JP5106197B2 - Semiconductor device and manufacturing method thereof - Google Patents

Description

  The present invention relates to a semiconductor device and a manufacturing method thereof, and more particularly to a semiconductor device in which connection pads on a wiring board and gold bumps provided on electrode terminals of a semiconductor element are bonded and a manufacturing method thereof.

  Conventionally, there is a flip chip type semiconductor device as a semiconductor device. In the flip chip type semiconductor device, a connection pad provided on a wiring board is opposed to an electrode terminal of a semiconductor element, and these are electrically connected through, for example, gold bumps provided in advance on the electrode terminal of the semiconductor element. It is a connected semiconductor device.

  FIG. 8 is a schematic cross-sectional view showing an example of a conventional flip-chip type semiconductor device, in which 110 is a wiring board and 120 is a semiconductor element. FIG. 9 is a top view of the wiring board 110. The wiring board 110 is formed by laminating a wiring conductor 102 made of copper and a plurality of insulating layers 101b made of thermosetting resin on both surfaces of an insulating plate 101a made by impregnating a glass cloth with a thermosetting resin, for example. A solder resist layer 103 made of a thermosetting resin is deposited on the insulating layer 101b and the wiring conductor 102 so as to expose a part of the wiring conductor 102, and the wiring exposed from the solder resist layer 103 is covered. A part of the conductor 102 forms a connection pad 107 for electrical connection with the semiconductor element 120. As shown in FIG. 9, the connection pad 107 is a rectangle arranged in a position corresponding to the outer peripheral portion of the semiconductor element 120.

  The semiconductor element 120 has an electrode terminal 121 on the lower surface, and a gold bump 122 is provided on the electrode terminal 121. Then, the gold bump 122 and the connection pad 107 of the wiring substrate 110 are joined to form a flip chip type semiconductor device. Normally, an underfill (not shown) made of a thermosetting resin is filled between the upper surface of the wiring board 110 and the semiconductor element 120.

  As shown in the enlarged view of the main part in FIG. 8, the gold bump 122 has a large-diameter base 122 a joined to the electrode terminal 121 and a small-diameter protrusion 122 b erected on the base 122 a. When the pitch of the electrode terminals 121 is narrow, the protrusion 122b is bonded to the connection pad 107 of the wiring board 110. The connection pad 107 of the wiring board 110 is formed with a width equal to or wider than the diameter of the protrusion 122b of the gold bump 122, and the surface thereof is plated with gold. Then, the protrusion 122b of the gold bump 122 is brought into contact with the upper surface of the connection pad 107 and ultrasonic vibration is applied while applying appropriate heat and load, so that the protrusion 122b and the connection pad 107 are ultrasonically welded. Be joined.

When the gold bump 122 and the connection pad 107 are connected by such a method, it is necessary to finely control the temperature, load, ultrasonic vibration output, and the like when ultrasonic welding is performed. However, the wiring board 110 usually has some warping and waviness, and the height of the connection pad 107 varies due to these warping and waviness. Further, the gold bump 122 itself is usually formed by ball bonding one end of a gold wire to the electrode terminal 121 of the semiconductor element 120 and then tearing it, and the height thereof has some variation. Therefore, no matter how finely controlled the temperature, load, ultrasonic vibration output, etc., when these are ultrasonically welded, all the protrusions 122b of the gold bumps 122 and the connection pads 107 of the wiring board 110 are bonded satisfactorily. It is extremely difficult, and the protrusion 122b is largely crushed by plastic deformation caused by friction with the connection pad 107, and contacts the adjacent connection pad 107 and the gold bump 122 bonded thereto, causing an electrical short circuit, There is a problem in that the protrusion 122b and the connection pad 107 are not sufficiently bonded to each other and peeling occurs between the two to cause electrical disconnection.
JP 2002-246417 A

  An object of the present invention is to provide a semiconductor device in which a connection pad of a wiring board and an electrode terminal of a semiconductor element are well connected via a gold bump, and a manufacturing method thereof.

  As a result of intensive studies to solve the above problems, the present inventor has made the width of the connection pad of the wiring board narrower than the diameter of the protrusion of the gold bump provided on the electrode terminal of the semiconductor element. Without finely controlling the temperature, load, output of ultrasonic vibration, etc. when ultrasonic welding the gold bumps of the semiconductor element and the connection pads of the wiring board, for example, to the connection pads of the wiring board or the gold bumps of the semiconductor element The present inventors have completed the present invention by finding a new finding that even if there is some height variation, all gold bumps and connection pads can be joined well without causing an electrical short circuit or disconnection.

That is, the semiconductor device according to the present invention has the following configuration.
(1) A semiconductor device in which a connection pad on a wiring board and a gold bump provided on an electrode terminal of a semiconductor element are joined, wherein the gold bump is joined to the electrode terminal with a large diameter base and the base A protrusion having a small diameter that is erected on the connection pad and is connected to the connection pad, wherein the connection pad has a width of a portion bonded to the protrusion that is narrower than a diameter of the protrusion. Semiconductor device.
(2) The semiconductor device according to (1), wherein a gold plating layer is deposited on a surface of the connection pad, and the gold plating layer and the protrusion are directly bonded.
(3) The semiconductor device according to (2), wherein the connection pad is embedded in the protrusion.
(4) The semiconductor device according to (1), wherein the protrusion and the connection pad are joined via solder.

Moreover, the manufacturing method of the semiconductor device in this invention consists of the following structures.
(5) A method of manufacturing a semiconductor device in which a connection pad on a wiring board and a gold bump provided on an electrode terminal of a semiconductor element are connected, and the diameter bonded to the electrode terminal of the semiconductor element as the gold bump Providing a gold bump having a large base and a small-diameter protrusion standing on the base, and forming a connection pad having a width smaller than the diameter of the protrusion as the connection pad; A method of manufacturing a semiconductor device, comprising bonding the protrusion and the connection pad.
(6) The method for manufacturing a semiconductor device according to (5), wherein a gold plating layer is deposited on the surface of the connection pad, and the gold plating layer and the protrusion are directly bonded. .
(7) The method for manufacturing a semiconductor device according to (6), wherein the connection pads are joined so as to be embedded in the protrusions.
(8) The method for manufacturing a semiconductor device according to (5), wherein the protruding portion and the connection pad are joined via solder.

According to the semiconductor device and the manufacturing method thereof of the present invention, since the connection pad of the wiring board is narrower than the diameter of the protrusion of the gold bump provided on the electrode terminal of the semiconductor element, the semiconductor element is connected to the connection pad of the wiring board. When the gold bumps are ultrasonically welded, the plastic deformation of the protrusions of the gold bumps mainly occurs only in the portion that contacts the connection pad narrower than the diameter of the protrusions, so even when a large load is applied, Although the protrusion deforms until the connection pad is embedded in the protrusion of the gold bump, the protrusion does not undergo large plastic deformation around the connection pad. There is no.
Further, when a gold plating layer is deposited on the surface of the connection pad, the connection pad and the gold bump are firmly bonded via the gold plating layer.
Furthermore, when the connection pad is embedded in the protrusion, the connection pad and the protrusion are bonded to each other via a three-dimensional bonding surface, so that the connection pad is bonded extremely firmly.
Further, when connecting the protrusion and the connection pad via solder, the solder stays between the protrusion having a small diameter and the connection pad having a width smaller than the diameter of the protrusion, so that the solder spreads widely. Absent.
Therefore, according to the semiconductor device and the manufacturing method thereof of the present invention, it is possible to finely control the temperature, load, output of ultrasonic vibration and the like when ultrasonic welding the gold bumps of the semiconductor element and the connection pads of the wiring board. Even if there are some height variations in the connection pads of the wiring board and the gold bumps of the semiconductor element, all the gold bumps and the connection pads are well bonded without causing an electrical short circuit or disconnection. An apparatus can be provided.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, an embodiment of a semiconductor device and a manufacturing method thereof according to the invention will be described in detail with reference to the drawings. FIG. 1 is a schematic cross-sectional view showing a semiconductor device according to the present embodiment in which peripheral type semiconductor elements are mounted by flip-chip connection, and FIG. 2 is a top view showing a wiring board in the semiconductor device of FIG. 3 is an enlarged view of the main part in FIG. 1, and FIG. 4 is an enlarged view of the main part in FIG.

  The semiconductor device according to the present embodiment is configured by mounting a semiconductor element 20 on the upper surface of a wiring board 10 as shown in FIG. The wiring board 10 is formed by alternately laminating insulating layers 1b and wiring conductors 2b mainly made of copper plating on the upper and lower surfaces of the insulating plate 1a on which wiring conductors 2a made mainly of copper are disposed from the upper surface to the lower surface, A protective solder resist layer 3 is deposited on the outermost surface.

  The insulating plate 1a has a thickness of about 0.3 to 1.5 mm. For example, an electrically insulating material obtained by impregnating a glass cloth in which glass fiber bundles are woven vertically and horizontally with a thermosetting resin such as bismaleimide triazine resin or epoxy resin. And functions as a core member of the wiring board 10.

  A plurality of through holes 4 having a diameter of about 0.05 to 0.3 mm are formed in the insulating plate 1a from the upper surface to the lower surface. A wiring conductor is formed on the upper and lower surfaces of the insulating plate 1a and the inner surface of the through hole 4. 2a is applied. The wiring conductor 2a is mainly formed of copper foil on the upper and lower surfaces of the insulating plate 1a, and is formed of electroless copper plating and electrolytic copper plating thereon on the inner surface of the through hole 4.

  The through hole 4 is filled with an embedded resin 5 made of a thermosetting resin such as an epoxy resin, and the wiring conductors 2 a formed on the upper and lower surfaces of the insulating plate 1 a are connected to each other in the through hole 4. It is electrically connected via 2a.

  Such an insulating plate 1a is obtained by sticking a copper foil for the wiring conductor 2a on the upper and lower surfaces of a sheet of glass fabric impregnated with an uncured thermosetting resin, and then thermally curing the sheet, The through hole 4 is drilled from the bottom to the bottom.

  In addition, the wiring conductor 2a has a copper foil having a thickness of about 3 to 50 μm adhered to the entire upper and lower surfaces of the sheet for the insulating plate 1a, and the through holes 4 are drilled in the copper foil and the insulating plate 1a. Electroless copper plating and electrolytic copper plating are sequentially applied to the inner surface of the through hole 4 and the surface of the copper foil, and then the through hole 4 is filled with the resin 5, and then the upper and lower copper foils and copper plating are photographed. The insulating plate 1a is formed on the upper and lower surfaces and the inner surface of the through hole 4 by etching into a predetermined pattern using a lithography technique.

  The embedded resin 5 is used to form the insulating layer 1b immediately above and below the through hole 4 by closing the through hole 4. An uncured paste-like thermosetting resin is placed in the through hole 4. After filling with a screen printing method and thermosetting it, the upper and lower surfaces thereof are polished to be substantially flat.

  The insulating layers 1b laminated on the upper and lower surfaces of the insulating plate 1a have a thickness of about 20 to 60 μm. Similarly to the insulating plate 1a, an electric insulating material in which a glass cloth is impregnated with a thermosetting resin, or an epoxy It consists of an electrically insulating material in which an inorganic filler such as silicon oxide is dispersed in a thermosetting resin such as a resin. Each insulating layer 1b is formed with a plurality of via holes 6 having a diameter of about 30 to 100 μm.

  A wiring conductor 2b made of electroless copper plating and electrolytic copper plating thereon is deposited on the surface of each insulating layer 1b and the inner surface of the via hole 6. Then, the wiring conductor 2b located in the upper layer and the wiring conductor 2b located in the lower layer are electrically connected via the wiring conductor 2b in the via hole 6 with the insulating layer 1b interposed therebetween, thereby forming a three-dimensional high density wiring. Is done.

  Among the plurality of wiring conductors 2 b, a part of the wiring conductor 2 b deposited on the outermost insulating layer 1 b on the upper surface side of the wiring substrate 10 is electrically connected via the electrode terminals 21 of the semiconductor element 20 and the gold bumps 22. A connection pad 7 for connecting a semiconductor element is formed, and a part of the pad 10 deposited on the outermost insulating layer 1b on the lower surface side of the wiring board 10 is electrically connected to the wiring conductor of the external electric circuit board. Connection pads 8 for connection are formed. A solder ball 9 to be bonded to the wiring conductor of the external electric circuit board is welded to the connection pad 8 for external connection.

  As shown in FIG. 2, the connection pads 7 for connecting the semiconductor elements have a predetermined pitch so that the positions corresponding to the outer peripheral portions of the semiconductor elements 20 extend in a direction perpendicular to the outer periphery of the semiconductor elements 20. Are provided side by side, and the central part is narrowed and narrowed. An electrode terminal 21 of the semiconductor element 20 is joined to the semiconductor element 20 via a gold bump 22.

  The wiring conductor 2b including such connection pads 7 is formed by a method called a semi-additive method. In the semi-additive method, for example, a base metal layer for electrolytic plating is formed on the surface of the insulating layer 1b where the via hole 6 is formed by electroless copper plating, and a plating resist layer having an opening corresponding to the wiring conductor 2b thereon Next, electrolytic copper plating is performed on the underlying metal layer exposed from the opening using the underlying metal layer as a power supply electrode to form the wiring conductor 2b, and after removing the plating resist, the exposed underlying metal layer is formed. In this method, each wiring conductor 2b is electrically independent by etching away.

  A solder resist layer 3 is deposited on the outermost insulating layer 1b and the wiring conductor 2b thereon. The solder resist layer 3 is a protective film for protecting the outermost wiring conductor 2b from heat and the external environment. The solder resist layer 3 on the upper surface side exposes the connection pads 7 and also has a lower surface side. The solder resist layers 3 are respectively deposited so as to expose the connection pads 8.

  Further, as shown in FIG. 2, the solder resist layer 3 on the upper surface side has a slit-like opening 3a that exposes the connection pad 7, and has a length corresponding to the width of the opening 3a. A connection pad 7 having a predetermined shape is defined by exposing a part of 2b.

  The semiconductor element 20 is, for example, a semiconductor integrated circuit element, and has a large number of electrode terminals 21 on the outer periphery of the lower surface thereof. As shown in FIG. 3, the gold bump 22 is joined to the electrode terminal 21 and has a large base portion 22a having a diameter of about 50 to 80 μm and a small protrusion having a diameter of about 20 to 40 μm standing on the base portion 22a. Part 22b. And this small diameter protrusion part 22b and the connection pad 7 are joined by ultrasonic welding.

  In the semiconductor device of the present invention, as shown in FIGS. 3 and 4, the width of the portion joined to the gold bump 22 of the connection pad 7 of the wiring board 10 is narrower than the diameter of the protrusion 22 b of the gold bump 22. This is important. By adopting such a configuration, as will be described later, when the gold bumps 22 of the semiconductor element 20 are ultrasonically welded to the connection pads 7 of the wiring substrate 10, the connection pads are not greatly crushed. 7 can be bonded satisfactorily. Therefore, the protrusion 22b contacts the adjacent connection pad 7 and the gold bump 22 bonded thereto to cause an electrical short circuit, or the protrusion 22b and the connection pad 7 are separated to cause an electrical disconnection. There is nothing. If the width of the portion of the connection pad 7 joined to the gold bump 22 exceeds 0.7 times the diameter of the protrusion 22b, the gold bump 22 and the connection pad 7 may be greatly crushed in the protrusion 22b. If it is less than 0.2 times, there is a high risk that the connection pad 7 may be peeled off or disconnected. Therefore, the width of the portion of the connection pad 7 connected to the gold bump 22 is preferably in the range of 0.2 to 0.7 times the diameter of the protrusion 22b. Furthermore, when the connection pad 7 is embedded in the protrusion 22b of the gold bump 22, the connection surface between the connection pad 7 and the protrusion 22b becomes three-dimensional, so that both are bonded extremely firmly. Therefore, the connection pad 7 is preferably in a state of being embedded in the protrusion 22 b of the gold bump 22.

  In order to join the connection pads 7 of the wiring board 10 and the gold bumps 22 of the semiconductor element 20 in this way, the gold bumps of the semiconductor element 20 are formed on the connection pads 7 of the wiring board 10 as shown in FIG. The 22 projections 22b are brought into contact with each other, and a load of about 0.196 to 1.47 N (20 to 150 gf) is applied from the upper surface side of the semiconductor element 20, and the frequency is about 40 to 60 KHz and the output is 0.5 to By applying ultrasonic vibration of about 2 W in the horizontal direction, as shown in FIG. 5 (b), the portion that contacts the connection pad 7 of the projection 22 b is plastically deformed by friction of ultrasonic vibration and welded to the connection pad 7. In addition, a method of embedding the connection pad 7 in the protruding portion 22b is employed. At this time, the plastic deformation of the protrusion 22b mainly occurs only in a portion in contact with the connection pad 7 whose width is narrower than the diameter of the protrusion 22b. Therefore, even if a large load is applied and ultrasonic welding is performed, the protrusion 22b of the gold bump 22 Although the protruding portion 22b is deformed until the connection pad 7 is embedded therein, the protruding portion 22b is further crushed because the protruding portion 22b does not undergo large plastic deformation around the connecting pad 7. There is nothing. Therefore, according to the method for manufacturing a semiconductor device of the present invention, the temperature, load, output of ultrasonic vibration, etc. when ultrasonically welding the gold bumps 22 of the semiconductor element 20 and the connection pads 7 of the wiring substrate 10 are controlled. For example, even if there is some height variation in the connection pads 7 of the wiring substrate 10 and the gold bumps 22 of the semiconductor element 20, all the gold bumps 22 and the connection pads 7 cause an electrical short circuit or disconnection. It can be done with good bonding.

  If a gold plating layer is deposited on the surface of the connection pad 7 of the wiring substrate 10 to a thickness of 0.02 to 1.5 μm, the connection pad 7 of the wiring substrate 10 and the gold bump 22 of the semiconductor element 20 Bonding can be made extremely strong by gold-gold metal bonding. Therefore, it is preferable to deposit a gold plating layer on the surface of the connection pad 7 of the wiring board 10 to a thickness of 0.02 to 1.5 μm.

  Further, under normal circumstances, the gap between the semiconductor element 20 and the wiring board 10 is filled with an underfill (not shown) made of a thermosetting resin such as an epoxy resin, and the semiconductor element 20 is mounted on the wiring board 10. It becomes a semiconductor device.

  The present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the gist of the present invention. For example, in the above-described embodiment, the connection pad 7 The connection pads 7 are formed such that the central portions are constricted and the constricted portions are arranged in a straight line. For example, as shown in FIG. 6, the constricted portions of the connection pads 7 are staggered. The connection pads 7 may be formed so that

  Furthermore, in the above-described embodiment, the connection pads 7 of the wiring board 10 and the gold bumps 22 of the semiconductor element 20 are directly bonded by ultrasonic welding. However, as shown in FIG. The gold bumps 22 of the element 20 may be joined via the solder 23. In this case, since the solder 23 stays between the projection 22b having a small diameter and the connection pad 7 having a width smaller than the diameter of the projection 22b, the solder 23 does not spread greatly laterally. Therefore, also in this case, it is possible to provide a semiconductor device in which all the gold bumps 22 and the connection pads 7 are well bonded without causing an electrical short circuit or disconnection.

It is a schematic sectional drawing which shows the semiconductor device concerning one Embodiment of this invention which mounts a peripheral-type semiconductor element by flip chip connection. It is a top view which shows the wiring board in FIG. FIG. 2 is an essential part enlarged view of the semiconductor device shown in FIG. 1. It is a principal part enlarged view of the wiring board shown in FIG. (A), (b) is a schematic sectional drawing for demonstrating the method to manufacture the semiconductor device shown in FIG. FIG. 5 is an enlarged view of a main part corresponding to FIG. 4 showing another embodiment of the semiconductor device according to the present invention. FIG. 5 is an enlarged view of a main part corresponding to FIG. 3 showing still another embodiment of the semiconductor device according to the present invention. It is a schematic sectional drawing which shows the example of the conventional semiconductor device. It is a top view which shows the wiring board in FIG. It is a top view which shows the wiring board of FIG.

Explanation of symbols

7: Connection pad 10: Wiring board 20: Semiconductor element 21: Electrode terminal 22: Gold bump 22a: Base 22b: Protrusion 23: Solder

Claims (8)

  A semiconductor device in which a connection pad on a wiring board and a gold bump provided on an electrode terminal of a semiconductor element are bonded to each other, wherein the gold bump is connected to the electrode terminal and a large-diameter base is formed on the base. A semiconductor device comprising: a projection having a small diameter joined to the connection pad, wherein the connection pad has a width of a portion joined to the projection narrower than a diameter of the projection. .   2. The semiconductor device according to claim 1, wherein a gold plating layer is deposited on a surface of the connection pad, and the gold plating layer and the protrusion are directly bonded.   The semiconductor device according to claim 2, wherein the connection pad is embedded in the protrusion.   The semiconductor device according to claim 1, wherein the protrusion and the connection pad are joined via solder.   A method of manufacturing a semiconductor device in which a connection pad on a wiring board and a gold bump provided on an electrode terminal of a semiconductor element are connected to each other, and the base having a large diameter bonded to the electrode terminal of the semiconductor element as the gold bump And a bump having a small diameter standing on the base, and a connection pad having a width smaller than the diameter of the protrusion is formed as the connection pad, and then the protrusion A method for manufacturing a semiconductor device, comprising: bonding a connection pad to the connection pad.   6. The method of manufacturing a semiconductor device according to claim 5, wherein a gold plating layer is deposited on the surface of the connection pad, and the gold plating layer and the protrusion are directly bonded.   The method of manufacturing a semiconductor device according to claim 6, wherein the connection pads are bonded so as to be embedded in the protrusions.   6. The method of manufacturing a semiconductor device according to claim 5, wherein the protruding portion and the connection pad are joined via solder.

Images