JP2001022089A - Method for working insulating film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an insulating film pattern of a good worked shape with good dimensional controllability. SOLUTION: This method includes toll owing processes. A mask material 3 containing an organosilicon compound having an Si-Si or Si-C bond in the principal chain is formed on an insulating film. The organic group of the organosilicon compound is degraded. A resist film is formed on the mask material. The formed resist film is patternwise exposed and developed to form a resist pattern 5. The resist pattern is transferred to the mask material to form a mask material pattern. The mask material pattern is transferred to the insulating film.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for processing an insulating film, and more particularly, to a method for processing an insulating film in manufacturing a semiconductor device.

[0002]

2. Description of the Related Art In a method of manufacturing a semiconductor device, there are many processing steps of an insulating film. Usually, in these processing steps, a photosensitive resin film called a resist film is formed on an insulating film, pattern exposure is performed on the photosensitive resin film, a resist pattern is formed through a developing step, and the resist pattern is further etched with an etching mask. Is used to dry-etch the insulating film.

However, it is necessary to reduce the thickness of the resist film in order to provide the necessary resolution, exposure latitude, or focus latitude during pattern exposure. The required film thickness cannot be secured.

In order to solve this problem, there is a method of forming a mask material on an insulating film which is more resistant to etching than a resist film, and sequentially transferring the pattern from the resist pattern to the mask material and then to the film to be processed. Have been.

Conventionally, as a mask material used in this method, 1) polysilane, 2) organic resin such as novolak resin, 3) carbon, 4) metal such as aluminum and tungsten have been used.

[0006]

However, in the mask materials 1) and 2) described above, the roughened side walls occur during the etching of the insulating film, and the roughened side walls are transferred to the insulating film. There is a problem that can not be obtained.

Further, the mask material of the above 3) and 4) is CV
Since the film is formed by the method D or the sputtering method, there is a problem that the film forming process is complicated and the process cost is increased as compared with the mask materials 1) and 2) which can be formed by the coating method. .

[0008] The present invention has been made in view of the above problems,
Using a mask material that can be formed by a coating method and does not cause surface roughness when etching a film to be processed, it is possible to obtain an insulating film pattern with a good processing shape with good dimensional controllability. It is intended to provide a processing method.

[0009]

In order to solve the above-mentioned problems, the present invention provides a semiconductor device comprising:
Or a step of forming a mask material containing an organic silicon compound having a bond between silicon and carbon, a step of decomposing organic groups of the organic silicon compound, a step of forming a resist film on the mask material, Pattern exposure and development to form a resist pattern, transferring the resist pattern to the mask material to form a mask material pattern, and transferring the mask material pattern to the insulating film. And a method for processing an insulating film.

In the method of processing an insulating film, the decomposition of the organic group of the organic silicon compound is performed by using a mask material of 300 to 1
Annealing can be performed at a temperature of 200 ° C. or by irradiating the mask material with an electron beam. In this case, the annealing is desirably performed in an atmosphere having an oxygen concentration of 1% or less. Annealing is performed at 1 × 10 ⁻¹ T
It is desirable to be performed under a reduced pressure atmosphere of orr or lower.

According to the insulating film processing method of the present invention configured as described above, an organic group in an organic silicon compound having a silicon-silicon or silicon-carbon bond in its main chain is decomposed to form an inorganic film. By modifying to, it is possible to prevent the side wall roughness generated in the mask material during the etching of the insulating film,
As a result, it is possible to obtain an insulating film pattern without side wall roughness.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A method for processing an insulating film according to an embodiment of the present invention will be specifically described below with reference to the drawings. 1 and 2 are cross-sectional views illustrating a method for processing an insulating film according to an embodiment of the present invention.

First, as shown in FIG. 1A, a film to be processed 2 is formed on a wafer substrate 1. The processing target film 2 is not particularly limited as long as it is an insulating film. For example, a silicon oxide film, a silicon nitride film, a silicon oxynitride film, a spin-on glass, a blank material used in manufacturing a mask, or the like is used. Can be mentioned.

Next, as shown in FIG. 1 (b), an organic silicon compound having a bond between silicon and silicon in the main chain, or an organic silicon compound in the main chain, is formed on the film 2 to be processed formed on the wafer substrate 1. A mask material 3 containing an organic silicon compound having a bond between silicon and carbon is formed.

The thickness of the mask material 3 is 50 to 5000 nm.
Is preferably within the range. The reason is that the film thickness is 50
If it is less than 500 nm, when forming a pattern by light exposure, the reflected light from the underlying substrate cannot be sufficiently suppressed, and
If the thickness is larger than 0 nm, a significant difference in dimensional conversion occurs when the resist pattern is transferred to the mask material by the dry etching method.

The silicon content in the mask material is preferably 5 to 65 parts by weight based on 100 parts by weight of the mask material. The reason is that when the amount is less than 5 parts by weight, the mask material is hardly etched when the resist pattern is transferred to the mask material, which causes an increase in a dimensional conversion difference. On the other hand, 6
If the amount is 5 parts by weight or more, the organic silicon compound becomes difficult to dissolve in the solvent, and it becomes difficult to obtain a coating film by a coating method.

The method of forming the mask material may be either a method of applying a solution or a method of forming a film by a gas phase method such as a CVD method (chemical vapor deposition method). Preferably, it is formed. The reason is that the coating method has a simpler process than the CVD method and can reduce the process cost.

Here, a method of forming a mask material by a coating method will be described in detail. First, an organic silicon compound having a bond between silicon and silicon in its main chain is dissolved in an organic solvent to prepare a solution material.

Examples of the organic silicon compound having a bond between silicon and silicon in its main chain include, for example, a compound represented by the general formula (SiR ₁₁₎
R ₁₂ ), wherein R ₁₁ and R ₁₂ are a hydrogen atom or a carbon atom
And 20 to 20 substituted or unsubstituted aliphatic hydrocarbons or aromatic hydrocarbons. ).

The polysilane may be a homopolymer or a copolymer, and may have a structure in which two or more polysilanes are bonded to each other via an oxygen atom, a nitrogen atom, an aliphatic group, or an aromatic group. Hereinafter, specific examples of the organic silicon compound will be described.

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[0035]

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[0036]

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In the above formula, m and n represent positive integers.
The molecular weight of these compounds is not particularly limited, but is preferably from 200 to 100,000. The reason is,
If the molecular weight is less than 200, the mask material will be dissolved in the solvent of the resist, while if it exceeds 100,000, the organic solvent will not be easily dissolved and it will be difficult to prepare a solution material.

The organic silicon compound is not limited to one kind, and several kinds of compounds may be mixed. In addition, a thermal polymerization inhibitor for improving storage stability as needed, an adhesion enhancer for improving adhesion to the silicon-based insulating film, and preventing light reflected from the silicon-based insulating film into the resist film. Dyes that absorb ultraviolet light, polymers that absorb ultraviolet light such as polysulfone and polybenzimidazole, conductive substances, substances that generate conductivity when exposed to light or heat, or cross-linking agents that can crosslink organosilicon compounds. You may.

Examples of the conductive substance include organic sulfonic acids, organic carboxylic acids, polyhydric alcohols, polyhydric thiols (eg, iodine and bromine), SbF ₅ , PF ₅ , BF ₅ , and S
nF _{5 and the} like.

Examples of the substance that becomes conductive by energy such as light or heat include carbon clusters (C ₆₀ , C ₇₀ ), cyanoanthracene, dicyananothracene, triphenylpyrium, tetrafluoroborate, tetracyanoquinodimethane, and tetracyanoquinodimethane. Examples include cyanoethylene, phthalimide triflate, perchloropentacyclododecane, dicyanobenzene, benzonitrile, trichloromethyltriazine, benzoyl peroxide, benzophenonetetracarboxylic acid, and t-butyl peroxide.

More specifically, the following formulas [2-1] to [2-1]
06].

[0042]

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The crosslinking agent is added to crosslink the organosilicon compound to prevent mixing of the resist and the organosilicon compound, and to improve heat resistance.

As the crosslinking agent, an organic substance having a multiple bond can be used. The organic substance having a multiple bond is
A compound having a double bond or a triple bond, more specifically, a compound having a vinyl group, an acrylic group, an aryl group, an imide group, an acetylenyl group, or the like. The organic substance having such a multiple bond may be any of a monomer, an oligomer, and a polymer.

The organic substance having such a multiple bond causes an addition reaction with the Si—H bond of the organic silicon compound by heat or light to crosslink the organic silicon compound. Note that the organic substance having a multiple bond may be self-polymerized. Specific examples of the organic substance having a multiple bond are shown below.

[0055]

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The organic solvent is not particularly limited.
For example, acetone, methyl ethyl ketone, methyl isobutyl ketone, ketone solvents such as cyclohexanone, methyl cellosolve, methyl cellosolve acetate, cellosolve solvents such as ethyl cellosolve acetate, ethyl lactate, ethyl acetate, butyl acetate, ester solvents such as isoamyl acetate, Examples thereof include alcohol solvents such as methanol, ethanol, and isopropanol, and anisole, toluene, xylene, and naphtha.

A coating material is prepared by the above method, and a solution material is applied on the film to be processed 2 by, for example, a spin coating method, and then heated to evaporate the solvent, thereby forming the mask material 3. Then, an organic group in the organic silicon compound is decomposed by performing annealing using a hot plate, an electric furnace, a thermal radiation furnace, infrared irradiation, or the like.

The degree of decomposition of the organic group is at least 0.98 with the area absorption intensity of the infrared absorption spectrum of the organic group as 1.
It is preferable to perform the following. The reason is,
If it exceeds 0.98, the decomposition of the organic group is insufficient, and the mask material is etched non-uniformly at the time of etching the film to be processed, and the surface of the mask material is roughened.

The distribution of the decomposition state of the organic group in the film thickness direction is not limited.

The annealing temperature is preferably in the range of 300 to 1200 ° C. If the annealing temperature is lower than 300 ° C., the decomposition reaction does not proceed sufficiently. On the other hand, if the annealing temperature is higher than 1200 ° C., the mask material is hardly etched when the resist pattern is transferred to the mask material, and the dimensional conversion difference increases. Will be invited.

The annealing time is preferably in the range of 10 seconds to 10 hours. If the annealing time is less than 10 seconds, the decomposition reaction does not sufficiently proceed, while if the annealing time is more than 10 hours, the oxidation proceeds,
When the resist pattern is transferred to the mask material, the mask material is less likely to be etched, resulting in an increase in the dimensional conversion difference.

The atmosphere during the annealing has an oxygen concentration of 1%,
More preferably, the concentration is 1000 ppm or less. If the oxygen concentration is 1% or more, oxidation proceeds, making it difficult for the mask material to be etched, resulting in an increase in dimensional conversion difference.

The pressure during annealing is 1 × 10 ^-1 T
orr or less is preferable. The pressure during annealing is 1 × 10 ^-1
When the degree of vacuum is equal to or higher than Torr, the degree of vacuum is low, the decomposed carbon component remains in the mask material, and the mask material is not easily etched when the resist pattern is transferred to the mask material, resulting in an increase in dimensional conversion difference. I will.

The decomposition of the organic group can also be performed by irradiating the mask material with an electron beam. The irradiation amount of the electron beam is not particularly limited, but is usually 0.01 μC / cm ^2.
〜1 × 10 ⁶ mC / cm ² is preferable. When the irradiation amount of the electron beam is less than 0.01 μC / cm ² , decomposition hardly occurs. On the other hand, when the irradiation amount exceeds 1 × 10 ⁶ mC / cm ² , the irradiation amount is too strong and oxidation occurs.

The irradiation of the electron beam and the heating may be performed simultaneously. In that case, the heating temperature is not particularly limited. The electron beam irradiation atmosphere is the same as the annealing atmosphere described above.

Next, a resist pattern is formed on the mask material 3. First, as shown in FIG.
A resist solution is applied thereon and subjected to a heat treatment to form a resist film 4. If the thickness of the resist film 4 is reduced,
As a result, the exposure latitude, focus latitude, or resolution at the time of exposure can be improved. Therefore, the thickness of the resist film 4 is preferably as thin as possible so long as the mask material 3 can be etched with good dimensional controllability.
The range of m is preferred.

The type of the resist is not particularly limited, and a positive type or a negative type can be selected and used according to the purpose. Specifically, as the positive resist, for example, a resist (IX-770, manufactured by Nippon Synthetic Rubber Co., Ltd.) composed of naphthoquinonediazide and a novolak resin, a polyvinylphenol resin protected with t-BOC and an acid generator Chemically amplified resist (APEX-
E, manufactured by Shipley Co., Ltd.). Examples of the negative resist include, for example, a chemically amplified resist (SNR200, manufactured by Shipley Co., Ltd.) comprising polyvinylphenol, a melamine resin and a photoacid generator, and a resist (RD) comprising polyvinylphenol and a bisazide compound.
-2000N, manufactured by Hitachi Chemical Co., Ltd.), but is not limited thereto.

These resist solutions are put on the mask material 3.
For example, after coating by a spin coating method, a dip method, or the like, the resist film 4 is formed by heating to vaporize the solvent.

The exposure light source is not limited, and includes, for example, ultraviolet light, X-ray, electron beam, ion beam and the like. As the ultraviolet light, a mercury lamp g-line (43
6 nm), i-line (365 nm), or XeF (wavelength = 3
51 nm), XeCl (wavelength = 308 nm), KrF
(Wavelength = 248 nm), KrCl (wavelength = 222 n)
m), ArF (wavelength = 193 nm), F ₂ (wavelength = 15
Excimer laser such as 1 nm).

Then, as shown in FIG. 1D, the exposed resist film 4 is developed with an alkali developing solution such as TMAH or choline to form a resist pattern 5.

If necessary, in order to reduce the multiple reflection in the resist film 4 that occurs when light exposure is performed, the upper antireflection film or the resist film 4 when electron beam exposure is performed. An upper antistatic film may be formed on the resist film 4 to prevent charge-up occurring therein.

Next, as shown in FIG. 2E, the resist material 5 can be transferred to the mask material 3 by dry etching the mask material 3 using the resist pattern 5 as an etching mask. Thereby, a mask material pattern 6 is obtained.

The etching method at this time is not particularly limited as long as fine processing is possible, such as reactive ion etching, magnetron type reactive ion etching, electron beam ion etching, ICP etching, or ECR ion etching. Never.

In order to maintain the selectivity with the resist, the power density applied to the electrode on which the wafer is placed is 10 W / cm
It is desirable to keep it to ² or less. The reason is that the etching of the mask material 3 is close to the chemical etching, so that the sputterability is increased, so that the etching rate of the resist is increased and the selectivity is prevented from being lowered.

In the case where an apparatus capable of independently generating plasma and generating bias is used, the bias is reduced for the above-described reason, and the power used for generating plasma is suppressed so that the number of ions does not become excessive. There is a need. Therefore, the power used for plasma generation is
It is desirable that the area of the wafer to be processed be suppressed to 10 W / cm ² or less.

The substrate temperature is preferably from 10 ° C. to 180 ° C. The reason is that if the temperature is lower than 10 ° C., the etching rate is low, and the throughput is reduced. If the temperature exceeds 180 ° C., the resist pattern is melted.

As the source gas, it is preferable to use a chlorine-based gas, ie, a gas containing chlorine atoms in molecules, or a bromine-based gas, ie, a gas containing bromine atoms in molecules.
Examples of the chlorine-based gas include CF ₃ Cl, CF ₂ Cl
₂ , CF ₃ Br, CCl ₄ , C ₂ F ₅ Cl ₂ , Cl ₂ ,
Examples of SiCl _4, BCl ₃ , and bromine-based gases include gases such as HBr. These chlorine gas and bromine gas may be mixed and used. By etching the mask material as described above, a high selectivity with respect to the resist can be obtained, and processing with high dimensional controllability can be performed.

Next, as shown in FIG. 2F, etching of the film to be processed 2 is performed using the resist pattern 5 and the mask material pattern 6 as an etching mask. As an etching method, for example, reactive ion etching,
There is no particular limitation as long as it can be finely processed, such as magnetron-type reactive ion etching, electron beam ion etching, ICP etching, or ECR ion etching.

In order to maintain the selectivity with respect to the resist or the mask material, it is desirable that the power density applied to the electrodes provided on the wafer be suppressed to 10 W / cm ² or less. The reason is to prevent the etching rate of the resist or the mask material from increasing due to the increase in the sputterability, thereby preventing the mask resistance from decreasing.

In the case where an apparatus capable of independently performing plasma generation and bias generation is used, the bias is reduced for the above-described reason, and the power used for plasma generation is suppressed so that the number of ions is not excessive. There is a need. Therefore, the power used for plasma generation is
It is desirable to suppress the area of the wafer to be processed to 10 W / cm ² or less.

After processing the mask material, the resist pattern 5 may be removed, and the film to be processed may be etched using only the mask material pattern 6 as an etching mask.

When processing an ultrafine film to be processed having a high aspect ratio, after processing the mask material, the resist on the mask material is removed by another device or the same device, and the aspect ratio at the time of processing is removed. Is preferably reduced. In this case, only the mask material pattern transferred by the resist is used as the etching mask, whereby the aspect ratio can be kept small, and the microloading effect can be suppressed.

By processing the processing target film 2 as described above, it is possible to prevent the side wall roughness from occurring in the mask material when the processing target film 2 is etched, and to obtain the processing target film pattern 7 having no side wall roughness. Will be possible. It is considered that the side wall roughness generated in the mask material is caused by uneven etching of the organic component and the inorganic component in the mask material, and is caused by thermal decomposition of the organic group in the organic silicon compound. It is considered that the ratio of the inorganic component increased and the etching proceeded uniformly.

Finally, an ashing process is performed to remove the resist pattern 5 and the mask material pattern 6, whereby a film pattern 7 to be processed can be obtained as shown in FIG.

[0094]

EXAMPLES Examples of the present invention will be described below, and the effects of the present invention will be described more specifically.

Example 1 First, as shown in FIG. 1A, a 500 nm-thick TEOS oxide film 2 was formed on a silicon wafer 1 by LPCVD as a film to be processed. Next, FIG.
As shown in (1), the mask material 2 was formed by the following methods (S1) to (S15). Each mask material was formed such that the film thickness after thermosetting became 150 nm.

(S1): A solution of a mask material is prepared by dissolving 10 g of the organosilicon compound represented by the formula (1-50) in 90 g of anisole, and the solution material is applied onto the film to be processed 2 by spin coating. To form a mask material 3,
Annealing was performed at 300 ° C. for 1 hour in a nitrogen atmosphere (oxygen concentration: 50 ppm or less, atmospheric pressure) using an electric furnace.

(S2): In (S1), annealing was performed at 500 ° C. for 1 hour.

(S3): In (S1), annealing was performed at 700 ° C. for 1 hour.

(S4): In (S1), annealing was performed at 900 ° C. for 1 hour.

(S5): 1200 ° C. in (S1)
For 1 hour.

(S6): In (S1), 1300 ° C.
For 1 hour.

(S7): In (S1), 1400 ° C.
For 1 hour.

(S8): A solution of a mask material is prepared by dissolving 10 g of the organosilicon compound represented by the formula (1-50) in 90 g of anisole, and applied to a film to be processed by a spin coating method. And annealed at 450 ° C. for 1 hour in the air using an electric furnace.

(S9): In (S8), annealing was performed in a nitrogen atmosphere (oxygen concentration: 2%).

(S10): In (S8), annealing was performed in a nitrogen atmosphere (oxygen concentration: 1%).

(S11): A solution of a mask material is prepared by dissolving 10 g of the organosilicon compound represented by the formula (1-50) in 90 g of anisole, and applied to a film to be processed by a spin coating method. And annealed at 450 ° C. for 1 hour in a reduced pressure atmosphere of 10 Torr using an electric furnace.

(S12): In (S11), 1 To
Annealing was performed at 450 ° C. for 1 hour in a reduced pressure atmosphere of rr.

(S13): In (S11), 1 × 1
Annealing was performed at 450 ° C. for 1 hour in a reduced pressure atmosphere of 0 ⁻¹ Torr.

(S14): In (S11), 1 × 1
Annealing was performed at 450 ° C. for 1 hour in a reduced pressure atmosphere of 0 ^-4 Torr.

(S15): In (S11), 1 × 1
Annealing was performed at 450 ° C. for 1 hour in a reduced pressure atmosphere of 0 ⁻⁶ Torr.

As a reference sample (R1),
The solution prepared in (S1) was applied on the film to be processed by spin coating so that the film thickness became 150 nm. At this time, the coating film was not heated.

Further, as a reference sample (R2),
In (S1), annealing was performed at 250 ° C. for 1 hour to form a mask material having a thickness of 150 nm. The above samples (R1), (R2), (S1) to (S15)
Are shown in Table 1 below.

[0113]

[Table 1]

The infrared absorption spectra of the mask material formed by the method of (S1) to (S15) and the reference sample formed by the method of (R1) or (R2) were measured.
The area intensity of the absorption peak due to the Si—CH ₃ bond seen near 3000 cm ⁻¹ was determined by heating (R
Table 2 below shows the results obtained by standardizing the strength in the case of 1) as 1.
Shown in

From Table 2 below, the absorption peak intensity does not change at an annealing temperature of 250 ° C. or less, but when annealing is performed at a temperature of 300 ° C. or more, the absorption temperature is attenuated regardless of the atmosphere during the annealing. It can be seen that the group has decomposed.

Next, a positive chemically amplified resist KRF M20G (manufactured by JSR) is applied on each mask material by spin coating, and then heated at 140 ° C. for 90 seconds using a hot plate. As shown in FIG. 1C, a resist film 3 was formed. The resist film thickness after heating is 300 nm.

Then, a reduction optical stepper using a KrF excimer laser as a light source (NA = 0.6, σ = 0.
After performing pattern exposure using 6), heating was performed at 140 ° C. for 90 seconds using a hot plate.

Subsequently, paddle development was performed for 30 seconds using 0.21 N tetraammonium hydroxyside to form a 0.15 μm line and space pattern as shown in FIG. 1 (d).

When the focus margin at the optimum exposure dose of 28 mJ / cm ² was examined, it was 0.6 μm, and a sufficient focus margin could be secured because the thickness of the resist was reduced.

Next, the resist pattern is etched
The mask material 2 is etched by using as a mask, and FIG.
As shown in (e), a mask material pattern 6 was formed.
Magnetron type etching equipment as etching equipment
Used, and a flow rate of 200 SCCM Cl as a source gas._TwoTo
Used, vacuum degree 75 mTorr, excitation power density 2 W / cm
^Two Etching was performed at a substrate temperature of 80 ° C.

For the determination of the etching time, end point detection by light emission was used, and overetching was performed by 50% with respect to the just time. The dimension of the resist pattern before etching is defined by X in FIG. 1 (c), and the dimension of the mask material pattern after etching is defined by Y in FIG. 1 (d), and the dimensional conversion difference (= Y− Table 2 below shows the results of measuring X).

As shown in Table 2 below, in each of (S1) to (S14), the mask material is processed within a permissible range of up to 7 to +7 nm, and does not substantially deviate from the resist pattern dimensions before etching. You can see that it was possible.

The etching of the mask material was stopped halfway and the selectivity of the mask material to the resist (= etching rate of mask material / etching rate of resist) was examined. The results are shown in Table 2 below.

From Table 2 below, it can be seen that all the mask materials are etched at a high selectivity of 1.5 times or more. As a result, it is considered that the shoulder of the resist pattern could be prevented from being dropped, and the mask material could be etched without deviation from the resist pattern dimensions.

When comparing the resist selectivity in (S1) to (S10), a decrease in resist selectivity is observed in (S6) to (S9). This is due to the annealing temperature in (S6) and (S7). (S8), (S9)
It is considered that the oxidation was excessively advanced because the oxygen concentration in the annealing atmosphere was too high, and the selectivity to resist decreased.

Further, comparing the selectivity with respect to the resist in (S11) to (S15), it can be seen that the selectivity significantly increases at a degree of vacuum of 1 × 10 ⁻¹ Torr or less. This is probably because carbon in the mask material volatilized by reducing the pressure.

Further, the formulas [1-1], [1-22],
Using the respective organosilicon compounds represented by the formulas [1-46], [1-47] and [1-115], the same as (S1) to (S15), (R1) and (R2) in Examples. A sample was prepared at the annealing temperature and in the annealing atmosphere, and the degree of decomposition of the organic silicon compound was measured by infrared absorption spectrum, and the mask material was etched.

As a result, the same tendency as in the case of the compound represented by the formula [1-50] was observed with respect to the annealing temperature, the degree of decomposition of the organic silicon compound with respect to the annealing atmosphere, and the resist selectivity. From the above experimental results, it can be said that the annealing temperature is generally 1200 ° C. or less, the atmosphere during the annealing is preferably 1% or less in oxygen concentration, and the vacuum degree is 1 × 10 ⁻¹ Torr or less.

Next, as shown in FIG. 2F, the film to be processed was etched using the resist pattern and the mask material pattern as an etching mask. A magnetron-type reactive ion etching apparatus was used as an etching apparatus, and a flow rate ratio of 10/100/200 SC was used as a source gas.
Using C ₄ F ₈ / CO / Ar of CM, excitation power 700
The etching was performed under the conditions of W, a degree of vacuum of 40 mTorr, and a substrate temperature of 20 ° C.

For the determination of the etching time, end point detection by light emission was used, and overetching was performed by 50% with respect to the just time.

Subsequently, after the etching, as shown in FIG. 2G, the remaining mask material pattern was removed by ashing to obtain an insulating film pattern 7. Ashing is performed using a downflow ashing device as an ashing device and O ₂ / with a flow ratio of 1000/140 SCCM as a source gas.
Using CF ₄ , excitation power 1000 W, vacuum degree 40 mTo
rr, the substrate temperature was 250 ° C.

Observation of the cross-section processing shape using a scanning electron microscope reveals that the line and space are processed with good anisotropy as shown in FIG. 2 (g).
When observed from above, no roughness was observed on the side wall of the insulating film pattern as shown in FIG.

Further, the width (= Z) of the insulating film pattern was measured, and a dimensional conversion difference (= Z−Y) generated by etching the film to be processed was calculated. The measurement results are shown in Table 2 below. From Table 2 below, the dimensional conversion difference is within the allowable range of ~ 7 to +
It is within the range of 7 nm, which indicates that the film to be processed could be processed with good dimensional control.

Next, (S1) to (S1)
A mask material is formed by each method of (S15), and a resist film is formed by the above-mentioned method, and each film is etched under the condition of etching the above-mentioned film to be processed, and each etching rate and surface roughness of the film surface are examined. Was. Table 2 below shows the mask resistance obtained from the etching rate of the resist film and the etching rate of the mask material.

From Table 2 below, it can be seen that the mask material according to the present invention has a higher resistance than the resist film, so that the etching mask composed of the mask material pattern and the resist pattern has less shoulder drop. As a result, it is considered that the processed film was etched with good anisotropy and good dimensional controllability.

[0136]

[Table 2]

FIGS. 6A and 6B show cross-sectional photographs of the mask material (S1) and the resist film taken at a magnification of 50,000 times using a scanning electron microscope.

As shown in FIGS. 6A and 6B, the mask material (S
It can be seen that although the surface of 1) is not rough, the surface of the resist film is rough. (S2)-(S1
No surface roughness was observed for the mask material formed by the method 5), and it was found that the mask material formed by the method of the present invention was less likely to have surface roughness than the resist film. Therefore, even if the resist pattern side wall is roughened during the etching of the film to be processed, it is considered that the side wall roughness generated in the resist pattern was not transferred to the film to be processed because the mask material which is hard to be roughened is used. .

Example 2 First, as shown in FIG. 1A, a 500 nm-thick TEOS oxide film 2 was formed on a silicon wafer 1 by LPCVD as a film to be processed. Next, FIG.
As shown in (1), the mask material 2 was formed by the following methods (S16) to (S19). Each mask material was formed such that the film thickness after curing became 150 nm.

(S16): After the mask material 2 was formed by the method of (R2) in Example 1, an electron beam with an irradiation amount of 10 μC / cm ^{2 was} irradiated using an electron beam irradiation device.

(S17): In (S16), the irradiation amount of the electron beam was set to 100 μC / cm ² .

(S18): In (S16), the electronic
Irradiation dose of 1000 μC / cm ²And

(S19): In (S16), the irradiation amount of the electron beam was set to 10000 μC / cm ² .

The samples (R1) and (R1)
2) and Table 3 below show the conditions of (S6) to (S19).

[0145]

[Table 3]

The infrared absorption spectrum of the mask material formed by the methods (S16) to (S19) was measured. Three
Table 4 below shows the results obtained by standardizing the area intensity of the absorption peak due to the Si—CH ₃ bond observed near 000 cm ⁻¹ with the intensity in the case of no electron beam irradiation (R1) as 1.

From Table 4 below, it can be seen that the absorption peak of the organic group was reduced by performing the electron beam irradiation as compared with the case of forming by the method (R1) without performing the electron beam irradiation. It can be seen that it has been decomposed.

Next, the film to be processed was processed in the same manner as in Example 1, and the evaluation results are summarized in Table 4 below. From Table 4 below, it can be seen that, similarly to Example 1, the film to be processed is processed with good dimensional controllability.

(S16)-(S1)
9) A mask material was formed by each method, and a resist film was formed by the above-mentioned method, and each film was etched under the conditions for etching the above-mentioned film to be processed. . Table 4 below shows the mask resistance obtained from the etching rate of the resist film and the etching rate of the mask material.

From Table 4 below, it can be seen that the mask material according to the present invention is:
It can be seen that there is little shoulder drop of the etching mask composed of the mask material pattern and the resist pattern because the resistance is higher than the resist film. As a result, it is considered that etching was performed with good anisotropy and good dimensional control.

Further, when a surface photograph of the mask material taken at a magnification of 50,000 times was observed using a scanning electron microscope, it was found that the surface material was the same as that of the mask material formed by the method of Examples (S1) to (S15). It can be seen that there is no roughening in.
Therefore, even if the resist pattern side wall roughness occurs during the etching of the film to be processed, it is considered that the side wall roughness generated in the resist pattern was not transferred to the film to be processed because the mask material that does not easily cause the side wall roughness was used. .

[0152]

[Table 4]

Comparative Example First, as shown in FIG. 4A, a TEOS oxide film 12 was formed on a silicon wafer 11 in the same manner as in the example. Next, as shown in FIG.
The mask material 13 was formed by the methods 1) and (R2).

Next, as shown in FIGS. 4C and 4D,
A resist film 14 is formed on each mask material 13 in the same manner as in the embodiment.
Was formed, and a resist pattern 15 was formed. afterwards,
As shown in FIG. 5E, the mask material 13 was etched using the resist pattern 15 as an etching mask to form a mask material pattern 16 in the same manner as in the example.

Next, as shown in FIG. 5 (f), in the same manner as in the embodiment, using the resist pattern 15 and the mask material pattern 16 as an etching mask,
Was etched.

Next, as shown in FIG. 5G, the resist pattern 15 and the mask material pattern 16 were removed by ashing in the same manner as in the example, and an insulating film pattern 17 was obtained. Ashing was performed under the same conditions as in the example.

When the insulating film pattern 17 after the processing was observed from above using a scanning electron microscope,
As shown in (b), roughness of the side wall was observed, and a favorable processed shape was not obtained.

When etching was performed in the same manner as in the example using the mask blanket for etching the film to be processed, both (R1) and (R2) were as shown in FIG. 6 (b). Surface roughness was observed. Therefore, it is considered that the roughness generated on the mask material side wall during the etching of the insulating film was transferred to the film to be processed.

As is clear from the comparison between this comparative example and the example, the thermal decomposition of the organic group in the mask material eliminates the surface roughness of the mask material, and allows the insulating film to be processed in a good processed shape. Is now possible.

[0160]

As described above in detail, according to the present invention, an organic group in an organic silicon compound having a silicon-silicon or silicon-carbon bond in a main chain constituting a mask material is decomposed. By inorganic modification, it is possible to prevent side wall roughness from occurring in the mask material during the etching of the insulating film, and as a result, it is possible to obtain an insulating film pattern without side wall roughness.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a processing sequence of an insulating film according to an embodiment of the present invention in the order of steps.

FIG. 2 is a sectional view showing a process of processing an insulating film according to an embodiment of the present invention in the order of steps.

FIG. 3 is a top view of an insulating film processed by a processing method according to the present invention and a processing method according to a comparative example.

FIG. 4 is a cross-sectional view illustrating a process of processing an insulating film according to a comparative example in the order of steps.

FIG. 5 is a cross-sectional view illustrating a process of processing an insulating film according to a comparative example in the order of steps.

FIG. 6 is an electron micrograph of a surface when a mask material according to the present invention and a mask material according to a comparative example are etched under the etching conditions of an insulating film.

[Explanation of symbols]

 1, 11 wafer substrate 2, 12 film to be processed 3, 13 mask material 4, 14 resist 5, 15 resist pattern 6, 16 mask material pattern 7, 17 insulating film pattern

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H01L 21/312 H01L 21/30 573 5F058 // G03F 7/40 521 21/302 F C08L 83:16 (72 ) Inventor Shuji Hayase 1 Toshiba-cho, Komukai-Toshiba-cho, Kawasaki-shi, Kanagawa F-term in the Toshiba R & D Center (reference) 2H096 AA25 CA02 HA23 4F006 AA42 AB39 AB76 BA01 BA06 BA08 CA03 CA08 DA03 EA03 4J035 HA02 HA05 JA01 JA02 JB01 JB02 LB16 5F004 AA02 BA11 BA13 BA14 BA17 BA20 CA03 CA04 DA04 DA05 DA06 DA07 DA10 DA11 DA13 DB03 DB24 EB07 5F046 NA12 5F058 AC03 AF04 AG01 AH01 BD04 BF07 BF25

Claims (5)

[Claims] A step of forming a mask material containing an organic silicon compound having a bond of silicon and silicon or silicon and carbon in a main chain on an insulating film; a step of decomposing an organic group of the organic silicon compound; Forming a resist film on the mask material; forming a resist pattern by performing pattern exposure and development on the resist film; transferring the resist pattern to the mask material to form a mask material pattern And a step of transferring the mask material pattern to the insulating film. 2. The method according to claim 1, wherein the decomposition of the organic group of the organosilicon compound is performed by annealing the mask material at a temperature of 300 to 1200 ° C. or irradiating the mask material with an electron beam. Item 4. The method for processing an insulating film according to Item 1. 3. The method according to claim 1, wherein the decomposition of the organic group of the organic silicon compound is performed so that the degree of decomposition is at least 0.98 or less, where the area absorption intensity of the infrared absorption spectrum of the organic group is 1. The method for processing an insulating film according to claim 1. 4. The method according to claim 2, wherein the annealing is performed in an atmosphere having an oxygen concentration of 1% or less. 5. The method according to claim 2, wherein the annealing is performed in a reduced pressure atmosphere of 1 × 10 ⁻¹ Torr or less.