JP3249718B2 - Fluorine-containing silicon network polymer, its insulating film and its manufacturing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a silicon network polymer containing fluorine in a polymer structure, an insulating film thereof, and a manufacturing method thereof.

[0002]

2. Description of the Related Art Macromolecules 26, 2111 (1)
993), Jpn. J. Appl. Phys. 34, L452
(1995) discloses a silicon network polymer and a method for synthesizing the same. The synthesis method uses a Wurtz type reaction in which a trihalogenated silane is condensed with sodium metal.

Further, Japanese Patent Application Laid-Open No. 3-258834 discloses a linear fluorinated polysilane and a method for synthesizing the same. This also uses a Wurtz type reaction.

However, conventionally, a fluorine-containing silicon network polymer has not been synthesized. The reason is,
The compounds that can be used for the Wurtz type reaction are limited, and the biggest cause is, in particular, that there is no raw material for the fluorine-containing silicon network polymer.

In electronic devices represented by semiconductors, there is a strong demand for lowering the dielectric constant of an insulating layer in order to improve performance.
In order to meet this demand, Plasma by CVD
A TEOS film, a SiOF film and the like have been studied. However, a CVD apparatus is required to form these films, and the productivity of the films is low. From such a viewpoint, a method of forming an insulating layer by a coating method has conventionally been required.

[0006] Appl. Phys. , 77, 2796 (1
995), Jpn. J. Appl. Phys. , 34, L452
(1995) describes a method for forming a SiO film using a silicon network polymer. However, when these fluorine-free silicon network polymers are used, the intended low-dielectric insulating layer cannot be obtained.

The linear fluorine-containing polysilane disclosed in Japanese Patent Application Laid-Open No. 3-258834 has low stability. Appl. Phys. , 77, 2796 (19
95), Jpn. J. Appl. Phys. , 34, L452
(1995) cannot be used as an insulating layer.

[0008] Organic SOG, one of the polysiloxane type coating materials, provides an insulating layer having a relatively low dielectric constant.
The stress at the time of curing is large, and only a submicron film can be formed. Further, there is a problem that workability is poor and cracks are easily generated.

Although the development of fluoroorganic SOG is considered to be advantageous in terms of dielectric constant, it has not been reported yet. This is probably because the fluorination reaction is difficult.

In order to streamline the manufacturing process of a semiconductor device, a photosensitive insulating thin film material is strongly required.

A photosensitive polymer material represented by a photosensitive polyimide meets this demand to some extent. However, it is inevitable that the miniaturization of semiconductors is further advanced. However, conventional photoresists containing an organic material as a main component have strong self-absorption of 350 nm or less.
It is not suitable for lithography using light having a wavelength shorter than 0 nm.

The light source has a wavelength of 300 n.
m Deep UV or KrF (248 nm) or A
Excimer lasers such as r (193n) are promising. Attention has been focused on photolithography in which these light sources are combined with polysilane having sensitivity in this region.

However, the pattern formation method using these polysilane resists also employs a wet development method using a solvent or a dry etching method using a reactive gas in the development process [SPIE, Vol 146].
6, 211 (1991)].

[0014]

SUMMARY OF THE INVENTION An object of the present invention is to provide a novel fluorine-containing silicon network polymer, an insulating film of the polymer, and a method for producing the same under the above-mentioned circumstances.

Another object of the present invention is to provide an electronic device such as a semiconductor or an integrated circuit using the polymer insulating film.

[0016]

The gist of the present invention for solving the above problems is as follows.

(1) General formula

[0018]

Embedded image

Wherein R is an alkyl group or aromatic group containing at least one fluorine, and n is an integer.
A fluorine-containing silicon network polymer having a molecular weight of 1,000 to 100,000.

(2) Tetrahalogenated silane of the formula [1] and organic halide of the formula [2]

[0021]

Embedded image SiX ₄ ... [1] RZ ... [2] (where R is an alkyl group or aromatic group containing at least one fluorine, X is bromine, iodine, chlorine, and Z is bromine, iodine, chlorine) And may be different from each other.) In the fluorine-containing silicon network polymer.

(3) An insulating film composed of the fluorine-containing silicon network polymer.

In the above-mentioned fluorine-containing silicon network polymer, a counter electrode whose one electrode is a magnesium electrode is inserted into a mixed solution of a tetrahalogenated silane of the formula [1] and an organic halide of the formula [2]. Then, a voltage is applied between the counter electrodes to cause a reaction, and the reaction solution is applied to a substrate to form a thin film.

The above thin film is prepared in the presence of oxygen by 200 to 1000
It can also be obtained by heat treatment at ℃.

The thin film can be obtained by irradiating the thin film with an electromagnetic wave in the presence of oxygen.

Further, the thin film is obtained by irradiating the thin film with an electromagnetic wave in the presence of oxygen and then performing a heat treatment at 200 to 1000 ° C.

The thin film can be formed directly on a substrate of an electronic device by coating or the like.

By reacting the tetrahalogenated silane of the present invention with a fluorinated organic halide in the presence of a magnesium electrode, a fluorinated silicon network polymer which could not be obtained conventionally can be obtained, and the polymer has a low dielectric constant. It gives an insulating film with excellent characteristics at a high rate.

Advantages of the above reaction include a wide range of application of the reaction and a high yield.

First, in the synthesis method, a fluorinated organic halide reacts with magnesium to produce a Grignard reagent. Next, the generated Grignard reagent reacts with the tetrahalogenated silane to generate a trihalogenated organic silane.
Finally, condensation of the trihalogenated organosilane yields the desired fluorinated silicon network polymer. Accordingly, the above-mentioned fluorinated organic halide may be any one that forms a Grignard reagent, such as an alkyl fluorinated halide and an allyl fluorinated halide.

The yield of the produced polymer is higher than that of the conventional wurtz type reaction. The content of R in the polymer can be adjusted by changing the ratio of SiX ₄ to RZ.

For the synthesis of polysilane having a fluorinated alkyl group, see Polymer Preprints, Japan, 4
0, (7), 2191 (1991) and JP-A-3-25.
No. 8834, which relates to a linear polysilane and differs from the present invention.

The fluorinated silicon network polymer obtained by this reaction is described in J. Am. Appl. Phys. , 77,
2796 (1995), it is possible to form an oxide film and pattern it. The relative permittivity of the obtained oxide film is lower than that of a conventional silicon network polymer, which is advantageous for improving the performance of an electronic device.

A film obtained by oxidizing a fluorinated silicon network polymer has a small film stress and is suitable for use as an insulating layer of a semiconductor.

[0035]

The operation of the present invention will be described with reference to an example in which a photo-oxidative crosslinking reaction of a fluorinated silicon network polymer is used.

A fluorinated silicon network polymer dissolved in an organic solvent such as toluene is coated on a substrate on which a pattern is to be formed by a method such as spin coating and dried to form a uniform thin film of the fluorinated silicon network polymer.

Next, in the presence of oxygen,
When irradiated with an electromagnetic wave of 150 nm, Si-
The Si bond is broken, and is bonded to oxygen to form a structure containing a large amount of SiO skeleton in the exposed portion.

In this process, volume expansion occurs by incorporating oxygen into the polysilane structure. Then, in vacuum 2
When the heat treatment is performed at 00 to 1000 ° C., the unexposed portion of the fluorinated silicon network polymer is decomposed and dissipated from the substrate, or becomes a semiconductor thin film such as SiC or amorphous Si. If the temperature is lower than 200 ° C., the silicon network polymer is stable, and decomposition or conversion to SiC, amorphous Si, or the like does not proceed.

On the other hand, since the exposed portion has an Si—O skeleton having high heat resistance, it remains on the substrate even after the heat treatment.
This results in a negative pattern. If the temperature is higher than 1000 ° C., the exposed portion volatilizes, so that a film cannot be obtained.

When a similar process was applied to the conventional linear polysilane, the polysilane film disappeared from the inorganic substrate on the exposed and unexposed portions due to the above heat treatment. This is because the linear polysilane has low heat resistance.

In the synthesis of the fluorinated silicon network polymer of the present invention, a part of the tetrahalogenated silane can be replaced with a trihalogenated silane within a range that does not impair the properties.

In the present invention, the exposure step can be omitted particularly when the formation of a fine pattern is not required. For example, by subjecting the formed network polysilane to heat treatment in oxygen at 100 to 1000 ° C., an insulating thin film having excellent film quality can be obtained.

By photooxidizing the fluorinated silicon network polymer in oxygen, an excellent insulating thin film can be obtained only by the exposure step. Needless to say, such a photoreaction and a thermal reaction can be selectively used or combined as necessary.

The volume expansion due to the oxidation reaction can be controlled by the degree of the photo-oxidation reaction and the degree of the thermal oxidation reaction, and the degree of the thermal decomposition reaction of the organic group. It is also possible to make it.

In using the formed film, the mechanical properties of the film become very important. When the resulting film contracts during the formation process, tensile film stress is generated, the film is brittle, and a crack is generated by a slight trigger. On the other hand, when the film to be formed expands during the formation process, cracks are less likely to occur due to contraction of film stress, which is extremely advantageous in processing the film.

The film obtained by the present invention and having a structure containing a large amount of SiO skeleton can control the film stress in this way, and is an optimum material for each process. From the viewpoint of the crack resistance of the film, it is desirable to expand the film in the forming step or to minimize shrinkage.

The thin film obtained by the present invention is excellent in coating characteristics and film characteristics, and thus, there is no particular limitation on the formed film thickness. In the case of spin coating, the thin film having a thickness of 0.1 to 10 μm is used. In this case, a homogeneous film can be easily obtained.

[0048]

Next, the present invention will be described in detail with reference to examples.

Example 1 A 200 ml tetrahydrofuran solution of 0.4 mol of tetrachlorosilane and 0.4 mol of pentafluorobromobenzene was dropped into a flask equipped with a magnesium working electrode and a nickel counter electrode and purged with nitrogen using a dropping funnel. And dropped under ice-cooling. The Grignard reaction between tetrachlorosilane and pentafluorobromobenzene was carried out under solvent reflux.

Next, a reaction was carried out at 0 ° C. for 3 hours while sweeping the potential between the above-mentioned electrodes at a rate of 50 mV / sec between −3 V and 0 V. The reaction solution was poured into 100 ml of methanol, and then reprecipitated and purified with 500 ml of distilled water. The yield was 51.3%.

In FIG. 1, the weight average molecular weight in terms of polystyrene measured by GPC was 14,240.

FIG. 1 shows a GPC chart of the obtained poly (pentafluorophenylsilin).

FIG. 2 shows a Raman spectrum of the polymer. It can be seen that the spectrum of the Si—Si bond is broad and networked. The broadening of the vibrational spectrum of networked polysilanes is described in ACS Symposium Series, 579, 408.
(1994).

FIG. 3 shows a visible ultraviolet absorption spectrum of the obtained polymer. The absorption of a pentafluorophenyl group is observed at around 270 nm.

The XPS (X-ray) of the polymer obtained in Table 1 was used.
The measurement results of Photoelectron Spectroscopy (X-ray photoelectron spectroscopy) are shown. Fluorine, oxygen and carbon signals are observed,
It can be seen that the desired network polymer has been obtained. It is considered that the observed oxygen atom was introduced by the reaction with methanol when the reaction was stopped.

[0056]

[Table 1]

Example 2 Synthesis was performed in the same manner as in Example 1 except that pentafluorobromobenzene was replaced with nonafluoroiodobutane, to obtain poly (nonafluorobutylsilin) with a yield of 55%.

Example 3 Pentafluorobromobenzene was replaced with heptafluoroiodopropane. Example 1
Was synthesized in the same manner as described above to obtain poly (heptafluoropropylsilin) with a yield of 50%.

Example 4 A 20% by weight toluene solution of poly (pentafluorophenylsilin) obtained in Example 1 was spin-coated on a silicon wafer. This is 500
After exposing for 10 minutes in the presence of oxygen using a W mercury lamp, heat treatment was performed at 500 ° C. for 1 hour in a vacuum.

As a result, an insulating thin film having a thickness of 1.5 μm was obtained.

When the above insulating thin film was observed with a microscope, no cracks due to shrinkage of the thin film in the heating process were observed.
It was confirmed that a very dense and homogeneous film was formed. The relative dielectric constant of this film measured at a frequency weight of 1 KHz was 2.7.

Example 5 A 20% by weight toluene solution of poly (heptafluoropropylsilin) obtained in Example 3 was spin-coated on a silicon wafer. This is 500
After exposing for 10 minutes in the presence of oxygen using a W mercury lamp, heat treatment was performed at 400 ° C. for 1 hour in vacuum. As a result, an insulating thin film having a thickness of 1.5 μm was obtained.

When the above insulating thin film was observed with a microscope, no cracks due to shrinkage of the thin film during the heating process were observed.
It was confirmed that a very dense and homogeneous film was formed. The relative dielectric constant of this film measured at a frequency of 1 KHz is 2.
It was 5.

Example 6 A 30% by weight toluene solution of poly (pentafluorophenylsilin) obtained in Example 1 was spun on a silicon wafer on which an aluminum pattern having an L / S = 1/1 μm and a height of 1 μm was formed. It was coated to form a film having a thickness of 2 μm.

After the film was treated in air at 400 ° C. for 1 hour, the surface of the coating film was flattened by chemical mechanical polishing (CMP). Even after polishing, no cracks or the like occurred in the film, and a tough insulating thin film was obtained. The withstand voltage of this film is 700V
/ Μm and the relative dielectric constant was 2.7.

FIG. 4 is a schematic sectional view of an aluminum two-layer wiring board obtained by repeating the above steps.

The aluminum wiring 2 and the aluminum via 3 were formed by a conventional etching method using aluminum deposited by a sputtering method. By forming the insulating film 4 and the aluminum wiring 2 on the silicon wafer 1 on which the active area is formed, a high-speed responsive integrated circuit can be obtained.

[0068]

The novel fluorinated silicon network polymer of the present invention has excellent coating properties and film properties,
By using the polymer as an insulating film of an electronic device or the like, a high-performance electronic device with a high response speed can be provided.

[Brief description of the drawings]

FIG. 1 is a GPC chart of the poly (pentafluorophenylsilin) of the present invention.

FIG. 2 is a Raman spectrum diagram of the poly (pentafluorophenylsilin) of the present invention.

FIG. 3 is a view showing a visible ultraviolet absorption spectrum of the poly (pentafluorophenylsilin) of the present invention.

FIG. 4 is a schematic cross-sectional view of an aluminum two-layer wiring substrate formed on a silicon wafer.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Silicon wafer, 2 ... Aluminum wiring, 3 ... Aluminum via, 4 ... Insulating film.

────────────────────────────────────────────────── ─── Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI H01L 21/90 P (56) References JP-A-6-263878 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C08G 77/60

Claims (11)

(57) [Claims] 1. A compound of the general formula Wherein R is an alkyl group or aromatic group containing at least one fluorine, and n is an integer.
A fluorine-containing silicon network polymer having a molecular weight of 00,000. 2. A tetrahalogenated silane of the formula [1] and an organic halide of the formula [2] (Where R is an alkyl group or aromatic group containing at least one fluorine, X is bromine, iodine, chlorine, Z is bromine,
Shows iodine and chlorine, which may be different from each other. The fluorine-containing silicon network polymer according to claim 1, wherein the fluorine-containing silicon network polymer is composed of a reactant with (a). 3. A compound of the general formula Wherein R is an alkyl group or aromatic group containing at least one fluorine, and n is an integer.
An insulating film of a fluorine-containing silicon network polymer having a molecular weight of 00,000. 4. A tetrahalogenated silane of the formula [1] and an organic halide of the formula [2] (However, R represents an alkyl group or an aromatic group containing at least one fluorine, X represents bromine, iodine, or chlorine, and Z represents bromine, iodine, or chlorine, and may be different from each other.) 2. The insulating film of a fluorine-containing silicon network polymer according to claim 1, wherein the insulating film comprises: 5. The insulating film of a fluorine-containing silicon network polymer according to claim 3, wherein the insulating film is a thin film irradiated with an electromagnetic wave in the presence of oxygen. 6. A tetrahalogenated silane of the formula [1] and an organic halide of the formula [2] (However, R is an alkyl group or aromatic group containing at least one fluorine, X is bromine, iodine or chlorine, and Z is bromine, iodine or chlorine and may be different from each other). A fluorine-containing silicon, wherein a counter electrode whose one electrode is a magnesium electrode is inserted, a voltage is applied between the counter electrodes to cause a reaction, and the reaction solution is applied to a substrate to form a thin film. Network polymer
Manufacturing method of insulating film . 7. The method according to claim 1, wherein the thin film is formed in the presence of oxygen at 200 to 100
The method for producing a fluorine-containing silicon network polymer insulating film according to claim 6, wherein the heat treatment is performed at 0 ° C. 8. The method for producing a fluorine-containing silicon network polymer insulating film according to claim 6, wherein the thin film is irradiated with an electromagnetic wave in the presence of oxygen. 9. The thin film is irradiated with electromagnetic waves in the presence of oxygen, and then heat-treated at 200 to 1000 ° C.
The method for producing a fluorine-containing silicon network polymer insulating film according to <1>. 10. The method for producing a fluorine-containing silicon network polymer insulating film according to claim 6, wherein said thin film is formed on an insulating inorganic substrate. 11. The insulating layer of a circuit board of an electronic device has the formula: Wherein R is an alkyl group or aromatic group containing at least one fluorine, and n is an integer.
An electronic device comprising a thin film of a fluorine-containing silicon network polymer having a molecular weight of 000,000.