JP3846890B2 - Semiconductor device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a semiconductor apparatus having an improvement in reliability by preventing the occurrence of bubbles from resin disposed in a gap between a semiconductor device and a circuit board. <P>SOLUTION: The semiconductor apparatus has a circuit board and a semiconductor device mounted on the board through bump electrodes, wherein resin is disposed in a gap between the circuit board and the semiconductor device, and around the semiconductor device. The bump electrodes are formed along the circumference of the semiconductor device, and a concave portion is formed in an area surrounded by the bump electrodes on the surface of the circuit board. <P>COPYRIGHT: (C)2004,JPO

Description

The present invention relates to a semiconductor device, and more particularly to a flip chip structure semiconductor device in which a resin is sealed in a gap portion between a semiconductor chip and a circuit wiring board in order to increase connection reliability of a bump electrode portion.

  2. Description of the Related Art In recent years, semiconductor devices have been required to have higher mounting density with higher integration. In addition to wire bonding technology, TAB technology, and the like, a flip chip mounting technology (US Pat. No. 3) as shown in FIG. , 401, 126 and U.S. Pat. No. 3,429,040) are widely used in the field of computer equipment and the like.

  Generally, since the thermal expansion coefficient of a semiconductor chip and the thermal expansion coefficient of a circuit wiring board are different, the heat generated during the operation of the semiconductor chip is transferred to the circuit wiring board through bump electrodes, resulting in a difference in thermal expansion coefficient. The resulting displacement occurs in the semiconductor chip and the circuit wiring board. The generated displacement generates a stress strain in the bump electrode connecting the semiconductor chip and the circuit wiring board, and this stress strain destroys the bump electrode, resulting in a decrease in the reliability life of the device ( Microelectronic Packaging Handbook (Van Nostrand Reinhold, 1989 ").

The reliability life is Nf = Cf ^1/3 γ _max · exp (1428 / Tmax)
(C is a constant, f is a frequency, and Tmax is a maximum temperature.) From the formula of the cycle life expressed by the formula, the reliability life can be improved by reducing the maximum shear strain γ _max generated in the bump portion. (IBM J. Res. Develop., 13; 251 (1969)).

  Here, the maximum shear strain generated in the bump electrode is expressed by the following equation.

γ _max = {1 / (Dmin / 2) ^{2 / β} } (V / πh ^{1 + β} ) ^{1 / β} · d · ΔT · Δα
(Dmin: minimum bump diameter, β: material constant, V: solder volume, h: solder height, Δα: thermal expansion coefficient difference, ΔT: temperature difference, d: distance from chip center to bump center)
Therefore, in the conventional flip chip mounting technology, the stress generated in the bump electrode has been reduced by using the following means. (1) The distance from the center of the semiconductor chip to the center of the bump electrode is reduced. (2) The difference between the thermal expansion coefficient of the semiconductor chip and the thermal expansion coefficient of the circuit wiring board is reduced. And (4) improving the structure of the bump electrode so that the generated stress strain can be sufficiently absorbed.

  Further, as shown in FIG. 19, the method of injecting resin 78 into the gap between the semiconductor chip 72 and the circuit wiring board 71 and the periphery of the chip, and sealing the semiconductor chip with silicon gel or the like improves the moisture resistance. In addition, it has been proposed to obtain a structure that reduces the stress applied to the bump electrode portion and does not reduce the cycle life.

  However, the mounting method for filling the gap between the semiconductor chip and the circuit wiring board (Japanese Patent Laid-Open No. 57-208149, Japanese Utility Model Laid-Open No. 58-18348) does not specify the physical properties of the resin. Destruction was sometimes accelerated. In addition, in order to smoothly fill the resin, a method of filling a hole in the glass substrate and filling the resin from the hole (Japanese Utility Model Laid-Open No. 58-18348, Japanese Patent Laid-Open No. 58-103143, etc.) It is clear that cracks are generated around the hole provided in the substrate due to the cycle stress, and there are practical problems and the reliability of the bump connection portion cannot be guaranteed.

  For this reason, as shown in FIG. 20, it has been proposed to improve the reliability of the bump connection part by not filling the region 81 surrounded by the semiconductor chip 72, the circuit wiring board 71 and the bump electrode 73. (Japanese Patent Laid-Open Nos. 58-204546, 57-208149, 58-134449, etc.). There was a problem that corrosion occurred.

  Further, an assembly structure is formed which has a concave-convex shape by sealing at least one portion outside the solder connection point where the array bump is formed and leaving the upper and lower surfaces adjacent to the solder connection portion in the center portion without being embedded with a dielectric material. A method for improving the reliability of the body (Japanese Patent Laid-Open No. 61-1777738) has been proposed. However, in the case of an organic polymer substrate having a very large difference in thermal expansion coefficient, the stress cannot be sufficiently relaxed. It was.

  Also, a method of filling a soft resin in the gap between the semiconductor chip and the circuit wiring board is disclosed (Japanese Patent Laid-Open No. 58-10841). However, since the thermal expansion coefficient of the soft resin is very large, the bump connection portion is also disclosed. The improvement of the thermal cycle life is not sufficient.

  In order to solve these problems, it has been proposed to improve the thermal cycle life of the bump connection portion by selecting the physical properties and composition of the resin (Japanese Patent Publication No. 4-51057, Japanese Patent Laid-Open No. Sho 63-316447). In the case of mounting a semiconductor chip having a relatively small size, the effect was exhibited.

  When resin is placed in the gap between the semiconductor chip and the circuit wiring board, the resin is applied in advance to the surface of the semiconductor chip or the semiconductor chip mounting position of the circuit wiring board, and the semiconductor chip is connected and bonded to the circuit wiring board. Methods (Japanese Patent Laid-Open No. 4-7447, Japanese Patent Laid-Open No. 2-234447, etc.) are typical. After an appropriate amount of sealing resin is applied to a part of the substrate excluding the bump electrodes, the semiconductor chip is assembled. There has also been proposed a method (such as Japanese Patent Application Laid-Open No. Sho 62-132331) in which a resin is arranged in the entire gap to avoid poor connection.

  Further, after flip-chip mounting of the semiconductor chip on the circuit wiring board, a resin is sealed in a gap portion between the semiconductor chip and the circuit wiring board using a capillary phenomenon (Japanese Patent Laid-Open Nos. 60-147140 and 3). In this case, the resin is sealed in a gap of about 20 μm to 50 μm by lowering the resin viscosity by heating the resin below the curing temperature.

  However, when the resin is injected into the gap between the semiconductor chip and the circuit board by using capillary reduction as described above, it becomes difficult to encapsulate the resin as the size of the semiconductor chip increases.

The injection rate of the resin is expressed by V = 1200 h / (μL) (h is the gap size (mm), μ is the viscosity (poise), and L is the inflow distance (mm)). That is, the injection speed is proportional to the distance (gap size) between the semiconductor chip and the circuit board, and inversely proportional to the viscosity and the size of the semiconductor chip, so that the resin viscosity decreases as the size of the semiconductor chip increases. It is also necessary to take measures such as increasing the gap size.

  In order to reduce the difference in coefficient of thermal expansion between the semiconductor chip and the circuit board, it is necessary to mix filler into the resin, but the viscosity of the resin increases due to the filler being mixed. On the other hand, the gap size is equal to the height of the bump after connection. However, since the bump melts into a spherical shape at the time of connection, it is impossible to make the bump height higher than the bump diameter. Therefore, there is a limit to the height of the bump, and it is difficult to increase the distance between the semiconductor chip and the circuit wiring board to facilitate resin encapsulation.

Further, as shown in FIG. 21, the injection rate of the resin rapidly decreases as the inflow distance increases. The curves shown in FIG. 21 are the results obtained with respect to resins having five types of viscosity of 10 to 100 poise with the distance (gap size) between the semiconductor chip and the circuit board being 0.5 mm.

  Further, when the resin is injected into the gap between the semiconductor chip and the circuit board, the resin 86 is not limited to the gap between the chip 84 and the substrate 83, as shown in FIGS. Proceed around 84. Since the flow rate of the resin is larger in the periphery of the chip as compared with the center portion of the chip, there is a possibility that bubbles 87 are finally generated as shown in FIG.

  Further, Japanese Patent Laid-Open No. 63-245942 proposes a structure in which a bump is exposed around a semiconductor chip and a semiconductor active element portion is a recess. In this structure, the semiconductor at the bump connection portion is proposed. There was a problem that the gap between the chip and the circuit wiring board became narrower than the bump height, making it difficult to encapsulate the resin.

  In order to relieve the stress generated in the bump electrode connecting the semiconductor chip and the circuit wiring board, it is preferable to dispose a resin having a small thermal expansion coefficient in the gap between the semiconductor chip and the circuit board. Therefore, conventionally, by increasing the filler content, a resin having a reduced thermal expansion coefficient and an increased elastic coefficient has been disposed in the gap between the semiconductor chip and the circuit wiring board. From the viewpoint of moisture shielding, it is preferable that the filler content is high, and that the larger the particle size of the filler, the better the moisture shielding effect.

  However, in recent years, as the dimensions of semiconductor chips increase, problems that cannot be dealt with by conventional resins have occurred, and it has become difficult to ensure sufficient reliability of semiconductor devices. That is, since the resin having a high filler content has a high viscosity, it cannot be injected into the gap between the semiconductor chip and the circuit board.

  In addition, a resin containing a filler with a large particle size cannot cope with the finer pitch of the bump electrodes and cannot be injected into the inner region of the bump electrodes. Even in the case of a resin containing filler that can be injected, the filler may pass through the passivation film of the semiconductor chip and destroy the semiconductor chip.

  In addition to the above-described problems, as the size of the semiconductor chip increases, it becomes easier for air bubbles to be entrained in the resin when the resin is injected into the gap between the semiconductor chip and the circuit board, resulting in a decrease in mechanical strength and into the air bubbles. There is a problem that reliability of the wiring is lowered due to corrosion of the wiring due to the dew condensation.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a semiconductor device in which generation of bubbles in a resin disposed in a gap between a semiconductor chip and a circuit board is prevented and reliability is improved.

  In order to solve the above problems, the present invention comprises a circuit wiring board and a semiconductor chip mounted on the board via bump electrodes, and the gap between the circuit wiring board and the semiconductor chip and the semiconductor chip. In the semiconductor device in which resin is arranged around, the bump electrode is formed through the connection electrode along the outer periphery of the semiconductor chip, and the connection electrode is within a region surrounded by the bump electrode on the surface of the circuit wiring board. A semiconductor device is provided in which a recess is formed in a region 0.3 mm to 2.0 mm inside from the inner end of the semiconductor device.

ADVANTAGE OF THE INVENTION According to this invention, the semiconductor device which prevented generation | occurrence | production of the bubble in resin arrange | positioned in the clearance gap between a semiconductor chip and a circuit board, and improved reliability is provided.

In the semiconductor device of the present invention, a recess is formed in a portion corresponding to the center of the semiconductor chip on the surface of the circuit board. For this reason, the speed of the resin at the central portion of the semiconductor chip is increased and the injection into the gap portion is facilitated, while the sealing speed of the resin at the peripheral portion of the semiconductor chip is not increased. That is, since the difference in the resin injection speed between the peripheral portion and the central portion of the semiconductor chip is reduced, it is possible to prevent bubbles from being involved in the resin.

  Furthermore, the present inventors have found that the flow rate of the sealing resin increases as the amount of resin applied increases in the region outside the bump electrode (outer peripheral portion of the semiconductor chip), whereas the region inside the bump electrode. Then, it discovered that it did not depend on the application quantity of resin. The present invention has been made based on such knowledge.

That is, in the present invention, the amount of resin applied to the gap between the semiconductor chip and the circuit board and the periphery of the semiconductor chip is limited to 1 to 3 times the volume of the gap. Can be prevented.

  Hereinafter, the present invention will be described in more detail with reference to the drawings.

(Reference Example I)
FIG. 1 shows a cross-sectional view of the semiconductor device of Reference Example I, and FIG. 2 shows a plan view of this device.

  As shown in FIG. 1, in a semiconductor device 9, a semiconductor chip 1 is mounted on a circuit wiring board 2 on which connection terminals 4 are formed via bump electrodes 3 and Al bonding pads 8. Further, as shown in FIG. 2, the first resin 5 is disposed in the gap between the semiconductor chip 1 and the circuit wiring board 2, that is, inside the region surrounded by the outermost peripheral bump electrode. On the other hand, the second resin 6 is disposed in an outer region not surrounded by the outermost peripheral bump electrode. Note that the area surrounded by the outermost bump electrode specifically refers to the area where the center line 7 of the outermost bump electrode is connected.

  As the resin, an inorganic filler can be used, and a solvent-free thermosetting resin can be used. For example, among phenolic epoxy resins, bisphenol type epoxy resins, acid anhydride curing agents, and imidazole curing catalysts. Or dimethylpolysiloxane as a silicone rubber, a mixture of organic peroxides, or a polyimide resin, a maleimide resin, a polyurethane resin, an acrylic resin, a phenolic epoxy resin, or the like. As the inorganic filler, silica, quartz, fused silica and the like can be used.

  The filler content and particle size contained in the first resin and the second resin can be determined by their relative relationships. That is, in the first resin, fillers having a particle size smaller than the maximum particle size and average particle size of the filler contained in the second resin are mixed and used in a smaller proportion than the second resin. For example, the filler content in the first resin is preferably 45% by weight or less, and more preferably 40% by weight or less. Further, the maximum particle size and the average particle size of the filler are preferably 45 μm or less and 25 μm or less, respectively, more preferably 40 μm or less and 20 μm or less, respectively.

  On the other hand, the filler content in the second resin is preferably 50% by weight or less, and more preferably 45% by weight or less. The maximum particle size and the average particle size of the filler are preferably 60 μm or less and 40 μm or less, respectively, and more preferably 50 μm or less and 45 μm or less, respectively.

  Furthermore, the occurrence of defects due to corrosion can be prevented by reducing at least one of the amount of sodium ions and the amount of chlorine ions contained in the first resin as compared to the second resin.

  In this case, the amount of sodium ions and the amount of chlorine ions in the first resin are preferably, for example, 1 ppm or less and 5 ppm or less, respectively, and the amount of sodium ions and the amount of chlorine ions in the second resin are For example, it is preferably 10 ppm or less and 10 ppm or less, respectively.

  The semiconductor device shown in FIG. 1 can be manufactured by the following processes, for example. 3 and 4 are process diagrams showing a first example of the manufacturing method.

  First, a semiconductor chip 1 as shown in FIG. 3A and a circuit wiring board 2 as shown in FIG. 3B are prepared. The bump electrode 3 on the back surface of the semiconductor chip 1 can be formed by using, for example, a vapor deposition method or an electroplating method. Generally, solder is used as the material of the bump electrode, but is not limited thereto. For example, a metal such as Au or Cu having rigidity compared to solder may be used. .

  The size of the semiconductor chip, the number of bump electrodes, and the bump pitch can be set arbitrarily, and the layout may be an area, and is not limited at all.

  Here, a 10 mm × 10 mm semiconductor chip was used to form the Cu / Ti barrier metal 10, and then a bump 3 having a diameter of 100 μm and a height of 75 μm ± 5 μm was formed from a Pb / Sn = 40/60 alloy. In addition, 256 bumps were arranged along the periphery of the semiconductor chip.

  That is, as shown in FIG. 3A, an Al bonding pad 8 and a passivation film 11 are formed on the surface of the semiconductor chip 1, and bumps are formed on the surface of the Al bonding pad 8 via the barrier metal 10. An electrode 3 is formed.

  Moreover, the material and structure of the circuit wiring board 2 are not particularly limited, and for example, a laminated glass epoxy board or the like can be used. Hereinafter, a printed circuit board SLC (Surface Laminar Circuit) substrate in which an insulating layer and a conductor layer are built up on a glass epoxy substrate will be described as a substrate.

  That is, as shown in FIG. 3B, the circuit wiring board 2 is provided with a 110 μmφ opening in the connection terminal portion 4 for the bump electrode of the semiconductor chip, and Cu as a terminal material is exposed, A solder resist 12 is coated on portions other than the terminal portion of the substrate.

  On the circuit wiring board 2 having such a configuration, as shown in FIG. 3C, the semiconductor chip 1 is aligned using a flip chip bonder, and the bump electrodes 3 and the connection terminals 4 of the circuit wiring board 2 are aligned. Are brought into electrical and mechanical contact. At this time, the circuit wiring board 2 is held on a stage 13 having a heating mechanism and preheated to 200 ° C. higher than the melting point of Pb / Sn = 40/60 in a nitrogen atmosphere.

  Further, the semiconductor chip 1 and the circuit wiring board 2 are kept in contact with each other, and the collet 14 holding the semiconductor chip is heated to the same temperature as the stage 13 described above at 200 ° C. in a nitrogen atmosphere. Thereby, the solder is melted, and the semiconductor chip 1 and the electrodes of the circuit wiring board 2 are temporarily connected electrically and mechanically. Finally, the circuit wiring board 2 on which the semiconductor chip 1 is mounted is passed through a reflow furnace heated to 250 ° C. in a nitrogen atmosphere, and the semiconductor chip and the circuit wiring board are electrically and mechanically connected.

  At this time, a self-alignment effect is generated by the surface tension of the solder, and a slight positional deviation generated during mounting is corrected, so that bonding can be performed at an accurate position.

  Through the above steps, a structure in which the semiconductor chip 1 is mounted on the circuit wiring board 2 with bumps as shown in FIG. Next, as shown in FIG. 4A, the first resin is potted by a dispenser 15 in a gap formed by the semiconductor chip 1 and the circuit wiring board 2. The resin 5 is injected into a region surrounded by the bump electrode 3 by a capillary phenomenon, and is arranged as shown in FIG.

  As the resin, a resin containing a bisphenol-based epoxy, an imidazole curing catalyst, an acid anhydride curing agent, and a spherical quartz filler (maximum particle size 20 μm, average particle size 5 μm) was used. The filler content was 30% by weight, and about 4 ml of resin having such a composition was disposed.

  Since the first resin has a composition different from that of the second resin to be disposed later, the gelation time of the region surrounded by the bump electrode 3 is shortened. Therefore, since the semiconductor chip 1 is temporarily fixed by injecting the first resin, the semiconductor chip 1 can be flip-chip mounted on the circuit wiring board 2 with high reliability.

  Subsequently, as shown in FIG. 4C, the second resin 6 is potted around the semiconductor chip 1 to seal the resin in a region not surrounded by the bump electrodes by using a capillary phenomenon.

  The second resin has the same composition as the first resin except that a spherical quartz filler having a maximum particle size of 35 μm and an average particle size of 10 μm is mixed at a ratio of 45% by weight. About 2 ml.

  The amount of the resin to be arranged can be appropriately selected for the first and second resins depending on the dimensions of the semiconductor chip, the height of the bump electrodes, and the like. Furthermore, the semiconductor device shown in FIG. 1 is obtained by storing in a clean oven at 80 ° C. for 4 hours and curing the arranged resin.

  In addition, the arrangement | positioning method of 1st and 2nd resin is not limited to the above-mentioned example, You may arrange | position as follows. FIG. 5 is a process chart showing a second example of the method for manufacturing the semiconductor device shown in FIG. The semiconductor chip and the circuit wiring board used here have the same structure as that shown in FIG. 3A and FIG. 3B, respectively, and the same composition as that used in the first example. The same amount of resin is placed.

  First, as shown in FIG. 5A, the first resin 5 is potted in advance in a region surrounded by the bump electrodes 3 on the circuit wiring board 2. Next, as shown in FIG. 5B, the semiconductor chip 1 is aligned on the circuit wiring board 2 by using a flip chip bonder, and the bump electrodes 3 and the connection terminals 4 of the circuit wiring board 2 are arranged. Are electrically and mechanically connected. At this time, the circuit wiring board 2 is held on a stage 13 having a heating mechanism and heated at 200 ° C. in a nitrogen atmosphere.

  The first resin 5 that has been potted in advance is completely enclosed in the gap between the semiconductor chip 1 and the circuit wiring board 2 as shown in FIG. 5C, and the sealed resin is also heated by 200 ° C. It is in the state of temporary hardening.

  Further, in the same manner as in FIG. 4C, the second resin 6 is potted around the semiconductor chip and finally completely cured in a clean oven at 80 ° C. for 4 hours. The first resin 5 may be potted in advance in a region surrounded by the bump electrode 3 on the semiconductor chip 1 as shown in FIG.

  As shown in FIG. 6B, the semiconductor chip 1 on which the first resin is arranged as described above is aligned on the circuit wiring board 2 using a flip chip bonder, and the bump electrode 3 and the circuit wiring board are aligned. Two connection terminals 4 are brought into electrical and mechanical contact. At this time, the circuit wiring board 2 is held on a stage 13 having a heating mechanism and heated at 200 ° C. in a nitrogen atmosphere.

  The first resin 5 is completely enclosed in the gap between the semiconductor chip 1 and the circuit wiring board 2 as shown in FIG. 6C, and the sealed resin is temporarily cured by heat at 200 ° C. Is in a state.

  Further, in the same manner as in FIG. 4C, the second resin 6 is potted around the semiconductor chip and finally completely cured in a clean oven at 80 ° C. for 4 hours. FIG. 7 is a process chart showing a third example of the method for manufacturing the semiconductor device shown in FIG. The semiconductor chip and the circuit wiring board used here have the same structure as that shown in FIG. 3A and FIG. 3B, respectively, and the same composition as that used in the first example. The same amount of resin is placed.

  First, as shown in FIG. 7A, the first resin 5 and the second resin 6 are respectively potted in a region surrounded by the bump electrode 3 on the circuit wiring board 2 and a region not surrounded. Keep it.

  Next, as shown in FIG. 7B, the semiconductor chip 1 is aligned on the circuit wiring board 2 by using a flip chip bonder, and the bump electrodes 3 and the connection terminals 4 of the circuit wiring board 2 are arranged. Are electrically and mechanically connected.

  As shown in FIG. 7C, the pre-potted resins 5 and 6 are respectively disposed in the gap formed by the semiconductor chip 1 and the circuit wiring board 2 and around the semiconductor chip. Note that both the first and second resins are in a temporarily cured state.

  Finally, it is completely cured in a clean oven at 80 ° C. for 4 hours. As shown in FIG. 8A, the first resin 5 and the second resin 6 are potted in a region surrounded by the bump electrode 3 and a region not surrounded by the semiconductor chip 1, respectively. May be.

  The semiconductor chip 1 in which the first resin 5 and the second resin 6 are arranged in this way is aligned on the circuit wiring board 2 using a flip chip bonder, as shown in FIG. The bump electrodes 3 and the connection terminals 4 of the circuit wiring board 2 are brought into electrical and mechanical contact. At this time, the circuit wiring board 2 is held on a stage 13 having a heating mechanism and heated at 200 ° C. in a nitrogen atmosphere.

  The semiconductor device shown in FIG. 1 can be manufactured by various methods as described above. Next, Reference Example I will be described in more detail with a specific example.

  Using the first manufacturing method described above, 256 bump electrodes of Pb / Sn = 40/60 with a diameter of 100 μmφ are formed on a 10 mm × 10 mm semiconductor chip and flip-chip mounted on an SLC substrate. The semiconductor device of Example (I-1) was obtained.

In this reference example (I-1), the elastic coefficient E ₁ of the resin (resin 1) disposed in the region surrounded by the bumps is set to 900 × 10 ⁷ Pa, and the resin is disposed in the region not surrounded by the bumps. The elastic modulus E ₂ of the resin (resin 2) is 1200 × 10 ⁷ Pa. In addition, the thermal expansion coefficient α is 39 × 10 ⁻⁶ / ° C. for any resin, and these physical properties are the maximum particle size and the average particle size, mainly depending on the filler content mixed in the resin, as required. It was determined by changing the resin molecular weight. The filler content in the first resin is 25% by weight, the maximum particle size is 30 μm, the average particle size is 7 μm, the filler content in the second resin is 40% by weight, the maximum particle size is 40 μm, the average The particle size was 15 μm.

  The obtained semiconductor device was subjected to a thermal cycle test, and the relationship between the temperature cycle and the cumulative failure rate was investigated by assuming that the connection was open even at one of the 256 pins, and the obtained result is shown in the curve of FIG. Indicated by a. The number of samples was 1000, and the temperature cycle conditions were (-55 ° C. (30 minutes) to 25 ° C. (5 minutes) to 125 ° C. (30 minutes) to 25 ° C. (5 minutes)).

As shown by the curve a, the elastic coefficient E ₂ of the resin (resin 2) disposed in the region not surrounded by the bump electrode is represented by the elasticity of the resin (resin 1) disposed in the region surrounded by the bump electrode. By making it larger than the coefficient E _1, it can be seen that no defect occurs until 2500 cycles.

Further, a semiconductor device of Reference Example (I-2) was manufactured in the same manner except that resins having different thermal expansion coefficients were used. In this reference example (I-2), the thermal expansion coefficient α ₁ of the resin (resin 1) disposed in the region surrounded by the bumps is 39 × 10 ⁻⁶ / ° C., and the region is not surrounded by the bumps The thermal expansion coefficient α ₂ of the resin (resin 2) disposed on the ^substrate was set to 20 × 10 ⁻⁶ / ° C. The elastic modulus was 900 × 10 ⁷ Pa for all the resins, and these physical properties were determined by changing the filler content mixed in the resin and the molecular weight of the resin as required. The filler content in the first resin is 30% by weight, the maximum particle size is 20 μm, the average particle size is 5 μm, the filler content in the second resin is 45% by weight, the maximum particle size is 35 μm, the average The particle size was 10 μm.

The obtained semiconductor device is subjected to the same thermal cycle test as described above, and the relationship between the number of cycles and the cumulative defect rate is shown by a curve b in FIG. As shown by the curve b, the thermal expansion coefficient α ₂ of the resin (resin 2) in the peripheral region of the semiconductor chip that is not surrounded by the bump electrode is expressed by the resin (resin 1) disposed in the region surrounded by the bump electrode. It can be seen that by making it smaller than the thermal expansion coefficient α ₁ , no defect occurs up to 3500 cycles, and the reliability is greatly improved.

Further, a semiconductor device manufactured in the same manner as above except that a resin having an elastic coefficient of 900 × 10 ⁷ Pa and a thermal expansion coefficient of 39 × 10 ⁻⁶ / ° C. is disposed in the inner and outer regions of the bump electrode is a comparative example (I-1). A semiconductor device manufactured without placing resin was set as Comparative Example (I-2). The semiconductor devices of Comparative Examples (I-1) and (I-2) were subjected to the same thermal cycle test, and the obtained results are shown by curves c and d, respectively.

  As shown in curve c, when resin with uniform physical properties is arranged in the inner and outer regions of the bump electrode, no defect occurs until 2000 cycles, but almost 100% becomes defective in 2500 cycles, and no resin is arranged In (curve d), a defect occurred in 2 cycles, and 100% became defective in 10 cycles or more.

  From the above results, it can be seen that the reliability is remarkably improved by providing a difference in the physical properties of the resin disposed between the region surrounded by the bump electrode and the region not surrounded by the bump electrode.

  Next, a semiconductor device is manufactured by the first manufacturing method described above using two kinds of resins in which the filler content, the average particle diameter, and the maximum particle diameter are changed as described below. -3). In addition, the content of filler mixed in the resin (first resin) arranged in the region surrounded by the bump electrode and the resin (second resin) arranged in the region not surrounded by the bump electrode, the average particle The diameter and the maximum particle diameter are as follows.

1st resin 2nd resin
Filler content (% by weight) 30 45
Average particle size (μm) 5 10
Maximum particle size (μm) 20 35
A high temperature and high humidity bias storage test at 85 ° C., 85%, VDD = 5V was performed on 100 obtained semiconductor devices, and the case where the bump electrode was open or shorted even at one location was regarded as defective, and the storage time and cumulative failure The relationship with the rate was examined, and is shown by a curve e in FIG.

  As shown by curve e, defects are generated up to 3000 cycles by providing differences in filler content, average particle size, and maximum particle size between the region surrounded by the bump electrode and the region not surrounded by the bump electrode. do not do. This is considered to be due to the fact that the resin has a sufficient moisture shielding effect because the filler content, maximum particle size, and average particle size of the resin around the chip are large.

  Furthermore, a semiconductor device manufactured by placing a resin mixed with filler having an average particle size of 7 μm and a maximum particle size of 20 μm at a ratio of 40% by weight in the inner and outer regions of the bump electrode is referred to as Comparative Example (I-3). A semiconductor device manufactured without arranging was used as Comparative Example (I-4). About the semiconductor device of these comparative examples (I-3) and comparative examples (I-4), the same test as the above-mentioned reference example (I-3) was conducted, and the obtained results are shown in FIG. Indicated by f and curve g.

  When a uniform resin is disposed in the inner and outer regions of the bump electrode as shown by the curve f, the occurrence of a defect can be suppressed until exceeding 2000H, but a defect occurs at 2300H and the resin is not disposed. In (curve g), a defect occurred at 500H, and when the storage time exceeded 1000H, 100% became defective.

  From the above results, it can be seen that the semiconductor device of this reference example has excellent reliability even under high temperature and high humidity.

Example I
Hereinafter, a semiconductor device of the present invention will be described in detail with reference to the drawings.

  FIG. 11 is a cross-sectional view illustrating an example of the semiconductor device of the present invention. As shown in FIG. 11, in the semiconductor device 20 according to the present invention, a connection electrode 24 formed along the outer periphery of a silicon semiconductor chip 23 is connected to a connection electrode 22 of a circuit board 21 by a solder bump 25. . A resin 26 is disposed in the gap between the semiconductor chip 23 and the circuit board 21 and in the peripheral portion of the semiconductor chip 23.

The material of the circuit board 21 used in the present embodiment is not particularly limited. For example, an insulating board such as glass epoxy, aramid-epoxy, BT resin, PPE, Al ₂ O ₃ or the like is used. Can be used. A concave portion 27 is formed in a region corresponding to the central portion of the semiconductor chip 23 on the surface of the circuit board 21. The central portion of the semiconductor chip 23 is the inner side of a region surrounded by the connection electrode 24 formed along the outer periphery of the chip, and preferably 0.3 mm to 2 mm from the inner end of the connection electrode 24. It is an area inside about 0 mm.

  The depth of the recess 27 formed on the surface of the substrate 21, that is, the level difference can be appropriately selected depending on the dimensions of the chip 23, the height of the solder bump 25, etc., but is preferably 10 μm or more and 100 μm or less.

  The concave portion 27 on the surface of the circuit board can be formed by, for example, grinding the surface of the circuit board 21. When a glass epoxy board is formed by laminating a plurality of glass epoxy sheets, the top layer of the board is formed. The predetermined area of the sheet may be punched with a press and then laminated to form a recess. Furthermore, the concave portion can be formed in the central portion by applying a solder resist with a predetermined film thickness only to the peripheral portion of the semiconductor chip.

  The connection electrode 24 can be formed by sequentially laminating titanium and copper, for example, and may be sequentially laminated with titanium, copper and gold or palladium. The connection electrode 22 can be formed by sequentially stacking copper, or copper, nickel, and gold. Further, the solder bump 25 has a ratio of Sn to Pb of 6: 4, and its height can be 40 to 80 μm.

  As the resin 26 disposed in the gap, any thermosetting resin mixed with a filler can be used, but those having a viscosity at room temperature of 50 poise or less are preferable. As the filler, for example, spherical quartz filler, silica, pulverized silica, fused silica and the like can be used, and the maximum particle size thereof is 1 of the distance between the semiconductor chip 23 and the substrate 21 in the recess 27. / 2 or less is preferable, and the filler content in the resin is preferably 20 wt% or more and 70 wt% or less.

  This resin is preferably used in a volume of 1 to 2 times the volume of the gap surrounded by the surfaces of the semiconductor chip 23 and the circuit board 21 and the inner surface of the bump electrode.

  The semiconductor device of this embodiment can be manufactured, for example, by the steps shown below. FIG. 12 is a sectional view showing the manufacturing process. First, as shown in FIG. 12A, the semiconductor chip 23 is connected to the circuit board 21 via the solder bumps 25.

  Next, in FIG. 12B, the sealing resin 26 is applied to the end of one of the four sides of the semiconductor chip 23 using the liquid ejection device 30 having a function of controlling the ejection amount. Subsequently, by reducing the viscosity of the resin by heating the circuit board from 40 ° C. to 60 ° C., the resin 26 is formed between the semiconductor chip 23 and the circuit board 21 by capillary action as shown in FIG. Flows into the gap.

  Finally, it is heated in an oven to cure the resin as shown in FIG. The heating is performed at 100 ° C. for 1 hour, and then at 120 ° C. for 3 hours. The atmosphere can be, for example, an air atmosphere, a nitrogen atmosphere having an oxygen concentration of 2% or less, or a reduced pressure atmosphere having a pressure of 1 Pa or less. .

  Through the above steps, the semiconductor device of the present invention is obtained. Next, the present invention will be described in more detail with reference to specific examples. A semiconductor chip (10.2 × 10.4 mm) was connected by solder bumps to connection electrodes of a glass epoxy circuit board (50 × 35 mm) having a recess of 8 × 8 mm and a depth of 50 ± 10 μm formed on the surface. The height of the bump after connection was 70 μm.

  Resin was placed in the gap between the semiconductor chip and the circuit board using the method described above. In this example, bisphenol-based epoxy, imidazole curing catalyst, acid anhydride curing agent, and spherical quartz filler (average particle size 7 μm, maximum particle size 20 μm) are contained at a ratio of about 40% by weight, The viscosity was 40 poise, and the amount was 3 times the volume of the gap.

At this time, the relationship between the inflow distance of the resin and the injection speed was measured and indicated by a curve h in FIG. The inflow distance was measured as shown in FIG. Further, as a comparative example, a resin similar to that described above was injected into a semiconductor device having a conventional structure as shown in FIGS. 14A and 14B, and the relationship between the inflow distance and the injection speed at that time was examined. . In the structure shown in FIG. 14A, the surface of the substrate 31 is flat. In the structure shown in FIG. 14B, in addition to the substrate surface being flat, the epoxy coating 38 is provided around the bumps 25. Is given.

The results obtained when injecting the resin into the structures shown in FIGS. 14A and 14B are shown by curve i and curve j in FIG. 13, respectively. As shown in FIG. 13, as the inflow proceeds, the resin injection rate tends to decrease. However, in the case of the present invention (curve h), the decrease in the injection rate is small and a sufficient rate can be maintained. Therefore, it turns out that impregnation can be performed easily.

On the other hand, as shown by the curve i, when resin impregnation is performed in the structure shown in FIG. 14A, the injection rate in the gap becomes small and impregnation becomes impossible. In such a structure, when a low-viscosity resin is used to facilitate the impregnation, the resin injection speed around the semiconductor chip increases, which may cause air bubbles to be easily involved in the resin. There is.

  Further, as shown by the curve j, in the structure as shown in FIG. 14B, since the gap size at the periphery of the chip on which the solder bump is formed is small, the inflow speed of the resin is in this region. Remarkably reduced. Therefore, it turns out that impregnation becomes impossible.

  Next, the above-mentioned resin was injected by changing the dimensions of the chip, and whether or not the resin was impregnated at that time and whether or not bubbles were involved in the impregnation step were examined. In order to facilitate the observation of the impregnation state of the resin, a glass chip is used, and the chip dimensions are 5.14 × 4.8 mm, 10.2 × 10.4 mm, and 12.52 × 11.96 mm. It was. The dimensions of the recesses on the substrate surface for mounting these chips are 3.2 × 3.0 mm, 8.0 × 8.0 mm, and 11.6 × 11.0 mm, respectively, and the depths of the recesses are all 50 ± 10 μm.

Furthermore, as a comparative example, the same resin was injected into the structure shown in FIG. 14A, and the possibility of resin impregnation at that time and the presence or absence of bubbles in the impregnation step were examined. The obtained results are summarized in Tables 1 and 2 below.

  As shown in Table 1, by setting the substrate temperature to 40 ° C., the semiconductor device of the present invention was able to be impregnated even when the chip size was increased, and bubble entrainment did not occur.

  On the other hand, in the comparative example of the conventional structure, since it was difficult to impregnate the resin at a heating temperature of 40 ° C., the impregnation was also performed in a state where the substrate temperature was set to 80 ° C. and the viscosity of the resin was lowered. As a result, when the substrate temperature is 40 ° C., a sample that cannot be impregnated is generated when a chip of 10.2 mm × 10.4 mm is used, and all of the chips of 12.52 mm × 11.96 mm It became defective. In addition, when the substrate temperature was 80 ° C., bubbles were caught even with the smallest chip of 5.14 mm × 4.8 mm.

  From the above, by forming a recess on the surface of the substrate as in this embodiment, the inflow property during resin impregnation is improved, so that resin sealing of a large semiconductor chip is possible, and further during resin impregnation It can be seen that it is also effective in preventing entrainment of bubbles.

Example II
FIG. 15 is a sectional view showing an example of the semiconductor device of Example II.

  As shown in FIG. 15, in the semiconductor device 40, the connection electrodes 44 of the silicon semiconductor chip 43 are connected to the connection electrodes 42 of the circuit board 41 by solder bumps 45. A resin 46 is disposed in the gap between the semiconductor chip 43 and the circuit board 41 and in the peripheral portion of the semiconductor chip 43.

  The material of the circuit board 41 is not particularly limited. For example, a board made of glass epoxy, aramid epoxy, BT resin, alumina ceramics, aluminum nitride, glass or the like can be used.

  The connection electrode 42 can be formed by sequentially stacking copper, or copper, nickel, and gold. The connection electrode 44 can be formed by sequentially stacking titanium and nickel, or may be formed by sequentially stacking titanium, nickel, gold, or palladium. The solder bump 45 is made of a composition having a ratio of Sn to Pb of 6: 4, and the height thereof can be 50 to 80 μm.

  As the resin 46 disposed in the gap, any thermosetting resin similar to that described in Example I can be used, but the viscosity at room temperature is 50 poise or less. As the filler, the same spherical quartz filler as described above can be used except that the maximum particle size is ½ or less of the distance between the semiconductor chip surface and the substrate surface. In addition, content of the filler in resin shall be 20 to 70 weight%.

  This resin is used in a volume of 1 to 3 times the volume of the gap surrounded by the surfaces of the semiconductor chip 23 and the circuit board 21 and the inner surface of the bump electrode. The semiconductor device shown in FIG. 15 can be manufactured by the following processes, for example. FIG. 16 is a sectional view showing the manufacturing process.

  First, as shown in FIG. 16A, the semiconductor chip 43 is connected to the circuit board 41 via the solder bumps 45. Next, in FIG. 16B, the sealing resin 46 is applied to the end of one of the four sides of the semiconductor chip 43 using the liquid ejection device 50 having a function of controlling the ejection amount.

  Subsequently, by reducing the viscosity of the resin by heating the circuit board from 40 ° C. to 60 ° C., the resin 46 is formed between the semiconductor chip 43 and the circuit board 41 by capillary action as shown in FIG. Flows into the gap.

  Finally, it is heated in an oven to cure the resin as shown in FIG. The heating is performed at 100 ° C. for 1 hour, and then at 120 ° C. for 3 hours. The atmosphere can be, for example, an air atmosphere, a nitrogen atmosphere having an oxygen concentration of 2% or less, or a reduced pressure atmosphere having a pressure of 1 Pa or less. .

Through the above steps, the semiconductor device shown in FIG. 15 is obtained. Next, this example will be described in more detail with reference to specific examples. A semiconductor chip (10.2 × 10.4 mm) was connected to a connection electrode of a glass epoxy circuit board (50 × 35 mm) by solder bumps. The height of the bump after connection was 70 μm, and the volume of the gap surrounded by the substrate, chip and bump electrode was 7.4 mm ³ .

  Further, a resin was disposed in the gap between the semiconductor chip and the circuit board using the method described above. Here, it contains bisphenol-based epoxy, imidazole curing catalyst, acid anhydride curing agent and spherical quartz filler (average particle size 5 μm, maximum particle size 12 μm) in a proportion of about 40% by weight, and the viscosity at room temperature is 30 poise. The volume of the resin was 1.5 times the volume of the region surrounded by the semiconductor chip, the circuit board, and the bump electrodes.

First, the volume of the resin to be arranged was changed, and the relationship between the resin amount and the injection rate at the chip center and the chip periphery was examined. The obtained result is shown in FIG. Incidentally, infusion rate, using the average value of the injection rate of the resin of the sealing resin of the semiconductor chips from the sides coated to a distance of 5 mm.

As shown in FIG. 17, the speed of the resin flowing around the semiconductor chip increases rapidly as the amount of resin applied increases. On the other hand, the injection speed at the center of the chip is substantially constant regardless of the coating amount. Therefore, the smaller the amount of resin applied, the smaller the difference between the injection rate at the periphery and center of the chip.

Next, by changing the amount of resin applied, various types of samples were prepared in the process shown in FIG. 16 and the number of voids was examined. The circuit board, semiconductor chip, and resin were the same as described above. The obtained results are shown in Table 3 below.

  As shown in Table 3, when the volume of the sealing resin is 5 times or more the volume of the gap between the semiconductor chip and the circuit board, entrainment of bubbles occurs. Therefore, the generation of voids can be prevented by limiting the volume of the resin to 3 times or less of the gap volume.

Sectional drawing which shows the semiconductor device of a reference example. The top view which shows the semiconductor device of a reference example. Sectional drawing which shows an example of the manufacturing process of the semiconductor device of a reference example. Sectional drawing which shows an example of the manufacturing process of the semiconductor device of a reference example. Sectional drawing which shows the other example of the manufacturing process of the semiconductor device of a reference example. Sectional drawing which shows the other example of the manufacturing process of the semiconductor device of a reference example. Sectional drawing which shows the other example of the manufacturing process of the semiconductor device of a reference example. Sectional drawing which shows the other example of the manufacturing process of the semiconductor device of a reference example. The graph which shows the relationship between a cycle number and a cumulative defect rate. The graph which shows the relationship between holding time and a cumulative defect rate. FIG. 10 is a cross-sectional view illustrating an example of a semiconductor device of the invention. Sectional drawing which shows the manufacturing process of the semiconductor device which concerns on this invention. The figure which shows the relationship between the inflow distance of resin, and injection | pouring speed . Sectional drawing which shows the semiconductor device of the conventional structure. Sectional drawing which shows the other example of the semiconductor device concerning this invention. Sectional drawing which shows the other example of the manufacturing process of the semiconductor device concerning this invention. The graph which shows the relationship between resin application amount and injection | pouring speed | rate . Sectional drawing which shows the conventional semiconductor device. Sectional drawing which shows the conventional semiconductor device. Sectional drawing which shows the conventional semiconductor device. The graph which shows the relationship between the inflow distance of resin, and injection | pouring speed . The figure which shows the inflow state of the resin inject | poured between the semiconductor chip and the circuit board.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Semiconductor chip, 2 ... Circuit wiring board, 3 ... Bump electrode, 4 ... Connection terminal 5 ... 1st resin, 6 ... 2nd resin, 7 ... Center of outermost periphery bump electrode 8 ... Al bonding pad, 9 ... Semiconductor device, 10 ... Barrier metal 11 ... Passivation film, 12 ... Solder resist, 13 ... Stage 14 ... Collet, 15 ... Dispenser, 20 ... Semiconductor device, 21 ... Circuit board 22 ... Connection electrode, 23 ... Semiconductor chip, 24 ... Connection electrode, 25 ... Solder bump 26 ... Resin, 27 ... Recess, 28 ... Liquid discharge device, 30 ... Semiconductor device, 31 ... Circuit board 32 ... Connection electrode, 33 ... Semiconductor chip, 34 ... Connection electrode, 35 ... Solder bump 36 ... Resin 37 ... Semiconductor device, 38 ... Epoxy coating layer, 40 ... Semiconductor device 41 ... Circuit board, 42 ... Connection electrode, 43 ... Semiconductor chip , 44 ... Connection electrodes 45 ... Solder bumps, 46 ... Resin, 48 ... Liquid ejection devices, 70 ... Semiconductor devices 71 ... Circuit wiring boards, 72 ... Semiconductor chips, 73 ... Bump electrodes, 74 ... Connection terminals 75 ... Connection terminals, DESCRIPTION OF SYMBOLS 77 ... Semiconductor device, 78 ... Conventional resin, 80 ... Semiconductor device 81 ... Gap part, 83 ... Circuit board, 84 ... Semiconductor chip, 85 ... Bump electrode 86 ... Resin, 87 ... Bubble.

Claims (1)

In a semiconductor device comprising a circuit wiring board and a semiconductor chip mounted on the board via bump electrodes, and a resin disposed in the gap between the circuit wiring board and the semiconductor chip and around the semiconductor chip,
The bump electrode is formed through a connection electrode along the outer periphery of the semiconductor chip, and is 0.3 mm to 2.0 mm from the inner end of the connection electrode in a region surrounded by the bump electrode on the surface of the circuit wiring board. A semiconductor device, wherein a recess is formed in an inner region .

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