JP2000021763A - Method of exposure and aligner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of exposure and an aligner in which arbitrary high-resolution patterns are produced by a double exposure which is obtained with a fine line pattern exposure and a rough pattern exposure. SOLUTION: The process comprises an exposure step, in which periodic patterns are exposed on a photoreceptive substrate and a rough exposure step in which rough patterns of a resolution lower than that of the relevant pattern are exposed on the photoreceptive substrate, and latent images generated by this process at the same positions of the photoreceptive substrate are overlapped. The fine line exposure step and the rough exposure step need not be in the same sequence as in the figure, i.e., the rough exposure step may be done first, and in the case of multiple exposures, the steps may be done alternately.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exposing method and an exposing apparatus, and more particularly, to exposing a photosensitive substrate with a fine circuit pattern, for example, a semiconductor chip such as an IC or LSI, a display element such as a liquid crystal panel, a magnetic head, and the like. It is suitable for use in the manufacture of various devices such as a detection device and an imaging device such as a CCD.

[0002]

2. Description of the Related Art Conventionally, when manufacturing ICs, LSIs, liquid crystal elements, and the like using photolithography technology, a photoresist or the like is applied to a pattern of a photomask or reticle via a projection optical system. A projection exposure apparatus that performs projection exposure on a substrate such as a wafer or a glass plate is used.

[0003] High integration of semiconductor devices such as ICs, LSIs, liquid crystal elements and the like is accelerating more and more, and the demand for fine processing of semiconductor wafers is accompanied by miniaturization of patterns, that is,
Higher resolution.

[0004] In response to such demands, projection exposure technology, which is currently the center of fine processing technology, is being improved to form an image having a size of 0.1 μm or less over a wide range. A method and an apparatus for forming a circuit pattern of 80 nm or less are desired.

FIG. 24 is a schematic diagram showing the principle of a conventional exposure apparatus.
Shown in In the figure, 251 is an excimer laser light source 252 is an illumination optical system, 253 is illumination light, 254 is a mask, 255 is an object side exposure light, 256 is a projection optical system, 257 is an image side exposure light, and 258 is a photosensitive substrate. , 259 represent a substrate stage for holding the photosensitive substrate.

In this exposure apparatus, first, laser light emitted from an excimer laser light source 251 is guided to an illumination optical system 252 so as to become illumination light 253 having a predetermined light intensity distribution, light distribution, and the like. It is adjusted and enters the mask 254.

On the mask 254, a pattern to be formed on the photosensitive substrate is formed by using a chrome or the like after a predetermined magnification conversion, and the illumination light 253 is transmitted and diffracted to expose the object side exposure light 255. Becomes Projection optical system 256 is incident exposure light 255
Is converted into image-side exposure light 257 that forms an image on a photosensitive substrate with a predetermined magnification and sufficiently small aberration.

The image side exposure light 197 converges on the photosensitive substrate 258 with a predetermined NA (numerical aperture = sin θ) as shown in the enlarged view at the bottom, and forms an image. The substrate stage 259 has a function of controlling the relative positions of the photosensitive substrate and the projection optical system by stepping when a plurality of patterns are formed on the photosensitive substrate.

[0009]

(Problems and Problems of Projection Exposure) However, as described above, in a projection exposure type exposure apparatus using a currently mainstream excimer laser, 0.1%
There is a problem that it is difficult to form a pattern of less than μm.

[0010] These problems will be described below with reference to examples. First, the projection optical system has limitations due to trade-offs in optical resolution and depth of focus due to the wavelength used. The resolution and depth of focus of the resolution pattern by the projection exposure
It is known to be represented by the Rayleigh equation of equations (1) and (2).

R = K ₁ λ / NA DOF = K ₂ λ / NA ² where λ is the wavelength, NA is the numerical aperture representing the brightness of the optical system described above, and K ₁ and K ₂ are the photosensitive substrate. It is a constant determined by the development process characteristics and the like. 5-0. Take a value of about 7.

From the equations (1) and (2), it is necessary to “short wavelength” to decrease the wavelength λ or “to increase NA” to increase the NA in order to increase the resolution R to a small value. is there. However, at the same time, the depth of focus DOF required as the performance of the projection optical system must be maintained at a certain value or more. For this reason, it is impossible to increase the NA higher than a certain level, and after all, shortening the wavelength is the only solution.

However, as the wavelength is shortened,
Another serious problem arises from this formula.

The biggest problem is that there is no glass material available for the projection optical system.

As the current projection exposure system, an optical system including a refraction system, that is, a lens, can sufficiently withstand the actual mounting of the apparatus due to the aberration amount, processing accuracy, controllability, and the like. The transmittance of a glass material used for a lens is almost zero in a short wavelength region of a general glass material, that is, in a deep ultraviolet region. Quartz and the like exist as glass materials manufactured using a special manufacturing method for an exposure apparatus, but their transmittance also sharply decreases to 193 nm or less,
0. It is very difficult to develop a practical glass material in the region of about 150 nm or less corresponding to a pattern of 1 μm or less. Furthermore, the existence of a glass material that satisfies a plurality of conditions such as durability, uniformity of refractive index, optical distortion, workability, and the like other than the condition of the transmittance is feared.

Thus, in the conventional projection exposure, the expression (1)
In order to expose the pattern depending on (2), it is necessary to shorten the wavelength, which causes a problem that no glass material is present. Exposure of 1 μm or less cannot be realized.

For example, an F2 laser having a wavelength of 157 nm is being used as a next-generation excimer laser light source. However, as described above, it is extremely difficult to use a refraction element or lens at this wavelength, and the projection optical system is difficult to use. A catadioptric system including a reflecting element, ie a mirror, or a total reflection system with only a mirror is advantageous. However, in a projection optical system including such a reflective element, there is a problem that it is difficult to configure a large NA due to overlapping optical paths due to reflection.

As described above, in order to form a practical circuit pattern with an exposure apparatus using an excimer laser, it is necessary to use an exposure apparatus. Difficulties have arisen in performing exposures below 1 μm.

On the other hand, 0. As an exposure system that can achieve 1 μm, batch exposure using proximity using X-rays with a wavelength of about 1 nm has been proposed, but it is difficult to control the gap between the mask and the wafer and to create a 1: 1 mask with an exposure of 80 nm or less. It is becoming.

Further, an electron beam exposure apparatus using an electron beam has been proposed, and although a performance exceeding 80 nm has actually been realized as a resolution, there is a problem that throughput, which is an important performance of the exposure apparatus, is low. is there.

As described above, various types of exposure aiming at 100 nm or less have respective advantages and disadvantages. Although high resolution of 100 nm or less can be achieved, various exposures of 80 nm or less form various patterns of a real circuit, and the However, each of the exposure apparatuses for producing the above has problems and is insufficient.

The present invention provides an exposure method capable of forming a pattern with a line width of 80 nm or less by appropriately using an exposure method that combines fine line exposure and rough exposure, and a line width of 80 nm or less using the same. It is intended to provide an exposure apparatus capable of performing actual circuit pattern exposure.

[0023]

An exposure method according to the present invention comprises: (1-1) an exposure step of exposing a periodic pattern to a photosensitive substrate; and exposing a rough pattern having a lower resolution than the pattern to the photosensitive substrate. And a latent image generated on the same portion of the photosensitive substrate by the exposure step.

In particular, (1-1-1) In the two exposure steps, light having different wavelengths and / or particle beams having different wavelengths are used, and the photosensitive substrate is provided with light having different wavelengths and / or different wavelengths. It is characterized by having exposure sensitivity to particle beams.

(1-1-2) The exposure step has a wavelength of 300
Use of projection exposure and / or two-beam interference exposure with ultraviolet light of nm or less.

(1-1-3) The exposure step uses electron beam exposure.

(1-1-4) The exposure step uses projection exposure and / or two-beam interference exposure with soft X-rays having a wavelength of 30 nm or less.

(1-1-5) The rough exposure step has a wavelength of 30 n
Use projection exposure with soft X-rays of m or less.

(1-1-6) The rough exposure step has a wavelength of 30
Use projection exposure with ultraviolet light of 0 nm or less.

(1-1-7) The rough exposure is a multi-level exposure.

(1-1-8) The rough exposure is an electron projection exposure.

(1-1-9) The rough exposure comprises multiple exposure.

(1-1-10) The rough exposure step uses a mask having a pattern region having a plurality of transmittances.

(1-1-11) The rough exposure step uses a mask having an area having a pattern having a line width equal to or less than the line width that can be resolved under the exposure conditions of the rough exposure step, and the pattern is not resolved. The light intensity of the exposure image is multi-valued.

(1-1-12) The exposure step is a multi-value exposure.

(1-1-13) The exposure step comprises multiple exposure. And so on.

The exposure apparatus of the present invention is characterized in that (2-1) the pattern on the mask is transferred to a photosensitive substrate by using the exposure method of the constitution (1-1).

The method for manufacturing a device according to the present invention comprises the following steps: (3-1) After exposing a pattern on a mask surface onto a wafer surface using the exposure method of the constitution (1-1), the wafer is subjected to a developing process. The device is manufactured via

(3-2) After exposing the pattern on the mask surface to the wafer surface using the exposure apparatus of the configuration (2-1), the device is manufactured through the developing process of the wafer. It is characterized by.

In the present invention, "multiple exposure" means "exposure of the same area on the photosensitive substrate to light patterns different from each other without passing through a developing process".

[0041]

DESCRIPTION OF THE PREFERRED EMBODIMENTS (Principle of the Invention) First, FIGS.
The principle of multiple exposure of the exposure method of the present invention will be described with reference to FIG.

FIG. 1 shows a basic flow of the exposure method of the present invention.
It is a figure showing a chart. The figure shows a fine line exposure step (fine line exposure), a rough exposure step (rough exposure), and a development step, which constitute the present exposure method, and the flow thereof.

The fine line exposure step and the rough exposure step do not need to be in the order shown in this figure, and the rough exposure step may be performed first. In the case of performing a plurality of exposures, the exposure can be performed alternately.

Further, an alignment step or the like can be appropriately inserted between the exposure steps to increase the image forming accuracy, and the present invention is not limited to the steps shown in FIG.

FIG. 10 is a diagram showing an example of the configuration of the exposure apparatus of the present invention. Next, the principle of how the effects of the present invention are realized by these steps will be described.
When the flow of FIG. 1 is used, first, a fine line pattern is periodically exposed on a photosensitive substrate by fine line exposure.

FIG. 2 is a schematic diagram showing this periodic fine line pattern. The numbers in the figure represent the exposure amount, that is, the hatched portions represent the exposure amount 1 and the white portions represent the exposure amount 0. When developing only such a fine line pattern, the exposure threshold of the photosensitive substrate is usually set between 0 and 1.

FIG. 3 shows the dependency of the film thickness after development on the exposure amount and the exposure threshold value Eth for the resist portion of the photosensitive substrate in the positive type and the negative type. The film thickness after development is 0 when the positive type is equal to or more than the exposure threshold value Eth, and when the negative type is equal to or less than the exposure threshold value Eth.

FIG. 4 is a schematic diagram showing a state in which a lithography pattern is formed through the development and etching processes when such exposure is performed. In the present invention, unlike the usual exposure sensitivity setting, when the maximum exposure amount in fine line exposure is 1, the exposure threshold value of the resist is set to be larger than 1.

In such a photosensitive substrate, as shown in FIG. 2, when an exposure pattern subjected to only fine line exposure is developed, the exposure amount is insufficient, and although the film thickness varies slightly, the film thickness is small.
No portion becomes 0, and no pattern is formed.

This can be regarded as the disappearance of the fine line exposure pattern. (It is to be noted that the description will be made using an example in which a negative type is used. The essence does not depend on whether it is a negative type or a positive type, it is common to both, and can be arbitrarily selected according to other requirements.)

The principle of the multiple exposure according to the present invention is that, as described above, a high-resolution pattern that is apparently lost only by fine line exposure is fused with a pattern by rough exposure, and selectively restored by the fusion effect. That is, the lithography pattern can be reproduced.

Next, an example of the pattern forming method according to the embodiment of the present invention will be described by adding rough exposure.

In order to expose the fine line pattern shown in FIG. 2 (fine line exposure step), in this embodiment, an exposure apparatus using light from an F2 laser as the exposure light shown in FIG. 11 was used.

In the figure, reference numeral 211 denotes a mask, 212 denotes a sub mirror, 213 denotes a main mirror, 214 denotes a wafer, 215 denotes a wafer stage, and 216 denotes a state of light transmission through an aperture stop. Also, for simplicity, an image-forming light beam only on the optical axis is shown.

In the figure, a mask 21 illuminated with exposure light
The light from 1 is reflected by the secondary mirror 212 and the primary mirror 213 in order,
The light is condensed on the wafer 214, and two light flux interference fringes are formed on the surface.

The projection optical system of this exposure apparatus is a Schwarzschild optical system, and the center of an NA (aperture stop) is shielded from light by a secondary mirror. In the present embodiment, the so-called central part of the pupil of the optical system is used as a filter for cutting the zero-order light of the diffracted light by the mask 211, and a periodic pattern having a pitch twice the pitch of the target fine line pattern is used. A fine line pattern was exposed on the image plane using two-beam interference of + 1st-order light and -1st-order light using a mask having.

As the resist, a chemically amplified resist having sensitivity to both laser light having a wavelength of 157 nm and X-rays of SR light described below was used. In addition, a resist other than the chemically amplified type can be used as long as it has sensitivity to both of the above.

FIG. 12 is a schematic diagram showing a state in which two-beam interference exposure is performed to expose a fine line pattern by this exposure apparatus. On the mask 211, a periodic pattern (converted to magnification) corresponding to twice the pitch of the target fine line pattern is formed. The reason the pitch is doubled is
In this exposure apparatus, the central part of the aperture stop (pupil) is shielded as shown by an aperture stop unit 216 in the figure, so that the zero-order light of the light diffracted by the periodic pattern on the mask is shielded. , + 1st-order light and -1st-order light, thereby forming a pattern having a pitch twice as large as that of normal three-beam interference exposure.

The wavelength is 157 nm, and the NA of the outermost light beam is 0. 6 and the resolution limit by two-beam interference exposure is 65 nmL & S.

In this embodiment, the projection optical system is constituted by a total reflection system. However, it goes without saying that the same effect can be obtained by a catadioptric system including a refraction element or a total refraction system.

Next, the rough exposure step in this embodiment will be described. FIG. 7A shows an exposure pattern in rough exposure.
It is.

In this embodiment, the periodic pattern formed by the above-mentioned F2 exposure apparatus is 65 nmL & S, but the resolution of the exposure pattern in the rough exposure is 130 nm, which is half of the fine line exposure pattern. FIG. 7A shows a state in which a line width pattern twice that of fine line exposure is formed by rough exposure.

In the present embodiment, an X-ray equal magnification proximity exposure apparatus shown in FIG. 13 was used for this rough exposure.

In FIG. 13, reference numeral 221 denotes an SR (synchrotron radiation) light source; 222, an SR light; 223, a beam shaping mirror;
4 is shutter, 225 is shutter control unit, 226
Is a mask, 227 is a wafer, 228 is a wafer stage, 229
Indicates a beryllium window, respectively.

The SR light 222 emitted from the SR (synchrotron radiation) generator 221 as an X-ray source is a SiC cylindrical mirror (convex surface) having a radius of curvature of approximately 60 m and placed at a position of approximately 3 m from the emission point. Mirror) 223 almost oblique incidence angle
It is incident at 15 mrad.

The SR light 222 reflected by the mirror 223 passes through a transmission mask 226 as an original plate having a desired pattern formed of an X-ray absorber formed on an X-ray transmission film.
The substrate (wafer) 227 having a desired pattern shape and coated with a resist as a photosensitive material is irradiated.

On the upstream side of the mask 226, a shutter 224 for controlling the exposure time over the entire exposure area is provided. The shutter 224 is driven by a shutter drive unit 225 controlled by a shutter control unit (not shown).

The thin film 229 of Be having a thickness of about 10 μm is a boundary of a chamber (not shown). The upstream side (light source side) of the thin film is under ultra-high vacuum, and the downstream side (wafer side) is under reduced pressure He.

In this embodiment, the above-mentioned X-ray exposure apparatus is used. However, as an exposure apparatus capable of performing rough exposure with a resolution of a wavelength of 130 nm, a super-resolution such as an ArF excimer laser or a phase shift mask is used. There are EB (electron beam) exposure equipment, EUV exposure equipment (soft X-ray reduction projection exposure equipment using a multilayer mirror), etc.
These can be used as appropriate.

Assuming that the exposure of this pattern is performed without the development step after the fine line exposure of the fine line pattern of FIG. 5, the distribution of the total exposure amount is as shown in FIG. 7B. Here, the exposure ratio between the fine line exposure and the rough exposure is 1: 1. Since the exposure threshold value Eth is set between 1 and 2 as in the case of the pattern disappearance in FIG. 6, the pattern shown in FIG. 7B is formed. This pattern has a fine line exposure resolution and is not a periodic pattern. That is, a high-resolution pattern that is higher than the resolution that can be realized by rough exposure is selectively obtained.

Further, as shown in FIG. 8A, when rough exposure is performed with a line width twice as large as the exposure threshold or more (here, double exposure amount), as shown in FIG. Then, the pattern of the fine line exposure disappears, and only the rough exposure pattern is formed.

The same applies to the case where the line width is tripled as shown in FIG. 9, and if the line width is larger than that, basically considering the combination of the double line width and the triple line width, etc. It is clear that all of the patterns that can be realized by exposure can be formed.

As described above, the fine line exposure and the rough exposure are performed in combination, and the threshold value of the photosensitive substrate and the amount of exposure in each exposure are adjusted, whereby FIGS. 6, 7B and 8
9 (B) and various patterns having high resolution as shown in FIG. 9 (B) can be formed without greatly lowering the throughput.

The principle of the present exposure method has been described above. (A-1) The pattern area where rough exposure is not performed, that is, the fine line exposure pattern below the exposure threshold is lost by development. I do.

(A-2) Regarding the pattern area of the rough exposure performed at an exposure amount equal to or less than the exposure threshold value, the exposure having the resolution of the fine line exposure determined by the combination of the pattern of the rough exposure and the fine line exposure. A pattern is formed.

(A-3) An arbitrary pattern is formed in the pattern region of the rough exposure performed with the exposure amount not less than the exposure threshold value, similarly to the rough exposure alone. It turns out that.

In the present invention, the order of the fine line exposure and the rough exposure is the order of the fine line exposure, but the present invention is not limited to this order.

Next, a pattern forming method according to the second embodiment of the present invention will be described. In the present embodiment, a so-called gate type pattern shown in FIG. 14 is intended as a circuit pattern obtained by exposure.

This pattern has a feature that the line width in the horizontal direction, that is, the line AA 'is 40 nm, while the line width in the vertical direction is 80 nm or more.

According to the present invention, for such a pattern in which high resolution is required only in one-dimensional direction, exposure in the fine line exposure step is performed only in one-dimensional direction requiring high resolution. Can be. In this embodiment, an example of a combination of one-dimensional fine line exposure and rough exposure will be described.

In this embodiment, the fine line exposure was performed by using an electron beam exposure apparatus shown in FIG. This exposure apparatus employs an electron beam exposure method called a so-called multi-beam exposure method.

In FIG. 19, 231a, 231b and 231c are electron guns which can individually turn on / off the electron beam. 232 is an electron gun 231
A reduction electron optical system for reducing and projecting a plurality of electron beams from a, 231b and 231c onto a wafer 233, and a deflector 234 for scanning the plurality of electron beams reduced and projected onto the wafer 233.

Reference numeral 235 denotes a dynamic focus coil for correcting the focus position of the electron beam according to the deflection aberration generated by the electron beam passing through the reduction electron optical system 232 when the deflector 234 is operated. This is a dynamic stig coil that corrects astigmatism of the electron beam according to the aberration. Reference numeral 237 denotes a wafer stage. Then, with the above configuration, a plurality of electron beams are scanned on the wafer 233, and the wafer 233 is exposed adjacent to the exposure field of each electron beam.

The wafer 233 is coated with a chemically amplified resist as a photosensitive agent. The electron beam incident as an image generates secondary electrons, and the secondary electrons generate acid, so that the solubility is locally changed. Thus, a pattern can be formed.

The resist is also subjected to rough X-ray exposure, which will be described later, to form secondary electrons from X-rays incident as an image in the same manner. This resist is sensitive to both electron beams and X-rays. Latent images can be superimposed by line exposure and rough exposure.

Since the electron beam exposure apparatus shown in FIG. 19 scans and exposes an arbitrary pattern in a so-called one-stroke manner as described above, it takes time for exposure control even with a multi-beam. In the case of using exposure, in the fine line exposure step of the present invention, straight lines are scanned and exposed at equal intervals. Therefore, the scanning distance is short, the control is simple, and the throughput is not greatly reduced.

In this embodiment, the above-described multi-beam system is used as an electron beam exposure apparatus. However, as the exposure apparatus, one having a deflection aberration corrected as disclosed in JP-A-9-330870 is appropriately used. be able to. Further, other electron beam exposure methods such as a stencil mask method other than the multi-beam exposure method can be used.

Further, as the fine line pattern exposure apparatus of this embodiment, an F2 excimer laser projection exposure apparatus, an X-ray exposure apparatus, an EUV exposure apparatus or the like can be used in addition to the electron beam exposure apparatus.

FIG. 15 is a schematic diagram showing a state of a pattern formed by the exposure apparatus described above.
A) shows a periodic exposure pattern by one-dimensional fine line exposure. The period is 80 nm, which corresponds to 40 nmL & S. Numerical values in the figure below represent exposure amounts.

In this embodiment, the pattern exposure shown in FIG. 11B is performed as a rough exposure step following the fine line exposure step. In the rough exposure step in this embodiment, the X-ray exposure apparatus described above with reference to FIG. 13 (in the first embodiment) was used. X
As described above, an electron beam exposure apparatus, an EUV exposure apparatus (a soft X-ray reduction projection exposure apparatus using a multilayer mirror), and the like other than the line exposure apparatus can be used.

The upper part of FIG. 11B shows the relative position with respect to the fine line exposure and the exposure amount in each area in this step.
The figure below maps this exposure with a resolution of 40 nm pitch. It can be seen that the line width of the pattern by this rough exposure is 80 nm, which is twice the fine line exposure.

As a method of performing the rough exposure in which the exposure amount varies depending on the region, a mask portion corresponding to the region shown in FIG. 1 is provided with a transmittance T%, and a mask portion corresponding to the region shown in FIG. There is a method using a mask having a multi-stage transmittance with a transmittance of 2T%. In this method, the rough exposure step can be completed by one exposure.

In this case, the exposure amount ratio in each step is as follows: fine line exposure: transmittance T: transmittance 2T = 1:
1: 2.

Also, instead of the halftone mask having only the pattern of the resolution size described above, the resulting image intensity using a fine pattern that does not resolve can be (continuous) halftone. A mask can be configured. Among them, a preferable example is to form a target gate pattern as it is on a mask.

The target gate pattern contains a fine line which is not resolved by rough exposure. When this line is exposed, the image becomes a so-called blurred image, and becomes a halftone in which the light intensity changes smoothly. This is the same as the image using the halftone, and the main effect is the same, and it is preferable to the image with the uniform halftone in that the peak position of the intensity of the target fine line coincides with the image. There are advantages.

Further, as another method not using a halftone mask, exposure can be performed twice with a mask having an exposure amount as shown in FIG. In this case, since the exposure amount may be one step, the transmittance of the mask may be one step. In this case, the exposure ratio on the photosensitive substrate is as follows: fine line exposure: first rough exposure: second rough exposure = 1: 1: 1.

Next, pattern formation by a combination of the two-beam exposure step and the rough exposure step will be described. In the present invention, there is no developing step between the fine line exposure step and the rough exposure step. Therefore, the exposure amount at each exposure pattern position in each step is added.
Then, a new combination exposure pattern is obtained based on the exposure amount after the addition.

FIG. 11C is a diagram showing the result of adding the exposure amounts in two steps according to the present embodiment. The lower figure shows the pattern obtained by developing this exposure pattern in gray. In this example, a photosensitive substrate having an exposure threshold of 1 or more and less than 2 was used. The pattern shown in grey matches the desired pattern shown in FIG. 14, and the pattern can be formed by the exposure method of the present invention.

Next, a pattern forming method according to the third embodiment of the present invention will be described. In this embodiment, fine line exposure is performed by electron beam exposure, and rough exposure is performed by electron projection exposure. First, the fine line exposure will be described.

FIG. 19 is used in Example 2 for fine line exposure.
Since the multi-beam exposure has been described with reference to FIG. It is exactly the same that other electron beam exposure apparatuses, X-ray equal-size exposure apparatuses, X-ray reduction exposure apparatuses, and the like can be used for fine-line exposure.

In this embodiment, a pattern of fine line exposure is two-dimensionally exposed. The line width of the fine line of this embodiment is
40 nm.

FIG. 16 is a schematic diagram showing an exposure pattern in the case of performing this two-dimensional fine line exposure as an exposure amount map. In this embodiment, the finally obtained exposure pattern
In order to increase the variation of the pattern, the exposure amounts in the two directions of fine line exposure were set to different values (twice). The two exposure amounts may be the same, and this is not limited by the present embodiment.

In the exposure pattern shown in FIG. 16, the exposure amount has four levels from 0 to 3 as a result of two fine line exposures. The number of exposure steps in rough exposure that is sufficiently effective for such fine line exposure is 5 or more. The exposure threshold of the photosensitive substrate is the maximum value of the exposure amount of the fine line exposure.
It is set to be larger and less than the maximum value 4 of rough exposure. FIG. 20 shows a schematic diagram of the electron projection exposure apparatus used in the rough exposure of the present embodiment.

In the figure, reference numeral 241 denotes an incident electron beam; 242, a mask; 243, an electron diffusion region; 244, an electron-transmitting substrate;
Is a transmitted electron beam, 241b is a diffused electron beam, 245 is a projection lens, 246 is an aperture mask, 247 is an aperture,
248 indicates a wafer, and 249 indicates a wafer stage.

Each of the incident electrons 241 passes through the mask 242. At this time, the electrons passing through the electron diffusion region 243 are diffused and have a scattering angle.
1a is more widespread.

The electrons passing only through the other electron transmission substrate 244 hardly diffuse, and the transmitted beam 241b mainly has a straight component. If electrons pass through the projection lens 245, aperture mask 247, and wafer 248 without any interaction with the mask and go straight, all the electron beams in the effective screen on the mask converge on the aperture 248. ,
Then, it is configured to be able to pass through and reach the wafer. The position at which the passed electrons arrive on the wafer, that is, the image position, has a one-to-one correspondence with the position on the mask.

Therefore, when a mask patterned by the electron diffusion region 243 on the electron transmission substrate 244 is used, only the transmitted electron beam that passes substantially straight without being diffused passes through the opening. The electron reaches the image position corresponding to the non-diffusion area on the mask because the resist reaches the image point on the corresponding wafer and exposes the resist applied on the wafer 248, and the electron beam reaches the image point corresponding to the diffusion area. Since the electrons do not reach the image position, the pattern applied to the mask is exposed to the resist applied on the wafer.

The principle of the electron projection exposure used in this embodiment has been described above. In this embodiment, the image intensity at the image plane position is reduced by using four types of diffusing materials having different degrees of diffusion in the electron diffusion region. Exposure with a halftone of five levels of 0, 1, 2, 3, and 4 was performed instead of binary values of 0 and 1. FIG. 21 shows a schematic diagram of a part of the mask used at this time. The range of scattering is different in each region, so that the amount of electrons that can pass through the opening in FIG. 20 changes stepwise, and a halftone image is formed on the image plane. The pattern size of each diffusion region was set to 80 nm, that is, twice the fine line width of fine line exposure.

FIG. 17 shows the respective exposure amounts of the exposure pattern obtained as a result of performing the rough exposure at such five stages (0, 1, 2, 3, 4). The hatched portion indicates a location above the exposure threshold, which is the final exposure pattern.

FIG. 17 shows a block having sides twice as long, with the resolution of rough exposure being half that of fine line exposure. FIG. 18 shows an example in which a pattern is formed in a wider area by changing the exposure amount of the rough exposure in such a block unit.

A pattern having a fine line exposure resolution and a very rich pattern other than the periodic pattern can be exposed. In this embodiment, the rough exposure is 2 times the line width of the fine line exposure.
Although the present invention was performed in units of double blocks, the present invention is not limited to this, and any pattern within the resolution of rough exposure can be used.
Rough exposure can be performed, and an exposure pattern combined with fine line exposure can be obtained according to each.

In this embodiment, the line width of the fine line exposure is 2
Although described in one direction as being the same, this may be changed arbitrarily. In addition, the angle between the two can be chosen arbitrarily.

In the present invention, (a) as an illumination method of the illumination optical system, it is applicable to illuminate a mask pattern with light from a KrF excimer laser, an ArF excimer laser or an F2 excimer laser.

(B) In an exposure apparatus, a refracting system and a reflecting system
It is applicable to project the mask pattern by a projection optical system composed of either a refraction system or a reflection system.

(C) As the exposure apparatus, a step-and-repeat type reduction projection exposure apparatus having the exposure method of the present invention as an exposure mode, a step-and-scan type reduction projection exposure apparatus having the exposure method of the present invention as an exposure mode, etc. are applied. It is possible.

Next, an embodiment of a method for manufacturing a semiconductor device using the above-described exposure apparatus will be described.

FIG. 22 shows a flow of manufacturing a semiconductor device (a semiconductor chip such as an IC or an LSI, or a liquid crystal panel or a CCD).

In step 1 (circuit design), a circuit of a semiconductor device is designed. Step 2 is a process for making a mask on the basis of the circuit pattern design.

On the other hand, in step 3 (wafer manufacture), a wafer is manufactured using a material such as silicon. Step 4
The (wafer process) is called a pre-process, and an actual circuit is formed on the wafer by lithography using the prepared mask and wafer.

The next step 5 (assembly) is called a post-process, and is a process of forming a semiconductor chip using the wafer produced in step 4, and includes an assembly process (dicing and bonding) and a packaging process (chip encapsulation). And the like.

In step 6 (inspection), inspections such as an operation confirmation test and a durability test of the semiconductor device manufactured in step 5 are performed. Through these steps, a semiconductor device is completed and shipped (step 7).

FIG. 23 shows a detailed flow of the wafer process. Step 11 (oxidation) oxidizes the wafer's surface. Step 12 (CVD) forms an insulating film on the wafer surface.

In step 13 (electrode formation), electrodes are formed on the wafer by vapor deposition. In step 14 (ion implantation), ions are implanted into the wafer. Step 15
In (resist processing), a photosensitive agent is applied to the wafer. Step 16 (exposure) uses the above-described exposure apparatus to print and expose the circuit pattern of the mask onto the wafer.

In step 17 (development), the exposed wafer is developed. In step 18 (etching), portions other than the developed resist are removed. In step 19 (resist stripping), the resist that has become unnecessary after the etching is removed. By repeating these steps, multiple circuit patterns are formed on the wafer.

By using the manufacturing method of this embodiment, it is possible to easily manufacture a highly integrated semiconductor device which has conventionally been difficult to manufacture.

The present invention is not limited to the embodiment described above, and the sequence flow and the like can be variously changed without departing from the spirit of the present invention.

[0127]

As described above, by using the exposure method and the exposure apparatus of the present invention for multiplex exposure of fine line exposure and rough exposure using different exposure apparatuses, exposure of various patterns of 80 nm or less can be performed. This can be realized without significantly lowering the throughput.

[Brief description of the drawings]

FIG. 1 is a view showing a basic flow of an exposure apparatus of the present invention.

FIG. 2 is a schematic view showing an exposure pattern by fine line exposure.

FIG. 3 is a schematic diagram showing exposure sensitivity characteristics of a resist.

FIG. 4 is a schematic view showing pattern formation by development.

FIG. 5 is a schematic view showing an exposure pattern by fine line exposure.

FIG. 6 is a schematic view showing a pattern formed according to the present invention.

FIG. 7 is a schematic view showing an example of a formation pattern according to the first embodiment of the present invention.

FIG. 8 is a schematic view showing another example of the pattern formed according to the first embodiment of the present invention.

FIG. 9 is a schematic view showing another example of the formation pattern according to the first embodiment of the present invention.

FIG. 10 is a main block diagram of the exposure apparatus of the present invention.

FIG. 11 is a schematic view showing an example of an F2 laser projection exposure apparatus.

FIG. 12 is a schematic view showing a state of two-beam interference exposure in an F2 laser projection exposure apparatus.

FIG. 13 is a schematic diagram showing an example of an X-ray exposure apparatus {a schematic diagram showing a circuit pattern used in Embodiment 2;

FIG. 14 is a schematic diagram of a circuit pattern used in Embodiment 2 of the present invention.

FIG. 15 is a schematic diagram illustrating Embodiment 2 of the present invention.

FIG. 16 is a schematic diagram illustrating a fine line exposure pattern according to a third embodiment of the present invention.

FIG. 17 is a schematic view showing a pattern formed in a two-dimensional block.

FIG. 18 is a schematic view showing an example of a pattern that can be formed in Embodiment 3 of the present invention.

FIG. 19 is a schematic view showing an example of a multi electron beam exposure apparatus.

FIG. 20 is a schematic view illustrating an example of an electronic projection exposure apparatus.

FIG. 21 is a schematic view illustrating an example of a halftone mask.

FIG. 22 is a flowchart of a device manufacturing method according to the present invention.

FIG. 23 is a flowchart of a device manufacturing method of the present invention.

FIG. 24 is a schematic view showing a conventional projection exposure apparatus.

[Explanation of symbols]

 211 Mask 212 Primary mirror 213 Secondary mirror 214 Wafer 215 Wafer stage 216 Aperture stop 221 SR light source 222 SR light 223 Beam shaping mirror 224 Shutter 225 Shutter control unit 226 Mask 227 Wafer 231 Electron mirror 232 Reduction electron optical system 233 Wafer 242 Mask 248 Wafer 251 Excimer laser light source 252 Illumination optical system 253 Illumination light 254 Mask 255 Object side exposure light 256 Projection optical system 257 Image side exposure light 258 Photosensitive substrate 259 Substrate stage

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (reference) H01L 21/30 541S

Claims (17)

[Claims] An exposure step of exposing a periodic pattern to a photosensitive substrate; and a rough exposure step of exposing the photosensitive substrate to a rough pattern having a lower resolution than the pattern. An exposure method, wherein latent images generated in the same portion are overlapped. 2. The method according to claim 1, wherein the two exposure steps use light having different wavelengths and / or particle beams having different wavelengths, and the photosensitive substrate has an exposure sensitivity to the light having different wavelengths and / or particle beams having different wavelengths. 2. The exposure method according to claim 1, comprising: 3. The exposure method according to claim 1, wherein the exposure step uses a projection exposure using ultraviolet light having a wavelength of 300 nm or less and / or a two-beam interference exposure. 4. The exposure method according to claim 1, wherein the exposure step uses electron beam exposure. 5. The method according to claim 1, wherein the exposing step includes a soft X having a wavelength of 30 nm or less.
3. The exposure method according to claim 1, wherein projection exposure using lines and / or two-beam interference exposure are used. 6. The exposure method according to claim 1, wherein the rough exposure step uses projection exposure using soft X-rays having a wavelength of 30 nm or less. 7. The exposure method according to claim 1, wherein the rough exposure step uses projection exposure using ultraviolet light having a wavelength of 300 nm or less. 8. The exposure method according to claim 1, wherein the rough exposure is an electronic projection exposure. 9. The exposure method according to claim 1, wherein the rough exposure is a multi-value exposure. 10. The exposure method according to claim 1, wherein the rough exposure comprises a multiple exposure. 11. The exposure method according to claim 9, wherein said rough exposure step uses a mask having a plurality of pattern areas having transmittance. 12. The rough exposure step uses a mask having an area having a pattern having a line width or less that can be resolved under the exposure conditions of the rough exposure step, and the light intensity of an exposure image in which the pattern is not resolved is used. 10. The exposure method according to claim 9, wherein is multi-valued. 13. The exposure method according to claim 1, wherein the exposure step is a multi-value exposure. 14. The exposure method according to claim 1, wherein the exposure step comprises a multiple exposure. 15. An exposure apparatus, wherein a pattern on a mask is transferred onto a photosensitive substrate using the exposure method according to claim 1. Description: 16. After the pattern on the mask surface is exposed on the wafer surface by using the exposure method according to claim 1, the device is manufactured through the developing process of the wafer. A method for manufacturing a device, comprising: 17. A device according to claim 15, wherein after the pattern on the mask surface is exposed on the wafer surface using the exposure apparatus according to claim 15, the wafer is subjected to a development process to produce a device. Production method.