JPH05136033A - Pattern forming method and device thereof - Google Patents

Abstract

PURPOSE:To provide the pattern forming method and device thereof capable of lessening the proximity effect easily without performing any complicated computer processing step. CONSTITUTION:After irradiating negative type electron beam resist 2 on a substrate 1 with energy beams (electron beams 3), the whole body is once developed to form patterns. Later, the whole surface is coated with the negative type electron beam resist again and then irradiated with the electron beams 3' again to form the patterns. These steps are repeated using the patterns. Through these procedures, the accumulated energy in the resist can be effectively dissipated thereby enabling the proximity effect to be minimized without performing any complicated computer processing step.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pattern forming method and a pattern forming apparatus for realizing the same, and more particularly to a pattern forming method and a pattern forming apparatus for reducing the proximity effect without performing complicated computer processing.

[0002]

2. Description of the Related Art With the progress of integration of semiconductor devices, there is an increasing demand for fine processing. As the size of each pattern to be resolved becomes finer, the density of the pattern also increases. That is, the distance between patterns tends to become shorter and shorter. Conventionally, when forming a pattern (for example, a wiring pattern), first, a resist material sensitive to an energy ray (for example, visible light or an electron beam) is selectively irradiated with an energy ray and then developed to form a resist pattern. It was necessary to do. Generally, a resist pattern is formed with a threshold of accumulated energy as a boundary.
Here, in pattern formation after development, in order to improve dimensional controllability, it is important that the intensity ratio of the energy accumulated in the resist, that is, the so-called contrast, is clear.

By the way, when the pattern density is increased as described above, the following problems have come to occur. When selectively irradiating the resist with energy rays, energy particles (photons and electrons) are diffracted and scattered in the resist, and the region between the patterns is effectively irradiated and energy is accumulated. For this reason, the above-mentioned contrast of stored energy becomes unclear. This phenomenon, generally called the proximity effect, is a very important issue in the future of integration.

For example, in the case of an electron beam, it is known that when a certain point is irradiated with the electron beam, the amount of energy accumulated in the resist has a spread as shown in FIG. Here, the horizontal axis is the distance from the point irradiated with the electron beam, and the vertical axis is the energy storage amount in the resist at a certain depth. As described above, it is known that the energy storage amount becomes a function of the distance from the irradiation point and approximately takes the form of superposition of two Gaussian distributions. Of these, a portion with a small spread is a portion where electrons are scattered in the resist and is called forward scattering, and a portion with a large spread is a portion where electrons are scattered from the underlying substrate and is called back scattering. The former has a high level but a narrow distribution, while the latter has a low level but a wide distribution.

Therefore, in general, when the electron beam is irradiated in an arbitrary shape, effective energy accumulation also occurs in the portion between the patterns as shown in FIG. If the proximity effect is not corrected here, the desired pattern cannot be resolved. Up to now, the irradiation pattern has been mainly corrected by computer processing as a method for reducing the proximity effect. For example, Journal of Applied Physics Volume 50 (1979)
Year 4317 to 4377 (J. Appl. Phys. 5
0 , 4371-4377 (1979)., There is a method of calculating the energy storage amount in the resist caused by electron beam irradiation over the entire irradiation region. This is a concept in which the amount of electron beam irradiation and the irradiation region are corrected by numerical calculation so that the energy is optimally stored for the formation of a target pattern.

[0006]

However, in the above-mentioned prior art, it is necessary to perform calculation over the entire electron beam irradiation area, and when the pattern becomes complicated, the calculation becomes complicated and it is difficult to correct. there were.

It is an object of the present invention to provide a proximity effect correction method and an apparatus for forming a pattern which is easier than the prior art.

[0008]

SUMMARY OF THE INVENTION The above problem is that a material, such as a resist, having sensitivity to energy rays, which is placed on a substrate, is subjected to a developing treatment after selectively irradiating the material with energy rays. In the pattern formation method to obtain,
It is realized by selectively irradiating the energy beam a plurality of times and performing a step of reducing the pattern forming reaction in the region other than the pattern forming portion during the plurality of times of irradiation.

Further, when a material having sensitivity to energy rays installed on a substrate is selectively irradiated with energy rays and then development processing is performed to form a pattern, a pattern of energy rays is selectively applied. To irradiate
A processing device for performing a step of reducing a pattern forming reaction in a region other than the pattern forming portion is integrated, and by using a pattern forming device in which a substrate is transferred between the devices by a transfer system, it is possible to efficiently A pattern can be formed.

[0010]

Here, the case where an electron beam is used as an energy beam for forming a pattern will be described as an example.

For simplicity, the target pattern is a dot,
Consider a one-dimensional array of dots as an example. Regarding the energy storage amount, the case at the interface between the resist and the base substrate may be taken into consideration. The energy storage at a point is the sum of the energy storage obtained by the surrounding irradiation. Therefore, as shown in FIG. 4, when the interval between dots is wide, the amount of energy stored in the resist at the point A between the dots is small in total because only low-level backscattering contributes. That is, the influence of the proximity effect can be almost ignored. However, as shown in FIG. 5, when the interval between dots becomes narrower, the amount of energy accumulated in the resist at the point A between the dots is largely contributed by high-level forward scattering from the adjacent irradiation points, In addition, the influence of backscattering also increases, the total amount of energy stored is large, and the influence of the proximity effect is large.

Therefore, in order to effectively reduce the proximity effect, the following is considered. The proximity effect is caused by irradiating the same resist at once. Therefore, in order to have the same arrangement as in FIG. 5, the electron beam is irradiated a plurality of times by dividing as shown in FIGS. 6 (a) and 6 (b). Then, the pattern formation reaction in the region other than the pattern formation portion may be reduced during each irradiation. For example, if the irradiations in FIGS. 6A and 6B are made of different resists, the contribution of electron scattering from the adjacent portion is suppressed as compared with the case of one irradiation. Therefore, in FIG.
The stored energy amount at the same point B can be reduced as compared with A in the figure. In this way, irradiation can be performed with the proximity effect suppressed.

To actually irradiate the electron beam a plurality of times, the following procedure may be performed. First, the irradiation shown in FIG. 6A is performed, and a pattern is formed here by development processing or the like as shown in FIG. 7A. After that, a resist is again set on the substrate by coating or the like, and a pattern corresponding to FIG. 6B is irradiated as shown in FIG. 7B. After that, a pattern as shown in FIG. 7C is obtained by development processing or the like. Here, when the resist is set again on the resist on which the pattern is once formed, the pattern shape may be deteriorated. However, if gelation of the formed pattern portion is sufficiently advanced, deterioration of the pattern is suppressed. In this way, it is possible to effectively suppress the proximity effect without requiring complicated computer processing.

Further, in reducing the pattern forming reaction in the area other than the pattern forming portion during each irradiation, the concentration of the substance which becomes the element of the pattern forming reaction may be reduced.

[0015]

The present invention will be described in detail below with reference to examples.

(Embodiment 1) In this embodiment, a case of using an electron beam will be described with reference to FIG.

A negative electron beam resist 2 was applied on a substrate 1 made of silicon or the like. Here, it is desirable that gelation occurs at a low electron beam dose. Here, for example, a chemically amplified resist (trade name: SAL601-ER7, Shipley)
Was spin coated to a thickness of 0.3 μm. As shown in FIG. 1A, the first electron beam 3 was irradiated to form a latent image 4 having a 0.1 μm pattern. Here, the electron beam dose is 10μ
It is C / cm ² . Then, after performing hot plate baking at 110 ° C. for 2 minutes, static development was performed for 3 minutes with a dedicated developing solution (usually tetramethyl hydroxide (TMAH) solution) to give a pitch of 0.3 μm as shown in FIG. 1 (b). A dot pattern having a diameter of 0.1 μm was obtained.

After that, the negative electron beam resist 2'is again formed.
Was spin coated to a thickness of 0.3 μm. And Fig. 1 (c)
Irradiate the second electron beam 3'as shown in
An m pattern of latent image 4'was formed. Here, the electron beam irradiation amount is 10 μC / cm ² . Then, after hot plate baking at 110 ° C. for 2 minutes, static development was carried out for 3 minutes with a dedicated developer to obtain a dot pattern having a pitch of 0.15 μm and a diameter of 0.1 μm as shown in FIG. 1 (d). .. The pattern obtained here cannot be obtained by the single drawing until now due to the proximity effect. The dimensional accuracy of the finished pattern was also high.
Regarding the positional relationship between the first irradiation and the second irradiation, the positional accuracy of both is improved by using the alignment mark pattern formed on the substrate 1. That is, a mark pattern is irradiated with an electron beam, and secondary electrons or reflected electrons emitted from the mark pattern are detected to accurately determine the position to be irradiated with the pattern.

Here, the electron beam dose is 10 μC / cm ²
However, it goes without saying that it is not limited to this. Similar results were obtained with a positive electron beam resist such as PMMA (polymethylmethacrylate). Further, there is a correlation between the size of the pattern and the film thickness of the resist, and in order to obtain a finer pattern, the film thickness of the resist may be reduced. The film thickness of the resist is 0.3 μm this time, but it is not limited to this.

In this embodiment, the negative type resist or the positive type resist is applied a plurality of times, but a combination of the negative type resist and the positive type resist may be used for the resist applied a plurality of times depending on the irradiation pattern. it can.

(Embodiment 2) In the above-mentioned embodiment, the electron beam irradiation is performed a plurality of times by dividing it into two, but the number of divisions can be increased depending on the density of the pattern. By increasing the number of divisions to three, a dot pattern having a pitch of 0.12 μm and a diameter of 0.1 μm was obtained. By further increasing the number of divisions, it has become possible to easily form higher density patterns.

(Embodiment 3) Depending on the resist material, there is a resist called a chemically amplified resist that forms a substance that serves as a catalyst for accelerating the pattern reaction upon irradiation with an electron beam when forming a pattern. Here, for example, a negative resist (trade name: SAL601-ER7, Shipley Company) is taken as an example. This resist generates hydrogen ions (protons) when irradiated with an electron beam. By the baking after the electron beam irradiation, the cross-linking material contained in the resist reacts and the resin is polymerized to form a pattern. At this time, hydrogen ions act as a catalyst for the crosslinking reaction. That is, since hydrogen ions are selectively generated in the area irradiated with the electron beam,
A negative pattern is formed because the crosslinking reaction of the resin proceeds at that portion. Here, since the area other than the pattern forming portion is effectively irradiated with the electron beam, a small amount of hydrogen ions corresponding to the electron beam irradiation amount are also generated in that area, which causes the proximity effect.

Therefore, if the electron beam irradiation is performed a plurality of times as in the above-described embodiment and the concentration of hydrogen ions generated in the region other than the pattern forming portion is reduced during each irradiation, the electron beam irradiation after the electron beam irradiation is performed. Since the crosslinking reaction during baking is suppressed, the proximity effect can be reduced.

Here, a method for chemically reducing the hydrogen ion concentration will be described. Usually, the developer is a dilute alkaline solution of tetramethyl hydroxide (TMAH).
(About 2%) is used. Here, the whole substrate is immersed in an ultrathin diluted solution of TMAH before baking after electron beam irradiation. Here, since the TMAH solution concentration is lower than the concentration for pattern formation, it does not dissolve the resist but simply penetrates into the resist. Since TMAH contains hydroxide ions, it combines with hydrogen ions to generate water (H ₂ O). Therefore, the hydrogen ion concentration in the resist is lowered as a whole.

At this time, since the pattern forming portion has a large electron beam irradiation amount, the hydrogen ion concentration originally present is high, and the reduction of the hydrogen ion concentration in the pattern formation is less effective.
However, since the concentration of the generated hydrogen ions is originally low in the area other than the pattern formation portion, the effect of this treatment is large and sufficient for suppressing the proximity effect.

A detailed description will be given with reference to FIG. Figure 8 (a)
Chemically amplified resist 9 on substrate 1 such as silicon
Was spin coated to a thickness of 0.3 μm, then 0.1 μm
Irradiation with the first electron beam 3 for pattern formation is performed.
Here, the electron beam irradiation amount is 10 μC / cm ² . This electron beam irradiation causes a large amount of hydrogen ions 10 in the pattern formation area.
On the other hand, a small amount of hydrogen ions 10 are also generated in the area other than the pattern forming portion due to the scattering of the electron beam. After that, the whole substrate was diluted with 0.01% TMAH solution.
Soak for 0 minutes. As a result, the hydrogen ion concentration of the entire resist was lowered as shown in FIG. 8 (b).

After that, as shown in FIG. 8 (c), 0.1 μm
Irradiation with a second electron beam 3'for pattern formation was performed. Here, the electron beam irradiation amount is 10 μC / cm ² . By this electron beam irradiation, a large amount of hydrogen ions 10 are again generated in the pattern forming portion, while a small amount of hydrogen ions 10 are also generated in the area other than the pattern forming portion due to electron beam scattering. Here, in order to reduce the concentration of hydrogen ions 10 in the area other than the pattern formation portion, 0.01% TMAH is used.
The entire substrate was immersed in the solution for 10 minutes. This process may be omitted. After that, hot plate baking was performed at 110 ° C. for 2 minutes, and then static development was performed for 3 minutes with a TMAH solution of about 2% to obtain a dot pattern with a pitch of 0.15 μm as shown in FIG. 8 (d). It was

Although only the negative type resist is described here, similar results were obtained for the positive type resist.

Further, in the above-mentioned embodiment, the electron beam irradiation is performed a plurality of times by dividing it into two, but the number of divisions can be increased depending on the density of the pattern. By increasing the number of divisions to three, the pitch is 0.12 μm and the diameter is 0.1 μm.
Got a dot pattern. By further increasing the number of divisions, it has become possible to easily form higher density patterns.

In the above example, the hydrogen ion concentration was reduced by using an ultrathin diluted developer, but the same effect was obtained by irradiating the entire substrate with visible light, ultraviolet rays or X-rays. ..

(Embodiment 4) In Embodiment 3 described above, the reduction of the hydrogen ion concentration is described chemically. Here, a method of physically performing reduction will be described.

On the substrate 1, a porous coatable glass (SO
G) 11 is applied to a thickness of 0.1 μm, and a chemical amplification resist 9 is applied thereon to a thickness of 0.3 μm by spin coating. Here, a negative resist will be described. Then, as shown in FIG. 9A, irradiation with the first electron beam 3 for forming a 0.1 μm pattern is performed. Here, the electron beam dose is 10 μC / cm
^{Is 2} . A large amount of hydrogen ions 10 are generated in the pattern forming portion by this electron beam irradiation, while a small amount of hydrogen ions 1 are also generated in the area other than the pattern forming portion due to electron beam scattering.
0 is generated. If left in the atmosphere for a sufficient period of time, the produced hydrogen ions 10 have a different concentration, so that the coating glass 1
Diffuse into one. As a result, the hydrogen ion concentration of the entire resist was lowered as shown in FIG. 9 (b). At this time, baking may be performed on a hot plate to promote diffusion. The baking temperature is preferably about 60 ° C. so that the crosslinking reaction does not proceed excessively. The baking time was sufficient.

After that, as shown in FIG. 9C, 0.1 μm
A second electron beam 3'for patterning was applied. Here, the electron beam irradiation amount is 10 μC / cm ² . Due to this electron beam irradiation, a large amount of hydrogen ions 10 are again generated in the pattern forming portion, while a small amount of hydrogen ions 10 are also generated in the area other than the pattern forming portion due to electron beam scattering. Here, in order to reduce hydrogen ions in a region other than the pattern formation portion, the film was left in the atmosphere for a sufficient time again. At this time, baking may be performed on a hot plate to promote diffusion. After that, hot plate baking was performed at 110 ° C. for 2 minutes, and then static development was performed for 3 minutes with a TMAH solution of about 2% to obtain a dot pattern having a pitch of 0.15 μm as shown in FIG. 9D. ..

Although only the negative type resist is described here, similar results were obtained for the positive type resist.

Further, in the above embodiment, the electron beam irradiation is performed a plurality of times by dividing it into two, but the number of divisions can be increased depending on the density of the pattern. By increasing the number of divisions to three, the pitch is 0.12 μm and the diameter is 0.1 μm.
Got a dot pattern. By further increasing the number of divisions, it becomes possible to easily form a higher density pattern.

Here, porous coatable glass (SOG) is used.
It has been described that the coating of 0.1 μm is applied.
The material is not limited to this, and any material that allows hydrogen ions to easily diffuse may be used. Needless to say, the film thickness is not limited to 0.1 μm.

(Embodiment 5) In order to realize the above embodiment, the devices were integrated. As shown in FIG. 10, the wafer is coated with the resist by the automatic coating machine 5, and the transfer system 6
It was conveyed to the electron beam drawing apparatus 7 through. The automatic coating machine 5 is provided with a spinner for resist coating and a hot plate for baking. The wafer on which the pattern is drawn is sent to the automatic developing machine 8 through the carrying system 6'and developed. The automatic developing machine 8 is provided with a baking hot plate and a developing machine. Examples 1 and 2
In order to perform the processing described in (1), the wafer was then again sent to the automatic coating machine 5 via the transfer systems 6 ′, 6 to be coated with resist, and then transferred to the electron beam drawing apparatus 7 via the transfer system 6. The wafer on which the pattern is drawn is sent to the automatic developing machine 8 through the carrying system 6'and developed. After that, this process may be repeated depending on the number of irradiations.

Here, the developing machine in the automatic developing machine 8 is connected to a developing machine having an extremely thin developer solution, and the visible light,
An ultraviolet or X-ray irradiation device is installed, and the processing described in the third embodiment can be performed. Further, the temperature of the hot plate for baking is automatically adjusted, and the processing described in the fourth embodiment can be performed. The wafer is transferred between the electron beam drawing apparatus 7 and the automatic developing machine 8 through the transfer system 6 '. The above process may be repeated depending on the number of irradiations.

By this method, a high-density ultrafine pattern of 0.1 μm or less with reduced proximity effect could be easily obtained with high accuracy.

In the above embodiments, the electron beam was used as the energy beam for forming the pattern, but the same effect was observed with respect to X-rays, visible light, ultraviolet rays, ion beams and gamma rays.

[0041]

According to the present invention, it is possible to form a high-density pattern in which the proximity effect is suppressed, and it is possible to easily reduce the proximity effect without requiring complicated computer processing.

[Brief description of drawings]

FIG. 1 is an explanatory view showing an embodiment of the present invention.

FIG. 2 is a distribution map of accumulated energy in a resist.

FIG. 3 is a distribution diagram of accumulated energy seen in a resist cross section.

FIG. 4 is a stored energy distribution map when the pattern interval is wide.

FIG. 5 is a stored energy distribution map when the pattern interval is narrow.

FIG. 6 is a stored energy distribution map when irradiation is divided and performed.

FIG. 7 is an explanatory diagram showing a state of pattern formation when irradiation is divided and performed.

FIG. 8 is an explanatory diagram showing an embodiment of the present invention.

FIG. 9 is an explanatory diagram showing an embodiment of the present invention.

FIG. 10 is an explanatory view showing the device of the present invention.

[Explanation of symbols]

1 ... Substrate, 2, 2 '... Negative electron beam resist, 3, 3'
... electron beam, 4, 4 '... latent image.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Natsuki Yokoyama 1-280, Higashi Koikeku, Kokubunji, Tokyo Metropolitan Research Laboratory, Hitachi Ltd. (72) Inventor, Dai-Kumoto 1-280 Higashi Koikeku, Kokubunji, Tokyo Hitachi Ltd. (72) Inventor Hideyuki Matsuoka, 1-280, Higashi Koikekubo, Kokubunji, Tokyo, Hitachi, Ltd. Central Research Institute (72) Inventor, Kazunori Torii, 1-280, Higashi Koikeku, Tokyo Kokubunji City, Hitachi, Ltd. (72) Inventor Hiromasa Noda 1-280 Higashi Koigokubo, Kokubunji City, Tokyo Inside Hitachi Central Research Laboratory

Claims (7)

[Claims] 1. A pattern forming method for obtaining a pattern by performing development processing after selectively irradiating a material having sensitivity to energy rays, which is installed on a substrate, with the energy rays being selected. The method for pattern formation is characterized by comprising the steps of: irradiating a plurality of times, and reducing the pattern formation reaction in a region other than the pattern forming portion during the plurality of times of irradiation. 2. The method according to claim 1, wherein the step of reducing the pattern forming reaction in a region other than the pattern forming portion is performed by applying a material having sensitivity to the energy rays to the substrate again after development processing. Pattern formation method to be installed. 3. The pattern forming method according to claim 1, wherein the step of reducing the pattern forming reaction in a region other than the pattern forming portion is to reduce the concentration of a substance which is a factor of the pattern forming reaction. 4. The pattern forming method according to claim 1, wherein the method of providing a sensitive material on a substrate is applying the material. 5. The pattern forming method according to claim 1, wherein the energy beam is any one of an electron beam, an X-ray, a visible light, an ultraviolet ray, an ion beam and a gamma ray. 6. The pattern forming method according to claim 1, wherein the developing process performed after selectively irradiating the energy beam is a wet developing process of immersing a substrate in a developing solution. 7. A method of forming a pattern by obtaining a pattern by performing a developing process after selectively irradiating a material having sensitivity to an energy ray, which is installed on a substrate, with the energy ray. The processing apparatus for performing the step of reducing the pattern formation reaction in the area other than the pattern forming portion is integrated with the apparatus for selectively irradiating the substrate, and the substrate is transferred between the apparatuses by the transfer system. A pattern forming device.