Glass substrate

Abstract

To provide a glass substrate that resists cracking and also can prevent the visibility of a mark from deteriorating.SOLUTION: A glass substrate 10 comprises a mark composed of a plurality of dots 104 provided on a surface 10A. The dots 104 have a depth H of 0.5 μm or more and 7.0 μm or less. The sides 104B of the dots 104 have an inclination angle of 5° or more and 56° or less.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a glass substrate. [Background technology]

[0002] During the manufacturing process of semiconductor devices, glass substrates are sometimes used as members for supporting the semiconductor devices. For example, as shown in Patent Documents 1 and 2, marks may be formed on the surface of such glass substrates by irradiating the surface with laser light and engraving it.

[0003] [Patent Document 1] International Publication No. 2018 / 150759 [Patent Document 2] Japanese Patent Application Publication No. 2019-131462 Summary of the Invention [Problem to be solved by the invention]

[0004] However, glass substrates are generally highly brittle, and there is a risk of cracks occurring starting from the marks engraved on the surface. Therefore, there is a tendency to process the marks shallowly to reduce the probability of cracks. On the other hand, if the depth of the marks is reduced to prevent cracks, there is a risk that the visibility of the marks and the readability of the reading device will decrease. Therefore, there is a need to prevent cracks in the glass substrate while also suppressing the decrease in the visibility of the marks.

[0005] The present invention has been made in view of the above-mentioned problems, and has an object to provide a glass substrate that can suppress cracking and also suppress a decrease in visibility of marks. [Means for solving the problem]

[0006] In order to solve the above-mentioned problems and achieve the object, the glass substrate of the present disclosure is a glass substrate having a mark composed of a plurality of dots formed on its surface, wherein the depth of the dots is 0.5 μm or more and 7.0 μm or less, and the inclination angle of the side surface of the dots is 5° or more and 56° or less. [Effects of the Invention]

[0007] According to the present invention, it is possible to suppress cracking while suppressing a decrease in the visibility of the mark. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a schematic diagram of a glass substrate according to this embodiment. [Figure 2] FIG. 2 is a schematic diagram of an example of a mark. [Figure 3] FIG. 3 is a schematic enlarged view of a portion of the glass substrate where dots are formed. [Figure 4] FIG. 4 is a cross-sectional view taken along line AA in FIG. [Figure 5] FIG. 5 is a diagram showing other examples of dot shapes. [Figure 6] FIG. 6 is a diagram showing other examples of dot shapes. DETAILED DESCRIPTION OF THE INVENTION

[0009] Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Note that the present invention is not limited to these embodiments, and when there are multiple embodiments, the present invention also includes configurations that are made by combining the respective embodiments. Furthermore, numerical values ​​include the range of rounding.

[0010] FIG. 1 is a schematic diagram of a glass substrate according to this embodiment. The glass substrate 10 according to this embodiment is used as a glass substrate for manufacturing semiconductor packages and can be said to be a glass substrate for supporting semiconductor devices. More specifically, the glass substrate 10 is a supporting glass substrate for manufacturing using Fan Out Wafer Level Package (FOWLP) technology. For example, when the glass substrate 10 is rectangular, it is a supporting glass substrate for manufacturing Fan Out Panel Level Package (FOPLP). However, the use of the glass substrate 10 is not limited to supporting semiconductor devices or manufacturing FOWLP or FOPLP, and may be any use, such as a glass substrate used to support any component. The glass substrate 10 may also be glass or glass-ceramic processed into any product, such as a cover glass for an image sensor or a substrate for a semiconductor device.

[0011] As shown in FIG. 1, glass substrate 10 is a plate-like member having surface 10A (one surface) as one major surface and surface 10B (the other surface) as the major surface opposite surface 10A. Glass substrate 10 has a circular disk shape when viewed from a plane, i.e., from a direction perpendicular to surface 10A. In other words, glass substrate 10 has a wafer shape. Glass substrate 10 may have a notch N formed on its outer peripheral surface, resulting in a circular shape with a portion of the periphery cut out. However, the shape of glass substrate 10 is not limited to a disk shape and may be any shape, such as a polygonal plate such as a rectangle. Furthermore, notch N is not a required component, and glass substrate 10 does not necessarily have to have notch N. Hereinafter, the direction perpendicular to surface 10A will be referred to as the Z direction. The Z direction can also be referred to as the thickness direction of glass substrate 10.

[0012] (diameter of glass substrate) The diameter D0 of the glass substrate 10 is preferably 150 mm or more and 700 mm or less, more preferably 150 mm or more and 600 mm or less, and even more preferably 150 mm or more and 450 mm or less. Having the diameter D0 within this range allows for proper support of components such as semiconductor devices. Note that the diameter D0 refers to the diameter when the glass substrate 10 is circular, but when the glass substrate 10 is not circular, it may refer to the maximum distance between any two points on the outer periphery of the glass substrate 10.

[0013] (thickness of glass substrate) The thickness of the glass substrate 10, i.e., the length in the Z direction between the surface 10A and the surface 10B, is preferably 2 mm or less, more preferably 0.5 mm to 1.8 mm, and even more preferably 0.6 mm to 1.5 mm. If the thickness of the glass substrate 10 exceeds this range, the weight increases, making it difficult to handle in semiconductor manufacturing equipment. If the thickness is smaller than this range, the rigidity when used as a support member is low, and warping of the glass and semiconductor device increases, making it unsuitable for use in semiconductor device manufacturing.

[0014] (Glass substrate composition) The glass substrate 10 preferably contains the following compounds in terms of mass % (wt %) based on oxides: By making the glass substrate 10 have the following composition, it is possible to properly support members. SiO2: 40 wt% or more and 75 wt% or less is preferable, and 50 wt% or more and 75 wt% or less is more preferable. Al2O3: preferably 0 wt% or more and 20 wt% or less, more preferably 0 wt% or more and 15 wt% or less B2O3: preferably 0 wt% or more and 20 wt% or less, more preferably 0 wt% or more and 10 wt% or less MgO: 0 wt% to 25 wt% is preferable CaO: preferably 0 wt% or more and 25 wt% or less, and more preferably 0 wt% or more and 15 wt% or less SrO: preferably 0 wt% or more and 10 wt% or less BaO: preferably 0 wt% or more and 20 wt% or less, more preferably 0 wt% or more and 15 wt% or less Li2O: 0 wt% or more and 40 wt% or less is preferable Na2O: preferably 0 wt% or more and 15 wt% or less K2O: 0 wt% or more and 10 wt% or less is preferable ZrO2: 0 wt% or more and 10 wt% or less is preferable, 0 wt% or more and 8 wt% or less is more preferable, and 0 wt% or more and 5 wt% or less is even more preferable. TiO2: 0 wt% to 5 wt% is preferred Y2O3: 0 wt% to 10 wt% is preferable

[0015] (mark) A mark 100, which is an engraving, is formed on the surface 10A of the glass substrate 10. The mark 100 may be an identifier composed of at least one of numbers, letters, two-dimensional codes, and figures, for example. There may be one or more numbers, letters, two-dimensional codes, and figures. The mark 100 as an identifier can be said to be a mark for identifying the glass substrate 10. The mark 100 as an identifier can be used, for example, to identify and manage the glass substrate 10.

[0016] The mark 100 is not limited to an identifier for identifying the glass substrate 10 and may be, for example, an alignment mark. An alignment mark is, for example, a mark for positioning the glass substrate 10 and can be used to align the position and direction of the glass substrate 10 during processing such as handling, cutting, chamfering, and bonding. The alignment mark may also be a mark for determining the orientation of the glass. That is, when stacking devices on a glass substrate, the mark may be engraved on the side opposite the side on which the devices are stacked to accommodate variations in warpage during device manufacturing. As a result, the alignment mark can be used to determine the direction of warpage of the glass. By engraving the mark on the side opposite the side on which the devices are stacked, the identifier of the glass substrate 10 can be recognized even after the devices are stacked. The direction of warpage is determined by the positive or negative bow, but it can also be determined by the amount of deflection at three points of support. The article to be bonded to the glass may be not only a device, but also a metal or organic thin film, a semiconductor wafer such as Si, glass, etc.

[0017] Hereinafter, one number, letter, or figure constituting the mark 100 will be referred to as a mark element 102. That is, the mark 100 is made up of a plurality of mark elements 102. However, the mark 100 may also be made up of a single mark element 102.

[0018] FIG. 2 is a schematic diagram of an example of a mark. In the example of FIG. 2, the mark 100 is shown as an identifier configured by 12 mark elements 102 arranged linearly in a single row. However, the mark 100 is not limited to this configuration. For example, the mark 100 may be configured by the respective mark elements 102 being arranged nonlinearly. Furthermore, the mark 100 may be configured by the respective mark elements 102 being arranged linearly or nonlinearly in two or more rows.

[0019] The overall dimensions of the mark 100 are not particularly limited. For example, in the case of a linear array of the mark elements 102 as shown in FIG. 2, the character spacing L1 may be in the range of 1.420±0.025 mm, and the vertical length L2 may be 1.624±0.025 mm. When the mark 100 is configured with a non-linear array of the mark elements 102, the character spacing L1 and the vertical length L2 of the mark 100 are defined as the lengths of the first and second sides of the smallest rectangle that includes the mark 100, respectively. The character spacing L1 refers to the distance between the center of a mark element 102 and the center of a mark element 102 that is horizontally adjacent to that mark element 102, and the vertical length L2 refers to the vertical distance between the centers of the dots 104 on the farthest side of the mark element 102 in the vertical direction and the dots 104 on the farthest side of the mark element 102 in the vertical direction.

[0020] The mark element 102 (mark 100) is composed of a plurality of dots 104. In other words, a single mark element 102 or mark 100 is formed by a plurality of dots 104. In this embodiment, the dots 104 do not overlap each other but are spaced apart. The pitch P between adjacent dots 104 is defined by SEMI AUX015-1106 SEMI OCR CHARACTER OUTLINES and SEMI-T7-0303, and is determined by the type of font or two-dimensional code. The pitch P refers to the distance between the center of one dot 104 and the center of the dot 104 adjacent to that dot 104 in the direction along the surface 10A.

[0021] The dots 104 are created by mechanical processing such as laser processing or sandblasting, chemical etching, printing, etc. In particular, when manufactured by laser processing, the mark element 102 is composed of a plurality of laser irradiation marks. The size of the laser irradiation marks and the pitch of the irradiation marks are determined by the configuration of the optical system of the laser processing machine.

[0022] (dot) FIG. 3 is a schematic enlarged view of a portion of a glass substrate where dots are formed, and FIG. 4 is a cross-sectional view taken along the line AA in FIG. 3. FIG. 4 can be considered a cross-sectional view of the glass substrate 10 taken along a plane PL passing through the center of the dot 104 and aligned in the Z direction. The dot 104 refers to a depression formed on the surface 10A of the glass substrate 10. However, the dot shape does not necessarily have to be a depression, i.e., a concave shape. For example, when formed by printing, the dot is convex, and when formed by sandblasting or the like, the surface roughness of the corresponding area increases, improving the visibility of the mark. In this embodiment, the dot 104 is formed by irradiating the surface 10A with laser light. That is, the dot 104 in this embodiment can be considered to be a laser irradiation mark (irradiation mark of laser light). One dot 104 may be formed by multiple laser irradiation marks or by a single laser irradiation mark. The laser may be irradiated multiple times at the same location to make the depth of the dot after processing easier to read, or the dot may be formed by irradiating with a laser at a fixed pitch. A single laser irradiation mark refers to an irradiation mark formed by one shot of laser light. That is, the dot 104 may be formed by laser light irradiated in one cycle from when the laser light is output until it is stopped, or may be formed by multiple laser irradiation marks. That is, the dot 104 may be formed by laser light irradiated intermittently over multiple cycles.

[0023] (dot shape) As shown in Fig. 3, the dots 104 are circular when viewed from the Z direction. However, the shape of the dots 104 when viewed from the Z direction is not limited to a circle. For example, the dots 104 may be elliptical when viewed from the Z direction. Furthermore, multiple laser irradiation marks may be combined to form a ring, a rectangle, a double circle, an incomplete circle like the letter "C," or a spiral shape.

[0024] As shown in FIG. 4, the dot 104 has a bottom surface 104A and a side surface 104B. The bottom surface 104A refers to the bottom portion of the dot 104, and the side surface 104B refers to the side surface portion connecting the bottom surface 104A of the dot 104 to the surface 10A of the glass substrate 10. The side surface 104B includes a side surface portion 104B1, a connecting portion 104B2, and a connecting portion 104B3. The side surface portion 104B1 is a portion that forms the side surface of the dot 104. The connecting portion 104B2 is a portion formed at the end of the side surface portion 104B1 opposite to the Z direction and has an R-shape that connects the bottom surface 104A and the side surface portion 104B1. The connecting portion 104B3 is a portion formed at the end of the side surface portion 104B1 on the Z direction side and has an R-shape that connects the side surface portion 104B1 to the surface 10A of the glass substrate 10. However, the side surface 104B is not limited to including the R-shaped connection portions 104B2 and 104B3, and the connection portion between the bottom surface 104A and the side surface portion 104B1 and the connection portion between the side surface portion 104B1 and the surface 10A of the glass substrate 10 may have an edge shape (angular shape).

[0025] 5 and 6 are diagrams showing other examples of the shape of the dot 104. As shown in FIG. 5, depending on the quality of the glass and the quality of the laser processing, a protrusion may occur near the side surface 104B on the front surface 10A. If the central axis AX of the dot 104 along the Z direction is taken as the axial direction, the protrusion near the side surface 104B can be considered to be a convex portion formed on the front surface 10A along the periphery of the dot 104 and radially outward from the dot 104. Furthermore, a depression may occur near the side surface 104B on the bottom surface 104A. The depression near the side surface 104B can be considered to be a recess (groove) formed on the bottom surface 104A along the periphery of the dot 104 and radially inward from the side surface 104B1 of the dot 104. This protrusion or depression is preferably less than 50% of the depth H of the dot 104 in the Z direction, and more preferably less than 25%. The protrusions or depressions preferably extend radially from the dot 104 within a range of 50% or less of the diameter D of the dot 104, more preferably within a range of 25% or less. That is, the width of the protrusions or depressions (the length of the protrusions or depressions in the radial direction of the dot 104) is preferably 50% or less of the diameter D, more preferably 25% or less of the diameter D. Having the protrusions or depressions within this range ensures ease of reading. It is particularly desirable for the protrusions to be negligibly small. To remove the protrusions after laser processing, chemical treatment with a chemical solution such as hydrofluoric acid or mechanical polishing using an abrasive or polishing pad may be performed. The protrusions may be processed locally around the dots, or uniformly across the entire substrate. While it is desirable for the surface roughness of the processed area after the protrusions are removed to be the same as that of the entire substrate, the surface roughness around the inscription may be reduced to reduce scattering of light from the reader and facilitate reading. Furthermore, when visibility cannot be ensured with a single circle, mark shapes such as double circles may be used, as shown in Figure 6. In either case, abrupt changes in shape are minimized to avoid stress concentration and maintain high strength of the glass substrate.

[0026] (dot diameter) The diameter D of the dot 104 is preferably 50 μm or more and 200 μm or less, more preferably 80 μm or more and 150 μm or less, and even more preferably 90 μm or more and 120 μm or less. By making the diameter of the dot 104 within this range, each dot 104 can be made relatively large, allowing the mark 100 to be properly viewed. As shown in FIG. 4, the diameter D of the dot 104 may refer to the diameter of an imaginary circle formed by the intersection of a curved surface (corresponding to the side of a truncated cone) along the side surface portion 104B1 and a plane along the surface 10A. Furthermore, if the dot 104 is not circular, the diameter D may be the longest distance between two points on the periphery of the imaginary region formed by the intersection of the plane along the side surface portion 104B1 and the plane along the surface 10A.

[0027] (dot depth) The depth H of the dots 104 is 0.5 μm to 7.0 μm, preferably 0.5 μm to 5.0 μm, and more preferably 0.5 μm to 3.0 μm. By setting the depth H within this range, cracks in the glass substrate 10 originating from the dots 104 can be suppressed, ensuring ease of reading. The depth H refers to the distance between the surface 10A and the bottom surface 104A in the Z direction. The depth H of the dot 104 is measured using the following method. The cross-sectional shape of any dot in the mark is measured using the laser microscope described above. Then, the lowest point of the cross-section is taken as S, and the difference in the Z direction between the surface 10A, which is the main surface of the glass, and the lowest point S is taken as the depth H. However, in the case of a configuration in which the outer periphery of the dot has a concave shape as shown in Figure 5, the concave on the outer periphery of the dot does not need to be taken into account as the lowest point. The depth H can be measured using an OLYMPUS OLS4000. Furthermore, when the deviation in the depth of the bottom surface excluding the recess occurring on the radially inner side of the bottom surface is ΔH, ΔH is preferably 50% or less of the depth H, and more preferably 25% or less.

[0028] (surface roughness of the bottom of the dot) The arithmetic mean roughness Ra of the bottom surface 104A of the dot 104, as specified in JIS B 0601:2001, is preferably 0.1 μm or less, more preferably 0.01 μm or more and 0.1 μm or less, and even more preferably 0.01 μm or more and 0.05 μm or less. Furthermore, the maximum height Rz of the bottom surface 104A of the dot 104, as specified in JIS B 0601:2001, is preferably 1 μm or less, more preferably 0.01 μm or more and 0.5 μm or less. Having the surface roughness of the bottom surface 104A within this range prevents substrate cracks originating from microcracks in the inscription, facilitating inscription reading. If the surface roughness is greater than this range, microcracks may be present, reducing the fracture stress of the inscription and potentially causing glass substrate cracks originating from the inscription. On the other hand, if the surface roughness is smaller than this range, the reference light for inscription reading may not be scattered or reflected properly, potentially resulting in inscription reading failure. The arithmetic mean roughness Ra and maximum height Rz are calculated by sampling only a reference length. The reference length may be, for example, 30 μm. The arithmetic mean roughness Ra and maximum height Rz can be measured using an OLYMPUS OLS4000. The magnification of the objective lens used in the measurement is 50x.

[0029] (Surface roughness of the side of the dot) The arithmetic mean roughness Ra of the side surface 104B1 of the dot 104, as specified in JIS B 0601:2001, is preferably 1 μm or less, more preferably 0.1 μm or less, and even more preferably 0.01 μm to 0.05 μm. By ensuring that the surface roughness of the side surface 104B1 falls within this range, even when the depth H of the dot 104 is shallow as in the above range, light can be appropriately reflected, thereby preventing a decrease in the visibility of the mark 100. The arithmetic mean roughness Ra of the side surface 104B1 is calculated by extracting a reference length from the roughness curve of the side surface 104B1. The reference length may be, for example, 30 μm.

[0030] (Angle of the dot side) In this embodiment, the diameter of the dot 104 decreases toward the bottom surface 104A. The inclination angle θ of the side surface 104B of the dot 104 is 5° to 56°, preferably 5° to 55°, and more preferably 15° to 55°. By setting the inclination angle θ within this range, even when the depth H of the dot 104 is shallow within the above range, light is appropriately reflected, thereby preventing a decrease in the visibility of the mark 100. If the inclination angle θ is larger than this range, the reflection area for the light source incident from the main surface side for mark reading becomes small, making reading difficult. The inclination angle θ refers to the angle between the bottom surface 104A and the side surface 104B of the dot 104 and can also be considered the gradient of the dot 104. The inclination angle θ can also be considered the angle between the bottom surface 104A and the side surface 104B, which passes through the side surface portion 104B1 and is aligned with the plane PL, and the line segment LI. More specifically, line segment LI can be said to be a straight line that passes from position P1 to position P2 on side surface 104B and is aligned with plane PL. Position P1 refers to a position that is 20% of the depth H away from bottom surface 104A in the Z direction, and position P2 refers to a position on side surface 104B that is 80% of the depth H away from bottom surface 104A in the Z direction. In the example of Fig. 4, position P1 is the boundary between side surface portion 104B1 and connecting portion 104B2, and position P2 is the boundary between side surface portion 104B1 and connecting portion 104B3.

[0031] (Glass substrate manufacturing method) The method for manufacturing the glass substrate 10 in this embodiment includes a preparation step of preparing a glass plate, i.e., a glass substrate before the mark 100 is formed, and an irradiation step of irradiating the surface of the glass plate with laser light to form the mark 100 and manufacture the glass substrate 10. In the preparation step, glass raw material is converted into a glass state using any glass melting and forming method, such as float, fusion, or ingot molding, to manufacture a glass plate, which is then processed into the shape of the glass substrate. In this embodiment, the glass substrate is circular, so the glass is cut into a circular shape by any method, such as slicing or circular cutting, to form a circular glass plate. The circularly cut glass plate is subjected to edge chamfering and surface grinding / polishing, and then undergoes cleaning and inspection processes to complete the preparation step. In the irradiation step, a process of irradiating the surface of the glass plate with laser light to form dots 104 is repeated to form a mark 100 consisting of multiple dots 104 on the surface of the glass plate. In the irradiation step, the glass surface is irradiated with laser light to form dots 104. The laser light is emitted from a light source with a wavelength of, for example, 193 nm, and is irradiated onto the glass surface from the light source through various optical devices. The spot diameter may be adjusted by an optical system so that the dot diameter is approximately 100 μm. The glass surface is moved in the x and y directions using a scanner, but an x ​​and y stage or the like may also be used.

[0032] (effect) As described above, the glass substrate 10 according to this embodiment has a mark 100 formed on its surface 10A and composed of a plurality of dots 104. The depth H of the dots 104 is 0.5 μm or more and 7.0 μm or less, and the inclination angle θ of the side surface 104B of the dot 104 is 5° or more and 56° or less. By setting the depth H of the dots 104 within this range, the glass substrate 10 according to this embodiment can suppress cracks originating from the dots 104. However, making the depth H of the dots 104 shallow in this manner may reduce the visibility of the mark 100. In contrast, by setting the inclination angle θ of the dots 104 within this range, the glass substrate 10 according to this embodiment can appropriately reflect light at the dots 104 and suppress a reduction in the visibility of the mark 100. That is, the glass substrate 10 of the embodiment has a depth H of 0.5 μm or more and 7.0 μm or less, and an inclination angle θ of 5° or more and 56° or less, thereby suppressing cracks originating from the dots 104 while suppressing a decrease in the visibility of the mark 100.

[0033] The depth H of the dot 104 is preferably 0.5 μm or more and 5.0 μm or less, and the inclination angle θ of the side surface 104B of the dot 104 is preferably 5° or more and 55° or less. By setting the depth H and the inclination angle θ within these ranges, it is possible to suitably suppress cracks originating from the dot 104 while suitably suppressing a decrease in the visibility of the mark 100.

[0034] The arithmetic mean roughness Ra of the bottom surfaces 104A of the dots 104, as specified in JIS B 0601:2001, is preferably 0.1 μm or less. By setting the arithmetic mean roughness Ra of the bottom surfaces 104A within this range, cracks originating from the dots 104 can be more suitably suppressed.

[0035] The arithmetic mean roughness Ra of the bottom surfaces 104A of the dots 104, as specified in JIS B 0601:2001, is preferably 0.01 μm or more and 0.1 μm or less. By setting the arithmetic mean roughness Ra of the bottom surfaces 104A within this range, cracks originating from the dots 104 can be more suitably suppressed.

[0036] It is preferable that the diameter D of the dot 104 be 50 μm or more and 200 μm or less. By making the diameter D of the dot 104, which is the smallest unit of the mark 100, relatively large in this manner, the dot 104 can appropriately reflect light, thereby suppressing a decrease in the visibility of the mark 100.

[0037] The mark 100 is preferably at least one of an identifier and an alignment mark. By configuring the mark 100 for such purposes with the dots 104 described above, it is possible to appropriately suppress a decrease in the visibility of the identifier or alignment mark.

[0038] The mark 100 is preferably used to determine the direction of warpage of the glass substrate 10. The mark 100 having the shape according to this embodiment is suitable for determining the direction of warpage of the glass substrate 10.

[0039] The glass substrate 10 is preferably circular or rectangular in shape, as this shape allows the glass substrate 10 to properly support a semiconductor device.

[0040] The glass substrate 10 is preferably used as a glass substrate for supporting a semiconductor device, since the glass substrate 10 can suppress breakage from the mark portion, and is therefore preferable as a glass substrate for supporting a semiconductor device.

[0041] (Example) Next, examples will be described. Table 1 shows each example.

[0042] [Table 1]

[0043] (Example 1) In Example 1, an EN-A1 glass substrate with a diameter of 300 mm and a thickness of 1.0 mm was prepared. The surface of the glass substrate was irradiated multiple times with a laser beam having a wavelength of 193 nm to form dots. The dot diameter was 100 μm, the dot depth was 0.5 μm, the arithmetic mean roughness Ra of the bottom surface of the dot was 0.01 μm, and the inclination angle of the dot side surface was 17.4°. The dot depth, angle, arithmetic mean roughness Ra of the bottom surface, and maximum height Rz were measured using a laser microscope, and the measurement length for the arithmetic mean roughness and maximum height was 30 μm.

[0044] (Examples 2-4) In Examples 2 to 4, laser processing was performed using the same settings and the same glass as in Example 1, with the number of shots adjusted to increase the dot depth. The conditions were the same as in Example 1, except that the dot depth, tilt angle, arithmetic mean roughness Ra, and maximum height Rz were as shown in Table 1. In Example 2, the protrusion near the side surface was measured and found to be 0.5 μm in height and 15 μm in width. The depression formed on the inner radial surface was measured and found to be 0.4 μm in height (depth) and 15 μm in width. The variation in the height of the bottom surface, ΔH, was 0.4 μm.

[0045] (Examples 5-7) In Examples 5 to 7, a laser with a wavelength of 532 nm was used to form multiple laser irradiation marks with a diameter of 10 μm, thereby forming double-circular dots with an outer diameter of 100 μm. The dot depth, tilt angle, arithmetic mean roughness Ra, and maximum height Rz were as shown in Table 1.

[0046] (evaluation) For the evaluation, light of a specified intensity was irradiated from a position at an elevation angle of 70 degrees toward the vicinity of the mark on the glass surface, and the reflected light was read by a reader (Insight1742 manufactured by Cognex) installed at an elevation angle of 90 degrees. For the evaluation, if the reader was able to successfully read the marking, it was deemed to have been able to read the reflected light and was given a "good" mark, meaning it could not read the reflected light, and if it was not able to be read, it was deemed to have failed and was given a "bad" mark.

[0047] In Examples 1 to 4 and 7, which are working examples, it is possible to read reflected light, and it is clear that a decrease in visibility of the mark can be suppressed. On the other hand, in Examples 5 and 6, which are comparative examples, the accuracy of the tilt angle (elevation angle) is high, so there are few elements that reflect the irradiated light for reading, and it is therefore possible to read the reflected light, and visibility of the mark is reduced. In Example 7, which is an working example, the marking depth is sufficiently deep at 5 μm or more, and reflected light can be successfully read.

[0048] Although the embodiments of the present invention have been described above, the embodiments are not limited to the contents of these embodiments. Furthermore, the above-described components include those that can be easily imagined by a person skilled in the art, those that are substantially the same, and those that are within the scope of what is called equivalents. Furthermore, the above-described components can be combined as appropriate. Furthermore, various omissions, substitutions, or modifications of the components can be made without departing from the spirit of the above-described embodiments. [Explanation of symbols]

[0049] 10 Glass substrate 10A, 10B surface 100 marks 104 dots 104A bottom 104B Side

Claims

1. A glass substrate having a mark made up of a plurality of dots formed on its surface, The dot is composed of one depression, The depth of the dots is 0.5 μm or more and 7.0 μm or less, the inclination angle of the side surface of the dot is 15° or more and 55° or less; the arithmetic mean roughness Ra of the bottom surface of the dots as specified in JIS B 0601:2001 is 0.01 μm or more and 0.1 μm or less; The diameter of the dots is 50 μm or more and 200 μm or less. Glass substrate.

2. 2. The glass substrate according to claim 1, wherein the depth of the dots is 0.5 μm or more and 5.0 μm or less.

3. The glass substrate according to claim 1 , wherein the mark is at least one of an identifier and an alignment mark.

4. The glass substrate according to claim 1 , wherein the mark is used to determine the direction of warpage of the glass substrate.

5. The glass substrate according to claim 1 , which has a circular or rectangular shape.

6. The glass substrate according to claim 1 , which is used as a glass substrate for supporting a semiconductor device.

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