Methods for processing silica-containing substrate for filling vias with metal

Abstract

A method for processing a silica-containing substrate may include submerging a silica-containing substrate and a counter electrode into a metal ion-containing solution. The silica-containing substrate may include a first surface and a second surface opposite the first surface. The silica-containing substrate may include at least one via that spans from the first surface to the second surface. The method may further include filling at least one via of the silica-containing substrate with a metal by an electroplating process. The electroplating process may include flowing a first current between the first surface and the counter electrode, and flowing a second current between the second surface and the counter electrode. The first current may include a first pulse waveform. The second current may include a second pulse waveform. The first pulse waveform may be different than the second pulse waveform. The entirety of the via may be filled with conductive metal while the first current and the second current are flowed.

Description

METHODS FOR PROCESSING SILICA-CONTAINING SUBSTRATE FOR FILLING VIAS WITHMETALCROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of priority to U.S. Provisional Patent Application No. 63 / 599,022 filed on November 15, 2023, the content of which is incorporated herein by reference in its entirety for all purposes.BACKGROUNDField

[0002] The present disclosure generally relates to silica-containing substrates with vias and, more particularly, to methods for filling such vias with metal.Technical Background

[0003] Substrates, such as silicon, have been used as an interposer disposed between electrical components (e.g., printed circuit boards, integrated circuits, and the like). Metalized through-substrate vias provide a path through the interposer for electrical signals to pass between opposite sides of the interposer. Glass substrates are attractive materials that are highly advantageous for electrical signal transmission, as they have excellent thermal dimensional stability due to a low coefficient of thermal expansion (CTE), as well as very good low electrical loss at high frequencies electrical performance, and the possibility of being formed at thickness as well as at large panel sizes. In particular, high silica content substrates, such as fused silica, are even more attractive then generic glasses, as the CTE of fused silica can be extremely low (~0.5ppm / deg C), and the electrical loss tangent can be even lower than in glasses that often contain significant fractions of non-silica material. However, through-via formation and metallization in high silica content substrates presents significant challenges.SUMMARY

[0004] According to one or more embodiments of the present disclosure, a method for processing a silica-containing substrate may comprise submerging a silica-containing substrate and a counter electrode into a metal ion-containing solution. The silica-containing substrate may comprise a first surface and a second surface opposite the first surface. The silica-containing substrate may comprise at least one via that spans from the first surface to the second surface. The method may further comprise filling at least one via of the silica-containing substrate with a metal by an electroplating process. The electroplating process may comprise flowing a first current between the first surface and the counter electrode, and flowing a second current between the second surface and the counter electrode. The first current may comprise a first pulse waveform. The second current may comprise a second pulse waveform. The first pulse waveform may be different from the second pulse waveform. The entirety of the via may be filled with conductive metal while the first current and the second current are flowed.

[0005] Additional features and advantages of the embodiments 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.

[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] The embodiments set forth in the drawings are illustrative and exemplary in nature and are 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:

[0008] FIG. 1 schematically depicts a partial perspective view of a silica-containing substrate, according to one or more embodiments described and illustrated herein;

[0009] FIG. 2 schematically depicts a system for processing silica-containing substrate for filling vias with metal, according to one or more embodiments described and illustrated herein;

[0010] FIG. 3 schematically depicts an example of a first current including a first pulse waveform and a second current including a second pulse waveform, according to one or more embodiments described and illustrated herein;

[0011] FIG. 4 schematically depicts another example of a first current including a first pulse waveform and a second current including a second pulse waveform, according to one or more embodiments described and illustrated herein;

[0012] FIG. 5 schematically depicts an example of a first current including a first pulse waveform and a third pulse waveform and a second current including a second pulse waveform and a fourth waveform, according to one or more embodiments described and illustrated herein;

[0013] FIG. 6 depicts specifications of the first current and the second current used for Comparative Examples 1-3 and Examples 4-9;

[0014] FIG. 7 depicts specifications of the first current and the second current used for Examples 10-12;

[0015] FIG. 8A shows a X-section photo of Comparative Example 1 ; and

[0016] FIGS. 8B and 8C show an X-section photo of Example 15.

[0017] Reference will now be made in greater detail to various embodiments of the present disclosure, some embodiments 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 similar parts.DETAILED DESCRIPTION

[0018] A need exists for alternative methods of filling vias with metal. Embodiments of the present disclosure meet this need by processing silica-containing substrates, as described herein. In one or more embodiments, the presently described processes produce silica- containing substrates that include a plurality of vias filled with conductive metal. The plurality of vias may be entirely filled with the conductive metal by flowing a first current and a secondcurrent having different pulse waveforms. By this process, as described in detail herein, the vias can be completely fdled without voids, which may occur utilizing conventional methods. For example, conventional embodiments for filling vias may utilize identical waveforms in the first current and second current. Without being bound by theory, by utilizing the first current and second current with different waveforms, the following four kinds of reactions may occur repeatedly to entirely fill the via with conductive metal: plating the metal on the one side of the substrate and etching the other side of the substrate; plating the metal on the one side of the substrate and plating the metal on the other side of the substrate; etching the one side of the substrate and plating the metal on the other side of the substrate; and etching one side of the substrate and etching the other side of the substrate. These reactions may occur repeatedly over a short period of time and throughout the whole electroplating process, and thereby the entirety of the via is filled by the metal, according to one or more embodiments described herein.

[0019] Referring generally to the figures, embodiments of the present disclosure are generally related to methods for forming silica-containing substrates having vias (e.g., holes) that are partially or fully filled with metal. Such articles may be for use in semiconductor devices, radio-frequency (RF) devices (e.g., antennae, electronic switches, and the like), interposer devices, microelectronic devices, optoelectronic devices, microelectronic mechanical system (MEMS) devices and other applications where vias may be leveraged.

[0020] In general, and as described in detail herein, vias may be filled by an electroplating process wherein electrically conductive material (e.g., copper) is deposited on the sidewalls of the via and continuously built up until the via is hermetically sealed. Electroplating vias can be challenging as the vias may become hermetically sealed prior to the entire space of the via being filled with metal. Such scenarios can lead to voids within the metal in the via, which is not generally desirable. Conventional processing has attempted to mitigate this problem by utilizing vias having an hourglass shape (i.e., having a narrow waist that provides a metal “bridge” for the electrically conductive material to be initially deposited). However, forming vias that are cylindrically shaped may be easier to form and more desirable.

[0021] The present embodiments utilize electroplating with the metal through providing a first current and a second current. The second current is different from the first current. In some such embodiments, vias that are substantially cylindrical in shaped may be fully filled by metals.

[0022] As described herein, embodiments of the present disclosure are also generally related to methods for fdling vias in silica-containing substrates with metals. Silica-containing substrates include glass and glass-ceramics. As used herein, the term “silica-containing substrate” may, in some embodiments, refer to silica-containing substrates comprises a silica (SiCh) content greater than or equal to 75 mol%, greater than or equal to 80 mol%, greater than or equal to 85 mol%, greater than or equal to 90 mol%, greater than or equal to 91 mol%, greater than or equal to 92 mol%, greater than or equal to 93 mol%, greater than or equal to 94 mol%, greater than or equal to 95 mol%, greater than or equal to 96 mol%, greater than or equal to 97 mol%, greater than or equal to 98 mol%, greater than or equal to 99 mol%, or greater than or equal to 99.9 mol%. In some embodiments, the silica-containing substrate may be fused silica. Example silica-containing substrates include, but are not limited to, HPFS® fused silica sold by Coming Incorporated of Coming, New York under glass codes 7980, 7979, and 8655. In one example, the silica-containing substrate is a substrate comprising unintentionally doped silica. The phrase “unintentionally doped” means that no additional ingredients are intentionally added to the silica prior to melting the silica.

[0023] According to additional embodiments, the silica-containing substrates described herein may have less than 75 mol% silica. For example, the methods described herein may also be utilized on glass or glass-ceramic substrates having less than 75 mol% silica (SiCh), such as Eagle XG® glass and Gorilla ® Glass sold by Coming Incorporated.

[0024] Properties of silica make it a desirable substrate as an interposer in electronic devices. The term “interposer” generally refers to any structure that extends or completes an electrical connection through the structure, for example but not limited to, between two or more electronic devices disposed on opposite surfaces of the interposer. The two or more electronic devices may be co-located in a single structure or may be located adjacent to one another in different structures such that the interposer functions as a portion of an interconnect nodule or the like. As such, the interposer may contain one or more active areas in which vias and other interconnect conductors (such as, for example, power, ground, and signal conductors) are present and formed. The interposer may also include one or more active areas in which blind vias are present and formed. When the interposer is formed with other components, such as dies, underfill materials, encapsulants, and / or the like, the interposer may be referred to as an interposer assembly. Also, the term “interposer” may further include a plurality of interposers, such as an array of interposers or the like.

[0025] The low coefficient of thermal expansion (CTE) of silica minimizes expansion and movement of the silica-containing substrate due to the application of heat flux, such as heat flux generated by a semiconductor device that is coupled to the silica-containing substrate acting as an interposer. Expansion of the interposer due to CTE mismatch between the interposer and a semiconductor device (or other electronic component) may cause the bond between the interposer and the semiconductor to fail and result in separation or other damage.

[0026] Additionally, silica-containing substrates provide desirable RF properties over other substrates such as silicon. Desirable RF properties may be important in high frequency applications, such as high-speed data communications applications.

[0027] Thus, silica-containing substrates comprising greater than or equal to 75 mol%, 80 mol%, 85 mol%, 90 mol%, 95 mol%, or 99 mol% silica (SiCh) may be a desired material in an interposer in particular electronics devices.

[0028] According to some embodiments, laser-damage-and-etch techniques may be utilized to form vias in silica-containing materials. For example, laser-damage-and-etch techniques used to form vias within silica-containing substrates may result in substantially cylindrical vias (i.e., vias with substantially straight walls) or those with hourglass shapes as described in US 17 / 320,646. An hourglass-shaped via has a narrow waist having a diameter that is less than a diameter of openings at the surfaces of the interposer. Other methods for forming vias are contemplated as suitable herein, such as mechanical boring, etc., and the method for forming the vias is not necessarily limiting on the methods described herein of filling such vias with metal.

[0029] Referring now to FIG. 1, an example article comprising a silica-containing substrate 100 is schematically depicted in a partial perspective view. The silica-containing substrate 100 may comprise a first surface 102 and a second surface 104 opposite from the first surface 102. A plurality of vias 110 extends through the bulk of the silica-containing substrate 100 from the first surface 102 to the second surface 104. It should be understood that any number of vias 110 may extend through the silica-containing substrate 100 in any arrangement. The thickness t of the silica-containing substrate 100 may be any appropriate thickness depending on the application. As non-limiting examples, the thicknesses t of the silica-containing substrate is within the range of 50 pm and 1 mm including endpoints, within a range of 100 pm and 700 pm including endpoints, within a range of 100 pm and 500 pm including endpoints, or withina range of 250 pm to 500 pm including endpoints.

[0030] A pitch of the vias 110, which is the center-to-center spacing between adjacent vias 110, may be any dimension according to the desired application, such as, without limitation, about 10 pm to about 2,000 pm, including about 10 pm, about 50 pm, about 100 pm, about 250 pm, about 1,000 pm, about 2,000 pm, or any amplitude or range between any two of these amplitudes (including endpoints). In some embodiments, the pitch may vary between vias 110 on the same silica-containing substrate 100 (i.e., the pitch between a first via and a second via may be different from a pitch between the first via and a third via). In some embodiments, the pitch may be a range, such as about 10 pm to about 100 pm, about 25 pm to about 500 pm, about 10 pm to about 1,000 pm, or about 250 pm to about 2,000 pm.

[0031] Referring now to FIG. 2, a system 10 includes the silica-containing substrate 100, a counter electrode 210 220, a metal -ion containing solution 300, a first rectifier 410, and a second rectifier 420. The silica-containing substrate 100 and a counter electrode 210 220 are submerged into a metal ion-containing solution 300. The first surface 102 may be connected with the counter electrode 210. The second surface 104 may be connected with the counter electrode 220. In embodiments, the silica-containing substrate 100 may be an interposer of counter electrode 210 220. The silica-containing substrate 100 includes a plurality ofmetalized vias 110 that electrically couple to the counter electrode 210 220 such that electrical signals and / or electrical power may pass there between. While FIG. 2 describes that two counter electrodes 210 220, one counter electrode or more than two electrodes can be provided to provide a first current and a second current.

[0032] The metal ion-containing solution 300 may comprise a metal. In embodiments, the metal may comprise copper, silver, aluminum, titanium, gold, platinum, nickel, tungsten, magnesium, or combinations thereof. In some embodiments, the metal is copper.

[0033] Still referring to FIG. 2, the counter electrode 210 and the first surface 102 may be connected with a first rectifier 410. The first rectifier 410 may flow a first current to the first surface 102. The first rectifier 410 may convert an oscillating two-directional alternating current (AC) into a single-directional direct current (DC).

[0034] The counter electrode 220 and the second surface 104 may be connected with a second rectifier 420. The second rectifier 420 may flow a second current to the second surface104. The second rectifier 420 may convert an oscillating two-directional AC into a singledirectional direct current DC.

[0035] In embodiments, the first current and the second current may be provided from 1 minute to 120 minutes, from 2 minutes to 120 minutes, from 5 minutes to 120 minutes, from 10 minutes to 120 minutes, from 15 minutes to 120 minutes, from 20 minutes to 120 minutes, from 25 minutes to 120 minutes, from 30 minutes to 120 minutes, from 1 minute to 100 minutes, from 2 minutes to 100 minutes, from 5 minutes to 100 minutes, from 10 minutes to 100 minutes, from 15 minutes to 100 minutes, from 20 minutes to 100 minutes, from 25 minutes to 100 minutes, from 30 minutes to 100 minutes, from 1 minute to 90 minutes, from 2 minutes to 90 minutes, from 5 minutes to 90 minutes, from 10 minutes to 90 minutes, from 15 minutes to 90 minutes, from 20 minutes to 90 minutes, from 25 minutes to 90 minutes, from 30 minutes to 90 minutes, from 1 minute to 80 minutes, from 2 minutes to 80 minutes, from 5 minutes to 80 minutes, from 10 minutes to 80 minutes, from 15 minutes to 80 minutes, from 20 minutes to 80 minutes, from 25 minutes to 80 minutes, from 30 minutes to 80 minutes, from1 minute to 70 minutes, from 2 minutes to 70 minutes, from 5 minutes to 70 minutes, from 10 minutes to 70 minutes, from 15 minutes to 70 minutes, from 20 minutes to 70 minutes, from 25 minutes to 70 minutes, from 30 minutes to 70 minutes, from 1 minute to 60 minutes, from2 minutes to 60 minutes, from 5 minutes to 60 minutes, from 10 minutes to 60 minutes, from 15 minutes to 60 minutes, from 20 minutes to 60 minutes, from 25 minutes to 60 minutes, from 30 minutes to 60 minutes, any and all sub-ranges formed from any of these endpoints.

[0036] Still referring to FIG. 2, the metal ion-containing solution may be provided on the first surface 102 and the second surface 104 by a nozzle 510 520. In embodiments, additional metal ion-containing solution may be sprayed on the first surface 102 and the second surface 104 by a nozzle 510 520. While FIG. 2 describes that two nozzles 510 520, one nozzle or more than two nozzles can be provided to provide additional metal ion-containing solution on the first surface 102 and the second surface 104.

[0037] In embodiments, a flow rate of the metal ion-containing solution provided by the nozzle 510 520 may be from 0. 1 Liter Per Minute (L / min) to 3.0 L / min, from 0.2 L / min to 3.0 L / min, from 0.3 L / min to 3.0 L / min, from 0.5 L / min to 3.0 L / min, from 0.7 L / min to 3.0 L / min, from 1.0 L / min to 3.0 L / min, from 1.05 L / min to 3.0 L / min, from 0.1 L / min to 2.5 L / min, from 0.2 L / min to 2.5 L / min, from 0.3 L / min to 2.5 L / min, from 0.5 L / min to 2.5 L / min, from 0.7L / min to 2.5 L / min, from 1.0 L / min to 2.5 L / min, from 1.05 L / min to 2.5 L / min, from 0.1 L / min to 2.0 L / min, from 0.2 L / min to 2.0 L / min, from 0.3 L / min to 2.0 L / min, from 0.5 L / min to 2.0 L / min, from 0.7 L / min to 2.0 L / min, from 1.0 L / min to 2.0 L / min, from 1.05 L / min to 2.0 L / min, from 0.1 L / min to 1.5 L / min, from 0.2 L / min to 1.5 L / min, from 0.3 L / min to 1.5 L / min, from 0.5 L / min to 1.5 L / min, from 0.7 L / min to 1.5 L / min, from 1.0 L / min to 1.5 L / min, from 1.05 L / min to 1.5 L / min, from 0.1 L / min to 1.15 L / min, from 0.2 L / min to 1.15 L / min, from 0.3 L / min to 1.15 L / min, from 0.5 L / min to 1.15 L / min, from 0.7 L / min to 1.15 L / min, from 1.0 L / min to 1.15 L / min, from 1.05 L / min to 1.15 L / min, or any and all sub-ranges formed from any of these endpoints.

[0038] Referring now to FIG. 3, an example first pulse waveform 610 and second pulse waveform 620 are depicted. The first current may comprise a first pulse waveform 610. In embodiments, the first pulse waveform 610 may comprise a sine waveform, a triangle waveform, a square waveform, a sawtooth waveform, or combinations thereof. In embodiments, the first pulse waveform 610 may comprise a square waveform. The second current may comprise a second pulse waveform 620. In embodiments, the second pulse waveform 620 may comprise a sine waveform, a triangle waveform, a square waveform, a sawtooth waveform, or combinations thereof. In embodiments, the second pulse waveform 620 may comprise a square waveform.

[0039] According to embodiments, the second pulse waveform 620 is different from the first pulse waveform 610. The first pulse waveform 610 may comprise a positive current portion 615 and a negative current portion 616. The second pulse waveform 620 may also comprise a positive current portion 625 and a negative current portion 626, but not identical to that of the first pulse waveform 610. Additionally, the first pulse waveform 610 may comprise a first current period segment 611 and a second current period segment 612, adding up to a full period. The second pulse waveform 620 may comprise a first current period segment 621 and a second current period segment 622, adding up to a full period.

[0040] The first current period segment 611 of the first pulse waveform 610 may have a different length of time than the second current period segment 612 of the first pulse waveform 610. The first current period segment 611 of the first pulse waveform 610 may have a longer length of time than the second current period segment 612 of the first pulse waveform 610.

[0041] The first current period segment 621 of the second pulse waveform 620 may have adifferent length of time than the second current period segment 622 of the second pulse waveform 620. The first current period segment 621 of the second pulse waveform 620 may have a longer length of time than the second current period segment 622 of the second pulse waveform 620.

[0042] By flowing the first pulse waveform 610 and the second pulse waveform 620, the following four (4) kinds of reactions may occur repeatedly to fill the via with conductive metal. When the first pulse waveform 610 is a positive current and the second pulse waveform 620 is a positive current, the metal may be plated on or near the first surface 102 and a second surface 104 to fill the via 110 at the same time. When the first pulse waveform 610 is a positive current and the second pulse waveform 620 is a negative current, the metal may be plated on or near the first surface 102 to fill the via 110, and the metal on or near the second surface 104 may be etched at the same time . When the first pulse waveform 610 is a negative current and the second pulse waveform 620 is a positive current, the metal on or near the first surface 102 may be etched, and the metal may be plated on or near the second surface 104 to fill the via 110 at the same time. When the first pulse waveform 610 is a negative current and the second pulse waveform 620 is a negative current, the metal on or near the first surface 102 may be etched, and the metal on or near the second surface 104 may be etched at the same time . These reactions occur repeatedly over a short period of time and throughout the whole electroplating process, and thereby the entirety of the via 110 is filled by the metal.

[0043] The first current period segment 611 of the first pulse waveform 610 may be a positive current and comprise a first amplitude 610A. The second current period segment 612 of the first pulse waveform 610 may be a negative current and comprise a second amplitude 610B. The first current period segment 621 of the second pulse waveform 620 may be a positive current and comprise a first amplitude 620A. The second current period segment 622 of the second pulse waveform 620 may be a negative current and comprise a second amplitude 620B.

[0044] In embodiments, a ratio of the first amplitude 610A of the first pulse waveform 610 to the second amplitude 610B of the first pulse waveform 610, a ratio of the first amplitude 620A of the second pulse waveform 620 to the second amplitude 620B of the second pulse waveform 620, or both, may be from 1 : 1 to 1: 10, from 1 :2 to 1: 10, from 1 : 3 to 1: 10, from 1 : 1 to 1:8, from 1:2 to 1:8, from 1:3 to 1:8, from 1: 1 to 1:6, from 1:2 to 1:6, from 1:3 to 1:6, from 1 : 1 to 1:5, from 1 : 2 to 1:5, from 1 : 3 to 1 : 5 , or any and all sub-ranges formed from any of theseendpoints. In some embodiments, the first amplitude 610A of the first pulse waveform 610 may be less than the second amplitude 61 OB of the first pulse waveform 610. In some embodiments, the first amplitude 620A of the second pulse waveform 620 may be less than the second amplitude 620B of the second pulse waveform 620.

[0045] In embodiments, a ratio of time period of the first current period segment 611 of the first pulse waveform 610 to time period of the second current period segment 612 of the first pulse waveform 610, a ratio of time period of the first current period segment 621 of the second pulse waveform 620 to time period of the second current period segment 622 of the second pulse waveform 620, or both, may be 20 milliseconds: 1 millisecond to 10 milliseconds, 25: 1 to 10, 30: 1 to 10, 35: 1 to 10, 40: 1 to 10, 45: 1 to 10, 50: 1 to 10, 55: 1 to 10, 60: 1 to 10, 65: 1 to 10, 70: 1 to 10, 75: 1 to 10, 80: 1 to 10, 20: 1 to 8, 25: 1 to 8, 30: 1 to 8, 35: 1 to 8, 40: 1 to 8, 45: 1 to 8, 50: 1 to 8, 55: 1 to 8, 60: 1 to 8, 65: 1 to 8, 70: 1 to 8, 75: 1 to 8, 80: 1 to 8, 20: 1 to 6, 25: 1 to 6, 30: 1 to 6, 35: 1 to 6, 40: 1 to 6, 45: 1 to 6, 50: 1 to 6, 55: 1 to 6, 60: 1 to 6, 65: 1 to 6, 70: 1 to 6, 75: 1 to 6, 80: 1 to 6, 20: 1 to 4, 25: 1 to 4, 30: 1 to 4, 35: 1 to 4, 40: 1 to 4, 45: 1 to 4, 50: 1 to 4, 55: 1 to 4, 60: 1 to 4, 65: 1 to 4, 70: 1 to 4, 75: 1 to 4, 80: 1 to 4, 20: 2, 25: 2, 30: 2, 35: 2, 40: 2, 45: 2, 50: 2, 55: 2, 60: 2, 65: 2, 70: 2, 75: 2, 80: 2, or any and all subranges formed from any of these endpoints.

[0046] In embodiments, a current density of the first current and a current density of the second current may be from 0.1 amps per square decimeter (ASD) to 3 ASD, 0.15 ASD to 3 ASD, 0.2 ASD to 3 ASD, 0.25 ASD to 3 ASD, 0.1 ASD to 2.5 ASD, 0.15 ASD to 2.5 ASD, 0.2 ASD to 2.5 ASD, 0.25 ASD to 2.5 ASD, 0.1 ASD to 2 ASD, 0. 15 ASD to 2 ASD, 0.2 ASD to 2 ASD, 0.25 ASD to 2 ASD, 0.1 ASD to 1.5 ASD, 0.15 ASD to 1.5 ASD, 0.2 ASD to 1.5 ASD, 0.25 ASD to 1.5 ASD, 0.1 ASD to 1 ASD, 0.15 ASD to 1 ASD, 0.2 ASD to 1 ASD, 0.25 ASD to 1 ASD, or any and all sub-ranges formed from any of these endpoints.

[0047] Referring now to FIG. 4, another example first pulse waveform 610 and second pulse waveform 620 are depicted. In one or more embodiments, the first pulse waveform 610 may further comprise a third current period segment 613, adding up to a full period. The third current period segment 613 may comprises a third amplitude 610C. The second pulse waveform 620 may further comprise a third current period segment 623, adding up to a full period. The third current period segment 623 may comprise a third amplitude 620C.

[0048] The third amplitude 610C of the first pulse waveform 610 may be greater than thefirst amplitude 610A of the first pulse waveform 610. The second amplitude 61 OB of the first pulse waveform 610 may be greater than the first amplitude 610A of the first pulse waveform 610. The second amplitude 61 OB of the first pulse waveform 610 may be lesser than the third amplitude 610C of the first pulse waveform 610.

[0049] The third amplitude 620C of the second pulse waveform 620 may be greater than the first amplitude 620A of the second pulse waveform 620. The second amplitude 620B of the second pulse waveform 620 may be greater than the first amplitude 620A of the second pulse waveform 620. The second amplitude 620B of the second pulse waveform 620 may be lesser than the third amplitude 620C of the second pulse waveform 620.

[0050] The first current period segment 611 of the first pulse waveform 610 may have a different length of time than the third current period segment 613 of the first pulse waveform 610. The first current period segment 611 of the first pulse waveform 610 may have a longer length of time than the third current period segment 613 of the first pulse waveform 610. The first current period segment 611 of the first pulse waveform 610 may have a different length of time than the second current period segment 612 of the first pulse waveform 610. The first current period segment 611 of the first pulse waveform 610 may have a longer length of time than the second current period segment 612 of the first pulse waveform 610. The third current period segment 613 of the first pulse waveform 610 may have a different length of time than the second current period segment 612 of the first pulse waveform 610. In embodiments, the third current period segment 613 of the first pulse waveform 610 may have a same length of time to those of the second current period segment 612 of the first pulse waveform 610.

[0051] The first current period segment 621 of the second pulse waveform 620 may have a different length of time than the third current period segment 623 of the second pulse waveform 620. The first current period segment 621 of the second pulse waveform 620 may have a longer length of time than the third current period segment 623 of the second pulse waveform 620. The first current period segment 621 of the second pulse waveform 620 may have a different length of time than the second current period segment 622 of the second pulse waveform 620. The first current period segment 621 of the second pulse waveform 620 may have a longer length of time than the second current period segment 622 of the second pulse waveform 620. The third current period segment 623 of the second pulse waveform 620 may have a different length of time than the second current period segment 622 of the second pulse waveform 620.In embodiments, the third current period segment 623 of the second pulse waveform 620 may have a same length of time to those of the second current period segment 622 of the second pulse waveform 620.

[0052] Referring now to FIG. 5, an example third pulse waveform 630 and fourth pulse waveform 640 are depicted. In one or more embodiments, the first current may further comprise a third pulse waveform 630 following the first pulse waveform 610. In embodiments, the third pulse waveform 630 may comprise a sine waveform, a triangle waveform, a square waveform, a sawtooth waveform, or combinations thereof. In embodiments, the third pulse waveform 630 may comprise a square waveform. The second current may further comprise a fourth pulse waveform 640 following the second pulse waveform 620. In embodiments, the fourth pulse waveform 640 may comprise a sine waveform, a triangle waveform, a square waveform, a sawtooth waveform, or combinations thereof. In embodiments, the fourth pulse waveform 640 may comprise a square waveform.

[0053] According to embodiments, the fourth pulse waveform 640 is different from the third pulse waveform 630. The third pulse waveform 630 may comprise a positive current portion 635 and a negative current portion 636. The fourth pulse waveform 640 may also comprise a positive current portion 645 and a negative current portion 646, but not identical to that of the third pulse waveform 630. Additionally, the third pulse waveform 630 may comprise a first current period segment 631 and a second current period segment 632, adding up to a full period. The fourth pulse waveform 640 may comprise a first current period segment 641 and a second current period segment 642, adding up to a full period.

[0054] In embodiments, the first current period segment 631 of the third pulse waveform 630 may have a different length of time than the second current period segment 632 of the third pulse waveform 630. The first current period segment 631 of the third pulse waveform 630 may have a longer length of time than the second current period segment 632 of the third pulse waveform 630. In embodiments, the first current period segment 631 of the third pulse waveform 630 may have a different length of time than the first current period segment 611 of the first pulse waveform 610. The first current period segment 631 of the third pulse waveform 630 may have a longer length of time than the first current period segment 611 of the first pulse waveform 610. In embodiments, the second current period segment 632 of the third pulse waveform 630 may have a same length of time than the second current period segment 612 ofthe first pulse waveform 610.

[0055] In embodiments, the first current period segment 641 of the fourth pulse waveform 640 may have a different length of time than the second current period segment 642 of the fourth pulse waveform 640. The first current period segment 641 of the fourth pulse waveform 640 may have a longer length of time than the second current period segment 642 of the fourth pulse waveform 640. In embodiments, the first current period segment 641 of the fourth pulse waveform 640 may have a different length of time than the first current period segment 621 of the second pulse waveform 620. The first current period segment 641 of the fourth pulse waveform 640 may have a longer length of time than the first current period segment 621 of the second pulse waveform 620. In embodiments, the second current period segment 642 of the fourth pulse waveform 640 may have a same length of time than the second current period segment 622 of the second pulse waveform 620.

[0056] The first current period segment 631 of the third pulse waveform 630 may be a positive current and comprise a third amplitude 630A. In embodiments, the third amplitude 630A of the third pulse waveform 630 may be same as the first amplitude 610A of the first pulse waveform 610. The second current period segment 632 of the third pulse waveform 630 may be a negative current and comprise a fourth amplitude 630B. The fourth amplitude 630B may be negative. In embodiments, the fourth amplitude 630B of the third pulse waveform 630 may be same as the second amplitude 610B of the first pulse waveform 610.

[0057] The first current period segment 641 of the fourth pulse waveform 640 may be a positive current and may comprise a third amplitude 640A. In embodiments, the third amplitude 640A of the fourth pulse waveform 640 may be same as the first amplitude 620A of the second pulse waveform 620. The second current period segment 642 of the fourth pulse waveform 640 may be a negative current and comprise a fourth amplitude 640B. In embodiments, the fourth amplitude 640B of the fourth pulse waveform 640 may be same as the second amplitude 620B of the second pulse waveform 620.

[0058] In embodiments, a ratio of the third amplitude 630A of the third pulse waveform 630 to the fourth amplitude 630B of the third pulse waveform 630, a ratio of the third amplitude 640A of the fourth pulse waveform 640 to the fourth amplitude 640B of the fourth pulse waveform 640, or both, may be from 1 : 1 to 1: 10, from 1 :2 to 1: 10, from 1 : 3 to 1: 10, from 1 : 1 to 1:8, from 1:2 to 1:8, from 1:3 to 1:8, from 1: 1 to 1:6, from 1:2 to 1:6, from 1:3 to 1:6, from1 : 1 to 1:5, from 1 : 2 to 1:5, from 1 : 3 to 1 : 5 , or any and all sub-ranges formed from any of these endpoints. In some embodiments, the third amplitude 630A of the third pulse waveform 630 may be less than the fourth amplitude 630B of the third pulse waveform 630. In some embodiments, the third amplitude 640A of the fourth pulse waveform 640 may be less than the fourth amplitude 640B of the fourth pulse waveform 640.

[0059] In embodiments, a ratio of time period of the first current period segment 631 of the third pulse waveform 630 to time period of the second current period segment 632 of the third pulse waveform 630, a ratio of time period of the first current period segment 641 of the fourth pulse waveform 640 to time period of the second current period segment 642 of the fourth pulse waveform 640, or both, may be 20 milliseconds: 1 millisecond to 10 milliseconds, 25: 1 to 10, 30: 1 to 10, 35: 1 to 10, 40: 1 to 10, 45: 1 to 10, 50: 1 to 10, 55: 1 to 10, 60: 1 to 10, 65: 1 to 10, 70: 1 to 10, 75: 1 to 10, 80: 1 to 10, 20: 1 to 8, 25: 1 to 8, 30: 1 to 8, 35: 1 to 8, 40: 1 to 8, 45: 1 to 8, 50: 1 to 8, 55: 1 to 8, 60: 1 to 8, 65: 1 to 8, 70: 1 to 8, 75: 1 to 8, 80: 1 to 8, 20: 1 to 6, 25: 1 to 6, 30: 1 to 6, 35: 1 to 6, 40: 1 to 6, 45: 1 to 6, 50: 1 to 6, 55: 1 to 6, 60: 1 to 6, 65: 1 to 6, 70: 1 to 6, 75: 1 to 6, 80: 1 to 6, 20: 1 to 4, 25: 1 to 4, 30: 1 to 4, 35: 1 to 4, 40: 1 to 4, 45: 1 to 4, 50: 1 to 4, 55: 1 to 4, 60: 1 to 4, 65: 1 to 4, 70: 1 to 4, 75: 1 to 4, 80: 1 to 4, 20: 2, 25: 2, 30: 2, 35: 2, 40: 2, 45: 2, 50: 2, 55: 2, 60: 2, 65: 2, 70: 2, 75: 2, 80: 2, or any and all subranges formed from any of these endpoints.

[0060] In embodiments, a ratio of time period of the first current period segment 611 of the first pulse waveform 610 to time period of the second current period segment 612 of the first pulse waveform 610 may be 40:4 and a ratio of time period of the first current period segment 631 of the third pulse waveform 630 to time period of the second current period segment 632 of the third pulse waveform 630 may be 80:4. In embodiments, a ratio of time period of the first current period segment 621 of the second pulse waveform 620 to time period of the second current period segment 622 of the second pulse waveform 620 may be 40:4 and a ratio of time period of the first current period segment 641 of the fourth pulse waveform 640 to time period of the second current period segment 642 of the fourth pulse waveform 640 may be 80:4.

[0061] In embodiments, the first pulse waveform 610 and the third pulse waveform 630 may be shifted to each other, the second pulse waveform 620 and the fourth pulse waveform 640 may be shifted to each other, or both, within from 1 minute to 50 minutes, from 2 minutes to 50 minutes, from 3 minutes to 50 minutes, from 4 minutes to 50 minutes, from 5 minutes to 50minutes, from 1 minute to 45 minutes, from 2 minutes to 45 minutes, from 3 minutes to 45 minutes, from 4 minutes to 45 minutes, from 5 minutes to 45 minutes, from 1 minute to 40 minutes, from 2 minutes to 40 minutes, from 3 minutes to 40 minutes, from 4 minutes to 40 minutes, from 5 minutes to 40 minutes, from 1 minute to 35 minutes, from 2 minutes to 35 minutes, from 3 minutes to 35 minutes, from 4 minutes to 35 minutes, from 5 minutes to 35 minutes, from 1 minute to 30 minutes, from 2 minutes to 30 minutes, from 3 minutes to 30 minutes, from 4 minutes to 30 minutes, from 5 minutes to 30 minutes, or any and all sub-ranges formed from any of these endpoints.

[0062] The partially fdled via may reduce thermal stability or electrical flow of the silica- containing substrate. By flowing the first current and the second current, which have a different pulse waveform, for the electroplating process, the present disclosure may fill the entirety of the via with the conductive metal, thereby providing the silica-containing substrates with improved thermal durability and surface flatness. These silica-containing substrates may be suitable for high precision electrode formations in relatively high temperature conditions for micro light-emitting diode (LED) or glass interposer. The entirety filled via may provide high reliability and heat dissipation due to the high heat conductivity of the metal.

[0063] The present disclosure includes numerous aspects, listed as aspects 1-20, hereinbelow.

[0064] Aspect 1. A method for processing a silica-containing substrate, the method comprising: submerging a silica-containing substrate and a counter electrode into a metal ioncontaining solution, wherein: the silica-containing substrate comprises a first surface and a second surface opposite the first surface; and the silica-containing substrate comprises at least one via that spans from the first surface to the second surface; filling at least one via of the silica-containing substrate with a metal by an electroplating process comprising: flowing a first current between the first surface and the counter electrode; and flowing a second current between the second surface and the counter electrode; wherein: the first current comprises a first pulse waveform; the second current comprises a second pulse waveform; the first pulse waveform is different than the second pulse waveform; and the entirety of the via is filled with conductive metal while the first current and the second current are flowed.

[0065] Aspect 2. The method of claim 1, wherein the silica-containing substrate comprises greater than or equal to 75 mol % silica.

[0066] Aspect 3. The method of any previous claim, wherein the silica-containing substrate comprise glass or glass-ceramic.

[0067] Aspect 4. The method of any previous claim, wherein the metal comprises copper, silver, aluminum, titanium, gold, platinum, nickel, tungsten, magnesium, or combinations thereof.

[0068] Aspect 5. The method of claim 4, wherein the metal is copper.

[0069] Aspect 6The method of any previous claim, wherein the at least one via is substantially cylindrically shaped.

[0070] Aspect 7. The method of any previous claim, wherein one or both of: the first pulse waveform comprises a first current period segment comprising a positive current and a second current period segment comprising a negative current; or the second pulse waveform comprises a first current period segment comprising a positive current and a second current period segment comprising a negative current.

[0071] Aspect 8. The method of claim 7, wherein the first current period segment of the first pulse waveform has a different length of time than the first current period segment of the second pulse waveform.

[0072] Aspect 9. The method of claim 7, wherein the first current period segment of the first pulse waveform has the same length of time as the first current period segment of the second pulse waveform but are out of phase relative to one another.

[0073] Aspect 10. The method of claim 7, wherein one or both of: a ratio of the first amplitude of the first pulse waveform to the second amplitude of the first pulse waveform is from 1:3 to 1:5; or a ratio of the first amplitude of the second pulse waveform to the second amplitude of the second pulse waveform is from 1:3 to 1:5.

[0074] Aspect 1 l.The method of claim 7, wherein one or both of: a ratio of time period of the first current period segment of the first pulse waveform to time period of the second current period segment of the first pulse waveform is 40: 1 to 10; or a ratio of time period of the first current period segment of the second pulse waveform to time period of the second current period segment of the second pulse waveform is 80: 1 to 10.

[0075] Aspect 12. The method of claim 7, wherein: a current density of the first current is from 0.1 amps per square decimeter to 3 amps per square decimeter; a current density of the second current is from 0.1 amps per square decimeter to 3 amps per square decimeter; or both.

[0076] Aspect 13. The method of claim 7, wherein one or both of: the first pulse waveform further comprises a third current period segment comprising a third amplitude, the third amplitude of the first pulse waveform is greater than the first amplitude of the first pulse waveform; or the second pulse waveform further comprises a third current period segment comprising a third amplitude, the third amplitude of the second pulse waveform is greater than the first amplitude of the second pulse waveform.

[0077] Aspect 14. The method of claim 13, wherein one or more of: the third current period segment of the first pulse waveform comprises a positive current; the fourth current period segment of the first pulse waveform comprises a negative current; the third current period segment of the second pulse waveform comprises a positive current; or the fourth current period segment of the second pulse waveform comprises a negative current.

[0078] Aspect 15.The method of claim 7, wherein the first current period segment of the first pulse waveform has a different length of time than the third current period segment of the first pulse waveform.

[0079] Aspect 16. The method of claim 7, wherein one or both of: the first current further comprises a third pulse waveform following the first pulse waveform; or second current further comprises a fourth pulse waveform following the second pulse waveform.

[0080] Aspect 17. The method of claim 16, wherein one or both of: the first pulse waveform and the third pulse waveform are shifted to each other within from 3 minutes to 50 minutes; or the second pulse waveform and the fourth pulse waveform are shifted to each other within from 3 minutes to 50 minutes.

[0081] Aspect 18. The method of claim 16, wherein one or both of: the third pulse waveform comprises a third current period segment comprising a positive current and a fourth current period segment comprising a negative current; or the fourth pulse waveform comprises a third current period segment comprising a positive current and a fourth current period segment comprising a negative current.

[0082] Aspect 19. The method of any previous claim, further comprising providing, by a nozzle, the metal ion-containing solution on the first surface and the second surface.

[0083] Aspect 20. The method of claim 19, wherein a flow rate of the metal ion-containing solution provided by the nozzle is from 0. 1 liter per minute to 3.0 liter per minute.Examples

[0084] A 50 mm x 50 mm Coming code 7980 fused silica substrate with 0.34 mm thickness and having a via (diameter of 20 micrometers) was provided to be submerged with a first counter electrode and a second counter electrode into a copper ion containing solution. The copper ion containing solution included a copper ion centration of from 50 to 65 grams per liter. The first counter electrode was connected with the first surface of the silica substrate. The second counter electrode was connected with the second surface of the silica substrate. The first counter electrode and the first surface were connected with the front rectifier. The second counter electrode and the second surface were connected with the back rectifier. The front rectifier flowed the first current. The back rectifier flowed the second current. In addition, the copper ion containing solution was provided on the first surface and the second surface by a nozzle having an inner diameter size of from 1 to 2 mm with a flow rate of 40 Hz (from 0.75 to 0.85 L / min).

[0085] Comparative Examples 1-3

[0086] As shown in FIG. 6, for Comparative Examples 1-3, the symmetric pulse waveform was provided as the first current and the second current. The first current and the second current had the specifications as shown in FIG. 6. For example, for Comparative Example 1, the first current and the second current had a current density of 0.26 ASD, and 300 % of periodic pulse reverse (PPR), which means the current density of negative current was -0.78 ASD while the current density of positive current was 0.26 ASD. For Comparative Example 1, the front rectifier PPR ratio plating time was 60 minutes while a ratio of time period of the positive amplitude of the first pulse waveform to time period of the negative amplitude of the first pulse waveform was 80 milliseconds: 4 milliseconds. The back rectifier PPR ratio plating time was 60 minutes while a ratio of time period of the positive amplitude of the second pulse waveform to time period of the negative amplitude of the second pulse waveform was 80:4. For Comparative Example 2, the first current and the second current had the same specifications ofthe first and the second currents of Comparative Example 1 except the current density was 0.53 ASD. For Comparative Example 3, the first current and the second current had the same specifications of the first and the second currents of Comparative Example 1 except the current density was 0.79 ASD.

[0087] Examples 4-6

[0088] As shown in FIG. 6, for Examples 4-6, the asymmetric pulse waveform was provided as the first current and the second current. The first current and the second current had the specifications as shown in FIG. 6. For example, for Example 4, the first current and the second current had a waveform diagram as shown in FIG. 6, a current density of 0.26 ASD, and 300 % of periodic pulse reverse (PPR), which means the current density of negative current was - 0.78 ASD while the current density of positive current was 0.26 ASD. For Example 4, the front rectifier PPR ratio plating time was a total 60 minutes including a first 30 minutes while a ratio of time period of the positive amplitude of the first pulse waveform to time period of the negative amplitude of the first pulse waveform was 40 milliseconds: 2 milliseconds, and the following 30 minutes while a ratio of time period of the positive amplitude of the first pulse waveform to time period of the negative amplitude of the first pulse waveform was 80 milliseconds: 2 milliseconds. The back rectifier PPR ratio plating time was a total 60 minutes including a second 30 minutes while a ratio of time period of the positive amplitude of the second pulse waveform to time period of the negative amplitude of the second pulse waveform was 80 milliseconds: 2 milliseconds, and the following 30 minutes while a ratio of time period of the positive amplitude of the second pulse waveform to time period of the negative amplitude of the second pulse waveform was 40 milliseconds: 2 milliseconds. For Example 5, the first current and the second current had the same specifications of the first and the second currents of Example 4 except the current density was 0.53 ASD and the back rectifier PPR ratio plating time was a total 60 minutes including a second 30 minutes while a ratio of time period of the positive amplitude of the second pulse waveform to time period of the negative amplitude of the second pulse waveform was 40 milliseconds: 2 milliseconds, and the following 30 minutes while a ratio of time period of the positive amplitude of the second pulse waveform to time period of the negative amplitude of the second pulse waveform was 80 milliseconds: 2 milliseconds. For Example 6, the first current and the second current had the same specifications of the first and the second currents of Example 5 except the current density was 0.79 ASD.

[0089] Examples 7-9

[0090] As shown in FIG. 6, for Examples 7-9, the asymmetric pulse waveform with an extra pulse was provided as the first current and the second current. The first current and the second current had the specifications as shown in FIG. 6. For example, for Example 7, the first current and the second current had a waveform diagram as shown in FIG. 6, a current density of 0.26 ASD, and 300 % of periodic pulse reverse (PPR), which means the current density of negative current was -0.78 ASD while the current density of positive current was 0.26 ASD. For Example 7, the front rectifier PPR ratio plating time was a total 60 minutes while a ratio of time period of the positive amplitude of the first pulse waveform to time period of the negative amplitude of the first pulse waveform was 38 milliseconds: 2 milliseconds. The extra pulse was provided during the time period of the positive amplitude of the first pulse waveform. The back rectifier PPR ratio plating time was a total 60 minutes while a ratio of time period of the positive amplitude of the second pulse waveform to time period of the negative amplitude of the second pulse waveform was 38 milliseconds: 2 milliseconds. The extra pulse was provided during the time period of the positive amplitude of the second pulse waveform. For Example 8, the first current and the second current had the same specifications of the first and the second currents of Example 7 except the current density was 0.53 ASD. For Example 9, the first current and the second current had the same specifications of the first and the second currents of Example 7 except the current density was 0.79 ASD.

[0091] Examples 10-12

[0092] As shown in FIG. 7, for Examples 10-12, the asymmetric pulse waveform was provided as the first current comprising a first pulse waveform and a third pulse waveform and the second current comprising a second pulse waveform and a fourth pulse waveform. The first current and the second current had the specifications as shown in FIG. 7. For example, for Example 10, the first current and the second current had a waveform diagram as shown in FIG. 7, a current density of 0.79 ASD, and 400 % of periodic pulse reverse (PPR), which means the current density of negative current was -3.16 ASD while the current density of positive current was 0.79 ASD. For Example 10, the front rectifier PPR ratio plating time of the first pulse waveform was 30 minutes while a ratio of time period of the positive amplitude of the first pulse waveform to time period of the negative amplitude of the first pulse waveform was 40 milliseconds: 2 milliseconds. The front rectifier PPR ratio plating time of the third pulsewaveform was 30 minutes while a ratio of time period of the positive amplitude of the third pulse waveform to time period of the negative amplitude of the third pulse waveform was 80 milliseconds: 2 milliseconds. The back rectifier PPR ratio plating time of the second pulse waveform was 30 minutes while a ratio of time period of the positive amplitude of the second pulse waveform to time period of the negative amplitude of the second pulse waveform was 80 milliseconds: 2 milliseconds. The back rectifier PPR ratio plating time of the fourth pulse waveform was 30 minutes while a ratio of time period of the positive amplitude of the fourth pulse waveform to time period of the negative amplitude of the fourth pulse waveform was 40 milliseconds: 2 milliseconds. For Example 11, the first current and the second current had the same specifications of the first and the second currents of Example 10 except waveform diagrams of the first, second, third, and fourth pulse waveforms, the front rectifier PPR ratio plating time of the first pulse waveform was a 30 minutes while a ratio of time period of the positive amplitude of the first pulse waveform to time period of the negative amplitude of the first pulse waveform was 40 milliseconds: 4 milliseconds and the front rectifier PPR ratio plating time of the third pulse waveform was a 30 minutes while a ratio of time period of the positive amplitude of the third pulse waveform to time period of the negative amplitude of the third pulse waveform was 80 milliseconds: 4 milliseconds. The back rectifier PPR ratio plating time of the second pulse waveform was also 30 minutes while a ratio of time period of the positive amplitude of the second pulse waveform to time period of the negative amplitude of the second pulse waveform was 40 milliseconds: 4 milliseconds. The back rectifier PPR ratio plating time of the fourth pulse waveform was 30 minutes while a ratio of time period of the positive amplitude of the fourth pulse waveform to time period of the negative amplitude of the fourth pulse waveform was 80 milliseconds: 4 milliseconds. For Example 12, the first current and the second current had the same specifications of the first and the second currents of Example 11 except the front rectifier PPR ratio plating time of the first pulse waveform and the front rectifier PPR ratio plating time were changed every 5 minutes and the back rectifier PPR ratio plating time of the second pulse waveform and the back rectifier PPR ratio plating time of the fourth pulse waveform were changed every 5 minutes.

[0093] Example 13

[0094] For Example 13, the first current and the second current had the same specifications of the first and the second currents of Example 12. However, the flow rate of the copper ion containing solution provided on the first surface and the second surface was 55 Hz (from 1.05to 1.15 L / min).

[0095] Example 14

[0096] For Example 14, the first current and the second current had the same specifications of the first and the second currents of Example 12 except a ratio of time period of the positive amplitude of the first pulse waveform to time period of the negative amplitude of the first pulse waveform was 40 milliseconds: 8 milliseconds and a ratio of time period of the positive amplitude of the third pulse waveform to time period of the negative amplitude of the third pulse waveform was 80 milliseconds: 8 milliseconds. Moreover, a ratio of time period of the positive amplitude of the second pulse waveform to time period of the negative amplitude of the second pulse waveform was 40 milliseconds: 8 milliseconds and a ratio of time period of the positive amplitude of the fourth pulse waveform to time period of the negative amplitude of the fourth pulse waveform was 80 milliseconds: 8 milliseconds.

[0097] Examples 15 and 16

[0098] For Examples 15 and 16, the first current and the second current had the same specifications of the first and the second currents of Example 14. However, the flow rate of the copper ion containing solution provided on the first surface and the second surface was 55 Hz (from 1.05 to 1.15 L / min) .

[0099] Surface Thickness Evaluation, Backlight Tests, and X-section photo evaluation Results

[0100] Backlight test and X-section photo evaluation was executed to determine whether the via was blocked or includes copper deposition of the center of via. For the backlight test, the light was provided to determine if the light was penetrated through the plurality of via. The X-section photo was taken by optical microscope.

[0101] Comparative Examples 1-3 showed none penetration of light but X-section photos of Comparative Examples 1-3 showed that the top and the bottom of the via entrance closed too early entrance closed too early before getting proper copper thickness at a center of via. In particular, FIG. 8A showed that the plurality of vias of Comparative Example 1 were not entirely filled with a copper.

[0102] In contrast, Examples 4-16 showed none penetration of light and X-section photos of Examples 4-14 showed that the plurality of vias of Examples 4-14 were more fdled with a copper compared to Comparative Examples 1-3. Moreover, X-section photos of Examples 15- 16 showed that the plurality of vias of Examples 15-16 were entirely filled with a copper. In particular, FIGS. 8B and 8C showed that the plurality of vias of Example 15 were entirely filled with a copper. Furthermore, Examples 4-16 showed lower surface thickness compared to Comparative Examples 1-3.

[0103] According to embodiments, the silica containing substrate may undergo electroplating to fully fill one or more vias with metal. As is known in the art, electroplating, also known sometimes as electrochemical deposition or electrodeposition, is a process for depositing a metal coating on a solid substrate through the reduction of cations of metal by means of a direct electric current. The part to be coated acts as the cathode (negative electrode) of an electrolytic cell; the electrolyte is a solution of a salt of the metal to be coated; and the anode (positive electrode) is usually either a block of that metal, or of some inert conductive material. The current is generally provided by an external power supply.

[0104] It should now be understood that embodiments described herein provide methods for providing hourglass-shaped vias in silica-containing substrates, such as high purity silica- containing substrates. The hourglass-shaped vias may be metalized using an electroplating process, for example. The hourglass-shaped vias may be formed by a laser-damage-and-etch process by which a customized damage track in formed in the silica-containing substrate prior to etching. The damage track has stronger material modification proximate the surfaces of the silica-containing substrate than in the bulk / middle of the silica-containing substrate. The customized damage track results in an etched via having tapered regions defining a waist. The waist may act as a metal bridge to grow an interior metal layer within the via. In embodiments, silica-containing substrates with hourglass-shaped vias may be used as interposers in electronic devices, such as high-frequency electronic devices.

[0105] 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 processing a silica-containing substrate, the method comprising: submerging a silica-containing substrate and a counter electrode into a metal ioncontaining solution, wherein: the silica-containing substrate comprises a first surface and a second surface opposite the first surface; and the silica-containing substrate comprises at least one via that spans from the first surface to the second surface; filling at least one via of the silica-containing substrate with a metal by an electroplating process comprising: flowing a first current between the first surface and the counter electrode; and flowing a second current between the second surface and the counter electrode; wherein: the first current comprises a first pulse waveform; the second current comprises a second pulse waveform; the first pulse waveform is different than the second pulse waveform; and the entirety of the via is filled with conductive metal while the first current and the second current are flowed.

2. The method of claim 1, wherein the silica-containing substrate comprises greater than or equal to 75 mol % silica.

3. The method of any previous claim, wherein the silica-containing substrate comprise glass or glass-ceramic.

4. The method of any previous claim, wherein the metal comprises copper, silver, aluminum, titanium, gold, platinum, nickel, tungsten, magnesium, or combinations thereof.

5. The method of claim 4, wherein the metal is copper.6 The method of any previous claim, wherein the at least one via is substantially cylindrically shaped.

7. The method of any previous claim, wherein: the first pulse waveform comprises a first current period segment comprising a positive current and a second current period segment comprising a negative current; and the second pulse waveform comprises a first current period segment comprising a positive current and a second current period segment comprising a negative current.

8. The method of claim 7, wherein the first current period segment of the first pulse waveform has a different length of time than the first current period segment of the second pulse waveform.

9. The method of claim 7, wherein the first current period segment of the first pulse waveform has the same length of time as the first current period segment of the second pulse waveform but are out of phase relative to one another.

10. The method of claim 7, wherein one or both of: a ratio of a first amplitude of the first pulse waveform to a second amplitude of the first pulse waveform is from 1:3 to 1:5; or a ratio of a first amplitude of the second pulse waveform to a second amplitude of the second pulse waveform is from 1:3 to 1:5.

11. The method of claim 7, wherein one or both of: a ratio of time period of the first current period segment of the first pulse waveform to time period of the second current period segment of the first pulse waveform is 40: 1 to 10; or a ratio of time period of the first current period segment of the second pulse waveform to time period of the second current period segment of the second pulse waveform is 80: 1 to 10.

12. The method of claim 7, wherein one or both of: a current density of the first current is from 0.1 amps per square decimeter to 3 amps per square decimeter; or a current density of the second current is from 0.1 amps per square decimeter to 3 amps per square decimeter.

13. The method of claim 7, wherein one or both of: the first pulse waveform further comprises a third current period segment comprising a third amplitude, the third amplitude of the first pulse waveform is greater than the first amplitude of the first pulse waveform; orthe second pulse waveform further comprises a third current period segment comprising a third amplitude, the third amplitude of the second pulse waveform is greater than the first amplitude of the second pulse waveform.

14. The method of claim 13, wherein one or more of: the third current period segment of the first pulse waveform comprises a positive current; the fourth current period segment of the first pulse waveform comprises a negative current; the third current period segment of the second pulse waveform comprises a positive current; or the fourth current period segment of the second pulse waveform comprises a negative current.

15. The method of claim 7, wherein the first current period segment of the first pulse waveform has a different length of time than the third current period segment of the first pulse waveform.

16. The method of claim 7, wherein one or both of: the first current further comprises a third pulse waveform following the first pulse waveform; or the second current further comprises a fourth pulse waveform following the second pulse waveform.

17. The method of claim 16, wherein one or both of:the first pulse waveform and the third pulse waveform are shifted to each other within from 3 minutes to 50 minutes; or the second pulse waveform and the fourth pulse waveform are shifted to each other within from 3 minutes to 50 minutes.

18. The method of claim 16, wherein one or both of: the third pulse waveform comprises a third current period segment comprising a positive current and a fourth current period segment comprising a negative current; or the fourth pulse waveform comprises a third current period segment comprising a positive current and a fourth current period segment comprising a negative current.

19. The method of any previous claim, further comprising providing, by a nozzle, the metal ion-containing solution on the first surface and the second surface.

20. The method of claim 19, wherein a flow rate of the metal ion-containing solution provided by the nozzle is from 0.1 liter per minute to 3.0 liter per minute.

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