KR20110130257A - Method of forming a semiconductor device using photolithography - Google Patents

Abstract

PURPOSE: A method of forming a semiconductor device using a photolithography is provided to improve throughput by forming a much finer pattern using the same mask without an additional mask and reducing a setting time. CONSTITUTION: In a method of forming a semiconductor device using a photolithography, a reflection barrier layer and a first photoresist film are formed in the top of a substrate(S10). The first photoresist film is exposed to outside(S20). The first pattern including the first opening is formed by developing the first photoresist film(S30). The first pattern is plasma-processed(S40). A second photoresist film is formed in the first pattern(S50). The second photoresist film is exposed to outside(S60). A second pattern including the second opening is formed by developing the second photoresist film(S70).

Description

Method of forming semiconductor device using photolithography {METHOD OF FORMING A SEMICONDUCTOR DEVICE USING PHOTOLITHOGRAPHY}

The present invention relates to a method of forming a semiconductor device using photolithography, and more particularly, to a method of forming a semiconductor device including a fine pattern using photolithography. According to the present invention, it is possible to form a semiconductor device including a pattern having excellent step coverage and having fine dimensions, for example, a pattern having an opening such as a contact hole.

With the development of semiconductor devices, the development of low-current and low-power semiconductor devices is becoming more important as the demand for high-end markets increases and environmentally friendly products are required. In order to meet the demands of the industry, the development of more integrated and detailed semiconductor devices is required.

In order to develop a highly integrated semiconductor device, it is necessary to develop a pattern forming technology for forming a fine pattern. According to the resolution, which is the basic principle of the optics that control this, the smaller the wavelength of the light source, the greater the degree of separation. KrF lasers used for light sources of conventional exposure equipment have wavelengths of about 248 nm and ArF lasers have wavelengths of about 193 nm, but light sources with shorter wavelengths are required to form finer patterns. However, the development and setting of photoresist materials and photolithography (or lithography) equipment corresponding thereto should also be carried out.

In view of these problems, a technique for realizing finer patterns while using conventional equipment and materials is desired.

One object of the present invention is to provide a method capable of forming a high resolution pattern having openings such as fine contact holes using photolithography.

Another object of the present invention is to provide a method of forming a semiconductor device such as a flash or DRAM by forming a fine pattern using the pattern forming method described above.

The objects of the present invention described above are parallel and optional, and do not imply that the claims of the present application will all fulfill them.

In the method for forming a semiconductor device using photolithography according to an aspect of the present invention, an antireflection film and a first photoresist film are formed on a bottom surface thereof. The first photoresist film is exposed and then developed to form a first pattern including the first opening. After the plasma treatment of the first pattern, a second photoresist film is formed on the first pattern. The second photoresist film is exposed and developed to form a second pattern including a second opening. In this case, the second opening may have a smaller dimension than the first opening.

In an embodiment of the present invention, the bottom surface may be formed by etching the bottom surface by using the first and second patterns as an etching mask to form a bottom pattern having fine openings.

According to an exemplary embodiment of the present invention, the method may further include soft baking after forming the first and second photoresist layers, respectively. The method may further include performing hard baking after developing the first and second photoresist layers. Meanwhile, the method may further include baking each of the first and second photoresist films and then baking the first and second photoresist films.

In an embodiment of the present invention, the plasma treatment comprises one or more of hydrogen bromide (HBr), hydrogen chloride (HCl), helium (He), neon (Ne), nitrogen (N ₂ ), and / or argon (Ar). Can be performed using. In one aspect of the invention, the plasma treatment may be performed for about 1 second to about 300 seconds.

In an embodiment of the present disclosure, the opening of the bottom pattern may include a contact hole, and the contact hole may have a minimum dimension of about 30 nm or less in cross section.

According to an embodiment of the present invention, each of the first and second photoresist layers may include a positive photoresist. The first and second photoresist films may each include a negative photoresist.

In an embodiment of the present invention, each of the first and second photoresist films may be exposed to an argon fluoride (ArF) laser light source, and light sources of different wavelengths may also be used. In addition, the first and second photoresist films may be exposed using an emulsion photolithography apparatus, and a general photolithography apparatus other than such an emulsion photolithography apparatus may be used.

According to an embodiment of the present invention, the anti-reflection film may include an organic anti-reflection film, and may be not limited to the organic anti-reflection film as long as the film prevents reflection by using interference of light.

In an embodiment of the present invention, the plasma treatment and the formation of the photoresist film may be repeatedly performed at least two times to form a pattern including an opening having a smaller dimension than the opening of the bottom pattern.

The method of forming a semiconductor device according to embodiments of the present invention may be applied to fabricating various semiconductor localities including a flash device or a DRAM device.

According to the present invention, a finer pattern, for example, a finer pattern having fine openings such as contact holes can be formed without changing the configuration or design of the conventional equipment. In addition, a finer pattern may be formed while using the same mask without making a separate mask. According to the embodiment of the present invention, a finer pattern can be formed using the same photoresist as in the conventional case. Accordingly, the manufacturing process of the semiconductor device may be simplified, the process conditions may be easily set, the setting time may be reduced, and the process throughput may be improved, thereby significantly reducing the cost of manufacturing the device.

1 is a process flow chart for explaining a bottom patterning method using a photolithography method according to embodiments of the present invention.
2 to 13B are cross-sectional views and plan views illustrating a method of forming a bottom pattern using photolithography using a positive photoresist according to embodiments of the present invention.
14-25B are cross-sectional views and plan views illustrating a method of patterning a bottom surface using photolithography using a negative photoresist according to other embodiments of the present invention.
Fig. 26 is a cross-sectional view showing the reflection and refraction of the light wavelength reaching the photoresist film, the reflective ring film and the bottom surface according to the present invention.
Fig. 27 is an IR diagram of the peak of the photoresist film after plasma treatment measured by IR.
28 is a graph comparing N-value values of the photoresist film and the anti-reflection film before and after plasma treatment.
29 is a graph comparing K-value values of the photoresist film and the anti-reflection film before and after plasma treatment.
30 is a graph plotting the reflectivity of the photoresist film and the anti-reflection film before and after the plasma treatment.
31 is a graph plotting the thickness of a pattern generated after the secondary coating after the plasma treatment.
32A and 32B are micrographs showing a first photoresist pattern and a second photoresist pattern.

Definition of Terms

In the present specification, "photolithography" refers to a process of transferring a circuit diagram manufactured on a photomask or a reticle onto a wafer to form a semiconductor device, and a method of patterning a fine shape having a dimension within about 10 m micro. Collectively.

"Interference" means the phenomenon in which two or more waves meet and are counted or weakened. "Reinforcement interference" is a phenomenon in which the two waves have the same phase difference and have a larger amplitude, and occur when the path difference between the two waves is an even multiple of half wavelength. The "offset interference" is a phenomenon in which the amplitudes are smaller because the phase differences of the two waves are opposite, and occur when the path difference from the two sources is an odd multiple of half wavelength.

"Diffraction" refers to the phenomenon that the wave is transmitted to the back of the obstacle when it meets an obstacle or passes through a narrow gap in the course of the wave, and when the wave progresses and reaches the edge or the gap of the obstacle, each wave point on the wavefront of the portion is waved. This creates a new wave and proceeds.

"Resolution" refers to the distance or time between two points on an object identified by an optical machine. In general, the resolution is expressed by the following equation. Here, k1 is an intrinsic constant that depends on the photoresist, photo equipment, and the like, lambda is the wavelength of the light source, and NA is the numerical aperture of the lens.

[expression]

By "high resolution" is meant a level of resolution that can be determined and controlled to fine dimensions with a minimum dimension of about 60 nm or less.

The term "reticle" or "mask" includes a pattern to be transferred to the bottom of the semiconductor substrate or the substrate on which the process has been progressed as a blueprint that defines the shape of the two-dimensional plane. These reticles contain a number of multiple slits, causing various optical effects, such as diffraction and interference, to the propagation of light.

"Pattern" means the shape designed on the reticle or mask and means the shape intended to be transferred to the bottom by the photoresist, and "patterning" means the process of transferring the shape designed on the mask to the bottom.

"Bottom" means the object surface or film | membrane to which a pattern is to be formed. Since the pattern or the film is transferred, it includes not only a semiconductor substrate but also a substrate on which a process is performed, and a photoresist may also be a bottom surface. In addition to planes that are flat in two dimensions, curved and uneven surfaces, as well as a single layer of material, include composite surfaces. Since the pattern of the mask is transferred through the photoresist, a photoresist is applied on the bottom surface. In addition to the photoresist, it may further include a surface necessary for performing photolithography. For example, an anti-reflective film or layer may be further applied on the bottom to control unwanted exposure disturbances due to reflection on the bottom.

The term "lower surface" means a film located on a lower side of a layer, so in the present specification, the bottom surface is sometimes referred to as the lower surface.

The term "photoresist" refers to a material capable of transferring the information of a predetermined pattern to a mask on the bottom surface by changing the exposed and unexposed portions and physical properties in response to light. Photosensitive organic substances that react to light, such as photosensitive polymers and photosensitive organic polymers. Differences in physical properties include differences in solubility in chemicals for development (in the present specification, "development"). The photoresist may be classified into a positive type photoresist and a negative type photoresist according to the properties of the exposed portion. The positive type photoresist is a portion in which a portion reacted with light is removed by a developer, and the negative type photoresist is a photoresist in which a portion which is not reacted with light, that is, a non-exposed portion, is removed by a developer.

By "development" is meant a process by which a desired pattern appears through an agent or reagent.

"Plasma" refers to a state in which positively charged particles and negatively charged particles that are freely moving are generally neutral mixed with a neutral gas, and "plasma treatment" refers to an operation using energy of plasma and a substance added to the plasma.

By “opening” is meant a recessed or pierced shape in a portion of the plane, the top of which may be closed or open.

The term "modification" refers to a phenomenon in which the physical properties of the film are changed after being subjected to plasma or heat treatment, and are distinguished from the "change" in the physical properties of the photoresist made in response to light.

By "baking" or "bake" is meant a process of raising the temperature of a film, layer, or film, or of the bottom comprising the same.

"Soft baking" refers to a process of raising the temperature before exposure, and "hard baking" refers to a process of raising the temperature after development. For example, (after temperature definition, the soft baking process may vary depending on the solvent, but the temperature may be raised to about 30 to 110 ° C., and the hard baking may be heated to about 80 ° C. to 160 ° C.).

"Post-exposure bake" means a process of raising the temperature after the exposure process.

"Dimension" means a value such as the width, length, depth, etc. of the shape formed by the pattern, and "minimum dimension" means the smallest of the dimensions of the shape.

Terms other than the terms defined above are defined in the meanings commonly used in the art or in terms generally used. In other words, unless otherwise defined herein, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. have. Terms such as those defined in the commonly used dictionaries should be construed as having meanings consistent with the meanings in the context of the related art, and are not to be construed in ideal or excessively formal meanings unless expressly defined herein. Do not.

As the invention allows for various changes and numerous embodiments, various embodiments will be described in detail herein. However, these examples are not intended to limit the present invention to the specific disclosed form, it should be understood to include all modifications, equivalents, and substitutes included in the spirit and scope of the present invention. In each figure, the same or similar reference numerals represent the same or similar components. Terms such as "first" and "second" are used to distinguish and refer to components having the same or similar properties or properties. The terms "primary" and / or "secondary" are often used to indicate the progress of a process and the first or second is used to distinguish between components, but the terms refer to one component as another component. It is used only for the purpose of distinguishing from and used interchangeably with terms such as "primary" and "secondary", respectively. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. In this specification, terms such as "comprise", "include", "have", "comprise" or "include", and the like refer to features, numbers, steps, operations, components, parts, or combinations thereof described on the specification. It is to be understood that one is intended to be present and does not exclude in advance the possibility of the presence or addition of one or more other features or numbers, steps, operations, components, parts or combinations thereof.

The dimensions of the bottom, layer (film, or film) or patterns shown in the accompanying drawings may be exaggerated and magnified than actual for clarity of the invention. In the present specification, each layer (film), pattern or structures is referred to as being formed on the substrate, each layer (film) or patterns "on", "upper" or "lower". Film), pattern or structures directly formed on or below the substrate, each layer (film) or patterns, or other layers (film), other patterns or other structures may be additionally formed on the substrate.

Hereinafter, a method of forming a semiconductor device using photolithography according to embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a flowchart illustrating a method of patterning a bottom surface using photolithography according to embodiments of the present invention.

Referring to FIG. 1, after applying a first photoresist on a bottom surface on which a film (or film) is formed (step S10), the first photoresist applied on the entire surface is exposed (step S20). In the present invention, the photolithography process includes a method of passing light through a reticle (mask) and patterning the bottom through a lens. The first photoresist formed on the bottom surface may be coated with a photosensitive photoresist in which the characteristics of the light receiving portion are changed. The first photoresist transmits the shape of the pattern of the exposure mask to the bottom surface through the first photoresist. I can buy it.

The first photoresist, which is divided into an exposed part and an unexposed non-exposed part whose characteristics have been changed through the exposing step of the first photoresist, is developed (step S30), and is formed on the bottom surface by a difference in solubility or reactivity of the developer. A first pattern is formed. When a first pattern having a predetermined shape is formed from the first photoresist, an exposed bottom surface (lower layer) is partially removed through an etching process using the etching pattern, and the first pattern is transferred to the bottom surface. This bottom surface is implemented in a desired pattern shape. The anisotropic etching process is more advantageous than the isotropic etching process as the etching process, and the anisotropic etching process may include a dry etching process.

In one embodiment of the present invention, after first developing the first photoresist to form the first pattern, the second photoresist is applied on the first pattern again without etching the bottom surface immediately. (Step S50), the applied second photoresist is exposed (step S60), and then the exposed second photoresist is developed (step S70) to form a second pattern, thereby forming a conventional photolithography apparatus and photoresist. It is possible to form a finer and more precise pattern than can be realized. According to one embodiment of the present invention, after the first pattern is formed on the bottom surface, further processing is performed to denature either or both of the first pattern and the anti-reflection film, and then secondarily to the second photo. The resist can be applied, exposed and developed to form a pattern with a finer minimum dimension. Such further processing includes plasma processing (step S40). For example, the plasma treatment is a plasma treatment of hydrogen halides such as hydrogen bromide (HBr) and hydrogen chloride (HCl), or an inert gas such as argon (Ar), helium (He), neon (Ne), nitrogen (N ₂ ), and the like. Plasma treatment may be included. In the present invention, the minimum dimension may be implemented up to 50 nm or less, preferably 30 nm or less, more preferably 17 nm to 50 nm. In the present invention, the treatment time of the plasma may be changed by the processing conditions, but may be treated for about 1 second to about 300 seconds.

In the embodiments of the present invention, since the photoresist is applied on the bottom surface in the form of a solution or a fluid containing a resin that is a polymer, in one aspect of the present invention, a photoresist is formed by applying a photoresist In order to increase the density of the film quality of the film, the method may include heating the bottom surface of the photoresist on which the photoresist is formed to remove the solvent, that is, baking the photoresist.

The photoresist may be divided into a positive photoresist in which the exposed portion is changed to increase its solubility in a developer, and a negative photoresist in which the exposed portion is changed, that is, the solubility is reduced.

In the case of the positive photoresist, the photoresist of the portion exposed by development is removed to form a photoresist pattern. In the case of the negative photoresist, the photoresist of the portion unexposed by development is removed to form a photoresist pattern.

The bottom surface is etched using the first pattern and / or the second pattern (step S80) to transfer the shape of the first pattern and / or the second pattern to the bottom surface, and then a stripping process is performed. To remove some of the remaining photoresist. Accordingly, a variety of fine patterns can be formed, and various patterns, such as a pattern having a straight line shape and a pattern having a large aspect ratio, can be formed finely and precisely. For example, the opening may include a contact hole, and the contact hole may have a minute dimension of about 17 nm to about 50 nm.

Hereinafter, according to embodiments of the present invention, a method of forming a pattern having an opening such as, for example, a contact hole will be described.

2 to 13B are cross-sectional views and plan views illustrating a method of forming a pattern having a contact hole from a bottom by using a positive photoresist.

Referring to FIG. 2, after providing the bottom surface 1000, an anti-reflective film or layer 500 is formed on the bottom surface 1000. In this specification, since the bottom surface 1000 refers to a surface or a film on which a pattern is transferred, the bottom surface 1000 may include not only a semiconductor substrate but also a substrate on which a process is performed, and the photoresist itself may correspond to the bottom surface 1000. Although the top of the bottom surface 1000 is illustrated in the form of a two-dimensional flat plane in the drawing, not only the plane but also the curved and uneven surface, in addition to a single material layer may include a composite surface. Subsequently, since the pattern of the first mask 800p (see FIG. 3) is transferred through the first photoresist film 100 (see FIG. 3), the first photoresist film 100 is formed on the bottom surface 1000. do. In another embodiment of the present invention, a surface required for performing photolithography in addition to the first photoresist film 100 may be additionally formed on the bottom surface 1000 and / or the anti-reflection film 500.

In the anti-reflection film 500, an anti-reflective film or layer is placed on the bottom surface 1000 to control the disturbance of the light intensity caused by the reflection of the lower surface and the transmissive surface and the reflection at the interface. It can be applied further. The antireflection film 500 may be classified into an inorganic antireflection film including a carbon film and the like and an organic antireflection film including an organic material. When the anti-reflection film 500 is an inorganic anti-reflection film, light intensity is absorbed to weaken the reflected light reflected from the lower surface of the anti-reflection film 500 to prevent reflection. On the other hand, when the anti-reflection film 500 is an organic anti-reflection film, the reflected light is extinguished by using the principles of wave reinforcement and destructive interference to prevent reflection. In the present invention, either or both of an inorganic antireflection film and an organic antireflection film may be adopted, and the organic antireflection film may be used alone or in combination.

Referring to FIG. 3, the first photoresist film 100 is formed on the anti-reflection film 500. FIG. 26 is a cross-sectional view illustrating a path of light in cross-sections of the anti-reflection film 500 and the first photoresist film 100.

As shown in FIG. 26, the anti-reflection film 500 causes extinction interference with the light reflected from the bottom surface 1000 to attenuate or remove the reflected light from the bottom surface 1000 to prevent the pattern from being disturbed due to the reflected light from the bottom surface.

The first photoresist film 100 includes a photosensitive polymer material, and receives the light to change physical properties of the exposed part to increase or decrease the solubility or reactivity of the developer to implement a selective pattern, thereby performing dry etching. The first photoresist pattern 110 (see FIG. 5A) remaining after the development during the etching process may serve as an etching mask to pattern the bottom surface 1000.

As a light source for exposing the first photoresist film 100, all kinds of light sources used in photolithography may be used, and may include white light or monochromatic light. In this invention, the laser which is the light of monochromatic wavelength can be used. For example, light such as i-line or g-line may be used as the laser light source, but KrF (248 nm) laser light and ArF (193 nm) laser light may also be used. However, the present invention is not limited to the type of laser light source among the exposure equipment, and a laser light source for forming other single wavelength light may be used.

The exposure equipment used in the present invention may include a laser device for forming a light source, a lens for dispersing or concentrating light, and a reticle (mask) containing a shape for a desired pattern.

In order to bring the shape of the desired pattern as close as possible to the bottom surface 1000 including the first photoresist film 100, a light source having a short wavelength and a lens having a large numerical aperture may be used. In addition, since it is necessary to focus a desired image within a desired dimension, a lens having a large numerical aperture can also be used for this purpose.

General lithography and emulsion lithography equipment can be used in the present invention. The emulsion lithography can fill a liquid (eg, water having a refractive index of about 1.44) between the projection optic or lens and the bottom to increase the resolution and expand the focusing range to form a good pattern shape. It maintains the wavelength as it is, and improves the depth of focus (DOF) by reducing the angle of incident light by using water, which is a high refractive index liquid, between the lens and the wafer. If NA) is set to 1 or more, a good resolution can be used even at the same wavelength.

The resist composition included in the first photoresist film 100 has a macromolecular mole having a polymer molecular weight of several thousand to tens of thousands, and a monomer included therein is a mixture containing a resin, an organic material in which monomers are repeatedly formed. . The first photoresist film 100 may be easily formed and a polymer to which monomers having various functions are connected may be used. In other words, the photoresist composition includes a photosensitive polymer or a photosensitive molecule and a polymer mixture in which the solubility in the developer is changed by chemical reaction when exposed to light. The photoresist is supplied in the form of a composition, in a liquid form, and may further include additives such as solvents (solvents), photosensitive resins, base ions, inhibitors, surfactants, photoreactive substances, reaction promoters, reaction inhibitors, and the like. Can be.

The photosensitive resin of the photoresist composition described above is sensitive to the main wavelength of the light to be reacted and has a property of changing and reacting. In the case of the KrF laser line, the photoresist may include a moiety of a polymer having an aromatic ring such as a benzene ring. The resin used for the shorter wavelength ArF laser light may include units of acrylates or units of aliphatic rings, fused rings. The representative resin of an aromatic ring is a novolak resin, As a representative ring of an aliphatic ring, a cyclohexyl ring and an aliphatic composite ring can mention an adamantyl group, for example. In addition, examples of the aliphatic complex ring may include a complex ring formed by the Diels-Alder reaction as an example of the polymer resin used in the present invention. In addition, in addition to carbon and hydrogen, a ring containing a hetero atom such as oxygen, nitrogen, and sulfur may also be included in the resin used in the present invention. Examples of aliphatic resins include acrylates, cycloolefins, maleic anhydrides, polynorbornene, cycloolefin resins.

The protecting group that reacts to light may include an ether type and an acetal type, and a representative protecting group of the ether type may include a t-butyloxycarbonyl group.

The photoresist composition liquid used in the present invention may include a photoreactive material to accelerate and amplify the photoreaction. The photoreactive material included in the ArF laser light or the photoresist composition used for the KrF laser light may include a chemical acid amplifying agent (photo acid generator PAG). A chemical amplifying agent is a substance that generates an acid that acts as a catalyst by curing the resin when it receives light. Examples of such compounds include tripetylsulfonium triflate (TPS-Tf). In the case of positive photoresist compositions, these compounds receive light and release a stronger triple acid than sulfuric acid to deprotect the ether moieties (-O-Protect) protected with acid protecting groups to make -OH solubility in the developer. Implement to be able to form a pattern by increasing the.

Referring back to FIG. 3, after the liquid or dispersed photoresist composition is applied onto the antireflection film 500 positioned on the bottom surface 1000 to form the first photoresist film 100, the first photoresist is formed. A first mask 800p having a predetermined pattern is disposed on the film 100, and the first photoresist film 100 is exposed. In this case, the first mask 800p may be a positive mask. For example, the first photoresist film 100 may be formed on the bottom surface 1000 through a spin coating process. In other words, the photoresist solution is dispensed while rotating the substrate (eg, wafer) having the bottom surface 1000 to form a thin first photoresist film 100 on the bottom surface 1000 (or wafer). The first photoresist film 100 may be uniformly mixed with the polymer and the photosensitive material, and may be formed on the bottom surface 1000 to a thickness of several μm to several tens of nm depending on the size of the pattern to be formed. Here, the concentration of the photoresist solution may be controlled to obtain a desired thickness of the first photoresist film 100. For example, in order to form the first photoresist film 100 with a thick thickness, the photoresist solution concentration can be made thicker. After the first photoresist film 100 is formed, the temperature of the first photoresist film 100 can be prevented and the film quality of the first photoresist film 100 can be improved by increasing the temperature to remove the remaining solvent. .

4A and 4B are cross-sectional views and plan views for explaining the first photoresist film 100 after exposure, respectively.

4A and 4B, after exposure, the first photoresist film 100 is partitioned into an exposed first photosensitive portion 105 and an unexposed first pattern portion 100p. On the other hand, in order to accelerate and assure the reaction of the photoresist composition due to the exposure, the temperature can be raised during or after the exposure. This temperature raising process is called Post Exposure Baking (PEB), which diffuses chemical property changes formed through photochemical reactions with light (for g-line and i-line) and deprotected acid. It is possible to supply enough activation energy (in case of KrF laser light or ArF laser light) to make the edge of the generated pattern smoother.

In the practice of the present invention, a polymer sensitive to the light source used as the polymer used in the photoresist composition can be used. Different chemicals are needed to obtain photochemical reactions with different wavelengths of light, and as the light sources change, new photoresist systems are required. In order to obtain a fine pattern, a short wavelength light source should be used. When using a light source such as KrF (248 nm) laser light or ArF (193 nm) laser light, a chemically amplified resist is used, and a photoacid generator (PAG) having high acid generation efficiency is used as a photoreactive material. Can be used to solve weak light source problems and improve productivity. When the first photoresist film 100 is exposed, the photoacid generator decomposes to generate acid, and the generated acid deprotects the ether group or the acetal protecting group. In this decomposition process, the acid participates as a catalyst, and when one reaction is completed, new acid is generated again to participate in another reaction, so that the above-mentioned reaction occurs continuously. The polymer of the first photoresist film 100 in which the protecting group is decomposed forms a first photosensitive portion 105 having high solubility in a developer.

5A and 5B are cross-sectional views and plan views illustrating a process of developing the first photoresist film 100 to form the first pattern 110, respectively.

Referring to FIG. 5A, the lower layer of the first pattern 100 having the first opening 700, such as a contact hole exposing the lower layer by exposing the first photosensitive portion 105 with a developer, is exposed. The first photosensitive portion 105, which is a portion of the first photoresist film 100 changed due to exposure, and the first pattern portion 100p (that is, the 'non-photosensitive portion'), which is an unchanged portion, are distinguished from each other. It is possible to form a first pattern 110 by distinguishing and removing them reactively. Developers that may be used in the present invention may include a base, and may include, for example, a tetramethylammonium hydride (TMAH) solution. Optionally, the development process may be completed by raising the temperature during or after the development of the first photoresist film 100, and the developer may be removed. Here, the temperature rise temperature is difficult to limit uniformly because it depends on the process conditions, but can generally be raised to a temperature range of about 90 ℃ to about 150 ℃. If the temperature is too low, it is difficult to completely remove the solvent. If the temperature is too high, the diffusion may proceed too much to deteriorate the shape of the first pattern 110.

6 is a cross-sectional view illustrating plasma processing of the first pattern 110 and the anti-reflection film 500. After the development process described with reference to FIGS. 5A and 5B, the formed first pattern 110 and the anti-reflection film 500 are plasma treated to denature physical and chemical properties from the first pattern 110 and the anti-reflection film 500. . In embodiments of the present invention, the plasma treatment may include plasma treatment of hydrogen halides such as hydrogen bromide and hydrogen chloride or plasma treatment of an inert gas such as argon, helium, neon, or nitrogen.

7A and 7B are cross-sectional views and plan views illustrating the modified first pattern 110a and the modified antireflection film 500a, respectively, formed through plasma processing.

As shown in FIGS. 7A and 7B, the modified first photoresist pattern 110a and the modified anti-reflection film 500a are formed on the bottom surface 1000 through the above-described plasma treatment. Regarding the modification of the first pattern 110 photoresist and the anti-reflection film 500 after the plasma treatment, referring to FIG. 27, the lactone (cyclic ester) or ketone (CO) peak before the plasma treatment gradually decreases after the plasma treatment. It can be seen that the photoresist pattern and the organic antireflective film were modified by plasma treatment.

In embodiments of the present invention, the plasma treatment may be performed for about 0.1 seconds to about 1,000 seconds, preferably about 1 second to about 700 seconds, very preferably about 5 seconds to about 500 seconds, but other It may vary depending on the process conditions. As a kind of gas that can be used for such plasma treatment, any one or more of hydrogen halides such as hydrogen bromide and hydrogen chloride, and inert gases such as argon, helium, neon, and nitrogen may be employed.

As shown in FIGS. 8A and 8B, the second photoresist film 300 is formed on the entire surface of the bottom surface 1000 while filling the first opening 700. The second photoresist film 300 may be substantially the same as the first photoresist film 100, but may be different from the positive photoresist. For example, the second photoresist film 300 may be formed by applying a photoresist composition having excellent coating properties and filling properties. Alternatively, the same photoresist composition may be used as in the case of the first photoresist film 100 because it can be controlled under similar process conditions. Here, the concentration of the photoresist composition can be further diluted to ensure improved filling. In addition, the height difference may not be greater than that of the modified first pattern 110a for sufficient light transmission. For example, the thickness of the second photoresist layer 300 may be higher than that of the first modified pattern 110a by about 1 nm to about 100 nm. As in the case of the first photoresist film 100 described above, a temperature raising process may be performed on the second photoresist film 300 to remove the solvent or the solvent.

9 is a cross-sectional view illustrating an exposure process on the second photoresist film 300.

As shown in FIG. 9, after placing the second mask 810p on the second photoresist film 300, the second photoresist film 300 is exposed. According to one embodiment of the present invention, when performing the exposure process on the second photoresist film 300, a mask substantially the same as the exposure to the first photoresist film 100 can be used. That is, the second mask 810p may be the same mask as the first mask 810p. If the same mask is used without making a separate mask, it is economical because it can simplify the process and reduce the cost. In this case, when the same second mask 810p as the first mask 800p is used, the planar portion (the exposed portion (the second pattern portion 300p)) of the second photoresist film 300 exposed to the light source is The portion of the first photoresist film 100 which is the same as the planar portion in the case of the difference exposure but is changed by being exposed to light (the second photosensitive portion 305) may be different.

10A and 10B are cross-sectional views and plan views illustrating the second photosensitive portion 305 and the second pattern portion 300P of the second photoresist film 300, respectively.

10A and 10B, the cross-sectional area of the second photosensitive portion 305 of the second photoresist film 300 is narrower and finer than that of the first photosensitive portion 105 of the first photoresist film 100. Is formed. Thereafter, the second photoresist film 300 is selectively heated, and then developed to form a second pattern 3010p having a second opening 750 as illustrated in FIGS. 11A and 11B.

As shown in FIGS. 12A and 12B, the predetermined anti-reflection film 550a and the bottom surface 1000 are partially etched by using the second pattern 310 and the modified first pattern 110a as etching masks. A bottom pattern 1000p is formed that includes an opening 7570 having a dimension of. The opening 770 may be formed from the anti-reflection film pattern 500p to the bottom pattern 1000p. Here, the opening 770 of the bottom pattern 1000p has a smaller dimension than the first opening 700 of the modified first pattern 110a and is substantially similar to the second opening 750 of the second pattern 310. May have dimensions.

Referring to FIGS. 13A and 13B, an ashing process and / or a stripping process may be performed to remove the remaining second pattern 310, the modified first pattern 110a, and the anti-reflection film pattern 500p, such as a contact hole. The bottom pattern 1000p including the predetermined opening 770 can be obtained. Here, the contact hole may be formed in a fine dimension of about 17nm to about 50nm.

Through the above-described method, it is possible to form a small size pattern having a small dimension, for example, a pattern having a fine opening, by using the same mask that forms a pattern having a large conventional pattern size as a process. According to one embodiment of the present invention, after the first pattern 110 is formed by the anti-reflection film 500 and the first photoresist pattern 110 by plasma treatment of the anti-reflection film 500 and the first photoresist pattern (110) It is presumed to denature both or at least one physical property. As described with reference to FIG. 26, in the case of the organic antireflection film, the light reflected from the bottom surface 1000 through the organic antireflection film and the light reflected through the first pattern 110, which is a photoresist pattern, are extinct and interfere with each other. Reduce or eliminate the effects of reflected light. However, when the plasma process is performed, some or all of the anti-reflection film 500 and the first photoresist pattern 110 may be modified to change the absorbance and the refractive index to change the degree of interference. In addition, after the second photoresist film 300 is formed on the first pattern 110, since the second opening 750 has a smaller width than that of the first opening 700, the light having the wave property is the second. It may not be well delivered to the opening 750. Light energy sufficient for the second photoresist film 300 to change in the first opening 700 of the first pattern 110 is required, and the amount of reflected light will increase more clearly and surely.

FIG. 28 shows the change of the refractive index (N-value) of the photoresist film PR and the antireflection film ARC during the plasma treatment. Referring to FIG. 28, the refractive index of the anti-reflection film ARC is greatly changed after the plasma treatment, and thus, the refractive index is similar to that of the second photoresist film PR. It is explained that by performing such plasma treatment, the physical properties of the film can be denatured and the light intensity can be adjusted more than when the plasma treatment is not performed. That is, it is understood that the intensity of light can be controlled by performing plasma treatment on the photoresist film PR and the antireflection film ARC to change the smoothness of the surface and the interference degree of the laminated film.

29 is a graph showing K-value values before and after plasma treatment. Where K-value is a coefficient representing the absorbance of the medium. As shown in FIG. 29, both the photoresist film and the anti-reflection film had high K-value and low reflectivity before the plasma treatment, but the K-value gradually increased by performing the plasma treatment. That is, when the plasma treatment is performed on the photoresist film and the anti-reflection film, the absorbance of light increases and the degree of reflection decreases.

30 is a graph showing changes in reflectivity before and after plasma treatment. In the graph of FIG. 30, the experiment was performed by making a sample coated with a photoresist film or an anti-reflection film on the bottom thereof, and measuring the numerical value by performing plasma treatment over time. This shows that the reflectivity of the plasma treated sample is lower than the reflectivity of the non-plasma treated sample, and the generation of acid through the intensity of reflected light may be reduced. As shown in FIG. 30, the treatment with HBr plasma for about 150 seconds shows a similar result to the reflectivity before the plasma treatment. Therefore, the treatment with HBr plasma for about 150 seconds may provide excellent effects of the present invention. Judging. In this case, it is a category that can be understood by those skilled in the art that different process conditions may show different aspects.

In the above description, various methods according to various embodiments of the present invention have been described. However, these descriptions are only described as a basis for supporting the integrity of the present invention as a means for understanding the present invention, and the present invention is limited to It is not intended to be limiting.

FIG. 31 is a graph showing the thickness of the second photoresist pattern formed during the HBr plasma treatment on the second photoresist film. The following table shows the thickness of the second pattern according to the HBr plasma treatment on the second photoresist film. Is the result of measurement.

Referring to FIG. 31 and the following table, when the plasma treatment is performed for about 30 seconds having the largest change in reflectance and refractive index, the cross-sectional width CD of the second photoresist pattern 305p becomes thick and the second photoresist The portion from which the film is removed, that is, the dimension of the second photosensitive portion is narrowed, so that a second pattern having a narrow second narrow opening of the resultant opening can be formed.

[table]

32A and 32B are micrographs of a state in which a second photoresist pattern is formed after forming a first photoresist pattern in a line form, respectively. 32A and 32B, the spacing between the second photoresist patterns becomes narrower by about 3 nm to about 15 nm per side than the spacing between the first photoresist patterns when forming the first photoresist pattern. Therefore, a photoresist pattern having a finer width could be formed.

Further, as another embodiment of the present invention, the third photoresist pattern is narrower by forming a third photoresist pattern on the second photoresist pattern by further performing plasma treatment, photoresist coating, exposure and development treatment. It may have an opening having a width.

Hereinafter, a method of forming a bottom pattern having an opening using a negative photoresist will be described with reference to FIGS. 14 to 25B. Unless specifically stated below, the descriptions of the embodiment embodiments using the positive photoresist described above may similarly apply.

Referring to FIG. 14, an anti-reflection film 500 and a first photoresist film 400, which is a negative photoresist film, are sequentially formed on the bottom surface 1000. Here, the negative photoresist of the first photoresist film 400 collectively refers to a photoresist having a property that the exposed portion is cured and solidified.

Referring to FIG. 15, a first mask 800n suitable for a negative photoresist is disposed on the first photoresist film 400, and the first photoresist film 400 is exposed. Accordingly, as shown in FIGS. 16A and 16B, the exposed portion of the first photoresist film 400 is hardened to form a first pattern portion 405, which is an exposed portion, and an unexposed portion. It is fractionated with 1 non-photosensitive part 400p.

17A and 17B, when the first photoresist film 400 is developed to remove the first non-photosensitive portion 400p, the first opening 700 partially exposing the anti-reflection film 500 is defined ( Defined first pattern 410 is formed. Here, the temperature raising process may be selectively performed on the bottom surface 1000 on which the first pattern 410 is formed.

Referring to FIG. 18, plasma processing is performed on the first pattern 410 and / or the anti-reflection film 500 to denature one or both of the first pattern 410 and the anti-reflection film 500. Accordingly, as illustrated in FIGS. 19A and 19B, the modified first pattern 4105a and the modified anti-reflection film 5500a are formed on the bottom surface 1000.

As shown in FIGS. 20A and 20B, the second photoresist film 600 is formed on the modified first pattern 410a and the modified anti-reflection film 500a while filling the first opening 700. As in the case of the positive photoresist described above, in order to make the light effect remarkable, the thickness of the second photoresist film 600 is advantageously not thicker than the thickness of the modified first pattern 410a, for example, several nm. To tens of nm higher.

Referring to FIG. 21, a second mask 810n for a negative photoresist is disposed on the second photoresist film 600, and then the second photoresist film 600 is exposed to expose the second photoresist. The film 600 is partitioned into an exposed second pattern portion 605 and an unexposed second non-exposed portion 600p.

22A and 22B, the width of the second pattern portion 605 of the second photoresist film 600 is widened by the action of the modified first photoresist pattern 410a and the modified antireflection film 500a. All. Thereafter, as illustrated in FIGS. 23A and 23B, the second pattern 610 having the second opening 750 by removing the second non-photosensitive portion 4600p of the second photoresist film 600 through the developing process. To form. Here, the second opening 750 of the second pattern 610 has a smaller dimension than the first opening 700 of the first pattern 410.

Referring to FIGS. 24A and 24B, the bottom surface 1000 and the modified anti-reflection film 500a are etched using the second pattern 610 and the modified first pattern 410a as etching masks to have openings 770. A bottom pattern 1000n and an antireflection film pattern 500n are formed. In this case, the opening 770 of the bottom pattern 1000n may have a dimension substantially similar to that of the second opening 750 of the second pattern 610. For example, the opening 770 may include a contact hole, and the contact hole may be formed in a minute dimension of about 17 nm to about 50 nm.

As shown in FIGS. 25A and 25B, the bottom surface pattern having the opening 770 may be removed by removing the residual photoresist patterns 610 and 410a and the anti-reflection film pattern 500n through a stripping process and / or an ashing process. 1000n) is obtained to form a bottom.

As described above, a fine pattern having fine openings may be implemented using a positive photoresist or a negative photoresist. Here, it may be more appropriate to use a positive photoresist in view of the characteristics of the fine pattern, such as the aspect ratio of the fine pattern and the smoothness of the surface.

While various embodiments of the present invention have been described above by way of example, the present invention is not limited by these exemplary embodiments, and does not depart from the scope of the claims and equivalents thereof. As will be appreciated by those skilled in the art, modifications to the present invention and the scope of the present invention are well understood.

Physical properties data of the photoresist pattern and the anti-reflection film according to the embodiments of the present invention were obtained by the following process.

Measurement of denaturation of photoresist pattern

After plasma treatment of the photoresist pattern, the physical property was measured and measured in real time with an Infra Red Spectroscopy. The photoresist composition of the photoresist pattern was used TARF-6A-813PH from TOK, and the anti-reflective coating was used NCHA4117 manufactured by Nissan Chemical.

In FIG. 27, the x-axis shows the absorption wavelength of IR and the y-axis shows the absorbance. Referring to FIG. 27, the photoresist pattern shows ketones and peaks near 1,800 cm −1 at 1,720 cm −1, but the photoresist pattern gradually decreases when treated with HBr plasma.

28 to 30 are graphs showing change values of N-value, K-value and reflectivity of the photoresist pattern and the anti-reflection film, respectively. As described above, treatment with HBr plasma shows a sharp decrease in the N-value of the antireflection film. In addition, the reflectivity of the modified photoresist pattern and the modified anti-reflection film decreased during HBr plasma treatment, and gradually increased to show a level equivalent to that of untreated when treated for about 150 seconds.

Referring to FIG. 31, exposure of performing the HBr plasma treatment for about 30 seconds and about 60 seconds results in the formation of a second second photoresist pattern even with the same mask. However, the sample treated for about 150 seconds shows that the influence of the adjacent portions of the first photoresist pattern is insignificant, so that the second photoresist pattern is all exposed and removed during the developing process.

As described above, a fine pattern having minute openings may be formed through the method of manufacturing a semiconductor device using photolithography according to exemplary embodiments of the present invention. According to the present invention, it is possible to form a fine and precise pattern having a smaller minimum dimension than that of a general photoresist pattern. In addition, since the same mask is used, time and cost required to manufacture the mask can be reduced, and because the same photoresist is used, it is easy to set process conditions and workability can be improved.

100 and 400: first photoresist film 100p and 405: first positive pattern portion
105: first photosensitive unit 110, 410: first pattern
110a and 410a: modified first pattern 300 and 600: second photoresist film
300p and 605: second pattern portion 305: second photosensitive portion
310 and 610: second pattern 400p: first non-photosensitive part
500: antireflection film 500a: modified antireflection film
500p, 500n: Antireflection film pattern 600p: Second non-photosensitive part
700: first opening 750: second opening
770: opening 800p, 800n: first mask
810p, 810n: second mask 1000: bottom
1000p, 1000n: bottom pattern

Claims (16)

Forming an anti-reflection film and a first photoresist film on the bottom surface;
Exposing the first photoresist film;
Developing the first photoresist film to form a first pattern including a first opening;
Plasma processing the first pattern;
Forming a second photoresist film on the first pattern;
Exposing the second photoresist film; And
Developing the second photoresist film to form a second pattern including a second opening;
And the second opening has a smaller dimension than the first opening. The semiconductor device of claim 1, further comprising forming a bottom pattern having an opening by etching the bottom surface by using the first and second patterns as an etching mask. Way. The method of claim 1, further comprising soft baking each of the first and second photoresist layers after forming the first and second photoresist layers. The method of claim 1, further comprising hard baking each of the first and second photoresist layers, respectively. The method of claim 1, further comprising baking each of the first and second photoresist films and then baking each of the first and second photoresist films. The method of claim 1, wherein the plasma treatment uses at least one selected from the group consisting of hydrogen bromide (HBr), hydrogen chloride (HCl), helium (He), neon (Ne), nitrogen (N ₂ ) and argon (Ar). A method of forming a semiconductor device using photolithography, characterized in that. 13. The method of claim 12, wherein the opening of the bottom pattern comprises a contact hole. 8. The method of claim 7, wherein the contact hole has a minimum dimension of 30 nm or less in cross section. The method of claim 1, wherein the plasma treatment is performed for 1 to 300 seconds. The method of claim 1, wherein each of the first and second photoresist films comprises a positive photoresist. The method of claim 1, wherein each of the first and second photoresist films comprises a negative photoresist. 2. The method of claim 1, wherein the first and second photoresist films are exposed with argon fluoride (ArF) laser light. The method of claim 1, wherein the first and second photoresist films are exposed using an emulsion photolithography apparatus. The method of claim 1, wherein the anti-reflection film comprises an organic anti-reflection film. The method of claim 2, further comprising repeating the plasma treatment and forming the photoresist film two or more times to form a pattern including an opening having a smaller dimension than the opening of the bottom pattern. A method of forming a semiconductor device using photolithography. The method of claim 2, wherein the semiconductor device comprises a flash device or a DRAM device.

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