JP2000058537A - Manufacture of electronic device having organic resin- based insulating film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method by which an electronic device having such an organic resin-based insulating film that contains less low-molecular weight components and has a high degree of polymerization and a superior heat resistance can be manufactured by forming the insulating film, by polymerizing a gaseous material containing at least either one of an aromatic compound and a heterocyclic compound with a plasma. SOLUTION: After an interlayer insulating film 2 composed of SiO2, etc., and a line-and-space-patterned wiring layer 3 composed of an Al-based metal, etc., are formed on a semiconductor substrate composed of Si, etc., an organic resin-based insulating film 4 is formed on the substrate 1 to be treated. The insulating film 4 is formed by polymerizing a gaseous starting material containing an aromatic compound or heterocyclic compound with a plasma. Then, after a connecting hole 6 is formed, a barrier metal layer 7 composed of TiN and a metallic layer 8 composed of W are successively formed. Therefore, the heat resistance of the insulating film 4 can be improved, because the nonvolatile impurity contained in the film 4 can be removed sufficiently.

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 an electronic device having an organic resin-based insulating film, and more particularly, to a highly integrated semiconductor device using an organic resin-based insulating film having a low dielectric constant as an interlayer insulating film or the like. The present invention relates to a method for manufacturing an electronic device such as a device.

[0002]

2. Description of the Related Art ULSI (Ultra Large Scale Integrate)
As the degree of integration of semiconductor devices such as d circuits increases, the wiring width and the wiring pitch need to be finer. At the same time, in order to meet the demands for low power consumption and high operating speed of semiconductor devices, especially high-speed logic semiconductor devices, selection of interlayer insulating film material with low dielectric constant is an elemental technology. One of them is becoming more important. This is also an important problem in various high-frequency fine electronic devices other than semiconductor devices.

[0003] Insulating film materials conventionally used for interlayer insulating films of semiconductor devices and the like include SiO ₂ (dielectric constant 4), S
iON (relative permittivity 4 to 6) or Si ₃ N ₄ (relative permittivity 6)
And other inorganic materials. As a method of reducing the capacitance between wirings of a highly integrated semiconductor device, for example, Japanese Patent Application Laid-Open
As disclosed in Japanese Patent Publication No. 50, it is effective to use an interlayer insulating film made of a material having a lower dielectric constant than these general inorganic materials. Representative examples of the low dielectric constant material include an inorganic insulating film material such as a silicon oxide insulating film containing fluorine atoms (hereinafter, referred to as SiOF) and an organic insulating film material containing carbon atoms.

[0004] SiOF is Si-O constituting SiO _2.
By terminating the F atoms to -Si bonds, that the density decreases, and the Si-F bonds and that O-F bond polarizability is small or the like, a low dielectric constant can be achieved than SiO _2. Since this SiOF is similar in film formation and etching process to conventional SiO ₂ , it can be easily adopted even in a current production apparatus. Also, since it is an inorganic material, it has excellent heat resistance.

A method of forming a SiOF film is described in TEOS (Tetra
Ethyl Ortho Silicate) as a silicon source gas, and CVD (Ch
emical Vapor Deposition) method is used. Method using C ₂ F ₆ as a fluorine source gas (25th SSDM Proceedings, p. 161 (1993)), Method using NF ₃ (40th Federation of Applied Physics-related lectures (Spring Annual Meeting, 1993)) Proceedings of Lectures, p.495, Lecture Number 1a-ZV-
9) has been reported. However, these methods use Si
It has also been reported that as the content of fluorine in the OF increases, the film quality deteriorates, and accordingly, the hygroscopicity significantly deteriorates.

In order to stabilize the film quality, SiF ₄ is adopted as a gas containing both silicon and fluorine, and SiF ₄ /
Plasma CVD method using O ₂ mixed gas and dissociating it by high-density plasma to form a film (Proceedings of the 40th Joint Lecture Meeting on Applied Physics (Spring Annual Meeting, 1993), p.
752, lecture number 31p-ZV-1) has also been proposed. SiOF obtained by this method is excellent in embedding characteristics even when the underlying substrate to be processed has a step with a high aspect ratio.

[0007] SiOF by high-density plasma CVD of a mixed gas of SiF ₄ / O ₂ is used in a region of low concentration of fluorine.
Higher film quality stability than F is secured. However, SiOF containing a high concentration of fluorine generates a Si = F ₂ bond in addition to a Si—F bond and an OF bond, which causes a problem of increased hygroscopicity. When the amount of water in the SiOF increases, the filling characteristics of the metal layer and the like in the contact plug forming step and the like decrease. Therefore, it is reported that the relative dielectric constant of SiOF formed by this method is limited to about 3.8 from the viewpoint of hygroscopicity.

Accordingly, an organic resin-based insulating film has been proposed for further lowering the dielectric constant. As a method for forming an organic resin-based insulating film, for example, a method has been proposed in which a paraxylylene resin containing fluorine is vapor-phase grown by using both a thermal decomposition reaction and a thermal polymerization reaction of a dimer (dimer) source gas. (VLSI / ULSI Multilevel Interconnection Conference
p.207 (1996)). The organic resin-based insulating film obtained by this method has a low dielectric constant of about 2.3.
However, a vapor phase growth method using both a thermal decomposition reaction and a thermal polymerization reaction requires a special raw material compound, and also requires a special structure for a vapor phase growth apparatus, and is therefore less versatile.

As another method of forming an organic resin-based insulating film,
There is a method in which an organic resin synthesized in advance is dissolved in a solvent and a film is formed by a coating method. This method is simple and can form a film by a usual spin coater or the like. In addition, an insulating film having a relatively low relative dielectric constant can be formed by selecting an organic resin. However, it is difficult to completely prevent the incorporation of low molecular weight components formed simultaneously with the synthesis of the organic resin and the effect of the residual solvent. In particular, when applied to an interlayer insulating film of a semiconductor device, in a metallization process of interlayer connection, volatilization and thermal decomposition of low molecular weight components due to insufficient heat resistance,
Alternatively, outgas is generated by the residual solvent or the like, and the shape of the contact plug and the contact resistance are deteriorated.

[0010]

SUMMARY OF THE INVENTION The present invention has been made in view of such problems of the prior art. That is, an object of the present invention is to provide a method of manufacturing an electronic device having an organic resin-based insulating film having a low degree of polymerization and a high degree of polymerization and excellent heat resistance. Another object of the present invention is to provide a method for manufacturing an electronic device having an organic resin-based insulating film, which does not require a special source gas or a film forming apparatus for film formation.

[0011]

In order to achieve the above-mentioned object, a method for manufacturing an electronic device having an organic resin-based insulating film according to the present invention comprises forming an organic resin-based insulating film on a substrate to be processed by a plasma CVD method. A method for manufacturing an electronic device having a step of forming, wherein the organic resin-based insulating film is formed by plasma polymerizing a source gas containing at least one of an aromatic compound and a heterocyclic compound. It is characterized by.

This source gas preferably further contains an unsaturated hydrocarbon compound. Among the unsaturated hydrocarbon compounds, examples of the compound containing a double bond include ethylene, propylene, butylene, amylene and hexene. A compound having two double bonds, such as allene or hexadiene, may be used. Examples of the compound containing a triple bond include acetylene, allylene, and butyne. 3-pentene-1- containing both double and triple bonds
It may be a compound such as in.

The aromatic compound used in the present invention may be, in addition to benzene, a ring condensate of a benzene ring, a ring assembly of a benzene ring, or at least one of an alkyl group, an alkylene group, a carboxyl group, a hydroxyl group and an amino group. It is desirable to use benzenes or naphthalenes having any one kind of substituent, but the present invention is not limited to these, and any compound may be used as long as it can be easily vaporized by heating or the like and introduced into a plasma CVD apparatus. Examples of the benzene having an alkyl group include toluene, xylene, mesitylene, cymene and cumene. Examples of the benzene having an alkylene group include styrene, methylstyrene, and ethylstyrene. Examples of benzenes and naphthalenes having a carboxyl group include benzoic acid, phthalic acid, salicylic acid, anthranilic acid and gallic acid. Examples of benzenes and naphthalenes having a hydroxyl group include phenol, cresol, picric acid, and naphthol. Examples of benzenes having an amino group include aniline and methylaniline. Examples of the ring condensate of a benzene ring include naphthalene, anthracene, naphthacene, chrysene, pyrene and perylene. Further, examples of the ring aggregate of the benzene ring include biphenyl and terphenyl.

The heterocyclic compound used in the present invention is
It is desirable that the compound has at least one kind of hetero element of nitrogen, oxygen and sulfur and has a conjugated double bond. Examples of the nitrogen-containing heterocyclic compound include pyridine, vinylpyridine, pyrimidine, pyrazine, pyridazine, triazine, pyrrole, pyrazole and triazole. Examples of the heterocyclic compound containing oxygen include furan and pyran. Examples of the sulfur-containing heterocyclic compound include thiophene and the like. These heterocyclic compounds may have a substituent such as an alkyl group, an alkylene group, a carboxyl group, a hydroxyl group or an amino group, like the aromatic compound. Further, a condensed ring compound or a ring aggregate of these heterocyclic compounds may be used. Further, it may be a heterocyclic compound containing different hetero atoms in one molecule. Examples include oxazole, oxazine, furazane or thiazole.

The plasma CVD apparatus used in the present invention is a plasma CV having a general plasma generation source such as a parallel plate type.
The D device may be used. However, it is desirable to use a plasma CVD apparatus having a high-density plasma source having an electron density of 10 ¹⁰ / cm ³ or more. Such a plasma CVD apparatus includes ECR (Electron Cyclotron Res.
onance) Plasma CVD equipment, ICP (Inductively Co
upled Plasma) CVD equipment, TCP (Transformer Coup
led Plasma) CVD apparatus or a helicon wave plasma CVD apparatus. Any of these plasma CVD apparatuses can obtain an electron density of about 10 ¹⁰ / cm ³ or more and less than 10 ¹⁴ / cm ³ . Plasma CV
As a means for introducing the source gas into the film formation chamber of the D apparatus, it is desirable to have a bubbler or the like for introducing a liquid or solid source compound by vaporizing it by heating or ultrasonic vibration.
It is desirable that the gas introduction piping system is heated by a heater, a heating medium, or the like.

The operation of the present invention will be described. The organic resin-based insulating film formed by the plasma CVD method of the present invention has an aromatic ring or a hetero ring in its polymer network. Compounds having these conjugated double bonds generally have high heat resistance. In addition, since the film is formed in a high vacuum, a lower-order reaction product is not taken into the film, and the heat resistance is also improved from this aspect.

Since the unsaturated hydrocarbon compound is easily dissociated in plasma and serves as a crosslinking accelerator for accelerating the polymerization reaction,
The molecular weight of the organic resin-based insulating film is increased, and the heat resistance is further improved.

Further, by employing a plasma CVD apparatus having a high-density plasma source having an electron density of 10 ¹⁰ / cm ³ or more, the source gas is highly dissociated, the cross-link density of the organic resin-based insulating film is improved, and the heat resistance is improved. Can be increased.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A semiconductor device will be described below as an example of an electronic device, and an example in which the present invention is applied to a process of forming an interlayer insulating film will be described with reference to FIG.

FIG. 1 is a schematic sectional view showing a main part of a semiconductor device to which the present invention is applied. That is, the interlayer insulating film 2 and the wiring layer 3 are formed on the semiconductor substrate 1, and the wiring layer 3
Is formed. On top of these structures,
An organic resin-based insulating film 4 is formed, and its surface is planarized. A connection hole 6 facing the wiring layer 3 is opened in the organic resin-based insulating film 4, and a contact plug including a barrier metal layer 7 and a metal layer 8 is embedded in the connection hole 6. The barrier metal layer 7 is made of Ti, Ta, Zr
Or a single layer or a laminate of such a high melting point metal or a nitride thereof. Note that the semiconductor device shown in FIG. 1 shows only relevant parts related to the present invention, and elements such as transistors formed on the semiconductor substrate 1 and upper wiring layers formed on contact plugs are all shown. Is omitted.

The characteristic portion of the semiconductor device shown in FIG. 1 is an organic resin-based insulating film 4, and the amount of low-molecular-weight reaction products and by-products in the organic resin-based insulating film 4 is smaller than that of a conventional device. It is extremely small compared to. Therefore, when the barrier metal layer 7 or the metal layer 8 is buried in the connection hole 6, these low molecular weight components do not vaporize. Therefore, the buried shape of the barrier metal layer 7 and the metal layer 8 is good, and a low-resistance and highly reliable contact plug can be formed.

The organic resin insulating film 4 is formed by subjecting a source gas containing an aromatic compound or a heterocyclic compound to plasma polymerization.

The semiconductor device as an example of the electronic device according to the present invention is not limited to the structure shown in FIG. 1, but may be an example in which an organic resin-based insulating film is formed directly on a semiconductor substrate, or a barrier formed on a flat organic resin-based insulating film. Various modifications are possible, such as a structural example in which a metal layer having a metal layer as a lower layer is formed. As electronic devices, in addition to semiconductor devices, organic resin insulation of various electronic devices such as thin film magnetic heads, magnetoresistive heads, thin film inductors, thin film coils, micromachines, etc. It can be suitably applied as a film.

Hereinafter, as an example of a method of manufacturing an electronic device according to the present invention, a method of manufacturing the semiconductor device shown in FIG. 1 will be described in more detail with reference to FIG.

Embodiment 1 This embodiment is an example in which xylene is used as an aromatic compound and acetylene is used as an unsaturated hydrocarbon compound, and a polyxylene resin is formed as an organic resin insulating film.

As shown in FIG. 2A, a substrate to be processed employed in this embodiment is formed on a semiconductor substrate 1 such as silicon.
interlayer insulating film 2 and the Al-based line-and-space pattern of the wiring layer 3 made of metal or the like made of iO ₂ like those that have been formed. The surface of the substrate to be processed has a step due to the wiring layer 3.

On the substrate to be processed, the next plasma CVD
An organic resin-based insulating film 4 was formed depending on the conditions. Note that a parallel plate type plasma CVD apparatus was used as a film forming apparatus. p-xylene 100 sccm acetylene 20 sccm pressure 1000 Pa RF power 500 W substrate temperature 400 ° C. p-xylene may be o-xylene or m-xylene. The thickness of the organic resin-based insulating film 4 is such that a sufficient thickness is formed as an interlayer insulating film on the surface of the wiring layer 3 as shown in FIG. Thickness.

Although the function as an interlayer insulating film is sufficient only with the organic resin insulating film 4, it is desirable to flatten the concave portions generated between the spaces of the wiring layer 3. Therefore, next, a silicon oxide-based insulating film 5 is formed to a thickness of, for example, 500 nm by a plasma CVD (Chemical Vapor Deposition) method (FIG. 2C). Silicon oxide insulating film 5
Is selected from SiO ₂ , SiOF, SiON or SiO ₂ containing impurities.

Next, this silicon oxide-based insulating film 5 is
Flattening is performed by a P (Chemical mechanical polishing) method (FIG. 2D).

Next, as shown in FIG.
Is opened by reactive ion etching. Immediately after cleaning the surface of the wiring layer 3 exposed at the bottom of the connection hole 6, a barrier metal layer 7 made of TiN is formed to a thickness of 70 nm by reactive sputtering. Subsequently, a metal layer 8 made of W is formed to a thickness of 800 nm by a blanket CVD method, flattened and polished by a CMP method, and a contact plug made of a barrier metal layer 7 and a metal layer 8 is formed in the connection hole 6. Embed. This embedding step may be performed by etching back the entire surface.

According to the present embodiment, the yield of the substrate to be processed whose contact resistance is within the specified value is 100%. On the other hand, the yield of a sample manufactured in exactly the same manner except that the polyimide resin was formed by a coating method according to a conventional method was 15%.

According to the present embodiment, in the reactive sputtering of TiN or the blanket CVD process of W, there is substantially no outgassing from the organic resin-based insulating film 4, so that there is no void or the like and the buried shape is excellent. A contact plug is formed. In addition, since the contact portion is less contaminated, adhesion is secured and a low-resistance contact plug can be formed.

In the flattening step as an interlayer insulating film, a silicon oxide-based insulating film 5 was formed on the organic resin-based insulating film 4 and subjected to CMP.
It is also possible to apply CMP directly to the surface to flatten it.

Embodiment 2 In this embodiment, salicylic acid is used as an aromatic compound, and pinacol (tetramethylethylene glycol; HOC (CH ₃ )) is used.
_{2 C (CH 3) 2 OH} ) was added, an example of forming an organic resin-based insulating film according polyether resin. Since the present embodiment is similar to the previous embodiment except for the step of forming the organic resin-based insulating film, the overlapping description will be omitted and only the description of the characteristic portions will be given.

The steps up to the step shown in FIG. 2A, that is, the steps up to the step of forming the wiring layer 3 may be the same as in the previous embodiment.

Thereafter, an organic resin-based insulating film 4 was formed under the following plasma CVD conditions. Note that an ECR plasma CVD apparatus was used as a film forming apparatus. Salicylic acid 100 sccm Pinacol 20 sccm Pressure 1 Pa Microwave power 500 W Substrate temperature 400 ° C. The thickness of the organic resin-based insulating film 4 is sufficient as an interlayer insulating film on the surface of the wiring layer 3 as shown in FIG. The thickness is set to such an extent that the film thickness is formed, for example, 0.8 μm on the wiring layer 3.

The subsequent steps, that is, up to the step of forming the contact plug shown in FIG. 2E, may be the same as in the previous embodiment.

According to the present embodiment, the yield of the substrate to be processed whose contact resistance is within the specified value is 100%. On the other hand, the yield of the sample formed by applying the benzocyclobutene (BCB) resin by the coating method was 15%.

According to the present embodiment, in the reactive sputtering of TiN or the blanket CVD process of W, there is substantially no outgassing from the organic resin-based insulating film 4, so that the buried shape is excellent without voids and the like. A contact plug is formed. In addition, since the contact portion is less contaminated, adhesion is secured and a low-resistance contact plug can be formed.

[Embodiment 3] This embodiment is an example in which pyridine is employed as a heterocyclic compound, and an organic resin-based insulating film of a polypyridine resin is formed using ammonia as an additive gas. This embodiment is the same as the previous embodiment 1 except for the step of forming the organic resin-based insulating film, so that the overlapping description will be omitted and only the description of the characteristic portions will be given.

The steps up to the step shown in FIG. 2A, that is, up to the step of forming the wiring layer 3 may be the same as in the first embodiment.

Thereafter, an organic resin-based insulating film 4 was formed under the following plasma CVD conditions. Note that a parallel plate type plasma CVD apparatus was used as a film forming apparatus. Pyridine 100 sccm Ammonia 20 sccm Pressure 1000 Pa RF power 500 W Substrate temperature 400 ° C. The thickness of the organic resin-based insulating film 4 is sufficient as an interlayer insulating film on the surface of the wiring layer 3 as shown in FIG. The thickness is set to such an extent that the thickness is formed, for example, 0.8 μm on the wiring layer 3.

The subsequent steps up to the step of forming the contact plug shown in FIG. 2E may be the same as the previous embodiment.

According to the present embodiment, the yield of the substrate to be processed whose contact resistance is within the specified value is 100%. On the other hand, the yield of the sample formed by applying the polyimide resin by the coating method was also 15%.

According to the present embodiment, in the reactive sputtering of TiN or the blanket CVD process of W, degassing from the organic resin-based insulating film 4 is substantially absent. A contact plug is formed. In addition, since the contact portion is less contaminated, adhesion is secured and a low-resistance contact plug can be formed.

Although the present invention has been described with reference to the three embodiments, the present invention is not limited to these embodiments.
Various organic resin-based insulating films can be obtained by appropriately combining a heterocyclic compound or, if necessary, an unsaturated hydrocarbon compound. A carrier gas such as Ar may be mixed with these source gases.

The present invention may be applied to a passivation film in addition to an interlayer insulating film of a semiconductor device.

Furthermore, in addition to the semiconductor device, the present invention is particularly suitably applied to various electronic devices such as a thin film magnetic head, a magnetoresistive head, a thin film inductor, a thin film coil, and a micromachine, particularly various electronic devices used in a high frequency band. Can be.

[0049]

As is apparent from the above description, according to the method of manufacturing an electronic device having an organic resin-based insulating film of the present invention, volatile impurities in the organic resin-based insulating film can be sufficiently removed, and Can be enhanced. Therefore, when a contact plug is formed in the connection hole opened in the organic resin-based insulating film, degassing is suppressed, and a low-resistance interlayer connection excellent in the buried shape can be achieved.

Further, the method of manufacturing an electronic device having an organic resin-based insulating film according to the present invention can be realized by a simple method without using a special raw material gas, a new manufacturing device, or the like.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view of an example in which an electronic device according to a manufacturing method of the present invention is applied to a semiconductor device.

FIG. 2 is a schematic cross-sectional view showing an example of a process in which the method for manufacturing an electronic device of the present invention is applied to a method for manufacturing a semiconductor device.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Semiconductor substrate, 2 ... Interlayer insulating film, 3 ... Wiring layer, 4 ... Organic resin based insulating film, 5 ... Silicon oxide based insulating film, 6 ... Connection hole, 7 ... Barrier metal layer, 8 ... Metal layer

Claims (5)

[Claims] 1. A method for manufacturing an electronic device, comprising a step of forming an organic resin-based insulating film on a substrate to be processed by a plasma CVD method, wherein the organic resin-based insulating film comprises an aromatic compound and a heterocyclic compound. A method for manufacturing an electronic device having an organic resin-based insulating film, wherein the method is formed by subjecting a source gas containing at least one of the compounds to plasma polymerization. 2. The method for manufacturing an electronic device having an organic resin-based insulating film according to claim 1, wherein said source gas further contains an unsaturated hydrocarbon compound. 3. The aromatic compound according to claim 1, wherein the aromatic compound is a benzene having at least one substituent selected from an alkyl group, an alkylene group, a carboxyl group, a hydroxyl group and an amino group. A method of manufacturing an electronic device having an organic resin-based insulating film. 4. The compound according to claim 1, wherein the heterocyclic compound has at least one hetero element of nitrogen, oxygen and sulfur and has a conjugated double bond. A method of manufacturing an electronic device having an organic resin-based insulating film. 5. The method according to claim 1, wherein the plasma CVD is performed at a rate of 10 ¹⁰ / cm.
^{2. The} method of manufacturing an electronic device having an organic resin-based insulating film according to claim 1, wherein the method is performed by a plasma CVD apparatus having a high-density plasma generation source having an electron density of ³ or more.