JPH0682649B2 - Insulation film for electric / electronic devices - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application The present invention provides a novel insulating film used in electric / electronic devices, particularly in semiconductor devices.

More specifically, the present invention relates to a novel insulating film having excellent electrical properties such as junction coat, passivation, moisture proof, buffer coat, α-ray shielding, and interlayer insulation, and excellent heat resistance and adhesion.

(B) Conventional Technology A polyimide resin obtained by reacting an aromatic tetracarboxylic acid and its derivative with a diamine exhibits excellent heat resistance and chemical resistance, and is therefore used for various purposes.

Regarding the use of polyimide resin in semiconductor devices, for example, apply polyimide resin to the pn junction (junction coat film) in order to protect the exposed end surface of the pn junction formed on the semiconductor substrate. To prevent contamination, apply polyimide resin to the surface of the device (passivation film), to improve the moisture resistance of the semiconductor device, to apply polyimide resin on the passivation film (moisture prevention film), to protect the semiconductor device mechanically. Applying a polyimide resin on the passivation film (buffer coat film), applying a polyimide resin on the passivation film to prevent a soft error of the memory element due to α-rays (α-ray shielding film), and between the wiring layers. Forming polyimide resin between wiring layers for insulation (interlayer insulation film) Attempts have been made to some are known to. (Functional material, July 1983 issue, p. 9, p.c., CMC Co., Ltd.) (C) Problems to be solved by the invention However, when the polyimide resin is used in each of the above fields, its electrical characteristics are insufficient. Often there is.

That is, since the polyimide resin has a polar group, it is known that it has a disadvantage that it is polarized when a voltage is applied and affects the surface of the semiconductor element to change the element characteristics [CMC Technical Report. Re
port), No. 27, special paint for electronics, page 88, publishing company CMC Co., Ltd.].

It is also known that the polarization (space charge polarization) of the polyimide resin is quantified by measuring the capacitance-voltage (hereinafter abbreviated as CV) characteristic, and the polyimide resin is significantly polarized when a voltage is applied. (Annual Report Conferennce on Electrical Insulati (Annual Report Conferennce on Electrical Insulati)
on & Dielectric Phenomina), 1985, 176-181,
National, Academic, Of, Science, Washington, USA (National Academy of Science, Wash
(ington USA)].

The present invention provides an insulating film for an electric / electronic device, which is made of a novel polyimide resin that has excellent electric characteristics that do not polarize when a voltage is applied, that is, exhibits low polarizability, and that has excellent heat resistance and adhesion. is there.

(D) Means for Solving the Problems As a result of diligent efforts and studies to solve the above problems, the present inventors have constructed tetracarboxylic acid and its derivatives.
Polyimide resin using tetracarboxylic acid and its derivatives in which four atoms directly bonded to each carbonyl group are carbon atoms having no unsaturated bond are not polarized when a voltage is applied, that is, excellent in low polarizability. The inventors have found that the insulating film for electric / electronic devices has excellent electrical characteristics, and has excellent heat resistance and adhesiveness, and has completed the present invention.

That is, the present invention is represented by the general formula [I]. [In the formula, R ₁ is a tetravalent organic group constituting tetracarboxylic acid and its derivative, and the four atoms directly bonded to the four carbonyl groups are carbon atoms having no unsaturated bond, R ₂ is a divalent organic group constituting diamine. ) Electricity consisting of polyimide resin containing repeating units
The present invention relates to an insulating film for electronic devices.

Specific examples of the tetracarboxylic acid and its derivative constituting R ₁ used to obtain the polyimide resin of the general formula [I] used for the insulating film for electric / electronic devices of the present invention include 1,2, Tetra such as 3,4-butanetetracarboxylic acid, cyclobutanetetracarboxylic acid, cyclopentanetetracarboxylic acid, cyclohexanetetracarboxylic acid, and 3,4-dicarboxy-1,2,3,4-tetrahydro-1-naphthalenesuccinic acid. Examples thereof include carboxylic acids and their dianhydrides, and further dicarboxylic acid diacid halides.

The tetracarboxylic acid and its derivative may be used alone or in combination of two or more.

Further, even if a tetracarboxylic acid and its derivative in which four atoms directly bonded to four carbonyl groups are carbon atoms having an unsaturated bond, are mixed and used, to the extent that the effects of the present invention are not impaired. Good.

Specific examples of such tetracarboxylic acid and its derivative include pyromellitic acid, benzophenonetetracarboxylic acid, tetracarboxylic acid of biphenyltetracarboxylic acid and dianhydrides thereof, and further dicarboxylic acid diacid halide and the like. To be

Specific examples of the diamine constituting R ₂ used for obtaining the polyimide resin of the general formula [I] used for the insulating film for electric / electronic devices of the present invention include p-phenylenediamine and m-phenylenediamine. , Diaminophenylmethane, diaminodiphenyl ether, 2,2-diaminodiphenylpropane, diaminodiphenylsulfone, diaminobenzophenone, diaminonaphthalene, 1,3-bis (4-aminophenoxy) benzene, 1,4-bis (4-
Aminophenoxy) benzene, 4,4'-di (4-aminophenoxy) diphenylsulfone, 2,2'-bis [4
Aromatic diamines such as (4-aminophenoxy) phenyl] propane are mentioned.

In addition, alicyclic diamine and aliphatic diamine may be used depending on the purpose.

Further, one kind or a mixture of two or more kinds of these diamines can be used.

The polymerization method for obtaining the polyimide resin of the general formula [I] used for the insulating film for electric / electronic devices of the present invention is not particularly limited, but the polyimide resin can be obtained by the reaction of tetracarboxylic acid or its derivative with diamine. A method of synthesizing a precursor and performing dehydration ring closure is preferable.

Like the usual polycondensation reaction, the polymerization degree n of the obtained polyimide resin precursor and polyimide resin can be arbitrarily adjusted by changing the reaction molar ratio of the tetracarboxylic acid or its derivative and the diamine used. Therefore, the closer the reaction molar ratio of both is to 1, the greater the degree of polymerization n of the obtained polyimide resin.

In the present invention, the degree of polymerization n is 3 or more and 1000 or less, preferably 5 or more and 500 or less.

When n is less than 3, the mechanical strength of the insulating film is insufficient when polyimide resin is used as the insulating film for electric / electronic devices.

When n is larger than 1000, workability in forming the insulating film is significantly reduced.

The reaction temperature of the tetracarboxylic acid or its derivative and the diamine can be selected at an arbitrary temperature of -20 to 150 ° C, but is preferably in the range of -5 to 100 ° C.

Furthermore, in order to convert the polyimide resin precursor into a polyimide resin, a method of dehydration ring closure by heating is usually adopted. The heat dehydration ring-closing temperature is 150 to 450 ° C., preferably
Any temperature between 170 and 350 ° C can be selected.

The time required for the dehydration ring closure is 30 seconds to 10 hours, preferably 5 minutes to 5 hours, depending on the reaction temperature.

As another method of converting the polyimide resin precursor into a polyimide resin, a known dehydration ring-closing catalyst may be used to chemically perform ring closure.

A polyimide resin or a polyimide resin precursor solution obtained from a tetracarboxylic acid or a derivative thereof and a diamine of the present invention is applied to a semiconductor device by a spin coating method or a printing method, and then heated and cured to form a junction coat, for passivation, or moisture proof. , Buffer coat, α-ray shielding, interlayer insulation, etc.

(E) Effect of the Invention The polyimide resin of the general formula [I] of the present invention has excellent electrical characteristics of exhibiting low polarizability even when a voltage is applied, and has excellent heat resistance and adhesiveness. It can be used as an insulating film for electronic devices.

(F) Examples The present invention will be described in more detail below with reference to Examples, but the present invention is not limited thereto.

Example 1 Diaminodiphenyl ether 10.61 g and cyclobutane tetracarboxylic acid dianhydride 10.03 g were reacted in 122 g of N-methyl-2-pyrrolidone (hereinafter abbreviated as NMP) at room temperature for 4 hours to prepare a polyimide resin precursor solution. did. The resulting polyimide resin precursor solution had a solid content of 14.5% by weight and a viscosity of 5.8 ps.

The number average molecular weight was 28,000 as measured by GPC using polyethylene glycol (hereinafter abbreviated as PEG) as a standard.

After diluting this solution with NMP to a total solid content of 7.0% by weight,
A polyimide resin film was formed by spin-coating on an n-type silicon substrate having a thermal oxide film of 00Å formed thereon and heat-treating it at 300 ° C. for 60 minutes. The thickness of the obtained polyimide resin film was 2000 liters.

An aluminum electrode having a diameter of 2 mm was formed on the obtained polyimide resin film by a vacuum evaporation method, and an aluminum electrode was also formed on the back surface of the silicon substrate. Before forming the aluminum electrode on the back surface of the silicon substrate, etching treatment was performed with hydrofluoric acid.

In this way Metal Polyimide Oxide Semiconductor
(Hereinafter, it is abbreviated as MPOS.) A model element is manufactured and C-
The V characteristic was measured.

Figure 1 shows a schematic diagram of the MPOS model device.

In FIG. 1, 1 is an aluminum electrode, 2 is a polyimide resin (film thickness 2000Å), 3 is a thermal oxide film (film thickness 1000Å), and 4 is a silicon substrate.

The CV characteristic measurement conditions are as follows.

That is, leave at + 15V for 40 seconds, sweep the voltage negative at 2V / second, and
Leave for 40 seconds at V, then sweep the voltage positively at 2V / second and stop when + 15V is reached.

The C-V characteristic diagram obtained by the above measurement is shown in FIG.

In FIG. 2, the vertical axis C / Co represents the ratio (%) of the electrostatic capacity to the electrostatic capacity when the bias voltage is +15 V, and the horizontal axis represents the bias voltage (volt). The downward arrow indicates a case of sweeping from the positive direction to the negative direction, and the upward arrow indicates a case of sweeping from the negative direction to the positive direction. (The same applies to FIGS. 3 to 9 below.) From FIG. 2, C-V is obtained regardless of the bias voltage sweep direction.
It can be seen that the curves match and the polyimide resin is not polarized.

For C-V characteristics, Journal, Electrochemical, Society (J. Electrochem. Soc.), 121 volumes,
No. 6, 198C).

Example 2 12.57 g of 1,4-bis (4-aminophenoxy) benzene,
Cyclobutane tetracarboxylic acid dianhydride 8.09 g NMP 117 g
A polyimide resin precursor solution was prepared by reacting at room temperature for 4 hours. The obtained polyimide resin precursor solution has a solid content
At 15.0 wt% the viscosity was 5.6 ps. GP with PEG as standard
According to C measurement, this number average molecular weight was 27,000.

Hereinafter, a CV characteristic diagram obtained by operating in the same manner as in Example 1 is shown in FIG.

From Fig. 3, C-V regardless of the bias voltage sweep direction
It can be seen that the curves match and the polyimide resin is not polarized.

Example 3 1,4-bis (4-aminophenoxy) benzene 5.85 g, 3,
5.89 g of 4-dicarboxy-1,2,3,4-tetrahydro-1-naphthalene succinic dianhydride was reacted in 101 g of NMP at room temperature for 24 hours to prepare a polyimide resin precursor solution. The obtained polyimide resin precursor solution had a solid content of 10.4% by weight and a viscosity of 70.3 ps. According to GPC measurement using PEG as a standard, this number average molecular weight was 24,000.

Hereinafter, a CV characteristic diagram obtained by operating in the same manner as in Example 1 except that the heat treatment temperature after spin coating was 200 ° C.
4 shows.

From Fig.-4, C-V regardless of bias voltage sweep direction
It can be seen that the curves match and the polyimide resin is not polarized.

Example 4 11.4 g of 4,4'-diamino-3,3'-dimethyldicyclohexylmethane, cyclobutanetetracarboxylic dianhydride 1
0.30 g was reacted in 187 g of NMP at room temperature for 48 hours to prepare a polyimide resin precursor solution. The obtained polyimide resin precursor solution had a solid content of 10.6% by weight and a viscosity of 18.9 ps. PE
By GPC measurement with G as standard, this number average molecular weight is 7,000
It was 0.

Hereinafter, a CV characteristic diagram obtained by operating in the same manner as in Example 1 except that the heat treatment temperature after spin coating was 200 ° C.
5 shows.

From Fig. 5, C-V regardless of bias voltage sweep direction
It can be seen that the curves match and the polyimide resin is not polarized.

Comparative Example 1 19.66 g of diaminodiphenyl ether and 20.34 g of pyromellitic dianhydride were reacted in 460 g of NMP at room temperature for 4 hours to prepare a polyimide resin precursor solution. The obtained polyimide resin precursor solution had a solid content of 8.0% by weight and a viscosity of 161 cps.

Hereinafter, the same CV characteristic diagram obtained by operating as in Example 1 is shown in FIG.

It can be seen from FIG. 6 that when the sweep direction of the bias voltage is different, hysteresis occurs in the CV curve and the polyimide resin is polarized.

Comparative Example 2 1,4-bis (4-aminophenoxy) benzene 14.62 g,
4.69 g of pyromellitic dianhydride in 180 g of NMP at room temperature
The reaction was carried out for a time to prepare a polyimide resin precursor solution. The obtained polyimide resin precursor solution had a solid content of 12.3% by weight and a viscosity of 31.7 ps.

Thereafter, the CV characteristic diagram obtained by operating in the same manner as in Example 1 is shown in FIG.

From Fig. 7, if the sweep direction of the bias voltage is different, C-
It can be seen that hysteresis occurs on the V curve and the polyimide resin is polarized.

Comparative Example 3 10.01 g of diaminodiphenyl ether and 15.79 g of benzophenone tetracarboxylic acid dianhydride were added at room temperature in 4 g of NMP of 177 g.
The reaction was carried out for a time to prepare a polyimide resin precursor solution. The obtained polyimide resin precursor solution had a solid content of 12.7% by weight and a viscosity of 435 cps.

Hereinafter, the CV characteristic diagram obtained by operating in the same manner as in Example 1 is shown in FIG.

From Figure-8, if the sweep direction of bias voltage is different, C-V
It can be seen that hysteresis occurs in the curve and the polyimide resin is polarized.

Comparative Example 4 4,4'-diamino-3,3'-dimethyldicyclohexylmethane 11.92 g, pyromellitic dianhydride 11.45 g were added to NMP 200 g.
The reaction was carried out at room temperature for 20 hours to prepare a polyimide resin precursor solution. The obtained polyimide resin precursor solution has a solid content
At 10.5 wt% the viscosity was 16.2 ps.

Hereinafter, a CV characteristic diagram obtained by operating in the same manner as in Example 1 except that the heat treatment temperature after spin coating was 200 ° C.
9 shows.

According to Fig. 9, if the sweep direction of bias voltage is different, C-V
It can be seen that hysteresis occurs in the curve and the polyimide resin is polarized.

[Brief description of drawings]

FIG. 1 shows Metal Polyimide Oxid of Examples 1 to 4.
It is an e Semiconductor (MPOS) model device. 1 ... Aluminum electrode, 2 ... Polyimide resin, 3 ...
Thermal oxide film, 4 Silicon substrate FIGS. 2 to 9 are CV characteristic diagrams of Example 1 to Comparative Example 4. The vertical axis C / Co is the ratio (%) of the electrostatic capacity to the electrostatic capacity when the bias voltage is + 15V, and the horizontal axis is the bias voltage (volts).
Indicates. If the down arrow is swept from positive to negative direction,
The upward arrow indicates the case of sweeping from negative to positive direction.

Claims (1)

[Claims] 1. Represented by the general formula [I] [In the formula, R ₁ is a tetravalent organic group constituting tetracarboxylic acid and its derivative, and the four atoms directly bonded to the four carbonyl groups are carbon atoms having no unsaturated bond, R ₂ is a divalent organic group constituting the diamine, and the repeating unit n is an integer of 3 or more and 1000 or less. ] An insulating film for electric / electronic devices made of a polyimide resin.