JP2007081266A - Method for repairing semiconductor device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To remove a semiconductor chip resin-sealed by underfill from a wiring board, leaving little resin residue and without damaging the substrate surface. <P>SOLUTION: In the method for repairing a semiconductor device, a separating plate 12 is inserted, while the adhesion strength of sealing resin 9 is made reduced by heating, into a gap between a wiring board 10 and a semiconductor chip 1 (Fig. (b)) to peel off the sealing resin 9 from the wiring board 10, thus removing the semiconductor chip 1 (Fig. (c)). It is desirable that the adhesion strength of the sealing resin 9 be 3.43 N/mm<SP>2</SP>or less when inserting the peeling plate into the gap between the semiconductor device and the wiring board. Further, it is desirable that particles with a multilayer structure having a siloxane framework be added to the sealing resin. <P>COPYRIGHT: (C)2007,JPO&amp;INPIT

Description

  The present invention relates to a repair method of a semiconductor device in which a plurality of semiconductor devices are mounted on a wiring board by flip-chip connection, and each semiconductor device is resin-sealed by underfill, and only defective semiconductor devices are selected. The present invention relates to a method for repairing a semiconductor device, which can be removed in an effective manner, has a small amount of sealing resin residue left on a wiring board when a semiconductor device is removed, and can be repaired in a short time.

  With the rapid development of electronic equipment, semiconductor devices such as LSIs are required to have higher functionality than ever. As the number of functions of a semiconductor device increases, the number of input / output terminals of the semiconductor device increases, and the wiring length for operating the semiconductor device at high speed is required to be shortened. As a connection method developed to realize such a requirement, there is a flip chip connection. Flip chip connection is suitable for increasing the number of pins because a connection pad can be provided on the wiring surface of the semiconductor chip on the area. Further, compared with other semiconductor chip connection methods such as wire bonding and tape automated bonding (TAB), the lead length is not required, so that the wiring length can be shortened. In general, many of the high-functional semiconductor devices that are flip-chip connected are high-value-added, and the fine wiring board on which these semiconductor devices are mounted is very expensive because it requires a multi-layered substrate. There is a very strong demand for improving the yield.

  As described above, an increasing number of semiconductor devices used in high value-added electronic devices use flip chip connection. On the other hand, many flip-chip connected semiconductor devices are connected by injecting and curing a liquid sealant called sealing resin in the connection part to alleviate the difference in thermal expansion between the semiconductor device and the wiring board. It is necessary to ensure reliability. By this resin sealing, it is possible to improve the drop impact resistance, thermal shock resistance, vibration resistance, dust resistance, and water resistance.

  Materials used for resin sealing include epoxy resin, silicone resin, phenolic resin, diallyl phthalate resin, polyimide resin, acrylic resin, urethane resin, etc., but heat resistance, moisture resistance, chemical resistance, adhesion, cost, etc. Epoxy resin, which is superior in terms of the above, is widely used. Many sealing resins including epoxy resins have high adhesive strength, so high mounting reliability can be ensured. On the other hand, once the resin is cured by heat treatment, its high resin strength and adhesive strength. It will be very difficult to remove. Therefore, it is very difficult to replace a defective part when a semiconductor device or a wiring board is defective, and there is a problem that the mounting cost is increased. Especially for high-value servers such as high-end servers and high-end computers, several tens of semiconductor devices may be mounted on a single fine wiring board. If all parts are discarded, a very large cost loss is incurred.

  There are mainly two types of substrates on which semiconductor devices are mounted, those using ceramics and those using organic materials. Many of the wiring boards used for high-density mounting use organic materials because they are excellent in narrowing the pitch, are lightweight, and are low in cost. Many high-density wiring boards have a laminated structure called build-up (see FIG. 1). The build-up wiring board is composed of two parts, a core layer and a build-up layer. The core layer serves as a structural support that reduces the warping of the wiring board and improves the mounting yield, and uses a high-density wiring layer at a low density by taking charge of the low-density wiring layer such as the power supply layer. It plays a role to balance the wiring density.

  Organic substrates that are advantageous in that they can draw narrow pitch wiring include acrylic, polyolefin, polyurethane, polycarbonate, polystyrene, polyether, polyamide, polyimide, fluorine-containing polymer, polyester, phenolic resin, fluorene resin, benzoic acid. Although there are various materials such as cyclobutene and silicone-based polymers, epoxy resins that are excellent in terms of cost, low thermal expansion, low dielectric loss, heat resistance and the like are generally used. Also, a solder resist is applied to the outermost layer of the wiring board for the purpose of preventing solder flow. Many of the solder resists are epoxy resins as well as the substrate material and the sealing resin, and it can be said that many of the current organic wiring boards are formed of an epoxy resin.

Next, the prior art of the sealing resin that enables repair will be described. As a first method, a thermoplastic component is added to the sealing resin, and the adhesion strength of the resin or the resin strength is reduced by exposing to a high temperature to remove the semiconductor chip, and the residue left on the substrate The concept including the process of removing resin by utilizing the plasticity under high temperature is devised (for example, refer patent documents 1-3).
However, with regard to the addition of general thermoplastic components, such as deterioration of filling properties in narrow gaps due to thickening and thixotropy (thixotropy) expression, reduced connection reliability due to increased linear expansion coefficient, reduced migration resistance, etc. In many cases, the performance is deteriorated, and it is difficult to satisfy the filling property, the connection reliability, and the repair property at the same time.

  Other removal methods include using an organic solvent and swelling the sealing resin to reduce the adhesion strength between the sealing resin and the wiring board, the resin strength, removing the semiconductor chip, and removing the residual resin. It has been devised (for example, see Patent Documents 2, 4, and 5). However, since many of the sealing resins and wiring boards that are currently used are epoxy resins, the solvent for removing resin residues can swell not only the sealing resin but also the wiring board, causing delamination of the build-up board There is. Furthermore, the state of the surface of the wiring board changes depending on the solvent for removing the resin residue, and there is a possibility that the refillability of the sealing resin is deteriorated when the wiring board is reused. As described above, when the solvent is used, it is generally difficult to selectively remove only the sealing resin without affecting the wiring board.

In view of the above concerns, a method of making the mounting form itself reusable structure has been devised in preparation for occurrence of defects. As an example of this, a method has been devised in which an interposer structure is taken when a semiconductor chip is mounted and the interposer is removed by solder reflow when a defect occurs (for example, see Patent Document 6).
However, the mounting method using an interposer is generally disadvantageous for high-speed signal propagation because of the long wiring length, and has a drawback that it is difficult to achieve impedance matching. In addition, the interposer structure increases the mounting area and mounting height, and there is a disadvantage that it is impossible to achieve both miniaturization and high density. As described above, the repair of the semiconductor device by adopting the interposer structure is not sufficient as a fundamental problem solving means.
As a sealing resin removing method that does not require a solvent, a method of removing a resin residue by irradiating the resin residue with an electromagnetic wave (see, for example, Patent Document 7), a wiring board that transmits laser light is used for mounting, and a semiconductor chip. Has been devised, such as a method of irradiating laser light from the back surface where the sealing resin is mounted to weaken the adhesion of the sealing resin (see, for example, Patent Document 8).
However, since most of the sealing resin currently used and the substrate material of the wiring board are both epoxy resin, it is difficult to selectively process only the sealing resin, and it is possible to remove the sealing resin. When the laser beam is irradiated with the intensity of 1, the sealing resin refillability at the time of reuse of the wiring board may be deteriorated due to the damage of the wiring board and the change of the wiring board surface state. Also, many of the wiring boards currently used do not have laser transparency, and it is difficult to solve the problem by the method of Patent Document 9. As described above, it is difficult to selectively process only the sealing resin by a method using non-contact energy.
JP 2000-323193 A Japanese Patent Laid-Open No. 11-274376 Japanese Patent Laid-Open No. 9-221650 Japanese Patent Laid-Open No. 10-67916 JP-A-7-102225 Japanese Patent Laid-Open No. 4-124845 JP-A-6-77264 JP-A-4-257240

  As described above, according to the prior art, the semiconductor device and the sealing resin are selectively removed without damaging the wiring board, and none of the filling property, connection reliability, and repair property can be satisfied at the same time. Further, one of the major causes that makes it difficult to repair a resin-encapsulated semiconductor device is a problem in a cleaning process of removing a resin composition remaining on a surface to be regenerated such as a substrate after removing a repair component. The first problem is that the substrate surface which is the reproduction surface is damaged during the cleaning operation and cannot be reused. The second problem is that even if the reproduction surface can be cleaned, the fine residue of the resin composition generated during cleaning enters the electrode portion of the reproduction surface and enters the electrode portion during component remounting. This is a problem that causes poor connection due to the residue of the resin composition. The third problem is that the cleaning process takes a lot of time. As for the removal of the resin composition, it is a matter of course that careful work is required so as not to damage the reproduction surface, but when it is necessary to remove the residue of the resin composition that has entered the fine electrode portion. Therefore, it is necessary to carry out the removal work for each of the many electrodes, and the effort is enormous.

  An object of the present invention is to solve the above-described problems of the prior art, and the purpose thereof is to remove a resin to be repaired without damaging the semiconductor device or the wiring board when removing the semiconductor device to be repaired. It is an object of the present invention to provide a repair method in which most of the composition is peeled off from the interface of a reused substrate or the like to minimize the resin residue, and the cleaning process can be performed easily and reliably. It is another object of the present invention to provide a repair method capable of reliably removing only a device to be repaired even when a plurality of semiconductor devices are mounted adjacent to each other.

  In order to achieve the above object, according to the present invention, one or more semiconductor devices are connected to a wiring board, and pads of the semiconductor device are connected to substrate-side pads on the wiring board via conductive bumps. A method for repairing a semiconductor device, wherein a gap between the semiconductor device and the wiring board is filled with a sealing resin, and at least the semiconductor device to be repaired is heated to reduce the adhesion strength of the sealing resin And the semiconductor device is separated from the wiring board by inserting a plate thinner than the gap between the semiconductor device and the wiring board into the gap between the semiconductor device and the wiring board. A repair method is provided.

Preferably, particles having a multilayer structure having a siloxane skeleton are added to the sealing resin. Or the particle | grains of a multilayer structure whose core part has lower hardness than a shell part are added to sealing resin. Preferably, the core portion of the multi-layered particle is composed of a linear polymer, and the shell portion is composed of a three-dimensional polymer. Or the core part of the particle | grains of a multilayer structure is a silicone rubber, and a shell part is a silicone resin. Further, preferably, the adhesion strength of sealing resin at the time of inserting the plate into the gap between the semiconductor device and the wiring board is less than ^{3.43N / mm 2 (350gf / mm} 2).

  With a sealing resin whose adhesion strength has been reduced by heating, it becomes possible to insert a metal-made peeling plate, which enables the sealing resin to be peeled from the wiring board, and a resin-sealed semiconductor device Can be easily separated from the wiring board. Moreover, the resin residue on a wiring board can be decreased. Further, by using a sealing resin in which particles having a multilayer siloxane skeleton are added to a sealing resin mainly composed of an epoxy resin, it becomes possible to easily reduce the adhesion strength of the sealing resin by heating. -The sealing resin can be easily peeled off from the substrate surface when removing the semiconductor device using the substrate, making it possible to eliminate almost any resin component remaining on the surface to be regenerated on the substrate after separation of the semiconductor device. Become. Therefore, the cleaning of the substrate surface following the removal of the semiconductor device is facilitated, the regeneration of the substrate surface can be ensured, and the repair operation can be performed easily and reliably in a short time.

FIG. 1 shows an example of a module (MCM) in which a plurality of semiconductor devices such as LSIs are flip-chip mounted on one build-up wiring board as an example of a semiconductor device that implements the repair method of the present invention (however, FIG. 1 shows only one of the flip-chip mounted semiconductor chips). The build-up wiring board 3 has one or more insulating layers 4 (two layers in the illustrated example) formed of a photosensitive resin layer, a prepreg cured layer, etc., and the wiring 5 is formed on the insulating layer 4. Has been. A solder resist 7 is formed on the surface of the build-up wiring board 3, and a region of the uppermost wiring 5 that is not covered with the solder resist 7 is a board-side pad 6. A chip-side pad 2 is formed on the semiconductor chip 1, and the chip-side pad 2 and the substrate-side pad 6 are electrically connected by solder bumps 8. A gap between the semiconductor chip 1 and the buildup wiring board 3 is filled with a sealing resin 9. FIG. 1 shows a flip chip as a semiconductor device. However, the semiconductor device to be repaired in the present invention is not limited to a flip chip, and is a device connected to a wiring substrate via a conductive bump. If so, any of a bare chip, a CSP (chip size package), a BGA (ball grid array), etc. may be used.
The material that establishes electrical connection between a device such as a semiconductor chip and the buildup wiring board is not limited to a solder material, and is not particularly limited as long as it is a conductive material. For example, it may be a connection using a conductive resin in which conductive particles are dispersed, or a connection of a gold bump using a conductive paint or solder. In the present specification, the bump includes a conductive ball such as a solder ball.
For the organic and inorganic materials that make up the wiring board such as solder resist and core material that cover the surface of the build-up wiring board, use materials that do not adversely affect the metal wiring, connection pads, etc. It is necessary to select it, and it is desirable to have heat resistance that can withstand the repair process of the semiconductor device. For example, in a generally used process of lead-free solder having a reflow temperature of 250 ° C., it is desirable to have no adverse effect on a wiring board, a semiconductor device, an electronic component, or the like.

  The base material of the sealing resin includes acrylic resin, melamine resin, epoxy resin, polyolefin resin, polyurethane resin, polycarbonate resin, polystyrene resin, polyether resin, polyamide resin, polyimide resin, fluororesin, polyester resin, phenol There are various materials such as a resin, a fluorene resin, a benzocyclobutene resin, and a silicone resin, but there is no particular limitation, and these can be used alone or in combination of two or more. Epoxy resins that are excellent in terms of viscosity, cost, heat resistance, and the like are generally used, but resins that are liquid at room temperature of 25 ° C. are desirable.

As an example of means for reducing the adhesion of the sealing resin at a heating temperature (hereinafter referred to as a repair temperature) for removing the semiconductor device, it is effective to add multilayer particles having a siloxane skeleton to the sealing resin. However, the multilayer particles will be described in more detail. The hardness of the core portion is designed to be lower than the hardness of the shell portion. For example, when two layers of particles are used, the preferred core has a hardness of less than 75 (spring type hardness tester JIS-A type JISK6301) and the shell has a hardness of 75 or more, more preferably the core It is desirable to set the hardness to 40 or less. When the hardness of the core part is designed to be small, the effect of reducing elasticity becomes large. This effect can reduce the resin adhesion at the repair temperature.
The multilayer particles having a siloxane skeleton added to the sealing resin have a structure in which the volume ratio of the core portion is higher than the volume ratio of the shell portion. Specifically, when the volume ratio of the core part is 1.5 times or more, more preferably 2 times or more larger than the volume ratio of the shell part, the effect of reducing the elasticity and suppressing the linear expansion appears more strongly.
The multilayer particle having a siloxane skeleton added to the sealing resin has a structure in which the glass transition temperature of the shell portion is higher than the glass transition temperature of the core portion. As one specific example, when the glass transition temperature of the core part is −80 ° C., the sealing resin base material is 110 ° C., and the glass transition temperature of the shell part is 260 ° C., the viscosity increases when the sealing resin is filled. In addition, the sealing resin could be cleaned without damaging the wiring board in a repair temperature range exceeding 180 ° C. The glass transition temperature of the core portion is less than 100 ° C. and the glass transition temperature of the shell portion is 125 ° C. or higher due to the influence on reliability when the operating temperature of the current LSI chip is assumed to be 105 ° C. and workability during repair. It is desirable. When the glass transition temperature point of the core part is higher than this, the repair property tends to be impaired, and the further glass transition temperature decrease of the shell part is lower than the upper temperature limit used for the thermal cycle test of the semiconductor device. It is. This design makes it possible to achieve both repairability and reliability.

The multilayer particles having a siloxane skeleton added to the sealing resin are preferably spherical, and the addition amount is preferably about 1 to 30 vol%. More preferably, addition of about 15 to 25 vol% is desirable. Addition of particles other than spheres has a strong tendency to increase viscosity, and addition of more than this often increases viscosity and deteriorates filling properties due to thixotropy, so filling for narrow gaps between semiconductor devices and wiring boards It will damage the sex.
The average particle diameter of the multilayer particles having a siloxane skeleton added to the sealing resin is preferably 1/10 or less of the gap between the semiconductor device and the wiring board to be filled, and the average particle diameter is 0.1. It is desirable to be in the range of about 30 μm. Further, the effect on the low linear expansion varies depending on parameters such as the particle size and hardness of the silicone particles. For example, the same kind of silicone raw material is used to form multilayer particles having a siloxane skeleton, particles having an average particle size of 0.5 μm, particles having an average particle size of 3 μm, particles having an average particle size of 5 μm. In the influence exerted on the linear expansion coefficient when the particles having the additive are added to the sealing resin, the effect of suppressing the increase in the linear expansion coefficient more strongly was observed with the particle diameter of 5 μm.

  Various materials such as silica, calcium carbonate, alumina, zirconium and titanium oxide are used for the inorganic filler added to the sealing resin, but silica with the most remarkable advantages such as cost, sphericity and low linear expansion is used. Often used. The average particle diameter of the silica to be added is preferably 1/10 or less of the gap between the semiconductor device and the wiring board to be filled, and the average particle diameter is preferably in the range of about 0.1 to 30 μm. Further, a coupling agent may be used on the surface of these inorganic additives in order to improve the wettability with the sealing resin and enhance the filling property. Coupling agents include silane, titanate, aluminate, zircoaluminate, chromate, borate, stunate, isocyanate, and other types of covalent bonds, and coordinate bonds such as β-diketone couplers. Various types can be used.

An example of a process for repairing a semiconductor device sealed with a resin whose adhesion strength at the repair temperature is reduced by the method described above will be described with reference to FIG. Assume that the semiconductor chip 1 mounted on the wiring substrate 10 shown in FIG. A substrate-side pad 6 is formed on the surface of the wiring substrate 10 by being partitioned by a solder resist 7. The chip-side pad 2 formed on the semiconductor chip 1 is electrically connected to the substrate-side pad 6 by solder bumps 8. The gap between the wiring substrate 10 and the semiconductor chip 1 is filled with a sealing resin 9. For removal, the semiconductor chip 1 is first heated to a repair temperature by a hot plate (not shown) or the like. As for the repair temperature, when metal bonding is performed like a solder bump, it is necessary to heat to a melting point temperature or higher at which the bump melts. For example, if it is eutectic solder, it will be 183 ° C or higher, and lead-free solder (Sn-3Ag-0.5Cu) will be 220 ° C or higher. Therefore, it is desirable to set it 20 ° C. or more higher than the melting point temperature, and the adhesion strength of the sealing resin at that time is 350 gf / mm ² (3.43 N / mm ² ) or less, more preferably 345 gf. / Mm ² (3.38 N / mm ² ) or less. In addition, the bump itself is not integrally formed by metal bonding or the like, and when the bump resin is simply in contact with the adhesive force of the sealing resin, the temperature at which the adhesion strength of the sealing resin is 350 gf / mm ² or less. Should be set. Further, when a conductive adhesive or the like is used as a bump, it is desirable to repair at a temperature at which the adhesion strength of the conductive resin bump and the adhesion strength of the sealing resin are both 350 gf / mm ² or less. When the adhesion strength of the sealing resin is 350 gf / mm ² or more and is sufficiently larger than 350 gf / mm ² , the substrate is damaged when the semiconductor chip is removed. If it is slightly larger than 350 gf / mm ² , the removal of the semiconductor chip is successful, but the sealing resin remains in the vicinity of the electrode part on the surface of the substrate to be regenerated. In addition, there is a high possibility that a connection failure occurs in the re-mounting process due to substrate damage or resin residue entering the electrode portion. Here, the peeling plate 12 shown in FIG. 3 required for removing the semiconductor chip from the wiring board is prepared. 3A is a plan view of the peeling plate 12, and FIG. 3B is a cross-sectional view taken along the line AA. The material of the peeling plate is preferably sufficiently stronger than the sealing resin at the repair temperature, and examples thereof include metals such as SUS, but are not limited thereto. The width W of the peeling plate 12 is approximately the same as the width of the semiconductor chip to be repaired. However, if there is no adjacent component, the width W is slightly larger than the semiconductor chip, and if there is an adjacent component, the semiconductor chip A slightly smaller width is desirable. The thickness t of the peeling plate needs to be thinner than the gap between the semiconductor chip and the wiring board because of being inserted into the gap between the semiconductor chip and the wiring board. It is desirable that the length L of the peeling plate is longer than the length of the semiconductor chip so that the peeling plate can be inserted to the end of the semiconductor chip. The shape of the corner portion 12a at the tip of the peeling plate 12 may be a right angle, but depending on the state of the substrate surface, etc., the substrate surface may be damaged at the plate corner portion during insertion of the peeling plate. It is desirable to process it.

Next, as shown in FIG. 2B, a peeling plate 12 is inserted along the surface of the wiring board into the side surface of the resin sealing the gap between the semiconductor chip 1 and the wiring board 10. . Immediately after the insertion, the sealing resin on the outer periphery of the side surface is destroyed. However, when the peeling plate is inserted little by little, the resin crack generated when the resin is destroyed is the interface peeling between the sealing resin 9 and the substrate. Then, the interface peeling is further advanced using the tip of the peeling plate 12, and finally the tip of the peeling plate reaches the side opposite to the insertion side, thereby wiring the semiconductor chip to be repaired. It can be removed from the substrate.
At this time, as shown in FIG. 2C, the resin residue 13 remains slightly on the periphery of the mounting area of the semiconductor chip on the wiring board, but there is no resin residue on the other part of the substrate surface and the resin chip 13 is sealed from the surface. Stop resin can be peeled cleanly. At this time, the residual solder 14 remains thin on the board-side pad 6.
Finally, as shown in FIG. 2D, the resin slightly remaining on the outer periphery of the mounting area of the semiconductor chip is removed by cleaning. As an example of the method, a solvent such as DMF (dimethylformamide) is used at room temperature. While being used, the resin remaining on the substrate can be completely removed by scraping with a cotton swab or the like. In this state, the semiconductor chip can be remounted. However, if the surface of the substrate including the pad on the substrate side is wiped off with DMF (dimethylformamide) alcohol or the like, fine dirt is removed and stable remounting is performed. It is effective.

  In addition, when inserting the peeling plate, it is necessary to destroy the sealing resin surface at the start of insertion and allow the plate tip to penetrate into the resin, so the plate tip should be sharp and made of metal. Although workability is good, after peeling of the interface between the resin and the substrate occurs, there is a possibility that the substrate may be damaged in some places with irregularities on the surface of the substrate. As shown in FIG. It is desirable that the end portion 12b of the plate 12 be rounded, and the material of the plate should be as soft as possible. Therefore, it is effective to use a plate with a sharp tip at the start of insertion, replace the peeling plate after destroying the resin surface, and use a material with a round tip and the same material as the substrate material. In addition, applying a heat-resistant resin such as polyimide coating or tape to the tip of the metal plate is also effective for protecting the substrate surface.

  Next, a method for repairing only defective semiconductor chips on a substrate on which a plurality of semiconductor chips are mounted will be described. Although only the semiconductor chip to be repaired may be removed while heating the whole, it is effective to locally heat only the semiconductor chip to be repaired when it is not desired to heat it more than necessary due to problems such as heat resistance of components. For example, as shown in FIG. 4, hot air 16 is sprayed from the air nozzle 15 only to the semiconductor chip 11 to be repaired to perform local heating. By this method, after the semiconductor chip to be repaired reaches a predetermined temperature, the semiconductor chip 11 to be repaired can be removed by the above-described method to reduce the thermal stress of other components.

Further, as shown in FIG. 5, local heating may be performed by bringing the heater block 17 into contact only with the semiconductor chip 11 to be repaired.
Note that the heating method shown in FIGS. 4 and 5 can be used not only when the chip is removed but also when the semiconductor chip is remounted, thereby reducing the thermal stress of other components.
In addition, applying local heating to a semiconductor chip to be repaired and cooling adjacent components is effective in reducing the thermal stress of other components. For example, as shown in FIG. 6, hot air 16 is radiated from the air nozzle 15 only to the semiconductor chip 11 to be repaired, and a metal cooling block 18 is brought into contact with the neighboring semiconductor chip 1. In this example, the cooling block is brought into contact with the cooling. However, as another example, a method in which a gel-like material is brought into contact or air at room temperature or lower is blown may be used.

When a plurality of semiconductor chips are arranged close to each other, a resin sealing each semiconductor chip may be connected. FIG. 7A shows a case where the sealing resin 9 of the semiconductor chip 11 to be repaired and the sealing resin 9 of the adjacent semiconductor chip 1 are connected. In this case, even if the substrate interface of the sealing resin of the semiconductor chip 11 on the defective side can be peeled cleanly, the sealing resin is connected so that the non-repairable semiconductor chip 1 side is damaged such as resin peeling. May be given. In order to avoid this, as shown in FIG. 7B, it is preferable to make a notch 19 between the connected sealing resins. By doing so, it is possible to divide the progress of the resin peeling at the time of removing the chip at the cut portion, and to prevent an adverse effect on the adjacent parts. As a means for making a cut in the resin at this time, a metal having a sharp tip after heating may be used, or an electric cutter or the like whose depth of cut can be adjusted at room temperature may be used. The depth of the cut is desirably half or more of the resin thickness, and more effective if it is just below the substrate surface.
The present invention will be described more specifically below, but the present invention is not limited to the following examples unless it exceeds the gist.

  First, investigations were made to reduce the adhesion of the epoxy resin at the repair temperature. A sealing resin composition in which different types of particles were added to the epoxy resin base material was made as a prototype. The composition A to which particles having a multilayer siloxane skeleton were added, the composition B to which polybutadiene particles were added, the composition C to which acrylic particles were added, and the composition D to which no organic particles were added were mixed in the ratio shown in the following table, The linear expansion coefficient and elastic modulus were measured. The results are shown in Table 1. In Table 1, α1 is a linear expansion coefficient at a temperature not higher than the glass transition temperature, and α2 is a linear expansion coefficient at a temperature not lower than the glass transition temperature (the same applies to Table 5). The composition A to which the particles having a multilayer siloxane skeleton of the present invention are added does not increase the linear expansion coefficient in spite of the addition of a large amount of organic filler, compared with the compositions B and C. Moreover, the elasticity modulus required at the time of repair was able to be made low compared with the composition D which added the same amount as the others only by adding an inorganic filler without adding an organic filler. That is, according to the method of the present invention, it was possible to achieve both a low linear expansion coefficient necessary for ensuring heat cycle resistance and a low elasticity necessary for repair. In addition, the data of the linear expansion coefficient shown in Table 1 are values obtained by averaging three or more repeated measurements.

  Silicone filler was added to the epoxy resin base material at the ratio shown in Table 2 below, and viscoelasticity measurement was performed. As a result, the addition of the silicone filler was able to reduce the elastic modulus of the sealing resin without causing a significant decrease in the glass transition temperature.

  A sealing resin composition in which different types of particles were added to the epoxy base material was made as a prototype. The composition A to which particles having a multilayer siloxane skeleton were added, the composition E to which silicone rubber particles having no multilayer structure were added, and the composition C to which acrylic particles were added were mixed at the following ratios, and their viscosity, thixotropy index, penetration The results of measuring the properties are shown in Table 3. As a result, by using particles having a multiple siloxane skeleton, the permeability could be improved with a low viscosity and a low thixotropy index.

  The adhesion strength at the repair temperature of the resin was measured. The evaluation method prepared the board | substrate material which coat | covered the solder resist PSR-4000CC02 made by Taiyo Ink Manufacturing Co., Ltd. on the surface of the glass epoxy material CS-3357s made by Risho Kogyo Co., Ltd. This substrate material was cut into 2 mm square, adhered to the same substrate material with an epoxy resin to be evaluated, and a sample in which the epoxy resin was sufficiently cured was used. The resin used in the evaluation is a composition F obtained by adding 25 vol% of particles having a multi-layered siloxane skeleton to a biphenyl epoxy resin, a composition G of a biphenyl epoxy resin without addition of organic particles, and a naphthalene epoxy resin without addition of organic particles The composition H. These test pieces were measured for adhesion strength of each resin by a shear test at 25 ° C. and a repair temperature of 240 ° C. adjusted to the solder melting temperature. The number of tests was 9 for each temperature, but for 240 ° C. of composition F, it was tripled to 27. The results are shown in Table 4.

（単位：Ｎ）

(Unit: N)

In the results, what is described above after the number is the one that did not peel even when the upper limit value of the measuring instrument was exceeded, and the accurate adhesion strength could not be measured.
As a result, when the composition H of the naphthalene epoxy resin and the composition G of the biphenyl epoxy resin were compared, it was confirmed that the adhesion strength of the composition H of the naphthalene epoxy resin was strong at 25 ° C. and 240 ° C. When comparing composition F, in which 25 vol% of particles having a multi-layer siloxane skeleton are added to a biphenyl-based epoxy resin, and composition G, which is a biphenyl-based epoxy resin to which no organic particles are added, the average value of the adhesion strength at the repair temperature is about 70%. It was confirmed that the addition of particles having a multilayer siloxane skeleton has the effect of reducing the adhesion at the repair temperature. In addition, the maximum value of the adhesion strength per unit area of the composition F at 240 ° C. was 353 gf / mm ² .

  Hereinafter, an example of repair actually using a semiconductor chip will be described. Table 5 shows details of a resin obtained by adding particles having a multilayer siloxane skeleton to the biphenyl epoxy resin used in the repair experiment.

The semiconductor chip used in the experiment has a size of 13 mm × 18 mm, a pitch of 0.8 mm, and 66 electrodes. The bump of the semiconductor chip was Sn-3Ag-0.5Cu lead-free solder. Next, a method for mounting a semiconductor chip on a build-up wiring board will be described. The solder bump tip of the semiconductor chip is pressed onto a glass plate on which the flux is uniformly and thinly applied and then peeled off with a predetermined load, and the flux is transferred to the solder bump tip of the semiconductor chip. The semiconductor chip can then be aligned on the build-up wiring board using a flip chip mounter, and after mounting, solder reflow can be performed in a reflow furnace with a peak temperature of 240 ° C to connect the build-up wiring board and the semiconductor chip. It was. The gap between the semiconductor chip and the build-up wiring board is about 250 μm.
The obtained build-up wiring board on which the semiconductor chip was mounted was swung in alcohol, and the flux residue remaining in the gap between the semiconductor chip and the build-up wiring board was cleaned. The obtained mounted product was baked in an oven at 125 ° C. for 2 hours to dry the alcohol used for flux cleaning.
Further, the dried package was heated on a hot plate, and after confirming that the surface temperature of the build-up wiring board was 100 ° C., the resin composition was supplied from the side surface of the semiconductor chip using a resin coating apparatus. At this time, the sealing resin composition flowed on the lower surface of the semiconductor chip by capillary action, and was able to be filled without generating voids in a gap of about 250 μm.

The mounting of the semiconductor chip was completed by curing the mounting of the resin filled with the resin in an air atmosphere at 150 ° C. for about 1 hour.
Using the semiconductor device thus obtained, an experiment was attempted to repair the semiconductor chip from the build-up wiring board.
The semiconductor chip mounting surface was placed on a hot plate, and the substrate surface was heated to 240 ° C., which is the melting temperature of the solder bumps. First, a repair experiment was performed by a method using the peeling plate of the present invention as a repair method.
The peeling plate used in the repair experiment has a width of 22 mm, a length of 130 mm, a thickness of 0.15 mm and a material of SUS420. While holding the build-up wiring board so as not to move, the tip of the peeling plate width 22 mm is applied to the sealing resin fillet on the side of the semiconductor chip 13 mm wide and pushed along the surface of the wiring board to destroy the side surface of the sealing resin Then, a peeling plate was inserted little by little. When the peeling plate is inserted, the resin crack that occurs when the resin is destroyed progresses to the interface peeling between the sealing resin and the substrate, and continues to insert the peeling plate as it is, further progressing the interface peeling. The semiconductor chip could be removed from the build-up wiring board by causing the tip of the peeling plate to reach the side opposite to the insertion side. When observing the build-up wiring board at this stage, it is confirmed that the resin residue on the board remains slightly in the resin fillet part around the semiconductor chip, and that the electrode pad part is cleanly separated from the board interface It was done. The resin residue that remained slightly could be removed from the substrate surface by cleaning such as rubbing with a cotton swab while using DMF (dimethylformamide) at room temperature. Although a new semiconductor chip was re-mounted on the regenerated build-up wiring board by the method described above, it could be mounted without any problem. From the above results, it was confirmed that repair was possible by the repair method of the present invention using a peeling plate.
In addition, the repair evaluation was conducted for five samples including a local heating method using hot air, and all the samples were able to remove the semiconductor chip from the substrate interface in the same manner.

Next, a removal experiment using tweezers was performed. After the mounted product was heated to 240 ° C. in the same manner as described above, the tip of the tweezers was hooked on the side surface of the semiconductor chip, and then the semiconductor chip was lifted and peeled off from the substrate. Then, 50% or more of the resin remained in the area ratio including many electrode areas on the build-up wiring board, and the resin could not be peeled off at the board interface.
In addition, using the biphenyl epoxy resin without addition of organic particles and the naphthalene epoxy resin without addition of organic particles used in the resin adhesion strength test described above, repair was performed under the same conditions as in the repair experiment using the peeling plate described above. Experiments were performed. First, in the case of naphthalene-based epoxy resin with strong adhesion strength, it was difficult to break the resin after pressing the release plate against the resin side, but when the release plate was inserted with a stronger force, the build-up board Substrate destruction occurred where most of the solder resist on the surface peeled off.

  Next, as a result of carrying out a repair experiment using a peeling plate with a biphenyl epoxy resin to which no organic particles were added, the semiconductor chip could be removed without destroying the substrate, but about 50% on the substrate. Resin residue was generated at an area ratio of, and further resin removal was attempted. As a result, substrate destruction occurred in which the solder resist on the build-up substrate surface was partially peeled off. Regarding this result, in the case of biphenyl-based epoxy resin to which no organic particles are added, when the adhesion strength and repairability of the resin at 240 ° C. are compared, there is a very delicate relationship, and from the measurement result of the resin adhesion strength described above. It can be considered that this result was obtained because there was some variation in the adhesion strength. That is, the resin peels off from the substrate interface at a location where the adhesion strength is low, but the resin remains on the substrate at a location where the adhesion strength is high, leading to solder resist peeling at the time of resin removal.

From the above results, the release plate is obtained under the condition that the resin in which the particles having a multilayer siloxane skeleton are added to the biphenyl-based epoxy resin is effective for repair and the adhesive strength of the resin is 350 gf / mm ² or less. It was confirmed that the sealing resin can be peeled off from the substrate interface by performing repair using.
Reliability evaluation was performed using a resin in which particles having a multilayer siloxane skeleton were added to a biphenyl epoxy resin. Ten sets (10p) of three types of packages each without sealing, with sealing (without repair), and with sealing (with repair) were produced. The obtained package was put into a temperature cycle test bath under a temperature condition of −25 ° C. to 125 ° C. (holding for 10 minutes in each bath, no intermediate holding), and the electrical resistance was monitored. While high resistance failure was detected in the total number of packages in the cycle, for the 20 samples with sealing, the semiconductor chip was repaired, and the heat cycle reliability exceeding 1500 cycles was confirmed for the remounted package I was able to.

  A cross section of the semiconductor device after the completion of the reliability test was observed, and the filling state of the sealing resin around the solder connection portion was observed. As a result, it was confirmed that the particles having a multilayer structure having two or more siloxane skeletons maintained a spherical shape even after the sealing resin was cured. It was confirmed that the particles having a multilayer structure having two or more siloxane skeletons did not melt at the curing temperature of the sealing resin and were not compatible with the epoxy resin serving as the base material of the sealing resin.

Sectional drawing of the semiconductor device which carried out the flip chip connection of the semiconductor chip on the buildup wiring board, and was filled with sealing resin. Sectional drawing of the process order which shows the repair method of this invention. The top view and fragmentary sectional view of the plate for peeling used for the repair method of this invention. The schematic diagram which shows a mode that a local heating is carried out with hot air, when a several semiconductor chip is mounted on a wiring board. The schematic diagram which shows a mode that it heats locally with a heater block, when a several semiconductor chip is mounted on a wiring board. The schematic diagram which shows a mode that an adjacent chip | tip is locally cooled by a cooling block, when a some semiconductor chip is mounted on a wiring board, heating locally by hot air. The schematic diagram explaining the repair when the resin which seals an adjacent semiconductor chip has connected in the case where a plurality of semiconductor chips are mounted on a wiring board.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Semiconductor chip 2 Chip side pad 3 Build-up wiring board 4 Insulation layer 5 Wiring 6 Board side pad 7 Solder resist 8 Solder bump 9 Sealing resin 10 Wiring board 11 Repair target semiconductor chip 12 Peeling plate 13 Resin residue 14 Residual solder 15 Air nozzle 16 Hot air 17 Heater block 18 Cooling block 19 Notch

Claims (16)

One or a plurality of semiconductor devices are mounted on a wiring board in such a manner that pads formed on each are connected via conductive bumps, and a gap between the semiconductor device and the wiring board is formed by a sealing resin. A method of repairing a filled semiconductor device, wherein at least a semiconductor device to be repaired is heated to reduce an adhesion strength of a sealing resin, and a plate thinner than a gap between the semiconductor device and the wiring board is formed on the semiconductor device A semiconductor device repairing method, wherein the semiconductor device is separated from the wiring board by being inserted into a gap between the wiring board and the wiring board. The method for repairing a semiconductor device according to claim 1, wherein particles having a multilayer structure having a siloxane skeleton are added to the sealing resin. The method of repairing a semiconductor device according to claim 1, wherein particles having a multilayer structure with a core portion having a hardness lower than that of the shell portion are added to the sealing resin. 4. The method of repairing a semiconductor device according to claim 2, wherein the core portion of the multi-layered particle is made of a linear polymer, and the shell portion is made of a three-dimensional polymer. 4. The method of repairing a semiconductor device according to claim 2, wherein the core portion of the particles having the multilayer structure is made of silicone rubber and the shell portion is made of silicone resin. The adhesion strength of the sealing resin when the plate is inserted into a gap between the semiconductor device and the wiring board is 3.43 N / mm ² (350 gf / mm ² ) or less. 6. The method for repairing a semiconductor device according to any one of 5 above. 7. The method of repairing a semiconductor device according to claim 1, wherein only the semiconductor device to be repaired is locally heated. 8. The method of repairing a semiconductor device according to claim 1, wherein only a semiconductor device to be repaired is locally heated and peripheral devices not to be repaired are selectively cooled. When the sealing resin of the semiconductor device to be repaired and the sealing resin of the semiconductor device adjacent to the semiconductor device to be repaired are connected, after cutting at least part of the connecting portion of the sealing resin, 9. The method of repairing a semiconductor device according to claim 1, wherein a semiconductor device to be repaired is selectively removed. 10. The method of repairing a semiconductor device according to claim 1, wherein the conductive bumps are separated from the pads on the wiring board side at the base of the wiring board by inserting the plate. 11. The method of repairing a semiconductor device according to claim 1, wherein the insertion of the plate into the sealing resin proceeds while peeling the sealing resin from the surface of the wiring board. When separating / removing the semiconductor device to be repaired, a plate (hereinafter referred to as the first plate) that first destroys the surface of the sealing resin and a plate (hereinafter referred to as the first plate) for separating the semiconductor device to be repaired from the wiring board. 12. The method for repairing a semiconductor device according to claim 1, wherein the two plates are different from each other. The method of claim 12, wherein the first plate is thinner than the second plate. 14. The method of repairing a semiconductor device according to claim 12, wherein a tip portion of the first plate is sharper than a tip portion of the second plate. 15. The method of repairing a semiconductor device according to claim 1, wherein a cross-sectional shape of a tip portion of the plate or the second plate has a round shape. 16. The method of repairing a semiconductor device according to claim 1, wherein the plate or the second plate is coated with a heat resistant resin.

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