JP2022180875A - Semiconductor device - Google Patents

Abstract

To provide a semiconductor device having a structure capable of securing heat radiation property while suppressing stress fractures of a power semiconductor element.SOLUTION: A semiconductor element 4 is arranged inside an outline of a recessed part 31 of a conductor 3, and has an outer peripheral portion fixed to the conductor 3 with a fixing member 6. At a gap between the conductor 3 and the semiconductor element 4 of the recessed part 31, a conductive heat radiation material 5 is arranged, the conductive heat radiation material being in a liquid state during drive of the semiconductor element 4. This allows reduction in connection area between the conductor 3 and the semiconductor element 4, which reduces a stress applied to the semiconductor element 4, and heat of the semiconductor element 4 is propagated to the conductor 3 by the conductive heat radiation material 5 while securing conduction between the conductor 3 and the semiconductor element 4, so that the heat radiation property of the semiconductor element 4 can be secured.SELECTED DRAWING: Figure 1

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor device having a structure in which heat from a semiconductor element is released to the outside through a liquid conductive heat dissipation material.

Conventionally, there is known a semiconductor device in which a power semiconductor element such as a power MOSFET (Metal-Oxide-Semiconductor Field Effect Transistor) is bonded to a metal film on an insulating substrate via solder (for example, Patent Document 1). In the semiconductor device described in Patent Document 1, a metal module substrate is welded to the surface of the insulating substrate opposite to the power semiconductor element, and heat generated by driving the power semiconductor element is transferred to the module substrate side through the solder. It has a structure in which it propagates and is released to the outside.

Japanese Patent Application Laid-Open No. 8-8395

In recent years, in this type of semiconductor device, the thickness of the power semiconductor element has been reduced. However, as the power semiconductor element becomes thinner, the amount of deformation of the power semiconductor element caused by heat generated during driving increases. According to studies by the present inventors, in a semiconductor device having a structure in which a thin power semiconductor element is bonded to another member having a different coefficient of linear expansion via solder, the stress applied to the power semiconductor element is large, and the power semiconductor element was found to undergo stress failure.

On the other hand, if the bonding area between the power semiconductor element and other members becomes small, the stress on the power semiconductor element caused by the difference in coefficient of linear expansion can be suppressed, but the heat generated by driving the power semiconductor element is trapped. , the heat dissipation deteriorates.

In view of the above points, the present invention provides a semiconductor device having a structure capable of ensuring heat dissipation while suppressing stress damage of the power semiconductor element even when a thin power semiconductor element is used. intended to

In order to achieve the above object, a semiconductor device according to claim 1 comprises a semiconductor element (4) having a front surface (4a) and a back surface (4b), and a recess facing the back surface and having a larger outline than the semiconductor element. (31) and a conductor (3) having an air trap (32) which is a recess provided in the bottom surface of the recess, and a conductor (3) disposed in a gap between the semiconductor element and the recess, being in a liquid state at least when the semiconductor element is driven, A fixing member for fixing the semiconductor element to the conductor, which is arranged to connect the conductive heat dissipating material (5) having conductivity, at least one of the side surfaces (4c) connecting the front surface and the front surface and the back surface of the semiconductor element, and the conductor. (6), and an expansion member (7) which has flexibility, is arranged between the fixing member and the conductor, contacts the conductive heat dissipation material, and expands due to heat generated when the semiconductor element is driven, The semiconductor element is arranged inside the contour of the recess and is thermally connected to the conductor via the conductive heat dissipating material.

According to this, a semiconductor device comprising a semiconductor element and a conductor having a recess, wherein the semiconductor element is arranged inside the contour of the recess of the conductor, and the semiconductor element is connected and fixed to the conductor by a fixing member at a portion other than the back surface. becomes. Therefore, the connection area between the semiconductor element and the conductor is reduced, the stress applied to the semiconductor element is reduced, and even if the semiconductor element is thinned, damage due to stress can be suppressed. In addition, since the semiconductor element is thermally connected to the conductor through the conductive heat dissipating material that has conductivity and becomes liquid during operation, the semiconductor element and the conductor can be heat dissipation is improved.

Furthermore, since the air trap is arranged on the bottom surface of the concave portion, even if air bubbles are generated in the conductive heat dissipating material due to some factor such as phase transition, the air bubbles are captured by the air trap and the conductor of the semiconductor element is removed. Air bubbles are suppressed from intervening in the gap between the conductor and the one surface facing the . In addition, since the expansion member that expands due to the heat generated when the semiconductor element is driven is arranged between the concave portion and the fixing member, the expansion member expands when the semiconductor element is driven, thereby displacing the liquid conductive heat dissipation material as described above. It has a structure that pushes out into the gap between Due to these actions, when the semiconductor element is driven, air bubbles intervene in the gap between the one surface of the semiconductor element and the concave portion, and the increase in thermal resistance is suppressed, resulting in a semiconductor device capable of securing more heat dissipation. .

It should be noted that the reference numerals in parentheses attached to each component etc. indicate an example of the correspondence relationship between the component etc. and specific components etc. described in the embodiments described later.

1 is a cross-sectional view showing a semiconductor device according to a first embodiment; FIG. FIG. 4 is a plan view showing an example of the arrangement relationship among conductors, semiconductor elements, and fixing members; FIG. 2 is an enlarged cross-sectional view of the III region of FIG. 1 showing how air bubbles are trapped in an air trap. FIG. 10 is a diagram showing a step of preparing members in the manufacturing method of the semiconductor device according to the first embodiment; FIG. 4B is a diagram showing a manufacturing process following FIG. 4A; FIG. 4C is a diagram showing a manufacturing process following FIG. 4B; FIG. 4D is a diagram showing a manufacturing process following FIG. 4C; 4C is a diagram showing the manufacturing process following FIG. 4D; FIG. FIG. 4D is a diagram showing a manufacturing process following FIG. 4E; 4F is a diagram showing the manufacturing process following FIG. 4F; FIG. FIG. 5 is an explanatory view for explaining the pushing of the conductive heat dissipating material by the expansion member and the flow of the conductive heat dissipating material. FIG. 10 is a plan view showing another arrangement example of the expansion member and the flow of the conductive heat dissipating material due to this. FIG. 10 is a plan view showing another arrangement of the expansion member and the flow of the conductive heat dissipating material. FIG. 10 is a plan view showing still another arrangement of the expansion member and the flow of the conductive heat dissipating material. It is a sectional view showing a semiconductor device of a 2nd embodiment. FIG. 10 is an enlarged cross-sectional view showing the X region of FIG. 9;

An embodiment of the present invention will be described below with reference to the drawings. In addition, in each of the following embodiments, portions that are the same or equivalent to each other will be described with the same reference numerals.

(First embodiment)
A semiconductor device 1 of the first embodiment will be described with reference to FIGS. 1 to 3. FIG. The semiconductor device 1 of the present embodiment is, for example, an in-vehicle application that is mounted in a vehicle such as an automobile, and is preferably applied to a power card or the like, but can of course be applied to other applications.

FIG. 1 shows a cross-sectional configuration at a position corresponding to the cross section taken along line I-I shown in FIG. 2, and a part of wiring 8, which will be described later, is omitted for the sake of clarity. In FIG. 2, in order to make it easier to understand the positional relationship of the conductor 3, the semiconductor element 4 and the fixing member 6, which will be described later, the outline of the area in which the semiconductor element 4 is arranged is indicated by a dashed line, and the outline of the area in which the fixing member 6 is arranged is indicated by broken lines. is indicated by a two-dot chain line.

[Basic configuration]
The semiconductor device 1 of this embodiment includes an insulating substrate 2, a conductor 3, a semiconductor element 4, a conductive heat dissipating member 5, a fixing member 6, an expansion member 7, and wiring 8, as shown in FIG. have In the semiconductor device 1, the conductor 3 has a recess 31, the semiconductor element 4 is arranged inside the contour of the recess 31, and is fixed to the conductor 3 by the fixing member 6 arranged at a position different from the recess 31. . The semiconductor device 1 has an air trap 32 formed on the bottom surface of the recess 31 . The semiconductor device 1 has a surface 4a opposite to the conductor 3 of the semiconductor element 4 and a back surface 4b opposite to the surface 4a. A conductive heat dissipating material 5 that becomes liquid during driving is arranged. The semiconductor device 1 is used with the back surface 4 b facing in the direction opposite to the vertical direction (hereinafter referred to as the “upward direction”). It has an intrusive structure.

The insulating substrate 2 is, for example, a plate-shaped member made of any insulating material such as aluminum nitride. For example, the conductor 3 is formed on the insulating substrate 2, or a separate conductor 3 is attached by brazing material (not shown) or the like.

The conductor 3 is a member made of, for example, a metal material having electrical conductivity and high thermal conductivity, such as Cu (copper) or Al (aluminum), or an alloy thereof. The conductor 3 is, for example, an electrode formed on the insulating substrate 2 or a member separate from the insulating substrate 2 such as a bus bar or a lead frame. The conductor 3 may have a plating layer (not shown) covering the outermost surface thereof, if necessary. For example, when the conductor 3 is made of Al and the conductive heat dissipating material 5 described later is mainly made of Ga (gallium), the conductor 3 has corrosion resistance to Ga in order to suppress corrosion by the conductive heat dissipating material 5. A plating layer (not shown) is formed. In such a case, the conductor 3 has a structure in which a plated layer is formed over at least the entire region in contact with the conductive heat dissipating member 5 . The conductor 3 has a concave portion 31 having a plane size larger than the outline of the semiconductor element 4 and facing the back surface 4 b of the semiconductor element 4 and an air trap 32 .

The recessed portion 31 is a region where the conductive heat dissipating material 5 is arranged, and has an air trap 32 which is a recess provided on the bottom surface thereof.

The air trap 32 is, for example, a plurality of grooves extending along the side formed by the contour of the recess 31 as shown in FIG. For example, the plurality of air traps 32 are independent of each other, and when air bubbles or breaks in the conductive heat dissipating material 5 occur in the gap between the semiconductor element 4 and the recess 31 as shown in FIG. It is provided to capture air bubbles and air carried by the flow and prevent them from escaping. The air trap 32 is arranged, for example, in a region of the bottom surface of the recess 31 located on or outside the outline of the semiconductor element 4 .

As a result, when air bubbles are trapped in the air trap 32, an increase in thermal resistance due to interposition of the air bubbles between the back surface 4b of the semiconductor element 4 and the bottom surface of the recess 31 is suppressed, and heat dissipation is improved. Further, since the air trap 32 has a structure in which air remains in the air trap 32 when the semiconductor element 4 is driven, the conductive heat radiating material 5 is pushed in by the expansion member 7 described later through the air, and the conductor 3 and the semiconductor element 4 are separated. There is also an effect of suppressing excessive pressure from being applied to the gap.

For example, when the contour of the recess 31 is square, the plurality of air traps 32 are arranged along each of the four sides of the contour and in a region different from the corners of the contour. However, it is not limited to this. For example, since the contour shape, size, etc. of the recess 31 can be appropriately changed according to the contour shape of the semiconductor element 4 , the number, size, arrangement, etc. of the plurality of air traps 32 can be changed according to the contour shape, etc. of the recess 31 . It may be changed as appropriate.

The semiconductor element 4 has, for example, a rectangular plate shape having a front surface 4a and a back surface 4b, and is made of a semiconductor material such as Si (silicon) or SiC (silicon carbide). The semiconductor element 4 is, for example, a power element such as a vertical power MOSFET, and is manufactured by a known semiconductor process. The semiconductor element 4 is, for example, a thin power element having a dimension of 200 μm or less in the thickness direction connecting the front surface 4a and the rear surface 4b. Electrode films (not shown) are formed on the front surface 4a and the rear surface 4b of the semiconductor element 4, and the wiring 8 made of wires or the like is connected to the front surface 4a to enable electrical communication with the outside.

The semiconductor element 4 is arranged in a region of the conductor 3 inside the contour of the recess 31 while being spaced apart from the conductor 3 , and its outer peripheral portion is fixed to the conductor 3 by a fixing member 6 . In other words, the semiconductor element 4 is connected and fixed to the conductor 3 via the fixing member 6 but is not in direct contact with the conductor 3 .

The conductive heat dissipating material 5 is arranged in the recess 31, has electrical conductivity and thermal conductivity equal to or higher than a predetermined value, and is a member that becomes liquid at least when the semiconductor element 4 generates heat. The conductive heat dissipating material 5 is made of liquid metal such as Ga (gallium) having a melting point of about 29.7° C. or an alloy thereof. The conductive heat dissipating material 5 ensures conduction between an electrode (not shown) formed on the back surface 4b of the semiconductor element 4 and the conductor 3, and conducts the heat to the conductor 3 when the semiconductor element 4 generates heat, thereby improving heat dissipation. play a role. In addition, since the conductive heat dissipating material 5 has fluidity, even if bubbles are generated in the recess 31, the bubbles are transported to the air trap 32, and the air trap 32 easily traps the bubbles. occur.

It should be noted that the conductive heat dissipating material 5 is not limited to the materials described above, as long as it is conductive and at least becomes liquid when the semiconductor element 4 generates heat and is fluid. For example, the conductive heat dissipation material 5 may be Hg (mercury), Cs (cesium), Rb (rubidium), K (potassium), Na (sodium), In (indium), or an alloy containing at least one of these. or other known materials. Also, the conductive heat dissipation material 5 may be in a state other than a liquid state such as a gel state or a paste state when the semiconductor element 4 is not driven or at room temperature. Furthermore, the generation of air bubbles and air in the recessed portion 31 includes, for example, volume reduction when the conductive heat dissipating material 5 undergoes a phase transition from solid to liquid, and when a plating layer (not shown) is provided in the recessed portion 31 of the conductor 3 . Generation of outgassing from the plating layer and the like can be mentioned.

The fixing member 6 is arranged to connect, for example, a portion of the conductor 3 located outside the recess 31 and a side surface connecting the front surface 4a or the front surface 4a and the back surface 4b of the semiconductor element 4, or both, It is a member for connecting and fixing the semiconductor element 4 to the conductor 3 . The fixing member 6 is made of, for example, an arbitrary hardening resin material such as an epoxy resin, and is arranged by coating with a dispenser or the like.

The expansion member 7 is made of a resin material having flexibility and a thermal expansion coefficient larger than that of the material of the fixing member 6, and is a member that expands when the semiconductor element 4 generates heat. The expansion member 7 is made of, for example, foamed silicon containing a plurality of independent cells inside. The expansion member 7 is disposed between the fixing member 6 and the conductor 3 , at least partially above the air trap 32 , and is in contact with the conductive heat dissipation material 5 . The expansion member 7 expands when the semiconductor element 4 generates heat, and increases the pressure in the air trap 32 to push the liquid conductive heat dissipation material 5 into the gap between the semiconductor element 4 and the recess 31 . As a result, it is possible to suppress the occurrence of a portion where the conductive heat dissipating material 5 does not exist in the gap between the semiconductor element 4 and the concave portion 31 (that is, the lack of liquid), and prevent an increase in thermal resistance between the semiconductor element 4 and the conductor 3. , the effect of improving the heat dissipation of the semiconductor element 4 is produced.

The wiring 8 is, for example, a metal wire made of Al, Cu, or the like, and is connected to an electrode (not shown) on the surface 4a of the semiconductor element 4 by wire bonding. The wiring 8 has one end opposite to the semiconductor element 4 side, for example, and is connected to another circuit board or the like (not shown) so that a voltage can be applied to the semiconductor element 4 from an external power supply (not shown).

The above is the basic configuration of the semiconductor device 1 of this embodiment.

〔Production method〕
Next, a method for manufacturing the semiconductor device 1 of this embodiment will be described with reference to FIGS. 4A to 4G.

First, as shown in FIG. 4A, an insulating substrate 2 and a conductor 3 having recesses 31 and air traps 32 are prepared. The insulating substrate 2 and the conductor 3 may be configured by joining these two members, or may be configured by forming the conductor 3 as an electrode on the insulating substrate 2 . The recesses 31 and the air traps 32 are formed by arbitrary methods such as etching and cutting, for example.

The semiconductor device 1 is manufactured in a state in which each member is oriented in a direction opposite to the state in which it is used, for example, in a state in which the concave portion 31 of the conductor 3 faces upward. Further, the air trap 32 is preferably surface-treated with, for example, a fluororesin or the like so that the wettability of the conductive heat dissipating member 5 is worse than that of the concave portion 31 . As a result, the liquid conductive heat dissipating material 5 is less likely to remain in the air trap 32 and is more likely to be pushed into the gap between the semiconductor element 4 and the recess 31 . Further, by reducing the wettability of the conductive heat dissipating material 5 in the air trap 32, an effect of reducing the area of the air trap 32 is expected.

Subsequently, for example, as shown in FIG. 4B, a positioning jig J is prepared for positioning the semiconductor element 4 and the conductive heat dissipating member 5 in the concave portion 31, and the jig J is arranged on the conductor 3. As shown in FIG. The jig J is, for example, a plate-shaped carbon member having an opening J<b>1 whose planar size is smaller than the outline of the recess 31 and larger than the outline of the semiconductor element 4 . The jig J may be made of a material that does not allow the liquid conductive heat dissipating material 5 to wet and spread, or may be surface-treated, and the material and configuration may be changed as appropriate. Then, the conductive heat-dissipating member 5 and the semiconductor element 4 are placed in the concave portion 31 of the conductor 3 in this order while being positioned by the jig J. As shown in FIG. At this time, for example, the environmental temperature is lower than the melting point of the conductive heat dissipating material 5, and the conductive heat dissipating material 5 is in a plate-like state.

Next, as shown in FIG. 4C, for example, the workpiece having the semiconductor element 4 and the conductive heat dissipating material 5 arranged in the recess 31 of the conductor 3 is heated by a heating stage (not shown) to melt the conductive heat dissipating material 5 . At this time, from the viewpoint of preventing unintentional air bubbles from remaining between the semiconductor element 4 and the conductor 3, the environment in which the heated work is placed is depressurized, and the work is shaken to perform defoaming. is preferred. In addition, from the viewpoint of reducing outgassing from the conductive heat dissipating material 5, the heating temperature of the workpiece is set to the maximum temperature or higher at the time of heat generation of the semiconductor element 4 (although not limited, if the heat generation temperature is 140 ° C., it is set to 150 ° C. etc.) is preferable. The heating temperature of the workpiece can be appropriately adjusted according to the maximum temperature, for example, when the semiconductor element 4 is mainly composed of SiC and operates at a higher temperature. After the conductive heat dissipating material 5 is melted and the air trap 32 is filled, the conductive heat dissipating material 5 is solidified by, for example, cooling, the semiconductor element 4 is fixed, and the jig J is removed.

Then, for example, as shown in FIG. 4D, foamed silicon is applied by a dispenser or the like to form an expansion member 7 covering the side surface 4c of the semiconductor element 4 and a part of the conductive heat dissipating member 5. Next, as shown in FIG. At this time, the expansion member 7 may be arranged so as to cover all the four sides forming the outline of the semiconductor element 4 (that is, the entire circumference of the side surface 4c). It is preferably arranged on some sides. This point will be described later.

Thereafter, as shown in FIG. 4E, for example, epoxy resin is applied by a dispenser or the like and then cured to connect the front surface 4a or the side surface 4c of the semiconductor element 4, or both, and the portion of the conductor 3 located outside the recess 31. A fixing member 6 is formed. The fixing member 6 is preferably arranged so as to cover all the four sides forming the outline of the semiconductor element 4 from the viewpoint of sealing the conductive heat dissipating material 5 in the recess 31, but is not limited to this. For example, the fixing member 6 may be arranged only in a portion different from the expansion member 7 to seal the conductive heat dissipation material 5 together with the expansion member 7, or the semiconductor element 4 and the recess 31 may be entirely covered with the sealing material 9 described later. In the case of covering, other arrangements may be used.

Subsequently, as shown in FIG. 4F, for example, a metal wire is connected to the surface 4a of the semiconductor element 4 by wire bonding or the like to form a wiring 8 electrically connecting the semiconductor element 4 and the outside.

If necessary, as shown in FIG. 4G, for example, after the wiring 8 is formed, a sealing material 9 covering the recess 31 of the conductor 3 and the semiconductor element 4 may be formed using a potting agent or the like.

The semiconductor device 1 of the present embodiment can be manufactured through the steps described above. Since the semiconductor device 1 does not use solder, the semiconductor element 4 is not exposed to a high temperature that melts the solder, and reliability and yield are improved compared to conventional semiconductor devices having solder. effect is also obtained.

[Expansion member]
Next, the effects and arrangement examples of the expansion member 7 will be described with reference to FIGS. 5 to 8. FIG.

5 to 8 show only the inner structure of the recess 31, and to make it easier to see, the outline of the semiconductor element 4 is indicated by broken lines, and the conductive heat dissipating member 5 and the fixing member 6 are omitted, and the cross section is not shown. However, the expansion member 7 is hatched. 5 to 8, for convenience of explanation, the direction in which the conductive heat dissipating material 5 is pushed in by the expansion of the expansible member 7 is indicated by a white arrow, and the flow of the conductive heat dissipating material 5 in the recess 31 is indicated by a thick arrow. .

Further, in the following description of the expansion member 7, for convenience, the terms "left", "right", "up", and "down" correspond to the directions indicated by the arrows in FIGS. 5 to 8, respectively. is.

First, an example of arrangement of the expansion member 7 will be described with reference to FIG.

The expansion member 7 is arranged on two opposing air traps 32 among the plurality of air traps 32, as shown in FIG. 5, for example. The expansion member 7 expands when the semiconductor element 4 generates heat, presses the conductive heat radiating material 5 and trapped air in the air trap 32, and increases the pressure of the air trap 32 in which the expansion member 7 is arranged. In this case, the pressure of the air traps 32 arranged along the left and right sides of the paper surface of FIG. power is generated.

As a result, as shown in FIG. 5 , the conductive heat dissipating material 5 flows upward and downward from the center of the recess 31 , pushing the conductive heat dissipating material 5 into the gap between the conductor 3 and the semiconductor element 4 in the recess 31 . part of it moves toward the air traps 32 located above and below. As a result, while suppressing the formation of a gap between the conductor 3 and the semiconductor element 4, when bubbles are generated in the conductive heat dissipating material 5, the bubbles are moved to the air trap 32 to be captured, and the conductor 3 and the semiconductor are separated. It is possible to prevent air bubbles from remaining between the element 4 and the element 4 .

Also, as shown for example in FIG. 6, the inflatable member 7 may be positioned above the two air traps 32, bottom and right. In this case, a force is generated to push the two conductive heat dissipating members 5 toward the center of the recess 31 from below and from the right, and the conductive heat dissipating member 5 is pushed into the gap between the conductor 3 and the semiconductor element 4 from the right and below while being pushed into the gap between the conductor 3 and the semiconductor element 4. flow to the top and left air traps 32 . In this manner, even when the expansion member 7 is arranged only in two adjacent air traps 32 out of the four air traps 32, the conductive heat dissipating material 5 can flow.

Alternatively, as shown in FIG. 7, the inflatable member 7 may be arranged above three air traps 32, namely left, right and bottom. In this case, a force is generated to push the three conductive heat dissipating members 5 toward the center of the concave portion 31 from the left, right, and bottom, and the conductive heat dissipating members 5 push the conductor 3 and the semiconductor element 4 from the left, right, and bottom three directions. Part of it flows into the upper air trap 32 while being pushed into the gap.

As described above, when the outline of the recessed portion 31 has a quadrilateral shape, the expansion member 7 is provided with air traps 32 along two adjacent or opposing sides among the four sides of the outline, or air traps 32 along three of the four sides of the outline. can be placed in the air trap 32 . In other words, the expansion member 7 can be placed in a state where it is not placed in the air trap 32 along at least one of the four sides of the contour of the recess 31 .

Further, the inflatable member 7 may be arranged over all the air traps 32, for example as shown in FIG. In this case, for example, by changing the constituent material, thickness, etc., a plurality of types of expansion members 7 having different expansion amounts when the semiconductor element 4 heats up are provided, and four expansion members 7 extending from the left, right, top, and bottom toward the center of the recess 31 are provided. A difference is generated in the force for pushing the conductive heat radiating material 5 . As a result, the pushing force becomes uneven, and while pushing the conductive heat-dissipating material 5 into the gap between the conductor 3 and the semiconductor element 4 in the recess 31, a part of the conductive heat-dissipating material 5 moves toward the predetermined air trap 32. occur.

In this way, from the viewpoint of allowing the conductive heat dissipating material 5 to flow within the recess 31 , it is preferable that the expansion member 7 be arranged and configured such that the force for pushing the conductive heat dissipating material 5 is uneven. This is because, when the expansion member 7 presses the conductive heat dissipating material 5 with a uniform force, when air bubbles are generated in the conductive heat dissipating material 5, the conductive heat dissipating material 5 is pushed into the gap between the conductor 3 and the semiconductor element 4 together with the air bubbles. This is because it becomes difficult for the air trap 32 to trap the air bubbles.

Note that the expansion member 7 may be arranged only on some of the air traps 32 among the plurality of air traps 32, and may have a different expansion amount, and the arrangement, configuration, etc. may be changed as appropriate. may

According to this embodiment, the semiconductor element 4 is arranged inside the contour of the recess 31 of the conductor 3, and the surface 4a and/or the side surface 4c of the semiconductor element 4 is connected and fixed to the conductor 3 by the fixing member 6. A semiconductor device in which the rear surface 4b of 4 is not fixed is obtained. Therefore, the connection area between the semiconductor element 4 and the conductor 3 is reduced, the stress applied to the semiconductor element 4 is reduced, and even if the semiconductor element 4 is thinned, breakage due to stress is suppressed. In addition, since the semiconductor element 4 is thermally connected to the conductor 3 through the conductive heat dissipating material 5 which has conductivity and becomes liquid when driven, the conductivity between the semiconductor element 4 and the conductor 3 is ensured. At the same time, the heat dissipation of the semiconductor element 4 is improved.

Furthermore, since the air trap 32 is arranged on the bottom surface of the concave portion 31 , even if air bubbles are generated in the conductive heat dissipating material 5 due to some factor such as phase transition, the air bubbles are captured by the air trap 32 . As a result, the presence of air bubbles in the gap between the back surface 4b of the semiconductor element 4 and the conductor 3 is suppressed. In addition, in the semiconductor device 1, since the expansion member 7 that expands when the semiconductor element 4 generates heat is arranged between the recess 31 and the fixing member 6, the expansion member 7 expands when the semiconductor element 4 is driven. , the liquid conductive heat dissipating material 5 is pushed out into the gap. By these actions, the semiconductor device 1 suppresses an increase in thermal resistance caused by air bubbles or voids interposed between the back surface 4b of the semiconductor element 4 and the conductor 3 when the semiconductor element 4 is driven, thereby improving heat dissipation. can be obtained.

(Second embodiment)
A semiconductor device 1 according to the second embodiment will be described with reference to FIGS. 9 and 10. FIG.

The semiconductor device 1 of the present embodiment differs from the first embodiment in that the expansion member 7 is arranged in the air trap 32 as shown in FIG. 9, for example. In this embodiment, this difference will be mainly described.

In the present embodiment, the inflatable member 7 is not fixed to the fixed member 6 but is arranged in a region directly below the air trap 32 as shown in FIG. 10, for example. The expansion member 7 can be arranged along the air trap 32, and may be configured to expand with heat generated when the semiconductor element 4 is driven. It is considered as a cylindrical tube. Also, the expansion member 7 may be a foam member containing a plurality of independent cells, such as foamed silicon, as in the first embodiment.

In the present embodiment, the expansion member 7 expands in the area immediately below the air trap 32 when the semiconductor element 4 generates heat, and increases the pressure inside the air trap 32 so that the liquid conductive heat dissipating material 5 is separated from the semiconductor element 4 and the concave portion 31 . It plays the role of pushing into the gap between

The semiconductor device 1 of this embodiment is basically manufactured by the same manufacturing process as that of the first embodiment, except for the step of arranging the expansion member 7 . The semiconductor device 1 is manufactured by, for example, placing the expansion member 7 in the air trap 32 and placing the conductive heat dissipation material 5 thereon before placing the plate-shaped conductive heat dissipation material 5 in the recess 31 . be.

According to the present embodiment, the semiconductor device 1 can obtain the same effects as those of the first embodiment. In addition, in the present embodiment, the process of arranging the expansion member 7 is simplified, and the manufacturing cost of the semiconductor device 1 can be reduced. The expansion effect of is alleviated, and an effect of further improving reliability is obtained.

(Other embodiments)
Although the present disclosure has been described with reference to examples, it is understood that the present disclosure is not limited to such examples or structures. The present disclosure also includes various modifications and modifications within the equivalent range. In addition, various combinations and configurations, as well as other combinations and configurations including only one, more, or less elements thereof, are within the scope and spirit of this disclosure.

For example, in each of the above-described embodiments, the case where the fixing member 6 hardly expands has been described as a representative example, but the fixing member 6 has a smaller amount of thermal expansion than the expansion member 7 when the semiconductor element 4 generates heat. It may be configured to have an expansion amount. In this case, the fixing member 6 also functions as the expansion member 7 , and the semiconductor device 1 substantially has a structure in which the semiconductor element 4 is fixed to the conductor 3 by the expansion member 7 .

3 Conductor 31 Recess 32 Air trap 4 Semiconductor element 4a Front surface 4b Back surface 4c Side surface 5 Conductive heat dissipation material 6 Fixing member 7 Expansion member

Claims (7)

a semiconductor element (4) having a front surface (4a) and a back surface (4b);
a conductor (3) facing the back surface and having an outer recess (31) larger than the outer shell of the semiconductor element and an air trap (32) that is a recess provided in the bottom surface of the recess;
a conductive heat dissipating material (5) disposed in the gap between the semiconductor element and the recess, being in a liquid state at least when the semiconductor element is driven, and having electrical conductivity;
a fixing member (6) arranged to connect at least one of the front surface and a side surface (4c) connecting the front surface and the back surface of the semiconductor element to the conductor and fixing the semiconductor element to the conductor;
an expansion member (7) having flexibility, disposed between the fixing member and the conductor, being in contact with the conductive heat dissipating material, and expanding due to heat generated when the semiconductor element is driven;
The semiconductor device according to claim 1, wherein the semiconductor element is arranged inside the contour of the recess and is thermally connected to the conductor through the conductive heat dissipating material. 2. The semiconductor device according to claim 1, wherein said conductive heat dissipation material is liquid metal. 3. The semiconductor device according to claim 1, wherein said air trap is arranged on said bottom surface of said recess on or outside the outline of said semiconductor element. 4. The semiconductor device according to claim 1, wherein said expansion member is arranged above said air trap. The semiconductor element has a rectangular plate shape,
The recess has an outline shape having at least four sides along the outline of the semiconductor element,
4. The semiconductor device according to claim 1, wherein said expansion member is arranged along at least two adjacent sides among four sides forming an outline of said recess. 6. The semiconductor device according to claim 5, wherein said expansion member is not arranged on at least one side of the four sides forming the contour of said recess. The recess has four or more independent air traps,
7. The semiconductor device according to claim 5, wherein said air trap extends at least along each of the four sides of said recess.

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