JPH07273470A - Multilayer-wiring structure - Google Patents

Abstract

PURPOSE:To stably manufacture the title high reliable multilayer-wiring structure capable of avoiding the release of a polyimide base insulating film from the substrate by covering the end of the substrate with the polyimide base insulating film. CONSTITUTION:Within the title multilayer-wiring structure provided with the first layer metallic wiring 3a formed on a substrate 1, the first layer insulating film 2a covering the first layer metallic wiring 3a as well as the second layer metallic wiring 3b connecting to the first layer metallic wiring 3a through the intermediary of an aperture part formed in the first layer insulating film 2a as the minimum components, at least one part of the upper end of the substrate 1 is covered with the first layer insulating film 2a.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multi-layer wiring structure, and more particularly to a multi-layer wiring structure for high density mounting using a polyimide resin or the like as an interlayer insulating film.

[0002]

2. Description of the Related Art A multilayer wiring structure having a structure shown in FIG. 3 is known as a high-density mounting multilayer wiring structure using a polyimide resin or the like as an interlayer insulating film (for example, "Nikkei Electronics" 149). Page, August 27, 1984 issue or TAKASHI INOUE et al., Micro Carrier for LSI
Chip Used in the HITAC M-880 Processor Group, IEE
E, 704, 1991). In FIG. 3, 1 is a substrate, 2a, 2b,
2c are insulating films of the first layer, the second layer, and the third layer, and 3c.
Reference numerals a, 3b, and 3c denote metal wirings of the first layer, the second layer, and the third layer, respectively, and 4 denotes an upper wiring and an opening (connection hole) portion.

[0003]

In such a multilayer wiring structure, the interlayer insulating film made of polyimide resin or the like must be formed by heat-treating each layer at about 400.degree. Further, when the metal wiring is formed by the sputtering method, the temperature of the substrate becomes high during the sputtering. Therefore, the lower insulating film (especially the first insulating film) is subjected to the thermal history of the number of times corresponding to the total number of wirings. Therefore, although the heat treatment is usually performed in a nitrogen atmosphere as the total number of wirings increases, deterioration of the insulating film made of polyimide resin or the like is promoted by a slight amount of oxygen. Further, thermal stress is accumulated at the interface due to the difference in thermal expansion coefficient between the substrate and the polyimide resin or the like.

However, since no consideration has been given to the structure of the end face of the substrate in the past, the adhesive force at the interface between the substrate and the insulating film is reduced, and the problem that the lower insulating film is peeled off from the substrate occurs, resulting in a multilayer wiring. The reliability of the construct was low.

The present invention was devised in view of the above-mentioned drawbacks of the prior art. The object of the present invention is to prevent the peeling between the substrate and the insulating film as seen in the conventional multilayer wiring structure. It is to obtain a multilayer wiring structure that is reliably prevented and has high reliability.

[0006]

The object of the present invention is as follows.
The first layer metal wiring formed on the substrate, the first layer insulating film covering the first layer metal wiring, and the first layer metal through the opening formed in the first layer insulating film A multilayer wiring structure including a second-layer metal wiring connected to a wiring as a minimum structural unit, wherein at least a part of an upper end of an end face of the substrate is covered with an insulating film. Achieved by the construct.

An example of a schematic sectional view of the multi-layer structure of the present invention is shown in FIGS. FIGS. 1 and 2 show a three-layer wiring structure, in which 1 is a substrate, 2a, 2b, and 2c are first-layer, second-layer, and third-layer insulating films, 3a, 3b, and 3, respectively.
Reference numeral c denotes metal wirings of the first layer, the second layer, and the third layer, 4 denotes an opening (connection hole) portion with respect to the upper wiring, and 5 denotes an end face of the substrate. The first layer metal wiring 3a on the substrate 1, the first layer insulating film 2a covering the first layer metal wiring 3a, the second layer metal wiring 3b on the first layer insulating film, the second layer A second-layer insulating film 2b covering the first-layer metal wiring 3b, a third-layer metal wiring 2c on the second-layer insulating film, and a third-layer insulating film 2c covering the third-layer metal wiring 3c. Has been formed. The upper end of the end surface 5 of the substrate is covered with the first-layer insulating film 2a in FIG. 1 and the second-layer insulating film 2b in FIG. The present invention is not limited to these aspects, and may be covered with an insulating film having a third layer or more, or may be covered with an insulating film having a plurality of layers. Alternatively, it may be covered with an insulating film formed separately for the purpose of covering the end face of the substrate, separately from the upper insulating film to be laminated.

With the structure in which at least a part of the upper end of the end surface of the substrate is covered with the insulating film, the insulating film on the end surface of the substrate is partially connected to the insulating film on the upper surface of the substrate. Also in this case, peeling does not occur between the substrate and the insulating film, and a highly reliable multilayer wiring structure can be obtained.

As the substrate in the present invention, silicon,
Aluminum, aluminum nitride, alumina ceramics, glass ceramics, sapphire, glass and the like are used, but not limited thereto. Further, as the substrate in the present invention, a substrate in which a thin layer of an inorganic compound type or an organic compound type is previously formed on these substrates can also be used. An example of such a substrate is a silicon substrate on which a silicon oxide layer is formed. The thin layer previously formed here may be patterned.

As the metal wiring in the present invention, gold,
Patterned so that copper, nickel, chromium and / or copper alloys, nickel alloys, alone or in multiple layers with electrically conductive materials such as aluminum, gold, chromium, platinum, silver, perform the desired function. Alternatively, a layer formed over the entire surface or the like is used, but the layer is not limited to these. These metal wirings are usually formed by a method such as vacuum deposition, sputtering and plating.

The insulating film in the present invention includes an insulating film made of a polyimide resin, an epoxy resin, a benzocyclobutene resin, etc., but a polyimide insulating film is generally used. The polyimide-based insulating film is formed by selectively combining tetracarboxylic dianhydride and diamine, and reacting them in a polar solvent such as N-methyl-2-pyrrolidone or N, N-dimethylacetamide to prepare a polyimide precursor. A varnish can be obtained by applying this polyimide precursor varnish on a substrate and performing heat treatment in the range of 200 to 400 ° C. for dehydration condensation, and known ones can be used. As a specific example, pyromellitic dianhydride and 4,4′-diaminodiphenyl ether, 3,
3 ', 4,4'-benzophenone tetracarboxylic dianhydride and 4,4'-diaminodiphenyl ether, 3,3
′, 4,4′-Biphenyltetracarboxylic dianhydride and 4,4′-diaminodiphenyl ether, pyromellitic dianhydride and 3,3 ′ (or 4,4 ′)-diaminodiphenyl sulfone, pyromellitic dianhydride Anhydrous and 3,
3 ', 4,4'-benzophenone tetracarboxylic dianhydride and 3,3' (or 4,4 ')-diaminodiphenyl sulfone, 3,3', 4,4'-benzophenone tetracarboxylic dianhydride 3,3 '(or 4,4')-
Diaminodiphenyl sulfone, 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride and 3,3 ′ (or 4,4 ′)-diaminodiphenyl sulfone, pyromellitic dianhydride and 4,4′- Diaminodiphenyl sulfide, 3,3 ', 4,4'-benzophenone tetracarboxylic dianhydride and 4,4'-diaminodiphenyl sulfide, 3,3', 4,4'-biphenyltetracarboxylic dianhydride and 4 , 4'-diaminodiphenyl sulfide,
3,3 ′, 4,4′-benzophenone tetracarboxylic dianhydride and paraphenylenediamine, 3,3 ′, 4,4
′ -Biphenyltetracarboxylic dianhydride and para-phenylenediamine, pyromellitic dianhydride and 3,3
′, 4,4′-Benzophenonetetracarboxylic dianhydride and paraphenylenediamine, pyromellitic dianhydride and 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride and paraphenylenediamine, 3, 3 ', 4,
4'-diphenyl ether tetracarboxylic acid dianhydride and 4,4'-diaminodiphenyl ether, 3,3 ',
Polyimide synthesized from 4,4′-diphenyl ether tetracarboxylic dianhydride and paraphenylenediamine, pyromellitic dianhydride and 4,4′-diaminodiphenyl ether and bis (3-aminopropyl) tetramethyldisiloxane A varnish of a precursor and a varnish of a photosensitive polyimide precursor obtained by imparting photosensitivity to these polyimide precursors are preferably used.

As the photosensitive polyimide precursor, for example, Japanese Patent Publication No. 55-30207 and Japanese Patent Publication No. 59-5282.
2, those described in JP-A-53-127723 can be used. Further, a commercially available photosensitive polyimide precursor can also be preferably used. As a commercially available photosensitive polyimide precursor, "Photonice" UR-
3140, UR-3180 (all manufactured by Toray Industries, Inc.),
"Paimel" G-6246A, TL (all manufactured by Asahi Kasei Corporation), "Pyralin" PD-2720, PD-2
740 (all manufactured by DuPont), "Photopal"
PL-3000 (manufactured by Hitachi Chemical Co., Ltd.) and the like are preferably used.

Next, an example of the method for manufacturing the multilayer wiring structure of the present invention will be described, but the present invention is not limited to this.

First-layer metal wiring is formed on a silicon substrate. For example, by sputtering copper on a silicon substrate
After forming 0.3 μm and further 10 μm by electrolytic plating, chromium is formed by sputtering to 0.1 μm and photoetching is performed to obtain a desired wiring pattern.

A first layer of polyimide-based insulating film is formed on this substrate. Usually, in order to provide an opening (connection hole) for the upper wiring, the polyimide insulating film is patterned. The pattern processing can be performed by a known method.

When a photosensitive polyimide precursor is used, after the polyimide precursor is applied and dried, a mask is placed on the photosensitive polyimide precursor film and ultraviolet rays are irradiated. Then, development is performed. After development, heat treatment is performed to obtain a substrate having an end face covered with a polyimide insulating film. When a polyimide precursor having no photosensitivity is used, the polyimide precursor is coated, dried, and heat treated, and then the polyimide is etched with oxygen plasma or the like to form a pattern using a metal thin film, silicon oxide, or a photoresist as a mask. .
Drying of the polyimide precursor is preferably performed in the range of 60 to 160 ° C. The heat treatment is carried out for 5 minutes to 5 hours in a nitrogen atmosphere by selecting a temperature from room temperature to 460 ° C. and gradually raising the temperature or selecting a certain temperature range and continuously raising the temperature.
The maximum temperature of this heat treatment is 120 to 460 ° C, preferably 130 to 450 ° C. For example, 130
Heat treatment is performed at 30 ° C., 200 ° C. and 400 ° C. for 30 minutes each. Alternatively, the temperature may be linearly raised from room temperature to 400 ° C. over 2 hours. After forming the pattern, it is desirable to etch the surface with an aqueous solution of ammonium persulfate or perform plasma treatment in order to reduce the contact resistance of the opening (connection hole) with the upper wiring.

When at least a part of the upper end of the end face of the substrate is covered with the first-layer polyimide insulating film, for example, the first layer polyimide precursor is applied so as to cover the end face of the substrate. That is, in the case of applying a polyimide-based insulating film using a spinner, after applying the polyimide precursor under predetermined conditions, a method of gradually reducing the number of rotations, after applying the polyimide precursor to the substrate upper surface with a spinner, the polyimide precursor Examples of the method include coating the end face with a roll coater or a spatula. When the coating is applied to the end face of the substrate as described above, it is necessary to irradiate the ultraviolet rays using a mask such that a pattern remains on the end face of the substrate. Also,
First, after patterning a polyimide-based insulating film on the upper surface of the substrate, the polyimide precursor may be applied to the end faces, and the substrate may be heat-treated again to imidize the polyimide precursor on the end faces.

Next, a two-layer wiring structure is obtained by forming a second layer of metal wiring on the wiring board thus obtained. Similar to the metal wiring of the first layer, the metal wiring of the second layer is, for example, 0.3 μm of copper is formed on the substrate by sputtering, 10 μm is further formed by electrolytic plating, and then chromium is formed by 0.1 μm by sputtering, and photoetching is performed. Can be formed.

Similarly, by repeating the above operation, a higher-order multilayer wiring structure can be obtained. When at least a part of the upper end of the substrate is covered with the second or more layers of the polyimide-based insulating film, the same procedure as that of the first-layer polyimide-based insulating film may be performed.

Also, when an insulating film other than the polyimide resin is used, the same method may be used.

[0021]

EXAMPLES The present invention will be specifically described below based on examples, but the present invention is not limited thereto.

Example 1 Copper was formed on a 99.5% alumina / ceramic substrate (10 × 10 × 0.2 cm) by sputtering to a thickness of 0.3 μm, and electrolytic plating was further performed to form a thickness of 10 μm.
Then, the first layer metal wiring pattern was formed by photolithography.

A photosensitive polyimide precursor "Photonice" UR-3180 (manufactured by Toray Industries, Inc.) was coated on this substrate with a spinner, and then the same photosensitive polyimide precursor was coated on the end face with a spatula, and the upper end of the end face was coated. Was covered with a photosensitive polyimide precursor. Dry at 80 ° C for 120 minutes in nitrogen atmosphere to a film thickness of 40
A μm photosensitive polyimide precursor coating was formed. The photosensitive polyimide precursor coating was exposed at 600 mJ / cm ² through the mask using an ultraviolet light exposure device PLA-501F manufactured by Canon Inc., and then the mask was removed,
The end face of the substrate was exposed at 600 mJ / cm ² . Developer D
Immersion development was performed while applying ultrasonic waves to V-605 (manufactured by Toray Industries, Inc.), rinsed with 2-propanol and blown with nitrogen to dry. Next, heat treatment was performed at 130 ° C., 200 ° C., and 400 ° C. for 30 minutes in a nitrogen atmosphere to form a substrate in which the upper end of the end face was covered with the first-layer polyimide insulating film.

Next, a second layer metal wiring was formed on the wiring board thus obtained to obtain a two-layer wiring structure. Second
Similar to the first layer metal wiring, the layer metal wiring is formed by forming 0.3 μm of copper on the substrate by sputtering, further forming 10 μm by electrolytic plating, and then forming 0.1 μm of chromium by sputtering and photoetching. did. Thereafter, this process was repeated in the same manner to obtain a three-layer wiring structure. However, the second- and third-layer polyimide insulating films were formed only on the upper surface of the substrate. A schematic cross-sectional view of the three-layer wiring structure obtained in this manner is shown in FIG.

The three-layer wiring structure was dipped in a 5% potassium hydroxide aqueous solution for 40 minutes, and the adhesiveness between the polyimide insulating film and the substrate was examined. As a result, no peeling from the substrate was observed.

Comparative Example 1 In Example 1, a three-layer wiring structure was obtained without covering the upper part of the end face of the substrate with the first layer of polyimide insulating film. A schematic cross-sectional view of the three-layer wiring structure thus obtained is shown in FIG.

The three-layer wiring structure was dipped in a 5% potassium hydroxide aqueous solution for 40 minutes, and the adhesiveness between the polyimide insulating film and the substrate was examined. As a result, the first-layer polyimide insulating film was peeled from the substrate.

Example 2 In Example 1, a three-layer wiring structure was obtained by using a silicon substrate on which a patterned silicon oxide layer was formed instead of the alumina / ceramic substrate as the substrate.

The three-layer wiring structure was dipped in a 5% potassium hydroxide aqueous solution for 40 minutes, and the adhesiveness between the polyimide insulating film and the substrate was examined. As a result, no peeling from the substrate was observed.

Comparative Example 2 In Example 2, a three-layer wiring structure was obtained without covering the upper part of the end face of the substrate with the first-layer polyimide insulating film.

The three-layer wiring structure was dipped in a 5% potassium hydroxide aqueous solution for 40 minutes, and the adhesiveness between the polyimide insulating film and the substrate was examined. As a result, the first-layer polyimide insulating film was peeled from the substrate.

Example 3 In Example 1, instead of covering the upper end of the end face of the substrate with the polyimide insulating film of the first layer, it was covered with the polyimide insulating film of the second layer to obtain a three-layer wiring structure. . A schematic cross-sectional view of the three-layer wiring structure thus obtained is shown in FIG.

The three-layer wiring structure was dipped in a 5% potassium hydroxide aqueous solution for 40 minutes, and the adhesion between the polyimide insulating film and the substrate was examined. As a result, no peeling from the substrate was observed.

[0034]

According to the present invention, by covering the end surface of the substrate with the polyimide-based insulating film, it is possible to prevent the peeling from the substrate due to the decrease in the adhesiveness between the polyimide-based insulating film and the substrate. A multilayer wiring structure can be manufactured stably.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view showing an example of a multilayer wiring structure according to the present invention.

FIG. 2 is a schematic sectional view showing another example of a multilayer wiring structure according to the present invention.

FIG. 3 is a schematic cross-sectional view showing an example of a conventional multilayer wiring structure.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Substrate 2a First layer insulating film 2b Second layer insulating film 2c Third layer insulating film 3a First layer metal wiring 3b Second layer metal wiring 3c Third layer metal wiring 4 Opening with upper wiring (Connection hole) 5 End face of substrate

Claims (4)

[Claims] 1. A first-layer metal wiring formed on a substrate, a first-layer insulating film covering the first-layer metal wiring, and an opening formed in the first-layer insulating film. In a multilayer wiring structure including, as a minimum structural unit, a second-layer metal wiring connected to a first-layer metal wiring, at least a part of an upper end of an end face of the substrate is covered with an insulating film. A characteristic multilayer wiring structure. 2. The multilayer wiring structure according to claim 1, wherein at least a part of the end face of the substrate is covered with the insulating film of the first layer. 3. The multilayer wiring structure according to claim 1, wherein the substrate is a silicon substrate, and a silicon oxide layer is formed between the substrate and the metal wiring of the first layer. 4. The multilayer wiring structure according to claim 1, wherein the insulating film is a polyimide insulating film.