JPH07283544A - Wiring structure and its manufacturing method - Google Patents

Abstract

PURPOSE:To improve reliability and to reduce cost by forming an insulation film which is made of a not heat-curable polymeric material and has a weight reduction rate within a specific range. CONSTITUTION:At least any one of polyamide material, polyamideimide material, polysulfon material, polyethersulfon material, and polyetherimide material can be used as insulation materials. Then, an insulation film 33 on a conductor 32 formed by them has a weight reduction rate of 5% or less per hour at 300 deg.C. Namely, these materials for insulating the wiring of a multilayer wiring structure body can be formed at 250 deg.C or lower, thus reducing the temperature for forming the insulation film.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a wiring structure in which wiring and insulating film are alternately laminated, and
The present invention relates to a wiring structure characterized by being an organic polymer material that can be formed at a temperature of 50 ° C. or less. The insulating material is formed at a low temperature, the wiring material is less damaged, the manufacturing time is short, and the cost is low. And a highly integrated mounting board, and manufacturing methods thereof.

[0002]

2. Description of the Related Art In recent years, wiring boards for mounting LSIs have become multi-layered, highly integrated, and have high performance, and thin-film wiring formed by thin-film technology is becoming more important. Polyimide is widely used as one of the insulating materials for the thin film wiring.

[0003]

Polyimide is produced by subjecting a diamine component and a tetracarboxylic dianhydride component to a polymerization reaction in an organic solvent to produce a polyimide precursor (polyamic acid), which is dehydrated and cyclized by heating or the like. It is obtained by the method of making. A mounting board manufactured by forming an insulating film of a thin film wiring by this method has been widely known in the past (eg, Microelectronics Packaging Handbook, Rao R. Tummala, Eugene J. Rymazewski.
Author, Nikkei BP, March 1991, p554, p56
2). The heating temperature for forming this polyimide usually reaches a high temperature of 350 to 450 ° C. Therefore, the temperature rise time and heating time during the mounting board manufacturing process are long, and it is necessary to cool to a temperature of 200 ° C. or lower before removal from the heating furnace in order to avoid substrate damage due to rapid cooling, and the precooling time is long. There was a problem such as. Also, especially when the wiring material is difficult to form a strong oxide film on the surface such as copper and is easily damaged by heat or oxygen, an expensive reducing gas of argon and hydrogen is used as an atmosphere during heating, There has been a problem that it is necessary to use a nitrogen gas stream having an extremely low oxygen and further to provide a barrier metal for protecting the copper surface.

In view of the problems of the present situation, the present inventors have
The insulating film formation temperature can be reduced, the heating time and the pre-cooling time before taking out the substrate are short, and there is no reactivity with the wiring material, reducing gas is used, or nitrogen with extremely low oxygen is used. Searching for an insulating material that does not require the use of an air flow or further providing a barrier metal for protecting the copper surface, and using this material, the adhesiveness between the insulating film and the substrate and wiring material is excellent, The present invention has been achieved as a result of intensive studies for the purpose of realizing a low-cost wiring structure having high reliability as a whole wiring board and a manufacturing method thereof.

[0005]

The present invention relates to a wiring structure in which the material for insulating the wiring of the multilayer wiring structure is an organic polymer material which can be formed at a temperature of 250 ° C. or lower. Examples of the insulating material include polyamide-based materials, polyamide-imide-based materials, polysulfone-based materials, polyether sulfone-based materials, and polyetherimide-based materials, and at least one of these can be used.

Here, as the polyamide-based material (Chemical formula 1), as the polyamide-imide-based material (Chemical formula 2), as the polysulfone-based material (Chemical formula 3), as the polyether sulfone-based material (Chemical formula 4), Examples of the polyetherimide-based material include materials having the structure of (Chemical Formula 5), which are preferably used.

[0007]

[Chemical 1]

[0008]

[Chemical 2]

[0009]

[Chemical 3]

[0010]

[Chemical 4]

[0011]

[Chemical 5]

Further, when the number of thin film layers of the wiring structure to be manufactured is large and the total film thickness is as thick as 100 μm or more, the stress due to the mismatch of the coefficient of thermal expansion between the substrate and the thin film layer is caused. In some cases, the problem that the thin film layer peels from the substrate may occur. In order to avoid this problem, it is possible to reduce the coefficient of thermal expansion of the insulating material. In such a case, it is desired that the structure of the insulating material has the following structure in a limited manner. That is, here, as a polyamide-based material (chemical formula 6), as a polyamide-imide-based material (chemical formula 7), as a polysulfone-based material (chemical formula 8), as a polyether sulfone-based material (chemical formula 9), As the ether imide-based material, a material having a structure of (Chemical Formula 10) can be mentioned and is preferably used.

[0013]

[Chemical 6]

[0014]

[Chemical 7]

[0015]

[Chemical 8]

[0016]

[Chemical 9]

[0017]

[Chemical 10]

These are used both as a solution dissolved in a solvent and as a film, and can be formed at a temperature of 250 ° C. or lower, and the problems derived from the above-mentioned high forming temperature can be solved. That is, when manufacturing the wiring structure, the heating time and the pre-cooling time for taking out the substrate are short, and further, there is no reactivity with the wiring material and a reducing gas is used, or a nitrogen gas stream with extremely low oxygen is used. Or
Furthermore, it is not necessary to provide a barrier metal for protecting the copper surface. Therefore, a wiring structure having high reliability and low cost can be realized as compared with the conventional case where polyimide is formed as an insulating film from its precursor by heating.

When the wiring material is copper, the formation temperature of the insulating material is 250 ° C. or less, which gives a new advantage in the present invention. Oxidation of the copper surface becomes remarkable from about 200 ° C. in the atmosphere (for example, Analytical Chemistry, 54, p682 (198).
2)). Therefore, it is necessary to reduce the oxygen concentration in the atmosphere when forming the insulating material. However, in the present invention, it has been clarified that when the surface of the copper wiring is covered with the insulating material, the oxidation of the copper surface can be significantly suppressed even when the atmosphere is the atmosphere. Therefore, it becomes possible to raise the temperature when forming the insulating material to 250 ° C.

The method of manufacturing the wiring structure of the present invention will be described below.

The method of manufacturing the wiring structure of the present invention can be roughly divided into three cases according to the method of forming the wiring and the insulating film.

The first method is a method of forming a wiring by using an electroplating technique and forming a via wiring before forming an insulating film. This will be described with reference to FIG.

First, a plating base film 12 used as a plating electrode is formed on a substrate 11 (FIG. 1a) (FIG. 1b).
As the base film 12, all metal materials that can be easily etched can be mentioned, but it is preferable that the metal thickness is 3 μm or less, and for example, Cr and Cu or Ti and C are used.
It may have a two-layer structure like u. The base film 12 can be formed by any one of the sputtering method, the vapor deposition method, and the plating method. Next, a resist 13 is formed (FIG. 1c), exposed with a predetermined mask, developed (FIG. 1d), and copper-plated 14 by electroplating (FIG. 1e). Further, the process drawings 1c to 1e are repeated (process drawings 1f to 1h). Then, the resist 13 is stripped with a stripping solution (FIG. 1i), and then the portion of the plating base film 12 which is not the base of the subsequent copper plating is removed by etching (FIG. 1j). Here, it is possible to form a protective film of Ni or the like on the surface of the Cu wiring 14 for the purpose of improving reliability (FIG. 1k), but this is not essential in the present invention. Then, the above-mentioned insulating material is applied in the form of a solution or a film, heated at 250 ° C. or lower, and if necessary kept under pressure or reduced pressure to form the insulating layer 16 (FIG. 11). Next, the insulating layer is flattened by mechanical grinding or polishing, and the top of the Cu wiring is found (FIG. 1m). To form multilayer wiring,
Further, the above-described FIGS. 1b to 1m are repeated for a desired number of steps to obtain a desired structure.

The second method is to form a wiring by using a technique of sputtering, vapor deposition or plating before forming an insulating film, then form a via wiring by a plating method, and then form a pattern on the underlying wiring. It is a method of forming. This will be described with reference to FIG.

A metal layer 22 for securing adhesion to the substrate and a wiring layer 23 are formed on the substrate 21 (FIG. 2a) (FIG. 2b). As the metal layer 22, for example, Al or C
r, Mo, W, Ti, etc., and A for the wiring layer 23
1, Cu, etc. are mentioned, but not limited thereto. Alternatively, the wiring layer 23 may be directly formed on the substrate 21 without forming the metal layer 22. The metal layer 22 can be formed by a sputtering method or an evaporation method, and the wiring layer 23 can be formed by a plating method in addition to the sputtering method or the evaporation method. Then, a resist 24 is formed (FIG. 2c),
After exposure with a predetermined mask, development is performed (FIG. 2d), and copper plating 25 serving as vias is applied by electroplating (FIG. 2e).
Next, the resist 24 is once peeled off (FIG. 2f), and the resist 24 is formed again so as to completely cover the copper plating 25 (FIG. 2g). Next, the resist 24 is exposed and developed to form a pattern on the resist 24 (FIG. 2h), and then the wiring layer 23 and the metal layer 22 are etched to form a pattern (FIG. 2i). Then, after removing the resist 24 (FIG. 2 j), it is possible to form a protective film such as Ni on the surfaces of the wiring 23 and the copper plating 25 for the purpose of improving reliability. Then, the above-mentioned insulating material is applied in the form of a solution or a film, heated at 250 ° C. or lower, and if necessary, kept under pressure or under reduced pressure to form the insulating layer 26 (FIG. 2K). Then, the insulating layer is flattened by mechanical grinding or polishing, and the top of the Cu wiring is found (see FIG. 2).
l). In order to form the multi-layer wiring, the above-mentioned FIG.
By repeating k for a desired number of steps, the desired structure can be obtained.

A third method is a method of forming an insulating film on the wiring formed in a pattern, forming a via hole in the insulating film, and then forming an upper wiring. This will be described with reference to FIG.

First, the conductor layer 32 having a predetermined pattern is formed on the substrate 31 by a well-known photo-etching technique, and then the above-mentioned insulating material is applied in the form of a solution or film, heated at 250 ° C. or lower, and if necessary. And pressurization or depressurization is performed to form the insulating layer 33 (FIG. 3a). As the conductor layer 32, Al, Cr, Ti, Ni, Cu, M
One or more of O, W, etc. can be used, and the sputtering method,
It can be formed by either a vapor deposition method or a plating method. Next, a photoresist 34 is applied on the insulating layer 33 and dried (FIG. 3b). The photoresist 34 is exposed by using a predetermined photomask, developed and the like to obtain a predetermined pattern (FIG. 3c). Then, the insulating layer 33 is formed by using the photoresist pattern as a mask.
A predetermined portion is selectively removed by etching using an etching solution that dissolves the metal to form a via hole 35, and the conductor layer 32 in this portion is exposed (FIG. 3d). After that, the photoresist 34 is removed with a resist remover (see FIG. 3).
e). Here, if the processing of the via hole 35 of the insulating layer 33 is performed using a laser beam such as an excimer laser, the process using the photoresist 34 of FIGS. 3B to 1D can be omitted. When the insulating layer 33 is used as a surface protective film, this via hole is used as a solder connecting portion in order to obtain electrical conduction with the outside of the substrate such as an LSI. When forming a multilayer wiring structure, the conductor layer 32
As the lower conductor layer, and the upper conductor layer 36 is further formed on the wiring layer formed as described above. That is, the upper conductor layer 3
6 is deposited on the entire surface of the substrate by a method such as a vacuum evaporation method, a sputtering method or a plating method, and the via hole 3 of the lower conductor layer 32 and the insulating layer 33 is formed by a well-known photo etching technique or the like.
The two-layer wiring structure is formed by forming a predetermined pattern electrically connected at the portion 5 (FIG. 3f). Further, by repeating this operation a number of times, a multilayer wiring structure having three or more layers is formed.

[0028]

According to the present invention, since the formation temperature of the insulating film can be reduced, the heating time and the precooling time before taking out the substrate are short, and further, there is no reactivity with the wiring material, and the insulating film is formed. Sometimes it is not necessary to use a reducing gas or a nitrogen stream of extremely low oxygen, and it is not necessary to provide a barrier metal to protect the copper surface, making the wiring board as a whole highly reliable. It becomes possible to realize a low-cost wiring structure and its manufacturing method.

This is because a material such as polyimide, which can be formed at a low temperature of 250 ° C. or lower, rather than a high temperature of 350 to 450 ° C., is used as the insulating material. Examples of materials that can be used as the insulating material in the present invention are already solid. These can be formed at a temperature that evaporates the solvent when applied and formed as a solution dissolved in some solvent, and when formed as a film on wiring, it is heated up to near the softening point of the material. It can be formed by It is sufficient for all of them to have a temperature of 250 ° C. or lower. Further, by coating the wiring with the insulating material at the low formation temperature, it is possible to suppress the damage to the wiring even when the wiring material is a material such as copper which is hard to form a strong surface oxide film. As a result, it has become possible to realize a highly reliable and low cost wiring structure and its manufacturing method.

[0030]

EXAMPLES Next, the present invention will be described with reference to examples.

In the following examples or comparative examples, the materials shown in Table 1 were used as the insulating material.

(Embodiment 1) FIG. 1 shows a manufacturing process of a multilayer wiring structure manufactured according to this embodiment. A mullite ceramic substrate 11 having a tungsten wiring inside (see FIG. 1).
a, 127 mm square, 3 mm thick) is formed on the tungsten wiring upper part as a plating base film 12 by a sputtering method.
(Film thickness of 0.05 μm) and Cu (0.7 μm) were sequentially formed (b). Next, the positive type resist 13 was spin-coated and heated in a nitrogen atmosphere at 90 ° C. for 30 minutes. The film thickness of the resist 13 at this time was 5 μm (c). Next, after exposure, development and rinsing with a predetermined mask (d), copper plating 14 was performed by electroplating (e). Plating solution composition is C
uSO ₄ / 5H ₂ O 70 g / l, H ₂ SO ₄ 140 g /
1, HCl 50 ppm, current density 1.0 (A / dm
² ), and the time required to obtain 5 μm thick copper is 20
It was a minute. After completion of copper plating, wash with water and dry at 80 ° C,
It was carried out for 30 minutes. Furthermore, the above process drawings 1 (c) to (e)
Was repeated (process drawings (f) to (h)). At this time, the thickness of the upper resist is set to 20 μm, and Cu that becomes the via wiring is formed.
Was formed to a thickness of 20 μm by setting the plating time to 80 minutes. Then, the resist 13 was peeled off with a peeling solution (i) and then washed with an alcoholic organic solvent. Next, of the copper and chromium that are the plating base film 12, the portions that are not the base of the subsequent copper plating are selectively removed with an ammonium chloride-based etching solution and a potassium ferricyanide / sodium hydroxide mixture solution (j ). Next, after washing with water, washing with an alcoholic organic solvent, and drying, the material of No. 1 in Table 1 is spin-coated, put into a heating furnace at 120 ° C, heated at 5 ° C per minute, and after reaching 240 ° C, further. Thirty
After holding for a minute to form the insulating layer 16, the temperature was lowered to 200 ° C. or lower and the product was taken out of the furnace (FIG. 11). Then, the insulating layer 16 was planarized by polishing with a tape (# 500 to # 4000) to which alumina particles were adhered, the insulating layer had a thickness of 25 μm, and washed with acetone (m). Furthermore, the above process diagram (b)
(M) was repeated 4 times to obtain a multilayer wiring structure including 5 wiring layers as shown in FIG. In the multilayer wiring structure completed as described above, there were no voids, peeling, cracks or the like near the interface between Cu and polyimide, and good electrical continuity was obtained over all wirings.

(Examples 2 to 6)

[0034]

[Table 1]

A multilayer wiring structure having 5 wiring layers was obtained by the same method as in Example 1 except that Nos. 2 to 6 in Table 1 were used as the insulating material. In the completed multilayer wiring structure, there were no voids, peeling, cracks, etc. near the interface between Cu and the insulating layer, and good electrical continuity was obtained over all wirings.

Comparative Example

[0037]

[Table 2]

The polyimide precursors in Table 2 were synthesized by polymerizing them in the solvents shown in the table and further heating them to reduce and adjust the viscosity of the solution.

(Comparative Example 1) As a material of the insulating layer 16, Table 2
No. 7 polyimide precursor varnish was used, and a multilayer wiring structure was manufactured in the same manner as in Example 1 except that the heating temperature at the time of forming the insulating layer was 350 ° C. instead of 240 ° C. As a result, the No. 7 polyimide precursor was applied on the Cu of the first wiring and then heated at 350 ° C. for 60 minutes (see FIG.
When the multilayer wiring structure in (l)) was observed with a microscope, the peripheral portion of the Cu wiring in the polyimide was discolored greenish brown. Next, a second layer of polyimide is formed to increase the film thickness and heated at 350 ° C. for 60 minutes (see FIG.
When the multilayer wiring structure was observed again with a microscope in (l)), blister was observed between the upper layer polyimide and the lower layer polyimide. After this, when the polyimide was further flattened by tape polishing (FIG. 1 (m)), a groove was formed between the polyimide and Cu and peeling was observed. This is because after a large amount of Cu was eluted into the polyimide, 350 ° C
It is considered that, since the polyimide film was exposed to the high temperature, the part of the polyimide film centering on the interface with Cu was decomposed and the adhesion at the interface was lowered.

Comparative Example 2 As a material of the insulating layer 16, Table 2
No. 8 polyimide precursor varnish was used, and a multilayer wiring structure was manufactured in the same manner as in Example 1 except that the heating temperature at the time of forming the insulating layer was 400 ° C. instead of 240 ° C. As a result, the No. 8 polyimide precursor was applied on the Cu of the first wiring and then heated at 400 ° C. for 60 minutes (see FIG.
When the multilayer wiring structure in (l)) was observed with a microscope, the peripheral portion of the Cu wiring in the polyimide was discolored greenish brown. Then, a second layer of polyimide is formed to increase the film thickness and heated at 400 ° C. for 60 minutes (see FIG.
When the multilayer wiring structure was observed again with a microscope in (l)), blister was observed between the upper layer polyimide and the lower layer polyimide. After that, when the polyimide was further flattened by tape polishing (FIG. 1 (m)), a groove was formed between the polyimide and Cu, peeling was observed, and C
A crack was generated in the planar direction around the u via. This is 350 after elution of a large amount of Cu into the polyimide.
It is considered that, because the polyimide film was exposed to a high temperature of ° C, a part of the polyimide film was decomposed, the adhesion was decreased, the elongation of the polyimide film was decreased, and the film stress could not be resisted, resulting in cracking.

[0041]

As described in the above examples and comparative examples, according to the present invention, since the formation temperature of the insulating film can be reduced, the heating time and the precooling time before taking out the substrate are shortened. Furthermore, there is no reactivity with the wiring material, there is no need to use a reducing gas when forming an insulating film, or to use a nitrogen gas stream with extremely low oxygen, and a barrier metal for protecting the copper surface is used. It is possible to provide a wiring structure having high reliability and low cost as a whole wiring board and a method for manufacturing the wiring structure without having to provide the wiring structure.

[Brief description of drawings]

FIG. 1 is a diagram showing an example of a manufacturing process of a multilayer wiring structure according to the present invention.

FIG. 2 is a diagram showing an example of a manufacturing process of a multilayer wiring structure according to the present invention.

FIG. 3 is a diagram showing an example of a manufacturing process of a multilayer wiring structure according to the present invention.

FIG. 4 is a diagram showing an example of a multilayer wiring structure manufactured according to the present invention.

[Explanation of symbols]

11 ... Ceramic substrate, 12 ... Underlayer, 13 ... Photoresist, 14 ... Plated copper, 15 ... Wiring protective film, 16 ... Insulating layer, 21 ... Substrate, 22 ... Wiring underlayer, 23 ... Wiring layer,
24 ... Photoresist, 25 ... Plated copper, 26 ... Insulating layer, 31 ... Substrate, 32 ... Conductor layer, 33 ... Insulating layer, 34 ...
Photoresist, 35 ... Via hole, 36 ... Upper conductor layer.

Continuation of front page (51) Int.Cl. ⁶ Identification number Office reference number FI Technical display location C08L 77/10 LQR 81/06 LRF H05K 3/28 C (72) Inventor Hideo Arima Yoshida Totsuka-ku, Yokohama-shi, Kanagawa 292, Machi Co., Ltd., Hitachi, Ltd.

Claims (13)

[Claims] 1. A wiring structure in which an insulating film is laminated on a conductor, wherein the insulating film is a non-thermosetting polymer material, and the weight reduction rate of the insulating film at 300 ° C. is 5% or less per hour. A wiring structure characterized by: 2. In a multi-layer wiring structure in which wiring and insulating films are alternately laminated, the insulating film is a non-thermosetting polymer material, and the weight reduction rate of the insulating film at 300 ° C. is 5 per hour. % Or less and the coefficient of thermal expansion is 3 to 20 × 10 to ⁶ /
K range and Young's modulus of 200 to 500 kgf /
A multilayer wiring structure characterized by having a range of mm ² . 3. The insulating film material according to claim 1 or 2, wherein the insulating film material is at least one of a polyamide-based material, a polyamide-imide-based material, a polysulfone-based material, a polyether sulfone-based material, or a polyetherimide-based material. The wiring structure according to claim 1 or 2, wherein 4. The wiring structure according to claim 2, wherein the polyamide-based material according to claim 3 has a structure represented by the following (Chemical formula 1). [Chemical 1] 5. The wiring structure according to claim 2, wherein the polyamide-imide-based material according to claim 3 has a structure represented by the following (Chemical formula 2). [Chemical 2] 6. The wiring structure according to claim 2, wherein the polysulfone-based material according to claim 3 has a structure represented by the following (Chemical Formula 3). [Chemical 3] 7. The wiring structure according to claim 2, wherein the polyether sulfone-based material according to claim 3 has a structure represented by the following (formula 4). [Chemical 4] 8. The wiring structure according to claim 2, wherein the polyetherimide-based material according to claim 3 has a structure represented by the following (formula 5). [Chemical 5] 9. The insulating film material according to claim 3, wherein the polyamide-based material is the following (Chemical formula 6), the polyamide-imide-based material is the following (Chemical formula 7), and the polysulfone-based material is the following (Chemical formula 8). 4. The wiring structure according to claim 3, wherein the polyether sulfone-based material has the following (Chemical formula 9) and the polyetherimide-based material has the following (Chemical formula 10). [Chemical 6] [Chemical 7] [Chemical 8] [Chemical 9] [Chemical 10] 10. A wiring characterized in that the insulating film of a wiring structure formed by laminating an insulating film on a conductor is non-thermosetting and is formed by the following steps (1) to (4). Structure manufacturing method. (1) a step of forming a conductor wiring in a pattern and a via, (2) a step of applying an insulating material as a solution containing a solvent, (3) heating the applied solution at a temperature of 250 ° C. or lower for insulation A step of forming a film, (4) a step of planarizing the insulating film by mechanical polishing. 11. A wiring characterized in that an insulating film of a wiring structure formed by laminating an insulating film on a conductor is non-thermosetting and is formed by the following steps (1) to (5). Structure manufacturing method. (1) A step of forming a conductor wiring in a pattern,
(2) applying an insulating material as a solution containing a solvent, (3) heating the applying solution at a temperature of 250 ° C. or lower to form an insulating film, (4) patterning a resist on the insulating film And forming a via hole in the insulating film by developing with a solvent that dissolves the insulating film,
(5) A step of peeling off the resist. 12. A wiring characterized in that an insulating film of a wiring structure formed by laminating an insulating film on a conductor is non-thermosetting and is formed by the following steps (1) to (3). Structure manufacturing method. (1) a step of forming a conductor wiring by forming a via with a pattern, (2) a step of thermocompression-bonding an insulating material on the conductor wiring in a film state at a temperature of 250 ° C. or lower, (3) an insulating film The process of flattening by mechanical polishing. 13. A wiring, wherein an insulating film of a wiring structure formed by laminating an insulating film on a conductor is non-thermosetting and is formed by the following steps (1) to (4). Structure manufacturing method. (1) A step of forming a conductor wiring in a pattern,
(2) Insulating material is applied in a film state on the conductor wiring.
Thermocompression bonding at a temperature of 0 ° C. or lower, (3) forming a resist on the insulating film in a pattern, and forming a via hole in the insulating film by developing with a solvent that dissolves the insulating film, (4) A step of peeling off the resist.