JP2008211170A - Substrate for packaging semiconductor element, its manufacturing method and semiconductor device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a substrate for packaging a semiconductor element, which improves the bonding strength of a bump electrode by an ultrasonic bonding, and to provide a manufacturing method therefor and a semiconductor device. <P>SOLUTION: The substrate 19 for packaging semiconductor elements has a packaging section 11, where electrode pads 12 are formed for packaging a semiconductor element 21 having the bump electrode 23 on a plurality of electrode terminals 22 formed on the lower surface thereof, on the upper surface of an insulating substrate 11. The bump electrode 23 is brought into contact with the electrode pad 12, and ultrasonic waves are applied from the upper surface of the semiconductor element 21 for joining the bump electrode 23 to the electrode pad 12. In the electrode pad 12, a center part 12a in the region brought into contact with the bump electrode 23 is lower than the peripheral part 12b, and an annular gap 12c is provided between the center part 12a and the peripheral part 12b. The center part 12a and the peripheral part 12b of the electrode pad 12 are engaged with the bump electrode 23, and a stress at joining can be relaxed by the gap 12c, thus joining strength and packaging reliability can be improved. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  According to the present invention, a bump electrode provided on an electrode terminal formed on a lower surface of a semiconductor element is applied to an electrode pad formed on an upper surface of an insulating substrate, and ultrasonic waves that vibrate the bump electrode are applied to the semiconductor element. The present invention relates to a semiconductor element mounting substrate to be bonded by the above, a method for manufacturing the semiconductor element mounting substrate, and a semiconductor device using the semiconductor element mounting substrate.

  There is a so-called flip-chip mounting method as one method for mounting and mounting an electronic component such as a semiconductor element on a semiconductor element mounting board which is a wiring board used for a circuit board, a semiconductor element storage package or the like.

  In this mounting method, generally, a protruding electrode made of gold or the like is provided on an electrode terminal of a semiconductor element by wire bonding technology or the like, while the protruding electrode is provided on a semiconductor element mounting substrate on which the semiconductor element is mounted. An electrode pad is provided at a position opposite to the semiconductor element, the protruding electrode such as gold of the semiconductor element is aligned with the electrode pad of the semiconductor element mounting substrate, the semiconductor element is placed on the semiconductor element mounting substrate, and the protrusion is The semiconductor element is mounted on the semiconductor element mounting substrate in a so-called face-down manner by bonding the protruding electrode and the electrode pad after bringing the electrode into contact with the electrode pad.

In such a flip chip mounting method, an ultrasonic wave is applied from the upper surface of the semiconductor element mounted on the semiconductor element mounting substrate as a method of bonding the electrode pad of the semiconductor element mounting substrate and the protruding electrode of the semiconductor element. By ultrasonic bonding, the protruding electrode is vibrated in the left-right direction (a direction parallel to the surface of the substantially planar electrode pad), and a metal such as gold is partially melted near the contact interface between the protruding electrode and the electrode pad. There is a mounting method to join.
JP 2006-128487 JP 2006-319211 A Japanese Patent Laid-Open No. 2002-222828

  However, the connection method between the protruding electrode and the electrode pad in the conventional mounting method as described above has the following problems.

  That is, when flip chip mounting is performed, the height of the protruding electrode is very low, which causes unevenness of the substrate for mounting a semiconductor element and variations in the thickness (height) of the electrode pad. As a result, there is a problem that the semiconductor element may be defective in mounting.

  In order to prevent such mounting defects, it is necessary that all the protruding electrodes of the semiconductor element be connected to the electrode pads of the substrate for mounting the semiconductor element. To that end, the variation in the height of the protruding electrodes is reduced. Therefore, it is necessary to improve the flatness of the semiconductor element mounting substrate and to reduce the variation in the thickness (height) of the electrode pads. However, the variation in the height of the protruding electrode is not as important as the variation in the flatness of the semiconductor element mounting substrate and the thickness (height) of the electrode pad because they are crushed during mounting.

  Therefore, in order to prevent mounting defects, the semiconductor element mounting substrate should be as flat as possible with as little unevenness as possible on the mounting surface, and the thickness (height) of the wiring pattern including the electrode pads can be reduced. It is considered desirable to form the film while suppressing variations.

  By the way, in the ultrasonic flip chip mounting in which the bump electrode of the semiconductor element and the electrode pad of the substrate for mounting the semiconductor element are ultrasonically bonded, the mounting surface of the semiconductor element mounting substrate having excellent flatness with no unevenness, particularly the electrode pad. When a semiconductor element is mounted by flip chip mounting using a flat semiconductor element mounting substrate, thermal expansion occurs due to environmental temperature or heat generated from the semiconductor element, and the thermal expansion coefficient between the semiconductor element and the semiconductor element mounting substrate Due to this difference, horizontal stress is generated on the substrate at the connection portion.

  In addition, the protruding electrodes are individually bonded to the semiconductor element by an ultrasonic wave for each protruding electrode by a wire bonding method or the like, and further, ultrasonic waves are collectively applied from the upper surface of the semiconductor element during flip chip mounting. Although the bonding strength to the semiconductor element (electrode terminal) is relatively strong, comparison with the electrode pad of the semiconductor element mounting substrate is only applied in a lump from the top of the semiconductor element during flip chip mounting. Weak joint strength.

  Therefore, by repeating the temperature cycle after mounting, the circuit may be disconnected due to the disconnection from the bonding interface between the electrode pad of the semiconductor element mounting substrate, which is the weakest bonding part, and the protruding electrode of the semiconductor element. was there.

  The present invention has been made in view of the above-described problems in the prior art, and its object is to increase the bonding strength by ultrasonic bonding to the electrode pad of the protruding electrode of the semiconductor element and improve the mounting reliability. An object of the present invention is to provide a substrate, a method for manufacturing the semiconductor element mounting substrate, and a highly reliable semiconductor device using the semiconductor element mounting substrate.

  The substrate for mounting a semiconductor element of the present invention is opposed to the electrode terminal for mounting a semiconductor element having a plurality of electrode terminals formed on the lower surface and having a protruding electrode on the upper surface of the insulating substrate. A mounting portion having a plurality of electrode pads is formed, and the protruding electrodes are brought into contact with the electrode pads, and ultrasonic waves are applied from the upper surface of the semiconductor element to bond the protruding electrodes to the electrode pads. A substrate for mounting a semiconductor element, wherein the electrode pad has a lower central portion of a region where the protruding electrode contacts lower than an outer peripheral portion, and an annular gap is provided between the central portion and the outer peripheral portion. It is characterized by being.

  Further, the semiconductor element mounting substrate of the present invention is characterized in that, in the above configuration, the gap is wider on the side intersecting with the left-right vibration of the protruding electrode due to the ultrasonic wave than other portions. .

  Moreover, the substrate for mounting a semiconductor element of the present invention is characterized in that, in the above configuration, the electrode pad has a plating layer having a thickness different from that of the central portion and the outer peripheral portion deposited on a base conductor layer. It is what.

  According to the method for manufacturing a substrate for mounting a semiconductor element of the present invention, the protruding electrode for mounting a semiconductor element having a plurality of electrode terminals formed on the lower surface of the insulating substrate and having a protruding electrode on the electrode terminal is provided. A step of forming a base conductor layer to be abutted and a plurality of electrode pads to be joined by applying ultrasonic waves from the upper surface of the semiconductor element; and the protruding electrode abuts on the surface of the base conductor layer The electrode pad is attached by depositing a plating layer on which the protruding electrode abuts so that the central portion of the region is lower than the outer peripheral portion and an annular gap is provided between the central portion and the outer peripheral portion. And a forming step.

  Further, in the method for manufacturing a semiconductor element mounting substrate according to the present invention, in the manufacturing method described above, before the step of depositing the plating layer and forming the electrode pad, the base conductor layer is formed at the center and the substrate. A portion corresponding to the outer peripheral portion is formed so as to be electrically independent across the gap, and the insulating substrate is plated only from a portion corresponding to the outer peripheral portion of the base conductor layer to an outer edge of the insulating substrate. The method includes a step of forming a lead line.

  Further, in the method for manufacturing a semiconductor element mounting substrate according to the present invention, in the manufacturing method described above, before the step of depositing the plating layer and forming the electrode pad, the base conductor layer is formed at the center and the substrate. A portion corresponding to the outer peripheral portion is formed so as to be electrically independent with the gap interposed therebetween, and at least the central portion of the insulating substrate on the central portion of the base conductor layer and the outer peripheral portion. Forming a first lead wire for plating from the portion corresponding to the outer edge of the insulating substrate, and forming a second lead wire for plating from the portion corresponding to the outer peripheral portion to the outer edge of the insulating substrate. Are provided.

  A semiconductor device according to the present invention includes a plurality of electrodes facing each of the electrode terminals for mounting a semiconductor element in which a plurality of electrode terminals are formed on the upper surface of the insulating substrate and the electrode terminals are provided with protruding electrodes. A substrate for mounting a semiconductor element having a mounting portion on which a pad is formed, a plurality of electrode terminals formed on the lower surface, and provided with a protruding electrode on the electrode terminal, and the protruding electrode is connected to the electrode pad by ultrasonic bonding And a semiconductor element mounted on the mounting portion, and an annular gap is provided between a central portion and an outer peripheral portion of a bonding region between the protruding electrode and the electrode pad. To do.

  In the semiconductor device according to the present invention, in the above configuration, the annular gap is wider on the side intersecting the left-right vibration of the protruding electrode due to the ultrasonic wave applied at the time of the ultrasonic bonding than other portions. It is characterized by this.

  In the semiconductor device according to the present invention, the electrode pad has a plating layer having a different thickness between the central portion and the outer peripheral portion on the underlying conductor layer, and the central portion is more in comparison with the outer peripheral portion. It is characterized by being deposited so as to be lowered.

  According to the substrate for mounting a semiconductor element of the present invention, the electrode pad has a lower central portion of the region where the protruding electrode contacts than the outer peripheral portion, and an annular gap is provided between the central portion and the outer peripheral portion. Therefore, the protruding electrode of the semiconductor element that vibrates with ultrasonic energy and the upper surface of the central portion of the electrode pad and the portion extending from the inner surface to the upper surface of the outer peripheral portion come into mesh with each other, and the protruding electrode vibrates. Since the range is limited by the inner surface of the outer peripheral portion of the electrode pad, it is possible to effectively suppress the occurrence of bonding failure such as misalignment of the protruding electrode in flip chip mounting.

  In addition, since the bonding surface between the protruding electrode and the inner side surface of the outer peripheral portion of the connection pad is orthogonal or inclined with respect to the horizontal plane, the bonding strength against the horizontal stress acting on the bonding portion between the protruding electrode and the connection pad is increased. Can be improved.

  In addition, since a gap is provided between the central portion and the outer peripheral portion of the electrode pad, internal stress generated in the protruding electrode near the bonding surface between the protruding electrode and the electrode pad at the time of ultrasonic bonding, For example, the protrusion electrode can be effectively relaxed by a minute deformation or the like in a portion facing the gap.

  Therefore, it is possible to provide a joint structure that is strong against stress in the horizontal direction on the upper surface of the insulating substrate, and it is possible to effectively prevent mechanical destruction of the protruding electrode caused by residual stress. In addition, it is possible to provide a semiconductor element mounting substrate with improved mounting reliability.

  Further, according to the substrate for mounting a semiconductor element of the present invention, in the above configuration, when the gap intersects with the vibration in the horizontal direction of the protruding electrode by the ultrasonic wave is wider than the other part, the protruding electrode and the electrode pad In the range (joint surface) to be joined, a gap can be widened on the side where the joint surface tends to be long (wide) due to the large vibration width of the protruding electrode due to the vibration caused by the ultrasonic waves. Therefore, it is possible to more effectively relieve stronger internal stress that may occur on the wide joint surface. Therefore, in this case, it is possible to provide a semiconductor element mounting substrate effective in further improving the mounting reliability.

  Further, according to the semiconductor element mounting substrate of the present invention, in the above configuration, the electrode pad has a plating layer having a thickness different between the central portion and the outer peripheral portion on the underlying conductor layer. For example, the thickness of the central portion and the outer peripheral portion can be adjusted by a plating layer that can be accurately formed with a thickness of about several μm and the thickness can be easily adjusted. Therefore, it is possible to provide a semiconductor element mounting substrate in which an electrode pad having a central portion lower than the outer peripheral portion is formed with higher accuracy.

  Further, according to the method for manufacturing a substrate for mounting a semiconductor element of the present invention, since the above steps are included, the surface of the underlying conductor layer formed on the mounting portion of the insulating substrate by a metallized layer or metal foil is masked, for example. In combination with the above means, an electrode pad is formed by depositing a plating layer on which the protruding electrode abuts so that the central portion is lower than the outer peripheral portion and an annular gap is provided between the central portion and the outer peripheral portion. Forming a semiconductor element mounting substrate having an electrode pad in which the central portion of the region where the protruding electrode abuts is lower than the outer peripheral portion and an annular gap is provided between the central portion and the outer peripheral portion. It can be manufactured accurately and reliably.

  Further, according to the method for manufacturing a substrate for mounting a semiconductor element of the present invention, in the above manufacturing method, before the step of forming the electrode pad by depositing the plating layer, the base conductor layer is placed on the central portion and the outer peripheral portion. Forming a corresponding portion so as to be electrically independent with a gap, and forming a lead wire for plating on the insulating substrate from only the portion corresponding to the outer peripheral portion of the base conductor layer to the outer edge of the insulating substrate. In this case, the semiconductor element mounting having the electrode pad in which the central portion of the region where the protruding electrode abuts is lower than the outer peripheral portion and an annular gap is provided between the central portion and the outer peripheral portion by the above-described process. The manufacturing method of the manufacturing substrate can be made easier and more productive.

  That is, the underlying conductor layer formed such that the portions corresponding to the central portion and the outer peripheral portion of the electrode pad are electrically independent with the gap therebetween, and the portions corresponding to the outer peripheral portion are electrically Only a plating layer can be applied by electrolytic plating. In addition, it is possible to deposit a plating layer on the entire base conductor layer including a portion corresponding to the central portion by an electroless plating method, and a plating layer having a predetermined thickness is also applied to the portion corresponding to the central portion. Can be applied. Therefore, for example, in addition to the plating layer deposited by the electroless plating method, the portion corresponding to the outer peripheral portion where the plating layer can be deposited by the electrolytic plating method is thicker than the portion corresponding to the central portion. Can be deposited. Further, in this case, a process such as masking is not necessary, and for example, it corresponds to the outer peripheral portion only by connecting the terminal of the plating jig for supplying the plating current to the lead wire for plating. A thick plating layer can be deposited only on the portion. Therefore, it is easy to form an electrode pad in which the central portion of the region where the protruding electrode contacts is lower than the outer peripheral portion.

  Further, according to the method for manufacturing a substrate for mounting a semiconductor element of the present invention, in the above manufacturing method, before the step of forming the electrode pad by depositing the plating layer, the base conductor layer is placed on the central portion and the outer peripheral portion. The corresponding portion is formed so as to be electrically independent with a gap, and the outer edge of the insulating substrate from the portion corresponding to at least the central portion of the portion corresponding to the central portion and the outer peripheral portion of the underlying conductor layer is formed on the insulating substrate. A step of forming the first lead wire for plating and a step of forming the second lead wire for plating from only the portion corresponding to the outer peripheral portion to the outer edge of the insulating substrate. Manufactures a substrate for mounting semiconductor elements having an electrode pad in which the central part of the area where the protruding electrode contacts is lower than the outer peripheral part and an annular gap is provided between the central part and the outer peripheral part The that way, it can be more easily and highly productive manufacturing method.

  That is, the underlying conductor layer formed so that the portions corresponding to the central portion and the outer peripheral portion of the electrode pad are electrically independent with a gap therebetween is electrically And a plating layer can be separately deposited on each of the portions corresponding to the outer peripheral portion by electrolytic plating. Further, it is possible to supply a plating current to the entire underlying conductor layer including the portion corresponding to the central portion via the first plating lead wire, and at least a predetermined thickness in the central portion. A plating layer can be deposited. In addition, a thicker plating layer can be applied to only the portion corresponding to the outer peripheral portion of the base conductor layer via the second lead wire for plating. Further, in this case, a process such as masking is not required. For example, the plating layer is deposited simply by connecting the terminal of the plating jig for supplying the plating current to different lead wires. Part (part corresponding to the central part or the outer peripheral part) can be selected. Therefore, since the current can be supplied only to the outer peripheral portion of the electrode pad that is higher, that is, the plating layer needs to be deposited thicker, the central portion of the region where the protruding electrode contacts is lower than the outer peripheral portion. The electrode pad can be easily formed.

  According to the semiconductor device of the present invention, since it has the above-described configuration and has the annular gap between the central portion and the outer peripheral portion of the bonding region between the ultrasonic bonded electrode and the electrode pad, The internal stress generated in the protruding electrode in the vicinity of the bonding surface between the protruding electrode and the electrode pad when the sound wave is applied is effectively relieved by, for example, minute deformation in the gap portion of the protruding electrode, and the inside of the protruding electrode. It can be assumed that there is no residue.

  Therefore, it is possible to provide a joint structure that is strong against stress in the horizontal direction on the upper surface of the insulating substrate, and it is possible to effectively prevent mechanical destruction of the protruding electrode caused by residual stress. A semiconductor device with improved long-term mounting reliability can be provided.

  Further, according to the semiconductor device of the present invention, in the above configuration, when the annular gap is wider than the other part on the side intersecting the left-right vibration of the protruding electrode due to the ultrasonic wave applied at the time of ultrasonic bonding In the area where the protruding electrode and the electrode pad are bonded (bonding surface), a gap is widened on the side where the bonding electrode tends to be long (wide) due to the large vibration width of the protruding electrode due to vibration. be able to. Therefore, it is possible to more effectively relieve stronger internal stress that may occur on the wide joint surface. Therefore, in this case, it is possible to provide a semiconductor device that is effective in further improving long-term mounting reliability.

  Further, according to the semiconductor device of the present invention, in the above configuration, the electrode pad has a thickness of, for example, several μm when a plating layer having a thickness different between the central portion and the outer peripheral portion is deposited on the base conductor layer. The thickness of the central portion and the outer peripheral portion can be adjusted by the plating layer that can be formed with a certain degree of accuracy with high accuracy and the thickness can be easily adjusted. Therefore, it is possible to provide a more reliable semiconductor device in which an electrode pad whose central portion is lower than the outer peripheral portion is formed with higher accuracy, and a sufficient gap is provided between the electrode pad and the protruding electrode. Further, it is effective in improving the productivity as a semiconductor device.

  A substrate for mounting a semiconductor element, a manufacturing method thereof, and a semiconductor device of the present invention will be described with reference to the accompanying drawings.

(Semiconductor element mounting substrate and semiconductor device)
First, a semiconductor element mounting substrate of the present invention and a semiconductor device of the present invention formed by mounting a semiconductor element on the semiconductor element mounting substrate will be described with reference to FIG. FIG. 1A is a plan view showing an example of an embodiment of a substrate for mounting a semiconductor element of the present invention, and FIG. It is sectional drawing of the semiconductor device of invention. In order to make the drawing easier to see, FIG. 1B shows the semiconductor element and the semiconductor element mounting substrate separated from each other.

  In FIG. 1, reference numeral 11 denotes an insulating substrate, and 12 denotes an electrode pad. The electrode pad 12 is formed on a mounting portion 11 a on the upper surface of the insulating substrate 11 to basically form a semiconductor element mounting substrate 19. Reference numeral 21 denotes a semiconductor element, and reference numeral 22 denotes a plurality of electrode terminals formed on the lower surface of the semiconductor element 21, each having a protruding electrode 23. The semiconductor device 30 is basically configured by mounting the semiconductor element 21 on the mounting portion 11 a of the semiconductor element mounting substrate 19 and joining the protruding electrode 23 to the electrode pad 12.

  The electrode pads 12 are formed so as to face the protruding electrodes 23, respectively, and the central portion 12a is lower than the outer peripheral portion 12b in the range where the protruding electrodes 23 are joined, and between the central portion 12a and the outer peripheral portion 12b. An annular gap 12c is provided.

  The semiconductor element 21 mounted on the semiconductor element mounting substrate 19 is, for example, a semiconductor integrated circuit element (IC, LSI), a micromachine (so-called MEMS element) or the like, and is integrated on the main surface of a semiconductor substrate (not indicated) such as silicon. Functional parts (not shown) such as movable parts such as circuits and switching mechanisms are formed. For example, a plurality of electrode terminals 22 electrically connected to the functional part are formed on the main surface of the semiconductor substrate on which the functional part is formed, and each electrode terminal 22 includes a protruding electrode 23.

  The protruding electrode 23 is made of a metal material such as gold, tin-lead solder, or tin-silver solder. If the protruding electrode 23 is made of, for example, gold, a bonding wire made of gold is bonded to the surface of the electrode terminal 22 and pressed into a predetermined shape such as a spherical shape or a conical shape, or coated by a plating method. It is formed by a so-called bump forming technique such as attaching.

  The insulating substrate 11 is formed in, for example, a square plate shape, and has a mounting portion 11a on which the semiconductor element 21 is mounted by so-called flip mounting. The insulating substrate 11 has a flat plate shape in the example of this embodiment, but has a recess (cavity) (not shown) for housing the semiconductor element 21 on the top surface, and the bottom surface of the recess is the mounting portion 11a. Good.

  The insulating substrate 11 is an aluminum oxide sintered body, a glass ceramic sintered body, a ceramic sintered body such as an aluminum nitride sintered body, a mullite sintered body, an organic resin such as an epoxy resin or a polyimide resin, or an aluminum oxide. Etc. are formed of an electrically insulating material such as a composite material formed by bonding an inorganic powder such as an epoxy resin with an organic resin.

  A plurality of electrode pads 12 are formed on the mounting portion 11 a of the insulating substrate 11 so as to face the plurality of protruding electrodes 23 on the lower surface of the semiconductor element 21.

  The electrode pad 12 is for mounting the semiconductor element 21 by bonding the protruding electrode 23, and electrically connecting the electrode terminal 22 of the semiconductor element 21 to an external electric circuit (not shown). It functions as a part of the conductive path. In this case, for example, the electrode pad 12 is electrically led out to the outside of the mounting portion 11a through a wiring conductor (not shown) formed from the electrode pad 12 to an outer surface such as a side surface or a lower surface of the insulating substrate 11. Keep it. That is, the protruding electrode 23 of the semiconductor element 21 is bonded to the electrode pad 12 of the semiconductor element mounting substrate 19, and the portion of the wiring conductor exposed on the outer surface of the insulating substrate 11 is electrically connected to an external electric circuit. By connecting, the electrode terminal 22 of the semiconductor element 21 is electrically connected to an external electric circuit through the protruding electrode 23, the electrode pad 12, and the wiring conductor.

  The electrode pad 12 and the wiring conductor are made of a metal material such as tungsten, molybdenum, manganese, copper, silver, palladium, or gold, and are formed on the insulating substrate 11 in the form of a metallized layer, a vapor deposition layer, a metal foil, a plating layer, or the like. Is done.

  Such bonding of the protruding electrode 23 to the electrode pad 12 is performed by ultrasonic bonding in the present invention. The bonding between the protruding electrode 23 and the electrode pad 12 by ultrasonic bonding is performed, for example, by aligning the protruding electrode 23 so as to face the electrode pad 12 and placing the semiconductor element 12 on the mounting portion 11a. The protruding electrode 23 is brought into contact with each other, ultrasonic waves are applied from the upper surface of the semiconductor element 12, and the protruding electrode 23 and the electrode pad 12 are ultrasonically bonded. In this case, the protruding electrode 23 vibrates (mainly the reciprocating motion in the left-right direction (the direction parallel to the upper surface of the insulating substrate 11 and the lower surface of the semiconductor element 21)) by the energy of the applied ultrasonic waves and comes into contact with the electrode pad 12. Frictional heat is generated on the surface, and local melting occurs on the contact surface between the protruding electrode 23 and the electrode pad 12, and bonding is performed.

  For example, when the protruding electrode 23 is made of gold, an ultrasonic wave having an oscillation frequency of about 20 to 100 kHz is appropriate. Further, when ultrasonic waves are applied from the upper surface of the semiconductor element 21, the semiconductor element 21 may be pressed downward from the upper surface to effectively transmit ultrasonic energy to the contact surface.

  In the semiconductor element mounting substrate 19 of the present invention, the electrode pad 12 has an annular portion between the central portion 12a and the outer peripheral portion 12b, and the central portion 12a of the region where the protruding electrode 23 abuts is lower than the outer peripheral portion 12b. Is provided with a gap 12c.

  As described above, in the electrode pad 12, the central portion 12a of the region where the protruding electrode 23 abuts is lower than the outer peripheral portion 12b, and the annular gap 12c is provided between the central portion 12a and the outer peripheral portion 12b. Therefore, the protruding electrode 23 of the semiconductor element 21 that vibrates with ultrasonic energy and the upper surface of the central portion 12a of the electrode pad 12 and the portion that extends from the inner surface to the upper surface of the outer peripheral portion 12b come into mesh with each other, and the protrusion Since the range in which the electrode 23 vibrates is limited by the inner surface of the outer peripheral portion 12b of the electrode pad 12, it is possible to eliminate the occurrence of bonding failure such as misalignment of the protruding electrode 23 in flip chip mounting.

  Further, since the bonding surface between the protruding electrode 23 and the inner surface of the outer peripheral portion 12b of the connection pad 12 is orthogonal or inclined with respect to the horizontal plane, the horizontal stress acting on the bonding portion between the protruding electrode 23 and the connection pad 12 In contrast, the bonding strength can be improved.

  Further, since the annular gap 12c is provided between the central portion 12a and the outer peripheral portion 12b of the electrode pad 12, a protrusion is formed near the joint surface between the protruding electrode 23 and the electrode pad 12 during ultrasonic bonding. The internal stress generated in the electrode 23 can be effectively relieved by, for example, minute deformation of the protruding electrode 23 at the portion facing the gap 12c.

  Therefore, it is possible to make the joint structure strong against the stress in the horizontal direction on the insulating substrate 11, and it is possible to effectively prevent mechanical destruction of the protruding electrode 23 due to residual stress and the like. Thus, the semiconductor element mounting substrate 19 with improved mounting reliability can be provided.

  Further, the gap 12 c is provided in an annular shape such as an annular shape or an elliptical shape in order to effectively relieve internal stress generated in the vicinity of the joint surface of the protruding electrode 23 with the electrode pad 12 over the entire circumference of the protruding electrode 23. The gap 12c does not have to have the same width over the entire circumference, and may be partially different in width.

  Note that the difference in height between the central portion 12a and the outer peripheral portion 12b of the electrode pad 12 is such that the tip (lower end) portion of the protruding electrode 23 is formed in order to make contact and bonding with the protruding electrode 23 easy and strong. Is set to a size such that when the electrode contacts the upper surface of the central portion 12a, the portion adjacent to the tip of the protruding electrode 23 contacts the portion on the upper surface from the inner surface of the outer peripheral portion 12b.

  For example, if the protruding electrode 23 has a spherical or hemispherical shape with a diameter of about 150 to 200 μm and the external dimensions of the electrode pad 12 when viewed in plan are approximately the same as the protruding electrode 23, the electrode pad 12 has a central portion. What is necessary is just to form so that the difference of the height of 12a and the outer peripheral part 12b may be 10-20 micrometers.

  Such an electrode pad 12 having a height difference of 10 to 20 μm between the central portion 12a and the outer peripheral portion 12b is, for example, the bonding strength of the electrode pad 12 to the insulating substrate 11, the productivity of the semiconductor element mounting substrate 19, and the economy. In consideration of the properties, the height of the central portion 12a is set to about 10 to 15 μm, and the height of the outer peripheral portion 12b is set to about 20 to 35 μm.

  The gap 12c between the electrode pads 12 is more effective in reducing the internal stress of the bump electrode 23. However, if the gap 12c is too wide, the bonding area itself with the bump electrode 23 becomes too small. Tend to be difficult to improve. Therefore, the width of the gap 12c is, for example, a circular shape with an outer shape of the electrode pad 12 having a diameter of 150 to 200 μm or a square shape with a side length of 150 to 200 μm, and the gap 12c is formed in an annular shape on the inside. In such a case, the gap 12c is preferably provided with a width of about 10 to 50 μm.

  Further, in such a semiconductor element mounting substrate 19, when the gap 12 c is wider than the other part on the side intersecting the left-right vibration of the protruding electrode 23 due to the ultrasonic wave, the protruding electrode 23 and the electrode pad 12 The gap 12c can be widened on the side where the joining surface tends to be long (wide) in the joining range (joining surface). Therefore, it is possible to more effectively relieve stronger internal stress that may occur on the wide joint surface. Therefore, in this case, the semiconductor element mounting substrate 19 that is more effective in improving the mounting reliability can be provided.

  For example, as described above, a circular outer shape with a diameter of 150 to 200 μm or a rectangular outer shape with a side length of 150 to 200 μm, the height of the central portion 12a is about 10 to 15 μm, and the height of the outer peripheral portion 12b is If the central portion 12a when viewed in plan is a circular electrode pad 12 having a diameter of about 40 μm, the width of the gap 12c is 40 to 40 at both ends in the ultrasonic vibration direction. The difference between the two is about 20-30 μm, with about 50 μm being about 10-30 μm at other sites.

  FIG. 1A shows an example in which vibration due to application of ultrasonic waves is applied in the long side direction of the rectangular electrode pad 12, and an example in which the gap 12c is wide on both short sides.

  Further, in such a semiconductor element mounting substrate 19, the electrode pad 12 is formed on the base conductor layer 13 (13a, 13b) with the plating layer 14 (14a, 14b) having a thickness different between the central portion 12a and the outer peripheral portion 12b. Can be accurately formed with a thickness of, for example, several μm, and the central portion 12a and the outer peripheral portion can be formed by the plating layer 14 (14a, 14b) whose thickness can be easily adjusted. 12 height adjustments are possible. Therefore, it is possible to provide the semiconductor element mounting substrate 19 in which the electrode pads 12 having the central portion 12a lower than the outer peripheral portion 12b are formed with higher accuracy.

  The underlying conductor layer 13 (13a, 13b) is made of a metal material such as tungsten, molybdenum, manganese, copper, silver, palladium, or gold. Such a base conductor layer 13 (13a, 13b) is formed on the mounting portion 11a of the insulating substrate 11 in the form of, for example, a metallized layer, a metal foil, or a plated layer.

  The plating layer 14 (14a, 14b) is made of a metal material such as nickel, copper, gold, palladium, and the surface of the underlying conductor layer 13 (13a, 13b) by a plating method such as an electrolytic plating method or an electroless plating method. To be attached.

  Then, the protruding electrode 23 of the semiconductor element 21 is bonded to the electrode pad 12 formed on the mounting portion 11a of the semiconductor element mounting substrate 19, and the semiconductor element 21 is mounted on the mounting portion 11a. Is hermetically sealed with a sealing means (not shown) such as a lid or a sealing resin, whereby the semiconductor device of the present invention is manufactured. As described above, the semiconductor element 21 and the semiconductor element mounting substrate 12 are drawn apart from each other. However, in actuality, in the semiconductor device 30, the protruding electrode 23 of the semiconductor element 21 is formed on the semiconductor element mounting substrate 19. The electrode pad 12 is in contact with the central portion 12a and the outer peripheral portion 12b, and is joined with a gap 12c between the central portion 12a and the outer peripheral portion 12b.

  A semiconductor device 30 shown in FIG. 1B is an example of an embodiment of a semiconductor device of the present invention. The semiconductor device 30 is opposed to the electrode terminals 22 for mounting a semiconductor element 21 having a plurality of electrode terminals 22 formed on the lower surface of the insulating substrate 11 and having protruding electrodes 23 on the electrode terminals 22. A semiconductor element mounting substrate 19 having a mounting portion 11a on which a plurality of electrode pads 12 are formed, a plurality of electrode terminals 22 formed on the lower surface, and a protruding electrode 23 on the electrode terminal 22; The protruding electrode 23 is joined to the electrode pad 12 by sonic bonding, and the semiconductor element 21 is mounted on the mounting portion 11a. Further, the semiconductor device 30 has an annular gap 12c between the central portion 12a and the outer peripheral portion 12b of the bonding region between the protruding electrode 23 and the electrode pad 12.

  Since the semiconductor device 30 has the above-described configuration and has an annular gap 12c between the central portion 12a and the outer peripheral portion 12b of the bonding region between the ultrasonic bonded bump electrode 23 and the electrode pad 12, When ultrasonic waves are applied, the internal stress generated in the protruding electrode 23 in the vicinity of the bonding surface between the protruding electrode 23 and the electrode pad 12 is caused by, for example, minute deformation in a portion facing the gap 12c of the protruding electrode 23. It can be effectively relaxed and not left inside the protruding electrode 23 or the like.

  Therefore, it is possible to make the joint structure strong against the stress in the horizontal direction on the insulating substrate 11, and it is possible to effectively prevent mechanical destruction of the protruding electrode 23 due to residual stress and the like. The semiconductor device 30 with improved long-term mounting reliability can be provided.

  Further, in the semiconductor device 30, the annular gap 12c is such that the width on the side intersecting with the vibration in the left-right direction of the protruding electrode 23 by the ultrasonic wave applied at the time of ultrasonic bonding is wider than the width at the other part. Has the following effects.

  That is, in the range (bonding surface) where the protruding electrode 23 and the electrode pad 12 are bonded, the bonding electrode tends to become longer (wider) because the vibration width of the protruding electrode 23 due to vibration is large (the vibrating left and right sides). On the direction side), it is preferable to widen the gap 12c. Thereby, it is possible to more effectively relieve the stronger internal stress that may occur on the wide joint surface. Therefore, in this case, it is possible to provide the semiconductor device 30 effective in further improving long-term mounting reliability.

  Further, in the semiconductor device 30 of the present invention, the electrode pad 12 is coated with the plating layers 14 (14a, 14b) having different thicknesses at the central portion 12a and the outer peripheral portion 12b on the underlying conductor layer 13 (13a, 13b). In this case, for example, the thickness of the central portion 12a and the outer peripheral portion 12b can be accurately formed with a thickness of about several μm and the thickness of the central portion 12a and the outer peripheral portion 12b can be easily adjusted by the plating layer 14 (14a, 14b). You can adjust the height. Therefore, the electrode pad 12 having the central portion 12a lower than the outer peripheral portion 12b can be formed with higher accuracy, and a more reliable semiconductor device having a sufficient gap 12c between the electrode pad 12 and the protruding electrode 23. 30 can be offered. Further, since the height accuracy of the electrode pad 12 is high, and the protruding electrode 23 can be brought into contact with the central portion 12a and the outer peripheral portion 12b of the electrode pad 12 more easily and accurately, the electrode pad 12 and the protruding electrode 23 Since the bonding by the ultrasonic bonding can be performed more easily, it is effective in improving the productivity as the semiconductor device 30.

(Manufacturing method of semiconductor element mounting substrate)
A method for manufacturing the semiconductor element mounting substrate 19 of the present invention will be described with reference to FIG. FIGS. 2A and 2B are cross-sectional views showing an example of an embodiment of a method for manufacturing the semiconductor element mounting substrate 19 shown in FIG. In FIG. 2, the same parts as those in FIG.

  First, as shown in FIG. 2A, a protrusion for mounting a semiconductor element 21 having a plurality of electrode terminals 22 formed on the lower surface of the insulating substrate 11 and having a protruding electrode 23 on the electrode terminal 22 is mounted. Underlying conductor layers 13 (13a, 13b) to be a plurality of electrode pads 12 to be bonded are formed by contacting the electrodes 23 and applying ultrasonic waves from the upper surface of the semiconductor element 21.

  As described above, the insulating substrate 11 is formed of an electrically insulating material such as a ceramic material, an organic resin, or a composite material of an inorganic powder and an organic resin.

  When the insulating substrate 11 is made of, for example, an aluminum oxide sintered body, it can be manufactured as follows. First, an appropriate organic binder and solvent are added to and mixed with raw material powders such as aluminum oxide, silicon oxide, calcium oxide, and magnesium oxide to produce a slurry ceramic slurry, and this ceramic slurry is subjected to a doctor blade method, a calender roll method, etc. A plurality of ceramic green sheets (not shown) are formed by adopting the sheet forming technique to form a sheet. Thereafter, the ceramic green sheets are laminated in a predetermined order and fired at a high temperature of about 1600 ° C. in a reducing atmosphere, whereby the insulating substrate 11 is manufactured.

  Further, if the insulating substrate 11 is made of an organic resin, for example, an uncured resin material such as an epoxy resin or a polyimide resin is applied to a glass cloth and processed into a sheet shape, and then heat or light (ultraviolet) is used. It is manufactured by adding and curing. Alternatively, a multilayer insulating substrate 11 may be manufactured by using a cured resin material as a base material and sequentially applying and curing an uncured organic resin such as an epoxy resin on the surface.

  The underlying conductor layer 13 (13a, 13b) to be the electrode pad 12 is made of a metal material such as tungsten, molybdenum, manganese, copper, silver, palladium, or gold, and forms such as a metallized layer, a vapor deposition layer, a metal foil, or a plating layer Thus, the insulating substrate 11 is formed.

  If the base conductor 13 (13a, 13b) is made of, for example, a tungsten metallized layer, a metal paste prepared by adding an organic solvent, a resin binder, or the like to tungsten powder is used for the ceramic green sheet serving as the insulating substrate 11. The surface can be formed by printing a predetermined pattern by a printing method such as a screen printing method.

  Further, if the underlying conductor layer 13 (13a, 13b) is made of, for example, copper metal foil (copper foil), a copper foil is used on the surface of the insulating substrate 11 made of a cured organic resin, and an adhesive is used. After the deposition, the film can be formed by etching and processing into a predetermined pattern.

  In order to form such a base conductor layer 13 (13a, 13b) at a position where it contacts and faces the protruding electrode 23 on the lower surface of the semiconductor element 21 mounted on the mounting portion 11a, for example, A positioning method such as aligning the screen printing plate with the insulating substrate 11 with reference to the outer edge of the insulating substrate 11 or a positioning mark (not shown) formed in advance on the upper surface of the insulating substrate 11. Can be used.

  The underlying conductor layer 13 (13a, 13b) may be formed by combining a metallized layer, a vapor deposition layer, a metal foil, and a plating layer. In this case, for example, after the first layer (not indicated) made of a metallized layer or metal foil is formed on the surface of the insulating substrate 11 by the method as described above, nickel or gold is formed on the surface of the metallized layer or metal foil. The base conductor layer 13 (13a, 13b) is formed by depositing a plating layer of copper, palladium, etc. as a second layer (no symbol) by an electrolytic plating method or an electroless plating method.

  In the example of this embodiment, since the central portion 12a and the outer peripheral portion 12b of the electrode pad 12 are separated by the gap 12c reaching the surface of the insulating substrate 11, the underlying conductor layer 13 (13a, 13a, 13b) is divided into a portion 13a corresponding to the central portion 12a and a portion 13b corresponding to the outer peripheral portion 12b, but the underlying conductor layer 13 (13a, 13b) is one connected pattern (circular shape, elliptical shape, square shape). It may be formed in a shape or the like.

  When the wiring conductor as described above is formed on the insulating substrate 11, the wiring conductor is made of the same material as that of the underlying conductor layer 13 (13a, 13b) and is attached to the insulating substrate 11 by the same method. Can be formed.

  Next, as shown in FIG. 2B, the central portion 12a of the region where the protruding electrode 23 abuts on the surface of the underlying conductor layer 13 (13a, 13b) is lower than the outer peripheral portion 12b, and the central portion The electrode pad 12 is formed by depositing a plating layer 14 (14a, 14b) against which the protruding electrode (not shown in FIG. 2) abuts so that an annular gap 12c is provided between the outer periphery 12b and the outer periphery 12b. To do.

  On the surface of the underlying conductor layer 13 (13a, 13b), the central portion 12a of the region where the protruding electrodes abut is lower than the outer peripheral portion 12b, and an annular gap 12c is formed between the central portion 12a and the outer peripheral portion 12b. In order to deposit the plating layer 14 (14a, 14b) so as to be provided, for example, a portion 13a corresponding to the central portion 12a of the underlying conductor layer 13 (13a, 13b) and a portion 13b corresponding to the outer peripheral portion 12b are provided. After depositing the first plating layer (no symbol) on both sides with a constant thickness, the portion corresponding to the central portion 12a is masked with a resin material or the like, and only the portion 13b corresponding to the outer peripheral portion 12b is masked. For example, a method of adding and depositing two plating layers (without reference numerals) can be used.

  Further, when the underlying conductor layer 13 (13a, 13b) is formed in a single connected pattern, the portion corresponding to the gap 12c is masked and the plating layer 14 (14a, 14b) is deposited. Just do it.

  Further, since it is difficult to mask a narrow portion corresponding to the gap 12c, the electrode pad 12 may be formed as follows. First, as shown in FIG. 3 (a), a masking material made of a photo-curing resin or the like in a range from the outer periphery of the underlying conductor layer 13 formed by one connected pattern to the outer periphery of the portion corresponding to the central portion 12a. Mask with M to deposit the first plating layer 14a. Thereafter, the masking material M is removed. Next, as shown in FIG. 3B, the range from the center (center) of the underlying conductor layer 13 to the inner periphery of the portion corresponding to the outer peripheral portion 12b is masked with a masking material M, and the second plating layer 14b. Is attached such that the outer peripheral portion 12b is higher than the central portion 12a. Then, as shown in FIG. 3C, by removing the masking material M with a solvent or the like, the outer peripheral portion 12b is higher than the central portion 12a (the central portion 12a is lower than the outer peripheral portion 12b), thereby forming the electrode pad 12. Is done. FIGS. 3A to 3C are cross-sectional views showing other examples of the embodiment of the method for manufacturing a semiconductor element mounting substrate according to the present invention in the order of steps. 3, parts similar to those in FIG. 2 are denoted by the same reference numerals.

  The plating layer 14 (14a, 14b) to be deposited is suitably made of a metal material such as nickel, copper, or gold. By depositing such a plating layer 14 (14a, 14b), it is possible to effectively prevent the oxidative corrosion of the electrode pad 12, and to join the protruding electrode 23 of the semiconductor element 21 by ultrasonic bonding. Is easier and more robust.

  In the above manufacturing method, before the step of forming the electrode pad 12 by depositing the plating layer 14 (14a, 14b), for example, as shown in FIG. 4A, the underlying conductor layer 13 (13a, 13b) is formed. ) Are formed so that the portions 13a and 13b corresponding to the central portion 12a and the outer peripheral portion 12b are electrically independent with the gap 12c interposed therebetween, and the outer periphery of the underlying conductor layer 13 (13a and 13b) is formed on the insulating substrate 11. In the case of providing the step of forming the lead wire 15 for plating from only the portion corresponding to the portion 12b to the outer edge of the insulating substrate 11, the central portion 12a of the region where the protruding electrode 23 abuts from the outer peripheral portion 12b by the above-described step. And a method for manufacturing a semiconductor element mounting substrate 19 having an electrode pad 12 having a low gap and an annular gap 12c provided between the central portion 12a and the outer peripheral portion 12b. It can be.

  That is, the underlying conductor layer 13 (13a) is formed such that the gap 12c is electrically independent and the portions corresponding to the central portion 12a and the outer peripheral portion 12b of the electrode pad 12 are electrically independent across the gap 12c. , 13b), as shown in FIG. 4 (b), the plating layer 14bb can be applied only to the portion 13b corresponding to the outer peripheral portion 12b by the electrolytic plating method. In addition, as shown in FIG. 4C, plating layers 14a and 14ba can be deposited on the entire base conductor layer 13 including the portion 13a corresponding to the central portion by an electroless plating method. The plating layer 14a can be applied to the portion 13a corresponding to the central portion 12a with a predetermined thickness.

  Therefore, for example, in addition to the plating layer 14ba deposited by the electroless plating method, the portion 13b corresponding to the outer peripheral portion 12b on which the plating layer 14bb can be deposited by the electrolytic plating method includes the portion 13a corresponding to the central portion 12a. It is possible to deposit the plating layer 14b (14ba, 14bb) thicker (higher) than that. Further, even if the electroless plating layer 14ba is not deposited on the portion 13b corresponding to the outer peripheral portion 12b, if the conditions (time, current density, etc.) of the electroplating are adjusted, the electroplating method alone is sufficiently thick (high) It is also easy to form a plating layer (not shown).

  Further, in this case, a process such as masking is not required. For example, a plating jig terminal (not shown) for supplying a plating current is simply connected to the lead wire 15 for plating. The thick plating layer 14b can be applied only to the portion 13b corresponding to the outer peripheral portion 12b of the underlying conductor layer 13 (13a, 13b). Therefore, it is easy to form the electrode pad 12 in which the central portion 12a of the region where the protruding electrode 23 abuts is lower than the outer peripheral portion 12b. FIGS. 4A to 4C are cross-sectional views showing enlarged main parts in order of processes in another example of the embodiment of the method for manufacturing the semiconductor element mounting substrate 19 shown in FIG. 4, parts similar to those in FIG. 1 are denoted by the same reference numerals.

  The lead wire 15 for plating can be formed by the same method using the same material as that of the base conductor layer 13 (13a, 13b) described above. In the case where a wiring conductor is formed on the insulating substrate 11, it is formed simultaneously with the wiring conductor (for example, using the same screen printing plate) to ensure good productivity of the semiconductor element mounting substrate 19. You may do it.

  For electroless plating, for example, if it is a nickel plating layer, a nickel compound such as nickel sulfate or nickel chloride and a reducing agent such as sodium hypophosphite or dimethylamine borane (DMAB) Can be carried out using an electroless nickel plating solution containing, as a main component, and a complexing agent, stabilizer, pH adjuster and the like.

  In this case, the plating layers 14a and 14ba (nickel) deposited by the electroless plating solution using sodium hypophosphite as the reducing agent have a hardness (micro Vickers hardness) due to the action of the eutectoid phosphorus component. It is as high as about 600 to 700, and is harder than the hardness (about 400 to 500) of the plating layer 14bb (nickel) deposited by the electrolytic plating method. For this reason, attenuation of ultrasonic energy applied when the electrode pad 12 and the protruding electrode 23 are bonded by ultrasonic bonding can be further reduced, which is effective in increasing the bonding strength.

  When the semiconductor element mounting substrate 19 is manufactured by this method, since the central portion 12a and the outer peripheral portion 12b of the electrode pad 12 are electrically independent, one of them is the protruding electrode 23 (electrode terminal 22). Can function as a conductive path that is electrically connected to an external electric circuit, and the other functions as a reinforcing pad that reinforces the strength of the joint.

  Further, in the case of this manufacturing method, after the plating layer 14bb is deposited by the electrolytic plating method, a step of removing the exposed portion of the lead wire 15 for plating from the surface of the insulating substrate 11 by a method such as polishing is added. You may do it.

  FIG. 4 shows an example in which the electrolytic plating layer 14bb is first deposited on the portion 13b corresponding to the outer peripheral portion of the underlying conductor layer 13, but the plating layers 14ba and 14a by the electroless plating method are first shown. Is applied to only the portion 13a corresponding to the entire region or the central portion of the base conductor layer 13 (13a, 13b), and then the plating layer 14bb by the electrolytic plating method is applied only to the portion 13b corresponding to the outer peripheral portion. May be.

  In the above manufacturing method, before the step of forming the electrode pad 12 by depositing the plating layer 14 (14a, 14b), for example, as shown in FIG. 5A, the underlying conductor layer 13 (13a, 13b) is formed. ) Are formed so that the portions 13a and 13b corresponding to the central portion 12a and the outer peripheral portion 12b are electrically independent with the gap 12c interposed therebetween, and the center of the underlying conductor layer 13 (13a and 13b) is formed on the insulating substrate 11. Forming a first lead wire 16a for plating from at least the portion 13a corresponding to the central portion 12a to the outer edge of the insulating substrate 11 among the portions 13a and 13b corresponding to the portion 12a and the outer peripheral portion 12b, and corresponding to the outer peripheral portion 12b And forming a second lead wire 16b for plating from only the portion 13b to the outer edge of the insulating substrate 11, the central portion 12a of the region in contact with the protruding electrode 23 is the outer peripheral portion 12b. Lower and central The method of manufacturing a semiconductor element mounting board 19 having an electrode pad 12 a gap 12c is provided annularly between the 12a and the outer peripheral portion 12b, can be more easily and highly productive manufacturing method.

  That is, the underlying conductor layer 13 (13a) is formed such that the gap 12c is electrically independent and the portions corresponding to the central portion 12a and the outer peripheral portion 12b of the electrode pad 12 are electrically independent across the gap 12c. , 13b), as shown in FIGS. 5 (b) and 5 (c), a plating layer 14 is separately formed on the portion corresponding to the central portion 12a and the portions 13a, 13b corresponding to the outer peripheral portion 12b by electrolytic plating. (14a, 14b) can be deposited. In addition, the entire base conductor layer 13 (13a, 13b) including the portion corresponding to the central portion 12a is supplied with a plating current via the first plating lead wire 16a, and corresponds to at least the central portion 12a. The plating layer 14a can be applied to the portion 13a to be formed with a predetermined thickness. Then, a thicker plating layer 14b can be applied only to the portion 13b corresponding to the outer peripheral portion 12b of the underlying conductor layer 13 (13a, 13b) via the second lead wire 16b for plating. Therefore, it is easy to make the outer peripheral part 12b higher than the central part 12a (thickening the plating layer 14b). 5 (a) to 5 (c) are cross-sectional views showing enlarged main portions in order of processes in another example of the embodiment of the method for manufacturing the semiconductor element mounting substrate 19 shown in FIG. 5, parts similar to those in FIG. 1 are denoted by the same reference numerals. FIG. 5 shows an example in which the plating layer 14a is first deposited on the portion 13a corresponding to the center portion of the underlying conductor layer 13 (13a, 13b), but the plating is first applied to the portion 13b corresponding to the outer peripheral portion. Layer 14b may be deposited.

  The first and second lead wires 16a and 16b for plating can be formed by the same method using the same material as the above-described base conductor layer 13 (13a and 13b). In the case where a wiring conductor is formed on the insulating substrate 11, it is formed simultaneously with the wiring conductor (for example, using the same screen printing plate) to ensure good productivity of the semiconductor element mounting substrate 19. You may do it.

  Also in this case, a process such as masking is not necessary. For example, the plating layer 14 (14a, 14b) can be obtained by simply connecting a terminal of a plating jig for supplying a plating current to a different lead wire. ) Can be selected (parts corresponding to the central part 12a and the outer peripheral part 12b). Therefore, in the case of this manufacturing method, current can be supplied only to the portion 13b corresponding to the outer peripheral portion 12b that is higher in the electrode pad 12, that is, the plating layer 14b needs to be deposited thicker. Thus, it is easy to form the electrode pad 12 in which the central portion 12a of the region where the protruding electrode 23 abuts is lower than the outer peripheral portion 12b.

  Even when the semiconductor element mounting substrate 19 is manufactured by this method, since the central portion 12a and the outer peripheral portion 12b of the electrode pad 12 are electrically independent, one of them has the protruding electrode 23 (electrode terminal 22) externally. It is possible to function as a conductive path that is electrically connected to the electrical circuit, and the other functions as a reinforcing pad that reinforces the strength of the joint.

  In the case of this manufacturing method, after the plating layer 14 (14a, 14b) is deposited, the exposed portions of the first and second lead lines 16a, 16b are polished from the surface of the insulating substrate 11 or the like. It is also possible to add a process to be removed by.

  Further, such a semiconductor element mounting substrate 19 is manufactured in the form of a square plate-like multi-piece substrate (not shown) in which a plurality of substrate regions to be the semiconductor element mounting substrate 19 are arranged vertically and horizontally. The first and second lead wires for plating (not shown) are respectively arranged on different sides of the outer periphery of the multi-chip substrate, the first being the first and the second being the second, respectively. It may be formed by drawing.

  In this case, the first and second lead lines for plating may be formed by being drawn out on each of two opposing sides of the four sides of the quadrangular multi-piece substrate. In this case, the multi-cavity substrate is held by sandwiching two opposing sides of the multi-cavity substrate from above and below with a conduction pin of a plating jig (so-called rack), and the predetermined first or second plating is performed. It is possible to select a lead-out line for electrical connection with an external power source easily and reliably, for example, by reducing the occurrence of problems such as artificially incorrect conduction. Therefore, the workability of the plating process can be improved, and the manufacturing method can be further improved in productivity.

  The electrode pad 12 is divided into a central portion 12a and an outer peripheral portion 12b across a gap 12c (the gap 12c reaches the upper surface of the insulating substrate 11), and the central portion 12a and the outer peripheral portion 12b When the manufacturing method is adopted such that the electrode pad 12 is electrically independent with the gap 12c interposed therebetween, the electrode pad 12 is, for example, electrically connected to the above-described wiring conductor only at the central portion 12a. You may form as. In this case, only the central portion 12a functions as a conductive path for connecting the protruding electrode 23 (electrode terminal 22) of the electrode pad 12 to an external electric circuit, and the outer peripheral portion 12b is connected to the protruding electrode 23. It functions to reinforce the bonding with the electrode pad 12 as described above.

  An insulating substrate is made of an aluminum oxide sintered body, and a circular electrode pad having an outer diameter of 200 μm is formed on the surface thereof by sequentially depositing a tungsten metallization layer and a nickel / gold plating layer, A substrate for mounting a semiconductor element was produced. Using this semiconductor element mounting substrate, the mounting reliability of the semiconductor element by ultrasonic bonding was tested. Further, as a comparative example, a conventional semiconductor element mounting substrate was prepared in which an electrode pad having a similar outer shape and a flat surface on which a protruding electrode is bonded is formed on a similar insulating substrate.

  The insulating substrate is made of aluminum oxide as a main raw material, and a raw material powder prepared by adding silicon oxide, magnesium oxide and calcium oxide is kneaded with an organic solvent and an organic binder, and then molded into a sheet shape by a doctor blade method. A ceramic green sheet was prepared, and this ceramic green sheet was laminated and then fired at 1600 ° C.

  The insulating substrate is a square plate with a side length of 25 mm and a thickness of 2 mm. The square area with a side length of 15 mm in the center of the upper surface is the mounting area of the semiconductor element. The electrode pad was formed here.

  The electrode pad was formed to have a circular shape with a diameter of 40 μm at the center, a gap with a width of 40 μm on the outside, and the outside of the gap as an outer peripheral part in contact with the protruding electrode of the semiconductor element. The gap was formed in an annular shape having a width of 50 μm, and the entire outer shape of each electrode pad was a square shape having a side length of 200 μm (0.2 mm). The gap was formed so as to reach the upper surface of the insulating substrate, and the central portion and the outer peripheral portion were made electrically independent.

  Each electrode pad had a central part height of about 15 μm and an outer peripheral part height of about 35 μm. The central portion was formed by sequentially depositing a nickel plating layer having a thickness of about 4 μm and a gold plating layer having a thickness of about 1 μm on the surface of a tungsten metallization layer having a thickness of about 10 μm. The outer peripheral portion was formed by sequentially depositing a nickel plating layer having a thickness of about 24 μm and a gold plating layer having a thickness of about 1 μm on the surface of a tungsten metallization layer having a thickness of about 10 μm. The nickel plating layer at the outer peripheral portion was deposited in two layers (a primary plating layer having a thickness of 4 μm and a secondary plating layer having a thickness of 20 μm) in order to relieve stress in the plating layer.

  The tungsten metallized layer was formed by printing tungsten metal paste on the surface of the ceramic green sheet by screen printing and co-firing with an insulating substrate. The nickel plating layer was formed by an electrolytic plating method using a watt bath, and the gold plating layer was formed by an electrolytic plating method using a cyan-based gold plating bath.

  In each mounting part, 256 electrode pads were formed in a 16 × 16 array.

  The mounting reliability is determined by ultrasonic bonding the bump electrode and electrode pad, and then applying a thermal cycle test (−40 to + 120 ° C, 1000 cycles) to repeatedly apply thermal stress to the bonded portion, and then peeling the bonded portion. This was done by checking the appearance. The number of samples was 10 semiconductor device mounting substrates (the number of electrode pads was 256 × 10 = 2560).

  As a comparative example, a semiconductor element mounting substrate on which a square electrode pad having a side length of 200 μm (0.2 mm) with no gap was formed as described above was manufactured. The test was performed in the same manner as the mounting substrate.

  As a result, in the semiconductor element mounting substrate of the present invention, no peeling occurred between the protruding electrode and the electrode pad, and no abnormality was found in the connection state, whereas in the comparative example, about 5% The protruding electrode peeled off from the electrode pad. Thus, it was confirmed that the semiconductor element mounting substrate and the semiconductor device of the present invention have high connection strength and mounting reliability between the protruding electrode and the electrode pad.

(A) is a top view which shows an example of embodiment of the board | substrate for semiconductor element mounting of this invention, (b) is sectional drawing which shows an example of embodiment of the board | substrate for semiconductor element mounting of this invention, and a semiconductor device It is. (A) And (b) is sectional drawing which shows an example of embodiment of the manufacturing method of the board | substrate for a semiconductor element mounting of this invention in order of a process, respectively. (A)-(c) is the principal part expanded sectional view which shows the other example of embodiment of the manufacturing method of the board | substrate for semiconductor element mounting of this invention in order of a process, respectively. (A)-(c) is the principal part expanded sectional view which shows the other example of embodiment of the manufacturing method of the board | substrate for semiconductor element mounting of this invention in order of a process, respectively. (A)-(c) is the principal part expanded sectional view which shows the other example of embodiment of the manufacturing method of the board | substrate for semiconductor element mounting of this invention in order of a process, respectively.

Explanation of symbols

11 ・ ・ ・ ・ ・ ・ Insulating substrate
11a ・ ・ ・ ・ ・ Mounting part
12 ・ ・ ・ ・ ・ ・ Electrode pads
12a: Central part
12b ... outer periphery
12c: Clearance
13 ・ ・ ・ ・ ・ ・ Base conductor layer
13a: The portion corresponding to the center of the underlying conductor layer
13b: The portion corresponding to the outer periphery of the underlying conductor layer
14 ・ ・ ・ ・ ・ ・ Plating layer
14a: Plated layer in the center
14b: plating layer on the outer periphery
15 ····· Plating lead wire
16a: First lead wire for plating
16b: Second lead wire for plating
19 ・ ・ ・ ・ ・ ・ Semiconductor element mounting board
21 ・ ・ ・ ・ ・ ・ Semiconductor elements
22 ・ ・ ・ ・ ・ ・ Electrode terminal
23 ・ ・ ・ ・ ・ ・ Projection electrode
30 ・ ・ ・ ・ ・ ・ Semiconductor device

Claims (9)

A mounting part in which a plurality of electrode pads are formed on the upper surface of the insulating substrate, each of which has a plurality of electrode terminals formed on the lower surface, and a plurality of electrode pads respectively facing the electrode terminals for mounting a semiconductor element having a protruding electrode on the electrode terminal. A substrate for mounting a semiconductor element, wherein the protruding electrode is brought into contact with the electrode pad and ultrasonic waves are applied from the upper surface of the semiconductor element to bond the protruding electrode to the electrode pad, The electrode pad is for mounting a semiconductor element, wherein a central portion of a region where the protruding electrode contacts is lower than an outer peripheral portion, and an annular gap is provided between the central portion and the outer peripheral portion. substrate. 2. The substrate for mounting a semiconductor element according to claim 1, wherein the gap is wider on the side intersecting with the left-right vibration of the protruding electrode due to the ultrasonic wave than other portions. 2. The semiconductor element mounting substrate according to claim 1, wherein the electrode pad is provided with a plating layer having a thickness different between the central portion and the outer peripheral portion on a base conductor layer. A plurality of electrode terminals are formed on the upper surface of the insulating substrate, and the protruding electrodes are mounted on the electrode terminals so as to be mounted on the electrode terminals. Forming a base conductor layer to be a plurality of electrode pads to which sound waves are applied and bonded;
The projecting electrode is formed such that a central portion of a region where the projecting electrode is in contact with the surface of the base conductor layer is lower than an outer peripheral portion, and an annular gap is provided between the central portion and the outer peripheral portion. A method of manufacturing a substrate for mounting a semiconductor element, comprising: depositing a plating layer on which the electrode contacts, and forming the electrode pad. Before the step of depositing the plating layer and forming the electrode pad,
The base conductor layer is formed such that portions corresponding to the central portion and the outer peripheral portion are electrically independent with the gap therebetween, and the insulating substrate corresponds to the outer peripheral portion of the base conductor layer. 5. The method of manufacturing a substrate for mounting a semiconductor element according to claim 4, further comprising a step of forming a lead wire for plating from only a portion to an outer edge of the insulating substrate. Before the step of depositing the plating layer and forming the electrode pad,
The base conductor layer is formed such that portions corresponding to the central portion and the outer peripheral portion are electrically independent with the gap therebetween, and the central portion and the outer periphery of the base conductive layer are formed on the insulating substrate. Forming a first lead wire for plating from at least a portion corresponding to the central portion of the portion corresponding to the portion to an outer edge of the insulating substrate;
5. The method of manufacturing a substrate for mounting a semiconductor element according to claim 4, further comprising: forming a second lead wire for plating from only a portion corresponding to the outer peripheral portion to an outer edge of the insulating substrate. A mounting part in which a plurality of electrode pads are formed on the upper surface of the insulating substrate, each of which has a plurality of electrode terminals formed on the lower surface, and a plurality of electrode pads respectively facing the electrode terminals for mounting a semiconductor element having a protruding electrode on the electrode terminal. A plurality of electrode terminals formed on the lower surface and provided with protruding electrodes, and the protruding electrodes are bonded to the electrode pads by ultrasonic bonding. And a semiconductor element, wherein an annular gap is provided between a central portion and an outer peripheral portion of a bonding region between the protruding electrode and the electrode pad. 8. The semiconductor device according to claim 7, wherein the annular gap has a wider side intersecting with the left-right vibration of the protruding electrode due to the ultrasonic wave applied during the ultrasonic bonding. The electrode pad is characterized in that a plating layer having a thickness different between the central portion and the outer peripheral portion is deposited on a base conductor layer so that the central portion is lower than the outer peripheral portion. The semiconductor device according to claim 7.

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