Method for perforating thin glass using high-frequency heating

Abstract

The present invention relates to a technique for forming a via hole having a diameter of approximately 0.1 mm or slightly larger in a thin glass, made of a glass material, such as a thin semiconductor substrate or an interposer, wherein a bar-shaped heating element having an outer diameter that corresponds exactly to the diameter of a via-hole in a thin glass to be processed is heated to a high temperature and then rotated in place to form the via-hole that penetrates from one surface to the other surface of the thin glass. According to the present invention, the outer diameter is formed small in the direction opposite the penetration direction of a high-frequency heating element, thereby preventing the occurrence of cracks during the penetration process.

Description

Thin glass perforation method by high-frequency heating

[0001] The present invention relates to a technique for forming via (vertical interconnect access) holes having a diameter of approximately 0.1 mm or slightly larger than that in a thin glass material such as a thin semiconductor substrate or an interposer.

[0002] More specifically, the present invention relates to a via hole formation technology that eliminates the need for an etching process because it enables processing without the occurrence of micro-cracks when forming a via hole penetrating from one side to the other of thin glass.

[0003] CPU chips, such as processor cores, typically have hundreds of contact points on their undersides that are densely spaced apart and distributed over a relatively small area. Due to this dense spacing, these contact points cannot be directly placed on a circuit board, the so-called mother board.

[0004] Therefore, an interposer is employed that allows for the expansion of the connection base. As the interposer, a fiberglass mat surrounded by epoxy material is often used, and this fiberglass mat is provided with a number of holes (via holes).

[0005] A conductive path extending on one side of the glass fiber mat extends to each via hole, fills the via hole, and reaches the terminals of the processor core on the other side of the glass fiber mat.

[0006] As a result, underfill is applied both around the perimeter of the processor core and between the processor core and the fiberglass mat; this underfill protects the wires and mechanically bonds the processor core and the fiberglass mat. However, the processor core and the fiberglass mat exhibit different thermal expansions.

[0007] For example, the fiberglass mat has a coefficient of thermal expansion of 15 to 17 x 10⁻⁶ / K, whereas the silicon-based core processor has a coefficient of thermal expansion of 3.2 to 3.3 x 10⁻⁶ / K. Therefore, when heated, the expansion of the core processor and the fiberglass mat differs, causing mechanical stress between these two components. This can be particularly critical to the contact connection if the two components are not completely face-to-face joined. In this case, the contact point can easily break.

[0008] Another drawback regarding the use of fiberglass mats is mechanically drilling via holes in the fiberglass mats. However, the diameter of the holes drilled is limited to 250 µm to 450 µm.

[0009] WO 02 / 058135 A2 describes the configuration and fabrication method of a connection structure usable as an interposer type, which employs wafer technology including forming via holes and trenches in a dielectric material such as silicon dioxide and filling the via holes and trenches with a conductive layer. However, this method of achieving contact connection is very expensive.

[0010] US 2002 / 0180015 A1 discloses a multichip module comprising a semiconductor device and a wiring board for mounting the semiconductor device. The wiring board is made of a glass substrate having via holes formed by sandblasting. In this case, a wiring layer is formed on the surface of the glass substrate. Additionally, the glass substrate has wiring and an insulating layer. This aims to select a coefficient of thermal expansion of the glass substrate close to the coefficient of thermal expansion of silicon.

[0011] However, for thin glass that is a processing target including an interposer, there is a need for the implementation of a technology that can eliminate existing high costs among methods for forming via holes regardless of the difference in the coefficient of thermal expansion with adjacent components.

[0012] Meanwhile, the prior art related to the present invention is as follows.

[0013] Korean Patent Application No. 10-2016-7001285 "Interposer and method for forming holes in the interposer"

[0014] Korean Patent Application No. 10-2015-0012459 "Silicon interposer having improved through-via holes and method of manufacturing the same"

[0015] Republic of Korea Patent Application No. 10-2013-7002443 "Method and apparatus for creating a plurality of holes in a workpiece"

[0016] Republic of Korea Patent Application No. 10-2004-0095105 "Glass tube processing method, glass tube processing apparatus and glass tube"

[0017] The objective of the present invention is to provide a method for drilling thin glass by high-frequency heating that can stably form via holes in thin glass regardless of the difference in the coefficient of thermal expansion between the thin glass and adjacent components when forming via holes in thin glass to be processed.

[0018] The thin glass perforation method by high-frequency heating according to the present invention may be configured to include: (a) a step of placing a plate glass on top of a high-frequency coil member; (b) a step of placing a thin glass to be processed on the plate glass; (c) a step of aligning a high-frequency heating element on top of the thin glass, the high-frequency heating element being formed in a cylindrical shape with a lower outer diameter that is relatively smaller than the lower outer diameter of a predetermined upper region and having a flat lower surface; (d) a step of operating the high-frequency coil member to heat the high-frequency heating element to a desired temperature; (e) a step of rotating the high-frequency heating element in place while in contact with the surface of the thin glass; and (f) a step of moving the high-frequency heating element downward to form a via hole that penetrates the thin glass in the vertical direction.

[0019] And, after step (f), (g) a step of moving the high-frequency heating element vertically upward to a position corresponding to the initial height; (h) a step of moving the high-frequency heating element and the high-frequency coil member horizontally for a predetermined distance in conjunction; and (i) a step of forming a plurality of via holes by repeating steps (f) to (h) sequentially a plurality of times.

[0020] Additionally, after step (f), the method may further comprise a step of waiting for residue formed at the bottom of the via hole of the thin glass to fall into the recessed portion of the plate glass; and a step of detaching the thin glass from the plate glass.

[0021] The present invention has the advantage of being able to implement via holes without considering the difference in the coefficient of thermal expansion with adjacent components to the thin glass by rotating a high-frequency heating element in place while penetrating the thin glass.

[0022] In addition, the present invention also exhibits the advantage of preventing cracks from occurring during the penetration process by forming the outer diameter in a direction opposite to the penetration direction of the high-frequency heating element to be small.

[0023] In addition, the present invention also has the advantage of solving the problem of high costs caused by conventional via hole formation by forming via holes through the heating and rotation in place of a high-frequency heating element.

[0024] FIG. 1 is an exemplary diagram of a thin glass employed in a thin glass perforation method by high-frequency heating according to the present invention.

[0025] FIG. 2 is an exemplary diagram illustrating a part of the configuration of an apparatus for implementing a thin glass perforation method by high-frequency heating according to the present invention.

[0026] FIG. 3 is a drawing of FIG. 2 viewed from a different angle.

[0027] FIG. 4 is an example diagram illustrating a state in which via holes are formed in thin glass as the high-frequency heating element moves up and down in FIG. 2.

[0028] Fig. 5 is a cross-sectional view along line A-A' of Fig. 4.

[0029] FIG. 6 is a drawing of FIG. 5 viewed from a different angle.

[0030] FIG. 7 is an enlarged drawing of a portion of FIG. 6.

[0031] FIG. 8 is a drawing illustrating the state in which residue has detached from the thin glass in FIG. 7.

[0032] FIG. 9 is a diagram exemplarily illustrating a state in which downward thermal vibration is formed within thin glass in response to the rotational speed of a high-frequency heating element according to the present invention.

[0033] FIG. 10 is a flowchart illustrating a thin glass perforation method by high-frequency heating according to the present invention.

[0034] The present invention will be described in detail below with reference to the drawings.

[0035] In the present invention, the thin glass (200) as the processing target may be a thin glass panel such as a semiconductor substrate, or an interposer as a glass panel connecting the semiconductor substrate and the chip may be used.

[0036] This thin glass (200) is formed with a plurality of via holes (210) as in FIG. 1 so that it can function as a thin panel (e.g., interposer) in the corresponding field, and is cut along cutting lines (221, 222) from the thin glass (200) of the original size to match the specifications of the panel.

[0037] In this specification, the process of forming the cutting lines (221, 222) of the thin glass (200) is omitted, and only the process of forming the via hole (210) in the thin glass (200) as shown in FIG. 1 is described.

[0038] Thin glass (200) is produced as a glass substrate by pouring molten glass liquid over molten tin and undergoing a rapid cooling process.

[0039] At this time, the rapidly cooling glass lattices move in the direction of crystallization, for example, as their volume decreases, but due to the rapid increase in viscosity caused by the cooling, solidified glass is formed before crystallization. The resulting glass is called 'Amorphous' or supercooled liquid, meaning it has no shape.

[0040] Meanwhile, when heat is applied to glass, the viscosity decreases rapidly in the rapid cooling region (transition point region), that is, in the region between 1 / 2 and 1 / 3 of the melting point, and the coefficient of thermal expansion or specific heat capacity changes rapidly, causing the glass to crack or break before reaching the melting point region.

[0041] While via holes can be formed using these properties of glass, if heat is applied directly to the area around the via hole during the via hole formation process, cracks may form around it, making it unusable as a product.

[0042] The high-frequency heating element (400) is preferably made of a metal that does not oxidize at a temperature of approximately 1000°C (e.g., platinum / iridium alloy).

[0043] Referring to FIGS. 5 and 6, the high-frequency heating element (400) may preferably be configured as a cylindrical shape in which the outer diameter of a predetermined upper region is relatively smaller than the outer diameter of the lower region. Also, it is preferable that the bottom surface of the high-frequency heating element (400) be configured to have a flat and smooth surface.

[0044] As a result, when the high-frequency heating element (400) comes into contact with the surface of the thin glass (200) during the process of the high-frequency heating element (400) processing the via hole (210) of the thin glass (200), vertical vibration caused by heat, which is a characteristic of glass particles, occurs. Here, when the high-frequency heating element (400) rotates while in contact with the surface of the thin glass (200), thermal vibration is generated inside the thin glass (200), in which the vertical vibration caused by heat of the glass particles vibrates in a cone shape, as shown in FIG. 9.

[0045] Meanwhile, FIG. 9(a) shows a case where the rotational speed of the high-frequency heating element (400) is relatively faster than that of FIG. 9(b). As such, when the rotational speed of the high-frequency heating element (400) is fast, the thermal vibration that vibrates in a cone shape as in FIG. 9(a) is formed to be narrower laterally and longer downwards than that of FIG. 9(b).

[0046] And, when the rotational speed of the high-frequency heating element (400) is slow, the thermal vibration that vibrates in a cone shape as in Fig. 9 (b) is formed to be wider laterally and shorter downward than in the case of Fig. 9 (a).

[0047] As shown in FIG. 9 (a), a configuration in which the rotational speed of the high-frequency heating element (400) is fast is suitable for cases where the thickness of the thin glass (200) is thick. And, as shown in FIG. 9 (b), a configuration in which the rotational speed of the high-frequency heating element (400) is slow is suitable for cases where the thickness of the thin glass (200) is thin.

[0048] Here, when processing the via hole (210) of the thin glass (200) through the high-frequency heating element (400) having the shape of FIG. 9, if heat conduction is limited as much as possible on the surface of the thin glass (200) corresponding to the entrance of the via hole (210), the vertical vibration caused by heat, which is a characteristic of the glass particles as in FIG. 9, is rotated, so that the thermal vibration occurs in a cone shape as in FIG. 5 and FIG. 6 at the position corresponding to the via hole (210).

[0049] Meanwhile, if heat conduction occurs at the entrance of the via hole (210) into which the high-frequency heating element (400) enters, cracks may occur in the thin glass (200) around the entrance of the via hole (210). To prevent such cracks, heat conduction is preferably blocked at the entrance of the via hole (210) during the process in which the high-frequency heating element (400), having a lower shape as shown in FIG. 9, enters to penetrate the thin glass (200).

[0050] In addition, the high-frequency heating element (400) moves downward on the thin glass (200) while rotating in place, and it is preferable to set the rotation speed to approximately 120 RPM or slightly higher.

[0051] On the other hand, the plate glass (300) can preferably be adopted as glass of the same thickness and physical properties as the thin glass (200) to be processed.

[0052] The plate glass (300) can preferably be composed of glass with a thickness of, for example, 2 mm to 3 mm, since the high-frequency coil member (100) is placed at the bottom to raise the bottom surface temperature of the high-frequency heating element (400) and high-frequency vortex currents pass through it.

[0053] As a result, as shown in FIGS. 7 and 8, during the process of melting the thin glass (200) in the area corresponding to the via hole (210), the corresponding area of ​​the plate glass (300) is also melted and gouged downward. At this time, the melted residue (201) from the thin glass (200) corresponding to the via hole (210) moves to the gouged part of the plate glass (300) as shown in FIGS. 7 and 8.

[0054] Referring to FIGS. 2 and FIGS. 3, the high-frequency coil member (100) can be configured by bending it into a small circle to effectively heat the small high-frequency heating element (400) at the bottom of the high-frequency heating element (400). To do this, a small copper tube and a relatively larger copper tube can be welded together and then wound into 3 to 4 layers to make it as small as possible.

[0055] And, the high-frequency coil member (100) can be shaped to face the harmonic heating element (400) above itself in the eddy current magnetic field formed from the inside out.

[0056] Here, the high frequency formed through the high frequency coil member (100) can preferably be configured in the range of 100 KHZ to 2 MHZ.

[0057] FIG. 10 is a flowchart illustrating a thin glass perforation method by high-frequency heating according to the present invention.

[0058] Steps S110 to S130: First, a plate glass (300) is placed on top of a high-frequency coil member (100) that generates high frequency upward in the range of approximately 100 KHZ to 2 MHZ.

[0059] Next, a thin glass (200) as a processing target for forming via holes is placed on the plate glass (300).

[0060] Then, a high-frequency heating element (400) is aligned on the upper part of the thin glass (200). At this time, the high-frequency heating element (400) may preferably be configured to have a cylindrical shape in which the outer diameter of a predetermined upper region is relatively smaller than the outer diameter of the lower part, as shown in FIGS. 2 to 6.

[0061] Here, it is preferable that the bottom surface of the high-frequency heating element (400) be configured to have a flat and smooth surface.

[0062] Steps S140 to S160: Here, a high-frequency coil member (100) having a frequency in the range of approximately 100 KHZ to 2 MHZ is operated to heat a high-frequency heating element (400) to a desired temperature (e.g., a temperature 200°C to 300°C higher than the melting point of glass).

[0063] Next, as shown in FIG. 9, the high-frequency heating element (400) in a high-temperature state is rotated in place while in contact with the surface of the thin glass (200), and the high-frequency heating element (400) is moved downward, thereby forming a via hole (210) that penetrates the thin glass (200) in the vertical direction.

[0064] Here, referring to FIGS. 2 to 6, when a high-frequency heating element (400) heated to a desired high temperature moves downward while rotating in place while in contact with the surface of the thin glass (200) corresponding to the via hole (210) area, the vertical vibration caused by heat, which is a characteristic of glass particles, is rotated in conjunction with the rotation of the high-frequency heating element (400), so that thermal vibration in a cone shape occurs as shown in FIGS. 6, 7, and 9.

[0065] As a result, the corresponding areas of the thin glass (200) and plate glass (300) corresponding to the via hole (210) melt and their volume decreases, forming empty spaces (S1, S2) as shown in FIG. 7, and the melted residue (201) temporarily hangs on the thin glass (200) corresponding to the edge of the via hole (210).

[0066] Steps S170 to S180: At this time, the residue (201) formed at the bottom of the via hole (210) of the thin glass (200) as in FIG. 7 is allowed to fall into the cut portion of the plate glass (300) as in FIG. 8.

[0067] Then, as time passes, the residue (201) that was temporarily suspended from the thin glass (200) corresponding to the edge of the via hole (210) falls downward as in FIG. 8 and settles on the recessed part of the plate glass (300).

[0068] Next, the thin glass (200) with the via hole (210) formed therein is removed from the plate glass (300), thereby completing the production of a component that functions as an interposer.

[0069] Meanwhile, after step S160, the high-frequency heating element (400) moves vertically upward to a position corresponding to the initial height as shown in FIGS. 5 and 6. Subsequently, the high-frequency heating element (400) and the high-frequency coil member (100) move horizontally a predetermined distance to a position for forming an adjacent via hole (210) in conjunction. Then, as in step S160, the high-frequency heating element (400) is moved downward again to form a via hole (210) that penetrates the thin glass (200) in the vertical direction as shown in FIGS. 5 to 7.

[0070] By repeating steps S160 to S180 sequentially a plurality of times, a plurality of via holes (210) can be formed as shown in FIG. 1.

Claims

1.(a) A step of placing a plate glass on top of a high-frequency coil member; (b) a step of placing the thin glass to be processed onto the plate glass; (c) A step of aligning a high-frequency heating element, which is formed in a cylindrical shape with a lower outer diameter that is relatively smaller than the lower outer diameter and has a flat lower surface, on the upper part of the thin glass; (d) a step of operating the high-frequency coil member to heat the high-frequency heating element to a desired temperature; (e) a step of rotating the high-frequency heating element in place while in contact with the surface of the thin glass; and (f) a step of moving the high-frequency heating element downward to form a via hole penetrating the thin glass in the vertical direction; A thin glass perforation method by high-frequency heating comprising 2. In Claim 1, After the above step (f), (g) A step in which the high-frequency heating element moves vertically upward to a position corresponding to the initial height; (h) a step in which the high-frequency heating element and the high-frequency coil member move in tandem for a predetermined distance in a horizontal direction; and (i) a step of forming a plurality of via holes by sequentially repeating steps (f) to (h) a plurality of times; A thin glass perforation method by high-frequency heating comprising further including 3. In Claim 2, After the above step (f), A step of waiting for residue formed at the lower part of the via hole of the thin glass to fall onto the recessed portion of the plate glass; and A step of separating the thin glass from the plate glass; A thin glass perforation method by high-frequency heating comprising further including

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