JP3535770B2 - Exposure method and exposure apparatus - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exposure method and an exposure apparatus, and more particularly to an exposure method and an exposure apparatus for exposing a photosensitive substrate with a fine circuit pattern. The exposure method and exposure apparatus of the present invention are used for manufacturing various devices such as semiconductor chips such as ICs and LSIs, display elements such as liquid crystal panels, detection elements such as magnetic heads, and imaging elements such as CCDs.

[0002]

2. Description of the Related Art Conventionally, when a device such as an IC, an LSI, or a liquid crystal panel is manufactured by using a photolithography technique, a circuit pattern of a photomask, a reticle or the like (hereinafter referred to as a "mask") is projected into a projection optical system. A projection exposure method and a projection exposure apparatus which project onto a photosensitive substrate such as a silicon wafer or a glass plate (hereinafter referred to as “wafer”) coated with a photoresist or the like and transfer (expose) onto the substrate are used. ing.

In response to the high integration of the above devices, it is required to miniaturize the pattern transferred onto the wafer, that is, to increase the resolution and to increase the area of one chip on the wafer. Also in the above-mentioned projection exposure method and projection exposure apparatus,
The resolution and the exposure area have been improved so as to form an image having the following dimensions (line width) over a wide range.

FIG. 18 shows a schematic diagram of a conventional projection exposure apparatus. In FIG. 18, 191 is an excimer laser that is a light source for far-ultraviolet exposure, 192 is an illumination optical system, 193 is illumination light, and 1
Reference numeral 94 denotes a mask, and 195 denotes a mask 194, and the optical system 1
Object-side exposure light incident on 96, 196 a reduction projection optical system, 197 image-side exposure light emitted from the optical system 196 and incident on the substrate 198, 198 a wafer which is a photosensitive substrate, 199
Shows a substrate stage for holding a photosensitive substrate.

Laser light emitted from the excimer laser 191 is guided to an illumination optical system 192 by a routing optical system, and a predetermined light intensity distribution, light distribution distribution, opening angle (numerical aperture NA), etc. are produced by the illumination optical system 192. The mask 194 is illuminated by being adjusted so that the illumination light 193 has. Mask 1
In 94, a pattern having a size in which a fine pattern formed on the wafer 198 is reciprocal times (for example, 2 times, 4 times or 5 times) the projection magnification of the projection optical system 196 is formed on a quartz substrate by chrome or the like. , The illumination light 193 is transmitted and diffracted by the fine pattern of the mask 194, and the object side exposure light 195
Becomes The projection optical system 196 transmits the object side exposure light 195,
The image side exposure light 19 for forming an image of the fine pattern of the mask 194 on the wafer 198 with the above projection magnification and a sufficiently small aberration.
Convert to 7. The image side exposure light 197 has a predetermined numerical aperture NA (= sin θ) as shown in the enlarged view of the lower part of FIG.
Converge on the wafer 198 to form an image of the fine pattern on the wafer 198. The substrate stage 199 is mounted on the wafer 198.
When a fine pattern is sequentially formed in a plurality of different areas (shot areas: one or a plurality of chips), the projection optical system of the wafer 198 is moved by step movement along the image plane of the projection optical system. Change position to 196.

However, it is difficult to form a pattern of 0.15 μm or less in the projection exposure apparatus using the above-mentioned excimer laser, which is currently the mainstream, as a light source.

The projection optical system 196 has a resolution limit due to a trade-off between the optical resolution and the depth of focus due to the exposure (used) wavelength. The resolution R and the depth of focus DOF of the resolution pattern by the projection exposure apparatus are expressed by Rayleigh's equations such as the following equations (1) and (2).

R = k ₁ (λ / NA) (1) DOF = k ₂ (λ / NA ² ) (2) where λ is the exposure wavelength and NA is the brightness of the projection optical system 196. The numerical aperture on the image side, k ₁ and k ₂ are constants determined by the development process characteristics of the wafer 198 and are usually 0.5.
It is a value of about 0.7. From these equations (1) and (2), numerical aperture N is required for high resolution with a small resolution R.
Although there is a "higher NA" for increasing A, in actual exposure, it is necessary to set the depth of focus DOF of the projection optical system 196 to a certain value or more, and thus it is impossible to further increase the NA to some extent. It can be seen that, in order to achieve higher resolution, it is necessary to “shorten the wavelength” to reduce the exposure wavelength λ after all.

However, as the wavelength becomes shorter, a serious problem occurs. This problem is that the glass material of the lens of the projection optical system 196 is used up. The transmittance of most glass materials is close to 0 in the far-ultraviolet region, and fused quartz currently exists as a glass material manufactured for an exposure apparatus (exposure wavelength of about 248 nm) using a special manufacturing method. Also drastically decreases for an exposure wavelength of 193 nm or less, and it is very difficult to develop a practical glass material in an exposure wavelength of 150 nm or less corresponding to a fine pattern of 0.15 μm or less. In addition to the transmittance, glass materials used in the far-ultraviolet region must satisfy multiple conditions such as durability, refractive index uniformity, optical distortion, and processability. Its existence is at stake.

As described above, in the conventional projection exposure method and projection exposure apparatus, in order to form a pattern of 0.15 μm or less on the wafer 198, it is necessary to shorten the exposure wavelength to about 150 nm or less. Since there is no practical glass material in this wavelength range, 0.15
It was not possible to form a pattern of μm or less.

US Pat. No. 5,415,835 discloses a technique for forming a fine pattern by two-beam interference exposure. According to the two-beam interference exposure, a pattern of 0.15 μm or less can be formed on a wafer.

The principle of the two-beam interference exposure will be described with reference to FIG. In the two-beam interference exposure, the laser beam which is a coherent and parallel light flux from the laser 151 is split into two beams by the half mirror 152, and the two beams are reflected by the plane mirror 153, respectively. Interfering fringes are formed at the intersections by intersecting the laser light (coherent parallel ray bundle) at an angle greater than 0 and less than 90 degrees, and the wafer 154 is formed by (the light intensity distribution of) the interference fringes. By exposing and exposing, a fine periodic pattern according to the light intensity distribution of the interference fringes is formed on the wafer.

When two light fluxes intersect each other on the wafer surface with the same angle in opposite directions to the vertical line of the wafer surface, the resolution R in the two light flux interference exposure is expressed by the following equation (3). To be done.

R = λ / (4 sin θ) = λ / 4NA = 0.25 (λ / NA) (3) Here, R is the width of each L & S (line and space), that is, the brightness of the interference fringes. And θ represent the widths of the light and dark areas, and θ represents the incident angle (absolute value) of the two light beams with respect to each image plane, and N
A = sin θ.

Comparing equation (1), which is the equation of resolution in normal projection exposure, with equation (3), which is the equation of resolution in two-beam interference exposure, the resolution R of two-beam interference exposure is in equation (1). Since this corresponds to the case where k ₁ = 0.25, it is possible to obtain a resolution that is at least twice as high as the resolution of normal projection exposure with k ₁ = 0.5 to 0.7 in two-beam interference exposure. . Although not disclosed in the above-mentioned US patent, for example, at λ = 0.248 nm (KrF excimer), N
When A = 0.6, R = 0.10 μm is obtained.

[0016]

However, since the two-beam interference exposure can basically obtain only a simple fringe pattern (periodic pattern) corresponding to interference fringes, it is necessary to form a circuit pattern of a desired shape on the wafer. I can't.

Therefore, the above-mentioned US Pat. No. 5,415,835 discloses a two-beam method using a simple stripe pattern by two-beam interference exposure.
After a valued exposure amount distribution is given to the resist on the wafer, ordinary lithography (exposure) is performed using a mask in which an opening having a size within the resolution range of the exposure apparatus is formed, and another binary value is obtained. It is proposed that an isolated line (pattern) be obtained by giving a different exposure dose distribution to the wafer.

However, if the double exposure of the above-mentioned US Pat. No. 5,415,835 is performed for each shot area (exposed area) of a normal wafer on which step-and-repeat exposure or step-and-scan exposure is performed, all shots are exposed. It takes a long time to complete the double exposure.

The object of the present invention is, for example, the above-mentioned US Pat.
A plurality of shot areas of a wafer with a plurality of images having different intensity distributions without development in the middle (in other words, a plurality of images giving mutually different exposure amount distributions) such as double exposure of Japanese Patent No. 415,835. It is an object of the present invention to provide an exposure method and an exposure apparatus that can reduce the time required for exposing a wafer.

[0020]

An exposure method according to the invention of claim 1
The method is an exposure method in which shot areas of a wafer are exposed with a plurality of images having different intensity distributions without developing in the middle, and a certain intensity is applied to a plurality of shot areas of each of a plurality of wafers. When the plurality of shot areas of each of the plurality of wafers are exposed with the image having another intensity distribution after the exposure of the plurality of wafers is performed,
Wafer position confirmation measuring system for measuring position
The wafer is housed in a stock carrier, and the alignment of the first exposure of the wafer is performed by the alignment mark on the wafer, and the alignment of the second exposure is performed using the alignment information on the wafer chuck. That
Is characterized by.

[0021] The exposure apparatus of the invention of claim 9, there is provided an exposure apparatus having an exposure mode in which the intensity distribution from each other to perform the exposure at different image without performing a development in the middle with respect to the shot area of the wafer, a plurality Exposure of each of the plurality of shot areas of the wafer with an image having an intensity distribution, and then exposure of each of the plurality of wafers of the plurality of shot areas with an image having another intensity distribution. The plurality of wafers in
Have a stock carrier that keeps
Cage, as characterized by being aligned when the first exposure of the wafer is performed by the alignment mark on the wafer, subjected to alignment when the second exposure using the positioning information on the wafer chuck There is.

[0022]

[0023]

The above-mentioned two types of images having different intensity distributions are the combination of the interference fringe (image) and the unblurred aperture image in US Pat. No. 5,415,835, and the interference fringe (image) and the device A combination of blurred images formed by imaging a pattern having a line width less than the resolution, or an interference fringe (image) proposed in Japanese Patent Application No. 9-304232
And a non-blurred pattern image that can give a multivalued exposure amount distribution.

The exposure apparatus of the present invention has a stock carrier for storing the above-mentioned plurality of wafers in a state in which their positions are guaranteed, and the wafers alone are stored in this stock carrier.
Alternatively, the wafer chuck may be stored together with the wafer chuck. Further, there is also a form in which this stock carrier is provided to a coater developer equipped with this stock carrier.

The present invention can be applied to any of the step-and-repeat method and the step-and-scan method, or an exposure apparatus and an exposure method that combine these methods.

In the present invention, each of the above-mentioned images is recorded in KrF (wavelength of about 2
48 nm excimer laser, ArF (wavelength about 193 n
m) An exposure device formed by using a laser beam from an excimer laser or an F2 (wavelength of about 157 nm) excimer laser and a reduction projection optical system.

This reduction projection optical system is an optical system composed of a refraction system, a reflection-refraction system or a reflection system.

According to the present invention, it is possible to provide a device manufacturing method including a step of exposing a wafer by any one of the above-mentioned exposure apparatuses and a step of developing the wafer.

[0030]

BEST MODE FOR CARRYING OUT THE INVENTION First, an embodiment of a double exposure method used in the present invention will be described with reference to FIGS.

FIG. 1 is a flowchart showing the double exposure method. FIG. 1 shows each block of a periodic pattern exposure step (fine exposure step), a projection exposure step (rough exposure step), and a development step which constitute the exposure method of the present invention and the flow thereof. The order of the projection exposure steps may be reversed from that of FIG. 1, and when either one of the steps includes a plurality of exposure steps, the steps can be alternately performed. Further, between each exposure step, there is a step of precisely aligning the shot (exposure area) on the wafer with respect to the mask and the projection optical system, but not shown here.
The periodic pattern exposure step is performed by, for example, two-beam interference exposure. No development is performed between the two-beam interference exposure and the normal exposure. The light intensity distribution of each image in these exposures is different.

When performing exposure according to the flow of FIG.
First, a wafer (photosensitive substrate) is exposed to a pattern by periodic pattern exposure as shown in FIG.
Exposure is performed in a periodic pattern as shown in. The numbers in FIG. 2 represent the exposure amount, and the shaded area in FIG.
The exposure amount of the white part is (actually arbitrary) and is zero.

When developing only such a periodic pattern after exposure, usually, the exposure threshold value E of the resist on the photosensitive substrate is used.
_th is the exposure amount 0 and 1 as shown in the lower graph of FIG.
Set between. The upper part of FIG. 2B shows a lithographic pattern (concavo-convex pattern) finally obtained.

FIG. 3 shows the exposure dose dependency of the film thickness after development and the exposure threshold value of the resist of the photosensitive substrate in this case as a positive type resist (hereinafter referred to as "positive type") and a negative type. Each of the resists (hereinafter, referred to as “negative type”) is shown. In the case of a positive type, it is above the exposure threshold value, in the case of a negative type, it is below the exposure threshold value. The film thickness becomes 0.

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 case of a negative type and a positive type.

In this embodiment, unlike this normal exposure sensitivity setting, as shown in FIG. 5 (the same drawing as FIG. 2A) and FIG. 6, periodic pattern exposure (two-beam interference exposure) is performed.
When the maximum exposure amount in 1 is set to 1, the exposure threshold value E _th of the resist on the photosensitive substrate is set to be larger than 1. In this photosensitive substrate, the exposure amount is insufficient when the exposure pattern (exposure amount distribution) subjected to only the periodic pattern exposure shown in FIG. 2 is developed. Therefore, there is some variation in film thickness, but the portion where the film thickness becomes 0 by development. Does not occur and the lithographic pattern is not formed by etching. This can be regarded as the disappearance of the periodic pattern (note that the present invention will be described using an example of the negative type here, but the present invention can also be implemented in the case of the positive type). . In FIG. 6, the upper part shows the lithography pattern (nothing can be done), and the lower part graph shows the relationship between the exposure dose distribution and the exposure threshold value. E _{1 in the} lower part represents the exposure amount in the periodic pattern exposure, and E ₂ represents the exposure amount in the normal projection exposure.

The feature of this embodiment is that a high-resolution exposure pattern, which disappears at first glance only by periodic pattern exposure, is fused with an exposure pattern of an arbitrary shape including a pattern having a size smaller than the resolution of an exposure apparatus by ordinary projection exposure. Thus, only a desired region is selectively exposed to the resist exposure threshold value or more to finally form a desired lithographic pattern.

FIG. 7A shows an exposure pattern by ordinary projection exposure, which cannot be resolved because the pattern is a fine pattern below the resolution of the exposure apparatus and the intensity distribution on the object to be exposed is blurred. .

In this embodiment, the fine pattern has a line width which is about half the resolution of normal projection exposure.

Projection exposure for forming the exposure pattern of FIG. 7A is performed after the periodic pattern exposure of FIG.
If the same resist is overlaid on the same region, the total exposure distribution of this resist is as shown in the lower graph of FIG. 7B. Here, the ratio of the exposure amount E ₁ of the periodic pattern exposure and the exposure amount E ₂ of the projection exposure is 1: 1, and the exposure threshold value E _{th of the} resist is the exposure amount E ₁ (= 1) and the exposure amount E ₁ . Since it is set within the sum (= 2) of the exposure amount E ₂ of the projection exposure, the lithography pattern shown in the upper part of FIG. 7B is formed. At that time, the center of the normal exposure pattern is made to coincide with the peak of the periodic pattern. The isolated line pattern shown in the upper part of FIG. 7B has a resolution of the periodic pattern exposure and does not have a simple periodic pattern. Therefore, a high-resolution pattern higher than the resolution of the exposure apparatus that can be realized by normal projection exposure is obtained.

Here, tentatively, projection exposure for producing the exposure pattern of FIG. 8 (projection exposure of a line width twice that of the exposure pattern of FIG. 5 and above an exposure threshold value (here, an exposure amount twice the threshold value) 5) is superimposed on the same region of the same resist without the development step after the periodic pattern exposure of FIG. At that time, the center of the pattern of the normal exposure is made to coincide with the peak of the periodic exposure, so that the position-superimposed pattern has good symmetry and a good image can be obtained. The total exposure dose distribution of this resist is as shown in FIG. 8B, and the exposure pattern of the two-beam interference exposure disappears, and finally only the lithography pattern by projection exposure is formed.

Further, as shown in FIG. 9, the theory is the same when the line width is three times as wide as that of the exposure pattern of FIG. The line width of the lithography pattern finally obtained from the combination of the exposure pattern having the width and the exposure pattern having the line darkness three times is obvious, and all the lithography patterns that can be realized by the projection exposure can also be formed in this embodiment. is there.

By adjusting the exposure amount distribution (absolute value and distribution) and the threshold value of the resist of the photosensitive substrate by each of the periodic pattern exposure and the projection exposure, which have been briefly described above, FIG. 6 and FIG. , A circuit pattern having a combination of various patterns as shown in FIGS. 8B and 9B and having a minimum line width of the resolution of the periodic pattern exposure (pattern of FIG. 7B) is formed. can do.

The principles of the above double exposure method are summarized as follows: The pattern area not subjected to projection exposure, that is, the cyclic exposure pattern below the exposure threshold of the resist disappears by the development. 2. An exposure pattern having a periodic pattern exposure resolution determined by a combination of the projection exposure and the periodic pattern exposure patterns is formed in the pattern area of the projection exposure performed with the exposure amount less than the exposure threshold of the resist. 3. In the pattern area of the projection exposure performed with the exposure amount equal to or more than the exposure threshold value, a fine pattern which is not resolved only by the projection exposure is also formed. It turns out that. Further, as an advantage of the exposure method, if the periodic pattern exposure having the highest resolution is performed by the two-beam interference exposure, a much larger depth of focus can be obtained as compared with the ordinary exposure.

In the above description, the order of the periodic pattern exposure which is the fine exposure and the projection exposure which is the rough exposure is the periodic pattern exposure first, but it is not limited to this order.

Next, another embodiment of double exposure will be described.

The present embodiment is intended for a so-called gate type pattern shown in FIG. 10 as a circuit pattern (lithographic pattern) obtained by exposure.

In the gate pattern of FIG. 10, the minimum line width in the horizontal direction, that is, in the AA 'direction in the figure is 0.1 μm, while it is 0.2 μm or more in the vertical direction. According to the present invention, high resolution is required only in such a one-dimensional direction.
For a dimensional pattern, periodic pattern exposure by, for example, two-beam interference exposure may be performed only in such a one-dimensional direction that requires high resolution.

In this embodiment, an example of a combination of periodic pattern exposure in only the one-dimensional direction and normal projection exposure will be shown with reference to FIG.

In FIG. 11, FIG. 11A shows a periodic exposure pattern by two-beam interference exposure in only the one-dimensional direction. The period of this exposure pattern is 0.2 μm, and this exposure pattern corresponds to a line width of 0.1 μmL & S pattern. Numerical values in the lower part of FIG. 11 represent the exposure dose.

An exposure apparatus for realizing such two-beam interference exposure includes an interferometer-type demultiplexing / multiplexing optical system including a laser 151, a half mirror 152, and a plane mirror 1534 as shown in FIG. As shown in FIG. 15, there is a projection exposure apparatus in which a mask and an illumination method are configured as shown in FIG. 16 or FIG.

The exposure apparatus of FIG. 14 will be described.

In the exposure apparatus of FIG. 14, as described above, the two light fluxes that are combined are obliquely incident on the wafer 154 at the angle θ, and the line width of the interference fringe pattern (of the exposure pattern) that can be formed on the wafer 154 is the above (3). It is represented by a formula. The relationship between the angle θ and the NA on the image plane side of the demultiplexing / multiplexing optical system is NA = sin θ. The angle θ can be arbitrarily adjusted and set by changing the angle of each of the pair of plane mirrors 153. If the value of the pair of plane mirror angles θ is set large, the line width of each fringe of the interference fringe pattern becomes small. . For example, the wavelength of two light beams is 24
In the case of 8 nm (KrF excimer), an interference fringe pattern having a line width of about 0.1 μm can be formed even if θ = 38 degrees.
At this time, NA = sin θ = 0.62. Angle θ
It is needless to say that a higher resolution can be obtained by setting the value larger than 38 degrees.

Next, the exposure apparatus shown in FIGS. 15 to 17 will be described.

The exposure apparatus of FIG. 15 is, for example, a projection exposure apparatus using an ordinary reduction projection optical system (consisting of a large number of lenses), and at present, with an exposure wavelength of 248 nm, NA0.
There are more than six.

In FIG. 15, 161 is a mask, 162 is the object-side exposure light that emerges from the mask 161 and enters the optical system 163, 163 is a projection optical system, 164 is an aperture stop, and 165 is a wafer that exits the projection optical system 163. Image side exposure light incident on 166, 166 indicates a wafer which is a photosensitive substrate, and 167
FIG. 6 is an explanatory diagram showing a position of a light beam on a pupil plane corresponding to a circular aperture of a diaphragm 164 by a pair of black dots. FIG. 15 is a schematic diagram showing a state in which two-beam interference exposure is performed, and both the object-side exposure light 162 and the image-side exposure light 165 differ from the normal projection exposure of FIG. Made of.

In order to perform the two-beam interference exposure in the ordinary projection exposure apparatus as shown in FIG. 15, the mask and its illumination method may be set as shown in FIG. 16 or FIG.
These three examples will be described below.

FIG. 16 shows a Levenson-type phase shift mask, in which the pitch P of the light shielding portions 171 made of chrome.
_{In the} mask, _O is represented by equation (4) and the pitch P _OS of the phase shifter 172 is represented by equation (5).

P _O = P / M = λ / {M · (2NA)} (4) P _OS = 2P _O = λ / {M · (NA)} (5) where M is a projection The projection magnification of the optical system 163, λ is the exposure wavelength, and NA is the image-side numerical aperture of the projection optical system 163.

On the other hand, the mask shown in FIG. 16 (b) is a shifter-edge type phase shift mask made of chrome and having no light-shielding portion, and the pitch P _OS of the phase shifter 181 is expressed by the equation (5) as in the Levenson type. It is configured to meet.

To perform two-beam interference exposure using the phase shift masks of FIGS. 16A and 16B, σ = 0 (or a value close to 0), so-called coherent illumination or σ = is applied to these masks. Provide a partially coherent illumination of ~ 0.3. Specifically, the mask is irradiated with a bundle of parallel rays or a light flux with a small opening angle from a direction perpendicular to the mask surface (direction parallel to the optical axis).

When such illumination is performed, the 0th-order transmitted diffracted light emitted from the mask in the above-described vertical direction becomes a phase difference of adjacent transmitted light of π due to the action of the phase shifter, and there is no mutual cancellation. ± 1st order of transmitted diffracted light 2
The parallel light flux is generated from the mask symmetrically with respect to the optical axis of the projection optical system 163, and the two object side exposures in FIG. 15 interfere on the wafer. Further, since the diffracted light of the second and higher orders does not enter the aperture of the aperture stop 164 of the projection optical system 163, it does not contribute to image formation.

The mask shown in FIG. 17 is a mask in which the pitch P _O of the light shielding portions of the light shielding portions made of chromium is represented by the equation (6) similar to the equation (4).

P _O = P / M = λ / {M · (2NA)} (6) where M is the projection magnification of the projection optical system 163, λ is the exposure wavelength, and NA is the image of the projection optical system 163. The numerical aperture on the side is shown.

The mask having no phase shifter shown in FIG. 17 is provided with oblique incidence illumination by one or two parallel ray bundles. In this case, the incident angle θ ₀ of the parallel light flux on the mask is
It is set so as to satisfy the expression (7). In the case of using two parallel ray bundles, θ _{0 in} opposite directions with respect to the optical axis
Illuminate the mask with an inclined bundle of parallel rays.

Sin θ ₀ = M · NA (7) Here, M is the projection magnification of the projection optical system 163, and NA is the image-side numerical aperture of the projection optical system 163.

When the mask not having the phase shifter shown in FIG. 17 is obliquely illuminated by the parallel light flux satisfying the above equation (7), the mask goes straight at an angle θ ₀ with respect to the optical axis. Two beams of the first-order transmitted diffracted light and the zero-order transmitted-diffracted light traveling along an optical path symmetrical to the optical path of the zero-order transmitted-diffracted light and the optical axis of the projection optical system (advancing at an angle -θ ₀ with respect to the optical axis) Occurs as the two object-side exposure lights 162 in FIG. 15, and these two light beams enter the aperture of the aperture stop 164 of the projection optical system 163 to form an image.

Note that, in the present invention, such oblique incidence illumination by one or two parallel ray bundles is also treated as "coherent illumination".

The above is the technique for performing the two-beam interference exposure using the ordinary projection exposure apparatus, and the illumination optical system of the ordinary projection exposure apparatus as shown in FIG. 18 is configured to perform the partial coherent illumination. Therefore, the aperture stop (not shown) corresponding to 0 <σ <1 of the illumination optical system in FIG. 18 can be replaced with a special aperture stop corresponding to σ≈0 or 0 <σ <0.3. , The projection exposure apparatus can be configured to provide substantially coherent illumination.

Returning to the description of the embodiment shown in FIGS.

In this embodiment, normal projection exposure which is rough exposure performed after the periodic pattern exposure which is fine exposure by the above-described two-beam interference exposure (for example, partial coherent illumination is performed on the mask by the apparatus of FIG. 18). thing)
Then, the gate pattern shown in FIG. 11B is exposed. The upper part of FIG. 11B shows the relative positional relationship with the periodic pattern by the two-beam interference exposure and the exposure amount in the area of the exposure pattern of the normal projection exposure, and the lower part of the same figure shows the normal projection exposure. The exposure amount for the resist on the wafer is mapped with a resolution of 0.1 μm pitch in the vertical and horizontal directions.

The portion of the minimum line width of the exposure pattern formed by this projection exposure is not resolved and widens, and the value of each point of the exposure amount decreases. The exposure amount is roughly, the center portion of the pattern is large, and both sides are small, It is represented by a and b, and the central portion where the blurred images come from both sides is c. A multi-valued exposure amount distribution in which the exposure amount is different for each region is generated. Here, the exposure amount is 1 <a <2 0 <b <1 0 <c
<1. The exposure amount ratio in each exposure when using this mask is two-beam interference exposure: projection exposure = 1: 2 on the wafer (photosensitive substrate).

A state in which the fine circuit pattern of FIG. 10 is formed by combining the above-described periodic pattern exposure and normal projection exposure will be described. In this embodiment, there is no development process between the periodic pattern exposure by the two-beam interference exposure and the normal projection exposure. Therefore, the exposure amount in the area where the exposure patterns of the respective exposures overlap is added, and a new exposure pattern is generated by the added exposure amount (distribution).

The upper part of FIG. 11C is the same as that of FIG.
11 shows an exposure amount distribution (exposure pattern) resulting from adding the exposure amounts of the exposure pattern of (a) and the exposure pattern of FIG. 11 (b), where the exposure amount of the area indicated by e is 1 + a
Is greater than 2 and less than 3. The lower part of FIG. 11C shows the pattern resulting from the development of this exposure pattern in gray. In this embodiment, the resist on the wafer has an exposure threshold value greater than 1 and less than 2, so that only the portion where the exposure amount is greater than 1 appears as a pattern due to development. Figure 11
The shape and size of the pattern shown in gray in the lower part of (c) are the same as the shape and size of the gate pattern shown in FIG. 10, and have a fine line width of 0.1 μm by the exposure method of the present invention. The circuit pattern can be switched between partial coherent illumination and coherent illumination, and σ
It can be formed using a projection exposure apparatus having an illumination optical system in which the value of (sigma) can be changed within the range of 0 <σ <1.

FIG. 12 and FIG. 13 show specific examples when a stepper (projection exposure apparatus) using a KrF excimer laser as a light source for emitting a laser beam having a wavelength λ = 248 nm is used. A gate pattern having a minimum line width of 0.12 μm as shown in FIG. 12 is normally exposed, and a periodic pattern is exposed by a Levenson-type phase shift mask so as to overlap with the minimum line width. The exposure conditions are shown below.

The NA of the projection lens is 0.3, and the illumination system is a normal illumination having a σ of 0.3 in exposure with a Levenson mask. In the normal mask exposure, σ outside the ring is 0.8 and σ inside the ring is 0. It was set as an annular illumination of 0.6. The exposure amount for the normal mask exposure was set to twice the exposure amount for the periodic pattern exposure.

In FIG. 13, the uppermost row shows the exposure dose distribution on the wafer when the periodic pattern is created, the second row shows the exposure dose distribution in the normal exposure, and the third row shows the double exposure of the periodic pattern and the normal exposure. The exposure amount distribution and the pattern on the wafer by the resist are shown in the fourth row.

Defocus is 0 μm from the left in each step.
To 0.2 μm and 0.4 μm.

As shown in the second row of FIG. 13,
Although only the normal exposure makes it impossible to obtain a fine gate pattern by blurring, by superimposing the periodic pattern of the first stage of FIG. 13, the fine portion is resolved as shown in the third stage of FIG. A desired gate pattern as shown in the fourth row of FIG. 13 was created.

FIG. 19 is a schematic diagram showing an example of an exposure apparatus for two-beam interference exposure for performing periodic pattern exposure. In FIG. 19, 201 is a two-beam interference exposure optical system, the basic structure of which is shown in FIG. It is the same as the optical system. 202
Is a KrF or ArF excimer laser, 203 is a half mirror, 204 is a plane mirror, and 205 is an off-axis type alignment optical system in which the positional relationship with the optical system 201 is fixed or can be appropriately detected as a baseline (quantity). The alignment mark for two-beam interference on 206 is observed and its position is detected. 206 is a wafer which is a photosensitive substrate, 2
Reference numeral 07 denotes a plane orthogonal to the optical axis of the optical system 201 and an XYZ stage movable in the optical axis direction, the position of which is accurately controlled using a laser interferometer or the like. Device 205 and 2
Since the configuration and function of 07 are well known, a detailed description will be omitted.

FIG. 20 is a schematic diagram showing a high-resolution exposure apparatus including a two-beam interference exposure apparatus for performing periodic pattern exposure, which is fine exposure, and an ordinary projection exposure apparatus, which is rough exposure.

In FIG. 20, reference numeral 212 denotes a two-beam interference exposure apparatus including the optical systems 201 and 205 shown in FIG.
Reference numeral 13 denotes an illumination optical system (not shown), a reticle alignment optical system 214, a wafer alignment optical system (off-axis alignment optical system) 217, and a projection optical system 216 for reducing and projecting the circuit pattern of the mask 215 onto the wafer 218. It is a normal projection exposure apparatus including. KrF (wavelength about 248 nm) excimer laser is used as the illumination light.
ArF (wavelength about 193 nm) or F2 (wavelength about 157n)
m) Laser light from an excimer laser, and the reduction projection optical system 216 is composed of any one of a refraction system, a catadioptric system, and a reflection system.

The reticle alignment optical system 214 observes the alignment mark on the mask 215 and detects its position. The wafer alignment optical system 217 observes the alignment mark for projection exposure on the wafer 206 or also for two-beam interference, and detects the position. Optical system 214, 21
Since the configurations and functions of Nos. 6 and 217 are well known, detailed description thereof will be omitted.

Reference numeral 219 in FIG. 20 is a two-beam interference exposure apparatus 2
12 and the projection exposure apparatus 213 are one XYZ stage, and this stage 219 is used by the apparatus 212,
It is movable in a plane orthogonal to each optical axis 13 and the optical axis direction, and its position in the XY directions is accurately controlled by using a laser interferometer or the like.

Stage 219 holding wafer 218
Is fed to the position (1) in FIG. 20 and the position is accurately measured, and the device 2 shown at the position (2) is based on the measurement result.
The wafer 218 is sent to the exposure position 12 for two-beam interference exposure, then sent to the position (3) and the position is accurately measured, and the device 213 shown at the position (4) is used.
And is projected to the wafer 218 for projection exposure.

In the apparatus 213, instead of the off-axis alignment optical system 217, the alignment mark on the wafer 218 is observed via the projection optical system 216 and the alignment of a TTL (not shown) for detecting the position is performed. An optical system or a TTR alignment optical system (not shown) for observing the alignment mark on the wafer 218 through the projection optical system 216 and the mask (reticle) 215 and detecting the position can be used.

FIG. 21 is a schematic diagram showing a high resolution exposure apparatus capable of performing both periodic pattern exposure which is fine exposure and normal projection exposure which is rough exposure.

In FIG. 21, reference numeral 221 denotes a KrF (wavelength of about 248 nm) excimer laser, ArF (wavelength of about 193n).
m) Excimer laser or F2 (wavelength about 157 nm) excimer laser, 222 is an illumination optical system, 223 is a mask (reticle), 224 is a mask stage, 227 is a mask 2
A projection optical system 225 for reducing and projecting the circuit pattern of 23 onto a wafer 228 is a mask (reticle) changer, and an ordinary reticle (a reticle for rough) and a Levenson type phase shift mask (fine reticle) described above are mounted on a stage 224. ) Or edge shifter type mask (f
It is provided to selectively supply one of the reticle for ine) and the periodic pattern mask (reticle for fine) having no phase shifter. The reduction projection optical system 227 is composed of any one of a refraction system, a catadioptric system, and a reflection system.

Numeral 229 in FIG. 21 is one XYZ stage which is commonly used for the periodic pattern exposure and the projection exposure by the two-beam interference, and this stage 229 is arranged in the plane orthogonal to the optical axis of the optical system 227 and in this optical axis direction. It is movable and its position in the XY directions is accurately controlled using a laser interferometer or the like.

The apparatus shown in FIG. 21 is equipped with the reticle alignment optical system 214 and the wafer alignment optical system 217 shown in FIG.

The illumination optical system 222 of the apparatus shown in FIG. 21 is configured to be capable of switching between partial coherent illumination and coherent illumination. In the case of coherent illumination, the above-described (1a) or ( The illumination light of 1b) is supplied to one of the above-described Levenson-type phase shift reticles or edge shifter-type reticles or periodic pattern reticles that do not have a phase shifter, and is illustrated in block 230 for partially coherent illumination. (2)
Illumination light is supplied to a desired reticle on which a circuit pattern is formed. Switching from the partial coherent illumination (σ> 0.5) to the coherent illumination is performed by changing the aperture stop, which is usually placed immediately after the fly-eye lens of the optical system 222, from the normal stop to a coherent illumination stop having a sufficiently small aperture diameter. You can replace it with A partial coherent illumination diaphragm with 0 <σ <0.3 may be used instead of the coherent illumination diaphragm.

FIG. 22 is a flow chart showing the first embodiment of the present invention, in which the projection exposure apparatus of FIG. 21 is used to perform double exposure on a large number of shot areas of 228 wafers. Is shown.

As can be understood from FIG. 22, according to the present embodiment, a “rough reticle” or a Levenson type phase shift reticle, which is a normal reticle in which a circuit pattern is first formed on the reticle stage of the exposure apparatus. Where a reticle for two-beam interference such as the "fine reticle" is installed, basically, for all shot areas of a large number of shot areas (exposed areas) of a wafer, Perform step-and-repeat exposure or step-and-scan exposure with an image having a light intensity distribution corresponding to one of the set reticles,
Next, in place of this one reticle, the other reticle is set on the reticle stage, and basically, for all shot areas of a large number of shot areas of the wafer exposed using this one reticle, Step-and-repeat exposure or step-and-scan exposure is performed by an image having (another) light intensity distribution corresponding to the other reticle installed. Here, a combined reticle in which the rough reticle pattern and the fine reticle pattern are formed on a common substrate may be used.

By performing such step-and-repeat exposure or step-and-scan exposure, it is possible to perform double exposure for a large number of shot areas on the wafer in a short time.

FIG. 23 is a flow chart showing the second embodiment of the present invention. Using the projection exposure apparatus of FIG. 21, for example, a lot of wafers 228 in one lot are used for respective shot areas. 2 shows a procedure for performing double exposure.

As can be seen from FIG. 23, according to the present embodiment, a "rough reticle" or a Levenson type phase shift reticle, which is a normal reticle in which a circuit pattern is first formed on the reticle stage of the exposure apparatus. Where a reticle for two-beam interference such as that described above is installed, either one of the "fine reticle" is installed, and a large number of wafers for one lot are sequentially arranged. All shots are subjected to step-and-repeat exposure or step-and-scan exposure with an image having a light intensity distribution corresponding to one of the set reticles and stored in a stock carrier, and then one of these Replace the reticle with the other reticle on the reticle stage and store it in the stock carrier. Removed from preparative fraction of large number of sequential carrier wafer, exposure using one of the reticle above is performed for essentially all the shot areas plurality of shot areas of the wafer taken out from the carrier,
Step-and-repeat exposure or step-and-scan exposure is performed by an image having (another) light intensity distribution corresponding to the other reticle installed. Also here, a combined reticle in which the rough reticle pattern and the fine reticle pattern are formed on a common substrate may be used.

By performing such step-and-repeat exposure or step-and-scan exposure, it is possible to perform double exposure in a short time on a large number of shot areas on the wafer.

FIG. 26 is a flowchart of the third embodiment of the present invention.

FIG. 26 shows a flowchart for performing exposure by distinguishing between normal exposure and double exposure. In the device manufacturing process of this embodiment, a wafer adsorption function called Vac (wafer vacuum setting) is provided in order to perform the wafer without removing it from the wafer chuck. The wafer chuck of this embodiment uses negative pressure, but if the wafer is fixed on the chuck, for example, an electrostatic adsorption method or a mechanical clamp may be used.

When the program for processing the wafer is executed in FIG. 26, first, the value of Vac is initialized (= 0) (step 301). The judgment (double exposure?) In the first half (step 305) is based on the information set in JOB (contents for instructing wafer conditions).
Vac = 1 is set in the condition setting (step 307).
In the latter half of the IF statement (step 315), it is judged whether or not the exposure is to be performed twice, and the reticle is replaced (step 30).
9) Do. If the fine side reticle has been set, set rough. Naturally, here
Although not shown, the reticle is aligned.

When the reticle exchange (step 309) is completed, the second exposure has the same flow as the normal single exposure. Therefore, the condition value Vac = 0 is set (step 308). In this way, in the latter half IF statement (step 315), it is determined that the exposure is normal, and the exposure of one wafer is completed and the next reticle is supplied without accidentally replacing the reticle. The steps for double exposure in this flowchart are steps 305, 306, and 30.
7, 308, 309, 315. At the time when the first exposure is completed, the reticle is replaced while holding the wafer on the chuck on the wafer stage without collecting the wafer.
The positional relationship of the wafer in the apparatus is maintained, and fine alignment measurement for measuring the wafer position is omitted. Naturally, the time for taking out the wafer from the carrier and the pre-alignment measurement of the wafer are omitted. As a result, high productivity can be realized by omitting the work, and high precision can be maintained since the fine alignment is performed once.

FIG. 27 is a flowchart of the fourth embodiment of the present invention.

FIG. 27 is a flowchart added to FIG. In FIG. 26, the reticle is exchanged for each wafer. Here, reticles are exchanged in lot units. A function called Lot is added for processing in lot units. Similar to the case of Vac, initialization is performed (= 0) even in Lot. During normal exposure, Lot becomes 0. Even in double exposure, Lot is always 0 when processing is performed in wafer units as in the case of FIG. When processed in lot units, Lot has a value of 1 or 2. Lot
= 1 is the first exposure condition. The second exposure is made when Lot = 2. And, Vac is always 0. That is, when the processing for each wafer is completed, the wafer is removed from the wafer chuck. By introducing lot units,
The number of reticle exchanges is reduced, further improving productivity. In the third embodiment, accuracy is maintained by not removing the wafer from the wafer chuck.

In this embodiment, the stock carrier is used so that the wafer can be stored while maintaining the positional relationship of the wafers in the apparatus. This makes both precision and productivity compatible.

The flowchart will be described. Vac and Lo
Initialize t. Fine as in step 302
Reticle for use with or for rough (step 32
2) Do. The first wafer is loaded and pre-aligned, the wafer is placed on the chuck in step 324, and the alignment (step 344) is executed. First, it is determined in step 325 whether double exposure or normal exposure is performed. In the case of double exposure, it is always Yes. Next, in step 327, it is determined whether to process wafers or lots. Here, if No, that is, in wafer units,
It operates in the same way as shown in FIG. The value of Lot is set to 0 (step 328). Step 328
Is set to 0 at the time of initialization in step 321, and may be omitted.

When the lot process is selected, it is judged in step 329 whether it is the first exposure or the second exposure. 1
At the time of the second time, Lot = 1 at step 340. At the time of the second time, Lot = 2 at step 341. In either case, Vac = 0, and the wafer is set to be separated from the wafer chuck as described above.

Next, exposure of all shots in the wafer is executed (steps 346 to 348). When exposure of all shots is completed, the determination of step 349 is executed. This is a portion corresponding to the IF statement (step 315) in FIG. 26. When processing is performed on a wafer-by-wafer basis, the process proceeds to Yes, and the reticle exchange is performed in step 350. This time, since it is the lot processing, the result is No, and the process goes to a new IF statement (step 351).

At step 351, it is judged whether the exposure is the first exposure or the second exposure in the lot process. The first exposure is Yes, and the process proceeds to step 352. The second exposure is No, and the process proceeds to step 353. There are other patterns that result in No, which is the case of the normal exposure or the second exposure performed in wafer units. In either case, the exposure is completed, and in step 353, the wafer is collected by the wafer carrier or the coater developer. In order to perform the second exposure, in the case of lot processing, the next wafer supply source is not the wafer carrier or coater developer,
This is a stock carrier that stores wafers that have been exposed for the first time. The IF statement (step 356) is executed to determine whether to bring the wafer from the stock carrier. 2 of all wafers in step 358
Until the second exposure is completed, the operation is to bring the wafer from the stock carrier.

Now, during the first exposure in the lot processing,
IF statement Step 351 becomes Yes, and Step 352
Is executed. The wafer for which the first exposure has been completed is sent to the stock carrier. Until all the wafers in the lot are processed in step 354, the process returns to step 323 again to supply a new wafer, the wafer is taken out from the wafer carrier or the like, and the above-described processing for wafer alignment is performed. When the processing of all the wafers in the lot is completed, the determination statement in step 354 becomes Yes. 1
Since the exposure for the second time has been completed for all the wafers, the reticle is replaced (step 357). The first exposure is fine
If so, the reticle for rough is exchanged for the second exposure. On the contrary, if the first exposure is rough, the fine reticle is replaced for the second exposure.

The first exposure is completed and the second exposure is started. The wafer stored in the stock carrier after completion of the first exposure must be supplied to the exposure stage again. Reticle exchange (step 35)
After 7), the step 323 of bringing the wafer from the wafer carrier or the coater developer is not performed. At step 360, the wafer is removed from the stock carrier. Then, in step 361, the positional deviation of the wafer that occurs when the wafer is stored in the stock carrier is corrected. The correction is obtained by a wafer position confirmation measuring system as shown in FIG. The correction method will be described later with reference to FIG.

By step 361, step 362
Thus, even if the wafer is reloaded on the wafer chuck, the positional relationship before the wafer is separated can be almost reproduced. The slight misalignment that remains at this time is within the measurement range of the fine alignment mark measurement (step 344). In step 363, the wafer position is measured in order to correct this slight positional deviation. The measurement system is the same as in step 344, but the points to be measured need not be plural points as in step 344. The measurement results of a plurality of points have already been stored in the first measurement, and the wafer position can be completely restored to the original relationship by selecting at least two points that are separated from each other among the plurality of points. .

Thus, depending on the stock carrier,
Not only does pre-alignment for the second exposure be omitted, but the fine alignment time is also greatly reduced. This makes it possible to improve productivity without deteriorating alignment accuracy.

The alignment measurement (step 344) can be omitted by the correction in step 363.
4 and step 325. Step 3
After 25, the process proceeds while making the judgment as described above. Then, the second exposure is completed, and the wafer is returned to the wafer carrier and the coater developer in step 353. Similar operations are performed via steps 346, 358, and 360 to bring the next wafer from the stock carrier.

When all wafers are processed, step 358 is performed.
Is YES, the process proceeds to END (step 364), and all processing is completed.

FIG. 28 shows a schematic diagram of an embodiment of the stock carrier described in the flowchart of FIG.

The flow of the wafer will be described. In the process of step 323 in FIG. 27, the robot 397 takes out the wafer into the apparatus from the interface with the wafer carrier or coater developer in step 396. The flow of the wafer at that time is represented by 407. The wafer moves to wafer pre-alignment 395 as indicated by arrow 408. The wafer pre-alignment 395 includes a mechanism 447 capable of rotating + horizontal movement and a measuring system 446 capable of pre-alignment measuring the wafer position. Here, the wafer is pre-aligned. Then, as shown by an arrow 409, it heads to the chuck on the stage. This corresponds to the block of step 324 in FIG. 27.

Next, for fine alignment, the position of the wafer is measured by using the alignment measuring system of step 385 or step 387, and the stage is corrected. This corresponds to the block of step 344 in FIG. 27. The illumination system 381 illuminates the reticle 382, and the reduction projection lens 384 projects the reticle pattern onto the wafer. This corresponds to the block near step 347 in FIG.

Up to this point, there is no difference from normal exposure. A stock carrier 386 is added in the exposure apparatus in order to perform double exposure efficiently. Reference numeral 394 is a robot for carrying the wafer to the stock carrier 386.

When the wafer is subjected to double exposure, the arrow 41
Heading to the stock carrier 386, as shown at 0,411. This operation corresponds to the block of step 352 in FIG.

The inside of the stock carrier is as shown in the right diagram of FIG. 28, and chucks corresponding to the wafer chucks 392 on the exposure stage 389 are arranged in each stage. The first wafer 401 is the lower chuck 40.
It is installed in 0. Positioning pins 399 are located around the chuck. This is to correct an error that the stock transfer robot 394 is carrying to the stock carrier.

First, the wafer is placed on the chuck with the pins retracted. In this state, the wafer position confirmation measurement system 3
97 measures the wafer position. This measured value is A.
Next, the pins are taken out and the wafer is positioned. Then, the measurement is again performed by the wafer position confirmation measuring system 397. Let this value be B. The difference between the value A and the value B is the transport error of the robot 394. This transport error is again caused by the exposure stage 389.
The same amount occurs when returning to. Within the stock carrier,
Although it was corrected by the positioning pin 399, it cannot be corrected when returning to the exposure stage. Therefore, only (value B-value A)
The exposure stage 38 is used when the wafer is remounted on the chuck.
A means for moving and correcting 9 is taken.

The wafer position confirmation measurement system 397 is
A mechanism 405 capable of rotating up and down is provided so that it can move to each stage. Positioning pin 399 is 3
There are more than one place, up and down movement by a mechanism not shown,
It has a function of moving to a predetermined position in the XY plane.
In addition, the wafer position confirmation measurement system 397 and the positioning pin 3
In order to correct the initial position error of 99, it also has a function of performing correction on the reference wafer. Each stage has a correction value C. The actual correction amount is (BA) -C.

With this correction, even if the wafer returns to the exposure stage at arrows 412 and 413, it is not necessary to return it to the pre-alignment station 395 because it is out of the fine alignment measurement. Furthermore, since it is possible to return with good reproduction, as described above, step 34
It is also possible to eliminate the need for fine alignment at a plurality of points such as No. 4.

FIG. 29 is an explanatory view of another embodiment of the stock carrier according to the present invention. The difference from FIG. 28 is that the wafer chuck and the wafer are loaded as a set into the stock carrier. Fine alignment 3 before the first exposure
At 44, the relationship between the wafer + chuck position measurement mark 428 mounted on the chuck 432 and the wafer is stored.
Wafer + chuck position measurement mark 428 is chuck 43
At least two or more of them are mounted on No. 2 and are larger than the exposure size, and are separated by 50 mm or more. The distant position is for accurately measuring the θ component.

When the wafer is carried into the stock carrier 427 after the first exposure is completed, that is, the arrow 451,
In the step of 452, the chuck and the wafer are conveyed in an adsorbed state so as not to lose their relative relationship. This is because the source of the negative pressure was obtained from the stage when in the exposure stage 429, but when the hand of the stock transfer robot 434 picks up the chuck 432 integrated with the wafer 433, the negative pressure is applied from the hand side. To be supplied. Therefore, the wafer 434 is transported to the stock carrier without leaving the chuck 433.

Although not shown, the stock carrier also has a negative pressure supply source, and when the chuck 433 is placed like the chuck 442, the negative pressure is supplied from the stock carrier side. Here again, the wafer 434 is safely stored in the stock carrier without leaving the chuck. Although a negative pressure is used to prevent the positional relationship between the wafer and the chuck from being changed, naturally there is no problem in the present invention even if a mechanical clamp or electrostatic force is used. As in FIG. 28, a wafer position confirmation measurement system 438 is provided in the stock carrier. Although the use is slightly different, it has two scopes (measurement system), a chuck scope 443 and a wafer scope 444. Scope 433
And the scope 444 may be combined. In order to process the measurement in parallel, in this embodiment, they are separately provided. This measurement system 488 is equipped with a mechanism 445 that can move up and down so that it can move to each stage.

For the second exposure, the exposure stage 43
Even when the arrows 453 and 454 are moved to move to the position 2, the chuck and the wafer are mounted on the stage again with the positional relationship maintained by the negative pressure. This corresponds to the block of step 362 in FIG. In the block of the next step 363, since the positional relationship between the chuck and the wafer is maintained, the wafer + chuck position measurement mark 428 can be seen without looking at the fine alignment mark on the wafer.
May be measured by the alignment optical systems 425 and 424. Then, the position of the chuck on the exposure stage can be known.

At the time of the first exposure, the positional correlation between the mark 428 and the wafer mark is known, and since the positional relationship is maintained by the negative pressure, the position of the mark 428 can be returned to the first exposure position. For example, the wafer can be returned to the same position as the first time. By this method, not only the time for measuring a plurality of alignment marks is shortened, but also the measurement for the second exposure is performed by the position measurement mark 428 formed not on the wafer but on the quartz glass such as chromium.
Therefore, there is no influence of process deception that occurs during wafer measurement.

As a matter of course, the wafer pre-alignment 4
There is no return to the pre-alignment work block as done at 35. It has a highly reliable structure.

Further, in order to improve reliability, there is the wafer position confirmation measuring system 438 described above. Originally, the chuck and the wafer should be stored in the stock carrier while maintaining the relationship. This is because the wafer position confirmation measuring system 438 chucks whether or not a deviation has occurred due to some trouble. Further, when the position of the mark 428 is measured on the stage, the error is twice as much as the error when the mark is transferred to the stock carrier so as not to deviate from the measurement range of the alignment optical systems 425 and 424 due to the transfer error of the stock transfer robot 434. It also has a function to correct the quantity.

In FIG. 29, when the first exposure is completed for each wafer, the chuck is performed on the stock carrier. Therefore, there is no chuck on the exposure stage. Even if the next exposed wafer is prepared, it cannot be placed because there is no chuck. Although not shown because the figure becomes complicated, there is a chuck carrier like the stock carrier. A plurality of chucks are stored in the chuck carrier. At the same time as the exposure is completed and the stock is unloaded, a new chuck is loaded from the chuck carrier. A stock transfer robot or a carrier wafer transfer robot may be used as a loading robot, but a dedicated chuck transfer robot is preferable in terms of productivity because it can perform parallel processing.

In the double exposure according to the present invention, productivity is improved without deteriorating wafer alignment accuracy, omitting reticle exchange, wafer supply / collection time and alignment time. It should be noted that whether to process wafers or lots may be automatically determined based on the production time (throughput).

The stock carrier and chuck carrier are
Although described in the case of being in the exposure apparatus, as another embodiment, an I / F provided between the coater developer and the stepper.
May be in the department or coater developer.

As a fifth embodiment of the present invention, when the double exposure mode is selected in the exposure apparatus in which the normal exposure mode and the double exposure mode can be selected, the exposure mode further shown in the flowchart of FIG. There is a mode in which any one of the exposure modes shown in the flowchart of FIG. 23 can be selected. For example, the time required from resist coating to resist development is calculated for each exposure mode based on the characteristics of the resist applied to the wafer 228, and the exposure mode that requires a shorter time is selected.

Further, in the projection exposure apparatus of the first to third embodiments, it is possible to select which of the "rough reticle" and the "fine reticle" to perform the exposure first.

24 and 25 are schematic views of an exposure apparatus suitable for performing the exposure mode shown in FIG. 23, respectively.
The difference between the exposure apparatus of FIG. 24 and that of FIG. 25 is that the internal structure of the stock carrier for storing a large number of wafers of one lot that has been exposed by one of the double exposures and the wafer chuck Whether to store each.

22 to 25 show the case where the projection exposure apparatus of FIG. 21 is used to perform double exposure by the step-and-repeat method or the step-and-scan method. However, the apparatus of FIG. 18 and the apparatus of FIG. It is also possible to perform double exposure by a step-and-repeat method or a step-and-scan method by using an exposure apparatus in which the above are combined or the exposure apparatus of FIG.

Using the exposure method and exposure apparatus described above, various devices such as semiconductor chips such as IC and LSI, display elements such as liquid crystal panels, detection elements such as magnetic heads, and image pickup elements such as CCDs can be manufactured. .

The present invention is not limited to the embodiments described above, but can be variously modified without departing from the spirit of the present invention. In particular, it is possible to appropriately select the number of exposures, the number of steps of the exposure amount, and the amount of blur in each step of the two-beam interference exposure and the normal exposure, and it is also possible to appropriately adjust the exposures by shifting them. is there. By making such adjustments, variations in the circuit patterns that can be formed increase.

[0140]

As described above, according to the present invention, a plurality of shot areas on a wafer can be subjected to double exposure or triple or more overlapping exposure in a short time.

[Brief description of drawings]

FIG. 1 is a flowchart of double exposure.

FIG. 2 is an explanatory diagram showing a periodic pattern (exposure pattern) obtained by two-beam interference exposure.

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

FIG. 4 is an explanatory diagram showing pattern formation by development.

FIG. 5 is an explanatory diagram showing a periodic pattern (exposure pattern) by ordinary two-beam interference exposure.

FIG. 6 is an explanatory diagram showing a periodic pattern (exposure pattern) by two-beam interference exposure in the present invention.

FIG. 7 is an explanatory diagram showing an example of an exposure pattern (lithography pattern) that can be formed in the first embodiment.

FIG. 8 is an explanatory diagram showing another example of an exposure pattern (lithography pattern) that can be formed in the first embodiment.

FIG. 9 is an explanatory diagram showing another example of an exposure pattern (lithography pattern) that can be formed in the first embodiment.

FIG. 10 is an explanatory diagram showing a gate pattern.

FIG. 11 is an explanatory diagram showing an actual form.

FIG. 12 is a diagram illustrating a gate pattern.

FIG. 13 is a diagram showing a pattern forming process.

FIG. 14 is a schematic diagram showing an example of a two-beam interference exposure apparatus for performing periodic pattern exposure.

FIG. 15 is a schematic diagram showing an example of a projection exposure apparatus that performs periodic pattern exposure by two-beam interference.

16 is an explanatory diagram showing an example of a mask and an illumination method used in the apparatus of FIG.

FIG. 17 is an explanatory diagram showing another example of a mask used in the apparatus of FIG. 16 and an illumination method.

FIG. 18 is a schematic view showing a conventional projection exposure apparatus.

FIG. 19 is a schematic diagram showing an example of a two-beam interference exposure apparatus.

FIG. 20 is a schematic view showing an example of a high resolution exposure apparatus.

FIG. 21 is a schematic view showing another example of a high resolution exposure apparatus.

FIG. 22 is a flowchart showing the first embodiment of the present invention.

FIG. 23 is a flow chart diagram showing a second embodiment of the present invention.

FIG. 24 is a schematic view showing an example of an exposure apparatus of the present invention.

FIG. 25 is a schematic view showing another example of the exposure apparatus of the present invention.

FIG. 26 is a flow chart diagram showing a third embodiment of the present invention.

FIG. 27 is a flow chart diagram showing a fourth embodiment of the present invention.

28 is a detailed view of a flowchart of a portion of FIG. 27. FIG.

FIG. 29 is an explanatory diagram of another embodiment of the exposure apparatus of the present invention.

[Explanation of symbols]

221 excimer laser 222 Illumination optical system 223 Mask (reticle) 224 Mask (reticle) stage 225 Two-beam interference mask and mask for normal projection exposure 226 Mask (Reticle) Changer 227 Projection optical system 228 wafers 229 XYZ stage

Claims (30)

(57) [Claims] 1. An exposure method for exposing a plurality of shot areas of a plurality of wafers to each other by exposing a plurality of images having different intensity distributions to each other without developing the shot areas of the wafer on the way. When the plurality of shot areas of each of the plurality of wafers are exposed with the image having another intensity distribution after the exposure with the image having the certain intensity distribution, the plurality of wafers are
A measurement system for wafer position confirmation that measures the position of the wafer is provided.
The wafer is stored in a stock carrier, and the alignment of the wafer during the first exposure is performed using the alignment mark on the wafer. The alignment during the second exposure is performed using the alignment information on the wafer chuck. exposure method characterized in that conducted are <br/> with. 2. The exposure method according to claim 1 , wherein one of the image having the certain intensity distribution and the image having the other intensity distribution is a finer image than the other. 3. The other is a partially or wholly blurred image, or a non-blurred image having a multivalued light intensity distribution (giving a multivalued exposure dose distribution to a resist on a wafer). The exposure method according to claim 2, which is characterized in that. 4. A minimum line width of the fine image is 0.15μm
The exposure method according to claim 2 , wherein the exposure method is smaller. 5. The exposure method according to claim 2, 3 or 4, wherein the fine image is an image of the fringe pattern. Characterized in that to obtain the striped image by imaging the pattern of coherent illumination or partially coherent illumination the performed the Levenson type phase shift mask with respect to 6. alternating phase shift mask
The exposure method according to claim 5 . 7. A pattern of the mask is imaged by performing partial coherent illumination with a larger σ (sigma) than partial coherent illumination performed on the Levenson-type phase shift mask for a certain mask. The exposure method according to claim 5 , wherein the other image is obtained. Claims, characterized in that to form the stripe-shaped image by 8. causing interference of parallel light collimated divergent light therefrom parallel light or from a laser is divided into two light beam splitter Item 6. The exposure method according to Item 5 . 9. An exposure apparatus having an exposure mode for exposing a plurality of image intensity distribution different from one another without performing development on the way to the wafer in the shot area, double
After performing the exposure by the image having an intensity distribution with respect to a plurality of shot regions of each number of the wafer, the double
When exposing the plurality of shot areas of each of the plurality of wafers with an image having another intensity distribution, the plurality of wafers are stored with their positions guaranteed.
The wafer has a stock carrier for performing the alignment of the wafer at the time of the first exposure by the alignment mark on the wafer and the alignment at the time of the second exposure by using the alignment information on the wafer chuck. An exposure apparatus characterized in that it is performed. 10. An apparatus according to claim 9, characterized in that one of the images with the other intensity distribution as an image having a certain intensity distribution is finer image than the other. 11. The other part is a partially or totally blurred image or a non-blurred image having a multivalued light intensity distribution (giving a multivalued exposure dose distribution to a wafer resist). The exposure apparatus according to claim 10, which is characterized in that. 12. The minimum line width of the fine image is 0.15μ
The exposure apparatus according to claim 10 , wherein the exposure apparatus is smaller than m. 13. The exposure apparatus according to claim 10, 11 or 12 , wherein the fine image is the striped image. 14. A pattern of the mask is imaged by performing partial coherent illumination having a larger σ (sigma) than the partial coherent illumination performed on the Levenson-type phase shift mask for a certain mask. claim 13, characterized in that to obtain the other image
The exposure apparatus according to. 15. claims, characterized in that to form the stripe-shaped image by interfering collimated light collimating diverging light therefrom parallel light or from a laser is divided into two light beam splitter Item 13. The exposure apparatus according to item 13 . 16. Claim 13, characterized in that to form the image with the other intensity distribution as an image having an intensity distribution in the by sequentially illuminated by two lighting method a mask different Exposure equipment. 17. The exposure apparatus according to claim 14 , further comprising an illumination optical system capable of changing the numerical aperture on the mask side. 18. The exposure apparatus according to claim 17 , further comprising means for selectively disposing one of the certain mask and the Levenson-type phase shift mask on a mask stage. 19. The exposure apparatus according to claim 17 , further comprising a mask stage on which both the certain mask and the Levenson-type phase shift mask are arranged. 20. The pattern of the pattern of the certain mask the Levenson type phase shift mask 請 characterized by having a common projection exposure system for projecting onto the wafer
The exposure apparatus according to claim 14 . 21. of claim 14, characterized in that a second projection exposure system for projecting a pattern of the first projection exposure system for projecting a pattern of the certain mask the Len Benson type phase shift mask Exposure equipment. 22. claims, characterized in that a wafer stage of a common movable to said first and second projection exposure system
21. The exposure apparatus according to 21 . 23. A claims, characterized in that to perform the exposure in a step-and-repeat method in the exposure mode
9. The exposure apparatus according to item 9 . 24. A claims, characterized in that to perform the exposure in a step-and-scan manner in the exposure mode
9. The exposure apparatus according to item 9 . 25. The exposure apparatus according to claim 9, wherein the wafer alone is stored in the stock carrier. 26. The exposure apparatus according to claim 9 , wherein the wafer chuck is stored in the stock carrier together with the wafer chuck. 27. The exposure apparatus according to claim 9 , further comprising a coater developer including the stock carrier. 28. An apparatus according to claim 9, characterized in that formed using the reduced projection optical system and the laser light from the respective images KrF, ArF or F2 excimer laser. 29. The reduction projection optical system is a refraction system, a reflection system.
29. The exposure apparatus according to claim 28 , which is an optical system including a refraction system or a reflection system. 30. A device manufacturing method comprising the steps of exposing a wafer and developing the wafer by using the exposure apparatus according to any one of claims 9 to 29 .