JP6713334B2 - Board structure - Google Patents

Description

The present invention relates to a substrate structure, particularly a substrate structure on which a semiconductor element such as a light emitting element is mounted.

An electronic device having a semiconductor element is formed, for example, by mounting the semiconductor element on a substrate using a conductive adhesive such as solder. At the time of this mounting, there is a problem in that the mounting failure of the element may occur due to the surplus conductive adhesive, or a short circuit of the wiring may occur.

Patent Document 1 discloses a substrate in which a soldering pad including a through hole or a recess is formed in a soldering pad. Further, Patent Document 2 discloses a configuration in which a third land is formed on one of the conductor patterns extending from each of the two surface mounting lands to prevent a solder pool. Patent Document 3 discloses a substrate in which a recess for accumulating a conductive adhesive is formed at a mounting position of a light emitting element array.

JP-A-4-87393 JP-A-5-267833 JP, 9-174923, A

An element in which a metal layer for bonding is formed on the bottom of a metal pad (land) of a substrate as described in Patent Documents 1 to 3 is used as a reducing agent such as a flux between the metal pad and the metal layer for bonding. Consider the case of fusion bonding via. In this case, in the joining process, the liquid flux flows out of the metal pad unevenly outwardly, and the element moves accordingly, so that the mounting accuracy of the element is deteriorated.

Further, when a plurality of elements are juxtaposed close to each other, at the time of joining, there is a problem that adjacent elements come close to each other because the fluxes used for joining adjacent elements come into contact with each other and become integrated. there were.

The present invention has been made in view of the above points, and an object of the present invention is to provide a substrate structure capable of preventing a mounting defect of an element and improving positioning accuracy when mounting the element.

In order to achieve the above-mentioned object, the substrate structure of the present invention has an element mounting surface and an array on the element mounting surface, has a metal layer on the upper surface, and has an in-plane surface of the element mounting surface on the upper surface. A plurality of element mounting pads having two sides facing each other in a direction perpendicular to the arrangement direction in the direction, and both ends of the plurality of element mounting pads on each of the two sides. A groove structure having one or a plurality of grooves reaching the groove structure is formed.

3 is a plan view of the substrate structure of Example 1. FIG. 3 is a partial side view of the substrate structure of Example 1. FIG. 4 is a side view of the substrate structure of Example 1. FIG. 4 is a partial plan view of when mounting a semiconductor element on the substrate structure of Example 1. FIG. 5 is a partial side view when mounting a semiconductor element on the substrate structure of Example 1. FIG. It is a partial side view of a semiconductor device. It is a partial top view of the substrate structure of a modification. It is a partial top view of the substrate structure of a modification.

Hereinafter, preferred embodiments of the present invention will be described in detail. In the following description and the accompanying drawings, substantially the same or equivalent parts are designated by the same reference numerals.

[Substrate structure]
FIG. 1A is a plan view of the substrate structure 10. FIG. 1B is a partial side view of the substrate structure 10. FIG. 1C is a side view of the substrate structure 10 viewed from a different direction than FIG. 1B. In the following description, a substrate structure in which three semiconductor elements are arranged in a row on one substrate will be described as an example.

The substrate 11 is a Si substrate having a flat element mounting surface 11S on one surface. The substrate 11 may be a substrate made of another material, a sintered substrate such as AlN, or a resin substrate.

The element mounting pad 13 is provided on the element mounting surface 11S and has a rectangular planar shape. The element mounting pads 13 are formed so as to be separated from each other in each of the regions of the element mounting surface 11S where the semiconductor element is mounted. That is, the element mounting pads 13 are arranged in a line on the element mounting surface 11S so as to be separated from each other.

The center line of each of the element mounting pads 13 along the arrangement direction of the element mounting pads 13 is XC. In this embodiment, as an example, the element mounting pads 13 are arranged in a straight line, and the center line XC of the three element mounting pads 13 is common. Further, the center line of each of the element mounting pads 13 in the direction perpendicular to the arrangement direction of the element mounting pads 13 is YC. Further, in this embodiment, the case where three semiconductor elements are arranged in a row as described above is taken as an example, so that the element mounting pads 13 are also arranged in three rows.

FIG. 1B shows a side view seen from the direction along the center line YC. In FIG. 1B, among the three element mounting pads 13, the central element mounting pad 13 and its periphery are shown in an enlarged manner. As shown in FIG. 1B, the element mounting pad 13 has a base pad 13A made of a metal material such as Au and Cu, and a bonding pad 13B formed on the base pad 13A. The base pad 13A is formed by depositing a metal material such as Au or Cu on the element mounting surface 11S by patterning by photolithography or the like.

Two base pad grooves 13AG, which are elongated rectangular parallelepiped grooves, are formed on the upper surface of the base pad 13A. The base pad grooves 13AG extend in parallel to each other in the direction perpendicular to the arrangement direction of the element mounting pads 13 in the in-plane direction of the element mounting surface 11S. The base pad groove 13AG has two ends on the two sides of the upper surface of the element mounting pad 13, along the arrangement direction of the element mounting pad 13, and perpendicular to the arrangement direction in the in-plane direction of the element mounting surface 11S. It is formed so as to reach up to two sides RS facing each other in different directions.

The two base pad grooves 13AG are formed symmetrically with respect to the center line XC of the element mounting pad 13. Further, the two base pad grooves 13AG are formed symmetrically with respect to the center line YC of the element mounting pad 13.

The base pad groove 13AG is formed by, for example, mechanically grinding the upper surface of the base pad 13A. The base pad groove 13AG may be formed by wet etching or dry etching the upper surface of the base pad groove 13A.

The bonding pad 13B is a layer made of a metal material formed on the base pad 13A. The bonding pad 13B is made of AuSn, for example. The bonding pad 13B is formed by depositing a metal material such as AuSn on the base pad 13A by patterning by photolithography or the like.

The bonding pad 13B is formed by uniformly depositing a metal material on the base pad 13A. Therefore, two bonding pad grooves 13BG as a groove structure having a shape derived from the base pad groove 13AG on the upper surface of the base pad 13A are formed on the surface of the bond pad 13B, that is, the upper surface of the element mounting pad 13.

As described above, the bonding pad groove 13BG has a shape derived from the base pad groove 13AG. Therefore, the bonding pad groove 13BG is an elongated rectangular parallelepiped groove, like the base pad groove 13AG, and extends parallel to each other in the direction perpendicular to the arrangement direction of the element mounting pads 13. Further, the bonding pad groove 13BG is formed so that each end reaches two sides of the upper surface of the element mounting pad 13, which are along the arrangement direction of the element mounting pad 13 and are opposite to each other RS. ing.

The two bonding pad grooves 13BG are formed symmetrically with respect to the center line XC of the element mounting pad 13. The two bonding pad grooves 13BG are formed so as to be symmetrical with respect to the center line YC of the element mounting pad 13. That is, the groove structure including the two bonding pad grooves 13BG formed on the surface (upper surface) of the element mounting pad 13 is formed symmetrically with respect to the center line XC and the center line YC.

The substrate groove 11G is a groove formed on the element mounting surface 11S of the substrate 11. The substrate groove 11G is viewed from a direction perpendicular to the element mounting surface 11S (hereinafter, also referred to as “in top view”),
The bonding pad groove 13BG continuously extends from both ends of the bonding pad groove 13BG. The substrate groove 11G extends from the two sides RS in a direction perpendicular to the arrangement direction of the element mounting pads 13.

FIG. 1C shows a side view seen from the direction along the center line XC. As shown in FIG. 1C, the substrate groove 11G is formed from the element mounting surface 11S immediately below both ends of one bonding pad groove 13BG, and extends in a direction perpendicular to the arrangement direction of the element mounting pads 13 in a top view, The element mounting surface 11S is terminated without reaching the end portion.

The width W1 of the substrate groove 11G is preferably larger than the width W2 of the bonding pad groove 13BG immediately below the bonding pad groove 13BG. This is to prevent the flux flowing out from the end portion of the bonding pad groove 13BG from flowing out to a region other than the substrate groove 11G of the element mounting surface 11S in the manufacturing of a semiconductor device described later.

[Semiconductor device and manufacturing thereof]
Hereinafter, a semiconductor device 10A manufactured by mounting a semiconductor element such as a light emitting element on the substrate 11 and manufacturing thereof will be described.

FIG. 2 shows a partial plan view of the semiconductor element 15 placed on the substrate 11. In this plan view, only one of the three element mounting pads 13 shown in FIG. 1A and its peripheral portion are shown. Further, FIG. 3 shows a side view of the substrate 11 and the semiconductor element 15 as seen from the direction along the central axis YC of FIG.

As shown in FIGS. 2 and 3, when mounting the semiconductor element 15 on the substrate 11, first, FL, which is a liquid serving as a reducing/fixing material, is applied onto the element mounting pad 13. Then, the semiconductor element 15 is mounted on the applied flux FL using a die bonder or the like.

As shown in FIG. 3, the semiconductor element 15 has a support substrate 15A made of Si or the like, and a semiconductor layer 15B having an active layer (not shown) formed on one surface of the support substrate 15A. The semiconductor element 15 further has a bonding layer 15C provided on the other surface of the support substrate 15A opposite to the one surface. The bonding layer 15C is formed of a metal eutectic with the metal forming the bonding pad 13B, such as Au or AuSn. The bonding layer 15C has the same planar shape as the bonding pad 13B.

The semiconductor element 15 is mounted on the element mounting pad 13 such that the upper surface of the bonding pad 13B and the surface of the bonding layer 15C face each other. In this mounting, if the flux FL is not spread in the bonding pad groove 13BG at the time of application, the flux FL may be spread in the bonding pad groove 13BG in this mounting.

In addition, when there is a surplus flux FL, the surplus flux FL is pushed out from the bonding pad groove 13BG toward the side surface of the element mounting pad 13. The extruded flux FL flows along the side surface of the element mounting pad 13 into the substrate groove 11G and is accumulated in the substrate groove 11G.

After this placement, the substrate 11 on which the semiconductor element 15 is placed is placed in, for example, a constant temperature oven and heated to eutecticize the bonding pad 13B and the bonding layer 15C. The semiconductor element 15 is fixed onto the element mounting pad 13 by metal bonding. At the time of this joining and fixing, the joining pad 13B is melted by heating.

In the initial stage before the melting of the bonding pad 13B at the time of bonding and fixing by heating, the flux FL applied on the bonding pad 13B is melted and further spreads to the surface of the bonding pad 13B including the bonding pad groove 13BG.

At this time, if there is a surplus flux FL, it flows out in the direction of the broken line arrow in the figure. That is, the surplus flux is pushed out from the bonding pad groove 13BG toward the side surface along the two sides RS of the element mounting pad 13. In other words, the surplus flux does not flow out to the region between the adjacent element mounting pads 13 on the element mounting surface 11S.

The extruded flux FL flows along the side surface of the element mounting pad 13 into the substrate groove 11G and is accumulated in the substrate groove 11G. That is, the substrate groove 11G functions as a flux pool that stores the extruded flux FL.

As described above, the width W1 of the substrate groove 11G is preferably larger than the width W2 of the bonding pad groove 13BG immediately below the bonding pad groove 13BG (see FIG. 2). By doing so, it is possible to prevent the flux flowing out from the end portion of the bonding pad groove 13BG from flowing out to a region other than the substrate groove 11G of the element mounting surface 11S.

FIG. 4 shows a partial side view of the semiconductor device 10A completed by the fixing. Similar to FIG. 3, FIG. 4 is a side view as seen from the direction along the central axis YC of FIG. As shown in FIG. 4, the bonding pad 13B is melted by the heating when fixing the semiconductor element 15, the bonding pad 13 completely fills the base pad groove 13AG, and the upper surface of the bonding pad 13B becomes flat.

As a result, the bonding pad 13B and the bonding layer 15C are bonded and fixed to each other in a state where the contact area between the bonding pad 13B and the bonding layer 15C is larger than that at the time of mounting, and the bonding pad 13B and the bonding layer 15C are strongly bonded.

Further, since the base pad groove 13AG is formed in the base pad 13A, the contact area between the bonding pad 13B and the base pad groove 13AG is larger than that when the upper surface of the base pad 13AG is flat. As a result, the bonding strength between the bonding pad 13B and the base pad groove 13A becomes high, and the thermal resistance between the bonding pad groove 13B and the base pad 13 also becomes low.

The power supply to the semiconductor element 15 in the semiconductor device 10A is appropriately performed by connecting the electrode (not shown) of the semiconductor element 15 and the power supply electrode (not shown) on the substrate 11 or outside by wire bonding or the like. It may be that.

As described above, when the semiconductor element 15 is mounted on the substrate 11 of the present embodiment, the fluidity of the flux FL is high when the semiconductor element 15 is mounted on the bonding pad 13 and at the initial stage of the subsequent bonding and fixing by heating. Will increase. The flux FL with increased fluidity flows into the substrate groove 11G through the bonding pad groove 13BG formed symmetrically with respect to the center lines XC and YC, and accumulates therein (shown by the hatched portion in the figure). ).

That is, the flux FL uniformly flows into the substrate groove 11G from the bonding pad grooves 13BG formed symmetrically on the element mounting pad 13. At this time, the flux FL flowing from the element mounting pad 13 into each of the substrate grooves 11G generates a force that moves the semiconductor element 15 in the direction along the extension direction of the bonding pad groove 13BG. At this time, the flux FL does not flow out from a portion other than the end portion of the bonding pad groove 13BG.

The flux FL flowing out from each of the end portions of the bonding pad groove 13BG flows into the separate substrate groove 11G. Therefore, the fluxes flowing out from the different ends of the bonding pad groove 13BG do not come into contact with each other. Further, the flux flows flowing out from the adjacent element mounting pads 13 do not join together. This can prevent the flow of flux flowing out from each of the different ends of the symmetrically formed bond pad grooves 13BG from becoming uneven.

That is, the flux FL flowing out from the region along the two sides RS (see FIG. 1) between the ends of the two bonding pad grooves 13BG does not occur, and the flux between the two ends of the two bonding pad grooves 13BG does not occur. In the region along the side RS, a force that prevents the movement of the semiconductor element 15 is generated. Therefore, the region along the two sides RS between the ends of the two bonding pad grooves 13BG hinders the movement of the semiconductor element 15 and functions as a stopper against the movement of the semiconductor element 15.

Further, since the bonding pad groove 13BG is formed symmetrically with respect to the center line YC of the element mounting pad 13, the forces that move the semiconductor element 15 along the extending direction of the bonding pad groove 13BG cancel each other out. Therefore, when the semiconductor element 15 is mounted on the substrate 11, that is, when the semiconductor element 15 is bonded and fixed by heating, the semiconductor element 15 is fixed on the element mounting pad 13 without being displaced from the upper surface of the element mounting pad 13. In other words, the semiconductor element 15 can be accurately arranged at a predetermined position, that is, the element mounting pad 13 in this embodiment.

As described above, according to the substrate structure 10 of the first embodiment, the semiconductor element 15 can be accurately arranged at a desired position. Therefore, when a large number of semiconductor elements 15 are arranged on the substrate 11, the semiconductor elements 15 can be arranged accurately and at a high density, and the degree of integration of the semiconductor device can be increased.
[Other Examples]
In the first embodiment, the case where two bonding pad grooves 13BG are formed on one element mounting pad 13 has been described as an example. However, one or three or more bonding pad grooves 13BG may be formed on one element mounting pad 13. Further, the planar shape of the bonding pad groove 13BG can be variously changed.

Further, in the first embodiment, the case where the bonding pad groove 13BG extends in the direction perpendicular to the arrangement direction of the element mounting pads 13 is shown. However, the bonding pad groove 13BG may be extended along the direction perpendicular to the arrangement direction of the element mounting pads 13 so that each end reaches each of the two sides RS of the upper surface of the element mounting pad 13.

FIG. 5 is a partial plan view of the substrate structure 10 in which the planar shape of each of the bonding pad grooves 13BG is changed. Note that FIG. 5 is a diagram showing only one of the element mounting pads 13 as in FIG. 2.

As shown in FIG. 5, the width of the bonding pad groove 13BG may be increased as the distance from the center line XC to the opposing two sides RS is increased. By doing so, it becomes possible to smoothly flow out the surplus flux FL from above the element mounting pad 13 via the bonding pad groove 13BG. That is, it is possible to further reduce the non-uniformity of the flow of the flux FL in the bonding pad groove 13BG and further reduce the force for moving the semiconductor element 15 to the element mounting pad 13 to the moving pad 13.

This makes it possible to further prevent the semiconductor element 15 from moving when the semiconductor element 15 is mounted. Therefore, the positional accuracy when the semiconductor element 15 is mounted is further enhanced, and the semiconductor element can be highly integrated in the semiconductor device.

In the above embodiment, the case where the substrate groove 11G is formed from the element mounting surface 11S immediately below both ends of one bonding pad groove 13BG and functions as a flux reservoir has been described. However, in order to prevent the fluxes FL flowing out from the adjacent element mounting pads 13 from coming into contact with each other, another structure may be adopted.

FIG. 6 is a partial plan view of the substrate structure 10 in which the planar shape of the substrate groove 11G is changed. Note that FIG. 6 is a diagram showing only one of the element mounting pads 13 as in FIG. 2. In the example of FIG. 6, a flux pool region 11AR as a flux pool surrounded by the substrate groove 11G is formed on the element mounting surface 11S. The substrate structure 10 is the same as that of the substrate structure 10 of the first embodiment except the planar shape of the substrate groove 11G.

In the example of FIG. 6, each of the substrate grooves 11G is in contact with each of the two regions of the two sides RS outside the ends of the bonding pad grooves 13BG when viewed from the center line YC in a top view. Has been formed. That is, the flux pool region 11AR surrounded by the side surface of the device mounting pad 13 and the substrate groove 11G is formed on the device mounting surface 11S.

In the substrate structure 10 shown in FIG. 6, when the semiconductor element 15 is heated to be bonded and fixed to the element mounting pad 13, the flux flowing out from the element mounting pad 13 through the bonding pad groove 13BG is the flux pool area 11AR. Leading to.

Since the flux pool area AR is surrounded by the substrate groove 11G, the flux flowing out to the flux pool area 11AR does not flow outside the substrate groove 11G. Therefore, it is possible to prevent the flux flowing out from one element mounting pad 13 from coming into contact with the flux flowing out from another adjacent element mounting pad 13. This can prevent the flux from flowing out of each of the bonding pad grooves 13BG from becoming non-uniform.

Further, by doing so, it is possible to prevent contact between the fluxes flowing out from other adjacent element mounting pads 13 even if a larger amount of surplus flux is generated than in the case of the first embodiment. Therefore, the allowable error amount at the time of applying the flux becomes large, the management of the amount of applying the flux becomes easy, and the yield at the time of manufacturing the semiconductor device 10A can be improved.

Further, in the above-described embodiments, the configuration in which the three element mounting pads 13 on which the semiconductor elements 15 are mounted are arranged in one row on the one substrate 11 has been described as an example, but the element mounting pads 13 are arranged in one row. One, two, or four or more may be arranged. Further, a plurality of rows of element mounting pads 13 may be formed on one substrate 11.

Further, in the above-described embodiment, the groove structure including the two bonding pad grooves 13BG formed on the surface (upper surface) of the element mounting pad 13 is formed symmetrically with respect to the center line XC and the center line YC. I decided. However, the groove structure may not be formed symmetrically with respect to the center line XC and the center line YC.

Further, in the above embodiment, the case where the substrate groove 11G is formed has been described as an example, but the substrate groove 11G may not be formed. Even in this case, when there is a surplus flux FL, the flux flows out evenly from each of the bonding pad grooves 13BG to the element mounting surface 11S in the direction of the broken line arrow in FIG. Therefore, when the semiconductor element 15 is bonded and fixed, it is possible to prevent the semiconductor element 15 from moving with respect to the element mounting pad 13 due to the flow of flux.

Further, even when the substrate groove 11G is not provided, the surplus flux is pushed out from the bonding pad groove 13BG toward the side surface of the element mounting pad 13 along the two sides RS. In other words, the surplus flux does not flow directly to the region between the adjacent element mounting pads 13 on the element mounting surface 11S. Therefore, the fluxes flowing out from the adjacent element mounting pads 13 are unlikely to come into contact with each other, and it is possible to prevent the uniformity of the flux flow from being deteriorated.

Further, the planar shapes of the bonding pad groove 13BG and the substrate groove 11G in the above-described embodiments and modifications can be combined as appropriate.

Further, in the above-described embodiment, the bonding pad 13 is made of AuSn and the bonding layer 15C is made of Au or AuSn. However, the bonding pad 13 and the bonding layer 15C may be formed of other materials as long as they can be bonded to each other by heating, for example, eutectic.

Further, in the above embodiment, the element mounting pads 13 are arranged on the center line XC of one straight line. However, the element mounting pads 13 do not have to be arranged on a straight line. The element mounting pads 13 may be arranged, for example, in a staggered arrangement, with left and right shifting in the direction perpendicular to the arrangement direction.

The various configurations, materials, and the like in the above-described embodiments are merely examples, and can be appropriately selected according to the application, the manufactured device, and the like.

Further, in the above-described embodiments, the substrate structure and the semiconductor device in which the semiconductor element is mounted on the substrate structure have been described, but the substrate structure of the present invention can be applied to other than the semiconductor device. That is, the substrate structure of the present invention can also be used when joining elements other than semiconductor elements via flux. The substrate structure of the present invention can also be used when a semiconductor element or other elements are mounted by using an adhesive of a type that is liquefied at the time of bonding and fixing.

10 Substrate Structure 10A Semiconductor Device 11 Substrate 11G Substrate Groove 11S Element Mounting Surface 11AR Flux Reservoir Area 13 Element Mounting Pad 13A Base Pad 13B Bonding Pad 13AG Base Pad Groove 13BG Bonding Pad Groove 15 Semiconductor Device FL Flux

Claims (6)

Element mounting surface,
A plurality of elements arranged on the element mounting surface, having a metal layer on the upper surface, and having two sides on the upper surface, each side facing each other in the direction perpendicular to the arrangement direction in the in-plane direction of the element mounting surface. The element mounting pad of
A groove structure having one or a plurality of grooves whose both ends reach each of the two sides is formed on the upper surface of each of the plurality of element mounting pads .
A substrate structure , wherein the width of the one or more grooves widens with increasing distance from the element mounting pad in the in-plane direction of the element mounting surface . Element mounting surface,
A plurality of elements arranged on the element mounting surface, having a metal layer on the top surface, and having two sides on the top surface, each side facing each other in the direction perpendicular to the arrangement direction in the in-plane direction of the element mounting surface. The element mounting pad of
A groove structure having one or a plurality of grooves whose both ends reach each of the two sides is formed on the upper surface of each of the plurality of element mounting pads.
On the element mounting surface, there is provided a substrate groove formed continuously from each of the both end portions of each of the one or more grooves of the groove structure when viewed from a direction perpendicular to the element mounting surface. Substrate structure characterized in that The width at each of the both ends of each of the one or more grooves is smaller than the width of the substrate groove at each of the ends of the substrate groove facing each of the both ends. The described substrate structure. 4. The groove structure has a shape symmetrical with respect to a center line of the device mounting pad perpendicular to the array direction in the in-plane direction of the device mounting surface. The substrate structure according to any one of the above. The substrate structure according to claim 1 , wherein the groove structure has a shape symmetrical with respect to a center line along the arrangement direction of the element mounting pads . The each of the one or a plurality of grooves extends along a direction perpendicular to the arrangement direction in an in-plane direction of the element mounting surface . Substrate structure.

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