KR100921932B1 - Patterning method using polyatomic molecule - Google Patents

Abstract

The present invention relates to a patterning method using polyatomic molecules, and according to the present invention, EUV is used to induce a change (nitridation, oxidation, etc.) of a polyatomic membrane by EUV using soft ultraviolet or soft X-rays. And by forming a pattern on the surface of the silicon substrate is disclosed a technique that can form a pattern with high precision at a fine level by using a functional group, such as -NH ₂ , -OH.

Lithography, EUV, Patterning, Adsorption, NH₃H₂O, Multiatomic Molecules

Description

Patterning method using polyatomic molecules {PATTERNING METHOD USING POLYATOMIC MOLECULE}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a patterning method using polyatomic molecules, and more particularly, to form a pattern by Extreme Ultra Violet (EUV) or Soft X-ray, which is a wavelength. It's about technology.

As predicted by Moore's law [D. Normile, Science 2100, 293, 787.], The feature size of semiconductor devices reached the level of 90 nm nodes in 2004, and current research focuses on reaching the 32 nm level. It is aligned. Unfortunately, standard Ultra Violet lithography cannot be used at such fine scales. So several next generation lithography techniques have been proposed.

The combination of scanning probe lithography and self-assembly has proven that a combination of top-down and bottom-up technologies can be effective. And photolithography, which uses short wavelengths of light such as extreme ultraviolet or soft x-rays, is considered to lead the next generation of lithography. The combined approach, combined with bottom-up assembly and Extreme Ultra Violet lithography (EUVL), can be used for industrial production, including the development of molecular devices such as microelectronic devices and biochips.

Polymers have been used as photosensitizers in ultraviolet lithography and the like. However, thinner photoresist layers are required to continuously reduce the size of the pattern through extreme ultraviolet lithography. For example, studies on adsorbing a self-assembled monolayer (SAM) thinner than a polymer on a solid surface and using it as a photosensitive material are being conducted.

On the other hand, a molecular film composed of small molecules formed on the surface of silicon as compared to polymers or SAMs creates nanolayers of only a few atomic layers. Because these systems are structurally simple and well-ordered, surface science studies have been conducted in recent decades to characterize these materials. As a result, the system is well known for its properties, and its simple structure makes it easy to observe changes on the surface, making it an excellent model system for studying surface changes at the atomic scale induced by extreme ultraviolet rays.

This patterned surface can be applied to next generation fabrication processes based on chemical reactivity differences.

On the other hand, very few studies have been carried out on the patterning of nano-sized molecular layers adsorbed on simple and well-defined silicon surfaces using extreme ultraviolet rays (EUV). Patterning results using extreme ultraviolet rays have not been reported.

In addition, through years of research in surface science, we have found that the adsorption of ammonia (NH ₃ ) or water (H ₂ O) on silicon (100) 2 × 1 surfaces is uniform and well-structured. It is known that the amine group and the hydroxyl group can be formed separately, but the extreme ultraviolet-induced surface modifications such as NH ₃ / Si and H ₂ O / Si The system, of course, has not been reported so far, even in well-ordered molecular systems such as self-assembled molecular layers (SAMs) terminated with amines, hydroxyl groups (-OH).

If photoreaction by short-ultraviolet ultraviolet light can be applied to resistless lithography, it will affect the next generation device fabrication process.

Accordingly, an object of the present invention is a patterning method using polyatomic molecules, in particular ammonia (NH ₃ ) or water (H ₂ O) molecules, by ultra-ultraviolet or soft x-rays with very short wavelengths, in the extension of the previous studies described above. In providing.

Patterning method using a polyatomic molecule according to an aspect of the present invention for achieving the above object A step of adsorbing a polyatomic molecule on the surface of a solid to form a molecular layer; And forming a pattern by selectively irradiating a part of the surface of the molecular layer formed in step A with extreme ultra violet (EUV) or soft x-ray (Soft X-ray). Characterized in that it comprises a.

Here, step C for forming a molecular pattern by adsorbing functional molecules to the pattern formed in step B; It is characterized by another comprising a further.

In one embodiment, the step B is performed by irradiating extreme ultraviolet or soft X-rays while the silicon substrate on which the molecular layer is formed in the step A is placed in a chamber of ultra high vacuum (UHV). do.

Further, the step B is another feature that forms a pattern by irradiating extreme ultraviolet light or soft X-rays while the gold mesh (Gold Mesh) is located on the upper surface of the molecular layer.

Further, in step B, the step B is characterized by forming a pattern by irradiating focused extreme ultraviolet (EUV: Extreme Ultra Violet) or soft x-rays.

Here, the polyatomic molecule is another feature that the molecule is ammonia (NH ₃ ) or water (H ₂ O) molecules.

Furthermore, another feature is that an oxide film and a nitride film can be formed at room temperature by EUV.

According to the present invention has the following effects.

First, a nano-molecular film of clean, molecularly aligned multiatomic molecules (especially ammonia (NH ₃ ) or water (H ₂ O) molecules) is formed on the surface of the silicon substrate. Because of the use, there is an effect that enables fine and fine surface patterning having a required pattern size.

Second, since the use of a photoresist having a concept as in the prior art, a baking process and an etching process in a photo process are unnecessary, the patterning procedure is simplified and has an environmentally friendly advantage.

Third, because it can be patterned into a functional molecule that is specifically required, it can be widely used in the fields of electronics, biotechnology, chemistry, energy and the like.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

Polyatomic Molecules (NH ₃  Or H ₂ O)  Used Patterning method

< Experimental Example >

The embodiment is made in Ultra High Vacuum (UHV). The base pressure is 2.0 × 10 ^-10 Torr, and the background gas such as H ₂ O, H ₂ , CO ₂ , and CO is kept below 5 × 10 ^-11 Torr. The residual gas analyzer You can check it. The chamber pressure was about 9 × 10 ⁻¹⁰ Torr during irradiation with gold through the Au mesh, and the chamber pressure was about 5 × 10 ⁻⁹ Torr during focused beam irradiation.

1A-1H are schematic diagrams of amine group patterning on Si (100) surfaces.

First, a Si (100) sample is placed in a vacuum chamber with a base pressure of 2 × 10 ⁻¹⁰ Torr. The sample is heated to 1250 degrees Celsius by passing a direct current. The temperature is then maintained for a few seconds to remove organic impurities and SiO ₂ layers. This process is repeated in a 2 x 10 ^-9 Torr vacuum chamber to prevent carbon and oxygen contamination by residual gases in the chamber.

After this heat treatment, a clean Si surface is obtained. It is then exposed to ammonia gas to form an amine layer at room temperature. That is, ammonia gas is introduced into the chamber.

 As shown in FIG. 1A, at room temperature, the ammonia molecules 101 dissociate into amines (NH 2) and hydrogen (H). The dissociated species then easily bond to the reactive dangling bond on a clean Si (100) surface 100.

As a result, an amine-terminated thin layer 102 is formed on the clean Si 100 surface 100 as shown in FIG. Clean, amine-finished surfaces can be identified by synchrotron radiation photoemission spectroscopy (PES).

On the other hand, in the case of using water molecules, a small amount of water vapor is introduced into the chamber to adsorb the H ₂ O. At room temperature, water molecules dissociate into hydroxy groups (OH) and hydrogen (H). The dissociated species then readily associate with the highly reactive dangling bonds on a clean Si surface. As a result, a sample with a hydroxyl group adsorbed can be produced.

Surface cleanliness and surface finished with amines can be verified using surface core level shifts. In the case of using water molecules, the cleanliness of the surface and the surface finished with hydroxy group can be verified using surface core level shift.

 Distinctive features of Si (100) surface 100 are reactive dangling bonds and asymmetric dimers 120. Here, the dimer 120 comprises a lower two-dimers 122 and an upper two-dimers 121. Since the transfer of charge is made from the down-dimers 122 down to the up-dimers 121 above, the up-dimers 121 above Filled with balance electrons, their Si 2p core levels (parts labeled S) exhibit lower binding energy (a binding energy of about 500 meV) than the bulk peak (parts labeled B).

The asymmetric bimolecular body 120 becomes symmetrical by combining dangling bonds with dissociated species. Accordingly, as shown in FIG. 1H, the asymmetric bimolecular body 120 becomes symmetrical by combining hydrogen with an amine (hydroxy group in the case of water molecules).

In addition, due to the large difference in electronegativity between silicon and nitrogen, the Si 2P peak of the silicon bimolecular body combined with nitrogen (denoted by N1) appears to be cleanly separated from the bulk peak, and Si-NH ₂ is widely formed (formed) over the entire surface. In the case of hydroxy groups, Si-OH is formed widely throughout the surface due to the large difference in electronegativity between silicon and oxygen.

Then, the inside of the chamber is restored to the base vacuum, and extreme ultraviolet (EUV) or soft x-rays are irradiated onto the amine nanolayer.

Two research methods can be used here.

One is to form an arbitrary pattern using a projection printing method of irradiating light 106 through a gold mesh 105 as shown in FIG. 1C and a focused beam as shown in FIG. 1D. There is a way to write directly.

The two irradiation methods can be appropriately selected and used according to the pattern to be formed.

The amine-finished molecular layer 102 chemically turns into silicon nitride over the region 107 exposed to extreme ultraviolet light.

In the case of using water molecules, the molecular layer finished with a hydroxyl group is chemically converted into silicon oxide on the exposed region.

As shown in FIGS. 1E-1F, the difference in chemical nature between the exposed and unexposed regions 107 creates a chemical pattern on the surface.

As shown in FIG. 1C, the amine-terminated nanolayer has a wavelength of 11.8 nm through a gold mesh 105 for 1 hour (photon flux: 2 × 10 ^14). (photons / sec.cm ² )) Exposed to extreme ultraviolet light.

2A and 2B show core-level SPEM images of Si 2p, N 1s, and O 1s for a pattern formed on the surface of a nanolayer finished with an amine.

As shown in FIG. 2A, a mesh pattern 207 is formed on the surface, which can be confirmed through scanning photoemission microscopy (SPEM) images of core levels of Si 2P, N 1s, and O 1s. μ-photoemission Spectroscopy (μ-PES) can be used to interpret chemical differences between the region 107 and the region 102 that are not irradiated with extreme ultraviolet light.

The molecular layer 102 finished with an amine or the molecular layer finished with a hydroxyl group is chemically converted to silicon nitride or silicon oxide on the exposed region. Can be formed. This is a good method for forming a nitride film and an oxide film in that a nitride film and an oxide film can be formed at room temperature in view of the conventional method of forming an oxide film or a nitride film at a high temperature by a chemical vapor deposition (CVD) method.

Fresnel zone plates can be used to focus and pattern the beam. [R. Klauser, I.-H. Hong, S.-C. Wang, M. Zharnikov, A. Paul, A. Glzhuser, A. Terfort, TJ Chuang, J. Phys. Chem. B 2003, 107, 13 133.] [R. Klauser, M.-L. Huang, S.-C. Wang, C.-H. Chen, TJ Chuang, A. Terfort, M. Zharnikov, Langmuir 2004, 20, 2050.]. At this time, by focusing the extreme ultraviolet beam, photons per unit area are also increased. For reference, the light, which was 2 × 10 ⁶ (photons / sec.μm ² ) per second in an area of 1μm diameter before focusing, increases to 5 × 10 ⁹ (photons / sec.μm ² ) per second, in an area of 1μm after focusing.

2B is a view showing a pattern formed using focused extreme ultraviolet rays. The desired pattern 208 can be written directly onto the substrate through fine control of the sample stage.

Scanning Photoemission Microscopy (SPEM) images of the core levels of Si 2p, N 1s, and O 1s clearly show the letters 208 written on the molecular nanolayer.

μ-photoemission spectroscopy (μ-PES) can be used to interpret chemical differences between the areas irradiated with extreme ultraviolet light.

A 0.7 eV N 1s core level shift can be seen, and the stepped area of the N 1s image reflects that the silicon nitride is formed in the exposed area.

으로 주어진다. 여기서 k₁과 k₂는 공정에 의존하는 변수이며, λ는 파장이고, NA는 광학장치의 개구수(numerical aperture)이다. On the other hand, the resolution (R) and depth of focus (DOF) for projection lithography

Given by Where k ₁ and k ₂ are process dependent variables, λ is the wavelength and NA is the numerical aperture of the optics.

From the above equation for the resolution R, the shorter the wavelength of the light used, the finer pattern can be formed on the surface, whereas the depth of focus (DOF) also becomes shorter as the wavelength becomes shorter. Therefore, in order to use extreme ultraviolet light having a short wavelength for patterning, the photoresist must also be thin in consideration of the short depth of focus. In the extreme ultraviolet region, the depth of focus ranges from a few nanometers to several tens of nanometers, so a polymer having a thickness of several hundred nanometers is not a suitable registry material for extreme ultraviolet patterning. The above system has atomic thicknesses such as NH ₂ , —OH, H and the like. Therefore, the short depth of focus caused by the shortening of the wavelength in this system is no longer a problem.

Recently, studies on extreme ultraviolet lithography have developed optical devices, masks, and light sources optimized for extreme ultraviolet rays having a wavelength of 13.4 nm, and many experiments have been carried out in this region. Since the system presented in this study is light-changed irrespective of the wavelength, it is possible to use the extreme ultraviolet rays of 13.4 nm wavelength and the optical devices and masks used in the light in this region.

Every time a new source with a different wavelength is developed. Conventional photolithography requires the development of new types of resist materials. In contrast, the molecular nanolayers in this study can be applied without any additional change because the surface change is independent of the wavelength of the incident light.

The functionality and thickness of the pattern can also be controlled according to the chemical, physical and structural properties of the adsorbed molecules.

In the case of NH ₃ / Si and H ₂ O / Si systems, it is possible to adsorb molecules which readily bind to amines and hydroxyl functional groups formed on the surface. At this time, the length of the adsorbed molecules can be controlled by various chemical synthesis methods, so that the thickness of the pattern can be controlled. In addition, the functionality of the pattern is determined by the functional group of the adsorbed molecule.

 Various related technologies are currently being developed to form nanopatterns using extreme ultraviolet rays. For example, extreme ultraviolet interference lithography is used to form regular nanopatterns such as wires and dots. Meanwhile, the nanostructure having an arbitrary shape may be made using a finely focused beam. Recently, extreme ultraviolet rays were focused to 15 nm size using zoneplate lens developed by Chao et al. If using this micro-focusing technology, nano-sized patterns with arbitrary shapes can be produced. will be.

In summary, nano-layers of extreme ultraviolet (or soft x-rays) and hydroxy groups (-OH) or amine groups (NH ₂ ) can be applied to form surface patterns of various functional groups.

According to the above experimental fact, it can be seen that the formation of the resistless pattern can be performed through sequential steps as referred to in the flowchart of FIG. 3.

< Patterning method >

 1. Molecular layer formation <S301>

The molecular layer is formed by adsorbing ammonia or water molecules on the surface of the silicon substrate.

2. Pattern formation by light irradiation <S302>

A portion of the surface of the molecular layer formed in step S301 is selectively irradiated with extreme ultraviolet rays (or soft x-rays located next to the extreme ultraviolet region) to form a pattern. At this time, the irradiation of the focused extreme ultraviolet rays can be made by placing a Fresnel zone plate.

3. Pattern formation by functional molecules <S303>

If the pattern formation by the functional molecule which is specifically required is necessary, the pattern by the functional molecule is formed by adsorbing the functional molecule on the pattern formed by irradiating the extreme ultraviolet rays focused in step S302. Of course, step S302 and step S303 can be performed almost simultaneously.

In the above experimental example, ammonia or water molecules are dissociated and adsorbed on the surface of silicon, but for example, a pattern may be formed by adsorbing ammonia or water molecules on the surface of a solid such as Ge (germanium). .

As described above, the detailed description of the present invention has been made by the embodiments with reference to the accompanying drawings. However, since the above-described embodiments have only been described with reference to preferred examples of the present invention, the present invention is limited to the above embodiments. It is not to be understood that the scope of the present invention should be understood by the claims and equivalent concepts described below.

1A-1H are schematic diagrams of amine group patterning on a Si (100) surface.

2A and 2B show core-level SPEM images of Si 2p, N 1s, and O 1s for a pattern formed on the surface of a nanolayer finished with an amine.

3 is a flowchart illustrating a patterning method using polyatomic molecules.

<Description of Reference Symbols for Main Parts of Drawings>

102 layer finished with amine 105 gold mesh

107 exposed region 120 dimer

Claims (6)

A step of adsorbing a polyatomic molecule-a molecule composed of heterogeneous atoms on the surface of the solid-to form a molecular layer; And A portion of the surface of the molecular layer formed in step A is selectively irradiated with extreme ultraviolet rays (EUV: Extreme Ultra violet) or soft X-rays having a wavelength belonging to a wavelength range of 4nm ~ 50nm and combined with functional components Forming a pattern of the molecular layer including a functional group capable of reacting; Patterning method using a multi-atomic molecule, characterized in that it comprises a. The method of claim 1, C step of forming a molecular pattern by adsorbing functional molecules on the pattern of the molecular layer formed in the step B; Patterning method using a multi-atomic molecule, characterized in that it further comprises. The method of claim 1, The step B is performed by irradiating extreme ultraviolet or soft X-rays while the silicon substrate on which the molecular layer is formed in the step A is positioned in a chamber of ultra high vacuum (UHV). Patterning method used. The method of claim 1, The step B is a patterning method using polyatomic molecules, characterized in that to form a pattern by irradiating extreme ultraviolet light or soft X-rays while the gold mesh (Gold Mesh) located on the upper side of the molecular layer. The method of claim 1, The step B is a patterning method using polyatomic molecules, characterized in that to form a pattern by irradiating focused extreme ultraviolet (EUV: Extreme Ultra Violet) or soft X-rays (Soft X-ray). The method according to any one of claims 1 to 5, The polyatomic molecule is a patterning method using a multiatomic molecule, characterized in that the ammonia (NH ₃ ) or water (H ₂ O) molecules.

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