JP2937398B2 - Manufacturing method of encapsulated semiconductor device - Google Patents

Description

The present invention relates to a method for manufacturing a sealed semiconductor device, and more particularly, to sealing a large element, sealing an ultra-thin package, and the like. The present invention relates to improvement of semiconductor element sealing such as sealing of a surface mount package.

(Prior art) Conventional semiconductor devices can be roughly classified into a package sealed with metal, ceramic, glass, or the like, and a plastic package sealed with epoxy resin or the like by a transfer molding device. .

Hollow packages that use metal, ceramic, glass, etc. for sealing are highly airtight and highly reliable, but have the disadvantages of poor productivity, high cost, and high hardness and poor toughness. There is. For the bonding at the time of sealing, a low melting point glass method or a metallization / metal solder method is used.
In addition, low temperature (100-200 ° C) as an alternative bonding method
Although a method using an organic adhesive which can be adhered with is performed, but the reliability is poor, the organic material used is limited,
There were problems such as poor heat resistance and poor productivity.

For these reasons, plastic packages are currently mainly used for sealing semiconductor devices. In addition, as the resin sealing, a method of sealing by a potting method using a liquid resin is also in practical use.

By the way, in recent years, in the field of resin encapsulation of a semiconductor device, miniaturization of various functional units on the element and enlargement of the element itself have been rapidly progressing along with high integration of the semiconductor element. In addition, a surface array package represented by a gate array called an ASIC (Application Specific IC) or a standard cell LSI is rapidly developing.
In mounting these surface mount packages, processes such as vapor phase reflow, infrared reflow, and solder immersion are employed. In these steps, the package is exposed to high temperatures (215-260 ° C). For this reason, in a resin-sealed semiconductor device sealed with an epoxy resin, a small amount of moisture that has penetrated the resin and penetrated into the inside thereof is rapidly vaporized, and cracks are formed in the sealing resin layer. When the crack reaches the outside, there is a serious problem that the moisture resistance reliability cannot be guaranteed. In addition, a phenomenon occurs in which the resin cannot be mounted due to swelling of the resin. Furthermore, cracks occur in PSG (phosphosilicate glass) and SiN (silicon nitride) used as passivation films for wiring layers such as aluminum, the passivation polyimide film peels off, and Au bonding wires break. Problems frequently occur.

As a countermeasure against these, (1) reduce the stress of the sealing resin on the internal enclosure, and use the sealing resin and the PSG, S
Encapsulation resins for large packages are required to increase the adhesion to iN, polyimide film and lead frame, (2) to provide high-temperature strength and high-moisture-absorption high-temperature strength corresponding to the mounting temperature and to reduce the amount of moisture absorption. Is increasing around the world.

From these viewpoints, as the sealing resin, for example, maleimide resin-based, PPS (polyphenylene sulfide)
Practical use of resin-based resins, PPO (polyhydroxyphenylene ether) -based resins, and liquid crystal polymers is being studied. Further, recently, a resin obtained by combining a maleimide resin and an epoxy resin, or an aminobismaleimide resin obtained by combining a bismaleimide resin and 4,4-diaminodiphenylmethane has been proposed as a sealing resin.

On the other hand, a resin-sealed semiconductor device (for example, Japanese Patent Application Laid-Open No. Sho 60-208847) has been proposed in which a problem in mounting is improved by a package structure. In this semiconductor device, a column or a polygonal hole is provided in a molding resin (sealing resin) portion below a die pad to form an extremely thin portion or a portion having no molding resin. The structure is such that gas generated by evaporation of moisture escapes from the extremely thin portion described above. Further, a method of forming a metallic coating layer on a package surface from a transfer molding method has been proposed. However, none of the resin-encapsulated semiconductor devices has been sufficiently satisfactory in terms of productivity and moisture resistance reliability.

Furthermore, in order to reduce the above-mentioned problems at the time of mounting and to prevent displacement or disconnection of the aluminum wiring due to the influence of the sealing resin, a hollow plastic package or the like has been proposed. It was not enough from the point of view.

(Problems to be Solved by the Invention) The present invention has been made in order to solve the above problems, and has excellent airtightness and moisture resistance reliability, and can be manufactured in a shorter time than a conventional transfer molding method. It is an object of the present invention to provide a method of manufacturing a sealed semiconductor device that can be mounted without various problems.

[Structure of the Invention] (Means for Solving the Problems) In order to solve the above problems, the present invention provides a method in which a package material in which both surfaces of a metal layer are covered with a resin layer is arranged so as to surround a semiconductor element. A method for manufacturing a sealed type semiconductor device, characterized in that a peripheral portion of the package material is selectively press-bonded so that an end of the metal layer is covered with the resin layer.

The resin that covers both surfaces of the metal layer constituting the package material used in the present invention is not particularly limited, and a thermoplastic resin or a B-staged thermosetting resin is used. However, those having excellent heat resistance, moisture resistance, insulation properties and adhesiveness are preferable, and among them, those having high purity and low ionic impurities as much as possible and containing no low molecular weight components are particularly preferable from the viewpoint of reliability. Examples of the thermoplastic resin include polysulfone, polyether sulfone, polyphenylene sulfide (PPS) resin, polyhydroxyphenylene ether (PPO) resin, and further, polyethylene terephthalate resin, polybutylene terephthalate resin, and the like. Engineering plastic resins such as liquid crystal polymer, polyetheretherketone (PEEK) resin, polyketone sulfide (PKS) resin, and fluororesin (PAF).

Examples of the B-staged thermosetting resin include epoxy resins, phenolic resins, maleimide resins, silicone resins, urethane resins, diallyl phthalate resins, and unsaturated polyester resins.

The thickness of each resin layer can be appropriately selected in consideration of securing adhesion by heating and pressing and insulating properties with respect to the metal layer. It is sufficient that the thickness of each resin layer is 5 μm or more.

Examples of the metal forming the metal layer include iron, nickel, copper, gold, silver, aluminum, tin, stainless steel,
Lead and alloys thereof are exemplified. Among these, those which can be processed to be thin, lightweight, and excellent in moisture resistance are preferable. The thickness of the metal layer may be any thickness that can block moisture and does not deform the package shape at a high temperature (for example, 215 ° C. to 260 ° C.). Typically, the metal layer has a thickness of 5 μm or more.

To prepare a package material by coating both sides of the metal layer with the resin layer, a method of dissolving the resin in a solvent and applying the resin to the metal layer, a method of applying the resin to the metal layer without solvent, a method of powder coating A method of forming a resin layer on a metal layer by a method,
Alternatively, a method in which a film-formed or compression-molded resin is heat-sealed to a metal layer, or an injection-integrated molding method can be appropriately adopted according to the thickness of the resin layer.

By the way, in the present invention, the above-mentioned package material is arranged so as to surround the semiconductor element, and is heated and pressed. To this end, as will be described more specifically with reference to the drawings, the package material may be previously processed into a box shape having a flange at an open edge. Such processing is
It can be performed by a metal working method such as integral punching or blow molding using a superplastic metal. This metal working can be performed before or after the formation of the resin layer.
Such a box-shaped package material may have a recess of a size and shape such that when placed, it does not contact the semiconductor element and the bonding wires.

The thermocompression bonding is performed such that the coating resin layer is softened or melted at the end portion (flange portion of the box-shaped package material) by heating so as to perform compression bonding. As a heating method, there are a plate heating method, an infrared heating method, and the like, and it is preferable to apply heat and pressure so that pressure is applied only to the peripheral portion of the package material. It is performed so as not to contact the frame. In order to further prevent the contact of the metal layer with the lead frame, a component such as an insulating inorganic filler serving as a spacer such as a spherical filler may be added to the resin coating the metal layer. . Further, the heat compression bonding is preferably performed in an inert gas atmosphere or under vacuum in order to further enhance the humidity resistance reliability.

The resin-encapsulated semiconductor device according to the present invention includes a form in which a semiconductor element is sealed from one side with the box-shaped package material, and a similar metal layer in which the box-shaped package material is coated on both sides with a similar resin. The semiconductor device is used in combination with a plate-shaped package material, and the semiconductor element is sealed from both sides. These modes are selected according to the mounting state of the semiconductor element. Note that a resin or the like which does not adversely affect the semiconductor element and the bonding wire may be sealed in the hollow portion inside the sealed semiconductor device of the present invention.

Hereinafter, the present invention will be described more specifically with reference to the drawings. Throughout the drawings, the same portions are denoted by the same reference numerals.

FIG. 1 shows a cross section of an example of a sealed semiconductor device according to the present invention. As shown in the figure, a semiconductor element 19 mounted on a die pad 20 of a lead frame and having an upper surface electrode bonded to a lead 22 by a wire 21 is a box type having resin layers 12 and 13 formed on both sides of a metal layer 13. And a flat package material 18 in which a similar metal layer 15 is covered with similar resin layers 16 and 17.

The upper box-shaped package material 14 has a flange portion 14a at an open edge thereof, and the flange portion 14a is adhesively bonded to the lead 22 by a resin of a resin layer. In addition, the lower plate-shaped package material 18 is adhesively bonded to the leads 22 at its ends by the resin of the resin layer. Note that the element 19 and the bonding wire 21 are hollow inside without contacting the box-shaped package material 14.

A method of manufacturing such a sealed semiconductor device will be described with reference to FIG. 2. The box-shaped package material 14 shown in FIG. 2A is replaced with the semiconductor element 19 shown in FIG. 2B. It is arranged so as to surround it. The semiconductor element 19, the die pad 20, and the lead 22 are placed on a flat package material 18 shown in FIG. 2 (c). In this state, the peripheral portions of both package materials 14 and 18 are heat-pressed by the method described above. Thus, the sealed semiconductor device shown in FIG. 1 is obtained.

FIG. 3 shows a TAB (Tape Automated Bonding) type semiconductor element 19 bonded to a film carrier 32 with a bump 31 by using an upper plate-shaped package material 18 and a lower box-shaped package material 14 at the film carrier 32 site. An example of sealing is shown.

Such an encapsulated semiconductor device is composed of a box-shaped package material 14 shown in FIG. 4A and a flat package material 18 shown in FIG. 4C, and a semiconductor element 19 shown in FIG. Is sandwiched between the film carriers 32, and the peripheral portions of both package materials 14 and 18 can be manufactured by thermocompression bonding according to the method described above.

FIG. 5 shows that the electrodes on the upper surface are mounted on
52 shows an example in which the semiconductor element 19 bonded by the wire 21 is sealed. In this encapsulated semiconductor device, the flat package material is not used, and the box package material 14 is
Sealing is performed so as to surround the semiconductor element 19, the wire 21, and the electrode 52.

This sealed type semiconductor device is made of a semiconductor device 19 shown in FIG. 6 (b) by using a box type package material shown in FIG. 6 (a).
Is sealed so as to surround the bonding wire 21 and the electrode 52. In this case, the box-shaped package material 14 is heated and pressed on the surface of the substrate 51 at the flange portion 14a.

(Operation) According to the present invention, since the semiconductor element is sealed by heating and compression so as to surround the semiconductor element with a package material in which a resin layer is coated on both surfaces of a metal layer, moisture can enter the package. Can be suppressed by the metal layer. As a result, it is possible to obtain a sealed semiconductor device having excellent moisture resistance reliability without causing cracks in the sealing resin layer due to rapid vaporization of a small amount of residual moisture upon heating during mounting. The metal layer
Since both surfaces are covered with the resin layer, malfunction can be prevented even if the internal bonding wires or the like may come into contact with the package material or even if the pins or the like come in contact with the outside. Furthermore, since the sealed semiconductor device of the present invention can be manufactured by heat compression bonding using the above-described package material, it can be molded in a shorter time than the transfer molding method and can be easily manufactured.

(Examples) Hereinafter, examples of the present invention will be described together with comparative examples.

In each of the following examples and comparative examples, as a semiconductor element to be sealed, a die pad size of 15.5 mm square, a plate thickness of 150 μm, and a 184-pin 4,2 alloy lead frame having a thickness of 150 μm were bonded to a bonding wire having a diameter of 25 μm. (A chip size of 15 mm square, passivation: surface polyimide film) bonded by the method described above. Unless otherwise specified, in the following examples and comparative examples, the shape of the obtained package was 32 mm × 32 mm × 3.6 mm.

Example 1 On both sides of a 400 μm thick aluminum plate,
A 00 μm PSK (polyketone sulfide resin) film (manufactured by Kureha Chemical Co., Ltd.) was applied by heat fusion, and processed into a box-shaped package material shown in FIG. 2 (a). Further, a flat package material shown in FIG. 2 (c) was produced using the same aluminum plate and resin film. Using these package materials, the semiconductor element was sealed as described with reference to FIG. Heat and pressure conditions are 5k pressure
The compression bonding was performed at a temperature of 280 ° C. for 20 seconds at g / cm ² .

Example 2 On both sides of an aluminum plate, a phenol-curable epoxy resin (catalyst: triphenylphosphine) containing a silicone rubber-based low stress imparting agent was B-staged by roll kneading and adjusted to a thickness of 100 μm with a solvent. A sealed semiconductor device was manufactured in the same manner as in Example 1 except that a box-shaped and a plate-shaped package material were produced by coating.

Example 3 An encapsulated semiconductor device was manufactured in the same manner as in Example 2 except that an epoxy resin-modified maleimide resin (phenyl ether-based amine cross-linking) was used as a coating resin.

Example 4 An encapsulated semiconductor device was manufactured in the same manner as in Example 2 except that a copper plate having a thickness of 100 μm was used instead of the aluminum plate.

Example 5 An encapsulated semiconductor device was manufactured in the same manner as in Example 4 except that the package thickness was changed from 3.6 mm to 2.0 mm.

Example 6 An encapsulated semiconductor device was manufactured in the same manner as in Example 4 except that the package thickness was changed from 3.6 mm to 1.0 mm.

Example 7 PPS was applied to both sides of a 400 μm thick aluminum plate.
(Polyphenylene sulfide resin, manufactured by Philips)
Is coated to a thickness of 100 μm, respectively, and this is
Into a box-shaped package material shown in Fig. Further, a flat package material shown in FIG. 2 (c) was prepared using the same aluminum plate and resin. Using these package materials, the semiconductor element was sealed as described with reference to FIG. Heat and pressure conditions are pressure 5 kg / cm ² , temperature 400
Crimping was performed at 20 ° C. for 20 seconds.

Comparative Example 1 A sealed semiconductor device was manufactured in the same manner as in Example 1 except that only an PSK molded product was used without using an aluminum plate. The heating and compression conditions were as follows: a pressure of 5 kg / cm ² and a temperature of 280 ° C.
The crimping was performed for 60 seconds.

Comparative Example 2 A semiconductor element was resin-sealed by transfer molding at 180 ° C. for 3 minutes using a mixture of the phenol-curable epoxy resin used in Example 2 and 75% of a filler. After-curing was performed at 180 ° C. for 4 hours.

Comparative Example 3 A box-shaped package material having the shape shown in FIG. 2A was made of Kovar alloy, and a flat package material having the shape shown in FIG. 2C was made of alumina ceramic. Was sealed. In addition, as an adhesive,
Using low-melting glass, epoxy resin adhesive,
Thermocompression bonding was performed at a pressure of 5 kg / cm ² and a temperature of 180 ° C. for 20 seconds.

Examples 1 to 7 and Comparative Examples 1 to 3 manufactured as described above
Temperature of 85 ° C and relative humidity of 85%
At 200 ° C for 200 hours to measure the water absorption.
2 minutes of VPS processing (vapor phase reflow processing)
After turning around, the appearance was observed immediately after the VPS treatment. In addition, temperature 1
A moisture resistance reliability test was performed in a pressure cooker at 28 ° C. and 2.5 atm to check for the occurrence of defective products. The results are shown in Table 1 below. Examples 1 to 7 and Comparative Examples 1 to 3
Table 1 shows the time required for encapsulation at the time of manufacturing the encapsulated semiconductor device.
It is described together.

As is clear from Table 1, the sealed semiconductor devices of Examples 1 to 7 have a metal layer, so that the penetration of moisture is suppressed, and the water absorption is smaller than that of the sealed semiconductor devices of Comparative Examples 1 and 2. . In addition, it can be seen that the encapsulated semiconductor devices of Examples 1 to 7 are superior in appearance after VPS treatment and superior in moisture resistance reliability as compared with the encapsulated semiconductor devices of Comparative Examples 1 to 3. Furthermore, the sealing type semiconductor devices of Examples 1 to 7 also require time for sealing,
Shorter than transfer molding and other methods.

[Effects of the Invention] As described in detail above, according to the method for manufacturing a sealed semiconductor device of the present invention, the problem of cracking of the resin during heating during mounting by suppressing the intrusion of moisture into the package is reduced. It does not occur, has excellent airtightness and excellent moisture resistance reliability after mounting, and is shorter and easier to manufacture than resin sealing by the transfer molding method used conventionally. Thus, it is possible to provide a sealed semiconductor device which can sufficiently cope with the trend toward the development of semiconductor devices.

[Brief description of the drawings]

FIG. 1 is a sectional view of a sealed semiconductor device of the present invention, FIG. 2 is a sectional view for explaining a method of manufacturing the sealed semiconductor device shown in FIG. 1, and FIG. FIG. 4 is a cross-sectional view of another encapsulated semiconductor device of the present invention, FIG. 4 is a cross-sectional view for explaining a method of manufacturing the encapsulated semiconductor device shown in FIG. 3, and FIG. FIG. 6 is a sectional view for explaining a method of manufacturing the sealed semiconductor device shown in FIG. 5, 11, 15,..., Metal layers, 12, 13, 16 , 17 …… Resin layer, 14 …… Box type package material, 18 …… Plate type package material, 19 ……
Semiconductor element, 20 ... die pad, 21 ... wire, 22 ...
... Lead, 31 ... Bump, 32 ... Film carrier, 51
…… Substrate, 52 …… Electrode

Continued on the front page (72) Inventor Michiya Higashi 1 Kosuka Toshiba-cho, Saiwai-ku, Kawasaki-shi, Kanagawa Prefecture Toshiba Research Institute, Inc. (72) Inventor Hiroshi Shimozawa 1 Kosuka Toshiba-cho, Sachi-ku, Kawasaki-shi, Kanagawa Stock (56) References JP-A-59-172253 (JP, A) JP-A-59-191358 (JP, A) Jikai 58-72847 (JP, U) (58) Fields investigated ( Int.Cl. ⁶ , DB name) H01L 23 / 02,23 / 06,23 / 08

Claims (1)

(57) [Claims] After arranging a package material in which both surfaces of a metal layer are covered with a resin layer so as to surround a semiconductor element, an edge of the metal layer is covered with the resin layer around a periphery of the package material. A method of manufacturing a sealed semiconductor device, wherein pressure bonding is selectively performed as described above.