Silica glass substrate, glass substrate, and metallized substrate

Abstract

The present invention relates to a glass substrate having a specific composition and a silica glass substrate wherein the root mean square height Rq of the substrate surface is 1 nm-300 nm inclusive, and the plate thickness is 10 μm-2 mm inclusive.

Description

Silica glass substrate, glass substrate and metallized substrate

[0001] The present invention relates to a silica glass substrate, a glass substrate, and a metallized substrate.

[0002] In electronic devices such as communication devices such as mobile phones, smartphones, personal digital assistants, and Wi-Fi devices, as well as surface acoustic wave (SAW) devices, radar components, and antenna components, signal frequencies are becoming higher in order to increase communication capacity, speed, etc. Circuit boards used in such electronic devices for high-frequency applications use metallized substrates, which are formed by metallizing insulating substrates such as resin substrates and glass ceramic substrates.

[0003] Insulating substrates used in high-frequency devices are required to reduce transmission loss due to dielectric loss, conductor loss, etc., in order to ensure characteristics such as the quality and strength of high-frequency signals. Among these insulating substrates, resin substrates have low rigidity due to their characteristics. Therefore, resin substrates are difficult to apply when rigidity (strength) is required for semiconductor package products. Glass-ceramic substrates have the drawback of being difficult to improve the surface smoothness, which tends to increase conductor loss due to the conductor formed on the substrate surface.

[0004] On the other hand, glass substrates have the advantages of being highly rigid, making it easy to miniaturize and thin packages, having excellent surface smoothness, and being easy to enlarge as a substrate itself.However, the metallized layer formed on the surface of a glass substrate has the problem of being easily peeled off due to poor adhesion between the glass and the metal film.

[0005] Regarding the problem of adhesion between glass and metal films, Non-Patent Document 1 reports a method of forming a highly adhesive metal layer on the surface of glass by adsorbing a palladium catalyst through a reaction between a zinc oxide film and palladium chloride and reducing it with a reducing agent, and a method of reducing metal ions by irradiating the zinc oxide with light, taking advantage of the optical semiconductor properties of zinc oxide. Patent Document 1 also discloses a chemical plating technique for ensuring adhesion between a substrate and a metal film.

[0006] Japanese Patent Application Publication No. 2011-195896

[0007] Electronics Packaging Technology (Vol. 11, No. 6, P32, 1995)

[0008] However, the above-mentioned method requires special equipment and has the problem of low productivity due to the complicated and lengthy process. Therefore, there is a demand for a metallized glass substrate that does not require a special metallization process and has high adhesion between the glass substrate and the metal film.

[0009] Furthermore, the thickness of the substrate is important for reducing transmission loss in the high-frequency band. Generally, to suppress noise, the substrate thickness is designed to be smaller than λ / 2, where λ is the wavelength of the high frequency. For example, when designing a device using a silica glass substrate or a glass substrate at a high frequency of 10 GHz, λ / 2 is 7.7 mm, so a substrate with a smaller thickness is required. The thinner the substrate, the smaller the transmission loss due to the noise suppression effect.

[0010] Therefore, an object of the present invention is to provide an insulating substrate that does not require a special metallization process, that has a metallized layer that is not easily peeled off even when the substrate surface is metallized, and that has small high-frequency transmission loss.

[0011] The present inventors focused on silica glass substrates and glass substrates, which have low dielectric loss, as insulating substrates to be metallized, and discovered that by setting the surface roughness Rq of silica glass substrates and glass substrates within a specific range, the metallized layer formed on the substrate surface is less likely to peel off, even when the substrate surface is metallized, and by setting the thickness to 2 mm or less, an insulating substrate with low high-frequency transmission loss can be provided, thereby completing the present invention.

[0012] That is, one embodiment of the present invention relates to a silica glass substrate and a glass substrate of a specific composition, in which the root mean square height Rq of the substrate surface is 1 nm or more and 300 nm or less, and the thickness is 10 μm or more and 2 mm or less. Another embodiment of the present invention relates to a metallized substrate in which a metallized layer is provided on the surface of the silica glass substrate or the glass substrate.

[0013] According to one embodiment of the present invention, it is possible to provide a silica glass substrate and a glass substrate as insulating substrates that do not require a special metallization process, that the metallized layer formed is not easily peeled off even when the substrate surface is metallized, and that have reduced high-frequency transmission loss.

[0014] Fig. 1 is a schematic cross-sectional view of a silica glass substrate according to one embodiment of the present invention. Fig. 2 is a schematic cross-sectional view of a metallized substrate according to one embodiment of the present invention. Fig. 3 is a Raman spectrum of the silica glass substrate according to one embodiment of the present invention.

[0015] The present invention will be described in detail below, but the present invention is not limited to the following embodiments and can be modified as desired without departing from the spirit of the present invention. Furthermore, the use of "to" to indicate a numerical range means that the numerical values ​​before and after it are included as the lower and upper limits. The embodiments shown in the drawings are schematic for the purpose of clearly explaining the present invention and do not necessarily accurately represent the size or scale of an actual device, etc. In this specification, mass % and weight %, and mass ppm and weight ppm are synonymous.

[0016] <Silica Glass Substrate> A silica glass substrate according to one embodiment of the present invention (hereinafter also simply referred to as the silica glass substrate of this embodiment) is characterized in that the root mean square height Rq of the substrate surface is 1 nm or more and 300 nm or less, and the substrate thickness is 10 μm or more and 2 mm or less. Figure 1 shows a schematic cross-sectional view of a silica glass substrate 10 according to this embodiment.

[0017] (Rq) It is important that the root mean square height Rq of the substrate surface of the silica glass substrate of this embodiment is 1 nm or more and 300 nm or less. When the Rq is 1 nm or more and 300 nm or less, the adhesion between the substrate and the metallized layer formed on the substrate surface is sufficient, and the metallized layer is less likely to peel off from the substrate surface.

[0018] In the silica glass substrate of this embodiment, the root mean square height Rq of the substrate surface is 1 nm or more, preferably 5 nm or more, more preferably 10 nm or more, and particularly preferably 20 nm or more, and is 300 nm or less, preferably 200 nm or less, more preferably 150 nm or less, and particularly preferably 100 nm or less.

[0019] Here, the root mean square height Rq of the substrate surface is defined in JIS B 0601 (2013), and represents the root mean square over a reference length, meaning the standard deviation of the surface roughness of the substrate. The root mean square height Rq of the substrate surface can be measured using, for example, a Surfcom 1400D manufactured by Tokyo Seimitsu Co., Ltd.

[0020] In the silica glass substrate of this embodiment, the Rq of the substrate surface can be set to 1 nm or more and 300 nm or less by, for example, manufacturing the silica glass substrate by a sintering method, as described below. Manufacturing a silica glass substrate by a sintering method makes it easy to control the surface properties, so it is easy to adjust Rq to the above range. Another method is to polish synthetic quartz glass or fused quartz glass to obtain a desired surface roughness.

[0021] (Thickness) It is important that the silica glass substrate of this embodiment has a thickness of 10 μm or more and 2 mm or less. By having the thickness of 10 μm or more and 2 mm or less, high frequency transmission loss can be reduced.

[0022] The thickness of the silica glass substrate of this embodiment is 10 μm or more, preferably 50 μm or more, more preferably 100 μm or more, and particularly preferably 150 μm or more, and is 2 mm or less, preferably 1 mm or less, more preferably 0.5 mm or less, and particularly preferably 0.2 mm or less.

[0023] (Df) The silica glass substrate of this embodiment has a Df (dielectric loss tangent) of 5.0×10 at 10 GHz. －３ ~1.0 x 10 －５ When the Df is in the above range, the transmission loss of high frequencies can be kept low. The Df is preferably 5.0×10 －４ More preferably, 1.0 x 10 －４More preferably, the following is true: for example, 5.0 × 10 －５ The above Df can be measured by a dielectric resonator method.

[0024] (Defects) The silica glass substrate of this embodiment has defects with an average diameter of 1 μm or more and 100 μm or less within 1 cm ２ Preferably, the number of defects is 500,000 or less per unit area. Here, "defects" refers to heterogeneous phases other than glass, such as crystals and bubbles, observed when measured with an optical microscope. Furthermore, the above-mentioned average diameter refers to the average diameter (average diameter) obtained by connecting two peripheries of defects extracted with image analysis software based on the color and shape of the pattern, selecting the glass portion as the background in an optical microscope image and using the software. Limiting the number of defects to 500,000 or less can prevent Rq from exceeding 300 nm.

[0025] The silica glass substrate of this embodiment has defects with an average diameter of 1 μm or more and 100 μm or less within 1 cm ２ More preferably, the number of particles is 300,000 or less, even more preferably 100,000 or less, and particularly preferably 10,000 or less, and for example, 1,000 or more.

[0026] Furthermore, in the silica glass substrate of this embodiment, defects having an average diameter of 5 μm or more and 100 μm or less are formed within 1 cm. ２ More preferably, the number of particles per particle is 5,000 or less, even more preferably 3,000 or less, and particularly preferably 2,000 or less, and for example, 50 or more.

[0027] Furthermore, in the silica glass substrate of this embodiment, defects having an average diameter of 1 μm or more and 5 μm or less are formed within 1 cm. ２ More preferably, the number of particles per particle is 30,000 or less, even more preferably 15,000 or less, and particularly preferably 10,000 or less, and may be, for example, 100 or more.

[0028] (H ２ O concentration) The silica glass substrate of this embodiment has a H converted from β-OH in the glass. ２ The O concentration is preferably less than 100 ppm by mass. ２When the O concentration is less than 100 mass ppm, the amount of water in the glass is sufficiently small, so that the transmission loss of high frequencies can be further reduced. ２ The O concentration is preferably less than 100 ppm by mass, more preferably 50 ppm by mass or less, further preferably 20 ppm by mass or less, particularly preferably 10 ppm by mass or less, and is, for example, 0.5 ppm by mass or more. ２ The O concentration can be obtained from the spectrum measured using an FT-IR (Fourier transform infrared spectrophotometer) using the following formula: ２ O concentration = ((|A1-A2| / t))*M / (10ερ)*10000 [mass ppm] A1: Reference wave number 3900-4000 cm －１ A2: Hydroxyl group absorption wave number 3400-3800 cm －１ t: Plate thickness (mm) ε: Molar absorption coefficient of β-OH 8.6 (L / mol / mm) ρ: Specific gravity 2.2 (g / cm ３ ) M:H ２ O molecular weight 18 (g / mol)

[0029] (Composition) In this embodiment, the silica glass substrate is also called quartz glass, and is substantially made of SiO ２ The substrate is made of glass consisting essentially of SiO ２ The glass consisting of only SiO ２ In addition, for example, Na, K, Ca, C, Zr, Ti, Al, Mg, Fe, Zn, etc. may be contained, and the term "glass" refers to a glass in which the content of each of these elements is on the order of ppm by mass.

[0030] (Total Content of Na, K, and Ca) The silica glass substrate of this embodiment preferably has a total content of Na, K, and Ca of 0.1 ppm by mass or more and 50 ppm by mass or less. By having the total content of Na, K, and Ca of 0.1 ppm by mass or more and 50 ppm by mass or less, microcrystals can be suppressed, so that the surface roughness Rq can be controlled to 300 nm or less, and high-frequency transmission loss can be further reduced. The total content of Na, K, and Ca is more preferably 20 ppm by mass or less, even more preferably 10 ppm by mass or less, particularly preferably 5 ppm by mass or less, and still more preferably 0.3 ppm by mass or more, particularly preferably 0.5 ppm by mass or more.

[0031] (C Content) The silica glass substrate of this embodiment preferably has a C content of 5 ppm by mass or less. By setting the C content to 5 ppm by mass or less, the amount of impurities can be reduced and microcrystals can be suppressed, thereby controlling the surface roughness Rq to 300 nm or less and further reducing high-frequency transmission loss. The C content is more preferably 4 ppm by mass or less, and even more preferably 3 ppm by mass or less, and may be, for example, 0.5 ppm by mass or more. In order to set the C content in the silica glass substrate of this embodiment within the above range, for example, a method that does not use a resin component as a raw material can be mentioned.

[0032] (Zr Content) The silica glass substrate of this embodiment preferably has a Zr content of 50 mass ppm or less. By having the Zr content of 50 mass ppm or less, the amount of impurities can be reduced and microcrystals can be suppressed, so that the surface roughness Rq can be controlled to 300 nm or less, and high-frequency transmission loss can be further reduced. The Zr content is more preferably 10 mass ppm or less, even more preferably 1 mass ppm or less, and particularly preferably 0.2 mass ppm or less, and may be, for example, 0.1 mass ppm or more. To set the Zr content in the silica glass substrate of this embodiment within the above range, for example, a method of selecting a raw material that does not contain Zr can be mentioned.

[0033] (Ti Content) The silica glass substrate of this embodiment preferably has a Ti content of 50 mass ppm or less. By having the Ti content of 50 mass ppm or less, the amount of impurities can be reduced and microcrystals can be suppressed, thereby controlling the surface roughness Rq to 300 nm or less and further reducing high-frequency transmission loss. The Ti content is more preferably 30 mass ppm or less, even more preferably 10 mass ppm or less, particularly preferably 3 mass ppm or less, and may be, for example, 0.1 mass ppm or more. To set the Ti content in the silica glass substrate of this embodiment within the above range, for example, a method of selecting a raw material that does not contain Ti can be mentioned.

[0034] (Al Content) The silica glass substrate of this embodiment preferably has an Al content of 50 mass ppm or less. By setting the Al content to 50 mass ppm or less, microcrystals can be suppressed, so that the surface roughness Rq can be controlled to 300 nm or less, and high-frequency transmission loss can be further reduced. The Al content is more preferably 30 mass ppm or less, even more preferably 10 mass ppm or less, and particularly preferably 3 mass ppm or less, and may be, for example, 0.1 mass ppm or more. To set the Al content in the silica glass substrate of this embodiment within the above range, for example, a method of selecting a raw material that does not contain Al can be mentioned.

[0035] The silica glass substrate of this embodiment preferably satisfies one or more of the following: a total content of Na, K, and Ca: 0.1 mass ppm to 50 mass ppm; a C content: 5 mass ppm or less; a Zr content: 50 mass ppm or less; a Ti content of 50 mass ppm or less; and an Al content: 50 mass ppm or less, more preferably satisfies two or more, even more preferably satisfies three or more, even more preferably satisfies four or more, and particularly preferably satisfies all five. ２ It is even more preferable that the O concentration be less than 100 ppm by mass.

[0036] (Etching rate (relative value)) The etching rate of the silica glass substrate of this embodiment is ３When the silica glass substrate is immersed in an aqueous solution containing 7 wt % HF, the relative value of the etching rate of the synthetic quartz glass, taken as 1, is preferably greater than 1. Having an etching rate of greater than 1 allows for a faster etching rate when adjusting the hole size by etching after laser drilling. The relative value of the etching rate of the silica glass substrate of this embodiment, taken as 1 for the synthetic quartz glass, is more preferably 1.1 or greater, even more preferably 1.2 or greater, and particularly preferably 1.3 or greater. Here, synthetic quartz glass refers to synthetic quartz glass produced by the VAD method (vapor-phase axial deposition method). To achieve the above-described range for the silica glass substrate of this embodiment, the aforementioned D2 / PH can be set to 0.10 or greater, or D1 / PH can be set to 0.40 or greater. The etching rate of the silica glass substrate of this embodiment can be measured, for example, by masking the silica glass substrate with Kapton tape and etching it in an aqueous solution containing 8 wt % HF, HNO . ３ After immersion in a 7 wt % aqueous solution for 5 hours, the mask is removed and the etching amount can be calculated from the step measurement results using a stylus surface profiler (Dektak 150, manufactured by Bruker). Specifically, since the masked portion is not etched, the etching amount can be calculated by measuring the step at the boundary between the masked and unmasked portions.

[0037] (Raman Spectrum) The silica glass substrate of this embodiment has a Raman spectrum of 370 cm －１ , 390 cm －１ , and 450 cm －１ The height (PH) of the composite peak of the three Si-O fundamental vibrations at 605 cm －１Preferably, the ratio (D2 / PH) of the D2 peak intensity derived from the three-membered ring structure to the D2 peak intensity derived from the three-membered ring structure is 0.10 or greater. When the D2 / PH ratio is 0.10 or greater, the etching rate can be increased when adjusting the hole size by etching after laser drilling. In the Raman spectrum shown in FIG. 3, the peak marked D2 is a peak derived from the three-membered ring structure, and the portion marked D2 corresponds to its peak intensity (D2). The peak indicated by the solid line is a composite peak of the Si—O fundamental vibration, and the portion marked PH corresponds to its peak height (PH). The D2 / PH ratio is preferably 0.10 or greater, more preferably 0.15 or greater, even more preferably 0.17 or greater, particularly preferably 0.18 or greater, and may be, for example, 0.25 or less. One way to achieve the D2 / PH ratio within the above range is to prepare silica glass with a low fictive temperature by, for example, rapid cooling.

[0038] The silica glass substrate of this embodiment has a Raman spectrum of 370 cm －１ , 390 cm －１ , and 450 cm －１ The height (PH) of the composite peak of the three Si-O fundamental vibrations at 490 cm －１ Preferably, the ratio (D1 / PH) of the D1 peak intensity derived from the four-membered ring structure to the D1 peak intensity derived from the four-membered ring structure is 0.40 or more. When the D1 / PH is 0.40 or more, the etching rate can be increased. As shown in FIG. 3, the peak marked with D1 is a peak derived from the four-membered ring structure, and the portion marked with D1 corresponds to its peak intensity (D1). The peak shown with a solid line is a composite peak of the Si—O fundamental vibration, and the portion marked with PH corresponds to its peak height (PH). The D1 / PH is preferably 0.40 or more, more preferably 0.50 or more, even more preferably 0.55 or more, even more preferably 0.57 or more, and may be, for example, 0.7 or less. To set the D1 / PH within the above range, for example, a method of producing silica glass with a low fictive temperature by rapid cooling or the like can be used.

[0039] In the silica glass substrate of this embodiment, it is more preferable that the D2 / PH is 0.10 or more and the D1 / PH is 0.40 or more.

[0040] The Raman spectrum was obtained using a microscopic laser Raman spectrometer, measuring a cylindrical region 5 μm below the surface of the silica glass substrate of this embodiment, with a diameter of about 3 μm and a length of about 3 μm.

[0041] <Glass Substrate> A glass substrate according to one embodiment of the present invention (hereinafter also simply referred to as the glass substrate of this embodiment) is characterized in that the root mean square height Rq of the substrate surface is 1 nm or more and 300 nm or less, and the plate thickness is 10 μm or more and 2 mm or less. Fig. 1 shows a schematic cross-sectional view of a silica glass substrate 10 according to this embodiment, but the same applies when a glass substrate is used instead of the silica glass substrate.

[0042] (Rq) It is important that the root mean square height Rq of the substrate surface of the glass substrate of this embodiment is 1 nm or more and 300 nm or less. When the Rq is 1 nm or more and 300 nm or less, the adhesion between the substrate and the metallized layer formed on the substrate surface is sufficient, and the metallized layer is less likely to peel off from the substrate surface.

[0043] In the glass substrate of this embodiment, the root mean square height Rq of the substrate surface is 1 nm or more, preferably 5 nm or more, more preferably 10 nm or more, and particularly preferably 20 nm or more, and is 300 nm or less, preferably 200 nm or less, more preferably 150 nm or less, and particularly preferably 100 nm or less.

[0044] Here, the root mean square height Rq of the substrate surface is defined in JIS B 0601 (2013), and represents the root mean square over a reference length, meaning the standard deviation of the surface roughness of the substrate. The root mean square height Rq of the substrate surface can be measured using, for example, a Surfcom 1400D manufactured by Tokyo Seimitsu Co., Ltd.

[0045] In the glass substrate of this embodiment, in order to set the Rq of the substrate surface to 1 nm or more and 300 nm or less, for example, a method of manufacturing a glass substrate by a sintering method, as described below, can be mentioned. Since the surface property is easily controlled by manufacturing a glass substrate by a sintering method, it is easy to adjust Rq to the above range. Another method is to polish a plate glass produced by a melting method to obtain a desired surface roughness Rq. Examples of the method of manufacturing the plate glass include a method using a float method, a roll method, a pull-up method, a down-draw method, an overflow fusion down-draw method, an up-draw method, or a Foucault method for the melting process and subsequent hot forming.

[0046] (Thickness) It is important that the glass substrate of this embodiment has a thickness of 10 μm or more and 2 mm or less. By having the thickness of 10 μm or more and 2 mm or less, high frequency transmission loss can be reduced.

[0047] The thickness of the glass substrate of this embodiment is 10 μm or more, preferably 50 μm or more, more preferably 100 μm or more, and particularly preferably 150 μm or more, and is 2 mm or less, preferably 1 mm or less, more preferably 0.5 mm or less, and particularly preferably 0.2 mm or less.

[0048] (Df) The glass substrate of this embodiment has a Df (dielectric loss tangent) of 5.0×10 at 10 GHz. －３ ~1.0 x 10 －５ When Df is in the above range, high frequency transmission loss can be kept low. Df is preferably 4.0×10 －３ More preferably, 3.0 x 10 －３ More preferably, the following is true: for example, 5.0 × 10 －５ The above Df can be measured by a dielectric resonator method.

[0049] (Defects) The glass substrate of this embodiment has defects with an average diameter of 1 μm or more and 100 μm or less within 1 cm ２Preferably, the number of defects is 500,000 or less per unit area. Here, "defects" refers to heterogeneous phases other than glass, such as crystals and bubbles, observed when measured with an optical microscope. Furthermore, the above-mentioned average diameter refers to the average diameter (average diameter) obtained by connecting two peripheries of defects extracted with image analysis software based on the color and shape of the pattern, selecting the glass portion as the background in an optical microscope image and using the software. Limiting the number of defects to 500,000 or less can prevent Rq from exceeding 300 nm.

[0050] The glass substrate of this embodiment has defects with an average diameter of 1 μm or more and 100 μm or less, which are 1 cm ２ More preferably, the number of particles is 300,000 or less, even more preferably 100,000 or less, and particularly preferably 10,000 or less, and for example, 1,000 or more.

[0051] In addition, the glass substrate of this embodiment has defects with an average diameter of 5 μm or more and 100 μm or less per 1 cm ２ More preferably, the number of particles per particle is 5,000 or less, even more preferably 3,000 or less, and particularly preferably 2,000 or less, and for example, 50 or more.

[0052] In addition, the glass substrate of this embodiment has defects with an average diameter of 1 μm or more and 5 μm or less per 1 cm ２ More preferably, the number of particles per particle is 30,000 or less, even more preferably 15,000 or less, and particularly preferably 10,000 or less, and may be, for example, 100 or more.

[0053] (Composition) The glass substrate in this embodiment has a composition of SiO 2 in mole percent based on oxides. ２ In order to obtain a low-loss substrate, the content of SiO ２ The content of is 60 mol% or more, preferably 72 mol% or more, and more preferably 75 mol% or more. From the viewpoint of increasing the linear expansion coefficient and improving the reliability of the device, the content is less than 100 mol%, preferably 90 mol% or less, more preferably 89 mol% or less, even more preferably 88 mol% or less, and still more preferably 85 mol% or less.

[0054] (B ２ O ３The glass substrate in this embodiment contains, in mole percent on an oxide basis, B ２ O ３ It is preferable that the content of B is 10 to 35 mol %. ２ O ３ The content is preferably 10 mol% or more, more preferably 12 mol% or more, and even more preferably 15 mol% or more. From the viewpoint of weather resistance, the content is preferably 35 mol% or less, preferably 30 mol% or less, and more preferably 25 mol% or less.

[0055] (P ２ O ５ , GeO ２ , CaO, MgO, BaO, Li ２ O, Na ２ O.K. ２ O, SnO ２ , ZnO, and TiO ２ The glass substrate in this embodiment contains, in mole percent on an oxide basis, ２ O ５ , GeO ２ , CaO, MgO, BaO, Li ２ O, Na ２ O.K. ２ O, SnO ２ , ZnO, and TiO ２ It is preferable that the glass further contains at least one of the following, and in this case, the total content thereof is more preferably 1 to 15 mol %. From the viewpoint of lowering the melting point of the glass and improving sinterability, the total content is preferably 1 mol % or more, more preferably 3 mol % or more. Furthermore, from the viewpoint of lowering the dielectric loss, the total content is preferably 15 mol % or less, more preferably 10 mol % or less.

[0056] The content of each of the above components is not particularly limited as long as the total content is 1 to 15 mol %, and is preferably 1 mol % or more, more preferably 2 mol % or more, and even more preferably 3 mol % or more. The content of each component is preferably 15 mol % or less, preferably 12 mol % or less, and more preferably 10 mol % or less.

[0057] The glass substrate in this embodiment contains, in mole percent on an oxide basis, SiO ２ : 60 mol% or more and less than 100 mol%, and in addition, B ２ O ３ : 10 to 35 mol%, and P ２ O ５ , GeO ２ , CaO, MgO, BaO, Li ２ O, Na ２ O.K. ２ O, SnO ２ , ZnO, and TiO ２ It is preferable to satisfy at least one of the following conditions, and more preferable to satisfy both of them: the total of: 1 to 15 mol %.

[0058] (Total Content of Na, K, and Ca) In the glass substrate of this embodiment, the total content of Na, K, and Ca is preferably 0.1 ppm by mass or more and 50 ppm by mass or less. When the total content of Na, K, and Ca is 0.1 ppm by mass or more and 50 ppm by mass or less, microcrystals can be suppressed, so that the surface roughness Rq can be controlled to 300 nm or less, and high-frequency transmission loss can be further reduced. The total content of Na, K, and Ca is more preferably 20 ppm by mass or less, even more preferably 10 ppm by mass or less, particularly preferably 5 ppm by mass or less, and further preferably 0.3 ppm by mass or more, particularly preferably 0.5 ppm by mass or more.

[0059] (C Content) The glass substrate of this embodiment preferably has a C content of 5 ppm by mass or less. By setting the C content to 5 ppm by mass or less, the amount of impurities can be reduced and microcrystals can be suppressed, thereby controlling the surface roughness Rq to 300 nm or less and further reducing high-frequency transmission loss. The C content is more preferably 4 ppm by mass or less, even more preferably 3 ppm by mass or less, and may be, for example, 0.5 ppm by mass or more. To set the C content in the glass substrate of this embodiment within the above range, for example, a method that does not use a resin component as a raw material can be mentioned.

[0060] (Zr Content) The glass substrate of this embodiment preferably has a Zr content of 50 mass ppm or less. By having the Zr content of 50 mass ppm or less, the amount of impurities can be reduced and microcrystals can be suppressed, so that the surface roughness Rq can be controlled to 300 nm or less, and high-frequency transmission loss can be further reduced. The Zr content is more preferably 10 mass ppm or less, even more preferably 1 mass ppm or less, and particularly preferably 0.2 mass ppm or less, and may be, for example, 0.1 mass ppm or more. To set the Zr content in the silica glass substrate of this embodiment within the above range, for example, a method of selecting a raw material that does not contain Zr can be mentioned.

[0061] (Ti Content) The glass substrate of this embodiment preferably has a Ti content of 50 ppm by mass or less. By having the Ti content of 50 ppm by mass or less, the amount of impurities can be reduced and microcrystals can be suppressed, so that the surface roughness Rq can be controlled to 300 nm or less, and high-frequency transmission loss can be further reduced. The Ti content is more preferably 30 ppm by mass or less, even more preferably 10 ppm by mass or less, particularly preferably 3 ppm by mass or less, and may be, for example, 0.1 ppm by mass or more. To set the Ti content in the glass substrate of this embodiment within the above range, for example, a method of selecting a raw material that does not contain Ti can be mentioned.

[0062] (Al Content) The glass substrate of this embodiment preferably has an Al content of 50 ppm by mass or less. By setting the Al content to 50 ppm by mass or less, microcrystals can be suppressed, so that the surface roughness Rq can be controlled to 300 nm or less, and high-frequency transmission loss can be further reduced. The Al content is more preferably 30 ppm by mass or less, even more preferably 10 ppm by mass or less, and particularly preferably 3 ppm by mass or less, and may be, for example, 0.1 ppm by mass or more. To set the Al content in the glass substrate of this embodiment within the above range, for example, a method of selecting a raw material that does not contain Al can be mentioned.

[0063] The glass substrate of the present embodiment preferably satisfies one or more of the following: a total content of Na, K, and Ca of 0.1 ppm by mass or more and 50 ppm by mass or less; a C content of 5 ppm by mass or less; a Zr content of 50 ppm by mass or less; a Ti content of 50 ppm by mass or less; and an Al content of 50 ppm by mass or less; more preferably satisfies two or more of the following; even more preferably satisfies three or more of the following; still more preferably satisfies four or more of the following; and particularly preferably satisfies all five of the following.

[0064] (Etching rate (relative value)) The etching rate of the glass substrate of this embodiment is ３ When the glass substrate is immersed in an aqueous solution of HF:7 wt %, the relative value when the etching rate of the synthetic quartz glass is taken as 1 is preferably greater than 1. By having the relative value exceeding 1, it is possible to increase the etching rate when adjusting the size of the holes by etching after drilling with a laser. The relative value of the etching rate of the glass substrate of this embodiment when the etching rate of the synthetic quartz glass is taken as 1 is more preferably 1.1 or more, even more preferably 1.2 or more, and particularly preferably 1.3 or more. Here, synthetic quartz glass means synthetic quartz glass produced by the VAD method. The etching rate of the glass substrate of this embodiment can be measured, for example, by masking a glass substrate with Kapton tape and etching it in an aqueous solution of HF:8 wt %, HNO . ３ After immersion in a 7 wt % aqueous solution for 5 hours, the mask is removed and the etching amount can be calculated from the step measurement results using a stylus surface profiler (Dektak 150, manufactured by Bruker). Specifically, since the masked portion is not etched, the etching amount can be calculated by measuring the step at the boundary between the masked and unmasked portions.

[0065] <Method for manufacturing silica glass substrate> The method for manufacturing the silica glass substrate of this embodiment is not particularly limited, but it is preferable to obtain the silica glass substrate by sintering a green sheet containing silica. This manufacturing method has the advantage that a substrate of 2 mm or less can be directly obtained without cutting and polishing, and a desired surface roughness Rq can be achieved without post-processing, making it possible to easily produce a silica glass substrate with low loss and resistance to metallization peeling. Below, a method for manufacturing the silica glass substrate of this embodiment using a sintering method will be described as an example, but the silica glass substrate of this embodiment is not limited to one obtained by this manufacturing method.

[0066] Preparation of Slurry Composition As an example of the method for producing a silica glass substrate according to this embodiment, a slurry composition is first prepared. The slurry composition can be obtained by mixing silica powder, a binder, and an organic solvent. In addition, as described below, a dispersant, a plasticizer, an antifoaming agent, etc. can also be mixed. There are no particular limitations on the mixing method, and a conventionally known method can be used.

[0067] (Silica Powder) The type of silica powder is not particularly limited, and examples thereof include silica sand, quartz powder, cristobalite powder, amorphous silica powder, spherical silica powder, etc. The silica powder can be used alone or in combination of two or more.

[0068] The shape of the silica powder may be spherical or non-spherical, such as amorphous or crushed, but spherical is preferred from the viewpoint of packing density. The silica powder may also be subjected to any surface treatment. Examples of surface treatments include treatments that add methacrylic groups, vinyl groups, phenyl groups, trimethylsilyl groups, phenylamino groups, and epoxy groups to the surface of the silica powder.

[0069] The silica powder preferably has a purity of 99.0% or more, more preferably 99.5% or more, and even more preferably 99.8% or more.

[0070] The 50% particle size on a volume basis in the cumulative particle size distribution is D ５０ When the D of the silica powder ５０The D of the silica powder is preferably 80 nm or more and 15 μm or less. ５０ When the D of the silica powder is 80 nm or more, it is easy to adjust the silica solid content of the green sheet to 30 vol % or more. Furthermore, when the solid content is high, densification by sintering is easily promoted, so it is easy to obtain a sintered body with Rq of 300 nm or less. ５０ When the D of the silica powder is 15 μm or less, the firing temperature can be prevented from becoming too high, and a sintered body such as quartz glass can be produced by sintering. ５０ When the D of the silica powder is 15 μm or less, the surface irregularities of the sintered body can be suppressed and the surface roughness can be controlled to be small, so that a sintered body having an Rq of 300 nm or less can be easily obtained. ５０ is more preferably 120 nm or more, even more preferably 150 nm or more, even more preferably 300 nm or more, particularly preferably 500 nm or more, and is more preferably 10 μm or less, even more preferably 5 μm or less, even more preferably 2 μm or less, particularly preferably 1 μm or less.

[0071] Silica powder is D ５０ D against １０ The ratio (D １０ / D ５０ It is preferable that the silica powder contains spherical particles having a D １０ / D ５０ By including spherical particles having a particle diameter within the above range, it is easy to prepare a green sheet. Furthermore, since insufficient densification during sintering can be suppressed, it is easy to obtain a sintered body having an Rq of 300 nm or less. １０ / D ５０ is more preferably 0.3 or more, even more preferably 0.4 or more, particularly preferably 0.5 or more, and is more preferably 0.9 or less, even more preferably 0.8 or less. １０ / D ５０ By reducing Rq, the particle size distribution can be broadened and the distance between particles can be increased, so that Rq can be controlled to be larger.

[0072] Silica powder is D ５０ D against ９０ The ratio (D ９０ / D ５０ Preferably, the silica powder contains spherical particles having a D of 1.0 or more and 3.0 or less. ９０ / D５０ By including spherical particles having a particle diameter within the above range, it is easy to prepare a green sheet. Furthermore, since insufficient densification during sintering can be suppressed, it is easy to obtain a sintered body having an Rq of 300 nm or less. ９０ / D ５０ is more preferably 1.2 or more, even more preferably 1.5 or more, particularly preferably 1.7 or more, and is more preferably 2.5 or less, particularly preferably 2.0 or less. ９０ / D ５０ By increasing the value of Rq, the particle size distribution can be broadened and the distance between particles can be increased, so that Rq can be controlled to a larger value.

[0073] Regarding the particle size distribution of silica powder, D ５０ is 80 nm or more and 15 μm or less, D １０ / D ５０ is 0.2 or more and 1.0 or less, D ９０ / D ５０ By setting Rq to 1.0 or more and 3.0 or less, a sintered body having Rq of 1 nm or more and 300 nm or less can be suitably obtained.

[0074] Here, the D of silica powder ５０ , D １０ , D ９０ means particle sizes at 50%, 10%, and 90% cumulative values ​​in the particle size distribution determined by a laser diffraction / scattering method, and can be measured, for example, using a laser diffraction / scattering particle size analyzer MT-3000 manufactured by Nikkiso Co., Ltd.

[0075] (Binder) The type of binder is not particularly limited, and examples thereof include polyvinyl alcohol-based resins such as polyvinyl alcohol, butyral-based resins such as polyvinyl butyral, cellulose-based resins such as methyl cellulose, ethyl cellulose, hydroxymethyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, hydroxypropylmethyl cellulose, and cellulose acetate phthalate, acrylic resins such as poly(meth)acrylic acid ester, nitrile-based resins such as polyacrylonitrile and polymethacrylonitrile, urethane-based resins such as polyurethane, vinyl-based resins such as polyethylene, polypropylene, polyvinylidene fluoride, polyvinylidene chloride, polyvinyl fluoride, and vinyl acetate, rubber-based resins such as styrene-butadiene rubber, and epoxy-based resins. The binder can be used alone or in combination of two or more. Commercially available binders may also be used.

[0076] (Organic Solvent) The organic solvent is selected taking into consideration the compatibility with the binder, dispersants and plasticizers described below, the desired properties of the green sheet, the process load that can be withstood, etc. Examples of organic solvents include hydrocarbons such as toluene, xylene, ethylbenzene, methylcyclohexane, and terpineol; alcohols such as ethanol, n-propanol, isopropanol, and n-butanol; ketones such as acetone, methyl ethyl ketone, and methyl isobutyl ketone; ethers such as ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, and propylene glycol monomethyl ether; and esters such as ethyl acetate, butyl acetate, isobutyl acetate, and propylene glycol monomethyl ether acetate. The organic solvents can be used alone or in combination of two or more.

[0077] (Other Components) The slurry composition may be prepared so as to contain, as other components, a dispersant, a plasticizer, an antifoaming agent, a rheology control agent, a wetting agent, and the like.

[0078] Examples of dispersants include surfactant-type dispersants and polymer dispersants. Dispersants can be used alone or in combination of two or more. Examples of surfactant-type dispersants include alkylamine salts, aliphatic or aromatic quaternary ammonium salts, heterocyclic quaternary ammonium salts such as pyridinium and imidazolium, phosphonium or sulfonium salts containing aliphatic or heterocyclic rings, and acetylene glycol. Examples of polymer dispersants include polymers having primary to tertiary amines, quaternary ammonium bases, quaternary phosphonium bases, carboxylic acid groups, hydrochloric acid groups, or phosphate groups in the polymer main chain or side chain; homopolymers of acrylic acid or its salts; and homopolymers, copolymers, and block copolymers of aminocarboxylic acid, polyamine, polyurethane, and polyacrylate types. Commercially available dispersants may also be used.

[0079] Examples of the plasticizer include adipic acid-based, adipic acid ether ester-based, phthalic acid-based, terephthalic acid ester-based, triethylene glycol diester-based, polyether ester-based, and epoxy-based plasticizers. More specifically, bis(2-ethylhexyl) adipate, diisononyl adipate, diisodecyl adipate, di-2-ethylhexyl phthalate, diisononyl phthalate, diisodecyl phthalate, diundecyl phthalate, dibutyl phthalate, dioctyl phthalate, butyl benzyl phthalate, dioctyl terephthalate, triethylene glycol bis(2-ethylhexanoate), (2-ethylhexanoyloxy)triethylene glycol benzoate, triethylene glycol dibenzoate, di-2-ethylhexyl epoxyhexahydrophthalate, di-2-ethylhexyl azelate, di-2-ethylhexyl sebacate, diepoxystearyl epoxyhexahydrophthalate, epoxidized soybean oil, etc. can be used. Plasticizers can be used alone or in combination of two or more. Commercially available products or reagents may be used as the plasticizer.

[0080] Forming of Green Sheet Subsequently, the prepared slurry composition is formed into a green sheet, for example, by applying the prepared slurry composition in the form of a sheet onto a support.

[0081] (Support) Examples of the support include resin films. Thermoplastic resin films are usually used as the resin film, and specific examples include polyethylene terephthalate films, polypropylene films, polyethylene films, polycarbonate films, polyethylene naphthalate films, polyarylate films, and nylon films. Among these resin films, polyethylene terephthalate films and polyethylene naphthalate films are preferred from the viewpoints of heat resistance, chemical resistance, and releasability after lamination. The thickness of the support is not particularly limited.

[0082] (Coating Method) As a method for applying the slurry composition in the form of a sheet onto a support, a known wet coating method can be used, and examples thereof include spin coating, doctor blade method, reverse roll coater method, spray coating, dip coating, die coating, curtain coating, screen coating, inkjet method, flow coating, gravure coating, bar coating, flexo coating, slit coating, roll coating, sponge roll coating, and squeegee coating.

[0083] The slurry composition may be applied in sheet form onto the support so that the thickness of the green sheet obtained after drying, which will be described later, is, for example, 10 μm to 2.4 mm, thereby adjusting the thickness of the silica glass substrate obtained after sintering to 10 μm to 2 mm.

[0084] Drying: After applying the slurry composition in a sheet form on a support, the slurry composition is dried to obtain a green sheet. Drying is a process for removing organic solvents and the like from the slurry composition applied in a sheet form on a support.

[0085] Drying conditions are appropriately set depending on the type and amount of the organic solvent used, etc. In the present invention, for example, drying conditions can be set at 60° C. for 4 hours.

[0086] (Green Sheet) As described above, the green sheet is obtained by drying a slurry composition containing silica powder, a binder, and an organic solvent, and may contain at least silica powder and a binder. Depending on the drying conditions, the green sheet may also contain an organic solvent. The green sheet may also contain other components such as a dispersant, a plasticizer, an antifoaming agent, a rheology control agent, and a wetting agent, as described in the section on the slurry composition.

[0087] - Manufacturing of Silica Glass Substrate Next, the produced green sheet is fired to obtain a silica glass substrate as a sintered body.

[0088] (Degreasing) The organic components of the obtained green sheet may be burned to obtain a degreased body. The degreasing is preferably carried out using a heating furnace such as an electric furnace at a temperature of 400 to 1000°C for 0.5 to 80 hours.

[0089] (Sintering) The obtained degreased body is sintered to obtain a sintered silica glass substrate. The degreased body may be sintered in a vacuum or an inert gas atmosphere.

[0090] When the degreased body is sintered in a vacuum or in an inert atmosphere, the firing temperature is preferably, for example, 1300 to 1550°C. Here, from the viewpoint of obtaining a high-density silica glass substrate, the firing temperature is preferably 1300°C or higher, more preferably 1350°C or higher, and even more preferably 1400°C or higher. Furthermore, from the viewpoint of suppressing cracking of the sintered body due to crystal precipitation, the firing temperature is preferably 1550°C or lower, more preferably 1500°C or lower, and even more preferably 1480°C or lower. Furthermore, when the degreased body is sintered in a vacuum or inert atmosphere, the firing time is, for example, 0.03 to 5 hours, or may be 5 to 30 hours, or may be 30 to 100 hours.

[0091] (Applications) The silica glass substrate of this embodiment is suitable for use in high-frequency devices because, even when the substrate surface is metallized, the formed metallized layer is resistant to peeling and high-frequency transmission loss is reduced. In particular, the substrate is suitable for high-frequency devices that handle high-frequency signals, particularly high-frequency signals exceeding 30 GHz, and even high-frequency signals of 70 GHz or higher, and can reduce transmission loss of such high-frequency signals to improve characteristics such as the quality and strength of the high-frequency signals. Examples of high-frequency devices suitable for use include high-frequency devices (electronic devices) such as semiconductor devices used in communication equipment such as mobile phones, smartphones, personal digital assistants, and Wi-Fi devices; surface acoustic wave (SAW) devices; radar components such as radar transceivers; and antenna components such as liquid crystal antennas.

[0092] <Method for Manufacturing Glass Substrate> The method for manufacturing the glass substrate of this embodiment is not particularly limited, but it is preferable to obtain the glass substrate by sintering a green sheet containing an inorganic powder adjusted to a specific composition. This manufacturing method has the advantage that a substrate of 2 mm or less can be directly obtained without cutting and polishing, and a desired surface roughness Rq can be achieved without post-processing, making it possible to easily produce a glass substrate in which the metallization is resistant to peeling. Below, a method for manufacturing the glass substrate of this embodiment using a sintering method will be described as an example, but the glass substrate of this embodiment is not limited to one obtained by this manufacturing method. For example, the glass substrate may also be obtained by a melting method.

[0093] Preparation of Slurry Composition As an example of the method for producing a glass substrate according to this embodiment, a slurry composition is first prepared. The slurry composition can be obtained by mixing an inorganic powder, a binder, and an organic solvent. In addition, as described below, a dispersant, a plasticizer, an antifoaming agent, etc. can also be mixed. The mixing method is not particularly limited, and a conventionally known method can be used.

[0094] ・Inorganic powder Inorganic powder is SiO ２ The content of SiO may be 60 mol % or more and less than 100 mol %, and preferably, the content is the same as the preferred composition of the glass substrate described above. ２ : 60 to 90 mol%, B ２ O３ : 10 to 35 mol%, P ２ O ５ , GeO ２ , CaO, MgO, BaO, Li ２ O, Na ２ O.K. ２ O, SnO ２ , ZnO, and TiO ２ The total of the above components is 1 to 15 mol %.

[0095] The form of the inorganic powder is not particularly limited, and examples thereof include frit obtained by crushing molten glass, glass beads, and the like.

[0096] The shape of the inorganic powder may be spherical or may be non-spherical such as amorphous or crushed, but from the viewpoint of packing density, spherical is preferred.

[0097] When the purity of the inorganic powder is 100% (0% impurities) when it consists only of the desired composition, the purity of the inorganic powder is preferably 99.0% or more, more preferably 99.5% or more, and even more preferably 99.8% or more.

[0098] The 50% particle size on a volume basis in the cumulative particle size distribution is D ５０ When the D of the inorganic powder ５０ The D of the inorganic powder is preferably 80 nm or more and 15 μm or less. ５０ When the D of the inorganic powder is 80 nm or more, it is easy to adjust the inorganic powder solid content of the green sheet to 30 vol % or more. Furthermore, when the solid content is high, densification by sintering is easily promoted, so it is easy to obtain a sintered body with Rq of 300 nm or less. ５０ When the D of the silica powder is 15 μm or less, the firing temperature can be prevented from becoming too high, and a glass sintered body can be produced by sintering. ５０ When the D of the inorganic powder is 15 μm or less, the surface irregularities of the sintered body can be suppressed and the surface roughness can be controlled to be small, so that a sintered body having an Rq of 300 nm or less can be easily obtained. ５０is more preferably 120 nm or more, even more preferably 150 nm or more, even more preferably 300 nm or more, particularly preferably 500 nm or more, and is more preferably 10 μm or less, even more preferably 5 μm or less, even more preferably 2 μm or less, particularly preferably 1 μm or less.

[0099] The inorganic powder is D ５０ D against １０ The ratio (D １０ / D ５０ It is preferable that the inorganic powder contains spherical particles having a D １０ / D ５０ By including spherical particles having a particle diameter within the above range, it is easy to prepare a green sheet. Furthermore, since insufficient densification during sintering can be suppressed, it is easy to obtain a sintered body having an Rq of 300 nm or less. １０ / D ５０ is more preferably 0.3 or more, even more preferably 0.4 or more, particularly preferably 0.5 or more, and is more preferably 0.9 or less, even more preferably 0.8 or less. １０ / D ５０ By reducing Rq, the particle size distribution can be broadened and the distance between particles can be increased, so that Rq can be controlled to be larger.

[0100] The inorganic powder is D ５０ D against ９０ The ratio (D ９０ / D ５０ It is preferable that the inorganic powder contains spherical particles having a D ９０ / D ５０ By including spherical particles having a particle diameter within the above range, it is easy to prepare a green sheet. Furthermore, since insufficient densification during sintering can be suppressed, it is easy to obtain a sintered body having an Rq of 300 nm or less. ９０ / D ５０ is more preferably 1.2 or more, even more preferably 1.5 or more, particularly preferably 1.7 or more, and is more preferably 2.5 or less, particularly preferably 2.0 or less. ９０ / D ５０ By increasing the value of Rq, the particle size distribution can be broadened and the distance between particles can be increased, so that Rq can be controlled to a larger value.

[0101] Regarding the particle size distribution of inorganic powder, D５０ is 80 nm or more and 15 μm or less, D １０ / D ５０ is 0.2 or more and 1.0 or less, D ９０ / D ５０ By setting the D of the inorganic powder to 1.0 or more and 3.0 or less, a sintered body having an Rq of 1 nm or more and 300 nm or less can be suitably obtained. ５０ , D １０ , D ９０ means particle sizes at 50%, 10%, and 90% cumulative values ​​in the particle size distribution determined by a laser diffraction / scattering method, and can be measured, for example, using a laser diffraction / scattering particle size analyzer MT-3000 manufactured by Nikkiso Co., Ltd.

[0102] (Binder) The type of binder is not particularly limited, and examples thereof include polyvinyl alcohol-based resins such as polyvinyl alcohol, butyral-based resins such as polyvinyl butyral, cellulose-based resins such as methyl cellulose, ethyl cellulose, hydroxymethyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, hydroxypropylmethyl cellulose, and cellulose acetate phthalate, acrylic resins such as poly(meth)acrylic acid ester, nitrile-based resins such as polyacrylonitrile and polymethacrylonitrile, urethane-based resins such as polyurethane, vinyl-based resins such as polyethylene, polypropylene, polyvinylidene fluoride, polyvinylidene chloride, polyvinyl fluoride, and vinyl acetate, rubber-based resins such as styrene-butadiene rubber, and epoxy-based resins. The binder can be used alone or in combination of two or more. Commercially available binders may also be used.

[0103] (Organic Solvent) The organic solvent is selected taking into consideration the compatibility with the binder, dispersants and plasticizers described below, the desired properties of the green sheet, the process load that can be withstood, etc. Examples of organic solvents include hydrocarbons such as toluene, xylene, ethylbenzene, methylcyclohexane, and terpineol; alcohols such as ethanol, n-propanol, isopropanol, and n-butanol; ketones such as acetone, methyl ethyl ketone, and methyl isobutyl ketone; ethers such as ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, and propylene glycol monomethyl ether; and esters such as ethyl acetate, butyl acetate, isobutyl acetate, and propylene glycol monomethyl ether acetate. The organic solvents can be used alone or in combination of two or more.

[0104] (Other Components) The slurry composition may be prepared so as to contain, as other components, a dispersant, a plasticizer, an antifoaming agent, a rheology control agent, a wetting agent, and the like.

[0105] Examples of dispersants include surfactant-type dispersants and polymer dispersants. Dispersants can be used alone or in combination of two or more. Examples of surfactant-type dispersants include alkylamine salts, aliphatic or aromatic quaternary ammonium salts, heterocyclic quaternary ammonium salts such as pyridinium and imidazolium, phosphonium or sulfonium salts containing aliphatic or heterocyclic rings, and acetylene glycol. Examples of polymer dispersants include polymers having primary to tertiary amines, quaternary ammonium bases, quaternary phosphonium bases, carboxylic acid groups, hydrochloric acid groups, or phosphate groups in the polymer main chain or side chain; homopolymers of acrylic acid or its salts; and homopolymers, copolymers, and block copolymers of aminocarboxylic acid, polyamine, polyurethane, and polyacrylate types. Commercially available dispersants may also be used.

[0106] Examples of the plasticizer include adipic acid-based, adipic acid ether ester-based, phthalic acid-based, terephthalic acid ester-based, triethylene glycol diester-based, polyether ester-based, and epoxy-based plasticizers. More specifically, bis(2-ethylhexyl) adipate, diisononyl adipate, diisodecyl adipate, di-2-ethylhexyl phthalate, diisononyl phthalate, diisodecyl phthalate, diundecyl phthalate, dibutyl phthalate, dioctyl phthalate, butyl benzyl phthalate, dioctyl terephthalate, triethylene glycol bis(2-ethylhexanoate), (2-ethylhexanoyloxy)triethylene glycol benzoate, triethylene glycol dibenzoate, di-2-ethylhexyl epoxyhexahydrophthalate, di-2-ethylhexyl azelate, di-2-ethylhexyl sebacate, diepoxystearyl epoxyhexahydrophthalate, epoxidized soybean oil, etc. can be used. Plasticizers can be used alone or in combination of two or more. Commercially available products or reagents may be used as the plasticizer.

[0107] Forming of Green Sheet Subsequently, the prepared slurry composition is formed into a green sheet, for example, by applying the prepared slurry composition in the form of a sheet onto a support.

[0108] (Support) Examples of the support include resin films. Thermoplastic resin films are usually used as the resin film, and specific examples include polyethylene terephthalate films, polypropylene films, polyethylene films, polycarbonate films, polyethylene naphthalate films, polyarylate films, and nylon films. Among these resin films, polyethylene terephthalate films and polyethylene naphthalate films are preferred from the viewpoints of heat resistance, chemical resistance, and releasability after lamination. The thickness of the support is not particularly limited.

[0109] (Coating Method) As a method for applying the slurry composition in the form of a sheet onto a support, a known wet coating method can be used, and examples thereof include spin coating, doctor blade method, reverse roll coater method, spray coating, dip coating, die coating, curtain coating, screen coating, inkjet method, flow coating, gravure coating, bar coating, flexo coating, slit coating, roll coating, sponge roll coating, and squeegee coating.

[0110] The slurry composition may be applied in sheet form onto the support so that the thickness of the green sheet obtained after drying, which will be described later, is, for example, 10 μm to 2.4 mm, thereby adjusting the thickness of the silica glass substrate obtained after sintering to 10 μm to 2 mm.

[0111] Drying: After applying the slurry composition in a sheet form on a support, the slurry composition is dried to obtain a green sheet. Drying is a process for removing organic solvents and the like from the slurry composition applied in a sheet form on a support.

[0112] Drying conditions are appropriately set depending on the type and amount of the organic solvent used, etc. In the present invention, for example, drying conditions can be set at 60° C. for 4 hours.

[0113] (Green Sheet) As described above, the green sheet is obtained by drying a slurry composition containing an inorganic powder, a binder, and an organic solvent, and may contain at least an inorganic powder and a binder. Depending on the drying conditions, the green sheet may also contain an organic solvent. The green sheet may also contain other components such as a dispersant, a plasticizer, an antifoaming agent, a rheology control agent, and a wetting agent, as described in the section on the slurry composition.

[0114] - Manufacturing of Glass Substrate Next, the produced green sheet is fired to obtain a glass substrate as a sintered body.

[0115] (Degreasing) The organic components of the obtained green sheet may be burned to obtain a degreased body. The degreasing is preferably carried out using a heating furnace such as an electric furnace at a temperature of 400 to 600°C for 0.5 to 80 hours.

[0116] (Sintering) The resulting degreased body is sintered to obtain a glass substrate as a sintered body. The degreased body may be sintered in a vacuum or an inert gas atmosphere.

[0117] When the degreased body is sintered in a vacuum or in an inert atmosphere, the firing temperature is preferably, for example, 600 to 1100°C. Here, from the viewpoint of obtaining a high-density glass substrate, the firing temperature is preferably 600°C or higher, more preferably 630°C or higher, and even more preferably 650°C or higher. Furthermore, from the viewpoint of suppressing cracking of the sintered body due to crystal precipitation, the firing temperature is preferably 1100°C or lower, more preferably 1000°C or lower, and even more preferably 950°C or lower. Furthermore, when the degreased body is sintered in a vacuum or inert atmosphere, the firing time is, for example, 0.03 to 5 hours, or may be 5 to 30 hours, or may be 30 to 100 hours.

[0118] (Applications) The glass substrate of this embodiment is suitable for use in high-frequency devices because, even when the substrate surface is metallized, the formed metallized layer is resistant to peeling and high-frequency transmission loss is reduced. In particular, the glass substrate is suitable for high-frequency devices that handle high-frequency signals, particularly high-frequency signals exceeding 30 GHz, and even high-frequency signals of 70 GHz or higher. The glass substrate can reduce transmission loss of such high-frequency signals and improve characteristics such as the quality and strength of the high-frequency signals. Examples of high-frequency devices suitable for use include high-frequency devices (electronic devices) such as semiconductor devices used in communication devices such as mobile phones, smartphones, personal digital assistants, and Wi-Fi devices; surface acoustic wave (SAW) devices; radar components such as radar transceivers; and antenna components such as liquid crystal antennas.

[0119] <Metallized Substrate> A metallized substrate according to one embodiment of the present invention (hereinafter simply referred to as the metallized substrate of this embodiment) is characterized in that a metallized layer is provided on the surface of the silica glass substrate or glass substrate of this embodiment described above. Figure 2 shows a schematic cross-sectional view of a metallized substrate 100 according to this embodiment, in which a metallized layer 20 is provided on the surface of a silica glass substrate 10 of this embodiment. The same applies when a metallized layer is provided on the surface of a glass substrate of this embodiment. In the metallized substrate of this embodiment, a metallized layer is provided on the surface of the silica glass substrate or glass substrate of this embodiment described above, so that the metallized layer is less likely to peel off and high-frequency transmission loss is reduced.

[0120] The metal species contained in the metallized layer is not particularly limited, and may be an alloy or a metal compound containing at least one of the above metals, such as copper, silver, aluminum, titanium, gold, platinum, nickel, tungsten, lead, manganese, magnesium, and chromium.

[0121] The metallization layer can be formed on the surface of the silica glass substrate or glass substrate of this embodiment by, for example, electroplating, electroless plating, chemical vapor deposition (CVD), physical vapor deposition (PVD) such as sputtering, thermal evaporation, and electron beam evaporation, a printing method, a dipping method, etc. Hereinafter, a method of forming a metallization layer by electroplating will be described, but the method is not limited to this.

[0122] To provide a metallized layer on the surface of the silica glass substrate or glass substrate of this embodiment by electroplating, the silica glass substrate or glass substrate is first placed in a plating solution containing an ionic compound having an anion and a cation of the metal from which the metallization layer is to be formed, and an electric current is applied, thereby depositing the metal in elemental form onto the surface of the silica glass substrate or glass substrate, forming a metallized layer containing the metal.

[0123] Examples of anions contained in the ionic compound containing the cation of the metal to be deposited include sulfate anion, nitrate anion, and chloride anion. An example of the ionic compound is copper sulfate. An example of the plating solution is copper sulfate pentahydrate (CuSO ４ ・5H ２ O) and potassium pyrophosphate (K ４ P ２ O ７ Another example of a plating solution is a solution of copper sulfate pentahydrate (CuSO ). ４ ・5H ２ O) and manganese sulfate monohydrate (MnSO ４ ・H ２ Also included is a solution containing ionic compound (ICO), sodium potassium tartrate tetrahydrate (Rochelle salt), and formaldehyde. In some embodiments, the concentration of the ionic compound in the plating solution is 0.001 M (mol / L) or more. In addition to the silica glass substrate or glass substrate, electrodes made of any conductive material may also be placed in the plating solution. In some embodiments, the temperature of the plating solution is 10°C to 50°C, for example, room temperature or 40°C.

[0124] Then, a current, a voltage, or a combination thereof is applied between the silica glass substrate or the glass substrate and the electrode to supply a negative constant current to the silica glass substrate or the glass substrate. For example, a current of about 0.001 mA / cm ２ ~Approx. 1A / cm ２and a voltage range of about −0.001 V to about −20 V. As a result, the cations of the metal that will become the metallization layer are reduced to their elemental form on the silica glass substrate or glass substrate. The rate of this reduction reaction is controlled by the current density. Therefore, the film formation rate can be increased or decreased by increasing or decreasing the applied current. Once a metallization layer containing the desired metal is formed on the silica glass substrate or glass substrate, the current is stopped, the silica glass substrate or glass substrate is removed from the plating solution, and the silica glass substrate or glass substrate with the metallization layer formed thereon may be washed with deionized water. Optionally, the silica glass substrate or glass substrate with the metallization layer formed thereon may be dried, for example, by passing a nitrogen flow over the silica glass substrate or glass substrate with the metallization layer formed thereon.

[0125] In the metallized substrate of this embodiment, the thickness of the metallized layer is preferably 0.01 μm to 100 μm, more preferably 0.1 μm to 50 μm, and even more preferably 1 μm to 25 nm. By having the thickness of the metallized layer in this range, loss and reflection that occur when a high-frequency signal passes through the metallized layer can be minimized.

[0126] As described above, the present specification discloses the following: [1] A silica glass substrate having a root mean square height Rq of 1 nm or more and 300 nm or less on the substrate surface and a thickness of 10 μm or more and 2 mm or less. [2] A silica glass substrate having defects with an average diameter of 1 μm or more and 100 μm or less within 1 cm ２ [3] The silica glass substrate according to the above [1], wherein the number of H atoms converted from β-OH is 500,000 or less per unit area. ２The silica glass substrate according to [1] or [2] above, having an O concentration of less than 100 ppm by mass. [4] The silica glass substrate according to any one of [1] to [3] above, having a total content of Na, K, and Ca of 0.1 ppm by mass or more and 50 ppm by mass or less. [5] The silica glass substrate according to any one of [1] to [4] above, having a C content of 5 ppm by mass or less. [6] The silica glass substrate according to any one of [1] to [5] above, having a Zr content of 50 ppm by mass or less. [7] The silica glass substrate according to any one of [1] to [6] above, having a Ti content of 50 ppm by mass or less. [8] The silica glass substrate according to any one of [1] to [7] above, having an Al content of 50 ppm by mass or less. [9] The silica glass substrate according to any one of [1] to [8] above, wherein the ratio (D2 / PH) of the intensity (D2) to the height (PH) of the peak derived from the three-membered ring structure in the Raman spectrum is 0.10 or more.

[10] The silica glass substrate according to any one of [1] to [9] above, wherein the ratio (D1 / PH) of the intensity (D1) to the height (PH) of the peak derived from the four-membered ring structure in the Raman spectrum is 0.40 or more.

[11] The silica glass substrate according to any one of [1] to

[10] above, which is used for a high-frequency device.

[12] A metallized substrate having a metallized layer provided on the surface of the silica glass substrate according to any one of [1] to

[10] above.

[0127]

[13] The root mean square height Rq of the substrate surface is 1 nm or more and 300 nm or less, the plate thickness is 10 μm or more and 2 mm or less, and the oxide-based mol% expression is SiO ２

[14] A glass substrate containing 60 mol % or more and less than 100 mol % of B, expressed in mol % on an oxide basis. ２ O ３

[15] The glass substrate according to

[13] above, further containing, in mole percent on an oxide basis, 10 mole percent to 35 mole percent of ２ O ５ , GeO ２ , CaO, MgO, BaO, Li ２ O, Na ２ O.K. ２ O, SnO ２ , ZnO, and TiO ２The glass substrate according to

[13] or

[14] above, further containing at least one of the following, wherein the total content thereof is 1 mol % or more and 15 mol % or less.

[16] The glass substrate according to any one of

[13] to

[15] above, wherein the total content of Na, K, and Ca is 0.1 ppm by mass or more and 50 ppm by mass or less.

[17] The glass substrate according to any one of

[13] to

[15] above, wherein the content of C is 5 ppm by mass or less.

[18] The glass substrate according to any one of

[13] to

[17] above, wherein the content of Zr is 50 ppm by mass or less.

[19] The glass substrate according to any one of

[13] to

[18] above, wherein the content of Ti is 50 ppm by mass or less.

[20] The glass substrate according to any one of

[13] to

[19] above, wherein the content of Al is 50 ppm by mass or less.

[21] The glass substrate according to any one of

[13] to

[20] above, which is used for a high-frequency device.

[22] A metallized substrate, comprising the glass substrate according to any one of

[13] to

[20] above, on the surface of which a metallized layer is provided.

[0128] The present invention will be described in detail below with reference to examples, but the present invention is not limited to these. Examples 1 to 13 are working examples, and Example 14 is a comparative example. Examples 1 to 6 and 14 are silica glass substrates, and Examples 7 to 13 are glass substrates. Blank spaces in Table 1 indicate that measurements were not taken.

[0129] (C Amount) The impurity amount (C amount) in the silica glass substrate and glass substrate of each example was measured using a carbon analyzer (EMIA-Pro, manufactured by HORIBA). The measurement results for each example are shown in Table 1.

[0130] (Amounts of Al, Zr, and Ti) The amounts of impurities (amounts of C, Al, Zr, and Ti) in the silica glass substrate and glass substrate of each example were measured using an ICP mass spectrometer (Agilent 8800, manufactured by Agilent Technologies, Inc.) The measurement results for each example are shown in Table 1.

[0131] (Total Content of Na, K, and Ca) The total content of Na, K, and Ca in the silica glass substrate and glass substrate of each example was measured using an ICP mass spectrometer (Agilent 8800, manufactured by Agilent Technologies, Inc.). The measurement results for each example are shown in Table 1.

[0132] (H ２ O) The β-OH in the silica glass substrate of each example was measured using a Fourier transform infrared spectrophotometer (IRXross, manufactured by Shimadzu Corporation), and H ２ The O concentration was calculated. The results for each example are shown in Table 1.

[0133] (Disadvantages) By processing the microscopic images obtained by an optical microscope (VHX8000 manufactured by Keyence Corporation) with image analysis software (Imagepro manufactured by Hakuto Co., Ltd.), it was possible to identify the 1 cm ２ Number of defects with an average diameter of 5 μm to 100 μm per 1 cm ２ The number of defects with an average diameter of 1 μm or more and 5 μm or less per 1 cm ２ The number of defects with an average diameter of 1 μm or more and 100 μm or less per defect was measured. The average diameter refers to the average diameter obtained by connecting two points on the periphery of defects extracted based on the color and shape of the pattern using image analysis software, with the glass portion selected as the background in an optical microscope image, and passing through the center of gravity. The measurement results for each example are shown in Table 1.

[0134] (Raman Spectrum) Raman spectroscopy was performed using a microscopic laser Raman spectrometer (LabRAM HR Evolution, manufactured by HORIBA), and the Raman shift (x) was measured in the range of 100 to 720 cm －１ The scattered light intensity (y) in the range of 1 μm, i.e., the Raman spectrum, was obtained. The measurement object was a cylindrical region 5 μm below the surface of the silica glass substrate in each example, with a diameter of approximately 3 μm and a length of approximately 3 μm. From the obtained Raman spectrum, the ratio (D2 / PH) of the peak (D2) derived from the three-membered ring structure to the height (PH), and the ratio (D1 / PH) of the peak (D1) derived from the four-membered ring structure to the height (PH) were calculated. The measurement results for each example are shown in Table 1. The Raman spectrum of Example 5 is also shown in Figure 3.

[0135] (Rq) The root mean square height Rq of the surface of the silica glass substrate and the glass substrate of each example was measured using a surface roughness measuring device (Surfcom 1400D, manufactured by Tokyo Seimitsu Co., Ltd.) based on the provisions of JIS B 0601 (2013). The measurement results for each example are shown in Table 1.

[0136] (Df) The Df (dielectric loss tangent) at 10 GHz of the silica glass substrate and the glass substrate of each example was measured by a dielectric resonator method.

[0137] (Etching Rate (Relative Value)) The etching rates of the silica glass substrate and the glass substrate in each example were determined by masking the silica glass substrate with Kapton tape and etching it with HF: 8 wt %, HNO ３ After immersion in a 7 wt % aqueous solution of HCl for 5 hours, the mask was removed and the etching rate was calculated from the results of measuring the step height using a stylus surface profiler (Dektak 150, manufactured by Bruker). The etching rate was calculated as a relative value, with the etching rate of synthetic quartz glass (AQ, manufactured by AGC) set at 1. The results are shown in Table 1.

[0138] (Plating Adhesion Test) A 0.07 μm Cu plating was applied to the surface of a silica glass substrate and a glass substrate by sputtering, and a test was carried out in accordance with the tape test method in the plating adhesion test method defined in JIS H 8504: 1999. The test area was visually observed, and if peeling or swelling of the plating was evident, it was marked with ×, and if not, it was marked with ○.

[0139] <Preparation of Silica Glass Substrate and Glass Substrate> (Example 1) D, which is the 50% particle size on a volume basis in the cumulative particle size distribution ５０ is 2180 nm, and D is the 10% particle size on a volume basis in the particle size distribution １０ is 1046 nm, and D is the 90% particle size on a volume basis in the cumulative particle size distribution ９０ is 3750 nm, D １０ and D ５０ The ratio (D １０ / D ５０ ) is 0.48, D ９０ and D ５０ The ratio (D ９０ / D ５０Spherical silica powder with a ρ of 1.72 was prepared, and an organic solvent was weighed out to a ratio of 45% by mass of propylene glycol monomethyl ether acetate, 30% by mass of 2-butanol, and 25% by mass of isopropyl alcohol. A dispersant (a polymer dispersant with an ammonium base on the polymer side chain) was added to the silica powder at 4% by mass, and a plasticizer (a commercially available adipic acid ether ester product) was added to the silica powder at 5% by mass, and the mixture was mixed in a ball mill. A solution of polyvinyl butyral was prepared as a binder at a component ratio of 22.4% by mass, and this was weighed out to a ratio of 5% by mass of the silica powder and added to the ball mill container. The binder solvent used was the same as the solvent composition of the dispersion slurry. The resulting slurry was degassed under reduced pressure and applied to a PET (polyethylene terephthalate) film using a doctor blade method to form a 0.18 mm thick green sheet. The resulting green sheet was dried at 60°C for 4 hours and cut using a disc cutter to obtain a sheet molded product. This was degreased at 600° C. for 1 hour and then fired in a vacuum at 1460° C. for 5 minutes to obtain a silica glass substrate as a sintered body having a thickness of 0.15 mm.

[0140] (Example 2) D, which is the 50% particle size on a volume basis in the cumulative particle size distribution ５０ is 2180 nm, and D is the 10% particle size on a volume basis in the particle size distribution １０ is 1046 nm, and D is the 90% particle size on a volume basis in the cumulative particle size distribution ９０ is 3750 nm, D １０ and D ５０ The ratio (D １０ / D ５０ ) is 0.48, D ９０ and D ５０ The ratio (D ９０ / D ５０Spherical silica powder with a viscosity index of 1.72 was prepared and weighed out to a ratio of 100% by mass of propylene glycol monomethyl ether acetate as an organic solvent. A dispersant (a polymer dispersant with an ammonium base on the polymer side chain) was added to the silica powder at 4% by mass and a plasticizer (a commercially available adipic acid ether ester-based product) was added to the silica powder at 5% by mass, and the mixture was mixed in a ball mill. A solution of polyvinyl butyral was prepared as a binder at a component ratio of 22.4% by mass, and weighed out to a ratio of 5% by mass of the silica powder. The binder solvent was the same as the solvent composition of the dispersion slurry. The resulting slurry was degassed under reduced pressure and applied to a PET film using a doctor blade method to form a 0.10 mm thick green sheet. The resulting green sheet was dried at 60°C for 4 hours and cut using a disc cutter to obtain a sheet molded product. This was degreased at 600° C. for 1 hour and then fired in a vacuum at 1460° C. for 5 minutes to obtain a silica glass substrate as a sintered body having a thickness of 0.08 mm.

[0141] (Example 3) D, which is the 50% particle size on a volume basis in the cumulative particle size distribution ５０ is 500 nm, and D is the 10% particle size on a volume basis in the particle size distribution １０ is 330 nm, and D is the 90% particle size on a volume basis in the cumulative particle size distribution ９０ is 640 nm, D １０ and D ５０ The ratio (D １０ / D ５０ ) is 0.66, D ９０ and D ５０ The ratio (D ９０ / D ５０Spherical silica powder with a % saturation index (SMA) of 1.28 was prepared, and an organic solvent consisting of 45% by mass of propylene glycol monomethyl ether acetate, 30% by mass of 2-butanol, and 25% by mass of isopropyl alcohol was weighed out. A dispersant (a polymer dispersant with an ammonium base on the polymer side chain) was added to the silica powder at 4% by mass, and a plasticizer (a commercially available adipic acid ether ester product) was added to the silica powder at 7% by mass, and the mixture was mixed in a ball mill. A solution of polyvinyl butyral was prepared as a binder at a component ratio of 22.4% by mass, and this was weighed out to 14% by mass of the silica powder and added to the ball mill container. The binder solvent used was the same as the solvent composition of the dispersion slurry. The resulting slurry was degassed under reduced pressure and applied to a PET film using a doctor blade method to form a 0.27 mm thick green sheet. The resulting green sheet was dried at 60°C for 4 hours and cut using a disc cutter to obtain a sheet molded product. This was degreased at 550° C. for 1 hour and then fired in a vacuum at 1550° C. for 5 minutes to obtain a silica glass substrate as a sintered body having a thickness of 0.225 mm.

[0142] (Example 4) D, which is the 50% particle size on a volume basis in the cumulative particle size distribution ５０ is 500 nm, and D is the 10% particle size on a volume basis in the particle size distribution １０ is 330 nm, and D is the 90% particle size on a volume basis in the cumulative particle size distribution ９０ is 640 nm, D １０ and D ５０ The ratio (D １０ / D ５０ ) is 0.66, D ９０ and D ５０ The ratio (D ９０ / D ５０Spherical silica powder with a % saturation index (SMA) of 1.28 was prepared, and an organic solvent consisting of 45% by mass of propylene glycol monomethyl ether acetate, 30% by mass of 2-butanol, and 25% by mass of isopropyl alcohol was weighed out. A dispersant (a polymer dispersant with an ammonium base on the polymer side chain) was added to the silica powder at 4% by mass, and a plasticizer (a commercially available adipic acid ether ester-based product) was added to the silica powder at 5% by mass, and the mixture was mixed in a ball mill. A solution of polyvinyl butyral was prepared as a binder at a component ratio of 22.4% by mass, and this was weighed out to 10% by mass of the silica powder and added to the ball mill container. The binder solvent used was the same as the solvent composition of the dispersion slurry. The resulting slurry was degassed under reduced pressure and applied to a PET film using a doctor blade method to form a 0.20 mm thick green sheet. The resulting green sheet was dried at 60°C for 4 hours and cut using a disc cutter to obtain a sheet molded product. This was degreased at 550° C. for 1 hour and then fired in a vacuum at 1510° C. for 5 minutes to obtain a silica glass substrate as a sintered body having a thickness of 0.168 mm.

[0143] (Example 5) D, which is the 50% particle size on a volume basis in the cumulative particle size distribution ５０ is 590 nm, and D is the 10% particle size on a volume basis in the particle size distribution １０ is 242 nm, and D is the 90% particle size on a volume basis in the cumulative particle size distribution ９０ is 838 nm, D １０ and D ５０ The ratio (D １０ / D ５０ ) is 0.41, D ９０ and D ５０ The ratio (D ９０ / D ５０Spherical silica powder with a viscosity index of 1.42 was prepared, and an organic solvent was weighed out to a ratio of 45% by mass of propylene glycol monomethyl ether acetate, 15% by mass of 2-butanol, 15% by mass of xylene, and 25% by mass of isopropyl alcohol. A dispersant (a polymer dispersant with an ammonium base on the polymer side chain) was added to the silica powder at 1% by mass, and a plasticizer (a commercially available adipic acid ether ester-based product) was added to the silica powder at 3% by mass, and the mixture was mixed in a ball mill. A solution of acrylic resin with a component ratio of 30% by mass was prepared as a binder, and this was weighed out to a ratio of 10% by mass of the silica powder and added to the ball mill container. The binder solvent used was the same as the solvent composition of the dispersion slurry. The resulting slurry was degassed under reduced pressure and applied to a PET film using a doctor blade method to form a 0.28 mm thick green sheet. The resulting green sheet was dried at 90°C for 1 hour and cut using a disc cutter to obtain a sheet molded product. This was degreased at 550° C. for 1 hour and then fired in a vacuum at 1470° C. for 5 minutes to obtain a silica glass substrate as a sintered body having a thickness of 0.245 mm.

[0144] (Example 6) D, which is the 50% particle size on a volume basis in the cumulative particle size distribution ５０ is 500 nm, and D is the 10% particle size on a volume basis in the particle size distribution １０ is 330 nm, and D is the 90% particle size on a volume basis in the cumulative particle size distribution ９０ is 640 nm, D １０ and D ５０ The ratio (D １０ / D ５０ ) is 0.66, D ９０ and D ５０ The ratio (D ９０ / D ５０Spherical silica powder with a % saturation index (SMA) of 1.28 was prepared, and an organic solvent consisting of 45% by mass of propylene glycol monomethyl ether acetate, 30% by mass of 2-butanol, and 25% by mass of isopropyl alcohol was weighed out. A dispersant (a polymer dispersant with an ammonium base on the polymer side chain) was added to the silica powder at 4% by mass, and a plasticizer (a commercially available adipic acid ether ester-based product) was added to the silica powder at 7% by mass, and the mixture was mixed in a ball mill. A solution of polyvinyl butyral resin with a component ratio of 22.4% by mass was prepared as a binder, and this was weighed out to 14% by mass of the silica powder and added to the ball mill container. The binder solvent used was the same as the solvent composition of the dispersion slurry. The resulting slurry was degassed under reduced pressure and applied to a PET film using a doctor blade method to form a 0.24 mm thick green sheet. The resulting green sheet was dried at 90°C for 1 hour and cut using a disc cutter to obtain a sheet molded product. This was degreased at 550° C. for 1 hour and then fired in a vacuum at 1550° C. for 5 minutes to obtain a silica glass substrate as a sintered body having a thickness of 0.203 mm.

[0145] (Example 7) D, which is the 50% particle size on a volume basis in the cumulative particle size distribution ５０ is 3252 nm, and D is the 10% particle size on a volume basis in the particle size distribution １０ is 2106 nm, and D is the 90% particle size on a volume basis in the cumulative particle size distribution ９０ is 5182 nm, D １０ and D ５０ The ratio (D １０ / D ５０ ) is 0.41, D ９０ and D ５０ The ratio (D ９０ / D ５０ A spherical inorganic powder having a SiO ２ 75 mol %, B ２ O ３The inorganic powder was mixed with propylene glycol monomethyl ether acetate (45% by mass), 2-butanol (30% by mass), and isopropyl alcohol (25% by mass) as solvents, weighed out to a ratio of 45% by mass, 30% by mass, and 25% by mass. A dispersant (a polymer dispersant with an ammonium base on the polymer side chain) was added to the inorganic powder at 1% by mass, and a plasticizer (a commercially available adipic acid ether ester-based product) was added to the inorganic powder at 3% by mass, and the mixture was mixed in a ball mill. A solution of polyvinyl butyral resin with a component ratio of 22.4% by mass was prepared as a binder, weighed out to a ratio of 10% by mass relative to the inorganic powder, and added to the ball mill container. The binder solvent was the same as the solvent composition of the dispersion slurry. The resulting slurry was degassed under reduced pressure and applied to a PET film using a doctor blade method to form a 0.24 mm thick green sheet. The resulting green sheet was dried at 90°C for 1 hour and cut using a disc cutter to obtain a sheet molded product. This was degreased at 550° C. for 1 hour and then fired in a vacuum at 800° C. for 5 minutes to obtain a glass substrate as a sintered body having a thickness of 0.200 mm.

[0146] (Example 8) D, which is the 50% particle size on a volume basis in the cumulative particle size distribution ５０ is 3470 nm, and D is the 10% particle size on a volume basis in the particle size distribution １０ is 2117 nm, and D is the 90% particle size on a volume basis in the cumulative particle size distribution ９０ is 5936 nm, D １０ and D ５０ The ratio (D １０ / D ５０ ) is 0.36, D ９０ and D ５０ The ratio (D ９０ / D ５０ A spherical inorganic powder having a SiO ２ 80 mol %, B ２ O ３The inorganic powder was mixed with a solvent of 45% by mass of propylene glycol monomethyl ether acetate, 30% by mass of 2-butanol, and 25% by mass of isopropyl alcohol. A dispersant (a polymer dispersant with an ammonium base on the polymer side chain) was added to the inorganic powder at 1% by mass, and a plasticizer (a commercially available adipic acid ether ester-based product) was added to the inorganic powder at 3% by mass, followed by ball mill mixing. A solution of polyvinyl butyral resin with a component ratio of 22.4% by mass was prepared as a binder, and this was weighed out to 10% by mass relative to the inorganic powder and added to the ball mill container. The binder solvent was the same as the solvent composition of the dispersion slurry. The resulting slurry was degassed under reduced pressure and applied to a PET film using a doctor blade method to form a 0.10 mm thick green sheet. The resulting green sheet was dried at 90°C for 0.5 hours and cut using a disc cutter to obtain a sheet molded product. This was degreased at 550° C. for 1 hour and then fired in a vacuum at 810° C. for 5 minutes to obtain a glass substrate as a sintered body having a thickness of 0.090 mm.

[0147] (Example 9) D, which is the 50% particle size on a volume basis in the cumulative particle size distribution ５０ is 3470 nm, and D is the 10% particle size on a volume basis in the particle size distribution １０ is 2117 nm, and D is the 90% particle size on a volume basis in the cumulative particle size distribution ９０ is 5936 nm, D １０ and D ５０ The ratio (D １０ / D ５０ ) is 0.36, D ９０ and D ５０ The ratio (D ９０ / D ５０ A spherical inorganic powder having a SiO ２ 85 mol%, B ２ O ３The inorganic powder was mixed with organic solvents (propylene glycol monomethyl ether acetate, propylene glycol monomethyl ether acetate, 2-butanol, and isopropyl alcohol) at a ratio of 45% by mass, 30% by mass, and 25% by mass, respectively. A dispersant (a polymer dispersant with an ammonium base on the polymer side chain) was added at 1% by mass relative to the inorganic powder, and a plasticizer (a commercially available adipic acid ether ester-based product) was added at 3% by mass relative to the inorganic powder, followed by ball mill mixing. A solution of polyvinyl butyral resin with a component ratio of 22.4% by mass was prepared as a binder, and this was weighed out to 10% by mass relative to the inorganic powder and added to the ball mill container. The binder solvent was the same as the solvent composition of the dispersion slurry. The resulting slurry was degassed under reduced pressure and applied to a PET film using a doctor blade method to form a 0.18 mm thick green sheet. The resulting green sheet was dried at 90°C for 0.5 hours and cut using a disc cutter to obtain a sheet molded product. This was degreased at 550° C. for 1 hour and then fired in a vacuum at 830° C. for 5 minutes to obtain a glass substrate as a sintered body having a thickness of 0.150 mm.

[0148] (Example 10) D, which is the 50% particle size on a volume basis in the cumulative particle size distribution ５０ is 3470 nm, and D is the 10% particle size on a volume basis in the particle size distribution １０ is 2117 nm, and D is the 90% particle size on a volume basis in the cumulative particle size distribution ９０ is 5936 nm, D １０ and D ５０ The ratio (D １０ / D ５０ ) is 0.36, D ９０ and D ５０ The ratio (D ９０ / D ５０ A spherical inorganic powder having a SiO ２ 90 mol %, B ２ O ３The amorphous particles were composed of 10 mol% of propylene glycol monomethyl ether acetate. The organic solvent was weighed out to a ratio of 45% by mass of propylene glycol monomethyl ether acetate, 30% by mass of 2-butanol, and 25% by mass of isopropyl alcohol. A dispersant (a polymer dispersant with an ammonium base on the polymer side chain) was added to the inorganic powder at 1% by mass, and a plasticizer (a commercially available adipic acid ether ester-based product) was added to the inorganic powder at 3% by mass, and the mixture was mixed in a ball mill. A solution of polyvinyl butyral resin with a component ratio of 22.4% by mass was prepared as a binder, and this was weighed out to a ratio of 10% by mass of the inorganic powder and added to the ball mill container. The binder solvent was the same as the solvent composition of the dispersion slurry. The resulting slurry was degassed under reduced pressure and applied to a PET film using a doctor blade method to form a 0.18 mm thick green sheet. The resulting green sheet was dried at 90°C for 0.5 hours and cut using a disc cutter to obtain a sheet molded product. This was degreased at 550° C. for 1 hour and then fired in a vacuum at 850° C. for 5 minutes to obtain a glass substrate as a sintered body having a thickness of 0.150 mm.

[0149] (Example 11) D, which is the 50% particle size on a volume basis in the cumulative particle size distribution ５０ is 3499 nm, and D is the 10% particle size on a volume basis in the particle size distribution １０ is 2458 nm, and D is the 90% particle size on a volume basis in the cumulative particle size distribution ９０ is 5308 nm, D １０ and D ５０ The ratio (D １０ / D ５０ ) is 0.46, D ９０ and D ５０ The ratio (D ９０ / D ５０ An inorganic powder having a SiO ２ 80 mol %, B ２ O ３The amorphous particles were composed of 15 mol% propylene glycol monomethyl ether acetate and 5 mol% MgO. 100% by mass of propylene glycol monomethyl ether acetate was weighed out as a solvent for the inorganic powder, and a dispersant (a polymer dispersant with an ammonium base on the polymer side chain) was added at 1% by mass relative to the inorganic powder, and a plasticizer (a commercially available adipic acid ether ester-based product) was added at 3% by mass relative to the inorganic powder, followed by ball mill mixing. A 22.4% by mass solution of acrylic resin was prepared as a binder, and weighed out to 10% by mass relative to the inorganic powder, and added to the ball mill container. The binder solvent was the same as the solvent composition of the dispersion slurry. The resulting slurry was degassed under reduced pressure and applied to a PET film using a doctor blade method to form a 0.23 mm thick green sheet. The resulting green sheet was dried at 90°C for 0.5 hours and cut using a disc cutter to obtain a sheet molded product. This was degreased at 550° C. for 1 hour and then fired in a vacuum at 810° C. for 5 minutes to obtain a glass substrate as a sintered body having a thickness of 0.20 mm.

[0150] (Example 12) D, which is the 50% particle size on a volume basis in the cumulative particle size distribution ５０ is 3234 nm, and D is the 10% particle size on a volume basis in the particle size distribution １０ is 2198 nm, and D is the 90% particle size on a volume basis in the cumulative particle size distribution ９０ is 4961 nm, D １０ and D ５０ The ratio (D １０ / D ５０ ) is 0.44, D ９０ and D ５０ The ratio (D ９０ / D ５０ An inorganic powder having a SiO ２ 80 mol %, B ２ O ３The amorphous particles were composed of 15 mol% propylene glycol monomethyl ether acetate and 5 mol% SnO. 100% by mass of propylene glycol monomethyl ether acetate was weighed out as a solvent for the inorganic powder, and a dispersant (a polymer dispersant with an ammonium base on the polymer side chain) was added at 1% by mass relative to the inorganic powder, and a plasticizer (a commercially available adipic acid ether ester-based product) was added at 3% by mass relative to the inorganic powder, followed by ball mill mixing. A solution of acrylic resin with a component ratio of 22.4% by mass was prepared as a binder, and weighed to 10% by mass relative to the inorganic powder, and added to the ball mill container. The binder solvent was the same as the solvent composition of the dispersion slurry. The resulting slurry was degassed under reduced pressure and applied to a PET film using a doctor blade method to form a 0.23 mm thick green sheet. The resulting green sheet was dried at 90°C for 0.5 hours and cut using a disc cutter to obtain a sheet molded product. This was degreased at 550° C. for 1 hour and then fired in a vacuum at 810° C. for 5 minutes to obtain a glass substrate as a sintered body having a thickness of 0.20 mm.

[0151] (Example 13) D, which is the 50% particle size on a volume basis in the cumulative particle size distribution ５０ is 4491 nm, and D is the 10% particle size on a volume basis in the particle size distribution １０ is 2172 nm, and D is the 90% particle size on a volume basis in the cumulative particle size distribution ９０ is 10030 nm, D １０ and D ５０ The ratio (D １０ / D ５０ ) is 0.22, D ９０ and D ５０ The ratio (D ９０ / D ５０ An inorganic powder having a SiO ２ 80 mol %, B ２ O ３The amorphous particles were composed of 15 mol% ZnO and 5 mol% ZnO. 100% by mass of propylene glycol monomethyl ether acetate was weighed out as a solvent for the inorganic powder, and a dispersant (a polymer dispersant with an ammonium base on the polymer side chain) was added at 1% by mass relative to the inorganic powder, and a plasticizer (a commercially available adipic acid ether ester-based product) was added at 3% by mass relative to the inorganic powder, followed by ball mill mixing. A solution of polyvinyl butyral resin with a component ratio of 22.4% by mass was prepared as a binder, and weighed to 10% by mass relative to the inorganic powder, and added to the ball mill container. The binder solvent was the same as the solvent composition of the dispersion slurry. The resulting slurry was degassed under reduced pressure and applied to a PET film using a doctor blade method to form a 0.23 mm thick green sheet. The resulting green sheet was dried at 90°C for 0.5 hours and cut using a disc cutter to obtain a sheet molded product. This was degreased at 550° C. for 1 hour and then fired in a vacuum at 800° C. for 5 minutes to obtain a glass substrate as a sintered body having a thickness of 0.20 mm.

[0152] Example 14 Example 14 is a synthetic quartz glass substrate (AQ, manufactured by AGC) with an Rq of 0.0001 μm.

[0153]

[0154] As shown in Table 1, in Examples 1 to 13, the root mean square height (Rq) of the substrate surface was 1 nm or more and 300 nm or less, resulting in high adhesion to the metal plating. Furthermore, the dielectric loss was very small and the substrate thickness was thin, achieving reduced high-frequency transmission loss. On the other hand, the synthetic quartz glass substrate (AQ, manufactured by AGC) in Example 14 had an Rq of 0.0001 μm, and visual peeling of the plating was observed in the plating adhesion test.

[0155] Although the present invention has been described in detail and with reference to specific embodiments, it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit and scope of the present invention. This application is based on a Japanese patent application (Patent Application No. 2023-214759) filed on December 20, 2023, the contents of which are incorporated herein by reference.

[0156] 10 Silica glass substrate 20 Metallized layer 100 Metallized substrate

Claims

1. A silica glass substrate having a root mean square height Rq of 1 nm or more and 300 nm or less on the substrate surface and a thickness of 10 μm or more and 2 mm or less.

2. Defects with an average diameter of 1 μm to 100 μm are 1 cm ２ 2. The silica glass substrate according to claim 1, wherein the number of particles per one of the plurality of particles is 500,000 or less.

3. H converted from β-OH ２ 2. The silica glass substrate according to claim 1, having an O concentration of less than 100 ppm by mass.

4. The silica glass substrate according to claim 1, wherein the total content of Na, K, and Ca is 0.1 ppm by mass or more and 50 ppm by mass or less.

5. The silica glass substrate according to claim 1, wherein the C content is 5 ppm by mass or less.

6. The silica glass substrate according to claim 1, wherein the Zr content is 50 ppm by mass or less.

7. The silica glass substrate according to claim 1, wherein the Ti content is 50 ppm by mass or less.

8. The silica glass substrate according to claim 1, wherein the Al content is 50 ppm by mass or less.

9. The silica glass substrate according to claim 1, wherein the ratio (D2 / PH) of the intensity (D2) to the height (PH) of the peak derived from a three-membered ring structure in a Raman spectrum is 0.10 or more.

10. The silica glass substrate according to claim 1, wherein the ratio (D1 / PH) of the intensity (D1) to the height (PH) of the peak derived from a four-membered ring structure in a Raman spectrum is 0.40 or more.

11. The silica glass substrate according to any one of claims 1 to 10, which is used in a high-frequency device.

12. A metallized substrate comprising a metallized layer provided on the surface of the silica glass substrate according to any one of claims 1 to 10.

13. The root mean square height Rq of the substrate surface is 1 nm or more and 300 nm or less, the plate thickness is 10 μm or more and 2 mm or less, and the oxide-based mole % expression is SiO ２ A glass substrate comprising 60 mol % or more and less than 100 mol % of the above.

14. In terms of mole percent based on oxide, B ２ O ３ The glass substrate according to claim 13, further comprising from 10 mol % to 35 mol % of 15. In mole percent based on oxide, P ２ O ５ , GeO ２ , CaO, MgO, BaO, Li ２ O, Na ２ O.K. ２ O, SnO ２ , ZnO, and TiO ２ The glass substrate according to claim 13, further comprising at least one of the following in a total content of 1 mol % to 15 mol %:

16. The glass substrate according to claim 13, wherein the total content of Na, K, and Ca is 0.1 ppm by mass or more and 50 ppm by mass or less.

17. The glass substrate according to claim 13, wherein the C content is 5 ppm by mass or less.

18. The glass substrate according to claim 13, wherein the Zr content is 50 ppm by mass or less.

19. The glass substrate according to claim 13, wherein the Ti content is 50 ppm by mass or less.

20. The glass substrate according to claim 13, wherein the Al content is 50 ppm by mass or less.

21. The glass substrate according to any one of claims 13 to 20, which is used in a high-frequency device.

22. A metallized substrate comprising a glass substrate according to any one of claims 13 to 20 and a metallized layer provided on the surface thereof.

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