JP3133857B2 - 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, the present invention relates to a method for manufacturing a semiconductor device which is excellent in both the embedding property into a step and the flattening.

[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. As the CVD method, a plasma CVD method, a normal pressure CVD method, a reduced pressure CVD method, a pressurized CVD method, a photo-excited CVD method and the like have been conventionally 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, with the increase in integration and density of VLSI devices, there is also a strong demand for an insulating film used as a final protective film to improve its flatness and film quality which affects device reliability. I have. 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 gap between steps is reduced depending on the surface condition of the base. The embedding property between wirings) is significantly deteriorated. In particular, the CVD method using TEOS and ozone as source gases has disadvantages such as a decrease in the density of an insulating film to be formed, an increase in an etch rate, and an increase in a leak current, depending on the formation conditions of a base. This may result in failure to obtain good insulation properties. In addition, the film formation rate is dependent on the underlying layer, and the degree of film formation is different between a portion having a dense step pattern and a portion having a sparse step pattern, and the step on the substrate is disadvantageously increased. further,
In the case of a step pattern having an aspect ratio of the step 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 "Tech" published in 1989
As described in “Nacal Digest Electron Devices Meeting”, p. 669, a method has been proposed in which an underlayer is plasma-treated and then an organosilane-CVD film is formed.
However, in this method, the dependence 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 a method of manufacturing a semiconductor device according to the present invention, when 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, and this processing is performed. Forming a first insulating film on the base surface by chemical vapor deposition, performing a plasma treatment on the surface of the first insulating film, and thereafter forming a second insulating film by chemical vapor deposition. It is assumed that.

By treating the underlayer surface with a fluid containing an organic compound such as methanol or ethanol,
Organic compounds are uniformly adsorbed on the base surface, and ozone and TE
The embedding property in the process of forming the insulating film can be further improved by CVD using OS as a source gas. The fluid treatment containing the 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 the steps is improved, but the difference in film forming speed due to the step pattern tends to increase, and therefore the flatness of the whole wafer is improved. There is a need. On the other hand, as described above, in the manufacturing method in which the plasma treatment is performed before the CVD film is formed, the difference in the 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 insufficient. When the step is 1.5 or more, voids are generated.

For this reason, in the present invention, the first insulating film is formed by the CVD method after performing the fluid treatment on the base surface with the organic compound. In the base surface treated with the organic compound, the insulating film is sufficiently buried in a portion having a high aspect ratio, and the insulating film is formed relatively thick. on the other hand,
In portions where the aspect ratio is low, the insulating film is formed relatively thin because the deposition rate is low. Next, plasma irradiation is performed on the surface of the first insulating film, and then a second insulating film is formed. Since the surface of the first insulating film has no effect of the treatment with the organic compound, the effect of the plasma irradiation is sufficiently exhibited. Therefore, in the process of forming the second insulating film, the first insulating film is formed at a substantially uniform film forming rate over the entire surface of the substrate. As a result, it is possible to further improve the filling property between steps in a portion having a high aspect ratio, and to further improve the flatness of the entire silicon substrate.

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 compounds pyridine, quinoline, pyrrole, piperidine, piperazine, morpholine, 2-pyrrolidinone,
-Methyl-2-pyrrolidinone In the present invention, the undercoating treatment with one kind of such organic compounds or the simultaneous or sequential treatment with two or more kinds of organic compounds can be performed. 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) has a high vapor pressure, and can form an insulating film with good characteristics,
Particularly preferred. 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.

Further, an RF or microwave plasma source can be used as a plasma source used for the plasma processing, and ammonia, nitrogen,
Hydrogen, oxygen, or a mixed gas thereof can be used. In particular, ammonia plasma is extremely effective.

[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 cross-sectional views showing a silicon substrate in a series of steps of a method of manufacturing a semiconductor device according to the present invention. In this example, an example in which an insulating film is formed over a first wiring will be described.

As shown in FIG. 2A, a BPSG film 12 having a thickness of 6000.degree. Is formed on a silicon substrate 11, and an aluminum wiring 13 having a height of 1 .mu.m is further formed thereon with a line width of 0.5 .mu.m and a space width of 0.5. A plasma-TEOS CVD NSG film 14 was formed to a thickness of 3000 mm on the BPSG film and the aluminum wiring. The film forming conditions for the plasma-TEOS CVD NSG film 14 were as follows: a film forming temperature of 350 ° C., a film forming pressure of 2.2 Torr,
OS is supplied at a rate of 1.8 ml / min, oxygen gas is supplied at a rate of 4.0 ml / min, and RF power is 400 KHz, 500 W and 13.56 MH
A total of 1 kW of z and 500 W was used, and the film formation time was 20 seconds.
The thickness of the plasma-TEOS CVD NSG film 14 is
Although it is 3000 mm above the surface, only about 1000 mm 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 1000 rpm, followed by drying at 2000 rpm for 60 seconds. Next, the silicon wafer is carried into the reaction chamber shown in FIG. 1, and the first ozone-TEOS CVD NSG film 15 is
The film was formed to a thickness of about 3000 mm. In this specification, the gas flow rate indicates a flow rate in a standard state at 0 ° C. and 1 atm.

[0022]

[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

Ozone-TEOS CVD formed in this manner
The NSG film 15 smoothly fills a narrow space between the aluminum wirings 13 and has good step coverage. Even if the first ozone-TEOS CVD NSG film 15 is formed, the effect of the ethanol treatment still exists on the surface of the silicon substrate.

Next, the silicon wafer is mounted in a plasma processing apparatus, and the surface of the first ozone-TEOS CVD NSG film 15 is subjected to plasma processing. Ammonia is used as the processing gas, the processing temperature is 400 ° C, the processing pressure is 5 Torr, and the RF
The power was 200 W (13.56 MHz) and the processing time was 10 seconds.

Then, the first ozone-TEOS CVD NSG film 15
The second ozone-TEOS CVD NSG film 16 under the same conditions as the deposition of
Is formed to a thickness of 5000-10000 mm. At this time, the effect of plasma processing is effectively provided over the entire processing surface of the silicon substrate, and the ozone-TEOS CVD NSG film is already buried smoothly between the aluminum wirings having a high aspect ratio. In addition, the second ozone-TEOS CVD NSG film can be formed at a uniform film forming rate over the entire surface of the silicon substrate. As a result, a high-quality insulating film having no voids and a low moisture content can be formed over the entire surface of the silicon substrate. In addition, the insulating film formed in this way has excellent moisture absorption resistance, and there is no possibility that cracks will be generated in post-processing, so that device characteristics can be improved.

The present invention is not limited to the embodiment described above, but can be variously modified. 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.
Cu, Mo, W, Ti, TiN, TiW or alloys thereof can also be used.

Further, in the above-described embodiment, the ozone-TEOS CVD NSG film is formed after performing the ethanol treatment. However, the mixed gas of ozone and TEOS supplied to the reaction chamber has TOP (trimethylphosphate) and TMB ( trimethylb
Ozone-TEOS CVD PSG by adding phosphorus and boron alkoxide gas as dopant
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 TMOS,
OMCTS, HMDS, TMCTS, SOB, DADBS, SOP, etc. can also be used.

[0029]

As described above, according to the present invention, the underlying surface is treated with a processing fluid containing an organic compound, a first insulating film is formed, and then the second insulating film is subjected to plasma processing. Since the film is formed, it is possible to realize a method for forming an insulating film having excellent filling properties and flatness even with a step pattern having a high aspect ratio.

[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]

 1 Silicon substrate 12 BPSG film 13 Aluminum wiring 14 Plasma-TEOS CVD NSG film 15 Ozone-TEOS CVD NSG film

──────────────────────────────────────────────────続 き Continued on the front page (58) Fields 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, the surface of a base insulating film is treated with a processing fluid containing an organic compound, and the first surface of the treated base is coated with a first fluid.
Forming a second insulating film by chemical vapor deposition, then performing a plasma treatment on a surface of the first insulating film, and then forming a second insulating film by chemical vapor deposition. Production method. 2. When forming an insulating film of a semiconductor device by chemical vapor deposition, an underlayer surface is formed of an aliphatic monohydric alcohol, an aliphatic unsaturated monohydric alcohol, an aromatic alcohol, or an aliphatic saturated polyhydric alcohol. And one or more organic compounds selected from aldehydes, ethers, ketones, ketone alcohols, carboxylic acids, nitroalkanes, amines, acyl nitriles, acid amides, and heterocyclic compounds. Then, a first insulating layer film is formed on the treated base surface by chemical vapor deposition, and then the surface of the first insulating film is subjected to plasma processing, and then the second insulating film is formed by chemical vapor deposition. A method for manufacturing a semiconductor device, comprising: 3. The method for manufacturing a semiconductor device according to claim 1, wherein the plasma treatment of the insulating layer is a plasma treatment using ammonia gas. 4. 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, and a first insulating layer film is formed on the treated base surface by chemical vapor deposition. A method for manufacturing a semiconductor device, comprising: forming the first insulating film by plasma growth; performing plasma treatment using ammonia gas on the surface of the first insulating film; and then forming the second insulating film by chemical vapor deposition.