JP3353830B2 - Electron beam exposure mask, electron beam exposure apparatus and electron beam exposure method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electron beam exposure mask, an electron beam exposure apparatus, and an electron beam exposure method using these masks, which are mainly used for manufacturing semiconductor devices. In particular,
The present invention relates to an electron beam exposure mask suitable for proximity effect correction, an electron beam exposure apparatus, and an electron beam exposure method.

[0002]

2. Description of the Related Art In electron beam exposure, a proximity effect caused by scattered electrons in a resist layer and a substrate is used.
effect) greatly affects the dimensional accuracy of the pattern.
Therefore, the correction of the proximity effect is one of the very important elemental technologies.

At present, in a partial projection exposure method (cell projection lithography), which is the mainstream of the electron beam exposure method, a complicated calculation by a sequential calculation method using an exposure intensity distribution (EID) function or a pattern density method is required. An exposure compensation method is used.

On the other hand, in recent years, a scattering angle limiting type electron beam exposure method (Scat
tering with Angular Limitation in Projection Elect
In ronBeam Lithography, the correction of the proximity effect is performed by a compensation method applying the GHOST method (ghost method). The scattering angle limiting type electron beam exposure method creates a pattern of the entire chip to be exposed on a mask,
This is a division transfer method in which the image is transferred onto a wafer while being scanned.

[0005] As a mask used in this scattering angle limiting type electron beam exposure method, an electron beam transmissive membrane (hereinafter simply referred to as a “membrane”) that hardly scatters an electron beam,
For example, a mask in which a pattern made of an electron beam scatterer, for example, tungsten having a thickness of about 50 nm is formed on a silicon nitride film having a thickness of about 100 nm (hereinafter, referred to as a “scattering membrane mask”) is used. Exposure is performed with an electron beam transmitted through the membrane, and a pattern contrast is formed on the wafer by a difference in electron beam scattering between the membrane region and the scatterer region.

In the proximity angle correction in the scattering angle limiting type electron beam exposure method, a part of the electrons largely scattered by the scatterer on the scattering membrane mask is provided in a limiting aperture located at or near the crossover position. This is carried out by selectively passing the scattered electrons through the annular opening, blurring the scattered electrons to the extent of the backscattering diameter by spherical aberration and chromatic aberration of the objective lens, and irradiating the wafer as an auxiliary exposure beam. Such a proximity effect correction method has already been described in J. Vac.Sci.Technol.B 13 (6), 2504-2507 (19
95), reported by GPWatson et al.
Compared to the conventional GHOST method in which a reverse pattern of a pattern to be exposed is separately exposed, a feature is that auxiliary exposure is performed simultaneously with exposure of a pattern to correct a proximity effect. The ability to perform the auxiliary exposure simultaneously with the pattern exposure greatly contributes to the improvement of the throughput.

On the other hand, a mask used in the partial batch exposure method or an apparatus used in this method (partial batch exposure type electron beam exposure apparatus) uses an opening pattern formed on a substrate that does not transmit an electron beam, for example, a silicon substrate having a thickness of 20 μm or more. (Hereinafter referred to as “stencil mask”) is generally used.

However, as patterns become finer as semiconductor devices become more highly integrated, stencil masks made of such a thick substrate have caused the following problems. That is, in the manufacture of a mask, the thickness 20
It is difficult to accurately form an opening pattern on a silicon substrate with a thickness of at least μm, which causes variations in dimensions.In electron beam exposure, electron beams are absorbed by the mask and the mask generates heat, resulting in reduced durability. And the position of the mask fluctuates due to thermal expansion. In addition, since the acceleration voltage is required to be high in order to reduce the aberration of the electron optical system and improve the resolution, the thickness of the mask substrate tends to be thick, and these problems become more remarkable. Is coming.

When the thickness of the mask substrate is reduced, the dimensional accuracy of the opening pattern is increased and the amount of heat generated is reduced. However, an electron beam to be shielded originally passes through the mask substrate portion (non-opening portion). The areas of the resist that should not be exposed are exposed, reducing contrast and reducing resolution.

Therefore, in order to solve such a problem,
JP-A-10-97055 is characterized in that an opening pattern is formed on a relatively thin mask substrate, and an electron beam scattering layer for scattering electron beams transmitted through the mask is formed on the back surface of the mask. An electron beam exposure mask is disclosed. As this electron beam scattering layer, polycrystalline silicon,
Examples include a layer made of a polycrystalline material such as tungsten silicide, molybdenum silicide, and titanium silicide, and a layer having an uneven shape. It is described that by forming such an electron beam scattering layer, it is possible to prevent electrons transmitted through a pattern layer (non-opening substrate portion) of a mask from being scattered and incident on a wafer.

Japanese Patent Application Laid-Open No. 6-163371 discloses that an electron beam forming aperture used as a mask has a structure in which an opening is provided in a substrate thinner than the range of the electron beam, and an electron beam below the forming aperture is formed. There is disclosed an electron beam lithography apparatus in which an optical system is provided with a mechanism for transmitting electrons through the substrate of the shaping aperture (mask) and blocking scattered electrons. In the present invention, a mechanism for blocking electrons scattered through the substrate portion of the forming aperture is provided, that is, a limiting aperture plate having a small hole diameter is provided on the crossover surface, and only the electron beam passing through the mask opening is passed. The electrons scattered by the mask substrate are removed by the limiting aperture plate. As another mechanism for blocking, an energy filter is provided, and decelerating electrons that have passed through the mask substrate and have lost a part of the energy are bent and their path is removed by a limiting aperture.

Japanese Patent Application Laid-Open No. 6-163371 discloses that the above-mentioned forming aperture (mask) is an electron beam that irradiates a large area graphic transfer mask with a uniform electron beam and exposes a large area graphic at a time. A first problem which will be described later has in a mask used in a projection type lithography apparatus, that is, a mask in which a thin film relatively transparent to an electron beam is used as a support and a figure is formed with a heavy metal which largely scatters the electron beam. Is also described.

[0013]

As a problem of the prior art, a mask used in a scattering angle limiting type electron beam exposure method for forming a contrast by a difference in an electron beam scattering angle of the mask, that is, an electron beam which hardly scatters an electron beam. The scattering membrane mask in which the electron beam scatterer pattern is formed on the beam transmitting membrane has the following problems.

The first problem is that since the transmitted electrons are scattered even in the electron beam transmitting membrane portion, the energy distribution of the exposure electrons is widened, which causes chromatic aberration and beam sag. In order to suppress the beam sag, the convergence half angle must be reduced. However, when the convergence half angle is reduced, the Coulomb effect becomes remarkable, and as a result, the resolution decreases. In order to reduce the Coulomb effect, the beam current may be reduced, but in that case, the exposure time becomes longer and the throughput decreases. Thus, sufficient electron exposure performance was not obtained with the scattering membrane mask.

Further, as a second problem, the scattering membrane mask is formed by patterning a thin metal film such as tungsten having a thickness of about 50 nm on a very thin silicon nitride film having a thickness of about 100 nm. Difficult and low yield.

In addition to the above problems, a third problem in the above-described proximity effect correction is as follows.

If an underlayer pattern such as a wiring made of heavy metal such as tungsten is formed on the underlayer of the resist layer on the wafer surface, the exposed electrons are reflected or backscattered by the underlayer pattern. As a result, the underlayer pattern is formed. The degree of the proximity effect is different between the resist region on the unexposed region and the resist region on the base pattern formation region. In the conventional proximity effect correction method, it is difficult to adjust the auxiliary exposure amount to be different for each region according to the base pattern, and even such an attempt has not been made.

An object of the present invention is to provide a stencil type mask suitable for a scattering angle limiting type electron beam exposure method and capable of correcting proximity effect simultaneously with pattern exposure. Another object of the present invention is to provide a mask which is easy to manufacture, can form a mask pattern with high accuracy, and can perform pattern exposure with high resolution and high accuracy. In addition, it is another object of the present invention to provide a mask capable of optimally correcting the proximity effect according to a base pattern of a wafer. Also,
An object of the present invention is to provide an electron beam exposure apparatus and an electron beam exposure method which have high exposure performance with high resolution and pattern accuracy, and which can perform proximity exposure correction simultaneously with pattern exposure and have high throughput. It is still another object of the present invention to provide an electron beam exposure apparatus and an electron beam exposure method capable of performing optimal proximity effect correction according to a base pattern of a wafer.

[0019]

According to the present invention, pattern exposure is performed using a mask having a scattering region by a scattering contrast due to a difference in electron beam scattering, and at the same time, a part of the scattered electrons scattered by the mask is used. A mask used in a scattering angle limiting type electron beam exposure method that performs proximity effect correction by using a mask substrate having a scattering region thinner than half the range of an electron beam, wherein the scattering region is The present invention relates to an electron beam exposure mask including an area corresponding to a range of a back scattering diameter of exposure electrons, wherein an aperture pattern is formed by providing an opening in the scattering area. Further, the present invention relates to the mask for electron beam exposure, wherein the mask substrate is provided with an electron beam scattering layer at least in the scattering region of the mask substrate.

The present invention also relates to the above-mentioned mask, wherein the scattering region has a thickness changed in accordance with the backscattering contributed by the underlying pattern of the wafer.

According to the present invention, there is further provided an electron beam exposure mask having a central opening and a closed band-like opening surrounding the opening in order to control the amount of scattered electrons scattered by the mask. The present invention relates to a scattering angle limiting type electron beam exposure apparatus having a limited aperture and capable of performing proximity effect correction using a part of scattered electrons simultaneously with pattern exposure.

According to the present invention, pattern exposure is performed using a mask having a scattering region by a scattering contrast due to a difference in electron beam scattering, and at the same time, proximity effect correction is performed by utilizing a part of the scattered electrons scattered by the mask. In the scattering angle limiting type electron beam exposure method to perform, as the mask,
A scattering region thinner than half the range of the electron beam is formed on the mask substrate, and the scattering region is formed so as to include a region corresponding to the range of the back scattering diameter of the exposure electrons on the wafer. The present invention relates to an electron beam exposure method using a mask obtained by forming an opening pattern by providing an opening.

Further, the present invention relates to the electron beam exposure method, wherein the scattering region is changed in thickness in accordance with the backscattering contributed by the underlying pattern of the wafer.

[0024]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a preferred embodiment of the present invention will be described in detail.

First, the basic configuration of the present invention will be described with reference to the conceptual diagrams of FIGS. FIG. 1 shows the trajectories of some scattered electrons and exposure electrons, and FIG. 2 shows the trajectories of only exposure electrons. Exposure electrons passing through the mask 1 are converged by the first projection lens 2 and pass through the center opening of the limiting aperture 3 arranged at the crossover position, that is, the rear focal plane, and then the objective lens, An image is formed on the resist 6 on the wafer 5 by the two projection lenses 4. Here, the resist 6 shown in FIG. 1 is a negative type in which an irradiated portion remains, and shows a shape after development for explanation. The resist used in the present invention may be of a positive type. Further, the first projection lens and the second projection lens form a doublet optical system. On the other hand, most of the scattered electrons scattered by the mask 1 are shielded by the restricting aperture 3, and a part of the scattered electrons pass through a central opening and a closed-band opening formed so as to surround the periphery. The passed scattered electrons are blurred to the extent of the backscattering diameter by the spherical aberration and chromatic aberration of the second projection lens 4 (objective lens), and are irradiated on the wafer as an auxiliary exposure beam. Here, the central opening and the closed band-shaped opening are arranged concentrically, and the closed band-shaped opening may be a ring-shaped band, a rectangular band or a square band. Usually, a ring-shaped band is used, but a rectangular or square band may be used depending on the material of the aperture and the conditions of the manufacturing method. Usually, a rib for connecting the outer peripheral portion and the inner peripheral portion of the closed band-shaped opening is provided. However, the width of the rib is increased within a range where the desired proximity effect correction can be performed, and the closed band-shaped opening is partially formed. It may be a closed shape.

The intensity of the auxiliary exposure beam (auxiliary exposure amount in proportion thereto) is adjusted by the opening area of the closed aperture of the limiting aperture, and the degree of blur is adjusted by the distance of the closed aperture from the center of the limiting aperture. In the case of a band-shaped opening, it is adjusted by the size of the diameter. Since the opening area of the closed-band opening is larger than the opening at the center of the restricting aperture, the actual proximity effect correction substantially depends on the amount of scattered electrons passing through the closed-band opening.

Next, the basic principle of the proximity effect correction will be described with reference to FIGS. Here, in order to clarify the electron beam scattering region and the electron beam transmission region in which the electron beam is hardly scattered (hereinafter also referred to as “transmission region”), a description will be given here using a conventional scattering membrane mask.

FIG. 3A shows a scattering membrane mask, wherein 21 is a membrane and 22 is a scatterer. The region where the scatterers are formed is the scattering region, and the membrane region where the scatterers are not formed is the transmission region. FIG. 3 (b)
FIG. 3C shows the energy storage distribution on the wafer when the auxiliary exposure beam is not irradiated, that is, when the proximity effect correction is not performed, using the limiting aperture having no closed-band opening. FIG. 4 shows an energy storage distribution when a beam is irradiated, that is, when a proximity effect correction is performed. Βb in the figure is the backscattering diameter. If the energy of the forward scattered electrons is 1, the energy of the back scattered electrons becomes the reflection coefficient η, and the corresponding auxiliary exposure rate δ is represented by η / (1 + η).

By blurring the auxiliary exposure beam to about the backscattering diameter βb, ie, about L, the stored energy that has dropped near the boundary line in FIG.
It can be made constant as shown in FIG. As a result, the dimensional accuracy of the pattern can be improved. In addition,
The larger the width of the closed-band opening of the limiting aperture (the larger the opening area), the larger the auxiliary exposure amount, and the larger the diameter of the closed-band opening, the larger the aberration and the greater the degree of blurring.

FIG. 4 shows that the scattering membrane mask shown in FIG.
That is, a case where a pattern having a pattern density of 50% is formed is shown. As is apparent from FIG. 4, the proximity effect correction is possible even if the pattern density changes, and there is no need to separately perform correction exposure for an inverted pattern requiring complicated calculation for each pattern unlike the conventional GHOST method. You can see that.

The basic structure of the electron beam exposure apparatus of the present invention and the basic principle of proximity effect correction have been described above. Next, the electron beam exposure mask of the present invention will be described with reference to FIG. FIG. 5A shows a line-and-space transfer pattern 31, and FIG. 5B shows a cross-sectional view of a mask corresponding to the line AB in FIG. 5A. Βb in the figure indicates the backscattering diameter. Note that the transfer pattern size and the mask size are set to 1: 1 in order to easily understand the correspondence between the transfer pattern and the mask.

The electron beam exposure mask of the present invention is a mask in which an opening is provided in a substrate made of silicon or the like and an opening pattern is formed. This substrate has a scattering region thinner than an electron beam range. And the opening pattern is formed in the scattering region. The scattering region includes a region corresponding to the range of the backscattering diameter βb of the exposure electrons on the wafer.

The opening pattern is formed in a scattering region thinner than the range of the electron beam on the mask substrate. Thereby, the electrons passing through the opening are irradiated on the wafer as exposure electrons,
Electrons transmitted through a thin portion (scattering region) of the substrate become scattered electrons, and most of the electrons are shielded by the limiting aperture at the crossover position, thereby forming a graphic contrast on the wafer. On the other hand, a part of the scattered electrons that have passed through the closed aperture of the limiting aperture is irradiated on the wafer as an auxiliary exposure beam, and the proximity effect correction is performed. The thickness of the scattering region of the mask of the present invention is set as follows in order to sufficiently transmit and scatter the electron beam. The upper limit of the thickness of the scattering region needs to be smaller than the range of the electron beam (penetration length), and is preferably smaller than half the range of the electron beam. Furthermore, the mean free path is preferably 25 times or less, more preferably 15 times or less, and even more preferably 10 times or less. The lower limit of the thickness of the scattering region is required to be thicker than the mean free path of the electron beam, preferably 1.5 times or more, more preferably 2 times or more of the mean free path,
More preferably, it is three times or more. Since the range of the electron beam and the mean free path greatly depend on the mask substrate material and the acceleration voltage, the thickness of the scattering region is appropriately set in consideration of the mask substrate material and the acceleration voltage. The mean free path is Jpn.J.
Appl. Phys., 10 (1971) p.678. Further, the thickness of the scattering region of the mask substrate set as described above is set so that the beam contrast is preferably 90% or more, more preferably 95% or more, and further preferably 98% or more. In some cases, it is necessary to consider a manufacturing point. For example, in a silicon substrate, the aspect ratio of the opening is desirably 10 or less, and the thickness is set in consideration of this point. In the mask of the present invention, since the opening pattern is formed in the thin scattering region, the processing accuracy of the opening pattern is improved, and since the electron beam almost transmits through the scattering region, heat generation of the mask due to electron beam irradiation can be suppressed. It also has advantages.

However, if the scattering area of the mask substrate is too thin, the mechanical strength of the mask is lost. Therefore, as shown in FIG. 5B, the mechanical strength of the mask is maintained in areas other than the scattering area. The thickness of the scattering region is preferably larger than that of the scattering region, and more preferably twice or more the thickness of the scattering region. When a silicon substrate is used as the mask of the present invention, for example, when the acceleration voltage is 100 kV (the range of the electron beam is about 67 μm), the range of the thickness of the scattering region of the silicon substrate is, for example, 0.2 to 0.2 μm. It can be in the range of 2 μm. The lower limit of the thickness of the scattering region of the silicon substrate is preferably 0.2 μm or more, more preferably 0.3 μm or more, further preferably 0.4 μm or more.
6 μm or more is more preferable. As a maximum, 5 micrometers or less are preferred, 3 micrometers or less are more preferred, and 2 micrometers or less are still more preferred.

Further, since the scattering angle of the scattered electrons becomes smaller as the scattering region of the mask substrate becomes thinner, the scattered electrons having the smaller scattering angle do not pass through the central opening of the limiting aperture so that the contrast is not lowered. Set the thickness appropriately.
Alternatively, in order to increase the scattering angle, an electron beam scattering layer may be laminated on the scattering region of the mask substrate. The electron beam scattering layer can be formed on the back surface, the front surface, or both surfaces of the mask. The thickness of the electron beam scattering layer is appropriately set so that electrons are sufficiently transmitted and sufficiently scattered at the same time, and dimensional accuracy can be ensured. For example, when using a heavy metal such as tungsten, the thickness is preferably 1 μm or less from the viewpoint of processing accuracy, and preferably 10 nm or more from the viewpoint of electron scattering. As materials for the electron beam scattering layer, tungsten,
Heavy metals such as chromium, molybdenum, titanium, gold, platinum,
Polycrystalline materials such as polycrystalline silicon, tungsten silicide, molybdenum silicide, and titanium silicide can be given. By forming such an electron beam scattering layer, the mask strength can be improved. Furthermore, when the electron beam scattering layer is provided, the energy loss of the scattered electrons occurs, and the scattering angle increases and the density of the scattered electrons decreases. As a result, the dimensional accuracy of the annular aperture of the restriction aperture can be ensured.

A further important point of the electron beam exposure mask of the present invention is that the mask substrate region corresponding to the range of the backscattering diameter of the exposure electrons on the wafer (hereinafter referred to as the "backscattering substrate region") is also an electron beam. That is, the above thickness which is smaller than the range. That is, it is necessary to form the scattering region of the mask substrate so as to include the back scattering substrate region. Unless electrons are transmitted or sufficient scattered electrons are not emitted in the backscattering substrate region, the proximity effect correction cannot be sufficiently performed. As described above, in order to correct the proximity effect, scattered electrons need to be blurred to the extent of the backscattering diameter and irradiated as an auxiliary exposure beam. Therefore, at least the mask substrate region corresponding to the range of the backscattering diameter, that is, the backscattering substrate Scattered electrons need to be emitted from the region.

Next, another embodiment of the electron beam exposure mask of the present invention will be described with reference to FIG. FIG. 6 (a)
FIG. 6B shows a line-and-space transfer pattern 31 and a base pattern 32 made of a substance having a higher density than the wafer material, for example, a gate or a wiring in a cell portion, a buried portion of a contact hole, and the like. A of (a)
FIG. 3 shows a cross-sectional view of the mask corresponding to line B. Beta _bSi in the figure shows the back-scattering diameter due to the silicon substrate, beta _bW illustrates yet backscattering diameter underlying pattern contributed. Note that the transfer pattern size and the mask size are set to 1:
It is set to 1. Heavy substances that make up the underlying pattern include tungsten, copper, tantalum, cobalt, titanium,
Heavy metals such as molybdenum; The line-and-space transfer pattern 31 corresponds to, for example, an upper layer pattern of a bit line or an aluminum wiring. In the present embodiment, since the backscattering coefficient η backscattered diameter beta _b is considering different depending on the kind of the material, allows more precise control of the transferred pattern size.

In this embodiment, regions having different mask thicknesses are formed in consideration of not only the substrate material but also the backscattering contributed by the underlying pattern. The thicknesses of the regions having different mask thicknesses are set according to the backscattering coefficient of the substrate material and the underlying pattern. The thickness of the region having a different mask thickness is set not only in the region corresponding to the formation range of the base pattern but also in the region corresponding to the range of the back scattering diameter to which the base pattern contributes. As shown in FIG. 6, the thickness of the mask area base pattern 32 is thinnest contributes region R _W backscattered, underlying pattern 32 does not contribute R
_Si is formed slightly thicker. Region R _W and the region R _Si is thinner than Fei enough for the electron beam to scatter by transmitting an electron beam, the other region R _SP is formed thicker than those for maintaining the mechanical strength of the mask. Region R _W is region R _Si
The reason why the film is formed thinner is to irradiate a larger amount of auxiliary exposure light onto the wafer in order to compensate for an increase in energy accumulation due to backscattering contributed by the underlying pattern. In this way, by reducing the thickness of the mask substrate region corresponding to the backscattering region to which the underlying pattern contributes, it becomes possible to correct the proximity effect to which the backscattering due to the underlying pattern contributes, and the dimensional accuracy of the resist pattern after development is further improved. Further improve.

In the above-described embodiment shown in FIG. 6, the scattered electrons are partially controlled by partially changing the thickness of the scattering region of the mask substrate in accordance with the backscattering contributed by the underlying pattern. The exposure amount of the auxiliary exposure beam irradiated above was partially adjusted. As another method of partially adjusting the auxiliary exposure amount, instead of changing the thickness of the scattering region of such a mask substrate, the auxiliary exposure amount is partially adjusted by providing an electron beam scattering layer in the scattering region. May be controlled. For example, in FIG. 6, the thickness of the entire scattering region (R _W , R _Si ) is set to an optimum thickness for the region R _W corresponding to the back scattering region to which the underlying pattern contributes, and the back scattering region to which the underlying pattern contributes. Region R _W corresponding to
An electron beam scattering layer is provided in the other scattering regions R _Si . The electron beam scattering layer increases the scattering angle of the scattered electrons and reduces the number of electrons passing through the restriction aperture. As a result, the amount of auxiliary exposure can be partially reduced. This electron beam scattering layer can be made of the same material and thickness as in the embodiment shown in FIG.

The electron beam exposure mask of the present invention can be manufactured by applying various conventional stencil mask manufacturing methods used in a partial batch exposure type electron beam exposure apparatus.

Hereinafter, an example of a conventional mask manufacturing method will be described with reference to FIG. 7, and then an embodiment of a method of manufacturing an electron beam exposure mask according to the present invention will be described.

First, as shown in FIG. 7A, a resist layer is formed on a bonded wafer 44 (Si / SiO ₂ / Si) by lithography and patterned. Reference numerals 41 and 43 indicate Si layers, and reference numeral 42 indicates an SiO ₂ layer.

Next, as shown in FIG. 7B, the Si layer 43 is dry-etched using the patterned resist layer 45 as a mask.

Subsequently, after removing the resist layer, FIG.
As shown in FIG. 7, a silicon nitride film 46 is formed as a protective film at the time of wet etching in a later step. Next, a resist layer is formed on the back surface and patterned to form a resist layer 47 having an opening window in the center.

Next, as shown in FIG. 7D, the silicon nitride film and the Si layer 41 exposed at the opening are wet-etched with an alkali solution such as a potassium hydroxide solution.
The tapered shape of the formed Si layer 41 depends on the plane orientation of the Si layer. Subsequently, the exposed SiO ₂ film is removed by wet etching.

Thereafter, as shown in FIG. 7E, the resist layer 47 and the protective film 46 are removed, and gold, platinum,
A conductive film 48 made of palladium or the like is formed by a sputtering method or the like.

The mask for electron beam exposure of the present invention can be manufactured by applying the above-mentioned conventional manufacturing method.

In order to partially change the thickness in the scattering region of the mask, the mask can be formed by irradiating an ion beam from the back surface and selectively removing the Si layer after forming the mask. Alternatively, after the step shown in FIG. 7D, after removing the resist layer 47 and the protective film 46 and before forming the conductive film 48 on the surface portion, the surface is selectively irradiated with an ion beam to selectively form the Si layer. It may be removed.

As another method, for example, after the step shown in FIG. 7B, the resist layer 45 is removed, and then a resist layer is formed and patterned by lithography (FIG. 8A). Dry etching is performed using the patterned resist layer 49 as a mask to form a partially thin region (FIG. 8B). Alternatively, after the step shown in FIG. 7D, the resist layer 47 and the protective film 46 are formed.
Is removed, and before the conductive film 48 is formed on the surface portion, a resist layer is similarly formed by lithography and patterned, and then dry-etched using the patterned resist layer as a mask to partially remove the thickness. May be formed.

The provision of the electron beam scattering film partially in the scattering region of the mask can be performed, for example, as follows.

After the step shown in FIG.
After removing the protective film 46 and before forming the conductive film 48 on the surface portion, a resist layer is formed by lithography and patterned (FIG. 9A), and then an electron beam is formed on the patterned resist layer 50. A scattering film 51 is formed (FIG. 9B), and the electron beam scattering film 51 on the resist layer 50 is formed.
Is removed together with the resist layer 50 to partially form an electron beam scattering film (FIG. 9C).

As another method, for example, after the step shown in FIG. 7D, the resist layer 47 and the protective film 46 are removed, and before the conductive film 48 is formed on the surface portion, the electron beam is applied to the surface portion. A scattering film 51 is formed (FIG. 10A), and then a resist layer is formed by lithography and patterned (FIG. 10B). Thereafter, the patterned resist layer 50 is used as a mask to etch unnecessary electrons. The beam scattering film is removed, and subsequently, the resist layer 50 is removed to partially form an electron beam scattering film (FIG. 10C).

[0053]

As is apparent from the above description, according to the present invention, there is provided a stencil-type mask suitable for a scattering angle limiting type electron beam exposure method and capable of correcting proximity effect simultaneously with pattern exposure. Can be. The mask of the present invention is easy to manufacture, can form a mask pattern with high precision, and enables high-resolution and high-precision pattern exposure. Further, it is possible to provide a mask capable of optimally correcting the proximity effect according to the underlying pattern of the wafer. Also,
According to the present invention, it is possible to provide an electron beam exposure apparatus and an electron beam exposure method that have high exposure performance with high resolution and pattern accuracy, and that can perform proximity exposure correction simultaneously with pattern exposure and have high throughput. Further, it is possible to provide an electron beam exposure apparatus and an electron beam exposure method capable of performing optimal proximity effect correction in accordance with a base pattern of a wafer.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram for explaining a basic configuration of the present invention.

FIG. 2 is a conceptual diagram illustrating a basic configuration of a scattering angle limiting type electron beam exposure apparatus according to the present invention.

FIG. 3 is a conceptual diagram for explaining a basic principle of proximity effect correction in the present invention.

FIG. 4 is a conceptual diagram for explaining a basic principle of proximity effect correction according to the present invention.

FIG. 5 is an explanatory diagram of a configuration of an electron beam exposure mask of the present invention.

FIG. 6 is an explanatory diagram of a configuration of an electron beam exposure mask of the present invention.

FIG. 7 is a process cross-sectional view for describing a conventional method for manufacturing an electron beam exposure mask.

FIG. 8 is a process cross-sectional view for explaining the method for manufacturing an electron beam exposure mask of the present invention.

FIG. 9 is a process cross-sectional view for explaining the method for manufacturing an electron beam exposure mask of the present invention.

FIG. 10 is a process sectional view for illustrating the method for manufacturing the mask for electron beam exposure according to the present invention.

[Explanation of symbols]

Reference Signs List 1 mask 2 first projection lens 3 limiting aperture 4 second projection lens 5 wafer 6 resist 21 membrane 22 scatterer 31 transfer pattern 32 base pattern 41, 43 Si layer 42 SiO ₂ layer 44 bonded wafer 45, 47, 49 , 50 resist layer 46 protective film (silicon nitride film) 48 conductive film 51 electron beam scattering film

Continuation of the front page (56) References JP-A-8-250414 (JP, A) JP-A-8-124833 (JP, A) JP-A-11-176720 (JP, A) JP-A 8-45808 (JP) JP-A 7-297097 (JP, A) JP-A 9-134701 (JP, A) JP-A 8-314121 (JP, A) JP-A 8-22940 (JP, A) 7-142360 (JP, A) JP-A-6-163371 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01L 21/027 G03F 1/16 G03F 7/20

Claims (10)

(57) [Claims] 1. A method of performing pattern exposure using a mask having a scattering region by a scattering contrast due to a difference in electron beam scattering, and simultaneously performing a proximity effect correction using a part of the scattered electrons scattered by the mask. A mask used in an angle limiting type electron beam exposure method, wherein the mask substrate has a scattering region thinner than half the range of the electron beam, and the scattering region is in a range of a back scattering diameter of exposure electrons on a wafer. An electron beam exposure mask comprising a region corresponding to the above, and an opening pattern formed by providing an opening in the scattering region. 2. A region other than the scattering region is at least twice the thickness of the scattering region so that the mechanical strength of the mask can be maintained.
The electron beam exposure mask according to claim 1, wherein the mask is formed to a thickness of: 3. The electron beam exposure mask according to claim 1, wherein an electron beam scattering layer is provided on at least the scattering region of the mask substrate. 4. The scattering region has a thickness changed according to backscattering contributed by a base pattern of a wafer.
Or the mask for electron beam exposure according to 2. 5. The electron beam exposure mask according to claim 1, wherein said scattering region is provided with an electron beam scattering layer in a region other than a region corresponding to a back scattering region to which a base pattern of a wafer contributes. 6. The electron beam exposure mask according to claim 1, wherein said mask substrate is made of silicon. 7. A mask according to any one of claims 1 to 6, and an opening at a central portion and a closed band surrounding the opening for controlling a passing amount of scattered electrons scattered by the mask. An electron beam exposure apparatus having a limited scattering angle, having a limiting aperture having an opening formed therein, and capable of performing proximity effect correction using a part of scattered electrons simultaneously with pattern exposure. 8. A method for performing pattern exposure using a mask having a scattering region by a scattering contrast due to a difference in electron beam scattering, and performing proximity effect correction using a part of the scattered electrons scattered by the mask. In the angle limiting type electron beam exposure method, a half of an electron beam range is provided on the mask substrate as the mask.
A thinner scattering region is formed, the scattering region is formed so as to include a region corresponding to the range of the back scattering diameter of the exposure electrons on the wafer, and an opening is formed in the scattering region to form an opening pattern. An electron beam exposure method, comprising using a mask. 9. The electron beam exposure method according to claim 8, wherein said scattering region changes its thickness in accordance with backscattering contributed by a base pattern of a wafer. 10. The electron beam exposure method according to claim 8, wherein the scattering region is provided with an electron beam scattering layer in a region other than a region corresponding to a back scattering region to which a base pattern of a wafer contributes.