JP3462110B2 - Charged particle beam exposure mask and exposure method using the same - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a charged particle beam exposure mask, a method for manufacturing the same, an exposure apparatus and an exposure method using the same.

[0002]

2. Description of the Related Art In recent years, as the degree of integration of semiconductor devices has increased, the circuit patterns of the LSI elements that make them up have become finer and finer. For the miniaturization of the pattern, not only the line width is simply reduced, but also the dimensional accuracy and the positional accuracy of the pattern are required to be improved.

Many techniques have been developed to meet these demands, but most of them are designed to draw a circuit pattern directly on a semiconductor substrate using charged particles such as an electron beam. , A transfer mask is drawn on a mask substrate using charged particles such as electron beams, and the mask substrate pattern is formed by using light such as ultraviolet rays and X-rays, charged particles such as electron beams and ion beams, and a semiconductor substrate. It uses the method of transcription on top. Therefore, in order to form a fine pattern with high accuracy, it is important to first improve the accuracy of pattern formation using charged particles such as an electron beam.

On the other hand, in addition to the high integration of semiconductor devices, the size of each device (so-called chip size)
As the size becomes larger, it takes a lot of time to draw the circuit pattern of one LSI element, resulting in a decrease in throughput, that is, a decrease in productivity. In general, high precision and high speed often conflict with each other. In particular, it is known that pattern formation using charged particles has high precision but low throughput.

Conventionally, various charged particle optical systems have been proposed for the purpose of forming a pattern using charged particles. However, it is difficult to sufficiently reduce various aberrations in these charged particle optical systems, and particularly when an attempt is made to increase the field size in order to improve throughput, extremely large aberrations occur, There is a problem that it cannot be put to practical use.

In order to address such a problem, as described in Japanese Patent Application No. 9-337331, a reflection type charged particle beam optical element based on a concept that has not existed in the past has been devised by the present inventor. The exposure apparatus used is being developed. That is, in this exposure apparatus, the charged beam is made incident on the reflection type exposure mask, and the reflected electrons are emitted in accordance with the pattern formed on the mask. By accurately guiding the reflected electrons to the substrate to be exposed, the substrate to be exposed is exposed in a desired pattern. However, as the development proceeds, Japanese Patent Application No. 9-33733.
Several new issues that had not been examined at the time of filing 1 were clarified.

[0007]

Some proposals have heretofore been made regarding transmissive masks, but there are no detailed proposals regarding reflective masks. However, obtaining a highly efficient reflective mask leads to suppression of heat generation in the mask, so that it is possible to improve the exposure accuracy and it is not necessary to increase the intensity of the light source extremely. From the above, it became clear that this is a great advantage for the entire exposure apparatus.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a charged particle beam capable of forming a pattern with high accuracy and high speed by providing a mask suitable for an exposure apparatus. An object is to provide an exposure mask, a method for manufacturing the same, an exposure apparatus and an exposure method using the same.

[0009]

In order to solve the above-mentioned problems, the present invention is directed to irradiating a charged particle beam emitted from a light source and irradiating the exposed substrate with the charged particle beam obtained by this irradiation. Type charged particle beam exposure mask, wherein a desired pattern portion is substantially composed of a single crystal, and except the desired pattern portion, the charged particle beam is more reflective than the desired pattern portion. Provided is a charged particle beam exposure mask, which is characterized by being composed of a material having a low index.

It is preferable that the charged particle beam exposure mask further includes the following configuration.

(1) Except for the desired pattern portion, it is made of an amorphous material.

(2) The amorphous material is made of an amorphous semiconductor and contains conductive impurities.

(3) The amorphous material is made of silicon oxide.

(4) The desired pattern portion is composed of a semiconductor single crystal substrate.

(5) The semiconductor single crystal substrate is silicon,
Consists of germanium or silicon germanium.

The charged particle beam exposure mask may be filled with a material having a different crystal structure as a material having a reflectance different from that of the single crystal substrate.

Further, the charged particle beam exposure mask is
An amorphous film made of the same material as the single crystal substrate is formed on a base including the substrate, a desired mask pattern is formed on the amorphous film, and then ion implantation is performed using the desired mask pattern. Then, the single crystal substrate is used as a seed crystal to single crystallize the amorphous film portion other than the ion-implanted portion.

Further, the charged particle beam exposure mask is
An insulating pattern is formed on a base including a single crystal substrate, an amorphous film made of the same material as the single crystal substrate is formed on the insulating pattern, and the amorphous film is formed by using the single crystal substrate as a seed crystal. It can also be produced by single crystallizing.

The charged particle beam exposure mask exposes a charged particle beam obtained by irradiating the exposure mask with the charged particle beam emitted from a light source and the illumination optical system. It can be used for an exposure apparatus having a projection optical system for irradiating a substrate.

The present invention is also an exposure method in which a charged particle beam emitted from a light source is applied to the reflective charged particle beam exposure mask, and the charged particle beam obtained by this irradiation is applied to a substrate to be exposed. An exposure method is provided in which a charged particle beam with which the exposure mask is irradiated and a substantially single crystal portion of the exposure mask satisfy a Bragg condition.

It is preferable that the exposure method further includes the following configuration.

(1) The Bragg condition is satisfied by controlling at least one of the energy, incident angle, emission angle and mask posture of the charged particle beam incident on the exposure mask.

(2) Using an aperture to remove at least part of the unwanted charged particle beam.

Further, the present invention is an exposure method in which a charged particle beam emitted from a light source is applied to the reflection type charged particle beam exposure mask, and the charged particle beam obtained by this irradiation is applied to a substrate to be exposed. There is provided an exposure method in which an extraction electric field is applied to the charged particle beam obtained by the irradiation, and at least a part of the obtained charged particle beam is removed by using an aperture.

It is preferable that the exposure method further includes the following configuration.

(1) As a method of applying the extraction electric field, a bias voltage is applied to the exposure mask.

(2) As a method of applying the extraction electric field, a bias voltage is applied to the aperture. According to the present invention, it is possible to provide a highly efficient charged particle beam exposure mask, and it is possible to perform exposure with sufficient throughput with high accuracy without extremely increasing the intensity of the light source.

[0028]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. (First Embodiment) FIG. 1 is a sectional view showing the arrangement of an electron beam mask according to the first embodiment of the present invention. Substrate 20 made of Si single crystal as a mask for electron beam
1, a desired mask pattern 202 made of Cu is formed. Further, the substrate 201 is bonded on a Cu support substrate having good heat conductivity, and has a structure in which heat generated on the mask surface can be easily removed from the back surface. It is known that an electron beam with kinetic energy E (eV) per electron behaves as a wave having a wavelength (de Broglie wavelength) given by the following equation (equation (1)).

[0029]

[Equation 1]

When a wave having such a wavelength is incident on a substance in which atoms are regularly arranged, such as a single crystal, when the Bragg reflection condition (equation (2)) of the following equation is satisfied,
It is known that particularly strong reflection occurs (see FIG. 2).

[0031]

[Equation 2]

Where d is the lattice spacing, θ is the angle of incidence / emission, and n is a positive integer. It has become possible to obtain a highly efficient reflective mask by utilizing this principle. In principle, if the substance has a different lattice constant or is not a single crystal, the Bragg reflection condition is not satisfied, so the reflection intensity is extremely small, and the unnecessary portion of the pattern may be formed of such a substance. For example, an amorphous substance or a substance having a large electron absorption coefficient is suitable. Further, more desirably, in order to prevent adverse effects due to the generation of a non-uniform electric field due to charging, a substance having an electric conductivity that prevents charging is suitable.

Strictly speaking, the wavelength given by (Equation (1)) is the wavelength in vacuum, and the wavelength giving the Bragg reflection condition (Equation (2)) is the wavelength in the substance.
It is necessary to correct the refractive index based on the average potential.
In addition, Bragg reflection is due to the crystallographic symmetry of the single crystal,
It should be noted that the reflection intensity does not become maximum for all integers n, and there is an index n that is forbidden reflection.

For example, in the case of Si, the average potential is 11.5.
Since it is V, it is necessary to correct the wavelength with a magnitude that cannot be ignored even when the incident energy is about 1 kV. Also, Si
Since is a diamond type crystal structure, {200} reflections are forbidden reflections. Assuming a Si (100) substrate that is relatively easily available, {400}, {800}, etc. {400} reflections that are integral multiples of the {300} reflection are easy to use. In this case, d in (Equation (2))
Is about 0.136 nm.

A feature of this embodiment is that the Bragg reflection is used, and thus the monochromaticity and directivity of the reflected electrons are extremely excellent. This has the advantage that it is possible to reduce the blur of the image when forming the reflected electrons and to improve the utilization efficiency of the reflected electrons.

FIGS. 3A to 3G are process cross-sectional views showing a method for manufacturing an electron beam mask according to the above embodiment. The resist 203 is rotated on the substrate 201 made of Si single crystal with a diameter of 12 inches and a thickness of 1 mm and a plane orientation (001).
After spin coating at 2000 rpm, heat treatment was performed at 110 ° C. for 90 seconds to form a thin film having a thickness of 0.3 μm (FIG. 3 (b)).

Next, a desired pattern is drawn by using the electron beam drawing device. Electron beam drawing has an accelerating voltage of 75
Under the conditions of kV and standard irradiation amount of 20 μC / cm ² , the irradiation amount correction was applied as a proximity effect countermeasure. After drawing, development processing was performed to obtain a desired resist pattern (Fig. 3).
(C)). Then, based on this resist pattern, HBr
Si substrate to 0.2 by reactive ion etching using
It was processed to a depth of μm (FIG. 3 (d)). After processing, the unnecessary resist was removed by ashing treatment in oxygen plasma, and then washed in a mixed solution of sulfuric acid and hydrogen peroxide solution (FIG. 3 (e)).

Next, a copper (Cu) film 202 having a film thickness of 0.2 μm is formed using an rf sputtering device under the condition of Ar pressure of 3 mTorr, and heat treatment is performed at 550 ° C. for 1 minute in the same vacuum as sputtering. Then, the recesses of the pattern were cohesively embedded (FIG. 3 (f)).

Finally, after removing excess Cu remaining on the flat portion by a polishing method, cleaning was performed (FIG. 3 (g)). Polishing conditions are polishing pressure 300 g
/ Cm ₂ , the rotation speed of the polishing platen was 100 rpm, and the polishing agent was 0.12 mol / l glycine (C ₂ H ₅ O ₂ N) aqueous solution.
5.3% by weight of silica particles having an average particle diameter of 30 nm as polishing particles were dispersed in a mixed solution of 0.44 mol / l hydrogen peroxide solution (H ₂ O ₂ ) to prepare 0.001 mol / l benzotriazole (C
₆ H ₅ N ₃ ) was used.

By the above method, a mask having the structure shown in FIG. 1 can be prepared, and a highly efficient reflective mask can be obtained. In order to manufacture a highly accurate mask, it is important that the surface of the substrate maintains a sufficient flatness in the electron beam drawing process and the polishing process. Therefore, in these steps, it is desirable to mount the substrate on a holder having sufficient flatness and sufficient rigidity.

(Second Embodiment) FIGS. 4H to 4N.
FIG. 6A is a process cross-sectional view illustrating a method for manufacturing an electron beam mask according to a second embodiment of the present invention. The difference from the first embodiment is that an SOI substrate is used as the substrate 201.

Si having a diameter of 12 inches and a thickness of 1 mm and a plane orientation (001)
The thickness of the single crystal is 0.1 μm thick with a SiO ₂ film
SOI substrate with 0.2 μm plane orientation (001) Si single crystal
A resist 203 was spin-coated at a substrate rotation speed of 2000 rpm on 201, and then heat-treated at 110 ° C. for 90 seconds to give a film thickness of 0.3 μm.
Was formed (FIG. 4 (i)).

Next, a desired pattern is drawn by using the electron beam drawing device. Electron beam drawing has an accelerating voltage of 75
Under the conditions of kV and standard irradiation amount of 20 μC / cm ² , the irradiation amount correction was applied as a proximity effect countermeasure. After drawing, development processing was performed to obtain a desired resist pattern (Fig. 4).
(J)). Then, based on this resist pattern, HBr
Si substrate to 0.2 by reactive ion etching using
It was processed to a depth of μm (FIG. 4 (k)). The use of the SOI substrate has the advantage that the SiO2 film serves as an etching stopper and the etching end points are evenly aligned. After processing, the unnecessary resist was removed by ashing treatment in oxygen plasma, and then washed in a mixed solution of sulfuric acid and hydrogen peroxide water (FIG. 4 (l)).

Next, a copper (Cu) film 202 having a film thickness of 0.2 μm is formed using an rf sputtering device under the condition of Ar pressure of 3 mTorr, and heat treatment is performed at 550 ° C. for 1 minute in the same vacuum as sputtering. Then, the recesses of the pattern were cohesively embedded (FIG. 4 (m)).

Finally, after removing excess Cu remaining on the flat portion by a polishing method, cleaning was performed (FIG. 4 (n)). Polishing conditions are polishing pressure 300 g
/ Cm ² , the rotation speed of the polishing platen was 100 rpm, and the polishing agent was 0.12 mol / l glycine (C ₂ H ₅ O ₂ N) aqueous solution.
5.3% by weight of silica particles having an average particle diameter of 30 nm as polishing particles were dispersed in a mixed solution of 0.44 mol / l hydrogen peroxide solution (H ₂ O ₂ ) to prepare 0.001 mol / l benzotriazole (C
₆ H ₅ N ₃ ) was used.

By the above method, a mask similar to the structure shown in FIG. 1 can be prepared, and a highly efficient reflection type mask can be obtained. In order to manufacture a highly accurate mask, it is important that the surface of the substrate maintains a sufficient flatness in the electron beam drawing process and the polishing process. Therefore, in these steps, it is desirable to mount the substrate on a holder having sufficient flatness and sufficient rigidity.

Further, with the use of the SOI substrate, there is a feature that the structure after the step of FIG. 4L has a structure that can be used as a mask. That is, the structure of FIG. 4 (l) is already formed of a pattern made of a single crystal and a portion made of an amorphous oxide film, and in this state, the condition required as a mask is satisfied. Therefore, there is also an advantage that inspection and correction can be performed before proceeding to the remaining steps.

(Third Embodiment) FIGS. 5A to 5F.
FIG. 6A is a process cross-sectional view showing the method of manufacturing an electron beam mask according to the third embodiment of the present invention. 12 inch diameter thickness
On a substrate 201 made of Si single crystal with 1 mm plane orientation (001),
A tungsten (W) film 204 having a film thickness of 0.2 μm was formed under the Ar pressure of 3 mTorr using an rf sputtering device (FIG. 5B). Then, set the resist 203 to 20
After spin coating at 00 rpm, heat treatment was performed at 110 ° C. for 90 seconds to form a thin film having a thickness of 0.3 μm (FIG. 5 (c)).

Next, a desired pattern is drawn by using the electron beam drawing device. Electron beam drawing has an accelerating voltage of 75
Under the conditions of kV and standard irradiation amount of 20 μC / cm ² , the irradiation amount correction was applied as a proximity effect countermeasure. After drawing, development processing was performed to obtain a desired resist pattern (Fig. 5).
(D)). Then, based on this resist pattern, CH
The tungsten film was processed by reactive ion etching using F ₃ until reaching the Si substrate (FIG. 5E).
After processing, the unnecessary resist is removed by ashing treatment in oxygen plasma, and then washed with dilute sulfuric acid and pure water (Fig. 5).
(F)).

By the above method, a mask having a structure having an absorber in an unnecessary portion of the pattern can be prepared, and a highly efficient reflection type mask can be obtained. In order to create a highly accurate mask, it is important that the surface of the substrate maintains a sufficient flatness in the electron beam writing process. Therefore, in these steps, it is desirable to mount the substrate on a holder having sufficient flatness and sufficient rigidity.

(Fourth Embodiment) FIGS. 6A to 6H.
FIG. 6A is a process cross-sectional view illustrating the method of manufacturing the electron beam mask according to the fourth embodiment of the invention. 12 inch diameter thickness
On a substrate 201 made of Si single crystal with 1 mm plane orientation (001),
A SiO2 film 205 having a thickness of 0.8 .mu.m was formed by the CVD method (FIG. 6 (b)). Then, set the resist 203 to the substrate rotation speed.
After spin coating at 2000 rpm, heat treatment was carried out at 110 ° C. for 90 seconds to form a thin film having a thickness of 0.3 μm (FIG. 6 (c)).

Next, a desired pattern is drawn by using the electron beam drawing device. Electron beam drawing has an accelerating voltage of 75
Under the conditions of kV and standard irradiation amount of 20 μC / cm ² , the irradiation amount correction was applied as a proximity effect countermeasure. After drawing, development processing was performed to obtain a desired resist pattern (Fig. 6).
(D)). Then, based on this resist pattern, CH
The SiO ₂ film was processed by reactive ion etching using F ₃ and CO gas until reaching the Si substrate (FIG. 6).
(E)). After processing, the unnecessary resist was removed by ashing treatment in oxygen plasma, and then washed in a mixed solution of sulfuric acid and hydrogen peroxide solution (FIG. 6 (f)).

Next, As is ion-implanted by using the remaining SiO ₂ film as a mask, an amorphous region 20 is formed on the surface layer of the Si substrate which is not covered with the SiO ₂ film.
6 was formed (FIG. 6 (g)). Finally, the SiO ₂ film was removed using a hydrofluoric acid (HF) aqueous solution to expose the surface of the Si substrate (FIG. 6 (h)).

By the above method, a mask having a structure in which an unnecessary portion of the pattern is formed of As-doped amorphous silicon having appropriate conductivity can be prepared, and a highly efficient reflection type mask can be obtained. In addition,
In order to create a highly accurate mask, it is important that the surface of the substrate maintains a sufficient flatness in the electron beam writing process. Therefore, in these steps, it is desirable to mount the substrate on a holder having sufficient flatness and sufficient rigidity.

(Fifth Embodiment) FIGS. 7A to 7G.
[FIG. 9A] is a process sectional view showing the method of manufacturing the electron beam mask according to the fifth embodiment of the present invention. 12 inch diameter thickness
On a substrate 201 made of Si single crystal with 1 mm plane orientation (001),
An amorphous silicon film 207 having a film thickness of 0.3 μm was formed by using the CVD method (FIG. 7B). And resist 20
3 was spin-coated at a substrate rotation speed of 2000 rpm, and then heat-treated at 110 ° C. for 90 seconds to form a thin film having a thickness of 0.3 μm (FIG. 7 (c)).

Next, a desired pattern is drawn by using the electron beam drawing device. Electron beam drawing has an accelerating voltage of 75
Under the conditions of kV and standard irradiation amount of 20 μC / cm ² , the irradiation amount correction was applied as a proximity effect countermeasure. After drawing, development processing was performed to obtain a desired resist pattern (Fig. 7).
(D)). Then, P 2 is ion-implanted at low energy based on this resist pattern, thereby forming an overdoped region 208 of P 2 in the amorphous silicon film (FIG. 7E). After ion implantation, after removing the unnecessary resist by ashing in oxygen plasma,
It was washed in a mixed solution of sulfuric acid and hydrogen peroxide (Fig. 7).
(F)).

Finally, annealing treatment was performed at 600 ° C.
Area 209 that was not ion-implanted due to the annealing treatment
, The crystallization progressed homoepitaxially with the underlying Si substrate, and the region 209 became a single crystal.
In 208, crystallization does not proceed sufficiently because the impurities are excessive, and it remains amorphous (FIG. 7 (g)).

By the above method, it becomes possible to prepare a mask having a structure in which an unnecessary portion of the pattern is formed of P-doped amorphous silicon having appropriate conductivity,
It was possible to obtain a highly efficient reflective mask. In order to create a highly accurate mask, it is important that the surface of the substrate maintains a sufficient flatness in the electron beam writing process. Therefore, in these steps, it is desirable to mount the substrate on a holder having sufficient flatness and sufficient rigidity.

(Sixth Embodiment) FIGS. 8A to 8H are process sectional views showing a method for manufacturing an electron beam mask according to a sixth embodiment of the present invention. Substrate 201 made of Si single crystal with a diameter of 12 inches and a thickness of 1 mm and a plane orientation (001)
A SiO ₂ film 205 having a film thickness of 0.2 μm was formed on the upper surface by the CVD method (FIG. 8B). Then, the resist 203 was spin-coated at a substrate rotation speed of 2000 rpm and then heat-treated at 110 ° C. for 90 seconds to form a thin film having a thickness of 0.3 μm (FIG. 8).
(C)).

Next, a desired pattern is drawn by using the electron beam drawing device. Electron beam drawing has an accelerating voltage of 75
Under the conditions of kV and standard irradiation amount of 20 μC / cm ² , the irradiation amount correction was applied as a proximity effect countermeasure. After drawing, development processing was performed to obtain a desired resist pattern (FIG. 8).
(D)). Then, based on this resist pattern, CH
The SiO ₂ film was processed by reactive ion etching using F ₃ and CO gas until reaching the Si substrate (FIG. 8).
(E)). After processing, the unnecessary resist was removed by ashing treatment in oxygen plasma, and then washed in a mixed solution of sulfuric acid and hydrogen peroxide (FIG. 8 (f)).

Then, using the remaining SiO2 film as a mask, Si was selectively epitaxially grown by the CVD method (FIG. 8 (g)). As a result, the Si single crystal 210 was homoepitaxially grown on the Si substrate not covered with the SiO ₂ film.

Finally, by polishing method, SiO ₂
After removing excess Si remaining on the film, cleaning was performed (FIG. 8 (h)). Polishing condition is polishing pressure 30
0 g / cm ² , the rotation speed of the polishing platen was 100 rpm, and the polishing agent was silica particles having an average particle size of 30 nm as abrasive particles of 5.3
The thing dispersed at weight% was used.

By the above method, a mask having a structure in which a required portion of a pattern is formed of a single crystal by selective growth can be prepared, and a highly efficient reflection type mask can be obtained. In addition, in order to create a highly accurate mask, in the electron beam drawing process and the polishing process,
It is important that the surface of the substrate maintain sufficient flatness. Therefore, in these steps, it is desirable to mount the substrate on a holder having sufficient flatness and sufficient rigidity.

(Seventh Embodiment) Next, a method of performing exposure using the electron beam mask obtained by the present invention will be described. FIG. 9 is a block diagram of an exposure apparatus equipped with a mask. The structural requirements are roughly classified into a light source 214, an illumination optical system 215, a projection optical system 216, an electron beam mask 217, a mask stage 218, and an exposed substrate 219.
The exposed substrate stage 220 and the control system 221 can be divided.

The features of this embodiment are as follows. In order to satisfy the condition of Bragg reflection, the illumination optical system 21
5 is not only the position of the electron beam incident on the mask 217,
It has an alignment lens 226a having a deflector system capable of finely adjusting the incident angle. Similarly, the projection optics 21
6 represents the reflected electrons emitted from the mask 217 with good directivity,
An alignment lens 226b having a deflector system capable of finely adjusting not only the taking-in position but also the taking-in angle is provided so as to enable accurate guiding.

Further, the apertures 227a and 227b provided in the projection optical system 216 are used to cut off unnecessary scattered electrons such as secondary electrons and remove unnecessary background. Further, the mask stage 218 also has a structure in which 6-axis control is possible so that fine adjustment can be performed to satisfy the condition of Bragg reflection in addition to the operation for normal step-and-scan exposure.

Further, since a bias voltage is applied to the mask 217, the wavelength of the electrons can be finely adjusted by finely adjusting the energy of the electrons incident on the mask so that the Bragg reflection condition can be satisfied. It has become a structure. At the time of actual exposure (transfer), while the mask 217 satisfies the Bragg condition, the mask 217 and the substrate 219 to be exposed are synchronously moved, and an elongated strip-shaped exposure (transfer) region is scanned. By doing so, the exposure (transfer) is performed on the entire exposed (transfer) area. In FIG. 9, reference numeral 222 is a mask stage control system, 223 is an exposed substrate stage control system, 224 is a mask side alignment mechanism,
Reference numeral 225 is an alignment mechanism on the exposed substrate side.

(Eighth Embodiment) FIG. 10 is a sectional view showing the structure of an electron beam mask according to the eighth embodiment of the present invention. As a mask for an electron beam, a desired mask pattern 211 made of BeCu is formed on a substrate 201 made of Si single crystal, and the surface of BeCu is oxidized to BeO.
Thin film 212 is formed. Further, the substrate 201 is bonded on a Cu support substrate having good heat conductivity, and has a structure in which heat generated on the mask surface can be easily removed from the back surface.

BeCu whose surface is oxidized to form BeO
Is well known as a substance having an extremely high secondary electron emission efficiency, and is used for a photomultiplier tube and the like. By utilizing this property, it becomes possible to obtain a highly efficient reflective mask. Hydrogen-terminated diamond is known as a substance having similar properties, and the same effect can be obtained by using this (see FIG. 11).

As shown in FIG. 11, no matter which material is used, the secondary electron emission efficiency γ is about 5 or more with respect to the incident electron with energy of 400 eV. I know the good thing. The unnecessary part of the pattern may be formed of any material as long as it is a material having a low secondary electron emission efficiency, but in order to prevent the adverse effect of the non-uniform electric field due to charging, charging is prevented. A substance having a degree of electric conductivity is desirable.

12A to 12G are process sectional views showing a method of manufacturing an electron beam mask according to the eighth embodiment. A resist 203 is applied to a substrate 201 made of Si single crystal with a diameter of 12 inches and a thickness of 1 mm and a plane orientation of (001) at a substrate rotation speed of 2000
After spin coating at rpm, heat treatment at 110 ℃ for 90 seconds,
A thin film having a thickness of 0.3 μm was formed (FIG. 12B).

Next, a desired pattern is drawn by using the electron beam drawing device. Electron beam drawing has an accelerating voltage of 75
Under the conditions of kV and standard irradiation amount of 20 μC / cm ² , the irradiation amount correction was applied as a proximity effect countermeasure. After drawing, development processing was performed to obtain a desired resist pattern (FIG. 12).
(C)). Then, based on this resist pattern, HBr
Si substrate to 0.2 by reactive ion etching using
It was processed to a depth of μm (FIG. 12 (d)). After processing, the unnecessary resist was removed by ashing treatment in oxygen plasma, and then washed in a mixed solution of sulfuric acid and hydrogen peroxide (FIG. 12 (e)).

Next, a BeCu film having a film thickness of 0.2 μm was formed under the condition of Ar pressure of 3 mTorr by using an rf sputtering device, and heat treatment was performed at 550 ° C. for 1 minute in the same vacuum as the sputtering to form the concave portion Cohesive embedding was carried out (FIG. 12).
(F)).

Finally, excess BeCu remaining on the flat portion was removed by a polishing method, and then cleaning was performed (FIG. 12 (g)). Polishing condition is polishing pressure 300
g / cm ² , the rotation speed of the polishing platen was 100 rpm, and the polishing agent was 0.12 mol / l glycine (C ₂ H ₅ O ₂ N) aqueous solution.
5.3% by weight of silica particles having an average particle diameter of 30 nm as polishing particles were dispersed in a mixed solution of 0.44 mol / l hydrogen peroxide solution (H ₂ O ₂ ) to prepare 0.001 mol / l benzotriazole (C
₆ H ₅ N ₃ ) was used. The surface of BeCu was oxidized and a thin film 212 of BeO 3 was formed during storage in the atmosphere after the cleaning process after polishing. The BeO 2 thin film 212 can be obtained by oxidizing the surface of BeCu in a separate oxidation process (the same applies to the embodiments described later).

By the above method, a mask having the structure shown in FIG. 10 can be prepared, and a highly efficient reflective mask can be obtained. In order to manufacture a highly accurate mask, it is important that the surface of the substrate maintains a sufficient flatness in the electron beam drawing process and the polishing process. Therefore, in these steps, it is desirable to mount the substrate on a holder having sufficient flatness and sufficient rigidity.

(Ninth Embodiment) FIGS. 13H to 13N are process sectional views showing a method for manufacturing an electron beam mask according to a ninth embodiment of the present invention. The difference from the eighth embodiment is that an SOI substrate is used as the substrate 201.

Si having a diameter of 12 inches and a thickness of 1 mm and a plane orientation (001)
The thickness of the single crystal is 0.1 μm thick with a SiO ₂ film
SOI substrate with 0.2 μm plane orientation (001) Si single crystal
A resist 203 was spin-coated at a substrate rotation speed of 2000 rpm on 201, and then heat-treated at 110 ° C. for 90 seconds to give a film thickness of 0.3 μm.
Was formed (FIG. 13 (i)).

Next, a desired pattern is drawn by using the electron beam drawing device. Electron beam drawing has an accelerating voltage of 75
Under the conditions of kV and standard irradiation amount of 20 μC / cm ² , the irradiation amount correction was applied as a proximity effect countermeasure. After drawing, development processing was performed to obtain a desired resist pattern (FIG. 13).
(J)). Then, based on this resist pattern, HBr
Si substrate to 0.2 by reactive ion etching using
It was processed to a depth of μm (FIG. 13 (k)). The use of the SOI substrate has an advantage that the SiO ₂ film serves as an etching stopper and the etching end points are evenly aligned. After processing, the unnecessary resist was removed by ashing treatment in oxygen plasma, and then washed in a mixed solution of sulfuric acid and hydrogen peroxide (FIG. 13 (l)).

Next, a BeCu film having a film thickness of 0.2 μm was formed using an rf sputtering device under the condition of Ar pressure of 3 mTorr, and heat treatment was performed at 550 ° C. for 1 minute in the same vacuum as the sputtering to form the concave portion Cohesive embedding was carried out (FIG. 13).
(M)).

Finally, excess BeCu remaining on the flat portion was removed by a polishing method, and then cleaning was performed (FIG. 13 (n)). Polishing condition is polishing pressure 300
g / cm ² , the rotation speed of the polishing platen was 100 rpm, and the polishing agent was 0.12 mol / l glycine (C ₂ H ₅ O ₂ N) aqueous solution.
5.3% by weight of silica particles having an average particle diameter of 30 nm as polishing particles were dispersed in a mixed solution of 0.44 mol / l hydrogen peroxide solution (H ₂ O ₂ ) to prepare 0.001 mol / l benzotriazole (C
₆ H ₅ N ₃ ) was used. The surface of BeCu was oxidized and a thin film 212 of BeO 3 was formed during storage in the atmosphere after the cleaning process after polishing.

By the above method, a mask similar to the structure shown in FIG. 10 can be prepared, and a highly efficient reflective mask can be obtained. In order to manufacture a highly accurate mask, it is important that the surface of the substrate maintains a sufficient flatness in the electron beam drawing process and the polishing process. Therefore, in these steps,
It is desirable to mount the substrate on a holder having sufficient flatness and sufficient rigidity.

(Tenth Embodiment) FIGS. 14A to 14H are process sectional views showing a method of manufacturing an electron beam mask according to a tenth embodiment of the present invention. Substrate 201 made of Si single crystal with a diameter of 12 inches and a thickness of 1 mm and a plane orientation (001)
Ar pressure 3 mTorr
A BeCu film 211 having a film thickness of 0.2 μm was formed under the condition (FIG. 14).
(B)). Then, set the resist 203 to the substrate rotation speed of 2000 rpm.
After spin coating at 90 ° C for 90 seconds,
A thin film of 0.3 μm was formed (FIG. 14 (c)).

Next, a desired pattern is drawn by using the electron beam drawing device. Electron beam drawing has an accelerating voltage of 75
Under the conditions of kV and standard irradiation amount of 20 μC / cm ² , the irradiation amount correction was applied as a proximity effect countermeasure. After drawing, development processing was performed to obtain a desired resist pattern (FIG. 14).
(D)). Then, based on this resist pattern, Cl
BeCu film 2 by reactive ion etching using ₂ gases
11 was processed until it reached the Si substrate 201 (Fig. 14).
(E)). After processing, the unnecessary resist was removed by ashing treatment in oxygen plasma, and then washed in a mixed solution of sulfuric acid and hydrogen peroxide solution (FIG. 14 (f)).

Even in this state, the structure required for the mask is provided and it can be used as a mask.
In order to reduce the unevenness of secondary electron emission due to the edge of BeCu, the following process was added. First, a P-doped polycrystalline silicon film 213 having a film thickness of 0.3 μm was formed by the CVD method (FIG. 14 (g)).

Finally, after removing excess Si remaining on the BeCu film by the polishing method, cleaning was performed (FIG. 14 (h)). Polishing condition is polishing pressure 300
The polishing rate was g / cm ² , the rotation speed of the polishing platen was 100 rpm, and the polishing agent used was a dispersion of 5.3% by weight of silica particles having an average particle size of 30 nm as polishing particles. After the cleaning process after polishing, the BeCu
The surface of was oxidized and a thin film of BeO 2 212 was formed.

By the above method, a mask having a structure in which a necessary portion of the pattern is formed of BeO / BeCu having a high secondary electron emission efficiency and an unnecessary portion of the pattern is formed of P-doped polycrystalline silicon having appropriate conductivity is used. It became possible to create a reflective mask with high efficiency.
In order to manufacture a highly accurate mask, it is important that the surface of the substrate maintains a sufficient flatness in the electron beam drawing process and the polishing process. Therefore, in these steps, it is desirable to mount the substrate on a holder having sufficient flatness and sufficient rigidity.

(Eleventh Embodiment) FIGS. 15A to 15G are process sectional views showing a method for manufacturing an electron beam mask according to an eleventh embodiment of the present invention. Substrate 201 made of Si single crystal with a diameter of 12 inches and a thickness of 1 mm and a plane orientation (001)
Ar pressure 3 mTorr
A BeCu film 211 having a film thickness of 0.2 μm was formed under the conditions (Fig. 15).
(B)). Next, Ar pressure using an rf sputtering device
0.2 μm thick tungsten (W) film under the condition of 3 mTorr
204 was deposited (FIG. 15C). And resist 20
3 was spin-coated at a substrate rotation speed of 2000 rpm, and then heat-treated at 110 ° C. for 90 seconds to form a thin film having a thickness of 0.3 μm (FIG. 15 (d)).

Next, a desired pattern is drawn by using the electron beam drawing device. Electron beam drawing has an accelerating voltage of 75
Under the conditions of kV and standard irradiation amount of 20 μC / cm ² , the irradiation amount correction was applied as a proximity effect countermeasure. After drawing, development processing was performed to obtain a desired resist pattern (FIG. 15).
(E)). Then, based on this resist pattern, CH
The tungsten film was processed by reactive ion etching using F ₃ until it reached the BeCu film (FIG. 15).
(F)). After processing, the unnecessary resist was removed by ashing treatment in oxygen plasma, and then washed with dilute sulfuric acid and pure water (FIG. 15 (g)). The surface of BeCu is oxidized during storage in the atmosphere after the cleaning process and BeO
Thin film 212 of was formed.

By the above method, the necessary portion of the pattern is formed of BeO / BeCu having a high secondary electron emission efficiency, and the unnecessary portion of the pattern has an appropriate conductivity and has a function of absorbing incident electrons. A mask having the formed structure can be prepared, and a highly efficient reflective mask can be obtained. In order to create a highly accurate mask, it is important that the surface of the substrate maintains a sufficient flatness in the electron beam writing process. Therefore, in these steps, it is desirable to mount the substrate on a holder having sufficient flatness and sufficient rigidity.

(Twelfth Embodiment) Next, the eighth embodiment of the present invention will be described.
A method of performing exposure using the electron beam mask obtained according to the eleventh embodiment will be described. FIG. 16 is a block diagram of an exposure apparatus equipped with a mask. The configuration requirements are roughly classified into a light source 214 and an illumination optical system 21.
5, projection optical system 216, mask 217 and mask stage 21
8, the exposed substrate 219, the exposed substrate stage 220, and the control system 221. The structure of the exposure apparatus shown in FIG. 16 is almost the same as that of the exposure apparatus shown in FIG.

The features of this embodiment are as follows. The secondary electrons emitted from the mask 217 have a wide energy distribution and a wide emission angle,
It is not a good idea to incorporate it directly into the projection optical system 216. Therefore, by applying a bias voltage to the mask, the emitted secondary electrons are uniformly accelerated to a sufficient energy,
The ratio of the energy distribution to the total energy is made small and the ratio of the momentum in the mask horizontal direction to the momentum in the mask vertical direction is made sufficiently small to improve the apparent monochromaticity and directivity.

Further, apertures 227a 'and 227b' are arranged to cut off excess electrons, and a voltage is applied to the apertures to increase the extraction electric field. During the actual exposure (transfer), the mask 217 and the substrate 219 to be exposed move in synchronization with each other,
By scanning the strip-shaped exposure (transfer) area,
Exposure (transfer) is performed on the entire exposed (transfer) area.

The present invention is not limited to the above embodiment. In addition to the above-described embodiment, various modifications can be made regarding the substance used as the mask material and the mask manufacturing process. As a substance that forms the non-reflective area, A
l, Ta, Ti, Cr, Ge, Ga, In and other substances and their compounds,
Various metals and semiconductors can be used, and Ge or the like can be used as the mask substrate in addition to Si. Further, in the present invention, not only electrons but also ions or the like can be used as the charged particles. In addition, various modifications can be made without departing from the spirit of the present invention.

[0094]

According to the present invention, it is possible to provide a highly efficient charged particle beam exposure mask, and it is possible to perform exposure with a sufficient throughput with high accuracy without extremely increasing the intensity of the light source. .

[Brief description of drawings]

FIG. 1 is a sectional view showing a configuration of an exposure mask according to a first embodiment of the present invention.

FIG. 2 is a schematic diagram illustrating the principle of the present invention.

FIG. 3 is a process sectional view showing the method of manufacturing the exposure mask according to the first embodiment.

FIG. 4 is a process sectional view showing the method of manufacturing the exposure mask according to the second embodiment of the present invention.

FIG. 5 is a process sectional view showing the method of manufacturing the exposure mask according to the third embodiment of the present invention.

FIG. 6 is a process sectional view showing the method of manufacturing the exposure mask according to the fourth embodiment of the present invention.

FIG. 7 is a process sectional view showing the method of manufacturing the exposure mask according to the fifth embodiment of the present invention.

FIG. 8 is a process sectional view showing the method of manufacturing the exposure mask according to the sixth embodiment of the present invention.

FIG. 9 is a sectional view showing the arrangement of an exposure apparatus used in the exposure method of the present invention.

FIG. 10 is a characteristic diagram showing secondary electron emission efficiency.

FIG. 11 is a sectional view showing the arrangement of an exposure mask according to the eighth embodiment of the present invention.

FIG. 12 is a process sectional view showing the method of manufacturing the exposure mask according to the eighth embodiment.

FIG. 13 is a process sectional view showing the method of manufacturing the exposure mask according to the ninth embodiment of the present invention.

FIG. 14 is a process sectional view showing the method of manufacturing the exposure mask according to the tenth embodiment of the present invention.

FIG. 15 is a process sectional view showing the method of manufacturing the exposure mask according to the eleventh embodiment of the present invention.

FIG. 16 is a sectional view showing the arrangement of another exposure apparatus used in the exposure method of the present invention.

[Explanation of symbols]

201 ... Substrate 202 ... Mask pattern 203 ... Resist 204 ... Tungsten 205 ... SiO ₂ film 206 ... Amorphized region 207 ... Amorphous silicon 208 ... Impurity doped region 209 ... Single crystallized region 210 ... Selective epitaxial growth region 211 ... BeCu 212 ... BeO 213 ... Polycrystalline silicon 214 ... Light source 215 ... Illumination optical system 216 ... Projection optical system 217 ... Mask 218 ... Mask stage 219 ... Exposure substrate 220 ... Exposure substrate stage 221 ... Control system 222 ... Mask stage Control system 223 ... Exposed substrate stage control system 224 ... Mask side alignment mechanism 225 ... Exposed substrate side alignment mechanism 226a, b ... Alignment lens 227a, b, 227a ', b' ... Aperture

Continuation of the front page (56) Reference JP 62-229836 (JP, A) JP 61-216323 (JP, A) JP 53-54974 (JP, A) JP 53-29080 (JP) , A) JP 11-160495 (JP, A) JP 8-213305 (JP, A) JP 4-137519 (JP, A) JP 4-116916 (JP, A) JP 3-101214 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) H01L 21/027 G03F 1/16 G03F 7/20 H01J 37/305

Claims (9)

(57) [Claims] 1. A reflective charged particle beam exposure mask in which a charged particle beam emitted from a light source is irradiated and the charged particle beam obtained by this irradiation is irradiated to a substrate to be exposed, wherein a desired pattern portion is substantially formed. Is composed of a single crystal, and except for the desired pattern portion, the charged
Reflects the particle beam more than the desired pattern
A charged particle beam exposure mask, characterized in that it is composed of a material having a low rate . 2. The charged particle beam exposure mask according to claim 1, wherein a portion other than the desired pattern portion is made of an amorphous material. 3. The amorphous material comprises an amorphous semiconductor,
The charged particle beam exposure mask according to claim 2, comprising a conductive impurity. 4. The charged particle beam exposure mask according to claim 2, wherein the amorphous material is made of silicon oxide. Wherein said desired pattern portion charged particle beam exposure mask according to claim 1 to 4, characterized in that it consists of a semiconductor single crystal substrate. 6. The charged particle beam exposure mask according to claim 5, wherein the semiconductor single crystal substrate is made of silicon, germanium, or silicon germanium. 7. An exposure method in which a charged particle beam emitted from a light source is applied to the reflective charged particle beam exposure mask of claim 1, and the charged particle beam obtained by this irradiation is applied to a substrate to be exposed. An exposure method, wherein the charged particle beam with which the exposure mask is irradiated and a substantially single crystal portion of the exposure mask satisfy a Bragg condition. 8. The Bragg condition is satisfied by controlling at least one of energy, incident angle, emission angle, and mask attitude of a charged particle beam incident on the exposure mask. 7. The exposure method according to 7 . Claim 7, wherein removing at least a portion of unnecessary charged particle beam using a 9. aperture
The exposure method according to.