KR101320421B1 - Etchant composition method for forming pattern with the same - Google Patents

Abstract

The present invention relates to an etching solution, the etching solution according to an embodiment of the present invention is 1 to 20% by weight of ammonium fluoride (NH ₄ F), 0.1 to 10% by weight of phosphoric acid (H ₃ PO ₄ ) relative to the total weight of the composition , Ammonium hydrogen fluoride (NH ₄ HF ₂ ) 0.1 to 5% by weight and the balance may include deionized water.

Description

Etching solution and pattern forming method of the insulating film using the same {Etchant composition method for forming pattern with the same}

The present invention relates to an etching solution and a pattern forming method of an insulating film using the same, and more particularly, to an etching solution capable of uniformly etching a silicon oxide film and a silicon nitride film and a pattern forming method of an insulating film using the same.

The silicon oxide film (SiO ₂ ) and the silicon nitride film (SiNx) are used as representative insulating films used in semiconductor manufacturing processes, and may be used alone, or one or more layers of silicon oxide and one or more layers of silicon nitride are alternately stacked. . In addition, the silicon oxide film and the silicon nitride film are also used as a hard mask for forming a conductive pattern such as metal wiring.

Conventionally, after etching the upper silicon nitride film by a dry etching method of etching the insulating film on which the silicon oxide film and the silicon nitride film is laminated, and then the silicon of the lower silicon silicon oxide etching solution such as BOE (Buffered Oxide Etchant) The oxide film was etched to form an insulating film pattern.

BOE (Buffered Oxide Etchant), which is widely used as a silicon oxide etching solution, is an etching solution containing hydrogen fluoride (HF) and ammonium fluoride (NH ₄ F). In addition, the etching rate of the silicon oxide layer was much higher than that of the silicon nitride layer, resulting in an undercut phenomenon caused by excessive etching to the side of the silicon oxide layer.

As described above, the occurrence of the undercut phenomenon causes a poor step coverage of the metal film deposited in a subsequent process, and in severe cases, causes a short circuit of the deposited metal film.

On the other hand, Korean Patent No. 10-0823461 has a use for etching silicon oxide film and silicon nitride film, hydrogen fluoride (HF) 0.5 to 3% by weight, ammonium fluoride (NH ₄ F) 20 to 40% by weight and azole compound 0.1 ˜10% by weight and the balance consists of deionized water and additionally discloses a composition consisting of 0.1-10% by weight of ammonium bifluoride (NH ₄ HF ₂ ).

However, due to the content of the ammonium fluoride (NH ₄ F) 20 to 40% by weight due to precipitation occurs during the process, a problem due to the damage caused to the a-Si, ITO film is highlighted.

KR 10-0823461 B1, April 14, 2008 KR 10-0379824 B1, June 26, 2002

Accordingly, the technical problem of the present invention was conceived in this respect, and an object of the present invention is to provide an etching solution of a new composition ratio having an etching characteristic which is reliable, has an excellent etching profile and uniformity, and can shorten processing time.

Still another object of the present invention is to provide a method of forming an insulating film using the etching solution.

The etching solution according to the present invention is 1 to 20% by weight of ammonium fluoride (NH ₄ F), 0.1 to 10% by weight phosphoric acid (H ₃ PO ₄ ), and 0.1 to 0.1% by weight of ammonium bifluoride (NH ₄ HF ₂ ) based on the total weight of the composition. 5% by weight and the balance include deionized water.

According to an embodiment of the present invention, the solution may further include hydrochloric acid.

According to an embodiment of the present invention, the hydrochloric acid may be included in 0.01 to 0.5% by weight based on the total weight of the composition.

According to an embodiment of the present invention, the ammonium fluoride (NH ₄ F) is adjusted to 5 to 15% by weight, the ammonium hydrogen fluoride (NH ₄ HF ₂ ) may be adjusted to 0.3 to 3% by weight.

Method for forming a pattern of the insulating film according to the present invention is 1 to 20% by weight of ammonium fluoride (NH ₄ F), 0.1 to 10% by weight of phosphoric acid (H 3 PO 4), 0.1 to 10% by weight of ammonium bifluoride (NH ₄ HF ₂ ) Preparing an etching solution including 5% by weight and the rest of deionized water, preparing a substrate, forming a dielectric film by stacking heterogeneous insulating films on the substrate, and forming a photoresist pattern on the insulating film Dry etching the insulating film selectively exposed by the photoresist pattern, and etching the insulating film with the etching solution on the substrate on which the dry etching is performed.

According to an embodiment of the present disclosure, preparing the substrate may include forming an amorphous silicon (α-Si) layer, an ITO conductive film, or a conductive layer stacked sequentially.

According to an embodiment of the present invention, the forming of the insulating film may include sequentially stacking a silicon oxide film and a silicon nitride film on the conductive layer.

The etching solution according to the present invention has the property of simultaneously etching the silicon oxide film and the silicon nitride film, thereby not only forming an excellent insulating film pattern but also causing corrosion of the conductive layer under the insulating film made of the silicon oxide film and the silicon nitride film. There is an advantage that does not.

In addition, the etching solution according to the present invention not only reduces the difference in the etching rate between the silicon oxide film and the silicon nitride film, but also has an excellent etching profile and uniformity, significantly reducing damage to the substrate, and shortening the processing time. Finally, there is an advantage that can increase the reliability of the device.

FIG. 1 is a photograph of a silicon oxide film and a silicon nitride film formed by alternately stacking two layers in a single layer, and forming a pattern by a photolithography process and confirming a dry etching state using a scanning electron microscope (SEM).
FIG. 2 is a wet etching process of a silicon oxide film and a silicon nitride film with an etchant prepared with the composition of Comparative Example 1 (A) and Example 6 (2) on a substrate in which a silicon oxide film and a silicon nitride film are stacked in double layers in a single layer alternately. One state is confirmed by scanning electron microscopy (SEM).
3 is a photograph of a substrate on which an amorphous silicon (α-Si) layer is formed, using a scanning electron microscope (SEM).
FIG. 4 illustrates a state in which an amorphous silicon (α-Si) layer is wet-etched with an etchant prepared with the composition of Comparative Example 1 (A) and Example 6 (2) on a substrate on which an amorphous silicon (α-Si) layer is formed. It is a photograph confirmed by a scanning electron microscope (SEM).
5 is a photograph confirming the substrate on which the ITO conductive film is formed by a scanning electron microscope (SEM).
FIG. 6 is an etching solution prepared by the composition of Comparative Example 1 (A) and Example 6 (2) on a substrate on which an ITO conductive film is formed, and shows a state in which an amorphous silicon (α-Si) layer is wet-etched. This is a confirmed picture.

BRIEF DESCRIPTION OF THE DRAWINGS The advantages and features of the present invention and the manner of achieving them will become apparent with reference to the embodiments described in detail below with reference to the accompanying drawings. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. The embodiments may be provided to make the disclosure of the present invention complete, and to fully inform the scope of the invention to those skilled in the art. Like reference numerals refer to like elements throughout the specification.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. In the present specification, the singular form includes plural forms unless otherwise specified in the specification. It is to be understood that the terms 'comprise', and / or 'comprising' as used herein may be used to refer to the presence or absence of one or more other components, steps, operations, and / Or additions.

Hereinafter, with reference to the accompanying drawings will be described in detail the pattern formation method of the etching solution and the insulating film using the same according to an embodiment of the present invention.

Etching solution according to an embodiment of the present invention is 1 to 20% by weight of ammonium fluoride (NH ₄ F), 0.1 to 10% by weight of phosphoric acid (H ₃ PO ₄ ), ammonium hydrogen fluoride (NH ₄ HF _{2 based} on the total weight of the composition ) 0.1 to 5% by weight, and deionized water such that the total weight of the total composition is 100%.

In addition, the etching solution according to an embodiment of the present invention is 1 to 20% by weight of ammonium fluoride (NH ₄ F), 0.1 to 10% by weight of phosphoric acid (H ₃ PO ₄ ), ammonium hydrogen fluoride (NH ₄₎ HF ₂ ) 0.1 to 5% by weight, hydrochloric acid to 0.01 to 10% by weight, and deionized water such that the total weight of the total composition is 100%.

More preferably, the etching solution according to an embodiment of the present invention is 5 to 15% by weight of the ammonium fluoride (NH ₄ F), 0.1 to 10% by weight of the phosphoric acid (H ₃ PO ₄ ), the fluoride Ammonium hydride (NH ₄ HF ₂ ) may include 0.3 to 3% by weight, 0.05 to 0.5% by weight of hydrochloric acid and deionized water to 100% of the total weight of the total composition.

The composition ratio of the etching solution according to the embodiment of the present invention overcomes the problems of the conventional etching solution due to the specificity of the semiconductor device, thereby increasing the reliability of the device and significantly reducing damage to the substrate compared to the conventional etching solution. In addition, it has an excellent etching profile and uniformity and is formulated in consideration of the process time, and may have an important meaning for the purpose of the present invention.

The content of ammonium fluoride may be adjusted to 1 to 20% by weight, more preferably 5 to 15% by weight. When the content is less than 1% by weight, the etching rate difference between the silicon oxide film and the silicon nitride film is increased, and when the content is more than 20% by weight, the etching rate of the silicon oxide film may be too low.

The content of ammonium bifluoride (NH ₄ HF ₂ ) may be 0.1 to 5% by weight, more preferably 0.3 to 3% by weight. As the ammonium bifluoride content increases, the etching rate of the silicon oxide film and the silicon nitride film increases, but when the content exceeds 5% by weight, the etching rate of the silicon oxide film is relatively higher, so that the etching rate of the silicon oxide film and the silicon nitride film is relatively higher. The difference may become large and may not be desirable. In contrast, when the content of ammonium bifluoride is less than 0.1% by weight, the effect of the addition of ammonium bifluoride may be insignificant.

Etching solution according to an embodiment of the present invention by using hydrochloric acid in place of the existing hydrofluoric acid not only reduces the difference in the etching rate of the silicon oxide film and silicon nitride film, but also provides an excellent etching profile and uniformity, poly-Si (Poly-Si ) Or significantly reduce the damage of amorphous silicon (α-Si), and by containing 0.1 to 10% by weight of phosphoric acid significantly reduces the damage to the ITO conductive film substrate, excellent etching profile and uniformity The process time can be shortened and the reliability of the device can be finally increased.

More specifically, when the content of the hydrochloric acid is less than 0.05% by weight may cause damage to polysilicon or atypical silicon, such damage may occur more at less than 0.01% by weight of the hydrochloric acid. . On the contrary, when the amount of hydrochloric acid exceeds 0.5% by weight, the etching rate may be affected, resulting in deterioration of the profile, damage to the substrate, and damage to the ITO conductive layer, and damage to polysilicon or amorphous silicon. It may also occur. Such damage may occur more when the amount of hydrochloric acid exceeds 10% by weight.

When the phosphoric acid content exceeds 10% by weight, the etching rate of the silicon oxide film is rapidly increased. When the phosphoric acid content is less than 0.1% by weight, the etching rate difference between the silicon oxide film and the silicon nitride film is 350 (Å / min ) May be undesirable.

Subsequently, a pattern forming method of the insulating film using the etching solution according to the embodiment of the present invention described above will be described in detail. Here, the overlapping information about the above-described etching solution may be omitted or simplified.

The pattern forming method of the insulating film according to an embodiment of the present invention comprises the steps of preparing a substrate, sequentially forming a silicon oxide film and a silicon nitride film on the substrate to form an insulating film, a photoresist on the silicon nitride film by a photolithography process The method may include forming a pattern, dry etching the silicon nitride layer, and etching the silicon oxide layer with the etching solution described above.

The forming of the insulating layer may include forming at least one or more layers of a silicon oxide layer and a silicon nitride layer on the substrate. The forming of the photoresist pattern includes forming a resist film on the insulating film and performing a photolithography process on the resist film to form a resist pattern having a line or hole shape. can do.

The etching of the insulating layer with the etching solution according to an embodiment of the present invention may be performed under process conditions that proceed for 30 seconds to 10 minutes while maintaining the temperature of the etching solution at 20 to 40 ℃. When the temperature is lower than 20 ° C. under the process conditions, the etching rate of the silicon nitride film may be lowered, which may be undesirable. On the contrary, when the temperature exceeds 40 ° C., fume may be generated, which may be undesirable.

The substrate is characterized in that it comprises an amorphous silicon (α-Si) layer, an ITO conductive film or a conductive layer sequentially stacked below the silicon oxide film. The etching solution according to the present invention has the property of simultaneously etching the silicon oxide film and the silicon nitride film, so that not only an excellent insulating film pattern can be formed, but also a conductive layer (eg, indium tin) disposed under the insulating film made of the silicon oxide film and the silicon nitride film. Oxide: ITO) also does not cause corrosion. Corrosion inhibitory effect of the ITO is shown in Figures 5 and 6, which is that the phosphoric acid contained in the etching solution of the present invention to suppress the corrosion damage to the conductive layer, such as indium tin oxide (ITO) This may be because it plays a role. However, when the content of phosphoric acid is less than 0.1% by weight, the effect of inhibiting corrosion damage to the conductive layer as described above may be insufficient. On the other hand, when the content of phosphoric acid is more than 10% by weight, it is excellent in inhibiting the corrosion damage to the conductive layer as described above, but due to the difference in the etching rate ratio of the hetero insulating layer between the oxide film and the nitride film, non-uniform etching occurs Can be.

Hereinafter, the present invention will be described in more detail through evaluation of etching characteristics using specific examples and comparative examples of the present invention.

[ Comparative Example ]

A substrate in which a silicon oxide film 3000 GPa / silicon nitride film 2000 GP was formed on a bare glass substrate by chemical vapor deposition (CVD) was prepared.

The etching solution of the silicon oxide film and the silicon nitride film was prepared by adjusting the content of the components of Comparative Examples 1 to 4 of Table 1 below.

 [ Example ]

A substrate in which a silicon oxide film 3000 GPa / silicon nitride film 2000 GP was formed on a bare glass substrate by chemical vapor deposition (CVD) was prepared.

The etching solution of the silicon oxide film and the silicon nitride film was prepared by adjusting the content of the components of Examples 1 to 6 of Table 1.

[ Test Example  1] Depending on the content of each component Etching speed

The etching rate of the silicon oxide film and the silicon nitride film was evaluated using the etching solution prepared in Comparative Examples and Examples.

As can be seen from the results of the etching rate using the etching solution of Comparative Example 2 and Example 5, that is, in Table 2, etching of the silicon oxide film and the silicon nitride film by adding hydrochloric acid (HCl) in place of hydrofluoric acid (HF) It can be seen that the speed difference is significantly reduced.

In addition, in the results of the etching rate using the etching solution of Example 4 and Example 5, it was confirmed that the difference in the etching rate between the silicon oxide film and the silicon nitride film according to the addition amount of hydrochloric acid (HCl).

In other words, by adding hydrochloric acid to the etching solution of the present invention from the above results, the damage to the amorphous silicon in the etching of the silicon oxide film and silicon nitride film can be reduced. Here, the content of the hydrochloric acid may be preferably adjusted to 0.01% to 0.5% by weight. More preferably, the amount of hydrochloric acid may be adjusted to 0.05% to 0.15% by weight. When the hydrochloric acid is added in less than 0.05% by weight, the effect of reducing the damage to the amorphous silicon may be insignificant. On the other hand, when the hydrochloric acid is added in excess of 0.15% by weight, the acidity of the etchant is out of the desired acidity value, the non-uniform interlayer etching can be generated for the hetero insulating layer having a different etching selectivity. In particular, when the hydrochloric acid is added in excess of 0.5% by weight, such non-uniform etching occurs.

In addition, in the result of Table 2, when the hydrochloric acid is added to the etching solution, that is, when the phosphoric acid content from the etching solution of Comparative Examples 3 and 4, Example 4 and Example 6 exceeds 10% by weight of silicon It was confirmed that the etching rate of the oxide film is rapidly increased, and when the phosphoric acid content is less than 0.1% by weight, the etching rate difference between the silicon oxide film and the silicon nitride film was found to be greater than 350 (min / min).

In addition, by adding phosphoric acid to the etching solution of the present invention has the effect of improving the etching profile and uniformity and shorten the process time.

From the above results, the etching solution of the silicon oxide film and the silicon nitride film containing the composition and content of the present invention has the advantage of increasing the reliability of the device.

Claims (11)

An etching solution for simultaneously etching silicon oxide and silicon nitride,
5 to 15% by weight of ammonium fluoride (NH ₄ F), 0.1 to 10% by weight of phosphoric acid (H ₃ PO ₄ ), 0.1 to 5% by weight of ammonium bifluoride (NH ₄ HF ₂ ), 0.01 to 5% by weight of the total composition Etching solution containing 0.5% by weight and the rest deionized water. The method of claim 1,
The ammonium hydrogen fluoride (NH ₄ HF ₂ ) is an etching solution containing 0.3 to 3% by weight. delete delete 3. The method according to claim 1 or 2,
Hydrochloric acid in the etching solution is an etching solution containing 0.05 to 0.15% by weight. 5 to 15% by weight of ammonium fluoride (NH ₄ F), 0.1 to 10% by weight of phosphoric acid (H ₃ PO ₄ ), 0.1 to 5% by weight of ammonium bifluoride (NH ₄ HF ₂ ), 0.05 to 5% by weight of the total composition Preparing an etching solution including 0.5% by weight and the rest of deionized water;
Preparing a substrate;
Forming a silicon oxide film on the substrate;
Forming a silicon nitride film on the silicon oxide film;
Dry etching the silicon nitride film; And
Wet etching the silicon oxide film using the etching solution; Pattern forming method of an insulating film comprising a. delete The method according to claim 6,
Preparing the substrate is:
Preparing a semiconductor substrate; And
Forming an amorphous silicon (α-Si) layer, an ITO conductive film, or a conductive layer sequentially stacked on the semiconductor substrate;
The wet etching of the insulating film may include etching the insulating film without corrosion of the conductive layer. 9. The method according to claim 6 or 8,
The etching solution is a pattern forming method of the insulating film containing ammonium bifluoride (NH ₄ HF ₂ ) 0.3 to 3% by weight. delete 9. The method according to claim 6 or 8,
Hydrochloric acid in the etching solution comprises a pattern of 0.05 to 0.15% by weight.

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