JP5279301B2 - Fine processing agent and fine processing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a microfabrication processing agent and a microfabrication processing method employing the same capable of selectively microfabricating a silicon oxide film when microfabricating a layered film obtained by layering at least the silicon oxide film and a silicon nitride film. <P>SOLUTION: The microfabrication processing agent contains: (a) at least one hydrogen fluoride in 0.01 to 15 wt.% and ammonium fluoride in 0.1 to 40 wt.%; (b) water; and (c) a soluble polymer of at least any one selected from a group constituted of acrylic acid, acrylic acid ammonium, acrylic ester, acrylamide, styrene sulfonic acid, styrene sulfonic acid ammonium, and styrene sulfonic acid ester in 0.001 to 10 wt.%. <P>COPYRIGHT: (C)2009,JPO&amp;INPIT

Description

  The present invention relates to a fine processing agent used for fine processing, cleaning processing, and the like in manufacturing of a semiconductor device, a liquid crystal display device, a micro electro mechanical systems (MEMS) device, and a fine processing method using the same. In particular, the present invention relates to a fine processing agent used for fine processing of a laminated film in which at least a silicon oxide film and a silicon nitride film are laminated, and a fine processing method using the same.

  One of the most important processes in the manufacturing process of semiconductor devices is to pattern and etch a silicon oxide film, silicon nitride film, polysilicon film, metal film, etc. formed on the wafer surface into a desired shape. It is. For wet etching, which is a kind of etching technique, a fine processing agent capable of selectively etching only a film to be etched is required.

  Examples of the fine processing agent that uses a silicon oxide film as an etching target include buffered hydrofluoric acid and hydrofluoric acid. However, when the buffered hydrofluoric acid or hydrofluoric acid is used as a microfabrication processing agent for the laminated film in which the silicon oxide film and the silicon nitride film are laminated, the silicon nitride film is also etched at the same time. As a result, it becomes difficult to pattern into a desired shape.

  As a fine processing agent capable of solving such problems and selectively etching only the silicon oxide film, for example, a hydrofluoric acid added with an anionic surfactant such as ammonium lauryl sulfate. (See Patent Document 1 below). However, the fine processing agent has a very high foaming property, which makes it unsuitable as a fine processing agent used in a semiconductor element manufacturing process.

  On the other hand, as a semiconductor element that performs wet etching using a fine processing agent, for example, a DRAM (Dynamic Random Access Memory) can be cited. The DRAM cell is composed of one transistor and one capacitor. This DRAM has been highly integrated about four times over the past three years. High integration of DRAM is mainly due to high integration of capacitors. Therefore, in order to secure a capacitance value necessary for stable storage operation while reducing the area occupied by the capacitor, the capacitor area is increased, the capacitor insulating film is thinned, and a high dielectric constant film is introduced.

  As the capacitor insulating film, a silicon oxide film is used, and so far, its thinning has been studied. However, the thinning of the silicon oxide film as the capacitor insulating film has reached the limit with 1Mbit DRAM. Therefore, a silicon nitride film is used as an insulating film in a 4M bit DRAM. Furthermore, application of a tantalum oxide film has been started as higher integration progresses.

  The capacitor structure of a 64-Mbit generation DRAM is a cylinder type. When the silicon oxide film thus formed is removed by wet etching to form a capacitor after forming the cylinder-type capacitor lower electrode, the following problems occur when a conventional etching solution is used.

  That is, after the capacitor lower electrode is formed, the formed silicon oxide film is removed by wet etching. Further, rinse with ultrapure water and dry. In this drying process, the surface tension of water existing between the capacitor lower electrodes frequently causes a “leaning” phenomenon in which the lower electrodes are inclined and adhere to each other, thereby inducing 2-bit failure. There is. For this reason, Patent Document 2 below discloses a technique for forming a support film made of a silicon nitride film between capacitor lower electrodes. Patent Document 3 listed below discloses a technique for forming a silicon nitride film as an insulating film in order to improve the insulation characteristics with respect to the bit line. A technique for forming a film as an etching stop film in an etching process of a silicon oxide film is disclosed.

  In the manufacturing process of these semiconductor elements, when a conventional etching solution is used, the silicon oxide film as the support film in Patent Document 1, the silicon nitride film in Patent Document 2, and the etching stop film in Patent Document 3 are used. There is a problem that the silicon oxide film is etched together with the etching target.

JP 2005-328067 A JP 2003-297852 A Japanese Patent Laid-Open No. 10-98155 JP 2000-22112 A

  The present invention has been made in view of the above-described problems, and an object of the present invention is to selectively finely process a silicon oxide film when finely processing a laminated film in which at least a silicon oxide film and a silicon nitride film are laminated. An object of the present invention is to provide a fine processing agent that can be used, and a fine processing method using the same.

  In order to solve the above-described conventional problems, the inventors of the present application have made extensive studies on a fine processing agent and a fine processing method using the same. As a result, the microfabrication processing agent to which a predetermined water-soluble polymer is added can selectively microfabricate only the silicon oxide film with respect to the laminated film in which the silicon oxide film and the silicon nitride film are laminated. As a result, the present invention has been completed.

  That is, in order to solve the above-mentioned problems, the microfabrication processing agent according to the present invention comprises (a) at least 0.01 to 15% by weight of hydrogen fluoride, or 0.1 to 40% by weight of ammonium fluoride. Any one, (b) water, (c) 0.001 to 10% by weight of acrylic acid, ammonium acrylate, acrylic ester, acrylamide, styrene sulfonic acid, ammonium styrene sulfonate, and styrene sulfonic acid ester And at least one water-soluble polymer selected from the group consisting of:

  According to the said structure, the fine processing agent of this invention can aim at reduction of the etching effect with respect to a silicon nitride film, without impairing the etching effect with respect to a silicon oxide film by containing the said water-soluble polymer. As a result, for example, when the microfabrication processing agent of the present invention is applied to microfabrication of a laminated film in which a silicon oxide film and a silicon nitride film are laminated, selective microfabrication of the silicon oxide film while suppressing etching of the silicon nitride film Is possible. As a result, the yield in the semiconductor element manufacturing process can be reduced.

  Here, the content of the water-soluble polymer is in the range of 0.001 to 10% by weight. By setting the lower limit to 0.001% by weight, the effect of adding the water-soluble polymer can be exhibited, and the etching of the silicon nitride film can be suppressed. Moreover, the increase in the metal impurity in a fine processing agent can be suppressed by making an upper limit into 10 weight%. In addition, an increase in viscosity can also be suppressed, thereby preventing a reduction in the rinse removal performance of the fine processing agent with a rinse agent such as ultrapure water. In the present invention, “microfabrication” means including etching of a film to be processed and surface cleaning. In addition, the “water-soluble polymer” means a polymer that dissolves 1 mass% or more (10 g / L) at room temperature in a mixed solution containing the components (a) and (b).

  In the above configuration, the water-soluble polymer is preferably a copolymer of ammonium acrylate and methyl acrylate.

  Moreover, in the said structure, it is preferable that the said water-soluble polymer is polyacrylamide.

  Furthermore, in the said structure, it is preferable that the weight average molecular weights of the said water-soluble polymer are in the range of 1000-1 million. By setting the weight average molecular weight of the water-soluble polymer to 1000 or more, the stabilizer that serves as a polymerization inhibitor can be reduced in the production of the water-soluble polymer. As a result, the water-soluble polymer can be prevented from being contaminated with metal. On the other hand, when the weight average molecular weight is set to 1 million or less, an increase in the viscosity of the fine processing agent can be suppressed, so that handleability can be improved. In addition, it is possible to prevent a reduction in the rinse removal performance of the fine processing agent by a rinse agent such as ultrapure water.

  Moreover, in the said structure, it is preferable that the etch rate in 25 degreeC with respect to a silicon oxide film exists in the range of 1-5000 nm / min. As a result, it is possible to improve the production efficiency by preventing the processing time of the fine processing for the silicon oxide film from being prolonged, and to easily control the film thickness and surface roughness of the silicon oxide film after the micro processing. To do.

  In order to solve the above-described problems, the microfabrication processing method according to the present invention microfabricates a laminated film in which at least a silicon oxide film and a silicon nitride film are laminated, using the micromachining treatment agent described above. It is characterized by that.

  In the method, at least a silicon oxide film and a silicon nitride film are added to the fine processing agent capable of reducing the etching effect on the silicon nitride film without impairing the etching effect on the silicon oxide film by adding the water-soluble polymer. Therefore, the silicon oxide film can be selectively finely processed while suppressing the etching of the silicon nitride film. As a result, the yield in the semiconductor element manufacturing process can be reduced.

  The silicon oxide film is a natural oxide film, a thermal silicon oxide film, a non-doped silicate glass film, a phosphorus-doped silicate glass film, a boron-doped silicate glass film, a phosphorus-doped silicate glass film, a TEOS film, or a fluorine-containing silicon oxide film. It is preferable that

  The silicon nitride film is preferably a silicon nitride film or a silicon oxynitride film.

The present invention has the following effects by the means described above.
That is, according to the present invention, only the silicon oxide film can be selectively finely processed with respect to the laminated film in which at least the silicon oxide film and the silicon nitride film are laminated. For example, a semiconductor device, a liquid crystal display device, It enables fine processing suitable for manufacturing micromachine devices and the like.

One embodiment of the present invention will be described below.
The fine processing agent according to the present invention according to the present embodiment includes (a) at least one of hydrogen fluoride and ammonium fluoride, (b) water, and (c) a water-soluble polymer. .

  The content of hydrogen fluoride in the component (a) is preferably in the range of 0.01 to 15% by weight, and more preferably in the range of 0.05 to 10% by weight. It is. When the content of hydrogen fluoride is less than 0.01% by weight, it is difficult to control the concentration of hydrogen fluoride, and thus there may be a large variation in etch rate with respect to the silicon oxide film. On the other hand, when the content of hydrogen fluoride exceeds 15% by weight, the etching rate for the silicon oxide film becomes excessively high, and the controllability of etching deteriorates.

  The ammonium fluoride content is preferably in the range of 0.1 to 40% by weight, and more preferably in the range of 5 to 25% by weight. If the content of ammonium fluoride is less than 0.1% by weight, it is difficult to control the concentration of ammonium fluoride, and thus there may be a large variation in etch rate with respect to the silicon oxide film. Moreover, when the content of ammonium fluoride exceeds 40% by weight, it approaches the saturation solubility of ammonium fluoride. Therefore, when the liquid temperature of the fine processing agent decreases, the fine processing agent reaches the saturation solubility, Crystals may be deposited.

  In the present embodiment, by including the component (a), the etching rate with respect to the silicon nitride film can be selectively suppressed, and the etching selectivity (silicon oxide film / silicon nitride film) can be increased. More specifically, for example, the etching rate for the silicon nitride film can be suppressed to 80% or less as compared with the case where the component (a) is not added.

  The component (a) may be hydrogen fluoride or ammonium fluoride alone or a mixture thereof. Moreover, the 3rd component may contain. Examples of the third component include surfactants and inorganic acids. However, it is not preferable to add an organic acid such as formic acid because the effect of selectively suppressing etching on the silicon nitride film is reduced.

  The surfactant is not particularly limited. For example, when component (a) is hydrofluoric acid alone, nonionic surfactants such as polyethylene glycol alkyl ether, polyethylene glycol alkyl phenyl ether, and polyethylene glycol fatty acid ester are used. Preferably exemplified. In addition, when the component (a) is a mixture of hydrofluoric acid and ammonium fluoride, or ammonium fluoride alone, an aliphatic alcohol, an aliphatic carboxylic acid, a hydrofluoroalkyl alcohol, a hydrofluoroalkylcarboxylic acid and a salt thereof, Alternatively, it may be used in one or a mixture of two or more of aliphatic amine salts and aliphatic sulfonic acids, and the form may be solid or liquid.

  The addition amount of the surfactant is preferably in the range of 0.001 to 0.1% by weight, and more preferably in the range of 0.003 to 0.05% by weight. By adding the surfactant, it is possible to suppress the roughness of the surface of the silicon nitride film or semiconductor substrate subjected to the etching process. Furthermore, the conventional etching solution tends to remain locally on the surface of the semiconductor substrate on which a fine pattern has been formed due to ultra-high integration, and uniformly etches when the resist interval is about 0.5 μm or less. It becomes more difficult. However, when the fine processing agent of the present invention to which a surfactant is added is used as an etching solution, the wettability to the surface of the semiconductor substrate is improved, and the uniformity of etching in the substrate surface is improved. However, if the addition amount is less than 0.001% by weight, the surface tension of the fine processing agent is not sufficiently lowered, and the effect of improving wettability may be insufficient. Further, if the addition amount exceeds 0.1% by weight, not only the effect corresponding to that can not be obtained, but also the defoaming property deteriorates, the bubbles adhere to the etched surface, the etching unevenness occurs, or the fine gaps are formed. Bubbles may enter and cause etching failure.

  It does not specifically limit as said inorganic acid, For example, hydrochloric acid, a sulfuric acid, phosphoric acid etc. can be illustrated. The addition amount of the inorganic acid is preferably in the range of 0.01 to 30% by weight, and more preferably in the range of 0.05 to 10% by weight. If the addition amount is less than 0.01% by weight, it is difficult to control the concentration of the inorganic acid, which causes a disadvantage that the variation in the etching rate with respect to the silicon oxide film becomes large. On the other hand, when it exceeds 30% by weight, for example, when hydrochloric acid is used, the vapor pressure becomes large, so that there is a disadvantage that the chemical composition against evaporation is not stable.

  The water-soluble polymer in the component (c) is at least any selected from the group consisting of acrylic acid, ammonium acrylate, acrylic ester, acrylamide, styrene sulfonic acid, ammonium styrene sulfonate, and styrene sulfonic acid ester. Or one.

  Among the water-soluble polymers listed above, the copolymer of ammonium acrylate and methyl acrylate is the case where the component (a) is composed of hydrogen fluoride alone or when hydrogen fluoride and ammonium fluoride are used in combination. In particular, the etching suppression effect on the silicon nitride film is high. The polymerization ratio between ammonium acrylate and methyl acrylate is preferably in the range of 9.9: 0.1 to 5: 5. When the polymerization ratio of methyl acrylate is larger than the above numerical range, there may be a disadvantage that the solubility of the copolymer of ammonium acrylate and methyl acrylate is reduced. In addition, polyacrylamide has a high etching suppression effect on the silicon nitride film, particularly when the component (a) uses hydrogen fluoride and ammonium fluoride in combination, or when hydrogen fluoride and hydrochloric acid are used in combination.

  The content of the water-soluble polymer in the component (c) is preferably in the range of 0.001 to 10% by weight, more preferably in the range of 0.1 to 5% by weight. Is preferred. If the content is less than 0.001% by weight, the effect of adding the water-soluble polymer is lowered, and the effect of suppressing the etch rate on the silicon nitride film becomes insufficient, such being undesirable. On the other hand, if the content exceeds 10% by weight, the metal impurities in the fine processing agent increase and the viscosity becomes high, so that the rinse removal performance of the fine processing agent with a rinse agent such as ultrapure water is lowered. As a result, it is not suitable as a fine processing agent used in the manufacturing process of a semiconductor device.

  The weight average molecular weight of the water-soluble polymer is preferably in the range of 1,000 to 1,000,000, and more preferably in the range of 1,000 to 10,000. If the weight average molecular weight is less than 1000, the amount of stabilizer used as a polymerization inhibitor is increased. As a result, it may be a cause of metal contamination to the fine processing agent. When the weight average molecular weight exceeds 1,000,000, the viscosity of the fine processing agent increases, and the handleability may deteriorate. Moreover, the rinse removal performance of the fine processing agent with a rinse agent such as ultrapure water may be reduced.

  In the fine processing agent of the present embodiment, additives other than the surfactant can be mixed within a range that does not impair the effect. Examples of the additive include hydrogen peroxide and a chelating agent.

  Depending on the required purity of the microfabricated surface treatment agent, the water-soluble polymer to be added may be purified by distillation, ion exchange resin, ion exchange membrane, electrodialysis, filtration, etc. Purification may be performed by filtration or the like.

  Next, a microfabrication processing method using the microfabrication processing agent according to the present embodiment will be described using wet etching as an example.

  The fine processing agent of the present embodiment is employed in various wet etching methods. As an etching method, there are an immersion method, a spray method, and the like, and the microfabrication processing agent of the present invention can be adopted in any method. The immersion method is preferable because the composition change of the fine processing agent is small due to evaporation in the etching process.

  The etching temperature when the fine processing agent is used as an etching solution is preferably in the range of 5 to 50 ° C, more preferably in the range of 15 to 35 ° C, and 20 to 30. More preferably, it is within the range of ° C. Within the above range, evaporation of the fine processing agent can be suppressed, and a change in composition can be prevented. In addition, it is difficult to control the etching rate due to evaporation of the fine processing agent at high temperatures, and the disadvantage is that the components in the micro processing agent are likely to crystallize at low temperatures, resulting in a decrease in etch rate and an increase in liquid particles. Can be avoided. Note that since the etch rate varies from film to film depending on the etching temperature, the difference between the etch rate for the silicon oxide film and the etch rate for the silicon nitride film may be affected.

  In the fine processing agent of the present embodiment, the etch rate for the silicon oxide film at 25 ° C. is preferably in the range of 1 to 5000 nm / min, and in the range of 15 to 1000 nm / min. Is more preferred. If the etch rate is less than 1 nm / min, it takes time for fine processing such as etching, which may lead to a decrease in production efficiency. On the other hand, if it exceeds 5000 nm / min, the controllability of the film thickness after etching and the roughness of the substrate surface (surface opposite to the surface on which the silicon oxide film etc. are formed) become remarkable, and the yield may decrease. is there.

  Hereinafter, preferred embodiments of the present invention will be described in detail by way of example. However, the materials, blending amounts, and the like described in the examples are not intended to limit the scope of the present invention only to them, but are merely illustrative examples, unless otherwise specified.

(Etch rate for silicon oxide film and silicon nitride film)
The film thickness of the silicon oxide film and the silicon nitride film before and after etching was measured using an optical film thickness measuring device (Nanospec 6100, manufactured by Nanometrics Japan Co., Ltd.), and the change in film thickness due to etching was measured. The above measurement was repeated at three different etching times to calculate the etch rate.

(Water-soluble polymer)
The water-soluble polymer used in each Example described later and the additive used in each Comparative Example are as shown in Table 1 below.

Example 1
7.0 parts by weight of hydrogen fluoride (manufactured by Stella Chemifa Corporation, high purity grade for semiconductor, concentration 50% by weight) and ammonium fluoride (manufactured by Stella Chemifa Corporation, high purity grade for semiconductor, concentration 40% by weight) ) In a mixed solution of 50.0 parts by weight and 40.5 parts by weight of ultrapure water, 2.5 parts by weight of ammonium polyacrylate (concentration 40% by weight, weight average molecular weight 6000) as a water-soluble polymer was added. After adding and stirring and mixing, the temperature of the mixed solution was adjusted to 25 ° C. and allowed to stand for 3 hours. As a result, an etching solution (fine processing agent) of 3.5% by weight of hydrogen fluoride, 20.0% by weight of ammonium fluoride, and 1% by weight of ammonium polyacrylate was prepared.

  Next, the etch rate for the TEOS film as the silicon oxide film and the silicon nitride film was measured. Furthermore, the etch rate selectivity (silicon oxide film / silicon nitride film) was evaluated. The results are shown in Table 2 below.

(Examples 2 to 10)
In Examples 2 to 10, the contents of hydrogen fluoride and ammonium fluoride and the contents and types of the water-soluble polymer were changed as shown in Table 1, and the same as in Example 1 above. Thus, an etching solution was prepared. Furthermore, the etching rate obtained with respect to the TEOS film and the silicon nitride film and the selectivity of the etching rate (silicon oxide film / silicon nitride film) were evaluated using the etching solution obtained in each example. The results are shown in Table 2 below.

(Comparative Examples 1 and 2)
In Comparative Examples 1-2, the content of hydrogen fluoride and ammonium fluoride was changed as shown in Table 1, and the same as Example 1 except that the water-soluble polymer was not added. Thus, an etching solution was prepared. Furthermore, using the etching solutions obtained in the respective comparative examples, the etching rate with respect to the TEOS film and the silicon nitride film and the selectivity of the etching rate (silicon oxide film / silicon nitride film) were evaluated. The results are shown in Table 2 below.

(Comparative Examples 3 to 7)
In Comparative Examples 3 to 7, the contents of hydrogen fluoride and ammonium fluoride were changed as shown in Table 1, except that the additives shown in Table 1 were used instead of the water-soluble polymer. An etching solution was prepared in the same manner as in Example 1. Furthermore, using the etching solutions obtained in the respective comparative examples, the etching rate with respect to the TEOS film and the silicon nitride film and the selectivity of the etching rate (silicon oxide film / silicon nitride film) were evaluated. The results are shown in Table 2 below.

  As apparent from Table 2, the additive added to the etching solution according to Comparative Examples 3 to 7 selectively suppresses the etch rate for the silicon nitride film, and selects the etch rate of the silicon oxide film for the silicon nitride film. The ratio (silicon oxide film / silicon nitride film) could not be increased.

  On the other hand, in the microfabricated surface treatment agents according to Examples 1 to 10, by adding a water-soluble polymer, the etch rate for the silicon nitride film is selectively suppressed, and the etch rate of the silicon oxide film for the silicon nitride film is reduced. It was confirmed that the selectivity (silicon oxide film / silicon nitride film) was increased.

(Example 11)
20.0 parts by weight of hydrogen fluoride (manufactured by Stella Chemifa Co., Ltd., high-purity grade for semiconductor, concentration 50% by weight) and 27 hydrochloric acid (manufactured by Hayashi Pure Chemical Industries, Ltd., electronic industry grade, concentration 36% by weight) 27 1.0 part by weight of polyacrylamide (concentration 50% by weight, weight average molecular weight 10,000) as a water-soluble polymer was added to a solution obtained by mixing 0.8 part by weight and 51.2 parts by weight of ultrapure water, and stirred. After mixing, the temperature of the mixture was adjusted to 25 ° C. and allowed to stand for 3 hours. As a result, an etching solution (fine processing agent) of 10% by weight of hydrogen fluoride, 10% by weight of hydrochloric acid, and 0.5% by weight of polyacrylamide was prepared.

  Next, the etch rate for the BPSG film as the silicon oxide film and the silicon nitride film was measured. Furthermore, the etch rate selectivity (silicon oxide film / silicon nitride film) was evaluated. The results are shown in Table 3 below.

(Example 12)
In Example 12, an etching solution was prepared in the same manner as in Example 11 except that the polyacrylamide content was changed as shown in Table 3. Furthermore, using the etching solution obtained in this example, the etching rate with respect to the BPSG film and the silicon nitride film and the selectivity of the etching rate (silicon oxide film / silicon nitride film) were evaluated. The results are shown in Table 3 below.

(Comparative Example 8)
In Comparative Example 8, an etching solution was prepared in the same manner as in Example 12 except that the water-soluble polymer was not added as shown in Table 3. Furthermore, using the etching solution obtained in this comparative example, the etching rate with respect to the BPSG film and the silicon nitride film and the selectivity of the etching rate (silicon oxide film / silicon nitride film) were evaluated. The results are shown in Table 3 below.

  As is clear from Table 3, in the etching solutions according to Examples 11 to 12, all of the etching rates for the silicon nitride film are selectively suppressed by adding polyacrylamide as a water-soluble polymer. It was confirmed that the etching ratio (silicon oxide film / silicon nitride film) of the etch rate of the silicon oxide film with respect to the silicon oxide increases.

(Example 13)
25.0 parts by weight of ammonium fluoride (manufactured by Stella Chemifa Co., Ltd., high purity grade for semiconductors, concentration 40% by weight) and hydrochloric acid (manufactured by Hayashi Junyaku Kogyo Co., Ltd., electronics industry grade, concentration 36% by weight) 27 To a mixed solution of 8 parts by weight and 45.2 parts by weight of ultrapure water, 2.0 parts by weight of polyacrylamide (concentration 50% by weight, weight average molecular weight 10,000) as a water-soluble polymer was added and stirred. After mixing, the temperature of the mixture was adjusted to 25 ° C. and allowed to stand for 3 hours. As a result, an etching solution (fine processing agent) containing 10% by weight of ammonium fluoride, 10% by weight of hydrochloric acid, and 1% by weight of polyacrylamide was prepared.

  Next, the etch rate for the TEOS film and the silicon nitride film as the silicon oxide film was measured. Furthermore, the etch rate selectivity (silicon oxide film / silicon nitride film) was evaluated. The results are shown in Table 4 below.

(Comparative Example 9)
In Comparative Example 9, an etching solution was prepared in the same manner as in Example 13 except that the water-soluble polymer was not added as shown in Table 4. Furthermore, using the etching solution obtained in this comparative example, the etch rate with respect to the TEOS film and the silicon nitride film and the selectivity of the etch rate (silicon oxide film / silicon nitride film) were evaluated. The results are shown in Table 4 below.

(Example 14)
25.0 parts by weight of ammonium fluoride (manufactured by Stella Chemifa Co., Ltd., high purity grade for semiconductor, concentration 40% by weight) and phosphoric acid (manufactured by Kishida Chemical Co., Ltd., electronics industry grade, concentration 85% by weight) To a mixed solution of 5 parts by weight and 49.5 parts by weight of ultrapure water, 2.0 parts by weight of polyacrylamide (concentration 50% by weight, weight average molecular weight 10,000) as a water-soluble polymer is added and mixed by stirring. After that, the temperature of the mixture was adjusted to 25 ° C. and left to stand for 3 hours. As a result, an etching solution (fine processing agent) containing 10% by weight of ammonium fluoride, 20% by weight of phosphoric acid, and 1% by weight of polyacrylamide was prepared.

  Next, the etch rate for the TEOS film and the silicon nitride film as the silicon oxide film was measured. Furthermore, the etch rate selectivity (silicon oxide film / silicon nitride film) was evaluated. The results are shown in Table 4 below.

(Comparative Example 10)
In Comparative Example 10, as shown in Table 4, an etching solution was prepared in the same manner as in Example 14 except that the water-soluble polymer was not added. Furthermore, using the etching solution obtained in this comparative example, the etch rate with respect to the TEOS film and the silicon nitride film and the selectivity of the etch rate (silicon oxide film / silicon nitride film) were evaluated. The results are shown in Table 4 below.

  As is apparent from Table 4, in the etching solutions according to Examples 13 to 14, the etch rate for the silicon nitride film is selectively suppressed by adding polyacrylamide as a water-soluble polymer, and the silicon nitride film It was confirmed that the etching ratio (silicon oxide film / silicon nitride film) of the etch rate of the silicon oxide film with respect to the silicon oxide increases.

Claims (3)

(A) at least one of 0.01 to 15% by weight of hydrogen fluoride or 0.1 to 40% by weight of ammonium fluoride;
(B) water,
(C) 0.001 to 10 wt% of the viewing contains a water-soluble copolymer of ammonium acrylate and methyl acrylate, at least a silicon oxide film, and a laminate film having a silicon nitride film stacked upon microfabrication A fine processing agent characterized by selectively finely processing a silicon oxide film . The fine processing agent according to claim 1 , wherein the water - soluble copolymer has a weight average molecular weight in a range of 1,000 to 1,000,000. By using a fine processing agent according to claim 1 or 2, the fine processing method, wherein at least the silicon oxide film, and a laminate film having a silicon nitride film stacked micromachining.