JP4183656B2 - Coating liquid for forming silica-based etching stopper film, silica-based etching stopper film, and method for forming semiconductor multilayer wiring - Google Patents

Description

  The present invention relates to an etching stopper film forming coating solution used for semiconductor wiring formation, an etching stopper film produced using the coating solution, and a semiconductor multilayer forming method using the coating solution. A coating solution for forming a silica-based etching stopper film having resistance and a low dielectric constant having a dielectric constant of 3.5 or less, a silica-based etching stopper film produced using the coating solution, and a semiconductor using the coating solution The present invention relates to a multilayer wiring forming method.

  As is well known, a basic wiring structure in a semiconductor integrated circuit includes a lower wiring layer formed directly or indirectly on a semiconductor substrate, and an upper wiring layer formed on the lower wiring layer via an interlayer insulating layer. Are connected by via wirings formed so as to penetrate the interlayer insulating layer. A multilayer wiring structure of a semiconductor integrated circuit is formed by multiplying the wiring structure into multiple layers.

  Generally, in the formation of the multilayer wiring structure, an etching stopper film is provided between each interlayer insulating film layer. The etching stopper film is an etching-resistant film that is applied to a portion that does not require etching, and is provided in order to prevent the lower layer from being etched when the interlayer insulating film is etched when a multilayer wiring is formed.

Since etching of an inorganic interlayer insulating film often uses a fluorine gas-based etchant such as CH ₃ F, in the case of an etching stopper film provided on an inorganic interlayer insulating film, the characteristics required for the stopper film Is sufficiently resistant to the etchant. From this point of view, CVD-based silicon oxide films, silicon nitride films, and the like are known as etching stopper films conventionally used.

However, at present, the characteristics required for the etching stopper film are insufficient only with resistance to fluorine gas-based etchants such as CH ₃ F. That is, the entire multilayer wiring structure is required to have a low dielectric constant, and the interlayer insulating film is a low dielectric constant material particularly in a multilayer wiring formed using a copper wiring or a low dielectric constant interlayer insulating film. In addition, the etching stopper film constituting the multilayer wiring is also required to be a low dielectric constant material. This dielectric constant is preferably as low as possible and is particularly required to be 4.0 or less.

  The above-described CVD-based silicon oxide film as an etching stopper film used conventionally has a relative dielectric constant of 4.0 to 4.5, and the silicon nitride film has a relative dielectric constant of about 7.0. The rate is high.

  Thus, although an etching stopper film having both good dry etching resistance and a low dielectric constant of 4.0 or less has been developed at the same time, there is no film that can be put into practical use. Therefore, realization of an etching stopper film having the above characteristics and a material capable of forming the etching stopper film has been strongly desired.

  The present invention has been made in view of the above circumstances, and provides a material suitable for forming a silica-based etching stopper film having dry etching resistance and having a low dielectric constant characteristic of a dielectric constant of 3.5 or less. Is.

  The inventors of the present invention have made extensive studies in order to solve the above-mentioned problems. As a result, a film formed using a silica-based coating liquid mainly composed of a hydrolysis product of a specific silica-based compound is satisfactorily etched. It has been found that it exhibits resistance and achieves a low dielectric constant, and has led to the present invention.

（式中、Ｒ¹は、水素原子、アルキル基、アルコキシ基のいずれかであり、少なくとも１つはアルコキシ基を表す。Ｒ²は、アルキレン基、フェニレン基、あるいは下記一般式（２）

（式中、Ｒ⁴はアルキレン基を表す。）で表される基のいずれかを表す。Ｒ³は、水素原子、アルキル基、アルコキシ基のいずれかであり、少なくとも１つはアルコキシ基を表す。ｎは、１〜２０の整数を表す。）で表される化合物の加水分解生成物を含有してなる。 That is, the coating liquid for forming a silica-based etching stopper film of the present invention has the following general formula (1)

(In the formula, R ¹ is any ^one of a hydrogen atom, an alkyl group, and an alkoxy group, and at least one represents an alkoxy group. R ² represents an alkylene group, a phenylene group, or the following general formula (2).

(Wherein R ⁴ represents an alkylene group). R ³ is any one of a hydrogen atom, an alkyl group, and an alkoxy group, and at least one represents an alkoxy group. n represents an integer of 1 to 20. The hydrolysis product of the compound represented by this is contained.

  The etching stopper film of the present invention is an etching stopper film provided between interlayer insulating films in the formation of semiconductor multilayer wiring, and the silica-based etching stopper film forming coating solution is applied to the surface of the interlayer insulating film. The coating film is obtained by drying and baking.

In addition, the semiconductor multilayer wiring forming method of the present invention,
A semiconductor multilayer wiring in which a lower wiring layer formed on a semiconductor substrate and an upper wiring layer formed thereon via an interlayer insulating layer are connected by a via wiring vertically passing through the interlayer insulating layer. In the forming method,
A first interlayer insulating layer forming step of laminating at least an interlayer insulating layer on the lower wiring layer;
A first etching stopper film forming step of forming a first etching stopper film by applying the silica-based etching stopper film forming coating solution on the surface of the interlayer insulating layer;
A second interlayer insulating layer forming step of laminating at least an interlayer insulating layer on the first etching stopper film; and a coating solution for forming the silica-based etching stopper film is applied on the second interlayer insulating layer to form a second A second etching stopper film forming step of forming the etching stopper film of
A photoresist layer is formed on the second etching stopper film, and after pattern exposure, development processing is performed to form a photoresist pattern, and etching is performed using the photoresist pattern as a mask to form a first etching space. Etching space forming step;
A filling step of filling the first etching space with a filling material;
Forming a photoresist layer on the second etching stopper film, irradiating the photoresist layer with pattern light, developing, and forming a photoresist pattern;
Etching is performed using the photoresist pattern as a mask, and the interlayer insulating layer above the first etching space is removed into a predetermined pattern to form a second etching space communicating with the first etching space. A space formation process;
And a wiring formation step of removing a filling material remaining in the first etching space and forming a wiring with copper buried therein.

  In addition, although the film formation composition using the compound similar to Unexamined-Japanese-Patent No. 2000-309752 and Unexamined-Japanese-Patent No. 2003-179050 is made | formed, this disclosed film formation composition is an interlayer. The target is an insulating film. As generally known, since the properties required for the film are different between the etching stopper film and the interlayer insulating film, the disclosed film forming composition and the silica-based etching stopper film forming coating liquid of the present invention are completely different. Is different. Specifically, the interlayer insulating film needs to be appropriately etched with an etchant, but the etching stopper film is provided on the interlayer insulating film layer and protects the interlayer insulating film. It is necessary to have resistance. That is, the etching stopper film is required to have a higher etching rate than the interlayer insulating film layer so that the lower interlayer insulating film layer is not etched during etching. Thus, the etching stopper film and the interlayer insulating film have completely different properties and uses, and it cannot be said that the film forming material disclosed in the above publication can be used for the etching stopper film. Further, there is no description or suggestion that it can be used as an etching stopper film.

  According to the present invention, it is possible to provide a material suitable for forming a silica-based etching stopper film that is suitable as an etching stopper, that is, has dry etching resistance and has a low dielectric constant characteristic of a dielectric constant of 3.5 or less.

Hereinafter, embodiments of the present invention will be described.
The coating liquid for forming a silica-based etching stopper film of the present invention comprises a hydrolysis product of a compound represented by the following general formula (1).

In general formula (1), R < ¹ > is either a hydrogen atom, an alkyl group, or an alkoxy group, and at least one represents an alkoxy group. R ² represents an alkylene group, a phenylene group, or a group represented by the following general formula (2).

In general formula (2), R ⁴ represents an alkylene group, and each may be a different alkylene group or the same alkylene group.

In the general formula (1), R ³ is any one of a hydrogen atom, an alkyl group, and an alkoxy group, and at least one represents an alkoxy group. n represents an integer of 1 to 20. n is preferably 1 to 15, and more preferably 1 to 10.

  Among the compounds represented by the general formula (1), a compound represented by the following general formula (3) or a compound represented by the following general formula (4) is particularly preferable. This is because the ratio of the number of carbon atoms in the entire coating solution is appropriate for obtaining good electrical characteristics (lower dielectric constant) and etching resistance.

（式中、Ｒ⁵はアルキル基を表す。）

(In the formula, R ⁵ represents an alkyl group.)

（式中、Ｒ⁵はアルキル基を表す。）

(In the formula, R ⁵ represents an alkyl group.)

In general formula (3) or (4), R ^{5 s} may be different alkyl groups or the same alkyl group.

  Examples of the compound represented by the general formula (3) include bistrimethoxysilylhexane, bistriethoxysilylhexane, and bistripropoxysilylhexane. Of these, bistrimethoxysilylhexane is particularly preferred.

  Examples of the compound represented by the general formula (4) include bistrimethoxysilyldiethylbenzene, bistriethoxysilyldiethylbenzene, bistripropoxysilyldiethylbenzene, and the like. Of these, bistrimethoxysilyldiethylbenzene is particularly preferable.

  The hydrolysis of the compound represented by the general formula (1) is preferably performed in an organic solvent. Examples of such organic solvents include monohydric alcohols such as methyl alcohol, ethyl alcohol, propyl alcohol, and butyl alcohol, polyhydric alcohols such as ethylene glycol, diethylene glycol, propylene glycol, glycerin, trimethylolpropane, and hexanetriol, and ethylene glycol monomethyl ether. , Ethylene glycol monoethyl ether, ethylene glycol monopropyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monopropyl ether, diethylene glycol monobutyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol Monoethers of polyhydric alcohols such as ethyl monopropyl ether and propylene glycol monobutyl ether, esters such as methyl acetate, ethyl acetate and butyl acetate, ketones such as acetone, methyl ethyl ketone and methyl isoamyl ketone, ethylene glycol dimethyl ether, ethylene glycol All hydroxyl groups of polyhydric alcohols such as diethyl ether, ethylene glycol dipropyl ether, ethylene glycol dibutyl ether, propylene glycol dimethyl ether, propylene glycol diethyl ether, propylene glycol dibutyl ether, diethylene glycol dimethyl ether, diethylene glycol methyl ethyl ether, and diethylene glycol diethyl ether are all alkyl ethers. Polyhydric alcohol Such as ethers, and the like. Of these, polyhydric alcohol ethers obtained by alkylating all hydroxyl groups of the polyhydric alcohol are preferred. These polyhydric alcohol ethers are preferred. These organic solvents may be used alone or in combination of two or more. The amount used is preferably in the range of 70 to 99% by mass. That is, it is preferable to use so that solid content concentration may be in the range of 30 to 1% by mass. By carrying out the reaction in this range, the hydrolysis and dehydration condensation reaction rates can be easily controlled, and the storage stability of the solution is further improved.

  In the hydrolysis of the compound represented by the general formula (1), water is further added to an organic solvent, and the hydrolysis reaction proceeds in the presence of an acid catalyst. As the acid catalyst, any conventionally used organic acid or inorganic acid can be used. Examples of the organic acid include organic carboxylic acids such as acetic acid, propionic acid, and butyric acid. Examples of inorganic acids include mineral acids such as hydrochloric acid, nitric acid, sulfuric acid, and phosphoric acid. Nitric acid and phosphoric acid are particularly preferred from the viewpoints of being easily available industrially and inexpensive and having little adverse effect on the interlayer insulating film and the like from the formed silica-based etching stopper film.

  The amount of water added is such that the water is in the range of 0.5 to 1.5 times the total number of moles of alkoxy groups (Si-OR groups) of the silica-based raw material in the reaction system. preferable. If the amount of water is too small, the finally produced silica-based etching stopper film-forming material has high storage stability over time, but the hydrolysis degree is low, and many organic groups remain in the hydrolyzate. It will be. For this reason, when a film is formed using this material, gas generation due to decomposed organic components becomes remarkable, which is not preferable. Conversely, if the amount of water used during production is large, the storage stability of the produced material is lowered, which is also not preferable.

  The acid catalyst may be added after adding water, or may be mixed with water and added as an aqueous acid solution. The amount of the acid catalyst used is adjusted so that its concentration in the hydrolysis system is in the range of 100 to 10000 ppm, preferably 100 to 1000 ppm. If the amount of the acid catalyst used is too small, the hydrolysis reaction does not proceed sufficiently. Conversely, if the amount is too large, the change with time of the reaction solution tends to increase, which is also not preferable.

  The hydrolysis reaction is usually completed in about 5 to 100 hours. In order to shorten the reaction time, it is preferable to add water and an acid catalyst dropwise to an organic solvent containing the compound represented by the general formula (1) at a heating temperature not exceeding 80 ° C.

  The silica-based etching stopper film-forming material prepared in this way can be used as it is as a coating solution, but it can be used by adjusting the concentration by concentration treatment or diluting by separately adding an organic solvent. May be. As the organic solvent used for the dilution, it is preferable to use the organic solvent described above.

  Regardless of whether or not alcohol is used as the solvent, the adjusted coating solution usually contains an alcohol component due to hydrolysis and polycondensation reaction of the compound represented by the general formula (1). It is preferable that the alcohol content in the coating solution is finally 15% by mass or less of the total amount of the coating solution. When the residual amount of alcohol in the coating solution is more than 15% by mass, the storage stability of the coating solution is lowered, or the original film characteristics are lost. When alcohol is contained excessively, it is preferable to remove excess alcohol by distillation under reduced pressure. The vacuum distillation is performed at, for example, a degree of vacuum, 10 to 300 mmHg, preferably 20 to 150 mmHg, and a temperature of 20 to 50 ° C.

  From the viewpoint of keeping the alcohol content in the coating solution to be finally prepared low, as the organic solvent used when the hydrolysis reaction of the general formula (1) proceeds, all the hydroxyl groups of the polyhydric alcohol are etherified. It is preferable to use polyhydric alcohol ethers. In particular, alkylene glycol monoalkyl ether is preferable, and propylene glycol monopropyl ether is particularly preferable.

  After completion of the hydrolysis reaction, solvent replacement may be performed in order to obtain a final coating solution. For example, after completion of the hydrolysis and polymerization reaction, the obtained uniform dispersion of the hydrolysis product is used as it is, and an organic solvent having a higher boiling point and suitable for other coating liquids is used as compared with the used reaction solvent. Further blend. For example, the mixture is distilled at an appropriate intermediate temperature so that the fractional distillation efficiently proceeds under reduced pressure, and the reaction solvent is selectively separated and removed from the dispersoid mainly composed of the silica-based polymer. .

  Finally, the solid content concentration is usually adjusted to about 1 to 20% by mass by concentration or dilution to obtain a coating solution for forming a silica-based etching stopper film.

  The obtained coating liquid for forming a silica-based etching stopper film is applied to the surface of the interlayer insulating film layer, and then heated, dried and baked to form a film. For the application, any method such as a spray method, a spin coating method, a dip coating method, or a roll coating method can be used.

  The coating film may be dried as long as the solvent in the coating solution diffuses to form a coating film, and there are no restrictions on the means, temperature, time, and the like. Generally, it is heated for about 1 to 6 minutes on a hot plate at about 80 to 300 ° C. It is preferable to raise the temperature stepwise, preferably in three or more steps. Specifically, after performing the first drying process for about 30 seconds to 2 minutes on a hot plate of about 70 to 120 ° C. in an air or an inert gas atmosphere such as nitrogen, the temperature is about 130 to 220 ° C. The second drying process is performed for about 30 seconds to 2 minutes, and the third drying process is performed at about 150 to 300 ° C. for about 30 seconds to 2 minutes. Thus, the surface of the formed coating film becomes uniform by performing stepwise drying treatment of three or more steps, preferably about 3 to 6 steps.

  The dried coating film is then baked. Firing is performed at a temperature of about 300 to 400 ° C. in a nitrogen atmosphere. If the baking temperature is less than 300 ° C., the etching resistance of the etching stopper film after baking may be insufficient. On the other hand, if the firing temperature exceeds 400 ° C., it may be difficult to keep the dielectric constant low. A good etching stopper film can be formed by performing the baking in a nitrogen atmosphere or an inert gas atmosphere.

  According to such a method for forming an etching stopper film, it is possible to form a silica-based etching stopper film having etching resistance and low dielectric constant characteristics having a dielectric constant of 3.5 or less. Similarly, a hard mask film can be formed.

  The film thickness of the etching stopper film of the present invention is 1/2 or less, preferably 1/5 or less, more preferably 1/10 or less of the interlayer insulating film. It is preferable in terms of efficiency and in forming a multilayer wiring with a high degree of integration. In addition, since etching resistance becomes so small that it is a thin film, it is desirable to set it as a film thickness of 10 nm or more. In practice, it is desirable to form the film with a thickness of 20 nm or more, preferably 30 nm or more.

The silica-based etching stopper film of the present invention exhibits excellent etching resistance against etching using oxygen plasma or etching using a fluorine gas-based etchant (RIE: reactive ion etching). Examples of the fluorine gas-based etchant include CH ₃ F, CH ₂ F ₂ , CHF ₃ , F ₄ , CF ₄ , C ₂ F ₆ , C ₄ F ₈ , C ₃ F ₅ , SF ₆ and SF _6. It is done.

  Although the etching stopper film of the present invention is a silica-based etching stopper film, the etching stopper film is characterized by being resistant to the above-described fluorine-based gas for etching an inorganic material and having a low dielectric constant. In addition, the silica-based etching stopper film of the present invention functions as an etching stopper film having the above effects even when the interlayer insulating film is an organic system. That is, the etching stopper film of the present invention can be provided on the interlayer insulating film regardless of whether the interlayer insulating film is organic or inorganic.

  The coating film formed by coating on the interlayer insulating film can be subjected to plasma treatment to further improve its etching resistance. Such a plasma treatment is preferably performed on the coating film before firing after the silica-based etching stopper film-forming coating solution is applied, preferably after the drying treatment is finished. The plasma treatment is preferably performed in a nitrogen atmosphere or an inert atmosphere such as helium. For example, plasma irradiation is continuously performed for 1 minute under the conditions of a nitrogen gas amount of 100 sccm, an output of 300 w, a pressure of 300 mTorr, and a temperature of 100 ° C.

  The surface of the film is modified by the plasma treatment, and a silica-based etching stopper film having excellent etching resistance can be formed. However, it is known that the plasma resistance can improve the etching resistance, but generally the dielectric constant is slightly improved. Therefore, the implementation of the plasma processing is decided in consideration of the design structure of the device. It is good to do.

  Next, the lower wiring layer formed on the semiconductor substrate using the coating solution for forming the silica-based etching stopper film of the present invention, and the upper wiring layer formed thereon via the interlayer insulating layer, An example of a method for forming a semiconductor multilayer wiring that is connected by via wiring that penetrates the interlayer insulating layer vertically will be described below. 1 and 2 are manufacturing process diagrams of a semiconductor device having a multilayer wiring structure. 1 to 2 is a continuous process, and represents the first to fourth processes from the top to the bottom of FIG. 1, and a series of processes of the fifth to eighth processes from the top to the bottom of FIG. Represents.

First, as shown in the first step of FIG. 1, an interlayer insulating layer (low dielectric layer) 2 is formed on the substrate 1. As a material constituting the interlayer insulating layer (low dielectric layer) 2, SiO ₂ , carbon-doped oxide (SiON), SOG (spin on glass), or the like is used. A resist film 3 is formed on the interlayer insulating layer (low dielectric layer) 2 and patterned. By using the patterned resist film 3 as a mask, the interlayer insulating layer (low dielectric layer) 2 is selectively etched, and then the resist film 3 is removed, so that a wiring trench ( Trench) 4 is formed. Next, by depositing a barrier metal film 5 on the surface of the interlayer insulating layer (low dielectric layer) 2 in which the wiring trench 4 is formed as described above, the inner surface of the wiring trench 4 is formed in the wiring trench 4. A barrier metal film 5 is formed to improve adhesion between the copper to be buried and the interlayer insulating layer (low dielectric layer) 2 and at the same time prevent diffusion of copper into the interlayer insulating layer 2. Thereafter, as shown in the third step, copper is buried in the wiring groove (trench) 4 by using an electrolytic plating method or the like to form a lower wiring layer (metal layer) 6.

  Next, copper and the remaining barrier metal 5 adhering to the surface of the interlayer insulating layer (low dielectric layer) 2 at this time are removed by chemical polishing (CMP), and the interlayer insulating layer (low dielectric layer) is removed. After the surface of 2 is planarized, a first interlayer insulating layer (low dielectric layer) 7 is formed thereon.

  Next, the 1st etching stopper film | membrane 8 is formed using the coating liquid for silica type etching stopper film | membrane formation of this invention. Furthermore, a second interlayer insulating layer (low dielectric layer) 9 is formed thereon, and then a second etching stopper film 10 is laminated using the silica-based etching stopper film forming coating solution of the present invention.

  Next, a resist mask 11 having a pattern for forming a first etching space (via hole) is formed on the second etching stopper film 10. Next, as shown in the fourth step, etching is performed using the resist mask 11, and the second etching stopper film 10, the second interlayer insulating layer (low dielectric layer) 9, and the first etching are performed. A first etching space (via hole) 12 that penetrates the stopper layer 8 and the first interlayer insulating layer (low dielectric layer) 7 and reaches the surface of the lower wiring layer 6 is formed.

  Subsequently, as shown in the fifth step of FIG. 2, the first etching space (via hole) 12 is filled with an embedding material 13 such as a photoresist material. Next, a resist mask 14 having a pattern for forming a second etching space (trench) is formed on the filling material 13. Using this resist mask 14, the filling material 13 is etched back to leave a predetermined thickness at the bottom of the first etching space (via hole) 12 as shown in the sixth step. As shown in the process, the second etching stopper film 10 and the second interlayer insulating layer (low dielectric layer) 9 are etched to form a second etching space (trench 15), and at the bottom of the via hole 12 The embedding material 13 remaining in is removed. Thereafter, copper is buried in the first etching space (via hole) 12 and the second etching space (trench) 15, and as shown in the eighth step, the via wiring 16 and the upper wiring layer (metal layer). 17. Thereby, a multilayer wiring structure in which the lower wiring layer (metal layer) 6 and the upper wiring layer (metal layer) 17 are electrically connected by the via wiring 16 is realized.

  Hereinafter, the present invention will be described in more detail based on examples. In addition, this invention is not limited to the following Example.

[Synthesis Example 1]
3.0 g (0.009 mol) of bistrimethoxysilylhexane was dissolved in 18.0 g of propylene glycol monopropyl ether and stirred. Next, an aqueous nitric acid solution prepared by mixing 20 g of nitric acid with 1.1 g (0.054 mol) of water was added dropwise while slowly stirring. After completion of the dropping, stirring was stopped and the solution was allowed to stand at room temperature (25 ° C.) for 1 day to obtain a solution 1 having a SiO ₂ conversion concentration of 5 mass% and a solid content molecular weight (Mw) of 12,000.

[Synthesis Example 2]
Bistrimethoxysilyldiethylbenzene 5.0 g (0.013 mol) was dissolved in propylene glycol monopropyl ether 25.7 g and stirred. Next, an aqueous nitric acid solution prepared by mixing 30 μl of nitric acid with 1.4 g (0.078 mol) of water was added dropwise while slowly stirring. After completion of the dropping, stirring was stopped and the solution was allowed to stand at room temperature (25 ° C.) for 1 day to obtain a solution 2 having a SiO ₂ conversion concentration of 5 mass% and a solid content molecular weight (Mw) of 14,000.

[Dry etching resistance evaluation]
The coatings 1 to 3 obtained in the following Examples 1 and 2 and Comparative Example 1 are subjected to dry etching treatment, and the change in film thickness before and after the treatment is measured with a spectroscopic ellipsometer “DHA-XA2” (manufactured by Mizoji Engineering Co., Ltd. : 633 nm), and the change in film thickness was evaluated as dry etching resistance evaluation. The dry etching process was performed as follows.
The processing conditions were an oxide film etcher (product name “TCE7612-XX”; manufactured by Tokyo Ohka Kogyo Co., Ltd.), an output of 400 W, a pressure of 300 mTorr, and an etching composition of CF ₄ / CF ₃ = 25/25 (cc / min), He: 100 (cc / min), dry etching evaluation for 30 seconds was performed.

[Dielectric constant measurement]
Using the dielectric constant measuring device SSM495 (manufactured by SSM Japan) for the coatings 1 to 3 obtained in Examples 1 and 2 and Comparative Example 1 below, the relative dielectric constant with respect to the vacuum in the film thickness direction of the coating was measured. .

<Example 1>
The coating solution (solution 1) prepared in Synthesis Example 1 was applied onto a silicon wafer by a spin coating method, and was subjected to heat treatment at 80 ° C. for 1 minute in the air on a hot plate. Next, heat treatment was performed at 150 ° C. for 1 minute and further at 200 ° C. for 1 minute (drying treatment).
Next, heat treatment (baking treatment) was performed at 350 ° C. for 30 minutes in a nitrogen atmosphere to form a coating film 1 having a thickness of 350 nm. The obtained coating 1 was subjected to the above dry etching resistance evaluation and dielectric constant measurement.
As a result, the film 1 had a film thickness change (film thickness decrease) of about 22 nm, and good dry etching resistance was recognized. The dielectric constant was about 3.31, and good low dielectric constant characteristics were observed.

<Example 2>
In Example 1, except that the coating solution (solution 2) prepared in Synthesis Example 2 was used instead of the solution 1, the coating 2 was formed in the same manner as in Example 1, and the above coating 2 was obtained with respect to the obtained coating 2 Was evaluated.
As a result, the film 2 had a film thickness change (film thickness decrease) of about 30 nm, and good dry etching resistance was recognized. The dielectric constant was about 3.48, and good low dielectric constant characteristics were also observed.

<Comparative Example 1>
In Example 1, instead of Solution 1, T-12 (product name; manufactured by Tokyo Ohka Kogyo Co., Ltd.), which is a coating solution containing a hydrolysis product of trialkoxysilane, was used. Thus, the coating film 3 was formed, and the above-described evaluation was performed on the coating film 3 obtained.
As a result, the coating film 3 showed a dielectric constant of about 3.21, and had good dielectric constant characteristics, but showed a film thickness change (film thickness reduction) of about 110 nm and low dry etching resistance.

  As described above, since the material for forming a silica-based etching stopper film according to the present invention has dry etching resistance and has a low dielectric constant characteristic of a dielectric constant of 3.5 or less, copper wiring and a low dielectric constant (Low− k) Suitable for use in a method for forming a multilayer wiring composed of an interlayer insulating film.

It is a manufacturing process figure of the first half of the semiconductor device of a multilayer wiring structure. FIG. 4 is a manufacturing process diagram of the latter half of the semiconductor device having a multilayer wiring structure following FIG. 1;

Explanation of symbols

1 substrate 2 interlayer insulation layer (low dielectric layer)
3 Resist film 4 Wiring trench
5 Barrier metal film 6 Lower wiring layer (metal layer)
7 First interlayer insulating layer (low dielectric layer)
8 First etching stopper film 9 Second interlayer insulating layer (low dielectric layer)
10 Second etching stopper film 11 Resist mask 12 First etching space (via hole)
13 Filling material in first etching space (via hole) 14 Resist mask 15 Second etching space (trench)
16 Via wiring 17 Upper wiring layer (metal layer)

Claims (5)

A coating solution for forming an etching stopper film provided between inorganic interlayer insulating films,
The following general formula (1)

(In the formula, R ¹ is any ^one of a hydrogen atom, an alkyl group, and an alkoxy group, and at least one represents an alkoxy group. R ² represents an alkylene group, a phenylene group, or the following general formula (2).

(Wherein R ⁴ represents an alkylene group). R ³ is any one of a hydrogen atom, an alkyl group, and an alkoxy group, and at least one represents an alkoxy group. n represents an integer of 1 to 20. )
A coating solution for forming a silica-based etching stopper film, comprising a hydrolysis product of a compound represented by the formula: The compound represented by the general formula (1) is represented by the following general formula (3).

(In the formula, R ⁵ represents an alkyl group.)
The coating liquid for forming a silica-based etching stopper film according to claim 1, wherein the coating liquid is a compound represented by the formula: The compound represented by the general formula (1) is represented by the following general formula (4).

(In the formula, R ⁵ represents an alkyl group.)
The coating liquid for forming a silica-based etching stopper film according to claim 1, wherein the coating liquid is a compound represented by the formula: In semiconductor multilayer wiring formation, an etching stopper film provided between inorganic interlayer insulating films,
The etching stopper film | membrane obtained by apply | coating the coating liquid for silica type etching stopper film formation of any one of Claims 1-3 to the surface of the said inorganic interlayer insulation film, and drying and baking this coating film. A lower wiring layer formed on a semiconductor substrate, thereon and the inorganic interlayer insulating film an upper wiring layer formed over the inorganic interlayer insulating film semiconductor multilayer are connected by a via wiring that penetrates vertically In the method of forming the wiring,
A first interlayer insulating film forming step of laminating at least an inorganic interlayer insulating film on the lower wiring layer;
The 1st etching stopper film | membrane formation which apply | coats the coating liquid for a silica type etching stopper film formation of any one of Claims 1-3 on the surface of the said inorganic interlayer insulation film , and forms a 1st etching stopper film | membrane Process,
A second interlayer dielectric film forming step for laminating at least an inorganic interlayer insulating film on the first etching stopper film,
The second etching stopper film for forming a second etching stopper film by coating a silica-based etching stopper film-forming coating liquid according to any one of claims 1 to 3 on the second interlayer insulating film Forming process;
A photoresist layer is formed on the second etching stopper film, and after pattern exposure, development processing is performed to form a photoresist pattern, and etching is performed using the photoresist pattern as a mask to form a first etching space. An etching space forming step,
An embedding step of filling the filler material in the first etching space,
Forming a photoresist layer on the second etching stopper film, irradiating the photoresist layer with pattern light, developing, and forming a photoresist pattern;
The etching is performed using the photoresist pattern as a mask to form the first upper portion of the inorganic interlayer second etching space insulating film is removed in a predetermined pattern communicating with said first etching space etched space a second etching space forming step,
A wiring formation step of removing a filling material remaining in the first etching space and forming a wiring with copper embedded;
A method for forming a semiconductor multilayer wiring, comprising:

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