JP2000031035A - Aligner and manufacture of device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable performing multiple exposure more simply, by containing two exposures which are performed in a state where zero-order light is shielded with a filter and a state where zero-order light is not shielded with the filter, in a multiple exposure mode. SOLUTION: A mask 161 is almost coherently illuminated from the almost perpendicular direction. Under the illumination, a light permeating through the mask 161 contains a zero-order light which travels straight, and a -1-order light of angle -θ0 direction and a +1-order light of angle +θ0 direction which symmetrically travel to a light axis 163a of a projection optical system 163, around the zero-order light as the center. The above three luminous fluxes enter the projection optical system 163. In this case, a retractable pupil filter 164 is arranged in the vicinity of a pupil (i.e., in the vicinity of an aperture stop) of the projection optical system 163. The zero-order light is eliminated by the filter 164, only the ±1-order diffracted lights practically contribute to imagery, and the zero-order light does not contribute to imagery. Thereby two luminous fluxes interference exposure step is performed by using a projection aligner, and multiple exposure is enabled with the common projection aligner.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to semiconductors such as ICs and LSIs, liquid crystal panels, magnetic heads, and CCDs (imaging devices).
The present invention relates to an exposure apparatus that exposes a photosensitive substrate such as a silicon plate or a glass plate with a pattern of a device such as a device, and a method of manufacturing a device.

[0002]

2. Description of the Related Art Conventionally, when manufacturing ICs, LSIs, liquid crystal elements and the like by using photolithography technology,
A pattern of a photomask or a reticle (hereinafter collectively referred to as a “mask”) is transferred to a silicon plate or a glass plate coated with a photoresist or the like via a projection optical system.
(Hereinafter referred to as a "wafer") is used.

FIG. 19 is a schematic diagram showing the principle of a conventional exposure apparatus.

In FIG. 19, reference numeral 191 denotes a light source K
rF excimer laser (wavelength: about 248 nm). 1
92 is an illumination optical system, 193 is illumination light, 194 is a mask,
195 denotes an object-side exposure light, 196 denotes a projection optical system, 197 denotes an image-side exposure light, 198 denotes a photosensitive substrate (wafer), and 199 denotes a substrate stage that holds the photosensitive substrate 198.

In this exposure apparatus, first, an excimer laser 1 is used.
The laser light emitted from the light source 91 is guided to the illumination optical system 192, and the illumination light 193 having a predetermined light intensity distribution, light distribution, and the like.
Then, the light enters the mask 194. A circuit pattern to be formed on the photosensitive substrate is formed on the mask 194 by using chrome or the like, and the illumination light 193 is transmitted and diffracted by this circuit pattern to become the object side exposure light 195. The projection optical system 196 converts the exposure light 195 into image-side exposure light 197 that forms the circuit pattern on the photosensitive substrate 198 at a predetermined magnification and with a sufficiently small aberration. The image-side exposure light 197 converges on the photosensitive substrate 198 with a predetermined NA (numerical aperture, = sin θ) and forms an image, as shown in the lower enlarged view of FIG. The substrate stage 199 has a function of changing the relative positions of the photosensitive substrate 198 and the projection optical system 196 by step-moving in order to form circuit patterns in a plurality of shot areas on the photosensitive substrate 198. I have.

[0006]

SUMMARY OF THE INVENTION As described above, K
With a projection exposure apparatus using an rF excimer laser, it is difficult to form a pattern image having a line width of 0.15 μm or less.

The reason will be described below. First, the projection optical system has a limitation due to a trade-off in optical resolution and depth of focus due to the wavelength of exposure light. The resolution R of the resolution pattern and the depth of focus DOF by the projection exposure apparatus can be expressed by the following formulas (1) and (2).

[0008]

(Equation 1)

Here, λ is the wavelength of the exposure light, NA is the numerical aperture on the light emission side representing the brightness of the optical system described above, and k ₁ and k ₂ are constants determined by the development process characteristics of the photosensitive substrate, etc. Usually, it takes a value of about 0.5 to 0.7.

From the equations (1) and (2), to increase the resolution to reduce the resolution R requires a "short wavelength" to reduce the wavelength λ or a "high NA" to increase the NA. is there. However, at the same time, the depth of focus DOF required as the performance of the projection optical system needs to be maintained at a certain value or more. For this reason, it is impossible to increase the NA much.

On the other hand, there is also an exposure method which does not depend on the above equations (1) and (2). FIG. 15 is a schematic diagram for explaining this exposure method. In FIG. 15, the coherent light from the laser light source 151 is split into two light beams by the half mirror 152,
The two light fluxes are angled by mirrors 153a and 153b and intersect on the surface of the photosensitive substrate 154 so as to intersect.
By making the light beam 4 incident, interference fringes are formed at the intersection of the two light beams. The interference fringes expose the photosensitive material of the photosensitive substrate 154 according to the light intensity distribution, and form a periodic uneven pattern according to the light intensity distribution by development.

The resolution R by this exposure method is expressed by the following equation (3). Here, R is each width of L & S (line and space), that is, each width of light and dark of the interference fringes, and θ is the substrate 154 of the two light fluxes 151a and 151b.
Represents the angle of incidence on the surface, where NA = sin θ.

[0013]

(Equation 2)

As can be seen from a comparison between the equations (3) and (1), k ₁ = 0.25 in the exposure method shown in FIG.
When the value of the conventional projection exposure system k ₁ is considered to be 0.5 to 0.7, it is possible to obtain more than twice the resolution as compared with the prior art. For example, λ = 0.248 μm,
If NA = 0.6, R = 0.10 μm is obtained.

However, the exposure method shown in FIG. 15 has a fundamental problem that various types of circuit patterns of a semiconductor element cannot be exposed. That is, in the exposure by interference of two light beams shown in the figure, only the line-and-space pattern having the same pitch over the entire intersection region can be exposed.

In order to solve this problem, the same area of the photosensitive substrate is exposed without sequentially developing the photosensitive substrate between the projection exposure by the apparatus of FIG. 19 and the two-beam interference exposure by the apparatus of FIG. For multiple exposure techniques.

However, the two-beam interference exposure in the conventional multiple exposure technique requires the apparatus shown in FIG. 15 other than the projection exposure apparatus, or requires a special mask such as a phase shift mask when using a projection exposure apparatus. there were.

An object of the present invention is to provide an exposure apparatus capable of performing multiple exposures more easily than in the past and a method of manufacturing a device using the same.

In addition, the present invention employs an exposure method in which two-beam interference exposure and projection exposure are combined to achieve a line width of 0.1.
Exposure method capable of realizing formation of a pattern image of 5 μm or less and real circuit pattern exposure with a line width of 0.15 μm or less using the same without using a special reticle such as a Levenson reticle. An object of the present invention is to provide a possible exposure apparatus and a method for manufacturing a device using the same.

[0020]

An exposure apparatus according to the present invention is an exposure apparatus having a multiple exposure mode, wherein the exposure apparatus has an illumination system and a projection system, and the projection system has the 0 of the lights from the mask illuminated by the illumination system
The multi-exposure mode includes supply means for supplying a filter for blocking the next light in the optical path, wherein the first exposure is performed in a state where the zero-order light is blocked by the filter, and the zero-order light is not blocked by the filter. It is characterized by including a second exposure performed in a state.

According to a second aspect of the present invention, in the first aspect of the present invention, the filter is provided at or near a pupil position of the projection system.

According to a third aspect of the present invention, in the second aspect, the mask used when the filter is supplied at or near the position of a pupil of the projection system is a periodic pattern image to be formed on an image plane. Is characterized by having a periodic pattern having a pitch twice as large as a value obtained by dividing the pitch P by the projection magnification.

According to a fourth aspect of the present invention, in the third aspect of the invention, in the first exposure in the multiple exposure mode, an exposure pattern having an exposure amount not exceeding a threshold value of the object to be exposed is formed on the object. In the exposure step including the second exposure in the multiple exposure mode, an exposure pattern having an exposure amount exceeding the threshold value and an exposure amount not exceeding the threshold value is formed on an object, and these exposure patterns The exposure amounts are determined so that the exposure pattern obtained by combining the above and the threshold value has a relationship of forming a desired circuit pattern.

According to a fifth aspect of the present invention, in the exposure apparatus according to any one of the first to fourth aspects, the first exposure is performed by interfering ± 1st-order diffracted light from the mask. I have.

According to a sixth aspect of the present invention, in the exposure apparatus according to any one of the first to fifth aspects, the first and the second
It is characterized in that exposure is performed in the order of exposure or vice versa.

According to a seventh aspect of the present invention, there is provided a method of manufacturing a device, comprising a step of printing a device pattern on an object using the exposure apparatus according to any one of the first to sixth aspects.

[0027]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention includes an illumination system and a projection system, wherein the projection system, when in a multiple exposure mode, includes a plurality of lights from a mask illuminated by the illumination system. Means for automatically or manually supplying a filter for blocking the zero-order light into the optical path. Here, in a state where the filter is supplied in the optical path, exposure of two-beam interference by ± 1st-order diffracted light in the multiple exposure is performed.

According to the present invention, in each of the above-mentioned embodiments, the filter is supplied at or near the position of a pupil of the projection system. The mask used when the filter is supplied at or near the position of a pupil of the projection system has a pitch twice as large as a value obtained by dividing a pitch P of a periodic pattern image to be formed on an image plane by a projection magnification. It has a periodic pattern.

According to the present invention, in the multiple exposure mode, the predetermined exposure is performed such that an exposure pattern having an exposure amount not exceeding a threshold value of an exposure target (resist) is formed. In an exposure step different from the predetermined exposure, an exposure pattern having an exposure amount exceeding the threshold value and an exposure amount not exceeding the threshold value is formed, and an exposure pattern obtained by combining these exposure patterns and the threshold value are formed. The respective exposure amounts are determined so that the values and the values have a relationship of forming a desired circuit pattern.

Next, one of the multiple exposure methods to which the present invention is applied will be described with reference to FIGS.

FIG. 1 shows the basic flow of the multiple exposure method.
It is a figure showing a chart. FIG. 1 shows a developing step in addition to the two-beam interference exposure and the projection exposure that constitute the multiple exposure. The two-beam interference exposure step and the projection exposure step need not be in the order shown in this figure, and the projection exposure step may be performed first. When each exposure step is performed a plurality of times, the exposure steps can be performed alternately. In addition, an alignment step or the like may be appropriately inserted between each exposure to increase the image forming accuracy, and the configuration of the present invention is not limited by this diagram.

In the case of the multiple exposure shown in the flow chart of FIG. 1, the photosensitive substrate is first exposed by a periodic pattern of interference fringes due to interference of two light beams. FIG. 2 is a schematic diagram showing this periodic pattern. The numbers in the figure represent the exposure amount, and the hatched portions represent the exposure amount 1 and the white portions represent the exposure amount 0 (FIG. 2).
(A)). When developing the photosensitive substrate exposed in such a periodic pattern, the exposure threshold value Eth of the photosensitive substrate is 0.
And 1 (FIG. 2B).

FIGS. 3 (A) and 3 (B) show the dependence of the developed film thickness on the amount of exposure and the exposure threshold value Eth of the resist portion of the photosensitive substrate for the positive type resist and the negative type resist. In the case of a positive resist, a portion exposed with an exposure amount equal to or more than the exposure threshold value Eth is obtained.

FIG. 4 is a schematic diagram showing a state in which a lithography pattern is formed through development and etching processes in the case of performing such an exposure, for each of a negative resist and a positive resist. is there.

In the multiple exposure in FIG. 1, when the maximum exposure amount in the two-beam interference exposure step is 1, the exposure threshold value of the resist is set to be larger than 1. In such a photosensitive substrate, when the exposure pattern obtained by performing only the two-beam interference exposure shown in FIG. 5 is developed, the exposure amount is insufficient, and although there is a slight variation in the film thickness, the portion where the film thickness becomes 0 is reduced. No lithography pattern is formed (see FIG. 6). This can be regarded as the disappearance of the two-beam interference exposure pattern. (Note that the description will be made using an example in which a negative resist is used. However, it is apparent that the present invention does not depend on whether the resist is a negative resist or a positive resist. And you can arbitrarily choose this).

As described above, the multiple exposure of this embodiment
A lithography pattern is formed by fusing a high-resolution periodic pattern that appears to be lost only by light beam interference exposure with a pattern formed by projection exposure, and selectively restoring and reproducing the pattern by the fusion. is there.

FIG. 7A shows a pattern (image) in the projection exposure step. The resolution in the projection exposure step is 2
Since it is about half that of the light beam interference exposure step, it is shown here that a large pattern having a line width about twice the minimum line width obtained by the two light beam interference exposure is formed.

Assuming that the projection exposure step of the pattern shown in FIG. 7A is performed after the two-beam interference exposure step shown in FIG. 5 without any development step, the distribution of the total exposure amount is as shown in FIG. 7 (B) is as shown below. Here, the exposure amount ratio between the two-beam interference exposure and the projection exposure is 1: 1. The exposure threshold value Eth is set between the exposure amount 1 and the exposure amount 2 as in the case of the pattern disappearing in FIG. Therefore, when the development is performed after the double exposure, the lithography pattern shown in the upper part of FIG. 7B is formed. This pattern is a convex pattern in the case of a negative resist, and a concave pattern in the case of a positive resist. This pattern has a resolution of two-beam interference exposure, and is not a periodic pattern but an isolated pattern. That is, according to this multiple exposure, a high-resolution pattern that is higher than the resolution achievable by projection exposure and cannot be obtained by only two-beam interference exposure is obtained.

As shown in FIG. 8 (A), after the projection exposure is performed with an exposure amount equal to or greater than the exposure threshold value Eth (here, an exposure amount twice Eth) in the pattern having the double line width as described above. Developing as shown in the upper diagram of FIG.
The pattern of the light beam interference exposure disappears, and only the lithography pattern by the projection exposure is formed.

This is shown in FIGS. 9A and 9B.
The same applies to a pattern having a line width three times as large as the minimum line width in the light beam interference exposure. For a line width larger than that, basically a combination of a double line width and a triple line width Considering the above, it is clear that all of the patterns that can be realized by projection exposure can be formed.

As described above, the two-beam interference exposure and the projection exposure are performed in combination, and at this time, the exposure amount in each exposure is appropriately adjusted with respect to the exposure threshold value Eth of the resist on the photosensitive substrate. 7 (B) and 8 (B) and / or
Alternatively, a pattern including various patterns as shown in FIG. 9B and having a minimum line width having a resolution of two-beam interference.
Can be formed.

The above is one example of the multiple exposure method to which the present invention is applied. (A-1) The pattern by the two-beam interference exposure step in which the total exposure amount after the projection exposure step is equal to or less than the exposure threshold value. -Disappears by development.

(A-2) For a pattern area exposed at an exposure amount equal to or less than the exposure threshold value in the projection exposure step, the total exposure amount of the projection exposure step and the two-beam interference exposure step is the exposure threshold. A portion exceeding the value Eth is selectively generated, and a lithography pattern is formed by development at the resolution of two-beam interference exposure.

(A-3) The lithography pattern is formed as it is in the pattern area exposed in the projection exposure step with the exposure amount not less than the exposure threshold value. It turns out that. Since the depth of focus in the two-beam interference exposure step is considerably large, it is advantageous for pattern formation. The order of two-beam interference exposure and projection exposure is as follows.
The order may be reversed.

Next, an embodiment of the exposure apparatus of the present invention will be described below with reference to FIG.

FIG. 18 is a schematic view showing an embodiment of the exposure method and the exposure apparatus according to the present invention. In the figure, reference numeral 11 denotes a light source for exposure such as a KrF excimer laser or an ArF excimer laser, and the wavelength of the exposure light is 400 n such as 248 nm and 193 nm.
m or less. 12 is an illumination optical system, 13 is a schematic diagram of an illumination mode, 14 is a mask, 15 is a mask to be replaced with the mask 14, 16 is a mask changer, 17 is a mask stage, 18 is a projection optical system, and 19a. , 19b denotes a pupil filter, 20 denotes a filter changer for automatically or manually taking in and replacing the pupil filter, 21 denotes a wafer, and 22 denotes a wafer stage.

In this exposure apparatus, when performing two-beam interference exposure capable of performing projection exposure at high resolution, a coherent illumination (mask) is used by using a dark filter having a light shielding area at the center indicated by 19a in the figure. Is applied to a normal mask having a repetitive pattern, which will be described later, using a parallel or substantially parallel light beam perpendicularly incident on the mask. When performing normal projection exposure, the illumination is appropriately switched to partial coherent illumination or the like having a relatively large σ (sigma), and the pupil filter is also switched to the filter 19b, or the filter 19a is retracted and The mask is switched to a mask having another pattern without using other filters.

Next, the configuration of the pupil filter 19a and the mask 14 in the case of two-beam interference exposure in the exposure apparatus of FIG. 18 will be described.

FIG. 16 shows a projection exposure apparatus using a projection optical system composed of, for example, a refraction system.
8 nm, NA of 0.6 or more. In the figure, 161 is a mask, 162 is object-side exposure light, 163 is a projection optical system,
164 is a pupil filter, 165 is an image side exposure light, 166
Is a photosensitive substrate (wafer), 167 is a schematic diagram showing the position of the light beam on the pupil plane, and the hatched portion is the light shielding portion of the filter 164. FIG. 16 is a schematic diagram showing a state in which the two-beam interference exposure is performed, and the object-side exposure light 162 and the image-side exposure light 1 are shown.
Reference numeral 65 includes three and two parallel light beams, respectively.

In order to perform two-beam interference exposure in a normal projection exposure apparatus, in the present invention, a mask and a method of illuminating the mask are set as shown in FIG.

The right view of FIG. 17 shows a mask 161 having a one-dimensional periodic pattern of the chrome light shielding portion 171 in which the pitch Po is expressed by the equation (4).

[0052]

(Equation 3)

Here, R is the resolving power, Po is the arrangement pitch of the light shielding portions 171 on the mask 161, P is the pitch of the periodic pattern image on the photosensitive substrate 166, and M is the projection optical system 1
63 denotes a magnification, λ denotes a wavelength, and NA denotes an image-side NA of the projection optical system.

As shown in the left diagram of FIG. 17, the mask 161 is substantially coherently illuminated from a substantially vertical direction. Under this illumination, the light transmitted through the mask 161 is composed of a zero-order light that travels straight, and a -1st-order light and an angle in the -θ0 direction that travel symmetrically with respect to the optical axis 163a of the projection optical system 163 around the _zero -order light. Three luminous fluxes of + 1st-order light in the + θ ₀ direction enter the projection optical system 163. Here, a pupil filter 164 that can be moved in and out of the pupil of the projection optical system 163 (that is, near the aperture stop) is arranged. The zero-order light is removed so that substantially only the ± first-order diffracted light contributes to the image formation, and the zero-order light does not contribute to the image formation.

In this manner, the two-beam interference exposure step shown in FIG. 1 can be performed by using the projection exposure apparatus, and the multiple exposure can be performed by the common projection exposure apparatus. Further, according to this method, since the ± 1st-order light is used, the pitch of the periodic pattern of the mask can be configured to be twice as large as that of a normal pattern, and a fine phase film needs to be provided on the mask like a Levenson type. This is advantageous for mask making and the like.

Next, a second embodiment of the multiple exposure method of the present invention.
This will be described with reference to FIGS. 10 and 11. In the present embodiment, a so-called gate type pattern shown in FIG. 10 is used as a circuit pattern obtained by exposure. In this gate pattern, the minimum line width in the horizontal direction, that is, in the AA 'direction is 0.
1 μm, whereas the minimum line width in the vertical direction is 0.2 μm.
m. Here, the high-resolution pattern by the two-beam interference exposure step is applied only to the vertical pattern 100 that requires high resolution.

FIG. 11A shows a one-dimensional periodic exposure pattern (distribution of image intensity or exposure amount) by two-beam interference exposure.
Is shown. The period is 0.2 μm, which corresponds to a periodic pattern image of 0.1 μmL & S. Here, this periodic pattern image is created using the exposure apparatus with the 0th-order light cut pupil filter and the normal line & space mask pattern described with reference to FIGS. The numerical value 1.0 in the lower diagram of FIG. 11A represents the exposure amount.

After the two-beam interference exposure step, the exposure of the exposure pattern 110 shown in FIG. This projection exposure also uses the projection exposure apparatus shown in FIG. The upper part of FIG. 11B shows the positional relationship between the exposure pattern of the two-beam interference exposure and the exposure pattern of the projection exposure, and the exposure amount in each region of the steps in the main projection exposure step. The lower part of FIG. 11B maps the exposure amount in this projection exposure step with a resolution of 0.1 μm pitch.

From FIG. 11B, it can be seen that the minimum line width of the exposure pattern in this projection exposure step is 0.2 μm, which is twice the line width of the two-beam interference exposure.

As a method of performing projection exposure for supplying an exposure pattern having a different exposure amount depending on such a region, the transmittance T corresponding to the region indicated by 1 in FIG.
%, There is a method using a mask having a plurality of (multi-valued) transmittances having openings having a transmittance of 2T% corresponding to the area indicated by 2. In this method, projection exposure is performed by one exposure. Can be completed. In this case, the exposure ratio in each step is as follows: two-beam interference exposure: projection exposure of an opening having a transmittance T: projection exposure of an opening having a transmittance 2T on the photosensitive substrate = 1:
1: 2.

As another type of mask for supplying an exposure pattern having a different exposure amount depending on the region, there is a mask having an opening similar to the gate pattern shown in FIG.
In this case, since the image of the vertical pattern 100 having the minimum line width cannot be resolved, the exposure amount is smaller than that of the other portions, and an exposure pattern close to that shown in the upper part of FIG. .

Further, as another method, there is a method of performing exposure twice using two types of masks for supplying an exposure pattern of a predetermined exposure amount as shown in the upper and lower portions of FIG. In this case, since the exposure amount may be one step, the transmittance of the mask is 1 unit.
Only the step requires a normal mask. In this case, the exposure ratio on the photosensitive substrate is two-beam interference exposure: first projection exposure: second projection exposure = 1: 1: 1.

The formation of the lithography pattern by the combination of the two-beam interference exposure and the projection exposure will be described. In this multiple exposure, there is no development step between the two-beam interference exposure step and the projection exposure step. Therefore, the exposure amount of each exposure pattern in each step is added. After the addition, a new exposure pattern (exposure amount distribution or latent image intensity distribution) is formed.

The upper part of FIG. 11C is a diagram showing the result of adding the exposure amounts in the two exposure steps of this embodiment. The lower part of FIG. 11C shows the lithography pattern as a result of developing the exposure pattern in gray. In the present embodiment, a photosensitive substrate having an exposure threshold value Eth of 1 or more and less than 2 is used.
The lithography pattern is a convex pattern in the case of a negative resist, and a concave pattern in the case of a positive resist.

The lithography pattern shown in gray matches the gate pattern shown in FIG. 10, and it can be seen that this pattern can be formed by the exposure method of this embodiment.

Next, a third embodiment of the present invention will be described with reference to the drawings.

In the present embodiment, the 0 shown in FIGS.
It uses a projection exposure apparatus with a secondary light cut pupil filter,
In a two-beam interference exposure step, a two-dimensional periodic pattern is formed. FIG. 12 is a schematic diagram showing an exposure pattern in the case of performing the two-dimensional two-beam interference exposure as a map of the exposure amount. In this embodiment, in order to increase the variation of the exposure pattern finally obtained, two different directions (X direction and Y direction) formed in the two-beam interference exposure step are used.
Direction), the exposure amounts of the interference fringes (periodic patterns) were set to different values. Specifically, one has an exposure amount that is twice the exposure amount of the other. The two exposure amounts may be the same.

In the exposure pattern shown in FIG. 12, as a result of the two-beam interference exposure step in the two directions of X and Y, the exposure amount for the resist has four steps (0 value) from 0 to 3. The number of exposure steps of projection exposure that is sufficiently effective for such two-beam interference exposure step is five or more.
The exposure threshold value of the resist on the photosensitive substrate is set to be larger than 3, which is the maximum value of the exposure amount of the two-beam interference exposure, and smaller than 4, which is the maximum value of the exposure amount of the projection exposure.

Such five steps (0, 1, 2, 3, 4)
FIG. 13 shows the respective exposure amounts of the exposure pattern as a result of performing the projection exposure at the exposure amount of. The hatched portion in FIG. 13 indicates a location above the exposure threshold, which is the exposure pattern that is finally converted into a lithography pattern by development.
It becomes.

FIG. 13 shows the projection exposure step as a block having sides twice as long as the two-beam interference exposure block with half the resolution of the two-beam interference exposure step. FIG. 14 shows an example in which an exposure pattern is formed over a wider area by changing the amount of projection exposure in such a block unit. An exposure pattern having a resolution in the two-beam interference exposure step and rich in variations including a pattern other than the periodic pattern can be formed.

The projection exposure step in the present embodiment has two steps.
In the present embodiment, the projection exposure step is performed with an arbitrary line width size within the resolution of the projection exposure, but the present invention is not limited to this. And an exposure pattern combined with a two-beam interference exposure step can be obtained accordingly.

In the present embodiment, the line width of the two-beam interference exposure is described as being the same in the two directions. However, the line width may be mutually changed in the two directions. Further, the angle formed between the two directions, that is, the angle formed by the two types of interference fringes can be arbitrarily selected.

The present invention is not limited to the embodiment described above, and the sequence of the multiple exposure and the specific configuration of the pupil filter can be variously changed without departing from the gist of the present invention. is there.

In particular, the number of exposures and the number of exposure steps in each of the two-beam interference exposure step and the projection exposure step can be selected as appropriate, and the exposures can be appropriately superimposed by shifting the exposure position. It is possible to By performing such adjustments, variations can be made in the circuit patterns that can be formed.

The present invention can be applied not only to the above-described multiple exposure method but also to various known multiple exposure methods having an exposure step of performing two-beam interference exposure using a mask and a projection exposure apparatus.

Next, an embodiment of a method of manufacturing a semiconductor device using an executable projection exposure apparatus having the multiple exposure mode described above as one of the plurality of exposure modes described above will be described.

FIG. 20 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 step of forming a semiconductor chip using the wafer produced in step 4, and includes an assembly step (dicing and bonding) and a packaging step (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. 21 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), unnecessary resist after 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 manufacture a highly integrated semiconductor device which has conventionally been difficult to manufacture.

[0086]

According to the present invention, it is possible to achieve an exposure apparatus capable of performing multiple exposures more easily than in the past and a method of manufacturing a device using the same.

In addition, according to the present invention, an exposure method capable of forming a pattern image with a line width of 0.15 μm or less by using an exposure method in which two-beam interference exposure and projection exposure are combined, and It is possible to achieve an exposure apparatus capable of forming an actual circuit pattern exposure having a line width of 0.15 .mu.m or less without using a special reticle such as a Levenson reticle and a method of manufacturing a device using the same. it can

[Brief description of the drawings]

FIG. 1 is a flowchart of an exposure method of the present invention.

FIG. 2 is a schematic diagram showing an exposure pattern by two-beam interference exposure.

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

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

FIG. 5 is a schematic view showing an exposure pattern by two-beam interference 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 formation pattern 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 schematic diagram showing a typical circuit pattern.

FIG. 11 is a schematic diagram illustrating Embodiment 2 of the present invention.

FIG. 12 is a schematic diagram illustrating a two-beam interference exposure pattern according to a third embodiment of the present invention.

FIG. 13 is a schematic view showing a pattern formed by a two-dimensional block.

FIG. 14 is a schematic view showing an example of a pattern that can be formed in Embodiment 3 of the present invention.

FIG. 15 is an explanatory view of a conventional two-beam interference exposure method.

FIG. 16 is a schematic view showing two-beam interference exposure according to the present invention.

FIG. 17 is a schematic view showing a mask and an illumination method according to the present invention.

FIG. 18 is a schematic view of a main part of the exposure apparatus of the present invention.

FIG. 19 is a schematic view showing a conventional projection exposure apparatus.

FIG. 20 is a flowchart of a device manufacturing method of the present invention.

FIG. 21 is a flowchart of a device manufacturing method of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Exposure light source 12 Illumination optical system 13 Illumination mode 14 Mask 15 Replacement mask 16 Mask changer 17 Mask stage 18 Projection optical system 19 Pupil filter 20 Pupil filter changer 21 Wafer 22 Wafer stage 161 Mask 162 Object Side exposure light 163 Projection optical system 164 Aperture stop 165 Image side exposure light 166 Photosensitive substrate 167 Pupil filter and luminous flux position on pupil 171 Chrome light shield 191 Excimer laser light source 192 Illumination optical system 193 Illumination light 194 Mask 195 Object side Exposure light 196 Projection optical system 197 Image side exposure light 198 Photosensitive substrate 199 Substrate stage

Claims (7)

[Claims] 1. An exposure apparatus having a multiple exposure mode, the exposure apparatus having an illumination system and a projection system, wherein the projection system includes a plurality of light beams from a mask illuminated by the illumination system. The multi-exposure mode includes a first exposure that is performed in a state where the zero-order light is blocked by the filter, and a zero-order light that is blocked by the filter. An exposure apparatus including a second exposure performed in a state where the exposure is not interrupted. 2. The apparatus according to claim 1, wherein the filter is provided at or near a position of a pupil of the projection system.
Exposure equipment. 3. The mask used when the filter is supplied at or near the position of a pupil of the projection system, the mask having a value obtained by dividing a pitch P of a periodic pattern image to be formed on an image plane by a projection magnification. 3. The exposure apparatus according to claim 2, wherein the exposure apparatus has a periodic pattern having a double pitch. 4. The first exposure in the multiple exposure mode, wherein an exposure pattern having an exposure amount not exceeding a threshold value of the exposure target is formed on the target, and the second exposure in the multiple exposure mode is performed. In the exposure step including, an exposure pattern having an exposure amount exceeding the threshold value and an exposure amount not exceeding the threshold value is formed on the target object, and an exposure pattern obtained by synthesizing these exposure patterns and the threshold value are formed. 4. The exposure apparatus according to claim 3, wherein each of the exposure amounts is determined so that a desired circuit pattern is formed. 5. The exposure apparatus according to claim 1, wherein the first exposure is performed by ± 1 from the mask.
An exposure apparatus characterized by performing interference by the next-order diffracted light. 6. The exposure apparatus according to claim 1, wherein the exposure is performed in the order of the first and second exposures or in the reverse order. 7. A method for manufacturing a device, comprising printing a device pattern on an object to be exposed using the exposure apparatus according to claim 1. Description: