KR20080038986A - Method of forming a photoresist pattern - Google Patents

Abstract

A method for forming a photoresist pattern is provided to coat a subsequentially formed layer without causing defects by performing a cleaning process for converting the surface of a hard mask layer including an SOG(spin on glass) material into a hydrophilic material. A preliminary hard mask layer including carbon as an SOG material can be formed on a substrate. A hard mask layer including a SOG material is formed on the resultant structure(S100). A cleaning process for surface treatment is performed to make the surface of the hard mask layer have a hydrophilic property(S110). An ARC(anti-reflective coating) is formed on the hard mask layer(S120). A photoresist layer is formed on the ARC(S130). The photoresist layer is patterned to form a photoresist pattern(S140).

Description

Method of forming a photoresist pattern

1 is a flowchart illustrating a method of forming a photoresist pattern according to an exemplary embodiment of the present invention.

2 is a cross-sectional view showing an example of a cleaning apparatus using ultrasonic waves on a general substrate.

3 to 7 are cross-sectional views illustrating a pattern forming method using the method of forming a photoresist pattern according to Embodiment 2 of the present invention.

Explanation of symbols on the main parts of the drawings

100: substrate 102: thin film

106: spin-on-carbon film 108: spin-on-glass film

110: hard mask film 112: antireflection coating film

114: photoresist layer 120: photoresist pattern

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of forming a photoresist pattern, and more particularly, to a method of forming a photoresist pattern, which can be applied at the time of pattern formation of a semiconductor device and uses a spin masked and cleaned hard mask film.

As the patterns constituting the semiconductor devices are required to be highly integrated, the precision of processing techniques for forming ultra fine patterns by performing a photolithography process is becoming increasingly strict. That is, in order to form patterns of 100 nm or less, an ArF photoresist pattern having a relatively lower wavelength than that of a conventional photoresist pattern is applied. However, when the lower film quality is etched by applying the ArF photoresist pattern, the mask film may not function as a result of the lack of etching resistance of the ArF photoresist pattern. In order to solve this problem, a method of using an amorphous carbon film and a silicon oxynitride (SiON) film as a hard mask has been introduced.

When the plasma ashing process is performed to remove both the hard mask including the silicon oxynitride (SiON) film and the photoresist pattern formed on the hard mask, the silicon oxynitride (SiON) film is not etched and only the photoresist pattern is removed. do. Therefore, in order to remove the hard mask, a separate etching process must be further performed.

On the other hand, when the amorphous carbon film is applied as a hard mask, the amorphous carbon film has a high absorption coefficient, making it difficult to read an overlay key on the film formed at the lower side, and requires a new investment of equipment for depositing amorphous carbon. This is brought about.

Therefore, spin-on-carbon (hereinafter referred to as "SOC") and spin-on-glass (hereinafter referred to as "SOG") to replace an opaque amorphous carbon film with light having a wavelength of 700 nm or less. It was used as a hard mask film containing a material, and a photoresist having improved etching resistance by using silicon.

In the method of forming the photoresist pattern, a hard mask film including SOC and SOG is formed on a substrate, and an anti-reflective coating (ARC) for preventing diffuse reflection during exposure on the hard mask film. Forming a film, coating a photoresist on the ARC film, and then performing an alignment process by placing a mask on which the desired pattern is drawn and selectively exposing light on the photoresist. After that, a developing process is performed in which a exposed portion or an unexposed portion is dissolved by treating with a developer.

However, when the ARC film is formed on the hard mask film including the spin-on-glass material, due to a difference in the adhesion force between the hard mask film and the ARC film and the pullback force of the ARC film. Defects are generated under the ARC film. In order to determine the cause of the defect occurrence, the contact angle of the hard mask film was measured. As a result of the measurement, the hard mask film contained a group having a hydrophobic bond, and it was confirmed that the hard mask film had hydrophobicity on the surface. As a result, when the ARC film is coated on the hydrophobic hard mask film and then the baking process is performed, an ARC film adhering to each other between the hydrophobic surface and the ARC film adhered to the upper surface of the hard mask film is present. do.

Therefore, some of the ARC films formed in small ovals formed in the middle of the ARC films that push each other are formed as defects, so that a photoresist pattern including silicon is not currently applied to the manufacturing process of semiconductor devices. I'm doing it.

Accordingly, it is an object of the present invention to provide a method of forming a photoresist pattern capable of performing defect-free coating of a subsequently formed film by performing a cleaning process that hydrophilically substitutes a surface of a hard mask film including a spin-on-glass material. have.

A method of forming a photoresist pattern according to the present invention for achieving the above object, to form a hard mask film containing a spin-on-glass material on a substrate. A cleaning process is performed to surface-treat the surface of the hard mask film to have hydrophilicity. An antireflective coating film is formed on the hard mask film on which the cleaning process is performed. A photoresist layer is formed on the antireflective coating layer. The photoresist layer is patterned to form a photoresist pattern.

Prior to forming the hard mask layer, a preliminary hard mask layer including carbon as a spin-on material may be further formed on the substrate.

As an example, the cleaning process rotates the substrate, provides de-ionized water as a cleaning liquid on the substrate, and then applies ultrasonic energy to the provided cleaning liquid. Subsequently, the substrate provided with the cleaning liquid is brushed.

As another example, the cleaning process rotates the substrate, provides de-ionized water to which ultrasonic energy is applied as a cleaning liquid on the substrate, and then brushes the substrate provided with the cleaning liquid.

According to the present invention, a group bonded to the surface of the spin-on-glass material of the hard mask layer is hydrophilically by performing a cleaning process of applying ultrasonic energy to deionized water on the substrate on which the hard mask layer including the spin-on-glass material is formed. Can be converted. Therefore, the bonding force difference of the groups bonded between the spin-on-glass material and the subsequently formed antireflective coating material can be greatly reduced. Accordingly, when forming the anti-reflective coating film on the hard mask film, a difference in adhesion force and repulsive force between the combined groups of the films may be generated, thereby improving a defect problem in which a part is agglomerated.

In addition, since a defect does not occur after coating of the antireflective coating layer on the substrate, the reliability of the photoresist pattern formed on the antireflective coating layer may be improved.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, the present invention is not limited to the following examples and may be implemented in other forms. The embodiments introduced herein are provided to make the disclosure more complete and to fully convey the spirit and features of the invention to those skilled in the art. In the drawings, the thicknesses of the respective films (layers) and regions are exaggerated for clarity of the invention, and when referred to as being placed on another film (layer) or substrate, It may be formed directly on the film (layer) or substrate, or an additional film (layer) may be interposed therebetween.

1 is a flowchart illustrating a method of forming a photoresist pattern according to an exemplary embodiment of the present invention. 2 is a cross-sectional view showing an example of a cleaning apparatus using ultrasonic waves on a general substrate.

Referring to FIG. 1, first, a substrate is prepared. Examples of the substrate may be a semiconductor substrate on which a thin film is formed, and examples of the thin film may include a silicon oxide film, a nitride film, a polysilicon film, and a metal film. The thin film is preferably a thin film from which contaminants and the like remaining on the surface are removed through a surface cleaning process.

Next, a hard mask film including a spin-on-glass material is formed on the cleaned thin film (step S100). The SOG material is silicon oxide and includes silsesquioxane. The hard mask layer may be formed by spin coating the SOG material on the substrate and then curing the SOG material.

As another example of the present invention, the hard mask layer may further form a preliminary hard mask layer including carbon as a spin-on material, and a spin-on-carbon (SOC) film and spin-on-glass. (SOG) film can be formed in a stacked structure.

Subsequently, a cleaning process is performed to surface-treat the surface of the hard mask film to have hydrophilicity (step S110). The cleaning process may be performed by providing deionized water on a spin-rotated substrate and applying ultrasonic energy. Specifically, the cleaning process may be performed using the general ultrasonic cleaning equipment shown in FIG.

The ultrasonic cleaning device will be described in brief with regard to the ultrasonic cleaning device including a cleaning container 300, a chuck 110 as a substrate support member positioned in the cleaning container 300 and supporting a substrate W to be cleaned. As a vibration transmission member which oscillates the nozzle 200 as a cleaning liquid supply member to supply the cleaning liquid 140 on the surface of the substrate W to be cleaned, and the cleaning liquid 140 supplied to the surface of the substrate W mounted on the 110. The cleaning probe 150 includes a cleaning probe 150, a generator 160 as a vibration generating member that generates oscillation energy to be delivered to the cleaning probe 150, and a brush 170.

The upper side of the washing vessel 300 is open, and a nozzle 200 for supplying the washing liquid into the washing vessel 300 is disposed. The lower portion of the cleaning container 300 has a discharge port 310 for discharging the cleaning liquid to the outside.

The chuck 110 is located in the cleaning container 300, and supports the substrate W and rotates the substrate W. The chuck 110 adsorbs the substrate W in a vacuum. An upper end of the rotation shaft 120 is connected to the bottom center of the chuck 110. A motor 130 that imparts rotational force to the rotating shaft 120 is connected to the lower end of the rotating shaft 120. A support 180 is disposed at the side of the chuck 110. A brush 160 for guiding the cleaning liquid on the surface of the substrate W to the outside is installed on the support 140.

The cleaning probe 150 is disposed on the substrate W placed on the chuck 110. The cleaning probe 150 applies a powerful ultrasonic vibration to the cleaning liquid 140 supplied to the substrate W through the nozzle 200. The cavitation bubbles rupture by the powerful ultrasonic waves applied to the cleaning solution, creating gaps between the foreign matters, and the bubbles penetrate and rupture to separate the foreign matters from the surface of the substrate W. In this case, when there is a risk of damage caused by the cavitation, it is preferable to use ultrasonic waves in units of megahertz (MHz).

 As the cleaning liquid 140, deionized water may be used for the purpose of removing and rinsing foreign substances adhering on the substrate (W). The cleaning probe 150 is in contact with the cleaning liquid 140 formed on the substrate W, and has a hollow rod shape having a circular cross section extending in the horizontal direction in the radial direction of the substrate W. In addition, the cleaning probe 150 may be made of quartz that can effectively transmit ultrasonic energy. The quartz probe 150 has a length in direct contact with the cleaning liquid 140 has a length corresponding to the radius of the substrate (W).

The generator 160 is a vibrator that generates vibrations to be transmitted to the cleaning probe 150 and couples with one end of the cleaning probe 150 acoustically or possibly in another way. The generator 160 generates a high frequency signal, for example, megahertz (MHz), which is transmitted to the cleaning probe 150.

The brush 160 may include a brush 170 for removing particles and unreacted cleaning liquid from the substrate W using the cleaning liquid 140 injected from the nozzle 200 to the entire surface of the substrate W. Spaced apart from the 150 is disposed on the substrate (W).

The ultrasonic cleaning device configured as described above operates as follows.

The substrate W to be cleaned is mounted on the chuck 110. As an exemplary embodiment of the present invention, a hard mask layer including a spin on glass material is formed on the substrate W. As shown in FIG. When the substrate W is mounted on the chuck 110, the substrate 130 is rotated by operating the motor 130 to rotate the chuck 110.

The cleaning probe 150 is placed in the cleaning position to have a proper distance on the substrate W.

When the cleaning probe 150 is in the cleaning position, the cleaning liquid 140 is supplied to the surface of the substrate W through the nozzle 200. The cleaning liquid 140 may be continuously supplied during the cleaning process. As an embodiment of the present invention, the cleaning liquid 140 uses deionized water.

When the cleaning liquid 140 is supplied, the generator 160 is operated to oscillate the cleaning probe 150 at high frequency in ultrasonic waves, for example, megahertz (MHz). The oscillated cleaning probe 150 agitates the cleaning liquid 140 supplied onto the substrate W surface.

Here, the cleaning solution 140 reacts the polymers constituting the hard mask film with the deionized water to replace the group having a hydrophobic bond on the surface of the hard mask film with a hydroxyl (OH-) group to have a hydrophilic bond. Can be converted. In addition, the cleaning liquid 140 may separate the foreign matter from the surface of the substrate (W).

As another example, the cleaning solution 140 may be provided in the form of de-ionized water to which ultrasonic energy is applied.

The cleaning liquid including the foreign matter separated from the surface of the substrate W is discharged to the outside through the outlet 310 while the brush 160 is in contact with the front surface of the rotating substrate (W).

In order to check whether the surface of the hard mask film was substituted with groups having a hydrophilic bond, a process of measuring a contact angle was further performed. As a result of measuring the contact angle, the contact angle was reduced from about 77 to 58.1 by about 19 ranges after the cleaning process using the deionized water as the cleaning liquid. Accordingly, it is confirmed that the bonding force of the hard mask film on the surface is reduced and is more hydrophilic than the initial stage.

Subsequently, an antireflective coating (ARC) film is formed on the hard mask film on which the cleaning process is performed (step S120). The ARC film is applied between the hard mask film and the subsequently formed photoresist layer, and has a very thin thickness compared to the photoresist layer, for example, is formed to a thickness of about 400 to 600 kPa. Specific components of the ARC membrane may be EUV44 (Nissan Caical), SNAC90 (Nissan Caical) and the like. The basic resin of the ARC component is polyacrylate, in which anthracene (antracene) is partially substituted with a substituent and crosses as an additive. A cross-linker is included. The application of these components onto a hard mask film and heating results in the formation of a crosslinked polymer with a crosslinking agent, resulting in a compound that is insoluble in most solvents.

The ARC film can reduce the refractive index of the light exposed during the subsequent photolithography process, which increases the reflectivity and scattering of light due to the lower spin-on-glass material, thereby reducing the problem of undesired exposure effects. Done.

Subsequently, a photoresist layer is formed on the antireflective coating (ARC) film (step S130). The photoresist layer may be coated on the ARC film with a thickness of about 10000 GPa by spin coating.

Subsequently, the photoresist layer is patterned to form a photoresist pattern (step S140).

Specifically, a mask is formed on the photoresist layer, and a mask capable of selectively transmitting light is positioned thereon, and an exposure process is performed. Only the specific region subjected to the light is chemically changed so that the pattern of the mask is aligned with the photoresist layer. At this time, it is preferable that the exposure process uses light having a short wavelength as the size of the pattern becomes smaller. As an example, a 193 nm ArF excimer light source may be used in a VLSI processor of 1G DRAM or more, and a F ₂ light source of 157 nm may be used to form an ultrafine pattern of about 50 nm.

After performing the exposure process, a development process is performed with a developer containing a basic material to remove the exposed or unexposed portions of the photoresist layer. As a result, a photoresist pattern is formed on the ARC film. In this case, tetra-methyl ammonium hydroxide (TMAH) is used as the solvent, and the photoresist layer subjected to the exposure process is removed from the substrate.

Subsequently, the exposed ARC film is removed after the patterning process to pattern the lower hard mask film.

Thereafter, a rinse process using deionized water may be further performed to remove the solvent and residues remaining on the thin film.

As described above, the substrate on which the hard mask film is formed is cleaned by using deionized water as a cleaning liquid and converted to have a hydrophilic bond, thereby adhering adhesion and repulsive force between groups bonded to the antireflective coating (ARC) film that is subsequently formed. Can reduce the difference. Therefore, the occurrence of defects in the ARC film can be reduced and the reliability of the photoresist pattern formed on the ARC film can be improved.

3 to 7 are cross-sectional views illustrating a pattern forming method using the method of forming a photoresist pattern according to Embodiment 2 of the present invention.

Referring to FIG. 3, a hard mask layer 110 is formed on an etching target. The etching target is the semiconductor substrate 100 on which the thin film 102 is formed. For example, the thin film 102 may be a silicon oxide film, a nitride film, a polysilicon film, a metal film, or the like. The hard mask film 110 has a structure in which a spin-on-carbon (SOC) film 106 and a spin-on-glass (SOG) film 108 are stacked.

In this case, the SOC film 106 is an amorphous carbon film, which is formed by spin-coating a composition containing a carbon polymer on a substrate and then performing a curing process. The hard mask film 108 is formed by spin coating a spin-on-glass material including silsesquioxane as a silicon oxide film on a substrate and then curing it.

Subsequently, a cleaning process is performed to surface-treat the hard mask layer 110 to have a hydrophilic surface. As an example, the deionized water is applied onto the substrate 100 using the equipment shown in FIG. 2 and ultrasonic wave energy is applied to perform the cleaning process.

By performing the cleaning process, the polymers constituting the hard mask layer 110 and the deionized water react to form a group having a hydrophobic bond on the surface of the hard mask layer 110 (OH—). It can be converted to have a hydrophilic bond by substituting with a group.

Therefore, the bonding force difference of the groups bonded between the spin-on-glass material and the subsequently formed antireflective coating material can be greatly reduced. Accordingly, when forming the anti-reflective coating film on the existing hard mask film, there is a difference in adhesion and repulsion between the combined groups of the films to improve the defect problem in which a part is agglomerated. have.

Subsequently, an anti-reflection coating (ARC) layer 112 is formed on the hard mask layer 110. The ARC film 112 is formed to a thickness of about 400 ~ 600Å. The ARC film 112 is to reduce the refractive index of the light exposed during the subsequent photolithography process, the reflection and scattering of the light due to the lower spin-on-glass (SOG) film quality is increased to bring an unwanted exposure effect It will serve to reduce the problem.

Referring to FIG. 4, a photoresist layer 114 is formed on the antireflective coating (ARC) 112 film.

Specifically, after the spin coating of the photoresist composition on the ARC 112 film, a first baking process is performed. The first baking process may be performed at a temperature of about 90 to about 120 ℃. The photoresist layer 114 is formed to increase adhesion to the ARC film 112 by performing the first baking process.

Referring to FIG. 5, a photoresist pattern 116 is formed on the ARC 112 film. First, a mask 118 having a predetermined pattern is positioned on a mask stage of an exposure apparatus, and the exposure mask 118 is aligned on the photoresist layer 114. Subsequently, the exposure mask 118 is irradiated with light for a predetermined time to project the light transmitted through the mask 118 onto the photoresist layer 114. As a result, a predetermined portion of the photoresist layer 114 including silicon reacted with the light is exposed and chemically changed. That is, the photoresist layer 114 of the exposed portion is relatively hydrophilic than the photoresist layer 114 of the non-exposed portion, so that the photoresist layer 114 of the exposed portion and the non-exposed portion are different from each other. Has solubility. Light with which can be used in the exposure process, it is preferable crazy a short wavelength, for example, and the like of the 193nm ArF excimer light source of 157nm or F ₂ light source.

Subsequently, a second baking process may be further performed on the substrate 100. The second baking process may be performed at a temperature of about 90 ° C to about 150 ° C. By performing the second baking process, the photoresist layer 114 of the exposed portion may be easily dissolved in a specific solvent. Subsequently, the photoresist pattern 120 is formed by removing the photoresist layer 114 of the exposed or unexposed portions. As an example of the solvent, tetra-methyl ammonium hydroxide (TMAH) or the like may be used, and the photoresist pattern 120 is completed by dissolving the photoresist layer 114 of the exposed portion. .

Subsequently, the ARC film 112 exposed to the photoresist pattern 120 is removed before the hard mask film 110 is patterned.

Referring to FIG. 6, the hard mask layer 110 exposed to the photoresist pattern 120 is etched to form a hard mask layer pattern 110a including a spin-on material. Specifically, the hard mask pattern 110a is formed by dry etching the hard mask layer 110 using an etching gas containing oxygen, and the spin-on-carbon layer pattern 106a and the spin-on-glass layer The pattern 108a has a stacked structure.

Subsequently, the exposed thin film 102 is patterned by applying the photoresist pattern 120 and the hard mask pattern 110a as an etching mask. As a result, a thin film pattern 102a is formed on the substrate 100.

Referring to FIG. 7, a development process and a rinse process are performed on the hard mask layer pattern 110a and the photoresist pattern 120 on the thin film pattern 102a and removed from the thin film pattern 102a.

In this case, tetra-methyl ammonium hydroxide (TMAH) or the like is used as the solvent used to perform the developing process, and the exposed photoresist pattern 120 and the hard mask layer pattern 110a are solvents. Dissolved in and removed. Thereafter, it is preferable to further perform a rinse process using deionized water to remove the solvent and residue remaining on the thin film pattern 102a.

According to the method of forming the photoresist pattern of the present invention and the pattern forming method using the same, the cleaning process is performed by applying ultrasonic energy to deionized water on a substrate on which a hard mask film including a spin-on-glass material is formed. The group bound to the surface of the spin-on-glass material of the mask film can be converted to hydrophilic.

Therefore, the bonding force difference of the groups bonded between the spin-on-glass material and the subsequently formed antireflective coating material can be greatly reduced. Accordingly, when forming the anti-reflective coating film on the hard mask film, a difference in adhesion force and repulsive force between the combined groups of the films may be generated, thereby improving a defect problem in which a part is agglomerated.

In addition, since a defect does not occur after coating of the antireflective coating layer on the substrate, the reliability of the photoresist pattern formed on the antireflective coating layer may be improved.

Although described above with reference to a preferred embodiment of the present invention, those skilled in the art will be variously modified and changed within the scope of the invention without departing from the spirit and scope of the invention described in the claims below I can understand that you can.

Claims (4)

Forming a hard mask film comprising a spin-on-glass material on the substrate; Performing a cleaning process for surface treating the surface of the hard mask layer to have hydrophilicity; Forming an anti-reflective coating layer on the hard mask layer on which the cleaning process is performed; Forming a photoresist layer on the antireflective coating layer; And Patterning the photoresist layer to form a photoresist pattern. The method of claim 1, further comprising forming a preliminary hard mask film including carbon as a spin-on material on the substrate before forming the hard mask film. The method of claim 1, wherein performing the cleaning process comprises: Rotating the substrate; Providing de-ionized water as a cleaning liquid on the substrate; Applying ultrasonic energy to a cleaning liquid provided on the substrate; And And brushing the substrate provided with the cleaning liquid. The method of claim 1, wherein performing the cleaning process comprises: Rotating the substrate; Providing de-ionized water to which ultrasonic energy is applied as a cleaning liquid on the substrate; And And brushing the substrate provided with the cleaning liquid.

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