JPH0593066A - Method for producing polyimide and method for producing electronic device using the polyimide - Google Patents

Abstract

(57) [Summary] [Structure] Dissociation constant (pKa) of 4 with tetracarboxylic acid diamine and alcoholic or phenolic OH group.
A method for producing a polyimide, in which the compounds of Nos. 12 to 12 are reacted to synthesize a diester compound, the diester compound and a fluorine-containing diamine are reacted in a solvent to synthesize a polyamic acid varnish, and the varnish is heated and condensed. [Effect] Since the diester compound and the fluorine-containing diamine have extremely high reactivity, a fluorine-containing polyimide having a rigid linear structure can be easily synthesized. This has an excellent balance of properties such as heat resistance, low thermal expansion property, low dielectric property, and flatness. Further, the precursor polyamic acid varnish also has low viscosity and high concentration.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a polyimide suitable as an insulating layer of an electronic device such as a thin film magnetic head, a multi-chip module and a semiconductor device, and an electronic device using the polyimide.

[0002]

2. Description of the Related Art Polyimide is widely known as a resin having excellent heat resistance and chemical resistance. And the synthetic method, generally, tetracarboxylic dianhydride or its derivative and a diamine are reacted in a solvent to produce a polyamic acid,
Next, methods such as heat dehydration ring closure or reaction of tetracarboxylic dianhydride and diisocyanate are known.

Although various uses of the polyimide are known, examples of applications to electronic devices include passivation films for semiconductor elements, buffer coat films, α-ray shielding films, thin film magnetic heads, and multi-chips. module,
It is also used in LSI.

However, the electronic device as described above is required to have higher performance and smaller size in recent years, and as a result, the structure has become finer and more complicated. For example, an LSI is a multi-layered wiring and has insulating properties that can sufficiently insulate between upper and lower wirings, and has a small coefficient of thermal expansion and a low dielectric constant. Moreover, when a multilayer wiring board or the like is formed in a manufacturing process, a step or an insulating layer is formed between layers. There is a demand for a highly reliable product that does not cause the disconnection. As such an insulating material, both organic and inorganic materials have been studied, but an organic material is advantageous in terms of low dielectric property and flattening characteristics (hereinafter referred to as flatness).

Polyimide as such an organic material is required to have excellent properties such as low thermal expansion property, low dielectric property and flatness in addition to heat resistance. Especially when low thermal expansion is used by laminating with parts made of inorganic material or metal material,
There is a possibility that the polyimide of the insulating layer may be cracked or separated due to the thermal stress based on the difference in thermal expansion coefficient between these and the polyimide, or the parts made of the inorganic material or the metal material may be damaged. In addition, low dielectric property is also necessary to increase the signal transmission speed of multi-chip modules, LSIs, etc., and flatness is essential for thinning the interlayer insulating layer for increasing the density of multi-layer wiring of LSIs and the like. ..

Looking at the prior art regarding low thermal expansion properties, low dielectric properties, and flatness of polyimide, low thermal expansion products are those using tetracarboxylic dianhydride and diamine having a linear chemical structure. It is known that organic substances having a molecular weight of 2 × 10 ⁵ K to ¹ or less have a small coefficient of thermal expansion (Japanese Patent Laid-Open No. 60-250031). Low dielectric properties are
Hough, J.M. Shaw and G, Tesoro, Alternativeal
Conferance on Polyimides, Proc./Abstracts of
As described in Third. (1988), there is a method of introducing a fluorinated alkyl group, and a method of using a long-chain tetracarboxylic dianhydride to reduce the density of imide bonds (Japanese Patent Laid-Open No. 62-62). No. 265327). On the other hand, for polyimide having excellent flatness, a method using an imide oligomer using a soluble hexafluoropropane group (Japanese Patent Laid-Open No. 63-207867) or PME'89 (Polymer) is used.
s for Microelectronics) / Abstracts on page 96, there is known an esterification method in which the reactivity is controlled by using tetracarboxylic acid as an ester.

[0007]

The above-mentioned conventional polyimides can satisfy individual characteristics (low thermal expansion, low dielectric property, flatness), but have excellent heat resistance and simultaneously satisfy the above respective characteristics. Polyimide has not been found, and therefore, conventional polyimide has improved the performance of electronic devices,
It is hard to say that it is a material that is sufficient for the demand for miniaturization.

An object of the present invention is to provide a process for producing a polyimide which has excellent heat resistance, low thermal expansion, low dielectric properties and flatness.

Another object of the present invention is to provide a method of manufacturing an electronic device using the above polyimide.

[0010]

DISCLOSURE OF THE INVENTION The present inventors first tried to synthesize a polyimide from a tetracarboxylic dianhydride having a linear skeleton and a fluorine-containing diamine in order to achieve both low thermal expansion and low dielectric constant. However, the reaction did not proceed sufficiently and a high molecular weight polyimide could not be obtained.

The cause is diamines with a high fluorine content, which are electron-withdrawing groups having a linear skeleton, such as 4,4'-diamino-octafluorobiphenyl, and the like. (1990), p. 795, it is considered that the electron density of carbonyl carbon is low and the reactivity is extremely low.

Therefore, various synthetic methods for improving the reactivity of the low-reactivity fluorine-containing diamine were investigated. as a result,
A diester compound having a leaving group dissociation constant (pKa) of 4 to 12 has an electron-withdrawing group and easily reacts with a low-reactivity fluorine-containing diamine during the reaction between an acid dianhydride and a diamine. Found.

The reaction between the tetracarboxylic dianhydride and the diamine is a nucleophilic substitution reaction, but the reactivity is in the following order with respect to the nucleophilic substitution reaction of the carboxylic acid derivative.

Acyl chloride>anhydride>ester> amide Therefore, in order to increase the reactivity of the tetracarboxylic acid derivative, the leaving group may be an ester. However, when a strong acid such as hydrogen chloride is used in an electronic device, it causes corrosion of the wiring and is difficult to put into practical use. Therefore, it was considered that if the leaving group is made weakly acidic, the reactivity will be somewhat high and the possibility of corrosion will be small. That is, in the synthesis of polyimide, it was considered that when the leaving group generated during the reaction between the diester compound and the diamine is a weakly acidic compound, the compound becomes highly reactive.

In the system using a diester compound having a weakly acidic leaving group, the reaction between the diester compound and the diamine is low at room temperature, so that the reaction with the diester compound is controlled near room temperature to increase the concentration of varnish. Is possible. Therefore, it was considered that the flatness described later was also excellent. By using such a diester compound, it was possible to supplement the low reactivity of the fluorine-containing diamine having a linear structure and achieve both low thermal expansion and low dielectric properties of the polyimide compound. The gist of the present invention is to react a tetracarboxylic acid diamine with a compound having an alcoholic or phenolic OH group and a dissociation constant (pKa) of 4 to 12 to give a compound of formula [1]

[0016]

[Chemical 7]

(Wherein R ¹ represents a tetravalent organic group, R ² and R ³ represent a monovalent organic group, provided that the formula [1] may be a structural isomer). Of the diester compound represented by the formula [1]

[0018]

Embedded image A diamine represented by H ₂ N—R ⁴ —NH ₂ ... [2] (In the formula, R ⁴ represents a divalent organic group having an electron-withdrawing group.) And both are dissolved. The method for producing a polyamic acid varnish for removing R ² OH and R ³ OH in a solvent, and the method for producing a polyimide characterized by subjecting the varnish to a condensation reaction.

The flatness of the varnish applied on the uneven surface depends on the concentration of the varnish and the melt flow characteristics during curing. That is, the higher the concentration of the varnish, the less the volume shrinkage during curing, and the better the melt flow, the more the step difference caused by the volume shrinkage can be eliminated. However, it is known that the relationship between the concentration of the polymer solution and the viscosity is represented by the formula (1).

[0020]

## EQU1 ## η∝n ³ φ (1) (wherein, η is viscosity, n is degree of polymerization, φ is polymer volume fraction) That is, the viscosity increases sharply as the varnish concentration increases. Not available. However, since the viscosity of the varnish of the present invention can be significantly reduced by lowering the degree of polymerization (n) in the varnish, a varnish having a high viscosity and a low viscosity can be obtained, and a varnish having excellent flatness can be obtained.

The diester compound represented by the above formula [1] improves the reactivity of a low-reactivity fluorine-containing diamine having a linear skeleton in the leaving group having pKa = 4 to 12 when reacted with a diamine. .. A diester compound having a leaving group of pKa <4 is a highly reactive and highly viscous polyamic acid varnish, and therefore cannot have excellent flatness. Further, when the leaving group is pKa> 12, the reactivity with the diester compound is lowered, and the structure of the diester compound requires an electron-withdrawing group, so that only a limited structure is used.

The diester compound of the above formula [1] comprises a tetracarboxylic dianhydride, a compound having an alcoholic or phenolic OH group and a dissociation constant (pKa) of 4 to 12 and a basic or acidic compound. It can be easily obtained by reacting under a catalyst.

As the tetracarboxylic dianhydride,
4,4 '-(hexafluoroisopropylidene) phthalic acid dianhydride, biphenylsulfonic acid-3,3', 4,4'-tetracarboxylic acid dianhydride 3,3 ', 4,4'-biphenyltetra Carboxylic dianhydride, 3,3 ", 4,4" -p-terphenyltetracarboxylic dianhydride, diphenylsulfone-3,3 ', 4,4'-tetracarboxylic dianhydride, diphenyl ether -3,3 ', 4,4'-tetracarboxylic dianhydride, pyromellitic dianhydride, trifluoromethyl pyromellitic dianhydride, bis (trifluoromethyl) pyromellitic dianhydride, etc. Be done.

The alcoholic or phenolic O
Specific examples of the compound having an H group and a dissociation constant (pKa) of 4 to 12 include phenol, o-fluorophenol, and m.
-Fluorophenol, p-fluorofephenol,
o-nitrophenol, m-nitrophenol, p-nitrophenol, 2,3,5-trimethylphenol,
2,4,6-trimethylphenol, o-bromophenol, m-bromophenol, p-bromophenol, o
-Methoxyphenol, m-methoxyphenol, p-
Methoxyphenol, 2,4-dichlorophenol, phenylacetic acid, trifluoroethanol and the like can be mentioned.

Examples of the diamine represented by the above formula [2] include 3,3'-bis (trifluoromethyl) -4,4'-diaminobiphenyl, 4,4'-diamino-octafluorobiphenyl and tetrafluoro-4. -Diaminobenzene,
4,4'-diaminododecafluoro-p-terphenyl and the like can be mentioned.

Examples of the solvent include polar solvents such as N-methylpyrrolidone, dimethylformamide, dimethylsulfoxide and tetrahydrofuran, and mixed solvents of these and nonpolar solvents.

When the diester compound of the above formula [1] of the present invention and the diamine of the above formula [2] are reacted in a solvent, the reaction with the diester compound is controlled at room temperature, so that the reaction with the diester compound is controlled and the viscosity becomes low. The varnish is highly concentrated.
When the varnish is heat-treated, it undergoes a condensation reaction to form a high molecular weight polyimide.

To obtain the polyimide of the present invention, the diester compound represented by the above formula [1] may be mixed with a tetracarboxylic acid dianhydride or its derivative which is usually used. Examples of such tetracarboxylic acid dianhydride or its derivative include 4,4 ′-(hexafluoroisopropylidene) phthalic acid dianhydride and biphenylsulfonic acid-
3,3 ′, 4,4′-tetracarboxylic dianhydride 3,3 ′,
4,4'-biphenyltetracarboxylic dianhydride, 3,
3 ″, 4,4 ″ -p-terphenyltetracarboxylic dianhydride, diphenylsulfone-3,3 ′, 4,4′-tetracarboxylic dianhydride, diphenylether-3,3 ′, 4,
4′-Tetracarboxylic acid dianhydride, pyromellitic dianhydride, trifluoromethylpyromellitic dianhydride, bis (trifluoromethyl) pyromellitic dianhydride and the like can be mentioned.

In order to obtain the polyamic acid of the present invention, the reaction temperature can be selected from any temperature in the range of -20 to + 250 ° C, particularly preferably in the range of -5 to + 200 ° C. Further, in order to convert the polyamic acid into polyimide, a method of dehydration ring closure by heating is usually adopted. The dehydration ring-closing temperature is 150 to 500 ° C., preferably 200 to 47.
It can be carried out at 0 ° C. The time required for the dehydration ring closure is 1 minute to 8 hours, preferably 20 minutes to 4 hours, depending on the reaction temperature.

As another method for converting polyamic acid to polyimide, a known dehydration ring-closing catalyst can be used for chemical ring closure.

A flat polyimide film can be formed by applying the polyamic acid varnish of the present invention by spin coating or the like, heating and curing. In addition,
Thin film magnetic head, multi-chip module, passivation film for electronic devices such as LSI, buffer coat film,
The concentration of the polyamic acid varnish used for the α-ray shielding film or the like is generally ten and several percent. In particular, the above formula [1]
In the polyamic acid varnish obtained by substantially equimolarly mixing the diester compound represented by the formula (1) and the diamine represented by the formula (2) and reacting them in a solvent, a coating film obtained by heating and curing the polyamic acid varnish has a formula The flattening rate shown in 2) is preferably 0.7 or more.

[0032]

## EQU00002 ## Flattening rate = 1-(. DELTA.H / H) (2) (where H is the degree of unevenness of the surface of the coating film-forming body, and .DELTA.H is the degree of unevenness of the coating film surface).

[0033]

The diester compound of the present invention has extremely high reactivity with a diamine on the high temperature side (about 200 ° C. or higher). Therefore,
It also easily reacts with a low-reactivity fluorine-containing diamine having a linear structure.

By using a diester compound having a fluorine group introduced into a linear skeleton structure and an amine, the reactivity of the two can be appropriately controlled, so that the polymerization degree of the polymer can be lowered and the viscosity of the varnish is significantly lowered. In addition, this can reduce the polarizability of the molecule and can provide a polyimide satisfying low thermal expansion, low dielectric property and flatness.

[0035]

The present invention will be described in detail with reference to Examples.

Table 1 shows the viscosity of the polyamic acid varnish produced in each example, the thermal expansion coefficient, the dielectric constant, and the thermal decomposition temperature of the polyimide obtained by heating and condensing the varnish.

[0037]

[Table 1]

Example 1 (1) Synthesis of diester compound Biphenyl-3,3 ', 4,4 was added to a well-dried 1-liter four-necked flask equipped with a calcium chloride tube, a Liebig cooling tube, a thermometer and a stirrer. 4'-Tetracarboxylic acid dianhydride 10
0 g (0.35 mol), 100 g of phenol (1.06 mol) and 6 g of pyridine as a catalyst were added, and the mixture was refluxed for about 70 hours. Infrared absorption (IR) of the obtained diester compound
The measurement result of the spectrum is shown in FIG.

[0039] While an excess of phenol can be seen from Figure 1, the absorption disappears based on the acid anhydride of 1860 cm ~ ¹ and 1780 cm ~ ^1, carboxylic absorption and 2500～2900Cm ~ ¹ based on an ester bond 1840Cm ~ ¹ It shows acid-based absorption. From this, it is understood that a biphenyl diester compound (three isomers are mixed) was obtained.

(2) Synthesis of polyamic acid A calcium chloride tube, a nitrogen gas introducing tube, a thermometer and a stirrer were attached to a well-dried 0.2-liter four-necked flask with a flow rate of 2
While introducing 0 ml / min of nitrogen gas, 15.0 g (0.046 mol) of 4,4'-diaminooctafluorobiphenyl and 55.5 g of N-methylpyrrolidone were added and dissolved with stirring. Then, the synthetic diester compound 21.8
g (0.046 mol) was added, and the mixture was stirred at room temperature (20 ° C.) for 8 hours to obtain a polyamic acid varnish as a polyimide precursor. The measurement result of the IR spectrum of the polyamic acid varnish is shown in FIG. 1650 to 1690 cm from FIG. ¹
And absorption based on polyamic acid appears at 1860 cm- ¹ .

(3) Synthesis of Polyimide The synthetic polyamic acid varnish described above was spin-coated on a silicon wafer having a diameter of 4 inches, and the temperature was set to 100 ° C./hour for 3 hours.
By heating at 50 ° C. or 400 ° C./1 hour, a polyimide film was obtained on the silicon wafer. The IR spectrum, thermal expansion coefficient, dielectric constant and thermal decomposition temperature of the film were measured. The measurement result of the IR spectrum is shown in FIG. Absorption of the polyamic acid from 3 to 1650~1690cm ~ ¹ is disappeared, and appeared the absorption of imide bond in 1730~1760cm ~ ^1, it was confirmed that the polyimide of interest is formed.

The varnish viscosity, flattening rate, thermal expansion coefficient, dielectric constant and thermal decomposition temperature were measured by the following methods.

Viscosity of polyamic acid varnish It was measured at room temperature (25 ° C.) using a rotational viscometer (E type, manufactured by Tokyo Seimitsu Co., Ltd.).

Thermal Expansion Coefficient of Polyimide A polyimide film (film thickness 8 to 10 μm) was set in a thermophysical tester (TMA-3000 type, manufactured by Vacuum Riko Co., Ltd.),
The elongation of the film was measured at a temperature rising rate of 5 ° C./min and a load of 0.5 g per 1 μm of film thickness. 10 on the elongation-temperature curve
The coefficient of thermal expansion was calculated from the elongation rate of 0 to 200 ° C.

Dielectric Constant of Polyimide After forming a polyimide film on a silicon wafer, a circular conductive paste having a diameter of 50 mm is applied on the front surface and the back side of the film, and the LF impedance analyzer (4
Using a Model 192A Yokogawa-Hewlett-Packard Company, measurement was performed at a frequency of 1 KHz in a hygroscopic state at room temperature (25 ° C.) (left standing in 50% RH for 10 hours).

Thermal decomposition start temperature of polyimide: A polyimide film is set on a thermobalance (TGD-3000 type, manufactured by Vacuum Riko Co., Ltd.) to remove moisture absorption, condensed water due to ring closure of unreacted polyamic acid, etc. 5 ° C
The change in weight when heated at 1 / min was measured, and the temperature at which the weight loss rate reached 3% was defined as the thermal decomposition start temperature.

Flattening Rate of Polyimide Evaluation was performed using a test substrate in which the pattern shown in FIG. 7 was formed of aluminum on a silicon substrate. A polyamic acid varnish is spin-coated on a test substrate and cured under the same conditions as the thermal expansion coefficient measurement sample to prepare a sample having a predetermined film thickness. The spin coating was performed at a spinner rotation speed of 250 to 5000 rpm depending on the required film thickness. The flatness of the sample is measured by a contact type surface roughness meter (α-step 200,
It was measured using a Tencar Instruments company). In addition,
The flattening rate in the table is defined by the following equation (3), and the value is the result when a 2 μm film is formed on the pattern. The definitions of ΔH and H in the equation are shown in FIG.

[0048]

[Equation 3] Flattening rate = 1− (ΔH / H) (3) [Example 2] In accordance with the synthesis method described in Example 1,
First, a diester compound was synthesized from biphenyl-3,3 ', 4,4'-tetracarboxylic dianhydride and phenol, and then 3,3'-bis (trifluoromethyl) -4,4'-diaminobiphenyl to polyimide. Was synthesized.

Example 3 According to the synthesis method described in Example 1, a diester compound was first synthesized from cyclopentyltetracarboxylic dianhydride and phenol, and then 4,4′-diaminooctafluorobiphenyl was used to form a polyimide. Was synthesized.

Example 4 According to the synthesis method described in Example 1, first, a diester compound was synthesized from cyclopentyltetracarboxylic dianhydride and phenol, and then 3,3′-bis (trifluoromethyl). A polyimide was synthesized from -4,4'-diaminobiphenyl.

Example 5 According to the synthesis method described in Example 1, a diester compound was first synthesized from trifluoromethyl-p-phenylenediamine and p-methoxyphenol, and then 4,4′-diaminoocta. Polyimide was synthesized from fluorobiphenyl.

Comparative Example 1 While introducing a nitrogen gas at a flow rate of 20 ml / min into a 0.5 l four-necked flask equipped with a calcium chloride tube, a nitrogen gas introduction tube, a thermometer and a stirrer,
10.0 g of 4,4'-diaminooctafluorobiphenyl
(0.03 mol) and 75.4 g of N-methylpyrrolidone are added and dissolved by stirring. After that, biphenyl-3,3 ', 4,4'
-Add 8.8 g (0.03 mol) of tetracarboxylic dianhydride and stir at room temperature (20 ° C) for 8 hours to obtain a polyamic acid varnish. Then, the dehydration ring closure reaction was carried out under the heating conditions of Example 1.

Comparative Example 2 0.5 L 4-necked flask equipped with a calcium chloride tube, a Liebig cooling tube, a thermometer and a stirrer, biphenyl-3,3 ', 4,4'-tetracarboxylic dianhydride 100 g (0.35 mol) and 100 g (2.17 mol) of ethyl alcohol having a pKa of about 18
And are refluxed for about 5 hours. 50 ℃ / 0.1mmHg
The unreacted ethyl alcohol is removed by maintaining the reduced pressure for 5 hours to obtain a diester compound. Then, while introducing nitrogen gas at a flow rate of 20 ml / min into a 0.2 l four-necked flask equipped with a calcium chloride tube, a nitrogen gas introduction tube, a thermometer, and a stirrer, 4,4'-diaminooctafluorobiphenyl 10. 0 g (0.03 mol) and N-methylpyrrolidone 87.0 g are added and dissolved with stirring. Then, 11.7 g (0.03 mol) of the diester compound synthesized above is added and stirred at room temperature (20 ° C.) for 8 hours to obtain a polyamic acid varnish that is a precursor of polyimide. Then, the dehydration ring closure reaction was carried out under the heating conditions described in Example 1.

Comparative Example 3 While introducing a nitrogen gas into a 0.5-liter four-necked flask equipped with a calcium chloride tube, a nitrogen gas introduction tube, a thermometer and a stirrer,
10.0 g (0.093 mol) of p-phenylenediamine and 139 g of N-methylpyrrolidone are added and dissolved with stirring.
Then, 26.9 g (0.093 mol) of biphenyl-3,3 ', 4,4'-tetracarboxylic dianhydride was added, and the mixture was stirred at room temperature (2
The mixture is stirred at 0 ° C.) for 8 hours to obtain a polyamic acid varnish.
Then, the dehydration ring closure reaction was carried out under the heating conditions described in Example 1.

As is apparent from Examples 1 to 5, fluorine-containing fluorine having a linear structure and low reactivity such as 4,4'-diaminooctafluorobiphenyl, which did not react in the conventional method of Comparative Examples 1 and 2. Polyimide is synthesized from the system diamine. Further, by selecting a diester compound or a diamine, it has a small thermal expansion coefficient of 2 × 10 to ⁵ K to ¹ or less, a dielectric constant of 2.5 or less and a high thermal decomposition temperature, and more than conventional ones. It is possible to obtain a polyimide having a flattening property that is two times or more.

Next, a method of manufacturing an electronic device using the polyimide of the present invention will be described.

FIG. 4 shows a schematic cross-sectional view of the multilayer wiring portion of the LSI. Aluminum wiring 3 is formed on the thermal oxide film 2 of the silicon wafer 1, and an insulating thin film 4 of polyimide is formed on the interlayer insulating film of the wiring 3.

The insulating thin film 4 is formed by spin-coating the polyamic acid varnish of the present invention, and by heating and condensing, the steps of the wiring 3 are alleviated and flattened, and a highly reliable wiring structure can be obtained. it can. Since the polyimide according to the present invention has a low thermal expansion coefficient, thermal stress on the LSI element is small, and it is possible to suppress cracking of the element or peeling of the insulating layer due to heat cycle or the like.

FIG. 5 shows a schematic sectional view of the thin film magnetic head. A lower magnetic body 6 and a gap alumina 7 are formed on the lower alumina 5. The first conductor coil 8 and the second conductor coil 10 are insulated by the interlayer insulating film 9. The upper magnetic body 11 is provided in the outermost layer. By forming the above-mentioned interlayer insulating film 9 by the spin coating method of the polyamic acid varnish of the present invention, the step difference of the interlayer insulating film 9 formed by the conductor coils 8 and 10 can be significantly reduced.

In the conventional method of forming an interlayer insulating layer, after thick coating, etching back is performed to flatten the film to a required thickness, but by using the polyimide of the present invention, etching back is almost unnecessary. became. Further, even if etching back is required, the amount of etching back is less than half that in the conventional case, and the manufacturing process can be shortened and the film thickness accuracy can be improved.

FIG. 6 shows a schematic sectional view of the multichip module. A copper wiring 14 is formed on the thermal oxide film 2 of the silicon wafer 1, and a copper wiring 14 ′ is formed via the insulating thin film 4. A thin film electrode (Pb / Sn) is used for the copper wiring 14.
16 through solder ball (BLM; Ball Limiting
A metallization electrode 17 is provided.

When the insulating thin film 4 is formed by using the polyimide of the present invention, the step of the insulating thin film caused by the copper wiring 14 can be flattened, so that a highly reliable wiring structure is provided. Further, thermal stress on the element can be suppressed.

[0063]

The polyimide obtained by using the polyamic acid varnish of the present invention has well-balanced properties of heat resistance, low thermal expansion property, low dielectric property and flatness as compared with the conventional polyimide. By using the above for the insulating layer or the like of the electronic device, an electronic device having excellent reliability can be provided.

[Brief description of drawings]

FIG. 1 is a biphenyl-3 synthesized according to an embodiment of the present invention.
1 is an IR spectrum of a diester compound synthesized from 3 ′, 4,4′-tetracarboxylic dianhydride and phenol.

FIG. 2 is an IR spectrum of a polyamic acid varnish composed of the diester compound shown in FIG. 1, 4,4′-diaminooctafluorobiphenyl and N-methylpyrrolidone.

FIG. 3 is an IR spectrum of a polyimide film obtained by heating and curing the polyamic acid varnish shown in FIG.

FIG. 4 is a schematic cross-sectional view of an LSI multilayer wiring board.

FIG. 5 is a schematic sectional view of a thin film magnetic head.

FIG. 6 is a schematic sectional view of a multi-chip module.

FIG. 7 is a schematic diagram of a flatness evaluation pattern.

FIG. 8 is a schematic sectional view of a flatness evaluation sample.

[Explanation of symbols]

1 ... Silicon wafer, 2 ... Thermal oxide film, 3 ... Aluminum wiring, 4 ... Insulating thin film, 5 ... Lower alumina, 6 ... Lower magnetic material, 7 ... Gap alumina, 8 ... First conductor coil, 9 ...
Interlayer insulating film, 10 ... Second conductor coil, 11 ... Upper magnetic body, 14, 14 '... Copper wiring, 15 ... Interlayer insulating film, 16 ...
Pb / Sn electrode, 17 ... BLM electrode.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Sato Court 4-13-1, Higashimachi, Hitachi, Ibaraki Prefecture Hitachi Chemical Co., Ltd. Yamazaki Factory

Claims (9)

[Claims] 1. A dissociation constant (pKa) having a tetracarboxylic acid diamine and an alcoholic or phenolic OH group.
Of the formula [1] (In the formula, R ¹ represents a tetravalent organic group, and R ² and R ³ represent a monovalent organic group. However, the formula [1] may be a structural isomer.) To synthesize a diester compound. The diester compound represented by the above formula [1] has the formula [2]: H ₂ N—R ⁴ —NH ₂ ... [2] (wherein R ⁴ is a divalent compound having an electron-withdrawing group). A method for producing a polyamic acid varnish, characterized in that R ² OH and R ³ OH are eliminated by a reaction with a diamine represented by the formula (1), which represents an organic group. 2. The viscosity of a polyamic acid varnish obtained by substantially equimolar reaction in a solvent in which both the diester compound represented by the formula [1] and the diamine represented by the formula [2] are dissolved, The method for producing a polyamic acid varnish according to claim 1, wherein the concentration of the polyamic acid is not more than 0.1 poise at a concentration of 30 to 50% by weight. 3. R ^{1 of the} diester compound represented by the above formula [1] is n is an integer of 1 or 2, R ² and R ³ are diester compounds represented by a phenyl group, a mesityl group, a halogenated phenyl group, a benzyl group, and a fluorinated alkyl group, and are represented by the above formula [2]. R ⁴ of the diamine is The method for producing a polyamic acid varnish according to claim 1 or 2, which is a fluorine-containing diamine represented by: 4. A dissociation constant (pKa) having a tetracarboxylic acid diamine and an alcoholic or phenolic OH group.
Of the above formula [1] (wherein
R ¹ is a tetravalent organic group, and R ² and R ³ are monovalent organic groups. However, the formula [1] may be a structural isomer. ) Is synthesized, and the diester compound represented by the above formula [1] is added to the above formula [2] (in the formula, R ⁴ represents a divalent organic group having an electron-withdrawing group). A method for producing a polyimide, characterized in that a polyamic acid varnish is synthesized by desorbing R ² OH and R ³ OH with a diamine represented by the formula ( ^{2) in} a solvent that dissolves both, and the varnish is subjected to a condensation reaction. 5. The viscosity of a polyamic acid varnish obtained by substantially equimolar reaction in a solvent in which both the diester compound represented by the formula [1] and the diamine represented by the formula [2] are dissolved. The method for producing a polyimide according to claim 3, wherein the polyamic acid concentration is 0.1 poise or less at a concentration of 30 to 50% by weight. 6. R ^{1 of the} diester compound represented by the above formula [1] is n is an integer of 1 or 2, R ² and R ³ are diester compounds represented by a phenyl group, a mesityl group, a halogenated phenyl group, a benzyl group, and a fluorinated alkyl group, and are represented by the above formula [2]. R ⁴ of the diamine is The method for producing a polyimide according to claim 4 or 5, which is a fluorine-containing diamine represented by: 7. A method of manufacturing an electronic device having an insulating layer made of a polyimide layer between a conductor or a semiconductor, wherein the insulating layer has a tetracarboxylic acid diamine and an alcoholic or phenolic OH group to dissociate. Constant (p
Ka) is reacted with a compound of 4 to 12 to give a compound of the above formula [1].
(In the formula, R ¹ represents a tetravalent organic group, and R ² and R ³ represent a monovalent organic group. However, the formula [1] may be a structural isomer.) To synthesize a diester compound. A diamine represented by the above formula [2] (in the formula, R ⁴ represents a divalent organic group having an electron-withdrawing group) in the diester compound represented by the above formula [1]; A method for producing an electronic device, comprising forming an insulating layer by applying a polyamic acid varnish obtained by desorption reaction of R ² OH and R ³ OH in a dissolving solvent, and subjecting the varnish to a heat condensation reaction. 8. A method of manufacturing a semiconductor device having an insulating layer made of a polyimide layer between a silicon wafer and a conductor or a conductor, wherein the insulating layer is tetracarboxylic acid diamine and an alcoholic or phenolic OH. Group with a dissociation constant (p
Ka) is reacted with a compound of 4 to 12 to give a compound of the above formula [1].
(In the formula, R ¹ represents a tetravalent organic group, and R ² and R ³ represent a monovalent organic group. However, the formula [1] may be a structural isomer.) To synthesize a diester compound. A diamine represented by the above formula [2] (in the formula, R ⁴ represents a divalent organic group having an electron-withdrawing group) in the diester compound represented by the above formula [1]; A method for manufacturing a semiconductor device, comprising forming an insulating layer by applying a polyamic acid varnish obtained by desorption reaction of R ² OH and R ³ OH in a dissolving solvent, and subjecting the varnish to a heat condensation reaction. 9. A method of manufacturing a thin film magnetic head having an insulating layer made of a polyimide layer between a substrate and wiring or between wiring, wherein the insulating layer is tetracarboxylic acid diamine, alcohol or It has a phenolic OH group and has a dissociation constant (p
Ka) is reacted with a compound of 4 to 12 to give a compound of the above formula [1].
(In the formula, R ¹ represents a tetravalent organic group, and R ² and R ³ represent a monovalent organic group. However, the formula [1] may be a structural isomer.) To synthesize a diester compound. A diamine represented by the above formula [2] (in the formula, R ⁴ represents a divalent organic group having an electron-withdrawing group) in the diester compound represented by the above formula [1]; A method for producing a thin film magnetic head, characterized in that an insulating layer is formed by applying a polyamic acid varnish obtained by desorption reaction of R ² OH and R ³ OH in a dissolving solvent, and the varnish is subjected to a heat condensation reaction.