JP2021015967A - Silicon nitride film etching solution and manufacturing method of semiconductor devices using the same - Google Patents

Abstract

To provide a technique for preventing the generation of silicon-based particles by etching a silicon nitride film.SOLUTION: In a silicon nitride film etching solution and a manufacturing method of a semiconductor devices using the same, due to inclusion of second colloidal silica particles having an increased surface area in spherical first colloidal silica particles based on the same volume, a phenomenon in which the colloidal silica particles aggregate even at a high temperature is prevented, and the generation of the silicon-based particles is prevented, and the etching selectivity of a silicon oxide film 12 to a silicon nitride film 11 is improved under an etching condition of a laminated structure 20.SELECTED DRAWING: Figure 1

Description

The present invention relates to a silicon nitride film etching solution and a method for manufacturing a semiconductor device using the same. More specifically, the present invention is a silicon nitride film that prevents the generation of particles and increases the selectivity of the silicon oxide film to the silicon nitride film. The present invention relates to an etching solution and a method for manufacturing a semiconductor device using the etching solution.

Currently, there are various methods for etching a silicon nitride film and a silicon oxide film, but a dry etching method and a wet etching method are mainly used.

The dry etching method is usually an etching method using a gas, and although it has an advantage of being more isotropic than the wet etching method, it is too inferior in productivity to the wet etching method and is an expensive method. Wet etching methods are becoming widely used.

In general, as a wet etching method, a method using phosphoric acid as an etching solution is well known. At this time, when only pure phosphoric acid is used for etching the silicon nitride film, not only the silicon nitride film but also the silicon oxide film is etched as the device becomes finer, so that various defects and patterns are formed. Since problems such as abnormalities may occur, it is necessary to form a protective film on the silicon oxide film to further reduce the etching rate of the silicon oxide film.

The present invention increases the surface area of colloidal silica particles contained in the silicon additive in the silicon substrate etching solution to prevent the generation of particles, and increases the selectivity of the silicon oxide film to the silicon nitride film under the etching conditions. It is an object of the present invention to provide a silicon nitride film etching solution.

Another object of the present invention is to provide a method for manufacturing a semiconductor device, which is performed by using the above-mentioned silicon nitride film etching solution.

In order to solve the above-mentioned technical problems, according to one aspect of the present invention, the silicon additive contains a phosphoric acid aqueous solution and a silicon additive, and the silicon additive is a spherical first colloidal silica and a second colloidal silica particles. The surface area of the second colloidal silica particles is more than 100% and 124% or less with respect to the surface area of the spherical first colloidal silica particles based on the same volume, and is contained in the silicon additive. A silicon nitride film etching solution in which the content of the second colloidal silica particles is 50% or more is provided.

Further, according to another aspect of the present invention, there is provided a method for manufacturing a semiconductor device, which is performed by using the above-mentioned silicon nitride film etching solution.

The silicon nitride film etching solution according to the present invention contains the second colloidal silica particles having an increased surface area with respect to the spherical first colloidal silica particles based on the same volume, so that the colloidal silica particles can be formed even at a high temperature. It is possible to prevent the phenomenon of aggregation and prevent the generation of silicon-based particles.

Further, the second colloidal silica particles having an increased surface area used in the present application are silicon under etching conditions due to an increase in the amount of hydroxy groups (−OH) expressed with respect to the spherical first colloidal silica particles. It is possible to improve the etching selectivity of the silicon nitride film with respect to the oxide film.

FIG. 5 is a cross-sectional view schematically showing a step of removing a silicon nitride film using an etching solution according to an embodiment of the present invention.

The advantages and features of the present invention, and the methods for achieving them, will be clarified with reference to the examples described later. However, the present invention is not limited to the examples disclosed below, and is embodied in various different forms. However, the present embodiment is provided to complete the disclosure of the present invention and to fully inform a person having ordinary knowledge in the technical field to which the present invention belongs to the scope of the invention, and the present invention is claimed. It is only defined by the category of terms.

The silicon nitride film etching solution according to the present invention will be described in detail below.

Usually, in order to protect the silicon oxide film from the aqueous phosphoric acid solution, the silicon nitride film etching solution may contain a silicon additive, and as the silicon additive, spherical colloidal silica particles are used. Colloidal silica particles in the etching solution can aggregate and grow into silicon-based particles. When silicon-based particles grow, they act on the biggest cause of defective silicon substrates.

In addition, the spherical colloidal silica particles have a small amount of hydroxy group (-OH) expression, and the passivation of the silicon oxide film.
The role as a layer) cannot be sufficiently performed, and there arises a problem that the etching selectivity with respect to the silicon nitride film is lowered with respect to the silicon oxide film.

In order to solve the above-mentioned problems, the silicon nitride film etching solution according to the embodiment of the present invention contains a phosphoric acid aqueous solution and a silicon additive, and the silicon additive is a spherical first colloidal silica and a second. The surface area of the second colloidal silica particles is more than 100% and 124% or less with respect to the surface area of the spherical first colloidal silica particles based on the same volume, and the silicon. When the content of the second colloidal silica particles contained in the additive is 50% or more, the selectivity of the second colloidal silica particles to the silicon nitride film is increased with respect to the silicon oxide film, and the silicon-based particles are contained even if the temperature rises. It is possible to suppress the growth as.

Here, in the second colloidal silica particles of the present application, the shape of the spherical first colloidal silica particles is deformed, and the surface area is increased with respect to the spherical first colloidal silica particles based on the same volume. It can mean, and by way of example, the second colloidal silica particles of the present application may exhibit an elliptical, polyhedral, tablet, or rugby ball shape.

That is, in the second colloidal silica particles of the present application, the shape of the spherical first colloidal silica particles is deformed, and the occurrence of stacking of the silica particles is reduced even at a high temperature, thereby generating silicon-based particles. Can be prevented. Further, by preventing silicon-based particles, defects of elements and equipment failures embodied on the silicon substrate can be reduced.

Further, the surface area of the second colloidal silica particles of the present application is more than 100% and 124% or less with respect to the surface area of the spherical first colloidal silica particles based on the same volume.

Here, the fact that the surface area of the second colloidal silica particles of the present application exceeds 100% with respect to the surface area of the spherical first colloidal silica particles is based on the same volume as the spherical first colloidal silica particles. It means that the surface area has increased. Further, the surface area of the second colloidal silica particles of the present application is 124% or less of the surface area of the spherical first colloidal silica particles, based on the same volume as the spherical first colloidal silica particles. Means that does not exceed 124%.

When the surface area of the second colloidal silica particles is 100% or less of the surface area of the spherical first colloidal silica particles based on the same volume, it is represented on the surface of the spherical first colloidal silica particles. The amount of hydroxy groups does not increase, and the effect of improving the etching selectivity of the silicon nitride film with respect to the silicon oxide film may be weak. The second colloidal silica particles having a surface area of more than 124% with respect to the surface area of the spherical first colloidal silica particles based on the same volume have manufacturing restrictions, and particles are formed by bonding between the silica particles. sell.

Preferably, the surface area of the second colloidal silica particles of the present application may be 110% or more and 124% or less with respect to the surface area of the spherical first colloidal silica particles based on the same volume. More preferably, the surface area of the second colloidal silica particles of the present application may be 115% or more and 120% or less with respect to the surface area of the spherical first colloidal silica particles based on the same volume. With respect to the surface area of the spherical first colloidal silica particles based on the same volume, the effect of increasing the etching selectivity of the silicon oxide film to the silicon nitride film as the surface area of the second colloidal silica particles of the present application increases. There is.

That is, the second colloidal silica particles of the present application are first formed by deforming the shape of the spherical first colloidal silica particles and increasing the surface area based on the same volume as the spherical first colloidal silica particles. The hydroxy group (-OH) represented on the surface of the second colloidal silica particles is increased as compared with the colloidal silica particles of.

As described above, the second colloidal silica particles of the present application can exhibit more hydroxy groups than the spherical first colloidal silica particles. The hydroxy group binds to the silicon oxide film to form a siloxane, and the siloxane acts as a protective film that protects the silicon oxide film from the aqueous phosphoric acid solution. Therefore, the second colloidal silica particles of the present application can bond with the silicon oxide film to form more siloxane with respect to the spherical first colloidal silica particles, and more effectively protect the silicon oxide film. can do. In addition, the silicon nitride film etching solution containing the second colloidal silica particles of the present application can improve the etching selectivity of the silicon nitride film with respect to the silicon oxide film.

The content of the second colloidal silica particles contained in the silicon additive is 50% or more. As an example, the silicon additive may include spherical first colloidal silica particles and second colloidal silica particles, and the silicon additive may contain relative to the content of the spherical first colloidal silica particles. , The content of the second colloidal silica particles may be the same or higher. Preferably, the content of the second colloidal silica particles contained in the silicon additive may be 70% or more. More preferably, the content of the second colloidal silica particles contained in the silicon additive may be 90% or more. As another example, the silicon additive does not have to contain the spherical first colloidal silica particles, in which case the content of the second colloidal silica particles contained in the silicon additive is 100%. It may be. When the content of the second colloidal silica particles contained in the silicon additive is less than 50%, stacking of the silica particles occurs at a high temperature, whereby silicon-based particles can be generated. When the content of the second colloidal silica particles is less than 50%, the amount of increase in hydroxy groups represented on the surface of the silica particles is small, and the etching selectivity of the silicon oxide film is improved with respect to the silicon nitride film. The effect can be weak.

The above-mentioned silicon additive is preferably present in the silicon nitride film etching solution at 100 to 100,000 ppm. Further, it is more preferable that the above-mentioned silicon additive is present in the silicon nitride film etching solution at 100 to 10,000 ppm. Here, the content of the silicon additive is the amount of the silicon additive dissolved in the silicon nitride film etching solution, and is shown in units of ppm.

For example, the presence of the silicon additive in the silicon nitride film etching solution at 100 ppm may mean that the silicon additive dissolved in the silicon nitride film etching solution is 100 ppm.

When the silicon additive is present at 100 ppm in the silicon nitride film etching solution, the amount of the silane compound is not sufficient under the etching conditions, and the effect of increasing the etching selectivity of the silicon oxide film with respect to the silicon nitride film is weak. possible.

On the other hand, when the silicon additive exceeds 100,000 ppm in the silicon nitride film etching solution, there may be a problem that silicon-based particles are generated due to an increase in the saturation concentration of the silane compound in the silicon nitride film etching solution.

The silicon substrate preferably contains at least a silicon oxide film (SiO _x ), and may contain both a silicon oxide film and a silicon nitride film. Further, in the case of a silicon substrate containing both a silicon oxide film and a silicon nitride film, the silicon oxide film and the silicon nitride film may be alternately laminated or may be laminated in different regions.

Here, the silicon oxide film is an SOD (Spin On Dielectric) film or HDP (High Density) depending on the application and the type of material.
Plasma) film, thermal oxide film, BPSG (Borophosphate)
Silicate Glass (Silicate Glass) Membrane, PSG (Phospho Silicate Glass) Membrane, BSG (Boro Silicate)
Glass) film, PSZ (Polysilazane) film, FSG (Fluorinated Silicate)
Glass) film, LP-TEOS (Low)
Pressure Tera Ethyl Ortho Silicate) Membrane, PETEOS (Plasma Enhanced Tera)
Ethyl Ortho Silicate) Membrane, HTO (High Temperature Oxide) Membrane, MTO (Medium)
Temperature Oxide (Temperature Oxide) Membrane, USG (Unloaded Silicate Glass) Membrane, SOG (Spin On Glass) Membrane, APL (Advanced Development)
Layer) membrane, ALD (Atomic Layer)
Deposition membrane, PE-oxide membrane (Plasma Enhanced oxide) or O _3- TEOS (O _3- Tetra Ethyl)
Ortho Silicate) and the like.

Here, the phosphoric acid aqueous solution is a component that etches the silicon nitride film and maintains the pH of the etching solution to prevent the silicon additive present in the etching solution from changing into silicon-based particles.

In one example, the phosphoric acid aqueous solution is preferably contained in an amount of 60 to 90 parts by weight with respect to 100 parts by weight of the silicon nitride film etching solution.

If the content of the phosphoric acid aqueous solution is less than 60 parts by weight with respect to 100 parts by weight of the silicon nitride film etching solution, the etching rate of the silicon nitride film decreases and the silicon nitride film is not sufficiently etched or silicon nitrided. The efficiency of the film etching process may decrease.

On the other hand, when the content of the phosphoric acid aqueous solution exceeds 90 parts by weight with respect to 100 parts by weight of the silicon nitride film etching solution, oxidation occurs as the etching rate of the silicon oxide film increases with respect to the etching rate of the silicon nitride film. The etching selectivity of the silicon nitride film to the film may decrease, and the etching of the silicon oxide film causes a defect of the silicon substrate.

The silicon nitride film etching solution according to an embodiment of the present invention is a fluorine-containing compound in order to compensate for the etching rate of the silicon nitride film, which is lowered by using the silicon additive, and to improve the efficiency of the overall etching process. May further be included.

The fluorine-containing compounds in the present application refer to all compounds in any form that dissociate fluorine ions.

In one example, the fluorine-containing compound is at least one selected from hydrogen fluoride, ammonium fluoride, ammonium bicarbonate, and ammonium hydrogen fluoride.

In still another embodiment, the fluorine-containing compound may be a compound in which an organic cation and a fluorine anion are ionically bonded.

For example, the fluorine-containing compound may be a compound in which an alkylammonium and a fluorine-based anion are ionically bonded. Here, the alkylammonium is an ammonium having at least one alkyl group and may have up to four alkyl groups. The definition for the alkyl group is as described above.

In yet another example, the fluorine-containing compounds are alkylpyrrolium, alkylimidazolium, alkyloxazolium, alkylpyridinium, alkylpyrimidinium, alkylpyridazinium, alkylpyrazinium, alkylpyrrolidinium, alkylphosphonium. , Alkylation morpholinium, dialkyl imidazolium, and alkyl piperidinium, and selected from fluorophosphates, fluoroalkyl-fluorophosphates, fluoroborates, and fluoroalkyl-fluoroborates. It may be an ionic liquid in which a fluorine-based anion is ionically bonded.

Among the silicon nitride film etching solutions, the fluorine-containing compound provided in the form of an ionic liquid has a higher boiling point and decomposition temperature than hydrogen fluoride or ammonium fluoride which is generally used as a fluorine-containing compound, and at a high temperature. There is an advantage that there is little possibility of changing the composition of the etching solution due to decomposition during the etching process performed.

According to another aspect of the present invention, there is provided a method for manufacturing a semiconductor device, which is carried out using the above-mentioned silicon nitride film etching solution.

According to this manufacturing method, a semiconductor device is manufactured by performing a selective etching step on a silicon nitride film using the above-mentioned etching solution on a silicon substrate containing at least a silicon nitride film (SI _x N _y ). Is possible.

The silicon substrate used for manufacturing the semiconductor element may include a silicon nitride film (SI _x N _y ), or may contain both a silicon oxide film and a silicon nitride film. Further, in the case of a silicon substrate containing both a silicon oxide film and a silicon nitride film, the silicon oxide film and the silicon nitride film may be alternately laminated or may be laminated in different regions.

The method for manufacturing a semiconductor device according to the present invention can be applied to a manufacturing process for a NAND device. More specifically, among the laminated structures for forming NAND, the above-mentioned etching solution is used in a process step in which selective removal of the silicon nitride film is required without loss to the silicon oxide film. You may be broken.

As an example, FIG. 1 is a schematic cross-sectional view for explaining a step of removing a silicon nitride film using an etching solution according to the present invention.

Referring to FIG. 1, a mask pattern layer 30 is formed on a laminated structure 20 in which a silicon nitride film 11 and a silicon oxide film 12 are alternately laminated on a silicon substrate 10, and then an anisotropic etching step is performed. The trench 50 is formed.

Further, referring to FIG. 1, the etching solution according to the present invention is injected through the trench 50 region formed in the laminated structure 20, and the silicon nitride film 11 is etched by this to etch the silicon oxide film 12 and the mask. Only the pattern layer 30 remains.

That is, the present invention minimizes the etching of the silicon oxide film 12 in the laminated structure 20 by using an etching solution having an improved etching selectivity for the silicon nitride film with respect to the silicon oxide film, and within a sufficient time. The silicon nitride film 11 can be completely and selectively removed. After that, the semiconductor device can be manufactured through a subsequent step including a step of forming a gate electrode in the removed region of the silicon nitride film 11.

Hereinafter, specific examples of the present invention will be presented. However, the examples described below are merely for exemplifying or explaining the present invention, and the present invention should not be restricted by this.

Example
Manufacture of etching solution
Manufacturing example 1
Tetraethyl orthosilicate
0.1 g equivalent of Orthosilicate, TEOS), 10 mL of water, 100 mL of ethanol, and 1 mL of ammonium hydroxide (NH ₄ OH) were stirred for 30 minutes and then left to stand for about 1 hour. Silica was produced by repeating the steps of stirring and leaving the mixture 20 times. The surface area of the manufactured silica and the surface area of the spherical colloidal silica (manufacturer: Yonil Kasei Co., Ltd., product name: YGS) were measured according to the BET method. Spherical colloidal silica based on the same volume (manufacturer:
The surface area of the manufactured silica was 123% of the surface area of Yongil Kasei Co., Ltd., product name: YGS).

Manufacturing example 2
The same composition as in Production Example 1 was left at room temperature for 3 days to produce silica. The surface area of the manufactured silica and the surface area of the spherical colloidal silica (manufacturer: Yonil Kasei Co., Ltd., product name: YGS) were measured according to the BET method. Based on the same volume, the surface area of the manufactured silica was 115% of the surface area of the spherical colloidal silica (manufacturer: Yonil Kasei Co., Ltd., product name: YGS).

Manufacturing example 3
The same composition as in Production Example 1 was stirred at about 300 RPM for 2 hours and then left to stand for about 30 minutes. The steps of stirring and leaving the mixture were repeated 20 times to produce a silicon additive. The surface area of the manufactured silica and the surface area of the spherical colloidal silica (manufacturer: Yonil Kasei Co., Ltd., product name: YGS) were measured according to the BET method. Based on the same volume, the surface area of the manufactured silica was 109% of the surface area of the spherical colloidal silica (manufacturer: Yonil Kasei Co., Ltd., product name: YGS).

Manufacturing example 4
A composition having the same composition and content as that of Production Example 1 was stirred at about 300 RPM for 24 hours to produce a silicon additive. The surface area of the manufactured silica and the surface area of the spherical colloidal silica (manufacturer: Yonil Kasei Co., Ltd., product name: YGS) were measured according to the BET method. Based on the same volume, the surface area of the manufactured silica was 102% with respect to the surface area of the spherical colloidal silica (manufacturer: Yonil Kasei Co., Ltd., product name: YGS).

Example 1
85% by weight of phosphoric acid, 70 ppm of silica according to Production Example 1, spherical colloidal silica (manufacturer: Yonil Kasei Co., Ltd., product name: YGS) 30 ppm, and the remaining amount of water are mixed to prepare a silicon nitride film etching solution. Manufactured.

Example 2
85% by weight of phosphoric acid, 90 ppm of silica according to Production Example 2, spherical colloidal silica (manufacturer: Yonil Kasei Co., Ltd., product name: YGS) 10 ppm, and the remaining amount of water are mixed to prepare a silicon nitride film etching solution. Manufactured.

Example 3
85% by weight of phosphoric acid, 70 ppm of silica according to Production Example 3, spherical colloidal silica (manufacturer: Yonil Kasei Co., Ltd., product name: YGS) 30 ppm, and the remaining amount of water are mixed to prepare a silicon nitride film etching solution. Manufactured.

Example 4
A silicon nitride film etching solution is prepared by mixing 85% by weight of phosphoric acid, 50 ppm of silica according to Production Example 4, 50 ppm of spherical colloidal silica (manufacturer: Yonil Kasei Co., Ltd., product name: YGS), and the remaining amount of water. Manufactured.

Comparative Example 1
A silicon nitride film etching solution was produced by mixing 85% by weight of phosphoric acid, spherical colloidal silica (manufacturer: Yonil Kasei Co., Ltd., product name: YGS) 100 ppm, and the remaining amount of water.

Comparative Example 2
A silicon nitride film etching solution is prepared by mixing 85% by weight of phosphoric acid, 10 ppm of silica according to Production Example 4, 90 ppm of spherical colloidal silica (manufacturer: Yonil Kasei Co., Ltd., product name: YGS), and the remaining amount of water. Manufactured.

Experimental Example A silicon nitride film etching solution having the composition according to Examples 1 to 4 and Comparative Examples 1 and 2 was added to a heated etching solution at 175 ° C. and a silicon oxide film (thermal oxide layer) having a thickness of 500 Å and a silicon nitride film. Immersed and etched for 10 minutes.

Before and after etching, the thickness of the silicon oxide film and the silicon nitride film is determined by ellipsometry (Nano-View, SE).
It is measured using MG-1000; Ellipometry), and the etching rate is a numerical value calculated by dividing the difference in thickness between the silicon oxide film and the silicon nitride film by the etching time (10 minutes) before and after etching. Is.

The measured etching rates are shown in Table 1 below.

As shown in Table 1 above, the silicon nitride film etching solutions of Examples 1 to 4 can reduce the etching rate for the silicon oxide film as compared with the silicon nitride film etching solutions of Comparative Examples 1 and 2. It can be confirmed that the etching selectivity for the silicon nitride film is improved with respect to the silicon oxide film.

In the above, one embodiment of the present invention has been described, but if the person has ordinary knowledge in the technical field, addition of components within the range not deviating from the idea of the present invention described in the claims. The present invention can be modified and changed in various ways by modification, deletion, addition, etc., and it can be said that this is also included in the scope of rights of the present invention.

10 Silicon substrate 11 Silicon nitride film 12 Silicon oxide film 20 Laminated structure 30 Mask pattern layer

50 trench

Claims (8)

Phosphoric acid aqueous solution;
Silicone additive; including
The silicon additive comprises spherical first colloidal silica and second colloidal silica particles.
Based on the same volume, the surface area of the second colloidal silica particles is more than 100% and 124% or less with respect to the surface area of the spherical first colloidal silica particles.
The content of the second colloidal silica particles contained in the silicon additive is 50% or more.
Silicon nitride film etching solution. The surface area of the second colloidal silica particles is 110% or more and 124% or less with respect to the surface area of the spherical first colloidal silica particles based on the same volume.
The silicon nitride film etching solution according to claim 1. The silicon additive is contained in the silicon nitride film etching solution at an amount of 100 to 100,000 ppm.
The silicon nitride film etching solution according to claim 1. The silicon nitride film etching solution is characterized by further containing at least one fluorine-containing compound selected from hydrogen fluoride, ammonium fluoride, ammonium bicarbonate, and ammonium hydrogen fluoride.
The silicon nitride film etching solution according to claim 1. The silicon nitride film etching solution is characterized by further containing a fluorine-containing compound having a form in which an organic cation and a fluorine anion are ionically bonded.
The silicon nitride film etching solution according to claim 1. The organic cations include alkyl-imidazolium, dialkyl-imidazolium, alkyl-pyridinium, alkylpyrrolidinium, alkylphosphonium, alkylphosphonium. It is characterized in that it is at least one selected from alkylmorpholinium (Alkyl-morpholinium) and alkylpiperidinium (Alkyl-piperidinium).
The silicon nitride film etching solution according to claim 5. The fluoroan anion is selected from at least one selected from fluorophosphate, fluoroalkyl-fluorophosphate, fluoroborate, and fluoroalkyl-fluoroborate. Characterized by being one,
The silicon nitride film etching solution according to claim 5. A method for manufacturing a semiconductor device, which comprises an etching step performed by using the silicon nitride film etching solution according to claim 1.

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