JP2000049154A - Manufacture of silica-based film and manufacture of semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a silica-based film having a low dielectric constant and a method for manufacturing a semiconductor device, having the silica-based film which has low dielectric constant as an interlayer insulating film. SOLUTION: This method for manufacturing a silica-based film is featured by including the steps of coating a coating solution on a substrate to form a silica-based film and thereafter heating the film at a temperature increase rate of 60 deg.C per minute from a temperature of room temperature to 5.0 deg.C to a set temperature of 300-600 deg.C for setting the film. The method for manufacturing a semiconductor device includes a step of forming an interlayer insulating film by the silica-based film manufacturing method.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing a silica-based coating and a method for producing a semiconductor device using the same.

[0002]

2. Description of the Related Art In recent years, in the field of semiconductor manufacturing, with the miniaturization of devices, an increase in capacitance between wirings due to a high dielectric constant of an interlayer insulating film between wirings made of aluminum or the like, a signal propagation delay of wirings, and the like. It is a problem. Commonly used interlayer insulating films such as BPSG (boron-phosphosilicate glass), P-TEOS (plasma-tetraethoxysilane), O ₃ -TEOS (ozone-tetraethoxysilane), SOG (spin-on-glass), etc. The relative dielectric constant (ε) is usually 4 or more, and in order to solve the above problem, it is necessary to lower the dielectric constant of the interlayer insulating film.

As one of the techniques for lowering the dielectric constant of an interlayer insulating film, it is effective to lower the density of the interlayer insulating film. Conventionally, the SOG film is formed by applying SOG on a substrate,
Immediately using a hot plate at a temperature below 300 ° C
A step of drying the solvent (hereinafter, referred to as pre-bake) is performed for 0 to 240 seconds, and thereafter, 300 to 60 using a curing furnace.
It is manufactured by performing a step of heating and curing at a temperature of 0 ° C. for 20 minutes or more. In this method, since the pre-baking is performed on the hot plate immediately after the application of the SOG, the solvent in the SOG evaporates at a stretch, and the film shrinks greatly (the film density becomes high). This phenomenon has a disadvantage that the dielectric constant increases.

[0004]

SUMMARY OF THE INVENTION The first aspect of the present invention provides a method for producing a silica-based coating having a low dielectric constant. The second aspect of the present invention provides a method for manufacturing a semiconductor device having a silica-based coating having a low dielectric constant as an interlayer insulating film.

[0005]

According to the present invention, a coating solution for forming a silica-based film is applied to a substrate, and the film is cured at a temperature rising rate of 60 ° C./minute or less from room temperature to 50 ° C. to 300-600 ° C. The present invention relates to a method for producing a silica-based coating, which comprises a step of curing by heating to a temperature. The present invention also provides
The present invention relates to a method for manufacturing a semiconductor device, including a step of forming an interlayer insulating film by the method for manufacturing a silica-based film.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS As a coating solution for forming a silica-based film used in the present invention, a solution of a silicon-based oligomer or polymer (hereinafter simply referred to as a silicon-based polymer) in an organic solvent may be used. Silicon-based polymers include those having a basic structure of polysiloxane, polycarbosilane, polysilane, or polysilazane. These silicon-based polymers may be used alone or in combination of two or more. Further, a copolymer with another organic polymer containing this as one component may be used.

Examples of the organic solvent include alcohols such as methanol, ethanol, propanol and butanol, ethers such as diethyl ether, dibutyl ether, tetrahydrofuran and dioxane, hexane, heptane,
Aliphatic hydrocarbons such as octane, benzene, toluene,
Examples thereof include aromatic hydrocarbons such as xylene, esters such as ethyl acetate and butyl acetate, ketones such as methyl ethyl ketone and methyl isobutyl ketone, and halogenated carbons such as methylene chloride and chloroform. These solvents may be used alone or in combination of two or more. The amount of the solvent used is such that the amount of the silicon-based polymer is 5 to 80.
It is preferable that the amount is such that it becomes% by weight.

[0008] Specific examples of the coating solution for forming a silica-based film are as follows.

Embedded image (Wherein R is an alkyl group having 1 to 4 carbon atoms, R ′ is an alkyl group having 1 to 4 carbon atoms or an aryl group such as a phenyl group, n
Represents an integer of 0 to 2). There is a coating liquid for forming a silica-based coating containing a polysiloxane (siloxane oligomer) obtained by hydrolyzing and polycondensing an alkoxysilane compound represented by the following formula:

The alkoxysilane compound represented by the general formula (I) is specifically described

Embedded image Such as tetraalkoxysilane,

Embedded image Monoalkyl trialkoxysilane such as,

Embedded image (Where Ph represents a phenyl group; the same applies hereinafter);

Embedded image And other dialkyl dialkoxysilanes

Embedded image And the like, and one or more of these may be used.

The alkoxysilane represented by the general formula (I) used in the present invention is not limited in the proportion of tetraalkoxysilane, monoalkyltrialkoxysilane and dialkyldialkoxysilane. The dialkyl dialkoxysilane is preferably not more than 50 mol% based on the total amount of the alkoxysilane compound used. Also, if necessary,
A disilane compound or the like is used in combination.

The polysiloxane in the present invention is produced by hydrolyzing and polycondensing the alkoxysilane compound represented by the above general formula (I). At this time, as a catalyst, hydrochloric acid, sulfuric acid, phosphoric acid , Nitric acid, inorganic acids such as hydrofluoric acid,
It is preferable to use an organic acid such as oxalic acid, maleic acid, sulfonic acid and formic acid, and a basic catalyst such as ammonia and trimethylammonium can also be used. These catalysts are used in an appropriate amount in accordance with the amount of the alkoxysilane compound represented by the general formula (I), and preferably from 0.001 to 1 mol per mol of the alkoxysilane compound represented by the general formula (I). It is used in a range of 0.5 mol.

The above-mentioned hydrolysis / polycondensation is preferably carried out in the above-mentioned solvent. In this reaction, water is present. The amount of water is determined as appropriate,
If the amount is too small or too large, there is a problem that the storage stability of the coating solution is reduced. Therefore, the amount of water is 0.5 to 1 mol of the alkoxysilane compound represented by the general formula (I). It is preferably in the range of 4 to 4 mol.

The reaction solution (siloxane polymer solution) of the hydrolysis / polycondensation product obtained as described above can be used as it is as a coating solution for forming a silica-based film. After the solvent is removed, it is again dissolved in the solvent and used as a silica-based coating liquid (siloxane polymer liquid).

Another specific example of a coating solution for forming a silica-based film is one containing a polysilazane compound. The polysilazane compound has the general formula (I)

Embedded image (In the formula, n represents an integer of 2 or more, and R ¹ , R ^2, and R ³ each independently represent a hydrogen atom, a fluoroalkyl group, an alkyl group, an alkenyl group, a cycloalkyl group, an aryl group, an alkylamino group, or an alkylsilyl group. Which represents a group). This can be obtained by reacting a halogenosilane, an organohalogenosilane, or the like with ammonia and an amine compound in an organic solvent and polymerizing the same.

As the halogenosilane, for example,

Embedded image and so on.

As the organohalogenosilane, for example,

Embedded image and so on.

These halogenosilane compounds may be used in combination of two or more. As the amine compound,

Embedded image and so on.

The production of the polysilazane compound is carried out by dissolving a halogenosilane, an organohalogenosilane or the like in a reaction solvent, and introducing and reacting at least 4 mol of ammonia or an amine compound with respect to 1 mol of the halogenosilane. As a reaction solvent, benzene, diethyl ether, tetrahydrofuran, hexane and the like are used.
After the reaction, a polysilazane compound can be obtained by filtering the reaction solution and removing the reaction solvent. The temperature of the above reaction is preferably adjusted to -20 ° C to 0 ° C.

The polysilazane compound is dissolved in an organic solvent to form a coating solution. Examples of the organic solvent include diethyl ether, dibutyl ether, tetrahydrofuran, and the like.
Ethers such as dioxane, aliphatic hydrocarbons such as hexane, heptane and octane; aromatic hydrocarbons such as benzene, toluene and xylene; esters such as ethyl acetate and butyl acetate; ketones such as methyl ethyl ketone and methyl isobutyl ketone And halogenated carbons such as methylene chloride and chloroform.

The coating solution for forming a silica-based film is applied onto a substrate such as a silicon wafer mainly by spin coating. Other application methods include a dipping method and a spray coating method. Further, glass, ceramic, metal, or the like can be used as the application substrate. After coating by these methods, the coated film is left for 0 to 48 hours,
By curing at 600 ° C., a silica-based coating is formed. Curing at 300 to 600 ° C. is preferably performed for 10 to 60 minutes. In the present invention, the rate of temperature rise from room temperature to 50 ° C. to the curing temperature is 60 ° C./min or less, preferably 1 to 50 ° C./min, and particularly preferably 5 to 40 ° C./min. By doing so, the density of the coating can be reduced, and therefore the dielectric constant of the coating can be reduced. If the rate of temperature rise is too low, productivity will decrease, and if the rate of temperature rise is too high, the density of the film will not easily decrease.

The silica-based coating of the present invention is preferably used as an interlayer insulating film of a semiconductor device. The interlayer insulating film of the semiconductor device is obtained by forming the silica-based coating of the present invention between wirings on the semiconductor device.

An example of the manufacturing process of the semiconductor device of the present invention will be described below. FIG. 1 is a manufacturing process diagram of a semiconductor device having a multilayer wiring structure. In FIG. 1, a semiconductor substrate 1 such as a silicon wafer, a glass plate, or a metal plate having circuit elements is provided.
Is covered with a protective film 2 such as a silicon oxide film except for a predetermined portion of the circuit element, and the first conductor layer 3 is formed on the exposed circuit element.
Are formed. The above-mentioned silica-based coating solution is applied on the semiconductor substrate by a spinner method or the like, and the interlayer insulating film 4 made of a polysiloxane film is formed by removing the solvent by heat treatment and baking (step (a)).

Next, a photosensitive resin layer 5 of a chlorinated rubber type or a phenol novolak type is formed on the interlayer insulating film 4 by a spinner method, and a predetermined portion of the interlayer insulating film 4 is exposed by a known photolithography technique. Thus, the window 6A is provided (step (b)).

The interlayer insulating film 4 of the window 6A is selectively etched by dry etching using a fluorine-based gas such as carbon tetrafluoride (for example, a method using a fluorine-based gas such as carbon tetrafluoride). 6B is opened. Next, the photosensitive resin layer 5 is completely removed by using an etching solution that does not corrode the first conductor layer 3 exposed from the window 6B but corrodes only the photosensitive resin layer 5 (step (c)).

Further, the second conductor layer 7 is formed by using a known metal film forming method and a photolithography technique, and the electrical connection with the first conductor layer 3 is completely performed (step (d)).

When a multilayer wiring structure having three or more layers is formed, the above steps are repeated to form each layer. That is, a step (a) of forming an interlayer insulating film to be an insulating layer on the conductor layer, a step of selectively removing a predetermined portion of the coating and opening a window (b), and a predetermined portion of the lower portion of the conductor layer Steps (c) and (d) for forming the upper conductor connected to the substrate are repeated.

The surface of the multilayer wiring structure thus manufactured is usually provided with a surface protection layer made of an organic material such as a polyimide resin or an inorganic material such as silicon nitride. , 6B may be opened. The entire semiconductor device is usually sealed with a sealing material containing epoxy resin or the like.

[0028]

EXAMPLES Examples of the present invention will be described below, but the present invention is not limited to these examples. (Example of preparation of coating solution for forming silica-based coating) In a reaction vessel,
15.2 g of tetramethoxysilane, 13.6 g of methyltrimethoxysilane, 12.0 of dimethylmethoxysilane
g, propylene glycol monopropyl ether 110
g, 1N nitric acid (1.5 g) and water (16.2 g) were added thereto, and reacted at room temperature for 72 hours to obtain a coating solution for forming a silica-based film containing polysiloxane.

Example 1 The above-mentioned coating solution for forming a silica-based film was spin-coated on a silicon wafer, and then placed in a quartz furnace and heated from 23 ° C. to 450 ° C. in nitrogen at a rate of 30 ° C./min. The temperature was raised, and after the temperature was raised, the coating was heated at the same temperature for 30 minutes to perform a curing treatment. The film thickness immediately after spin coating is 4000 °, the film thickness after curing is 3200 °,
The film shrank by 20% immediately after the application. The relative permittivity of the produced cured film was determined to be 2.6 from the capacitance measurement at a frequency of 10 KHz.

Example 2 The above-mentioned coating solution for forming a silica-based film was spin-coated on a silicon wafer, and then placed in a quartz furnace and heated from 23 ° C. to 450 ° C. in nitrogen at a rate of 10 ° C./min. The temperature was raised, and after the temperature was raised, the coating was heated at the same temperature for 30 minutes to perform a curing treatment. The film thickness immediately after spin coating is 4000 °, the film thickness after curing is 3400 °,
The film shrank by 15% immediately after application. The relative permittivity of the produced cured film was determined by capacitance measurement at a frequency of 10 KHz, and was 2.5.

Comparative Example 1 The above-mentioned coating solution for forming a silica-based film was spin-coated on a silicon wafer, and heated at 150 ° C. for 30 minutes in a nitrogen atmosphere on a hot plate.
After that, prebaking was performed at 250 ° C. for 30 seconds to obtain a silicon wafer on which a silica-based coating film was formed. next,
The silicon wafer on which the silica-based coating film was formed was placed in a quartz furnace heated to 450 ° C. in nitrogen,
The coating was heated for about 1 minute to cure the silica-based coating. The film thickness immediately after spin coating is 4000 ° and the film thickness after curing is 240.
0 °, and the film contracted 40% immediately after the application. The relative permittivity of the cured film produced by capacitance measurement at a frequency of 10 KHz was 3.0.

[0032]

According to the method of the first aspect, a silica-based coating having a low dielectric constant can be produced. According to the method of claim 2, a semiconductor device having a silica-based coating having a low dielectric constant as an interlayer insulating film can be manufactured.

[Brief description of the drawings]

FIG. 1 is a process chart showing an example of a manufacturing process of a semiconductor device of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Semiconductor substrate 2 Protective film 3 1st conductor layer 4 Interlayer insulating film 5 Photosensitive resin layer 6A, 6B, 6C Window 7 2nd conductor layer

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Yasuhiro Yamamoto 4-13-1, Higashicho, Hitachi City, Ibaraki Prefecture Inside the Hitachi Chemical Co., Ltd. Yamazaki Plant (72) Inventor Takenori Narita 4-13 Higashicho, Hitachi City, Ibaraki Prefecture No. 1 Hitachi Chemical Co., Ltd. Yamazaki Factory (72) Inventor Hiroyuki Morishima 4-3-1 Higashicho, Hitachi City, Ibaraki Prefecture Hitachi Chemical Co., Ltd. Yamazaki Factory

Claims (2)

[Claims] After coating a coating solution for forming a silica-based film on a substrate, the coating film is heated to room temperature to 50 ° C. at a heating rate of 60 ° C./min or less.
A method for producing a silica-based coating, comprising a step of heating and curing from a temperature of 300 ° C. to a curing temperature of 300 to 600 ° C. 2. A method for manufacturing a semiconductor device, comprising a step of forming an interlayer insulating film by the method for manufacturing a silica-based film according to claim 1.