KR100845744B1 - Fabrication method for superhydrophobic surface and superhydrophobic surface body fabricated therefrom - Google Patents

Abstract

A fabricating method of a super-hydrophobic surface and a super-hydrophobic surface body fabricated therefrom are provided to enhance super-hydrophobic characteristics of a final surface by forming a double protrusion structure. A mask pattern(20) is formed on a wafer(10). A plurality of first protrusions(11) and a plurality of second protrusions(12) formed between the first protrusions are simultaneously formed by etching the wafer exposed by the mask pattern. A hydrophobic thin film is formed on the first protrusions and the second protrusions. The process for forming the first and second protrusions is performed by a plasma etch process using CF4 gas. The process for forming the first and second protrusions is performed under conditions of etch pressure of 2Pa-5pa and RF power of 100W-300W.

Description

Manufacturing method of superhydrophobic surface and superhydrophobic surface body manufactured by this, {FABRICATION METHOD FOR SUPERHYDROPHOBIC SURFACE AND SUPERHYDROPHOBIC SURFACE BODY FABRICATED THEREFROM}

The present invention relates to a method for producing a superhydrophobic surface and to a superhydrophobic surface prepared by the method. More specifically, the wettability of a solid surface is not only low, but also the contact angle of a fluid such as pure water. The present invention relates to a method for artificially manufacturing a superhydrophobic surface having a large contact angle and a small contact angle hysteresis, and a superhydrophobic surface body produced thereby.

In general, the wettability of the solid surface depends on the chemical properties of the surface, but it is known that the wettability is significantly reduced by making a fine projection pattern on the surface of the solid. For example, a surface with fine projections on a surface compared to a flat surface subjected to the same chemical treatment has a contact angle with pure water (the angle between the fluid and the solid when the liquid is thermodynamically equilibrated on the solid surface). In Fig. 170, the hydrophobic property appears. Thus, the wettability of the solid surface is significantly lowered.

Two models are known for the theory of contact angles of pure water with droplets on surfaces with fine projections, that is, surfaces with roughness. Wenzel [R.N. Wenzel, Ind. Eng. Chem. 28 (1936) 988] assumed a model where the area under water droplets is completely wet. The surface roughness increases the contact area between the solid and the water droplet (fluid), resulting in a larger apparent contact angle. As another theory, Baxter [A.B.D. Cassie, S. Baxter, S. Trans, Faraday Soc. 40 (1944) 546] hypothesized that air is trapped between this rough surface and water droplets, and the contact angle is increased because the water droplets are on the air.

However, even if the contact angle is large, if the contact angle hysteresis of the solid surface is large, a large amount of energy is required when flowing a fluid such as water onto the solid surface. Accordingly, solid surfaces with large contact angle histories have limitations that cannot be widely applied to the application of hydrophobic surfaces.

Here, the contact angle history is an arithmetic difference between the advancing angle, which is the contact angle in the moving direction, and the receding wetting angle, which is the opposite direction, and indicates a difference between the ideal state and the non-ideal state. Most of this theory of contact history is based on thermodynamic models, Lafuma and Que're '[A. Lafuma, D. Qoere, Nat. Mater. 2 (2003) 457 reported that the contact angle history is larger on the surface of the composite projection due to the pinning effect of the fluid. See also McHale [G. McHale, N.J. Sjirtcliffe, M.I. Newton, Langmuir 20 (2004) 10146 et al. Suggested that composite projection surfaces are slippery and wet surfaces are relatively sticky.

As such, large contact angle histories are a significant constraint on the application of hydrophobic surfaces, including the flow of fluid. That is, in such applications of hydrophobic surfaces, fluid such as water flows through the surface of the solid, so the contact angle hysteresis together with the static contact angle is an important factor for the application of the hydrophobic surface.

In order to expand the application range of hydrophobic surfaces, efforts have been made to make superhydrophobic surfaces with a small contact angle history, such as the surface of lotus' leaf in nature, by overcoming limitations of contact angle as well as contact angle history. By using the surface of the solid having such superhydrophobic properties, the fluid does not form on the superhydrophobic surface, it is possible to automatically clean the surface. In addition, the microfluidic device has high utility, such as being used as a channel inner wall surface having a low resistance to the flow of fluids and drops.

It is therefore an object of the present invention to provide a method for producing a superhydrophobic surface having a large contact angle and a small contact angle hysteresis.

Another object of the present invention is to provide a superhydrophobic surface body having a large contact angle and a small contact angle hysteresis produced by such a manufacturing method.

The object is, in accordance with the present invention, forming a mask pattern on a wafer; Etching the wafer exposed by the mask pattern to simultaneously form a first protrusion and a second protrusion between the first protrusion; And forming a hydrophobic thin film on the first and second protrusions.

The forming of the first and second protrusions may be performed by plasma etching using CF ₄ gas.

The forming of the first and second protrusions may include etching pressure of 2Pa to 5Pa and r.f. of 100W to 300W. It is preferably carried out under the condition of a power supply.

The forming of the mask pattern may include depositing a metal thin film on the wafer through sputtering; The method may include converting the metal thin film into a mask pattern formed of a plurality of metal dots through annealing.

And, the deposition of the metal thin film is r.f. The power is maintained at 150W to 300W and the pressure in the vacuum chamber at 2Pa to 5Pa is performed by DC magnetron sputtering, and the annealing is performed at a temperature of 500 ° C to 600 ° C using rapid heat treatment (RTP) equipment. In 10 minutes to 20 minutes.

In addition, the metal dot may have a diameter of 100nm to 500nm.

Here, the hydrophobic thin film may include a silicon and oxygen-containing amorphous carbon (a-C: H: Si: O) thin film formed through the PACVD method.

The forming of the hydrophobic thin film may be performed at a pressure of 2 Pa to 10 Pa using a mixed gas containing hexamethyldisiloxane and argon (Ar) having a fraction of argon gas of 10% to 30%. Can be.

Here, the superhydrophobic surface preferably has a contact angle of 160 degrees or more and a contact angle history of 5 degrees or less.

Another object of the invention is, according to the present invention, a plurality of first projections formed on a wafer; A plurality of second protrusions formed in an area between the first protrusions and smaller than the first protrusions; And a hydrophobic thin film formed to cover the first and second projections.

In addition, a metal dot is further formed on the first protrusion, and the metal dot may have a diameter of 100 nm to 500 nm.

In addition, the second protrusion may have a diameter of 10 nm to 200 nm.

The hydrophobic thin film may be a silicon and oxygen-containing amorphous carbon (a-C: H: Si: O) thin film having a thickness of 10 nm to 1000 nm.

The surface of the superhydrophobic surface body preferably has a contact angle of 160 degrees or more and a contact angle history of 5 degrees or less.

Hereinafter, a method of manufacturing a superhydrophobic surface and a superhydrophobic surface body produced thereby will be described as a means for solving the problems of the present invention with reference to the drawings.

The present invention forms a first projection and a second projection of different sizes having a nanometer (nm) size on the surface of a wafer made of silicon (Si), by forming a hydrophobic thin film on the first projection and the second projection The present invention relates to a technique for forming a superhydrophobic surface having a contact angle history of more than 160 degrees and a contact angle history of 5 degrees or less, and a superhydrophobic surface body manufactured thereby.

Specifically, as shown in FIGS. 1A and 1B, a mask pattern 20 having a predetermined shape is formed on the surface of the wafer 10.

The mask pattern 20 is formed by forming a mask layer 25 (see FIG. 1A) on the surface of the wafer 10 to have a predetermined thickness, and then patterning the formed mask layer 25 to have a predetermined pattern. Here, the mask layer 25 may be made of a metal such as Cu, Al, and in this case, the mask layer 25 is formed by a sputtering method. In this case, the mask layer 25 is a metal thin film. In addition, the mask layer 25 made of metal may be patterned through an annealing process, or may be patterned into a desired pattern through a photolithography method. By patterning, the mask layer 25, which is a metal thin film, is converted into a mask pattern 20 composed of a plurality of metal dots 21. The plurality of metal dots 21 are physically separated from each other.

Subsequently, as shown in FIG. 1C, the wafer 10 between the metal dots 21 is etched using the mask pattern 20 as a mask. Accordingly, the wafer 10 covered by the mask pattern 20 is not etched, and only the wafer 10 exposed to the mask pattern 20 is removed to form the first protrusion 11. At the same time, the second protrusion 12 having a smaller size than the first protrusion 11 is formed in the region between the first protrusions 11. That is, the first protrusion 11 and the second protrusion 12 are simultaneously formed by one etching process. The secondary etching used herein is plasma etching using only CF ₄ as a gas, unlike the above-described primary etching. Numerous protrusions of nano size are formed on the surface of the wafer 10 etched by plasma etching using only CF ₄ as a gas. These nano-sized protrusions constitute the second protrusion 12. In summary, the region of the wafer 10 which is not etched by the metal dot 21 is formed of the first protrusion 11, and at the same time, only CF ₄ is used as a gas on the surface of the etched wafer between the first protrusions 11. Due to the characteristics of plasma etching, numerous second protrusions 12 having a nano size are formed.

Thereafter, as shown in FIG. 1D, the hydrophobic thin film 30 is formed to cover the first protrusion 11 and the second protrusion 12. The hydrophobic thin film 30 may be a silicon and oxygen-containing amorphous carbon (a-C: H: Si: O) thin film formed through a plasma assisted chemical vapor deposition (PACVD) method. In another embodiment, the hydrophobic thin film may include Teflon, hydrocarbons, and the like. The fraction of argon (Ar) gas in the gas used in the PACVD method may be 10% to 30%. If the fraction of argon (Ar) gas is too low, silicon oxide particles may be generated in the PACVD process, and the generated plasma becomes unstable. If the fraction of argon (Ar) gas is too high, the hydrophobic thin film cannot be formed or the performance of the produced hydrophobic thin film is poor and the coating time becomes too long. In order to solve this problem and achieve the object of the present invention, it is preferable to maintain the fraction of argon (Ar) gas at about 10% to 30%.

By such a process, an object (superhydrophobic surface body) having a superhydrophobic surface is completed. The superhydrophobic surface thus produced has a contact angle of 160 degrees or more and a contact angle history of 5 degrees or less. The reason why the superhydrophobic surface thus produced shows characteristics of large contact angle and small contact angle history is as follows.

First, this is because the double protrusion structure is formed as compared with the prior art. Although a clear theory on the principle that the contact angle of the surface is increased by the formation of the double protrusion and the contact angle history is not elucidated, it is predicted as follows. That is, the fluid on the surface has a convex surface downward between the first protrusions 11 due to the high contact angle while being in contact with the first protrusions 11, and thus receives a force to be pulled upwards. Therefore, even if such a surface meets the second projection 12 formed on the surface between the first projections 11, the wettability with the second projection 12 will be significantly reduced. Therefore, it is thought that the phenomenon that the wettability on the surface is significantly reduced as a whole occurs. This will be described in detail in the paragraphs comparing and comparing the embodiments of the present invention with the comparative examples.

In addition, by further forming a hydrophobic thin film in the above-mentioned double protrusion structure, it is possible to further increase the hydrophobicity of the final surface to produce a surface having superhydrophobic characteristics.

As described above, according to the present invention, a method for producing a superhydrophobic surface having a large contact angle and a small contact angle hysteresis is provided.

In addition, superhydrophobic surfaces are provided which have a large contact angle and low contact angle hysteresis.

The surface body manufactured as described above has a self-cleaning function, and according to the manufacturing method described above, a surface structure having super hydrophobic properties in which lotus leaves or salt flies are visible as in nature can be artificially manufactured.

Hereinafter, specific comparative examples and examples for carrying out the present invention will be described in detail with reference to the accompanying drawings.

Comparative Example 1

In Comparative Example 1, a simple protrusion is formed on the surface of the wafer 10. That is, the surface of the wafer 10 is treated by plasma etching using a mixed gas of CF ₄ and O ₂ . At this time, the pressure in the chamber was maintained at 2 Pa. FIG. 2A is a picture of the surface of the wafer 10 shown in this case. As shown in FIG. 2A, when the surface of the wafer 10 is treated using a mixed gas of CF ₄ and O _2, an overall smooth surface is formed. However, increasing the pressure in the chamber to 5 Pa results in a rough undulation, as shown in FIG. 3A. It can be seen in Figure 3a that the rough protrusion structure is composed of fine protrusions.

Comparative Example 2

In Comparative Example 2, a simple protrusion was formed on the surface of the wafer 10, but only CF ₄ gas was used during plasma etching. When plasma etching is performed on the surface of the wafer 10 while the pressure in the chamber is maintained at 2 Pa, as shown in FIG. 2B, many projections of nano size are formed. This protrusion has a larger size than that of Comparative Example 1. When the pressure in the chamber is kept at 5 Pa, as shown in Fig. 3A, larger sized protrusions are formed on the surface of the wafer 10. When the pressure in the chamber was 5 Pa, the height of the highest protrusion was about 90.1 ± 11 nm and its diameter was about 71.5 ± 10 nm.

It can be seen from the Comparative Example 1 and Comparative Example 2 that the height and diameter of the protrusion formed as the etching pressure in the chamber gradually decreases. Using this principle, the operator can roughly produce protrusions of the desired size.

<Example of the present invention>

First, the method of forming the mask pattern 20 is demonstrated concretely.

First, the silicon wafer 10 having the 110 plane is placed at the cathode in a vacuum chamber (not shown), the pressure in the chamber is maintained at 2Pa to 5Pa, and r.f. The power was maintained at 150W to 300W. By sputtering a copper target using a DC magnetron sputtering method, the thickness of the metal thin film made of copper is deposited on the wafer 10 to be 3 nm to 5 nm. The metal thin film thus formed is the mask layer 25 of Fig. 1A. Subsequently, when annealing is performed at a temperature of about 550 ° C. for about 15 minutes using a rapid thermal annealing process (RTP) equipment, the mask layer 25 of the metal thin film is formed of a plurality of metal dots 21. The mask pattern 20 is completely converted (see FIG. 1B). Meanwhile, in the embodiment of the present invention, the annealing was performed at a temperature of 550 ° C. for about 15 minutes, but the temperature at the time of annealing may have a range of 500 ° C. to 600 ° C., and the annealing time may also be 10 minutes to 20 minutes. It may be in the range of minutes. In other words, the temperature and time during the annealing process can be appropriately adjusted according to the change of the environment during the annealing process and / or to adjust the size of the metal dot 25 to be formed.

The average height of the metal dot 21 thus prepared was about 352.0 ± 53.2nm and the average diameter was about 360.5 ± 63.1nm. That is, in order to achieve the object of the present invention, the metal dot 21 is appropriately formed so that the average diameter is in the range of 100nm to 500nm. This is because the size and distribution of the first protrusions 11 to be formed in a later process are determined by the size and distribution of the metal dot 21, so that the surface to be formed in consideration of the distribution and size with the second protrusions 12 is determined. It is controlled to have superhydrophobicity. That is, it is manufactured in consideration of the distribution density of the first protrusion 11 and the second protrusion 12 to have a superhydrophobic characteristic. However, such numerical limitation may vary according to changes in process conditions and the like, and is not limited only to the numerical range described above.

Next, the method of forming the 1st protrusion 11 and the 2nd protrusion 12 is demonstrated.

First, the surface of the wafer 10 between the metal dots 21 is etched through plasma etching using rf PACVD. The plasma etching used herein uses only CF _{4 as a} gas, the etching pressure is 2Pa to 5Pa, and the rf power is 100W to 300W. This is similar to the manufacturing process of Comparative Example 2 described above. In the surface treatment using CF ₄ gas, the metal dot 21 etches only the portion of the wafer 10 which is not covered by the metal dot 21 by significantly lowering the etching rate in the vicinity of the metal dot 21. As a result, the first protrusion 11 is formed. At the same time, the area between the first protrusions 11 etched due to the characteristics of plasma etching using only CF _{4 as a} gas is surface treated, and as shown in FIG. 4A, the area between the first protrusions 11 is about 100 nm or less. A plurality of second protrusions 12 having a diameter are formed.

Meanwhile, although the first protrusion 11 manufactured in FIG. 4A is provided to have a relatively sparsely distributed distribution (the distribution of the first protrusion 11 depends on the distribution of the metal dot 21), the first protrusion 11 is shown in FIG. 4B. As described above, the density of the first protrusions 11 may be increased by adjusting the distribution of the metal dot 21. However, if the distribution density of the first protrusion 11 is too high, it is close to a normal flat surface, and the hydrophobic characteristics of the first protrusion 11 and the second protrusion 12 are lowered. In addition, even when the distribution density of the first protrusion 11 is too low, the effect of the double protrusion structure is lowered and the hydrophobic property is lowered. Therefore, the distribution density of the first projection 11 and the distribution density of the second projection should be adjusted appropriately so as not to be too low or high.

As a result, a double protrusion structure such as a natural lotus leaf structure is artificially manufactured.

Finally, a method of forming the hydrophobic thin film 30 on the wafer 10 on which the first and second protrusions 11 and 12 are formed will be described.

The hydrophobic thin film 30 is formed through a PACVD method and may be a silicon and oxygen-containing amorphous carbon (a-C: H: Si: O) thin film. This hydrophobic thin film 30 is 13.56Mhz r.f. It is deposited using plasma decomposition of mixed gas of HMDSO (hexamethyldisiloxane) and argon (Ar) gas. The fraction of argon gas in the precursor gas was maintained at 28.6%, and r.f. The power was fixed at 30W. The thickness of the hydrophobic thin film 30 was uniformly deposited to about 10 nm, and the pressure used was 5 Pa. The surface characteristics of the hydrophobic thin film 30 thus produced are r.f. It depends on the fraction of argon (Ar) in the power source and the precursor gas. Therefore, r.f. Argon (Ar) fraction in the power source and precursor gas can be properly adjusted to deposit thin films with improved hydrophobicity. Specific conditions for this can be found in M. Grischke, A. Hieke, F. Morgenweck, H. Dimigen, Diam. Relat. Mater. 7 (1998).

Meanwhile, although the fraction of argon gas used in the embodiment of the present invention is 28.6%, the fraction of argon gas may be changed in order to change process conditions and obtain desired surface characteristics of the hydrophobic thin film. The fraction of argon gas is preferably maintained at 10% to 30%. If the fraction of argon (Ar) gas is too low, silicon oxide particles may be generated in the PACVD process, and the generated plasma may become unstable. If the fraction of argon (Ar) gas is too high, the hydrophobic thin film cannot be formed or the performance of the produced hydrophobic thin film is poor and the coating time becomes too long. In addition, although the pressure in the chamber is maintained at 5 Pa in the above-described embodiment, it can be adjusted in the range of 2Pa to 10Pa.

Thereby, the object (superhydrophobic surface body) which has the superhydrophobic surface in which the hydrophobic thin film was formed on the double protrusion structure is completed.

The superhydrophobic surface body thus produced includes a plurality of first protrusions 11 formed on the wafer, as shown in FIG. 1D; A plurality of second protrusions 12 formed between the first protrusions 11 and smaller in size than the first protrusions 11; The metal dot 21 formed on the first protrusion 11 and the hydrophobic thin film 30 formed to cover the first protrusion 11 and the second protrusion 12 are included.

As described in the above-described manufacturing method, the metal dot 21 has a diameter of 100 nm to 500 nm, and the second protrusion 12 has a diameter of 10 nm to 200 nm. The hydrophobic thin film 30 is a silicon and oxygen-containing amorphous carbon (a-C: H: Si: O) thin film having a thickness of 10 nm to 1000 nm.

The surface of the superhydrophobic surface body of this structure has a contact angle of 160 degrees or more and a contact angle history of 5 degrees or less.

Hereinafter, a method of measuring the hydrophobic property of the superhydrophobic surface body thus prepared and its results will be described in detail.

The contact angle was measured using a Goniometer (Data Physics instrument Gmbh, OCA 20L). The instrument makes it possible to measure the optical image and contact angle of sessile droplets on the surface. The static contact angle was measured by gently landing 5 ml droplets on the surface and automatically changing the amount of water from the syringe to measure the dynamic contact angle to measure the contact angle history. I was. The advancing angle was measured by gradually increasing the water volume from 0.053 ml / sec to 2-5 ml, and the receding angle was measured in the process of removing water from the droplet at the same rate.

FIG. 5A is an enlarged view of the wafer 10 when the hydrophobic thin film (aC: H: Si: O thin film) is coated on the structure of Comparative Example 1, and FIG. 5B is on the surface of the wafer 10 to measure the contact angle. Picture of the shape of the water droplets 40 in Esau. The wafer 10 surface was etched with a mixed gas of O ₂ and CF ₄ at a pressure of ₂ Pa to form a wafer surface having a nano size mono roughness. First, a hydrophobic thin film (aC: H: Si: O thin film) was coated on the smooth wafer surface, and the contact angle of the water droplet 40 was measured. The contact angle was measured at 101.8 degrees, which can be used as a value representing the chemical properties of the surface of the hydrophobic thin film (aC: H: Si: O thin film). The hysteresis of the contact angle was measured at 12.6 degrees on the smooth coating layer.

FIG. 6A is an enlarged view of the wafer 10 when the hydrophobic thin film (aC: H: Si: O thin film) is coated on the structure of Comparative Example 2, and FIG. 6B is on the surface of the wafer 10 to measure the contact angle. The picture taken the shape of the droplet 40. The wafer surface of FIG. 6A is completed by depositing a hydrophobic thin film (aC: H: Si: O thin film) on the surface of a nano-sized simple protrusion structure made by plasma etching using CF ₄ gas. And the contact angle of the water droplet 40 located on the wafer 10 thus produced was measured. The measured contact angle is approximately 137.8 degrees, which can be expected to be influenced by nanoscale projections. Here, the Cassie and Baxter and Wenzel angles of the projection surface structure are 145.4 degrees and 112.7 degrees, respectively. Considering the two calculated contact angles, 137.8 degrees, the contact angle of water droplets on nanoscale projections, does not belong to either angle. Here, the contact angle history shows 36.7 degrees.

FIG. 7A is an enlarged view of a wafer 10 having a surface having the structure as shown in FIG. 1C, and FIG. 7B is a photograph of the shape of the water droplet 40 on the surface of the wafer 10 in order to measure a contact angle. As shown in Figs. 7A and 7B, the contact angle shows no particular difference in the distribution of the metal dots 21 (see Fig. 1C). That is, the contact angle of the water droplets on the metal dots 21 (see FIG. 1C) arranged sparsely is 137.5 degrees, showing little difference. However, the contact angle history is approximately 61.4 degrees, which is a significant difference.

The results that can be known through the above three experimental examples (see FIGS. 5A to 7B) are as follows. It can be seen that the contact angle is always measured large on a fine pattern with nanoscale projections or roughness rather than on a smooth plane. This sticky behavior accounts for the following facts. In other words. Wetability exhibits sticky behavior on the wafer 10 when the spacing between nanoscale protrusions is on the nano meter scale.

8A and 8B show optical images for measuring contact angle and history of contact angle in the case of the structure as in the embodiment of the present invention. Specifically, FIG. 8A is an enlarged view of the wafer 10 of the surface having the structure as shown in FIG. 1E, and FIG. 8B is a photograph of the shape of the droplet 40 on the surface of the wafer 10 to measure the contact angle. It is a photograph. The contact angle measured at the surface of the wafer 10 having this structure is 161 degrees. However, it can be seen that the contact angle history is measured to be 4.3 degrees smaller than in any case shown in FIGS. 5A to 7B. This is because it is a surface having both slippery surface properties on the superhydrophobic surface. In particular, the distribution of nano-sized protrusions 11 and 12 is also important, but the role of the metal dot 21 (FIG. 1E) having a scale of several tens of nanometers makes the superhydrophobic property. In general, wet surfaces have sticky properties, while surfaces with dual roughness are easily slippery. This structure thus enables self-cleaning of the solid surface to the fluid.

9 is a view for explaining the wetting behavior (or wettability) of the water droplets 40 on the double protrusion structure. As shown in FIG. 9, the shape of the water droplets 40 on the surface coated with the hydrophobic thin film 30 on the surface having the double protrusion structure is locally wetted by the metal dot 21 and the first protrusions 11. The second projections 12 made by CF ₄ between the projections 11 show a shape that is not wet. Therefore, the force of the interface of the water droplets 40 is directed to the center of the water droplets 40, thereby suppressing the water droplets 40 from completely contacting the bottom, thereby making the superhydrophobic characteristic under static or dynamic contact of the water droplets. Will be maintained.

If the spacing between the metal dots 21 is far enough, the water droplets come into contact with the second projections 12, similar to the shape of the water droplets on the surface with the mono roughness of FIGS. 6A and 6B. The contact angle is also expected to be the same. On the other hand, if the spacing between the metal dots 21 becomes relatively too close, the droplet 40 will have a contact angle formed on the metal dot 21.

Therefore, in order to make a surface having a super hydrophobic characteristic from the double protrusion structure, it is important to properly maintain the distribution between the characteristics of the first protrusion 11 and the metal dot 21 and the second protrusion 12 having a smaller size. Do.

The present invention is not limited to the fabrication of a wafer surface having a double protrusion structure using a mask pattern 20 composed of CF ₄ plasma and a metal dot 21, and a double protrusion structure on a wafer surface using another plasma source. You can create a pattern.

1A to 1D are cross-sectional views for sequentially explaining a method of manufacturing a surface of a double protrusion structure according to the present invention;

FIG. 2A is an enlarged image of a wafer surface manufactured under a condition of maintaining pressure at 2 Pa in Comparative Example 1; FIG.

FIG. 2B is an enlarged image of the wafer surface manufactured under the condition of maintaining the pressure at 2 Pa in Comparative Example 2. FIG.

3A is an enlarged image of a wafer surface manufactured under a condition of maintaining pressure at 5 Pa in Comparative Example 1;

3B is an enlarged image of a wafer surface manufactured under a condition of maintaining pressure at 5 Pa in Comparative Example 2;

Figure 4a is a photograph of the surface of the wafer fabricated to have the structure of Figure 1c,

FIG. 4B is a photograph of the surface of the wafer on which the first and second protrusions are manufactured so as to have a relatively higher density than that of FIG. 4A.

5a and 5b are optical images taken to measure the contact angle and the contact angle history of water droplets on the surface prepared by further coating a hydrophobic thin film in Comparative Example 1,

6a and 6b show optical images taken to measure the contact angle and the contact angle history of water droplets on the surface prepared by further coating a hydrophobic thin film in Comparative Example 2,

7A and 7B show optical images taken to measure the contact angle and the contact angle history of water droplets on a surface manufactured to have the structure shown in FIG. 1C.

8A and 8B illustrate optical images taken to measure contact angles and contact angle histories of water droplets on a surface manufactured to have a double protrusion structure as in the embodiment of the present invention.

9 is a view for explaining the wetting behavior (or wettability) of the water droplets 40 on the double protrusion structure.

* Explanation of symbols for the main parts of the drawings

10: wafer 11: first projection

12: second projection 20: mask pattern

21 metal dot 25 mask layer

30: hydrophobic thin film 40: water drop

Claims (14)

Forming a mask pattern on the wafer; Etching the wafer exposed by the mask pattern to simultaneously form a first protrusion and a second protrusion between the first protrusion; And And forming a hydrophobic thin film on the first protrusion and the second protrusion. The method of claim 1, Forming the first projections and the second projections is a method of producing a super hydrophobic surface, characterized in that through the plasma etching using CF ₄ gas. The method of claim 2, The forming of the first protrusion and the second protrusion may include etching pressure of 2Pa to 5Pa and r.f. of 100W to 300W. Method for producing a super hydrophobic surface, characterized in that carried out under the conditions of the power source. The method of claim 1, Forming the mask pattern, Depositing a metal thin film on the wafer by sputtering; And converting the metal thin film into the mask pattern made of a plurality of metal dots through annealing. The method of claim 4, wherein The deposition of the metal thin film is r.f. It is performed by DC magnetron sputtering method while maintaining the power of 150W to 300W and the pressure in the vacuum chamber at 2Pa to 5Pa. The annealing is a method of manufacturing a super hydrophobic surface, characterized in that performed for 10 to 20 minutes at a temperature of 500 ℃ to 600 ℃ using a rapid heat treatment (RTP) equipment. The method of claim 4, wherein The metal dot is a method of producing a super hydrophobic surface, characterized in that having a diameter of 100nm to 500nm. The method of claim 1, The hydrophobic thin film comprises a silicon and oxygen-containing amorphous carbon (a-C: H: Si: O) thin film formed through the PACVD method of producing a super hydrophobic surface. The method of claim 7, wherein The forming of the hydrophobic thin film is performed using a mixed gas containing hexamethyldisiloxane (hexamethyldisiloxane) and argon (Ar) having a fraction of argon gas of 10% to 30%, at a pressure of 2Pa to 10Pa. A method for producing a superhydrophobic surface, characterized in that. The method of claim 1, The superhydrophobic surface is a method of producing a super hydrophobic surface, characterized in that the contact angle is 160 degrees or more, the contact angle history is 5 degrees or less. A plurality of first protrusions formed on the wafer; A plurality of second protrusions formed in an area between the first protrusions and smaller in size than the first protrusions; And A superhydrophobic surface body comprising a hydrophobic thin film formed to cover the first projection and the second projection. The method of claim 10, A metal dot is further formed on the first protrusion, The metal dot is a super hydrophobic surface, characterized in that having a diameter of 100nm to 500nm. The method of claim 10, The second projection is a super hydrophobic surface, characterized in that having a diameter of 10nm to 200nm. The method of claim 10, The hydrophobic thin film is a super hydrophobic surface, characterized in that the silicon and oxygen-containing amorphous carbon (a-C: H: Si: O) thin film having a thickness of 10nm to 1000nm. The method of claim 10, The superhydrophobic surface of the superhydrophobic surface is characterized in that the contact angle is 160 degrees or more, the contact angle history is 5 degrees or less.

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