JPH07326691A - Semiconductor element and integrated circuit device - Google Patents

Abstract

PURPOSE:To improve the wettability of a sealing resin to a protective film so as to improve the adhesion between the sealing resin and protective film by forming the protective film of a fluororesin having a fluoroaliphatic ring structure and, after forming a thin film of a polyimide resin on the surface of the protective film, sealing the protective film with the sealing resin. CONSTITUTION:After forming a protective film (passivation film, buffer coat film, or passivation film which also plays the role of a buffer coat film) composed of a fluororesin having a fluoroaliphatic ring structure and a thin film of a polyimide resin on the surface of the protective film, the protective film is sealed with a sealing resin (for example, an epoxy resin, silicone resin, etc.). The thickness of the protective film is adjusted to 0.5-10mum, preferably, to 1-5mum and the thickness of the thin film of the polyimide resin is adjusted to about 0.5-20mum, preferably, to 1-10mum. In addition, the surface of the protective film is treated in advance with laser light, corona discharge, or plasma. Therefore, the adhesion between the sealing resin and protective film can be increased, because the wettability of the sealing resin to the protective film is improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resin-encapsulated semiconductor element / integrated circuit device having a protective film formed of a thin film of a fluororesin having a fluorine-containing alicyclic structure.

[0002]

2. Description of the Related Art Generally, it is difficult to form a uniform thin film by coating a fluororesin because it is insoluble in a solvent. However, JP-A-63-238111 and JP-A-63-2.
As disclosed in Japanese Patent No. 60932 and U.S. Pat. No. 4,754,009, a fluororesin that can be dissolved in a special solvent has been developed, and its electrical characteristics and low water absorption are utilized to apply it to semiconductor protective films and other applications. No. 393682.

However, since the above-mentioned fluororesin has a high fluorine content and an extremely low surface energy, when a thin film is formed on a semiconductor element as a protective film such as a passivation film, a buffer coat film, or a passivation / buffer coat combined film, In the subsequent encapsulation process, there was a problem that the adhesion to the encapsulation resin was poor and the reliability was poor. In particular, when left under high temperature and high humidity for a long period of time, there is a problem that water is accumulated between the sealing resin and the fluororesin, which causes cracks in the sealing resin and deteriorates the performance of the element.

The passivation film here is a film for preventing moisture and impurities from entering the aluminum wiring of the semiconductor element, and the buffer coat film is for relieving mechanical stress due to the sealing resin at the time of assembly. Of the film.

Further, when a sealing resin that is liquid at room temperature and has a low viscosity is used, the sealing resin is repelled during the curing process because the surface energy of the fluororesin is low as described above. It was difficult to seal uniformly.

[0006]

DISCLOSURE OF THE INVENTION The present invention solves the above-mentioned drawbacks found in a semiconductor using a fluororesin as a protective film between a sealing resin and a semiconductor element, and
An object is to provide a semiconductor element / integrated circuit device having excellent reliability.

[0007]

Means for Solving the Problems The inventors of the present invention have made extensive studies based on the recognition of the above problems, and as a result, formed a polyimide resin thin film on the surface of a protective film made of a fluororesin to form a polyimide resin. It is newly found that a sealing resin layer can be uniformly formed on the upper surface and excellent adhesion between the fluororesin and the polyimide resin and between the polyimide resin and the sealing resin can be achieved, and a highly reliable semiconductor element / integrated circuit device can be manufactured. I arrived.

Thus, the present invention has been completed based on the above findings, and a protective film and a sealing resin which are thin films of a fluororesin having a fluorine-containing alicyclic structure used for semiconductor elements and integrated circuit devices. A semiconductor element / integrated circuit device characterized by having a polyimide resin thin film between them.

The polymer having a fluorinated alicyclic structure is obtained by polymerizing a monomer having a fluorinated cyclic structure, or a fluorinated monomer having at least two polymerizable double bonds is cyclopolymerized. The polymer having a ring structure in the obtained main chain is exemplified in a wide range including known or well known polymers.

Polymers having a ring structure in the main chain obtained by cyclopolymerization of a fluorine-containing monomer having at least two polymerizable double bonds are disclosed in JP-A-63-238111 and JP-A-63-238115. It is known from the gazette and the like. That is, it can be obtained by homopolymerization of a monomer such as perfluoro (allyl vinyl ether) or perfluoro (butenyl vinyl ether), or by copolymerization with a radical polymerizable monomer such as tetrafluoroethylene.

Polymers having a ring structure in the main chain obtained by polymerizing a monomer having a fluorinated ring structure are disclosed in Japanese Examined Patent Publication No.
It is known from the gazette of 3-18964, etc. That is, it is obtained by homopolymerizing a monomer having a fluorine-containing ring structure such as perfluoro (2,2-dimethyl-1,3-dioxole) or by copolymerizing this monomer with a radical polymerizable monomer such as tetrafluoroethylene. To be

Perfluoro (2,2-dimethyl-1,3
A polymer obtained by copolymerizing a monomer having a fluorine-containing ring structure such as -dioxole) with a fluorine-containing monomer having at least two polymerizable double bonds such as perfluoro (allyl vinyl ether) or perfluoro (butenyl vinyl ether) .

As the polymer having a fluorinated alicyclic structure, those having 20 mol% or more of the fluorinated alicyclic structure in the repeating unit of the polymer are preferable from the viewpoint of transparency and mechanical properties.

As a method for forming a protective film (hereinafter simply referred to as a protective film) consisting of a thin film of a fluororesin having a fluorine-containing alicyclic structure on a semiconductor device / integrated circuit device, a fluororesin solution is applied onto the device. After that, a method of volatilizing the solvent by heating and drying is preferably adopted. Examples of the coating method at this time include a spin coating method, a dipping method, and a potting method.

From the viewpoint of the reliability of the device, in this case, aluminum, aluminum alloy, titanium,
Wiring metal surface such as gold or platinum, semiconductor surface such as silicon or gallium arsenide, or silicon oxide film,
Since sufficient adhesion to the surface of an insulating film such as a silicon nitride film or alumina is required, it is desirable to treat the underlayer with a coupling agent or use a fluororesin solution mixed with a coupling agent.

The coupling agent is not particularly limited as long as it can provide the adhesiveness to the surface of the underlayer, and a silane coupling agent, a titanate coupling agent, an aluminum chelate coupling agent, hexamethyldisilazane ( HMDS) is preferably exemplified.

As a method of forming a polyimide resin thin film on the protective film, a method of applying a solution of a polyimide resin on the protective film or a method of applying a solution of polyamic acid, which is a precursor of the polyimide resin, on the protective film The preferred method is

Examples of the coating method at this time include a spin coating method, a dipping method, a potting method and the like. From the viewpoint of the reliability of the element, in this case, since adhesion between the fluororesin thin film and the polyimide resin thin film is required, the fluororesin thin film is treated with a coupling agent or a coupling agent is added to the polyimide solution. It is desirable to use a mixture. The coupling agent is not particularly limited as long as it can provide the adhesiveness to the surface of the fluororesin thin film, and the above-mentioned coupling agent is preferably used.

Further, in order to improve the adhesion between the protective film and the polyimide resin thin film, the protective film is treated by using electromagnetic waves such as laser light irradiation and microwave irradiation, electron beam irradiation treatment, glow discharge treatment, corona discharge. It is effective to perform processing such as processing and plasma processing.

Among these, laser beam irradiation treatment, corona discharge treatment, and plasma treatment are examples of suitable treatment methods that can be applied to the mass production process of semiconductor elements / integrated circuit devices. Furthermore, the plasma treatment is desirable because it causes less damage to the semiconductor element / integrated circuit device. As a device that performs plasma processing, you can introduce a desired gas into the device,
There is no particular limitation as long as an electric field can be applied, and a commercially available barrel type or parallel plate type plasma generator can be appropriately adopted.

The gas introduced into the plasma apparatus is not particularly limited as long as it effectively activates the surface of the protective film, and examples thereof include argon, helium, nitrogen, oxygen, and a mixture of these gases. Furthermore, it effectively activates the surface of the fluorine-containing resin having a fluorine-containing alicyclic structure, and at this time, as a gas with almost no film reduction,
Nitrogen and a mixed gas of nitrogen-oxygen are preferably exemplified.

For the purpose of further improving the adhesion between the polyimide resin thin film and the sealing resin and the wettability of the sealing resin, even after the adhesion improving agent is applied to the polyimide resin thin film, the sealing with the sealing resin is performed. Good. The adhesion improver is not particularly limited as long as it improves the uniform coating property of the sealing resin on the polyimide resin thin film and improves the adhesion, and the above-mentioned coupling agent is preferably adopted. .

When coating on a polyimide resin thin film,
These adhesion improvers may be applied as they are, or may be appropriately diluted with water or an organic solvent such as alcohol, toluene or xylene. The coating method is not limited as long as it does not impair the properties of the adhesion improver, and spin coating and dipping are preferred.

The thickness of the protective film is about 0.5 to 10 μm,
The film thickness of the polyimide resin thin film is preferably 0.5 to 20 μm, and more preferably 1 to 10 μm.

The encapsulating resin used in the present invention is not particularly limited and may be appropriately selected from known ones such as epoxy resin, silicone resin and polyimide resin depending on the characteristics of the semiconductor element / integrated circuit device and the encapsulation form. Epoxy resin is preferably used in terms of reliability and price.

The epoxy sealing resin is roughly classified into a liquid type and a solid type at room temperature. The former is mainly TAB (Tape Automated Bonding) and flip chip mounting, which are bare chip mounting (COB; chip
It is used for on-board), and is usually heat-cured after potting on a device with a dispenser.

The latter are mainly pin insertion types such as DIP (dual inline package), PGA (pin grid array), SOP (small outline package), FPP (flat plastic package).
It is used for surface-mounting type semiconductor packages such as packages) and is usually sealed by transfer molding.

As the epoxy encapsulating resin used in the present invention, a desired encapsulating form may be selected depending on the characteristics and uses of the semiconductor element / integrated circuit device, and either a liquid form or a solid form may be used. Further, as widely known, the epoxy encapsulating resin generally contains a curing agent, an inorganic filler, and an additive such as a silane coupling agent in addition to the epoxy resin, and reliability, An optimal composition may be selected from the viewpoint of price and the like. Further, a surfactant may be added in order to further improve the spreadability on the surface-treated protective film.

Examples of the semiconductor element / integrated circuit device according to the present invention include the following semiconductor elements and integrated circuit devices. That is, as the semiconductor element, a compound semiconductor typified by HEMT (hemt), an individual semiconductor such as a diode, a transistor, a thermistor, a varistor, or a thyristor, a light emitting diode, a photoelectric conversion element such as a charge-coupled element, or the like can be given.

As the integrated circuit device, MMIC is used.
(Compound semiconductor represented by (monolithic microwave integrated circuit), DRAM (Dynamic Random Access Memory), SRAM (Static Random Access Memory), EPROM (Erasable Programmable Read Only Memory), Mask ROM (Mask Read Only Memory), EEPROM (Electrical Erasable Programmable Read Only Memory), Hybrid Integrated Circuit (Hybrid IC), Flash memory or other storage device or microprocessor, ASIC
Such as theoretical circuit element.

In the present invention, since the polyimide resin thin film is applied on the surface of the protective film and then sealed with the sealing resin, the spreadability and adhesion of the sealing resin are improved and the sealing resin layer is formed. It is considered that they can be formed uniformly and excellent reliability can be achieved.

[0032]

【Example】

Synthesis Example 1 35 g of perfluoro (butenyl vinyl ether), 150 g of ion-exchanged water, and ((C
H ₃₎ the ₂ CHOCOO) ₂ of 90 mg, internal volume 200
It was put in a pressure-resistant glass autoclave of cc. 3 in the system
After replacement with nitrogen twice, suspension polymerization was carried out at 40 ° C. for 22 hours. As a result, 28 g of fluoropolymer A was obtained. The intrinsic viscosity [η] of this polymer was 0.34 in perfluoro (2-butyltetrahydrofuran) at 30 ° C. The glass transition point of the polymer is 108 ° C., and it is a tough and transparent glassy polymer at room temperature. The 10% thermal decomposition temperature was 465 ° C., and the dielectric constant was 2.1. The surface free energy of this polymer was 19 dyn / cm ² .

Example 1 The fluoropolymer A obtained in Synthesis Example 1 was dissolved in perfluorotributylamine to prepare a 9% by weight solution. This solution was applied on a silicon wafer having a semiconductor element with aluminum wiring by a spin coater, and was applied at 50 ° C. for 1 hour.
For 3 hours after drying for 1 hour at 200 ℃
m coating film was formed. The silicon wafer was previously surface-treated with 3-aminopropyltriethoxysilane.

The wafer on which the fluororesin protective film was formed was set in a parallel plate type plasma apparatus, and argon gas was set to 200 cm ³ (standard state) under a pressure of 1 Torr.
Plasma treatment was performed for a minute.

Next, the polyimide precursor was applied by a spin coater and imidized by heat treatment. After the completion of the wafer process, the assembly process was started, the chips were cut out, mounted on a lead frame, bonded, and then sealed with an epoxy resin. After the moisture absorption test, the IR reflow, and the epoxy resin encapsulation, the adhesion was evaluated by ultrasonic survey, and as a result, excellent adhesion was exhibited.

If the polyimide resin thin film is not formed on the fluororesin protective film and sealed with an epoxy resin, the adhesiveness is deteriorated by the ultrasonic probe evaluation after the IR reflow treatment regardless of the plasma treatment. Admitted.

Table 1 shows the results of the evaluation of the adhesiveness (ultrasonic survey evaluation) to the epoxy resin when only the two-layer film of the fluororesin protective film and the polyimide resin film and the fluororesin protective film were used. In the table, the number represented by% indicates the yield.

[0038]

[Table 1]

[0039]

According to the present invention, a protective film made of a fluororesin having a fluorine-containing alicyclic structure is formed, and a polyimide resin thin film is formed on the surface of the protective film, and then sealed with a sealing resin. The effect of improving the wettability of the sealing resin to the fluororesin protective film, enhancing the adhesion between the two, and obtaining semiconductor elements / integrated circuit devices with excellent electrical characteristics and reliability with an extremely good yield. Have.

 ─────────────────────────────────────────────────── --- Continuation of the front page (72) Hidemitsu Egawa Inventor Hidemitsu Egawa 72 Horikawa-cho, Sachi-ku, Kawasaki-shi, Kanagawa Stock company Toshiba Horikawa-cho factory (72) Inventor Yuri Yonekura 72 Horikawa-cho, Kawasaki-shi, Kanagawa Stock company Toshiba Horikawa-cho factory (72) Inventor Riichiro Aoki 72 Horikawa-cho, Saiwai-ku, Kawasaki-shi, Kanagawa Stock company Toshiba Horikawa-cho factory

Claims (4)

[Claims] 1. A semiconductor element having a polyimide resin thin film between a protective film made of a thin film of a fluororesin having a fluorine-containing alicyclic structure used in a semiconductor device / integrated circuit device and a sealing resin. -Integrated circuit device. 2. The polyimide resin thin film is formed by a method of applying a solution of a polyimide resin on a protective film or a method of applying a solution of a polyimide precursor and then polyimidizing the solution. 1 semiconductor device
Integrated circuit device. 3. The semiconductor element / integrated circuit device according to claim 1, wherein the surface of the protective film on which the polyimide resin thin film is to be formed has been previously subjected to laser light irradiation treatment, corona discharge treatment or plasma treatment. . 4. The semiconductor element / integrated circuit device according to claim 1, 2 or 3, wherein the protective film is a passivation film, a buffer coat film, or a passivation / buffer coat combined film.