JP4498842B2 - 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 an underfill resin is injected between a resin protective film on a substrate and a semiconductor component and the semiconductor component is mounted on the substrate, and a manufacturing method thereof.

  In a semiconductor device configured to mount a surface mount type semiconductor component on a wiring board, the semiconductor component is filled with an underfill resin between the semiconductor component and the wiring board due to a difference in thermal expansion between the semiconductor component and the wiring board. The connection reliability is improved by preventing the bumps electrically connecting the wiring board and the wiring board from being broken (see, for example, Patent Document 1).

  Here, each process of the conventional manufacturing method is demonstrated with reference to FIG. 1 thru | or FIG.

  As shown in FIGS. 1A to 1C, in a BGA (Ball grid array) type semiconductor device 10, a large number of bumps (terminals) 12 are arranged on the lower surface of a square-shaped semiconductor chip 14, The semiconductor chip 14 is placed on the upper surface of the mounting substrate 16, and the bumps 12 are soldered to the electrode pads 18 on the mounting substrate 16. On the surface of the mounting substrate 16, a solder resist 20 is formed as a resin protective film.

The gap formed between the semiconductor chip 14 and the solder resist 20 is filled with the underfill resin 22 and baked. Thereby, the periphery of the bump 12 is reinforced by the underfill resin 22, and bump destruction due to a difference in thermal expansion between the semiconductor chip 14 and the mounting substrate 16 is prevented.
JP 2000-150557 A

  However, as shown in FIGS. 2A and 2B, as the number of terminals arranged on the lower surface of the semiconductor chip 14 made of an LSI chip increases, the distance between the terminals also decreases, and the bumps 12 are also formed. It is formed small and the pitch between the bumps 12 is narrowed. At this time, the height of the bump 12 is also lowered due to the decrease in the bump diameter. Further, when the mounting substrate 16 is viewed from below, there are a terminal region α where the bumps 12 are dense and a non-terminal region β where the bumps 12 are not formed.

  As shown in FIG. 2C, when the semiconductor chip 14 with a narrow pitch between the bumps 12 is placed on the upper surface of the mounting substrate 16 and the bumps 12 are soldered to the electrode pads 18 on the mounting substrate 16, Since the height of the bump 12 is also lowered, the gap S between the semiconductor chip 14 and the solder resist 20 is narrowed.

  Further, as shown in FIG. 2 (D) by enlarging part C, since the wiring pattern 24 is formed on the surface of the mounting substrate 16, the surface of the solder-resist 20 has the shape of the wiring pattern 24. Concave and convex shape according to. Therefore, as shown in FIG. 2E with the D portion enlarged, the gap S between the semiconductor chip 14 and the solder resist 20 is narrowed above the wiring pattern 24 and is included in the underfill resin 22. Among the fillers 25 and 26, the filler 25 with small particles can pass through the gap S, but the filler 26 with large particles becomes difficult to pass through the gap S and becomes a resistance when filling the underfill resin 22. There has been a problem that the speed is slow or filling is impossible.

  Further, when the underfill resin 22 is filled in the gap between the semiconductor chip 14 and the solder resist 20, the underfill resin 22 is in a liquid state with a relatively low viscosity, so that it is injected from one side of the mounting substrate 16 and others. The whole is filled so as to move to the side.

  Here, the flow state of the conventional underfill resin 22 (shown as a satin pattern in FIG. 3) will be described with reference to FIGS. 3A to 3E, the semiconductor chip 14 is seen through and is indicated by a one-dot chain line.

  As shown in FIGS. 3A to 3E, when the mounting substrate 16 is viewed from above, the flow velocity distribution of the underfill resin 22 is caused by the capillary phenomenon in the terminal region α where the bumps 12 are dense. The flow speed of the fill resin 22 is increased. On the other hand, in the non-terminal region β where the bumps 12 are not formed, the flow rate of the underfill resin 22 tends to be relatively slow.

  Therefore, when the underfill resin 22 is filled from one side of the mounting substrate 16 to the other side, the underfill resin 22 does not move at a uniform speed, and the flow rate of the underfill resin 22 is delayed in the non-terminal region β in the central portion of the substrate. The flow velocity in the terminal region α surrounding the central portion where the bumps 12 are densely increased, and a part of the flow of the underfill resin 22 arriving at the other side of the mounting substrate 16 is directed toward the central portion. (Indicated by an arrow in FIG. 3E). As a result, there arises a problem that voids 28 are formed by the cavities between the flow delayed in the non-terminal region β and the flow flowing in from the terminal region α.

  Further, depending on the size of the gap between the semiconductor chip 14 and the mounting substrate 16 and the characteristics of the underfill resin 22, the flow of the underfill resin 22 is slowed down in the terminal region α due to the influence of the filler particles in a position different from the above. There arises a problem that voids are generated.

  In view of the above, an object of the present invention is to provide a semiconductor device and a method for manufacturing the same that solve the above problems.

  In order to solve the above problems, the present invention has the following features.

The invention according to claim 1 is the first step of forming a resin protective film on the surface of the mounting substrate, and the resin protective film formed according to the wiring pattern of the mounting substrate by polishing the surface of the resin protective film. A second step of forming a plurality of polishing traces extending linearly on the surface of the resin protective film in a certain direction, and an electrode pad on the mounting substrate on the lower surface of the semiconductor component A third step of connecting the arranged bumps, and a fourth step of mounting the semiconductor component on the mounting substrate by filling an underfill resin between the resin protective film and the semiconductor component. It is characterized by.

The invention according to claim 2 is characterized in that, in the fourth step, the injection direction of the underfill resin is made to coincide with the extending direction of a plurality of polishing marks formed on the surface of the resin protective film.

According to a third aspect of the present invention, an underfill resin is filled between the resin protective film and the semiconductor component in a state where the terminals of the semiconductor component are connected to the electrode pads of the substrate having the resin protective film formed on the surface. In a semiconductor device in which the semiconductor component is mounted on the substrate, the surface of the resin protective film is polished by a polishing member to form a plurality of polishing marks extending in a straight direction on the surface of the resin protective film. , characterized in that it was filled with pre-Symbol underfill resin.
The invention according to claim 4 is characterized in that the underfill resin is filled along the extending direction of the plurality of polishing marks.

According to the present invention, the surface of the resin protective film is polished to remove the uneven surface portion of the resin protective film formed according to the wiring pattern of the mounting substrate, and extends linearly to the surface of the resin protective film. After forming multiple polishing marks in a certain direction, filling the underfill resin between the resin protective film and the semiconductor component to mount the semiconductor component on the mounting substrate, the surface shape of the resin protective film is flattened Thus, the flow of the underfill resin containing the filler can be filled by moving from one side of the mounting substrate to the other side at a substantially uniform speed.

Further, the underfill resin by filling along a plurality of polishing streaks extending linearly in the surface of the resin protective layer, the other side in the process of filling an underfill resin from one side of the mounting substrate to the other side It is possible to prevent the arrival of the flow of the underfill resin that has arrived, and to prevent generation of voids.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

  4A to 4F are process diagrams showing one embodiment of a method for manufacturing a semiconductor device according to the present invention. 4A to 4F, the same parts as those shown in FIGS. 1 to 3 are denoted by the same reference numerals.

  As shown in FIG. 4A, in step 1, after the electrode pad 18 and the wiring pattern are formed on the mounting substrate 16, the solder resist 20 is formed on the mounting substrate 16 excluding the electrode pad 18 by screen printing. . Alternatively, a photosensitive solder resist may be formed on the mounting substrate 16 and a resist pattern may be formed by exposure and development.

  Since the surface of the solder resist 20 is polished in a process described later, the solder resist 20 is formed slightly thicker than usual (for example, about 20 μm to 30 μm in thickness on the wiring pattern).

  As shown in FIG. 4B in which the A portion is enlarged, the wiring pattern 24 is formed on the mounting substrate 16 and the solder resist 20 is also coated on the wiring pattern 24. Therefore, the solder resist The surface 20a of 20 has a convex portion 20b on the wiring pattern 24, and a concave portion 20c in a region where the wiring pattern 24 does not exist.

  As shown in FIG. 4C, in step 2, the surface unevenness portion is removed by polishing the surface 20a of the solder resist (resin protective film) 20 using the buffing machine 30 shown in FIG. Therefore, the surface 20a of the solder resist (resin protective film) 20 is apparently flattened, and the underfill resin 22 having fillers 25 and 26 having different particle sizes can easily flow. It is possible to prevent the speed from changing due to the uneven surface portion.

Here, the buffing machine 30 will be described with reference to FIG.
As shown in FIG. 5, the buffing machine 30 includes an upper surface baffle 32 as a roll-shaped polishing member for polishing the solder resist 20 formed on the upper surface of the mounting substrate 16, and a lower surface for polishing the lower surface of the mounting substrate 16. And the upper and lower surfaces of the mounting substrate 16 are polished at the same time. A pressing roller 36 that presses the mounting substrate 16 upward is provided below the upper surface baffle 32, and a pressing roller 38 that presses the mounting substrate 16 downward is provided above the lower surface baffle 34. It has been. Accordingly, the upper and lower surfaces of the mounting substrate 16 are pressed with a predetermined load against the upper surface baffle 32 and the lower surface baffle 34 that are rotationally driven by a motor (not shown). The corresponding thickness is polished.

  Further, the buffing machine 30 is provided with a plurality of transport rollers 40 and 42 for transporting the mounting substrate 16 to the upper surface baffle 32 and the lower surface baffle 34. The transport rollers 40 and 42 transport the mounting substrate 16 at a predetermined transport speed in a transport direction indicated by an arrow by a motor (not shown).

  The buffing machine 30 has a configuration in which a pair of upper surface baffles 32 and lower surface buffols 34 are provided, but the number of upper surface baffles 32 and lower surface baffles 34 may be two or three. It is. Accordingly, the numbers of the upper surface buffules 32 and the lower surface buffols 34 are selected according to the polishing amount of the solder resist 20 to be polished, and the types (sizes of abrasive grains) of the upper surface buffol 32 and the lower surface buffol 34 are selected. By selecting, the depth of the polishing mark left on the surface 20a of the mounting substrate 16 can be set to an arbitrary depth.

  As shown in FIG. 4D in which the portion B is enlarged, the solder resist 20 is processed into a flat surface by removing the irregularities on the surface 20a by performing the polishing process of the solder resist 20 by the buffing machine 30. At the same time, fine polishing marks 44 are linearly formed on the surface 20a of the solder resist 20 along the conveying direction.

  That is, the mounting substrate 16 is formed on the surface 20a of the solder resist 20 polished by passing through the rotating upper surface baffle 32, for example, a linear polishing mark 44 made of a plurality of fine grooves having a depth of 1 to 10 μm. Is formed. This fine polishing mark 44 functions as a regulating means for regulating the flow direction of the underfill resin 22 when the underfill resin 22 is filled.

  Further, the underfill resin 22 is also bonded to the surface 20a of the solder resist 20 more firmly by filling the polishing marks 44 formed of fine grooves.

  As shown in FIG. 4E, in step 3, the bumps 12 arranged on the lower surface of the semiconductor chip 14 are soldered to the electrode pads 18 on the mounting substrate 16.

  As shown in an enlarged view in FIG. 4F, in step 4, an underfill resin 22 is filled in the gap S between the surface 20a of the solder resist 20 planarized by the polishing step and the lower surface of the semiconductor chip 14. The semiconductor chip 14 is mounted on the mounting substrate 16 by baking. The underfill resin 22 has fillers 25 and 26 having different particle sizes. Since the surface 20a of the solder resist 20 is flattened by the polishing process, the surface 20a of the solder resist 20 and the lower surface of the semiconductor chip 14 are provided. The filler S 26 having a large particle size can be moved freely, and the flow of the underfill resin 22 can be performed smoothly.

  Accordingly, when the underfill resin 22 is injected into the gap S from the side of the mounting substrate 16, the flow direction of the underfill resin 22 changes due to the unevenness of the surface 20 a of the solder resist 20, or the filler 26 having large particles 26 The movement is not restricted and the entire area between the solder resist 20 and the semiconductor chip 14 can be filled with the underfill resin 22.

  Here, the flow state of the underfill resin 22 (shown as a satin pattern in FIG. 6) when filling the underfill resin 22 will be described with reference to FIGS. In FIG. 6, the semiconductor chip 14 is seen through and is indicated by a one-dot chain line.

  As shown by a broken line in FIG. 6A, a polishing mark 44 made of a fine groove is formed on the surface 20a of the solder resist 20 on the mounting substrate 16 so as to extend in a certain direction (X direction). ing. Then, the underfill resin 22 is injected into the gap S between the surface 20 a of the solder resist 20 and the lower surface of the semiconductor chip 14 from the right side of the mounting substrate 16. The underfill resin 22 is discharged onto the solder resist 20 from the tip discharge port of a resin filling nozzle (not shown) and filled along the right side of the semiconductor chip 14.

  Thus, the underfill resin 22 placed on the solder resist 20 flows into the gap S between the surface 20a of the solder resist 20 and the lower surface of the semiconductor chip 14, as shown in FIG. 6B. In addition, the underfill resin 22 is a low-viscosity liquid, and the surface 20a of the solder resist 20 is formed on a flat surface having no irregularities by the polishing process, so that the gap S can be easily moved, particularly in FIG. As indicated by the middle arrow, the flow velocity (filling speed) in the terminal region α where many bumps 12 are densely packed becomes faster than that in the non-terminal region β due to capillary action.

  As shown in FIG. 6C, the underfill resin 22 positively progresses in the terminal region α where a large number of bumps 12 are densely packed, but the movement in the non-terminal region β is delayed.

  As shown in FIG. 6D, when the underfill resin 22 is filled in the non-terminal region β, the underfill resin 22 that has traveled in the X direction in the terminal region α reaches the other side of the semiconductor chip 14. is doing. However, since the underfill resin 22 moves in the extending direction of the minute polishing marks 44 formed on the surface 20 a of the solder resist 20, the underfill resin 22 that has reached the other side of the semiconductor chip 14 has the polishing marks 44. This suppresses the flow in the Y direction toward the center.

  As shown in FIG. 6E, while the underfill resin 22 that has traveled in the X direction through the terminal region α is restrained from flowing in the Y direction by the polishing marks 44, the non-terminal region β is moved in the X direction. The advanced underfill resin 22 advances to the vicinity of the other side of the semiconductor chip 14.

  As shown in FIG. 6F, finally, when the underfill resin 22 having advanced in the non-terminal region β in the X direction reaches the other side of the semiconductor chip 14, the solder resist 20 and the semiconductor chip 14. The filling of the underfill resin 22 is completed in the entire gap.

  As described above, the minute polishing marks 44 formed on the surface 20a of the solder resist 20 regulate the flow direction of the underfill resin 22 in one direction (X direction), thereby causing the under-terminal region β to advance in the X direction. Even if the flow rate of the fill resin 22 is slow, the underfill resin 22 that has advanced through the terminal region α is prevented from entering in the Y direction, and the generation of voids is prevented. Therefore, the reliability of the underfill resin filling process is improved. It becomes possible.

It is a longitudinal cross-sectional view for demonstrating the mounting process of the semiconductor device 10 of the BGA package using an underfill. It is a longitudinal cross-sectional view for demonstrating the mounting process of the semiconductor chip with which bump pitch became small. It is a top view for demonstrating the flow of the conventional underfill resin. It is process drawing which shows one Example of the manufacturing method of the semiconductor device which becomes this invention. 2 is a perspective view showing a configuration example of a buffing machine 30. FIG. 5 is a plan view for explaining a flow state of the underfill resin 22 when filling the underfill resin 22. FIG.

Explanation of symbols

12 Bump 14 Semiconductor chip 16 Mounting substrate 18 Electrode pad 20 Solder resist 22 Underfill resin 24 Wiring pattern 25, 26 Filler 30 Buffing machine 32 Upper surface baffle 34 Lower surface baffle 36, 38 Pressing roller 40, 42 Conveying roller 44 Polishing mark

Claims (4)

A first step of forming a resin protective film on the surface of the mounting substrate;
The surface of the resin protective film is polished to remove surface irregularities of the resin protective film formed according to the wiring pattern of the mounting substrate, and a plurality of linearly extending surfaces of the resin protective film are formed. A second step of forming polishing marks in a certain direction ;
A third step of connecting a bump disposed on the lower surface of the semiconductor component to the electrode pad on the mounting substrate;
A fourth step of mounting an underfill resin between the resin protective film and the semiconductor component and mounting the semiconductor component on the mounting substrate;
A method for manufacturing a semiconductor device, comprising: In the fourth step, the method of manufacturing a semiconductor device according to claim 1, characterized in that to match the injection direction of the underfill resin in the extending direction of the plurality of polishing marks formed on the surface of the resin protective layer . An underfill resin is filled between the resin protective film and the semiconductor component with the terminal of the semiconductor component connected to the electrode pad of the substrate having the resin protective film formed on the surface, and the semiconductor component is placed on the substrate. In the semiconductor device to be mounted,
A plurality of polishing streaks extending linearly in the surface of the resin protective layer of the resin protective layer by polishing the surface of the polishing member is formed in a predetermined direction, characterized by being filled with pre-Symbol underfill resin Semiconductor device. 4. The semiconductor device according to claim 3, wherein the underfill resin is filled along an extending direction of the plurality of polishing marks .

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