JP4998168B2 - Imprint mold manufacturing method - Google Patents

Description

  The present invention relates to a method for manufacturing an imprint mold used for forming a fine three-dimensional structure pattern.

  An imprint mold in which a specific fine three-dimensional structure pattern (for example, a multi-step shape) is formed on a substrate (for example, glass, resin, metal, silicon, etc.) is expected to be used in a wide range of fields. Has been. For example, semiconductor devices, optical elements, wiring circuits, recording devices (such as hard disks and DVDs), medical testing chips (such as DNA analysis applications), display panels, and microchannels can be used.

  In recent years, there has been an increasing demand for finer patterns and structures with a larger number of steps in imprint molds.

  For example, in the semiconductor field, it has been proposed to use a multi-stage imprint mold in forming a dual damascene structure in which a specific fine three-dimensional structure pattern is formed (see Non-Patent Document 1).

  In the manufacture of a multi-stage imprint mold, the photosensitive resin is patterned a plurality of times according to the level difference. Hereinafter, as an example, a method for producing a multi-stage imprint mold will be specifically described with reference to FIG.

First, a mold original plate 3 having conductivity on the quartz substrate 1 and having a metal thin film 2 serving as a mask for quartz etching on the surface is prepared, and a photosensitive resin 4 is applied.
Next, the pattern of the first layer and the alignment mark (not shown in the drawing) are drawn and developed by a drawing apparatus using an electron beam and a laser as a light source (FIG. 1B).
Next, the metal thin film 2 is removed by plasma etching (FIG. 1C).
Next, the quartz 1 is etched (FIG. 1D).
Next, residual photosensitive resin or the like is removed by a cleaning process to obtain a mold intermediate (FIG. 1 (e)).
Next, the photosensitive resin 5 is applied again in order to pattern the second layer. When processing the second layer with an electron beam, an electron beam photosensitive resin is used, and a conductive polymer having electrical conductivity (not shown in the drawing) is applied thereon (FIG. 1 (f)).
Next, based on the alignment mark, the first layer is overlaid and the second layer is drawn and developed to obtain a pattern (FIG. 1 (g)).
Next, similarly to the first layer, the metal thin film 2 is removed by plasma etching (FIG. 1 (h)), and then the quartz 1 is etched (FIG. 1 (i)).
Next, the residual photosensitive resin and the metal thin film are removed.
From the above, an imprint mold having a multistage structure (FIG. 1 (k)) is completed.

On the other hand, it has been reported that addition of fullerenes to a photosensitive resin can prevent pattern collapse during development and improve dry etching resistance (see Patent Documents 1 and 2).
JP-A-10-282649 JP 2005-53832 A Proc. Of SPIE., Vol.5992, pp.786-794 (2005)

  In the manufacture of a multi-stage imprint mold, the photosensitive resin is patterned a plurality of times according to the level difference.

  However, when a step structure is further formed on a substrate already provided with a step, the photosensitive resin film on the convex portion becomes thin when the photosensitive resin is applied on the stepped substrate. The conductive resin film cannot be obtained (see FIG. 1 (f)). For this reason, the edge portion of the non-uniform photosensitive resin film (thin portion of the photosensitive resin film) disappears preferentially at the time of etching, and excessive etching is performed at the edge portion, so that the shape of the structure pattern It will cause defects.

  Then, this invention is made | formed in order to solve the above-mentioned subject, and it aims at providing the imprint mold manufacturing method suitable for manufacture of the imprint mold provided with the several level | step difference.

  The present invention described in claim 1 includes a step of applying a photosensitive resin to a substrate, a step of patterning the photosensitive resin using exposure light, and etching the substrate using the patterned photosensitive resin as an etching mask. A step of patterning a new pattern using exposure light on the photosensitive resin, and a step of etching the substrate again using the patterned photosensitive resin as an etching mask. It is the imprint mold manufacturing method characterized.

  The present invention described in claim 2 is the imprint mold manufacturing method according to claim 1, wherein the etching step is an etching step using plasma etching, and the photosensitive resin is sensitive to plasma emission. It is an imprint mold manufacturing method characterized by being resin which does not have property.

  The present invention described in claim 3 is the imprint mold manufacturing method according to claim 2, wherein the photosensitive resin contains carbon black, fullerene or a derivative thereof. is there.

  A fourth aspect of the present invention is the imprint mold manufacturing method according to any one of the first to third aspects, wherein the substrate is a substrate in which a metal thin film is formed on the surface of the substrate. It is an imprint mold manufacturing method.

  The present invention according to claim 5 is the imprint mold manufacturing method according to claim 1, wherein a pattern is formed on the patterned photosensitive resin, and the patterned photosensitive resin is etched. An imprint mold manufacturing method comprising performing the step of etching the substrate as a mask a plurality of times.

The imprint mold manufacturing method of the present invention is characterized in that a new pattern is patterned again on a patterned photosensitive resin used as an etching mask, and etching is performed again.
According to the configuration of the present invention, an imprint mold having a plurality of step structures can be formed by performing patterning on a photosensitive resin a plurality of times without applying the photosensitive resin again to the stepped substrate. Can be manufactured. For this reason, the shape defect of the structure pattern resulting from the application | coating of a non-uniform photosensitive resin can be prevented, and it becomes possible to form a fine three-dimensional structure pattern accurately.

Hereinafter, the imprint mold manufacturing method of the present invention will be described.
The imprint mold manufacturing method of the present invention includes:
Applying a photosensitive resin to the substrate;
Patterning the photosensitive resin using exposure light;
Etching the substrate using the patterned photosensitive resin as an etching mask;
Patterning a new pattern using exposure light on the photosensitive resin;
Etching the substrate again using the patterned photosensitive resin as an etching mask,
Is provided.

<Step of applying photosensitive resin to substrate>
First, a photosensitive resin is applied to the substrate. As a coating method, a known coating method may be used as appropriate. For example, a spin coating method or a die coating method may be used.

  The substrate may be any material that has sufficient processing characteristics for the etching process described later. For example, silicon or quartz may be used. In particular, quartz exhibits good transmission characteristics with respect to general exposure light, and thus can be suitably used for manufacturing an optical imprint mold used in the optical imprint method.

  The substrate is preferably a substrate having a metal thin film formed on the substrate surface. By forming the metal thin film on the substrate surface, the etching ratio between the substrate body and the metal thin film and the etching ratio between the photosensitive resin and the metal thin film can be increased. For this reason, a fine pattern can be suitably formed. In particular, in the imprint mold manufacturing method of the present invention, since the second and subsequent patterns form a finer pattern than the first pattern, the effect of forming a metal thin film is very large. In addition, when the step of the final layer of the imprint mold is formed, the etching conditions can be easily set because the substrate may be etched using only the metal thin film as an etching mask.

  A material for the photosensitive resin may be selected according to the pattern width to be formed. In addition, the photosensitive resin used in the present invention is preferably a photosensitive resin that does not require baking before development because it is subjected to patterning a plurality of times after being applied once.

  As the photosensitive resin, for example, a positive type electron beam photosensitive resin (trade name: ZEP520A) may be used. ZEP520A has a high pre-bake temperature (about 180 ° C.), does not require PEB, is durable against repeated development, and is not sensitive to light having a wavelength of 300 nm or more. It is a photosensitive resin suitable for the method. In addition, since the polymer itself has a benzene ring having a carbon conjugated double bond, the photosensitive resin itself has an ultraviolet light absorption effect, and there is a characteristic that ultraviolet light does not easily enter the polymer.

<Step of patterning photosensitive resin using exposure light>
Next, the photosensitive resin is patterned using exposure light. In pattern formation, a known fine pattern forming method may be used as appropriate, and a lithography method or the like may be used.

  In addition, it is preferable to form alignment marks simultaneously with pattern formation. Since the imprint mold manufacturing method of the present invention performs patterning a plurality of times, it is necessary to align the position of the second and subsequent pattern formations relative to the already formed pattern. For this reason, in the imprint mold manufacturing method of this invention, the effect which provides an alignment mark is very large.

<Process for etching the substrate>
Next, the substrate is etched using the patterned photosensitive resin as an etching mask. As an etching method, a known etching method / apparatus may be appropriately used.

  Further, the etching process is an etching process using plasma etching, and the photosensitive resin is preferably a resin that is not sensitive to plasma emission. In the case of performing plasma etching, there is a possibility that ultraviolet light having a wavelength that causes photosensitivity of the photosensitive resin (light having a wavelength of 300 nm or more) is generated by light emission of plasma. For this reason, when etching using plasma etching is used, it is preferable to use a resin that does not have photosensitivity to plasma emission, so that the photosensitive resin is prevented from being excessively exposed at the stage of etching. Patterning can be performed again.

In the case of an etching process using plasma etching, the photosensitive resin preferably contains carbon black, fullerene or a derivative thereof.
Carbon black, fullerene or derivatives thereof are known to have a large number of carbon conjugated double bonds, and can absorb ultraviolet light by the carbon conjugated double bonds, thereby improving the ultraviolet light shielding performance. . Therefore, carbon black, fullerene, or a derivative thereof has strong absorption against ultraviolet light, and thus is particularly suitable as an ultraviolet photosensitive inhibitor used in the imprint mold manufacturing method of the present invention.
In particular, by adding fullerenes to the photosensitive resin, it is possible to increase the strength of the photosensitive resin, prevent pattern collapse during development, and improve dry etching resistance.

When a quartz substrate is used, it is desirable to perform NLD (magnetic neutral plasma) etching.
In order to anisotropically etch quartz, RIE (reactive ion etching) is usually used. More preferably, an NLD (magnetic neutral line plasma) method, which is a kind of RIE, can be used. The etching mechanism of quartz is considered to be that a reaction layer containing CF is always formed on the etching surface, and etching occurs when C or F in the reaction layer reacts with quartz due to ion bombardment. The NLD method is characterized by low-pressure, high-density plasma. Compared to other methods, the NLD method has a higher ratio of ions to radicals in the plasma, and performs etching with higher selectivity for quartz that progresses by fluorocarbon ion bombardment. I can do it.

<Step of patterning a new pattern>
Next, a new pattern is patterned on the photosensitive resin using exposure light.
Similar to the above-described <patterning process of photosensitive resin using exposure light>, a new pattern may be patterned using the exposure light on the patterned photosensitive resin.

<Re-etching process>
Next, the substrate is etched again using the patterned photosensitive resin as an etching mask.
Etching may be performed on the substrate in the same manner as described above in <Process for etching substrate>.

  In the imprint mold of the present invention, the step of patterning a new pattern on the patterned photosensitive resin and the step of etching the substrate using the patterned photosensitive resin as an etching mask are performed a plurality of times. Also good. When the said process is performed in multiple times, the imprint mold provided with the step number according to the enforced frequency | count can be manufactured. Therefore, the imprint mold provided with the level | step difference of 3 steps or more can be suitably manufactured by performing the said process in multiple times.

The imprint mold manufacturing method of the present invention is characterized in that a new pattern is patterned again on the patterned photosensitive resin used as an etching mask, and etching is performed again. According to the configuration of the present invention, an imprint mold having a plurality of step structures can be formed by performing patterning on a photosensitive resin a plurality of times without applying the photosensitive resin again to the stepped substrate. Can be manufactured. For this reason, the shape defect of the structure pattern resulting from the application | coating of a non-uniform photosensitive resin can be prevented, and it becomes possible to form a fine three-dimensional structure pattern accurately.
In addition, since the photosensitive resin coating process is not performed a plurality of times, the number of processes can be reduced (reduction of the coating process, cleaning process, etc. for each number of stages) and the amount of photosensitive resin used can be reduced.

  First, a quartz substrate 7 on which a Cr thin film 6 having a thickness of 10 nm was formed by sputtering was prepared.

  Next, a fullerene C60 derivative {(PCNBB: phenyl C61-butyl acid n-butyl ester), (trade name: nanom spectra E200)} is added to the positive electron beam photosensitive resin (trade name: ZEP520A). % Photosensitive resin 8 was coated with a thickness of 400 nm using a spin coating method (FIG. 2A).

Next, patterning of the first layer (wiring layer) and the alignment mark for superposition was performed on the photosensitive resin 8 at a dose of 100 μC / cm ² using an electron beam drawing apparatus.
Next, it developed with the developing solution (brand name: ZED-N50), and obtained the resist pattern of the 1st layer (FIG.2 (b)).

Next, the Cr thin film 6 was etched using Cl ₂ and O ₂ as etching gases. (Fig. 2 (c))
At this time, the pressure during etching was 1.5 Pa to 3 Pa.

Next, the etching gas was switched to CF ₄ and CH ₂ F ₂ to set the pressure to 0.8 Pa, and the quartz substrate 7 was etched to a depth of 250 nm (FIG. 2D).

Next, a conductive polymer (trade name: aquaSAVE, manufactured by Mitsubishi Rayon Co., Ltd.) was applied to the entire surface layer including the photosensitive resin 8, and baked at 110 ° C. for about 300 seconds (not shown in the drawing).
At this time, the conductive polymer had a film thickness of about 25 nm.
The conductive polymer only needs to ensure conductivity on the substrate surface, and the degree of adhesion to the substrate surface and film thickness unevenness do not cause a problem in the drawing process. Further, the baking temperature of aquaSAVE is sufficiently lower than the pre-baking temperature of ZEP520A, and there is no influence on the already patterned photosensitive resin. Further, it can be easily removed by rinsing with pure water.

  Next, the second layer (Via layer) was drawn on the basis of the alignment mark information by an electron beam drawing apparatus, and the second layer was patterned through polymer peeling and development (FIG. 2 (e)).

Next, as in the first layer, Cl ₂ and O ₂ are used as etching gases, the second layer Cr film is etched (FIG. 2F), and the etching gas is switched to CF ₄ and CH ₂ F _2. The second layer (Via layer) quartz was etched to 200 nm using the thin film as a mask (FIG. 2G).

Next, the Cr thin film was removed by etching with Cl ₂ and O ₂ gas (FIG. 2 (h)).
From the above, an imprint mold having a multistage structure was produced.

It is a figure which shows the imprint mold production process which has the conventional multistage structure. It is a figure which shows the imprint mold production process which has a multistage structure of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Quartz substrate 2 ... Metal thin film 3 ... Substrate 4 ... Photosensitive resin 5 ... Photosensitive resin 6 with non-uniform film thickness ... Cr thin film 7 ... Quartz substrate 8 ... Fullerene mixed photosensitive resin

Claims (5)

Applying a photosensitive resin to the substrate;
Patterning the photosensitive resin using exposure light;
Etching the substrate using the patterned photosensitive resin as an etching mask;
Patterning a new pattern using exposure light on the photosensitive resin;
Etching the substrate again using the patterned photosensitive resin as an etching mask,
An imprint mold manufacturing method comprising: The imprint mold manufacturing method according to claim 1,
The etching process is an etching process using plasma etching,
The photosensitive resin is a resin that is not sensitive to plasma emission,
The imprint mold manufacturing method characterized by these. The imprint mold manufacturing method according to claim 2,
The method for producing an imprint mold, wherein the photosensitive resin contains carbon black, fullerene, or a derivative thereof. The imprint mold manufacturing method according to any one of claims 1 to 3,
An imprint mold manufacturing method, wherein the substrate is a substrate having a metal thin film formed on the substrate surface. The imprint mold manufacturing method according to claim 1,
Patterning a new pattern on the patterned photosensitive resin;
Etching the substrate using the patterned photosensitive resin as an etching mask;
The imprint mold manufacturing method characterized by performing multiple times.