JP2017195290A - Substrate structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a substrate structure preventing mounting failures of an element and capable of increasing the positioning accuracy in element mounting.SOLUTION: A substrate structure 10 of the present invention includes: an element mounting surface 11S; and a plurality of element mounting pads 13 which are arranged on the element mounting surface, and each of which has a metal layer on the top surface and has, on the top surface, two sides facing each other in a direction perpendicular to the arrangement direction in an in-plane direction of the element mounting surface. On the top surface of each of the plurality of element mounting pads, a groove structure is formed, the groove structure having one or more grooves 13BG each of which has both ends reaching the two sides, respectively.SELECTED DRAWING: Figure 1A

Description

  The present invention relates to a substrate structure, and more particularly to 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 mounting, there is a problem that a defective mounting of the element occurs due to an excessive conductive adhesive, or a short circuit of the wiring occurs.

  Patent Document 1 discloses a substrate in which a solder pool including through holes or recesses is formed on a soldering pad. Patent Document 2 discloses a configuration in which a third land is formed on one of conductor patterns extending from each of two surface mounting lands to prevent solder accumulation. Patent Document 3 discloses a substrate in which a recess for storing a conductive adhesive is formed at a place where a light emitting element array is placed.

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

  An element in which a metal layer for bonding is formed at the bottom of a metal pad (land) of a substrate as described in Patent Documents 1 to 3, and the metal pad and the metal layer for bonding are reduced with a reducing agent such as a flux. Consider the case of fusion bonding via In this case, in the bonding process, there is a problem that the liquid flux flows out from the metal pad to the outside in a non-uniform manner, and the device moves accordingly.

  In addition, when a plurality of elements are juxtaposed in close proximity, there is a problem in that adjacent elements come close to each other when the fluxes used for joining adjacent elements come into contact with each other at the time of joining. there were.

  The present invention has been made in view of the above-described points, and an object of the present invention is to provide a substrate structure that can prevent defective mounting of an element and can increase positioning accuracy in mounting the element.

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

1 is a plan view of a substrate structure of Example 1. FIG. 1 is a partial side view of a substrate structure of Example 1. FIG. 1 is a side view of a substrate structure of Example 1. FIG. 3 is a partial plan view when a semiconductor element is mounted on the substrate structure of Example 1. FIG. 2 is a partial side view when a semiconductor element is mounted 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 board | substrate structure of a modification. It is a partial top view of the board | 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 denoted 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 as seen 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 an element mounting surface 11S that is a flat surface on one surface. The substrate 11 may be a substrate made of another material, a sintered body 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 to be separated from each other in the region where the semiconductor element is mounted on the element mounting surface 11S. That is, the element mounting pads 13 are arranged in a row on the element mounting surface 11S so as to be separated from each other.

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

  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 includes a base pad 13A made of a metal material such as Au or 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.

  On the upper surface of the base pad 13A, two base pad grooves 13AG which are elongated rectangular parallelepiped grooves are formed. The base pad grooves 13AG extend in parallel to each other in a direction perpendicular to the arrangement direction of the element mounting pads 13 in the in-plane direction of the element mounting surface 11S. Each end of the base pad groove 13AG is 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 two sides RS facing each other in a certain direction.

  The two base pad grooves 13AG are formed symmetrically with respect to the center line XC of the element mounting pad 13. 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, machining and grinding the upper surface of the base pad 13A. Further, the base pad groove 13AG may be formed by performing wet etching or dry etching on 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, for example, AuSn. 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 forming a metal material on the base pad 13A. Therefore, on the surface of the bonding pad 13B, that is, the upper surface of the element mounting pad 13, 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.

  As described above, the bonding pad groove 13BG has a shape derived from the base pad groove 13AG. Accordingly, the bonding pad groove 13BG is an elongated rectangular parallelepiped groove, like the base pad groove 13AG, and extends parallel to each other in a direction perpendicular to the arrangement direction of the element mounting pads 13. The bonding pad groove 13BG is formed so that each end reaches two sides RS along the arrangement direction of the element mounting pads 13 and facing each other, on the two sides of the upper surface of the element mounting pads 13. 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 symmetric with respect to the center line YC of the element mounting pad 13. That is, the groove structure composed of 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 in 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 an element mounting surface 11S immediately below both ends of one bonding pad groove 13BG, and extends perpendicularly to the arrangement direction of the element mounting pads 13 in a top view. Terminate without reaching the end of the element mounting surface 11S.

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

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

  FIG. 2 shows a partial plan view when the semiconductor element 15 is 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 part are shown. 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 is applied to the element mounting pad 13 as a flux as a reducing / fixing material. Thereafter, 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 layer 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 includes a bonding layer 15C provided on the other surface on the opposite side of the one surface of the support substrate 15A. 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 placed on the element mounting pad 13 so that the upper surface of the bonding pad 13B faces the surface of the bonding layer 15C. In the case of this mounting, when the flux FL does not spread in the bonding pad groove 13BG during the application, the flux FL may spread in the bonding pad groove 13BG during the mounting.

  When there is an excess flux FL, the excess 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 accumulates in the substrate groove 11G.

  After this placement, the substrate 11 on which the semiconductor element 15 is placed is heated in, for example, a constant temperature furnace so that the bonding pad 13B and the bonding layer 15C are eutectic. The semiconductor element 15 is fixed on the element mounting pad 13 by metal bonding. During the bonding and fixing, the bonding pad 13B is melted by heating.

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

  At this time, if there is surplus flux FL, it flows out in the direction of the broken line arrow in the figure. That is, the excess 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 a region between 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 accumulates in the substrate groove 11G. That is, the substrate groove 11G functions as a flux reservoir that accumulates 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 in this way, it can prevent that the flux which flows out from the edge part of bonding pad groove | channel 13BG flows out into area | regions other than the board | substrate groove | channel 11G of the element mounting surface 11S.

  FIG. 4 shows a partial side view of the semiconductor device 10A completed by the fixing. 4 is a side view as seen from the direction along the central axis YC of FIG. 2, as in FIG. As shown in FIG. 4, the bonding pad 13B is melted by heating when the semiconductor element 15 is fixed, the bonding pad 13 completely fills the base pad groove 13AG, and the upper surface of the bonding pad 13B becomes flat.

  Thereby, the bonding is fixed in a state in which the contact area between the bonding pad 13B and the bonding layer 15C is larger than that at the time of mounting, and a strong bonding between the bonding pad 13B and the bonding layer 15C is realized.

  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 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 increases, and the thermal resistance between the bonding pad groove 13B and the base pad 13 also decreases.

  In addition, power supply to the semiconductor element 15 in the semiconductor device 10A is appropriately performed by connecting an electrode (not shown) of the semiconductor element 15 and a power supply electrode (not shown) on the substrate 11 or outside by wire bonding or the like. It is good as well.

  As described above, when the semiconductor element 15 is mounted on the substrate 11 of this embodiment, the fluidity of the flux FL when the semiconductor element 15 is placed on the bonding pad 13 and at the initial stage of bonding and fixing by heating thereafter. Increase. The flux FL having increased fluidity flows into the substrate groove 11G via the bonding pad groove 13BG formed so as to be symmetric with respect to the center lines XC and YC, and accumulates there (indicated by the hatched portion in the figure) ).

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

  The flux FL that has flowed out from each end of the bonding pad groove 13BG flows into a separate substrate groove 11G. Therefore, fluxes flowing out from different ends of the bonding pad groove 13BG do not contact each other. Further, flux flows flowing out from adjacent element mounting pads 13 do not merge. This can prevent the flow of the flux flowing out from each of the different ends of the bonding pad groove 13BG formed symmetrically 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 is not generated, and the two between the ends of the two bonding pad grooves 13BG are not generated. In the region along the side RS, a force that prevents the semiconductor element 15 from moving is generated. Accordingly, the region along the two sides RS between the end portions of the two bonding pad grooves 13BG prevents the movement of the semiconductor element 15 and functions as a stopper for 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 for moving the semiconductor element 15 along the extending direction of the bonding pad groove 13BG cancel each other. 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 shifting 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, on the element mounting pad 13 in the present 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 accurately arranged 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. Also, the planar shape of the bonding pad groove 13BG can be variously changed.

  In the first embodiment, the bonding pad groove 13BG extends in a direction perpendicular to the arrangement direction of the element mounting pads 13. However, the bonding pad groove 13BG only needs to extend along a direction perpendicular to the arrangement direction of the element mounting pads 13 so that each end reaches each of the two sides RS on 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 bonding pad groove 13BG is changed. FIG. 5 is a diagram showing only one of the element mounting pads 13 as in FIG.

  As shown in FIG. 5, the width of the bonding pad groove 13BG may be increased as the distance from the center line XC approaches the opposite two sides RS. In this way, it is possible to smoothly flow out the excess flux FL from the element mounting pad 13 through 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 that causes the semiconductor element 15 to move relative to the element mounting pad 13.

  Thereby, it is possible to further prevent the movement of the semiconductor element 15 when the semiconductor element 15 is mounted. Accordingly, the positional accuracy when the semiconductor element 15 is mounted is further increased, 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 contacting each other, it is possible to adopt another structure.

  FIG. 6 is a partial plan view of the substrate structure 10 in which the planar shape of the substrate groove 11G is changed. 6 shows only one of the element mounting pads 13 as in FIG. 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 is the same as that of the substrate structure 10 of Example 1 except for the planar shape of the substrate groove 11G.

  In the example of FIG. 6, each of the substrate grooves 11 </ b> G has both end portions in contact with each of the two regions of the two sides RS outside the end portion of the bonding pad groove 13 </ b> BG when viewed from the center line YC. Is formed. That is, a flux accumulation region 11AR surrounded by the side surface of the element mounting pad 13 and the substrate groove 11G is formed on the element mounting surface 11S.

  In the substrate structure 10 of FIG. 6, the flux that flows out from the element mounting pad 13 through the bonding pad groove 13BG during the heating for bonding the semiconductor element 15 to the element mounting pad 13 is the flux accumulation region 11AR. To.

  Since the flux accumulation area AR is surrounded by the substrate groove 11G, the flux flowing out to the flux accumulation 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 flowing out from each of the bonding pad grooves 13BG from becoming non-uniform.

  Moreover, by doing in this way, even if more surplus flux than the case of Example 1 generate | occur | produces, it is possible to prevent the contact of the fluxes which flowed out from the other element mounting pad 13 adjacent. Therefore, an allowable error amount at the time of flux application increases, management of the flux application amount becomes easy, and as a result, the yield at the time of manufacturing the semiconductor device 10A can be improved.

  In the above-described embodiment, the configuration in which three element mounting pads 13 on which the semiconductor elements 15 are placed is arranged on one substrate 11 is described as an example. However, the element mounting pads 13 are arranged in one line. It is good also as arranging 1, 2 or 4 or more. Also, a plurality of rows of element mounting pads 13 may be formed on one substrate 11.

  In the above embodiment, the groove structure formed by 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. It was decided. However, the groove structure may not be formed symmetrically with respect to the center line XC and the center line YC.

  Moreover, in the said Example, although the case where the board | substrate groove | channel 11G was formed was demonstrated to the example, the board | substrate groove | channel 11G does not need to be formed. Even in this case, when there is 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, 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 when the semiconductor element 15 is bonded and fixed.

  Even when there is no substrate groove 11G, the excess 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 out directly to a region between adjacent element mounting pads 13 on the element mounting surface 11S. Therefore, the possibility that the fluxes flowing out from the adjacent element mounting pads 13 come into contact with each other is low, and it is possible to prevent the flux flow uniformity from being lowered.

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

  In the above 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, by eutectic crystal.

  In the above embodiment, the element mounting pads 13 are arranged on one central line XC. However, it is not necessary to arrange the element mounting pads 13 on a straight line. The element mounting pads 13 may be arranged, for example, shifted left and right in the direction perpendicular to the arrangement direction, such as a staggered arrangement.

  Various configurations, materials, and the like in the above-described embodiments are merely examples, and can be appropriately selected depending on the application, the device to be manufactured, and the like.

  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. However, 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 elements other than semiconductor elements are bonded via a flux. The substrate structure of the present invention can also be used when a semiconductor element or other elements are mounted using a type of adhesive that liquefies during adhesion fixation.

DESCRIPTION OF SYMBOLS 10 Substrate structure 10A Semiconductor device 11 Substrate 11G Substrate groove 11S Element mounting surface 11AR Flux accumulation area 13 Element mounting pad 13A Base pad 13B Bond pad 13AG Base pad groove 13BG Bond pad groove 15 Semiconductor element FL Flux

Claims (6)

An element mounting surface;
A plurality of elements arranged on the element mounting surface, each having a metal layer on the upper surface, and each having two sides facing each other in a direction perpendicular to the arrangement direction in the in-plane direction of the element mounting surface. And an element mounting pad.
A substrate structure in which a groove structure having one or a plurality of grooves each having both end portions reaching each of the two sides is formed on an upper surface of each of the plurality of element mounting pads.   2. The substrate according to claim 1, wherein the groove structure has a symmetric shape with respect to a center line of the element mounting pad perpendicular to the arrangement direction in an in-plane direction of the element mounting surface. Construction.   The substrate structure according to claim 1, wherein the groove structure has a symmetrical shape with respect to a center line along the arrangement direction of the element mounting pads.   4. The device according to claim 1, wherein each of the one or more grooves extends along a direction perpendicular to the arrangement direction in an in-plane direction of the element mounting surface. 5. Board structure.   5. The substrate structure according to claim 1, wherein the width of the one or more grooves increases as the distance from the element mounting pad increases in an in-plane direction of the element mounting surface.   On the element mounting surface, there is a substrate groove formed continuously from each of the both ends of each of the one or more grooves of the groove structure when viewed from a direction perpendicular to the element mounting surface. The substrate structure according to any one of claims 1 to 5, wherein:

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