Ceramic substrate and manufacturing method for the same, and light-emitting device and manufacturing method for the same

Abstract

To provide a highly reliable ceramic substrate and a manufacturing method for the same, as well as a light-emitting device and manufacturing method for the same, which can improve the adhesion between a ceramic plate and a conductive member inside a through hole or recess in the ceramic plate, and suppress metal migration within the conductive member.SOLUTION: The manufacturing method for a ceramic substrate includes irradiating a ceramic plate containing aluminum nitride, which has a first surface and a second surface opposite to the first surface, with a laser so as to precipitate aluminum, forming a through-hole or recess in the ceramic plate, removing the precipitated aluminum from the inner surface of the through-hole or recess, and placing a conductive paste inside the through-hole or recess.SELECTED DRAWING: Figure 12A

Description

[Technical Field]

[0001] The present disclosure relates to a ceramic substrate and a manufacturing method thereof, and a light emitting device and a manufacturing method thereof. [Background technology]

[0002] In recent years, in order to reduce the size, improve the functionality, and increase the integration of electronic devices or components, a substrate has been proposed in which through-holes (also referred to as "holes" or "vias") are formed in an insulating substrate and a conductive material such as copper or silver is placed in the through-holes to electrically connect both surfaces of the substrate. For example, a via-filled substrate is known that has an insulating substrate with a hole and a conductive via portion formed by a conductor filled in the hole, in which the porosity of the conductive via portion is 10% by volume or less, there is substantially no gap between the conductive via portion and the wall surface of the hole, and the conductive via portion is formed by a conductive via body having a sea-island structure consisting of a continuous phase and a dispersed phase, and an active metal film present at the interface with the wall surface of the hole (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2022-13766 Summary of the Invention [Problem to be solved by the invention]

[0004] The present disclosure aims to provide a highly reliable ceramic substrate and a method for manufacturing the same, and a light-emitting device and a method for manufacturing the same, which can improve adhesion between a ceramic plate and a conductive member inside a through hole or recess in the ceramic plate and can suppress migration of metal in the conductive member. [Means for solving the problem]

[0005] A method for manufacturing a ceramic substrate according to one embodiment of the present disclosure includes irradiating a ceramic plate containing aluminum nitride, the ceramic plate having a first surface and a second surface opposite the first surface, with a laser to precipitate aluminum, thereby forming a through hole or a recess in the ceramic plate; removing the aluminum precipitated on the inner surface of the through hole or the recess; and placing a conductive paste inside the through hole or the recess.

[0006] Furthermore, a ceramic substrate according to one embodiment of the present disclosure comprises a ceramic plate containing aluminum nitride, having a first surface and a second surface opposite the first surface, and having a through hole connecting the first surface and the second surface or a recess in at least one of the first surface and the second surface, and a conductive member formed inside the through hole or the recess, wherein the inner surface defining the through hole or the recess has a nitride coating having an average thickness of 10 μm or more and 35 μm or less.

[0007] Furthermore, a method for manufacturing a light-emitting device according to one embodiment of the present disclosure includes preparing the ceramic substrate manufactured by the method for manufacturing the ceramic substrate according to one embodiment of the present disclosure, and arranging a light-emitting element having an electrode on the ceramic substrate, and electrically connecting the electrode and a conductive member.

[0008] Furthermore, a light-emitting device according to one embodiment of the present disclosure includes the ceramic substrate according to one embodiment of the present disclosure and a light-emitting element having an electrode arranged on the ceramic substrate, and the electrode and the conductive member are electrically connected. [Effects of the Invention]

[0009] According to one embodiment of the present disclosure, it is possible to provide a highly reliable ceramic substrate and a manufacturing method thereof, as well as a light-emitting device and a manufacturing method thereof, which can improve adhesion between a ceramic plate and a conductive member inside a through hole or recess of the ceramic plate and can suppress migration of metal in the conductive member. [Brief explanation of the drawings]

[0010] [Figure 1A] 1 is a schematic top view illustrating an example of a ceramic substrate according to a first embodiment. [Figure 1B] 1 is a schematic bottom view illustrating an example of a ceramic substrate according to a first embodiment. [Figure 1C] 1C is a schematic cross-sectional view illustrating a cross section taken along line IC-IC in FIGS. 1A and 1B. FIG. [Figure 2] FIG. 3 is a schematic cross-sectional view showing a modified example of the ceramic substrate according to the first embodiment. [Figure 3A] FIG. 4 is a schematic top view illustrating an example of a ceramic substrate according to a second embodiment. [Figure 3B] FIG. 6 is a schematic bottom view illustrating an example of a ceramic substrate according to a second embodiment. [Figure 3C] 3C is a schematic cross-sectional view illustrating a cross section taken along line IIIC-IIIC in FIGS. 3A and 3B. FIG. [Figure 4] FIG. 10 is a schematic cross-sectional view showing a modified example of the ceramic substrate according to the second embodiment. [Figure 5] 3 is a flowchart showing an example of a method for manufacturing a ceramic substrate according to the first embodiment. [Figure 6A] 1 is a schematic cross-sectional view showing an example of a ceramic plate used in a method for manufacturing a ceramic substrate according to a first embodiment. [Figure 6B] 3 is a schematic cross-sectional view showing an example of forming a through hole in the method for manufacturing a ceramic substrate according to the first embodiment. FIG. [Figure 6C] FIG. 3 is a schematic cross-sectional view showing an example of removing precipitated aluminum in the method for manufacturing the ceramic substrate according to the first embodiment. [Figure 6D] 3 is a schematic cross-sectional view showing an example of polishing or grinding the ceramic plate in the method for manufacturing the ceramic substrate according to the first embodiment. FIG. [Figure 6E] 3 is a schematic cross-sectional view showing an example of arranging a conductive paste in the method for manufacturing a ceramic substrate according to the first embodiment. FIG. [Figure 6F] 3A to 3C are schematic cross-sectional views showing an example of forming a conductive member in the method for manufacturing a ceramic substrate according to the first embodiment. [Figure 6G] 3 is a schematic cross-sectional view showing an example of polishing or grinding the conductive member in the method for manufacturing the ceramic substrate according to the first embodiment. FIG. [Figure 7A] FIG. 6F is an enlarged cross-sectional view schematically showing an area VIIA in FIG. 6E. [Figure 7B] FIG. 6B is an enlarged cross-sectional view schematically showing an enlarged region VIIB of FIG. 6F. [Figure 8] 1 is a schematic cross-sectional view illustrating an example of a light-emitting device according to an embodiment. [Figure 9A] 10A and 10B are perspective views showing application examples of the light emitting device according to the embodiment. [Figure 9B] FIG. 9B is a cross-sectional view showing the cross section IXB-IXB of FIG. 9A. [Figure 10] 1 is a flowchart illustrating an example of a method for manufacturing a light emitting device according to an embodiment. [Figure 11A] 1 is a cross-sectional observation image of a through hole after laser irradiation in forming the through hole in Example 1. [Figure 11B] 1 is a cross-sectional observation image of a through-hole after etching in removing aluminum in Example 1. [Figure 12A] 1 is an image of a cross section of a ceramic substrate of Example 1 observed with a scanning electron microscope (SEM). [Figure 12B] 1 is an observation image of a cross section of a ceramic substrate of Example 1 using a fluorescent X-ray spectroscopic image (Ti-Kα). [Figure 13A] 1 is an image of a region including inner surfaces defining through holes on a first surface of a ceramic substrate of Example 1, observed with a metallurgical microscope. [Figure 13B] 1 is an image of a region including inner surfaces defining through-holes on a first surface of a ceramic substrate of Example 1, observed with a scanning electron microscope (SEM). DETAILED DESCRIPTION OF THE INVENTION

[0011] A ceramic substrate and a manufacturing method thereof, as well as a light emitting device and a manufacturing method thereof according to embodiments of the present disclosure, will be described in detail with reference to the drawings. However, the embodiments shown below are intended to exemplify a ceramic substrate and a manufacturing method thereof, as well as a light emitting device and a manufacturing method thereof, for realizing the technical concept of the present disclosure, and are not limited to the following.

[0012] Furthermore, unless otherwise specified, the dimensions, materials, shapes, relative arrangements, etc. of components described in the embodiments are not intended to limit the scope of the present disclosure, and are merely illustrative examples. The sizes, positional relationships, etc. of components shown in each drawing may be exaggerated for clarity. In the following description, the same names and symbols indicate the same or similar components, and detailed descriptions will be omitted as appropriate. To avoid overly complex drawings, schematic diagrams may be used in which some elements are omitted, or end views showing only the cut surface may be used as cross-sectional views.

[0013] Furthermore, in this disclosure, polygons such as rectangles, triangles, and quadrilaterals are referred to as polygons, including shapes in which the corners of the polygons have been processed, such as by rounding, chamfering, corner removal, or rounding. Shapes in which processing has been applied not only to the corners (edges of the edges) but also to the middle portions of the edges are also referred to as polygons. In other words, shapes in which partial processing has been applied while retaining the polygon as a base are included in the interpretation of "polygon" described in this disclosure.

[0014] The same applies not only to polygons, but also to words that represent specific shapes such as trapezoids, circles, and irregularities. The same also applies when dealing with the sides that form the shape. In other words, even if the corners or middle part of a side have been processed, the interpretation of "side" includes the processed part. Note that when distinguishing a "polygon" or "side" that has no processing from a processed shape, the word "strict" is added, for example, "strict quadrangle."

[0015] Furthermore, in the following description, terms indicating specific directions or positions (e.g., "upper," "lower," "X," "Y," "Z," and other terms including these terms) are used as necessary. However, the use of these terms is intended to facilitate understanding of the invention with reference to the drawings, and the meaning of these terms does not unduly limit the technical scope of the present invention. For example, when describing an "upper surface," the invention does not necessarily have to be used so that it faces upward. Furthermore, parts with the same reference numerals appearing in multiple drawings indicate the same or equivalent parts or components. Furthermore, in the embodiments, "cover" is not limited to direct contact, but also includes indirect covering, for example, via another component.

[0016] Furthermore, in this specification or claims, when there are multiple elements of a certain type and each element needs to be expressed separately, the elements may be distinguished by adding "first," "second," etc. to the beginning of the element.

[0017] [Ceramic substrate] First Embodiment Fig. 1A is a schematic top view showing an example of a ceramic substrate according to the first embodiment. Fig. 1B is a schematic bottom view showing an example of a ceramic substrate according to the first embodiment. Fig. 1C is a schematic cross-sectional view illustrating a cross section taken along line IC-IC in Figs. 1A and 1B. Each component of the ceramic substrate 100 will now be described.

[0018] The ceramic substrate 100 according to the first embodiment comprises a ceramic plate 1 containing aluminum nitride, which has a first surface 1a and a second surface 1b opposite to the first surface 1a and has a through hole 3 connecting the first surface 1a and the second surface 1b, and a conductive member 2 formed inside the through hole 3, and in the through hole 3, the inner surface 3a defining the through hole 3 has a nitride coating 4 having an average thickness of 10 μm or more and 35 μm or less.

[0019] (Ceramics plate 1) The ceramic plate 1 is an insulating member that serves as a base for forming the conductive member 2. The ceramic plate 1 is preferably a sintered one, and is not in a softened state before sintering.

[0020] The ceramic plate 1 contains aluminum nitride. The ceramic plate 1 preferably contains aluminum nitride as a main material, and may further contain other secondary materials as necessary. Here, the "main material" refers to the material that has the largest amount of substance among the materials that make up the ceramic plate 1.

[0021] The secondary material in the ceramic plate 1 is not particularly limited, but examples include ceramics other than aluminum nitride, glass, etc. These may be used alone or in combination of two or more.

[0022] The ceramics other than aluminum nitride are not particularly limited, and examples thereof include nitride ceramics such as silicon nitride and boron nitride, oxide ceramics such as aluminum oxide, silicon oxide, calcium oxide and magnesium oxide, silicon carbide, mullite, borosilicate glass, etc. These may be used alone or in combination of two or more.

[0023] The ceramic plate 1 is preferably a plate-like member having a rectangular outer shape in plan view. This rectangle may have long and short sides. Unless specifically mentioned to exclude squares, the rectangle may also include squares. Note that the outer shape of the ceramic plate 1 in plan view is not limited to a rectangle, but may also be a circle, an ellipse, a polygon, or the like.

[0024] The first surface 1a may or may not be a flat surface, but is preferably a flat surface in that it allows for suitable placement of a light emitting element when the ceramic substrate 100 is used in a light emitting device.

[0025] The second surface 1b is the surface of the ceramic plate 1 opposite to the first surface 1a. The second surface 1b may or may not be flat, but being flat is preferable because when the ceramic substrate 100 is used in a light emitting device, it can be suitably placed on a mounting substrate.

[0026] In the ceramic substrate 100 according to the first embodiment, the upper surface of the ceramic plate 1 in FIG. 1C is shown as the first surface 1a, and the lower surface of the ceramic plate 1 is shown as the second surface 1b. However, this is merely for convenience's sake; when the ceramic substrate 100 is used in a light-emitting device, a mounting substrate may be placed on the first surface 1a, and a light-emitting element may be placed on the second surface 1b.

[0027] The first surface 1a and the second surface 1b are, for example, parallel to each other. Here, when the term "parallel" is used with respect to the surfaces of the ceramic plate 1, a difference of ±5 degrees is permitted.

[0028] The through hole 3 connects the first surface 1a and the second surface 1b and is, for example, a via hole.

[0029] The shape of the opening of the through hole 3 in the plan view of the ceramic plate 1 is preferably circular or elliptical. Note that the shape of the opening of the through hole 3 in the plan view of the ceramic plate 1 is not limited to circular or elliptical, and may be polygonal including rectangular.

[0030] In the ceramic substrate 100 according to the first embodiment, the opening diameter of the through hole 3 formed on the first surface 1a and the opening diameter of the through hole 3 formed on the second surface 1b in a plan view of the ceramic plate 1 are not particularly limited and can be selected appropriately depending on the purpose, but are preferably 50 μm or more and 500 μm or less, and more preferably 50 μm or more and 200 μm or less.

[0031] In the ceramic substrate 100 according to the first embodiment, the opening diameter of the through holes 3 formed on the first surface 1a of the ceramic plate 1 is the same as the opening diameter of the through holes 3 formed on the second surface 1b. Here, when describing the opening diameters of the through holes 3 in the ceramic plate 1 as "same," a difference of ±5% or less is permitted.

[0032] When the opening of the through hole 3 is circular or elliptical, the "opening diameter" refers to the maximum diameter of the opening. When the opening of the through hole 3 is rectangular in plan view of the ceramic plate 1, the "opening diameter" refers to the length of the diagonal of the opening.

[0033] The number of through holes 3 in the ceramic plate 1 is not particularly limited and may be one or more, but from the viewpoint of mounting on a light emitting device, it is preferable that there be more than one.

[0034] When there are multiple through holes 3, there are no particular restrictions on the arrangement of the multiple through holes 3 in a planar view of the ceramic plate 1, or the pitch between one through hole 3 and another adjacent through hole 3, and these can be selected appropriately depending on the purpose.

[0035] In the through hole 3, the inner surface 3a defining the through hole 3 has a nitride coating 4 with an average thickness of 10 μm or more and 35 μm or less. That is, the nitride coating 4 is disposed at the interface between the inner surface 3a defining the through hole 3 and the conductive member 2. The nitride coating 4 improves the adhesion between the ceramic plate 1 and the conductive member 2 formed inside the through hole 3, making it possible to obtain a highly reliable ceramic substrate 100.

[0036] The inner surface 3a of the ceramic plate 1 that defines the through holes 3 has irregularities and is roughened. The recesses of the inner surface 3a that define the through holes 3 have an irregular microstructure. In the present disclosure, the irregular microstructure of the recesses of the inner surface 3a that define the through holes 3 may be referred to as, for example, dendritic or dendrite. Nitrides are present in these dendritic recesses. Therefore, the nitride coating 4 includes the inner surface 3a that defines the dendritic through holes 3 and the nitrides present in the inner surface 3a. More specifically, the nitride coating 4 includes the material that constitutes the ceramic plate 1 and nitrides, and may further include components derived from the conductive member 2.

[0037] The arithmetic mean roughness Ra of the inner surface 3a defining the through hole 3 is not particularly limited and can be selected appropriately depending on the purpose, but is preferably 1.0 μm or more and 3.5 μm or less. The arithmetic mean roughness Ra of the inner surface 3a defining the through hole 3 is measured in accordance with JIS B 0601 using a stylus-type surface roughness meter (for example, SE3500 manufactured by Kosaka Laboratory Co., Ltd.) equipped with a diamond stylus with a tip curvature radius r of 2 μm.

[0038] The nitride in the nitride coating 4 may be, for example, titanium nitride.

[0039] The average thickness of the nitride coating 4 is 10 μm or more and 35 μm or less, and preferably 10 μm or more and 25 μm or less.

[0040] In the ceramic substrate 100 according to the first embodiment, the average thickness of the nitride coating 4 is measured as follows. A scanning electron microscope (SEM) image is obtained by observing, at a magnification of 250x, a region X including at least a portion of the conductive member 2 and a region of the ceramic plate 1 extending from the inner surface 3a defining the through hole 3 to at least 50 μm in the depth direction of the recess in a cross section in the thickness direction of the ceramic substrate 100 and passing through the center of gravity of the opening of the through hole 3. In the SEM image of region X, the maximum length l of the dendritic recess extending from the inner surface 3a defining the through hole 3 toward the ceramic plate 1 is measured. In the same manner, the maximum length l is measured at five randomly selected locations on the ceramic substrate 100, and the average maximum length L of the five locations is determined. This average maximum length L is defined as the average thickness of the nitride coating 4 in the ceramic substrate 100 according to the first embodiment.

[0041] The inner surface 3a defining the through hole 3 may have the nitride coating 4 discontinuously or continuously.

[0042] Here, having a "discontinuous" nitride coating 4 means that the nitride coating 4 on the inner surface 3a defining the through hole 3 has at least a partially discontinued region within the range of the average thickness of the nitride coating 4. In this case, in the region of the inner surface 3a defining the through hole 3 where the nitride coating 4 is discontinued, i.e., in the region without the nitride coating 4, no nitride is present in the tree-root-like recesses of the inner surface 3a defining the through hole 3.

[0043] Furthermore, when the inner surface 3a defining the through hole 3 has a discontinuous nitride coating 4, the region without the nitride coating 4 may have an aluminum film derived from the ceramic plate 1 on the inner surface 3a defining the through hole 3. In other words, when the inner surface 3a defining the through hole 3 has a discontinuous nitride coating 4, the inner surface 3a defining the through hole 3 may have a discontinuous aluminum film. In this case, the inner surface 3a defining the through hole 3 has a region with the nitride coating 4 and a region with an aluminum film. Therefore, when the inner surface 3a defining the through hole 3 has a discontinuous nitride coating 4, the inner surface 3a defining the through hole 3 does not have a continuous aluminum film.

[0044] Furthermore, having the nitride coating 4 "continuously" means that the nitride coating 4 on the inner surface 3a defining the through hole 3 is arranged without interruption within the range of the average thickness of the nitride coating 4. In other words, when the inner surface 3a defining the through hole 3 has the nitride coating 4 continuously, the inner surface 3a defining the through hole 3 does not have an aluminum film derived from the ceramic plate 1.

[0045] (Conductive member 2) The conductive member 2 is a member that provides electrical wiring in the ceramic substrate 100. The conductive member 2 is, for example, a via. In the ceramic substrate 100 according to the first embodiment, the conductive member 2 is formed inside the through hole 3. Preferably, the conductive member 2 is formed so that it is flush with the first surface 1a of the ceramic plate 1 on the first surface 1a side, and so that it is flush with the second surface 1b on the second surface 1b side.

[0046] The conductive member 2 preferably contains a eutectic structure of silver and copper. The eutectic structure of the conductive member 2 can be confirmed by observing a cross section of the ceramic substrate 100 in the thickness direction, including the cross section of the conductive member 2, with an SEM.

[0047] The ceramic substrate 100 according to the first embodiment can be suitably manufactured by a method for manufacturing a ceramic substrate according to the first embodiment, which will be described later.

[0048] <<Modification of the First Embodiment>> FIG. 2 is a schematic cross-sectional view showing a modified example of the ceramic substrate according to the first embodiment.

[0049] The modified example of the ceramic substrate 100 according to the first embodiment differs from the ceramic substrate 100 according to the first embodiment in that the opening diameter of the through hole 3 on the first surface 1a of the ceramic plate 1 is larger than the opening diameter of the through hole 3 on the second surface 1b. Here, when describing the opening diameter of the through hole 3 of the ceramic plate 1 as "large," it means that the opening diameter of the through hole 3 on the second surface 1b is larger by more than 5% compared to the opening diameter of the through hole 3 on the first surface 1a of the ceramic plate 1.

[0050] Note that Figure 2 shows an example in which the opening diameter of the through hole 3 on the first surface 1a of the ceramic plate 1 is larger than the opening diameter of the through hole 3 on the second surface 1b, but the first surface 1a and the second surface 1b are shown merely for convenience in the drawing to distinguish the surfaces, and the opening diameter of the through hole 3 on the second surface 1b of the ceramic plate 1 may be larger than the opening diameter of the through hole 3 on the first surface 1a.

[0051] There is no particular limitation on the ratio between the opening diameter of the through-hole 3 in the first surface 1a and the opening diameter of the through-hole 3 in the second surface 1b.

[0052] Second Embodiment Fig. 3A is a schematic top view showing an example of a ceramic substrate according to the second embodiment, Fig. 3B is a schematic bottom view showing an example of a ceramic substrate according to the second embodiment, and Fig. 3C is a schematic cross-sectional view illustrating a cross section taken along line IIIC-IIIC in Figs. 3A and 3B.

[0053] The ceramic substrate 100 according to the second embodiment comprises a ceramic plate 1 containing aluminum nitride, which has a first surface 1a and a second surface 1b opposite to the first surface 1a, and has a recess 5 on at least one of the first surface 1a and the second surface 1b, and a conductive member 2 formed inside the recess 5, and in the recess 5, the inner surface defining the recess 5 has a nitride coating 4 having an average thickness of 10 μm or more and 35 μm or less.

[0054] FIG. 3A shows an example in which the first surface 1a has a recess 5, but the first surface 1a and the second surface 1b are shown merely for the sake of convenience in distinguishing the surfaces in the drawing, and the second surface 1b may also have the recess 5.

[0055] The ceramic substrate 100 of the second embodiment differs from the ceramic substrate 100 of the first embodiment in that the through holes 3 in the ceramic substrate 100 of the first embodiment are replaced with recesses 5, but the configuration other than the recesses 5 is the same as that of the ceramic substrate 100 of the first embodiment.

[0056] The recess 5 is a bottomed hole that does not penetrate from the first surface 1a to the second surface 1b. The recess 5 has a side surface 5a that connects the opening to the bottom in the Z-axis direction, and a bottom 5b. That is, the inner surface that defines the recess 5 is made up of the side surface 5a and bottom 5b of the recess 5. The recess 5 has the same configuration as the through hole 3, except that the cross-sectional shape in the Z-axis direction is different.

[0057] The maximum depth of the recess 5, i.e., the maximum length in the Z-axis direction of the inner surface defining the recess 5 in a cross-sectional view, is not particularly limited and can be selected appropriately depending on the thickness of the ceramic plate 1, but is preferably 25 μm or more and 300 μm or less, more preferably 50 μm or more and 200 μm or less, and even more preferably 50 μm or more and 100 μm or less.

[0058] <<Modification of the Second Embodiment>> FIG. 4 is a schematic cross-sectional view showing a modified example of the ceramic substrate according to the second embodiment.

[0059] The modified example of the ceramic substrate 100 according to the second embodiment differs from the ceramic substrate 100 according to the first embodiment in that the opening diameter of the recess 5 is larger than the bottom diameter of the bottom 5b of the recess 5. Here, when describing the opening diameter of the recess 5 of the ceramic plate 1 as "large," it means that the bottom diameter of the bottom 5b of the recess 5 is larger than the opening diameter of the recess 5 by more than 5%.

[0060] The ratio between the opening diameter of the recess 5 and the bottom diameter of the bottom 5b of the recess 5 is not particularly limited.

[0061] The cross-sectional shape of the recess 5 of the ceramic substrate 100 according to the second embodiment in the Z-axis direction is not limited to a rectangle, but may be, for example, a triangle, a trapezoid, a U-shape, or the like.

[0062] [Method for manufacturing ceramic substrate] First Embodiment Fig. 5 is a flowchart showing an example of a method for manufacturing a ceramic substrate according to the first embodiment. The method for manufacturing a ceramic substrate according to the first embodiment will be described with reference to Figs. 6A to 7B.

[0063] The method for manufacturing a ceramic substrate according to the first embodiment includes the steps of irradiating a ceramic plate 1 containing aluminum nitride, which has a first surface 1a and a second surface 1b opposite to the first surface 1a, with a laser L to precipitate aluminum 11, thereby forming through holes 3 in the ceramic plate 1 (S1), removing the aluminum 11 precipitated on the inner surface 3a that defines the through holes 3 (S2), and disposing a conductive paste 30 inside the through holes 3 (S3). The method for manufacturing a ceramic substrate according to the first embodiment preferably further includes the steps of polishing or grinding the ceramic plate 1 (S2-1), forming a conductive member 2 (S4), and polishing or grinding the conductive member 2 (S5).

[0064] (S1) Forming a through hole Fig. 6A is a schematic cross-sectional view showing an example of a ceramic plate used in the method for manufacturing a ceramic substrate according to Embodiment 1. Fig. 6B is a schematic cross-sectional view showing an example of forming a through hole in the method for manufacturing a ceramic substrate according to Embodiment 1.

[0065] A ceramic plate 1 containing aluminum nitride is prepared, having a first surface 1a and a second surface 1b opposite to the first surface 1a. The ceramic plate 1 may be a ceramic precursor before sintering or a sintered ceramic, but a sintered ceramic is preferred because there is no dimensional change due to sintering.

[0066] In the step S1 of forming the through holes, the ceramic plate 1 is irradiated with a laser L so as to precipitate aluminum 11, thereby forming the through holes 3 in the ceramic plate 1. There are no particular limitations on the laser L as long as it can precipitate aluminum 11 derived from the ceramic plate 1 at the irradiated portion 20 of the through holes 3, but a laser L that can be thermally processed is preferred.

[0067] In the method for manufacturing a ceramic substrate according to the first embodiment, the pulse width of the laser L that is maximized in the pulse repetition period is a continuous wave (CW), and the pulse width of the laser L includes a continuous wave.

[0068] The laser L capable of thermal processing preferably has a pulse width in the microsecond or nanosecond range, more preferably in the nanosecond range, and even more preferably from 1 nanosecond to 23 nanoseconds.

[0069] Examples of lasers L that can be used for thermal processing include lasers with an oscillation wavelength of 750 nm or more and lasers with an output of 500 W or more. Specific examples of lasers L that can be used for thermal processing include fiber lasers, disk lasers, and CO2 lasers.

[0070] There are no particular limitations on the pulse width, output, and wavelength of the laser L that can be used for thermal processing, and processing can be performed under conditions such as a fiber laser (CW: 1 nanosecond, wavelength: 532 nm, output: 1,500 W), a disk laser (CW: 3 nanoseconds, wavelength: 1,064 nm, output: 1,000 W), or a CO2 laser (pulse: 16 nanoseconds x 200 times, wavelength: 10,600 nm, equivalent output: 300 W to 700 W), but as long as aluminum 11 is precipitated, the conditions are not limited to these.

[0071] A laser beam L is irradiated in the Z-axis direction onto a predetermined region of the first surface 1a of the ceramic plate 1 and thermally processed, whereby the ceramic is removed by melting and sublimation mainly at the irradiated portion 20 that absorbs the irradiated laser beam L, forming a through hole 3 that penetrates from the first surface 1a to the second surface 1b. At this time, aluminum 11 precipitates at the irradiated portion 20 of the ceramic plate 1 that is irradiated with the laser beam L. The through hole 3 may be formed by a single irradiation of the laser beam L, or may be formed by gradually removing the ceramic by irradiating the laser beam L multiple times.

[0072] In the ceramic plate 1 irradiated with the laser L, heat generated by the irradiation of the laser L spreads not only in the irradiated portion 20 of the laser L but also from the irradiated portion 20 of the laser L to a peripheral portion 21. Therefore, precipitation of aluminum 11 from the ceramic plate 1 occurs not only in the irradiated portion 20 of the laser L but also in a peripheral portion 21 inside the ceramic plate 1 from the irradiated portion 20 in the X-axis direction.

[0073] (S2) Removing aluminum FIG. 6C is a schematic cross-sectional view showing an example of removing precipitated aluminum in the method for manufacturing a ceramic substrate according to the first embodiment.

[0074] In the method for manufacturing a ceramic substrate according to the first embodiment, "removing the precipitated aluminum 11" includes not only complete removal of the precipitated aluminum 11, but also removal of only the surface side and / or partial removal of the precipitated aluminum 11.

[0075] The partial removal of the precipitated aluminum 11 is not particularly limited as long as it does not impair the effects of the present disclosure, but it is preferable that 70% or more, more preferably 80% or more, and even more preferably 90% or more of the total area of ​​the inner surface 3a defining the through hole 3 is removed. The removal rate of the precipitated aluminum 11 can be confirmed by observing the cross section of the ceramic plate 1 in the thickness direction, including the cross section of the through hole 3, with an SEM or by electrical testing.

[0076] When only the surface side of the deposited aluminum 11 is removed, it is preferable that 50% or more of the deposited aluminum 11 be removed in the thickness direction, more preferably 70% or more, and even more preferably 90% or more. The deposited aluminum 11 may not be formed with a uniform thickness over the entire surface of the inner surface 3a that defines the through hole 3, and aluminum nitride may be exposed in part of the inner surface 3a that defines the through hole 3. Here, "the thickness direction of the deposited aluminum 11" means the direction from the inner surface 3a that defines the through hole 3 toward the through hole 3, i.e., the YX axis direction.

[0077] There are no particular limitations on the method for removing aluminum 11 deposited on irradiated areas 20 of the inner surface 3a that defines the through holes 3 in the step S1 of forming the through holes, but it is preferable to bring a solvent into contact with the irradiated areas 20 of the inner surface 3a that defines the through holes 3. Examples of methods for bringing a solvent into contact with the irradiated areas 20 of the inner surface 3a that defines the through holes 3 include an etching method and a method of immersing the ceramic plate 1 having aluminum deposited on the irradiated areas 20 of the inner surface 3a that defines the through holes 3 in a solvent.

[0078] The solvent is not particularly limited as long as it can remove the precipitated aluminum 11, and examples thereof include alkaline solvents such as sodium hydroxide, potassium hydroxide, and lithium hydroxide; and acidic solvents such as phosphoric acid, hydrochloric acid, sulfuric acid, nitric acid, and acetic acid. These may be used alone or in combination of two or more.

[0079] The temperature and time when the solvent is brought into contact with the irradiated portion 20 of the inner surface 3a defining the through-hole 3 are not particularly limited as long as the deposited aluminum 11 can be removed.

[0080] When the aluminum 11 deposited on the ceramic plate 1 is removed, the inner surface 3a, which has irregularities and is roughened and defines the through-hole 3, is exposed. At this time, the aluminum 11 deposited in the peripheral region 21 of the region irradiated with the laser L is also removed, and the root-like recesses 21a on the inner surface 3a defining the through-hole 3 are exposed. Therefore, the aluminum nitride of the ceramic plate 1 is exposed on the inner surface 3a defining the through-hole 3.

[0081] Furthermore, when the aluminum 11 precipitated from the ceramic plate 1 is removed, burrs 12 may be generated around the openings of the through holes 3 on the first surface 1a and the second surface 1b of the ceramic plate 1.

[0082] (S2-1) Polishing or grinding ceramic plates FIG. 6D is a schematic cross-sectional view showing an example of polishing or grinding the ceramic plate in the method for manufacturing a ceramic substrate according to the first embodiment.

[0083] In polishing or grinding the ceramic plate S2-1, burrs 12 formed on the first surface 1a and the second surface 1b of the ceramic plate 1 are polished or ground to be removed. If burrs 12 are formed in polishing or grinding the ceramic plate S2-1, it is preferable to remove the burrs 12 and make the periphery of the opening of the through hole 3 approximately flush with the first surface 1a and the second surface 1b.

[0084] Alternatively, the step of polishing or grinding the ceramic plate S2-1 may be omitted, and in the step of polishing or grinding the conductive member S5, the burrs 12 may be removed simultaneously with the polishing or grinding of the conductive member 2.

[0085] (S3) Placing conductive paste Fig. 6E is a schematic cross-sectional view showing an example of arranging a conductive paste in the method for manufacturing a ceramic substrate according to Embodiment 1. Fig. 7A is an enlarged cross-sectional view schematically showing an enlarged region VIIA of Fig. 6E.

[0086] In the step S3 of disposing the conductive paste, the conductive paste 30 is filled into the through-hole 3, thereby disposing the conductive paste 30 inside the through-hole 3. At this time, the tree-root-shaped recesses 21a are also filled with the conductive paste 30.

[0087] The step S3 of placing the conductive paste can be carried out by filling the through-holes 3 with the conductive paste 30 by, for example, screen printing, metal mask printing, or nozzle injection, so that the surface height of the conductive paste 30 is approximately the same as that of the first surface 1a and the second surface 1b of the ceramic plate 1.

[0088] In the step S3 of arranging the conductive paste, in addition to filling the through-holes 3 with the conductive paste 30, it is preferable to arrange the conductive paste 30 so as to cover the openings of the through-holes 3 and at least a portion of at least one of the first surface 1a and the second surface 1b of the ceramic plate 1. This makes it possible to prevent a decrease in dimensional accuracy due to volume shrinkage when the conductive paste 30 is sintered in the step S4 of forming the conductive member.

[0089] As a specific example, when filling the through holes 3 with the conductive paste 30 in the step S3 of disposing the conductive paste, the conductive paste 30 is filled into the through holes 3 from the first surface 1a of the ceramic plate 1 using, for example, a squeegee, which is a tool used in screen printing, and then the conductive paste 30 is filled into the through holes 3 from the second surface 1b of the ceramic plate 1 using the same squeegee as on the first surface 1a, so that the conductive paste 30 can be disposed so as to cover the opening of the through holes 3 and at least a portion of at least one of the first surface 1a and the second surface 1b of the ceramic plate 1. In other words, the conductive paste 30 can be disposed so as to continue from the through holes 3 and cover at least a portion of at least one of the first surface 1a and the second surface 1b of the ceramic plate 1.

[0090] Furthermore, in the step S3 of disposing the conductive paste, it is preferable to further dry the conductive paste 30 and pressurize the dried conductive paste 30 after disposing the conductive paste 30 and before sintering. To dry the conductive paste 30, for example, it may be dried by placing it in an electric furnace in an atmosphere at a temperature higher than room temperature but lower than 100°C. Furthermore, it is preferable to place the ceramic plate 1 with the conductive paste 30 disposed therein in the electric furnace via a pressurizing mold, so that drying and pressurization are performed simultaneously. By drying and pressing here, the conductive paste 30 is less likely to undergo volumetric shrinkage in the step S4 of forming the conductive member 2.

[0091] -Conductive Paste 30- The conductive paste 30 preferably contains an active metal brazing material, which allows a nitride coating 4 to be suitably formed on the inner surface 3a that defines the through hole 3, thereby improving the adhesion between the ceramic plate 1 and the conductive member 2. The active metal brazing material contains a eutectic powder 14 of silver and copper, an active metal powder 15, and a solvent 16, and preferably further contains an inorganic filler 17, and may further contain other components as necessary.

[0092] The active metal brazing material has fluidity, and can be freely filled into through holes 3 of any shape, and can be arranged by applying it to any shape and thickness and then curing it.

[0093] --eutectic powder 14-- The eutectic powder 14 is a eutectic powder of silver and copper, whose melting point is about 780°C.

[0094] The content of the eutectic powder 14 in the conductive paste 30 is not particularly limited, but is preferably 40% by mass or more and 95% by mass or less, where the total amount of the eutectic powder 14, the active metal powder 15, and the inorganic filler 17 is 100% by mass.

[0095] --Active metal powder 15-- After sintering, the active metal powder 15 becomes a metal compound 18 that is disposed on the inner surfaces 3 a that define the through-holes 3 and on at least a part of the surface of the inorganic filler 17 .

[0096] The active metal powder 15 is not particularly limited, and examples thereof include titanium hydride (TiH2), cerium hydride (CeH2), zirconium hydride (ZrH2), and magnesium hydride (MgH2). These may be used alone or in combination of two or more. Among these, it is preferable that the active metal powder 15 contains TiH2. When the active metal powder 15 contains TiH2, it reacts with aluminum nitride exposed on the inner surface 3a defining the through hole 3 and can become titanium nitride (TiN) as the metal compound 18. Titanium nitride is known as a barrier metal. Therefore, migration of metal in the conductive member 2 can be suppressed, resulting in a highly reliable ceramic substrate 100.

[0097] The content of the active metal powder 15 in the conductive paste 30 is not particularly limited, but is preferably 2% by mass or more and 15% by mass or less, when the total amount of the eutectic powder 14, the active metal powder 15, and the inorganic filler 17 is taken as 100% by mass. When the content of the active metal powder 15 is 2% by mass or more relative to the total amount of the eutectic powder 14, the active metal powder 15, and the inorganic filler 17, a nitride coating 4 of an appropriate thickness can be formed. Furthermore, the hydrogen derived from the active metal powder 15 can make the reaction phase a reducing atmosphere, and the conductive paste 30 can be suitably sintered. This is because if the content of the active metal powder 15 exceeds 15% by mass relative to the total amount of the eutectic powder 14, the active metal powder 15, and the inorganic filler 17, the generated hydrogen is likely to remain as voids in the conductive member 2 without being completely released.

[0098] --Solvent 16-- The solvent 16 is not particularly limited, but an organic binder is preferred. The organic binder is not particularly limited, and examples thereof include thermosetting resins and thermoplastic resins. Specific examples of organic binders include epoxy resins, silicone resins, acrylic resins, urethane resins, polyvinyl resins, ethyl cellulose resins, phenolic resins, polyimide resins, polyurethane resins, melamine resins, and polyurea resins. The organic binder may also be a solvent or resin material commonly used as a via material. These may be used alone or in combination of two or more. The organic binder functions as a sintering binder, and is therefore decomposed, evaporated, and removed in the step S4 of forming the conductive member 2.

[0099] The content of the solvent 16 in the conductive paste 30 is not particularly limited, and can be appropriately selected depending on the contents of the eutectic powder 14, the active metal powder 15, and the inorganic filler 17.

[0100] --Inorganic filler 17-- The inorganic filler 17 is not particularly limited, and examples thereof include ceramic fillers such as silica fillers, metal fillers, and glass fillers. These may be used alone or in combination of two or more. Among these, ceramic fillers are preferred as the inorganic filler 17. When the conductive paste 30 contains the inorganic filler 17, the thermal conductivity and heat dissipation characteristics of the conductive member 2 can be improved.

[0101] The ceramic filler is not particularly limited, and examples thereof include aluminum nitride (AlN), silicon nitride (Si3N4), aluminum oxide (Al2O3), and silicon carbide (SiC).

[0102] Furthermore, inorganic filler 17 is preferably a material with a linear expansion coefficient of 8 ppm or less, which can reduce the linear expansion coefficient of conductive member 2 and improve thermal shock resistance.

[0103] The median diameter of the inorganic filler 17 is not particularly limited, but is preferably 1 μm or more and 50 μm or less, and more preferably 2 μm or more and 15 μm or less.

[0104] Furthermore, inorganic filler 17 is preferably a material with a linear expansion coefficient of 5 ppm or less and a high thermal conductivity of 100 W / m·K or more. Examples of such materials include the ceramic filler described above. By dispersing such materials in conductive member 2, the difference in linear expansion coefficients can be alleviated, and reliability such as thermal shock resistance can be improved.

[0105] The thermal conductivity of the inorganic filler 17 is not particularly limited, but is preferably 20 W / (m / K) or more, and more preferably 30 W / (m / K) or more, at a measurement temperature of 300K.

[0106] The content of inorganic filler 17 in conductive paste 30 is not particularly limited, but is preferably 4% by mass or more and 50% by mass or less, when the total amount of eutectic powder 14, active metal powder 15, and inorganic filler 17 is 100% by mass.

[0107] --Other ingredients-- The other components in the conductive paste 30 are not particularly limited and may include, for example, a reducing agent such as an organic acid, a eutectic alloy powder other than the eutectic powder of silver and copper, etc. These may be used alone or in combination of two or more.

[0108] Examples of eutectic alloy powders other than the eutectic powder of silver and copper include a eutectic alloy of copper and zinc, a eutectic alloy of copper and tin, etc. These may be used alone or in combination of two or more.

[0109] The melting point of the other eutectic alloy powder is not particularly limited, but is preferably 700°C or higher and 1,200°C or lower, more preferably 720°C or higher and 1,100°C or lower, and even more preferably 780°C or higher and 850°C or lower.

[0110] The content of other eutectic alloy powders is not particularly limited as long as it does not impair the effects of the present disclosure.

[0111] (S4) Forming a conductive member Fig. 6F is a schematic cross-sectional view showing an example of forming a conductive member in the method for manufacturing a ceramic substrate according to Embodiment 1. Fig. 7B is an enlarged cross-sectional view schematically showing an enlarged region VIIB of Fig. 6F.

[0112] In forming the conductive member S4, the conductive member 2 is formed inside the through hole 3, and the nitride coating 4 is formed on the inner surface 3a that defines the through hole 3.

[0113] In step S4 of forming the conductive member, the conductive member is formed by sintering the active metal brazing material as the conductive paste 30. The sintering can be performed using a sintering furnace such as an electric furnace.

[0114] The sintering temperature for sintering the conductive paste 30 is not particularly limited, but is preferably 700° C. to 1,200° C., more preferably 720° C. to 1,000° C., and even more preferably 750° C. to 900° C. By sintering the conductive paste 30 at a preferred sintering temperature, the eutectic of silver and copper melts, and electrical continuity of the conductive member 2 can be achieved.

[0115] The sintering atmosphere when sintering the conductive paste 30 is not particularly limited, but it is preferable to use an Ar atmosphere of 99.9% or more or an Ar atmosphere of 10 -5 It is preferable that the atmosphere is a vacuum of 100 Pa or less.

[0116] The sintering time for sintering the conductive paste 30 is not particularly limited, but is preferably 5 minutes to 60 minutes, more preferably 10 minutes to 50 minutes, and even more preferably 15 minutes to 45 minutes.

[0117] The conductive member 2 produced using the conductive paste 30 includes, for example, a metal compound 18, a metal 19, and an inorganic filler 17. The solvent 16 is evaporated and removed when the conductive paste 30 is sintered.

[0118] For example, when the total content of the metal compound 18, the metal 19, and the inorganic filler 17 is taken as 100 mass%, the conductive member 2 preferably contains 1 mass% to 10 mass% of the metal compound 18, 40 mass% to 95 mass% of the metal 19, and 4 mass% to 50 mass% of the inorganic filler 17. By including the inorganic filler 17 at a predetermined ratio, the conductive member 2 can reduce volumetric shrinkage. Furthermore, by including the metal 19 at a predetermined ratio, the conductive member 2 can disperse the inorganic filler 17 in the continuous metal 19.

[0119] When the metal 19 is formed as the conductive member 2, it is a metal member that, together with the inorganic filler 17, becomes the core of the conductive member 2. The metal 19 is arranged in a state in which the inorganic filler 17 is dispersed.

[0120] In forming the conductive member S4, the silver-copper eutectic powder 14 in the conductive paste 30 is sintered to form the metal 19. Therefore, the metal 19 includes a silver-copper eutectic, and if the conductive paste 30 includes another metal eutectic powder, the metal 19 further includes the metal eutectic.

[0121] The inorganic filler 17 is arranged in a dispersed state as a plurality of particles in the conductive member 2. Here, "plurality of inorganic fillers 17" indicates that the inorganic filler 17 is not a single particle but a plurality of particles.

[0122] The inorganic filler 17 has a thickness of 100 μm in a cross-sectional view of the conductive member 2 in the Z-axis direction b. 2 per 10 μm 2 More than 75μm 2 It is preferable that they are arranged in the following ranges.

[0123] The metal compounds 18 are formed by sintering the active metal powder 15. By sintering the conductive paste 30, a reaction phase between the inorganic filler 17 and the active metal powder 15 is formed on the surface of the inorganic filler 17. The metal compounds 18 are mainly disposed on at least a part or all of the surface of the inorganic filler 17 and on at least a part of the inner surface 3a that defines the through hole 3. The metal compounds 18 include filler surface metal compounds 18a that are disposed on the surface of the inorganic filler 17 and wall surface metal compounds 18b that are disposed on at least a part of the inner surface 3a that defines the through hole 3. Preferably, the active metal powder 15, the inorganic filler 17, and components of the inner surface 3a that defines the through hole 3 are sintered, and thereby the filler surface metal compounds 18a and wall surface metal compounds 18b are disposed as reactants.

[0124] The filler surface metal compound 18a is a metal compound 18 and is arranged so as to cover at least a part or all of the surface of the inorganic filler 17. For example, when the inorganic filler 17 is aluminum nitride (AlN) or silicon nitride (Si3N4), the filler surface metal compound 18a reacts with titanium hydride (TiH2) in the active metal powder 15 before sintering to form titanium nitride (TiN) on the surface of the inorganic filler 17. The filler surface metal compound 18a then forms continuous jagged irregularities on its surface, and the surface of the inorganic filler 17 also becomes jaggedly irregular. The inorganic filler 17 with the filler surface metal compound 18a arranged on its surface is then dispersed in the continuous conductive member 2.

[0125] The wall surface metal compound 18b is disposed as the metal compound 18 on at least a portion of the inner surface 3a defining the through hole 3. For example, since the inner surface 3a defining the through hole 3 contains silicon nitride, if the pre-sintered active metal powder 15 is, for example, titanium hydride, a reaction product is generated and the wall surface metal compound 18b is formed as a compound on the inner surface 3a defining the through hole 3. The wall surface metal compound 18b forms a continuous jagged unevenness on the inner surface 3a defining the through hole 3. The wall surface metal compound 18b is also formed in the tree-root-like recesses on the inner surface 3a defining the through hole 3, forming a nitride coating 4. This improves adhesion between the inner surface 3a defining the through hole 3 and the conductive member 2. Furthermore, heat conducted from the conductive member 2 to the ceramic contained in the ceramic plate 1 via the inner surface 3a defining the through hole 3 can be efficiently dissipated.

[0126] In this manner, a ceramic substrate 100 is obtained, which includes the ceramic plate 1 and the conductive member 2 having the nitride coating 4 on the inner surface 3a that defines the through hole 3. The average thickness of the nitride coating 4 on the ceramic substrate 100 is preferably 10 μm or more and 35 μm or less, and more preferably 10 μm or more and 25 μm or less.

[0127] (S5) Polishing or grinding conductive members FIG. 6G is a schematic cross-sectional view showing an example of polishing or grinding the conductive member in the method for manufacturing a ceramic substrate according to the first embodiment.

[0128] In polishing or grinding the conductive member S5, the conductive member 2 is polished or ground so that at least one of the first surface 1a and the second surface 1b of the ceramic plate 1 in the portion covered with the conductive member 2 is exposed.

[0129] The ceramic substrate 100 obtained by forming the conductive member S4 may be used as is, for example, if in arranging the conductive paste S3, the conductive paste 30 is filled only in the through holes 3 of the ceramic plate 1. However, if the conductive member is arranged so as to cover the opening of the through holes 3 and at least a portion of at least one of the first surface 1a and the second surface 1b of the ceramic plate 1, the conductive member can be further polished or ground S5 to make the surfaces (exposed surfaces) of the first surface 1a and the second surface 1b of the ceramic plate 1 and the conductive member 2 approximately flush with each other.

[0130] Furthermore, in forming the conductive member S4, the first surface 1a and the second surface 1b of the ceramic plate 1 may become blackened, but this can be removed by polishing or grinding the conductive member S5.

[0131] <<First Modification of First Embodiment>> The first variant of the method for manufacturing a ceramic substrate according to the first embodiment differs from the method for manufacturing a ceramic substrate according to the first embodiment in that, in forming the through hole S1, laser L is irradiated so that the opening diameter of the through hole 3 on the first surface 1a of the ceramic plate 1 is larger than the opening diameter of the through hole 3 on the second surface 1b.

[0132] The cross-sectional shape of the through-holes 3 can be adjusted to a desired shape by changing the pulse width of the laser L and, if necessary, the output, and for example, by lowering the output of the laser L and shortening the irradiation time of the laser L compared to the method for manufacturing a ceramic substrate according to the first embodiment. In addition, it is preferable to irradiate the laser L from the first surface 1a side of the ceramic plate 1.

[0133] Second Embodiment The method for manufacturing a ceramic substrate according to the second embodiment differs from the method for manufacturing a ceramic substrate according to the first embodiment in that in forming a through hole S1, forming a through hole 3 in the ceramic plate 1 is changed to forming a recess 5 in the ceramic plate 1 S1A.

[0134] By changing the pulse width of the laser L and, if necessary, the output, the recesses 5 can be formed and the depth of the recesses 5 can also be adjusted. For example, compared to the method for manufacturing a ceramic substrate according to the first embodiment, the output of the laser L can be lowered and the irradiation time of the laser L can be shortened.

[0135] <<First Modification of Second Embodiment>> The first variant of the method for manufacturing a ceramic substrate according to the second embodiment differs from the method for manufacturing a ceramic substrate according to the second embodiment in that, in step S1A of forming a recess 5 in the ceramic plate 1, a laser L is irradiated so that the opening diameter of the recess 5 on the first surface 1a of the ceramic plate 1 is larger than the bottom diameter of the recess 5.

[0136] The cross-sectional shape of the recess 5 can be adjusted to a desired shape by changing the pulse width of the laser L and, if necessary, the output. For example, this can be achieved by lowering the output of the laser L and shortening the irradiation time of the laser L, as compared to the method for manufacturing a ceramic substrate according to the second embodiment.

[0137] <<Second Modification of First or Second Embodiment>> The second variant of the method for manufacturing a ceramic substrate according to the first embodiment or the method for manufacturing a ceramic substrate according to the second embodiment differs from the method for manufacturing a ceramic substrate according to the first embodiment or the method for manufacturing a ceramic substrate according to the second embodiment in that the conductive paste 30 further contains at least one type of powder 31 selected from the group consisting of copper powder, silver powder, powder of a silver-copper alloy, and ceramic powder.

[0138] The content of at least one type of powder 31 selected from the group consisting of copper powder, silver powder, silver-copper alloy powder, and ceramic powder in the conductive paste 30 is not particularly limited as long as it does not impair the effects of the present disclosure, but is preferably 5% by mass or more and 20% by mass or less, when the total amount of the eutectic powder 14, the active metal powder 15, the inorganic filler 17, and the powder 31 is 100% by mass.

[0139] Copper powder, silver powder, and silver-copper alloy powder have better conductivity than eutectic powder of silver and copper. Furthermore, copper powder has a melting point of 1,084°C, and silver powder has a melting point of 962°C. Therefore, copper powder is less likely to melt in conductive paste 30 during sintering in step S4 to form the conductive member, and silver powder can remain dispersed as powder in conductive member 2. This can further improve the conductivity of ceramic substrate 100.

[0140] Furthermore, since the ceramic powder also has a high melting point, it is difficult to melt in the conductive paste 30 during sintering in step S4 to form the conductive member, and can remain dispersed as powder in the conductive member 2. This reduces the difference in linear expansion coefficient between the ceramic plate 1 and the conductive member 2, further improving the reliability of the ceramic substrate 100.

[0141] [Light-emitting device] The light emitting device 200 according to the embodiment includes the ceramic substrate 100 according to the embodiment, and a light emitting element 202 having an electrode 205 arranged on the ceramic substrate 100, and the electrode 205 and the conductive member 2 are electrically connected.

[0142] 8 is a schematic cross-sectional view showing an example of a light emitting device 200 according to an embodiment. Each component of the light emitting device 200 will be described below.

[0143] The light emitting device 200 is a device in which light emitting elements 202 are arranged on a ceramic substrate 100 to emit light. The number of light emitting elements 202 may be one or more. When there are more than one light emitting elements 202, there are no particular limitations on their arrangement, and they may be arranged in a line, for example.

[0144] The light emitting device 200 includes, as an example, a light-transmitting member 203 that covers the light extraction surface of the light emitting element 202, a light-reflecting member 204 that covers the side surface of the light emitting element 202 and the first surface 1a of the ceramic plate 1 in the ceramic substrate 100, and a metal bump 206 that electrically connects the light emitting element 202 and the conductive member 2 of the ceramic substrate 100.

[0145] The ceramic substrate 100 can be formed with wiring of various patterns depending on the application, but in the light-emitting device 200 of the embodiment, the light-emitting element 202 has a pair of electrodes 205 on the same side, and is mounted face-down with the surface having the electrodes 205 facing the first surface 1a of the ceramic plate 1 on the ceramic substrate 100.

[0146] In addition, the light emitting device 200 according to the embodiment may be mounted face-up, in which the pair of electrodes 205 of the light emitting element 202 are placed on the side opposite to the surface in contact with the ceramic substrate 100 and connected to the conductive member 2 of the ceramic substrate 100 by wires.

[0147] (light-emitting element 202) The light emitting element 202 has a pair of electrodes 205 , a semiconductor laminate 207 , and an element substrate 208 .

[0148] As an example, the light emitting element 202 includes a semiconductor laminate 207 on the bottom side of an element substrate 208, and has a pair of electrodes 205 on the semiconductor laminate 207 side.

[0149] The semiconductor laminate 207 can have any composition depending on the desired emission wavelength. For example, a nitride semiconductor (In x Al y Ga 1-x-y N, 0≦X, 0≦Y, X+Y≦1) or GaP, or GaAlAs or AlInGaP capable of emitting red light can be used. These may be used alone or in combination of two or more. The size and shape of the light-emitting element 202 can be appropriately selected depending on the purpose of use.

[0150] The element substrate 208 is, for example, a sapphire substrate or a silicon substrate.

[0151] Electrode 205 is connected to conductive member 2 of ceramic substrate 100 by metal bump 206 and bonding member 209. One of electrodes 205 is a p-electrode, and is disposed at a distance from the other n-electrode so as not to cause an electrical short circuit. As an example, electrode 205 is configured so that one p-electrode and one n-electrode are disposed in one location, but it may also be configured so that one of them is disposed in two locations and the other is disposed in one location.

[0152] (Translucent member 203) The light-transmitting member 203 is disposed on the flat surface side of the element substrate 208, which serves as the light extraction surface. The light-transmitting member 203 is made of, for example, a light-transmitting resin material, and an epoxy resin, a silicone resin, or a mixture thereof can be used. The light-transmitting member 203 may contain a phosphor. For example, by including a phosphor that absorbs blue light from the light-emitting element 202 and emits yellow light, white light can be emitted. The light-transmitting member 203 may also contain multiple types of phosphors. For example, by including a phosphor that absorbs blue light from the semiconductor stack 207 and emits green light and a phosphor that emits red light, white light can also be emitted from the light-emitting element 202.

[0153] Examples of such phosphors include yttrium-aluminum-garnet phosphors (e.g., Y3(Al,Ga)5O 12 :Ce), lutetium aluminum garnet phosphors (e.g., Lu3(Al,Ga)5O 12 :Ce), terbium aluminum garnet phosphors (e.g., Tb3(Al,Ga)5O 12 :Ce), β-sialon phosphors (e.g., (Si,Al)3(O,N)4:Eu), α-sialon phosphors (e.g., Mz(Si,Al) 12 (O,N) 16(However, 0 < z ≤ 2, and M is a lanthanide element excluding Li, Mg, Ca, Y, and La and Ce), nitride-based phosphors such as CASN-based phosphors (e.g., CaAlSiN3:Eu) or SCASN-based phosphors (e.g., (Sr,Ca)AlSiN3:Eu), fluoride-based phosphors such as KSF-based phosphors (e.g., K2SiF6:Mn), KSAF-based phosphors (e.g., K2(Si,Al)F6:Mn), or MGF-based phosphors (e.g., 3.5MgO·0.5MgF2·GeO2:Mn), or quantum dot phosphors such as perovskite and chalcopyrite can be used.

[0154] (Metal bump 206) The metal bump 206 is a member that electrically connects the electrode 205 and the conductive member 2. The metal bump 206 may be disposed on either the electrode 205 side or the conductive member 2 side. Also, the shape, size, and number of the metal bumps 206 can all be appropriately set as long as they can be arranged within the range of the electrode 205. Further, the size of the metal bump 206 can be appropriately adjusted according to the size of the semiconductor laminate 207, the required light emission output of the light emitting device, etc., and for example, a size with a diameter of about several tens of μm to several hundreds of μm can be mentioned.

[0155] The metal bump 206 can be formed of, for example, Au, Ag, Cu, Al, Sn, Pt, Zn, Ni, or an alloy thereof. The metal bump 206 can be formed of, for example, a stud bump known in the art. The stud bump can be formed by a stud bump bonder, a wire bonding device, etc. Also, the metal bump 206 may be formed by a method known in the art such as electrolytic plating, electroless plating, vapor deposition, sputtering, etc.

[0156] Here, as an example, the metal bumps 206 are bonded via a bonding member 209. Examples of the bonding member 209 used here include tin-bismuth, tin-copper, tin-silver, and gold-tin solders, eutectic alloys such as alloys mainly composed of Au and Sn, alloys mainly composed of Au and Si, and alloys mainly composed of Au and Ge, paste materials such as silver, gold, and palladium, anisotropic conductive materials such as ACP and ACF, brazing filler metals of low melting point metals, conductive adhesives and conductive composite adhesives that combine these materials, and the like.

[0157] (Light reflecting member 204) The light reflecting member 204 is a member having light reflectivity. The light reflecting member 204 is disposed so as to cover the first surface 1a of the ceramic plate 1 of the ceramic substrate 100 and also to cover the side surface of the light emitting element 202. The light reflecting member 204 is disposed so as to expose the light extraction surface of the light emitting element 202 and to be flush with the light reflecting member 204 of the light emitting element 202. For example, the light reflecting member 204 is also disposed between the lower surface of the light emitting element 202 and the first surface 1a of the ceramic plate 1 of the ceramic substrate 100.

[0158] The light reflecting member 204 preferably has a high reflectance in order to effectively utilize the light from the light emitting element 202. The light reflecting member 204 is preferably white. The reflectance of the light reflecting member 204 is preferably, for example, 90% or more, and more preferably 94% or more, at the wavelength of the light emitted by the light emitting element 202.

[0159] The resin that can be used for the light reflecting member 204 is, for example, a thermoplastic resin such as an acrylic resin, a polycarbonate resin, a cyclic polyolefin resin, a polyethylene terephthalate resin, a polyethylene naphthalate resin, or a polyester resin, or a thermosetting resin such as an epoxy resin or a silicone resin. The light diffusing material that can be used is, for example, a known material such as titanium oxide, silicon oxide, aluminum oxide, zinc oxide, or glass.

[0160] In the light-emitting device 200, one light-emitting element 202 is treated as one unit, and the brightness and on / off control unit is one unit, but the number of light-emitting elements 202 included in one unit may be one or more. For example, one unit may consist of four light-emitting elements 202 in one row and four columns, or two rows and two columns, or nine light-emitting elements 202 in three rows and three columns, and the number of light-emitting elements 202 is not limited.

[0161] <Application examples of light-emitting devices> Fig. 9A is a perspective view showing an application example of the light emitting device according to the embodiment. Fig. 9B is a cross-sectional view showing the cross section IXB-IXB of Fig. 9A. Note that Fig. 9B omits some of the configuration of Fig. 9A.

[0162] The light emitting module 300 may include a plurality of light emitting devices 200 arranged in a row (11 in FIG. 9A), or may include 11 light emitting devices 200 mounted on one ceramic substrate 100. The configuration of the light emitting module 300 will be described.

[0163] The light emitting module 300 has 11 light emitting devices 200 arranged in a row, a light reflecting member 204 on the outer periphery of the light emitting devices 200, a frame body 301 on the outside of the light reflecting member 204, and a module substrate 302 connected to the surface of the ceramic substrate 100 opposite the first surface 1a of the ceramic plate 1.

[0164] The frame body 301 is a member for surrounding the light reflecting member 204 that covers the plurality of light emitting devices 200. The frame body 301 is formed in a rectangular ring shape that is, for example, rectangular in plan view, and is disposed so as to surround the periphery of the light reflecting member 204.

[0165] The frame 301 can be formed using a frame-shaped member made of a metal, alloy, or ceramic. Examples of metals include Fe, Cu, Ni, Al, Ag, Au, Al, Pt, Ti, W, and Pd. Examples of alloys include alloys containing at least one selected from the group consisting of Fe, Cu, Ni, Al, Ag, Au, Al, Pt, Ti, W, and Pd.

[0166] A resin material may also be used for the frame 301. In this case, the metal, alloy, or ceramic member may be embedded in the frame 301 formed of the resin material, or part of the frame 301 may be formed of the resin material and the other part may be formed of the metal, alloy, or ceramic member.

[0167] The module substrate 302 is a member on which the light emitting device 200 is mounted and electrically connects the light emitting device 200 to the outside. The module substrate 302 is formed, for example, in a substantially rectangular shape in a plan view. The module substrate 302 includes a substrate portion 303 and a wiring board portion 304.

[0168] The material of the substrate portion 303 is preferably, for example, an insulating material, and is preferably a material that is not easily transmitted by light emitted from the light emitting element 202 or external light. For example, ceramics such as aluminum oxide, aluminum nitride, and mullite; thermoplastic resins such as polyamide, polyphthalamide, polyphenylene sulfide, and liquid crystal polymer; and resins such as epoxy resin, silicone resin, modified epoxy resin, urethane resin, and phenolic resin. Among these, ceramics with excellent heat dissipation properties are preferably used as the material of the substrate portion 303.

[0169] Moreover, the wiring board portion 304 is formed on the substrate portion 303 at a position facing the conductive member 2 on the surface opposite to the first surface 1a of the ceramic plate 1 in the ceramic substrate 100 of the light emitting device 200. Examples of materials for the wiring board portion 304 include the materials exemplified for use in the conductive member 2.

[0170] The module substrate 302 is bonded to the frame 301 via a conductive adhesive 305, and is disposed so as to bond the conductive member 2 to the wiring board portion 304. As the conductive adhesive 305, for example, eutectic solder, conductive paste, or bumps may be used. In the light emitting device 200, a protective element 306 is disposed on the ceramic substrate 100 in parallel with each light emitting element 202.

[0171] Since the light-emitting module 300 is configured as described above, when it is driven, the following occurs. That is, in the light-emitting module 300, a current is supplied from an external power source to the light-emitting element 202 via the wiring board portion 304, the conductive member 2, and the electrode 205, causing the light-emitting element 202 to emit light. Of the light emitted by the light-emitting element 202, light traveling upward is extracted to the outside of the light-emitting device 200 via the light-transmitting member 203. Light traveling downward is reflected by the ceramic substrate 100 and extracted to the outside of the light-emitting device 200 via the light-transmitting member 203. Light traveling between the light-emitting element 202 and the frame 301 is reflected by the light-reflecting member 204 and the frame 301 and extracted to the outside of the light-emitting device 200 via the light-transmitting member 203. Light traveling between the light-emitting elements 202 is reflected by the light-reflecting member 204 and is extracted to the outside of the light-emitting device 200 via the light-transmitting member 203. In this case, by narrowing the distance between the light-transmitting members 203 (for example, 0.2 mm or less), for example, when the light-emitting module 300 is used as a light source for a vehicle headlight, the configuration of the optical system can be made simple and compact.

[0172] When manufacturing light emitting module 300, light emitting devices 200 are arranged on a sheet member, frame body 301 is placed around them, and in this state, light reflecting member 204 is filled into the space surrounded by frame body 301 and the sheet member, thereby arranging light reflecting member 204. Thereafter, light emitting device 200 supported by frame body 301 and light reflecting member 204 is placed on module substrate 302, on which wiring board portion 304 and conductive adhesive 305 are placed, and conductive member 2 and wiring board portion 304 are electrically connected, thereby manufacturing light emitting module 300.

[0173] [Method for manufacturing a light-emitting device] The manufacturing method of the light emitting device according to the embodiment includes preparing a ceramic substrate 100 manufactured by the manufacturing method of the ceramic substrate 100 according to the embodiment, and arranging a light emitting element 202 having an electrode 205 on the ceramic substrate 100, and electrically connecting the electrode 205 and the conductive member 2.

[0174] 10 is a flowchart illustrating an example of a method for manufacturing a light emitting device according to the embodiment. Note that the method for manufacturing a light emitting device according to the embodiment includes, as an example, arranging a light reflecting member.

[0175] (S11) Preparing a ceramic substrate In preparing the ceramic substrate 100 S11, the ceramic substrate 100 according to the embodiment is prepared.

[0176] The ceramic substrate 100 may have multiple areas for arranging the light-emitting elements 202, and may be sized to be separated into individual light-emitting devices 200 after the light-reflecting member 204 is arranged, or may have dimensions for each light-emitting device 200.

[0177] (S12): Arranging the light-emitting element In disposing the light emitting element S12, a light emitting element 202 having an electrode 205 is disposed on the ceramic substrate 100. In disposing the light emitting element S12, the electrode 205 of the light emitting element 202 is connected to a bonding member 209 disposed on the conductive member 2 using a metal bump 206. Note that the light emitting element 202 is disposed in a state in which the light transmissive member 203 is previously connected to the element substrate 208. When bonding the light transmissive member 203 to the element substrate 208, a light transmissive bonding material is used.

[0178] (S13) Arranging a light reflecting member In arranging the light reflecting member S13, the light reflecting member 204 is arranged so as to cover the first surface 1a of the ceramic plate 1 of the ceramic substrate 100 and also to cover the side surface of the light emitting element 202. The light reflecting member 204 is arranged on the ceramic substrate 100 so as to surround the light emitting element 202 and expose the upper surface of the light-transmitting member 203, which is the light extraction surface of the light emitting element 202. The light reflecting member 204 is arranged so as to be rectangular in plan view.

[0179] In the manufacturing method of the light emitting device according to the embodiment, after the step S13 of arranging the light reflecting member, a singulation operation is performed as necessary. Each unit of the light emitting device 200 is preset based on the number of light emitting elements 202 used. Therefore, when a plurality of light emitting devices 200 are manufactured at once, a singulation operation is performed. When the singulation operation is performed, the light emitting devices 200 are produced by cutting in a lattice pattern. In addition, examples of the cutting method include a method using a disk-shaped rotary blade, an ultrasonic cutter, a laser beam emitting blade, etc. [Example]

[0180] The present invention will be specifically explained below by way of examples, but the present invention is not limited to these examples in any way.

[0181] Example 1 A conductive paste 30 was prepared by mixing 84 parts by mass of silver-copper eutectic powder, 10 parts by mass of titanium hydride powder, 1 part by mass of polyvinyl butyral (PVB) resin, and 5 parts by mass of aluminum nitride powder. Using this conductive paste 30, a ceramic substrate 100 was manufactured by the ceramic substrate manufacturing method according to the embodiment, based on the flowchart shown in FIG. 5 . In step S1 of forming the through holes, a fiber laser (CW: 1 nanosecond, wavelength: 532 nm, output: 1,500 W) was used. In step S4 of forming the conductive members, the ceramic plate 1 with the conductive paste 30 placed in the through holes 3 was sintered at 850°C for 30 minutes.

[0182] After performing the through-hole forming step S1 and the aluminum removing step S2, the ceramic plate 1 was cut in the thickness direction by laser irradiation and observed at 250x magnification with a metallurgical microscope. Figure 11A shows a cross-sectional image of the through-hole 3 after laser L irradiation in the through-hole forming step S1. Precipitated aluminum 11 was observed on the inner surface defining the through-hole 3. Figure 11B shows a cross-sectional image of the through-hole 3 after etching in the aluminum removing step S2. It was confirmed that the precipitated aluminum 11 had been removed and that burrs 12 had appeared on the inner surface 3a defining the through-hole 3.

[0183] The produced ceramic substrate 100 was cut in the thickness direction by laser irradiation. The region including the inner surface 3a defining the through hole 3 in the cut cross section was observed with an SEM at a magnification of 250x. Fig. 12A shows an SEM image of the cross section of the ceramic substrate 100. Fig. 12B shows an X-ray fluorescence spectroscopic image (Ti-Kα) of the cross section of the ceramic substrate 100.

[0184] Furthermore, regions on the first surface 1a of the manufactured ceramic substrate 100, including the inner surfaces 3a that define the through holes 3, were observed using a metallurgical microscope and an SEM, each at a magnification of 250x. Fig. 13A shows an image of the region on the first surface 1a of the ceramic substrate 100, including the inner surfaces 3a that define the through holes 3, observed using a metallurgical microscope. Fig. 13B shows an image of the region on the first surface 1a of the ceramic substrate 100, including the inner surfaces 3a that define the through holes 3, observed using an SEM, in a cross section of the ceramic substrate 100.

[0185] These observation images confirmed the inner surfaces 3a that defined the dendrite-shaped through holes 3, and the nitride coating 4 containing nitrides present within the inner surfaces 3a. The average thickness of the nitride coating 4 was 20 μm, and the opening diameter of the through holes 3 was 100 μm.

[0186] As described above, the present invention has been described based on specific embodiments, but these are presented merely as examples, and the present invention is not limited to the above embodiments. The above embodiments can be embodied in various other forms, and various combinations, omissions, substitutions, additions, modifications, etc. can be made without departing from the spirit of the invention. These embodiments and their modifications are included within the scope and spirit of the invention, and are also included in the inventions and their equivalents set forth in the claims.

[0187] In addition to the above-described embodiments, the following supplementary notes are also disclosed. (Appendix 1) irradiating a ceramic plate containing aluminum nitride with a laser so that aluminum precipitates, the ceramic plate having a first surface and a second surface opposite to the first surface, thereby forming a through hole or a recess in the ceramic plate; removing the aluminum deposited on the inner surface of the through hole or the recess; Placing a conductive paste inside the through hole or the recess; The method for manufacturing a ceramic substrate includes: (Appendix 2) In disposing the conductive paste, the conductive paste is an active metal brazing material; The method for manufacturing the ceramic substrate according to Appendix 1 includes filling the through-hole or the recess with the active metal brazing material, and then sintering the active metal brazing material to form a conductive member. (Appendix 3) This is a method for manufacturing a ceramic substrate described in Appendix 2, wherein, in placing the conductive paste, the conductive paste is placed so as to cover at least a portion of the opening of the through hole or the recess and at least one of the first surface and the second surface of the ceramic plate. (Appendix 4) In the method for manufacturing a ceramic substrate according to Appendix 2 or 3, the active metal brazing material contains a eutectic powder of silver and copper, an active metal, and a solvent. (Appendix 5) The method for producing a ceramic substrate according to Appendix 4, wherein the active metal brazing material further contains at least one powder selected from the group consisting of copper powder, silver powder, powder of a silver-copper alloy, and ceramic powder. (Appendix 6) The method for manufacturing a ceramic substrate according to claim 4 or 5, wherein the content of the active metal in the active metal brazing material is 2% by mass or more and 15% by mass or less. (Appendix 7) The method for manufacturing a ceramic substrate according to any one of Appendix 3 to Appendix 6, wherein forming the conductive member includes polishing or grinding the conductive member so that at least one of the first surface and the second surface of the ceramic plate in the portion covered with the conductive member is exposed. (Appendix 8) The method for manufacturing a ceramic substrate according to any one of Supplementary Note 1 to Supplementary Note 7, further comprising contacting the inner surface of the through hole or the recess with a solvent in removing the aluminum. (Appendix 9) The method for manufacturing a ceramic substrate according to any one of Appendix 1 to Appendix 8, wherein, in forming the through hole or the recess, the opening diameter of the through hole formed in the first surface of the ceramic plate is larger than the opening diameter of the through hole formed in the second surface. (Appendix 10) The method for manufacturing a ceramic substrate according to any one of Appendix 2 to Appendix 9, wherein, in forming the conductive member, an average thickness of the nitride coating formed on the inner surface defining the through hole or the recess is 10 μm or more and 35 μm or less. (Appendix 11) The method for manufacturing a ceramic substrate according to any one of Appendix 1 to Appendix 10, wherein, in forming the through hole or the recess, the ceramic plate is thermally processed by irradiating the laser, and the aluminum is precipitated on the inner surface of the through hole or the recess. (Appendix 12) 12. The method for manufacturing a ceramic substrate according to claim 11, wherein the laser has an oscillation wavelength of 750 nm or more or an output of 500 W or more. (Appendix 13) The method for manufacturing a ceramic substrate according to any one of Supplementary Note 1 to Supplementary Note 12, wherein in forming the through-holes or the recesses, the ceramic plate is a sintered ceramic plate. (Appendix 14) Preparing the ceramic substrate manufactured by the method for manufacturing the ceramic substrate according to any one of Supplementary Note 1 to Supplementary Note 13; and disposing a light-emitting element having an electrode on the ceramic substrate; The method for manufacturing a light emitting device further comprises electrically connecting the electrode and the conductive member. (Appendix 15) a ceramic plate including aluminum nitride, the ceramic plate having a first surface and a second surface opposite to the first surface, and a through-hole connecting the first surface and the second surface or a recessed portion on at least one of the first surface and the second surface; a conductive member formed inside the through hole or the recess; and In the ceramic substrate, the inner surface defining the through hole or the recess has a nitride coating having an average thickness of 10 μm or more and 35 μm or less. (Appendix 16) The conductive member is a ceramic substrate according to appendix 15, which contains a eutectic structure of silver and copper. (Appendix 17) The conductive member is the ceramic substrate according to claim 16, further containing at least one powder selected from the group consisting of copper powder, silver powder, powder of an alloy of silver and copper, and ceramic powder. (Appendix 18) 17. The ceramic substrate according to claim 15, wherein an inner surface defining the through-hole or the recess has a discontinuous nitride coating and does not have a continuous aluminum film. (Appendix 19) 19. The ceramic substrate according to any one of claims 15 to 18, wherein an inner surface defining the through-hole or the recess has a continuous nitride coating. (Appendix 20) The ceramic substrate according to any one of Supplementary Note 15 to Supplementary Note 19; a light-emitting element provided with an electrode and disposed on the ceramic substrate; and The electrode and the conductive member are electrically connected to each other in the light-emitting device. [Explanation of symbols]

[0188] 1. Ceramic plate 1a 1st page 1b 2nd side 2 Conductive material 3 Through holes 3a Inner surface 4. Nitride coating 5 recess 11. Aluminum 12. Bali 14 Eutectic powder 15 Active metal powder 16 Solvents 17 Inorganic filler 18 Metal compounds 18a Filler surface metal compound 18b Wall metal compound 19 metal 20 Irradiation area 21 Peripheral areas 30 Conductive Paste 31 Powder 100 Ceramic substrate 200 Light-emitting device 202 Light-emitting element 203 Translucent material 204 Light reflecting member 205 Electrode 206 Metal Bump 207 Semiconductor laminate 208 Element substrate 209 Joint Materials 300 Light Emitting Module 301 Frame 302 module board 303 Circuit Board 304 Wiring board section 305 Conductive adhesive 306 Protection element

Claims

1. irradiating a ceramic plate containing aluminum nitride with a laser so that aluminum precipitates, the ceramic plate having a first surface and a second surface opposite to the first surface, thereby forming a through hole or a recess in the ceramic plate; removing the aluminum deposited on the inner surface of the through hole or the recess; Placing a conductive paste inside the through hole or the recess; A method for manufacturing a ceramic substrate, comprising:

2. In disposing the conductive paste, the conductive paste is an active metal brazing material; 2. The method for manufacturing a ceramic substrate according to claim 1, further comprising filling the through-hole or the recess with the active brazing material, and then sintering the active brazing material to form a conductive member.

3. 3. The method for manufacturing a ceramic substrate according to claim 2, wherein the conductive paste is arranged so as to cover an opening of the through hole or the recess and at least a portion of at least one of the first surface and the second surface of the ceramic plate.

4. 3. The method for manufacturing a ceramic substrate according to claim 2, wherein the active metal brazing material contains a eutectic powder of silver and copper, an active metal, and a solvent.

5. 5. The method for manufacturing a ceramic substrate according to claim 4, wherein the active metal brazing material further contains at least one powder selected from the group consisting of copper powder, silver powder, powder of an alloy of silver and copper, and ceramic powder.

6. The method for manufacturing a ceramic substrate according to claim 4 , wherein the content of the active metal in the active metal brazing material is 2% by mass or more and 15% by mass or less.

7. 4. The method for manufacturing a ceramic substrate according to claim 3, wherein forming the conductive member includes polishing or grinding the conductive member so that at least one of the first surface and the second surface of the ceramic plate in the portion covered with the conductive member is exposed.

8. The method for manufacturing a ceramic substrate according to claim 1 , further comprising contacting an inner surface of the through hole or the recess with a solvent in removing the aluminum.

9. 2. The method for manufacturing a ceramic substrate according to claim 1, wherein, in forming the through hole or the recess, the opening diameter of the through hole formed on the first surface of the ceramic plate is larger than the opening diameter of the through hole formed on the second surface.

10. 3. The method for manufacturing a ceramic substrate according to claim 2, wherein in forming the conductive member, an average thickness of the nitride coating formed on the inner surface defining the through hole or the recess is 10 μm or more and 35 μm or less.

11. 2. The method for manufacturing a ceramic substrate according to claim 1, wherein, in forming the through holes or the recesses, the ceramic plate is thermally processed by irradiating the laser, and the aluminum is precipitated on the inner surfaces of the through holes or the recesses.

12. The method for manufacturing a ceramic substrate according to claim 11, wherein the laser has an oscillation wavelength of 750 nm or more or an output of 500 W or more.

13. The method for manufacturing a ceramic substrate according to claim 1 , wherein the ceramic plate is a sintered ceramic plate when the through-hole or the recess is formed.

14. Preparing the ceramic substrate manufactured by the method for manufacturing the ceramic substrate according to any one of claims 1 to 13; and disposing a light-emitting element having an electrode on the ceramic substrate; The method for manufacturing a light emitting device further comprises electrically connecting the electrode and the conductive member.

15. a ceramic plate including aluminum nitride, the ceramic plate having a first surface and a second surface opposite to the first surface, the ceramic plate having a through-hole connecting the first surface and the second surface or a recessed portion on at least one of the first surface and the second surface; a conductive member formed inside the through hole or the recess; and A ceramic substrate, wherein an inner surface defining the through hole or the recess has a nitride coating having an average thickness of 10 μm or more and 35 μm or less.

16. The ceramic substrate according to claim 15, wherein the conductive member contains a eutectic structure of silver and copper.

17. 17. The ceramic substrate according to claim 16, wherein the conductive member further contains at least one powder selected from the group consisting of copper powder, silver powder, powder of an alloy of silver and copper, and ceramic powder.

18. 16. The ceramic substrate according to claim 15, wherein an inner surface defining the through-hole or the recess has a discontinuous nitride coating and does not have a continuous aluminum film.

19. The ceramic substrate according to claim 15 , wherein an inner surface defining the through-hole or the recess has a continuous nitride coating.

20. The ceramic substrate according to any one of claims 15 to 19; and a light-emitting element provided with an electrode and disposed on the ceramic substrate; and The electrode and the conductive member are electrically connected to each other.

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