JP2015053459A - Method for forming resist pattern and method for producing mold - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for forming a pattern of a resist, bringing high resolution to a resist layer while suppressing a required exposure amount.SOLUTION: In a method for forming a resist pattern, a resist layer formed by coating a solution on a substrate surface is drawn or exposed, and subjected to development processing to form a resist pattern, the solution mainly containing a compound that has a main chain of repeated siloxane bonds and a composition capable of forming a solute of a solution using an organic solvent as a solvent. The method includes: a first heating treatment step of subjecting a resist layer formed by coating a solution to heating treatment at a first heating treatment temperature; a pattern drawing step of performing drawing or exposure on the resist layer after the first heating treatment step; a first development processing step of subjecting the resist layer through the pattern drawing step to development processing using a first developer liquid; a second heating treatment step of subjecting the resist layer through the first development processing step to heating treatment at a second heating treatment temperature; and a second development processing step of subjecting the resist layer through the second heating treatment step to development processing using a second developer liquid.

Description

  The present invention relates to a method for forming a resist pattern and a method for producing a mold. In particular, the present invention relates to a pattern on a resist layer containing hydrogen silsesquioxane (hereinafter referred to as HSQ) having sensitivity to electron beams alone or as a main component. The present invention relates to a developing solution and a developing treatment method for forming a film, and a mold manufacturing method using the resist pattern forming method.

As resists for electron beam drawing (exposure) capable of forming a pattern of 20 nm or less, polymethyl methacrylate, a copolymer of α-methylstyrene and α-chloroacrylic acid, calixarene, HSQ and the like are commercially available.
In particular, HSQ is a compound having a main chain of repeated siloxane bonds (Si-O bonds). Therefore, when pattern processing is performed on a layer to be processed that can be dry-etched with an etching gas containing a mixed gas of chlorine and oxygen as a main component, for example, a layer containing chromium (Cr) as a main component, HSQ is the most One suitable resist material. Further, since it has an organic functional group in the side chain, it is soluble in an organic solvent such as methyl isobutyl ketone (hereinafter referred to as MiBK).

  As a standard developer for HSQ, a 0.26N (2.38%) tetramethylhydroammonium aqueous solution (hereinafter referred to as TMAH aqueous solution) is recommended (see Non-Patent Document 1). On the other hand, various developing solutions have been studied in order to realize higher resolution, that is, formation of a finer pattern.

For example, an aqueous solution in which 4% of salt (NaCl) is added to 1% of sodium hydroxide (NaOH) has been devised (see Non-Patent Document 2). Using this developer, the required exposure (sensitivity): 5.5 nC / cm ² (acceleration voltage 10 kV) and resolution: 12 nm pitch (that is, 6 nm line and space pattern (hereinafter referred to as LS pattern)) It has been reported that the formation has been realized.

On the other hand, it has been studied to use various organic solvents as a developer (see Non-Patent Document 3). By using an organic solvent as a developer, compared with a developer composed of an aqueous solution in which 4% of salt (NaCl) is added to 1% of sodium hydroxide (NaOH), the resolution is inferior, but the required exposure is reduced ( It has been reported that high sensitivity can be realized. Specifically, it has been reported that a pattern with a pitch of 124 nm (that is, a LS pattern of 62 nm) can be formed with xylene (Xylene) as a developer and an exposure amount of 185 μc / cm ² (acceleration voltage 100 kV).

Further, as another means for improving the resolution of HSQ, there has been proposed an HSQ resist pattern forming method (development processing method) in which etching treatment with hydrofluoric acid is performed following development processing with an alkaline aqueous solution (non-patent document). (Ref. 4). When a resist layer made of HSQ is developed using an alkaline aqueous solution as a developer, a poorly soluble layer is formed on the surface of the resist layer made of HSQ during the development process, resulting in a residue (scum). Deteriorate. As a means for removing the hardly soluble layer, HSQ residue (scum) is removed by performing an etching process using hydrofluoric acid after a developing process using an alkaline aqueous solution. As a result, it is reported that an isolated dot pattern with a 25 nm pitch can be formed, that is, the resolution is improved.
Further, when an aqueous solution in which 4% of salt (NaCl) is added to 1% of sodium hydroxide (NaOH) is used as a developing solution, the functional effect of NaCl is similar to that of etching with hydrofluoric acid. It is reported to be removed.

Product Information: XR-1541 E-Beam Resist, DOW CORNING J.Vac.Sci.Technol.B 27 (6), Nov / Dec 2009, "Understanding of HSQ electron resist for sub-5nm-half-pitch lithography" J.Vac.Sci.Technol.B 22 (6), Nov / Dec 2004, "Nonaqueours development of Silsesquioxane electron beam resist" J.Vac.Sci.Technol.B 27 (1), Jan / Feb 2009, "Two-step resist development process of HSQ for high-density EB nano-patterning"

前記のアルカリ水溶液（３種）を現像液とした場合、露光部残膜率が最大となって飽和安定する露光量域は１０００μＣ／ｃｍ^２以上であり、そのコントラスト（γ値）は４．２乃至５．９であった。即ち、アルカリ水溶液による現像処理は、有機溶剤からなる現像液（３種）に対比して、解像度は高い（解像度に優る）が、感度が低い（必要露光量は高い）。
一方、前記各種の有機溶剤を現像液（３種）とした場合では、露光部残膜率が最大となって飽和安定する露光量域は１００μＣ／ｃｍ^２以下であるが、そのコントラスト（γ値）は１．２乃至２．６であった。即ち、アルカリ水溶液（３種）を現像液とした場合に対比して、有機溶媒による現像処理は、感度は桁違いに高い（必要露光量は桁違いに低い）が、解像度は低い（解像度に劣る）。
なお、ここでは便宜的に、残膜率２０％と８０％との間の残膜感度曲線の傾斜をコントラスト（γ値）と定義した。 In FIG. 1, a developer solution is isopropanol (hereinafter referred to as IPA), methyl ethyl ketone (MEK), methyl isobutyl ketone (hereinafter referred to as MiBK), 2.38% TMAH aqueous solution, 25% TMAH aqueous solution, sodium hydroxide (NaOH). ) A representative example of the result of obtaining the residual film sensitivity curve (exposed part residual film ratio with respect to electron beam exposure amount) of a resist layer made of HSQ as six types of an aqueous solution in which 4% of salt (NaCl) is added to 1%. is there. In any case, the acceleration voltage for exposure (drawing) is 100 kV. Here, in any case, the heat treatment after HSQ application is not performed.
Table 1 shows the results of obtaining the contrast (γ value) of each remaining film sensitivity curve shown in FIG.

When the alkaline aqueous solution (3 types) is used as a developing solution, the exposure amount region where the exposure portion residual film ratio becomes maximum and becomes saturated and stable is 1000 μC / cm ² or more, and the contrast (γ value) is 4.2. To 5.9. That is, the development treatment with an alkaline aqueous solution has higher resolution (higher resolution) but lower sensitivity (higher required exposure amount) than a developer (three types) made of an organic solvent.
On the other hand, in the case where the above-mentioned various organic solvents are used as developing solutions (three types), the exposure amount region in which the exposure portion residual film ratio becomes maximum and becomes saturated and stable is 100 μC / cm ² or less, but the contrast (γ value) ) Was 1.2 to 2.6. That is, in contrast to the case where an alkaline aqueous solution (3 types) is used as the developer, the development treatment with the organic solvent has an order of magnitude higher sensitivity (the required exposure amount is an order of magnitude lower), but a lower resolution (to the resolution). Inferior).
For convenience, the slope of the remaining film sensitivity curve between the remaining film rate of 20% and 80% is defined as contrast (γ value).

By the way, for example, the required exposure amount (sensitivity) of an electron beam resist commonly used in photomask manufacture is about 10 to 20 μC / cm ² (acceleration voltage 50 kV). If a resist having a higher necessary exposure amount (lower sensitivity) than this is used, the productivity of drawing simply decreases, and the manufacturing cost of the photomask increases.
On the other hand, as described above, when pattern formation of 20 nm or less is performed, if a developer composed of a resist layer made of HSQ and an alkaline aqueous solution is used, the necessary exposure (sensitivity) is 1000 μC / cm ² or more (acceleration voltage 100 kV). turn into.

Here, the relationship between the acceleration voltage of the electron beam lithography apparatus and the exposure amount is approximately proportional. A resist that can be patterned with an apparatus with an acceleration voltage of 50 kV and a required exposure amount of 20 μC / cm ² has a required exposure amount of about 40 μC / cm ² (approx. Approximately) with an apparatus with an acceleration voltage of 100 kV (when the acceleration voltage is doubled). Otherwise, the resist pattern cannot be formed. When a pattern of 20 nm or less is formed, the required exposure amount of the resist layer made of HSQ is 1000 μC / cm ² or more in an electron beam drawing apparatus with an acceleration voltage of 100 kV. Therefore, the ratio between the two is 25 times (1000/40) or more. It is clear that the required exposure amount of HSQ is remarkably large (sensitivity is remarkably low), and photomask production (including mold production) using a resist layer made of HSQ is not industrially feasible.

In addition, the resolution required for lithography technology is required to form a half pitch of 16 nm (16 nm LS pattern) in 2015 and a half pitch of 11 nm (11 nm LS pattern) in 2019 for semiconductor applications. Yes. Furthermore, in patterned media applications where finer pattern formation is required, a bit pitch of 18 nm bit pattern (9 nm diameter bit) was formed in 2015, and a bit pitch of 15 nm bit pattern (7.5 nm diameter bit in 2018). ) Is required.
In particular, in the nanoimprint method in which an uneven pattern on the mask surface is physically pressed to transfer the pattern, that is, in the nanoimprint method in which the same size pattern is transferred as compared with the reduction projection exposure method (reduction transfer to 1/4), a nanoimprint mask (mold, It is also necessary to form a very fine pattern of about 10 nm or less.

  However, as described above, although it is a resist layer made of HSQ that has been proven to have a resolution of 10 nm or less, a lower required exposure amount suitable for industrial mask manufacture (including manufacture of nanoimprint masks (molds)). There is no process method or pattern formation method that provides (high sensitivity).

  The object of the present invention has been made in consideration of the above-mentioned circumstances, and when forming a resist pattern, the resist layer having a predetermined composition has a reduced exposure (with higher sensitivity). ), Providing a resist pattern forming method that provides a desired high resolution, and a mold manufacturing method using the pattern forming method.

The first aspect of the present invention is:
A resist layer formed by applying a solution containing as a main component a compound having a composition that can be a solute of a solution using an organic solvent as a solvent and having a repeating chain of siloxane bonds (Si-O bonds) as a solvent. In addition, a resist pattern forming method of forming a resist pattern by irradiating with an energy beam and drawing or exposing, and thereafter developing processing,
A first heat treatment step of heat-treating a resist layer obtained by applying the resist on the substrate surface at a first heat treatment temperature;
A pattern drawing step of performing predetermined drawing or exposure on the resist layer formed through the first heat treatment step;
A first development processing step of developing the resist layer that has undergone the pattern drawing step with a first developer;
Then, a second heat treatment step of heat-treating the resist layer that has undergone the first development treatment step at a second heat treatment temperature;
Then, a second development processing step of developing the resist layer that has undergone the second heat treatment step with a second developer,
This is a resist pattern forming method.
The second aspect of the present invention is:
In the invention according to the first aspect,
The first heat treatment temperature is lower than the second heat treatment temperature.
It is characterized by that.
The third aspect of the present invention is:
In the invention according to the first or second aspect,
The first developer contains an organic solvent;
It is characterized by that.
The fourth aspect of the present invention is:
In the invention according to any one of the first to third aspects,
The second developer is an aqueous solution mainly composed of an alkaline aqueous solution.
It is characterized by that.
According to a fifth aspect of the present invention,
In the invention according to any one of the first to fourth aspects,
The second heat treatment temperature is lower than 350 ° C.,
It is characterized by that.
The sixth aspect of the present invention is:
In the invention according to the third aspect,
The organic solvent is a solvent of the solution used for forming the resist layer.
It is characterized by that.
The seventh aspect of the present invention is
In the invention according to the third or sixth aspect,
The organic solvent is methyl isobutyl ketone (MiBK).
It is characterized by that.
The eighth aspect of the present invention is
In the invention according to the third aspect,
The organic solvent is an organic solvent that maximizes the exposure area residual film ratio and minimizes the amount of exposure that is saturated and stabilized.
It is characterized by that.
The ninth aspect of the present invention provides
In the invention according to the eighth aspect,
The organic solvent is isopropanol (IPA).
It is characterized by that.
The tenth aspect of the present invention provides
In the invention according to any one of the first to ninth aspects,
The second developer has a higher dissolution rate of the compound (for example, HSQ) than the first developer.
It is characterized by that.
The eleventh aspect of the present invention is
In the invention according to the fourth aspect,
The second developer contains an aqueous tetramethylhydroammonium (TMAH) solution,
It is characterized by that.
The twelfth aspect of the present invention provides
In the invention according to the fourth aspect,
The second developer includes an aqueous solution obtained by adding sodium chloride (NaCl) to sodium hydroxide (NaOH).
It is characterized by that.
The thirteenth aspect of the present invention provides
In the invention according to any one of the first to twelfth aspects,
The solution containing the compound as a main component is a solution in which the compound has an organic functional group in a side chain and the organic solvent is a main solvent.
It is characterized by that.
The fourteenth aspect of the present invention provides
In the invention according to any one of the first to twelfth aspects,
The solution containing the compound as a main component is a solution in which the compound has an organic functional group in a side chain and MiBK is a main solvent.
It is characterized by that.
The fifteenth aspect of the present invention provides
In the invention according to any one of the first to fourteenth aspects,
In the first development processing step, a first development processing time by the first developer is determined according to a time at which dissolution of the resist layer after exposure is saturated.
It is characterized by that.
The sixteenth aspect of the present invention provides
In the invention according to any one of the first to fifteenth aspects,
In the second development processing step, the second development processing time by the second developer is determined according to the time when the dissolution of the resist layer after exposure is saturated.
A resist pattern forming method.
The seventeenth aspect of the present invention provides
A resist pattern is formed using the invention according to any one of the first to sixteenth aspects, the substrate is processed based on the resist pattern, and a concavo-convex pattern is formed on the substrate surface to produce a mold. ,
This is a method for producing a mold.
The eighteenth aspect of the present invention provides
A resist pattern is formed on the surface of the substrate using the invention according to any one of the first to sixteenth aspects, and a mold that uses the resist pattern as an uneven pattern is produced.
This is a method for producing a mold.

  According to the present invention, in order to form a pattern in a resist layer having a predetermined composition, high resolution can be achieved while suppressing a necessary energy irradiation amount (necessary exposure amount).

It is the example which showed the relationship between various developing solutions and the remaining film sensitivity curve (relationship between a remaining film rate and exposure amount) of the resist layer which consists of HSQ by the conventional resist pattern formation method. The developer is various organic solvents, a TAMH aqueous solution, or an aqueous solution obtained by adding NaCl (4%) to NaOH (1%). It is process schematic for demonstrating the resist pattern formation method which concerns on this embodiment, and a mold preparation method. It is a cross-sectional schematic diagram for demonstrating the process in the resist pattern formation method and mold preparation method which concern on this embodiment. 3 is a residual film sensitivity curve of an HSQ resist layer according to Example 1 and Comparative Example 1.

  For the resist layer having a predetermined composition (in this embodiment, a resist layer made of HSQ or a resist layer containing HSQ as a main component (hereinafter simply referred to as an HSQ resist layer)). Various means have been examined for providing a high resolution and a low required exposure (high sensitivity).

  In particular, the present inventors use the first developer in the first development processing step as an organic solvent in order to reduce the required exposure while maintaining a high resolution, and also in the second development processing step. The second developer has a composition in which the dissolution rate of the HSQ resist layer is larger than that of the first developer, and the second developer is the second developer after the first developer and before the second developer. It was found that a resist pattern having substantially the same resolution as that obtained when the second developing solution was used alone could be formed while suppressing the required exposure amount by including the heat treatment step.

<Embodiment>
Hereinafter, an embodiment of the present invention will be described based on FIG. 2 which is a schematic diagram for explaining steps of resist pattern formation and mold manufacturing and FIG. 3 which is a schematic sectional view.

(Substrate manufacturing process)
(Preparation of substrate)
First, the substrate 1 that will eventually become the mold 20 is prepared.
The substrate in the present embodiment is made of a metal such as quartz, sapphire, or Si, plastic, ceramic, or a combination thereof. Any material, structure or shape can be used as long as it can be used as the mold 20.

  In the present embodiment, description will be made using a substrate 1 made of wafer-shaped quartz. Hereinafter, the substrate 1 made of quartz having a wafer shape is simply referred to as a substrate 1.

(Formation of hard mask layer on substrate 1)
First, the substrate 1 (FIG. 3A) that has been appropriately polished and cleaned as necessary is introduced into a sputtering apparatus. In this embodiment, a target made of chromium (Cr) is sputtered with argon gas and nitrogen gas to form a hard mask layer 2 made of chromium nitride (FIG. 3B).

  Note that the hard mask layer 2 in the present embodiment is composed of a single layer or a plurality of layers, and the hard mask layer 2 in a portion corresponding to a groove (hereinafter referred to as a groove portion) of the resist pattern 7 described later is removed by etching. After that, it refers to a layer that acts as a mask material when the substrate 1 is etched to form a groove portion, and can protect portions other than the groove portion. Here, the hard mask layer 2 preferably has good adhesion to the HSQ resist layer 3. Further, if necessary, an adhesion auxiliary layer may be provided between the hard mask layer 2 and the resist layer 3. The hard mask layer 2 preferably has good etching selectivity with the HSQ resist layer 3. Further, the film thickness of the hard mask layer 2 at this time is preferably a thickness that remains until etching for forming a groove in the substrate 1 is completed.

(Resist application process)
In the present embodiment, the substrate 1 on which the hard mask layer 2 is formed is appropriately washed, and after performing dehydration baking before resist application or formation of an adhesion auxiliary layer as necessary for improving adhesion. As shown in FIG. 3C, an HSQ resist layer 3 is formed on the substrate 1 on which the hard mask layer 2 is formed.
In this embodiment, a resist solution containing HSQ using an organic solvent as a solvent is used, and after dropping the resist solution on the main surface of the substrate 1 on which the hard mask layer 2 is formed, the substrate 1 is attached at a predetermined rotational speed. A spin coating method in which the resist layer 3 is formed by rotating is used.

  The HSQ resist layer only needs to have reactivity when drawn or exposed by irradiation with an energy beam, and is a resist layer sensitive to ultraviolet rays, X-rays, electron beams, ion beams, proton beams, and the like. It may be. The HSQ resist layer may be any layer that is soluble in an organic solvent or can be formed as a solute of a solution using an organic solvent as a solvent.

  In the present embodiment, a case where electron beam drawing is performed will be described.

  At this time, a conductive agent for preventing charge-up may be applied on the resist layer 3.

  In addition, the thickness of the resist layer 3 at this time is preferably such a thickness that the resist layer 3 remains until etching of the hard mask layer 2 formed on the substrate 1 is completed. This is because etching to the hard mask layer 2 removes not only the portion corresponding to the resist dissolution portion formed in the resist layer 3 but also the resist layer 3 in the resist non-dissolution portion.

  In addition, when the substrate 1 can be etched to form a groove using a resist pattern as a mask material without the need for the hard mask layer 2, the resist layer 3 may be formed directly on the substrate 1. In this case, after the dehydration baking process or the adhesion auxiliary layer is formed on the substrate 1, the resist layer 3 is provided thereon.

(First heat treatment step)
Next, the substrate 1 on which the resist layer 3 is spin-coated on the hard mask layer 2 is subjected to a first heat treatment using, for example, a hot plate under predetermined first heat treatment conditions (temperature and time). . Then, it cooled and formed the resist layer 4 which passed 1st heat processing (FIG.3 (d)).
The first heat treatment temperature is desirably lower than the second heat treatment temperature described later.
In some cases, this heat treatment may not be performed.

(Pattern drawing process)
Next, using the electron beam drawing apparatus, a desired pattern is drawn and exposed on the resist layer 4 that has undergone the first heat treatment.
This fine pattern may be on the micron order, but may be on the nano order from the viewpoint of the performance of electronic devices in recent years, and this is preferable in view of the performance of the final product.
In the present embodiment, the HSQ resist layer 3 is a negative resist. That is, a case will be described in which a portion drawn with an electron beam becomes a non-dissolving portion with respect to the developer, and thus corresponds to a non-groove portion of the mold 20.

(First development processing step)
(First development processing)
After the desired fine pattern is drawn with an electron beam, as shown in FIG. 3E, the resist layer 4 is developed with a predetermined first developer, and the electron beam is not drawn on the resist layer 4. The first resist pattern 5 corresponding to a desired fine pattern is formed.

  Here, in the present embodiment, the drawn resist layer 4 is developed with a first developer containing an organic solvent. That is, the resist layer in the non-drawing portion is dissolved and removed (first development processing step).

  Here, the first developer used in the first development processing step is preferably a solvent of an HSQ resist solution.

Specifically, when the solvent of the HSQ resist solution is MiBK, MiBK is desirable.
By using MiBK, that is, the solvent of the HSQ resist solution, in the first developer, the exposure amount at which the exposed portion residual film ratio becomes maximum and becomes saturated and stable, the portion drawn / exposed below the exposure amount, and completely The residual film ratio of the part not drawn / exposed is minimized, and the development residue can be minimized.

FIG. 1 shows the results of determining the residual film sensitivity curve (relationship between the residual film ratio and the electron beam exposure amount) of the HSQ resist layer using various organic solvents (3 types) as a developing solution. As shown in FIG. 1, when the temperature and time of the heat treatment after application of the HSQ resist solution are fixed (in this case, no heat treatment is performed), a low exposure region (for example, FIG. The remaining film ratio in the region of 1 in which the exposure amount is 10 μC / cm ² or less was the smallest as compared with the case where the other organic solvent was used as the first developer.

  In addition, a portion (non-drawing portion) other than the portion (desired drawing portion) on which the electron beam is drawn is actually slightly exposed due to backscattering, forward scattering and fogging caused by electron beam drawing. And remains as a residue after the first development processing step. Therefore, if the solvent of the HSQ resist solution is the first developer used in the first development processing step, the residue can be minimized.

  In addition, the first developer used in the first development processing step is an organic solvent in which the exposure amount at which the exposure portion residual film ratio becomes maximum and becomes saturated and stable is minimized as compared with other organic solvents. desirable. By using such an organic solvent as the first developer, it is possible to minimize the exposure amount substantially necessary for forming the resist pattern.

  More specifically, the first developer is preferably IPA. As shown in FIG. 1, when IPA is used as a developer, the HSQ resist layer has the highest sensitivity (low required exposure amount), more specifically, compared to the case where another organic solvent is used as a developer. The exposure amount at which the exposure portion residual film ratio becomes maximum and becomes saturated and stable shows a minimum value.

Specific examples of the development process for the resist layer 4 include the following methods.
That is, the hard mask layer 2 and the resist layer 3 are provided, and the substrate 1 on which a desired pattern is drawn (exposed) with respect to the resist layer 4 that has undergone the first heat treatment is rotated at a predetermined rotational speed. Then, a first developer containing the organic solvent is dropped from above the substrate 1 to the substrate 1. At this time, the first developer may be at room temperature or may be maintained at a predetermined temperature. During the dropping of the first developer, dissolution of the resist dissolving portion by the first developer occurs.
In addition, even after the dissolution of the resist dissolving portion is completed, the first developer containing the resist melt is kept on the substrate 1 by continuously dropping the first developer excessively while rotating the substrate 1. It flows down from the outer edge of the substrate due to the centrifugal force caused by the rotation. Further, by continuing to dripping the first developer excessively while rotating the substrate 1, the first developer containing the resist solution is replaced with the first developer containing no resist solution. A clean first resist pattern 5 is formed.

(Developer for the first development process)
In this embodiment, only a single organic solvent is used as the first developer in the first development processing step, but a plurality of organic solvents may be mixed. Further, it is sufficient that the dissolution rate in the HSQ resist layer is small as compared with the second developer used in the second developing process described later.

(First development processing time)
Further, the development processing time by the first developer in the first development processing step is determined in advance so that the dissolution of the non-drawing (exposure) portion or the drawing portion (exposure portion) is saturated and does not proceed any further. This is the first development processing time. This is to minimize the residue generated in the non-drawing part in the first development processing step.

(rinse)
After the predetermined first developing process, a rinsing process may be performed by supplying a rinsing solution dropwise to wash away the first developing solution.
It is preferable that the dropping supply of the rinse liquid is performed immediately before stopping the dropping supply of the first developer, and is continued even after the dropping supply of the first developer is stopped. By doing so, it is possible to prevent the first developing solution from being gradually replaced with the rinsing solution, and the resist melt remaining in the developing solution staying on the substrate to be precipitated again and become dirty.
Further, it is desirable that this rinsing solution is mixed with the first developer, and further, it is desirable that the rinse solution is also mixed with the second developer used in the second developing process described later.
Furthermore, it is desirable that the rinsing solution has a lower dissolution rate in the HSQ resist layer than the first and second developing solutions. Since the dissolution rate is relatively low, the quality of the HSQ resist pattern can be maintained high without causing unnecessary dissolution of the HSQ resist pattern after the first development processing.

(Dry)
A drying process is performed on the substrate 1 that has been subjected to the rinsing process and the substrate 1 that has been subjected to only the first development process without being subjected to the rinsing process. This drying process is performed by rotating the substrate 1 at a predetermined rotational speed after stopping the dripping supply of the rinse agent after performing the rinse process. As a result, the rinse agent flows down from the outer edge of the substrate due to centrifugal force or evaporates. Thus, the substrate 1 with the hard mask layer 2 on which the resist pattern 5 composed of the desired resist-dissolved portion and the resist non-dissolved portion is formed is obtained.

(Second heat treatment step)
Next, the substrate 1 on which the resist pattern 5 is formed is subjected to heat treatment at a predetermined temperature and time using, for example, a hot plate. Then, it cooled and formed the resist pattern 6 which passed 2nd heat processing (FIG.3 (f)).
The second heat treatment temperature is preferably higher than the first heat treatment temperature. By this second heat treatment, the dissolution rate of the resist pattern 5, particularly the originally desired drawing portion in the resist pattern 5, with respect to the second developer described later is reduced, so that higher sensitivity (low required exposure amount) is obtained. ) And a resist pattern 7 having a shape close to the originally desired resist pattern 7, that is, a high contrast resist pattern 7 is finally obtained.
The second heat treatment temperature is desirably less than 350 ° C. This is because if the heat treatment is performed at a temperature higher than 350 ° C., the HSQ resist pattern 6 or the HSQ resist pattern 7 has a higher risk of cracking during the second heat treatment or in the next second development treatment.

(Second development processing step)
(Second development process)
After the second heat treatment, the formed resist pattern 6 is developed with a predetermined second developer, and the residue is removed to form the originally desired resist pattern 7. That is, in addition to the originally desired electron beam drawing (exposure) portion, a portion of the electron beam drawn with a relatively low exposure amount by forward scattering, back scattering, and fogging of the drawing electron beam, The solution is removed with a developer.

  Here, in the present embodiment, the resist pattern 5 formed through the first development treatment with the second developer containing the alkaline aqueous solution is subjected to the second heat treatment (resist pattern 6). Development is performed again (second development process), that is, an excessive drawing portion (resist layer) is dissolved and removed to form the originally desired resist pattern 7.

As a specific method of the second development treatment with the second developer for the resist pattern 6, for example, the following method may be mentioned.
That is, the substrate 1 (FIG. 3 (f)), which has reached the normal temperature or a predetermined temperature through the second heat treatment and has stabilized, is rotated at a predetermined rotational speed. Then, a second developer containing the alkaline aqueous solution is supplied dropwise from above the substrate 1 to the substrate 1 (FIG. 3F). At this time, the second developer may be at room temperature or may be maintained at a predetermined temperature. During the dropping of the second developer, the excessively exposed portion is dissolved and removed by the second developer.
In addition, even after the dissolution of the excessively exposed portion is completed, the second developer containing the resist solution is obtained by continuing to dripping the second developer excessively while rotating the substrate 1. Due to the centrifugal force generated by the rotation of the substrate 1, it flows down from the outer edge of the substrate. Further, by continuing to dripping the second developer excessively while rotating the substrate 1, the second developer containing the resist solution is replaced with the second developer containing no resist solution. A clean resist pattern is formed.

(Developer for the second development process)
In the present embodiment, the single aqueous alkali solution is used as the second developer in the second development processing step, but a plurality of alkaline substances may be mixed. Further, NaCl may be added.
In addition, it is desirable that the second developer has a higher dissolution rate in the HSQ resist layer than the first developer used in the first development process described above.

(Second development processing time)
Note that the development processing time with the second developer in the second development processing step is determined in advance so that the dissolution of the non-drawing (exposure) portion or the drawing portion (exposure portion) is saturated and does not proceed further. This is the second development processing time.
This is for minimizing the residue of the non-drawing portion generated in the first development process in the second development process.

(rinse)
After the predetermined second developing process, a rinsing process may be performed by supplying a rinsing liquid dropwise from above the substrate 1 while rotating the substrate 1 in order to wash away the second developing solution.
It is preferable that the dropping supply of the rinse liquid is performed before stopping the dropping supply of the second developer and is continued even after the dropping supply of the second developer is stopped. By doing so, it is possible to prevent the second developing solution from being gradually replaced with the rinsing solution, and the resist melt remaining in the developing solution staying on the substrate to be deposited again and become dirty.
Further, it is desirable that this rinse liquid is mixed with the second developer.
Furthermore, it is desirable that this rinsing solution has a lower dissolution rate with respect to the HSQ resist layer than the second developing solution. Since the dissolution rate is relatively low, the quality of the HSQ resist pattern can be maintained high without causing dissolution of the HSQ resist pattern after unnecessary development processing.
In order to prevent the resist pattern from collapsing (pattern collapse) in the subsequent drying step, the rinse solution may be IPA or water to which a surfactant is added. Alternatively, after rinsing with IPA, rinsing may be performed using a fluorinated solvent. By using a developer having a smaller surface tension, the resist pattern collapse (pattern collapse) in the subsequent drying process is further prevented.

(Dry)
A drying process is performed on the substrate 1 subjected to the rinsing process. This drying process is performed by rotating the substrate 1 at a predetermined rotational speed after stopping the dripping supply of the rinse agent after performing the rinse process. As a result, the rinse agent flows down from the outer edge of the substrate due to centrifugal force or evaporates. In this way, the substrate 1 with the hard mask layer 2 on which the resist pattern 7 composed of the desired resist dissolved portion and the resist non-dissolved portion is formed is obtained.
It is to be noted that, in order to remove the developer or rinse agent remaining in the formed resist pattern 7 and to improve the adhesion between the resist pattern 7 and the hard mask layer 2, drying is performed as necessary. You may heat-process following a process.

(Substrate etching process)
(Descum of resist pattern 7: first etching)
Thereafter, the substrate 1 with the hard mask layer 2 on which the resist pattern 7 is formed (FIG. 3G) is introduced into a dry etching apparatus. Then, for example, first etching with a fluorine-based gas such as CF ₄ is performed to remove the residue (scum) of the resist dissolution portion. Here, helium (He) or argon (Ar) gas may be added to the fluorine-based gas.

(Etching of hard mask layer 2: second etching)
Subsequently, after exhausting the gas used in the first etching, dry etching is performed with a mixed gas composed of chlorine gas and oxygen gas, and the hard mask layer 2 exposed by the development process and the first etching process is removed. Remove.
Thus, as shown in FIG. 3 (h), a groove corresponding to the resist pattern 7 is applied to the hard mask layer 2 on the substrate 1 (hard mask pattern 8).
The etching end point at this time is determined by using, for example, a reflection optical end point detector.

(Etching substrate 1: third etching)
Subsequently, after exhausting the gas used in the second etching, a third etching using a fluorine-based gas is performed on the substrate 1.

  Thus, as shown in FIG. 3I, the substrate 1 is subjected to groove processing corresponding to the resist pattern 7 and the hard mask pattern 8, and the remaining portions of the hard mask pattern 8 and the resist pattern 7 remaining except the groove portions are removed. The mold 9 before being produced is produced.

As the fluorine-based gas used in the first etching and the third etching, C _x F _y (for example, CF ₄ , C ₂ F ₆ , C ₃ F ₈ ), CHF ₃ , a mixed gas thereof, or These include those containing noble gases (He, Ar, Xe, etc.) as additive gases. Note that in the first etching and the third etching, wet etching using hydrofluoric acid may be performed when a pattern to be formed is on the micro order.

(Removal of resist pattern 7 and hard mask pattern 8: fourth etching)
Subsequently, the remaining hard mask pattern 8 and resist pattern 7 remaining after the third etching are removed. Here, a chemical solution capable of dissolving and removing the hard mask pattern 8 containing chromium (Cr) as a main component is used, and wet etching is performed to remove the remaining of the hard mask pattern 8 and the resist pattern 7 remaining thereon.

(Mold completed)
After the above steps, the substrate 1 is cleaned if necessary. In this way, a master mold 20 as shown in FIG.

In the present embodiment as described above, the following effects can be obtained.
That is, in order to form a pattern on a resist layer having a predetermined composition, a high resolution can be achieved while suppressing a necessary energy irradiation amount (necessary exposure amount).

In the present embodiment, the substrate surface is a solution containing as a main component a compound having a composition that can be a solute of a solution containing an organic solvent as a solvent, and having a repeating siloxane bond (Si—O bond) as a main chain. Although the resist layer formed by coating on the substrate has been described, it is presumed that the technical idea of the present invention is not limited to this type of resist. The resist is not particularly limited as long as it has reactivity when drawn or exposed by irradiation with an energy beam, and may be a resist having sensitivity to ultraviolet rays, X-rays, electron beams, ion beams, proton beams, and the like. Good.
That is, it is estimated that the first developer and the second developer for the resist can be set each time depending on the type of resist. In addition, even when the organic solvent and the alkaline aqueous solution mentioned in the present embodiment are not used, another type of compound is used as the first developer, and a compound having a higher resist solubility than the first developer is used. If so, there is a possibility that the effects described in the present embodiment are produced.
The technical idea of the present invention has been intensively studied by the inventors.

  Moreover, the resist pattern formation method and mold preparation method in the said embodiment are applicable to the following uses besides mold preparation. For example, photomasks for semiconductor devices, semiconductor manufacturing, microelectromechanical systems (MEMS), sensor elements, optical disks, optical components such as diffraction gratings and polarizing elements, nanodevices, organic transistors, color filters, overcoat layers, microlens arrays It can also be widely applied to the production of immunoassay chips, DNA separation chips, microreactors, nanobiodevices, optical waveguides, optical filters, photonic liquid crystals, and the like.

  As mentioned above, although embodiment which concerns on this invention was mentioned, said disclosure content shows exemplary embodiment of this invention. The scope of the present invention is not limited to the exemplary embodiments described above. Whether or not explicitly described or suggested herein, those skilled in the art will make various modifications to the embodiments of the present invention based on the disclosure of the present specification. Can be implemented.

  Next, an Example is shown and this invention is demonstrated concretely. Of course, the present invention is not limited to the following examples.

<Example 1>
In this example, a wafer-shaped synthetic quartz substrate (outer diameter 150 mm, thickness 0.7 mm) was used as the substrate 1 (FIG. 3A).
First, the substrate 1 was introduced into a sputtering apparatus, and a target made of chromium (Cr) was sputtered with argon gas and nitrogen gas to form a hard mask layer 2 made of chromium nitride having a thickness of 2 nm (FIG. 3B). )). The substrate 1 on which the hard mask layer 2 was formed was baked on a hot plate at 200 ° C. for 10 minutes to perform a dehydration baking process. Thereafter, the substrate 1 was placed on the cooling plate, and the substrate 1 was cooled.

  Next, the substrate 1 on which the hard mask layer 2 was formed was set in a resist spin coater. Then, a 6% solution of XR-1541 (manufactured by Dow Corning), which is an HSQ resist solution using MiBK as a solvent, was prepared in advance. About 3 ml of this resist solution was dropped on the substrate 1, and then the substrate 1 was rotated at 800 rpm for 60 seconds to obtain a resist layer 3 (FIG. 3C).

  After spin coating of the resist solution, the substrate 1 on which the resist layer 3 is formed is subjected to a first heat treatment at 300 ° C. for 15 minutes on a hot plate to remove unnecessary residual solvent in the formed resist layer. Thus, an HSQ resist layer 4 having a thickness of about 200 nm was obtained (FIG. 3D).

  Then, using a point beam type electron beam drawing machine with an acceleration voltage of 100 kV, a square pattern with a side of 50 μm was drawn with increasing exposure amount.

  After the pattern drawing, the resist layer 4 of the substrate 1 was developed with the first developer according to this example. Specifically, MiBK was used as the first developer.

  During the first development process, the substrate 1 was kept rotating at 250 rpm. Then, the first developer was dropped from above the substrate 1 for 60 seconds. At this time, the developer was kept at room temperature (22.5 ° C.).

  Then, after finishing the first developing process with the first developer, that is, after stopping the dropping of the first developer, the substrate 1 was appropriately rotated at 1500 rpm to perform a drying process.

  Next, after the first development process, the substrate 1 on which the resist pattern 5 was formed was subjected to a second heat treatment at 325 ° C. for 15 minutes on a hot plate to obtain a resist pattern 6 (see FIG. 3 (f)).

  Next, a second development process was performed with the second developer according to this example. As the second developer, an aqueous solution in which 4% NaCl was added to 1% NaOH was used.

  During the second development process, the substrate 1 on which the resist pattern 6 was formed was continuously rotated at 250 rpm. Then, the second developer was dropped from above the substrate 1 for 300 seconds. At this time, the developer was kept at room temperature (22.5 ° C.).

After passing through the predetermined second developing process, pure water was dropped as a rinse liquid from above the substrate 1 while rotating the substrate 1 to perform a rinsing process.
Specifically, after performing the second development process with the second developer for 300 seconds, a rinse liquid composed of the second developer and pure water is supplied to the substrate 1 for 5 seconds, and then the first The supply of the developer was stopped, and only the supply of the rinse solution was continued for 30 seconds.
Then, after performing a rinsing treatment with the rinsing liquid composed of the pure water for 30 seconds, IPA is also used as the rinsing liquid, and the rinsing liquid composed of pure water and the rinsing liquid composed of IPA are simultaneously supplied to the substrate 1 for 5 seconds. Thereafter, the supply of the rinse liquid composed of pure water was stopped, and the supply of the rinse liquid composed of the IPA was continued for 15 seconds. Thereafter, the supply of the rinse solution composed of the IPA was stopped.

  Next, a drying process was performed on the substrate 1 subjected to the rinsing process. In this drying treatment, after the rinse treatment was performed, the dropping supply of the rinse liquid was stopped, and then the substrate 1 was appropriately rotated at 1500 rpm to perform the drying treatment. Thus, a sample according to the example, that is, the substrate 1 with the hard mask layer 2 (FIG. 3G) on which the resist pattern 7 including a desired resist-dissolved portion and a resist non-dissolved portion was formed was obtained.

  Thereafter, the film thickness of the resist pattern 7 formed on the substrate 1 after finishing the second development process is measured with a spectral reflection type resist film thickness meter, and the first development measured in advance in the same manner. With reference to the film thickness of the resist layer 4 before processing, a residual film sensitivity curve after the second development processing was obtained. That is, the relationship between the remaining film rate and the electron beam exposure amount was obtained (FIG. 4).

<Comparative Example 1>
In Comparative Example 1, the development processing after pattern drawing was performed using the second developer, that is, an aqueous solution obtained by adding NaCl (4%) to NaOH (1%). Further, the film thickness of the resist layer was measured with a spectral reflection type resist film thickness meter, and a residual film sensitivity curve was obtained in the same manner as in Example 1.
A sample was prepared in the same manner as in Example 1 except for this.

<Evaluation>
FIG. 4 shows the residual film sensitivity curve of the HSQ resist layer after the second development process of the example and the residual film sensitivity curve of the HSQ resist layer after the development process of Comparative Example 1.

From the residual film sensitivity curve of Comparative Example 1, the necessary exposure amount for obtaining a residual film ratio of 50% is about 2250 C / cm ² and the contrast (γ value) is about 5.9.
On the other hand, from the residual film sensitivity curve of Example 1, the necessary exposure amount for obtaining a residual film ratio of 50% is about 605 μC / cm ² , and the contrast (γ value) is about 5.2, which is almost the same as that of Comparative Example 1. there were.
From the above comparison, when the resist pattern is formed in accordance with the embodiment of the present invention, that is, the result of Example 1 shows that the required exposure amount is about 27% while maintaining the contrast value as compared with Comparative Example 1. Can be reduced (high sensitivity). That is, the required exposure amount was reduced by about 73%.

DESCRIPTION OF SYMBOLS 1 Substrate 2 Hard mask layer 3 HSQ resist layer 4 after application Resist layer 5 after first heat treatment step 5 Resist pattern after first development treatment step
6 Resist pattern 7 after second heat treatment step 7 Resist pattern 8 after second development treatment step 8 Hard mask pattern 9 Residual hard mask pattern and mold 20 before resist pattern removal Mold

Claims (18)

Irradiate an energy beam to a resist layer formed by applying a solution containing as a main component a compound having a composition that can be a solute of a solution using an organic solvent as a solvent and repeating siloxane bonds as the main chain. A resist pattern forming method of drawing or exposing and then developing to form a resist pattern,
A first heat treatment step of heat-treating the resist layer formed by applying the solution on the substrate surface at a first heat treatment temperature;
A pattern drawing step of performing predetermined drawing or exposure on the resist layer formed through the first heat treatment step;
A first development processing step of developing the resist layer that has undergone the pattern drawing step with a first developer;
Then, a second heat treatment step of heat-treating the resist layer that has undergone the first development treatment step at a second heat treatment temperature;
Then, a second development processing step of developing the resist layer that has undergone the second heat treatment step with a second developer,
A resist pattern forming method. In the resist pattern formation method of Claim 1,
The first heat treatment temperature is lower than the second heat treatment temperature.
A resist pattern forming method. In the resist pattern formation method of Claim 1 or 2,
The first developer contains an organic solvent;
A resist pattern forming method. In the resist pattern formation method in any one of Claim 1 to 3,
The second developer is an aqueous solution mainly composed of an alkaline aqueous solution.
A resist pattern forming method. In the resist pattern formation method in any one of Claim 1 to 4,
The second heat treatment temperature is lower than 350 ° C.,
A resist pattern forming method. In the resist pattern formation method of Claim 3,
The organic solvent is a solvent of the solution used for forming the resist layer.
A resist pattern forming method. In the resist pattern formation method of Claim 3 or 6,
The organic solvent is methyl isobutyl ketone,
A resist pattern forming method. In the resist pattern formation method of Claim 3,
The organic solvent is an organic solvent that minimizes the amount of exposure that is saturated and stable with the maximum exposed area remaining film ratio,
A resist pattern forming method. In the resist pattern formation method of Claim 8,
The organic solvent is isopropanol;
A resist pattern forming method. In the resist pattern formation method in any one of Claim 1 to 9,
The second developer has a higher dissolution rate of the compound than the first developer.
A resist pattern forming method. In the resist pattern formation method of Claim 4,
The second developer contains an aqueous tetramethylhydroammonium solution.
A resist pattern forming method. In the resist pattern formation method of Claim 4,
The second developer includes an aqueous solution obtained by adding sodium chloride to sodium hydroxide.
A resist pattern forming method. In the resist pattern formation method in any one of Claim 1 to 12,
The solution containing the compound as a main component is a solution in which the compound has an organic functional group in a side chain and the organic solvent is a main solvent.
A resist pattern forming method. In the resist pattern formation method in any one of Claim 1 to 12,
The solution containing the compound as a main component is a solution in which the compound has an organic functional group in a side chain and methyl isobutyl ketone is a main solvent.
A resist pattern forming method. In the resist pattern formation method in any one of Claim 1 to 14,
In the first development processing step, a first development processing time by the first developer is determined according to a time at which dissolution of the resist layer after exposure is saturated.
A resist pattern forming method. In the resist pattern formation method in any one of Claim 1 to 15,
In the second development processing step, the second development processing time by the second developer is determined according to the time when the dissolution of the resist layer after exposure is saturated.
A resist pattern forming method. A resist pattern is formed using the resist pattern forming method according to claim 1, a substrate is processed based on the resist pattern, and a concavo-convex pattern is formed on the substrate surface to produce a mold. To
A method for producing a mold characterized by the above. A resist pattern is formed on the surface of the substrate using the resist pattern forming method according to any one of claims 1 to 16, and a mold that uses the resist pattern as an uneven pattern is produced.
A method for producing a mold characterized by the above.

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