JPH11224923A - Semiconductor stack - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a semiconductor stack, in which a ceramic plate for electrically insulating a semiconductor element and a cooler is protected from damages. SOLUTION: An electrically insulating and thermal conducting ceramic plate 3 between a pressure-welding type semiconductor element 1 and a cooler 2, and a heat conductive metal spacer 7 are provided. A semiconductor element 1, the metal spacer 7, the ceramic plate 3, and the cooler 2 are sequentially stacked and held in a pressed state by the use of pressing means to form a semiconductor stack. The metal spacer 7 has each disk-shaped end with a largest diameter which is larger than the post diameter of a semiconductor element 1. The metal spacer 7 has a circular groove 13 in a central direction on a circumferential part of a curved face thereof. The diameter of the circular groove 13 is as large as the post diameter of the semiconductor element 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in the structure of a semiconductor stack using a press-contact type semiconductor device.

[0002]

2. Description of the Related Art A plan view of a conventional semiconductor stack is shown in FIG.
FIG. 11A is a front view of FIG. The semiconductor stack includes a press-contact type semiconductor element 1 and a cooler 2 for cooling the semiconductor element 1, a ceramic plate 3 for electrically insulating the semiconductor element 1 from the cooler, a conductor 4a for electrically connecting to the outside,
4b, a leaf spring 5 for pressing both surfaces of the semiconductor element 1 toward the cooler 2 with a predetermined pressure,
And an insulating spacer 6 for electrical insulation from the substrate. Both ends of the leaf spring 25 are attached to the threaded portions 9 a of the pair of stud bolts 9 erected on the cooler 2 by the nuts 11.

The ceramic plate 3 is, of course, required to have a high electrical insulation property. In addition, the ceramic plate 3 transmits heat generated from the semiconductor element 1 to the cooler 2 to allow the temperature of the semiconductor element 1 to be increased. It is necessary that the temperature be lower than the temperature. Therefore, aluminum nitride or the like having a high thermal conductivity is used as the material. Often used.

[0004]

However, since ceramics are more easily broken than metals,
Care must be taken so that partial concentrated load and bending load are not applied, and the press-contact portion of the conductor 4b that contacts the ceramic plate 3 is a component that requires precision in any of surface roughness, flatness, and parallelism.

In addition, it is required for the characteristics of the semiconductor element 1 that the pressure contact of the semiconductor element 1 has uniformity over the entire post surface, and the pressure contact surface of the ceramic plate 3 is also pressed uniformly for the above reason. It is desired.

However, since the conductor 4b is required to be insulated from the cooler 2, a bent portion is provided on the way from the press-contact portion of the conductor 4b to the outside of the semiconductor stack, so that the conductor 4b is spaced from the cooler 2. ing. Therefore, the residual stress due to the bending process remains near this bent part,
In order to ensure a uniform stress distribution over the entire area of the press-contact surface, this often becomes an obstacle, and may cause insulation failure due to cracking of the ceramic plate 3.

In addition, the shape of the press-contact portion is not uniform with respect to the press-contact center of the semiconductor stack, so that partial stress concentration is likely to occur, which has been a factor leading to the occurrence of cracks in the ceramic plate 3.

The semiconductor element 1, the conductors 4a and 4b are portions to which a voltage is applied, and it is necessary to insulate the cooler 2 and the leaf spring 5 from each other. The leaf spring 5 and the conductor 4a are insulated by the insulating spacer 6, and the cooler 2 and the conductor 4b are insulated by the ceramic plate 3. However, the creepage distance L between the end face of the conductor 4b and the cooler 2 is required for insulation. Only the dimensions need to be secured. Therefore, the outer diameter (diameter) of the ceramic plate 3 is larger than the post diameter of the semiconductor element 1 (a portion having a potential, which is indicated by a dimension D in FIG. 10A).

For this reason, the distance L1 between the two points, which is the portion of the leaf spring 5 supported by the stud bolts 9 which is naturally located outside the ceramic plate 3, becomes large. As L1 increases, the thickness of the spring 5 needs to be increased to increase the section modulus.

Also, since the bending moment applied to the surface of the cooler 2 in contact with the ceramic plate 3 increases as L1 increases, the bending moment of the cooler 2 is adjusted so that a load in the bending direction is not generated on the ceramic plate 3. In order to suppress the resulting deflection, it is necessary to increase the rigidity of the cooler 2 by increasing the thickness of the base portion of the cooler 2 or the like.

Further, since the L1 dimension must be large, it is disadvantageous in terms of miniaturization of the entire semiconductor stack. (Object) It is an object of the present invention to solve the above-described problem of cracking of the ceramic plate of the conventional semiconductor stack and to realize a highly reliable semiconductor stack.

[0012]

According to a first aspect of the present invention, a ceramic plate having electrical insulation and thermal conductivity and a metal spacer having thermal conductivity are provided between a press-contact type semiconductor element and a cooler. In a semiconductor stack having at least a seed, a semiconductor element, a metal spacer, a ceramic plate, and a cooler stacked in this order, and pressing and holding these by pressing means, the metal spacer has a maximum diameter of both end faces of the semiconductor element. It has a disk shape larger than the post diameter,
A semiconductor stack is characterized in that a groove is provided circumferentially in a peripheral portion forming a curved surface of the metal spacer, and a diameter of the groove is substantially the same as a post diameter of the semiconductor element.

According to the first aspect of the present invention, since the groove is provided in the peripheral portion of the metal spacer, the force from the semiconductor element is dispersed at the outer peripheral end of the surface of the metal spacer to be joined to the ceramic plate, and the stress is reduced. This prevents concentration and prevents cracking of the ceramic plate.

According to a second aspect of the present invention, at least two types of a ceramic plate having electrical insulation and thermal conductivity and a metal spacer having thermal conductivity are provided between the press-contact type semiconductor device and the cooler. These are semiconductor elements, metal spacers,
In a semiconductor stack in which a ceramic plate and a cooler are stacked in this order and pressed and held by pressing means, both end faces of the metal spacer are circular, and the diameter of the end face on the semiconductor element side is slightly larger than the post diameter of the semiconductor element. The semiconductor stack according to the present invention is characterized in that the end face, which is large and is in contact with the ceramic plate, has a shape whose diameter gradually increases toward the ceramic plate so as to have a larger diameter.

According to the second aspect of the present invention, since the force from the semiconductor element is dispersed at the outer peripheral edge of the metal spacer, it is possible to prevent the stress from being concentrated on that portion and the ceramic plate from breaking.

According to a third aspect of the present invention, there is provided a semiconductor stack according to the second aspect, wherein the degree of the diameter of the metal spacer gradually increases as approaching the ceramic plate.

[0017] Therefore, stress concentration at the outer peripheral end of the metal spacer can be further reduced, so that cracking of the ceramic plate can be favorably prevented. According to a fourth aspect of the present invention, in the semiconductor stack according to any one of the first to third aspects, an edge of a surface of the metal spacer corresponding to the ceramic plate is chamfered into a convex curved surface over the entire circumference. is there.

Therefore, since the outer peripheral edge of the metal spacer in contact with the ceramic plate is not a corner but a convex curved surface, it is possible to prevent stress from being concentrated on that portion and damaging the ceramic plate.

According to a fifth aspect of the present invention, in any one of the first to fourth aspects of the present invention, a conductor for external electrical connection is integrally connected to the metal spacer by brazing or the like, and the connection position is the metal spacer. The semiconductor stack is located closer to the semiconductor element side in the thickness direction of the peripheral portion of the semiconductor stack.

According to the fifth aspect of the present invention, by integrally connecting the conductor to the metal spacer, the thermal resistance therebetween is improved, and the connection position for the integration is set to the thickness of the peripheral portion of the metal spacer. Since the conductor is less likely to apply a concentrated stress to the ceramic plate by disposing it closer to the semiconductor element side in the vertical direction, cracking of the ceramic plate can be prevented.

A sixth aspect of the present invention is the semiconductor stack according to any one of the first to fifth aspects, wherein the metal spacer is provided between the ceramic plate and the cooler.

According to the sixth aspect of the present invention, the metal spacer is provided between the ceramic plate and the cooler.
Even if the processing accuracy of the press contact surface of the cooler is poor, the concentration of stress applied to the ceramic plate is easily alleviated.

According to a seventh aspect of the present invention, there is provided a semiconductor stack in which a ceramic plate having electrical insulation and thermal conductivity is interposed between a press-contact type semiconductor element and a cooler, and these are pressed and held by pressing means. In the cooler, a plurality of plate-like fins are formed along a predetermined direction on a surface opposite to the semiconductor element mounting surface, and the pressing means has a semiconductor element at a center portion at both ends in a longitudinal direction thereof. The semiconductor stack is characterized in that a longitudinal direction of the spring and a direction of each of the fins of the cooler are in the same direction.

According to the seventh aspect of the present invention, since each fin is formed in a direction in which the section modulus is increased with respect to the bending direction of the cooler by the spring, the rigidity of the cooler is high,
Since bending distortion due to the spring is suppressed, bending stress applied to the ceramic plate can be reduced.

The invention according to claim 8 is a semiconductor stack in which a ceramic plate having electrical insulation and thermal conductivity is interposed between the press-contact type semiconductor element and the cooler, and these are pressed and held by pressing means. The outer peripheral portion of the ceramic plate is made of an insulator having a substantially L-shaped cross section due to a joining portion fixed to the outer peripheral portion of the one surface and a rising portion provided on the periphery of the joining portion. A semiconductor stack is provided with a ring body.

According to the eighth aspect of the present invention, since the peripheral portion of the ring body has a cylindrical rising portion, an insulation distance can be secured by the rising portion.
The outer dimensions of the ceramic plate can be reduced, and the size of the semiconductor stack can be reduced.

According to a ninth aspect of the present invention, in the semiconductor stack, a ceramic plate having electrical insulation and heat conductivity is interposed between the press-contact type semiconductor element and the cooler, and these are pressed and held by pressing means. The pressing means is a spring that can obtain a load for pressing the semiconductor element toward the center by supporting both ends thereof, and is fixed to the outer peripheral part of the ceramic plate by joining one end surface to the cooler. In a semiconductor stack, a reinforcing ring is provided, and a stud bolt for supporting a spring is screwed into the reinforcing ring.

According to the ninth aspect of the present invention, since the stress generated in the spring is dispersed and transmitted from the stud bolt to the cooler via the reinforcing ring, the stress of the spring is directly transmitted from the stud bolt to the cooler. The bending generated on the press-contact surface of the cooler can be reduced as compared with the case where the cooling device is used.

[0029]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS (First Embodiment) FIGS. 1 and 2
1 shows a first embodiment of the present invention. FIG. 1 is a front view of a semiconductor stack according to the first embodiment of the present invention.
2A is an enlarged view of a portion A in FIG. 1, and FIG. 2B is a perspective view of a metal spacer.

The semiconductor stack has a cooler 2 for cooling the semiconductor device 1. On the upper surface of the cooler 2, a ceramic plate 3 made of a material having a high insulating property and a high thermal conductivity, a metal spacer 7 made of a material having a high thermal conductivity such as copper or aluminum, and the semiconductor element 1 to the outside. The conductor 4c for electrical connection, the semiconductor element 1, the other conductor 4a for electrically connecting the semiconductor element 1 to the outside, and the insulating spacer 6 are sequentially laminated so that the center portions of the respective components substantially coincide with each other. Have been. The laminate 8 is pressed and held by the leaf spring 5.

That is, the leaf spring 5 is formed by a band-shaped plate having a predetermined thickness and has a length longer than the diameter of the laminated body 8, and both ends thereof are formed on the upper surface of the cooler 2. It is supported by a pair of stud bolts 9 erected outside the body 8 in the radial direction. A nut 11 is screwed into a screw portion 9 a formed at the upper end of the stud bolt 9, and a pressing spacer 12 is interposed between the lower surface of the leaf spring 5 and the insulating spacer 6. Therefore, if the nut 11 is tightened, the pressing spacer 1
Each component of the laminated body 8 is elastically pressed by the leaf spring 5 through the intermediary 2 and is held integrally with the cooler 2.

The metal spacer 7 is provided with a groove 13 on the peripheral surface thereof at a predetermined depth over the entire length, and the edge of the surface in contact with the ceramic plate 3 has a convex curved surface 14 as shown in FIG. Beveled. A pair of upper and lower flanges 7a and 7b are formed around the metal spacer 7 by the groove 13.

Both the diameter D1 which is the outer dimension of the flange 7a located on the semiconductor element 1 side of the metal spacer 7 and the diameter D2 which is the outer dimension of the flange 7b located on the ceramic plate 3 side are the same as those of the semiconductor element 1. The diameter D3, which is set to be larger than the post diameter D, and which is the outer dimension of the groove 13 at an intermediate portion in the thickness direction, is set to be substantially the same as the post diameter D of the semiconductor element 1.

The metal spacer 7 is subjected to a heat treatment by annealing, and is thereby softened. Further, a large number of fins 2 a for increasing a heat radiation area are formed on the lower surface side of the cooler 2 along a direction intersecting the longitudinal direction of the leaf spring 5.

(Operation) According to the semiconductor stack having the above structure, the groove 13 is formed in the metal spacer 7, so that the flange 7b is formed on the side of the metal spacer 7 which is in contact with the ceramic plate 3. Therefore, when the stacked body 8 is pressed by the leaf spring 5 and held integrally with the cooler 2, the force transmitted from the portion of the semiconductor element 1 having the post diameter D to the metal spacer 7 is as shown in FIG. As shown by an arrow in ()), the particles are dispersed radially outward of the flange 7b. Therefore, it is possible to reduce the concentration of stress on the portion corresponding to the bottom of the groove 13 and the contact portion with the ceramic plate 3 as indicated by B in the figure as in the case where the flange 7b is not provided. The portion is formed on the convex curved surface 14 by chamfering. Therefore, even if the force transmitted to the metal spacer 7 is distributed to the flange 7b, FIG.
Since stress can be prevented from being concentrated on the portion indicated by C in FIG. 3A, damage to the portion corresponding to C of the ceramic plate 3 is also prevented.

Further, since the metal spacer 7 is annealed and softened by the heat treatment, it absorbs small errors in processing such as surface roughness, flatness, parallelism and the like of the bonding surface with the ceramic plate 3. This alleviates the concentration of stress between these joining surfaces.

Therefore, according to the first embodiment, the concentration of stress at the periphery of the laminate 8, that is, at the periphery of the metal spacer 7 joined to the ceramic plate 3 is eliminated.
Pressing with a uniform load becomes possible, and it is possible to prevent an excessive stress from being applied to the ceramic plate 3, so that a highly reliable semiconductor stack against cracking of the ceramic plate 3 can be realized.

Further, by inserting the metal spacer 7, the insulation distance between the conductor 4c and the cooler 2 can be ensured. Thereby, since it is not necessary to provide a bending process in the middle of the conductor 4c to secure insulation, there is also an advantage that the shape can be simplified.

(Other Embodiments) Next, second to eighth embodiments of the present invention will be described with reference to FIGS. The same parts as those in the first embodiment are denoted by the same reference numerals, and description thereof will be omitted.

(Second Embodiment) FIG. 3 is a front view of a semiconductor stack according to a second embodiment of the present invention. This embodiment is a modification of the metal spacer 7A. The metal spacer 7A is formed in a tapered shape whose diameter increases as the outer peripheral surface goes from the upper surface to the lower surface. That is, the diameter of the end surface on the semiconductor element 1 side, which is the upper surface of the metal spacer 7A, is slightly larger than the post diameter D of the semiconductor element 1, and the diameter of the lower surface, which is in contact with the opposite Lamix plate 3, is further increased. The outer peripheral surface between the upper surface and the lower surface of the metal spacer 7A is formed in the tapered portion 15.

When the metal spacer 7A having such a configuration is used, similarly to the first embodiment, the force transmitted from the semiconductor element 1 is dispersed to the peripheral portion by the tapered portion 15 of the metal spacer 7A. There is no stress concentration at the outer peripheral portion of the spacer 7A, and a highly reliable semiconductor stack against cracks in the ceramic plate 3 can be realized.

(Third Embodiment) FIG. 4 is a front view of a semiconductor stack according to a third embodiment of the present invention. The second embodiment is a modification of the metal spacer 7B. The metal spacer 7B is similar to the second embodiment in that the lower surface has a larger diameter than the upper surface.
The second embodiment differs from the second embodiment in that the outer peripheral surface is formed as a slope 16 having a concave curved surface.

In the third embodiment as well, the stress at the periphery of the metal spacer 7B is relaxed in the same manner as in the second embodiment. The effect of the stress attenuation at the outermost peripheral portion in contact with No. 3 is great.

(Fourth Embodiment) FIG. 5 is a front view of a semiconductor stack according to a fourth embodiment of the present invention. In the present embodiment, the conductor 4d is integrated (by brazing or the like) around the metal spacer 7.

With such a configuration, the contact thermal resistance between the conductor 4d and the metal spacer 7 is eliminated, and the temperature reduction efficiency of the semiconductor element 1 can be improved. Further, the connection portion of the conductor 4d is provided on the upper side in the thickness direction of the peripheral portion of the metal spacer 7, that is, on the semiconductor element 1 side (connected to the flange 7a). The influence of the unevenness of stress in the metal spacer 7 due to this is unlikely to appear on the surface of the metal spacer 7 to which the ceramic plate 3 is joined. For this reason, it is possible to prevent the ceramic plate 3 from being unevenly pressed by the metal spacer 7 and damaged.

(Fifth Embodiment) FIG. 6 is a front view of a semiconductor stack according to a fifth embodiment of the present invention. In the present embodiment, the metal spacer 7 is provided not only between the ceramic plate 3 and the conductor 4c but also between the ceramic plate 3 and the cooler 2.

According to such a configuration, it is possible to reduce the stress concentration of the ceramic plate 3 from the cooler 2 and the application of non-uniform stress by the action of the pair of metal spacers 7.

In addition, the ceramic plate 3 is sandwiched between the pair of metal spacers 7, so that the periphery thereof is in a state of being floated from the upper surface of the cooler 2. Therefore, the force from the semiconductor element 1 is not applied to the peripheral portion of the ceramic plate 3, so that the supporting span of the ceramic plate 3 is reduced and the bending stress applied thereto is also reduced, which is advantageous for cracking.

The insulation between the conductor 4c and the cooler 2 is as follows:
It is ensured by the creepage distance L2 using the upper and lower surfaces of the peripheral portion of the ceramic plate 3 sandwiched between the pair of metal spacers 7. Therefore, the size of the ceramic plate 3 can be reduced, and the distance L between the support points of the plate spring 5 can be reduced.
Since the value of 1 can be reduced, the size of the leaf spring 5 can also be reduced, so that the size of the semiconductor stack can be reduced.

(Sixth Embodiment) FIGS. 7A and 7B
FIG. 7A shows a plan view of a semiconductor stack, and FIG. 7B shows a front view of a sixth embodiment of the present invention.

In the present embodiment, a plurality of plate-like fins 2a are provided on the lower surface side of the cooler 2 at predetermined intervals along a predetermined direction, and the surface is opposite to the surface on which the fins 2a are provided. On the upper surface, a laminate 8 such as the semiconductor element 1 is provided with a leaf spring 5.
Pressed and held. A pair of stud bolts 9
Each of the above-described embodiments is characterized in that the band-shaped leaf spring 5 whose both ends are supported and the laminated body 8 is pressed and held is provided so that its longitudinal direction is the same as the longitudinal direction of the fin 2a. Is different.

According to such a configuration, the nut 11 is tightened to press the middle part of the leaf spring 5 in the longitudinal direction against the laminated body 8, and when the laminated body 8 is held, the reaction force generated by the stud bolt 13 is generated. The fins 12 are arranged in a direction to increase the section modulus of the cooler 2 with respect to the bending load applied to the cooler 2. Therefore, the amount of bending strain generated in the cooler 2 can be suppressed to a small value, so that the bending stress applied to the ceramic plate 3 in contact with the cooler 2 also decreases, and the reliability of the ceramic plate 3 against cracking improves.

(Seventh Embodiment) FIGS. 8A and 8B
8 shows a seventh embodiment of the present invention. FIG. 8A is a front view of a semiconductor stack, and FIG. 8B is a perspective view of an insulating flange. In the present embodiment, similarly to the fifth embodiment, the ceramic plate 3 is formed by a pair of metal spacers 7.
When the ceramic plate 3 is miniaturized, the insulating ring body 18 is formed using the space 17 formed between the lower surface of the peripheral portion of the ceramic plate 3 and the upper surface of the cooler 2. It is provided.

As shown in FIG. 8 (b), the insulating ring body 18 is made of an electrically insulating material, and has a joining portion 18a which is horizontal in the radial direction and a rising portion 18b which stands upright on the periphery of the joining portion 18a. Thus, the cross-sectional shape is substantially L-shaped. The inner diameter of the joint 18 a is smaller than the outer dimension of the ceramic plate 3, and the outer dimension is set to be larger than the outer dimension of the ceramic plate 3.

The insulating ring 18 is provided with the joining portion 18a joined and fixed to the periphery of the lower surface of the ceramic plate 3 with an adhesive or the like, with the rising portion 18b surrounding the periphery of the ceramic plate 3. That is, the presence of the space portion 17 allows the insulating ring body 18 to be provided in a state where a part (joining portion 18 a) is located on the lower surface of the ceramic plate 3.

By providing the insulating ring body 18 having such a structure on the ceramic plate 3, the joining portion 18a and the rising portion 18b allow L3 between the upper surface of the cooler 2 and the semiconductor element 1 as shown in FIG. Can be ensured. Therefore, not only the size of the ceramic plate 3 can be reduced, but also the distance between the pair of support points of the leaf spring 5 can be reduced, so that the size of the leaf spring 5 and the size of the semiconductor stack can be reduced. It is possible.

In the seventh embodiment, the metal spacers 7 are provided on the upper and lower surfaces of the ceramic plate 3 in order to form the space 17 around the lower surface side of the ceramic plate 3, but instead the lower spacers are provided. When the metal spacer 7 is integrally formed on the upper surface of the cooler 2 or the metal spacer 7 is not provided on the lower side, a space is formed in a portion corresponding to the peripheral portion of the ceramic plate 3 on the upper surface of the cooler 2. By forming the concave portion in an annular shape, the joint portion 18a of the insulating ring body 18 may be provided to be provided around the lower surface of the ceramic plate 3 using the concave portion 19.

(Eighth Embodiment) FIGS. 9 and 10 show an eighth embodiment of the present invention. FIG. 9 (a) is a plan view of a semiconductor stack, FIG. 9 (b) is a front view, FIG. 10 is a perspective view of a reinforcing ring body. In this embodiment, in this embodiment, a hollow reinforcing ring 21 having an inner diameter larger than the outer dimensions of the ceramic plate 3 is attached to the cooler 2, and a pair of stud bolts 13a supporting the leaf spring 5 are reinforced. The laminated body 8 is erected on the ring body 21 and is pressed and held by the leaf spring 5.

That is, the reinforcing ring body 21 has a large number of bolt holes 22 for attaching the reinforcing ring body 21 to the cooler 2 and two bolt holes 22 for screwing the stud bolts 13A.
Two female screws 23 are provided.

The cooling device 2 is also provided with a female screw 24 at a position corresponding to the bolt hole 22 of the reinforcing ring body 21, and the reinforcing ring body 21 is attached to the laminated body 8 and its center by a bolt 25 screwed into the female screw 24. Is fixed at the position where

The stud bolt 9 is screwed into the female thread 23 of the reinforcing ring body 21, and both ends of the leaf spring 5 are supported on the stud bolt 9 and pressed against the laminated body 8. According to the present embodiment, the reaction force generated by the leaf spring 5 pressing and supporting the laminate 8 is 2
Instead of being directly applied to the cooler 2 via the stud bolts 9, it is dispersed in the circumferential direction by the reinforcing ring body 21 and applied to the cooler 2.

As a result, the bending generated on the upper surface of the cooler 2 to which the ceramic plate 3 is bonded is reduced, so that the bending load applied to the ceramic plate 3 bonded to the upper surface is reduced, and the ceramic plate 3 is prevented from being broken by bending. Can be prevented. In addition, since the rigidity of the cooler 2 can be increased by providing the reinforcing ring body 21 in the cooler 2, the thickness of the cooler 2 is increased in order to increase the rigidity of the cooler 2 as in the related art. Since it is not necessary to perform such operations, the cooler 2 can be reduced in size and measured.

[0063]

According to the present invention, it is possible to prevent partial concentrated load and excessive bending stress from being applied to the ceramic body, to obtain a uniform and favorable pressure distribution, and to prevent the ceramic plate from cracking. Also, for the semiconductor element, the internal pressure distribution becomes uniform, so that the element characteristics are improved.
A highly reliable semiconductor stack can be realized.

Further, it is possible to reduce the size of the laminated component (laminated body), so that the bending generated in the cooler is reduced, the bending stress applied to the ceramic plate is reduced, and the reliability is improved. Become.

[Brief description of the drawings]

FIG. 1 is a front view of a semiconductor stack according to a first embodiment of the present invention.

2A is an enlarged view of a portion A in FIG. 1, and FIG.
The perspective view of a metal spacer.

FIG. 3 is a front view of a semiconductor stack according to a second embodiment of the present invention.

FIG. 4 is a front view of a semiconductor stack according to a third embodiment of the present invention.

FIG. 5 is a front view of a semiconductor stack according to a fourth embodiment of the present invention.

FIG. 6 is a front view of a semiconductor stack according to a fifth embodiment of the present invention.

FIG. 7A is a plan view of a semiconductor stack according to a sixth embodiment of the present invention, and FIG. 7B is a front view of the same semiconductor stack.

FIG. 8A is a front view of a semiconductor stack according to a seventh embodiment of the present invention, and FIG. 8B is a perspective view of the same insulating flange.

FIG. 9A is a plan view of a semiconductor stack according to an eighth embodiment, and FIG. 9B is a front view of the semiconductor stack according to the eighth embodiment.

FIG. 10 is a perspective view of a reinforcing ring according to an eighth embodiment of the present invention.

FIG. 11A is a plan view of a conventional semiconductor stack,
(B) is a front view of the same semiconductor stack.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Semiconductor element 2 ... Cooler 2a ... Fin 3 ... Ceramic plate 4a, 4c, 4d ... Conductor 5 ... Leaf spring 6 ... Insulating spacer 7, 7A, 7B ... Metal spacer 9 ... Stud bolt 13 ... Groove 14 ... Convex curved surface 15 ... taper portion 16 ... slope portion 18 ... insulating ring body 23 ... reinforcing ring body

Claims (9)

[Claims] 1. A semiconductor device having at least two types of a ceramic plate having electrical insulation and thermal conductivity and a metal spacer having thermal conductivity between a press-contact type semiconductor element and a cooler.
In a semiconductor stack in which a semiconductor element, a metal spacer, a ceramic plate, and a cooler are stacked in this order, and these are pressed and held by pressing means, the metal spacer has a disk shape in which the maximum diameter of both end faces is larger than the post diameter of the semiconductor element. Wherein a groove is provided circumferentially around a peripheral portion forming a curved surface of the metal spacer, and the diameter of the groove is substantially the same as the post diameter of the semiconductor element. . 2. A semiconductor device having at least two types of a ceramic plate having electrical insulation and thermal conductivity and a metal spacer having thermal conductivity between a press-contact type semiconductor element and a cooler.
These are semiconductor elements, metal spacers, ceramic plates,
In the semiconductor stack stacked in the order of the coolers and pressed and held by pressing means, the metal spacers have circular end faces, and the diameter of the end face on the semiconductor element side is slightly larger than the post diameter of the semiconductor element. A semiconductor stack, characterized in that the end face on the opposite side in contact with the substrate has a larger diameter, and the diameter gradually increases toward the ceramic plate. 3. The semiconductor stack according to claim 2, wherein the degree of the gradual increase in the diameter of the metal spacer increases as it approaches the ceramic plate. 4. The semiconductor stack according to claim 1, wherein an edge of a surface of said metal spacer which contacts said ceramic plate is chamfered to a convex curved surface over an entire circumference. 5. The metal spacer according to claim 1, wherein a conductor for external electrical connection is integrally connected to the metal spacer by brazing or the like, and the connection position is in a thickness direction of a peripheral portion of the metal spacer. A semiconductor stack, which is closer to the semiconductor element side. 6. The semiconductor stack according to claim 1, wherein a metal spacer is provided between the ceramic plate and the cooler. 7. A semiconductor stack in which a ceramic plate having electrical insulation and heat conductivity is interposed between a press-contact type semiconductor element and a cooler, and these are pressed and held by pressing means, wherein the cooler is the semiconductor A plurality of plate-like fins are formed along a predetermined direction on the surface opposite to the element mounting surface, and the pressing means is provided with a load for pressing the semiconductor element at the center at both ends in the longitudinal direction. A semiconductor stack, wherein a longitudinal direction of the spring and a direction of each fin of the cooler are the same. 8. A semiconductor stack in which a ceramic plate having electrical insulation and heat conductivity is interposed between a press-contact type semiconductor element and a cooler, and these are pressed and held by pressing means, wherein an outer peripheral portion of said ceramic plate is provided. A ring body made of an insulator having a substantially L-shaped cross section is provided by a joint portion fixedly joined to an outer peripheral portion of the one surface and a rising portion provided on the periphery of the joint portion. A semiconductor stack, characterized in that: 9. A semiconductor stack in which a ceramic plate having electrical insulation and thermal conductivity is interposed between a press-contact type semiconductor element and a cooler, and these are pressed and held by pressing means, wherein the pressing means comprises A spring capable of obtaining a load pressing the semiconductor element at the center by being supported at both ends, and a reinforcing ring fixed at one end face to the cooler at an outer peripheral portion of the ceramic plate. And a stud bolt supporting a spring is screwed into the reinforcing ring.