JP2008015168A - Method for manufacturing near field exposure mask, near field exposure method and near field exposure device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a near field exposure mask by which distortion on a mask surface can be suppressed and a flat mask can be formed in manufacturing a near field exposure mask using a rubber elastic material, and to provide a near field exposure method and a near field exposure device. <P>SOLUTION: The method for manufacturing a near field exposure mask includes: a step of preparing a first substrate; a release layer forming step of forming a release layer on the first substrate; a light shielding layer forming step of forming a light shielding layer that blocks illumination light on the release layer; an aperture forming step of forming an aperture opening having a width shorter than the wavelength of the illumination light on the light shielding layer; a mask base forming step of forming a mask base material made of a rubber elastic material that is transparent to the illumination light, on the light shielding layer where the aperture is formed; a second substrate joining step of joining a second substrate that is transparent to the illumination light on the mask base material; and a first substrate peeling step of peeling the first substrate from the light shielding layer via the peeling layer. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a near-field exposure mask manufacturing method, a near-field exposure method, and a near-field exposure apparatus used in lithography technology when manufacturing semiconductor devices and optical devices.

With the advancement and diversification of lithography techniques, various exposure methods have been proposed as emerging lithography techniques for exploring new possibilities.
Among such exposure methods, for example, an exposure method using an optical near field that allows fine processing beyond the diffraction limit of light as in Patent Document 1 has been proposed.

In this exposure method using near-field exposure, in order to expose a fine pattern on the resist using near-field exposure, exposure is performed with the minute openings formed in the mask and the distance between the resists as close as possible. This is because the intensity distribution of the near-field light rapidly attenuates as the distance from the minute aperture increases.
However, there are slight undulations and irregularities in the resist-coated substrate. In order to perform near-field exposure on such a substrate, it is necessary to ensure adhesion of the mask to waviness or unevenness in a desired region.

Therefore, Patent Document 2 proposes that the mask substrate is made into a thin film and used as a mask that can be elastically deformed, and the thin film portion is deformed by pressure control or the like to perform adhesion peeling with the resist.
As a manufacturing method of such a near-field exposure mask, a fine pattern is formed on a thin film that becomes a light-shielding film on a substrate, a material that becomes a base material of the mask is formed thereon, and finally the substrate is removed and the mask is removed. There is known a method of manufacturing the above.

In addition to the above, a technique called nanoimprint is known as an emerging lithography technique.
In this nanoimprint, a technique is adopted in which a stamp having a nano-sized structure is pressed against a viscous resist material, and the structure of the stamp is transferred to the resist material.
Also in this technique, it is difficult to transfer a uniform structure over the entire surface due to the swell of the substrate or the swell of the stamp itself. Therefore, Non-Patent Document 1 proposes a solution in which the stamp is made of polydimethylsiloxane having rubber-like elasticity to absorb the waviness of the substrate and transfer the pattern uniformly.
Japanese Patent Laid-Open No. 2003-156834 Japanese Patent Laid-Open No. 11-145051 The 4th International Conference on Nanoimprint and Nanoprint Technology Digest of Papers P. 20-21 ¨Comparison of two PDMS stamp materials in Soft UV-NIL

By the way, in the case of near-field exposure, the following problems arise when using a mask that is made thin and can be elastically deformed in order to ensure the adhesion of the mask to the waviness and unevenness present on the resist-coated substrate.
That is, the thin film portion of these masks may be destroyed by handling mistakes such as transportation, transportation, and installation during the mask fabrication process.
In view of this, it is conceivable to use a technique based on nanoimprinting in which a stamp is made of a rubber-like elastic material, instead of an elastically deformable thin film that may be destroyed, as a near-field exposure mask.
That is, according to this, it is possible to use a rubber-like elastic body that is not easily broken compared to the thin film, and it is possible to make the mask adhere to the resist uniformly as in the case of the nanoimprint described above.

However, since the near-field exposure mask requires a light-shielding film that blocks exposure light, the following inconvenience occurs when the technique using the rubber-like elastic body by the nanoimprint is transferred as it is.
That is, when a light-shielding film that blocks exposure light is formed on such a rubber-like elastic body, the surface of the rubber-like elastic body and the light-shielding film is distorted by the stress of the light-shielding film, and a flat mask is formed. It may be a hindrance.
Further explaining these, the surface of the polydimethylsiloxane film having rubber-like elasticity before forming the light-shielding film is shown on the atomic force microscope image as shown in FIG. It has a flat surface.
On the other hand, the atomic force microscope image in the case where the light shielding film is formed on the polydimethylsiloxane film shows that the surface is distorted by the stress of the light shielding film as shown in FIG. The flatness shown is gone.
Thus, when a near-field exposure mask is formed by forming a light-shielding film on a rubber-like elastic body, the surface of the rubber-like elastic body and the light-shielding film is distorted due to the stress of the light-shielding film. A difficult mask is difficult to form.

In view of the above problems, the present invention can suppress the generation of distortion on the mask surface when manufacturing a near-field exposure mask using a rubber-like elastic body that is less fragile than conventional ones, and can form a flat mask. An object of the present invention is to provide a method for manufacturing a near-field exposure mask that can be used.
Another object of the present invention is to provide a near-field exposure method and a near-field exposure apparatus using a mask that is manufactured by the above-described method for manufacturing a near-field exposure mask and is less fragile than conventional ones.

In order to solve the above problems, the present invention provides a near-field exposure mask manufacturing method, a near-field exposure method, and a near-field exposure apparatus configured as follows.
The method for manufacturing a near-field exposure mask according to the present invention includes a light-shielding layer in which a minute opening is formed, elastically deforms an object to be exposed, and performs contact exposure with near-field light generated in the minute opening. A manufacturing method of
Preparing a first substrate;
A release layer forming step of forming a release layer on the first substrate;
A light shielding layer forming step of forming a light shielding layer for shielding illumination light on the release layer;
Forming an opening having a width shorter than the wavelength of the illumination light in the light shielding layer; and
A mask base material forming step of forming a mask base material made of a rubber-like elastic body transparent to the illumination light on the light shielding layer in which the opening is formed;
A second substrate bonding step of bonding a second substrate transparent to the illumination light on the mask base material;
And a first substrate peeling step of peeling the first substrate from the light shielding layer through the peeling layer.
In the method of manufacturing a near-field exposure mask according to the present invention, the light shielding layer may be subjected to ozone ashing in the light shielding layer forming step.
In the method for producing a near-field exposure mask of the present invention, in the mask base material forming step, polydimethylsiloxane is used as a transparent rubber-like elastic body, and a layer having a thickness of 1 μm or more and 100 μm or less is formed. And
Also, the near-field exposure mask manufacturing method of the present invention is characterized in that, in the second substrate bonding step, the rubber-like elastic body and the second substrate are subjected to ozone ashing.
Further, the near-field exposure mask manufacturing method of the present invention uses a photoresist as a release layer in the release layer forming step, dissolves the photoresist using a solvent in the first substrate release step, and removes the light from the light shielding layer. The first substrate is peeled off.
Further, the near-field exposure method of the present invention is a near-field exposure method in which the exposure mask is deformed and brought into close contact with an object to be exposed, and exposure is performed using a near-field that oozes from a minute opening formed in the exposure mask.
As the exposure mask, a near-field exposure mask manufactured by any one of the above-described methods for manufacturing a near-field exposure mask is used, and the light-shielding film side of the near-field exposure mask is disposed to face the object to be exposed. Process,
Bringing the near-field exposure mask close to the object to be exposed and pressing the near-field exposure mask against the object to be exposed with a uniform force;
Illuminating exposure light from the second substrate side of the near-field exposure mask;
It is characterized by having.
Further, the near-field exposure apparatus of the present invention is a near-field exposure apparatus that performs exposure using a near-field that oozes from a minute opening formed in the exposure mask by deforming the exposure mask and closely contacting the object to be exposed.
As the exposure mask, provided with a near-field exposure mask manufactured by the method for manufacturing a near-field exposure mask according to any of the above,
A mask contact mechanism for pressing the near-field exposure mask against the object to be exposed with a uniform force;
An exposure light source that illuminates light from the second substrate side of the near-field exposure mask;
It is characterized by having.

According to the present invention, when a near-field exposure mask is manufactured using a rubber-like elastic body that is harder to break than the conventional one, the occurrence of mask surface distortion can be suppressed, and a flat mask can be formed. A method of manufacturing a near-field exposure mask can be realized.
Further, according to the present invention, it is possible to realize a near-field exposure method and a near-field exposure apparatus using a mask that is manufactured by the above-described method for manufacturing a near-field exposure mask and is less fragile than the conventional one.

Next, an embodiment of the present invention will be described.
In this embodiment, the mask base material of the near-field exposure mask is formed of a rubber-like elastic body.
As this rubber-like elastic body, a material that deforms greatly compared to glass or metal and restores its original shape when unloaded is used.
Specifically, the Young's modulus is 1 Mpa or more and 1 GPa or less. For example, polydimethylsiloxane (hereinafter referred to as PDMS) can be used.
PDMS is transparent at wavelengths of 250 nm and above. Specific examples of PDMS include Sylgard 182, 184 and 186 manufactured by Dow Corning Company and marketed by Sylgard®.

In the present embodiment, a near-field exposure mask is formed as follows using such a mask base material made of a rubber-like elastic body.
First, a first substrate on which a release layer is formed is prepared.
Next, a light shielding film is formed on the peeling layer formed on the first substrate, and a minute opening is formed in the light shielding film.
Next, a mask base material made of the rubber-like elastic body is formed on the light shielding film in which the minute openings are formed.
Next, a transparent second substrate is bonded to the surface of the mask base material.
Finally, the first substrate is peeled from the surface of the light shielding film through the peeling layer.
Thereby, generation | occurrence | production of the distortion of the surface of a rubber-like elastic body and a light shielding film can be suppressed, and a flat mask can be formed.

Examples of the present invention will be described below.
[Example 1]
In Example 1, a manufacturing method of a near-field exposure mask to which the present invention is applied will be described.
FIG. 1 shows a process flow for explaining a procedure for producing a near-field exposure mask in this embodiment.
In FIG. 1, 101 is a silicon substrate, 102 is a peeling layer, 103 is a light-shielding film, 104 is a minute opening, 105 is a mask base material, and 106 is a transparent substrate.
When producing a near-field exposure mask, first, a silicon substrate 101 having a flat surface is prepared (FIG. 1A).
Next, a photoresist having a thickness of 1 μm is formed on the silicon substrate 101 having a flat surface by a spin coating method. (FIG. 1 (b)).
This photoresist layer can be easily dissolved by immersing it in an organic solvent and applying ultrasonic waves, and has a function as a release layer 102.
The release layer 102 may be any organic material that is soluble in an organic solvent. In addition to such an organic material, any material that can be readily dissolved in a solvent can be used as the release layer 102.

Next, chromium (Cr) is formed with a thickness of 50 nm by a sputtering method as a light-shielding film 103 having a light-shielding property with respect to exposure light used in an exposure process described later (FIG. 1C).
Here, Cr is used as the light-shielding film 103, but any material having sufficient light-shielding performance against exposure light used in an exposure process to be described later may be used. A method for forming the film may be a sputtering method or a vacuum evaporation method. Any film forming method such as a sol-gel method may be used.

Next, a minute opening 104 is formed in the Cr light-shielding film 103 (FIG. 1D). Any method may be used for the method of manufacturing the minute opening 104. For example, an electron beam resist may be applied on the light shielding film, patterned by electron beam drawing, and dry etching of the light shielding film may be performed using the resist as a mask.
Alternatively, the light shielding film 103 may be directly processed using a focused ion beam (FIB). Furthermore, any other method can be used as long as it is a microfabrication means capable of forming a microscopic opening.

Next, polydimethylsiloxane (PDMS) having a rubbery elasticity as a mask base material 105 was applied on the light-shielding film 103 having the minute openings 104 by spin coating, and baked to a thickness of 10 μm. (FIG. 1 (e)).
As the coating method, in addition to the spin coating method, a dipping method, a spin coating method, a spray coating method, a vapor deposition method, or the like can be used. Baking is performed at 100 to 200 ° C. for about 10 to 60 minutes using a heating means such as a hot plate or hot air dryer.
At that time, ozone ashing treatment was performed on the light shielding film 103 in order to improve the PDMS adhesion between the light shielding film 103 and the mask base material 105.

At this time, polydimethylsiloxane was used as the mask base material 105. However, any material having sufficient transmittance with respect to exposure light used in an exposure process described later and having rubber-like elasticity may be used. It is not limited to siloxane.
In this embodiment, the thickness of the rubbery elastic material is 10 μm. However, the thickness is 0.1 μm to 1000 μm depending on the adhesion pressure in the adhesion operation performed in the exposure process described later and the swell of the substrate. The film may be formed with a preferable thickness within the range. Here, the thickness is particularly preferably 1 μm to 100 μm.

Next, a quartz substrate is bonded as the transparent substrate 106 to the PDMS surface of the mask base material 105, and both are bonded (FIG. 1 (f)).
In this embodiment, the quartz substrate is bonded, but the material is not limited to this material, and any substrate such as a diamond substrate or a sapphire substrate may be used as long as it is transparent to the exposure light used in the exposure process described later.
In this bonding step, ozone ashing is performed on the substrate and the surface of the PDMS as necessary in order to improve the adhesion between the PDMS and the transparent substrate 106.
At that time, other means for increasing the adhesion may be performed, for example, the substrate and the PDMS surface may be exposed to an ultraviolet-ozone atmosphere. Or you may provide the primer layer for raising adhesiveness.

Finally, the substrate on which the film has been formed is immersed in an organic solvent such as N, N-dimethylacetamide or acetone, and the photoresist film of the peeling layer 102 is dissolved by ultrasonic cleaning, and the silicon substrate is peeled off. (FIG. 1 (g)).
By the above production procedure, a light-shielding film can be formed on the upper layer of the rubber-like elastic body without generating distortion on the surface, and a near-field exposure mask without distortion on the surface can be produced.

[Example 2]
In Example 2, an exposure method using a near-field exposure mask manufactured by a method for manufacturing a near-field exposure mask to which the present invention is applied will be described.
FIG. 2 is a diagram for explaining the near-field exposure method of this embodiment.
In FIG. 2, 201 is a near-field exposure mask, 202 is a photoresist substrate, 203 is a light shielding film, and 204 is a transparent substrate.

At the time of exposure, a photoresist is formed on the substrate (hereinafter, the substrate on which the photoresist is formed is referred to as a photoresist substrate 202).
Next, the surface of the near-field exposure mask 201 on which the light-shielding film 203 exists is opposed to the photoresist surface of the photoresist substrate 202, and both are brought into close contact with a uniform force.
At this time, since the base material of the near-field exposure mask 201 has a rubber-like elastic body, the rubber-like elastic body is deformed following the wave of the substrate, and the near-field exposure mask 201 and the photoresist substrate 202 are evenly adhered. Is obtained.
Thereafter, i-line (wavelength 365 nm) of a mercury lamp is irradiated as exposure light EL from the transparent substrate 204 side of the near-field exposure mask 201, and near-field light generated from a minute opening formed in the light-shielding film 203 of the near-field exposure mask 201. To expose the photoresist.
Next, by developing the photoresist, a pattern can be formed in the photoresist.

In the present embodiment, as a means for making the near-field exposure mask face the photoresist surface of the photoresist substrate and bringing them into close contact with each other with a uniform force, for example, the one having the structure shown in Patent Document 2 described above is used. Can be used.
Further, the i-line of the mercury lamp is used as the exposure light, but the present invention is not limited to this as long as the photoresist has a wavelength with sensitivity.
For example, when a photoresist having sensitivity at a wavelength of 248 nm is used, a deuterium lamp or a KrF excimer laser may be used.
When a photoresist having a sensitivity at a wavelength of 193 nm is used, an ArF excimer laser may be used, and the type of light source is not limited.

It is a figure which shows the process flow for demonstrating the preparation procedure of the near-field exposure mask in Example 1 of this invention. It is the schematic for demonstrating the exposure method using the near-field exposure mask in Example 2 of this invention. It is an atomic force microscope image of the surface of the film | membrane of the polydimethylsiloxane which has rubber-like elasticity before forming the light shielding film for demonstrating the subject of this invention. It is an atomic force microscope image of the surface which formed the light shielding film on the film | membrane of polydimethylsiloxane for demonstrating the subject of this invention.

Explanation of symbols

101: Silicon substrate 102: Release layer 103: Light shielding film 104: Micro opening 105: Mask base material 106: Transparent substrate 201: Near-field exposure mask 202: Photoresist substrate 203: Light shielding film 204: Transparent substrate

Claims (7)

A method of manufacturing a near-field exposure mask having a light-shielding layer having a minute opening, elastically deforming an object to be exposed, and performing contact exposure with near-field light generated in the minute opening,
Preparing a first substrate;
A release layer forming step of forming a release layer on the first substrate;
A light shielding layer forming step of forming a light shielding layer for shielding illumination light on the release layer;
Forming an opening having a width shorter than the wavelength of the illumination light in the light shielding layer; and
A mask base material forming step of forming a mask base material made of a rubber-like elastic body transparent to the illumination light on the light shielding layer in which the opening is formed;
A second substrate bonding step of bonding a second substrate transparent to the illumination light on the mask base material;
A first substrate peeling step of peeling the first substrate from the light shielding layer through the peeling layer;
A method of manufacturing a near-field exposure mask, comprising:   The method for manufacturing a near-field exposure mask according to claim 1, wherein in the light shielding layer forming step, the light shielding layer is subjected to ozone ashing treatment.   3. The near field according to claim 1, wherein, in the mask base material forming step, polydimethylsiloxane is used as a transparent rubber-like elastic body to form a layer having a thickness of 1 μm or more and 100 μm or less. Manufacturing method of exposure mask.   4. The method of manufacturing a near-field exposure mask according to claim 1, wherein in the second substrate bonding step, the rubber-like elastic body and the second substrate are subjected to ozone ashing treatment.   The photoresist is used as a release layer in the release layer forming step, the photoresist is dissolved using a solvent in the first substrate release step, and the first substrate is released from the light shielding layer. Item 5. A manufacturing method of a near-field exposure mask according to any one of Items 1 to 4. In the near-field exposure method in which the exposure mask is deformed and brought into close contact with an object to be exposed, and exposure is performed using a near-field that oozes out from a minute opening formed in the exposure mask.
A near-field exposure mask manufactured by the method for manufacturing a near-field exposure mask according to claim 1 is used as the exposure mask, and the light-shielding film side of the near-field exposure mask faces the object to be exposed. And arranging the process,
Bringing the near-field exposure mask close to the object to be exposed and pressing the near-field exposure mask against the object to be exposed with a uniform force;
Illuminating exposure light from the second substrate side of the near-field exposure mask;
A near-field exposure method comprising: In a near-field exposure apparatus that performs exposure using a near field that oozes from a minute opening formed in the exposure mask by deforming the exposure mask and closely contacting the object to be exposed.
As the exposure mask, comprising a near-field exposure mask manufactured by the method of manufacturing a near-field exposure mask according to any one of claims 1 to 5,
A mask contact mechanism for pressing the near-field exposure mask against the object to be exposed with a uniform force;
An exposure light source that illuminates light from the second substrate side of the near-field exposure mask;
A near-field exposure apparatus comprising:

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