JP2012156467A - Wiring substrate, wiring substrate with solder bump, and semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a wiring substrate in which an electrode of a semiconductor element is bonded to a connection pad arranged on an insulation substrate via a solder bump, and an air gap between the connection pad and the electrode caused by electromigration is suppressed.SOLUTION: A wiring substrate has: an insulation substrate 1 having a mounting part 1a for an electronic component element; a through conductor 3 formed from the mounting part 1a to the inside of the insulation substrate 1; and a connection pad 2 made of copper or an alloy whose main component is copper, and adhered from an upper face of the insulation substrate 1 to an end part of the through conductor 3, and to which an electrode 5 of a semiconductor element 4 is bonded via solder 6. In a region adhered to the end part of the through conductor 3 in a plan view, a metal layer 8 made of nickel or an alloy whose main component is nickel is adhered to an upper face of the connection pad 2. Due to the metal layer 8, migration of the connection pad 2 is suppressed, and due to a copper component of the connection pad 2 bonded to the solder 6, the migration of the connection pad 2 can be suppressed.

Description

  The present invention relates to a wiring board having a connection pad to which an electronic component element such as a semiconductor element is bonded via solder, a wiring board with solder bumps in which a solder bump is bonded to the connection pad of the wiring board, and a semiconductor element in the wiring board Relates to a semiconductor device formed by bonding via solder.

  An electronic component element, for example, a semiconductor element such as a semiconductor integrated circuit element (IC) is usually mounted on a wiring board such as a ceramic wiring board for mounting a semiconductor element to become a semiconductor device, and is an electronic device such as a computer, a communication device, or a sensor device. It is used by being mounted on an external electric circuit (motherboard or the like) constituting the device.

  In general, a semiconductor element has a structure in which an electronic circuit is formed on one main surface of a semiconductor substrate such as silicon and a circular electrode or the like electrically connected to the electronic circuit is arranged on one main surface. The electronic circuit is electrically connected to the electrode by directly connecting one end thereof to a part of the outer periphery of the electrode.

  The wiring board has a structure in which connection pads are formed on the upper surface of an insulating substrate such as a ceramic substrate corresponding to the arrangement of electrodes of electronic component elements such as semiconductor elements. When the electrodes of the semiconductor element and the connection pads of the wiring board are opposed to each other and bonded together via solder interposed therebetween, a semiconductor device is formed. The solder is made of, for example, a solder material such as tin-silver or tin-silver-bismuth, and is attached to the connection pad of the wiring board, for example, in a convex shape as a solder bump, and used for the above-described joining between the connection pad and the electrode. .

  The connection pad is electrically connected to a wiring conductor formed inside or on the bottom surface of the insulating substrate via a through conductor formed from the mounting portion to the inside of the insulating substrate. That is, the connection pad is attached from the upper surface of the insulating substrate to the end portion of the through conductor. The part of the wiring conductor exposed on the lower surface of the insulating substrate is joined to the external electric circuit via a conductive connecting material such as solder, so that the semiconductor element and the external electric circuit are electrically connected via the wiring substrate. Is done.

  The semiconductor device is mounted on the substrate of the electronic device, and currents as various signals are passed from the external electric circuit to the electrodes of the semiconductor element through the through conductors, the connection pads, and the solder bumps.

JP 2010-103501

Yi-Shao Lai et al., Electromigration of 96.5Sn-3Ag-0.5Cu Flip-chip Solder Bumps Bonded on Substrate Pads of Au / Ni / Cu or Cu Metallization, IEEE Electronic Components and Technology Conference, 2006 Lou Nicholls et al., Comparative Electromigration Performance of Pb Free Flip Chip Joints with Varying Board Surface Condition, IEEE Electronic Components and Technology Conference, 2009

  However, in the above-described prior art wiring board, when the electrode of the semiconductor element is joined to the connection pad via the solder (solder bump) and energized, a void (gap) is generated at the joint of the connection pad with the solder. There was a problem that there was a possibility of.

  This is because the current flowing from the through conductor to the solder bump through the connection pad tends to concentrate on the area of the connection pad where the through conductor is connected in plan view. Since the current density tends to be high in the area of the connection pad where the through conductor is connected in plan view, copper, which is the main component of the connection pad, causes electromigration in this area and partially diffuses into the solder bump. There is a possibility of creating voids. When such a gap due to electromigration occurs, problems such as a local increase in electrical resistance or disconnection occur between the connection pad and the solder bump.

  In particular, with the recent increase in the speed of semiconductor elements, the current flowing from the external electric circuit through the through conductor to the connection pad and the solder bump tends to increase further. Due to this, voids are more likely to be generated.

  The present invention has been completed in view of the above-described problems of the prior art. In a wiring board in which a connection pad is disposed on a mounting portion of an insulating substrate and an electrode of a semiconductor element is bonded to the connection pad via a solder bump. Another object of the present invention is to provide a wiring board capable of suppressing gaps due to electromigration of connection pads and electrodes. Another object of the present invention is to provide a wiring board with a solder bump and a semiconductor device capable of effectively suppressing the gap in the joint surface between the connection pad and the electrode with the solder bump.

  The wiring board of the present invention comprises an insulating substrate having an electronic component element mounting portion on the upper surface, a through conductor formed from the mounting portion to the inside of the insulating substrate, and copper or an alloy containing copper as a main component, A wiring board comprising a connection pad, which is deposited from the main surface of the insulating substrate to the end portion of the through conductor and to which the electrode of the main surface of the semiconductor element is bonded via solder, and in a plan view In the region attached to the end of the through conductor, a metal layer made of nickel or an alloy containing nickel as a main component is attached to the upper surface of the connection pad.

  Further, the wiring board according to the present invention has the above-described configuration in which the through conductor contains a glass component, and the connection pad has a glass component more in the portion connected to the through conductor than in other portions. It is characterized by containing.

  Moreover, the wiring board of the present invention is characterized in that, in the above configuration, the connection pad does not contain a glass component on the upper surface side to which the solder is bonded.

  A wiring board with solder bumps according to the present invention includes the wiring board having any one of the above-described structures and solder bumps bonded to the connection pads.

  A semiconductor device according to the present invention includes a wiring board having any one of the above-described configurations, and a semiconductor element mounted on the mounting portion and having an electrode formed on a main surface thereof bonded to the connection pad via solder. Features.

According to the wiring board of the present invention, the metal layer made of nickel or an alloy containing nickel as a main component is covered on the upper surface of the connection pad in the region having the above-described configuration and attached to the end of the through conductor in a plan view. Thus, the metal layer can suppress the electromigration of copper, which is the main component of the connection pad, and suppress the generation of voids in the connection pad.

  That is, in the above configuration, the current density of the current flowing from the through conductor to the solder (solder bump) through the connection pad is higher than the other parts, and is attached to the end of the through conductor in plan view. In the region, the metal layer made of nickel or an alloy containing nickel as a main component is in direct contact with the solder. In addition, nickel is a metal that is less susceptible to electromigration than copper. In addition, the resistance to the current flowing from the connection pad to the solder bump is increased by the metal layer as compared with the portion where the metal layer is not deposited, and the current in the region where the through conductor is connected in the plan view of the connection pad. The current density can be suppressed to some extent. Therefore, it is possible to suppress the generation of voids in the connection pad due to electromigration as described above.

  In the wiring board of the present invention, in the above configuration, the through conductor contains a glass component, and the connection pad contains more glass components in the portion connected to the through conductor than in other portions. In this case, the bonding strength between the through conductor and the connection pad and the insulating substrate and between the through conductor and the connection pad can be further increased by the bonding between the glass components. Therefore, in this case, the above-mentioned air gap can be suppressed, and the junction (electrical and mechanical connection) between the through conductor and the connection pad and the insulating substrate, and between the through conductor and the connection pad. A wiring board with higher reliability can be provided.

  In the wiring board of the present invention, in the above configuration, when the connection pad does not contain a glass component on the upper surface side to which the solder is bonded, voids in the connection pad and the electrode are generated as described above. It is possible to suppress and improve the bonding strength between the through conductor and the connection pad, etc., and it is also advantageous for increasing the reliability of the connection (electrical and mechanical connection) between the connection pad and the solder. A substrate can be provided. Moreover, it is advantageous also in suppressing the contact resistance between the connection pad and the solder.

  According to the wiring board with solder bumps of the present invention, since the wiring board having any one of the above structures and the solder bumps bonded to the connection pads are provided, when the semiconductor bump electrodes are joined and energized In addition, the metal layer can suppress electromigration at the joint surface of the connection pad with the solder bump, and can effectively suppress the generation of voids in the connection pad. Therefore, it is possible to provide a wiring board with solder bumps capable of manufacturing a highly reliable semiconductor device.

  In addition, according to the semiconductor device of the present invention, the wiring board having any one of the above configurations and a semiconductor element mounted on the mounting portion and having electrodes formed on the main surface joined to the connection pads via solder are provided. Therefore, as in the case of the wiring board, it is possible to suppress the electromigration at the joint surface of the connection pad with the solder, and to effectively prevent the generation of a gap in the connection pad. A highly reliable semiconductor device can be provided.

It is sectional drawing which shows the principal part in an example of embodiment of the wiring board of this invention. (A) is a top view which shows an example of the whole wiring board which shows the principal part in FIG. 1, (b) is sectional drawing in the AA of (a). (A) is sectional drawing which shows the principal part in the other example of embodiment of the wiring board of this invention, (b) is a top view of (a). It is sectional drawing which shows an example of embodiment of the wiring board with a solder bump of this invention. It is sectional drawing which shows an example of embodiment of the semiconductor device of this invention.

  A wiring board of the present invention, a wiring board with solder bumps using the wiring board, and a semiconductor device will be described with reference to the accompanying drawings. In the following description, an example in which a semiconductor element is used as the electronic component element will be described. The electronic component element is not limited to a semiconductor element, but may be another electronic component element such as an element in which the semiconductor element is mounted on a relay substrate or the like, or a piezoelectric element.

  FIG. 1 is a cross-sectional view showing a main part in an example of an embodiment of a wiring board of the present invention. 2A is a plan view showing an example of the entire wiring board shown in FIG. 1, and FIG. 2B is a cross-sectional view taken along the line AA in FIG. 1 and 2, 1 is an insulating substrate, 2 is a connection pad, 3 is a through conductor, 4 is a semiconductor element, and 5 is an electrode of the semiconductor element 4. A wiring board for mounting the semiconductor element 4 by the insulating substrate 1, the connection pad 2 disposed on the mounting portion 1a on the upper surface of the insulating substrate 1, and the through conductor 3 having the connection pad 2 attached to the end. Is basically configured.

  In FIG. 1, the semiconductor element 4 is mounted on the wiring board, and the electrode 5 of the semiconductor element 4 is joined to the connection pad 2 via the solder (solder bump) 6 (electrically and mechanically connected). FIG. 2 shows only the wiring board. The electrode 5 of the semiconductor element 4 is bonded to the connection pad 2 of the wiring board via the solder bumps 6 by a method such as soldering (reflow) to form a semiconductor device.

  The wiring board is a so-called IC package or the like for mounting a semiconductor element 4 to manufacture a semiconductor device. The wiring board is made of, for example, a ceramic material such as a glass ceramic sintered body, an aluminum oxide sintered body, a mullite sintered body, an aluminum nitride sintered body, a resin material such as an epoxy resin or a polyimide resin, a ceramic material, A mounting portion 1a of a semiconductor element 4 is provided on the upper surface of an insulating substrate 1 formed of an insulating material such as a composite material of a glass material and a resin material, and a connection pad 2 is disposed on the mounting portion 1a. Yes.

If the insulating substrate 1 is made of, for example, a glass ceramic sintered body, it can be manufactured as follows. That is, a glass component such as borosilicate glass and a ceramic component such as aluminum oxide are main components, and an appropriate organic binder and organic solvent are added to and mixed with the raw material powder prepared by adding a sintering aid or the like. This is formed into a sheet shape by using a sheet forming technique such as a doctor blade method or a lip coater method to obtain a plurality of ceramic green sheets, and then the ceramic green sheets are appropriately cut and punched. A plurality of these are laminated, and finally the laminated ceramic green sheets are fired at a temperature of about 800 to 1000 ° C. in a reducing atmosphere.

  The insulating substrate 1 has, for example, a square plate shape, and a region such as a square shape at the center of the upper surface thereof serves as a mounting portion 1 a for the semiconductor element 4. A plurality of connection pads 2 to which the plurality of electrodes 5 of the semiconductor element 4 are electrically connected are arranged on the mounting portion 1a.

  The connection pad 2 is arranged on the mounting portion 1 a on the upper surface of the insulating substrate 1 so as to face the electrode 5 arranged on the main surface (lower surface in the example of FIG. 1) of the semiconductor element 4. The connection pad 2 and the electrode 5 of the semiconductor element 4 are bonded to each other through the solder bump 6, whereby the semiconductor element 4 and the wiring board are electrically and mechanically connected to form a semiconductor device.

  The connection pad 2 is made of copper or a metal material containing copper as a main component. Since the main component of the connection pad 2 is copper and the electrical resistance (resistivity) of copper is low, the electrical resistance in the connection pad 2 can be kept low.

  The connection pad 2 has, for example, a circular shape, an elliptical shape, a quadrangular shape, or the like in plan view, and the shape and size are appropriately set according to the shape and size of the electrodes 5 that are connected to face each other. For example, when the electrode 5 has a circular shape with a diameter of about 100 to 300 μm, the connection pad 2 is formed in a slightly larger circular shape (with a diameter of about 200 to 400 μm).

  The connection pad 2 can be formed in the form of a metallized layer, a plating layer, a vapor deposition layer, or the like. For example, if the connection pad 2 is made of a copper metallized layer, a metal paste prepared by kneading copper powder together with an organic solvent and a binder is used as the surface of a ceramic green sheet (insulating substrate 1). It is formed by printing with a predetermined connection pad 2 pattern by a printing method such as a screen printing method and co-firing from the exposed surface of a metal paste to be a through conductor 3 to be described later to the upper surface). Can do.

  The connection pad 2 is electrically connected to an external electric circuit (not shown in FIGS. 1 and 2) through a through conductor 3 formed from the mounting portion 1a of the insulating substrate 1 to the inside. That is, the through conductor 3 is for forming a conductive path for electrically connecting the connection pad 2 to an external electric circuit. Therefore, the through conductor 3 is formed from the mounting portion 1a to the inside of the insulating substrate 1, and the connection pad 2 is attached from the upper surface of the insulating substrate 1 to the end portion of the through conductor 3 (the end portion exposed to the mounting portion 1a). Yes. By connecting the connection pad 2 (lower surface) directly to the end portion of the through conductor 3, the connection pad 2 and the through conductor 3 are electrically connected to each other. Since the connection pad 2 is attached from the upper surface of the insulating substrate 1 to the end portion of the through conductor 3, the connection pad 2 has a portion overlapping the through conductor 3 and a portion overlapping the upper surface of the insulating substrate 1 in plan view. is doing.

  The through conductor 3 having the connection pad 2 attached to the end portion on the mounting portion 1a side is connected to the wiring conductor 7 formed on the inside or the lower surface of the insulating substrate 1 at the opposite end portion. If a portion of the wiring conductor 7 exposed on the lower surface of the insulating substrate 1 is joined to an external electric circuit via a conductive connecting material such as solder or a conductive adhesive, it is electrically connected to the electrode 5 of the semiconductor element 4. The connected connection pad 2 can be electrically connected to an external electric circuit through the through conductor 3 and the wiring conductor 7.

The through conductor 3 has, for example, a circular shape (cylindrical shape) with a diameter of about 75 to 200 μm, and is connected to the central portion of the connection pad 2 in plan view. In addition, the connection position with respect to the connection pad 2 of the edge part of the penetration conductor 3 in planar view may be not only the center part of the connection pad 2, but an outer peripheral part. A plurality of through conductors 3 may be connected to one connection pad 2. Further, the through conductor 3 is not limited to a circular shape, and may be an elliptical shape, a rectangular shape, or the like.

  The through conductor 3 and the wiring conductor 7 can be formed in the same manner using the same metal material as that of the connection pad 2. As for the metal material forming the through conductor 3 and the wiring conductor 7, copper and silver are advantageous in suppressing the respective electric resistances. In this case, for example, a through hole is formed in advance in the ceramic green to be the insulating substrate 1 at a position where the connection pad 2 is to be formed, and a metal such as copper or silver to be the through conductor 3 in the through hole. By filling the paste and performing simultaneous firing, the through conductors 3 can be formed in the thickness direction of the insulating substrate 1.

Examples of the solder material for forming the solder bump 6 for joining (electrically and mechanically connecting) the connection pad 2 and the electrode 5 of the semiconductor element 4 include tin-lead, tin-silver, tin-silver-copper, Tin-silver-bismuth or the like can be used. The solder bump 6 is preferably a so-called lead-free solder that does not contain harmful substances such as lead in order to avoid adverse effects on the environment. Since these solder materials contain about 90 mass% or more of tin, the electrical resistance (resistivity) of the solder bump 6 is approximately the same as the electrical resistance (resistivity) of tin.

  The solder bump 6 can be formed, for example, by aligning and setting a solder ball produced using the above solder material on the connection pad 2 and heating (reflowing) integrally in an electric furnace. it can. The solder bump 6 formed by this method has a spherical shape in which a joint portion with the connection pad 2 is flattened. In order to facilitate connection with the electrode 5 of the semiconductor element 4, when a plurality of solder bumps 6 are collectively pressed from above with a flat surface (such as a pressing mold), the solder bumps 6 The upper surface side of the plate becomes flat.

  A metal layer 8 made of nickel or an alloy containing nickel as a main component is covered on the upper surface of the connection pad 2 in a region (hereinafter also referred to as a deposition region) deposited on the end of the through conductor 3 in plan view. It is worn. Since such a metal layer 8 is deposited, the metal layer 8 can suppress electromigration of copper, which is the main component of the connection pad 2, and suppress the generation of voids in the connection pad 2. Can do.

That is, in the above configuration, the current density of the current flowing from the through conductor 3 through the connection pad 2 to the solder bump 6 is a portion higher than the other portions, and is attached to the end portion of the through conductor 3 in plan view. In this region, the metal layer 8 made of nickel or an alloy containing nickel as a main component is in direct contact with the solder bump 6. In addition, nickel is a metal that is less susceptible to electromigration than copper. Empirically, copper may migrate at a current density of about 5000 to 6000 A / cm ² , whereas nickel is about 15000 A / cm ^2.
It has been confirmed that there is no migration even to the extent. Further, the resistance to the current flowing from the connection pad 2 to the solder bump 6 is increased by the metal layer 8 as compared with the portion where the metal layer 8 is not attached, and the through conductor 3 is connected in plan view of the connection pad 2. The current density of the current in the formed region can be suppressed to some extent. Therefore, generation | occurrence | production of the space | gap in the connection pad 2 by electromigration as mentioned above can be suppressed.

  Further, according to the wiring board of the present invention, nickel or the metal layer 8 mainly composed of nickel of the connection pad 2 is deposited on the end of the through conductor 3 in plan view. Since the region is not the entire region, it includes a portion to which the connection pad 2 made of copper or a copper-based alloy is directly connected. Therefore, when the electrode 5 of the semiconductor element 4 is bonded to the connection pad 2 through the solder bump 6 and energized, electromigration in the electrode 5 can be suppressed. This is because the copper component of the connection pad 2 is thermally diffused to the electrode 5 side of the semiconductor element 4, and the diffused copper, the tin component of the solder bump 6, and the electrode 5 are formed on the surface of the electrode 5. This is because an alloy layer mainly composed of a metal such as nickel is formed and the alloy layer is difficult to electromigration.

  Such a metal layer 8 can be deposited on the upper surface of the connection pad 2 by a method such as plating or vapor deposition. When the metal layer 8 is deposited by, for example, a plating method, the connection pad 2 is contained in an electroless nickel plating solution mainly composed of a nickel component such as nickel sulfate and a reducing agent such as sodium hypophosphite. Can be applied by immersing the film in a predetermined time at a predetermined temperature.

  Considering that the metal layer 8 is advantageous in increasing the density of the connection pads 2 and the wiring conductors 7 in the wiring board because a plating conductive line is not required when the plating layer to be the metal layer 8 is deposited. In this case, it is preferable that the film is deposited by an electroless plating method.

In order to deposit the metal layer 8 on the deposition region of the connection pad 2 while suppressing displacement, for example, the image is based on the outer peripheral position of the connection pad 2 (for example, two arbitrary points on the outer periphery). If the mask material is deposited on the upper surface of the connection pad 2 using the recognition device (the mask material is deposited on the area other than the deposition area), the nickel plating layer is deposited on the portion exposed from the mask material. Good. An example of the mask material is an ultraviolet curable resin film. The mask material is preferably one that can be completely removed with a chemical solution or the like after the plating layer (metal layer 8) is deposited.

  The thickness of the metal layer 8 is more effective in suppressing electromigration, but if it is too thick, the strength and economics of depositing the metal layer 8 on the connection pad 2 due to the internal stress of the metal layer 8 are increased. May be reduced. On the other hand, if the thickness is too large, the specific resistance of the metal layer 8 is increased, so that the current may be easily concentrated on a portion other than the metal layer 8, and the resistance of the entire semiconductor device may be increased.

Considering such conditions, the thickness of the metal layer 8 is such that, for example, the solder bump 6 is made of tin-silver-copper (Sn-3Ag-0.5Cu), and the current density of the current flowing through the deposition region is about 5000. If it is about ˜15000 A / cm ² , it may be set to about 1 to 3 μm.

  Further, the thickness of the metal layer 8 is preferably the same thickness in the entire region in order to obtain the effect of suppressing electromigration in the entire region where the metal layer 8 is deposited.

  In addition, the metal layer 8 needs to be deposited on the upper surface of the connection pad 2 at least over the entire deposition region, but does not need to exactly coincide with the deposition region. It may be slightly protruded outside the deposition area.

  Regarding the metal layer 8, examples of the alloy mainly composed of nickel include nickel-phosphorus and nickel-cobalt-phosphorus. The nickel content in nickel-phosphorus is about 90 to 98% by mass when formed by, for example, an electroless plating method.

  For example, as shown in FIG. 3, the metal layer 8 is a range in which the metal layer 8 is deposited on the upper surface of the connection pad 2 in order to reduce the positioning effort with respect to the deposition region when the metal layer 8 is formed. May be set slightly larger than the deposition area. 3A is a cross-sectional view showing a main part of another example of the embodiment of the wiring board according to the present invention, and FIG. 3B is a plan view of FIG. 3A. In FIG. 3, the same parts as those in FIG. Further, FIG. 3A shows that the semiconductor element 4 is mounted on the wiring board, and the electrode 5 of the semiconductor element 4 is joined to the connection pad 2 via the solder (solder bump) 6 (electrically and mechanically connected). 3 (b) shows only the wiring board.

  When the metal layer 8 protrudes outside the deposition region, for example, the solder bump 6 is directly bonded to the connection pad 2 outside the circular metal layer 8 on the upper surface of the circular connection pad 2. It is preferable to secure a width of the annular portion of 5 μm or more.

  In such a wiring board, the through conductor 3 contains a glass component, and the connection pad 2 contains more glass components in the portion connected to the through conductor 3 than in other portions. The bonding strength between the through conductor 3 and the connection pad 2 and the insulating substrate 1 and between the through conductor 3 and the connection pad 2 can be further increased by the mutual bonding of the glass components. Therefore, in this case, the gaps in the connection pads 2 can be suppressed, and the through conductors 3, the connection pads 2 and the insulating substrate 1, and the junctions between the through conductors 3 and the connection pads 2. A wiring board having higher strength, higher reliability of electrical connection, and the like can be provided.

  In this case, for example, as shown in FIG. 1, the connection pad 2 can be regarded as being constituted by a lower layer 2 a having a relatively high glass component content and an upper layer 2 b having a relatively small amount.

  Examples of the glass component contained in the through conductor 3 include the same glass components used when the insulating substrate 1 is formed of a glass ceramic sintered body. Moreover, what is necessary is just to set suitably content of the glass component in the penetration conductor 3 according to the material which forms the insulated substrate 1, the dimension of the penetration conductor 3, etc. FIG.

  For example, the insulating substrate 1 is made of a glass ceramic sintered body using borosilicate glass, the glass component added to the through conductor 3 is borosilicate glass, and the size of the through conductor 3 is a circular shape (circle) having a diameter of 100 μm. In the case of (columnar), the content of the glass component in the through conductor 3 may be set to about 10 to 20% by mass.

  As for the connection pad 2, it is assumed that the glass component content is different from each other as described above. For example, as shown in FIG. 1, the connection pad 2 includes the lower layer 2a and the upper layer 2b. When forming by the metallization method, the metal pastes that will become the connection pads 2 are prepared with different glass contents, and the first paste having a high glass content is firstly applied from the surface of the ceramic green sheet. It prints over the edge part of the metal paste used as the penetration conductor 3, Then, it is made to print the 2nd paste with little glass content on the printed 1st paste by the same pattern as the 1st paste, for example. It may be fired.

In the above case, the portion of the connection pad 2 with a low glass component content, for example, the upper layer 2b may be a portion that does not contain a glass component. For example, if the second paste is prepared by kneading with an organic solvent using only copper powder, the upper part including the upper surface to which the solder bumps 6 are bonded is copper (copper content is 99.99% by mass or more). , So-called pure copper).

  When the connection pad 2 does not contain a glass component on the upper surface side (for example, the upper layer 2b) to which the solder bumps 6 are bonded, the wiring board has voids in the connection pad 2 and the electrode 5 as described above. It is possible to suppress the occurrence and improve the bonding strength between the through conductor 3 and the connection pad 2, and to improve the reliability of the connection (electrical and mechanical connection) between the connection pad 2 and the solder bump 6. It is possible to provide a wiring board that is advantageous in increasing the height.

  The thickness of the connection pad 2 that does not contain a glass component (such as the upper layer 2b) is preferably 5 μm or more in consideration of, for example, corrosion in a soldering (reflow) process.

  When solder bumps 6 are joined to the connection pads 2 of this wiring board, a wiring board with solder bumps as shown in FIG. 4 is obtained. FIG. 4 is a cross-sectional view showing an example of an embodiment of a wiring board with solder bumps of the present invention. 4, parts similar to those in FIG. 1 are denoted by the same reference numerals.

  According to such a wiring board with solder bumps, since the wiring board having the above configuration and the solder bumps 6 joined to the connection pads 2 are provided, the electromigration at the joint surface between the connection pads 2 and the solder bumps 6 is performed. Therefore, it is possible to provide a wiring board with solder bumps that can effectively suppress the generation of voids due to the above and can manufacture a highly reliable semiconductor device.

  The solder bump 6 is formed of a solder material such as tin-lead, tin-silver, tin-silver-copper, or tin-silver-bismuth as described above. The solder bump 6 is preferably a so-called lead-free solder that does not contain harmful substances such as lead in order to avoid adverse effects on the environment.

  The solder bump 6 can be formed, for example, by aligning and setting a solder ball manufactured using the above solder material on the connection pad 2 and reflowing using an electric furnace or the like. The solder bump 6 formed by this method has a spherical shape in which a joint portion with the connection pad 2 is flattened. In order to facilitate the connection with the electrode 5 of the semiconductor element 4, the plurality of solder bumps 6 may be collectively pressed from above with a flat surface (such as a pressing mold). In this case, the upper surface side of the solder bump 6 is also flat.

  If the semiconductor element 4 is mounted on the mounting portion 1a of the wiring board having the above-described configuration, and the electrode 5 on the main surface of the semiconductor element 4 is joined to the connection pad 2 via the solder (solder bump) 6, FIG. A semiconductor device as shown is manufactured. FIG. 5 is a cross-sectional view showing an example of an embodiment of a semiconductor device of the present invention. 5, parts similar to those in FIG. 1 are denoted by the same reference numerals.

  For joining the electrode 5 and the connection pad 2 via the solder bump 6, for example, a method of aligning and placing the electrode 5 of the semiconductor element 4 on the solder bump 6 of the wiring board with solder bump of the present invention and reflowing it. Can be done.

  In the semiconductor device, solder is bonded to the electrode 5 of the semiconductor element 4 in a convex shape (a solder bump 6 is formed on the electrode 5 side), and then the solder bump 6 bonded to the electrode 5 is used. The electrode 5 of the semiconductor element 4 can be joined to the connection pad 2 of the wiring board via the wiring.

  The semiconductor element 4 is formed of a semiconductor substrate made of a semiconductor material such as silicon, phosphorus gallium arsenide, germanium, gallium arsenide, gallium nitride, or silicon carbide. The semiconductor element 4 is, for example, a rectangular plate-like silicon substrate having a side length of about 3 to 10 mm, and an electrode 5 made of copper, aluminum, or the like is formed on the main surface thereof.

  The electrode 5 is used to electrically connect an electronic circuit (integrated circuit) (not shown) of the semiconductor element 4 to the wiring board, and to electrically connect the semiconductor element 4 and an external electric circuit via the wiring board. belongs to. The electrode 5 is formed of a metal material such as copper, aluminum, silver, palladium, or nickel. Of these metal materials, copper and aluminum are often used as the main components of the metal material forming the electrode 5 in consideration of low electrical resistance, economy, and the like.

  The shape and dimensions of the electrode 5 are appropriately set according to the arrangement position of the electronic circuit and the like, and are formed in, for example, a circular shape having a diameter of about 100 to 300 μm.

  For example, the semiconductor element 4 is formed by forming a silicon oxide film (unsigned) on the main surface of a semiconductor substrate (silicon wafer or the like), and then depositing aluminum or copper into a pattern of a predetermined electronic circuit or electrode 5 using a vapor deposition method and a photo process. It is manufactured by forming with a fine processing technique such as a lithographic method. A passivation layer (no symbol) made of an insulating material such as polyimide resin is formed between conductors such as electrodes 5 in the semiconductor substrate.

  Such a semiconductor device is mounted as a component in various electronic devices such as a computer, a communication device, and an inspection device. A circuit such as a motherboard provided in the electronic device corresponds to an external electric circuit.

  According to such a semiconductor device, the wiring board with solder bumps having the above configuration and the semiconductor element mounted on the mounting portion 1a and bonded to the connection pads 2 via the solder bumps 6 are formed on the main surface. 4, a highly reliable semiconductor device capable of effectively suppressing the generation of voids due to electromigration at the joint surface of the connection pad 2 with the solder bump 6 can be provided.

  In the above wiring board, wiring board with solder bumps, and semiconductor device, the metal layer 8 does not have to be formed of the same material, and is formed by laminating a plurality of materials. It doesn't matter. Moreover, the thing of the structure of the several layer by which the same material is apply | coated separately in multiple times may be sufficient. For example, the metal layer 8 may be formed by laminating two types of nickel-phosphorous layers having different phosphorus contents.

  The following semiconductor element and wiring board are prepared, and the electrodes of the semiconductor element and the connection pads of the wiring board are electrically and mechanically connected to each other via solder bumps made of tin-silver solder, and the semiconductor device of the embodiment (An example of a semiconductor device using the wiring board of the present invention) and a semiconductor device of a comparative example were manufactured. In the semiconductor device of the example, a metal layer is formed on the upper surface of the connection pad in a region (deposition region) deposited on the end of the through conductor in plan view, and the metal layer is formed in the semiconductor device of the comparative example. There wasn't.

Semiconductor element: As a semiconductor substrate, a silicon substrate of a square plate shape with a side length of 5 × 5 mm is used, and the main surface of the semiconductor substrate is covered with an electronic circuit made of aluminum and copper and copper via a silicon oxide film. An electrode having a nickel layer is disposed. The electrodes were circular with a diameter of about 100 μm, and 64 (8 × 8) arrays were arranged vertically and horizontally on the main surface of the semiconductor substrate.

Wiring board: Circular shape with a diameter of about 150μm on the upper surface of a square plate-like insulating board with a side length of about 10 x 10 x 1 mm made using a glass ceramic sintered body. The connection pads were formed. The number of connection pads is 64, the same as the number of electrodes of the semiconductor element, and each connection pad was formed at a position corresponding to the electrode of the semiconductor element. The through conductor was formed in a circular shape (cylindrical shape) having a diameter of about 100 μm using copper in the same manner as the connection pad, and its end was directly connected to the center of the connection pad.

  Metal layer: A metal layer made of a nickel-phosphorus alloy was deposited on the upper surface of the connection pad by electroless plating. The metal layer had a thickness of about 1.5 μm and a nickel content of about 95% by mass.

Solder bump: Tin-silver-copper (Sn-3Ag-0.5Cu) solder was used. The solder bumps were formed by placing solder balls having the above composition on the electrodes of the semiconductor element and reflowing them at about 260 ° C. to join them in a convex shape.

About each of the above examples and comparative examples, each semiconductor device was mounted on a printed circuit board, energized between the wiring board and the semiconductor element for 500 hours, and before and after energization between the connection pad and the electrode. The rate of increase in resistance was calculated, and a failure was determined when the rate of increase was 20% or more. The energization amount at each connection pad (the magnitude of the current flowing from each through conductor of the wiring board through the connection pad to the solder bump and further to the electrode at each connection pad) is about 0.8 A
It was. Similarly, a current of about 0.8 A was applied to the electrodes of the semiconductor element. The current density at the connection pad is about 4527 A / cm ² and the current density at the electrode is about 10185 A / cm ^2.
Met.

  As a result, no failure occurred in the semiconductor device of the example of the present invention, whereas 20% of the connection pads failed in the semiconductor device of the comparative example. Thereby, the effect which suppresses generation | occurrence | production of the space | gap in a connection pad and an electrode in the semiconductor device produced using the wiring board of this invention has been confirmed.

DESCRIPTION OF SYMBOLS 1 ... Insulating substrate 1a .... Mounting part 2 ... Connection pad 3 ... Through-conductor 4 ... Semiconductor element 5 ... Electrode 6 ... Solder (solder bump)
7 ... Wiring conductor 8 ... Metal layer

Claims (5)

An insulating substrate having an electronic component element mounting portion on an upper surface, a through conductor formed from the mounting portion to the inside of the insulating substrate, and copper or an alloy containing copper as a main component, and from the upper surface of the insulating substrate A wiring board having a connection pad attached to an end portion of a through conductor and to which an electrode of the semiconductor element is bonded via solder, and is an area attached to the end portion of the through conductor in a plan view And a metal layer made of nickel or an alloy containing nickel as a main component is deposited on the upper surface of the connection pad. The said penetration conductor contains the glass component, The said connection pad contains more glass components in the part connected with the said penetration conductor than the other part. The wiring board described. The wiring board according to claim 2, wherein the connection pad does not contain a glass component on an upper surface side to which the solder is bonded. A wiring board with solder bumps, comprising: the wiring board according to claim 1; and solder bumps bonded to the connection pads. A wiring board according to any one of claims 1 to 3 and a semiconductor element mounted on the mounting portion and formed on a main surface and bonded to the connection pad via solder. A featured semiconductor device.

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