JP3217528B2 - Method for forming silicate glass thin film - Google Patents

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 for manufacturing the same.

[0002]

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

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

Conventionally, as a method of forming an insulating film such as a silicate glass thin film (SiO ₂ film), for example, a method using coated glass (SOG), a CVD method, or 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 a base by a spin coating method, and then this thin film is heat-treated at a temperature of about 700 to 900 ° C.
To O ₂ reduction. In the CVD method, an 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. However, if a raw material gas or the like is selected, the SiO ₂ film can be formed at a temperature of about 450 ° C. In the method using the silicone resin composition, a thin film of the silicone resin composition is formed on a base by spin coating as in the case of 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 the Al wiring and the like are easily damaged. On the other hand, the method using the silicone resin composition includes a method using SOG and a method using CVD.
The insulating film can be formed at a lower temperature than the method,
An insulating film with a larger thickness can be formed as compared with the CVD method.

As a silicone resin composition used for forming an insulating film or a passivation film, for example, Reference 1: Japanese Patent Application Laid-Open No. 60-10839 discloses an organoladder polysiloxane 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. Reference 2: JP-A-55-127523 discloses an ultraviolet-curable resin composition comprising an organosiloxane having an unsaturated group and an organic peroxide. Reference 3: JP-A-62-215944 discloses a photosensitive heat-resistant composition comprising a mixture of an alkylsilsesquioxane and an aromatic bisazide. Reference 4: "JP-A-62-56956" and Reference 5:
JP-A-60-96942 discloses a heat-resistant silicone resin composition.

Further, as a conventional silicone resin composition usable as a resist for fine processing, for example, reference 6: Japanese Patent Application Laid-Open No. 61-144439 discloses a siloxane oligomer, a quinonediazide compound and a phenol. A radiation-sensitive resin composition comprising a resin is disclosed. This radiation resin composition could be used in a multi-layer resist process for performing lithography on a processed substrate having irregularities finely and with high precision. Reference 7: “JP-A-63-16623” and Reference 8:
Japanese Unexamined Patent Publication (Kokai) No. 63-14432 proposes using polyladada-organosiloxane as an intermediate layer of a three-layer resist and using it as an etching mask when etching a lower resist with oxygen plasma.

[0009]

However, when the silicone resin compositions described in the above-mentioned references 1 to 5 are cured to form an insulating film or the like, the organic groups remain on the side chains of the cured polymer. . Therefore, there is a possibility that the organic group is thermally decomposed during the high-temperature treatment and damages the thin film.

Further, when a resist is formed by curing the silicone resin composition disclosed in References 6 to 8, a quinonediazide compound or a phenol resin other than the siloxane oligomer is contained in the formed resist. Inevitably, the silicon (Si) content decreases. Therefore, the insulating film obtained by curing each of the above-described silicone resin compositions is made of SO
The plasma resistance is inferior to a silicate glass thin film (SiO ₂ film) containing no carbon component formed by using the G and CVD methods.

By the way, the inventor of the present application disclosed in Patent Document 9: “Japanese Patent Application No. 4-017588” that a silicone resin having an alkoxy group bonded to the Si side chain of polysiloxane and an acid generator. And a radiation-sensitive resin composition containing the same. In this resin composition, the following (3)
As shown in the formula, when a functional group having a CO bond such as a t-butoxy group is bonded to Si, the bond is cut by an acid to remove the carbon component from the polymer. I will Therefore, the inventors of the present application have continued testing and research and found that a silicate glass thin film containing no carbon component can be formed by utilizing a reaction in which a C—O bond is cut by an acid. Was.

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

[0013]

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[0014]

In order to achieve this object, according to the method of forming a silicate glass thin film of the present invention,
Forming a linear or ladder-like poly (siloxane) silicon resin thin film having a C—O—Si bond for each monomer unit on the underlayer; The method includes a step of irradiating a part with cations and a step of heating the thin film irradiated with the cations.

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 an underlayer;
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 functional groups of hydrogen, tert-butyl, 1-phenethyl, 1-methyl-1-phenethyl, cyclohexen-2-yl and t-butoxycarbonyl. At least one or more functional groups are preferred.

[0017]

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The heating temperature is desirably 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 a poly (siloxane), the C—O bond connecting the functional group and the poly (siloxane) can be cleaved by an acid. It is considered that the acid that cleaves the C—O bond may be one that belongs to a so-called Lewis acid. Reference 9 mentioned above
In the technique proposed by the inventor, the coordination of hydrogen ions generated from the acid generator as a Lewis acid triggers the cleavage of the CO bond. As a chemical species that causes such cleavage, a cation such as a hydrogen ion can be used.

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

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

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

[0023]

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

FIRST EXAMPLE As a linear poly (siloxane) having a CO--Si bond for each monomer unit, a silicone resin comprising a poly (siloxane) represented by the following formula (4): 1.0 g was dissolved in 9.0 ml of methyl isobutyl ketone.
A resin solution was prepared by filtration through a μm filter. This resin solution was spin-coated on a 3-inch Si plate as a base,
Heating (baking) at a temperature of 0 ° C. for 1 minute forms a thin film. However, one inch is about 2.54 cm.

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

Next, after irradiation with hydrogen ions, the sample was taken out of the hydrogen ion shower device, and heated at a hot plate.
Baking is performed at 5 ° C. for 5 minutes to form a silicate glass thin film.

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

[0028]

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Second Embodiment The same resin solution as that prepared in the first embodiment is spin-coated on a 3-inch Si substrate and heated at a temperature of 80 ° C. for 1 minute.
To form a thin film.

Next, the baked sample was set in a hydrogen ion shower, and the formed thin film was 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 amount is 2.8 × 10
¹⁷ pieces / cm ² .

Next, after the irradiation with hydrogen ions, the sample was taken out of the hydrogen ion shower device, and heated at 140 ° C using a hot plate.
Baking is performed at 5 ° C. for 5 minutes to form a silicate glass thin film.

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

Third Embodiment The same resin solution as that prepared in the first embodiment was spin-coated on a 3-inch Si substrate and heated at a temperature of 80 ° C. for 1 minute.
To form a thin film.

Next, the baked sample is set in a hydrogen ion shower, 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 amount is 2.8 × 10
¹⁷ pieces / cm ² .

Next, after irradiation with hydrogen ions, the sample was taken out of the hydrogen ion shower device and heated at 60 ° C. using a hot plate.
Bake for 30 minutes to form a silicate glass thin film.

The glass thin film formed in the third embodiment was analyzed by IR spectroscopy.
C-H stretch of 0 cm ^-1, t of 1395,1365Cm ^-1
It was confirmed that absorption derived from an organic group such as CC stretching of -butyl disappeared. From this, it is considered that the silicate glass thin film formed in this example was converted into a complete inorganic film.

Fourth Embodiment The same resin solution as that prepared in the first embodiment is spin-coated on a 3-inch Si substrate and heated at a temperature of 80 ° C. for one minute.
To form a thin film.

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

The glass thin film formed in the fourth embodiment was analyzed by IR spectroscopy.
C-H stretch of 0 cm ^-1, t of 1395,1365Cm ^-1
It was confirmed that absorption derived from an organic group such as CC stretching of -butyl disappeared. From this, it is considered that the silicate glass thin film formed in this example was converted into a complete inorganic film.

Fifth Embodiment The same resin solution as that prepared in the first embodiment is spin-coated on a 3-inch Si substrate and heated at a temperature of 80 ° C. for one minute.
To form a thin film.

Next, in the fifth embodiment, the baked sample was set in a focused ion beam exposure apparatus (manufactured by Seiko Electronics Co., Ltd.), and the acceleration voltage was 50 kV, the ion current was 2 mA, and the beam diameter was 0.063 μm. The test pattern was drawn by irradiating the formed thin film with gallium ions as cations under the conditions described in (1).

Next, the sample on which the test pattern was drawn was taken out of the focused ion beam exposure apparatus, and the hot play was performed.
Bake at 140 ° C for 5 minutes. Next, the baked sample was developed with isoamyl acetate for 30 seconds.
Bake at 0 ° C for 5 minutes to pattern the silicate glass thin film.
To form

The 10 μm square pad-shaped portion of the pattern of the silicate glass thin film formed in the fifth embodiment was analyzed by micro IR spectroscopy, and it was found that the portion was 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 stretching of butyl disappeared. From this, it is considered that the silicate glass thin film formed in this example was converted into a complete inorganic film.

When the resolution of the pattern was examined using a SEM length measuring device (S6100 (trade name) manufactured by Hitachi, Ltd.), a line and space of 60 nm with a 120 nm cycle was resolved. I understood that.

In the above-described embodiments, hydrogen ions and gallium ions have been described as examples of cations. However, in the present invention, similar effects can be expected by using other cations.

[0046]

According to the method for 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. For this reason, a silicate glass thin film can be easily formed at low temperature compared with the method using SOG and CVD.

If a cation is implanted into the thin film while performing a heat treatment after the formation of the silicon resin thin film, a silicate glass thin film can be formed in one step.

Further, when hydrogen ions or gallium ions are used as 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. Also, when the method of the present invention is used in, for example, an insulating film forming step or a passivation film forming step in 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 possibility of damaging the wiring due to high temperature, so that migration of the wiring can be prevented. As a result, the reliability of the device can be improved. Also, the method of the present invention includes:
Since ultrafine lithography technology using a focused ion beam can be applied, it is suitable for use in manufacturing a quantum effect device.

Claims (4)

(57) [Claims] 1. A step of forming a thin film of a linear or ladder-like poly (siloxane) silicone resin having a C—O—Si bond for each monomer unit on an underlayer; A step of irradiating hydrogen ions or gallium ions as cations to the entire surface or a selected part of the film, and a step of heating the thin film irradiated with the cations. Forming method. 2. A step of forming, on a base, a thin film of a linear or ladder-like poly (siloxane) silicone resin having a C—O—Si bond for each monomer unit, Irradiating cations to the entire surface or a selected portion of the thin film while heating the 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): ) Is represented by the following formula (2), wherein 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 member selected from the group consisting of yl and t-butoxycarbonyl functional groups.
A method for forming a silicate glass thin film, wherein the silicate glass thin film has at least two kinds of functional groups. Embedded image 4. The method for forming a silicate glass thin film according to claim 2, wherein the cation is a hydrogen ion or a gallium ion.