JP4265679B2 - Manufacturing method of semiconductor device - Google Patents

Description

  The present invention is excellent in solder heat resistance, stage shift when semiconductor is resin-sealed, and highly reliable resin pellet for semiconductor sealing that does not cause wire flow, and semiconductor element using the semiconductor pellet for semiconductor sealing The present invention relates to a semiconductor device formed by sealing and a method for producing the resin pellet for semiconductor sealing.

  In recent years, it has become very important to mount semiconductor devices on a wiring board at high density in order to reduce the size of electronic devices. Therefore, instead of the “insertion mounting method” in which the lead pins of the semiconductor device are inserted into the holes in the substrate and soldered from the back side of the substrate as in the past, the “surface mounting method” in which the semiconductor device is temporarily fixed to the substrate surface and then heated overall. "Has become commonplace.

  Along with the shift to the surface mounting method, the soldering process, which has not been much of a problem in the insertion mounting method, has become a big problem. In the insertion mounting method, the lead portion is only partially heated in the soldering process. However, in the surface mounting method, the entire package is heated, so that the entire package has a high temperature of 210 to 270 ° C. Will be heated. Therefore, in the resin-sealed package, the moisture absorbed by the sealing material between molding and the mounting process explosively vaporizes and expands during soldering heating, and cracks occur during soldering, There was a problem that peeling occurred between the sealing material and the silicon chip or lead frame, resulting in a decrease in reliability. Conventionally, studies have been made to reduce the water absorption rate by using a high filler filler for this problem.

  Further, in the field of semiconductor integrated circuits, progress in microfabrication technology is remarkable, and high integration of IC chips is being promoted. In order to further improve the degree of integration, the occupation ratio of the IC chip in the package is increased, and the package is required to be large, thin, and have a large number of pins. However, in order to seal these large, thin, and multi-pin packages by increasing the filler, sealing resin characteristics with excellent moldability that do not cause stage shift, wire flow, and void generation are required.

On the other hand, a transfer molding method has been widely used to encapsulate semiconductor elements in the past. Usually, this transfer molding method involves placing a tableted resin in a mold pot and heating it to inject the resin under pressure. This is a method of molding. However, as IC package development progresses, the molding methods and molds have diversified, and tablets of various sizes have been used. Therefore, tablet size management suitable for the molding methods and molds is required. ing. In order to omit tablet size management, a method of resin-sealing a semiconductor element using powder before tableting has been proposed. Since pellets are molded by measuring the amount of resin required for each shot, there are significant cost advantages in terms of effective use of resin and inventory management compared to tablets.

JP-A-9-283550

An object of the present invention is excellent in solder heat resistance, the stage shifts in the semiconductor resin-sealing a semiconductor which seals the semiconductor element with excellent semiconductor sealing resin pellet of reliability is wire sweep does not occur It is to provide a method for manufacturing a device.

That is, the present invention
1. “A method for producing a semiconductor device by encapsulating a semiconductor element by a molding method selected from a low pressure transfer molding method, an injection molding method and a compression molding method using resin pellets for semiconductor encapsulation,
The pellet is formed by molding a molten resin composition containing 80% by weight or more of the inorganic filler, and the specific surface area of the pellet is 40 × 10 ⁻⁴ m ² / g to 150 × 10 ⁻⁴ m ^2. / g der is,
A method for manufacturing a semiconductor device, comprising a virtual circumscribed sphere having a diameter of 0.5 mm to 5.0 mm with respect to the pellet, the content of which is 90% or more . "
2. “A method for manufacturing a semiconductor device, wherein the molten resin composition contains an epoxy resin and a curing agent.”
3. “The method for manufacturing a semiconductor device according to any one of the above, wherein the epoxy resin contains a biphenyl type epoxy.”
4). “The method for manufacturing a semiconductor device according to any one of the above, wherein the number of pellets having a maximum length of 0.5 mm to 5.0 mm is 90% or more.”
5 . “A method for manufacturing a semiconductor device according to any one of the above, wherein a pellet obtained by forming a molten resin composition containing 80 wt% or more of an inorganic filler from a molten state and pelletizing the molten resin composition is used.” 6 . “Manufacture of any one of the above semiconductor devices, wherein the epoxy resin, the curing agent, and the inorganic filler are melt-kneaded to form a melt-kneaded resin composition, and then molded from a molten state and pelletized. Method."
Is to provide.

According to the present invention, it is possible to provide a highly reliable manufacturing method of a semiconductor device in which a stage shift and a wire flow do not occur and a void does not occur when a semiconductor is sealed with a resin.

  Hereinafter, the configuration of the present invention will be described in detail. In the present invention, “pellet” means an individual pellet or an assembly of a plurality of individual pellets.

  The resin pellet for semiconductor encapsulation of the present invention is preferably produced from a melt of a resin composition for semiconductor encapsulation containing an epoxy resin (A), a curing agent (B), and an inorganic filler (C). The semiconductor sealing resin composition will be described below.

  The epoxy resin (A) in the present invention has two or more epoxy groups in one molecule and is not particularly limited. Specific examples thereof include, for example, a cresol novolac type epoxy resin, a phenol novolac type epoxy resin, and a phenol aralkyl. Type epoxy resin, naphthol aralkyl type epoxy resin, dicyclopentadiene skeleton containing epoxy resin, biphenyl type epoxy resin, naphthalene type epoxy resin, bisphenol A type epoxy resin, bisphenol F type epoxy resin, linear aliphatic epoxy resin, alicyclic type Examples thereof include an epoxy resin, a heterocyclic epoxy resin, a spiro ring-containing epoxy resin, and a halogenated epoxy resin, and these may be used alone or in combination of two or more.

  Specific examples of particularly preferred epoxy resin (A) include 4,4′-bis (2,3-epoxypropoxy) biphenyl and 4,4′-bis (2,3-epoxypropoxy) -3,3 ′. 5,5′-tetramethylbiphenyl, 4,4′-bis (2,3-epoxypropoxy) -3,3′5,5′-tetraethylbiphenyl, 4,4′-bis (2,3-epoxypropoxy) Biphenyl type epoxy resins such as -3,3'5,5'-tetramethyl-2-chlorobiphenyl and the like, and it is preferable to contain these biphenyl type epoxy resins in all epoxy resins, particularly 60 to 100 wt. % Is preferable.

  The curing agent (B) in the present invention is optional as long as it is a compound that reacts with an epoxy resin, but a phenolic compound having a hydroxyl group in the molecule is preferably used as a compound having a low water absorption rate when cured. It is done. Specific examples of the phenol compound include phenol novolak resin, cresol novolak resin, naphtho novolak resin, tris (hydroxyphenyl) methane, 1,1,2-tris (hydroxyphenyl) ethane, 1,1,3. -Tris (hydroxyphenyl) propane, terpene and phenol condensation compound, dicyclopentadiene-modified phenol resin, phenol aralkyl resin, naphthol alcohol resin, catechol, resorcin, hydroquinone, pyrogallol, phloroglucino- And the like.

  In the present invention, the compounding equivalent ratio of the epoxy resin (A) and the curing agent (B) (molar ratio of hydroxyl group to epoxy group) is usually 0.5 to 2.0, preferably 0.7 to 1. 5. As a compounding quantity of an epoxy resin (A) and a hardening | curing agent (B), the range whose sum of an epoxy resin (A) and a hardening | curing agent (B) is 5 to 20 weight% with respect to the whole composition is preferable, and a more preferable compounding quantity The range of 5 to 15% by weight.

  As the inorganic filler (C) in the present invention, amorphous silica, crystalline silica, calcium carbonate, magnesium carbonate, alumina, magnesia, silicon nitride, magnesium aluminum oxide, zirconia, zircon, clay, talc, calcium silicate, oxidation Examples include titanium, antimony oxide, asbestos, glass fiber, calcium sulfate, and aluminum nitride, and any shape such as spherical, crushed, and fibrous can be used. Preferable specific examples of the inorganic filler (C) are amorphous silica, crystalline silica, and alumina. More preferably, the spherical filler has a spherical shape of 60 to 100% by weight, particularly 80 to 80% by weight. It is preferable to contain 100 weight%.

  In the present invention, the proportion of the inorganic filler (C) is required to be 80% by weight or more of the entire resin composition, but more preferably 86% by weight or more. Since the inorganic filler has a higher thermal conductivity than the resin component, when the inorganic filler is contained in an amount of 80% by weight or more, when the pellet is heated in the pot at the time of molding, the whole pellet is rapidly and uniformly melted to cause uneven flow of the resin. In addition, the water absorption rate is reduced and the solder resistance is improved.

  In the present invention, the inorganic filler (C) is preferably blended with a coupling agent such as a silane coupling agent in terms of reliability when sealing a semiconductor device. The coupling agent may be blended as it is or may be surface-treated in advance on the inorganic filler (C).

  As a coupling agent, a silane coupling agent in which an organic group having a functional group such as epoxy silane, amino silane, mercapto silane, or ureido silane is bonded to a silicon atom, and a hydrolyzable group such as an alkoxy group is directly bonded to the silicon atom. Are preferably used, and two or more of them may be used in combination. In particular, it is preferable to add a coupling agent having an amino group, and specific examples thereof include γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, N-phenyl-γ-aminopropyltrimethoxysilane, Examples thereof include N-phenyl-γ-aminopropylmethyldimethoxysilane, N-β (aminoethyl) γ-aminopropyltrimethoxysilane, N-β (aminoethyl) γ-aminopropylmethyldimethoxysilane.

  Moreover, the addition amount of a coupling agent is 0.1 to 2 weight% normally with respect to the whole epoxy resin composition.

  In the present invention, a curing accelerator can be further blended. The curing accelerator to be used is arbitrary as long as it accelerates the reaction between the epoxy resin and the curing agent. Specific examples of the curing accelerator include triphenylphosphine, tributylphosphine, and tri (p-methylphenyl) phosphine. Phosphines such as 2-methylimidazole, 2-phenylimidazole, 2-phenyl-4-methylimidazole, imidazoles such as 2-heptadecylimidazole, triethylamine, benzyldimethylamine, α-methylbenzylamine, 1,8-diazabicyclo (5,4,0) undecene-7, 1,5-diazabicyclo (4,3,0) nonene-5, 7-methyl-1,5,7-triaza And amines such as bicyclo (4,4,0) decene-5.

  In the present invention, a bromine compound can be blended. Further, the bromo compound substantially present is usually added as a flame retardant to the epoxy resin composition for semiconductor encapsulation, and is not particularly limited, and may be a known one.

  Preferred examples of the existing bromo compound include brominated epoxy resins such as brominated bisphenol A type epoxy resin and brominated phenol novolak type epoxy resin, brominated polycarbonate resin, brominated polystyrene resin, brominated polyphenylene oxide resin, tetra Bromobisphenol A, decabromodiphenyl ether and the like can be mentioned. Among them, brominated epoxy resins such as brominated bisphenol A type epoxy resins and brominated phenol novolac type epoxy resins are preferable from the viewpoint of moldability.

  In the present invention, an antimony compound can be blended. This is usually added as a flame retardant aid to the epoxy resin composition for semiconductor encapsulation, and is not particularly limited, and known ones can be used. Preferable specific examples of the antimony compound include antimony trioxide, antimony tetraoxide, and antimony pentoxide.

  In the present invention, silicone rubber, olefin copolymer, modified nitrile rubber, modified polybutadiene rubber, elastomer such as modified silicone oil, long chain fatty acid, metal salt of long chain fatty acid, ester of long chain fatty acid, long chain fatty acid A mold release agent such as amide or paraffin wax can be blended. Of these, modified silicone oils are preferred, and preferred specific examples thereof include epoxy-modified silicone oils, carboxyl-modified silicone oils, amino-modified silicone oils, polyether-modified silicone oils, and the like. Epoxy-modified silicone oils and carboxyl-modified silicone oils are particularly preferred. It can be preferably used.

  In the present invention, as other additives, coloring agents such as carbon black and iron oxide, ion scavengers such as hydrotalcites and bismuth, thermoplastic resins such as polyethylene and polypropylene, and crosslinking agents such as organic peroxides. It can be added arbitrarily.

  In the present invention, the resin pellet for semiconductor encapsulation is usually used as an aggregate composed of a plurality of pellets. When resin-sealing a semiconductor, generally 10 or more in one pot in one molding cycle. Use to form.

In the present invention, the “specific surface area” means the specific surface area of the pellet itself in the case of individual pellets, and the average of the specific surface area of 100 pellets randomly collected from the aggregate in the case of aggregates. Mean value. Semiconductor sealing resin pellets of the present invention has a specific surface area of 4.5 × ¹⁰ -4 ^m 2 / g or ^{more, 4.5 × 10 -4 ~200 × 10} -4 m 2 / g is preferred arbitrariness. When the specific surface area is large, the thermal conductivity is good, and when the pellet is heated in the pot, the entire pellet melts uniformly and quickly, so there is no uneven flow of the resin, and there are problems such as stage shift and wire flow. I don't get up. However, when the specific surface area is 200 × 10 ⁻⁴ m ² / g or more, it becomes fine powder, which is not preferable in terms of handling and working environment.

  The size of the pellet is not limited, but when a virtual circumscribed sphere is assumed for the pellet, it is preferable that 90% or more in number is included in the range where the diameter is 10.0 mm or less, and the diameter is 0.00. It is particularly preferable that 5 mm to 8.0 mm is 90% or more, and 0.5 mm to 5.0 mm is 90% or more.

  In the present invention, the “longest part length” means the length of the longest part when the size of the pellet is measured. For example, in the case of a cylindrical shape, it corresponds to a diagonal line of a cross section including the centers of two bottom circles, and in the case of a cube or a rectangular parallelepiped, it corresponds to the diagonal line. The resin-encapsulating assembly for semiconductor encapsulation of the present invention preferably includes 90% or more in terms of the number having a longest length of 10.0 mm or less, and 0.5 mm to 8.0 mm is 90% or more. More preferably, 0.5 mm to 5.0 mm is particularly preferably 90% or more.

  The shape of the pellet is not particularly limited, but a cylindrical shape, a spherical shape, a bowl shape, and a plate shape are preferable, and it is preferable that the shapes are as uniform as possible.

  The following method is mentioned as a manufacturing method of the resin pellet for semiconductor sealing of this invention. First, preferably a composition containing an epoxy resin (A), a curing agent (B), and an inorganic filler (C) is mixed, and then preferably at a temperature of 60 to 140 ° C., more preferably 60 to 120 ° C. Melt kneading at a temperature of The melt-kneading apparatus is manufactured using a known kneader such as a Banbury mixer, kneader, roll, single-screw or twin-screw extruder. The melt kneader is preferably provided with a vent device so as not to leave voids in the melt discharge. Moreover, it is preferable to use a kneading screw, a dalmage screw, etc. for screw arrangement, in order to knead | mix a resin, an inorganic filler, etc. uniformly.

  Next, the molten resin composition in the molten state is pelletized. The molten resin composition is extruded into a rod shape or a sheet shape, cut with various cutters to be pelletized, the molten resin composition is poured into a mold and pelletized. It can be obtained by a known method such as

  As a method for manufacturing a semiconductor device by sealing a semiconductor element using the resin pellet for semiconductor sealing of the present invention, a low-pressure transfer molding method is generally used, but an injection molding method or a compression molding method is also possible. As a molding condition, for example, a semiconductor device is obtained by molding a resin pellet for semiconductor encapsulation at a molding temperature of 150 to 200 ° C., a pressure of 5 to 15 MPa, a molding time of 30 to 300 seconds, and obtaining a cured product of the sealing resin composition. Is manufactured. Moreover, the said molded object is further heat-processed for 2 to 15 hours at 100-200 degreeC as needed.

  Hereinafter, the present invention will be described specifically by way of examples. The numbers in Tables 2 and 3 indicate% by weight.

Examples 1-8 , Comparative Examples 1-4
The components shown in Table 1 were blended in a powder state with a mixer at the composition ratios shown in Tables 2 and 3. This was melt-kneaded using a twin-screw extruder with a barrel temperature of 90 ° C., and extruded in the molten state into a cylindrical bar shape from the discharge port. This was cut with a cutter to obtain approximately cylindrical pellets having the sizes shown in Tables 2 and 3. Using this pellet, a semiconductor device was molded by sealing under a condition of 175 ° C. × 2 minutes by a low pressure transfer molding method.

  Stage shift: Eight 36-pin TSOP devices (outer dimensions: 10 x 23 x 1.0 mm, dummy chip: 6 x 16 x 0.3 mm, frame material: 42 alloy, chip surface: polyimide film), and ultrasonic The cross section was observed with a flaw detector, and the package was cut and the cut surface was observed with a microscope. The case where the stage shift and the chip displacement were all less than 50 μm was marked as “◎”, the case where the shift was 50 μm or more and less than 100 μm was marked as “◯”, and the case where the stage shift or chip displacement occurred was marked as “X”.

  Solder resistance: 8 each of 36-pin TSOP devices (outer dimensions: 10 × 23 × 1.0 mm, dummy chip: 6 × 16 × 0.3 mm, frame material: 42 alloy, chip surface: polyimide film) were formed. The semiconductor device was obtained by additional heating at 4 ° C. for 4 hours. These were humidified for 168 hours under the conditions of 85 ° C. and 85% RH, and then passed through an IR (infrared) reflow furnace heated to 245 ° C. under the conditions of 245 ° C. and 10 seconds. Thereafter, the number of external cracks was checked, and the cracked package was defined as a defective package, and the number of defects was determined.

  The diameter and the longest length of the virtual circumscribed sphere of the pellet were determined by the following method. Take a micrograph of 100 randomly collected pellets, consider the pellet as a cylinder, measure the outer diameter and length from this photograph, find its distribution, and calculate the diameter and longest length of the virtual circumscribed sphere . Next, ten of the virtual circumscribed spheres with the largest diameter and longest length were excluded, and the value of the largest of the remaining 90 was described.

  The specific surface area was calculated from the weight distribution of 100 randomly collected pellets, the outer diameter and length distribution determined by the above method, and the average value thereof.

As can be seen in Tables 2 and 3, when the semiconductor sealing pellets having specific surface areas of Examples 1 to 8 of 40 × 10 ^{−4 to} 150 × 10 ⁻⁴ m ² / g are used, there is no stage shift and solder resistance. A semiconductor device excellent in the above can be obtained. On the other hand, in Comparative Example 1, the inorganic filler is less than 80% by weight, and in Comparative Examples 2 to 4, the specific surface area is less than 4.5 × 10 ⁻⁴ m ² / g. Wake up and solder resistance is getting worse.

Claims (6)

A method of manufacturing a semiconductor device by sealing a semiconductor element by a molding method selected from a low-pressure transfer molding method, an injection molding method and a compression molding method using a resin pellet for semiconductor encapsulation,
The pellet is formed by molding a molten resin composition containing 80% by weight or more of the inorganic filler, and the specific surface area of the pellet is 40 × 10 ⁻⁴ m ² / g to 150 × 10 ⁻⁴ m ^2. / g der is,
A method for manufacturing a semiconductor device, comprising a virtual circumscribed sphere having a diameter of 0.5 mm to 5.0 mm with respect to the pellet, the content of which is 90% or more .   The method for manufacturing a semiconductor device according to claim 1, wherein the molten resin composition contains an epoxy resin and a curing agent.   3. The method of manufacturing a semiconductor device according to claim 2, wherein the epoxy resin contains a biphenyl type epoxy.   4. The method of manufacturing a semiconductor device according to claim 1, wherein 90% or more of pellets having a longest part length of 0.5 mm to 5.0 mm are contained. 5. The method for manufacturing a semiconductor device according to any one of claims 1 to 4 , wherein a pellet obtained by forming a molten resin composition containing 80% by weight or more of an inorganic filler from a molten state and pelletizing the molten resin composition is used. The semiconductor according to any one of claims 1 to 4 , wherein an epoxy resin, a curing agent and an inorganic filler are melt-kneaded to form a molten resin composition, and then a pellet formed from a molten state and pelletized is used. Device manufacturing method.