JP2009071155A - Semiconductor device and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To form an adhesive layer between a semiconductor element and a circuit board into a shape whose bottom is spread enough toward the circuit board, when the semiconductor element is mounted on the circuit board. <P>SOLUTION: In a method for manufacturing a semiconductor device, a first adhesive layer 12 is beforehand formed at the periphery of a mounting position of the semiconductor element 13 on the circuit board 11 on which the semiconductor element is mounted. Further a second adhesive layer 15 is beforehand formed on the mounting surface of the semiconductor element. The semiconductor element is arranged on the circuit board, and the first adhesive layer and the second adhesive layer are melted and integrated to form a fillet 16. <P>COPYRIGHT: (C)2009,JPO&amp;INPIT

Description

  The present invention relates generally to the technical field of semiconductors, and more particularly to a technique for improving the bonding between a semiconductor element (chip) and a circuit board.

  In recent years, along with downsizing, thinning, and high performance of mobile devices, particularly mobile phones and laptop computers, there is a demand for further downsizing and thinning of mounted semiconductor devices. In response to such demands for miniaturization and thinning, the gap between the circuit board and the semiconductor element (chip) that is flip-chip bonded to the circuit board is also reduced. It has become difficult to inject.

  In order to cope with this problem, a semi-cured sealing resin layer is formed on the semiconductor chip side or circuit board side in advance, and the electrode and the sealing resin are collectively flip-chip bonded (the “first underfill method” ")" Has been widely used.

  FIG. 1A is a schematic diagram for explaining general tip-underfill type chip bonding. In this example, a semi-cured sealing resin layer 105 is formed on the semiconductor chip 103 side where the protruding electrodes 104 are formed prior to bonding. When mounting on the circuit board 101, the semiconductor chip 103 is turned upside down and flip-chip bonded so that the protruding electrode 104 is positioned on the pad electrode 108 on the circuit board 101.

  However, this method has the following problems. That is, if the semi-cured encapsulating resin layer 105 is provided in advance on the semiconductor chip 103 side, the semi-cured encapsulating resin layer 105 is cured due to a wafer transport, a dicing process, and the like, and flows at the time of flip chip bonding. Sex is reduced. As a result, as indicated by a broken-line circle C in FIG. 1A, the resin layer 105 swells and protrudes in the lateral direction, and a resin pool called a fillet is not sufficiently formed.

  The fillet is an effective structure for ensuring the adhesion between the semiconductor element 103 and the circuit board 101 and improving the connection reliability. FIG. 1B shows an ideal fillet 106 shape. The ideal fillet 106 has a shape that reliably covers the end face of the semiconductor chip 103 and expands toward the circuit board 101 so as to draw a skirt smoothly, as indicated by a circle A. This is because, with such a shape, even when the semiconductor chip 103 or the circuit board 101 is warped due to a difference in thermal expansion coefficient or the like, the bonding between the two can be stably held.

  In order to form a good fillet that also spreads on the outer peripheral end face of the semiconductor chip, a semi-cured resin is formed in advance on the internal area of the semiconductor mounting position on the circuit board side, and at the same time, a resin is also formed on the end face of the semiconductor chip. In addition, a method has been proposed in which a fillet is formed by fusing a resin on a chip end surface and a semi-cured resin on a circuit board at the time of flip chip bonding (see, for example, Patent Document 1).

  However, this method can cover the end face of the semiconductor chip, but does not take into account the formation of the flared hem portion on the circuit board. In other words, with respect to the end face portion of the semiconductor chip, a controlled fillet is formed by arranging the resin in advance, but it is possible to control the shape of the fillet in the bottom portion, that is, the fillet near the circuit board. difficult.

In general, the fillet is often not uniformly formed due to the tilt of the tool and stage during flip chip bonding, and it is even more difficult to control the shape of the fillet at the skirt. When the fillet skirt is not sufficiently formed, the bonding between the semiconductor chip and the circuit board becomes insufficient, and the bonding reliability cannot be satisfied.
JP 2006-32625 A

  Therefore, in view of the above-described problems, an object of the present invention is to provide a method for forming a necessary amount of fillets within a necessary range in a good shape.

In order to solve the above problems, according to a first aspect, a method for manufacturing a semiconductor device is provided. This method
(A) forming a first adhesive layer in advance on the outer periphery of the mounting position of the semiconductor element of the circuit board on which the semiconductor element is mounted;
(B) forming a second adhesive layer in advance on the mounting surface of the semiconductor element;
(C) disposing the semiconductor element on the circuit board and fusing and integrating the first adhesive layer and the second adhesive layer to form a fillet;
Process.

  In a preferred embodiment, the first adhesive layer is formed at a predetermined interval from the mounting position of the semiconductor element, for example, 10 to 20 μm.

  In another preferred embodiment, the first adhesive layer is formed so that the amount of resin in the vicinity of the corner of the mounting position of the semiconductor element is larger than that of other portions.

  In any case, it is desirable that the first adhesive layer and the second adhesive layer are compatible with each other.

  In a second aspect, a semiconductor device having a semiconductor element mounted on a circuit board is provided. The semiconductor device includes an adhesive layer positioned between the semiconductor element and the circuit board, and the adhesive layer has a shape that covers an outer peripheral end surface of the semiconductor element and has a hem that extends toward the circuit board. And the density | concentration distribution of the filler contained in the said contact bonding layer becomes low, so that it goes to the edge part of the said skirt expansion part.

  In one embodiment, the semiconductor element is flip-chip bonded to the circuit board.

  Bonding reliability between the semiconductor element (chip) and the circuit board can be ensured.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of the invention will be described with reference to the accompanying drawings. FIG. 2 is a manufacturing process diagram of a semiconductor device according to an embodiment of the present invention, and FIG. 3 is a plan view before and after mounting a semiconductor chip. First, as shown in FIG. 2A, a semi-cured sealing resin layer 12 as a substrate-side adhesive layer is formed at a place where a fillet of a built-up substrate 11 as a circuit board is to be formed. Here, a semi-cured resin mainly composed of an epoxy resin was used. As other resin materials, a cyanate ester resin, a phenoxy resin, a urethane resin, or a resin containing these as a main component can be used.

  The viscosity of the semi-cured sealing resin layer 12 formed on the built-up substrate 11 is 100 to 500 Pa · s at the time of bonding, and the resin layer 15 formed on the bonding surface on the semiconductor chip side (FIG. 2B) Adjustment) so that it can be easily integrated. In general, the viscosity of the resin greatly varies depending on the temperature. Therefore, the viscosity of the semi-cured sealing resin layer 12 can be adjusted by controlling the bonding temperature. As another viscosity adjusting method, the fluidity can be ensured by setting the silica content of the semi-cured sealing resin layer 12 formed on the built-up substrate 11 side to be low, for example, 0 to 40 wt%.

  For the formation of the sealing resin layer 12 on the built-up substrate 11, a dispenser device (FAD320s) manufactured by Musashi Engineering was used. In the dispenser device, the amount of resin can be accurately controlled by adjusting the coating pressure, coating speed, and coating time.

  FIG. 3A is a diagram illustrating an application example 1 of the semi-cured sealing resin 12 on the built-up substrate 11. In this example, the semi-cured sealing resin layer 12 is formed with a uniform width outside the semiconductor chip mounting position indicated by the dotted line. At this time, in order to avoid interference between the semi-cured sealing resin 12 on the built-up substrate 11 side and the semiconductor chip 13 at the time of flip chip bonding, a gap (gap) is formed between the chip mounting position and the semi-cured sealing resin layer 12. ) Set G. Considering the mounting accuracy of the flip chip bonder, it is desirable to provide a gap G of 10 to 20 μm.

  Referring back to FIG. 2B, the semiconductor chip 13 on which the semi-cured sealing resin layer 15 has been formed in advance is flip-chip bonded onto the substrate 11 on which the semi-cured sealing resin layer 12 has been formed in advance. For the semi-cured sealing resin layer 15 on the chip 13 side, an epoxy resin, a phenoxy resin, a urethane resin, or a resin containing these as a main component can be used, but the semi-cured sealing resin 12 on the built-up substrate 11 side. Select materials that are compatible with each other. Prior to bonding, the semiconductor chip 13 is positioned so that the protruding electrode 14 of the semiconductor chip 13 is positioned on the pad electrode 18 formed on the built-up substrate 11.

  The bonding conditions can be arbitrarily set depending on the combination of electrode materials to be used and the presence / absence of application of ultrasonic waves. For example, when a Ni / Au electrode is used for the pad electrode 18 on the substrate 11 side and an Au stud bump or wire bump with a pedestal diameter of 30 μm is used for the protruding electrode 14 on the semiconductor chip 13 side and bonded by thermocompression bonding, 220 ° C., 20 sec, bump The upper semiconductor chip 13 is bonded to the built-up substrate 11 under the condition that the hit pressure is 15 gf. In addition to thermocompression bonding, a joining method such as fusion connection or ultrasonic connection may be used.

  At this time, the semi-cured sealing resin layer 15 on the semiconductor chip 13 side is pushed outward as indicated by an arrow by the pressure during bonding, and at the same time, the sealing resin layer 15 on the semiconductor chip 13 side is pressed by the bonding temperature. And the sealing resin layer 12 on the substrate 11 side are melted and integrated. As a result, as shown in FIG. 2C, a fillet 16 that covers the end of the semiconductor chip 13 and has a sufficient hem as shown by the circle B is formed. That is, as shown in the plan view of FIG. 3B, a fillet 16 is formed that extends uniformly from the edge of the semiconductor chip 13 toward the outside without a gap. Thereby, the reliability of joining is ensured.

  2 and 3, since the semiconductor chip 13 is flip-chip bonded, the fillet 16 for bonding the semiconductor chip 13 to the built-up substrate 11 can be formed simultaneously with the connection between the electrodes.

  In addition, when one or both of the semi-cured encapsulating resin layer 15 on the semiconductor chip 13 side and the semi-cured encapsulating resin layer 12 on the built-up substrate 11 side contain a silica filler, these resin layers are melted. As a result of integration, a gradation structure in which the content of the silica filler decreases toward the end of the fillet 16 is obtained. This is because the fluidity of the other resin components is higher than that of the silica filler, so that the content of the silica filler decreases toward the end of the bottom of the fillet 16.

  Finally, the bonded semiconductor chip 13 and built-up substrate 11 are baked in an oven (for example, at 170 ° C. for 1.5 hours), the sealing resin (fillet) is cured, and the semiconductor device 10 is completed. .

  4 (A) and 4 (B) are diagrams showing an application example 2 of the semi-cured sealing resin layer 22 on the built-up substrate 11. In the example of FIG. 4, the semi-cured sealing is performed so that the width of the semi-cured encapsulating resin layer 22 is narrow and wide near the corner in the region corresponding to the central portion between the corners of the chip mounting position indicated by the broken line. A resin layer 22 is formed. Also in this case, a gap G is set between the semi-cured sealing resin layer 22 and the semiconductor chip mounting position.

  The application shape of the semi-cured encapsulating resin layer 22 in FIG. 4 (A) is such that the application pressure of the semi-cured encapsulating resin layer 22 is constant in the range of 30 to 100 kPa, and the time for holding at each corner is 0.00. It can be realized by providing about 5 s to 1.0 sec. Further, the gap G for preventing the interference between the semi-cured sealing resin layer 22 and the semiconductor chip 13 at the time of flip chip bonding is set to 10 to 20 μm in consideration of the mounting accuracy of the flip chip bonder. In this case, the gap G is set such that the constricted portion at the center of the semi-cured sealing resin layer 22 is 10 to 20 μm away from the semiconductor chip mounting position.

  The semi-cured sealing resin layer 22 has such a shape because the sealing resin from the central portion of each edge rather than the corner portion of the semiconductor chip 13 is applied by applying pressure when the semiconductor chip 13 is bonded. This is because the amount of outflow often increases.

  The planar application shape of the semi-cured sealing resin 22 is not limited to the example in FIG. 4A, and any application shape can be selected as long as the amount of resin increases at the corner portion. For example, on the inner side of the semi-cured sealing resin layer 22 (side facing the chip 13), the central portion is curved so as to be constricted, while on the other hand, the outer side of the semi-cured sealing resin layer 22 (opposite the end of the substrate 11). (Side), it may be formed to extend linearly.

  As described above, the material of the semi-cured sealing resin layer 22 is an epoxy resin, a cyanate ester resin, a phenoxy resin, a urethane resin, or a resin containing these as a main component. Further, the silica content is set to 0 to 40 wt% in order to ensure fluidity at the time of chip bonding.

  When the semiconductor chip 13 is bonded to the built-up substrate 11 having such a semi-cured sealing resin layer 22, methods such as thermocompression bonding, melting, and ultrasonic bonding are the same as described with reference to FIG. Can be adopted. Since the semi-cured sealing resin layer 22 on the substrate 11 side is formed to be thick in the vicinity of the corner of the semiconductor chip 13, even when the sealing resin flows out from the central portion of each edge of the semiconductor chip 13. When the sealing resin layer 15 on the semiconductor chip 13 side and the sealing resin layer 22 on the substrate 11 side are melted and integrated, the formation of the fillet 16 becomes more uniform. As a result, as shown in FIG. 2C, a cross-sectional shape of the fillet 16 that reliably covers the end of the semiconductor chip 13 and has a hem that smoothly spreads is obtained, and as shown in FIG. 4B. Further, the semiconductor chip 13 has a planar shape that spreads uniformly from the edge toward the outside without a gap.

  When a filler such as silica filler is contained in one or both of the semi-cured sealing resin layer 15 on the semiconductor chip 13 side and the semi-cured sealing resin layer 22 on the built-up substrate 11 side, As shown in FIG. 2 (C), the content profile of the filler decreases toward the end of the bottom portion of the fillet 22.

  Finally, the bonded semiconductor chip 13 and built-up substrate 11 are baked at 170 ° C. for 1.5 hours, and the sealing resin is cured to complete the semiconductor device.

  FIG. 5 is a photograph showing the shape of the fillet 16 of the semiconductor device manufactured by the method of FIG. A fillet 16 is formed which covers the end portion of the semiconductor chip 13 and has a skirt sufficiently and uniformly spreading toward the substrate surface.

  In the method of the embodiment described above, the fillet resin is supplied to the necessary portions on the built-up substrate 11 as much as necessary. Therefore, even when the substrate in the fillet forming region has irregularities, the fillet 16 having a sufficient skirt is formed. Can be formed. As a result, the bonding reliability is improved. Further, the fillet can be reliably supplied and formed even on a substrate made of a material having a poor resin flow in a normal sealing resin injection process. Furthermore, since it melts and integrates at the time of joining, there is no resin discontinuity. That is, it is possible to prevent the occurrence of local residual stress in the resin and to further ensure the bonding reliability.

  The semiconductor device and the manufacturing method thereof according to the present invention are not limited to the above-described embodiments, but include various modifications that can be performed by those skilled in the art. For example, the protruding electrodes 14 provided on the semiconductor chip 13 can be solder, Au plated bumps, Cu plated bumps, paste bumps, or the like instead of Au stud bumps or Au wire bumps. Also in this case, the temperature at the time of thermocompression bonding is controlled within a range where the resin can flow freely, for example, in the range of 200 ° C. to 240 ° C., so that the semi-cured sealing resin layer 15 on the semiconductor chip 13 side and the built-up substrate 11 The side semi-cured sealing resin layer 12 (or 22) can be melted and integrated to form a fillet 16 having a sufficient hem.

  The method of the above-described embodiment is suitable for flip chip bonding particularly with the circuit formation surface of the semiconductor chip 13 facing downward (the built-up substrate 11 side), but is not limited to this. The present invention can also be applied to a case where electrical connection with the built-up substrate 11 is performed by wire bonding. In that case, the bonding pads on the built-up substrate 11 are arranged in advance so as to be located outside the bottom end of the adhesive layer (fillet) that adheres the semiconductor element 13 to the built-up substrate 11. Cap resin is formed after wire bonding. Even in this application example, the reliability of bonding is maintained by the good fillet shape between the semiconductor chip 13 and the built-up substrate 11.

  Further, an electrode such as a solder ball may be further formed on the back side of the built-up board 11 so that it can be mounted on another wiring board (motherboard) or the like.

It is the schematic which shows the problem of the joining method of the conventional semiconductor chip. It is a manufacturing process figure of the semiconductor device in the embodiment of the present invention. It is a figure which shows the application example 1 of the semi-hardening sealing resin in embodiment. It is a figure which shows the application example 2 of the semi-hardening sealing resin in embodiment. It is a photograph which shows the fillet shape of the semiconductor device produced by the method of the embodiment.

Explanation of symbols

10 Semiconductor device 11 Built-up board (circuit board)
12, 22 Circuit board side adhesive layer (second adhesive layer; semi-cured sealing resin layer)
13 Semiconductor element (semiconductor chip)
14 Protruding electrode 15 Chip side adhesive layer (first adhesive layer; semi-cured sealing resin layer)
16, 26 Fillet 18 Substrate side pad electrode 19 Filler (silica filler)
G gap

Claims (6)

Forming a first adhesive layer in advance on the outer periphery of the mounting position of the semiconductor element of the circuit board on which the semiconductor element is mounted;
A second adhesive layer is formed in advance on the mounting surface of the semiconductor element,
The semiconductor element is disposed on the circuit board, and the first adhesive layer and the second adhesive layer are melted and integrated to form a fillet.
The manufacturing method of the semiconductor device characterized by including a process.   2. The method of manufacturing a semiconductor device according to claim 1, wherein the first adhesive layer is formed at a predetermined interval from a mounting position of the semiconductor element.   3. The semiconductor device according to claim 1, wherein the first adhesive layer is formed such that a resin amount in the vicinity of a corner of the mounting position of the semiconductor element is larger than that of other portions. Manufacturing method.   The first adhesive layer is formed so that a width at a position corresponding to a central portion between corners is narrower than a width near a corner at a mounting position of the semiconductor element. The manufacturing method of the semiconductor device in any one of 1-3. In a semiconductor device in which a semiconductor element is mounted on a circuit board,
Having an adhesive layer located between the semiconductor element and the circuit board;
The adhesive layer covers the outer peripheral end surface of the semiconductor element and has a shape in which a skirt expands toward the circuit board, and a concentration distribution of the filler contained in the adhesive layer is an end portion of the skirt expanded portion. The semiconductor device is characterized by being lowered toward   The semiconductor device according to claim 5, wherein the semiconductor element is flip-chip bonded to the circuit board.