JPH04337380A - Heat-resistant photo-sensitive polyimide adhesive - Google Patents

Abstract

PURPOSE:To provide the subject adhesive containing a specific polyamic acid, a C=C bond-having amine, etc., as essential components, having excellent heat resistance, adhesiveness and processability and especially useful for assembling semiconductors, etc. CONSTITUTION:The objective adhesive contains (A) a polyamic acid synthesized from (i) a dicarboxylic acid anhydride consisting essentially of 3,3',4,4'- biphenyltetracarboxylic acid(BPDA) and 4,4'-benzophenonetetracarboxylic acid dianhydride(BTDA) and (ii) a diamine consisting essentially of p- phenylenediamine(PPD) and 1,3-bis(3-aminophenoxy)benzene(APB). The contents of BPPA and BTDA are preferably 70-80mol.% and 15-24mol.%, respectively, in the component A, and the contents of PPD and APB are preferably 60-90mol.% and 10-40mol.%, respectively, in the component B.

Description

[Detailed description of the invention]

0001

[Industrial Field of Application] The present invention relates to a heat-resistant photosensitive polyimide adhesive that is highly heat-resistant and can be processed in fewer steps than conventional adhesives, which is particularly useful in the assembly of semiconductor elements in the electronics field, and a method for using the same. It is related to.

0002

2. Description of the Related Art In recent years, new semiconductor devices such as multi-chip modules have been developed as semiconductors become faster and more dense. This enables extremely high-density circuit configuration by mounting multiple semiconductor elements on a multilayer circuit board. When this semiconductor element is mounted on a substrate, circuits are connected within the adhesive surface between the two. Therefore, the adhesive for both is required to have high heat resistance (250° C. or higher) that can withstand the soldering process for circuit connection. Polyimide resins are extremely useful as such adhesives having high heat resistance. This resin has an extremely high thermal decomposition temperature of 500° C. or more, and has high heat resistance that can sufficiently withstand high temperatures during solder mounting.

Furthermore, it is necessary to form a contact hole for wiring within the bonding surface between the two. To form a contact hole using a conventional polyimide adhesive, it is necessary to remove the resin from the hole portion by hydrazine or plasma irradiation using a photoresist. However, these processing steps are complicated and require the addition of new steps such as resist coating or removal, as well as the use of harmful chemicals and special equipment.

0004

SUMMARY OF THE INVENTION An object of the present invention is to provide a heat-resistant, photosensitive polyimide adhesive that has both high heat resistance and easy processability.

[0005]

[Means for Solving the Problems] The present invention provides (A) 3,3
',4,4'-biphenyltetracarboxylic dianhydride (hereinafter abbreviated as BPDA), 3,3',4,4'-benzophenonetetracarboxylic dianhydride (hereinafter abbreviated as BTDA), p-phenylene Diamine (hereinafter abbreviated as PPD)
, a polyamic acid synthesized from a combination of a dianhydride and a diamine containing 1,3-bis(3-aminophenoxy)benzene (hereinafter abbreviated as APB) as an essential component, (B) carbon capable of dimerization or polymerization; - It is a heat-resistant, photosensitive polyimide adhesive containing two essential components: an amine having a carbon double bond, an ammonium compound, or an acid amide compound, and a photosensitizer or the like added as necessary.

[0006]

[Operation] One of the characteristics of the adhesive according to the present invention is that it has a polyamic acid structure as a polyimide precursor in order to realize high heat resistance. After heat curing, this material changes into a polyimide structure with excellent heat resistance. However, general polyimide has poor adhesion to substrates. Therefore, in the present invention, the above-mentioned BTDA, BPDA,
By using a combination of diacid anhydride and diamine containing PPD and APB as essential components, extremely excellent adhesive strength is obtained, especially when the substrate is silicon, glass, alumina, etc.

These BTDA, BPDA, PPD and A
The amount of PB to be charged is preferably 70 to 80 mol% and 15 to 25 mol%, and 60 to 90 mol% and 10 to 40%, respectively, based on the total diacid anhydride. If the proportion of any of these dianhydrides or diamines exceeds the above range, the adhesive strength or heat resistance will decrease. Further, the ratio of all diacid anhydrides to all diamines is desirably 0.
It is 9-1.1. When the ratio is out of this range, the molecular weight of the resin decreases, which tends to cause problems such as a decrease in the viscosity of the varnish and a decrease in sensitivity during optical processing. This polyamic acid preferably contains the above diacid anhydride and diamine at 10%
N,N-dimethylformamide, N,N-dimethylacetamide, N-methyl-2- at a temperature of ℃ to 80℃
It can be obtained by ring-opening polyaddition reaction in a solvent such as pyrrolidone.

A major feature of the present invention is that an amine, ammonium compound, or acid amide compound having a dimerizable or polymerizable carbon-carbon double bond is included in the composition of the adhesive, and if necessary, a photosensitizer. etc., to impart photosensitivity. This makes it possible to process contact holes through a simple and easy process of exposing the resin through a mask to areas other than the areas that need to be removed, and developing to dissolve and remove the resin in the unexposed areas, without having to apply new photoresist. became.

Since the developer used to remove the resin is also an organic solvent, it does not have the same harmful effects as hydrazine and the like, and there is little possibility of environmental pollution. In addition, amines, ammonium compounds, acid amide compounds, photosensitizers, etc. decompose and volatilize during curing after development and do not remain in the resin, resulting in the high adhesiveness and heat resistance inherent to polyimide resins. be able to.

Examples of such amines, ammonium compounds or acid amide compounds include methacrylic acid N,
N-dimethyl-3-propyl, N,N-dimethyl-2-ethyl methacrylate, N,N-diethyl-methacrylate
3-propyl, N,N-dimethyl-3-propyl acrylate, N,N-dimethylacrylamide, N-methylacrylamide, acrylamide, methacrylamide, N
, methylol acrylamide, etc.

[0011] The amount of such amine, ammonium compound or acid amide compound to be added depends on the type thereof, but is desirably 1 part by weight or more and 1000 parts by weight or less per 100 parts by weight of polyamic acid. If it is less than 1 part by weight, practical sensitivity cannot be obtained during optical processing, and if it is more than 1000 parts by weight, the viscosity of the adhesive varnish will decrease significantly, making it difficult to form a good adhesive film or coating on the substrate. becomes.

Furthermore, by adding a photosensitizer such as Michler's ketone to the system as necessary, optical processing can be performed with less exposure energy. It is also possible to simultaneously add a thermal polymerization inhibitor, a leveling agent, etc. to the system.

The adhesive according to the present invention can be used in the form of a varnish or a film dissolved in an organic solvent. This adhesive varnish can be obtained by adding and dissolving the above-mentioned amine, ammonium compound or acid amide compound, a sensitizer as required, etc. into the polyamic acid reaction solution after the completion of the above-mentioned synthesis reaction. Furthermore, some amines, ammonium compounds, or acid amide compounds can be used as a reaction solvent for polyamic acid, and adhesive varnish can be obtained more easily.

[0014] Then, applying this adhesive varnish onto the substrate,
After evaporation of the solvent, exposure through a mask that covers the portion to be removed, development, and drying, adhesion can be performed by overlapping another substrate that requires adhesion and bonding under heat and pressure. The adhesive varnish can be applied using a spin coater, a bar coater, a die coater, etc., and the solvent can be removed by evaporation on a hot plate or in a hot air circulation dryer at 50 to 150°C. Exposure can be performed using ultraviolet/visible light, X-rays, electron beams, excimer lasers, etc.
Preferably, ultraviolet light is used, such as from a high-pressure mercury lamp. After exposure,
The adhesive coating in the unexposed areas is dissolved and removed using an organic solvent.

As the developer, N,N-dimethylformamide, N,N-dimethylacetamide, N-methyl-
The main component is a solvent that dissolves polyamic acid such as 2-pyrrolidone well, and an appropriate amount of a poor solvent such as methyl alcohol or ethyl alcohol is added thereto depending on the resin structure. After development, a photoprocessed polyamic acid coating film is obtained by rinsing with a solvent such as methyl alcohol or ethyl alcohol. After drying at a maximum temperature of 200 to 300°C using a hot air dryer, etc., another substrate that requires adhesion is layered, and the temperature is 300 to 400°C and the pressure is 10 to 100K.
By heat-pressing at g/mm2, it becomes possible to bond with high adhesive strength and high heat resistance.

On the other hand, this adhesive film can be obtained by applying this adhesive varnish onto a substrate, evaporating the solvent, and then peeling it off from the substrate. On the other hand, in the case of using it in film form, the adhesive film is first pasted onto the substrate, and the subsequent operations of exposure, development, drying, overlaying another substrate, and heat-pressing are performed using the adhesive varnish described above. It is exactly the same as when used. Regardless of the usage method, there is no difference in the properties after adhesion, and adhesion with excellent heat resistance and processability is possible depending on the processing method depending on the application.

[0017]

[Examples] The present invention will be specifically explained below with reference to Examples, but it goes without saying that the present invention is not limited to the following Examples.

(Example 1) (1) Synthesis of polyamic acid varnish (I) 20.60 g (0.07 mol) of BPDA, 9.0 g (0.07 mol) of BTDA.
67g (0.03 mol) dissolved in 200ml of N-methyl-2-pyrrolidone (hereinafter abbreviated as NMP) was added with PP.
D7.57g (0.07mol), APB12.07g (
A varnish-like (I) was obtained by adding 0.03 mol) at a system temperature of 20°C and stirring under dry nitrogen for 3 hours while controlling the system temperature at 20°C.

■Preparation of adhesive varnish (II) Add 5 parts by weight of N,N-dimethyl-3-propyl methacrylate and 1 part by weight of Michler's ketone to 100 parts by weight of polyamic acid varnish (I), and stir and dissolve at room temperature. This gave adhesive varnish (II).

■ Adhesion of silicone plate Dispense adhesive varnish (II) onto the silicone plate,
After the solvent was applied evenly using a spin coater so that the thickness after evaporation of the solvent was approximately 15 μm, it was dried at 80°C in a hot air circulation dryer.
The solvent was evaporated by heating for 60 minutes. Next, 1000mJ of ultraviolet rays from a high-pressure mercury lamp was applied through a mask covering the wiring connections.
/cm2 in a mixed solvent of NMP and methanol.
After dipping for a minute, the resin in the unexposed area was dissolved and removed, and then rinsed with 2-propanol. The substrate on which the adhesive pattern was formed in this way was heated at 150°C for 60 minutes, then at 250°C for 60 minutes.
After drying for 0 minutes, another silicon substrate was placed on the adhesive surface, and the two substrates were bonded together by heating and pressing at 350° C. and 50 kg/cm 2 for 5 minutes.

■Measurement of adhesive strength The two silicon plates bonded as described above were cut into a rectangular parallelepiped shape of 10 mm long and 5 mm wide, and a shearing force was applied to the bonded surface to generate the force necessary to cause peeling. It was measured as adhesive strength. As a result, the adhesive strength was as high as 670 kg/mm2.

(Example 2) ■ Preparation of adhesive film (III) Adhesive varnish (III) was uniformly applied onto a glass plate using a dispenser and spin coater so that the thickness became 20 μm after evaporation of the solvent, and then hot air was applied. The adhesive film (III
)was gotten.

■Adhesion of silicon plate Adhesive film (III) is pasted on the silicon plate, then 1000 mJ/cm2 of ultraviolet light from a high-pressure mercury lamp is irradiated through a mask covering the wiring connection part, and 2 After dipping for 30 seconds to dissolve and remove the resin in the unexposed areas, the resin was rinsed with 2-propanol. The substrate on which the adhesive pattern was formed in this way was
After drying at ℃ for 60 minutes and then at 250℃ for 60 minutes, another silicon substrate was placed on the adhesive surface and dried at 350℃ for 50 minutes.
The two substrates were bonded together by heat-pressing at kg/cm for 25 minutes.

(2) Measurement of Adhesive Strength The adhesive strength of the two silicon plates bonded together as described above was measured in the same manner as in Example 1. As a result, the adhesive strength was as high as 550 g/mm2.

(Comparative Example 1) In the synthesis of polyamic acid (I) in Example 1, all dianhydrides were replaced with the same mole of pyromellitic dianhydride, and all diamines were replaced with the same mole of 4,4'-
The same operation as in Example 1 above was carried out except that each substance was replaced with diaminodiphenyl ether. However, the adhesive strength between the two silicon plates was only 40 kg/mm2, which was very low.

(Comparative Example 2) In Example 1, the adhesive varnish (II) was not prepared, but instead the polyamic acid varnish (I) was used as it was as the adhesive varnish. At this time, two new steps of photoresist coating and pre-bake were added before the exposure step in Example 1, and instead of the development step, O2/CF4 plasma irradiation (pressure 0.2 Torr) was added.
By adding the two steps of removing the resin and removing the photoresist using the following method (200 W, output: 200 W, time: 20 minutes), the same adhesion as in Example 1 could be achieved.

[0027]

According to the present invention, it is possible to obtain a heat-resistant, photosensitive polyimide adhesive having high heat resistance, high adhesiveness, and good processability.

Claims (2)

[Claims] Claim 1: (A) 3,3',4,4'-biphenyltetracarboxylic dianhydride (hereinafter abbreviated as BPDA)
, 3,3',4,4'-benzophenonetetracarboxylic dianhydride (hereinafter abbreviated as BTDA), p-phenylenediamine (hereinafter abbreviated as PPD), 1,3-bis(3-aminophenoxy)benzene ( Polyamic acid synthesized from a combination of dianhydride and diamine (hereinafter abbreviated as APB) as an essential component; (B) amine, ammonium compound, or acid amide having a carbon-carbon double bond that can be dimerized or polymerized; A heat-resistant, photosensitive polyimide adhesive that contains two chemical compounds as essential components. [Claim 2] BPDA in polyamic acid (A)
, the content of BTDA in the total diacid anhydride is 7, respectively.
0 to 80 mol%, 15 to 25 mol%, the content of PPD and APB in the total diamine is 60 to 90 mol%, respectively.
, 10 to 40%, and the ratio of total acid anhydride to total diamine is 0.9 to 1.1.