JP3050345B2 - Connection method for integrated circuit elements - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for connecting an integrated circuit element for connecting a fine electrode pad such as an LSI and an electrode terminal provided on a mounting substrate.

[0002]

2. Description of the Related Art Conventionally, for this type of connection, an anisotropic conductive material for electrical connection containing conductive particles on its surface has been applied,
A method of thermocompression bonding at 80 to 200 ° C. and about ²⁰ to 30 kg / cm ² is employed.

That is, as shown in FIG. 4A, an LSI chip 1 having metal bumps 51 formed on electrode pads 2 and a substrate 3 having electrode terminals 4 formed corresponding to the electrode pads 2. Are opposed to each other via a thermal adhesive resin 10 containing an anisotropic conductive material for electrical connection including conductive particles 11. Next, as shown in FIG.
This is performed by pressing the chip 1 against the substrate 3 and heating it to soften the thermal adhesive resin 10 and connect the electrode pads 2 and the electrode terminals 4 with the conductive particles 11. In some cases, this connection is made via the conductive particles 11 only between the electrode pad 2 and the electrode terminal 4 without using the metal bump 51.

[0004]

In the above-described conventional connection mounting method, when the number of conductive particles 11 electrically connecting the electrode pad 2 and the electrode terminal 4 increases, the adjacent electrode pad or electrode becomes larger. Short circuit or current leak occurs between terminals. In order to avoid this, the conductive particles 11
If the number of is reduced, there is a problem that the connection resistance increases and varies. In severe cases, there were connection points that became electrically open. In addition, this trend is becoming more and more remarkable with recent increase in connection dimension. Also, it is extremely difficult for the LSI chip to be pressed strictly parallel to the substrate,
There is a problem that the gap between the electrode terminals varies, and the number of conductive particles between the electrode terminals varies, resulting in unstable connection. These phenomena are serious drawbacks that cause device malfunction.

It is an object of the present invention to provide a reproducible, stable,
In addition, it is an object of the present invention to provide a method for connecting integrated circuit elements capable of high definition.

[0006]

Means for Solving the Problems As a result of intensive studies to achieve the above object, it has been found that the above problems can be solved by using an active energy ray-curable resin, and the present invention is completed. Reached.

That is, the present invention relates to a method of connecting an integrated circuit element, wherein an electrode pad formed on the integrated circuit element and an electrode terminal formed on a substrate corresponding to the electrode pad are connected via a metal bump. An element connection method, wherein 1) a step of forming a metal bump on at least one surface of an electrode pad or an electrode terminal, 2) at least one of an integrated circuit element side or a substrate side surface is coated with an active energy ray-curable resin. 3) patterning the active energy ray-curable resin by lithography to selectively remove the active energy ray-curable resin on the electrode pads or electrode terminals; 4) facing the electrode pads and the electrode terminals ,
After the electrode pads or electrode terminals facing the metal bumps are brought into contact, the active energy ray-curable resin is brought into close contact with the integrated circuit element or substrate by thermocompression bonding, and the electrode pads and the electrode terminals are connected to the metal bumps. And 5) a step of performing a heat treatment and / or an irradiation treatment with active energy rays.

Next, the present invention will be described in more detail. FIG.
As shown in the figure, a metal bump layer of indium or the like is laminated by a vapor deposition method or the like on a substrate provided with electrode elements in advance or an integrated circuit element provided with electrode pads, and a photoresist is formed on the obtained metal bump layer. After application and drying, after exposure through a mask pattern, unnecessary resist portions are removed, and metal bumps are formed on the electrode pads or electrode terminals by plasma etching, immersion in an etchant, or the like.

After the metal bumps are provided at desired positions, an active energy ray curable resin is provided on at least one of the integrated circuit element and the substrate side surface, and is patterned by lithography to form active energy rays on the electrode pads or electrode terminals. The curable resin is selectively removed.

Here, the metal bumps used in the method of the present invention include solder, gold, aluminum, indium, and I.
Although a conductor such as TO can be used, indium which can be fused at a relatively low temperature is particularly preferably used.

As the active energy ray-curable resin used in the method of the present invention, a resin composition containing an active energy ray-reactive resin and an active energy ray polymerization initiator can be used.

The active energy ray-reactive resin may be any resin as long as it is cured by irradiation with active energy rays such as ultraviolet rays, electron beams, and X-rays, and the cured product shows adhesiveness by heat treatment. Phenol novolak type epoxy resin which shows curability by irradiation with active energy rays,
Cresol novolak type epoxy resin, glycidylamine type epoxy resin, biphenyl type epoxy resin and their bromides acrylic acid, methacrylic acid, crotonic acid,
Maleic acid, monomethyl maleate, monopropyl maleate, monobutyl maleate, those obtained by reacting an unsaturated base acid such as sorbic acid with the epoxy group of the above resin and esterified are preferably used, and acrylic acid is particularly preferable. This unsaturated basic acid has an acid equivalent / epoxy equivalent ratio of 0.1.
The reaction is preferably performed in the range of 5 to 1.5.

In order to make the active energy ray-reactive resin thus obtained alkali developable, the above-mentioned resin is further added to phthalic acid, phthalic anhydride, maleic acid, maleic anhydride, oxalic acid, adipic acid, citric acid, and the like. It is preferable to react a polybasic acid such as an acid. In this case, the obtained resin preferably has an acid value of 50 to 150.

The above resin component is cured by irradiation with active energy rays such as ultraviolet rays, and the cured product must exhibit adhesiveness by heat treatment. In this case, the heat treatment temperature is 50 to 120 ° C., preferably 60 to 120 ° C. ~ 90 ° C. If the temperature is lower than 50 ° C., good adhesiveness cannot be provided, while if it exceeds 120 ° C., a pattern having a good shape cannot be obtained, which is not preferable.

The active energy ray polymerization initiator generates radicals upon irradiation with active energy rays, and promotes the polymerization of the active energy ray reactive resin by the physical properties of the initiator itself such as a hydrogen abstraction reaction and a radical cleavage reaction. be able to. Representative substances of the hydrogen abstraction type are benzophenones. Examples of radical cleavage types include benzyldimethyl ketals. Further, a thioxanthone compound is also used. Specifically, benzophenone, 4,4′-dimethylaminobenzophenone,
4'-diethylaminobenzophenone, 2-ethylanthraquinone, tert-butylanthraquinone, benzoin ethyl ether, benzoin isopropyl ether, 2,2-dimethoxy-2-phenylacetophenone, 2,2-diethoxyacetophenone, 2-chlorothioxanthone, diethylthioxanthone , 2-hydroxy-2-methylpropiophenone, 4-isopropyl-
There are 2-hydroxy-2-methylpropiophenone and the like, and it is preferable to mix one or more of these at a ratio of 2 to 10% by weight based on the active energy ray-reactive resin.

The active energy ray-curable resin is usually practically used in the form of a coating solution dissolved in an organic solvent. Examples of such a solvent include ethylene glycol monoethyl ether, ethylene glycol monoethyl ether acetate, and the like. Ethylene glycol monobutyl ether,
One or a mixture of two or more of ethylene glycol monobutyl ether acetate, propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, methyl ethyl ketone, methyl isobutyl ketone, 1,1,1-trichloroethane and trichloroethylene can be used.

The active energy ray-curable resin used in the connection method of the present invention can be used in the above-mentioned composition. However, at the time of thermocompression bonding, a softener and an adhesive for imparting flexibility to the resin to prevent the occurrence of cracks and the like are used. An adhesion enhancer for controlling the temperature at which the property is imparted can be added.

As such a softening agent, various monomers and oligomers such as an acrylate type, a methacrylate type urethane type and a styrene type are used.

As the adhesion improver, a phenol novolak type epoxy resin, a cresol novolak type epoxy resin, and a bisphenol A type epoxy resin are preferably used. This adhesiveness improver is 5 to 40% by weight, preferably 10 to 20% by weight, based on the solid content of the active energy ray-curable resin.
% By weight.

The temperature at which the adhesive property appears can be freely controlled by arbitrarily changing the mixing ratio of the adhesive improver within the above range, but the temperature at which the adhesive property appears is preferably 50 to 120 ° C. . At 120 ° C. or higher, the adhesion improver is cured by opening the epoxy ring, and can increase the strength of the active energy ray-curable resin.

In addition, when a substrate transparent to visible light, such as glass, is used, carbon black, titanium black,
One or more of inorganic pigments such as iron black, lead white, titanium dioxide, titanium yellow, and ultramarine blue, and one or more organic pigments such as azo, phthalocyanine, isoinhydrin, and dioxane can be added with a light-shielding material. The light-shielding material can be added at a ratio of 5 to 40% by weight, preferably 10 to 30% by weight based on all components, and the light transmittance at a wavelength of 400 to 700 nm of the resin film after bonding and curing is improved. It is appropriately selected and added so as to be less than 5%.

Further, a dye, a pigment, a polymerization inhibitor, a defoaming agent, etc., which are commonly used, can be added to the active energy ray-curable resin, if necessary.

The solution obtained by dissolving the above-described active energy ray-curable resin in a solvent is applied by a roll coater, curtain flow coater, screen printing, spray coater, spin coater or the like as shown in FIG. dry. After drying, as shown in FIG. 2 (b), an active energy ray such as an ultraviolet ray is selectively irradiated using a mask in which the electrode portion is shielded from light or a substrate transparent to the active energy ray such as a glass substrate is irradiated. When used, the active energy ray curable resin is left only between the electrodes by irradiating the active energy ray from the back surface of the substrate and removing the unirradiated portion using a developing solution as shown in FIG. 2C. .
The amount of the active energy ray irradiated at the time of exposure is 0.05 to 0.15 J / cm ² when no light-shielding agent is contained.
About 0.3 to 2.5 J / cm if contained
Irradiation at an intensity of ² . If the irradiation intensity is less than this, it is not possible to give sufficient curability to the irradiated part,
If the amount is too large, the energy ray-curable component in the resin is completely cured, and it is difficult to obtain adhesiveness, which hinders the subsequent steps.

The patterned active energy ray-curable resin is subjected to heat treatment to impart adhesiveness, and as shown in FIG. 2D, the electrode pads and the electrode terminals are overlapped via metal bumps. Temperature 50-12
The active energy ray-curable resin is bonded to a substrate or element by thermocompression bonding at 0 ° C. and a pressure of 1 to 20 kg / cm ² , and the electrode pad and the electrode terminal are connected via a metal bump. I do. In order to more reliably connect the electrode pad or the electrode terminal to the metal bump, the temperature may be further raised to 120 to 180 ° C. and thermocompression bonding may be continued for several minutes.

Thereafter, the whole is heated at a temperature in the range of 120 ° C. to 200 ° C., or 1 to 5 J as shown in FIG.
Irradiation treatment with active energy rays such as ultraviolet rays in the range of / cm ² is performed to completely cure and bond the resin. As a result, strong adhesion is obtained between the electrode terminals and the electrode pads via the metal bumps and between the substrate and the active energy ray-curable resin. In this case, a connection that does not cause a short circuit or the like is performed.

When the resin is cured, sufficient curability can be obtained with active energy rays or heat alone, but the curing time can be shortened by using the resin in combination. If the heat curing temperature is 120 ° C. or lower, curing does not start. If the heat curing temperature is 200 ° C. or higher, heat sagging occurs in the resin, making it impossible to obtain a preferable pattern shape and adversely affecting the substrate and the electrodes.

Thus, an object of the present invention is to provide a method of connecting an LSI chip which has good reproducibility, is stable, has high connection reliability, and is capable of high definition.

[0028]

The electrode pad and the electrode terminal are connected via a metal bump, and the integrated circuit element and the substrate are bonded using an active energy ray-curable resin.
The variation of the connection resistance can be reduced. further,
When the substrate is transparent to visible light, by setting the light transmittance of the active energy ray-curable resin at a wavelength of 400 nm to 700 nm to less than 5%, even if the LSI itself is not shaded, It is possible to prevent malfunction due to light.

[0029]

Embodiment 1 Hereinafter, the present invention will be described with reference to the drawings. 1 and 2 are sectional views showing a method of connecting an LSI chip as an embodiment of the present invention in the order of steps. FIG. 1 shows a stage before the process, and FIG. 2 shows a stage after the process. First, referring to FIG. 1A, an integrated circuit device 1 (hereinafter, referred to as an LSI chip)
On the surface of the substrate, for example, a three-layered Au / Cr / Al metal film (each having a thickness of 1.0 μm, 0.05 μm, 0.
5 μm) or a three-layer metal film of Au / TiN / Al (thicknesses of the respective layers are 0.8 μm, 0.08 μm, and 0.1 μm).
2 μm), and an electrode terminal 4 is formed on the substrate 3 corresponding to the electrode pad 2. In the present invention, the metal bumps 5 are integrally formed on the electrode pads 2. As a component of the metal bump, In (indium) metal is used, but if it is necessary to control the melting temperature, an alloy of indium and lead may be used.

Next, as shown in FIG. 2A, a phenol novolak type epoxy acrylate resin to which tetrahydrophthalic anhydride has been added 9.0 g on a substrate 3 A cresol novolak type epoxy acrylate resin to which tetrahydrophthalic anhydride has been added 14 3.0 g Cresol novolak type epoxy resin 12.9 g Urethane oligomer 6.5 g 2-Methyl-[-4 (methylthio) phenyl] -2-morpholino-1-propane 6.4 g Diethylthioxanthone 3.2 g Propylene glycol monomethyl ether acetate 34. An active energy ray-curable resin solution prepared by mixing and dissolving 0 g of the mixture is uniformly applied with a spinner or the like, and then dried.

Next, as shown in FIG. 2B, ultraviolet rays 8 as active energy rays are irradiated through a photomask.

Next, as shown in FIG. 2C, development is carried out with a developing solution 9 comprising a 5% aqueous solution of triethanolamine, and the resin layer on the electrode terminals 4 is removed to form a mask pattern.

Next, as shown in FIG. 2D, the metal bumps 5 and the electrode terminals 4 face each other, and the LSI chip 1 is placed on the substrate 3 preheated to 80 ° C. 4 and a load of 5 kg / cm ² is applied to bond the active energy ray-curable resin and the substrate, and the LSI chip 1 and the electrode terminals 4 are connected to the metal bumps 5.
Was crimped through. 5k to further strengthen the connection
Heat at 150 ° C. for 2 minutes while applying a load of g / cm ² . Thus, the metal bump 5 was melted, and the metal bump 5 and the electrode terminal 4 were fixed.

Then, as shown in FIG. 2E, the entire surface is irradiated with ultraviolet rays at 3 J / cm ² to cure the active energy ray-curable resin, and the LSI chip 1 and the substrate 3 are bonded and fixed, and the metal bumps are formed. The bonding portion was fixed to complete the illustrated device. There was no poor connection or short circuit between the LSI chip and the substrate, and a good device was obtained.

Example 2 In Example 1, the resin having photo-thermosetting properties was
It was applied to the SI chip 1 side, and connection was made in the following process order, but a good device was obtained as in Example 1.

Example 3 In Example 1, the heat treatment was performed in an oven at 150 ° C. for 15 minutes in place of the UV irradiation for curing the active energy ray-curable resin. An element was obtained in the same manner as in Example 1. The electrodes of this element were also connected well without any poor connection or short circuit.

Example 4 In the above-mentioned Example 1, the entire surface irradiation treatment with ultraviolet rays performed to cure the active energy ray-curable resin was performed.
The entire surface was irradiated with 1 J / cm ² on a hot plate at ℃ ° C., but a good device was obtained as in Example 1.

Example 5 When a glass substrate was used in Example 1 above, the following light-shielding agent component CF black (pigment / manufactured by Okuni Pigment Co., Ltd.) was added to the active energy ray-curable resin component.
The connection to which 14.0 g was added was made in accordance with the process sequence of Example 1, but no defective connection or short circuit between the LSI chip and the substrate was found. In addition, while the obtained device was incorporated in an electronic device and used, light from a white fluorescent lamp was continuously applied to the entire surface of the device, but no malfunction occurred due to the photoelectric effect or the like.

[0039]

As described above, according to the method of connecting an LSI chip of the present invention, since the conductive particles are not dispersed in the adhesive resin as in the conventional method, high-definition connection is ensured. An extremely remarkable effect that it can be easily and reliably implemented is obtained. Also, since the metal bumps are provided directly on the electrode pads of the LSI chip or the electrode terminals of the substrate,
At the same time that the connection is made securely, the variation of the connection resistance can be reduced. Furthermore, when the substrate is transparent to visible light, using a light-shielding material for the active energy ray-curable resin can prevent a malfunction due to light of the LSI without shielding the LSI itself. is there.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a first step of an LSI connection method according to the present invention.

FIG. 2 is a cross-sectional view showing a subsequent step of an LSI connection method according to the present invention.

FIG. 3 is a cross-sectional view of a device obtained by the method of the present invention.

FIG. 4 is a cross-sectional view showing a conventional LSI chip connection method in the order of steps.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... LSI chip, 2 ... electrode pad, 3 ... substrate, 4 ... electrode terminal, 5 ... low melting point metal bump, 6 ... active energy ray curable resin, 7 ... photomask, 8 ... ultraviolet light, 9 ... developer, 10 ... thermal bonding resin, 11 ... conductive particles, 51 ... metal bumps.

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Kazuaki Utsumi 5-7-1 Shiba, Minato-ku, Tokyo NEC Corporation (72) Inventor Eiichi Ogawa 150 Nakamaruko, Nakahara-ku, Kawasaki City, Kanagawa Prefecture Tokyo Ohka Kogyo (72) Inventor Hiroshi Komano 150 Nakamurako Nakahara-ku, Kawasaki City, Kanagawa Prefecture Inside Tokyo Ohka Kogyo Co., Ltd. (72) Inventor Toshimi Aoyama 150 Nakamaruko Nakahara-ku, Kawasaki City, Kanagawa Prefecture Tokyo Ohka Kogyo Co., Ltd. Referee Masato Ikeda Referee Masafumi Tominaga Referee Masami Sakai (56) Reference JP-A-3-225934 (JP, A)

Claims (4)

(57) [Claims] 1. A method of connecting an integrated circuit element, wherein an electrode pad formed on the integrated circuit element and an electrode terminal formed on a substrate corresponding to the electrode pad are connected via a metal bump, A step of forming a metal bump on at least one surface of the electrode pad or the electrode terminal; 2) a step of coating at least one of the integrated circuit element side or the substrate side surface with an active energy ray-curable resin; 3) an active energy ray-curable A step of selectively removing the active energy ray-curable resin on the electrode pads or electrode terminals by patterning the resin by lithography, 4) facing the electrode pads and the electrode terminals, and facing the metal bumps or the electrode pads or electrodes After contacting the terminals, by thermocompression bonding, the active energy ray-curable resin and the integrated circuit element or substrate are brought into close contact with each other, and A method of connecting an electrode terminal via a metal bump; and 5) performing a heat treatment and / or an irradiation treatment with an active energy ray. 2. The method according to claim 1, wherein the metal bump is indium. 3. When the substrate according to claim 1 is transparent to visible light, the selectively removed active energy ray-curable resin has a light transmittance at a wavelength of 400 nm to 700 nm of less than 5%. 3. The method for connecting integrated circuit elements according to claim 1, wherein: 4. An active energy ray-curable resin and an integrated circuit element or substrate are bonded at a temperature in the range of 50 to 120 ° C. when thermocompression bonding is performed after the electrode pads and the electrode terminals are brought into contact with each other facing each other. 3. The method for connecting an integrated circuit element according to claim 1, wherein the metal bump and the electrode pad or the electrode terminal facing the metal bump are connected at a temperature of 120 to 180 [deg.] C. after the step.