NaOH), potassium hydroxide (KOH), calcium hydroxide (Ca(OH)2), barium hydroxide (Ba(OH)2). In one or more embodiments, the etchant may comprise one or more of sodium hydroxide and potassium hydroxide. In one or more embodiments, the etchant may comprise from 20 vol.% to 50 vol.% of the one or more strong bases based on the total volume ofthe etchant. For example, the etchant may comprise the one or more strong bases from 20 vol.% to 50 vol.%, from 25 vol.% to 50 vol.%, from 30 vol.% to 50 vol.%, from 35 vol.% to 50 vol.%, from 40 vol.% to 50 vol.%, from 45 vol.% to 50 vol.%, from 20 vol.% to 45 vol.%, from 20 vol.% to 40 vol.%, from 20 vol.% to 35 vol.%, from 20 vol.% to 30 vol.%, from 20 vol.% to 25 vol.%, or any range or combination of ranges formed from these endpoints.

[0048] Contacting the glass-based substrate 100 with the etchant may occur for any period of time suitable for forming the fiducial mark 130. In one or more embodiments, contacting the glass-based substrate 100 with the etchant may occur for a time from 30 min. to 600 min. For example, without limitation contacting the glass-based substrate 100 with the etchant may occur for a time from 30 min. to 600 min., from 50 min. to 600 min., from 100 min. to 600 min., from 200 min. to 600 min., from 300 min. to 600 min., from 400 min. to 600 min., from 500 min. to 600 min., from 30 min. to 500 min., from 30 min. to 400 min., from 30 min. to 300 min., from 30 min. to 200 min., from 30 min. to 100 min., from 30 min. to 50 min., or any range or combination of ranges formed from these endpoints.

[0049] In one or more embodiments, the selectivity between etching the plurality of damage tracks 120 and the remainder of the glass-based substrate 100 may be from 10 to 1000. In other words, the plurality of damage tracks 120 may be etched at a rate that is from 10 to 1000 times greater than the rate at which the remainder of the glass-based substrate 100 is etched. For example, the selectivity between etching the plurality of damage tracks 120 and the remainder of the glass-based substrate 100 may be from 10 to 1000, from 100 to 1000, from 300 to 1000, from 500 to 1000, from 700 to 1000, from 900 to 1000, from 10 to 800, from 10 to 600, from 10 to 400, from 10 to 200, or any range or combination of ranges formed from these endpoints.

[0050] Referring now to FIG. 5, in one or more embodiments, the method may further comprise irradiating the glass-based substrate 100 with a laser beam 302a to form one or more damage tracks 160 extending from the first major surface 102 of the glass-based substrate 100 to the second major surface 104 of the glass-based substrate 100. Irradiating the glass-based substrate 100 to form one or more damage tracks 160 extending from the first major surface 102 of the glassbased substrate 100 to the second major surface 104 of the glass-based substrate may be achieved by the methods described hereinabove, except that the laser beam 302a may be focused into a laserbeam focal line 302c extending through the glass-based substrate 100 from the first major surface 102 of the glass-based substrate 100 to the second major surface 104 of the glass based substrate 100.

[0051] In one or more embodiments, irradiating the glass-based substrate 100 with a laser beam 302a to form one or more damage tracks 160 extending from the first major surface 102 of the glass-based substrate 100 to the second major surface 104 of the glass-based substrate 100 may occur before, after, or even during the step of irradiating the glass-based substrate 100 with a laser beam to form a plurality of damage tracks 120 that extend from the first major surface 102 of the glass-based substrate 100 into the glass-based substrate 100. In one or more embodiments, the one or more damage tracks 160 extending from the first major surface 102 of the glass-based substrate 100 to the second major surface 104 of the glass-based substrate 100 may be formed using the same laser apparatus that is used to form the plurality of damage tracks 120 that each extend from the first major surface 102 of the glass based substrate 100 into the glass based substrate 100. Without intending to be bound by theory, adjusting the relative position of the optics 306 to the glass-based substrate 100 may result in the laser beam focal line passing through the entirety of the glass-based substrate 100 to form damage tracks 160 or may result in the laser beam focal line passing through a portion of the glass based substrate 100 to form damage tracks 120. Forming the damage tracks 120 and the damage tracks 160 using the same laser while moving either the glassbased substrate or the laser relative to each other may improve the alignment between the damage tracks 120 and 160 because the glass-based substrate may not need to be transferred or reoriented while the damage tracks 120 and 160 are being formed.

[0052] Additionally, the methods described herein may be used to form both through-glass vias 170 and the fiducial mark 130 in the same etching step. Referring now to FIG. 6, the step of contacting the glass-based substrate 100 with the etchant may remove at least a portion of the glass-based substrate from the one or more damage tracks 160 extending from the first major surface 102 of the glass-based substrate 100 to a second major surface 104 of the glass-based substrate 100 to form one or more through-glass vias 170. In the same step of contacting the glassbased substrate 100 with the etchant, at least a portion of the glass-based substrate may be removed from the plurality of damage tracks 120 to form fiducial mark 130. Without intending to be bound by theory, forming the through-glass vias 170 and the fiducial mark 130 in the same etching stepmay result in improved the alignment of the through-glass vias 170 with the fiducial mark 130 relative to processes in which through-glass vias 170 are formed in a separate process from the fiducial mark 130.

[0053] According to one or more embodiments, methods for forming fiducial marks 130 may comprise forming a second fiducial mark on the second major surface 104 of the glass-based substrate 100. Referring now to FIG. 7, the method may include a step of irradiating the glassbased substrate 100 with a laser beam 302a to form a second plurality of damage tracks 180 that extend from the second major surface 104 of the glass-based substrate 100 into the glass-based substrate 100. In one or more embodiments, the laser beam 302a may be focused into a laser beam focal line 302d that extends through a portion of the glass-based substrate 100 from the second major surface 104 of the glass-based substrate 100 into the glass-based substrate 100. The optics 306 used to focus the laser beam 302a may be positioned facing the second major surface 104 of the glass-based substrate 100.

[0054] In one or more embodiments, the step of irradiating the glass-based substrate 100 with a laser beam 302a to from a second plurality of damage tracks 180 that extend from the second major surface 104 of the glass-based substrate 100 into the glass-based substrate 100 may occur before, after, or even during the step of irradiating the glass-based substrate 100 with a laser beam to form the plurality of damage tracks 120 that extend from the first major surface 102 of the glassbased substrate 100 into the glass-based substrate 100.

[0055] Each of the second plurality of damage tracks 180 may extend through less than or equal to 90 % of the thickness 110 of the glass-based substrate 100. For example, each of the second plurality of damage tracks 180 may extend through less than or equal to 90%, 80%, 70%, 60%, 50%, 40%, 20%, or even 10% of the glass-based substrate 100. In one or more embodiments, each of the second plurality of damage tracks 180 may extend through from 1% to 90% of the glass-based substrate 100. For example, each of the second plurality of damage tracks 180 may extend through from 1% to 90%, from 5% to 90%, from 15% to 90%, from 25% to 90%, from 35% to 90%, from 45% to 90%, from 55% to 90%, from 65% to 90%, from 75% to 90%, from 85% to 90%, from 1% to 80%, from 1% to 70%, from 1% to 60%, from 1% to 50%, from 1% to40%, from 1% to 30%, from 1% to 20%, from 1% to 10% of the glass-based substrate, or any range or combination of ranges formed from these endpoints.

[0056] Referring now to FIG. 8, the second plurality of damage tracks 180 may be arranged along a second damage track line 182. In one or more embodiments, the second damage track line 182 may comprise one or more straight portions. In some embodiments, the second damage track line 182 may comprise one or more curved portions. The second damage track line 182 may comprise both one or more curved portions and one or more straight portions. In one or more embodiments, the second damage track line 182 may form a closed shape on the second surface 104 of the glass-based substrate 100. For example, the second damage track line 182 may form a circle, oval, ellipse, triangle, rectangle, or other polygon, a cross, or any other symmetrical or asymmetrical closed shape. In some embodiments, the second damage track line 182 may form a circle or a cross.

[0057] In one or more embodiments, a distance 184 between adjacent damage tracks 180 on the second damage track line 182 may be from 1 pm to 150 pm. For example, a distance 184 between adjacent damage tracks 180 on the second damage track line 182 may be from 1 pm to 150 pm, from 10 pm to 150 pm, from 30 pm to 150 pm, from 50 pm to 150 pm, from 70 pm to 150 pm, from 90 pm to 150 pm, from 110 pm to 150 pm, from 130 pm to 150 pm, from 1 pm to 140 pm, from 1 pm to 120 pm, from 1 pm to 100 pm, from 1 pm to 80 pm, from 1 pm to 60 pm, from 1 pm to 40 pm, from 1 pm to 20 pm, or any range or combination of ranges formed from these endpoints.

[0058] Referring now to FIG. 9, the contacting the glass-based substrate 100 with the etchant, as described hereinabove, may remove at least a portion of the glass-based substrate along the second damage track line 182 to from a second fiducial mark 190 comprising a second linear depression in to the second major surface 104 of the glass-based substrate 100. In one or more embodiments, the second fiducial mark 190 may be aligned with the first fiducial mark 130, such that the first fiducial mark 130 and the second fiducial mark 190 have substantially the same shape and position on the first major surface 102 and the second major surface 104 of the glass-based substrate 100 respectively. Without intending to be bound by theory, forming the first fiducial mark 130 and the second fiducial mark 190 during the same etching step may help improve thealignment between the first fiducial mark 130 and the second fiducial mark 190 on opposite surfaces of the glass-based substrate. In some embodiments, the second fiducial mark 190 may not be aligned with the first fiducial mark 130.

[0059] In one or more embodiments, a mask may be applied to at least a portion of the second major surface 104 of the glass-based substrate. The mask may be a thin film that is deposited onto the second major surface 104 of the glass-based substrate 100. The mask may comprise any material that is resistant to the etchant, such that portions of the second major surface 104 of the glass-based substrate 100 covered by the mask undergo less etching, or even no etching, relative to portions of the glass-based substrate 100 that are not covered by the mask. The mask may have one or more openings such that features may be etched into the second major surface 104 of the glass-based substrate 100. These features may include, but are not limited to, cavities, trenches, depressions, or even fiducial marks.

[0060] The mask may be applied at any point in the processes describe herein before the step of contacting the glass-based substrate with the etchant. In one or more embodiments, the mask may be applied to the second major surface 104 of the glass-based substrate 100 before the glass-based substrate 100 is irradiated with the laser beam. In such embodiments, the mask may comprise one or more openings through which the laser beam may irradiate the glass-based substrate to form damage tracks, including but not limited to the plurality damage tracks 120 extending from the first major surface 102 of the glass-based substrate 100 into the glass-based substrate to form fiducial marks 130, damage tracks 160 extending from the first major surface 102 to the second major surface 104 of the glass based substrate 100 to form through-glass vias 170, and damage tracks 180 extending from the second major surface 104 of the glass-based substrate 100 into the glass-based substrate 100 to form second fiducial marks 190. Without intending to be bound by theory, one or more embodiments of the methods described herein may be used to form fiducial marks in the glass-based substrate 100 without flipping the glass-based substrate 100, which may damage the mask.EXAMPLES

[0061] The embodiments described herein will be further clarified by the following examples.Example 1 - Forming a Fiducial Mark on a Glass-Based Substrate

[0062] A glass-based substrate was irradiated with a laser beam to form a plurality of damage tracks. FIG. 10 depicts an optical micrograph of a side view of the glass-based substrate including the plurality of damage tracks. The glass-based substrate had a thickness of 0.7 mm. The damage tracks were formed through about 300 pm from the back side of the glass-based substrate. The laser was incident the glass-based substrate from the front side of the glass-based substrate.

[0063] The laser beam and the glass-based substrate were moved relative to each other during the irradiation process to form a damage track line. FIG. 11A and 11B depict optical micrographs of the back side of the glass-based substrate. As shown in FIG. 11 A, the plurality of damage tracks are arranged in a circle. FIG. 1 IB shows an enlarged view of glass-based substrate to show discrete damage tracks in the glass-based substrate.

[0064] The glass-based substrate was immersed in an etchant comprising 10 vol.% HF for about 370 minutes. A total of about 150 pm of glass-based substrate was etched from the glassbased substrate, about 75 pm from the top side and about 75 pm from the back side of the glassbased substrate. Etching the glass-based substrate removed material from the damage tracks, forming linear depression in the glass-based substrate. FIG. 12 depicts an optical micrograph of the back side of the glass-based substrate after the etching. The etching process formed a circular fiducial mark, a glass circle, surrounded by the linear depression. The glass circle had a diameter of 1000 pm, and the linear depression extended out from the glass circle about 150 pm in each direction. The linear depression extended about 300 pm into the surface of the back side of the glass-based substrate.

[0065] The fiducial mark was tested using a Coming Laser Technology laser system to find and fit the circular fiducial. FIG. 13 depict a screen capture showing the fiducial mark being recognized and fitted to a circle by the computer software system. The computer system was also able to calculate the coordinates of the center of the fiducial mark. This verification step shows that the fiducial mark formed in the example was of sufficient quality (i.e., had sufficient, size, shape, and contrast) to be used in practice. Specifically, the fiducial mark was fit to a circle with a score of 99.95% by the software.

[0066] In a first aspect of the present disclosure, method for forming a fiducial mark on a glass-based substrate comprises irradiating the glass-based substrate with a laser beam to form a plurality of damage tracks that each extend from a first major surface of the glass-based substrate into the glass-based substrate, wherein each damage track comprises a plurality of voids in the glass-based substrate, wherein each damage track extends through less than or equal to 90 % of a thickness of the glass-based substrate, and wherein the plurality of damage tracks are arranged along a damage track line and are spaced apart by a distance from 1 pm to 150 pm along the first surface of the glass-based substrate; and contacting the glass-based substrate with an etchant to remove at least a portion of the glass-based substrate along the damage track line to form the fiducial mark comprising a linear depression in the first major surface of the glass-based substrate.

[0067] A second aspect of the present disclosure may include the first aspect, wherein the damage track line forms a closed shape on the first surface of the glass-based substrate.

[0068] A third aspect of the present disclosure may include either the first or second aspect, wherein the linear depression of the fiducial mark forms a closed shape on the first surface of the glass-based substrate.

[0069] A fourth aspect of the present disclosure may include any of the first through third aspects, wherein the damage track line is curved.

[0070] A fifth aspect of the present disclosure may include any of the first through fourth aspects, wherein the linear depression of the fiducial mark is curved.

[0071] A sixth aspect of the present disclosure may include any of the first through fifth aspects, wherein each damage track is substantially perpendicular to the first major surface of the glass-based substrate.

[0072] A seventh aspect of the present disclosure may include any of the first through sixth aspects, wherein a diameter of a smallest circle circumscribing the fiducial mark is from 50 pm to 3000 pm.

[0073] An eighth aspect of the present disclosure may include any of the first through seventh aspects, wherein the linear depression has a width from 5 pm to 300 pm.

[0074] A ninth aspect of the present disclosure may include any of the first through eighth aspects, wherein the glass-based substrate has a thickness from 20 pm to 2000 pm.

[0075] A tenth aspect of the present disclosure may include any of the first through ninth aspects, wherein the laser beam is focused into a laser beam focal line extending through a portion of the glass-based substrate from the first major surface of the glass-based substrate.

[0076] An eleventh aspect of the present disclosure may include any of the first through tenth aspects, wherein the laser beam is pulsed for a duration from 50 fs to 20 ps.

[0077] A twelfth aspect of the present disclosure may include any of the first through eleventh aspects, wherein the laser beam has a wavelength from 300 nm to 2000 nm.

[0078] A thirteenth aspect of the present disclosure may include any of the first through twelfth aspects, wherein each of the plurality of voids of the damage track has a diameter of less than or equal to 2 pm.

[0079] A fourteenth aspect of the present disclosure may include any of the first through thirteenth aspects, wherein the etchant comprises one or more strong acids.

[0080] A fifteenth aspect of the present disclosure may include any of the first through thirteenth aspects, wherein the etchant comprises or one or more strong bases.

[0081] A sixteenth aspect of the present disclosure may include any of the first through fifteenth aspects, wherein the contacting the glass-based substrate with an etchant comprises immersing the glass-based substrate in the etchant.

[0082] A seventeenth aspect of the present disclosure may include any of the first through fifteenth aspects, wherein the contacting the glass-based substrate with the etchant comprises spraying etchant onto the glass-based substrate.

[0083] An eighteenth aspect of the present disclosure may include any of the first through seventeenth aspects, wherein the method further comprises irradiating the glass-based substrate with a laser beam to form one or more damage tracks extending from the first major surface of the glass-based substrate to a second major surface of the glass-based substrate, wherein the contactingof the glass-based substrate with the etchant removes at least a portion of the glass-based substrate from the one or more damage tracks extending from the first major surface of the glass-based substrate to a second major surface of the glass-based substrate to form one or more through glass vias.

[0084] A nineteenth aspect of the present disclosure may include any of the first through eighteenth aspects, wherein the method further comprises irradiating the glass-based substrate with a laser beam to form a second plurality of damage tracks that extend from a second major surface of the glass-based substrate into the glass-based substrate, wherein each of the second plurality of damage tracks extends through less than or equal to 90% of the thickness of the glass-based substrate, wherein the second plurality of damage tracks are arranged along a second damage track line and are spaced apart by a distance from 1 pm to 150 pm, wherein the contacting of the glassbased substrate with the etchant removes at least a portion of the glass-based substrate along the second damage track line to form a second fiducial mark comprising a second linear depression into the second major surface of the glass-based substrate.

[0085] A twentieth aspect of the present disclosure may include the nineteenth aspect, wherein the fiducial mark and the second fiducial mark are substantially opposite each other on the glass-based substrate.

[0086] The present disclosure is directed to various embodiments of methods for forming a fiducial mark on a glass-based substrate. The methods may comprise irradiating the glass-based substrate with a laser beam to form a plurality of damage tracks that each extend from a first major surface of the glass-based substrate into the glass-based substrate. Each damage track may comprise a plurality of voids in the glass-based substrate and each damage track may extend through less than or equal to 90 % of a thickness of the glass-based substrate. The plurality of damage tracks may be arranged along a damage track line and may be spaced apart by a distance from 1 pm to 150 pm along the first surface of the glass-based substrate. The methods may further comprise contacting the glass-based substrate with an etchant to remove at least a portion of the glass-based substrate along the damage track line to form the fiducial mark comprising a linear depression in the first major surface of the glass-based substrate. The fiducial marks may be usedto align electrical components with the glass-based substrate or features on the glass-based substrate, such as through-glass vias.

[0087] It will be apparent to those skilled in the art that various modifications and variations can be made to the embodiments described herein without departing from the spirit and scope of the claimed subject matter. Thus, it is intended that the specification cover the modifications and variations of the various embodiments described herein provided such modification and variations come within the scope of the appended claims and their equivalents.

Claims

CLAIMS1. A method for forming a fiducial mark on a glass-based substrate, the method comprising: irradiating the glass-based substrate with a laser beam to form a plurality of damage tracks that each extend from a first major surface of the glass-based substrate into the glass-based substrate, wherein each damage track comprises a plurality of voids in the glass-based substrate, wherein each damage track extends through less than or equal to 90 % of a thickness of the glass-based substrate, and wherein the plurality of damage tracks are arranged along a damage track line and are spaced apart by a distance from 1 pm to 150 pm along the first surface of the glass-based substrate; and contacting the glass-based substrate with an etchant to remove at least a portion of the glass-based substrate along the damage track line to form the fiducial mark comprising a linear depression in the first major surface of the glass-based substrate.

2. The method of claim 1 , wherein the damage track line forms a closed shape on the first surface of the glass-based substrate.

3. The method of claim 1 or 2, wherein the linear depression of the fiducial mark forms a closed shape on the first surface of the glass-based substrate.

4. The method of any one of claims 1 to 3, wherein the damage track line is curved.

5. The method of any one of claims 1 to 4, wherein the linear depression of the fiducial mark is curved.

6. The method of any one of claims 1 to 5, wherein each damage track is substantially perpendicular to the first major surface of the glass-based substrate.

7. The method of any one of claims 1 to 6, wherein a diameter of a smallest circle circumscribing the fiducial mark is from 50 pm to 3000 pm.

8. The method of any one of claims 1 to 7, wherein the linear depression has a width from 5 pm to 500 pm.

9. The method of any one of claims 1 to 8, wherein the glass-based substrate has a thickness from 20 pm to 2000 pm.

10. The method of any one of claims 1 to 9, wherein the laser beam is focused into a laser beam focal line extending through a portion of the glass-based substrate from the first major surface of the glass-based substrate.

11. The method of any one of claims 1 to 10, wherein the laser beam is pulsed for a duration from 50 fs to 20 ps.

12. The method of any one of claims 1 to 11, wherein the laser beam has a wavelength from300 nm to 2000 nm.

13. The method of any one of claims 1 to 12, wherein each of the plurality of voids of the damage track has a diameter of less than or equal to 2 pm.

14. The method of any one of claims 1 to 13, wherein the etchant comprises one or more strong acids.

15. The method of any one of claims 1 to 13, wherein the etchant comprises or one or more strong bases.

16. The method of any one of claims 1 to 15, wherein the contacting the glass-based substrate with an etchant comprises immersing the glass-based substrate in the etchant.

17. The method of any one of claims 1 to 15, wherein the contacting the glass-based substrate with the etchant comprises spraying etchant onto the glass-based substrate.

18. The method of any one of claims 1 to 17, the method further comprising: irradiating the glass-based substrate with a laser beam to form one or more damage tracks extending from the first major surface of the glass-based substrate to a second major surface of the glass-based substrate, wherein the contacting of the glass-based substrate with the etchant removes at least a portion of the glass-based substrate from the one or more damage tracks extending from the first major surface of the glass-based substrate to a second major surface of the glass-based substrate to form one or more through glass vias.

19. The method of any one of claims 1 to 18, the method further comprising: irradiating the glass-based substrate with a laser beam to form a second plurality of damage tracks that extend from a second major surface of the glass-based substrate into the glass-based substrate, wherein each of the second plurality of damage tracks extends through less than or equal to 90% of the thickness of the glass-based substrate, wherein the second plurality of damage tracks are arranged along a second damage track line and are spaced apart by a distance from 1 pm to 150 pm, wherein the contacting of the glass-based substrate with the etchant removes at least a portion of the glass-based substrate along the second damage track line to form a second fiducial mark comprising a second linear depression into the second major surface of the glass-based substrate.

20. The method of claim 19, wherein the fiducial mark and the second fiducial mark are substantially opposite each other on the glass-based substrate.

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