JPH06283506A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To provide an insulating film, which is sufficient in coverage, is high in self-flatness, has good flow properties and moreover, has low permeability to water and is small in a water content, as a passivation film or a dielectric film. CONSTITUTION:The surface of an insulative nitride or oxynitride base film 14 is treated with an organic solvent and thereafter, an insulating film 17 is formed by a CVD method using an organic silane and ozone-containing oxygen, whereby the insulating film, which is good in coverage and burying properties, is superior in flatness, has low permeability to water and is small in a water content, is obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a method of manufacturing a semiconductor device,
In particular, a final insulating film that acts as a passivation film on a semiconductor substrate and metal wiring and an insulating film that can be used as a dielectric film for forming a capacitance are formed by chemical vapor deposition using an organic silane compound as a source gas. The present invention relates to a method for manufacturing a semiconductor device as described above.

[0002]

2. Description of the Related Art In recent years, high integration and high density of VLSI devices have been rapidly advanced, and submicron processing has become essential in semiconductor processing technology. As the submicron processing progresses, the unevenness of the semiconductor substrate surface becomes more and more intense,
The aspect ratio becomes large, and this unevenness becomes a constraint in device manufacturing. What is most strongly desired for solving such a problem is a flattening technique for an insulating film used for a passivation film and a dielectric film.

Characteristics required for an insulating film for submicron devices include forming a space on the order of submicrons and achieving excellent step coverage for a pattern having a high aspect ratio. A chemical vapor deposition method (CVD method) using organic silane and inorganic silane as source gases is known as a method for forming an interlayer insulating film that satisfies such requirements. As the CVD method, plasma CVD, atmospheric pressure CVD method, low pressure CVD method, pressure CVD method
Methods and photo-excited CVD methods have been proposed.

Among these, an insulating film formed by an atmospheric pressure CVD method using an organic silane as a raw material gas and adding ozone gas thereto, that is, an atmospheric pressure ozone-organic silane CVD silicon oxide film is particularly excellent in flatness. This is one of the most expected methods of being able to do so. An atmospheric pressure CVD method using such a mixed gas of ozone-organosilane is disclosed in
No. 61-77695 or "Electrochemistry" 56, No. 7 (1988), 527-
It is described on page 532.

Further, with respect to the insulating film used as the final protective film, it is strongly demanded that the flatness thereof and the film quality which affects the reliability of the device are improved with the high integration and high density of VLSI devices. There is. This is mainly to prevent intrusion of moisture and alkali metal ions from the outside of the semiconductor device.

[0006]

However, in the conventional method for forming an insulating film by the CVD method using organosilane as a raw material gas, there is a gap between steps (between wirings) depending on the substrate material due to the substrate dependency of the deposition rate. However, there is a drawback in that the embedding property of is deteriorated and a void is generated in the film. The fact that the organic silane-CVD film has a large underlayer dependency is described in, for example, "The Institute of Electrical Engineers of Japan", Vol. 111, No. 7, pp. 652-658, published in 1991. When the embedding property deteriorates or voids are formed in this way, the leak current between the wirings increases and the device characteristics are adversely affected.

Further, the conventional CVD film using organic silane has a large amount of carbon compounds (unreacted substances) containing water etc. in the film.
However, there is a defect that the film quality is poor, the moisture absorption resistance is poor, and cracks occur. If a thick film is used to supplement the moisture absorption resistance, cracks are more likely to occur in the film, which has the drawback of impairing the reliability of the device.

In order to alleviate the above-mentioned drawbacks of the conventional insulating film forming method, a method of reacting an organic compound of silicon such as silicate ester with ozone has been developed as a CVD method having self-flatness. However, there is a problem in that the film quality, the film forming speed, and the embedding property are strongly influenced by the underlying state, and a good film cannot be formed.

In general, when there is an oxide film on the underlayer as a treatment for alleviating the dependency on the underlayer, the surface of the oxide film is subjected to plasma treatment using a gas such as N2 or NH3, and then an atmospheric pressure CVD film of organic silane is formed. Is said to be effective, but there is concern about the problem of plasma damage. Further, the plasma treatment has a drawback that the embedding property is not improved and the process is unstable.

In particular, an insulating nitride (SiN) or oxynitride of silicon used as a passivation film or a dielectric film is generally formed by a plasma CVD method, but its coverage is poor and a large step remains. Further, it was difficult to carry out multilayer wiring. A silicon plasma nitride film (p-SiN) is generally used for the passivation film, but it has a drawback that the coverage is poor, the film is formed in an inverse tapered shape, and voids are likely to remain. Although oxynitride has an advantage that it has a high withstand voltage and a good film quality, it has a drawback that the surface is highly hydrophobic and it is difficult to form an insulating film by atmospheric pressure CVD on it.

The object of the present invention is to solve the above-mentioned drawbacks in the conventional insulating film formation, and to be excellent in embedding between steps and elimination of voids in the film without plasma damage. As well as having an excellent film quality that is effective for use as an insulating film with no cracks, sufficient coverage, high self-flatness and rich flowability, and an excellent water permeability and low content. An object of the present invention is to provide a method for manufacturing a semiconductor device having a passivation film or a dielectric film.

[0012]

In the method of manufacturing a semiconductor device according to the present invention, when an insulating film is formed by chemical vapor deposition using an organic silane-based compound as a raw material, a base treatment with an organic compound or a solution thereof is performed. It is characterized in that the passivation film and the dielectric film are formed by atmospheric pressure CVD in which the underlayer dependency is eliminated and then the organosilane compound and oxygen containing ozone are reacted.

Examples of the organic compound include aliphatic saturated monohydric alcohols, aliphatic unsaturated monohydric alcohols, aromatic alcohols, aliphatic saturated polyhydric alcohols and their derivatives, aldehydes, ethers, ketones and keto alcohols. , Carboxylic acids, nitroalkanes, amines, acylnitriles, acid amides, and heterocyclic compounds, and the following substances can be specifically used. Aliphatic saturated monohydric alcohols: methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-methyl-1-propanol, 2-butanol, 2-methyl-2-propanol, 1-pentanol, 3 -Methyl-1-butanol, 3-methyl-2-butanol, 2-methyl-2-butanol, 1-hexanol, cyclohexanol Aliphatic unsaturated monohydric alcohols: allyl alcohol, propargyl alcohol, 2-methyl-3 -Butin-2-ol aromatic alcohols: benzyl alcohol, furfuryl alcohol, aliphatic saturated polyhydric alcohols and their derivatives: ethylene glycol, propylene glycol, diethylene glycol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, Tylene glycol mono-n-butyl ether, ethylene glycol monoisobutyl ether, propylene glycol monomethyl ether, ethylene glycol dimethyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol dimethyl ether Aldehyde: formaldehyde, acetaldehyde, glyoxal ether: diethyl ether, dioxane, tetrahydrofuran, tetrahydroflur Furyl alcohol Ketone / keto alcohol: Acetone, 2-butanone, diacetone alcohol, γ-butyrolactone, propylene carbonate Carboxylic acid: Formic acid, acetic acid, propionic acid, glycolic acid, lactic acid, ethyl lactate Nitroalkane: Nitromethane, Nitroethane, Nitropropane, Nitro Benzene amine: ethylamine, propylamine, isopropylamine, butylamine, isobutylamine, allylamine, aniline, toluidine, ethylenediamine, diethylamine, ethylene imine, dipropylamine, diisopropylamine, dibutylamine, triethylamine,
Tri-n-propylamine, tri-n-butylamine Acyl nitriles: acetonitrile, propiononitrile, butyronitrile, acrylonitrile, methacrylonitrile, benzonitrile Acid amide: formamide, N-methylformamide,
N, N-dimethylformamide, N-methylacetamide, N, N-dimethylacetamide, heterocyclic compound: pyridine, quinoline, pyrrole, piperidine, piperazine, morpholine, 2-pyrrolidinone,
1-Methyl-2-pyrrolidinone However, lower alcohols and acetylene alcohols are particularly preferable.

The following compounds can be used as the organic silane compound. Organic silane Tetraalkoxy silane (orthosilicate ester): tetramethoxysilane, tetraethoxysilane, tetra-n
Propoxysilane, tetraisopropoxysilane, tetra-n-butoxysilane Alkylalkoxysilane: methyltrimethoxysilane, methyltriethoxysilane, methyltri-n-propoxysilane, methyltriisopropoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, ethyltri-n-propoxy Silane, ethyltriisopropoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, phenyltrimethoxysilane dimethyldimethoxysilane, dimethyldiethoxysilane, diethyldimethoxysilane, diethyldiethoxysilane, diethyldi-n-propoxysilane, diethyldiisopropoxysilane , Methylvinyldimethoxysilane, methylvinyldiethoxysilane methyldimethoxysilane, methyldiethoxy Run Dimethylvinylmethoxysilane, Dimethylvinylethoxysilane Polysiloxane: Tetrakis (dimethylsiloxy) silane Cyclosiloxane: Octamethylcyclotetrasiloxane, pentamethylcyclotetrasiloxane, Tetramethylcyclotetrasiloxane, Hexamethylcyclotrisiloxane, Trimethylcyclotrisiloxane Disiloxane: hexamethyldisiloxane, tetramethyldimethoxydisiloxane, dimethyltetramethoxydisiloxane, hexamethoxydisiloxane Alkylsilane: monomethylsilane, dimethylsilane,
Trimethylsilane, triethylsilane, tetramethylsilane, tetraethylsilane allyltrimethylsilane hexamethyldisilane silylamine: dimethyltrimethylsilylamine, diethyltrimethylsilylamine silane nitrogen derivative: aminopropyltriethoxysilane trimethylsilylazide, trimethylsilylcyanide silazane: hexamethyldisilazane, tetra Methyldisilazane octamethylcyclotetrasilazane, hexamethylcyclotrisilazane Halogenated silanes and derivatives: trimethylchlorosilane, triethylchlorosilane, tri-n-propylchlorosilane, methyldichlorosilane, dimethylchlorosilane,
Chloromethyldimethylchlorosilane, chloromethyltrimethylsilane, chloropropylmethyldichlorosilane,
Chloropropyltrimethoxysilane dimethyldichlorosilane, diethyldichlorosilane, methylvinyldichlorosilane, methyltrichlorosilane,
Ethyltrichlorosilane, vinyltrichlorosilane, trifluoropropyltrichlorosilane, trifluoropropyltrimethoxysilane, trimethylsilyliodide, in the present invention, the above-mentioned organosilane compounds are used alone or in combination of two or more substances. Can be used. When mixed and used, the mixing ratio may be appropriately adjusted. Further, from the viewpoint of effects, it is most preferable to use ethanol as the organic compound and TEOS as the organic silane compound as the main raw material gas.

[0015]

According to the method of manufacturing a semiconductor device according to the present invention as described above, the underlying surface is treated with the above-mentioned organic compound or its solution before the insulating film is formed by the CVD method using the organosilane compound as the source gas. By performing a very simple treatment (hereinafter also referred to as organic matter treatment), it is possible to greatly reduce the dependency on the underlayer, and it is excellent in embedding property, self-flatness and flowability, and has no cracks or voids. An insulating film having excellent coverage and water permeability and a film quality with a small content can be formed, and the throughput can be remarkably improved.

As the solvent for treating the underlying surface before film formation, the above-mentioned organic compounds having high polarity capable of removing active adsorption sites are preferable, and ethanol is most preferable.

The underlying nitride film is a plasma nitride film formed by the reaction of silane or organic silane with nitrogen, a plasma oxynitride film formed by the reaction of silane or organic silane with nitrous oxide / nitrogen, or an oxide film and ammonia. Examples thereof include an oxynitride film formed by the gas-solid reaction or an oxynitride film formed by the gas-solid reaction of a nitride film and oxygen or an oxidizing gas.

Since the surface energy of the nitride film is high and chemical adsorption is likely to occur, the surface state is made constant by forcibly adsorbing the solution of the organic compound on this surface, and the subsequent AP-CVD Flatness, flowability, and coverage can be improved.

[0019]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a configuration of an example of an apparatus that can be used as an apparatus for forming an organosilane-CVD film in an embodiment of a method for manufacturing a semiconductor device according to the present invention described below. A heater 2 is provided inside the reaction chamber 1 to heat the silicon wafer 4 supported by the susceptor 3. Further, an ozone generator 5 and a constant temperature bath 6 are provided outside the reaction chamber 1, and a gas bubbler 7 is placed inside the constant temperature bath. Ozone gas is supplied to the ozone generator 5 to generate ozone. The ozone generation rate of this ozone generator 5 is 4.0%
Is. Nitrogen gas was supplied to the gas bubbler 7 arranged in the constant temperature bath 6, and the organic silane contained in the gas bubbler,
In this example, TEOS gas is generated. This TEOS gas is supplied to the reaction chamber 1 together with ozone generated by the ozone generator 5 using nitrogen gas as a carrier gas. A dispersion head 8 is arranged in the reaction chamber 1, and a mixed gas of ozone and TEOS gas is applied as a laminar flow to the surface of the silicon wafer 4 so that a uniform film is formed on the entire surface of the silicon wafer. To Further, for this purpose, the silicon wafer 4 is swung in the plane together with the heater 2 and the susceptor 3 to ensure the uniformity of film formation.

(Example 1) As shown in FIG. 2, a BPSG film 12 having a film thickness of 1 μm is formed on a silicon substrate 11, and an aluminum pattern 13 having a height of 1 μm is formed as a first wiring on the BPSG film 12 by etching. To do. Then plasma-TE
An OS CVD NSG film 14 was formed, and an aluminum wiring 15 having a height of 1 μm was formed thereon with a line width of 0.5 μm and a space width of 0.5 μm. Further, on the plasma-TEOS CVD NSG film 14 and the aluminum wiring 15, a plasma nitride film as a nitride was formed by the reaction of silane and nitrogen to a thickness of 0.2 μm. The deposition conditions for this plasma nitride film are:
At ℃, film formation pressure 0.35 Torr, silane is supplied at a rate of 500 ml / min, ammonia is supplied at a rate of 30 ml / min, and RF
The power used was 50 KHz, 1 KW, and the film formation time was 6 minutes.

Next, the surface of the plasma nitride film 16 which is the base of the silicon wafer was treated with a solution of an organic compound, for example, with ethanol. In the ethanol treatment of this example, a silicon wafer was placed on a spin coater,
Ethyl alcohol was applied at a flow rate of 100 ml / min for 2 seconds while rotating at 1000 rpm, and then dried at 2000 rpm for 60 seconds.

Next, the thus dried silicon wafer was carried into the reaction chamber shown in FIG. 1, and an ozone-TEOS CVD PSG film 17 was formed to a film thickness of 6000Å under the following film forming conditions. Further, a plasma nitride film 18 is further formed thereon under the above conditions by 0.2
A μm film was formed. This PSG film is used as a passivation film.

[Table 1] Film formation temperature 400 ℃ Film formation pressure Atmospheric pressure Film formation time 545 seconds Nitrogen gas flow to gas bubbler 1.5l / min Constant temperature bath temperature 65 ℃ Oxygen flow to ozone generator 7.5l / min Ozone concentration 120g / m3 Carrier N2 18 SLM The ozone-TEOS CVD PSG film 17 thus formed fills the narrow space between the aluminum wirings 15, has good step coverage, has excellent self-flatness, and forms voids. However, it had good coverage and embeddability, and had good film quality with low water permeability and low content.

Further, when forming the dielectric film, a metal layer as one electrode plate of the capacitor is formed to a thickness of 0.2 at the place where the capacitor is to be provided when the underlying insulating film is formed.
μm, for example by etching locally, then
A nitride film having a thickness of 0.05 μm is formed under the above conditions, and the surface of this silicon wafer is treated with the same organic compound solution as described above, for example, with ethanol. Then, this silicon wafer was loaded into the reaction chamber shown in FIG. 1, and ozone-TEOS CVD N was formed under the same film forming conditions as described above.
An SG film is formed to a desired thickness, for example, 0.5 μm, and then the other electrode plate metal is provided above the electrode plate metal layer. In this way, a capacitor composed of the bipolar plates and the two insulating films between them can be obtained.

[0024]

As described above, in the method of manufacturing a semiconductor device according to the present invention, before forming an insulating film by a chemical vapor deposition method using an organic silane-based source gas, the underlying surface is treated with an organic compound solution. By the extremely simple and rapid process such as the direct process, the CVD insulating film has a good burying property, there is no void in the insulating film, and a high-quality insulating film having high self-flatness can be formed with good coverage. In addition, the passivation film or the insulating film as a dielectric film thus formed has a small amount of water,
It also has excellent moisture absorption resistance, there is no risk of cracks occurring in the post-treatment, the device characteristics can be improved, and it can be suitably used as a passivation film and a dielectric film.

[Brief description of drawings]

FIG. 1 is a diagram showing the configuration of a chemical vapor deposition apparatus for forming an ozone-organosilane CVD film in a method for manufacturing a semiconductor device according to the present invention.

FIG. 2 is a cross-sectional view showing a semiconductor device formed by an embodiment of a method for manufacturing a semiconductor device according to the present invention.

[Explanation of symbols]

 1 Reaction Chamber 2 Heater 3 Susceptor 4 Silicon Wafer 5 Ozone Generator 6 Constant Temperature Chamber 7 Gas Bubbler 8 Dispersion Head 11 Substrate 12 BPSG Film 13 Al 14 Plasma-TEOS CVD NSG Film 15 Al Wiring 16 Plasma Nitride Film 17 Ozone-TEOS CVD PSG Film 18 Plasma nitride film

Claims (2)

[Claims] 1. When forming an insulating film by chemical vapor deposition using an organic silane-based compound as a raw material, an undertreatment with an organic compound or a solution thereof is applied to the underlayer to eliminate the underlayer dependency, and then the organic silane compound is added. A method for manufacturing a semiconductor device, characterized in that a passivation film or a dielectric film is formed by atmospheric pressure CVD in which oxygen containing ozone is reacted. 2. The method of manufacturing a semiconductor device according to claim 1, wherein the base is an insulating nitride or an oxynitride.