JP2023147620A - Ceramic substrate, bonded body, and semiconductor device using the same - Google Patents

Abstract

To provide a ceramic substrate, a bonded body, and a semiconductor device using the same, with improved yield when forming a notch.SOLUTION: A ceramic substrate 1 having at least one notch 2 and an opening at the end of a notch includes a portion in which the angle of the notch between the notch and a straight line connecting the ends of the opening in the same notch at the angle of the end of the opening exceeds 90 degrees.SELECTED DRAWING: Figure 4

Description

The embodiments described below generally relate to a ceramic substrate, a bonded body, and a semiconductor device using the same.

An insulating circuit board in which an insulating substrate and a circuit section are bonded is used as a board on which a semiconductor element is mounted. Screws are used as a method for fixing insulating circuit boards. As a screwing method, there are a method of providing a screwing part on the board and a method of using a fixing jig. In recent years, attempts have been made to provide screw-fastening portions on substrates in order to stabilize screw-fastening positions and save space. The screwed portion provided on the board is called a notch.

If the opening end of the ceramic substrate is at right angles as described in Patent Document 1 or 2, sufficient positional accuracy cannot be maintained at the screwed part when screwing, and two or more notches or It was found that unless there was a combination of one notch and a through hole, the screwed part would easily come off. On the other hand, if the screw-fastening part has only a through hole, it is not possible to form a circuit part for mounting a semiconductor element on the side closer to the side of the board (on the outer edge side) than the screw-fastening part, so the area of the board can be effectively utilized. I wasn't able to do that. According to the present invention, it is possible to form a cutout portion that can be screwed with high positional accuracy and that can effectively utilize the area of the board.

The present invention is intended to address such problems, and provides a substrate having at least one notch and an opening at an end of the notch, wherein the opening An object of the present invention is to provide a ceramic substrate characterized in that the angle between the opening ends and the notch part is larger than 90 degrees in some places.
Further, the angle of the opening end as described above may be controlled microscopically.

JP2005-56933A International Publication No. 2011/004798

Because the edges of the opening were at right angles, there was a problem that the board could easily come off when screwing. The present invention is intended to deal with such problems, and provides a substrate having an opening at the end of the notch, the ends of the opening being at an angle with each other. An object of the present invention is to provide a ceramic substrate characterized in that the angle between the notch and the notch is larger than 90 degrees.

The ceramic substrate according to the embodiment is a substrate having at least one notch, and an opening at an end of the notch, and the opening end at an angle of the end of the opening. The ceramic substrate is characterized in that the angle between the two parts and the notch part is larger than 90 degrees.

FIG. 2 is a schematic diagram showing an example of the shape of a cutout portion and a through hole provided in a ceramic substrate according to an embodiment. FIG. 2 is a schematic diagram showing an example of a ceramic substrate having a cutout shape according to an embodiment. FIG. 2 is a schematic diagram showing an example of a ceramic substrate having a cutout shape according to an embodiment. FIG. 2 is a schematic diagram showing an example of a ceramic substrate having a cutout shape according to an embodiment. FIG. 2 is a schematic diagram showing an example of a ceramic substrate having a cutout shape according to an embodiment. FIG. 2 is a schematic diagram showing an example of a ceramic substrate having a cutout shape according to an embodiment. FIG. 2 is a schematic diagram showing an example of a ceramic substrate having a cutout shape according to an embodiment. FIG. 2 is a schematic diagram showing an example of a ceramic substrate having a cutout shape according to an embodiment. FIG. 2 is a schematic diagram showing an example of a ceramic substrate having a cutout shape according to an embodiment. FIG. 1 is a schematic diagram showing an example of a semiconductor device according to an embodiment. FIG. 3 is a schematic diagram showing another example of the semiconductor device according to the embodiment. FIG. 2 is a schematic diagram showing an example of a side surface shape of a cutout portion of a ceramic substrate according to an embodiment.

The ceramic substrate according to the present embodiment has at least one notch, and has an opening at the end of the notch, and has a straight line connecting the ends of the opening. The present invention provides a ceramic substrate characterized in that the angle between the notch and the notch is greater than 90 degrees. The angle between the notch and the straight line connecting the ends of the opening is referred to as angle θ ₁ . Angle θ ₁
is shown in Figure 1.

The ceramic substrate according to the present embodiment may have, for example, one notch and one or more through holes, or it may have a plurality of notches, such as two or more. Moreover, when providing a plurality of notches, the shapes of the notches may all be the same or different. Furthermore, the notch portion may be provided at a corner of the ceramic substrate. Further, when the ceramic substrate is rectangular, the location may be provided on the short side or the long side. Further, the shape of the ceramic substrate may be approximately circular, approximately elliptical, or approximately semicircular. Further, a rounded portion or a chamfered portion may be formed at one or more opening ends.
The fact that a rounded part or a chamfered part may be formed at the opening end means that the size thereof is not particularly determined. Therefore, this includes forming a minute chamfer or rounded portion only in the vicinity of the opening end. Further, in the embodiment of the present invention, when a perpendicular line is drawn from the midpoint between the opening ends, there may be a portion where the shape of the cutout portion is not symmetrical with respect to the perpendicular line. Furthermore, the notch formed in this manner may be combined with a through hole or a notch in which the opening is narrower than other parts, or a notch in which the opening is at right angles. good.

FIG. 1 illustrates an example of a combination of a notch and a through hole.
Further, reference numeral 1 is a ceramic substrate, and reference numeral 2 is a notch. Reference numeral 3 is a through hole. P1 is the open end 1. P2 is the open end 2. θ ₁ is the angle between the straight line connecting the ends of the opening and the notch. Fig. 2 shows a notch formed so that the side other than the opening is approximately trapezoidal, and the notch end is an example of the shape of the notch when a substantially trapezoidal notch is provided. be. Further, P3 indicates an end that is not an opening, and symbol θ ₂ is an angle of the end that is not on the opening side.
FIG. 4 illustrates an example in which a substantially semicircular notch is formed. P4 indicates the midpoint between the open ends. Further, P5 is the farthest point of intersection between the perpendicular line drawn from the midpoint between the opening ends and the substrate. Furthermore, P6 is the intersection of a perpendicular line drawn from the midpoint between the opening ends and the notch portion having the opening. Also, L1 is the distance between P4 and P5, and L2 is the distance between P4 and P5.
and P6.
FIG. 5 shows an example of a notch shaped like a combination of a substantially U-shape and a substantially V-shape. θ ₃ is the angle of the internal angle of the substrate at the end of the notch, and θ ₄ is the angle of the boundary between the R or C portion and the opening.
FIG. 6 illustrates a case where the two cutout portions do not have the same shape.
FIG. 7 illustrates an example in which notches are formed at the corners of the substrate. Moreover, a case is shown in which the other notch has a shape similar to that of a through hole.
FIG. 8 illustrates an example in which the opening end of the notch has an R-shaped chamfer.
FIG. 9 shows an example in which the opening end of the notch has a C-shaped chamfer.
FIG. 10 shows an example of a bonded body in which a conductor portion is provided and bonded to a ceramic substrate. 4 is a conductor part, 5 is an active metal bonding layer, and 6 is a bonded body.
FIG. 11 shows a semiconductor device in which a semiconductor element is mounted on the assembly shown in FIG.
7 is a semiconductor element, 8 is a bonding layer (between the semiconductor element and the conductor part), 9 is a plating film, and 10 is a semiconductor device.

FIG. 12 shows an example of the side shape of the notch portion of the ceramic substrate.

Regarding the angle of the end of the opening, a location where the angle between the opening ends of the same notch and the notch is larger than 90 degrees is one notch. It is more preferable that the opening side end portions of the
A more preferable range of the angle θ ₁ is 100 degrees or more and 170 degrees or less, and even more preferably 100 degrees or more and 160 degrees or less. If the angle is too small, such as less than 100 degrees, there is a risk that the effect of increasing the angle of the opening beyond 90 degrees may not be sufficiently achieved. On the other hand, if the angle is larger than 170 degrees, as described above, the end of the notch shape is too sharp and there is a risk that the open end will be damaged when an impact is applied after screwing.
Further, in the case of having a plurality of notches, it is sufficient that the angle θ ₁ at at least one location is larger than 90 degrees. Moreover, it is more preferable that all angles θ ₁ are larger than 90 degrees. Further, a rounded portion or a chamfered portion may be formed at the open end toward the center of the substrate.
In addition, when forming an R part or a chamfer on the center side of the board at the open end as described above, it is necessary to Let the angle of the notch side with the straight line be θ ₁ . In addition, if there is no inflection point, the location closest to the center of the notch is used instead of the inflection point. Further, the size of the R portion and the C portion is not particularly limited, and they may be provided only near the opening end.

It is preferable that the end portion that is not on the opening side has a substantially U-shape, a substantially trapezoidal shape, or a substantially V-shape. Further, when the end portion that is not on the opening side is approximately V-shaped, the angle thereof is preferably 70 degrees or more as the angle on the notch side. This is because if the angle is smaller than 70 degrees, cracks may occur from this end. As described above, it may have a substantially V-shape as long as the angle of the end not on the opening side is 70 degrees or more on the notch side. The angle of the end that is not on the opening side is defined as angle θ ₂ . The angle θ ₂ is the angle between the side surfaces of the cutout portion 2. It is shown in FIG. 3 as an angle θ ₂ . A substantially U-shape is one that has an R section at the end, and a substantially trapezoidal shape is one that has a C section at the end. That is, the cutout portion may have a substantially pentagonal or hexagonal shape.

Further, by providing a chamfered portion at a location other than the opening side, the effect of suppressing the occurrence of cracks at this end portion can be further enhanced. By having this chamfered portion with an R portion or a C portion, the effect of suppressing the occurrence of cracks at this end portion can be further enhanced. Therefore, it is more preferable to have an R section or a C section at a location other than the opening side. This shape is preferably approximately V-shaped (approximately V-shaped angle is 70 degrees or more), approximately trapezoidal, or approximately U-shaped. At this time, the approximately V-shape (approximately V-shaped angle is 70 degrees or more), approximately trapezoidal shape, or approximately U-shape may have any size. Therefore, it may be very small, provided in a small portion of the notch shape, or it may be formed over the entire notch. Further, when the R portion to the C portion have a substantially U-shape, the effect of suppressing the occurrence of cracks can be further enhanced. Therefore, it is more preferable that the R portion to the C portion have a substantially U-shape. Here, the R section refers to the corner of the tip of the cutout section 2 that is rounded off to form a substantially U-shape.
Further, the C portion refers to a portion in which the corner of the tip of the notch portion 2 is cut linearly to form a substantially trapezoidal shape.
Further, when the C portion is provided in this manner, it is more preferable that the angle on the notch side formed from the upper base of the trapezoid is 30 degrees or more.
Further, at this time, it is more preferable that the ratio of the upper base to the lower base of the substantially trapezoidal shape is 0.1 or more. The upper base of the substantially trapezoid is the length of the side of the tip of the notch 2. Also, the bottom of the trapezoid is
This is the length of the opening of the notch 2. Therefore, the length is the straight line connecting the opening ends.
By doing so, it becomes possible to further reduce cracks and chips compared to the occurrence of cracks and chips in the ceramic substrate during screwing when a substantially V-shape is formed.

Even if the angle between the opening ends and the notch (for example, the angle shown as θ ₁ in Figure 1) is less than 90 degrees, the corner of a rectangular or square board On the other hand, when an opening is provided, the opening end of the substrate of the opening may become thin. In such cases, it may be difficult to maintain sufficient strength. Therefore, it is preferable that the substrate has a portion where the internal angle is 100 degrees or more at both ends of the opening.

Further, it is preferable that the side shape is also controlled. Also in the side shape, it is preferable that at least one end portion has an R portion or a C portion. It is more preferable that both ends of at least one surface side (referred to as the front surface) have an R section or a C section. Further, it may be open on both surfaces (front and back surfaces).
Further, the arithmetic mean roughness Ra of this cross section is preferably 1.2 μm or less. Furthermore, it is preferable that the maximum height Rz of this cross section is 2.0 μm or less. Ra and Rz are JIS
B 0601:2013. JIS B 0601:2013 is ISO
4287:1997/AMENDMENT 1:2009 (IDT).

The midpoint of the notch ends is P4, and when a perpendicular line is drawn from P4, the end of the board furthest from P4 on this perpendicular line is P5, and the end of the board farthest from P4 is P5. length P4
The length of the notch (L2) defined by the distance between P6 and P4 is L2/ L1 is 0.1
It is preferable that it is 0.4 or less. The end of the board farthest from P4 is defined as P5, which is the end of the board that ignores the through hole when the through hole is on a perpendicular line drawn from P4 in a combination of a notch and a through hole. This is what is shown.
In addition, if the perpendicular line drawn from the midpoint of the opening end (referred to as opening end 1) and the other opening end (referred to as opening end 21) does not intersect with another notch, this perpendicular line Let the length consisting of the intersection of the substrates be L1. In addition, if a perpendicular line drawn from the midpoint between the opening ends intersects with another notch, the distance between the straight line connecting the opening ends of the other notch and the midpoint between the opening ends is L1. do. Moreover, among the perpendicular lines provided from the straight line connecting the opening ends, the longest one at the intersection with the edge of the notch is defined as L2. At this time, L2/L1 is preferably 0.1 or more and 0.4 or less. More preferably, it is 0.1 or more and 0.35 or less. If this value is larger than 0.4, there is a possibility that the substrate will be easily broken. On the other hand, if it is smaller than 0.05, there is a possibility that the effect of providing the notch portion may not be sufficiently obtained. In other words, L1 corresponds to the length of the substrate when the notch is not located at a corner and there is only one notch. The maximum width of the notch is L3
The ratio of L3 to L4, where L3 is the opening width, is preferably 0.5≦L4/L3<1. In this case, it is assumed that L3 is a width parallel to L4. If L4/L3 is smaller than 0.5, there is a possibility that the open end will be easily covered. On the other hand, if it is 1 or more, the effect of making the angle of the opening larger than 90 degrees cannot be sufficiently obtained, and there is a possibility that the positional accuracy of the screwed portion may deteriorate.

Further, the ceramic substrate preferably contains one or two selected from silicon nitride, aluminum nitride, sialon, alumina, and zirconia as a main component. The main component refers to a component contained in an amount of 50% by mass or more. Furthermore, it is more preferable that the ceramic substrate is one of a silicon nitride substrate, an aluminum nitride substrate, and an algyl substrate. Arsil is a material containing a total of 50% by mass or more of two types, alumina and zirconia.

The thickness of the ceramic substrate is preferably 0.1 mm or more and 1 mm or less. Substrate thickness is 0.1
If it is less than mm, the strength may decrease. If the substrate thickness is thicker than 1 mm, the insulating substrate itself becomes a thermal resistor, which may reduce the heat dissipation performance of the ceramic circuit board.
The three-point bending strength of the silicon nitride substrate is preferably 600 MPa or more. The thermal conductivity of the silicon nitride substrate is preferably 80 W/m·K or more. By increasing the strength of the silicon nitride substrate, the substrate thickness can be reduced. Therefore, the three-point bending strength of the silicon nitride substrate is 60
0 MPa or more, more preferably 700 MPa or more. The thickness of the silicon nitride substrate is 0.40
It can be made as thin as 0.30 mm or less. Further, the three-point bending strength of the aluminum nitride substrate is about 300 to 450 MPa. On the other hand, the thermal conductivity of the aluminum nitride substrate is 160 W/m·K or more. Since the aluminum nitride substrate has low strength, the substrate thickness is preferably 0.60 mm or more.
Although the three-point bending strength of an aluminum oxide substrate is about 300 to 450 MPa, aluminum oxide substrates are inexpensive among ceramic substrates. The three-point bending strength of Algyl board is 5
Although it is high at about 50 MPa, its thermal conductivity is about 30 to 50 W/m·K. The Algyl substrate is a substrate made of a sintered body of a mixture of aluminum oxide and zirconium oxide. Preferably, the ceramic substrate is a nitrogen-containing ceramic substrate. Among the nitrogen-containing ceramic substrates, nitride ceramics are more preferred, and either a silicon nitride substrate or an aluminum nitride substrate is even more preferred.

The thickness of the ceramic substrate is preferably 0.1 mm or more and 1 mm or less. Board thickness is 0.1m
If it is less than m, the strength may be insufficient. Further, if the substrate thickness is greater than 1 mm, the insulating substrate itself becomes a thermal resistor, which may reduce the heat dissipation performance of the insulating circuit board.

Further, the cutout portion of the ceramic substrate described in this application can be suitably used for screwing.

The silicon nitride substrate preferably has a three-point bending strength of 600 MPa or more. The thermal conductivity is preferably 80 W/m·K or more. By increasing the strength of the silicon nitride substrate, the substrate thickness can be reduced. Therefore, the three-point bending strength of the silicon nitride substrate is preferably 600 MPa or more, more preferably 700 MPa or more. The thickness of the silicon nitride substrate can be reduced to 0.40 mm or less, and further to 0.30 mm or less.
The three-point bending strength of an aluminum nitride substrate is about 300 to 450 MPa. On the other hand, the thermal conductivity of the aluminum nitride substrate is 160 W/m·K or more. Since the aluminum nitride substrate has low strength, the substrate thickness is preferably 0.60 mm or more.
Although the three-point bending strength of an aluminum oxide substrate is about 300 to 450 MPa, aluminum oxide substrates are inexpensive. The three-point bending strength of Algyl substrate is high at around 550 MPa,
Thermal conductivity is about 30 to 50 W/m·K. The Algyl substrate is a substrate made of a sintered body of a mixture of aluminum oxide and zirconium oxide.
The conductor portion may be bonded to a ceramic substrate having such a notch, or the notch portion having the shape described above may be formed in a bonded body with the ceramic substrate after the conductor portion is bonded. Further, the conductor portion may be provided on only one side of the ceramic substrate (referred to as the front conductor portion) or may be provided on the back surface (referred to as the back conductor portion) on both sides. Furthermore, the conductor portion may have different compositions for the back conductor portion and the front conductor portion. If the front conductor part and the back conductor part have the same composition, it is possible to provide a joined body that is easy to use, so it is more preferable that the back conductor part and the front conductor part have the same composition.
It is preferable that the conductor part is a copper member or an aluminum member. The copper member is a copper plate, a copper alloy plate, a member produced by imparting a circuit shape to a copper plate, or a member produced by imparting a circuit shape to a copper alloy plate, and is made of copper or a copper alloy. The aluminum member is an aluminum plate, an aluminum alloy plate, a member produced by imparting a circuit shape to an aluminum plate, or a member produced by imparting a circuit shape to an aluminum alloy plate, and is made of aluminum or an aluminum alloy. Hereinafter, a member manufactured by adding a circuit shape to a copper plate will be referred to as a copper circuit. A member manufactured by adding a circuit shape to an aluminum plate is called an aluminum circuit. The conductor portion may be a metallized layer or a conductive thin film other than a copper member or an aluminum member. The metallized layer is formed by firing a metal paste. The thickness of the conductor portion may be 0.3 mm or more, and further 0.6 mm or more. By increasing the thickness of the conductor portion, the heat dissipation of the joined body can be improved. The thickness of the front conductor portion may be the same as or different from the thickness of the back conductor portion. As the conductor part, a copper member is particularly preferable. Preferably, the copper member is made of oxygen-free copper. Oxygen-free copper has a copper purity of 99.96% by mass or more as shown in JIS-H-3100.

The ceramic substrate and the copper member are preferably bonded via a bonding layer containing titanium. In the active metal bonding method, an active metal brazing material containing Ti is used. The active metal brazing material contains silver or copper as a main component, and also contains Ti. The ceramic substrate and the copper member are preferably bonded via a bonding layer containing carbon. By incorporating carbon into the active metal brazing material, a bonding layer containing carbon can be formed. By incorporating carbon into the active metal brazing material, the fluidity of the brazing material can be improved. Thereby, bonding strength can be improved.

The active metal brazing material contains Ag (silver) from 0% by mass to 70% by mass, Cu (copper) from 15% by mass to 85% by mass, and Ti (titanium) or TiH2 (titanium hydride) from 1% by mass or more. The content is preferably 15% by mass or less. Furthermore, Nb or Zr may be used instead of Ti, or Nb or Zr may be added to Ti for the active metal brazing material. However, the active metal brazing material preferably contains 1% by mass or more and 15% by mass or less of Ti (titanium) or TiH2 (titanium hydride).
When both Ti and TiH2 are used, the total thereof is in the range of 1% by mass or more and 15% by mass or less. When both Ag and Cu are used, the Ag content is 20% by mass or more and 70% by mass.
Hereinafter, the content of Cu is preferably 15% by mass or more and 65% by mass or less.
If necessary, one or two of Sn (tin) or In (indium) may be added to the brazing filler metal.
The content may be greater than or equal to 50% by mass. Content of Ti or TiH2 is 1% by mass
The content is preferably 15% by mass or less. In addition, if necessary, C (carbon) may be added to the brazing filler metal.
You may contain 0.1 mass % or more and 2 mass % or less.

The active metal brazing material composition ratio is calculated based on the total of the solid raw materials to be mixed as 100% by mass. This solid raw material is preferably in powder form. For example, when the active metal brazing material is composed of three types of Ag, Cu, and Ti, Ag+Cu+Ti=100% by mass. Ag, Cu, TiH
2. When composing an active metal brazing filler metal with four types of In, Ag+Cu+TiH2+In=100
Mass%. When configuring the active metal brazing filler metal with five types of Ag, Cu, Ti, Sn, and C,
Ag+Cu+Ti+Sn+C=100% by mass.
It is preferable to mix a solvent according to the composition with the powder raw material having the above composition. By mixing a solvent, the brazing filler metal can be made into a paste.

The above-mentioned notch shape may be provided in the bonded body obtained by forming the conductor portion on the ceramic substrate in this manner. Further, the conductor portion may be provided on a ceramic substrate provided with the above-mentioned notch shape. Further, the conductor portion may be bonded to a circuit shape in advance, or may be bonded to a circuit shape after bonding the conductor portion to the ceramic substrate.

It is preferable that the side surface of the copper member described above has an inclined shape. That is, the side surface of the copper member is preferably inclined with respect to the in-plane direction and the thickness direction. The in-plane direction is
This is a direction parallel to the bonding surface of the ceramic substrate with the copper member. The thickness direction is a direction connecting the ceramic substrate and the copper member, and is perpendicular to the in-plane direction.
The thickness of the bonding layer 5 is preferably in the range of 10 μm or more and 60 μm or less. Also,
The insulating circuit board preferably has a shape in which the bonding layer protrudes from the side surface of the copper member.
The part of the bonding layer that protrudes is called a bonding layer protrusion part. The protruding portion of the bonding layer preferably has a ratio of length L to thickness T (L/T) within a range of 0.5 or more and 3.0 or less. The thickness of the protruding portion of the bonding layer is the thickness of the thickest portion of the protruding portion of the bonding layer. The length of the bonding layer protruding portion is the length of the longest portion protruding from the side surface of the copper member. The thickness and length of the protruding portion of the bonding layer are measured from an arbitrary cross section of the ceramic copper circuit board. By providing the copper member with an inclined shape and providing the bonding layer with a protruding portion, the TCT characteristics of the ceramic copper circuit board can be improved.
Further, the bonding layer used for bonding the plating film and the semiconductor element or the conductor part and the semiconductor element may include those using copper, tin, solder paste, or silver paste.
The ceramic substrate is a silicon nitride substrate with a thickness of 0.4 mm or less, and the thickness of the copper member is 0.4 mm or less.
．． It is preferable that it is 6 mm or more. A thin silicon nitride substrate with a thickness of 0.4 mm or less,
It has the effect of lowering the thermal resistance of ceramic substrates. Further, if the copper plate is thicker than 0.6 mm, heat dissipation is improved. Furthermore, if the silicon nitride substrate has a three-point bending strength of 600 MPa or more, the effect can be easily obtained. Therefore, silicon substrates with a thickness of 0.4 mm or less and silicon substrates with a thickness of 0.6 mm are used.
The above thick copper plates may be combined.

Next, the manufacturing method will be explained.

The notch can be formed by any method as long as it can form the notch as described above, such as by using a laser, or by applying pressure to the green sheet to form the recess. Methods include leaving it in place and cutting it out with a scroll saw. Among these, a method of forming using a laser is more preferable. This is because when this method is used, the notch can be formed with high positional accuracy. Further, by using laser processing, when the shape of the notch is viewed from the side of the substrate, it is possible to make the shape such that the front side is open to the center of the substrate. In addition, the lasers used are not particularly limited, but include CO2 laser, YAG laser (fundamental wave, 2nd harmonic, 3rd harmonic, or 4th harmonic), femtosecond laser, picosecond laser, and semiconductor laser. , LD laser, excimer laser, YVO4 laser, and DDL laser. Further, as a method of forming the cutout portion by laser processing, the cutout portion may be formed by one laser irradiation, or may be formed by irradiation multiple times. Further, dust collection or assist gas may be used as necessary. Further, irradiation may be performed from only one side or from both sides. However, when irradiating from both sides, positional accuracy with respect to the first irradiation surface becomes important. Therefore, it is preferable to irradiate from only one side. In order to form such a notch, a continuous groove may be provided or a dot shape may be provided. Further, the output mode of the laser may be pulsed or CW (continuous), or a combination of both may be used. Furthermore, it is preferable that the maximum depth of the groove formed by the laser be controlled with respect to the thickness of the substrate. It is preferable that 0.5<d/t≦1, where t is the thickness of the substrate and d is the maximum depth of the groove. Here, the maximum depth of the groove is indicated by the total value when the laser is irradiated from both the front and back sides. Further, it is more preferable that 0.7≦d/t≦1.0. More preferably, d/t is 1.0. Moreover, it is more preferable that the formed grooves exist on both the front and back surfaces. It is further preferred that the depth of the groove is always 1.0 in ratio to t. In this way, by increasing the groove depth to a certain level or more relative to the substrate thickness and forming the groove, excessive pressure is applied during the separation process to separate the notch side from the substrate in order to form the notch. Since it is not necessary to obtain the shape of the notch through the process, costs can be reduced.
Further, the ceramic substrate may be honed if necessary. If the ceramic substrate is a sintered ceramic substrate, the honing may be performed before or after the notch shape is formed.

Although the timing of forming the notch is not particularly limited, if it is formed when the green sheet is formed, there is a risk that the positional accuracy will be degraded due to the subsequent sintering process. Therefore, it is preferable to perform the process after sintering. Further, the notch portion may be formed after or before the conductor portions are bonded.
Furthermore, by controlling the shape of the notch, it is possible to increase the torque when screwing.

(Example)
(Examples 1 to 7, Comparative Example 1)
Table 1 lists the types and thicknesses of the ceramic substrates used. Further, the silicon nitride substrate used had a thermal conductivity of 90 W/m·K and a three-point bending strength of 700 MPa. The aluminum nitride substrate used had a thermal conductivity of 170 W/m·K and a three-point bending strength of 400 MPa. The alumina (aluminum oxide) substrate used had a thermal conductivity of 25 W/m·K and a strength of 450 MPa. A zirconia (zirconium oxide) substrate with a strength of 25 W/m·K and a strength of 500 MPa was used.
The Algyl substrate used had a substrate of 25 W/m·K and a strength of 550 MPa.

Table 2 shows the shapes of the notches in the Examples and Comparative Examples listed in Table 1.
Here, if 90 degrees or more is written in the angle column of the end of the notch that is not on the opening side, it means that the end was rounded.

In Table 3, 100 ceramic substrates each having four notches were prepared for each example. After screwing was performed on this ceramic substrate, the positional accuracy of the screwed portion was measured. Further, the exclusive area of the notch portion is expressed as a percentage (%) of the increase relative to Example 1. This ratio is based on 400 locations (100 ceramic substrates x 4 locations per ceramic substrate), where the defective rate of positional accuracy of the screwed part and the exclusive area of the notch are taken as 1, which is increased from 1 notch compared to Example 1. Notch part) Measured. This area increase rate is a comparison of the ratio occupied by the shape of a notch for fixing a screw of the same size to a board of the same size.

From Table 3, it can be seen that the ceramic substrates of the examples were able to reduce the occurrence of burrs, chips, and cracks during the formation of notches compared to conventional ceramic substrates with right-angled edges.

Table 4 shows the measured values of the arithmetic surface roughness Ra and maximum surface roughness Rz of the side surface of the notch. The notch side surface refers to the notch in the thickness direction of the substrate. Also, the shape of the notch is
This is the shape of the notch when viewed from above. Further, the opening end is the shape of the side that is not the opening.

As can be seen from Table 2, Table 3, and Table 4, in the case where all the claims were satisfied, no chipping or cracking occurred during screwing. From this, controlling the shape of the cutout portion of the substrate also from the lateral aspect contributes to increasing the yield when screwing.

1... Ceramic substrate 2... Notch 3... Through hole 4... Conductor part 5... Active metal bonding layer 6... Bonded body 7... Semiconductor element 8... Bonding layer (between semiconductor element and conductor part)
9...Plated film 10...Semiconductor device _θ1 ...Angle θ2 of the notch formed between the ends of the opening and the notch ₂ ...Angle θ3 of the end not on the opening side ₃ ...End of the notch Angle θ ₄ of the internal angle of the substrate in...Angle P1 of the boundary between the R part or C part and the opening part...Opening end 1
P2...Opening end 2
P3... End that is not an opening P4... Midpoint between the open ends P5... Farthest point of intersection between the perpendicular line drawn from the midpoint between the open ends and the board P6... Drawn from the midpoint between the open ends the intersection of the perpendicular line and the notch having the opening;

Claims (15)

A substrate having at least one notch and an opening at an end of the notch, wherein the ends of the openings in the same notch are connected to each other at an angle of the end of the opening. A ceramic substrate characterized by having a portion where the angle of the cutout portion formed by the connected straight line and the cutout portion is larger than 90 degrees.
The shape of the end that is not on the opening side is approximately U-shaped, approximately trapezoidal, or approximately V-shaped;
The ceramic substrate according to claim 1, wherein in the substantially V-shape, the angle of the end portion is 70 degrees or more as the angle on the notch side.
The ceramic substrate according to claim 1 or 2, characterized in that the ceramic substrate has an R section or a C section at a location other than the opening side.
Claims 2 to 3, wherein the shape of the end portion that is not on the opening side is approximately U-shaped.
Ceramic substrate according to any one or more of
The ceramic substrate according to any one of claims 1 to 4, wherein the substrate has a portion where an internal angle of 100 degrees or more is formed at both ends of the opening. Any one or more of claims 1 to 5, characterized in that there is no boundary between the opening and the portion having the end that is not on the opening side, or the angle on the substrate side at the boundary is 100 degrees or more. Ceramic substrate described in
The ceramic substrate according to any one of claims 1 to 6, wherein the arithmetic surface roughness Ra of the notch is 1.2 μm or less when viewed from a side surface of the notch.
8. The ceramic substrate according to claim 1, wherein the maximum surface roughness Rz of the side surface of the notch is 2.0 μm or less.
The ceramic substrate according to any one of claims 1 to 6, wherein the side surface shape of the notch portion has an open portion on at least one surface side.
The midpoint of the notch ends is P4, and when a perpendicular line is drawn from P4, the end of the board furthest from P4 on this perpendicular line is P5, and the length of the board is Sawo P4
The length of the notch (L2) defined by the distance between P6 and P4 is L2/ L1 is 0.1
10. The ceramic substrate according to claim 1, wherein the ceramic substrate is 0.4 or more.
11. The ceramic substrate according to claim 1, wherein the ceramic is a nitrogen-containing ceramic.
A bonded body comprising a ceramic substrate according to any one of claims 1 to 11 and a conductor portion bonded to the ceramic substrate.
The joined body according to claim 12, wherein the conductor portion is a copper member or an aluminum member.
Any one or more of claims 12 to 13, characterized in that a brazing material containing at least one of copper or silver and containing an active metal is used to bond the conductor portion and the ceramic substrate. The zygote described in.
A semiconductor device, characterized in that a semiconductor element is mounted in the bonded body according to any one or more of claims 12 to 14.

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