JP5489860B2 - Multilayer semiconductor module - Google Patents

Description

  The present invention relates to a semiconductor module for stacking disposed in a lowermost layer when a plurality of semiconductor devices are stacked and configured, and a stacked semiconductor module using the same.

  In response to demands for miniaturization and higher functionality of various electronic devices such as mobile phone devices and digital cameras, electronic components, especially stacked semiconductor modules that are integrated by stacking multiple semiconductor devices and chips (Package on Package) ) Has been developed.

  In the mounting of this stacked semiconductor module, the improvement in inspection sensitivity due to the higher yield and higher functionality of the connection of upper and lower packages due to higher density has become a problem. There is a need for improved yields.

  Patent document 2 etc. are known as a conventional laminated semiconductor module. FIG. 8A shows a conventional stacked semiconductor module, in which a second package PK2 is stacked and mounted on a first package PK1.

  The external connection terminals 2 are disposed on the lower surface of the first package PK1, and the upper and lower connection terminals 1 are disposed on the upper surface of the first package PK1. In a normal product, the upper and lower connection terminals 1 are bonded onto the upper layer module connection pads 15a formed on the upper surface of the first package PK1. Further, the shape of the connection surface of the upper and lower connection terminals 1 and the shape of the external connection terminal 2 are both similar circular shapes. Further, the upper layer module connection pad 15a is circular as shown in FIG.

  In Patent Document 2, as shown in FIG. 9, the land 4 itself provided on the substrate 11 of the semiconductor device is formed in a rectangle, an ellipse, an ellipse or the like that is elongated in the direction of thermal expansion. What improved connection reliability is described.

JP 2004-363126 A JP 2000-208557 A

  Usually, an electrical inspection is used to determine the connection between the upper and lower semiconductor devices. In other words, in general, re-inspection is performed in the state of the connection between the upper and lower sides and the state of the laminated finished product connected in the upper and lower directions in order to ensure electricity.

  In the inspection, the stacked semiconductor module is inserted into the socket of the inspection apparatus, and the external connection terminal 2 of the first package PK1 is brought into contact with the probe on the socket side by applying a load from above. The connection between the first package PK1 and the second package PK2 is determined to be conductive through the internal wiring of the stacked semiconductor module.

  However, in such an electrical inspection, when the bonding state between the first package PK1 and the second package PK2 is not a reliable bonding and it is delicate whether or not it is simply in contact, There is a case in which a state in which the connection between the connection portions of the first package PK1 and the second package PK2 is temporarily taken due to the load occurs and the inspection is passed because it is determined as “electrically OK”. is there.

  Therefore, not only the upper and lower connection terminals are in contact but also whether or not the upper and lower connection terminals are properly physically joined and the connection is maintained is determined by a non-contact transmission inspection such as X-ray inspection or ultrasound. The flaw detection method (SAT Scanning Acoustic Tomograph) is used.

However, such a transmission inspection takes a very long time for visual determination, and it is difficult to set a threshold value even with automatic determination, and it is very difficult to determine whether or not there is a joint.
Specifically, in the example shown in FIGS. 8A and 8B, the pad 15a has a circular shape, and the external connection terminal 2 has a ball-shaped circular shape. Even if the mold type semiconductor module is transmitted from the upper part, both are circular and identical. Moreover, in contrast to the circular shape of the connection surface in the vertically joined state, the planar shape of the ball of the upper terminal itself can be seen in the unjoined state and the non-contact state, and both are the same shape. In addition, since the connection terminals of the same shape such as the lowermost terminal and the upper terminal are mixed regardless of the size, the size and shape of the joined state are the same at first glance, even in the unjoined state, Furthermore, since the other connecting terminals have the same shape, it is difficult to distinguish the joint location and the other connecting terminals.

  Japanese Patent Application Laid-Open No. H10-228561 discloses a land having a rectangular shape as shown in FIG. 9 for the purpose of improving the connection strength of a semiconductor device to a printed circuit board. However, it is clear that this is not a problem at the time of inspection in which terminals are present in the upper and lower sides in a stacked state as in a stacked semiconductor module.

  Specifically, simply applying the rectangular lands found in Patent Document 2 to the upper and lower connection terminals is not clear in the size difference between the upper and lower connection terminals and the shape difference in each connection part. In the transmission inspection such as the above, there is a possibility that connection terminals having the same shape such as the lowest terminal and the upper and lower terminals are mixed.

  The present invention provides a stacked semiconductor module and a stacked semiconductor module that can easily and reliably determine the quality of a joint in a nondestructive inspection, thereby improving quality and reliability. For the purpose.

The stacked semiconductor module of the present invention has a first semiconductor chip mounted on one surface, a second pad outside the holding region of the first semiconductor chip, and a solder on the first pad on the other surface. A first substrate having a first connection terminal, a second substrate having a second semiconductor chip mounted on one surface, the first substrate and the second substrate, and A stacked semiconductor module including a first connection terminal and a second connection terminal made of solder for connecting between the first substrate and the second substrate, wherein the second pad is covered with an insulating film having an opening, The planar shape of the opening is different from the planar shape of the first connection terminal, and the second connection terminal fills the opening and is joined to the second pad, and the first substrate and the When the transmission inspection is performed in the stacking direction with the second substrate, And the pitch of the first connection terminals is equal, and the planar shape of the openings is parallel to the arrangement of the openings and the arrangement of the first connection terminals, but the positions thereof are different. A part of the opening protrudes from the surface, and the planar shape of the opening is entirely polygonal; the planar shape of the first connection terminal is entirely circular; and the polygon of the opening The outer shape is larger than the diameter of the first connection terminal .

  According to this configuration, the stacked semiconductor module includes the planar shape of the second connection terminal that connects the lower layer module and the upper layer module and the planar shape of the first connection terminal formed on the other surface of the first substrate. The shape of the connection surface between the other end of the second connection terminal and the pad on the first substrate side is different, and the transmission inspection is performed in the stacking direction of the first connection terminal and the opening. The outer shape of the opening protrudes from the first connection terminal, or the outer shape of the opening is larger than the second connection terminal and the first connection terminal, so that the lower layer module and the upper module are not joined. The shape is obviously different depending on the bonding state. In addition, in the transmission inspection from above, the planar shape of the second connection terminal that fills the opening and is bonded to the pad is not hidden by other terminals, so that the shape difference can be easily detected by transmission inspection from above. Can be determined. Therefore, the inspection of the joint between the upper layer and lower layer modules can be ensured, and the semiconductor device and module can be supplied with high quality and reliability.

(A) Cross-sectional view of stacked semiconductor module, (b) Cross-sectional view of connection surface A, (c) Cross-sectional view of connection surface B, (d) Cross-sectional view of connection surface C in the embodiment of the present invention Explanatory drawing of the manufacturing method of the laminated semiconductor module in the embodiment Sectional drawing of the lower layer module of the semiconductor device for lamination | stacking in the same embodiment The top view of the projection state of the 1st substrate 11 in the embodiment (A) A cross-sectional view of the case where the stacked semiconductor module is partially unjoined in the embodiment, and (b) an image when observed through transmission with an X-ray transmission device from above. The enlarged plan view which shows the shape of the opening part in the embodiment Illustration of the problem Sectional view of the stacked semiconductor module described in the conventional example and plan view of the joint surface of the lower layer module The top view which shows the shape of the land described in another prior art example

Hereinafter, embodiments of the present invention will be described with reference to FIGS.
FIG. 1A shows a stacked semiconductor module of the present invention. Note that the numbers and shapes of terminals, electrodes, wirings, and the like are omitted or easy to show. Similar omissions are made in all the following figures.

  A second package PK22 is stacked and mounted on the first package PK21. The first semiconductor chip 12 is mounted on the upper surface of the first package PK21, and the second semiconductor chip 22 is mounted on the upper surface of the second substrate 25 of the second package PK22.

  Specifically, the second package PK22 is a general-purpose stacking memory device or the like, in which a second semiconductor chip 22 such as a memory is mounted on a substrate, and the electrodes are connected to each other by wire bonding or a flip chip method. It is used for electrical connection, and in some cases, it is sealed or coated with resin so as to cover the semiconductor chip.

  FIG. 2 shows a stacking process of the first package PK21 and the second package PK22. A second connection terminal 30 is formed in the second package PK22 for joining with the first package PK21. As the joining metal constituting the connection terminal 30, a solder ball using a solder material such as SnPb, SnAgCu, SnCu, SnBi is generally used.

The first package PK21 of the stacked semiconductor module, which is a lower layer module, is configured as shown in FIG.
The first package PK 21 includes a first substrate 11 and a first semiconductor chip 12 mounted on the chip holding surface of the first substrate 11.

  The first semiconductor chip 12 is provided with an integrated circuit formation region (not shown) in which a semiconductor element is formed at the center of a planar rectangular chip substrate, and a plurality of first chip terminals 23 are arranged on the outside thereof. Has been. The first chip terminal 23 is generally formed of the same metal as that used for forming the wiring of the integrated circuit, and is formed of aluminum, copper, or a laminated material of aluminum and copper. The surface of the chip substrate is covered with an insulating film (not shown) such as polyimide except for the region where the first chip terminals 23 are formed. The first chip terminal 23 may be disposed in the integrated circuit formation region. A protruding electrode 24 is formed on the first chip terminal 23 by a known method such as a wire bump method or a plating method.

  The protruding electrode 24 provided on the first chip terminal 23 may be a simple substance or a laminate made of two or more of solder, gold, copper, nickel, etc., and the shape is spherical or columnar. It may be a bump.

  The first substrate 11 has a multilayer wiring structure formed of aramid resin, glass epoxy resin, polyimide resin, ceramic, or the like. A plurality of first chip connection terminals 13 are provided on the chip holding surface of the first substrate 11 at positions corresponding to the protruding electrodes 24 provided on the first semiconductor chip 12.

  The first semiconductor chip 12 is flip-chip mounted on the first substrate 11, and the protruding electrode 24 of the first semiconductor chip 12 is electrically connected to the first chip connection terminal 13 by the conductive adhesive 14. Has been. Furthermore, an underfill resin 16 fills the space for reinforcing the connection between the first semiconductor chip 12 and the first substrate 11. The first semiconductor chip 12 and the first substrate 11 may be connected using a method of connecting by curing shrinkage of a non-conductive resin film instead of the underfill resin 16.

  On the surface (back surface) opposite to the chip holding surface of the first substrate 11, a plurality of first connection terminals 2 for external connection are arranged in a lattice pattern at equal intervals. The first connection terminal 2 can be electrically connected to an external board (not shown) which is a printed board. As a material for the first connection terminal 2, a solder material such as SnPb, SnAgCu, SnCu, SnBi or a ball-shaped material made of gold, copper, nickel, or the like is usually mounted, and the first reflow heating is performed to a temperature higher than the melting point. It can be melt bonded to the substrate 11. Further, as the first connection terminal 2, a resin ball provided with conductivity by performing metal vapor deposition or the like on the surface layer can also be used.

  A pad for connecting an upper layer module for connecting to a second package PK22 as an upper layer module of the stacked semiconductor module is provided on the outer side of the holding region of the first semiconductor chip 12 on the chip holding surface of the first substrate 11. A plurality of 15 are provided. Further, an insulating film 20 such as solder resist or polyimide covers a part of the pad 15 and a part of the pad 15 is exposed by the opening 3 for connecting the upper layer module. The portion exposed from the opening 3 is subjected to surface treatment by plating such as nickel or gold plating to prevent oxidation of the underlying pad. An insulating film 20 such as solder resist or polyimide is also formed on the surface (back surface) opposite to the chip holding surface of the first substrate 11 except for the portion where the first connection terminals 2 are formed.

FIG. 4 shows details of the first substrate 11 of the first package PK21.
4 shows a projection view of the first connection terminal 2 in addition to the plan view of FIG.
Here, the opening 3 has a square shape, whereas the first connection terminal 2 is a solder ball, so the shape of the opening 3 is circular. Yes. Moreover, the outer shape of the opening 3 is larger than that of the external connection terminal 2.

  In this embodiment, there is a feature in the difference and size of the opening 3 of the first package PK21 and the first connection terminal 2, and thereby, the first package PK21 and the second package PK22 are different. The connection state can be easily detected by non-contact transmission inspection as described below.

  The second package PK22 is mounted on the first package PK21 configured as described above as shown in FIG. 2, and is melted and solidified by reflow heating at or above the melting point of the material of the connection terminal 30. Thus, the lower end of the connection terminal 30 is solder-bonded to the pad 15 on the first package PK21 side, and the first package PK21 is electrically connected to the second package PK22 via the connection terminal 30.

  The melted connection terminal 30 wets, spreads and solidifies along the shape of the opening 3, so that the bottom surface has substantially the same shape as the opening shape of the opening 3. FIG. 1B is a cross-sectional view of the connection surface A between the second package PK22 and one connection terminal 30 in the stacked semiconductor module formed as described above, and FIG. 1C is a view illustrating the first package PK21. FIG. 1D is a cross-sectional view of the connection surface C between the first package PK21 and the first connection terminal 2, and FIG.

  The quadrangle of the opening 3 in the normal bonded state filled with the solidified component of the connection terminal 30 is connected when the stacked semiconductor module is observed through transmission from above using an X-ray transmission device or the like. Since the bottom surface of the terminal 30 spreads over the entire opening 3 and the rectangular outer shape of the opening 3 is larger than the first connection terminal 2, the X-ray or the like from the top In the transmission observation, even if the connection terminal 30 overlaps the first connection terminal 2 of the lower layer module, the bottom surface of the connection terminal 30, that is, the opening, as shown in FIG. The quadrangular shape of the portion 3 can be observed by protruding from the shadow of the first connection terminal 2 located below the portion.

  On the other hand, if there is a bonding failure in the case of non-bonding in which wetting failure has occurred, or if the bonding failure has occurred as indicated by P on the left side of the connection terminal 30 shown in FIG. 3 does not spread over the entire area 3, and thus a circular bottom surface close to the shape of the original connection terminal 30 is formed. When the poorly bonded stacked semiconductor module is observed through an X-ray transmission device or the like from the upper direction, the opening 3 and the pad itself are as thin as 10 μm to 20 μm. In addition, only the unjoined terminal image of the connection terminal 30 having a relatively thicker thickness, for example, 100 μm or more, is displayed very clearly as a circular shape. FIG. 5B shows an example of detection of a joint failure portion P. As shown in FIG.

  As can be seen by comparing FIG. 5A and FIG. 5B, the square shape as the shape of the original connection terminal can be confirmed when normally joined, and when not joined, the first package PK21. However, the connection state of the second package PK22 can be easily detected. Therefore, by assembling the stacked semiconductor module using the first package PK21 having the structure shown in FIG. 3 as a lower layer module, a highly reliable stacked semiconductor module can be realized only by a simple inspection process.

In the above embodiment, the case where the shape of the opening 3 is a quadrangle has been described as an example, but a polygon having more corners than the quadrangle may be used. Specific examples are shown in FIGS.
6A shows a case where the shape of the opening 3 is a cross shape, FIG. 6B shows a case where the shape of the opening 3 is a square and a corner is attached, and FIG. 6C shows a shape of the opening 3. 6 (d) shows a case where the shape of the opening 3 is a square and a rounded corner is attached to the corner portion, and FIG. 6 (e) shows that the shape of the opening 3 is partially This is the case of a deformed elliptical shape. In either case, the polygonal outer shape of the opening 3 is made larger than the diameter of the first connection terminal 2. Thus, it may be a cross, a corner provided with rounded corners, a pentagon, a polygon that includes an arc at a part of the side, a polygon that is all curved but has corners, and the like.

It should be noted that by applying a radius to the corner portion of the opening 3, resist residue and foreign matter residue can be reduced as compared with a case where the corner portion of the opening 3 is not radiused, which is effective.
In addition, the size of the opening 3 may be a size that covers the entire diameter of the first connection terminal 2 and may be a size that hides the entire shape. For example, in practice, the variation level of the external terminal diameter is about 0.01 mm or less, and the variation in the opening size is also about 0.01 mm. Therefore, it is desirable to make the square average 0.015 mm or more larger than the terminal diameter. Accordingly, the connection surface at the opening can be confirmed without being hidden by almost all the external connection terminal diameters.

  Specifically, for a ball diameter of about φ0.3 mm, a polygonal shape such as a square larger than □ 0.315 mm may be set. In addition, when the opening 3 and the first connection terminal 2 are viewed on the projection plane, if the polygonal straight and corner portions of the opening 3 are visible, the difference from the circular shape is clear and easy to understand. .

  In the lower module, the pitch of the openings 3 of the upper module and the pitch of the first connection terminals 2 can be made equal. If the pitches are equal, the external connection terminals of the upper and lower modules are arranged at equal intervals in the same size as shown in FIG. 7, so that X-rays, SAT, etc. Although it is difficult to determine by inspection, in this embodiment, as shown in FIG. 4, the opening 30 of the lower module to which the upper module PK22 is connected is polygonal, and the circular shape of the first connection terminal 2 of the lower module Since the outer shape is larger than the diameter of the first connection terminal 2 of the lower layer module, it can be easily discriminated in transmission observation.

  Further, when an upper layer module having a general-purpose ball-shaped connection terminal 30 is bonded to and stacked on the lower layer module as described above, the bottom surface of the connection terminal 30 of the upper layer module in the state of the stacked semiconductor module. Exhibits a polygonal shape, and the unjoined portion remains circular. Thus, the shape is different and the diameter is larger than the diameter of the connection terminal 30 of the upper layer module. Therefore, the presence or absence of bonding can be clearly determined in the transmission inspection from the upper part by X-ray or the like.

  If the diameter is not larger than the diameter of the connection terminal 30, when viewed through the top, the polygonal shape of the bottom surface is hidden by the connection terminal 30 itself, and a circular shape of the terminal diameter is seen as a transmission image. It may not be possible to distinguish from the case of joining. In addition, the change in the bottom shape of the connection terminal is before and after connection, that is, only before and after lamination, in the manufacturing process of the upper and lower semiconductor modules, there is no special processing, and the pad shape is changed to the polygon as described above. Therefore, it is easy to use existing processes and general-purpose modules. In addition, when the opening and the external connection terminal are viewed on the projection plane, if the polygonal straight and corner portions of the opening are visible, the difference from the circular shape is clear and easy to understand. That is, here, the shape of the opening 3 is a polygon, and the bottom surface of the connection terminal 30 is also a polygon. The size is larger than the diameter of the connection terminal 30 of the upper layer module. Or it is larger than the diameter of the 1st connection terminal 2 of a lower layer module. In addition, it may be larger than both.

  In each of the above embodiments, the planar shape of the opening 3 is different from the planar shape of the first connection terminal 2, and the outer shape of the opening 3 is larger than that of the first connection terminal 2. Unlike the planar shape of the first connection terminal 2, the outer shape of the opening 3 is different from that of the first connection terminal 2 in a state where a transmission inspection is performed in the stacking direction of the first connection terminal 2 and the opening 3. The same effect can be expected even if it protrudes.

  In each of the above-described embodiments, the planar shape of the opening 3 is different from the planar shape of the connection terminal 30 and the planar shape of the first connection terminal 2 formed on the other surface of the first substrate 11. The other end of the connection terminal 30 connected to the second substrate 25 is melted and solidified to fill the opening 3 and bonded to the pad 15, and the outer shape of the opening 3 is the connection terminal 30 and the first connection terminal 2. However, the planar shape of the opening 3 is different from the planar shape of the connection terminal 30 and the planar shape of the first connection terminal 2 formed on the other surface of the first substrate 11. The other end of the connection terminal 30 connected to the second substrate 25 is melted and solidified to fill the opening 3 and bonded to the pad 15, and transmission inspection is performed in the stacking direction of the first connection terminal 2 and the opening 3. In this state, the outer shape of the opening 3 is the connection terminal 30 and the first connection. Even if not protrude from the child 2 can expect a similar effect.

  In each of the embodiments described above, the outer shape of the upper layer module connection pad opening in a state in which all of the inter-module connection terminals to be inspected are subjected to a transmission inspection in the stacking direction of the external connection terminal and the upper layer module connection pad opening. Should protrude from the inter-module connection terminal and the external connection terminal. In this case, since all defects to be inspected can be determined by a simple transmission inspection, it is possible to eliminate the need for open or short electrical inspection.

  Further, when the opening of the upper layer module connection pad is a combination of a circular shape and an irregular shape portion, the protruding portion in the transparent state includes an irregular shape portion with respect to the external connection terminal. As a result, even when a locally irregularly shaped portion is provided due to design constraints, it can be discriminated by transmission inspection even though it is a limited region. For example, with respect to the circular shape of the external connection terminal, a linear shape may be formed at the protruding portion.

  Further, the height of the upper module connection pad opening may be less than half the height of the inter-module connection terminal. More specifically, the inter-module connection terminal height is 300 μm to 400 μm, and the height of the pad opening with respect to the pad surface is 5 μm to 20 μm. Thus, the following effects are acquired by making pad opening part height low enough.

  As a characteristic connection failure of this laminated module, there is a case where the terminal contacts the upper module connection pad surface and the electrical continuity is maintained only temporarily. This phenomenon is that after the solder of the terminal is heated and melted, it does not spread on the pad, but remains in a solid state and maintains its original terminal shape at the position where it touches the pad surface or not. It occurs in. When the height of the pad opening is close to the connection terminal, the connection terminal melts following the side of the pad opening even when the pad is not wet and spread. The shape of the pad opening is exhibited, and this defect phenomenon cannot be distinguished by transmission inspection. On the other hand, in the present invention, since the height of the pad opening is as low as half or less of the height of the connection terminal, there is a difference in the shape of the bottom surface when the contact only is abnormal and when the contact is spread and connected normally. Can be confirmed by simple transmission inspection.

  The present invention contributes to improving the reliability of various small electronic devices such as small devices, mobile phone devices, digital still cameras, and video cameras.

PK21 First package PK22 Second package 2 External connection terminal 3 Opening (upper module module pad opening)
11 First substrate 12 First semiconductor chip 13 First chip connection terminal 14 Conductive adhesive 15 Upper layer module connection pad 16 Underfill resin 20 Insulating film 22 Second semiconductor chip 23 First chip terminal 24 Protrusion Electrode 25 Second substrate 30 Module connection terminal

Claims (2)

A first semiconductor chip is mounted on one surface, a second pad is provided outside the holding region of the first semiconductor chip, and a first connection terminal made of solder is provided on the first pad on the other surface. 1 substrate,
A second substrate a second semiconductor chip is mounted on one surface,
And laminating the first substrate and the second substrate, there in the stacked semiconductor module and a second connection terminal composed between the first substrate and the second substrate from the solder to connect And
The second pad is covered with an insulating film having an opening,
The planar shape of the opening, unlike the prior SL planar shape of the first connection terminal,
The second connection terminal fills the opening and is joined to the second pad,
When transmission inspection is performed in the stacking direction of the first substrate and the second substrate, the pitch of the openings is equal to the pitch of the first connection terminals, and the planar shape of the openings is the opening. The arrangement of the first connection terminals is parallel to the arrangement of the first connection terminals but the position is different, and a part of the opening protrudes from the first connection terminals,
The planar shape of the opening is all polygonal, and the planar shape of the first connection terminal is all circular.
The stacked semiconductor module , wherein the polygonal outer shape of the opening is larger than the diameter of the first connection terminal . The arrangement of the openings is located on the outer peripheral side of the first substrate with respect to the arrangement of the first connection terminals.
The stacked semiconductor module according to claim 1.

Images