JPS60140734A - Multilayer interconnection structure and manufacture thereof - Google Patents

Abstract

PURPOSE:To obtain a multilayer interconnection structure having high reliability by a method wherein a first wiring conductor with a predetermined opening is applied on a semiconductor substrate and the first wiring conductor is coated with a thermosetting resin insulating film, a beam and radiation sensitive high-molecular material having plasma resistance shown by a specific formula is formed on the insulating film, a through-hole from which the prescribed section of the first wiring conductor is exposed is bored to the high-molecular material and a second wiring conductor having a predetermined pattern is buried into the through-hole. CONSTITUTION:An Al first conductor layer 2 having a prescribed pattern is formed on the surface of an Si substrate 1, and a thermosetting resin film 3 consisting of polyimide resin, etc. is applied on the whole surface by using a spinner while burying 21 shaped to the layer 2. A high-molecular material 51 having plasma resistance and high sensitivity to beams and radiation shown by formula having Si-Sin bonds is applied on the film 3, through-holes 52 are bored to the material 51 and the film 3 through plasma etching, and second wiring layers 6 are shaped to the exposed conductor layer 2. Accordingly, cracks, pin holes, etc. are not generated even when the layer thickness of the material 51 is thinned, and a fine pattern is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a multilayer wiring structure and a method for manufacturing the same. This type of wiring structure is used in fields such as VLSI, magnetic bubble memories, and thin film magnetic heads.

[Background of the invention]

As a conventional multilayer wiring structure of this type, there is a semiconductor device using a thermosetting resin such as $limide as an interlayer insulating film. In the case of such a semiconductor device, a window (
In order to install a through hole, the conventional method is to etch the resin insulating layer at a predetermined position using a well-known photo-etching method, and then remove the resin insulating layer by etching with a specific organic solvent. . However, as a result of etching with an organic solvent in this method, the resist used at this time is required to have properties that do not change at all even when immersed in such an etching solvent. Therefore, in the conventional method (wet method), there is an unavoidable problem that there are restrictions on the resists that can be used.

On the other hand, in recent years, for the purpose of increasing the density and integration of semiconductor elements, integrated circuits, etc., it has become necessary to form fine patterns, such as /4' turns with a submicron width.

Further, in order to compensate for the step shape that occurs due to the multilayering of wiring conductors, the interlayer insulating film has a thickness distribution depending on its position. This is because the difference in height is eliminated by forming a thick insulating layer in the portion that is lowered due to the difference in height. Therefore,
When drilling holes in interlayer insulating films, it is necessary to drill deep holes in some thick parts of the insulating film, so this is accompanied by a demand for higher accuracy in pattern etching.

Drilling methods with a higher aspect ratio than conventional methods and highly precise drilling methods that can drill deep holes with a uniform diameter all the way to the bottom have become essential.

In order to meet the above requirements, a dry etching process using discharge plasma or the like is being actively studied as a processing method for interlayer insulating films in place of the conventional wet method.

This is because when discharge plasma is used, there is no problem of resist limitations associated with the wet method, and even deep holes can be precisely and easily opened. The process shown in FIGS. 1A-F is an example. The structure of FIG. 1A will be explained. First, an insulating film is formed using a thermosetting resin (for example, polyimide) on the surface of a substrate 1 having a first wiring conductor 2 having a predetermined exposed portion, and then an insulating film is formed using an inorganic material that is resistant to oxygen plasma. An inorganic film 4 is formed using the inorganic film 4, and a light- and radiation-sensitive polymer material is further applied thereon to form a sensitive film 5. Inorganic films are usually obtained by plasma C■ or SOG (S
(p In on glass ass) to obtain a film with properties close to 5tO2, or M.

2 is obtained by forming a metal film such as.

The etching process will now begin, and the process consists of forming a predetermined pattern on the layer 5 (light- and radiation-sensitive polymer film) in FIG. Then, using this resist layer as a mask, the inorganic layer 4 is etched to obtain the structure shown in FIG. 1C. Subsequently, the insulating layer 3 is etched nine times using oxygen plasma. At this time, the uppermost resist layer 5 is also etched at the same time, but the inorganic layer 4 is not etched at all, so that the structure shown in the first diagram is obtained.

Finally, only the inorganic layer 4 is selectively etched away to form the structure shown in FIG. 1E, and then a second wiring conductor 6 is formed by vapor deposition or sputtering. This results in the structure shown in FIG. 1F.

The problem with this process is that it requires a large number of steps and is unreliable. This problem is mainly caused by the inorganic film 4.
This is due to the use of That is, the use of the inorganic membrane 4
This tends to complicate the process and reduce reliability. First, the inorganic material 4 used here has a different coefficient of thermal expansion and other physical properties from the underlying organic insulating layer 3, so cracks, pinholes, etc. are likely to occur. Secondly, especially when a metal is used for the inorganic film 4, the process for removing the metal film after processing the insulating layer (D in Figure 1) is necessary.
to F), it may be difficult to select an etching solution that does not easily dissolve the first wiring conductor. Considering these circumstances,
Considering that the wiring of the device will be multilayered with three or more layers, by avoiding the use of the above-mentioned inorganic film, which involves extremely complicated processes such as film formation, processing, and removal, it is possible to easily and easily form the glabella insulating film. At present, highly reliable microfabrication technology is highly desired.

[Purpose of the invention]

An object of the present invention is to eliminate the drawbacks of the prior art described above, to provide a multilayer wiring structure having fine mother turns, high reliability, and excellent characteristics, and to be able to produce the structure with fewer steps. The object of the present invention is to provide an advantageous manufacturing method.

[Summary of the invention]

The present inventors believe that in order to achieve the above object, it is possible to use a film that has the properties of the fourth layer (inorganic layer) and the fifth layer (light- and radiation-sensitive polymer material) in FIG. The present invention was completed by focusing on the positive aspects. That is, the present invention uses a light- and radiation-sensitive polymer film that is resistant to discharge plasma as a film formed on a thermosetting resin insulating film. According to this, pattern formation by light or radiation and plasma etching can be performed in a single layer, making it unnecessary to use both a photosensitive film and an inorganic film as in the past. Therefore, the number of steps can be reduced. This is because the photosensitive film is made plasma resistant so that it can function as both photosensitive and a mask for plasma etching.

The sensitive film may be left as it is, or after removal, four turns of the wiring conductor may be further formed. For example, a typical material having heat resistance (plasma resistance) comparable to a film of ) can be used. This polymer material has high sensitivity to ultraviolet rays and radiation, and can be formed into holes and turns using well-known photolithography, electron beam, or soft X-ray lithography techniques, and patterned resist films can be It has extremely high resistance to oxygen plasma, and is characterized by almost no film loss even when exposed to oxygen plasma for a long time.

Furthermore, the heat resistance temperature of this polymeric material is 400°C, and when crosslinked by electron beam irradiation, it reaches 450°C, showing heat resistance comparable to that of conventional polyimide. The present invention can be realized by using a material like this material that is sensitive to light and radiation and has plasma resistance.

For example, a detailed explanation of the present invention according to the configuration illustrated in FIG. 2 will be as follows. In manufacturing the multilayer wiring board of the present invention, first, in a first step I, a thermosetting resin insulating film is insulated on the surface of the board 1, which has a first wiring conductor 2 having a predetermined exposed portion 21 formed thereon. A film 3 is formed. Next, in a second step (2), a light- and radiation-sensitive polymer film 51 resistant to discharge plasma is formed thereon. This state is shown in FIG. 2(a). Thereafter, in a third step (3), a predetermined portion is irradiated with light or radiation to remove unnecessary portions 52 of the light- and radiation-sensitive polymer film 51. At this point, the state becomes as shown in FIG.

Next, in the fourth step (3), at least a portion 31 of the lower thermosetting resin insulating film 3 is removed by plasma etching by utilizing the discharge plasma resistance of the remaining light- and radiation-sensitive polymer film 51. At least a portion 22 of the first wiring conductor is exposed. Here, illustrated (c)
It will be like this. Next, in the fifth process (3), the casing or the remaining light and radiation polymer film 51 is removed, and a predetermined layer is further coated on the exposed portion 22 of the first wiring conductor 2 and the thermosetting resin insulating film 3. A second wiring conductor layer 6 of the mother turn is formed. As a result, a structure as shown in the figure (d) can be obtained, and a multilayer wiring structure can be obtained.

In order to embody the present invention, the following embodiments can be adopted. First, on the surface of the substrate 1 having the first wiring conductor 2 with a predetermined exposed portion 21, an insulating layer 3 made of polyimide or the like is applied to a thickness of 2 to 3 μm, and baked to form a step shape on the substrate surface. After planarization, -81-(-S i 9-) is formed in the molecule as a second layer.

A photoresist layer 51 made of a polymeric material having a bond (where n represents an integer from 1 to 5) is 0.1 to 0.
．． It is coated to a thickness of 3 μm to form a two-layer structure (FIG. 2(a)). Next, the upper photoresist layer 51 is patterned using the well-known IJ lithography technique (FIG. 2(b)). Using this as a mask, the lower polyimide layer 3 is dry-etched using oxygen plasma to form a predetermined pattern shape. A glabellar insulating film is obtained (second
Figure (C)). On the other hand, a second wiring conductor is deposited,
A multilayer wiring structure can be manufactured (see (d) in Figure 2).
)).

As the thermosetting resin insulating film 3, for example, polyimide resin, phenol resin, epoxy resin, etc. can be used, or a combination of two or more of these resins may be used.

Further, as the material of the wiring conductor, aluminum, molybdenum, nickel, copper, platinum, titanium, etc. may be used, or an alloy of two or more of these may be used.

As mentioned above, the present invention has the following advantages: (1) The resist layer (51 in FIG. 2) can be made thinner, and there is no need to use two layers as in the conventional method, making it possible to form extremely fine patterns. It is possible to do so.

(2) Lower layer (3 in Figure 2) and upper layer (51 in Figure 2)
) can be made into a material with good affinity.

For example, if both can be made of organic polymer materials, they will have good affinity with each other and have similar physical properties such as thermal expansion coefficients, so cracks and pinholes will not occur in the resist layer.
Therefore, the yield is increased. This is an effect that could not be expected at all with conventional techniques that had to use inorganic membranes.

(3) Since the resist layer (51 in FIG. 2) has plasma resistance, it can be used as it is as a heat-resistant insulating film, and the manufacturing process can be significantly shortened. In addition, high heat resistance can generally be expected. In addition, by using a material having a StMo S''j-n j 1% i ratio, it has good turn-forming ability and can be used as an advantageous film having properties such as plasma resistance and high heat resistance.

Next, materials that can be used in carrying out the present invention will be explained. The light- and radiation-sensitive organic polymer material used as the upper resist material has the general formula (where n represents an integer from 1 to 5: R+.

A polymer whose main component is a repeating unit represented by R2, R3* (R4 is a monovalent organic group; R' is a divalent organic group) can be used.

R1, R2, Rs, and R4 in the above general formula are monovalent organic groups, and specific examples thereof include alkyl groups such as methyl group and ethyl group, and aryl groups such as phenyl group.
+R2 and R3+R4 may all be the same organic group, or may be different organic groups.

In the above general formula, R' is a divalent organic group, specifically: (A) a divalent organic group consisting only of an aromatic ring structure; (B) a divalent organic group having an aromatic ring structure and a chain structure; Organic group: (C) alkylene group; or (D) divalent organic group containing a heteroatom;
- etc.; (C) is CH2CH2-1CH2CH2CH
2- etc.; (D) is -@)-osha, (shi802(瀘,-
□ Combined SO2%o-1-o -@o %o-5-〇sha5(
)0- etc.

Note that it is also possible to use 2o compounds in which the aromatic ring contained in the above-mentioned organic group is substituted with one or more nologon atoms, alkyl groups, etc. For example, the following various methods can be used to synthesize the materials used in carrying out the present invention.

(a) It has -81 (-8i+, bond (however, n represents an integer from 1 to 5) in the molecule, and s 1- at both ends.
Dichlorosilane compound with ct bond and Mg at both ends
A method of polycondensing a Grignard reagent having an X group (X represents Ct or Br).

(b) -81 (Si+-n bond (however, n
represents an integer from 1 to 5), a 5i-ct group at one end of the molecule, and a lithium atom at the other end. (However, n is 1
(representing an integer up to 5), with 5t-ct at both ends
A method in which a dichlorosilane compound having a bond and a dilithium compound having L1 atoms at both ends are used as a condensation polymerization source.

(d) −81 and 81+ bonds in the molecule (where n is 1
(representing an integer from 5 to 5) and having anilino groups at both ends, ie, a method of polycondensing a compound and an aromatic diol.

The light- and radiation-sensitive organic polymer materials exemplified above are:
When these materials are used for microfabrication of interlayer insulating films, e.g. ebuluene, xylene, mesitylene, p-cymene, etc. A solution of the above-mentioned polymer in an aromatic solvent is used.The above-described polymer solution (resist solution) is spin-coated onto an element substrate, and prebaked under appropriate temperature conditions.

[Embodiments of the invention]

The present invention will be explained in more detail below by describing some specific synthesis examples and examples.

First, a synthesis example for obtaining a light- and radiation-sensitive polymer will be explained.

Synthesis Example 1 () Synthesis of mother bis(methylphenylethoxysilyl)benzene [1]) Methylphenyldiethoxysila/123 was placed in a 500 mt three-necked flask equipped with a stirrer, a cooler, and a dropping funnel.
F, magnesium 14 f and tetrahydrofuran 100
mt, stir, and drop into a dropping funnel under a nitrogen stream.
A solution of 100 mt of dibromobenzene fi9 t in tetrahydrofuran was added dropwise over about 3 hours. After the dropwise addition, the mixture was further refluxed for about 5 hours while stirring. After refluxing, the solvent was distilled off and distilled under reduced pressure to obtain para-bis(methylphenylethoxysilyl)benzene 93f (yield near 8.
%) (boiling point: 213-215°C/3 Hf) was obtained.

[1] NMR spectrum (cct4) δ (ppm)
: 0.76 (3H,s, Me-8i), 1.36 (
3H, t, CH3-C).

3.94 (2H, q, CH2-C), 7.4
~7.8 (7H, m, ringprotons
) Synthesis of Synthesis Example 2 () and Larbis(chloromethylphenylsilyl)benzene [2]) Refluxing 92t of para-bis(methylphenylethoxysilyl)benzene obtained in Synthesis Example 1 and 250f of acetyl chloride for about 5 hours. Para-bis(chloromethylphenylsilyl)benzene 82f (boiling point: 229-232'c/3III+1Hf) was obtained with a yield of 94%.

[2] NMIt spectrum (CC44) δ (ppm)
: 1.00 (3H, 1I, Me-81), 7.5-7
．． 8(7H,m, ringprotons) Synthesis example a, (poly(cysilanylenephenylene):PDS
Synthesis of P) In a 300 mt three-necked flask equipped with a stirrer, a condenser, and a dropping funnel, the No.9 obtained in Synthesis Example 2 was added to about 100 ml of a toluene solution containing sodium 5F under a nitrogen stream. Lavis (chloromethylphenylsilyl)
100 ml of a benzene m solution containing 15 f of benzene was slowly added dropwise, and the mixture was refluxed at 70 to 80°C for about 5 hours. After heating, the obtained polymer was mixed with benzene-ethanol (1:
1 by vot) solution to obtain a white powder of the polymer with a yield of about 65%.

The properties and instrumental analysis results of the obtained polymer are shown below.

Melting point: 155-163°C Number average molecular weight: 34.00O NMR spectrum (C6D6) δ (ppm): o, 64
(3H,!1.

Me-3i), 7.26 and 7.30 (
7H, ring protons) IR spectrum:
3080.3060.2980.1435.1385
.

1260.1130.1110.1001000a Spectrum: λmax 270 nm Next, specific examples will be described.

Example 1 A first conductor layer 2 having a predetermined pattern was formed using a well-known IJ nography technique using an N+ conductivity type silicon wafer for the substrate 1 in FIG. 2 and aluminum for the first conductor layer. did.

Next, polyimide resin, which is a thermosetting resin (in this example,
PIQ (manufactured by Hitachi Chemical Co., Ltd.) was applied. Here, spin coating was performed on the substrate at a rotation speed of 2000 to 6000 rpm.

This was sequentially heated at 200° C. and 360° C. for 9 minutes each to cure the resin, thereby obtaining an insulating film 3.

Next, as a light and radiation sensitive polymer, 5
A photoresist having an i(St+ bond) was applied. In this example, a new photoresist, P
DSP P-cymene solution at 1000-2000 rpm
Spin coated. Thereafter, the photoresist layer 51 was formed by heating at 80 to 100° C. for I minutes.

Subsequently, a /4' turn was formed in the photoresist layer 51 by a well-known photolithography technique.

That is, contact exposure was performed through a predetermined master turn mask. The exposure amount is λ=254, taking into account the resist sensitivity of this example (400 mJ/crn2 at λ-254 city).
520 mJAm2 in mm. Note that the light source intensity in this example is 1.3 mW/at λ=254 mm.
It was 3”.

Next, it is developed with a prescribed developer (in this example, a mixed solvent of inzolobyl alcohol and toluene (volume ratio 5:1)), and then with a prescribed rinsing liquid (in this example, isozolobil alcohol).
Washed with

The resolution of the resist pattern thus obtained reached a maximum of 05 μm.

Next, in this example, the sample was exposed to oxygen plasma, and the thermosetting resin film exposed in the through hole 52 was removed by reaction with the oxygen plasma.
p, plasma output -200W), a second layer on the thermosetting resin film
A window 31 (through hole) shown in Figure (c) was formed.

At this time, the remaining resist film (51 in FIG. 2) hardly decreases.

Next, before depositing the second conductor layer 6, the remaining resist film can be removed (immersed in toluene at 60°C for 5 minutes), but even if it is not removed, it will not have any negative effect on the device characteristics. This has been confirmed. In addition, if the remaining resist film is irradiated with an electron beam shower to cause significant crosslinking, the heat resistance can be increased to 450.
This is even more convenient since it reaches temperatures above ℃.

Subsequently, if necessary, the first layer conductor aluminum surface 22 exposed to the window 31 (through hole) is cleaned with a phosphoric acid-containing solution or lightly etched with a halogen-based glazma, and then aluminum is vapor-deposited. did. Thereafter, using a well-known photolithography technique, a second conductor part 6 was formed which was electrically connected to the first conductor layer 2 at a window 31 (through hole) formed at a predetermined position.

As is clear from the above description, by using the two-layer structure insulating film of the present invention, an extremely fine insulating film pattern can be easily obtained. For example, it is easy to form an insulating film i4 turn having a high aspect ratio with a groove width of 7 μm and a depth of about 38° C.

〔Effect of the invention〕

As is clear from the above description, the present invention greatly simplifies the microfabrication process of interlayer insulating films in various multilayer wiring structures, which is extremely advantageous. In addition, since there is no need to use two layers, it is possible to process using an extremely thin resist layer, and essentially ultra-fine processing dimensions can be achieved, which will greatly improve the integration and functionality of semiconductor devices. effective.

It should be noted that, as a matter of course, the present invention does not apply to the above-described embodiments and
The present invention is not limited to the synthetic example or the illustrated structural example.

[Brief explanation of the drawing]

FIG. 1 shows a conventional manufacturing process for a multilayer wiring structure. FIG. 2 is a process diagram for explaining the present invention in detail, and is applicable to the embodiments of the present invention. DESCRIPTION OF SYMBOLS 1... Substrate, 2... First wiring conductor, 3... Thermosetting resin insulating film, 31... Through hole, 51... Light and radiation sensitive polymer material with plasma resistance ,6
...Second wiring conductor. Agent Patent Attorney Tadashi Akimoto Figure 1 Figure 2

Claims (1)

[Claims] (1) A first wiring conductor having a predetermined exposed portion is formed on the substrate surface, a thermosetting resin insulating film is formed on this, and a thermosetting resin insulating film is further formed on this which is resistant to discharge plasma. A certain light- and radiation-sensitive polymer film is formed, and the light- and radiation-sensitive polymer film is provided with predetermined through holes by irradiation with light or radiation, and the thermosetting resin insulating film is formed with predetermined through holes. A through hole is formed by discharge plasma in at least a part of the position corresponding to the first wiring conductor, thereby forming a second wiring conductor in a predetermined pattern on the partially exposed surface of the first wiring conductor. A multilayer wiring structure made up of 2. The light- and radiation-sensitive polymer has the general formula (where n represents an integer from 1 to 5, R1+R2
+R3*R4 represents a monovalent organic group, and R' represents a divalent organic group. ) The multilayer wiring structure according to claim 1, wherein the multilayer wiring structure is an organosilicon polymer material having a repeating unit represented by: 3. The multilayer wiring structure according to claim 1 or 2, wherein the thermosetting resin insulating film is made of polyimide resin. 4 A first wiring conductor having a predetermined exposed portion is formed on the substrate surface, a thermosetting resin insulating film is formed on this, and this thermosetting resin insulating film is formed on the insulating film. By irradiating light or radiation to a light- and radiation-sensitive polymer film that is resistant to discharge plasma to provide a predetermined through hole, at least a portion of the position corresponding to the through hole is formed. A through hole is formed by discharge plasma, thereby exposing a part of the first wiring conductor, and further forming a predetermined layer on the surface from which the light and radiation green photosensitive polymer film has been previously removed. second pattern
A multilayer wiring structure formed by forming wiring conductors. 5. The light- and radiation-sensitive polymer has the general formula (where n represents an integer from 1 to 5, R1°R2
+R3 and R4 represent a monovalent organic group, and R' represents a divalent organic group. ) The multilayer wiring structure according to claim 1, wherein the multilayer wiring structure is an organosilicon polymer material having a repeating unit represented by: 6. Claim 4, wherein the thermosetting resin insulating film is made of polyimide resin.
6. The multilayer wiring structure according to item 5. 7. Forming a thermosetting resin insulating film on the surface of the substrate on which the first wiring conductor having a predetermined exposed portion is formed, and forming a light- and radiation-sensitive polymer film resistant to light. Alternatively, a step of irradiating a predetermined portion with radiation to remove unnecessary portions of the light- and radiation-sensitive polymer film, and utilizing the discharge glazma resistance of the remaining light- and radiation-sensitive polymer film to removing at least a portion of the thermosetting resin insulating film by plasma etching, thereby exposing at least a portion of the first wiring conductor;
A step of forming a second wiring conductor layer of a predetermined /e turn on the exposed portion of the first wiring conductor and the thermosetting resin insulating film by removing the remaining light and radiation polymer film as it is or by removing the remaining light and radiation polymer film. A method for manufacturing a multilayer wiring structure, comprising: 8. The light and radiation sensitive polymer has the general formula (where n represents an integer from 1 to 5 and -R11R2
rR3 and R4 represent a monovalent organic group, and R' represents a divalent organic group. ) The method for manufacturing a multilayer wiring structure according to claim 7, wherein the organic silicon polymer material has a repeating unit represented by the following formula. 9. The method of manufacturing a multilayer wiring structure according to claim 7 or 8, wherein the thermosetting resin insulating film is made of polyimide resin.