Glass substrate with through hole

Abstract

To provide a glass substrate with a through hole that has improved oxidation resistance for the conductive material inside the through hole, and also have improved conductivity when stacked with other substrates, with an eye toward three-dimensional mounting.SOLUTION: A glass substrate with a through hole includes a glass substrate having a first surface and a second surface opposite the first surface, a plurality of through holes penetrating the first surface and the second surface, vertical conductive portions containing Ag paste filled in the through holes, and Cu cap portions sealing the vertical conductive portions on the first surface and the second surface, and the Cu cap portions serve as lands for connection to other glass substrates. Additionally, the thickness of the Cu cap portions is in the range of 1 to 10 μm.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a glass substrate with a through hole, and more particularly to a glass substrate with a through hole used in a laminated substrate. [Background technology]

[0002] Conventionally, organic substrates have been used as substrates with through-holes. However, with the rapid development of electronic devices, such as smartphones, 3D packaging technologies, such as vertical stacking of semiconductor elements or arranging different types of semiconductor elements on the same substrate, are becoming essential. These technological developments will enable electronic devices to achieve even higher speeds, larger capacities, and lower power consumption. However, conventional organic substrates have significant challenges due to the resin's tendency to absorb moisture and expand / contract with temperature, making it difficult to fabricate fine wiring at scale. Therefore, the development of interposers using silicon or glass as substrates has attracted considerable attention. These materials are less susceptible to moisture absorption and expansion / contraction, making them ideal for fabricating fine wiring. Furthermore, through-hole electrodes, known as TSVs (Through-Silicon Vias) and TGVs (Through-Glass Vias), are formed by filling minute through-holes with conductive materials. These through-holes connect the wiring on the front and back surfaces of the substrate over the shortest distance, achieving excellent electrical properties, such as high signal transmission speeds. Furthermore, since this structure has wiring formed inside, it is an effective mounting method for miniaturizing devices and increasing their density.

[0003] In the core board of Patent Document 1, electrical continuity between the front and back surfaces is established by the conductive material located in the multiple through holes, and the conductive material has no voids, preventing the occurrence of cracks and breaks in the board. In other words, a highly reliable multilayer wiring board is formed by filling the areas separated into the electrolytic plating area and the filled conductive material area with conductive material.

[0004] The substrate of Patent Document 2 has through holes, a protective film is placed on the underside of the substrate, and a resin portion is filled into the through holes. After the protective film is removed, a highly adhesive seed layer is formed on the underside of the substrate.

[0005] The printed circuit board of Patent Document 3 is characterized by having no voids and having through electrodes. The printed circuit board also has one or more insulating layers and wiring layers, each of which has a via. The via is directly connected to the through electrode, and the land laminated on the second surface of the substrate is directly connected to the through electrode. The above-mentioned features make it easier to provide a printed circuit board with a void-free through electrode. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2005-310934 [Patent Document 2] Japanese Patent Application Laid-Open No. 2012-114400 [Patent Document 3] Japanese Patent Application Laid-Open No. 2015-156424 Summary of the Invention [Problem to be solved by the invention]

[0007] The descriptions and disclosures in Patent Documents 1 to 3 can resolve the problems within the substrate. However, in the case of Cu paste, the resistance is relatively high and Cu is easily oxidized. For this reason, changes to the material are being considered. In addition, in the Cu plating process, plating is applied to both the front and back surfaces of the substrate, requiring an additional process of polishing to remove the plating.

[0008] In view of the above-mentioned problems, the present invention aims to provide a glass substrate with through holes that has improved oxidation resistance of the conductive material in the through holes and that has improved conductivity when stacked on other substrates with a view to three-dimensional packaging. [Means for solving the problem]

[0009] The glass substrate with through holes of the embodiment is characterized by comprising a glass substrate having a first surface and a second surface opposite to the first surface, and having a plurality of through holes penetrating the first surface and the second surface, upper and lower conductive portions containing Ag paste and filled in the through holes, and Cu cap portions that seal the upper and lower conductive portions on the first surface side and the second surface side, respectively, and the Cu cap portions serve as land portions for connection to other glass substrates.

[0010] Furthermore, in the glass substrate with through holes, the Cu cap portion may prevent the intrusion of liquids or solids, and may also serve as a land portion to extend the connection area for connection to other glass substrates on the first and second surfaces. The Cu cap portion may be made of Cu, and may have a Ti thin film portion of 0.1 μm or less as an adhesive layer between the Cu cap portion and the glass substrate to ensure close contact with the glass substrate. Additionally, the film thickness of the Cu cap portion may be in the range of 1 to 10 μm. [Effects of the Invention]

[0011] The glass substrate with through holes of the present invention comprises a glass substrate having a first surface and a second surface opposite the first surface, and having a plurality of through holes penetrating the first surface and the second surface, upper and lower conductive portions containing Ag paste and filled in the through holes, and Cu cap portions sealing the upper and lower conductive portions on the first surface side and the second surface side, respectively, and the Cu cap portions serve as land portions for connection to other glass substrates, thereby increasing the oxidation resistance of the conductive material in the through holes and further increasing the conductivity when stacked with other substrates with an eye toward three-dimensional implementation. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a partial cross-sectional schematic view showing a glass substrate with a through hole according to an embodiment. [Figure 2] 2(a) is a schematic plan view of the glass substrate with through holes of FIG. 1, and FIG. 2(b) is a schematic partial cross-sectional view thereof. [Figure 3] 1A is a schematic plan view of a glass substrate with through holes according to another embodiment, and FIG. 1B is a schematic partial cross-sectional view thereof. [Figure 4] 1A is a first schematic plan view of an example of the shape of a Cu cap portion of a glass substrate with a through hole, FIG. 1B is a second schematic plan view, and FIG. 1C is a third schematic plan view. DETAILED DESCRIPTION OF THE INVENTION

[0013] Hereinafter, a glass substrate with a through hole for use in a laminated substrate according to an embodiment will be described.

[0014] In an embodiment, Ag paste is used in the upper and lower conductive portions of a glass substrate with through holes. Ag paste has a lower resistance and is less susceptible to oxidation than Cu paste, making it possible to manufacture highly reliable glass substrates with through holes. Ag paste has better productivity than Cu plating and is not dependent on the hole diameter or plating filling speed, thereby improving the efficiency of the manufacturing process.

[0015] In this embodiment, a Cu cap portion (i.e., a lid and a land portion) is formed to seal the upper and lower conductive portions. The Cu cap portion also functions as a land portion that expands the connection area with the laminated substrate (another glass substrate). Specifically, the Cu cap portion is configured to allow air bubbles generated from residual organic matter, etc., to escape during a high-temperature reliability test. In this embodiment, the high-temperature reliability test is performed under temperature conditions (approximately 260°C) specified in Japanese Industrial Standard JIS C 5012:1993, in which the substrate is immersed in an immersion liquid such as silicone oil for approximately 30 minutes. Next, the substrate is transferred to the next step at a temperature of 20±15°C within 15 minutes. After that, the substrate is treated in an immersion liquid such as an organic solvent at a temperature of 20±15°C for approximately 20 minutes, and then transferred at a temperature of 20±15°C within 15 minutes. Furthermore, Cu is used as the material for the Cu cap portion. If necessary, a Ti thin film portion is provided as an adhesion layer on the glass substrate side of the Cu cap portion to ensure adhesion between the Cu cap portion and the glass substrate. The Ti thin film portion has a thickness of 0.1 μm or less, and the Cu cap portion has a thickness in the range of 1 to 10 μm.

[0016] FIG. 1 is a cross-sectional view of a main portion of a glass substrate 10 with a through hole. The glass substrate 10 of this embodiment has a first surface 11 and a second surface 12 facing the first surface 11. A plurality of through holes 13 are formed in the glass substrate 10, penetrating the first surface 11 and the second surface 12. Ag paste is filled into each of the through holes 13, ensuring electrical conductivity in the thickness direction from the first surface 11 to the second surface 12 of the glass substrate 10, thereby forming vertical conductive portions 15. Cu cap portions 20 (21, 22) cover the open ends of the through holes 13 filled with Ag paste. One surface of the glass substrate 10 (insulating member) serves as a main surface (first surface 11) for mounting a semiconductor element, and the opposite surface (second surface 12) serves as an external connection surface for connection to other components. A plurality of electrode layers for mounting the semiconductor element are formed on the main surface, and a plurality of electrode layers for connection to other components are formed on the external connection surface. The glass substrate 10 with a through hole is also used for stacking with other glass substrates 10 with through holes. Therefore, the Cu cap portion 20 of the glass substrate 10 with a through hole functions as a land portion 23 that widens the connection area (connection margin) with other glass substrates 10 with a through hole. In the Cu cap portion 20, a Cu cap portion 21 is attached to the first surface 11, and a Cu cap portion 22 is attached to the second surface 12.

[0017] The Cu cap portions 20 (21, 22) attached to the glass substrate 10 with through holes of the embodiment function as land portions that expand the connection margin with the laminated substrate. When a conductive layer is formed on the inner surface of the through hole 13, the smallest hole portion is filled with a conductive material (Ag paste). This prevents the phosphor and / or protective resin from leaking to the opposite side through the through hole 13. In the glass substrate 10 with through holes of the embodiment, the Cu cap portions 20 (21, 22) have an upper limit film thickness of 10 μm or less, enabling high-density wiring. Furthermore, the Cu cap portions 20 (21, 22) function as land portions 23, expanding their area, improving connectivity with laminated substrates and other glass substrates 10 with through holes. Furthermore, the presence of the Cu cap portions 20 prevents liquid and solid contaminants from entering the through hole 13.

[0018] In the embodiment, when the diameter of the through hole 13 of the glass substrate 10 with through holes is more than twice the upper limit of the thickness of the through electrode pattern (Cu cap portion 20), the through electrode pattern may have a cylindrical shape with a hollow center line along the longitudinal direction of the through hole. Furthermore, when the thickness is less than twice the upper limit of the thickness, the through electrode pattern preferably has a cylindrical shape with the through hole filled with the conductive material. Furthermore, if necessary, a Ti thin film portion 30 is interposed to ensure close contact between the Cu cap portion 20 (21, 22) and the glass substrate 10. The Ti thin film portion 30 serves as an adhesive layer on the glass substrate 10 side of the Cu cap portion 20.

[0019] The glass substrate 10 with through holes according to the embodiment is characterized by including a Cu cap portion 20 serving as a land portion 23 that widens the connection margin with a laminated substrate or another glass substrate 10 with through holes. This configuration improves the reliability of the glass substrate 10 with through holes and enables high-density mounting. Furthermore, the glass substrate 10 with through holes according to the embodiment may have bump conductors formed to protrude from the underside of the conductor circuit of the upper-layer circuit board and bump conductors formed to protrude from the upper surface of the conductor circuit of the lower-layer circuit board, which are joined and integrated at their tips within a through hole formed in an insulating base material to form columnar conductors, thereby forming a conductive structure between the respective conductor circuits. This configuration enables the glass substrate 10 with through holes to be made high-density and thin, making it suitable for use in the manufacture of semiconductor modules with excellent connection reliability.

[0020] Furthermore, the through electrodes (vertical conductive portions 15) according to the embodiment can be formed with finer and narrower pitches than those formed on printed wiring boards generally used in post-wall waveguides, and therefore can exhibit a shielding effect against higher frequency electromagnetic waves. Furthermore, the use of the vertical conductive portions can ensure conductivity inside the through holes 13 after filling with Ag paste.

[0021] The glass substrate 10 with through holes according to the embodiment is used for mounting a semiconductor chip, and a conductive film covering the entire back surface of the cap substrate may be formed. The glass substrate 10 with through holes configured in this manner allows for high-density wiring, improving the signal transmission performance of the semiconductor chip. Furthermore, since a conductive film covering the entire back surface of the cap substrate is formed, heat generated by the semiconductor chip is efficiently dissipated, thereby solving the problem of heat generation during high-speed operation.

[0022] The glass substrate 10 with through holes of this embodiment has a semiconductor circuit covered with an insulating film, and at least a portion of the bump portion is formed by this insulating film. Furthermore, the Cu cap portion 20 that seals the vertical conductive portion 15 has a film thickness of 1 μm or more and 10 μm or less, preferably 3 μm or more and 7 μm or less, thereby ensuring high reliability. Furthermore, the vertical conductive portion 15, in which the through holes are filled with Ag paste, has high conductivity, enabling high-speed signal transmission.

[0023] A method for manufacturing a glass substrate 10 with through holes according to an embodiment will be described. Through holes 13 (also called via portions) are formed in a glass substrate 102 with through holes. This allows for the formation of land portions 23 that widen the connection margin with the laminated substrate while also forming the through holes 13, enabling a higher density circuit design. The through holes 13 are formed by known techniques such as laser irradiation and glass corrosion by etching.

[0024] In the embodiment, the thickness of the Cu cap portion 20 that seals the vertical conduction portion 15 is 1 μm or more and 10 μm or less, thereby forming a land portion 23 that widens the connection margin with a laminated substrate or another glass substrate 10 with a through hole. This improves the connectivity with a laminated substrate or another glass substrate 10 with a through hole, making it possible to provide a highly reliable glass substrate 10 with a through hole.

[0025] In the embodiment, when the porous structure is formed by sintering high-melting-point metal particles, the porous structure in the vertical conductive portion 15 of the glass substrate 10 with through holes is susceptible to strain fracture because it is subjected to tensile and compressive stresses from the surrounding substrate due to temperature changes that occur when a low-resistance metal is infiltrated into the formed porous structure. To address this problem, in the embodiment, the Cu cap portion 20 is the land portion 23, which widens the connection margin and makes it possible to prevent fracture of the porous structure.

[0026] As shown in the plan view (a) and cross-sectional view (b) of FIG. 2, a glass substrate 10 with through holes is provided with multiple through holes 13, and the holes are filled with Ag paste to form vertical conductive portions 15. The holes are then sealed with Cu cap portions 20, thereby forming a glass substrate 10 with through holes. While conventional methods require heating, this embodiment eliminates the need for heating, simplifying the manufacturing process. Furthermore, the central portion of the Cu cap portion 20 (shown as Cu cap portion 21 on the first surface 11 in the figure) may be connected to the openings of the through holes 13 on the first and second surfaces. Even after filling and firing the paste containing Ag, residual organic matter may remain in the paste. During reliability testing at high temperatures, such as 200°C or higher, residual organic matter may expand and generate bubbles. In this case, forming a ring-shaped Cu cap portion (lid and land portion), such as that shown in FIG. 3, allows bubbles generated from residual organic matter to escape during high-temperature testing.

[0027] The shape of the Cu cap portion 20 is not particularly limited. According to the plan view of FIG. 3(a) and the cross-sectional view of FIG. 3(b), the Cu cap portion 20 may have holes at the upper and lower ends of the Ag paste vertical conductive portion 15. In the illustrated example, the Cu cap portion 20 (21) is annular. Furthermore, as shown in FIG. 4, the Ag paste vertical conductive portion 15 sealed by the Cu cap portion 20 may have a plate-like shape (plan view of FIG. 4(a)), a shape in which multiple vertical conductive portions 15 are sealed by a single Cu cap portion 20 (plan view of FIG. 4(b)), or a rectangular column shape (plan view of FIG. 4(c)). Even in the case of FIG. 4, a cap structure for allowing bubbles generated from residual organic matter contained in the Ag paste to escape may be formed by appropriately forming a void for allowing bubbles to escape, such as a hole in the Cu cap portion 20 itself, as shown in FIG. 3 (not shown). Furthermore, the holes in the Cu cap portion 20 itself do not need to be formed in both the upper and lower Cu cap portions 20, and may be formed on only one side.

[0028] The glass substrate 10 with through holes according to the embodiment is characterized in that the Cu cap portion 20 also serves as a land portion 23 that widens the connection margin with a laminated substrate or another glass substrate 10 with through holes. The material of the Cu cap portion 20 is essentially Cu. Alternatively, a low-melting-point metal such as Sn or Sn-Ag may be used, and bonding may be performed by pressure bonding. The glass substrate 10 with through holes configured in this manner contributes to the realization of high-density electronic circuits.

[0029] In the glass substrate 10 with through holes of the embodiment, high reliability and high density are achieved by employing a Cu cap portion 20 having a land portion 23 that widens the connection margin with the laminated substrate. In addition, by using Ag paste for the vertical conductive portion 15, conductivity is improved compared to Cu, and the oxidation resistance improves reliability.

[0030] In the embodiment, when the interlayer member is formed from an uncured prepreg, there may be cases where it is not necessary to perform a desmear treatment before filling the through-holes 13 with Ag paste to form the vertical conductive portions 15. However, when the interlayer member is formed from a glass substrate or a hard resin substrate such as epoxy resin, it is desirable to perform a desmear treatment using a chemical removal method in which the interlayer member is immersed in an oxidizing agent such as acid, permanganate, or chromic acid, or a physical removal method using plasma discharge, corona discharge, or the like, in order to ensure connection reliability.

[0031] Methods for forming the land portion 23 of the glass substrate 10 with through holes in the embodiment include filling the inside of the through holes 13 with Ag paste to form the upper and lower conductive portions 15, and then polishing and removing the conductive layer and the resin filled in the through holes down to the surface of the glass substrate 10 to expose the upper and lower ends of the through electrodes to form lands, and patterning the conductive layer located at the upper and lower ends of the through electrodes to form lands.

[0032] The manufacturing method of the glass substrate 10 with through holes according to the embodiment may include a planarizing step and a seed layer forming step. The planarizing step may include attaching a first protective sheet to one side of the substrate on which the through holes 13 are formed and closing one opening of the through holes to which the first protective sheet is attached with a temporary filler, thereby planarizing one side of the device substrate. The seed layer forming step may include removing the first protective sheet and then forming a seed layer as a current supply path on one side of the planarized device substrate.

[0033] The glass substrate 10 with a through hole according to the embodiment has land portions 23 as Cu cap portions 20 (21, 22) that widen the connection margin (contact area, connection region) with a laminated substrate or another glass substrate 10 with a through hole, thereby improving the connectivity with the laminated substrate or the like. Furthermore, the shrinkage rate after firing is suppressed, so that the substrate shrinkage is suppressed. The Cu cap portion 20 has a film thickness of 1 μm or more and 10 μm or less, and serves as the land portion 23 that widens the connection margin with the laminated substrate. The shrinkage rate after firing may be approximately +2.6% to +3.0%.

[0034] The glass substrate 10 with through holes of the embodiment includes a Cu cap portion 20 equipped with a land portion 23 that widens the connection margin with a laminated substrate or another glass substrate 10 with through holes. This prevents the compressive stress of the wiring pattern from becoming greater than the adhesion force between the substrate and the wiring pattern during a high-temperature / low-temperature cycle test of the wiring circuit board, causing the through electrode pattern and the wiring pattern to peel off from the substrate, thereby damaging the wiring circuit board.

[0035] The glass substrate 10 with a through hole according to the embodiment includes a glass substrate, a vertical conductive portion 15, and a Cu cap portion 20. The vertical conductive portion 15 is filled into the through hole 13 using Ag paste to plug it. Thereafter, volatile components in the Ag paste are removed by, for example, heating using infrared rays, hot air, a high-temperature atmosphere (such as a nitrogen reflow oven), or contact with a heated jig.

[0036] The Cu cap portion 20 of the glass substrate 10 with a through hole according to the embodiment serves as a land portion 23 that widens the connection margin with a laminated substrate or another glass substrate 10 with a through hole. In this case, the diameter of the middle portion of the through hole 13 may be larger than the diameter of the opening end, or conversely, may be smaller.

[0037] In the glass substrate 10 with through holes of the embodiment, a plurality of through holes 13 are provided in the glass substrate 10, and are filled with Ag paste to form vertical conductive portions 15. The holes are then sealed with a Cu cap portion 20. When filled with a conductive paste such as Ag paste, it is possible to form a land together with a conformal plating film to ensure conductivity with the conductive vias (through holes).

[0038] The viscosity of the Ag paste is adjusted when the Ag paste is injected into the through-hole 13. For example, the diameter of the through-hole 13 may be smaller than 0.1 mm depending on the layout of the wiring on the substrate, and the diameter may be larger than 0.3 mm to improve the electrical characteristics, thermal characteristics, etc.

[0039] The wiring substrate formed from the glass substrate 10 with through holes of the embodiment may be provided with an appropriate cavity or the like (not shown) as needed. Furthermore, the diameters of the through electrodes do not all need to be the same, and some of the through electrodes may be different. Examples of components that need to be separately incorporated in this way include components that are sensitive to heat, such as batteries, components that require transparency in the substrate, such as displays and light-emitting / receiving elements, and bare chips of relatively large elements (ICs).

[0040] In the glass substrate 10 with through holes according to the embodiment, a sealing resin is used to seal the gap between the semiconductor chip and the solid-state device. A light-transmitting support is provided on the top surface of the semiconductor chip, and the gap between the semiconductor chip and the solid-state device, excluding this support, is sealed with the sealing resin. In this manner, the intrusion of air between the semiconductor chip and the solid-state device is suppressed. Furthermore, the use of the light-transmitting support allows light generated from the semiconductor chip to be emitted to the outside, achieving high signal transmission performance. The porosity can also include the area ratio of gaps occurring at the interface. In the embodiment, the porosity is preferably 5% or less.

[0041] In the embodiment of the glass substrate 10 with a through hole, the shape of the land portion 23 formed by the Cu cap portion 20 can be, for example, formed at the same height as the surfaces 11 and 12 of the glass substrate 10, or formed several microns higher than the surfaces 11 and 12 of the glass substrate 10.

[0042] In the glass substrate 10 with through holes of the embodiment, no elemental Al remains in the Au-Al alloy layer at the bonding surface (interface, i.e., land portion 23) below the connection portion of the glass substrate 10 with through holes, enabling stable operation even in a high-temperature usage environment. The glass substrate 10 with through holes configured in this manner has higher connection reliability than conventional circuit boards in which the wall surfaces inside the through holes 13 are uneven. Furthermore, the width of the land portion 23 also improves connection reliability with laminated substrates or other glass substrates 10 with through holes.

[0043] The glass substrate 10 with through holes according to the embodiment may have an inorganic adhesive layer. The inorganic adhesive layer may be a single layer film made of a single material selected from the group consisting of tin oxide, indium oxide, zinc oxide, nickel, nickel phosphorus, chromium, chromium oxide, aluminum nitride, copper nitride, aluminum oxide, tantalum, titanium, and copper, or a laminated film of two or more layers made by combining two or more materials. The glass substrate 10 with through holes configured in this manner is highly reliable and can be manufactured at low costs. Furthermore, materials such as tin oxide, indium oxide, zinc oxide, and nickel phosphorus can be used as the material for the inorganic adhesive layer, enabling high-density mounting.

[0044] The glass substrate 10 with through holes according to the embodiment is suitable for applications such as high-frequency signal transmission, and has improved high-frequency signal transmission characteristics. Furthermore, the method for manufacturing the glass substrate 10 with through holes according to the embodiment is simpler than conventional manufacturing methods, and costs can be reduced. Furthermore, the glass substrate 10 with through holes according to the embodiment is suitable for high-density mounting, and can be made smaller and lighter. [Explanation of symbols]

[0045] 10 Glass substrate with through holes 11 First surface of glass substrate 12 Second surface of glass substrate 13 Through hole 15 Upper and lower conductive parts 20, 21, 22 Cu cap part 23 Land Department 30 Ti thin film part

Claims

1. a glass substrate having a first surface and a second surface opposite to the first surface, the glass substrate having a plurality of through holes penetrating the first surface and the second surface; a vertical conductive portion containing Ag paste and filled in the through hole; a Cu cap portion that seals the vertical conductive portion on the first surface side and the vertical conductive portion on the second surface side, The Cu cap portion serves as a land portion for connection to another glass substrate. A glass substrate with a through hole.

2. 2. The glass substrate with a through hole according to claim 1, wherein the Cu cap portion prevents intrusion of liquids or solids, and the Cu cap portion serves as the land portion to extend a connection area for connection to other glass substrates on the first surface and the second surface.

3. The glass substrate with a through hole according to claim 1, characterized in that the Cu cap portion is made of Cu, and the Cu cap portion has a Ti thin film portion of 0.1 μm or less as an adhesion layer between the Cu cap portion and the glass substrate to ensure close contact with the glass substrate.

4. 2. The glass substrate with a through hole according to claim 1, wherein the thickness of the Cu cap portion is in the range of 1 to 10 μm.

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