JPS6165457A - Multilayer wiring structure of semiconductor devices - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] [Field of application of the invention] The present invention relates to a multilayer wiring structure of a semiconductor device.

[Background of the invention]

Multilayer wiring technology in the manufacture of semiconductor devices is becoming increasingly important as the degree of integration increases. The technical challenge is to form highly reliable wiring on the various irregularities that appear on the surface when semiconductor devices are formed.

The currently widely used method is vapor phase growth (CVD).
In this method, a multilayer conductor layer for wiring is formed by using an inorganic film made by the above-mentioned inorganic film or a film with an anti-corrosive structure of an inorganic film that can be coated with a spinner as an insulating film between wiring layers.

By the way, in the vapor phase growth method, the irregularities on the surface of the film faithfully reflect the irregularities of the underlying layer, and the surface cannot be flattened.

Flattening the surface not only prevents disconnection of the conductor layer, but also
It is one of the most important multilayer wiring technologies because it prevents the thickness of the conductor layer from decreasing at stepped portions, lowers wiring resistance, and improves wiring processing accuracy.

Conventionally, various methods have been proposed to achieve planarization. For example, Japanese Patent Publication No. 57-18343 discloses a method in which a part of the attached conductor layer is made into an oxide and used as part of an interlayer insulating film to suppress the occurrence of steps. There is also a method of attaching low melting point glass to the surface and heating it to a temperature above the softening point to reduce the slope of the stepped portion, as shown in Japanese Patent Application Laid-open No. 56-76548.

In addition to this method, there is a method using an organic resin film as an interlayer insulating film. For example, polyimide is a typical example. Polyimide is in a liquid state before being cured, and can be easily flattened by simply applying it to the wafer surface with a spinner and leaving it to stand, and has advantageous properties in forming multilayer wiring. However, its fatal drawback, like other organic resin films, is that it has poor moisture permeability. If the interlayer film or the uppermost protective film is moisture permeable, moisture entering from the outside easily reaches the wiring layer and promotes corrosion of the metal used as a conductor.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to provide a multilayer wiring structure for a semiconductor device that can have a flat surface and is highly reliable.

[Summary of the invention]

The features of the present invention include an n-th conductor layer, an insulating layer formed on the n-th conductor layer, and an (n-th) layer laminated on the insulating layer.
+1) multilayer wiring f4 of a semiconductor device consisting of the conductor layer
In the structure, the insulating layer includes an inorganic insulating film laminated on the nth conductor layer and an organic resin film having a coefficient of thermal expansion smaller than that of the (+1+1)th conductor layer. be.

Further, the organic resin film of the present invention is an organic resin film whose coefficient of thermal expansion is larger than that of the inorganic insulating film.

[Example ``A'' of the invention]

FIG. 1 shows a cross-sectional structure when the present invention is applied to a two-layer wiring. The first layer of aluminum is covered with a relatively thin inorganic film 4, on which an organic film is formed. Furthermore, an inorganic film can be used as the top protective film, and the reliability of the second aluminum layer is also ensured.

Hereinafter, embodiments of the present invention will be described in detail using FIG. 2.

(FIG. 2(a)) After various junctions such as source, drain, paste, emitter, etc. are formed on the semiconductor substrate 1, a phosphorus glass 1 (PSG film) 2 is formed on the surface of the semiconductor substrate 1. This area is provided for surface stabilization, as is well known. After this, 118 of the predetermined part where the wiring is to be taken out.
A hole reaching the surface of the medium conductor base 1 is formed in the G film 2 .

In this figure, various joints and irregularities existing on the surface are omitted for simplicity.

(FIG. 2(b)) A second conductor layer 3 is deposited on the entire surface to a predetermined thickness, and unnecessary portions are removed by a conventional lithography technique.

(FIG. 2(C)) Next, an inorganic insulating film 4 is laminated over the entire surface. This inorganic insulating film 4ii covers the surface of the conductor 1-3 to prevent moisture from entering through the upper organic film. This inorganic film plays a further role when the conductor layer 3 is made of aluminum.

It is widely known that aluminum has a phenomenon known as hillocks, where the surface of aluminum rises during heat treatment, but aluminum has an inorganic film on its surface. The thickness of the insulating film 4 is preferably about 1000 to 4000 Å.

(FIG. 2(d)) Next, the expanded polyimide 5 is formed into a predetermined size by applying low heat to the organic resin. Here, low thermal expansion polyimide 5
is one of the materials described below, and its coefficient of thermal expansion is about I x 10-'K"', and At (thermal expansion coefficient equal to 2.3 Department )
, Cu (thermal expansion coefficient 1.4 x 10-'K-')
, ALIC thermal expansion coefficient 1.4 X 10-'K-'
) is smaller than 2 expansion coefficients such as This thickness is designed to reduce the unevenness of the surface to the extent that it does not have a negative effect on the subsequent process of forming the second conductor layer, and also to reduce the interlayer breakdown voltage between the first conductor and the second conductor. should be chosen to have a predetermined value. For normal LSI, 0.5 to 4 μm is appropriate.

(FIG. 2(e)) Next, through holes 9 are formed in the interlayer film consisting of the inorganic insulating film 4 and the low thermal expansion organic film 5. This is possible using conventional photolithography techniques.

In this case, the side wall of the formed through hole 9 becomes a surface inclined at 30 to 50 degrees, as shown in this figure. Therefore, when a second layer conductor is formed as shown in FIG. Since the processing of the inorganic insulating film 4 in this portion can be done as a self-line using the organic film 5 as a mask, no particular problem arises.

(Fig. 2 (0)) After this, the second conductor layer is laminated and patterned using the usual method. At this time, as mentioned above, since the surface irregularities are small, highly accurate processing is possible. Also, variations in conductor film thickness are small, and highly reliable wiring can be formed.

Finally, the entire inorganic insulating film 7, which will serve as a protective film, is formed to form the shape shown in FIG. iFn When an ordinary organic film is used as an interlayer film, if an inorganic film is laminated on top of it, the inorganic film will crack and will no longer function as a protective film.In the case of a low expansion organic film, , there is no such problem, 2t*+'
The reliability of aluminum wiring can be sufficiently increased.

The above has been explained using 2) i wiring sound formation as an example, but when further multilayering is required, the steps shown in Fig. 2 (C) to (f)
All you have to do is repeat the process, and no problems will arise.

In this way, by using the low expansion polyimide film 5e as a part of the interlayer film, it is possible to prevent cracks from occurring and also to flatten the surface. Therefore, it is possible not only to improve the degree of processing and the reliability of wiring, but also to contribute to an improvement in yield, which has a large effect.

A list of materials for the low thermal expansion organic resin film used in the present invention is shown in the following formula (CI).

[I]

(R is a lower alkyl group, a fluorine-containing lower alkyl group, n is O
~4. ) is an aromatic group selected from ] Consists of polyimide containing the chemical structural unit shown.

'Also, it is preferably made of polyimide containing a chemical structural unit represented by [■]. Furthermore, preferably, the polyimide containing the formula [■] or CID has the following formula CI[[] [wherein Ar2 is an aromatic group of 21t[li], A r s
is a tetravalent aromatic group. ] It is a polyimide containing the chemical structural unit shown by.

The material of the organic resin film with low thermal expansion used in the present invention is p-
Phenylesia ξene, 2.4-diaminotoluene, 2.4
= Diaminoxolene, diaminotoluene, 1.5-diaminonaphthalene, 2.6-diaminonaphthalene, or incyanyl compounds thereof! : Can be obtained by reaction with piphenyltetracarbonta or its derivatives. Among diamines, p-phenylenediamine has the best toughness, fatigue properties, and heat resistance. Also,
The same applies to p-phenylene diisonanate.

Derivatives of tetracarboxylic acids include esters, acid anhydrides, and acid chlorides. The use of acid anhydrides is advantageous in terms of synthesis. The synthesis reaction is N-methylpyrrolidone (NMP) and dimethylformamide (DMF).

Dimethylacetamide (J) MAC), dimethyl sulfoxide (DMSO), dimethyl sulfate, sulfolane, butyrolactone, cresol, phenol, halogenated phenol, cyclohexanone.

It is carried out in a solution such as dioxane at a temperature of 0 to 200°C.

In addition to the above-mentioned components, other aromatic diamines, aromatic diisocyanates, tetracarboxylic acids, or derivatives thereof may be introduced as materials for the low thermal expansion organic resin film used in the present invention. It is also possible to denature it.

Specific examples include m-phenylenediamine, benzidine 4.4//-diaminotoluenyl, 4,4/
//-diaminoquaterphenyl, 4゜4'-0 aminodiphenylmethane, 1,2-bis(anilino)ethane, 4.4'-diaminodiphenyl ether, diaminodiphenylsulfone, 2゜2-bisCp-7 minophenyl) Furopane, 2゜2-bis(p-aminophenyl)hexafluoropropane, 3,3'-dimethylbenzidine,
3゜3'-Dimethquinpenzidine, 3.3'-dimethyl-4,4'-diaminodiphenylnial, 3゜3'-
Dimethyl-4,4'-diaminodiphenylmethane, diaminotoluene, diaminobensitrifluoride, 1.
4-bis(p-aminophenoxy7)benzene, 4.4'
-bis(p-aminophenoxy)piphenyl, 2.2-
Bis(4-(p-aminophenoxy)phenyl)propane, diaminoanthraquinone, 4.4'-bis(3-aminophenoxyphenyl)diphenylsulfone, 11)
-bis(anilino]hexafluoropropane, 1.4-
Bis(anilino)octafluorobutane, 1.5-bis(anilino)decafluoropentane, 1.7-bis(anilino)tetradecafluorohbutane, general formula % formula % (Rs, By are divalent organic groups,几4.R6 is a monovalent organic group, diaminotoluene, 2.2-bis(4-(1)-aminophenox7)phenyl)hexafluoropropane, 2. 2-bis[4-(3-aminophenoquine)phenyl)hexafluoropropane, 2,2-bis+4-(2-aminophenoxy)phenyl)hexafluoropropane, 2゜2-bis[4-(4 -aminophenoxy)-3゜5-dimethylphenyl)hexafluoropropane, 2.2-bis+4
-(4-aminophenoxy)-3,5-ditrifluoromethylphenyl)hexafluoropropane, p-bis(
4-Amino-2-trifluoromethylphenoxy7) Benzene, 4゜4'-bis(4-amino-2-trifluoromethylphenoxy)biphenyl, 4.4'-bis(4-
Amino-3-trifluoromethylphenoxy)biphenyl, 4,4'-bis(4-amino-2-trifluoromethylphenoxy)diphenylsulfone, 4,4'-bis(3-amino-5-trifluoromethylphenoxy) Diphenylsulfone, 2,2-bis+4-(4-amino-
Diamines such as 3-trifluoromethylphenoxy)phenyl)hexafluoropropane, and diino-7 obtained by reaction of these diamines with phosgene, etc.
Examples include aromatic diisocyanates such as tolylene diisocyanate, diphenylmethane diisocyanate, naphthalene diisonanate, diphenyl ether diisonanate, phenylene-1,3-'') isocyanate.

In addition, examples of tetracarboxylic acids and derivatives thereof include the following. Although the tetracarboxylic acid is exemplified here, its esterified products, acid anhydrides, and acid chlorides can of course also be used.

Pyromellitic acid, 2,3.3', 4'-tetracarboxydiphenyl, 3.3', 4.4'-tetracarboxydiphenyl ether, 2,3.3'.

4'-tetracarboxydiphenyl ether, 3°3'
, 4.4'-tetracarboxybenzophenone, 2,
3.3', 4'-tetracarpoki7penzophenone, 2,3,6.7-tetracarpoxynaphthalene, 1,
4,5.7-tetracarboxy7f7fiVn, 1,2,
5.6-tetracarpoquinaphthalene, 3.3', 4
．． 4'-Tetracarphokifudiphenylmethane, 2.2-
Bis(3,4-dicarboxyphenyl)propane, 2,
2-bis(3,4-dicarboxyphenyl)hexafluoropropane, 3.3',4.4'-tetracarboxydiphenylsulfone, a,4; 9,10-tetracarboxyperylene, 2,2-bis (4-(3,4-dicarboxyphenoxy)phenyl)propane, 2.2-
Examples include bis[4-(3,4-dicarboxyphenox7)phenyl)hexafluoropropane, phthanetetracarboxylic acid, and cyclobenkunetetracarboxylic acid. Also,
It is also possible to introduce a crosslinked structure or ladder structure by modifying with a compound having a reactive functional group. For example, there are the following methods.

(1) By modifying with a compound represented by the general formula (IV), all of the pyrrolone ring, isoindoquinazolinedione ring, etc. are introduced.

Here, R' is a 2 +

X is 1 or 2.

(11) Amine, diamine having a polymerizable unsaturated bond,
It is modified with dicarboxylic acid, tricarboxylic acid, and tetracarboxylic acid derivatives to form a crosslinked structure upon curing. As the unsaturated compound, maleic acid, nadic acid, tetrahydrophthalic acid, ethynylaniline, etc. can be used.

(Ill) A phenolic hydroxyl group or a carboxylic acid is modified with an aromatic amine, and a network structure is formed using a crosslinking agent that can react with the hydroxyl group or carboxyl group.

Each of these ingredients? The coefficient of thermal expansion is 4 by modifying with
14 can be adjusted. That is, the specific modification component detailed above is included in the general formula [■], and by increasing the content ft of this structural unit, the polymer consisting only of the structural units represented by the general formula [■] It can be made larger than the expansion coefficient, and can be arbitrarily set depending on the purpose or use. For example, the coefficient of linear expansion of a polymer consisting only of structural units represented by the general formula C1) is approximately I
-1 to 10-', but paraphenylenediamine (abbreviated as A'I+I'I'DA of general formula [I]) has diaminodiphenyl needles (ff formula, c II
) (2) A'2.

When DDE (abbreviated as DDE) is blended, the linear expansion coefficient of the polyimide produced is as shown in FIG. In addition, the carboxylic acid component used at this time was one using only biphenyltetracarboxylic dianhydride, which was reacted with a wholly aromatic diamine component using halogen.

In addition, it can be seen from FIG. 3 that the expansion coefficient decreases quite rapidly when the amount of DDE added is 75 moles.

In this example, since the low thermal expansion organic resin material is used in combination with an inorganic insulating film, adhesion with the material is important. It is preferable to roughen the surface of the material of the insulating film or to perform surface treatment with a silane coupling agent, titanate coupling, aluminum alcoholate, aluminum chelate, zirconium chelate, aluminum acetylacetone, etc. These surface treatments Agents may be added to the low thermal expansion organic phase 11'r''r material.

In this example, in order to lower the coefficient of thermal expansion, increase the modulus of elasticity, control fluidity, or reduce costs, we used powders, fibers, and chopped materials such as inorganic, organic, or metal materials. It is also possible to use a mixture of strands.

〔Effect of the invention〕

According to the present invention, it is possible to obtain a multilayer wiring structure of a semiconductor device that can flatten the surface and prevent the occurrence of cranks.

[Brief explanation of drawings]

Figure 1 is a cross-sectional structural diagram of an embodiment of the present invention, Figure 2 is a manufacturing process diagram of an embodiment of the present invention, and Figure 3 is a diagram showing the relationship between the amount of DDE blended and the coefficient of linear expansion of polyimide. be. 3... First conductor layer, 4... Inorganic insulating film, 5...
・Low heat 2nd blade 2nd cause (〆UGE) 315g

Claims (1)

[Claims] 1. nth conductor layer, insulating layer laminated on this nth conductor layer, (n+1)th conductor layer laminated on this insulating layer
In a multilayer wiring structure of a semiconductor device including a conductor layer, the insulating layer has a coefficient of thermal expansion that is higher than that of the (n+1)th conductor layer than the inorganic insulating film laminated on the n-th conductor layer. 1. A multilayer wiring structure for a semiconductor device, comprising an organic resin film having a coefficient of thermal expansion smaller than that of . 2. A multilayer wiring structure for a semiconductor device according to claim 1, wherein the organic resin film is an organic resin film having a coefficient of thermal expansion larger than that of the inorganic insulating film. 3. In claim 1, the organic resin film is expressed by the following formula [I] ▲There are mathematical formulas, chemical formulas, tables, etc.▼[I] [In the formula, Ar_1 is ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (R is a lower alkyl group, a fluorine-containing lower alkyl group, n is 0
~4. ), ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ and ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ It is an aromatic group selected from. ] A multilayer wiring structure for a semiconductor device, characterized in that it is made of polyimide containing a chemical structural unit represented by the following. 4. In claim 1, the organic resin film is made of polyimide containing a chemical structural unit represented by the following formula [II] ▲ Numerical formula, chemical formula, table, etc. ▼ [II] Multilayer wiring structure of semiconductor devices. 5. In claim 3 or 4, the organic resin film has the following formula [III] ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ [III] [In the formula, Ar_2 is a divalent aromatic group. , Ar_3 is a tetravalent aromatic group. ] A multilayer wiring structure for a semiconductor device, characterized in that it is made of polyimide containing a chemical structural unit represented by the following.