JP2677855B2 - Mounting board for LSI tower - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of use] The present invention relates to an LSI mounting board,
More specifically, the present invention relates to an LSI mounting board using polyimide as an insulating film of a multilayer wiring structure.

[Prior Art] A mounting board for mounting an LSI using polyimide as an insulating film is described in, for example, “Nikkei Electronics”, page 105, January 1983.
It is known in the 31st issue, also pages 145 to 158, and the 27th August 1984 issue. In this application, as the wiring metal, usually, copper or gold alone or a two-layer structure of these metals and chromium, molybdenum and nickel is mainly used. In such a mounting board, the adhesiveness between polyimide and these wiring metals is extremely important in terms of reliability. When the adhesiveness is lowered, moisture is accumulated at the interface between the polyimide and the wiring metal and the wiring metal is corroded, which adversely affects the reliability. That is, it is indispensable for the polyimide insulating film to have high reliability and durability to withstand any environmental conditions during use, not to mention during the manufacturing or processing of the mounting substrate.

However, conventional polyimides for insulating films, such as polyimide obtained from pyromellitic dianhydride (PMDA) and 4,4′-diaminodiphenyl ether (DAE), and benzophenone tetracarboxylic dianhydride (BTDA) and DAE.
LSI using polyimide obtained from
In a mounting board for mounting, there is a problem that the adhesiveness is often greatly reduced, and an urgent and fundamental solution has been earnestly desired.

[Problems to be Solved by the Invention] The inventors of the present invention have diligently studied measures for improving and improving the adhesiveness in view of the current state of the art, and as a result, in the case of using a polyimide having a specific structure and physical properties, We have found that the drawbacks found in polyimide can be solved, and that a mounting board for LSI mounting with high reliability that can withstand severe environmental conditions during use as well as during the manufacturing or processing stage can be obtained. The invention has been reached.

[Means for Solving the Problems] An object of the present invention is to provide a first-layer wiring formed on a substrate, a first-layer insulating film that covers the first-layer wiring, and a first-layer insulating film.
A mounting board for mounting LSI, comprising a multi-layer wiring structure body, which comprises, as a minimum structural unit, a wiring of a second layer connected to a wiring of the first layer through an opening formed in a layer insulating film, As at least one insulating film, the following A, B and C
A wholly aromatic polyimide satisfying all of the above physical properties, wherein 40 mol% or more of the total acid component of the polyimide is 3,3 ′, 4,4′-
Biphenyl tetracarboxylic acid anhydride, 40 to 85 mol% of all diamine components are paraphenylenediamine and / or
Alternatively, a polyimide which is 4,4′-diaminoterphenyl and 10 to 55 mol% of which is 1,4-bis (4-aminophenoxy) benzene and / or 4,4′-bis (4-aminophenoxy) diphenyl is used. Characterized by using
LSI mounting board.

A. Having a glass transition point, B. Oxygen permeability less than 10 × 10 ^-12 ml / cm ² / sec / cmHg, C. Water vapor permeability less than 1.5g / m ² / 24hr / mm .

The substrate used in the present invention is usually ceramic, but is not limited to this, of course.

The wiring in the present invention is a layer formed in a pattern or on the entire surface so that the electrically conductive material performs a desired function. Aluminum as an electrically conductive material,
Copper, gold, nickel, chromium, molybdenum, nichrome, palladium, silver and the like are preferably used alone or as a layer, but are not limited thereto. These wires are
Usually, it is formed on the entire surface or in a pattern by a physical vapor deposition method such as vacuum vapor deposition, sputtering, electron beam vapor deposition, or plating. When it is formed on the entire surface, it is often patterned by an etching method typified by photoetching.

The polyimide in the present invention refers to the following [I] formula (In the formula, R ₁ is a tetravalent organic group and R ₂ is a divalent organic group.) A polymer containing as a main constituent unit, and having the following physical properties A, B and C at the same time. It is a thing.

A. have a glass transition point, it B. oxygen transmission rate is ^{10 × 10 -12 ml / cm 2} / sec / cmHg, it C. water vapor transmission rate of 1.5g / m ² / 24hr / mm .

In the present invention, wholly aromatic polyimide is used. Here, the wholly aromatic polyimide means that both the acid and the amine constituting the polyimide are aromatic compounds. However, a small amount of an aromatic acid or an acid other than an aromatic amine or an amine can be used as a constituent component as long as the physical properties are not impaired.

Further, the polyimide may contain units other than the above structural unit [I] as long as the above conditions are satisfied. Examples of the unit other than the structural unit [I] include amide imide, ester imide, and amide, but are not limited thereto.

In the structural unit [I], R ₁ is a tetravalent organic group having at least 2 carbon atoms. From the viewpoint of heat resistance of the polyimide, R ₁ preferably has a structure in which the bond with the carbonyl group of the polymer main chain is directly formed from an aromatic ring or an aromatic heterocycle. Therefore, R ₁ contains an aromatic ring or an aromatic heterocycle and has 4 to 6 carbon atoms.
Valent groups are preferred.

In the above structural unit [I], R ₂ is a divalent organic group having at least two carbon atoms, but from the viewpoint of heat resistance of the polyimide, the bond with the imide group of the polymer main chain is an aromatic ring. Alternatively, those having a structure directly formed from an aromatic heterocycle are preferable. Therefore, R ₂ is preferably a divalent group containing an aromatic ring or an aromatic heterocycle and having 6 to 30 carbon atoms.

Furthermore, in order to improve the adhesion between the insulating film made of polyimide and the substrate, it is possible to copolymerize an aliphatic group having a siloxane structure as R ₂ within a range that does not lower the heat resistance. As a preferred specific example But not limited thereto.

In the above structural unit [I], R ₁ and R ₂ may each be composed of only one kind, or may be composed of two or more kinds.

The polyimide having a glass transition point in the present invention means, among the polyimides defined above, one having a clear transition point between 60 and 400 ° C. as measured by a differential scanning calorimeter described later.

When polyimide having no glass transition point is used for the interlayer insulating film, the polyimide-polyimide adhesion is deteriorated even when the oxygen transmission rate and the water vapor transmission rate satisfy the conditions specified in the present invention.

Further, the polyimide used in the present invention has a glass transition point, oxygen permeability is 10 × 10 ^-12 ml / cm ² / sec /
less than cmHg, and water vapor transmission rate 1.5g / m ^2/24
It is necessary to be smaller than hr / mm, and by having such a configuration, the adhesiveness between the interlayer insulating film and the wiring metal can be reliably ensured for a long time even under severe environmental conditions such as high temperature dry heat or wet heat. It can be realized, and durability or reliability can be dramatically improved.

The polyimide used in the present invention is not particularly limited as long as it satisfies all the above characteristics A, B and C. Specific examples of the polyimide that satisfies such conditions include, but are not limited to, polyimides obtained by chemically or thermally converting a polyimide precursor obtained from the following combination of monomers.

(1) 3,3′4,4′-biphenyltetracarboxylic anhydride (BPDA) and paraphenylenediamine (PDA) and 1,4
A polyimide obtained from bis (4-aminophenoxy) benzene (BAPOB).

(2) BPDA and 4,4'-diaminota-phenyl (DATP)
And a polyimide obtained from 4,4'-bis (4-aminophenoxy) diphenyl (BAPOD).

(3) BPDA, pyromellitic dianhydride (PMDA) and BAPO
Polyimide obtained from D and PDA.

Of these, a polyimide in which BPDA is 40 mol% or more of the total acid component is preferable. Further, a polyimide in which 40 to 85 mol% of all amine components are PDA and / or DATP is preferable. Particularly preferred is a polyimide in which BPDA is 40 mol% or more of the total acid component and PDA and / or DATP is 40 to 85 mol% of the total amine component.

Further, a combination of each of these with bis (3-aminopropyl) tetramethyldisiloxane is particularly preferable. Here, bis (3-aminopropyl) tetramethyldisiloxane is 1 to 15 mol%, preferably 3 to 6 mol% of the total amine.

As the polyimide precursor, one to which photosensitivity is imparted,
It is preferable because it can be directly patterned and the process can be simplified, but it is not limited to this. The method of imparting photosensitivity is described in, for example, JP-B-55-30207, JP-A-53-127723, and JP-A-59-52822.

Next, an example of a method of manufacturing the LSI mounting board of the present invention will be described.

First, the wiring of the first layer is formed on a multilayer alumina ceramic substrate including a power source and a ground layer. For example, after sequentially stacking copper and chromium on a ceramic substrate by vapor deposition,
A desired wiring pattern is obtained by photoetching.

Next, an insulating film (D) made of polyimide that satisfies the characteristics A, B and C specified in the present invention is formed. The insulation (D) is usually obtained by applying a solution of the polyimide precursor to form a film (E), patterning it if necessary, and then heat treating it to obtain an insulation film (D).

The pattern processing of the film (E) can be performed by a usual method.

When a photosensitive polyimide precursor is used, after coating and drying, a mask is placed on the photosensitive polyimide precursor film and ultraviolet rays are irradiated. Then, development is performed. After development, heat treatment is performed to obtain a film (D).

The heat treatment is carried out for 5 minutes to 5 hours while selecting several steps of temperature in the range of room temperature to 450 ° C. and gradually raising the temperature or continuously selecting a certain temperature range and continuously raising the temperature. The maximum temperature of this heat treatment is 150 to 450 ° C., preferably 180 or higher. For example, heat treatment is performed at 130 ° C., 200 ° C., and 400 ° C. for 30 minutes each. Also, the temperature may be raised from room temperature to 400 ° C. almost linearly over 2 hours.

When using a non-photosensitive polymide precursor,
After coating and heat treatment, a pattern can be formed by etching with a mixed solution of hydrazine and ethylenediamine using a negative photoresist as a mask or by plasma etching using a metal thin film or the like as a mask.

Next, a wiring is formed on the film (D) to obtain a two-layer wiring structure. By repeating the same procedure below, a structure having three or more wiring layers can be obtained.

[Advantages of the Invention] The present invention uses a polyimide having a glass transition point and a specific oxygen permeability and water vapor permeability as an interlayer insulating film in a mounting substrate for mounting LSI, and thus high temperature deterioration and high humidity are achieved. Since excellent adhesiveness was able to be exhibited even under severe environmental conditions such as deterioration, the reliability and durability of the LSI mounting board can be dramatically improved.

[Measurement Method] (1) Preparation of Polyimide Film A solution of a polyimide precursor (in the case of soluble polyimide, a solution of polyimide) is applied on a polyester film and dried at 80 ° C. for 60 minutes. The polyimide precursor film is peeled from the polyester film, tension-fixed to an iron frame, and then heat-treated at 135 ° C., 250 ° C., and 350 ° C. for 30 minutes each to form a polyimide film. Thickness is 20 ± 2μ
Adjust so that

(2) Measurement of glass transition point A differential scanning calorimetry (DSC) is performed under the following conditions using the film in the item (1).

Differential scanning calorimeter: Perkin Elmer DSC-2 type Sample amount: 10 mg Temperature rising rate: 40 ° C / min Atmosphere: Dry nitrogen Measuring temperature range: 60 ° C to 420 ° C Measurement is performed twice continuously and second time The data was used to examine the presence or absence of transition points between 60 and 400 ° C. The figure shows a typical measurement example. Reference numeral 1 is a measurement example of a polyimide having no glass transition point (polyimide obtained from Comparative Example 1).
Further, 2 is a polyimide having a glass transition point (Example 1
It is an example of measurement of polyimide obtained from.

(3) Measurement of oxygen transmission rate Using the film prepared in (1), a GTR type gas separator manufactured by Yanagimoto Seisakusho Co., Ltd. was used, and measurement was carried out at 24 ° C. by a gas chromatography method.

(4) Measurement of water vapor transmission rate The film prepared in (1) was used to measure at 40 ° C. using a high speed water vapor transmission rate measuring instrument manufactured by Yamatake Honeywell Co., Ltd.

(5) Evaluation of adhesiveness A cutter is used to form 6 cuts at intervals of 2 mm each on the wiring metal surface of the wiring structure to form 25 boards. A cellophane adhesive tape (manufactured by Nichiban Co., Ltd.) is stuck on this, and peeled off according to the method described in JIS D0202 Table 13, Type 1 column, and the number of peeled pieces is checked.

[Examples] The present invention will be specifically described based on Examples, but the present invention is not limited thereto.

Example 1 BAPOB (56.13 g), bis (3-aminopropyl) tetramethyldisiloxane (SiDA) (3.97 g) and PDA (20.76 g) were added to N-.
It was dissolved in 784 g of methyl-2-pyrrolidone (NMP) to prepare an amine solution. To this amine solution, 117.7 g of BPDA was added and reacted at 55 ° C. for 3 hours to obtain a polymer solution of 150 poise at 25 ° C.

To this polymer solution, 126 g of dimethylaminoethyl methacrylate, 5.0 g of 4-azidochalcone, 9.8 g of N-phenyldiethanolamine and 170 g of NMP were added, mixed and passed to prepare a photosensitive polyamide precursor solution.

Copper was deposited on the ceramic substrate by 5 μm and chromium was deposited by 0.2 μm by a sputtering apparatus, and photoetching was performed to form a wiring pattern. The above-mentioned photosensitive polyimide precursor solution was applied onto this substrate and dried at 80 ° C. for 2 hours to obtain a coating film having a film thickness of 20 μm.

Next, it was set on an exposure machine (PLA-501F manufactured by Canon Inc.) and exposed through a mask at 300 mj / cm ² (strength of 365 nm),
It was developed with a developer consisting of NMP / methanol = 70/30 (weight ratio), rinsed with isopropanol, and then dried while rotating with a spinner. Next, heat treatment was performed at 130 ° C., 200 ° C., 300 ° C., and 400 ° C. for 30 minutes in a nitrogen atmosphere to form an insulating film.

On the insulating film thus obtained, the second layer wiring was further formed in the same manner as described above. Repeat in the same way, 3
A layer wiring structure was obtained.

The three-layer wiring structure obtained in this way was dried (20
After standing at 0 ° C. × 200 hours) and in a heat and humidity state (121 ° C., saturated steam at 2 atm for 100 hours), the adhesiveness was examined by the measuring method (5). Further, the presence or absence of a glass transition point, oxygen permeability and water vapor permeability were measured by the methods described in the measuring methods (1), (2) and (3). Table 1 shows the results.

Examples 2 to 6 and Comparative Examples 1 to 5 As in Example 1, the composition of polyimide and the kind of wiring metal were changed to prepare a three-layer wiring structure, and the same evaluation as in Example 1 was performed. The results are summarized in Table 1.

As is clear from Table 1, only substrates having a glass transition point and having oxygen transmission rate and water vapor transmission rate satisfying the conditions specified in the present invention have remarkably excellent adhesiveness after an environmental test, that is, reliability. It turns out that is high.

[Brief description of the drawings]

 The figure is a diagram showing a measurement example of the glass transition point. 1: Polyimide of Comparative Example 1 2: Polyimide of Example 1

Continuation of the front page (56) Reference JP 60-32827 (JP, A) JP 60-44338 (JP, A) JP 61-60725 (JP, A) JP 62-111453 (JP , A) JP 62-140465 (JP, A)

Claims (1)

(57) [Claims] 1. A wiring of a first layer formed on a substrate, and the first wiring.
As a minimum constitutional unit, a first-layer insulating film covering the first-layer wiring and a second-layer wiring connected to the first-layer wiring through an opening formed in the first-layer insulating film are provided. A mounting substrate for mounting LSI, comprising a multi-layer wiring structure, which is a wholly aromatic polyimide satisfying all of the following physical properties A, B and C as an insulating film of at least one layer, and a total acid component of the polyimide. 40 mol% or more of 3,3 ′, 4,4′-biphenyltetracarboxylic acid anhydride is 40 to 85% of the total diamine component.
Mol% is paraphenylenediamine and / or 4,4 '
-Diaminoterphenyl, 10-55 mol% of which is 1,4-
Bis (4-aminophenoxy) benzene and / or
A mounting board for mounting LSI, which is characterized by using a polyimide composed of 4,4′-bis (4-aminophenoxy) diphenyl. A. Having a glass transition point, B. Oxygen permeability less than 10 × 10 ^-12 ml / cm ² / sec / cmHg, C. Water vapor permeability less than 1.5g / m ² / 24hr / mm .