JP3467411B2 - Etching solution, method for producing the same and etching method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an etching solution for a silicon nitride film, a method of manufacturing the same, and a method of etching the same, and more particularly to measures for improving an etching selection ratio with a silicon oxide film.

[0002]

2. Description of the Related Art Conventionally, in a manufacturing process of a semiconductor device, a LOCOS film made of a thick oxide film surrounding an active region of a semiconductor substrate is formed in order to electrically isolate elements arranged in the semiconductor device from each other. The technology to do is widely used. 1A to 1D are cross-sectional views showing the steps of forming this LOCOS film.

First, in a step shown in FIG. 1A, a silicon oxide film 2 functioning as a pad oxide film is formed on a silicon substrate 1, and a silicon nitride film 3 serving as a mask at the time of oxidation is formed thereon. Form. Next, in the step shown in FIG. 1B, the silicon nitride film 3 and the silicon oxide film 2 are patterned to form an opening 5 in a region where a LOCOS film is to be formed, and a silicon substrate in the opening 5 is formed. Exposing the surface of 1. Then, in the step shown in FIG. 1C, an oxidation process is performed using the silicon nitride film 3 as a mask to oxidize the silicon substrate 1 exposed in the opening 5 to form a thick silicon oxide film in the opening 5. The LOCOS film 4 that grows and functions as an element isolation region is formed.

Then, in the step shown in FIG.
After the formation of the OS film 4, in order to remove the silicon nitride film 3 which has been the oxidation mask, an etching process with a phosphoric acid solution boiled in a temperature range of 150 ° C. to 170 ° C. is performed.

This phosphoric acid solution has an etching selection ratio of a high etching rate for a silicon nitride film and a low etching rate for a silicon oxide film.
The silicon nitride film 3 can be selectively removed without removing the LOCOS film 4 made of a silicon oxide film. The phosphoric acid solution used for removing the silicon nitride film 3 is a highly pure solution in which particles and impurities in the solution are extremely reduced in order to minimize contamination on the wafer surface. There is.

Here, the etching rate of the conventional phosphoric acid solution with respect to the silicon nitride film and the silicon oxide film will be described. The etching rate of the phosphoric acid solution heated to about 160 ° C. for the silicon nitride film is about 4.0 nm / m.
and the etching rate for the silicon oxide film is about 0.12 to 0.13 nm / min. That is, the etching selection ratio for the silicon nitride film and the silicon oxide film is about 30.

On the other hand, the silicon nitride film 3 shown in FIG.
If not completely removed, the subsequent steps will be hindered. Therefore, overetching is performed for a predetermined time even after it is determined that the removal of the silicon nitride film 3 is completed. Specifically, the time required for removing the silicon nitride film 3 is 50
Since it is general to secure an over-etching time of approximately 100%, when removing the silicon nitride film 3 having a thickness of 100 nm, over-etching is performed for 13 to 25 minutes after the silicon oxide film 2 is exposed. Then, the silicon oxide film 2 is etched during that time. When the thickness of the silicon nitride film 3 is 160 nm,
Over-etching for 20-40 minutes is required. In particular, in order to suppress the bird's beak, the larger the thickness of the silicon nitride film, the more advantageous it is.
Has a tendency to increase to a thickness of about 200 nm.

Here, when the silicon oxide film 2 as a pad oxide film is completely removed and the lower silicon substrate 1 is exposed after the etching of the silicon nitride film 3 is completed,
It has been found that the silicon substrate 1 is etched by phosphoric acid vapor. Therefore, it is necessary to overetch the silicon nitride film 3 under the condition that the silicon oxide film 2 under the silicon nitride film 3 is not completely removed.

[0009]

However, the conventional method of etching a silicon nitride film with hot phosphoric acid has the following problems.

When the silicon nitride film 3 used as a mask is over-etched, the silicon oxide film 2 which is a pad oxide film existing under the silicon nitride film 3 is also slightly removed. In the manufacturing process of the semiconductor device formed by the design rule larger than the 0.5 μm rule, the film thickness of the pad oxide film is about 20 nm, which is sufficiently thick.
Even after over-etching with a phosphoric acid solution after the pad oxide film was exposed, the pad oxide film was not completely removed and the silicon substrate was not exposed.

However, with the miniaturization of the elements in the semiconductor device, the pad oxide film must be as thin as possible in order to suppress the invasion amount of the transverse beak in the lateral direction during the oxidation of LOCOS and to secure the widest active area. preferable. Further, in order to suppress the dimension shift due to the standing wave at the time of lithography, it is preferable that the pad oxide film is thin. For these reasons, for example, a device whose design rule is miniaturized to 0.35 μm or less is 5 n
A thin silicon oxide film of about m is provided below the silicon nitride film. When the pad oxide film becomes thin in this way, the silicon substrate below the pad oxide film may be exposed due to the above-described overetching.

Therefore, as disclosed in, for example, Japanese Patent Application Laid-Open No. 9-45660, a compound (fluorine compound) that produces fluorine ions in an etching solution composed of hot phosphoric acid solution.
There is known a technique for improving the etching selection ratio by adding Al. According to this technique, by adding a fluorine compound to the hot phosphoric acid solution, the etching rate for the silicon nitride film is improved, and as a result, the etching selection ratio for the silicon oxide film and the silicon nitride film is about 1/50 to 1/70. It is said to improve to.
Therefore, the reduction of the over-etching time can prevent the pad oxide film from being removed as much as possible during that time.

However, when the etching is advanced while circulating the hot phosphoric acid containing the fluorine compound, the etching rates for the silicon oxide film and the silicon nitride film change greatly with the passage of time, and the silicon oxide film and the silicon nitride film are changed. The etching selectivity ratio with respect to and was 1/25 in the first batch, but was 1/10 in the 10th batch.
The number becomes 63, and becomes 1/27 to 1/20 in the 13th batch, which is a large change with the passage of time (see the same publication).

See column). This phenomenon is considered to be due to the fact that the fluorine compound hydrolyzes into F ⁻ ions and functions as hydrofluoric acid (HF). Then, it is considered that by circulating at a high temperature for a long time, the hydrofluoric acid evaporates and the etching rate for the silicon oxide film and the silicon nitride film decreases.

From the above results, when the fluorine compound is added to the hot phosphoric acid solution, the etching cannot be performed at a stable etching rate immediately after the use of the etching solution,
It is difficult to implement due to process control.

Further, as another problem, when the etching of the wafer is repeated, Si _n O _n-2 which is a compound generated by the etching is added to the filter in the circulation system of the phosphoric acid solution.
Since (OH) _{n + 2} is deposited and clogging occurs, its maintenance is required. For example, about 1000 to 20
Drain the liquid after processing 00 sheets, replace the filter, or
There is also a problem that the operation rate of the apparatus is lowered because it is necessary to perform a cleaning operation using a solution that etches Si _n O _n-2 (OH) _{n + 2} such as F.

The present invention has been made in view of the above problems, and its main purpose is to maintain a stable etching rate for a silicon nitride film and a silicon oxide film and to have a high etching selection ratio for both. An object of the present invention is to provide an etching solution capable of exhibiting the above, a manufacturing method thereof, and an etching method.

[0017]

A first etching liquid of the present invention is a phosphoric acid liquid, an organic compound containing silicon, and an organic compound containing silicon dissolved in the phosphoric acid liquid. The above silicon containing an organic solvent as a solvent for
The organic solvent in which the organic compound containing
It is adjusted by adding it to the acid solution .

As a result, the etching rate of the etching solution for the silicon oxide film and the silicon nitride film is maintained in a stable range with respect to the increase in the number of wafers to be processed, and the etching rate for the silicon oxide film is significantly low. Therefore, the etching selection ratio between the silicon nitride film and the silicon oxide film is increased. Therefore,
It is possible to prevent the silicon oxide film from being partially removed during the overetching of the silicon nitride film.

The above solvent is a solvent compatible with the phosphoric acid solution.
Is preferred, and lower aliphatic alcohol
Is more preferable, and further, an organic compound containing the above silicon
The compound is a lower aliphatic alcohol that is compatible with the above phosphoric acid solution.
It is preferably soluble in alcohol.

The second etching solution of the present invention comprises a phosphoric acid solution and the following structural formulas (1), (2) and (3).

[0021]

[Chemical 10]

[0022]

[Chemical 11]

[0023]

[Chemical 12]

A silicon nitride film and a silicon film containing a silicon-containing compound containing at least one of the organic compounds represented by and a solvent for dissolving the silicon-containing compound in the phosphoric acid solution. The etching selectivity with respect to the oxide film is adjusted to be a predetermined value or more.

Tetraethoxysilane is a typical compound containing silicon.

A first etching method of the present invention comprises a step of forming a silicon oxide film and a silicon nitride film on a substrate,
Existence as a solvent in which an organic compound containing silicon is dissolved
Etching is performed using an etching solution obtained by adding an organic solvent to a phosphoric acid solution, and the silicon nitride film is removed while leaving the silicon oxide film.

By this method, it becomes possible to selectively remove only the silicon nitride film by utilizing the high etching selection ratio as described above.

The second etching method of the present invention is applied to a substrate.
A step of forming a silicon oxide film and a silicon nitride film,
Compound containing silicon is dissolved in phosphoric acid solution through solvent.
Etching is performed using the resulting etching solution, and
The silicon nitride film is removed while the silicon oxide film remains.
And the compound containing silicon is
Structural formulas (1), (2) and (3)

[0029]

[Chemical 13]

[0030]

[Chemical 14]

[0031]

[Chemical 15]

At least one of the organic compounds represented by
Includes one or the other .

The compound containing silicon is tetraeth
It is preferably xysilane.

In the step of etching the silicon nitride film, it is preferable to raise the temperature of the etching solution in the range of 145 ° C. to 170 ° C.

The manufacturing method of the first etching solution of the present invention includes the steps of dissolving the organic compound containing silicon in an organic solvent <br/> as solvent after the step, an organic compound containing the silicon and organic Adding a solvent to the phosphoric acid solution to melt the organic compound containing silicon in the phosphoric acid solution .

By this method, the compound containing silicon can be surely dissolved in the phosphoric acid solution, and the etching solution having a high etching selection ratio with respect to the silicon nitride film and the silicon oxide film can be obtained.

The above solvent is a solvent which is compatible with the phosphoric acid solution.
Is preferred, and lower aliphatic alcohol
Is more preferable, and further, an organic compound containing the above silicon
The compound is a lower aliphatic alcohol that is compatible with the above phosphoric acid solution.
It is preferably soluble in alcohol.

A second method for producing an etching solution according to the present invention comprises a step of dissolving a compound containing silicon in a solvent,
After the above step, was added to the compound and phosphoric acid solution and the solvent containing the silicon, Ri the compounds containing the silicon
And a step of melting in a phosphoric acid solution , wherein the compound containing silicon has the following structural formulas (1), (2) and (3):

[0039]

[Chemical 16]

[0040]

[Chemical 17]

[0041]

[Chemical 18]

It contains at least one of the organic compounds represented by:

The compound containing silicon is tetraeth
It is preferably xysilane.

[0044]

BEST MODE FOR CARRYING OUT THE INVENTION First, the experiments conducted in the process of the invention will be described.

Conventionally, the phosphoric acid solution used for etching the silicon nitride film has a phosphoric acid content of 75% or more. The etching solution after etching the silicon nitride film with this phosphoric acid solution was analyzed. Table 1 below
Indicates the analysis result.

[0046]

[Table 1]

As shown in Table 1, silicon ions (Si) and ammonium ions (NH ₄ ) were detected in the etching solution. From this, phosphoric acid (H ₃
It was estimated that by etching the silicon nitride film (Si ₃ N ₄ ) with PO ₄ ), the reaction according to the following reaction formula (1) proceeded, and polysiloxane and ammonium phosphate were generated. However, polysiloxane is a general term for substances having a siloxane bond —Si—O— in the main chain.

Si ₃ N ₄ + H ₃ PO ₄ + H ₂ 0 → Si _n O _n-2 (OH) _{n + 2} + (NH ₄ ) ₃ PO ₄ (1) Fine device with a design rule of 0.5 μm or less Then, the thickness of the silicon nitride film serving as the oxidation mask is 20
If the thickness of the pad oxide film is 0 nm and the thickness is 5 nm, the silicon oxide film and the silicon nitride film have an etching rate of 4.0 nm / min or more in the silicon nitride film in the range of the phosphoric acid solution temperature of 160 ± 10 ° C. 0.06 nm / min or less (more preferably 0.0
4 nm / min or less) (that is, the etching selection ratio between the silicon nitride film and the silicon oxide film is 67 or more). On the other hand, it has been found that such conditions are satisfied by an etching solution under certain conditions, such as processing a wafer for an extremely long time. As a result of analyzing a phosphoric acid solution satisfying these preferable conditions, silicon ion is 40 ppm and ammonium ion is 30 ppm.
ppm was detected.

Therefore, quartz particles (fumed silica; SiO ₂ ) are mixed in the phosphoric acid solution, the temperature is raised to 150 ° C. and the mixture is dissolved for 100 hours, and further ammonia is dropped to add silicon ions and ammonium. An etching solution was prepared so that the concentration of each ion was about 30 ppm. While circulating the phosphoric acid solution, the etching solution was heated to about 160 ° C. and the etching rates of the silicon oxide film and the silicon nitride film were measured. As a result, the etching rate for the silicon oxide film was 0.08 nm / min. .

Here, in the etching experiment of the present embodiment, the silicon nitride film 3 which causes the above-described change from the state shown in FIG. 1C to the state shown in FIG. 1D is etched.

As described above, the etching rate of the pure phosphoric acid solution with respect to the silicon oxide film is 0.13 nm / mi.
Since it is about n, it can be seen that the etching rate is significantly reduced. Further experiments have revealed that the presence of silicon ions results in a stable lowering of the etching rate of the phosphoric acid solution with respect to the silicon oxide film.

However, 0.06 nm / min, which is a preferable condition for manufacturing a fine device under the 0.5 μm rule as described above, has not been reached. It is presumed that this is because the concentration of silicon ions and ammonium ions reaches a certain limit.

On the other hand, as described in the above publication, the addition of a substance that produces fluorine ions to the phosphoric acid solution has a certain effect of improving the solubility of quartz particles in the phosphoric acid solution.
As described above, it was found that stable etching cannot be performed from the initial state of the etching solution.

Therefore, in the present invention, an experiment using an organic silicon compound was conducted in order to improve the solubility. In that case, since the organic silicon compound is not simply dissolved in the phosphoric acid solution, water, an organic solvent, particularly an alcohol compatible with phosphoric acid was used as a solvent. As the organic compound containing silicon, a compound having solubility in alcohol compatible with phosphoric acid, such as tetraethoxysilane (TEOS) and 3-aminopropitoltriethoxysilane, was selected.

The results of experiments conducted using an organic compound containing silicon will be described below.

-Relationship between Silicon Ion Concentration and Etching Rate- First, ethanol was used as a solvent, and TEOS (tetraethoxysilane) was used as an organic compound containing silicon. The adjustment procedure is as follows.

A mixed solution is prepared by dissolving ethanol and TEOS in a ratio of 1: 1. Next, this mixed solution is added to a phosphoric acid solution to form an etching solution having a TEOS amount of 200 μL and a silicon ion concentration of 50 ppm, and TEO.
An etching solution having an S amount of 80 μL and a silicon ion concentration of 20 ppm and an etching solution having a TEOS amount of 2.1 mL and a silicon ion concentration of 510 ppm were prepared.

These etching solutions were heated to about 160 ° C. and the etching rates for the silicon oxide film and the silicon nitride film were measured. As a result, the etching rate of the etching liquid containing 20 ppm of silicon ions with respect to the silicon oxide film was 0.06 nm / min. The etching rate of the etching solution containing 50 ppm of silicon ions with respect to the silicon oxide film is 0.02 nm.
It was / min. In addition, silicon ion 510p
The etching rate of the etching liquid containing pm with respect to the silicon oxide film was 0 or less. At this time, the etching rates of the above etching solutions for the silicon nitride film are:
Both are stable at 4.4 to 4.8 nm / min.

FIG. 2 shows the results of investigating the relationship between the concentration of this silicon ion and the etching rate for the silicon oxide film, by making etching solutions containing silicon ions of various concentrations using tetraethoxysilane and ethanol. FIG. In the figure, the horizontal axis represents the concentration (ppm) of silicon ions in the phosphoric acid solution, and the vertical axis represents the etching rate (nm / min) for the silicon oxide film.

As shown in the figure, it is presumed that the appropriate concentration of silicon ions is 20 ppm to 500 ppm. When an etching solution containing 510 ppm of silicon ions was used, a deposit was observed in the etching solution after 1 hour. From this, 500 in phosphoric acid solution
It is presumed that silicon ions above ppm are in a supersaturated state.

Further, as a result of studying the concentration of silicon ions so that the etching rate with respect to the silicon oxide film becomes stable at 0.04 nm / min or less, when the variation between wafers is taken into consideration, the concentration of silicon ions is 25 p.
It is preferably at least pm.

On the other hand, when the concentration of silicon ions was further increased, it was observed that the etching rate for the silicon oxide film tended to grow in the reverse direction from approximately 0 at around 150 ppm. Increasing the amount of silicon ions added means that over-saturated silicon is deposited on the filter installed in the liquid circulation system during repeated processing of etching and removing the silicon nitride film, and Because of clogging, the life of the liquid is shortened when the number of processed wafers is used as a reference.

Therefore, an appropriate concentration for ensuring the service life of filters and liquid exchange is 25 ppm to 150 ppm.
ppm is preferred.

-Type of compound containing silicon-
The relationship between the concentration of silicon ions and the etching rate for the silicon oxide film is different between the case where TEOS as a compound containing silicon is added to the phosphoric acid solution and the case where 3-aminopropyltriethoxysilane is added to the phosphoric acid solution. I understood it.

Table 2 below shows the results of an etching experiment using an etching solution in which TEOS and 3-aminopropyltriethoxysilane were added at different silicon ion concentrations. However, the data of the film thickness measurement values are three-point values, and the variation of the measurement values is ± 2 nm due to the accuracy of the equipment.

[0066]

[Table 2]

As can be seen from Table 2 above, TEOS and 3
-When using aminopropyltriethoxysilane,
Unless the concentration of silicon ions is higher than that in the case of TEOS, the etching rate for the silicon oxide film and the silicon nitride film cannot be controlled to the above preferable conditions. When TEOS is used, if the concentration of silicon ions in the etching solution is 50 ppm, the etching rate for the silicon oxide film is 0.027n.
It becomes m / min. However, when 3-aminopropyltriethoxysilane is used, the etching rate for the silicon oxide film cannot be set to 0.029 nm / min unless the concentration of silicon ions in the etching solution is as high as 730 ppm. This is probably because TEOS and 3-aminopropyltriethoxysilane are different in the dissociation state of each ion in the etching solution.

In particular, a substance represented by the form of polysiloxane Si _n O _n-2 (OH) _{n + 2} in the above reaction formula (1) after a compound containing silicon is dissolved in a phosphoric acid solution. Is present in the phosphoric acid solution, it seems that the etching rate for the silicon oxide film is significantly suppressed and the etching for the silicon nitride film is not hindered. The concentration of the polysiloxane _{Si n O n-2 (OH} ) n + material represented in a form such as _2, since regarded as substantially equivalent to the concentration of silicon ions, the phosphoric acid solution, a polysiloxane Si _n O It is preferable that the substance represented by a form such as _n-2 (OH) _{n + 2} is present at a concentration of 20 to 500 ppm, and it can be seen from the data of FIG.
More preferably it is present at a concentration of pm.

-Other Examples of Compounds Containing Silicon-Table 3 below shows data showing etching rates when other compounds containing silicon are dissolved in a phosphoric acid solution under the condition that the concentration of silicon ions is 50 ppm. is there.

[0070]

[Table 3]

As shown in Table 3, it can be seen that various compounds can be used. As this compound, those represented by the following structural formulas (1), (2) and (3) are particularly suitable. Has been confirmed.

[0072]

[Chemical 19]

[0073]

[Chemical 20]

[0074]

[Chemical 21]

According to this embodiment, the following effects can be obtained by using the etching solution prepared by dissolving the compound containing silicon as described above in the phosphoric acid solution.

The etching solution of this embodiment has a very low etching rate with respect to the silicon oxide film.
Even if the silicon oxide film below the silicon nitride film is a thin oxide film like the nitride film mask at the time of OCOS formation, the silicon nitride film can be over-etched so that the silicon substrate is not exposed.

In this case, mass productivity of this new phosphoric acid solution can be secured by simplifying the method of dissolving the compound containing silicon for controlling the etching rate for each film species in the phosphoric acid solution.

Further, in order to suppress the etching rate of the silicon oxide film of the phosphoric acid solution, Si _n O _n-2 (OH) _{n + 2}
It is possible to add a compound containing silicon so that the substance having such a shape has a correct concentration. In other words, never concentration in the form of a substance such as _{Si n O n-2 (OH} ) n + 2 in accordance with a phosphate solution narrowing dissolving the silicon nitride film in the previous product processing is excessive (supersaturated) Therefore, the life of the liquid due to clogging of the filter was 1800 in the past, but has been extended to 2500.

In the present embodiment, the concentration of the solvent for dissolving the organic silicon compound such as TEOS was set to the ratio of TEOS and ethanol of 1: 1 in this example. However, since there is currently 10% variation between the set value in the preparation and the actually measured concentration value, the amount of the organic solvent for the organic silicon compound has a margin of 10% or more with respect to the saturation concentration of dissolution. It is preferable.

In the phosphoric acid solution test of this embodiment, a quartz tank equipped with a heater, an in-line heater for raising the temperature of the phosphoric acid solution outside the quartz tank, and a dust trap in the etching solution are used. A filter equipped with a filter and a circulating pump driven by air pressure was used.

When an etching solution containing silicon ions in a supersaturated state is used, polysiloxane Si _n O _n-2 (O
H) It is preferable not to use in a supersaturated state, because a substance represented by a form such as _{n + 2} is deposited on the filter and causes clogging.

[0082]

According to the present invention, a compound containing silicon is dissolved in a phosphoric acid solution through a solvent and is used as an etching solution for a silicon nitride film. Therefore, the etching rate for a silicon oxide film is extremely small. ,
In addition, an etching solution capable of stably maintaining an etching rate for a silicon nitride film and applicable to selective etching of a nitride film mask after LOCOS formation of a fine device of 0.5 μm rule or later, its manufacturing method, and An etching method can be provided.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a process for forming a LOCOS film.

FIG. 2 is a diagram showing a silicon ion concentration dependency of an etching rate of an etching solution with respect to a silicon oxide film.

[Explanation of symbols]

1 Silicon substrate 2 Silicon oxide film 3 Silicon nitride film 4 LOCOS film

Claims (18)

(57) [Claims] 1. A phosphoric acid solution, an organic compound containing silicon, and an organic solvent as a solvent for dissolving the organic compound containing silicon in the phosphoric acid solution, wherein the organic compound containing silicon is dissolved. The above organic solution
Etching solution obtained by adding a chemical to the above phosphoric acid solution. 2. The etching solution according to claim 1, wherein The above solvent must be compatible with the phosphoric acid solution.
Characteristic etching liquid. 3. The etching solution according to claim 2, wherein The solvent is a lower aliphatic alcohol
Etching solution. 4. The etching solution according to claim 3, The organic compound containing silicon is compatible with the phosphoric acid solution.
Solubility in low-grade aliphatic alcohol
Etching liquid characterized by. 5. A phosphoric acid solution and the following structural formulas (1), (2) and (3): [Chemical 2] [Chemical 3] In including at least one of the organic compound represented by a compound containing silicon, a compound containing the above silicon and a solvent for dissolving the above phosphate solution, and a silicon nitride film and a silicon oxide film An etching solution that is adjusted so that the etching selection ratio with respect to is not less than a predetermined value. 6. The etching solution according to claim 5, wherein the compound containing silicon is tetraethoxysilane. 7. A step of forming a silicon oxide film and a silicon nitride film on a substrate, and a step of using as a solvent in which an organic compound containing silicon is dissolved.
Etching is performed using an etching solution obtained by adding an organic solvent to phosphoric acid solution, and the silicon nitride film is removed while leaving the silicon oxide film. 8. The etching method according to claim 7,
hand, The above solvent must be compatible with the phosphoric acid solution.
Characteristic etching method. 9. The etching method according to claim 8.
hand, The solvent is a lower aliphatic alcohol
Etching method. 10. A silicon oxide film and a silicon nitride film are formed on a substrate.
The step of forming a film and dissolving the silicon-containing compound in a phosphoric acid solution via a solvent.
Etching is performed using the resulting etching solution, and
The silicon nitride film is removed while the silicon oxide film remains.
The compound containing silicon has the following structural formula (1):
(2) and (3) [of 4] [Chemical 5] [Chemical 6] At least one of the organic compounds represented by
Etching method including . 11. The etching method according to claim 10.
The compound containing silicon is tetraethoxysilane.
An etching method characterized by being present . 12. The etching method according to any one of claims 7 to 11, wherein in the step of etching the silicon nitride film, the etching solution is heated to a temperature in the range of 145 ° C to 170 ° C. An etching method which is performed by heating. 13. the organic compound containing silicon and a solvent
A step of dissolving in an organic solvent Te, after the step, an organic compound containing the silicon and organic
Adding a solvent to the phosphoric acid solution to melt the organic compound containing silicon in the phosphoric acid solution . 14. The method for producing an etching solution according to claim 13, wherein the solvent is a solvent compatible with a phosphoric acid solution. 15. The method for producing an etching solution according to claim 14, wherein the solvent is a lower aliphatic alcohol. 16. The method for producing an etching solution according to claim 15, wherein the organic compound containing silicon is compatible with the phosphoric acid solution.
Solubility in low-grade aliphatic alcohol
And a method for producing an etching solution. 17. A process for a compound containing silicon is dissolved in a solvent, after the step, is added to the compound and phosphoric acid solution and the solvent containing the silicon, Ri the compounds containing the silicon
And a step of melting in a phosphoric acid solution , wherein the compound containing silicon has the following structural formula (1):
(2) and (3) [of 7] [Chemical 8] [Chemical 9] The manufacturing method of the etching liquid containing at least any one of the organic compounds represented by. 18. Production of the etching solution according to claim 17.
In the method The compound containing silicon is tetraethoxysilane.
Characterized by being Etching liquid manufacturing method.