JPH0371633A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To avoid the passivation cracking by a method wherein a denatured polyimide resin wherein a compound having any one group out of acryloil group, methacryloil group and acetylenyl group is added or condensation-reacted to polyimide resin represented by specific formulae. CONSTITUTION:The surface of a semiconductor element is coated with a diglyme solution of denatured polyimide resin wherein a compound having any one group out of acryloil group, methacryloil group and acetylenyl group is added or condensation-reacted to polyimide resin comprising acid anhydride, aromatic diamide. organopolysiloxane represented by the formulae I-IV and then developed to be pattern-formed after setting by ultraviolet ray or electron ray. Accordingly, the polyimide resin can be formed into a film on the semiconductor element simply by heating a solvent in relatively low boiling point such as diglyme, etc., at the temperature sufficient for evaporating or volatilizing the solvent. Through these procedures, such problems as passivation cracking, complicated manufacturing process, imidization at high temperature, application of detrimental etchant, etc., can be solved.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention uses a photosensitive polyimide resin as a buffer coating film on a semiconductor element, thereby achieving high reliability as well as heat resistance, and simplifying the manufacturing process. The present invention relates to a method for manufacturing a standardized semiconductor device.

(Prior Art) Recently, there has been remarkable progress in increasing the density and integration of semiconductors, and the circuits on semiconductor elements are becoming thinner and the wiring is becoming more multi-layered.

At the same time, devices are becoming larger in order to increase the capacity of semiconductors, and as a result, it is necessary to reduce the thickness of the encapsulant to prevent the overall volume of semiconductor devices from increasing, which increases the reliability of these semiconductors. The current situation is that the demands for this have become extremely strong. Furthermore, there is a tendency for the mounting method of these semiconductors to shift from the conventional through-hole type to the surface mount type, but since semiconductor devices are exposed to high heat during surface mounting,
Semiconductor devices are required to have high heat resistance and solder crack resistance.

In this trend, by coating the surface of semiconductor devices, they can be made to have high heat resistance, moisture resistance, and σ resistance.
It is known that the introduction of a buffer coat film that relieves the stress from the semiconductor sealing material and prevents the occurrence of passivation cracks in addition to the passivation film that provides linearity has an excellent effect on improving the reliability of the semiconductor.

By the way, it is already well known that by using a polyimide resin with extremely high heat resistance as a buffer coat film, it is possible to protect a semiconductor element, which is extremely sensitive to external temperatures, with heat resistance.

However, conventional Bolii is used as a passivation film.

Although it is recognized that the reliability is improved for those coated with mido resin, the Young's modulus is 300 to 700 kg/+nm2
This is large and cannot completely prevent passivation cracks because it cannot absorb the stress from the outside.
Absolute reliability has not yet been achieved.

As a countermeasure against this problem, a method is known in which, for example, a silicone component is introduced into polyimide resin to lower Young's modulus. (For example, Japanese Unexamined Patent Publication No. 61-64730) Furthermore, the buffer coat film requires a step of opening a bonding pad hole, a pier hole, a redundant hole, etc., but in the conventional polyimide resin passivation film, It required complicated steps such as coating, (1) resist coating, (2) resist exposure, (2) resist development, (2) removal of unnecessary portions of the polyimide resin by etching, (2) resist peeling, and (2) heat curing of the polyimide. In these processes, it is customary to use hydrazine, which is harmful to the human body, as an etching liquid, and there are also problems such as safety in process operations and pollution caused by waste liquid treatment.

Recently, in order to solve problems such as the complexity of these processing steps and the use of harmful chemicals such as hydrazine, so-called photosensitive polyimide, which is made by introducing photosensitive groups into polyamic acid, which is a precursor of polyimide, has been developed. resin has been developed.

(For example, Japanese Patent Publication No. 55-30207, Japanese Patent Publication No. 54-1988
145794, etc.) The processing steps using these photosensitive polyimide resins as a buffer coat film are not only simplified to 1) polyimide coating, 2) exposure, 2) removal of unexposed areas by development, and 2) heating, but also development of the resin. During removal, it is possible to use organic solvents and alkaline aqueous solutions that are less harmful than hydrazine, which improves the safety of process operations.

However, since conventional photosensitive polyimide resins have relatively large values of Young's modulus, even when these photosensitive polyimide resins are used as a buffer coat film, the effect of improving reliability against passivation cracks in semiconductor devices is poor.

Another problem when using polyimide resin as a protective film for semiconductor devices is that most polyimide resins become insoluble in solvents after ring closure and imidization, so it is difficult to apply a solution of polyamic acid to the surface of semiconductor devices before ring closure. After coating, a polyimide resin film is obtained by heating and imidizing, but since the imidizing temperature is as high as 250 to 450°C, the quality of semiconductor elements, which are particularly sensitive to heat, deteriorates. There is a fear.

As one solution to this problem, photosensitive polyimide resins that are soluble in solvents even after quimidization have been developed by selecting the molecular structure of the monomer diacid anhydride or diamine. (For example, Japanese Patent Application Laid-Open No. 59-108031, etc.) However, even when photosensitive polyimide resins soluble in these solvents are used, the fundamental problem of vacillation crank resistance still remains as described above. The present invention addresses various problems that occur when polyimide resin is used in the buffer coat film of semiconductor devices, namely, generation of passivation cracks, complicated manufacturing processes, and imide formation at high temperatures. The object of the present invention is to provide a method for manufacturing a semiconductor device that has high reliability and good processability and workability by solving problems such as chemical processing and the use of harmful etching solutions.

(Means for solving the problem) A compound having any one of an acryloyl group, a methacryloyl group, and an acetylenyl group is added to a polyimide resin consisting of an acid anhydride, an aromatic diamine, and an organopolysiloxane shown in A diglyme solution of modified polyimide resin subjected to a condensation reaction is applied to the surface of a semiconductor element, cured with ultraviolet rays or electron beams, and then developed to form a pattern, thereby producing a semiconductor device with high reliability and good processability and workability. This is the manufacturing method.

(Function) The polyimide resin used in the present invention uses oxycyphthalic dianhydride, particularly 4,4'-oxycyphthalic dianhydride, as the acid anhydride, and uses a diamine with an asymmetric structure as the aromatic diamine.

As a result, even after ring closure and imidization, it becomes soluble in relatively low boiling point solvents such as diglyme, so there is no need to apply the high temperature required when applying a normal polyamic acid solution and imidizing it. Polyimide resin films can be formed on semiconductor devices simply by applying a temperature that evaporates and volatilizes a solvent with a relatively low boiling point, such as diglyme.

Specific examples of aromatic diamines include 2,4-toluenediamine, 2.5-toluenediamine, 2.6-toluenediamine, metaxylene diamine, 2,4-diamino-1,
5-chlorotoluene, 2.4-diamino-6-chlorotoluene, 2.4.6-1-dimethyl-2,3-diaminobenzene, meta, meta-methylenediamine, meta, meta-sulfone dianiline, ortho, Examples include meta-sulfone dianiline and diaminoanthraquinone.

These aromatic diamines may be used alone or in a mixture of two or more types, and it is preferable to use a mixture of two or more types.

For example, a polyimide resin using a mixture of 2,4-toluenediamine and 2,6-toluenediamine exhibits better solubility than one using each aromatic diamine alone.

Incidentally, these aromatic diamines must have a carboxyl group, a hydroxyl group, a hydrothiol group, etc. for introducing a photosensitive group.

The next characteristic of the polyimide resin used in the present invention is the above formula (II
The purpose of this invention is to significantly reduce the Young's modulus of a polyimide resin by introducing a flexible polysiloxane moiety into the main chain of the polyimide using an organopolysiloxane represented by I) or (IV).

In formulas (II[) and [■], R1-R1 is -
CH5, -CFs, -(CHz)n-CFs, -CF
t-CHF-CFs, -CsHs, -CHz-C
H2-COO-CH2-CF, -CF *-c F
, , etc., and R3 is -(CH2)n-, -(CF
*)n-*, -(CH*)n-CF z-,-
C*H4- (all 1≦n≦10) and the like can be cited as examples of R.

Among these, in order to effectively reduce the Young's modulus, R1-R5 are methyl groups, and R2 is -(CHz)x-
Desirably, it is either 1-(CHz)a- or -C4H8-.

In addition, in formulas (n[) and [IV), n is 5 or more, 50
or less, preferably 7 or more and 20 or less.

When n is 5 or less, there is no effect of lowering Young's modulus, and when it is 50 or more, the reactivity of siloxane becomes small and the film properties deteriorate.

The method for synthesizing the polyimide resin of the present invention is to first react an acid anhydride, an aromatic diamine, and an organopolysiloxane in a solvent such as N-methylpyrrolidone at 0 to 80°C, preferably 10 to 30°C, for 2 to 16 hours. By this, a polyamic acid which is a polyimide precursor is obtained.

In the reaction, the molar ratio of acid anhydride and aromatic diamine is l:
A polymer with a high molecular weight and high strength can be obtained by increasing the amount of the acid anhydride or the aromatic diamine to a slight excess, but a polymer with excellent workability and processability can be obtained by adding a very slight excess of either the acid anhydride or the aromatic diamine.

The amount of organopolysiloxane to be blended is preferably 5 to 60% by weight based on the total of the acid anhydride, aromatic diamine, and organopolysiloxane.

When the amount of organopolysiloxane blended is less than 5% by weight, the Young's modulus of the polyimide resin made is 260 kg/
cm'' or more, there is no effect of reducing stress on the semiconductor element, and if the blending amount is greater than 60% by weight, the temperature at which the thermal decomposition of the resulting polyimide resin starts will decrease, and the semiconductor element will be damaged by the gas generated during decomposition. There is a risk of contamination and reduced reliability.

Next, the ring closure and
Imidization is carried out by heating to 90 to 180°C or to the boiling point of the polyamic acid solvent. When the boiling point of the solvent is less than 160°C, imidization can proceed even at low temperatures by adding a dehydrating agent such as acetic anhydride or a tertiary amine such as pyridine.

In addition, depolymerization due to water in the system during imidization can be minimized by adding a solvent such as toluene that is azeotropic with water and removing the water in the system as an azeotrope using a Dean-Starkut trap. It becomes possible to do so.

Next, a photo-crosslinkable functional group is introduced into the aromatic diamine moiety of the polyimide resin thus obtained to impart photosensitivity, thereby facilitating pattern formation of the polyimide resin film.

For this purpose, an aromatic diamine having one of a carboxyl group, a hydroxyl group, and a hydrothiol group is used, and a compound having one of an acryloyl group, a methacryloyl group, and an acetylenyl group is added to these functional groups, or These functional groups are introduced by a condensation reaction.

Examples of reactions for introducing these functional groups include addition or condensation of either the hydroxyl group or hydrothiol group of the aromatic diamine to the carboxyl group (○≦r≦2) of the aromatic diamine. Any of the following ring-opening addition reactions may be mentioned.

Among the reactions for introducing photosensitive groups, the addition reaction of incyanate is 0.
It can be carried out at a relatively low temperature of ~80°C, but especially in the ring-opening reaction of epoxy, it is carried out at a temperature of 120'C in the presence of a catalyst such as a tertiary amine to avoid thermal polymerization of the photosensitive group. It is necessary to do so within the specified time.

The semiconductor device according to the present invention is obtained by applying a polyimide resin solution into which a photosensitive group has been introduced onto the surface of a semiconductor element by a conventional method, and then heating and evaporating the solvent. Electron beam, ultraviolet excimer laser (wavelength 308 nm), i-ray (wavelength 3
65 nm) visible light, g-line (436 nm), etc. are used.

Development is performed using a solvent that dissolves the polyimide resin, such as diglyme, and the unexposed areas are dissolved and removed.

By heating and drying at about 130° C., a polyimide resin pattern having a high thermal decomposition temperature and a low Young's modulus can be obtained.

(Example) Example 1 In a 150n+12 four-bottle flask equipped with a thermometer, nitrogen inlet tube, stirrer, and raw material input section, 3-64sb of 4.4'-year-old xydiphthalic dianhydride was added.
3.5-diaminobenzoic acid 1.20g, the following formula (V)?
3.22 g of the indicated diaminosiloxane 5N-methyl-
20+nl of 2-pyrrolidone was added, and the mixture was stirred and reacted at 20°C for 6 hours.

After removing the solvent, the resulting polyimide resin was further heated at 160'O for 4 hours to imidize it.
Fourth, dissolve 20 m#J of diglyme in a 7-glass flask, and add 1.01 g of glycidyl acrylate and 0.00 hydroquinone.
5g of triethylenediamine and 0.02g of triethylenediamine were added thereto, and the mixture was heated at 90°C for 1 hour under a nitrogen stream.

The average molecular weight of the obtained modified poly 4218M resin was 60 in number.
00, 1L amount was 23,000.

Next, a varnish sensitive to i-line (365 nm) was prepared with the following formulation.

Modified polyimide resin 100 parts by weight Tetraethylene glycol diacrylate 16 parts by weight l-phenyl-propanedione-2-Co-ethoxycarbonyl)oxime 6 parts by weight N-7zyldiethanolamine 311i parts 1-7. Nilu 5~
Mercapto-IH-tetrazole 3 parts by weight Methyldimethoxysilylpropyl methacrylate l! Parts by weight, 6-t-
A varnish containing 0.1 parts by weight of butyl cresol was coated with a spinner to a thickness of 10 μm on the surface of a silicon wafer on which a semiconductor element enclosure was formed. This wafer was prebaked on a hot plate at 60°C for 3 minutes and on a hot plate at 80°C for 3 minutes, then a pattern was placed on it and exposed. For exposure, a contact exposure machine is used,
250n+j/cm2 was applied to the i-line. For development, use a spray developing machine and remove the resin in the unexposed areas (ponding butt holes) with diglyme at 130°C.
It was heated and dried for 20 minutes.

The silicone wafer was then scribed and cut into chips.

This semiconductor element was mounted on a lead frame, bonded with gold wire, and then heat-sealed with an epoxy resin sealant (mold temperature 175°C, 3 minutes, then 17
After curing at 5°C for 8 hours, a semiconductor device was obtained.

Separately, the above modified polyimide resin was spin-coded onto a Teflon plate and dried at 130'C for 20 minutes to form a film with a thickness of about 25 μm,
This film was subjected to tensile testing and thermogravimetric analysis.

Table 1 shows the Young's modulus and thermal decomposition onset temperature obtained as a result of these tests.

As can be seen from Table 1, the polyimide resin applied to the surface of a semiconductor element has both a low Young's modulus and a high thermal decomposition initiation temperature, and a semiconductor device coated with it on the element has a
No gas is generated due to thermal decomposition when sealing with the sealant or bonding with gold paste, and no cracks occur when applying resin to the element or during heat cycle tests of the device after sealing. It had excellent reliability and did not occur.

Examples 2 and 3 The amounts of 4.4'-oxycyphthalic dianhydride, 3.5-diaminobenzoic acid, diaminosiloxane represented by formula (V) and glycidyl acrylate were set as shown in Table 1, The evaluation results of the semiconductor device and film obtained in the same manner as in Example 1 are shown in Table 1.

Similar to Example 1, the resins obtained in Examples 2 and 3 have a low Young's modulus and a high thermal decomposition onset temperature, and semiconductor devices using these resins have good gas generation properties and crack resistance during sealing. The results were obtained.

Comparative Examples 1 to 4 Comparative Example 1 had a high Young's modulus when the amount of diaminosiloxane was reduced to 2% by weight, and no stress reduction effect was obtained.

In Comparative Example 2, the amount of diaminosiloxane was increased to 70% by weight, and unreacted siloxane remained, resulting in a decrease in heat resistance, as well as a large amount of gas generation, resulting in a decrease in reliability due to contamination.

In Comparative Example 3, the degree of siloxane polymerization was 1, and the Young's modulus could not be lowered because this part had poor flexibility.

In Comparative Example 4, the degree of siloxane polymerization was set to 120, and due to the low reactivity of diaminosiloxane, unreacted siloxane bleeds out and not only does the Young's modulus not decrease, but the resulting film is also brittle. there were.

Examples 4-6 4,4'-oxysiphthalic acid, 3,5- as heptanomer
Select diaminobenzoic acid and siloxanoic anhydride represented by the following formula (Vl), and adjust the amounts of these and glycidyl acrylate in the first order.
Semiconductor devices and films were prepared and evaluated using the same equipment and operations as in Example 1 using the settings as shown in the table. The evaluation results are shown in Table 1.

The resins obtained in Examples 4 to 6 have a low Young's modulus and a high thermal decomposition onset temperature, similar to the resins using siloxane diamine obtained in Examples 1 to 3, and are effective in sealing semiconductor devices coated with them. Gas generation properties and crack resistance when stopped were good.

Comparative Examples 5 to 8 In Comparative Example 5, the amount of siloxanoic anhydride was reduced to 2% by weight, the Young's modulus was high, and no stress reduction effect was obtained.

In Comparative Example 6, the amount of siloxanoic acid anhydride was increased to 80% by weight, and unreacted siloxane remained, resulting in reduced reliability due to gas contamination.

In Comparative Example 7, the degree of siloxane polymerization was 1, and due to poor flexibility, the Young's modulus could not be lowered and cracks occurred.

In Comparative Example 8, the degree of siloxane polymerization was 120, and only a brittle film was obtained due to the low reactivity of siloxane.

(Margin below) (Effects of the invention) The polyimide resin used in the present invention has a low Young's modulus and a high thermal decomposition initiation temperature, and is soluble in a relatively low boiling point solvent even after ring closure and imidization. Furthermore, patterning is possible by exposure.

Devices using these polyimide resins as coatings on the surface of semiconductor devices have higher heat resistance and better heat resistance than conventional methods.
It not only has crack resistance and significantly improves the reliability of semiconductor devices by reducing heat damage to semiconductor elements during the coating process, but also simplifies the film patterning process and eliminates the use of harmful developers. It has become possible to make the manufacturing process safer.

Claims (2)

[Claims] (1) (A) Acid anhydride represented by the following formula [I] ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ ... [ I ] (B) Aromatic diamine represented by the following formula [II] ▲ Mathematical formula,
There are chemical formulas, tables, etc. ▼... [II] (Ar: trivalent aromatic group, R_1: -OH, -COOH, -SH group) (C) Organopolysiloxane represented by the following formula [III] ▲ Formula , chemical formulas, tables, etc.▼...[III] (R_2: Divalent unsubstituted or substituted aliphatic hydrocarbon group having 1 to 12 carbon atoms or unsubstituted or substituted aromatic hydrocarbon group having 6 to 10 carbon atoms , R_3_~_6: Same or different monovalent carbon number 1~
12 unsubstituted or substituted aliphatic hydrocarbon groups or unsubstituted or substituted aromatic hydrocarbon groups having 6 to 10 carbon atoms, n: 5 to 50 However, the amount of [III] added is [I] + [II] + [ III]-5
A diglyme solution of a modified polyimide resin obtained by adding or condensing a compound having one of an acryloyl group, a methacryloyl group, and an acetylenyl group to a polyimide resin consisting of (~60% by weight) is applied to the surface of the semiconductor element, A method for manufacturing a semiconductor device, comprising forming a pattern by curing with ultraviolet rays or electron beams and then developing. (2) (A) Acid anhydride represented by the following formula [I] ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼……[ I ] (B) Aromatic diamine represented by the following formula [II] ▲ Mathematical formula,
There are chemical formulas, tables, etc. ▼... [II] (Ar: trivalent aromatic group, R_1: -OH, -COOH, -SH group) (C) Organopolysiloxane represented by the following formula [IV] ▲ Formula , chemical formulas, tables, etc.▼...[IV] (R_7: Trivalent unsubstituted or substituted aliphatic hydrocarbon group having 1 to 12 carbon atoms or unsubstituted or substituted aromatic hydrocarbon group having 6 to 10 carbon atoms , R_3_~_6: Same or different monovalent carbon number 1~
12 unsubstituted or substituted aliphatic hydrocarbon groups or unsubstituted or substituted aromatic hydrocarbon groups having 6 to 10 carbon atoms, n: 5 to 50 However, the amount of [IV] added is [I] + [II] + [ IV] No. 5~
A diglyme solution of a modified polyimide resin obtained by adding or condensing a compound having one of an acryloyl group, a methacryloyl group, and an acetylenyl group to a polyimide resin (60% by weight) is applied to the surface of the semiconductor element, and then exposed to ultraviolet rays. Alternatively, a method for manufacturing a semiconductor device, characterized in that a pattern is formed by curing with an electron beam and then developing.