KR20180120866A - EUV mask cleansing solution and method of fabrication of the same - Google Patents

Abstract

A method for cleaning an EUV mask is provided. The EUV mask cleaning method is a process for removing contaminants generated in an EUV lithography process, comprising the steps of: preparing a cleaning solution comprising a quaternary ammonium basic aqueous solution and an organic solvent; providing the cleaning solution on an EUV mask to clean the EUV mask; rinsing the cleaned EUV mask; and drying the rinsed EUV mask.

Description

[0001] The present invention relates to an EUV mask cleaning solution and a method of cleaning the same,

The present invention relates to an EUV mask cleaning solution and a cleaning method thereof, and more particularly to an EUV mask cleaning solution including a basic solution and an organic solvent, and a cleaning method thereof.

[This study was carried out as a result of a research project # 10045366, which will be supported by the Ministry of Commerce, Industry and Energy and the Korea Semiconductor Research Consortium (KSRC)

As the pattern of the semiconductor device becomes finer, the conventional ArF immersion lithography process approaches the limit of pattern line width fineness, and studies for fine patterning of less than 20 nanometers are under way by applying extreme ultraviolet (EUV) lithography process.

Since the extreme ultraviolet rays of a short wavelength of 13.5 nm used in an extreme ultraviolet lithography process are easily absorbed by all materials, an extreme ultraviolet reflective mask using a multilayer film in which silicon and molybdenum are repeatedly deposited is applied, Extreme ultraviolet light reaches the wafer surface through the reflective optical system.

In the above process, the contaminants generated on the surface of the reflection type mask and the reflection type optical system cause defects in the pattern formation. The contaminants absorb the extreme ultraviolet light to lower the extreme ultraviolet reflectance of the mask and the optical system, The line width of the fine pattern is increased and it is difficult to form a precise pattern.

In order to solve these problems, various pollution cleaning methods have been developed. For example, Korean Patent Laid-Open Publication No. 10-2017-0015067 (Application No. 10-2015-0162014, Applicant: Taiwan Semiconductor Device Co., Ltd.) discloses a method of manufacturing a photo- An acoustic energy generator configured to generate acoustic energy comprising a mechanical vibration of a megasonic frequency and a wavelength, an acoustic energy generator configured to generate an acoustically stimulated fluid stream directed to a second side of the photomask And a fluid distributor coupled to the acoustic energy generator such that acoustic energy generated by the acoustic energy generator is received by the fluid distributor, wherein the first side of the photomask is opposite the second side of the photomask, The first side provides an EUV mask cleaning system and method comprising a pattern.

In addition, various techniques for cleaning the contaminants generated in the EUV lithography process are continuously being researched and developed.

Korean Patent Laid-Open No. 10-2017-0015067

An object of the present invention is to provide an EUV mask cleaning solution and a cleaning method therefor that are excellent in the contamination cleaning effect generated in the EUV lithography process.

It is another object of the present invention to provide an EUV mask cleaning solution and a cleaning method thereof that can minimize damage to the surface of an EUV mask when cleaning contaminants generated in the EUV lithography process.

Another object of the present invention is to provide an EUV mask cleaning solution and a cleaning method thereof that can easily reuse an EUV mask after performing a contaminant cleaning process occurring in an EUV lithography process.

The technical problem to be solved by the present invention is not limited to the above.

According to an aspect of the present invention, there is provided an EUV mask cleaning method.

According to one embodiment, the EUV mask cleaning method comprises the steps of: preparing a cleaning solution containing a quaternary ammonium basic aqueous solution and an organic solvent in a process of cleaning an EUV mask used in an EUV lithography process; Providing the EUV mask to clean the EUV mask, rinsing the cleaned EUV mask, and drying the rinsed EUV mask.

According to one embodiment, the concentration of the organic solvent may be more than 60 wt% to less than 80 wt%.

According to one embodiment, the EUV mask cleaning method may include a change in the concentration of the organic solvent depending on the concentration of the quaternary ammonium basic aqueous solution.

According to one embodiment, the step of cleaning the EUV mask may include the step of megasonicizing the cleaning solution.

According to one embodiment, a contaminant containing hydrocarbon may be generated on the EUV mask in the EUV lithography process, and the contaminant may be removed by the cleaning solution.

According to an aspect of the present invention, there is provided an EUV mask cleaning solution.

According to one embodiment, the EUV mask cleaning solution comprises a quaternary ammonium basic aqueous solution and an organic solvent with a concentration of greater than 60 wt% and less than 80 wt%, in a cleaning solution for cleaning an EUV mask used in an EUV lithography process can do.

According to one embodiment, the quaternary ammonium basic aqueous solution may include at least one of tetramethylammonium hydroxide (TMAH), tetraethylammonium hydroxide (TEAH), tetrapropylammonium hydroxide (TPAH), and tetrabutylammonium hydroxide (TBAH).

According to one embodiment, the organic solvent may include at least one of dimethyl sulfoxide (DMSO) and tetrahydrofuran (THF).

The EUV mask cleaning solution according to an embodiment of the present invention may include a quaternary ammonium basic aqueous solution and an organic solvent having a concentration of more than 60 wt% and less than 80 wt%. The cleaning solution can easily remove contaminants formed on the EUV mask used in the EUV lithography process. Thus, the lowering of the reflectivity of the EUV mask surface is prevented, and the damage of the EUV mask surface can be minimized.

As a result, in the process of cleaning the EUV mask used in the EUV lithography process, when the cleaning solution is used, the EUV mask can be easily reused.

1 is a flowchart illustrating an EUV mask cleaning method according to an embodiment of the present invention.
2 is a view showing an EUV mask cleaning process according to an embodiment of the present invention.
3 is a graph showing the cleaning effect of the quaternary ammonium basic solution and the DMSO organic solvent in the EUV mask cleaning method according to the embodiment of the present invention with respect to concentration and time.
4 is a photograph of the cleaning effect of the EUV cleaning solution according to the concentration of the quaternary ammonium basic aqueous solution and the organic solvent according to the embodiment of the present invention.
FIG. 5 is a graph showing the efficiency according to the concentrations of the quaternary ammonium basic aqueous solution and the organic solvent included in the EUV mask cleaning solution according to the embodiment of the present invention.
FIG. 6 is a photograph of the cleaning effect of the quaternary ammonium basic aqueous solution and the DMSO organic solvent in the EUV mask cleaning method according to the embodiment of the present invention, according to the concentration and time.
FIG. 7 is a photograph showing the characteristics of the EUV mask cleaning solution according to the concentration of the organic solvent included in the cleaning solution according to the embodiment of the present invention.
FIG. 8 is a graph comparing FTIR of precipitates precipitated in an EUV mask cleaning solution and FTIR of an organic solvent according to an embodiment of the present invention.
FIG. 9 is a photograph showing the effect of a cleaning solution to determine the concentration of an organic solvent in accordance with the concentration of a quaternary ammonium basic aqueous solution of an EUV cleaning solution according to an embodiment of the present invention.
10 is a graph showing the cleaning effect according to the kind of the quaternary ammonium basic aqueous solution of the EUV mask cleaning solution according to the embodiment of the present invention.
FIGS. 11 and 12 are photographs illustrating the cleaning effect according to the concentration of the organic solvent included in the EUV cleaning solution according to the embodiment of the present invention.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, the technical spirit of the present invention is not limited to the embodiments described herein but may be embodied in other forms. Rather, the embodiments disclosed herein are provided so that the disclosure can be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.

In this specification, when an element is referred to as being on another element, it may be directly formed on another element, or a third element may be interposed therebetween. Further, in the drawings, the thicknesses of the films and regions are exaggerated for an effective explanation of the technical content.

Also, while the terms first, second, third, etc. in the various embodiments of the present disclosure are used to describe various components, these components should not be limited by these terms. These terms have only been used to distinguish one component from another. Thus, what is referred to as a first component in any one embodiment may be referred to as a second component in another embodiment. Each embodiment described and exemplified herein also includes its complementary embodiment. Also, in this specification, 'and / or' are used to include at least one of the front and rear components.

The singular forms "a", "an", and "the" include plural referents unless the context clearly dictates otherwise. It is also to be understood that the terms such as " comprises "or" having "are intended to specify the presence of stated features, integers, Should not be understood to exclude the presence or addition of one or more other elements, elements, or combinations thereof.

In the following description of the present invention, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention rather unclear.

FIG. 1 is a flowchart illustrating an EUV mask cleaning method according to an embodiment of the present invention, and FIG. 2 is a view illustrating an EUV mask cleaning process according to an embodiment of the present invention.

Referring to FIGS. 1 and 2, a cleaning solution 120 containing a quaternary ammonium basic aqueous solution and an organic solvent is prepared (S110).

According to one embodiment, the quaternary ammonium basic aqueous solution may include at least one of tetramethylammonium hydroxide (TMAH), tetraethylammonium hydroxide (TEAH), tetrapropylammonium hydroxide (TPAH), and tetrabutylammonium hydroxide (TBAH).

According to one embodiment, the organic solvent may include at least one of dimethyl sulfoxide (DMSO) and tetrahydrofuran (THF).

According to one embodiment, the cleaning solution 120 may be a solution in which the quaternary ammonium aqueous solution, the organic solvent, and DI water are mixed. For example, the cleaning solution 120 may be a solution in which TBAH, DMSO, and DI water are mixed at a ratio of 10: 50: 40 wt%.

The cleaning efficiency of the cleaning solution 120 may vary depending on the concentration of the quaternary ammonium basic aqueous solution and the organic solvent. According to one embodiment, the concentration of the organic solvent may be varied depending on the concentration of the quaternary ammonium basic aqueous solution. According to one embodiment, the concentration of the quaternary ammonium aqueous solution may be greater than 0.3M. According to one embodiment, the concentration of the quaternary ammonium aqueous solution may comprise more than 2 wt%. According to one embodiment, the concentration of the organic solvent may be more than 60 wt% to 80 wt%.

The cleaning solution 120 may be provided in the EUV mask 100 so that the EUV mask 100 may be cleaned (S120). According to one embodiment, the step of cleaning the EUV mask 100 may be performed for a period of time greater than 10 minutes.

According to one embodiment, the cleaning solution 120 may be used to clean an EUV mask 100 used in an extreme ultra violet (EUV) lithography process. Specifically, in the EUV lithography process, contaminants 110 may be generated on the EUV mask 100. For example, the contaminant 110 may include hydrocarbons. Specifically, the contaminant 110 may be a non-polar hydrocarbon compound. The contaminants 110 on the EUV mask 100 can be removed by the cleaning solution 120.

According to another embodiment, the cleaning solution 120 may be used to remove the contaminants 110 formed on a substrate used in a semiconductor process, except for an EUV lithography process.

According to one embodiment, the cleaning solution 120 may be filled into the lab 130. The EUV mask 100 on which the contaminants 110 are formed may be contained in the cleaning solution 120. For example, the EUV mask 100 on which the contaminants 110 are formed may be immersed in the cleaning solution 120 for 30 minutes. Accordingly, the contaminant 110 can be cleaned with the cleaning solution 120.

According to one embodiment, the cleaning solution 120 does not include an oxidizing agent in order to prevent damage to the surface of the EUV mask 100 during the process of removing the contaminants 110 .

According to one embodiment, cleaning the EUV mask 100 may include agitating the cleaning solution 120. For example, the cleaning solution 120 may be megasonicized and agitated. In another example, the cleaning solution 120 may be agitated at a speed of 200 rpm using a magnetic bar. Accordingly, the cleaning solution 120 can easily remove the contaminants 110.

According to one embodiment, cleaning the EUV mask 100 may include heat treating the cleaning solution 120. According to one embodiment, the cleaning solution 120 may be heat-treated at a temperature ranging from 50 ° C to 80 ° C. As the cleaning solution 120 is heat-treated, the reactivity between the cleaning solution 120 and the contaminants 110 may be improved.

More specifically, when the contaminant 110 reacts with the cleaning solution 120, the hydroxide ion (OH < ^- & gt ^; ) of the quaternary ammonium aqueous solution may react with carbon between the contaminants 110 .

When the hydroxide ions of the quaternary ammonium aqueous solution and the carbon between the contaminants 110 react with each other, the carbon bonding between the contaminants 110 is removed, And the cleaning solution 120 may be infiltrated into the space. Accordingly, the coupling force between the contaminant 110 and the EUV mask is reduced, and the contaminant 110 can be removed from the EUV mask 100.

The organic solvent may improve the activity of the hydroxide ion of the quaternary ammonium aqueous solution. Accordingly, the cleaning solution 120 can easily remove the contaminants 110.

According to one embodiment, the contact angle of the cleaned EUV mask 100 and the contaminant 110 may include greater than 9 degrees and less than 23 degrees.

The cleaned EUV mask 100 may be rinsed (S130). According to one embodiment, the cleaned EUV mask 100 may be rinsed in an overflow fashion using DI water.

The rinsed EUV mask 100 may be dried (S140). According to one embodiment, the EUV mask 100 that has been rinsed can be dried by providing nitrogen (N ₂ ) gas.

Unlike the above-described embodiment of the present invention, in the case of a conventionally used sulfuric acid peroxide mixture (SPM) cleaning solution in the process of removing the contaminants 110 generated in the EUV lithography process, the surface of the EUV mask 100 The absorber layer can be etched. In addition, in the case of a conventionally used ozonated water cleaning solution (for example, a solution in which ozone gas is dissolved in DI water) and a UV cleaning process, the ruthenium (Ru) protective film on the surface of the EUV mask 100 is etched, Can be oxidized. Accordingly, the surface of the EUV mask 100 may be damaged.

However, the EUV mask cleaning solution according to an embodiment of the present invention may include a quaternary ammonium basic aqueous solution and an organic solvent having a concentration of more than 60 wt% and less than 80 wt%. The cleaning solution (120) The contaminants 110 formed on the EUV mask 100 used in the EUV lithography process can be easily removed. Accordingly, the lowering of the reflectivity of the surface of the EUV mask 100 is prevented, and the damage of the surface of the EUV mask 100 can be minimized.

As a result, in the process of cleaning the EUV mask 100 used in the EUV lithography process, when the cleaning solution 120 is used, the EUV mask 100 can be easily reused.

Hereinafter, the EUV mask cleaning method according to the embodiment of the present invention described above, and specific experimental production examples and characteristics evaluation results of the cleaning solution will be described.

3 is a graph showing the cleaning effect of the quaternary ammonium basic solution and the DMSO organic solvent in the EUV mask cleaning method according to the embodiment of the present invention with respect to concentration and time.

Referring to FIG. 3, cleaning solutions containing different concentrations of TBAH and DMSO organic solvents are prepared. When the TBAH concentration is 0.1 M and the DMSO concentration is 70 wt%, the TBAH concentration is 0.2 M and the DMSO concentration is 65 wt%, the TBAH concentration is 0.3 M and the DMSO concentration Was 60 wt%, the EUV mask with contaminants formed thereon was washed with each of the cleaning solutions at a temperature of 80 DEG C for 10 minutes, 15 minutes, and 20 minutes, and then the contact angle of the contaminants with the EUV mask , degree) were measured.

As can be seen from FIG. 3, it was confirmed that the cleaning efficiency was improved as the concentration of TBAH increased. In addition, it was confirmed that the cleaning progressed more efficiently as the cleaning time increased. However, in the case of the cleaning solution containing 0.1 M concentration of TBAH and 70 wt% of DMSO, it was confirmed that cleaning does not progress efficiently even if the cleaning time is increased.

4 is a photograph of the cleaning effect of the EUV cleaning solution according to the concentration of the quaternary ammonium basic aqueous solution and the organic solvent according to the embodiment of the present invention.

4 (a) to 4 (c), cleaning solutions containing different concentrations of TBAH and DMSO organic solvents are prepared. When the TBAH concentration is 0.1 M and the DMSO concentration is 70 wt%, the TBAH concentration is 0.2 M and the DMSO concentration is 65 wt%, the TBAH concentration is 0.3 M and the DMSO concentration Was 60 wt%, the EUV mask on which contaminants had been formed was washed for 20 minutes, and then a photograph was taken and the contact angle (degree) of the contaminants and the EUV mask was measured.

As can be seen from FIGS. 4 (a) to 4 (c), it was confirmed that the cleaning efficiency was increased as the TBAH concentration was increased. However, as can be seen from FIGS. 5 (b) and 5 (c), it was confirmed that the concentration of DMSO for efficient washing varies with the change of the TBAH concentration.

FIG. 5 is a graph showing the efficiency according to the concentrations of the quaternary ammonium basic aqueous solution and the organic solvent included in the EUV mask cleaning solution according to the embodiment of the present invention.

Referring to FIG. 5, a cleaning solution containing different concentrations of TBAH and DMSO is prepared. A cleaning solution containing 0.1 M TBAH and 70 wt% DMSO, a cleaning solution containing 0.2 M TBAH and 65 wt% DMSO, and a solution of TBAH at 0.3 M and DMSO at 60 wt% And the contact angle of the contaminants with the EUV mask was measured after cleaning at a temperature of 80 캜.

As can be seen from FIG. 5, it was confirmed that the cleaning efficiency was improved as the concentration of TBAH increased. It is also understood that the ultrasonic treatment of the cleaning solution effectively reduces the EUV mask cleaning time. In addition, when the EUV mask cleaning process was performed after the ultrasonic treatment of the cleaning solution containing TBAH at a concentration of 0.3M and DMSO at a concentration of 60 wt%, it was confirmed that the cleaning effect was effective even in a short time.

FIG. 6 is a photograph showing the cleaning effect of the quaternary ammonium basic aqueous solution and the DMSO organic solvent in the EUV mask cleaning method according to the embodiment of the present invention, according to concentration and time.

6 (a) to 6 (f), cleaning solutions containing different concentrations of TBAH and DMSO organic solvents are prepared. When the TBAH concentration is 0.1 M and the DMSO concentration is 70 wt%, the TBAH concentration is 0.2 M and the DMSO concentration is 65 wt%, the TBAH concentration is 0.3 M and the DMSO concentration Each of the cleaning solutions was subjected to a megasonic treatment, and the EUV mask on which contaminants were formed was cleaned at a temperature of 80 캜 for 5 minutes and 10 minutes, And the contact angle (degree) of the EUV mask were measured.

6 (c) to 6 (f), when the cleaning solution having a TBAH concentration of 0.3 M and a DMSO concentration of 60 wt% was subjected to ultrasonic treatment and washed for 5 minutes, When the cleaning solution having a TBAH concentration of 0.1 M and a DMSO concentration of 70 wt% is subjected to ultrasonic treatment and cleaning for 10 minutes, the concentration of TBAH is 0.2 M and the concentration of DMSO is 65 wt% When the cleaning solution was subjected to ultrasonic treatment and cleaning for 10 minutes, and the cleaning solution having the TBAH concentration of 0.3M and the DMSO concentration of 60 wt% was ultrasonicated and cleaned for 10 minutes , 17 °, 17 °, 15 °, and 10 °, respectively.

Accordingly, it can be seen that the EUV mask cleaning method effectively reduces the EUV mask cleaning time by ultrasonic treatment of the cleaning solution.

Further, when the cleaning solution is subjected to ultrasonic treatment and cleaning for 10 minutes, the difference in cleaning power depending on the TBAH concentration is smaller than that in the case where the cleaning solution is cleaned for 10 minutes without ultrasonic treatment Able to know. In other words. It can be understood that when the cleaning solution is subjected to ultrasonic treatment and cleaning for 10 minutes or more, the difference in cleaning power depending on the difference in concentration of the TBAH can be overcome.

As a result, when the cleaning solution is subjected to ultrasonic treatment and cleaning for 10 minutes or more, the amount of TBAH used in the EUV mask cleaning process can be reduced.

Additional experimental data for determining the effective concentration of the cleaning solution in the EUV mask cleaning process are summarized in Tables 1 and 2 below.

Cleaning solution ratio (wt%)
(TBAH: DMSO: DI water) Cleaning time (min) Cleaning result 0: 100: 0 20 Remove X 2: 28: 70 20 Remove X 5: 30: 65 20 Remove X 8: 32: 60 20 Remove O

Cleaning solution ratio (wt%)
(TBAH: DMSO: DI water)
+ Megasonic Cleaning time (min) Cleaning result 2: 28: 70 10 Remove X 5: 30: 65 10 Remove O 8: 32: 60 10 Remove O

As can be seen from Tables 1 and 2, it can be seen that the EUV mask cleaning method is efficient in cleaning with a cleaning solution containing TBAH at a concentration exceeding 2 wt%.

It is also understood that, in order to improve the cleaning efficiency while minimizing the use of TBAH, the TBAH concentration exceeds 2 wt%, and it is efficient to clean the cleaning solution by megasonic treatment.

FIG. 7 is a photograph showing the characteristics of the EUV mask cleaning solution according to the concentration of the organic solvent included in the cleaning solution according to the embodiment of the present invention.

7 (a) and 7 (b), cleaning solutions containing TBAH of the same concentration and different concentrations of DMSO organic solvent are prepared. When the concentration of TBAH was 0.3M, the concentration of DMSO was 60wt%, the concentration of TBAH was 0.3M, and the concentration of DMSO was 70wt%, the EUV mask cleaning solution was photographed.

7 (a), it was confirmed that the EUV mask cleaning solution was transparent when the concentration of TBAH was 0.3M and the concentration of DMSO was 60wt%. As can be seen from FIG. 5 (b), when the concentration of TBAH was 0.3 M and the concentration of DMSO was 70 wt%, it was confirmed that the EUV mask cleaning solution became turbid. The turbid EUV mask cleaning solution indicates that the TBAH and the DMSO are not efficiently dissolved in the DI water, and when the EUV mask cleaning is performed using them, contaminants may not be easily removed.

Accordingly, it can be understood that the concentration of DMSO should be controlled to 60 wt% or less when the concentration of TBAH is 0.3M in the EUV mask cleaning solution.

FIG. 8 is a graph comparing FTIR of precipitates precipitated in an EUV mask cleaning solution and FTIR of an organic solvent according to an embodiment of the present invention.

8 (a) and 8 (b), an EUV mask cleaning solution having a concentration of TBAH of 0.3 M and a concentration of DMSO of 70 wt% was prepared, and the precipitate precipitated in the EUV mask cleaning solution and the DMSO FTIR (Fourier transform infrared spectroscopy) was analyzed.

As can be seen from FIGS. 8A and 8B, the FTIR peak of the precipitate and the FTIR peak of the DMSO substantially agree with each other. Accordingly, when the concentration of the TBAH is 0.3 M, the EUV mask cleaning solution is found to precipitate in the cleaning solution and become turbid when the concentration of the DMSO exceeds 60 wt% . In the EUV mask cleaning method, it is necessary to control the concentration of the organic solvent according to the concentration of the quaternary ammonium basic aqueous solution.

Further experimental data for examining the concentration of TBAH and DMSO contained in the cleaning solution in the EUV mask cleaning process are summarized in Table 3 below.

TBAH concentration (M) DMSO concentration (wt.%) 50 55 60 65 70 75 80 0.1 O O O O O X X 0.2 O O O O X X X 0.3 O O O X X X X 0.4 O O X X X X X 0.5 O X X X X X X

(O: transparent, X: cloudy)

As shown in Table 3, when the concentration of TBAH is 0.1M, it is necessary to control the DMSO concentration to 70%. When the TBAH concentration is 0.2M, it is necessary to control the DMSO concentration to 65% M concentration, it is necessary to control the DMSO concentration to 60%. When the TBAH concentration is 0.4 M, it is necessary to control the DMSO concentration to 55%. When the TBAH concentration is 0.1 M, the DMSO concentration is controlled to 50% Is needed.

When the DMSO concentration according to the TBAH concentration is lower than the control concentration described above with reference to Table 3, the washing power of the washing solution is lowered and the washing efficiency is decreased. In addition, when the DMSO concentration according to the TBAH concentration is higher than the control concentration described above with reference to Table 3, the dissolution of TBAH and DMSO in the DI water is not efficiently performed, and the cleaning efficiency is decreased.

FIG. 9 is a photograph showing the effect of a cleaning solution to determine the concentration of an organic solvent in accordance with the concentration of a quaternary ammonium basic aqueous solution of an EUV cleaning solution according to an embodiment of the present invention.

Referring to Figures 9 (a) to 9 (c), cleaning solutions containing TBAH of the same concentration and different concentrations of DMSO organic solvent are prepared. When the TBAH concentration is 0.3M and the DMSO concentration is 50 wt%, the TBAH concentration is 0.3M and the DMSO concentration is 60 wt%, the TBAH concentration is 0.3M and the DMSO concentration Was 70 wt%, the EUV mask on which contaminants were formed was cleaned for 20 minutes, and then the photographs were taken and the contact angle (degree) of the contaminants and the EUV mask was measured.

9 (a) to 9 (c), when the concentration of TBAH is 0.3 M and the concentration of DMSO is 50 wt%, the contact angle is less than 32 °, the concentration of TBAH is 0.3 M, When the concentration of DMSO was 60 wt%, the contact angle was less than 10 DEG. When the concentration of TBAH was 0.3M and the concentration of DMSO was 70 wt%, the contact angle was less than 55 DEG. Accordingly, it can be seen that the EUV mask cleaning solution according to the present embodiment is effective in cleaning the EUV mask when the concentration of DMSO is 60 wt% when the concentration of TBAH is 0.3M.

10 is a graph showing the cleaning effect according to the kind of the quaternary ammonium basic aqueous solution of the EUV mask cleaning solution according to the embodiment of the present invention.

Referring to FIG. 10, cleaning solutions containing different kinds of quaternary ammonium basic aqueous solution and THF organic solvent are prepared. For the cleaning solution containing 0.1 M concentration of TMAH, 0.1 M concentration of TEAH, 0.1 M concentration of TPAH, and 0.1 M concentration of TBAH, when the THF organic solvent is contained in an amount of 0 to 80 wt% At a temperature of 50 DEG C for 10 minutes, and the contact angle of the contaminants with the EUV mask was measured.

As can be seen from FIG. 10, it was confirmed that when the substrate was cleaned with the EUV mask cleaning solution containing 0.1 M of TBAH and 70 wt% of THF, the contact angle was less than 10 °. In addition, 0.1 M TMAH does not dissolve when the concentration of THF exceeds 20 wt% and TEAH concentration of 0.1 M does not dissolve when the THF concentration exceeds 20 wt% And it was confirmed that it did not dissolve at more than 40 wt%. It was also confirmed that the use of TBAH as the quaternary ammonium basic aqueous solution was the most efficient for the EUV mask cleaning solution.

FIGS. 11 and 12 are photographs illustrating the cleaning effect according to the concentration of the organic solvent included in the EUV cleaning solution according to the embodiment of the present invention.

Referring to Figures 11 (a) to 11 (c), a cleaning solution containing TBAH and THF of the same concentration is prepared. When a cleaning solution containing 0.1 M TBAH and 70 wt% THF was cleaned for 5 minutes, a cleaning solution containing 0.1 M TBAH and 70 wt% THF was added for 10 minutes In the case of cleaning, a cleaning solution containing TBAH at a concentration of 0.1 M and THF at a concentration of 70 wt% was cleaned for 15 minutes, and the contact angle of the contaminants with the EUV mask was measured.

As can be seen from FIGS. 11 (a) to 11 (c), it was confirmed that the cleaning solution was efficiently cleaned as the cleaning time increased. In addition, it was confirmed that, in the case of the cleaning solution containing TBAH at a concentration of 0.1 M and THF at a concentration of 70 wt%, it was efficient to perform cleaning for a time of 10 minutes or more.

Referring to Figures 12 (a) to 12 (d), a cleaning solution containing TBAH of the same concentration and different concentrations of THF is prepared. A cleaning solution containing TBAH at a concentration of 0.1 M and THF at a concentration of 40 wt%, a cleaning solution containing TBAH at a concentration of 0.1 M and THF at a concentration of 60 wt%, TBAH at a concentration of 0.1 M and THF at a concentration of 70 wt% And a cleaning solution containing TBAH at a concentration of 0.1 M and THF at a concentration of 80 wt% were respectively taken for 10 minutes, and contact angles of the contaminants and the EUV mask were measured.

As can be seen in Figures 12 (a) to 12 (d), a cleaning solution containing TBAH at a concentration of 0.1 M and THF at a concentration of 40 wt%, a cleaning solution containing a 0.1 M TBAH and a 60 wt% , A cleaning solution containing TBAH at a concentration of 0.1 M and a THF at a concentration of 70 wt% and a cleaning solution containing TBAH at a concentration of 0.1 M and THF at a concentration of 80 wt% °, and a contact angle of less than 53 °. Accordingly, it can be seen that the EUV mask cleaning method is efficient in using an EUV mask cleaning solution containing an organic solvent having a concentration of more than 60 wt% and less than 80 wt%.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the scope of the present invention is not limited to the disclosed exemplary embodiments. It will also be appreciated that many modifications and variations will be apparent to those skilled in the art without departing from the scope of the present invention.

100: EUV mask
110: Contaminant
120: cleaning solution
130: Experimental group
140: Heat treatment apparatus
150: megasonic device

Claims (8)

In the process of cleaning an EUV mask used in an EUV lithography process,
Preparing a cleaning solution containing a quaternary ammonium basic aqueous solution and an organic solvent;
Providing the cleaning solution to the EUV mask to clean the EUV mask;
Rinsing the cleaned EUV mask; And
And drying the rinsed EUV mask.
The method according to claim 1,
Wherein the concentration of the organic solvent is more than 60 wt% to less than 80 wt%.
The method according to claim 1,
Wherein the concentration of the organic solvent varies depending on the concentration of the quaternary ammonium basic aqueous solution.
The method according to claim 1,
Wherein the step of cleaning the EUV mask comprises the step of megasonicizing the cleaning solution.
The method according to claim 1,
In the EUV lithography process, contaminants containing hydrocarbons are generated on the EUV mask,
Wherein the contaminant is removed by the cleaning solution.
In a cleaning solution for cleaning an EUV mask used in an EUV lithography process,
Quaternary ammonium basic aqueous solution; And
An EUV mask cleaning solution comprising an organic solvent in a concentration of greater than 60 wt% to less than 80 wt%.
The method according to claim 6,
Wherein the quaternary ammonium basic aqueous solution comprises at least one of tetramethylammonium hydroxide (TMAH), tetraethylammonium hydroxide (TEAH), tetrapropylammonium hydroxide (TPAH), and tetrabutylammonium hydroxide (TBAH).
The method according to claim 6,
Wherein the organic solvent comprises at least one of DMSO (dimethyl sulfoxide) and THF (tetrahydrofuran).

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