JPH06267937A - Forming method of silicate glass thin film - Google Patents

Abstract

PURPOSE:To provide a method of easily forming a silicate glass thin film or patterned silicate glass thin film. CONSTITUTION:1.0g of silicone resin comprising linear poly(siloxane) having C-O-Si coupling per unit monomer is melted in 9.0ml of methylisobutyl ketone to prepare the resin solution by filtrating it using a 0.2mum filter. Next, this resin solution is spin-coated on a 3-inch Si substrate and then baked for one minute at the temperature of 80 deg.C to form the title thin film. Next, this thin film is irradiated with hydrogen ions for eight minutes meeting the requirements for acceleration voltage of 0.3kV, ion current of 3.3mA and quantity of hydrogen ion irradiation of 3.5X10<16>each/cm<2>. Finally, a specimen is heated on a hot plate at 140 deg.C for five minutes to form the title silicate glass thin film.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor device and a method for forming a silicate glass thin film used in manufacturing the same.

[0002]

2. Description of the Related Art Conventionally, a silicate glass thin film (silicon oxide film) has been used as an interlayer insulating film or a protective film in a semiconductor device and its manufacturing process. Further, since silicate glass can have a large etching selection ratio with respect to polysilicon, it is also used as an etching mask in fine processing of a structure such as a gate electrode using polysilicon. Silicate glass as an etching mask is usually patterned using a photoresist.

Silicate glass can also be used as an etching mask for wiring processing using tungsten (W), copper (Cu) or the like, which is being studied as a wiring material in the future.

Conventionally, as a method of forming an insulating film such as a silicate glass thin film (SiO ₂ film), there are, for example, a method using coated glass (SOG), a CVD method, and a method using a silicone resin composition. is there. Hereinafter, each of the above methods will be briefly described.

In the method using SOG, a thin film of SOG is formed on the base by a spin coating method, and then this thin film is heat treated at a temperature of about 700 to 900 ° C. to form Si.
Convert to O ₂ . In the CVD method, a SiO ₂ film is formed using a silicon-based source gas. In the CVD method, usually 650 ° C
The SiO ₂ film is formed at a temperature of about 450 ° C., but the SiO ₂ film can be formed at a temperature of about 450 ° C. by selecting a source gas or the like. In the method using the silicone resin composition, a thin film of the silicone resin composition is formed on the base by spin coating similarly to SOG, and the formed thin film is cured to form an insulating film.

In the method using SOG and the CVD method,
Since it is necessary to process at a high temperature, there is a problem that Al wiring or the like is easily damaged. On the other hand, the method using the silicone resin composition includes the method using SOG and the CVD method.
The insulating film can be formed at a lower temperature than the method.
An insulating film having a thicker film thickness can be formed as compared with the CVD method.

[0007] As a silicone resin composition used for forming an insulating film or a passivation film, for example, Document 1: "JP-A-60-108839" discloses an organoladapolysiloxane and an unsaturated group. A photosensitive heat-resistant material comprising a bissilyl compound, which is a condensate with a sensitive silane, and a photosensitizer is disclosed. Further, Document 2: "JP-A-55-127023" discloses an ultraviolet-curable resin composition comprising an organosiloxane having an unsaturated group and an organic peroxide. Further, Document 3: "JP-A-62-215944" discloses a photosensitive heat-resistant composition comprising a mixture of alkylsilsesquioxane and aromatic bisazide. Further, Document 4: "JP-A-62-56956" and Document 5:
"JP-A-60-96942" discloses a heat-resistant silicone resin composition.

Further, as a conventional silicone resin composition which can be used as a resist for fine processing, for example, Reference 6: "JP-A-61-144639" discloses a siloxane oligomer, a quinonediazide compound and a phenol. A radiation sensitive resin composition comprising a resin is disclosed. This radiation resin composition can be used in a multi-layer resist process for performing fine and highly accurate lithography on a substrate to be processed having irregularities. Further, Document 7: "Japanese Patent Laid-Open No. 63-16623" and Document 8:
In Japanese Patent Laid-Open No. 63-14432, it is proposed to use polylada-organosiloxane as an intermediate layer of a three-layer resist and to use the lower layer resist as an etching mask when etching with oxygen plasma.

[0009]

However, when the silicone resin composition described in the above-mentioned references 1 to 5 is cured to form an insulating film or the like, an organic group remains in the side chain of the polymer after curing. . Therefore, this organic group may be thermally decomposed during high temperature treatment and may damage the thin film.

When the silicone resin composition disclosed in Documents 6 to 8 is cured to form a resist, the formed resist contains a quinonediazide compound and a phenol resin in addition to the siloxane oligomer. Inevitably, the silicon (Si) content will decrease. Therefore, the insulating film obtained by curing each of the silicone resin compositions described above has an SO
Plasma resistance is inferior to that of a silicate glass thin film (SiO ₂ film) containing no carbon component formed by the G and CVD methods.

In the meantime, the inventor of the present application discloses in Reference 9: "Japanese Patent Application No. 4-017588" a silicone resin having an alkoxy group bonded to the side chain of Si of polysiloxane and an acid generator. A radiation-sensitive resin composition containing the same is proposed. In this resin composition, the following (3)
As shown in the formula, when Si has a functional group having a C—O bond such as a t-butoxy group bonded thereto, the C—O bond is cleaved by an acid to remove the carbon component from the polymer. Get burned. Then, the inventor of this application continued to conduct tests and studies and found out that a silicate glass thin film containing no carbon component could be formed by utilizing a reaction in which a C—O bond is cleaved by an acid. It was

Accordingly, it is an object of the present invention to provide a method for easily forming a silicate glass thin film or a patterned silicate glass thin film.

[0013]

[Chemical 2]

[0014]

In order to achieve this object, according to the method for forming a silicate glass thin film of the present invention,
A step of forming a thin film of a silicone resin of linear or ladder-like poly (siloxane) having a C--O--Si bond for each monomer unit on a base, and the entire surface of the thin film or selected It is characterized by including a step of irradiating a part of the film with cations and a step of heating the thin film irradiated with the cations.

Further, a step of forming a thin film of a silicone resin composed of a linear or ladder-shaped poly (siloxane) having a C--O--Si bond for each monomer unit on a base,
Irradiating the entire surface or a selected portion of the thin film with cations while heating the thin film.

Preferably, the linear poly (siloxane) is represented by the following formula (1), and the ladder poly (siloxane) is represented by the following formula (2): And the functional group R in the formula (2) is selected from the group consisting of hydrogen, tert-butyl, 1-phenethyl, 1-methyl-1-phenethyl, cyclohexen-2-yl and t-butoxycarbonyl. At least one kind of functional group is preferable.

[0017]

[Chemical 1]

The heating temperature is preferably 60 ° C. or higher. This is because the heating time can be shortened.

[0019]

When a functional group such as an alkoxy group is bonded to poly (siloxane), the C--O bond connecting the functional group and poly (siloxane) can be cleaved with an acid. It is considered that the acid that cleaves the C—O bond may be any acid that belongs to the so-called Lewis acid. Document 9 mentioned above
In the technique proposed by the inventor of the present invention, the C—O bond is cleaved as a Lewis acid triggered by the coordination of hydrogen ions generated from the acid generator. As the chemical species causing such cleavage, cations including hydrogen ions can be used.

Therefore, in the present invention, since a thin film of silicone resin (hereinafter also referred to as a resin film) formed on the base is directly implanted with cations and heat treatment,
An elimination reaction that cleaves the C—O bond is triggered. Since cations are directly driven into the resin film without using an acid generator,
There is an advantage that the decomposed product of the acid generator does not remain in the thin film as a carbon component.

Furthermore, by implanting cations into the resin film while performing the heat treatment, the silicate glass thin film can be formed in one step after forming the resin film.

Therefore, by irradiating the entire surface of the thin film (resin film) of the silicone resin composition with cations, it is possible to form a silicate glass thin film on the entire surface of the underlayer, and it is possible to selectively form the resin film. By irradiating with cations, a patterned silicate glass thin film can be formed.

[0023]

EXAMPLES Examples of the method for forming a silicate glass thin film of the present invention will be described below. Numerical conditions such as the materials used and the amounts thereof, the processing time, the processing temperature, and the film thickness mentioned in the following description are only suitable examples within the scope of the present invention. Therefore, it is obvious that the present invention is not limited to the following examples.

First Example As a linear poly (siloxane) having a C--O--Si bond for each monomer unit, a silicone made of poly (siloxane) represented by the following formula (3): 1.0 g of the resin was dissolved in 9.0 ml of methyl isobutyl ketone, which was dissolved in
The resin solution was prepared by filtering with a 2 μm filter. This resin solution is spin coated on a 3 inch Si plate as a base,
A thin film is formed by heating (baking) at a temperature of 80 ° C. for 1 minute. However, one inch is about 2.54 cm.

Next, the thin film of the obtained silicone resin is irradiated with cations. In this example, a Si substrate on which this thin film was formed was mounted as a sample in a hydrogen ion shower device (manufactured by ELIONIX Co., Ltd.), and the acceleration voltage was 0.3 kV and the ion current was 3.3 mA for 8 minutes. This thin film is irradiated with hydrogen ions. The amount of hydrogen ion irradiation is 3.5 × 10 ¹⁶ ions / cm ² .

Next, after the irradiation with hydrogen ions, the sample was taken out from the hydrogen ion shower device and heated at 140 ° C. with a hot plate.
The silicate glass thin film is formed by baking at 5 ° C. for 5 minutes.

When the silicate glass thin film formed in the first example was analyzed by IR spectroscopy, C-H expansion and contraction of 2960 cm ^-1 before hydrogen ion irradiation, 1395 and 1965 cm were observed.
It was confirmed that the absorption derived from the organic group such as C-C stretch of t-butyl of ^-1 disappeared. From this, it is considered that the silicate glass thin film formed in this example is converted into a complete inorganic film. Thus, the silicate glass thin film can be easily formed by using the apparatus used in the usual semiconductor manufacturing process.

[0028]

[Chemical 3]

Second Example The same resin solution as the resin solution prepared in the first example was spin-coated on a 3-inch Si substrate, and the temperature was kept at 80 ° C. for 1 minute.
And a thin film is formed.

Next, the baked sample is mounted in a hydrogen ion shower apparatus, and the formed thin film is irradiated with hydrogen ions for 4 minutes under the conditions of an accelerating voltage of 3.0 kV and an ion current of 12 mA. . Hydrogen ion irradiation dose is 2.8 × 10
¹⁷ pieces / cm ² .

Next, after the irradiation of hydrogen ions, the sample was taken out from the hydrogen ion shower apparatus and heated at 140 ° C. with a hot plate.
The silicate glass thin film is formed by baking at 5 ° C. for 5 minutes.

When the silicate glass thin film formed in the second embodiment was analyzed by IR spectroscopy, C-H expansion and contraction of 2960 cm ^-1 before irradiation with hydrogen ions, 1395, 1365 cm.
It was confirmed that the absorption derived from the organic group such as C-C stretch of t-butyl of ^-1 disappeared. From this, it is considered that the silicate glass thin film formed in this example is converted into a complete inorganic film.

Third Embodiment The same resin solution as the resin solution prepared in the first embodiment is spin-coated on a 3-inch Si substrate, and is applied at a temperature of 80 ° C. for 1 minute.
And a thin film is formed.

Next, this baked sample is mounted in a hydrogen ion shower apparatus, and the formed thin film is irradiated with hydrogen ions for 4 minutes under the conditions of an acceleration voltage of 3.0 kV and an ion current of 12 mA. . Hydrogen ion irradiation dose is 2.8 × 10
¹⁷ pieces / cm ² .

Next, after the irradiation with hydrogen ions, the sample was taken out from the hydrogen ion shower apparatus and heated at 60 ° C. in a hot plate.
And baked for 30 minutes to form a silicate glass thin film.

When the glass thin film formed in the third embodiment was analyzed by IR spectroscopy, it was found to be 296 before hydrogen ion irradiation.
C-H stretch of 0 cm ^-1, t of 1395,1365Cm ^-1
It was confirmed that absorption derived from an organic group such as C-C expansion and contraction of -butyl disappeared. From this, it is considered that the silicate glass thin film formed in this example is converted into a complete inorganic film.

Fourth Embodiment The same resin solution as the resin solution prepared in the first embodiment is spin-coated on a 3-inch Si substrate, and is applied at a temperature of 80 ° C. for 1 minute.
And a thin film is formed.

Next, this baked sample was mounted in a hydrogen ion shower apparatus, and the sample was heated to an accelerating voltage of 3.0 kV, an ion current of 12 mA, and in the fourth embodiment at a temperature of 120 ° C. The formed thin film is irradiated with hydrogen ions for 4 minutes to form a silicate glass thin film. The amount of hydrogen ion irradiation is 2.8 × 10 ¹⁷ ions / cm ² .

When the glass thin film formed in the fourth embodiment was analyzed by IR spectroscopy, it was found to be 296 before hydrogen ion irradiation.
C-H stretch of 0 cm ^-1, t of 1395,1365Cm ^-1
It was confirmed that absorption derived from an organic group such as C-C expansion and contraction of -butyl disappeared. From this, it is considered that the silicate glass thin film formed in this example is converted into a complete inorganic film.

Fifth Embodiment The same resin solution as the resin solution prepared in the first embodiment is spin-coated on a 3-inch Si substrate, and the temperature is kept at 80 ° C. for 1 minute.
And a thin film is formed.

Next, in the fifth embodiment, the sample subjected to this baking is mounted in a focused ion beam exposure apparatus (manufactured by Seiko Denshi Co., Ltd.), an acceleration voltage of 50 kV, an ion current of 2 mA, and a beam current of 2 mA. A test pattern was drawn by irradiating the formed thin film with gallium ions as cations under the condition that the diameter of the film was 0.063 μm.

Next, the sample on which the test pattern was drawn was taken out from the focused ion beam exposure apparatus, and was hot-pressed.
Baking at 140 ° C for 5 minutes. Next, the baked sample was developed with isoamyl acetate for 30 seconds, and
The pattern of the silicate glass thin film was obtained by baking at 0 ° C for 5 minutes.
Form

When a 10 μm square pad-shaped portion of the pattern of the silicate glass thin film formed in the fifth embodiment was analyzed by microscopic IR spectroscopy, it was found to be 2960 before hydrogen ion irradiation.
C-H stretching of cm ^-1, the 1395,1365cm ^-1 t-
It was confirmed that absorption derived from an organic group such as C-C expansion and contraction of butyl disappeared. From this, it is considered that the silicate glass thin film formed in this example is converted into a complete inorganic film.

Further, when the resolution of the pattern was examined by using an SEM measuring device (S6100 (trade name) manufactured by Hitachi Ltd.), a line and space of 60 nm having a cycle of 120 nm was resolved. I found out.

In the above-mentioned embodiments, hydrogen ions and gallium ions have been described as examples of cations, but in the present invention, the same effect can be expected even if other cations are used.

[0046]

According to the method of forming a silicate glass thin film of the present invention, a silicate glass thin film containing no carbon component can be easily formed from a silicon resin thin film. Therefore, the silicate glass thin film can be easily formed at a lower temperature than the method using the SOG and CVD methods.

After forming a thin film of silicone resin, a silicate glass thin film can be formed in one step by implanting cations into the thin film while performing heat treatment.

If hydrogen ions or gallium ions are used as the cations for irradiating the silicon resin thin film, a silicate glass thin film can be easily formed by using an apparatus used in a usual semiconductor manufacturing process. can do. Further, when the method of the present invention is used in an insulating film forming step or a passivation film forming step in, for example, LSI manufacturing, a wiring pattern can be formed at a lower temperature than when using a CVD method or the like. For this reason, there is no risk of damaging the wiring due to high temperature, and therefore migration of the wiring can be prevented. As a result, the reliability of the device can be improved. The method of the present invention also includes
Since an ultrafine lithography technique using a focused ion beam can be applied, it is suitable for use in manufacturing a quantum effect device.

Claims (4)

[Claims] 1. A step of forming a thin film of a silicone resin composed of a linear or ladder-shaped poly (siloxane) having a C—O—Si bond for each monomer unit on a base, and the thin film. A method of forming a silicate glass thin film, comprising: a step of irradiating the entire surface or a selected part of the cation with cations; and a step of heating the thin film irradiated with the cations. 2. A step of forming a thin film of a silicone resin composed of linear or ladder-shaped poly (siloxane) having a C—O—Si bond for each monomer unit on a base, and the thin film. Irradiating cations to the entire surface or a selected part of the thin film while heating the thin film, the method for forming a silicate glass thin film. 3. The method for forming a silicate glass thin film according to claim 1, wherein the linear poly (siloxane) is represented by the following formula (1), and the ladder-shaped poly (siloxane) is used. ) Is represented by the following formula (2), and the functional group R in the formulas (1) and (2) is hydrogen, tert-butyl, 1-phenethyl, 1-methyl-1-phenethyl, cyclohexene-2-. At least one selected from the group of functional groups of yl and t-butoxycarbonyl.
A method for forming a silicate glass thin film, which comprises more than one kind of functional group. [Chemical 1] 4. The method for forming a silicate glass thin film according to claim 1 or 2, wherein the cations are hydrogen ions or gallium ions.