JP3054289B2 - Method for manufacturing semiconductor device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for manufacturing a semiconductor device,
In particular, a primary insulating film between the semiconductor substrate and the first layer metal wiring,
The present invention relates to a method for forming a final insulating film acting as an interlayer insulating film between metal wirings and a passivation film and an insulating film which can be used as a sidewall of a gate of a field effect transistor by chemical vapor deposition.

[0002]

2. Description of the Related Art In recent years, high integration and high density of VLSI devices have rapidly progressed, and submicron processing has become essential for semiconductor processing technology. As the submicron processing progresses, the irregularities on the surface of the semiconductor substrate become more and more severe,
The aspect ratio has become large, and this unevenness has become a constraint in device manufacturing. What is most strongly desired for solving such a problem is a technique for planarizing an interlayer insulating film.

The characteristics required for an interlayer insulating film for a submicron device include forming a space on the order of submicrons and achieving excellent step coverage for a pattern having a high aspect ratio. As a method of forming an interlayer insulating film satisfying such a demand, a chemical vapor deposition method (CVD method) using organic silane and inorganic silane as a source gas is known. The CVD methods include plasma CVD, normal pressure CVD, reduced pressure CVD, and pressurized CV.
The D method and the photo-excited CVD method have been proposed.

Of these, organosilane is used as a source gas,
An insulating film formed by adding an ozone gas thereto and performing normal pressure CVD, that is, a normal pressure ozone-organosilane CVD silicon oxide film is one of the most promising methods because of its particularly excellent flatness. . A normal pressure CVD method using such an ozone-organosilane mixed gas is disclosed in, for example,
-77695 and `` Electrochemistry '' 56, No. 7 (1988), 527-53
It is described on page 2 etc. TEOS (t
etraethoxyorthosilicate), TMOS (tetramethoxyorthosi
licate), OMCTS (octamethylcyclotetrasiloxane), HMDS
(hexamethyldisiloxane), TMCTS (tetramethylcyclotetr
asiloxane), SOB (trimethylsilyl borate), DADBS (diace
toxydi-tertiary-butoxysilane), SOP (trimethylsilyl
phosphate) is known.

[0005] In addition, as for the insulating film used as the final protective film, with the increase in integration and density of VLSI devices, there is a strong demand for improvement of coverage characteristics and flatness, and improvement of film quality which affects device reliability. Have been. This is mainly to prevent invasion of moisture and the like from the outside of the element.

[0006]

However, in the conventional method of forming an insulating film by a CVD method using organic silane as a source gas, the characteristics of the insulating film are significantly reduced or the level difference between steps (depending on the surface condition of the base) is reduced. The embedding property between wirings) is significantly deteriorated. In particular, in the CVD method using TEOS and ozone as source gases, problems such as a decrease in the density of an insulating film to be formed, an increase in an etch rate, or an increase in a leak current are caused depending on the conditions for forming the base. Arises
There is a possibility that good insulating properties cannot be obtained. Also,
The deposition rate is dependent on the underlying layer, and the deposition rate is different between a dense part and a sparse part of the step pattern, and the step on the substrate after forming the insulating film is disadvantageously increased. I have. Further, in the case of a step pattern having a step aspect ratio larger than about 2, there is a disadvantage that the step is not completely filled and a void is generated between the steps.

As a method for solving such a problem,
For example, 16 of the proceedings of the 1992 Spring Society of Applied Physics
p-2Q-6 and the magazine "Technical" published in 1989
As described in Digest Electron Devices Meeting, page 669, a method has been proposed in which an underlayer is subjected to plasma treatment and then an organosilane-CVD film is formed. However, in this method, the dependency of the film formation rate on the base is eliminated, but the filling property between the steps is further deteriorated.

Accordingly, an object of the present invention is to solve the above-mentioned drawbacks, to further improve the dependency of the film formation rate on the underlayer and the filling property between the steps, and particularly to a semiconductor suitable for forming an insulating film of a submicron device. An object of the present invention is to provide a method for manufacturing a device.

[0009]

According to the method of manufacturing a semiconductor device of the present invention, when forming an insulating film of a semiconductor device by chemical vapor deposition, the underlying surface is treated with a processing fluid containing an organic compound, The underlayer surface is treated with plasma, and thereafter, an insulating film is formed by chemical vapor deposition.

By treating the underlayer surface with a processing fluid containing an organic compound such as methanol or ethanol, the organic compound is uniformly adsorbed on the underlayer surface, and the insulating film is formed by CVD using ozone and TEOS as source gases. The embedding property in the forming step can be further improved. This fluid treatment containing an organic compound is described in detail in Japanese Patent Application No. 5-52412 proposed by the present applicant.
See the publication of this patent application.

In the fluid treatment containing the organic compound, the filling performance between steps is improved, but the difference in film forming speed due to the step pattern tends to increase, and therefore the flatness of the entire wafer is improved. There is a need. On the other hand, as described above, in the manufacturing method in which the plasma processing is performed before the CVD film is formed, the difference in deposition rate due to the step is reduced, but the filling performance in the step pattern having a high aspect ratio is insufficient, and the aspect ratio is low. In the case of a step having a ratio of 1.5 or more, voids are generated.

For this reason, in the present invention, after performing fluid treatment on the underlying surface with an organic compound, plasma treatment is further performed, and then an insulating film is formed by a CVD method. If the underlying surface is treated with a treatment fluid containing an organic compound, the treatment fluid can enter between the steps having a large aspect ratio.
On the other hand, in the case of the plasma treatment, active radicals or ions are unlikely to enter between small steps, and the effect is limited to a wide flat base surface. Therefore, it is presumed that fluid treatment with an organic compound is extremely effective for a dense step pattern having a large aspect ratio, and plasma treatment is effective for a base surface having a small aspect ratio and a sparse step pattern. Therefore, by using both the fluid treatment and the plasma treatment with the organic compound, both the embedding property between the steps and the flattening can be sufficiently achieved even on the base surface where the portion having the large aspect ratio and the portion having the small aspect ratio exist. be able to.

In the present invention, it is preferable that the insulating film is formed by chemical vapor deposition using organosilane as a raw material. As the organic silane, for example, the above-mentioned TEOS, TMOS, OMCTS, HMDS, SOB, DADBS or SOP
However, another silane compound can be used as a raw material. Further, in the method for manufacturing a semiconductor device according to the present invention, the organic compound of the processing fluid may be an OH group,
It is preferable to use an organic compound or a heterocyclic compound having at least one functional group of CO group, COC group, CN group, NO ₂ group and NR (R = H or alkyl group). Among these organic compounds, it is preferable to use an alcohol having an OH group, particularly ethanol or methanol. Also,
An aqueous solution of an organic compound or an organic solvent solution can also be used as the processing fluid. Further, as in the embodiment described later, a base insulating film is formed before forming the insulating film by chemical vapor deposition, and the base insulating film is treated with a processing fluid or a polysilicon pattern is formed. Can be treated with a treatment fluid.

As described above, examples of the organic compound for performing the base treatment include aliphatic saturated monohydric alcohols, aliphatic unsaturated monohydric alcohols, aromatic alcohols, aliphatic saturated polyhydric alcohols, and the like. Derivatives, aldehydes, ethers, ketones / keto alcohols, carboxylic acids,
Nitroalkanes, amines, acyl nitriles, acid amides,
Heterocyclic compounds can be mentioned, and specifically, the following substances can be used. Aliphatic saturated monohydric alcohols (OH group): 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 (OH groups): allyl alcohol, propargyl alcohol, 2-methyl-3-butyn-2-ol Aromatic alcohol (OH group): benzyl alcohol, furfuryl alcohol Aliphatic saturated polyhydric alcohols and their derivatives (OH group):
Ethylene glycol, propylene glycol, diethylene glycol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol mono nbutyl 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 (CO group): formaldehyde, acetaldehyde, glyoxal ether (COC group): diethyl ether, dioxane, tetrahydrofuran, tetrahydrofurfuryl alcohol Ketone / keto alcohol (CO group): acetone, 2-butanone, diacetone alcohol, γ-butyrolactone, propylene carbonate carboxylic acid (CO group): formic acid, acetic acid, propionic acid, glycolic acid, lactic acid, ethyl lactate Nitroalkane (NO ₂ group): nitromethane, nitroethane, nitropropane, nitrobenzene Amine (NR: R = H) Ethylamine, propylamine, isopropylamine,
Butylamine, isobutylamine, allylamine, aniline, toluidine, ethylenediamine, diethylamine, ethyleneimine, dipropylamine, diisopropylamine, dibutylamine, triethylamine, tri-n
Propylamine, tri-n-butylamine acylnitrile (CN group): acetonitrile, propiononitrile, butyronitrile, acrylonitrile, methacrylonitrile, benzonitrile amide (NR: R = alkyl group) 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 In the present invention, the undercoating treatment can be performed with one kind of such organic compounds, or the treatment can be performed simultaneously or sequentially with two or more kinds of organic compounds. Among these organic compounds, alcohols having 5 or less carbon atoms are particularly preferred.

The following materials can be used as an organosilicon compound as a raw material when the insulating film is formed by chemical vapor deposition. Tetraalkoxysilane (orthosilicate): Tetramethoxysilane (TMOS), tetraethoxysilane (TEO
S), tetra-n-propoxysilane, tetra-isopropoxysilane, tetra-n-butoxysilane Alkylalkoxysilane: methyltrimethoxysilane, methyltriethoxysilane, methyltri-n-propoxysilane, methyltriisopropoxysilane, ethyltrimethoxysilane, ethyltriethoxy Silane, ethyltri-n-propoxysilane, ethyltriisopropoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, phenyltrimethoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, diethyldimethoxysilane, diethyldiethoxysilane, diethyldinpropoxysilane , Diethyldiisopropoxysilane, methylvinyldimethoxysilane, methylvinyldiethoxysilane, methyldimethoxysilane, methyl Ludiethoxysilane, dimethylvinylmethoxysilane, dimethylvinylethoxysilane Polysiloxane: tetrakis (dimethylsiloxy) silane Cyclosiloxane: octamethylcyclotetrasiloxane
(OMCTS), pentamethylcyclotetrasiloxane, tetramethylcyclotetrasiloxane, hexamethylcyclotrisiloxane, trimethylcyclotrisiloxane disiloxane: hexamethyldisiloxane (HMDS), tetramethyldimethoxydisiloxane, dimethyltetramethoxydisiloxane, hexa Methoxydisiloxane alkylsilane: monomethylsilane, dimethylsilane,
Trimethylsilane, triethylsilane, tetramethylsilane, tetraethylsilane, allyltrimethylsilane,
Hexamethyldisilane Silylamine: dimethyltrimethylsilylamine, diethyltrimethylsilylamine Silane nitrogen derivative: aminopropyltriethoxysilane, trimethylsilyl azide, trimethylsilyl cyanide Silazane: hexamethyldisilazane, tetramethyldisilazane, octamethylcyclotetrasilazane, hexamethylcyclotri Silazane halogenated silanes and derivatives: trimethylchlorosilane, triethylchlorosilane, tri-n-propylchlorosilane, methyldichlorosilane, dimethylchlorosilane,
Chloromethyldimethylchlorosilane, chloromethyltrimethylsilane, chloropropylmethyldichlorosilane,
Chloropropyltrimethoxysilane, dimethyldichlorosilane, diethyldichlorosilane, methylvinyldichlorosilane, methyltrichlorosilane, ethyltrichlorosilane, vinyltrichlorosilane, trifluoropropyltrichlorosilane, trifluoropropyltrimethoxysilane, trimethylsilyl iodide As the silicon compound, tris (trimethylsiloxy) borane (SOB), tris (trimethylsiloxy) phosphoryl (SOP), diacetoxydi-tert-butoxysilane (DADBS) and the like can also be used. Among these organic silanes, tetraethoxysilane (TEOS) is particularly preferable because it has a high vapor pressure and can form an insulating film having favorable characteristics. In the present invention, the above-mentioned organosilicon compounds can be used alone or as a mixture of two or more organosilicon compounds. In the case of using a mixture, the mixing ratio may be appropriately determined.

As the surface treatment, a coating treatment or a dipping treatment of the organic compound or its aqueous solution or its organic solvent solution with a spin coater, or an exposure treatment of the organic compound or its aqueous solution or its organic solvent solution with a vapor, Spray treatment, shower treatment, curtain flow coat treatment and the like can be mentioned. In a preferred embodiment of the present invention, in forming an insulating film acting as an interlayer insulating film of a semiconductor device, a plasma-CVD TEOS NSG film is formed as a base, and the surface thereof is subjected to an ethanol treatment using a spin coater.
O ₃ -TE by atmospheric ozone-CVD method using methane as raw material gas
An OS CVD NSG film is formed.

An RF or microwave plasma source can be used as a plasma source for the plasma treatment. A gas for generating plasma is ammonia, nitrogen, hydrogen, oxygen, helium, argon or a mixed gas thereof. Can be used. In particular, it is extremely effective for ammonia plasma.

[0018]

Embodiments of the present invention and comparative examples will be described below with reference to the drawings. FIG. 1 shows the structure of an example of an apparatus for forming an organic silane-CVD film in an embodiment of a method of manufacturing a semiconductor device according to the present invention described below. A heater 2 is provided inside the reaction chamber 1 to heat a silicon wafer 4 supported by a susceptor 3. Further, an ozone generator 5 and a thermostat 6 are provided outside the reaction chamber 1, and a gas bubbler 7 is disposed inside the thermostat. Oxygen gas is supplied to the ozone generator 5 to generate ozone. The ozone generation rate of the ozone generator 5 is 4.0%. Nitrogen gas is supplied to the gas bubbler 7 disposed in the constant temperature bath 6 to generate a gas of organic silane contained in the gas bubbler, in this example, TEOS. The TEOS gas is supplied to the reaction chamber 1 together with the ozone generated by the ozone generator 5 using the 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 over 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 uniformity of film formation.

FIGS. 2A to 2C are schematic sectional views showing a series of steps in a method for manufacturing a semiconductor device according to the present invention. As shown in FIG. 2A, an aluminum wiring 12 having a height of 1 μm was formed on a silicon substrate 11. As shown in FIG. 2 (b), a plasma-TEOS C
A VD NSG film 13 was formed to a thickness of 3000 mm. This plasma
The film formation temperature of the TEOS CVD NSG film 13 is 350
C., the deposition pressure was 2.2 Torr, TEOS was supplied at a rate of 500 sccm, oxygen gas was supplied at a rate of 500 sccm, RF power was 500 W, and deposition time was 20 seconds. The thickness of this plasma-TEOS CVD NSG film 13 is
Although it is 3000mm, only about 1000mm is formed on the side wall.

Next, the underlying surface of the silicon wafer was treated with ethanol. In the ethanol treatment of this example, a silicon wafer was placed on a spin coater, and ethyl alcohol was applied at a flow rate of 100 ml / min for 10 seconds while rotating at 3000 rpm, and then dried at 2000 rpm for 60 seconds.

Next, the silicon wear was mounted in a plasma generator and plasma irradiation was performed. Upon generation of plasma, ammonia gas was supplied at a rate of 50 sccm, nitrogen gas was supplied at a rate of 2000 sccm, RF power was set to 600 W, and plasma was generated under these conditions, and 100
The substrate heated to ℃ was irradiated with plasma for 1 minute.

Next, the silicon wafer is carried into the reaction chamber shown in FIG. 1 and the ozone-TEOS C
A VD NSG film 14 was formed to a thickness of 8000 mm. In this specification, the gas flow rate indicates a flow rate in a standard state at 0 ° C. and 1 atm.

[Table 1] Deposition temperature 400 ℃ Deposition pressure Atmospheric pressure Deposition time 545 seconds Nitrogen gas flow to gas bubbler 1.5 l / min Temperature bath temperature 65 ℃ Oxygen flow to ozone generator 7.5 l / min Ozone concentration 5 wt% Carrier N ₂ gas flow rate 18 l / min The ozone-TEOS CVD NSG film 14 thus formed fills a narrow space between the aluminum wirings 12, has a good step coverage, and has excellent flatness. It had good film quality with no voids formed.

The present invention is not limited to the above-described embodiment, and various modifications are possible. For example, in the above-described embodiment, an example in which a TEOS CVD NSG film is formed on an aluminum wiring has been described. However, the present invention can be applied to a case where an organic silane CVD film is formed as an interlayer insulating film. The present invention can be applied to the formation of a passivation film and the formation of a sidewall film on the side surface of a gate electrode of a FET, and also to the formation of a polysilicon multilayer wiring.

Further, the metal constituting the conductive wiring is not limited to the above-described embodiment, but may be, for example, Al,
Cu, Mo, W, Ti, TiN, TiW or alloys thereof can also be used.

Further, in the above-described embodiment, the ozone-TEOS CVDNSG film is formed after performing the ethanol treatment. However, the mixed gas of ozone and TEOS supplied to the reaction chamber is provided with TOP (trimethylphosphate) and TMB (trimethytyr).
ozone-TEOS CVDPSG by adding phosphorus and boron alkoxide gases as dopants (lborate)
A film or a BPSG film can also be formed. Further, as the organic silane raw material compound, not only TEOS but also the above-mentioned TMO
S, OMCTS, HMDS, TMCTS, SOB, DADBS, SOP, etc. can also be used.

[0026]

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, the underlying surface is treated with an organic substance and plasma treatment is performed. A step pattern having a high aspect ratio (aspect ratio of 3 or more), which could not be obtained in the past, can be buried, and the dependence of the deposition rate of the CVD film on the underlayer can be eliminated to form a flatter insulating film. Can be.

[Brief description of the drawings]

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

FIG. 2 is a sectional view showing a series of steps of a method for manufacturing a semiconductor device according to the present invention.

[Explanation of symbols]

 11 Silicon substrate 12 Aluminum wiring 13 Plasma-TEOS CVD NSG film 14 Ozone-TEOS CVD NSG film

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-4-61335 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) H01L 21/316

Claims (4)

(57) [Claims] In forming an insulating film of a semiconductor device by chemical vapor deposition, a base surface is treated with a processing fluid containing an organic compound, then the base surface is treated with plasma, and then the insulating film is chemically treated. A method for manufacturing a semiconductor device, wherein the method is formed by vapor phase growth. 2. The method according to claim 1, wherein the insulating film is formed by chemical vapor deposition using tetraethoxysilane as a raw material. 3. The method according to claim 1, wherein the processing fluid containing the organic compound is an alcohol having 5 or less carbon atoms. 4. A method for manufacturing a semiconductor device, wherein the plasma treatment is performed by using annimore plasma or nitrogen plasma.