JP2015103746A - Wiring board and semiconductor device comprising the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a wiring board capable of suppressing electromigration.SOLUTION: A wiring board comprises: an insulating substrate 1 having a mounting portion of a semiconductor element 9 on one main surface and having a through conductor 2 formed to penetrate the one main surface and the other main surface; a wiring conductor layer 3 which is electrically connected to the through conductor 2 and provided on the other main surface side so that the outer periphery of the wiring conductor layer 3 is positioned outside the outer periphery of an end surface of the through conductor 2 in a planar view; a barrier layer 4 provided so as to overlap and be in contact with the wiring conductor layer 3; and a solder joint layer 5 which is joined to a solder bump 6 and provided so as to overlap the barrier layer 4 in a planar view.

Description

  The present invention includes, for example, a wiring board having a mounting portion for a semiconductor element such as an electronic component element on the upper surface, a wiring conductor layer on the lower surface side, and electrically connected to a circuit board or the like via a solder bump. The present invention relates to a semiconductor device or the like in which a semiconductor element is mounted on a wiring board.

  In the wiring board, for example, a connection pad corresponding to the arrangement of electrodes of a semiconductor element such as an electronic component element is formed on the main surface (upper surface) of an insulating substrate such as a ceramic substrate, and the other main surface (lower surface). In this structure, a wiring conductor layer corresponding to the arrangement of electrode patterns on a circuit board (for example, a printed board) is formed. In addition, the connection pad and the wiring conductor layer are electrically connected to the end faces of the through conductors provided so as to penetrate the upper and lower surfaces of the insulating substrate.

  2. Description of the Related Art A semiconductor device is composed of a circuit board on which a semiconductor element is mounted on a wiring board and provided on the lower surface of the wiring board. For example, the wiring board and the semiconductor element are bonded to each other with the electrodes of the semiconductor element and the connection pads of the wiring board facing each other with gold bumps interposed therebetween. In addition, the wiring board and the circuit board are bonded to each other with, for example, the wiring conductor layer of the wiring board and the electrode pattern of the circuit board facing each other and a solder (solder bump) interposed therebetween. The solder bump is made of a solder material such as tin-silver-copper or tin-silver-bismuth. In this way, a semiconductor device is formed.

  As described above, the semiconductor device is mounted on the circuit board, and currents as various signals are passed from the electric circuit of the circuit board to the electrodes of the semiconductor element through the solder bump, the wiring conductor layer, the through conductor, the connection pad, and the bump. Energized. In addition, currents as various signals are passed from the electrodes of the semiconductor element to the bumps, connection pads, through conductors, wiring conductor layers, solder bumps, and electric circuits of the circuit board. An example of such a semiconductor device is disclosed in Patent Document 1.

JP 2001-168224 A

  However, in the above-described prior art wiring board, when the electrode pattern of the circuit board is joined to the wiring conductor layer via solder (solder bump) and energized, voids (voids) are formed on the joint surface between the wiring conductor layer and the solder. ) May occur.

  This is because the current flowing from the electrode pattern on the circuit board to the solder bumps tends to concentrate on the area of the wiring conductor layer where the through conductor is connected in plan view. Since the current density tends to be high in the area of the wiring conductor layer where the through conductor is connected in plan view, the metal material such as copper forming the wiring conductor layer in this area causes electromigration and is partially soldered. It diffuses in the bump and creates a void. When such a gap due to electromigration occurs, problems such as local increase in electrical resistance and disconnection occur between the wiring conductor layer and the solder bump.

In particular, with the recent increase in the speed of semiconductor elements, the current flowing from the external electric circuit to the solder bumps and the wiring conductor layer tends to increase further. Therefore, the increase in the current density is remarkable, and the gap due to electromigration is further increased. It is becoming easier to occur.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a wiring substrate and a semiconductor device that can suppress electromigration by providing a barrier layer so as to cover the wiring conductor layer. There is to do.

  A wiring board according to an aspect of the present invention has a semiconductor element mounting portion on one main surface and an insulating substrate having a through conductor formed through the one main surface and the other main surface; A wiring conductor layer electrically connected to the penetrating conductor, provided on the other main surface side so that an outer periphery thereof is located outside an outer periphery of an end surface of the penetrating conductor in plan view; and the wiring conductor layer And a solder bonding layer that is provided so as to overlap with the barrier layer in a plan view and is bonded to the solder bump.

  A semiconductor device according to an aspect of the present invention includes a wiring board according to the present invention, a semiconductor element mounted on the mounting portion on the one main surface, and a solder bump on the solder bonding layer. And a circuit board connected to the circuit board.

  According to the wiring board of the present invention, the electromigration can be suppressed by providing the barrier layer so as to cover the wiring conductor layer.

It is sectional drawing of the semiconductor device containing the wiring board which concerns on embodiment of this invention. 1A is a plan view of an insulating substrate when the insulating substrate of the wiring substrate shown in FIG. 1 is viewed from above, and FIG. 1B is a plan view of the insulating substrate when the wiring substrate shown in FIG. 1 is viewed from below. (A) is an enlarged view of the main part A of the part including the solder bumps of the wiring board shown in FIG. 1, (b) is a plan view of the main part A as viewed from below, and (c) is the wiring board. It is explanatory drawing for demonstrating electromigration. It is sectional drawing of the semiconductor device containing the wiring board of the other example of the wiring board of embodiment of this invention. It is an enlarged view of the principal part B of the part containing the solder bump of the wiring board shown in FIG. It is sectional drawing of the semiconductor device containing the wiring board of the other example of the wiring board of embodiment of this invention. It is an enlarged view of the principal part C of the part containing the solder bump of the wiring board shown in FIG. It is sectional drawing of the semiconductor device containing the wiring board of the wiring board of other embodiment of this invention. (A) is an enlarged view of the principal part D of the part containing the solder bump of the wiring board shown in FIG. 8, (b) is a schematic diagram for demonstrating a wiring conductor layer.

  Hereinafter, a wiring board and a semiconductor device according to embodiments of the present invention will be described with reference to the drawings. Note that the drawings used in the following description are schematic, and the dimensional ratios and the like on the drawings do not necessarily match the actual ones. Further, for convenience of explanation, the semiconductor device defines an orthogonal coordinate system XYZ and uses the word “upper surface” or “lower surface” with the positive side in the Z direction as the upper side.

  In the description of the embodiments and the like, components that are the same as or similar to the components that have already been described may be assigned the same reference numerals and descriptions thereof may be omitted.

<Embodiment 1>
A wiring board 20 and a semiconductor device according to a first embodiment (referred to as the first embodiment) of the present invention will be described below with reference to FIGS. The semiconductor device has a semiconductor element 9 mounted on a wiring board. The semiconductor element 9 is, for example, a light emitting diode or an integrated circuit.

  The wiring substrate 20 according to the embodiment has a configuration as shown in FIG. 1 and has a mounting portion for the semiconductor element 9 on one main surface and penetrates one main surface and the other main surface. The insulating substrate 1 having the formed through conductor 2 and the other main surface side so that the outer periphery is located outside the outer periphery of the end surface of the through conductor 2 in plan view, which is electrically connected to the through conductor 2. Solder joint that is joined to the solder bumps 6 that are provided so as to overlap the barrier layer 4 in plan view, and the barrier layer 4 that is provided so as to overlap and contact the wiring conductor layer 3. Layer 5. In the present embodiment, the upper surface of the insulating substrate 1 is one main surface, and the lower surface of the insulating substrate 1 is the other main surface.

  The wiring substrate 20 is for manufacturing a semiconductor device by mounting the semiconductor element 8 and is made of an insulating material. The wiring board is, for example, a ceramic material such as a glass ceramic sintered body, an aluminum oxide sintered body, a mullite sintered body, or an aluminum nitride sintered body, or a resin material such as an epoxy resin or a polyimide resin. Further, it may be a composite material of a ceramic material or a glass material or the like and a resin material.

  The wiring board 20 has the insulating substrate 1 formed of these insulating materials, and has a through conductor 2 formed through one main surface and the other main surface of the insulating substrate 1. That is, the through conductor 2 penetrates the upper and lower surfaces of the insulating substrate 1. As shown in FIG. 2A, the wiring board has, for example, a rectangular plate shape, and a region such as a square shape including a central portion of the upper surface (one main surface) of the insulating substrate 1 is a mounting portion of the semiconductor element 9. In this mounting portion, the connection pad 7 is formed so as to be opposed to the electrode 10 of the semiconductor element 9. As shown in FIG. 2A, the insulating substrate 1 is, for example, a rectangular plate-like body. However, the insulating substrate 1 is not limited to this, and a circular or elliptical plate-like body, or a polygonal shape other than a rectangular shape. It may be a plate-like body. 2B is a plan view of the insulating substrate 1 when the wiring substrate 1 including the wiring conductor layer 3 is viewed from below, and the through conductor 2 is provided on the wiring conductor layer 3 provided on the lower surface of the insulating substrate 1. FIG. Indicates the position.

  The wiring substrate 20 is provided so that one end surface of the through conductor 2 is exposed on the upper surface (one main surface) of the insulating substrate 1 and covers the end surface of the through conductor 2 where the connection pad 7 is exposed. Yes. The connection pad 7 is electrically connected to the plurality of electrodes 10 of the semiconductor element 9 through the bumps 8. 2A is a plan view of the insulating substrate 1 when the wiring substrate 1 including the connection pads 7 is viewed from above, and the through conductors 2 and the bumps 8 are connected to the connection pads 7 provided on the upper surface of the insulating substrate 1. FIG. Each position is shown.

  In the wiring board 20, the through conductor 2 is formed from the mounting portion of the insulating substrate 1 to the inside of the insulating substrate 1, and the connection pad 7 is electrically connected to the semiconductor element 9. It is electrically connected to the electrode pattern 12 of the circuit board 11 via That is, the through conductor 2 serves as a conductive path for electrically connecting the connection pad 7 electrically connected to the semiconductor element 9 and the electrode pattern 12 of the circuit board 11.

One end surface of the through conductor 2 is exposed on the upper surface (one main surface) of the insulating substrate 1, and the exposed end surface of the through conductor 2 is electrically connected to the connection pad 7. The other end surface of the through conductor 2 is exposed on the lower surface (the other main surface) of the insulating substrate 1, and the exposed end surface of the through conductor 2 is electrically connected to the wiring conductor layer 3. In this way, the through conductor 2 electrically connects the connection pad 7 on the upper surface of the insulating substrate 1 and the wiring conductor layer 3 on the lower surface.

  The through conductor 2 has, for example, a circular shape with a diameter of, for example, 30 (μm) to 300 (μm) in plan view, and is provided inside the insulating substrate 1 in a cylindrical shape. The through conductor 2 is made of, for example, a metal material such as copper, silver, tungsten, or molybdenum. In particular, when the through conductor 2 is copper or silver, the electrical resistance of copper or silver is low. Electrical resistance can be kept low.

  Further, as shown in FIG. 2A, the through conductor 2 has an end surface exposed from one main surface of the insulating substrate 1 in a plan view at the lower end (negative side in the Y direction) of the connection pad 7. It is connected. That is, in FIG. 2A, the through conductor 2 is electrically connected to the connection pad 7 in the lower region (negative side in the Y direction) of the connection pad 7. The connection position between the end surface of the through conductor 2 and the connection pad 7 in a plan view is not limited to the end portion of the connection pad 7 but may be a central portion of the connection pad 7. It is appropriately set so that the end face of the through conductor 2 is provided in the region. As long as the through conductor 2 and the connection pad 7 are electrically connected, a part of the through conductor 2 may protrude outside the outer periphery of the connection pad 7.

  Further, as shown in FIG. 2B, the through conductor 2 has an end surface exposed from the other main surface of the insulating substrate 1 in a plan view, an end portion on the lower side (negative side in the Y direction) of the wiring conductor layer 3. Connected with. That is, in FIG. 2B, the through conductor 2 is electrically connected to the wiring conductor layer 3 in a region below the wiring conductor layer 3 (negative side in the Y direction). The connection position between the end surface of the through conductor 2 and the wiring conductor layer 3 in a plan view is not limited to the end portion of the wiring conductor layer 3 but may be the central portion of the wiring conductor layer 3. 3 is set as appropriate so that the end face of the through conductor 2 is provided in the region inside 3. As long as the through conductor 2 and the wiring conductor layer 3 are electrically connected, a part of the through conductor 2 may protrude outside the outer periphery of the wiring conductor layer 3.

  A plurality of through conductors 2 may be connected to one connection pad 7 or one wiring conductor layer 3. Further, the through conductor 2 is not limited to a circular shape in plan view, and may be an elliptical shape or a quadrangular shape. The shape of the through conductor 2 in plan view is not particularly limited as long as the connection pad 7 and the wiring conductor layer 3 can be electrically connected.

  2B, the other end surface of the through conductor 2 is exposed on the lower surface (the other main surface) of the insulating substrate 1, and the wiring conductor layer 3 is the end surface of the through conductor 2. Is provided on the lower surface (the other main surface) of the insulating substrate 1. The wiring conductor layer 3 is electrically connected to the through conductor 2 and is provided so that the outer periphery thereof is located outside the outer periphery of the end face of the through conductor 2 in plan view. Thus, the wiring board 20 is provided on the other main surface of the insulating substrate 1 so that the wiring conductor layer 3 covers the other end surface of the through conductor 2 exposed from the other main surface of the insulating substrate 1 in plan view. It has been.

  In the semiconductor device, a circuit board 11 is provided on the lower surface side of the wiring board 20 as shown in FIG. The wiring substrate 20 is provided with the wiring conductor layer 3 on the lower surface side of the insulating substrate 1, the circuit board 11 is provided with the solder bumps 6 on the upper surface side, and the semiconductor device has the wiring conductor layer 3 via the solder bumps. And the electrode pattern 12 of the circuit board 11 are electrically connected.

The wiring conductor layer 3 has a thickness of, for example, 0.2 (μm) to 10 (μm). The wiring conductor layer 3 is made of, for example, a metal material such as copper, silver, or gold, and is formed using a sputtering method, a vapor deposition method, or the like. Further, when the wiring conductor layer 3 is made of copper or a metal material containing copper as a main component, the main component is copper, and the resistivity of copper is low, so that the electric resistance of the wiring conductor layer 3 is kept low. Can do. The resistivity of copper at 20 ° C. is 1.68 (× 10 ⁻⁸ Ωm), and 20
The resistivity of silver at ° C. is 1.59 (× 10 ⁻⁸ Ωm), and the resistivity of gold at 20 ° C. is 2.21 (× 10 ⁻⁸ Ωm).

  As shown in FIG. 1, the barrier layer 4 is provided so as to overlap and contact the wiring conductor layer 3. The barrier layer 4 suppresses the wiring conductor layer 3 from moving due to electromigration. That is, the metal material of the wiring conductor layer 3 is prevented from moving to the solder bump 6 side due to electromigration. The barrier layer 4 is provided so as to cover the wiring conductor layer 3 and is laminated on the wiring conductor layer 3.

  In addition, the wiring substrate 20 is provided with the barrier layer 4 so as to be in contact with the wiring conductor layer 3, whereby the barrier layer 4, which is unlikely to cause electromigration, suppresses the movement of the wiring conductor layer 3, thereby suppressing electromigration. The barrier layer 4 is made of a refractory metal that is unlikely to cause electromigration. For example, the barrier layer 4 is made of a metal material such as titanium, tungsten, tantalum, or platinum, or a metal material such as an alloy thereof. The alloy material is made of, for example, a titanium alloy, a tungsten alloy, a tantalum alloy, a platinum alloy, or a titanium tungsten alloy. The thickness of the barrier layer 4 is set to, for example, 0.1 (μm) to 2 (μm) in order to suppress electromigration of the wiring conductor layer 3.

  The solder bonding layer 5 is laminated on the barrier layer 4 as shown in FIG. Further, the solder bonding layer 5 may be provided so as to cover the barrier layer 4. That is, the solder bonding layer 5 may be provided so as to be laminated on the barrier layer 4 and cover the side surface of the barrier layer 4. Further, when a second adhesive layer 14 described later is provided between the barrier layer 4 and the solder bonding layer 5, the solder bonding layer 5 is provided so as to overlap the barrier layer 4 in plan view.

  The solder bonding layer 5 ensures wettability with the solder bumps 6 and improves the bonding properties with the solder bumps 6. The solder bonding layer 5 is provided so as to cover the barrier layer 4 and is laminated on the barrier layer 4. Has been. The solder joint layer 5 is made of, for example, a metal material such as nickel, palladium, or gold.

  Moreover, the thickness of the solder bonding layer 5 is, for example, 0.5 (μm) to 5 (μm) so that the bondability with the solder bump 6 is improved.

  On the lower side of the wiring board 20, a circuit board 11 that provides a driving current or an electric signal to the semiconductor element 9 is provided. The circuit board 11 includes an electrode pattern 12 and solder bumps 6 provided on the electrode pattern 12. As shown in FIG. 1, the wiring conductor layer 3 is electrically bonded to the electrode pattern 12 of the circuit board 11 through the solder bumps 6. The solder bump 6 is used to electrically and mechanically connect the wiring conductor layer 3 and the circuit board 11. For example, a material such as tin-silver, tin-silver-copper, or tin-silver-bismuth is used. Can do.

  The connection pad 7 is provided on the upper surface (one main surface) of the insulating substrate 1 and is formed of a metal material. Further, as shown in FIG. 2A, for example, the connection pad 7 has a quadrangular shape in plan view, but is not limited thereto, and may be circular or elliptical.

  The connection pad 7 is provided so as to face the electrode 10 of the semiconductor element 9 and is electrically joined to the electrode 10 of the semiconductor element 9 via the bump 8. The shape and size of the connection pad 7 are appropriately set according to the shape or size of the semiconductor element 9. The electrode shape of the semiconductor element 9 is, for example, a quadrangular shape in a plan view similar to the shape of the connection pad 7.

As shown in FIG. 1, the connection pad 7 includes a first layer 7 a and a second layer 7 b, and the first layer 7 a is a layer provided on one main surface side of the insulating substrate 1. It is provided so as to cover the end face of the through conductor 2 exposed on the substrate 1 and is made of a metal material such as copper, silver, gold, tungsten or molybdenum. Further, when the first layer 7a is made of copper or a metal material containing copper as a main component, the main component is copper, and the resistivity of copper is low, so that the electrical resistance of the connection pad 7 can be kept low. it can. The second layer 7b is a layer provided on the first layer 7a and is made of a metal material such as nickel, palladium, or gold. As described above, the second layer 7b is made of a metal material having excellent corrosion resistance, such as nickel or gold, and can improve electrical connectivity with the electrode 10 of the semiconductor element 9. The first layer 7a has a thickness of, for example, 0.2 (μm) to 10 (μm), and the second layer 7b has a thickness of, for example, 0.5 (μm) to 5 (μm). ).

  The electrode 10 of the semiconductor element 9 is made of a metal material such as copper, nickel, or gold, and is electrically bonded to the bonding pad 7 via the bump 8. The bumps 8 are disposed between the connection pads 7 and the electrodes 10 of the semiconductor element 9 and are electrically connected to each other. In FIG. 2A, the bumps 8 are connected via the four bumps 8. The pad 7 and the electrode 10 of the semiconductor element 9 are electrically joined. The bumps 8 are made of a metal material such as gold or tin.

  As shown in FIG. 1, the wiring board 20 has the wiring conductor layer 3 electrically connected to the electrode pattern 12 of the circuit board 11 via the solder bumps 6, and the electrodes 10 of the semiconductor element 9 are bumps 8. It is electrically bonded to the bonding pad 7 via Thus, the semiconductor device includes the wiring board 20, the semiconductor element 9 mounted on the mounting portion on one main surface, and the circuit board 11 electrically connected to the solder bonding layer 5 via the solder bumps. To prepare.

  Here, electromigration will be described. In the wiring board 20, when current flows from the solder bump 6 and the solder bonding layer 5 to the through conductor 2 through the wiring conductor layer 3, an electron flow occurs in a direction opposite to the current flow. That is, in the wiring board 20, an electron flow is generated from the through conductor 2 through the wiring conductor layer 3 and the solder bonding layer 5 toward the solder bump 6. For example, when the barrier layer 4 is not provided on the wiring substrate 20, the wiring substrate 20 is first electromigrationd between the solder bonding layer 5 and the solder bump 6 by the flow of electrons toward the solder bump 6. Next, there is a possibility that electromigration may occur among the wiring conductor layer 3, the solder joint layer 5, and the solder bump 6.

  Specifically, in the wiring board 20, the current flows from the solder bump 6 through the wiring conductor layer 3 to the through conductor 2, so that the current is concentrated in a region located below the through conductor 2 on the other main surface. In this region, electromigration of the wiring conductor layer 3 is likely to occur. In this way, the current tends to concentrate particularly in the region where the through conductor 2 and the wiring conductor layer 3 overlap in plan view, and the region where the current concentrates is the concentration region R. As shown in FIG. 3C, the concentrated region R is a region surrounded by the extended outer periphery by extending the outer periphery of the through conductor 2 to the wiring conductor layer 3 side. Is concentrated. In other words, the concentration region R is a region located below the through conductor 2 and is particularly a region where current is concentrated and is surrounded by a broken line as shown in FIG.

Thus, the wiring board 20 tends to have a high current density in the concentrated region R, that is, in the wiring conductor layer 3 positioned below the other end face of the through conductor 2. The metal material forming the layer 3 or the metal material forming the solder joint layer 5 is partially diffused (moved) into the solder bump 6 by electromigration, and the wiring conductor layer 3 or the through conductor 2 and There is a possibility that a gap is formed between the wiring conductor layer 3 and the wiring conductor layer 3. As described above, when a gap due to electromigration is generated inside the wiring conductor layer 3 or between the through conductor 2 and the wiring conductor layer 3, the wiring substrate 20 is formed inside the wiring conductor layer 3 or between the through conductor 2 and the wiring conductor layer 3. There is a possibility that problems such as local increase in electrical resistance or disconnection may occur.

  However, the wiring board 20 according to Embodiment 1 is provided so that the barrier layer 4 is between the wiring conductor layer 3 and the solder bonding layer 5 and is in contact with the wiring conductor layer 3. 4 suppresses electromigration of the wiring conductor layer 3. This is because the barrier layer 4 is formed of a refractory metal that is unlikely to cause electromigration, so that the diffusion (movement) of the metal material of the wiring conductor layer 3 is suppressed.

  Accordingly, since the wiring board 20 is provided so that the barrier layer 4 is in contact with the wiring conductor layer 3, electromigration of the metal material forming the wiring conductor layer 3 can be suppressed. Therefore, the wiring board 20 can suppress the occurrence of problems such as a local increase in electrical resistance or disconnection in the wiring conductor layer 3 or between the wiring conductor layer 3 and the through conductor 2. In addition, by using the wiring substrate 20, the semiconductor device can suppress electromigration.

  For example, when the wiring conductor layer 3 is made of copper or a metal material mainly composed of copper, the copper electromigration is suppressed by providing the barrier layer 4 so as to be in contact with the wiring conductor layer 3 as described above. can do.

  In addition, since the semiconductor device includes the wiring substrate 20 having the above-described configuration and the solder bumps 6 electrically connected to the wiring conductor layer 3, the solder bumps 6 are electrically connected to the wiring conductor layer 3 and energized. Since a barrier layer is provided between the solder bonding layer 5 and the wiring conductor layer 3, a gap due to electromigration in the wiring conductor layer 3 or between the wiring conductor layer 3 and the through conductor 2 is provided. Can be effectively suppressed. Therefore, by using the wiring substrate 20, a highly reliable semiconductor device can be manufactured.

  In addition, as shown in FIGS. 4 and 5, the wiring substrate 20 </ b> A can be provided with a first adhesive layer 13 in order to improve the adhesion between the insulating substrate 1 and the wiring conductor layer 3. That is, the wiring board 20 </ b> A is obtained by providing the first adhesive layer 13 between the insulating substrate 1 and the wiring conductor layer 3 in the wiring board 20. The first adhesive layer 13 is made of a metal material such as titanium or chromium, for example. The first adhesive layer 13 has a thickness of, for example, 0.05 (μm) to 0.5 (μm). As described above, the first adhesive layer 13 is interposed between the insulating substrate 1 made of a ceramic material and the wiring conductor layer 3 to improve the adhesiveness to the insulating substrate 1 and to improve the adhesion with the wiring conductor layer 3. Adhesiveness can be improved.

  In addition, as shown in FIGS. 6 and 7, the wiring board 20 </ b> B may further include a second adhesive layer 14 in order to improve the adhesion between the barrier layer 4 and the solder bonding layer 5. it can. The second adhesive layer 14 is provided so as to cover the barrier layer 4, and the solder bonding layer 5 is provided so as to cover the barrier layer in plan view. The second adhesive layer 14 is made of a metal material such as nickel, copper, or gold, for example. The second adhesive layer 14 has a thickness of, for example, 0.1 (μm) to 2 (μm).

  As described above, the second adhesive layer 14 is interposed between the barrier layer 4 and the solder joint layer 5 to improve the adhesiveness to the solder joint layer 5 and to improve the adhesiveness to the barrier layer 4. Can be made. In the wiring board 20, the second adhesive layer 14 may be provided between the barrier layer 4 and the solder bonding layer 5.

In addition, the second adhesive layer 14 is more effective, particularly when a metal material that easily oxidizes the barrier layer 4 can secure the adhesion to the solder bonding layer 5. The metal material of the barrier layer 4 that is easily oxidized is, for example, titanium, tantalum, tungsten, or the like.

  Here, a method for manufacturing a wiring board will be described.

  If the insulating substrate 1 is made of, for example, an aluminum oxide sintered body, it can be manufactured as follows. That is, a ceramic produced by forming a slurry prepared by adding and mixing an appropriate organic binder and organic solvent to raw powders such as aluminum oxide and silicon oxide into a sheet shape using a sheet forming technique such as a doctor blade method or a lip coater method. Make a green sheet. Thereafter, the ceramic green sheet is formed into a predetermined shape and size by using a cutting process or a punching process, and a plurality of these are laminated and fired at a temperature of about 1300 (° C.) to 1500 (° C.), for example. Can be produced.

  In addition, the through conductor 2 has a through hole formed in advance in a position where the wiring conductor layer 3 and the connection pad 7 are to be formed in the ceramic green sheet to be the insulating substrate 1. By filling a metal paste to be the through conductor 2 and performing simultaneous firing, a sintered body of the wiring board 20 in which the through conductor 2 is formed in the thickness direction of the insulating substrate 1 can be manufactured.

  The connection pad 7 is formed on one main surface of the insulating substrate 1 as follows. First, a metal layer to be the connection pad 7 is formed on one main surface of the insulating substrate 1 by an electroless plating method, a sputtering method, a vapor deposition method, or the like. Thereafter, a resist pattern is formed so as to cover a portion to be the connection pad 7 using a photolithography method, and then an excess metal layer not covered with the resist pattern is removed using a chemical etching method, a dry etching method, or the like. . Thereafter, by removing the resist pattern, the connection pads 7 having a predetermined pattern can be formed on one main surface of the insulating substrate 1.

  The wiring conductor layer 3 and the barrier layer 4 are formed on the other main surface of the insulating substrate 1 as follows. First, a metal layer that becomes the wiring conductor layer 3 and the barrier layer 4 is sequentially formed on the other main surface of the wiring substrate 1 by an electroless plating method, a sputtering method, a vapor deposition method, or the like. Thereafter, a resist pattern is formed so as to cover a predetermined wiring conductor layer 3 and a portion to be the barrier layer 4 using a photolithography method, and then an excess metal layer not covered with the resist pattern is subjected to a chemical etching method or a dry etching. Remove using the method. Thereafter, by removing the resist pattern, a predetermined pattern of the wiring conductor layer 3 and the barrier layer 4 can be formed on the other main surface of the insulating substrate 1.

  The solder bonding layer 5 is formed by sequentially forming a metal layer to be the wiring conductor layer 3, the barrier layer 4, and the solder bonding layer 5 on the other main surface of the wiring substrate 1, and using the photolithography method described above, the wiring conductor It can be formed on the layer 3 and the barrier layer 4 simultaneously. The solder joint layer 5 can be formed on the wiring conductor layer 3 and the barrier layer 4 formed in a predetermined pattern by using an electroless plating method, an electrolytic plating method, or the like.

  The first adhesive layer 13 is formed, for example, by sequentially forming a metal layer to be the first adhesive layer 13, the wiring conductor layer 3, and the barrier layer 4 on the insulating substrate 1 by using the photolithography method described above. The wiring conductor layer 3 and the barrier layer 4 can be formed simultaneously.

  Further, the second adhesive layer 14 is formed, for example, in the order of the wiring conductor layer 3, the barrier layer 4, and the second adhesive layer 14, and is formed on the wiring conductor layer 3 and the barrier layer 4 by using the photolithography method described above. Can be formed simultaneously.

  The solder bumps 6 of the circuit board 11 are, for example, set by aligning and setting the solder balls made using the above-described solder material on the electrode pattern 12 and heating them integrally in an electric furnace ( (Reflow). The solder bump 6 formed by this method has a spherical shape in which a joint portion with the solder joint layer 5 is flattened. In order to facilitate connection with the electrode pattern 12 of the circuit board 11, when a plurality of solder bumps 6 are pressed together on a flat surface (such as a pressing mold) from the upper side, the solder bumps The upper surface side of 6 also becomes flat.

  The present invention is not limited to the first embodiment described above, and various modifications and improvements can be made without departing from the scope of the present invention. Hereinafter, other embodiments will be described. Of the wiring boards according to the other embodiments, the same parts as those of the wiring board 20 according to the first embodiment are denoted by the same reference numerals, and the description thereof is omitted as appropriate.

<Embodiment 2>
A wiring board 20C and a semiconductor device according to a second embodiment (referred to as a second embodiment) of the present invention will be described below with reference to FIGS.

  The wiring conductor layer 3 has a first wiring conductor layer 3a and a second wiring conductor 3b. As shown in FIGS. 8 and 9, the first conductive conductor layer 3 has a first wiring surface from the other main surface side. The wiring conductor layer 3a and the second wiring conductor layer 3b are sequentially stacked. As shown in FIG. 9B, the second wiring conductor layer 3b has an average crystal grain size smaller than that of the first wiring conductor layer 3a. The second wiring conductor layer 3b is compared with the average wiring grain size of the first wiring conductor layer 3a by comparing the average grain diameter of the crystal grains of the second wiring conductor layer 3b. The average grain size of the crystal grains is smaller than that of the conductor layer 3a.

  The average grain size of the crystal grains of the first wiring conductor layer 3a is, for example, 1 (μm) to 5 (μm), and the average grain diameter of the crystal grains of the second wiring conductor layer 3b is, for example, It is 0.01 (μm) to 0.5 (μm). The first wiring conductor layer 3a has a thickness of, for example, 0.5 (μm) to 8 (μm), and the second wiring conductor layer 3b has a thickness of, for example, 0.1 (μm). ~ 2 (μm). The first wiring conductor layer 3a is formed so as to be thicker than the second wiring conductor layer 3b. Further, the size of the crystal grains of the first wiring conductor layer 3a is, for example, the same size as the thickness of the first wiring conductor layer 3a.

  For example, in the wiring conductor layer 3, a metal material is formed using a sputtering method, but a grain boundary due to grain growth occurs during the film formation. When the wiring conductor layer 4 has large crystal grains, if the barrier layer 4 is provided so as to be in contact with the wiring conductor layer 3, the barrier layer 4 grows along the grain boundary of the wiring conductor layer 3. 4 is in a state in which a part thereof penetrates into the wiring conductor layer 3. Therefore, the barrier layer 4 is a pinhole penetrating the barrier layer 4 in a region grown along the grain boundary of the wiring conductor layer 3. Is easily formed. The metal material forming the wiring conductor layer 3 is easily diffused (moved) to the solder bumps 6 through the pinholes formed in the barrier layer 4 by electromigration, so that the inside of the wiring conductor layer 3 or the wiring conductor layer 3. There is a possibility that problems such as local increase in electrical resistance or disconnection may occur between the through conductor 2 and the through conductor 2. That is, when the wiring conductor layer 3 is copper, copper is easily diffused (moved) to the solder bumps 6 through the pinholes of the barrier layer 4 by electromigration.

  However, in the wiring board 20C, the wiring conductor layer 3 is provided with the second wiring conductor layer 3b having crystal grains smaller than that of the first wiring conductor layer 3a on the barrier layer 4 side. Since 3b has small crystal grains, the grain boundary 3b1 tends to be small. Thus, as shown in FIG. 9B, the grain boundary that is the boundary between crystal grains is such that the gap between the grain boundaries 3b1 of the second wiring conductor layer 3b is the grain boundary 3a1 of the first wiring conductor layer 3a. It is smaller than the gap.

  Even if the barrier layer 4 grows along the grain boundary of the wiring conductor layer 3, since the grain boundary 3b1 of the second wiring conductor layer 3b is small, a part of the barrier layer 4 is the second wiring conductor layer. It is difficult to be in a state of entering into 3b. Therefore, even if a part of the barrier layer 4 grows along the grain boundary 3b1 of the second wiring conductor layer 3b, it is difficult to form a pinhole that penetrates the barrier layer 4 in that region.

  As described above, the wiring board 20 </ b> C is hard to form pinholes in the barrier layer 4, and local electrical resistance increases between the wiring conductor layer 3 or between the wiring conductor layer 3 and the through conductor layer 2 due to electromigration. Or possibility that malfunctions, such as a disconnection will arise, is further reduced.

  The wiring conductor layer 3 is provided as follows. The first wiring conductor layer 3a is formed with a desired thickness of 70 (%) to 90 (%) of the wiring conductor layer 3 by forming a film in a high energy state using a sputtering method. And the 2nd wiring conductor layer 3b is formed in the remaining thickness with respect to the desired thickness of the wiring conductor layer 3 by forming into a film in a low energy state using sputtering method. In this way, the wiring conductor layer 3 can be continuously formed with the first wiring conductor layer 3a and the second wiring conductor layer 3b by changing the film forming conditions.

  In addition, the high energy state means that a film is formed with a high thermal energy or a high collision speed using a sputtering method, and the low energy state means a metal that is formed. The film formation is performed in a state where the thermal energy of the particles is low or the collision speed is low. Note that in a sputtering method, for example, a high energy state is achieved by increasing the film formation temperature, increasing the acceleration voltage during sputtering, or decreasing the sputtering gas pressure. In the sputtering method, for example, a low energy state is achieved by lowering the film formation temperature, lowering the acceleration voltage during sputtering, or raising the sputtering gas pressure.

  By forming the film in this way, the wiring conductor layer 3 can be formed with different crystal grain sizes in the first wiring conductor layer 3a and the second wiring conductor layer 3b.

  Further, since the first wiring conductor layer 3a forms a metal component in a high energy state, adhesion to the insulating substrate 1 or the first adhesive layer 13 is improved.

The size of the crystal grains of the first wiring conductor layer 3a and the crystal grains of the second wiring conductor layer 3b can be measured by observing a cross section of the wiring conductor layer 3 using scanning ion microscopy. The average particle diameter can be calculated using an area calculation method, an intercept method, or the like. For example, in the area calculation method, the target area A is set in the cross section of the wiring conductor layer 3 and the number n of crystal grains existing in the target area A is calculated. At this time, the number of crystal grains on the boundary line of the target area A is counted as ½. Next, an average crystal grain cross-sectional area a is calculated from the number n of crystal grains and the target area A. Thus, by obtaining the square root of the average crystal grain cross-sectional area a, the average grain size per crystal grain can be obtained.

  The present invention is not particularly limited to the above-described embodiments, and various changes and improvements can be made within the scope of the present invention.

DESCRIPTION OF SYMBOLS 1 Insulating substrate 2 Through-conductor 3 Wiring conductor layer 3a 1st wiring conductor layer 3b 2nd wiring conductor layer 4 Barrier layer 5 Solder joint layer 6 Solder bump 7 Connection pad 8 Bump 9 Semiconductor element 10 Electrode 11 Circuit board 12 Electrode pattern 13 First Adhesion Layer 14 Second Adhesion Layer 20, 20A, 20B, 20C Wiring Board

Claims (3)

An insulating substrate having a semiconductor element mounting portion on one main surface and having a through conductor formed through the one main surface and the other main surface;
A wiring conductor layer that is electrically connected to the through conductor, provided on the other main surface side so that the outer periphery is located outside the outer periphery of the end surface of the through conductor in plan view;
A barrier layer provided so as to overlap and contact the wiring conductor layer;
A wiring board comprising: a solder bonding layer that is provided so as to overlap the barrier layer in plan view and is bonded to a solder bump.   The wiring conductor layer is formed by laminating a first wiring conductor layer and a second wiring conductor layer having an average grain size smaller than that of the first wiring conductor layer from the insulating substrate side. The wiring board according to claim 1. The circuit board according to claim 1 or 2, a semiconductor element mounted on the mounting portion on the one main surface, and a circuit board electrically connected to the solder joint layer via solder bumps And a semiconductor device.

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