Laminate structure for manufacturing silicon nitride substrate, method of manufacturing silicon nitride substrate with reduced warpage and silicon nitride substrate manufactured thereby

Abstract

A laminated structure for manufacturing a silicon nitride substrate is provided, comprising an upper plate, a lower plate, and at least one silicon nitride laminated sheet interposed between the upper plate and the lower plate, wherein the silicon nitride laminated sheet comprises one or a plurality of laminated silicon nitride sheets, and spherical particulate boron nitride is coated on at least one surface of the silicon nitride laminated sheet.

Description

Technology Field

[0001] The present invention relates to a laminated structure for manufacturing a silicon nitride substrate, a method for manufacturing a silicon nitride substrate with suppressed warping, and a silicon nitride substrate manufactured therefrom. Background Technology

[0003] Ceramic materials possessing high electrical insulation and thermal conductivity can be used as heat transfer media to rapidly transfer heat generated by devices. Ceramic materials are used as substrates for transport devices, substrates for highly integrated electronic circuits, heat dissipation components for laser oscillators, reaction vessel components for semiconductor manufacturing equipment, and precision mechanical parts.

[0004] In particular, ceramic substrates used in high-power devices require high insulation, high dielectric strength, high thermal conductivity, high strength, and low dielectric constant. Ceramic substrates suitable for these requirements include aluminum nitride substrates, alumina substrates, and silicon nitride substrates.

[0005] Silicon nitride (Si3N4) substrates exhibit high strength (500 MPa to 800 MPa), high toughness (5 MPa·m to 8 MPa·m), and excellent compatibility of the coefficient of thermal expansion with silicon (Si). Furthermore, silicon nitride (Si3N4) substrates possess high thermal conductivity (70 W / mK to 170 W / mK). In other words, silicon nitride (Si3N4) substrates are suitable as materials for next-generation high-power devices. The problem to be solved

[0007] The objective of the present invention is to provide a method for manufacturing a silicon nitride substrate with suppressed warping, which can be manufactured such that the deviation in the content ratio of each component according to location is low, warping is suppressed, and the deviation in thermal and mechanical properties is reduced.

[0008] The object of the present invention is to provide a laminated structure for manufacturing a silicon nitride substrate formed during the method of manufacturing the silicon nitride substrate with suppressed bending.

[0009] The objective of the present invention is to provide a silicon nitride substrate manufactured by the method for manufacturing a silicon nitride substrate with suppressed warping, having a low deviation in the ratio of each component content, suppressed warping, and reduced deviation in thermal and mechanical properties.

[0010] The objects of the present invention are not limited to those mentioned above, and other unmentioned objects and advantages of the present invention may be understood from the following description and will be more clearly understood by the embodiments of the present invention. Furthermore, it will be readily apparent that the objects and advantages of the present invention can be realized by the means and combinations thereof set forth in the claims. means of solving the problem

[0012] In one embodiment of the present invention, the invention comprises an upper plate; a lower plate; and at least one silicon nitride laminated sheet interposed between the upper plate and the lower plate, wherein the silicon nitride laminated sheet comprises one or a plurality of laminated silicon nitride sheets.

[0013] A laminated structure for manufacturing a silicon nitride substrate is provided, wherein spherical particulate boron nitride is coated on at least one surface of the silicon nitride laminated sheet.

[0014] The cumulative volume particle size D50 of the particle diameter of the above-mentioned spherical particulate boron nitride may be 10㎛ to 500㎛.

[0015] The silicon nitride sheet may include yttrium oxide (Y2O3), magnesium oxide (MgO), or both.

[0016] A silicon nitride substrate can be manufactured by degreasing and sintering the above-mentioned laminated structure for manufacturing a silicon nitride substrate.

[0017] The silicon nitride substrate manufactured above comprises magnesium (Mg), yttrium (Y), and silicon (Si), and the difference in magnesium content measured at any two points relative to the total content of magnesium (Mg), yttrium (Y), and silicon (Si) in the silicon nitride substrate of 100 mass% may be within 7 mass%.

[0019] In one embodiment of the present invention,

[0020] A step of forming a slurry by mixing silicon nitride powder, a ceramic additive, and a solvent;

[0021] A step of forming a silicon nitride sheet by molding the above slurry;

[0022] A step of forming a silicon nitride laminated sheet from the silicon nitride sheet;

[0023] A step of applying spherical particulate boron nitride on at least one surface of the silicon nitride laminated sheet;

[0024] A step of forming a laminated structure having at least one silicon nitride laminated sheet interposed between an upper plate and a lower plate;

[0025] A step of performing a degreasing process on the above laminated structure; and

[0026] A step of performing a sintering process on the above-mentioned laminated structure;

[0027] A method for manufacturing a silicon nitride substrate with suppressed warping is provided.

[0028] After the above degreasing process and the above sintering process, the silicon nitride substrate can be formed from the silicon nitride laminated sheet.

[0029] The ceramic additive may include yttrium oxide (Y2O3), magnesium oxide (MgO), or both.

[0030] The cumulative volume particle size D50 of the particle diameter of the above-mentioned spherical particulate boron nitride may be 10㎛ to 500㎛.

[0031] The spherical particulate boron nitride can be applied wet or dry on at least one surface of the silicon nitride laminated sheet.

[0032] A boron nitride slurry prepared by mixing the spherical particulate boron nitride with a wet solvent can be applied to at least one surface of the silicon nitride laminated sheet by a spray method.

[0033] The above boron nitride slurry can be applied to one or both sides of the silicon nitride laminated sheet using nitrogen pressure, and then the wet solvent can be removed by hot air drying.

[0034] The spherical particulate boron nitride powder can be applied to at least one surface of the silicon nitride laminated sheet.

[0036] In one embodiment of the present invention, a silicon nitride substrate comprising magnesium (Mg), yttrium (Y), and silicon (Si) is provided, wherein the difference in magnesium content measured at any two points as a relative content to a total content of 100 mass% of magnesium (Mg), yttrium (Y), and silicon (Si) is within 7 mass%.

[0038] In one embodiment of the present invention, a silicon nitride substrate is manufactured according to a method for manufacturing a silicon nitride substrate with suppressed bending, and the diagonal length (L, mm) of the rectangular silicon nitride substrate is scanned by a non-contact 3D measuring instrument, and the difference (ΔZ, mm) between the lowest point and the highest point of one surface of the silicon nitride substrate is measured in the height direction from a sample holder, and the value of the ratio of the measured diagonal length (L) to ΔZ, ΔZ / L (mm / mm), is calculated to be 0.0015 or less. Effects of the invention

[0040] The method for manufacturing the silicon nitride substrate with suppressed warping according to the present invention can manufacture a silicon nitride substrate in which the variation in the content ratio of each component is low depending on the location, warping is suppressed, and the variation in thermal and mechanical properties is reduced.

[0041] In addition to the effects described above, the specific effects of the present invention are described together with the specific details for implementing the invention below. Brief explanation of the drawing

[0043] FIG. 1 is a flowchart illustrating a method for manufacturing a silicon nitride substrate with suppressed warping according to one embodiment of the present invention. FIGS. 2 to 4 are schematic diagrams for explaining step (S10) in FIG. 1. FIG. 5 is a schematic diagram illustrating step (S20) in FIG. 1. FIG. 6 is a schematic diagram illustrating step (S30) in FIG. 1. FIG. 7 is a schematic diagram illustrating step (S40) in FIG. 1. FIG. 8 is a schematic diagram illustrating step (S50) in FIG. 1. FIG. 9 is a schematic diagram illustrating step (S60) in FIG. 1. FIG. 10 is a schematic diagram illustrating step (S70) in FIG. 1. Specific details for implementing the invention

[0044] The aforementioned objectives, features, and advantages are described in detail below with reference to the attached drawings, thereby enabling those skilled in the art to easily implement the technical concept of the present invention. In describing the present invention, detailed descriptions of known technologies related to the present invention are omitted if it is determined that such descriptions would unnecessarily obscure the essence of the invention. Hereinafter, preferred embodiments according to the present invention will be described in detail with reference to the attached drawings. In the drawings, the same reference numerals are used to indicate the same or similar components.

[0045] In the following, the statement that any configuration is placed on the "upper (or lower)" of a component or on the "upper (or lower)" of a component may mean not only that any configuration is placed in contact with the upper (or lower) surface of said component, but also that another configuration may be interposed between said component and any configuration placed on (or below) said component.

[0046] In addition, where it is stated that one component is "connected," "combined," or "connected" to another component, it should be understood that while the components may be directly connected or connected to each other, another component may be "interposed" between each component, or each component may be "connected," "combined," or "connected" through another component.

[0048] In one embodiment of the present invention, a step of forming a slurry by mixing silicon nitride powder, a ceramic additive, and a solvent;

[0049] A step of forming a silicon nitride sheet by molding the above slurry;

[0050] A step of forming a silicon nitride laminated sheet from the silicon nitride sheet;

[0051] A step of applying spherical particulate boron nitride on at least one surface of the silicon nitride laminated sheet;

[0052] A step of forming a laminated structure having at least one silicon nitride laminated sheet coated with boron nitride interposed between an upper plate and a lower plate;

[0053] A step of performing a degreasing process on the above laminated structure; and

[0054] A step of performing a sintering process on the above-mentioned laminated structure;

[0055] A method for manufacturing a silicon nitride substrate with suppressed warping is provided.

[0056] The silicon nitride substrate manufactured by the above method for producing a silicon nitride substrate with suppressed warping is a sintered substrate produced by a sintering process. Typically, the cause of warping in silicon nitride substrates is attributed to the difference in composition between the edge portion and the center portion within the laminated sheet as the sintering process progresses. Additives used to facilitate the liquid-phase sintering of silicon nitride include yttrium oxide and magnesium oxide. These additive components sublimate during sintering, resulting in changes in their content. However, because there is a difference in the diffusion rate of these additive components within the silicon nitride laminated sheet, a deviation in the ratio of additives occurs between the edge portion and the center portion, which causes warping of the silicon nitride substrate.

[0057] A warped substrate poses a problem in that it increases the bonding defect rate during the subsequent post-process of bonding the metal layer, thereby reducing the yield. Therefore, suppressing the warping of silicon nitride substrates is very important in terms of improving yield.

[0058] A silicon nitride substrate manufactured by the above method for manufacturing a silicon nitride substrate with suppressed warping can suppress warping by reducing such deviations.

[0059] Below, each step of the method for manufacturing the silicon nitride substrate with suppressed warping is described in more detail.

[0060] FIG. 1 is a flowchart illustrating a method for manufacturing a silicon nitride substrate with suppressed warping according to an embodiment of the present invention. Referring to FIG. 1, a method for manufacturing a silicon nitride substrate with suppressed warping according to an embodiment of the present invention may include the steps of: mixing silicon nitride powder, a ceramic additive, and a solvent to form a slurry (S10); molding the slurry to form a silicon nitride sheet (S20); forming a silicon nitride laminated sheet from the silicon nitride sheet (S30); applying spherical particulate boron nitride on at least one surface of the silicon nitride laminated sheet (S40); forming a laminated structure with at least one silicon nitride laminated sheet interposed between an upper plate and a lower plate (S50); performing a degreasing process on the laminated structure (S60); and performing a sintering process on the laminated structure (S70).

[0061] The ceramic additive (SA) may include yttrium oxide (Y2O3), magnesium oxide (MgO), or both. The ceramic additive (SA) may be added to the slurry in powder form.

[0062] In one embodiment, the ceramic additive (SA) may include magnesium oxide (MgO).

[0063] In one embodiment, the ceramic additive (SA) may further include an additional oxide (e.g., zirconium oxide).

[0064] The mass ratio of yttrium oxide (Y2O3) to the ceramic additive (SA) may be 0.3 to 0.5. The mass ratio of magnesium oxide (MgO) to the ceramic additive (SA) may be 0.5 to 0.7.

[0065] FIG. 2 is a schematic diagram illustrating the step (S10) of forming a slurry by mixing silicon nitride powder, a ceramic additive, and a solvent in FIG. 1.

[0066] Referring to FIGS. 1 and 2, a solvent (SV) and a plurality of balls (BA) may be provided within a container (CON). The solvent (SV) is an organic solvent and may include, for example, isopropyl alcohol and toluene. Isopropyl alcohol and toluene may be mixed in a volume ratio of 4:6. The balls (BA) may include silicon nitride.

[0067] A first mixture (MI1) can be prepared by adding silicon nitride (Si3N4) powder (SNP), a ceramic additive (SA), and optionally, a dispersant (DIS) to the solvent (SV) of the container (CON). The dispersant (DIS) can be a commercially available dispersant (DIS), for example, BYK-111, a type of ester-based block copolymer manufactured by BYK Chemie, Germany.

[0068] The solvent (SV) may have 40 Vol% to 60 Vol% of the total volume of the first mixture (MI1). The silicon nitride powder (SNP) may have 15 Vol% to 25 Vol% of the total volume of the first mixture (MI1). The ceramic additive (SA) may have 5 wt% to 10 wt% of the mass of the first mixture (MI1). More specifically, the ceramic additive (SA) may have 5 wt% to 7 wt% of the mass of the first mixture (MI1). By including the ceramic additive (SA) within the above content range, the silicon nitride substrate may have physical properties (e.g., thermal conductivity) at a predetermined level, and the purity of the silicon nitride substrate may also be at a predetermined level.

[0069] For the first mixture (MI1), the first mixture (MI1) can be uniformly mixed by a method such as a ball milling process or basket milling, for example. Silicon nitride balls may be used in the ball milling process or basket milling. The balls can physically help the first mixture (MI1) to be uniformly mixed.

[0070] Specifically, the ball milling process may include rotating a container holding the first mixture (MI1) at a constant speed using a ball milling machine. As the container rotates, mechanical grinding and uniform mixing may be performed by balls inside the container. The rotational speed of the ball milling machine may be 100 rpm to 500 rpm.

[0071] Referring to FIGS. 1 and 3, a second mixture (MI2) can be prepared by adding a binder (BI) and a plasticizer (PL) to a first mixture (MI1) after a ball milling process. The binder (BI) may include at least one of cellulose derivatives such as ethyl cellulose, methyl cellulose, nitrocellulose, and carboxycellulose, resins such as polyvinyl alcohol, acrylic acid esters, methacrylic acid esters, and polyvinyl butyral, and mixtures of said derivatives and said resins. For example, the binder (BI) may include polyvinyl butyral (PVB). The plasticizer (PL) may include dibutyl phthalate or dioctyl phthalate. The mass of the added plasticizer (PL) may be about 50% of the mass of the added binder (BI). Additionally, a solvent may be added to the first mixture (MI1).

[0072] For the second mixture (MI2), the second mixture (MI2) can be uniformly mixed by a method such as ball milling or basket milling, for example. By uniformly mixing the second mixture (MI2) through the ball milling process, a slurry (SL) can be formed (S120). The ball milling process may be substantially the same or similar to the ball milling process described above. The balls can then be removed.

[0073] Referring to FIGS. 1 and 4, volatile gases can be removed from the slurry (SL) by aging the slurry (SL) formed by a ball milling process. During the aging of the slurry (SL), the slurry (SL) can be stirred using a stirrer (SIT). Aging can be performed for approximately 24 hours.

[0074] FIG. 5 is a schematic diagram illustrating the step (S20) of forming a silicon nitride sheet by molding the slurry in FIG. 1.

[0075] Referring to FIGS. 1 and 5, a silicon nitride sheet (SH) can be formed by molding the slurry (SL) prepared in step (S10) using a tape casting process (S130). Specifically, the tape casting process may involve pouring the slurry (SL) onto a blade set to a certain dam height and applying the slurry (SL) onto a moving substrate film. A silicon nitride sheet (SH) molded body can be obtained by evaporating the solvent from the slurry (SL) applied onto the substrate film and peeling it off. The substrate film may be a stainless steel tape, oil paper tape, or a polymer tape such as polyester. For example, the slurry (SL) may be poured onto a doctor blade set to a dam height of about 0.3 mm and applied onto a substrate film moving at a predetermined speed (e.g., 0.1 m / min to 1 m / min). Subsequently, a silicon nitride sheet (SH) can be obtained by performing a drying process and a process to remove the substrate film.

[0076] The tape casting process can be performed at 30°C to 80°C. The silicon nitride sheet (SH) formed by the tape casting process can be cut to an appropriate size. The thickness of the silicon nitride sheet (SH) can be 0.1 mm to 0.5 mm.

[0077] The silicon nitride sheet (SH) may have a size of M × N. Each of the above M and N may be 60 mm to 300 mm, but is not particularly limited. That is, M and N may each be changed depending on the size of the desired silicon nitride substrate.

[0078] FIG. 6 is a schematic diagram illustrating the step (S30) of forming a silicon nitride laminated sheet from the silicon nitride sheet in FIG. 1. A silicon nitride laminated sheet may be formed by laminating a plurality of silicon nitride sheets. Although it is possible for the silicon nitride laminated sheet to be formed from a single silicon nitride sheet, for convenience, it is collectively referred to as a 'laminated' sheet. Hereinafter, a process for forming a silicon nitride laminated sheet by laminating a plurality of silicon nitride sheets is described by example.

[0079] Referring to FIGS. 1 and FIGS. 6, a plurality of silicon nitride sheets (SH) prepared in step (S20) can be laminated. A lamination process can be performed on the laminated silicon nitride sheets (SH) to form a silicon nitride laminated sheet (SSH) (S30). For example, one to three silicon nitride sheets (SH) can be laminated to form a silicon nitride laminated sheet (SSH). The lamination process can be performed at a pressure of about 10 MPa and a temperature of about 60°C.

[0080] The silicon nitride laminated sheet (SSH) can be pressed. The pressing process may utilize a warm isostatic press (WIP). The pressing process may be performed at a pressure of about 30 MPa and a temperature of about 70°C. Finally, the thickness (TH) of the silicon nitride laminated sheet (SSH) may be 0.3 mm to 4 mm.

[0081] The silicon nitride laminated sheet (SSH) may be a superposition of sheets (SH), and the size of the silicon nitride laminated sheet (SSH) may also be substantially the same as the size of the sheet (SH). In other words, the silicon nitride laminated sheet (SSH) may have a size of M × N. Each of the above M and N may be 60 mm to 300 mm.

[0082] FIG. 7 is a schematic diagram illustrating the step (S40) of applying spherical particulate boron nitride on at least one surface of the silicon nitride laminated sheet in FIG. 1.

[0083] FIG. 7 illustrates a silicon nitride laminated sheet (SSH) obtained in step (S30) having spherical particulate boron nitride coated on one or both sides of the silicon nitride laminated sheet (SSH), where BNP represents the coated spherical particulate boron nitride.

[0084] In order to recover silicon nitride substrates manufactured from each silicon nitride laminated sheet (SSH) after sintering, a plurality of silicon nitride laminated sheets (SSH) are stacked and sintered in a crucible (see S70), and before performing a degreasing process, boron nitride powder can be applied dry or wet as a release agent to one or both sides of the silicon nitride laminated sheets (SSH).

[0085] In one embodiment, a boron nitride slurry is prepared by mixing the spherical particulate boron nitride with a wet solvent and can be applied by a spray method. The wet solvent of the boron nitride slurry may be acetone or water. Specifically, the boron nitride slurry can be prepared by dispersing 10 to 20 mass% of boron nitride in acetone. The boron nitride slurry can be dispersed and used in a ball mill, bead mill, or basket mill. The boron nitride slurry can be applied to one or both sides of a silicon nitride laminated sheet (SSH) using nitrogen pressure.

[0086] After coating, the wet solvent of the boron nitride slurry is removed. To do this, hot air drying can be performed at 70 to 90°C.

[0087] In one embodiment, the spherical particulate boron nitride can be applied dry in a powder state.

[0088] As the above-mentioned spherical particulate boron nitride is positioned between the silicon nitride laminated sheets (SSH), fine spaces are created between the silicon nitride laminated sheets (SSH). As the sublimation rate of the ceramic additive in the center of the silicon nitride laminated sheet (SSH) becomes similar to that in the edge portion, the difference in composition ratio within the silicon nitride laminated sheet (SSH) due to sintering is reduced. As a result, as the ratio of the ceramic additive within the silicon nitride substrate obtained by sintering becomes relatively uniform, the variation in physical properties according to location within the substrate is reduced, and warping of the silicon nitride substrate can be suppressed.

[0089] In one embodiment, the cumulative volume particle size D50 of the particle diameter of the spherical particulate boron nitride may be 10 μm to 500 μm, specifically 10 μm to 300 μm, and more specifically 10 μm to 35 μm. By using the spherical particulate boron nitride with the aforementioned particle size, the ratio of ceramic additives within the silicon nitride laminated sheet (SSH) resulting from sintering can be made uniform, thereby helping to manufacture a silicon nitride substrate with suppressed warping.

[0090] The above "cumulative volume particle size D50 of particle diameter" can be defined as the particle size corresponding to 50% of the cumulative volume, and can be measured, for example, using the laser diffraction method.

[0091] The "spherical particle" above is a particle having an aspect ratio of the shortest axis length to the longest axis length greater than 0.5. The lengths of the shortest axis and the longest axis refer to the lengths connecting two points where an axis, which is a straight line passing through the center point of the particle, meets the surface of the particle. The center point of the particle may be the geometric center of volume. In the case of a perfect sphere, the aspect ratio may be 1, but irregular shapes of the kind that naturally occur during the formation of the particle are not considered significantly in the context of the present invention, and the spherical particle is defined by the aspect ratio.

[0092] In one embodiment, the aspect ratio of the spherical particulate boron nitride may be 0.6 or higher, 0.7 or higher, 0.8 or higher, or 0.9 or higher.

[0093] FIG. 8 is a schematic diagram illustrating the step (S50) of forming a laminated structure in which at least one silicon nitride laminated sheet coated with boron nitride is interposed between the upper plate and the lower plate of FIG. 1.

[0094] Referring to FIGS. 1 and FIGS. 8, a laminated structure (SS) can be prepared. The laminated structure (SS) may include a lower plate (PLT1), an upper plate (PLT2), and a silicon nitride laminated sheet (SSH) coated with boron nitride interposed between them. Preparing the silicon nitride laminated structure (SS) may include interposing the silicon nitride laminated sheet (SSH) prepared in step (S40) between the lower plate (PLT1) and the upper plate (PLT2) (S150). If the boron nitride is wet-coated, the wet solvent of the boron nitride slurry is sufficiently removed by hot-air drying, and then a plurality of silicon nitride laminated sheets (SSH) are stacked and placed between the lower plate (PLT1) and the upper plate (PLT2).

[0095] The upper plate (PLT1) and the lower plate (PLT2) may contain boron nitride. For example, the upper plate (PLT1) and the lower plate (PLT2) may be boron nitride plates.

[0096] FIG. 8 illustrates a silicon nitride laminated sheet (SSH) interposed between a lower plate (PLT1) and an upper plate (PLT2), but the present invention is not limited thereto. In one embodiment, two or more laminated sheets (SSH) may be interposed between a lower plate (PLT1) and an upper plate (PLT2).

[0097] FIG. 9 is a schematic diagram illustrating the step (S60) of performing a degreasing process on the laminated structure of FIG. 1.

[0098] Referring to FIGS. 1 and 9, a degreasing process (Binder Burn Out, BBO) can be performed on the laminated structure (SS) prepared in step (S50) (S60). This allows all organic materials, such as binders, dispersants, and plasticizers within the silicon nitride laminated sheet (SSH), to be incinerated and removed. In one embodiment, the degreasing process can be performed at a predetermined temperature under atmospheric pressure for about 30 to 100 hours. For example, the degreasing process can be performed in an atmospheric furnace (AF) at a temperature of about 600°C for about 30 hours. That is, the degreasing process can be performed under atmosphere (air).

[0099] FIG. 10 is a schematic diagram illustrating the step (S70) of performing a sintering process on the laminated structure of FIG. 1.

[0100] Referring to FIG. 1 and FIG. 10, after step (S60), a laminated structure (SS) may be provided inside a crucible (CRU). Bedding powder (NP) may be placed inside the crucible (CRU) so that the laminated structure (SS) can be embedded within the bedding powder (NP). The bedding powder (NP) may include boron nitride powder, silicon nitride powder, or a mixture thereof. If the bedding powder (NP) includes a mixture of boron nitride powder and silicon nitride powder, the boron nitride powder and silicon nitride powder may be mixed in a 1:1 ratio. In one embodiment, as shown in FIG. 10, the crucible (CRU) may be in a stacked multi-layer structure, and a separate laminated structure (SS) may be provided for each layer inside each crucible (CRU).

[0101] A crucible (CRU) can be heated to perform a sintering process on the laminated structure (SS) (S70). This allows the silicon nitride laminated sheet (SSH) to be sintered, thereby forming a silicon nitride substrate.

[0102] In one embodiment, the sintering process may be performed at a temperature of 1700°C to 2000°C for 6 to 12 hours. For example, the sintering process may be performed at a temperature of about 1900°C for about 6 hours. The sintering process may be performed in a nitrogen atmosphere. A silicon nitride laminated sheet (SSH) after sintering can be obtained as a silicon nitride substrate.

[0103] The silicon nitride substrate may have MXN sizes, where M and N each may be 40 mm to 200 mm. In one embodiment of the present invention, the size of the silicon nitride substrate may be reduced to a size smaller than that of the silicon nitride laminated sheet (SSH) by a sintering process.

[0105] In one embodiment of the present invention,

[0106] Upper plate;

[0107] lower plate; and

[0108] at least one silicon nitride laminated sheet interposed between the upper plate and the lower plate; comprising

[0109] The silicon nitride laminated sheet comprises one or a plurality of laminated silicon nitride sheets, and

[0110] Spherical particulate boron nitride is coated on at least one surface of the silicon nitride laminated sheet.

[0111] A laminated structure for manufacturing silicon nitride substrates is provided.

[0112] The above-described laminated structure for manufacturing a silicon nitride substrate may be a laminated structure for manufacturing a silicon nitride substrate manufactured in step (S50) of the method for manufacturing a silicon nitride substrate with suppressed warping described above.

[0113] Accordingly, the detailed description of the laminated structure for manufacturing the silicon nitride substrate is as described in the method for manufacturing the silicon nitride substrate with suppressed warping.

[0114] The cumulative volume particle size D50 of the particle diameter of the above-mentioned spherical particulate boron nitride may be 10㎛ to 500㎛.

[0115] In the method for manufacturing a silicon nitride substrate with suppressed warping described above, since the ceramic additive (SA) may include magnesium oxide (MgO), the silicon nitride sheet may include magnesium oxide (MgO). As described above, in addition to magnesium oxide (MgO), the silicon nitride sheet may further include components included in the ceramic additive (SA).

[0116] A silicon nitride substrate can be manufactured by degreasing and sintering the above-mentioned laminated structure for manufacturing a silicon nitride substrate.

[0117] As the above-described laminated structure for manufacturing a silicon nitride substrate is manufactured according to the method for manufacturing a silicon nitride substrate with suppressed warping, the silicon nitride substrate manufactured by degreasing and sintering the above-described laminated structure for manufacturing a silicon nitride substrate has a low variation in the content ratio of each component depending on the location, for example, a low variation in the content ratio of the magnesium component, and warping is suppressed, and accordingly, the variation in thermal and mechanical properties is reduced.

[0118] In one embodiment, the difference in magnesium content measured at any two points on the manufactured silicon nitride substrate may be within 7 mass%, specifically within 5 mass%, more specifically within 3 mass%.

[0119] In one embodiment of the present invention, a silicon nitride substrate comprising magnesium (Mg), yttrium (Y), and silicon (Si) is provided, wherein the difference in magnesium content measured at any two points as a relative content to a total content of 100 mass% of magnesium (Mg), yttrium (Y), and silicon (Si) is within 7 mass%. The silicon nitride substrate may be manufactured by the method for manufacturing a silicon nitride substrate with suppressed warping as described above.

[0120] In one embodiment of the present invention, a silicon nitride substrate is provided, manufactured according to the method for manufacturing a silicon nitride substrate with suppressed warping, wherein the diagonal length (L, mm) of the rectangular silicon nitride substrate is scanned by a non-contact 3D measuring instrument, and the difference (ΔZ, mm) between the lowest point and the highest point of one surface of the silicon nitride substrate is measured in the height direction from a sample holder, and the value of the ratio of the measured diagonal length (L) to ΔZ, ΔZ / L (mm / mm), is calculated to be 0.0015 or less. The silicon nitride substrate may be manufactured by the method for manufacturing a silicon nitride substrate with suppressed warping described above.

[0122] Examples and comparative examples of the present invention are described below. The following examples are merely embodiments of the present invention, and the present invention is not limited to the following examples.

[0124] (Example)

[0125] Example 1

[0126] A silicon nitride substrate was manufactured using the manufacturing method described in FIGS. 1 to 10. The cumulative volume particle size D50 of the particle diameter of the spherical particulate boron nitride used was 15 μm, and a boron nitride slurry was prepared by mixing boron nitride powder with a wet solvent and applied to both sides of a silicon nitride laminated sheet (SSH) by spraying. After application, hot air drying was performed at 80°C to remove the wet solvent from the boron nitride slurry.

[0128] Example 2

[0129] A silicon nitride substrate was prepared in the same manner as in Example 1, except that the cumulative volume particle size D50 of the particle diameter of the spherical particulate boron nitride used was 30 μm.

[0131] Comparative Example 1

[0132] A silicon nitride substrate was prepared in the same manner as in Example 1, except that plate-shaped boron nitride (cumulative volume particle size D50 of particle diameter is 7 μm) was used instead of the spherical-shaped boron nitride used in Example 1.

[0134] (Experimental Example)

[0135] Bending measurement

[0136] The warping was measured non-contactually. A square silicon nitride substrate (140 mm × 190 mm × 0.32 mm) was scanned diagonally using a non-contact 3D measuring instrument. The warping value was defined as the ratio △Z / L (mm / mm), which is the difference between the lowest and highest points (△Z, mm) of one side of the silicon nitride substrate in the height direction from the sample holder, and the scanned diagonal length (L, mm).

[0138] Magnesium content measurement

[0139] Magnesium content was measured using XRF (Rigaku AZX400). A 140x190mm sample was loaded into the instrument and the entire substrate was mapped. Magnesium (mg), yttrium (y), and silicon (Si) were selected as the mapping elements and measured so that all three elements satisfied 100%, allowing for semi-quantitative measurement.

[0140] For each measurement, the measurement range was set to Φ10mm, and the entire substrate was mapped sequentially to measure the elemental content (mass%) of each region. In this measurement, 109 measurement points were set and the measurement was performed.

[0141] The measured values ​​were calculated by determining the ratio for each section based on the center of the silicon nitride substrate.

[0143] The evaluation results of Examples 1-2 and Comparative Example 1 are listed in Table 1.

[0144] Bending (mm / mm) Magnesium content ratio Magnesium Content (wt%) @ Center Minimum magnesium ratio for each part Maximum magnesium ratio for each part Example 1 0.0010 ±3% 1.44 0.97 1.02 Example 2 0.0015 ±5% 1.46 0.95 1.03 Comparative Example 1 0.0023 ±9% 1.51 0.91 1.07

[0145] Compared to Examples 1-2, Comparative Example 1 exhibited greater warping and a larger variation in magnesium content. Since the fine space that can be generated by spherical particulate boron nitride is reduced when plate-shaped particulate boron nitride is used, the effect of similar sublimation rates of ceramic additives within the silicon nitride laminated sheet (SSH) is also reduced. Accordingly, an inferior effect can be observed in Comparative Example 1 compared to Examples 1-2.

[0147] Although the present invention has been described above with reference to embodiments, the present invention is not limited by the embodiments disclosed in this specification, and it is obvious that various modifications can be made by a person skilled in the art within the scope of the technical concept of the present invention. Furthermore, even if the effects of the configuration of the present invention were not explicitly described while describing the embodiments of the present invention above, it is natural to acknowledge that the effects predictable by said configuration should also be recognized.

Claims

Claim 1 A silicon nitride substrate obtained by sintering a laminated structure for manufacturing a silicon nitride substrate, wherein the laminated structure for manufacturing a silicon nitride substrate comprises: an upper plate; a lower plate; and at least one silicon nitride laminated sheet interposed between the upper plate and the lower plate; wherein the silicon nitride laminated sheet comprises one or a plurality of laminated silicon nitride sheets, and spherical particulate boron nitride is applied on at least one surface of the silicon nitride laminated sheet, and the diagonal length (L, mm) of the square silicon nitride substrate is scanned by a non-contact 3D measuring instrument, and the difference (ΔZ, mm) between the lowest point and the highest point of one surface of the silicon nitride substrate is measured in the height direction from a sample holder, and the calculated value of the ratio of the measured diagonal length (L) to ΔZ, ΔZ / L (mm / mm), is 0.0015 or less. Claim 2 In claim 1, the silicon phosphate substrate has a cumulative volume particle size D50 of the particle diameter of the spherical particulate boron nitride ranging from 10㎛ to 500㎛. Claim 3 In claim 1, the silicon nitride sheet is a silicon nitride substrate comprising yttrium oxide (Y2O3), magnesium oxide (MgO), or both. Claim 4 In paragraph 3, a silicon nitride substrate is manufactured by degreasing and sintering the laminated structure for manufacturing the silicon nitride substrate. Claim 5 In claim 4, the silicon nitride substrate manufactured comprises magnesium (Mg), yttrium (Y), and silicon (Si), and the difference in magnesium content measured at any two points as a relative content to 100 mass% of the total content of magnesium (Mg), yttrium (Y), and silicon (Si) in the silicon nitride substrate is within 7 mass%. Claim 6 A method for manufacturing a silicon nitride substrate according to claim 1, comprising: a step of mixing silicon nitride powder, a ceramic additive, and a solvent to form a slurry; a step of molding the slurry to form a silicon nitride sheet; a step of forming a silicon nitride laminated sheet from the silicon nitride sheet; a step of applying spherical particulate boron nitride on at least one surface of the silicon nitride laminated sheet; a step of forming a laminated structure in which at least one silicon nitride laminated sheet is interposed between an upper plate and a lower plate; a step of performing a degreasing process on the laminated structure; and a step of performing a sintering process on the laminated structure. Claim 7 A method for manufacturing a silicon nitride substrate according to claim 6, wherein the silicon nitride substrate is formed from the silicon nitride laminated sheet after the degreasing process and the sintering process. Claim 8 A method for manufacturing a silicon nitride substrate according to claim 6, wherein the ceramic additive comprises yttrium oxide (Y2O3), magnesium oxide (MgO), or both. Claim 9 A method for manufacturing a silicon phosphate substrate according to claim 6, wherein the cumulative volume particle size D50 of the particle diameter of the spherical particulate boron nitride is 10㎛ to 500㎛. Claim 10 A method for manufacturing a silicon nitride substrate according to claim 6, wherein the spherical particulate boron nitride is applied wet or dry on at least one surface of the silicon nitride laminated sheet. Claim 11 A method for manufacturing a silicon nitride substrate according to claim 6, wherein a boron nitride slurry is prepared by mixing the spherical particulate boron nitride with a wet solvent and applied by a spray method on at least one surface of the silicon nitride laminated sheet. Claim 12 A method for manufacturing a silicon nitride substrate according to claim 11, wherein the boron nitride slurry is applied to one or both sides of the silicon nitride laminated sheet using nitrogen pressure, and then the wet solvent is removed by hot air drying. Claim 13 A method for manufacturing a silicon nitride substrate according to claim 6, wherein the spherical particulate boron nitride powder is applied on at least one surface of the silicon nitride laminated sheet. Claim 14 A silicon nitride substrate comprising magnesium (Mg), yttrium (Y), and silicon (Si), wherein the difference in magnesium content measured at any two points as a relative content to a total content of 100 mass% of magnesium (Mg), yttrium (Y), and silicon (Si) is within 7 mass%. Claim 15 delete

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