JP3262074B2 - 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 exposing method and an exposing apparatus, and more particularly, to exposing a photosensitive substrate with a fine circuit pattern, for example, a semiconductor chip such as an IC or LSI, a display element such as a liquid crystal panel, a magnetic head, and the like. It is suitable for use in the manufacture of various devices such as a detection device and an imaging device such as a CCD.

[0002]

2. Description of the Related Art Conventionally, when devices such as ICs, LSIs, and liquid crystal panels are manufactured using photolithography technology, circuits formed on the surface of a photomask or reticle (hereinafter, referred to as "mask"). A projection exposure method and projection in which a pattern is projected onto a photosensitive substrate such as a silicon wafer or a glass plate (hereinafter, referred to as a “wafer”) coated with a photoresist or the like by a projection optical system, and transferred (exposed) there. An exposure apparatus is used.

In recent years, in response to the higher integration of the above devices, there has been a demand for miniaturization of a pattern to be transferred to a wafer, that is, higher resolution and larger area of one chip on the wafer. Therefore, even in the above-described projection exposure method and projection exposure apparatus that form the center of microfabrication technology for wafers,
In order to form an image (circuit pattern image) having a dimension (line width) of 0.5 / μm or less over a wide range, improvement in resolution and enlargement of an exposure area have been attempted.

FIG. 22 shows a schematic view of a conventional projection exposure apparatus. In FIG. 22 , reference numeral 191 denotes an excimer laser as a light source for exposure to far ultraviolet rays, 192 denotes an illumination optical system, 193 denotes illumination light emitted from the illumination optical system 192, 194 denotes a mask,
Reference numeral 95 denotes an optical system (projection optical system) 19 which exits from the mask 194.
Reference numeral 196 denotes an object-side exposure light, reference numeral 196 denotes a reduction type projection optical system, reference numeral 197 denotes an image-side exposure light which exits from the projection optical system 196 and enters a substrate 198, reference numeral 198 denotes a wafer which is a photosensitive substrate,
Reference numeral 99 denotes a substrate stage for holding a photosensitive substrate.

[0005] The laser light emitted from the excimer laser 191 is guided to the illumination optical system 192 by the routing optical systems (190a, 190b), and the illumination optical system 192 provides a predetermined light intensity distribution, light distribution, and opening angle (Sekiguchi). The mask 19 is adjusted so as to have the illumination light 193 having several NA) or the like.
Light 4 On the mask 194, a pattern having a size obtained by reciprocally multiplying (for example, 2 times, 4 times, or 5 times) the fine pattern formed on the wafer 198 by a projection magnification of the projection optical system 196 is formed on a quartz substrate by chrome or the like. And illumination light 1
93 is transmitted and diffracted by the fine pattern of the mask 194, and becomes the object side exposure light 195.

[0006] The projection optical system 196 includes an object side exposure light 195.
Is converted into image-side exposure light 197 that forms a fine pattern on the mask 194 on the wafer 198 at the above-mentioned projection magnification and with a sufficiently small aberration. As shown in the enlarged view at the bottom of FIG. 22 , the image-side exposure light 197 has a predetermined numerical aperture NA (= Sin
(Θ)) converges on the wafer 198 to form an image of a fine pattern on the wafer 198. The substrate stage 199 includes a plurality of different areas (shot areas: 1) on the wafer 198.
In the case where a fine pattern is sequentially formed on an area which becomes one or a plurality of chips, the projection optical system 196 of the wafer 198 is moved stepwise along the image plane of the projection optical system.
Has changed its position with respect to

Although the above-described projection exposure apparatus using an excimer laser as a light source has a high projection resolution, it is technically difficult to form a pattern image of, for example, 0.15 μm or less.

[0008] The projection optical system 196 has a resolution limit due to a trade-off between the optical resolution due to (exposure) wavelength and the depth of focus. The resolution R of the resolution pattern and the depth of focus DOF by the projection exposure apparatus are expressed by the following Rayleigh formulas (1) and (2).

R = k1 (λ / NA) ‥‥‥ (1) DOF = k2 (λ / NA2) ‥‥‥ (2) where:
λ is the exposure wavelength, NA is the image-side numerical aperture representing the brightness of the projection optical system 196, and k1 and k2 are constants determined by the development process characteristics of the wafer 198, and are usually 0.5 to
It is a value of about 0.7. From equations (1) and (2),
One of the ways to increase the resolution to reduce the resolution R is to increase the numerical aperture NA. However, in actual exposure, the depth of focus DOF of the projection optical system 196 needs to be set to a certain value or more, so that it is difficult to increase the NA to a certain value or more. It is understood that "short wavelength" for reducing the wavelength λ is required.

However, as the exposure wavelength is shortened, a serious problem arises. It is the projection optical system 196
Is that the glass material of the lens that constitutes is lost. The transmittance of most glass materials is close to 0 in the deep ultraviolet region,
Using a special manufacturing method for exposure equipment (exposure wavelength about 248
nm), fused quartz exists as a glass material.
The transmittance of this fused quartz also sharply decreases with respect to the exposure wavelength of 193 nm or less, and practical glass material development is extremely difficult in the region of 150 nm or less corresponding to fine patterns with a line width of 0.15 μm or less. Difficult. In addition, the glass material used in the deep ultraviolet region must satisfy various conditions such as durability, uniformity of refractive index, optical distortion, workability, etc. in addition to transmittance. Existence is at stake.

As described above, in the conventional projection exposure method and projection exposure apparatus, it is necessary to shorten the exposure wavelength to about 150 nm or less in order to form a pattern having a line width of 0.15 μm or less on a wafer. On the other hand, at present, there is no practical glass material in this wavelength region, so that a pattern having a line width of 0.15 μm or less cannot be formed on the wafer.

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 having a line width of 0.15 μm or less is formed on a wafer. be able to.

[0013] The principle of two-beam interference exposure is described with reference to FIG. 18. In the two-beam interference exposure, a laser beam L151 having coherence from a laser 151 and being a parallel beam is converted into laser beams L151a and L151 by a half mirror 152.
The two laser light beams (coherent parallel light beams) are divided from larger than 0 to 9 by being split into two light beams of ab and reflecting the split two light beams by the plane mirrors 153a and 153b, respectively.
An interference fringe is formed at the intersection by intersecting at an angle of less than 0 degree on the surface of the wafer 154. By exposing and exposing the wafer 154 with (the light intensity distribution of) the interference fringes, a fine periodic pattern corresponding to the light intensity distribution of the interference fringes is formed on the wafer 154.

The two light beams L151a and L151b are
In the case where the wafer intersects with the perpendiculars formed on the 54 surfaces in a state inclined at the same angle in the opposite directions to each other on the wafer surface, the resolution R in the two-beam interference exposure is expressed by the following equation (3).

R = λ / (4 sin θ) = λ / 4NA = 0.25 (λ / NA) (3) where R is the width of each L & S (line and space), ie, interference fringes. The width of each of the light and dark portions is shown. Β represents the incident angle (absolute value) of the two light beams with respect to each image plane, and NA = Sin θ.

Comparing equation (1), which is the equation for resolution in normal projection exposure, and equation (3), which is the equation for resolution in two-beam interference exposure, the resolution R of two-beam interference exposure is expressed by equation (1). Since this corresponds to the case where k ₁ = 0.25, it is possible to obtain a resolution twice or more as high as that of a normal projection exposure in which k ₁ = 0.5 to 0.7 in two-beam interference exposure. .

Although not disclosed in the above US patent, for example, when λ = 0.248 nm (KrF excimer) and NA =
At 0.6, R = 0.10 μm is obtained.

[0018]

In the two-beam interference exposure, basically, only a simple fringe pattern corresponding to the light intensity of the interference fringes (exposure amount distribution) can be obtained. Difficult to form.

The above-mentioned US Pat. No. 5,415,835 discloses that a simple fringe pattern (periodic pattern), that is, a binary exposure amount distribution is given to a wafer (resist) by two-beam interference exposure, and then the resolution of the exposure apparatus is increased. Obtaining an isolated line (pattern) by performing normal lithography (exposure) using a mask in which an opening having a size within the range is formed and giving another binary exposure distribution to the wafer Has been proposed.

However, the above-mentioned US Pat.
In the multiple exposure method disclosed in Japanese Patent Publication No. 35, after a wafer is placed in an exposure apparatus for two-beam interference exposure and exposed, the wafer is placed back in another exposure apparatus for normal exposure and exposure is performed.
There was a problem that it took time.

An object of the present invention is to provide an exposure method and an exposure apparatus capable of performing multiple exposures in a relatively short time.

According to the present invention, a circuit pattern having a complicated shape is formed on a wafer by using two exposure methods: periodic pattern exposure represented by two-beam interference exposure and normal pattern exposure (normal exposure) not including a periodic pattern. An object is to provide an exposure method and an exposure apparatus which can be formed.

Another object of the present invention is to provide a line width of 0.15 μm.
An exposure method and an exposure apparatus capable of easily obtaining a circuit pattern including the following parts are provided.

Another object of the present invention is to provide an exposure apparatus capable of performing two exposure methods, periodic pattern exposure and normal exposure.

[0025]

According to the present invention, there is provided an exposure apparatus comprising: (1-1) an illumination optical system for illuminating a plurality of different mask patterns with light from a light source; and light from the mask pattern to a region to be exposed. An exposure apparatus having a projection optical system for projecting, wherein the exposure apparatus has an exposure mode for performing multiple exposure, holds the plurality of mask patterns on a common mask stage, and sets the plurality of mask patterns different from each other. It is characterized by simultaneous lighting under lighting conditions.

Here, the different illumination conditions may include a partial coherent illumination and a coherent illumination, and the plurality of mask patterns include a normal pattern and a periodic pattern, and the partial coherent illumination includes A normal pattern may be illuminated, and the periodic pattern may be illuminated by the coherent illumination.

Further, the different illumination conditions may have different σ (sigma), different NA (numerical aperture), and different incident angles of the illumination light. You may do it.

Further, the illumination optical system has an optical integrator in which the exit angles of the light beams from the plurality of fly-eye lenses in the central region and the exit angles of the light beams from the plurality of fly-eye lenses in the peripheral region are different from each other. And illuminating a first mask pattern of the plurality of mask patterns with light beams from the plurality of fly-eye lenses in the central region, and the plurality of mask patterns using light beams from a plurality of fly-eye lenses in the peripheral region. The second of
The illumination of the mask pattern may be performed simultaneously.

Here, the first mask pattern may be a periodic pattern, and the second mask pattern may be a normal pattern.

The different mask patterns may be formed on separate substrates.

The different mask patterns may be formed on a common substrate.

Preferably, the substrate is transparent.

One of the different mask patterns is a line-and-space pattern, and the line-and-space pattern is a Levenson type phase shift mask or a shifter edge type phase shift mask without a light shielding portion. preferable.

Preferably, the plurality of mask patterns are illuminated with light from a KrF excimer laser, an ArF excimer laser or an F2 excimer laser.

Preferably, the mask pattern is projected by a projection optical system comprising a reflection system.

According to the exposure method of the present invention, in the exposure method for exposing a substrate to be exposed with a line and space pattern of a mask, the line and space pattern is formed in a rectangular area long in a repetition direction of the line and space. Scanning the substrate to be exposed in a direction orthogonal to the repetition direction while the mask is fixed.

Here, the line and space pattern is preferably a Levenson type phase shift mask or a shifter edge type phase shift mask having no light shielding portion.

Here, KrF excimer laser, ArF
The pattern is preferably illuminated with light from an excimer laser or an F2 excimer laser, and the pattern is preferably projected by a projection optical system comprising a reflection system.

Here, the exposure apparatus may be a step-and-repeat reduction projection type exposure apparatus. Further, the exposure apparatus may be a step-and-scan reduction projection type exposure apparatus.

A method of manufacturing a device according to the present invention is characterized in that the method includes a step of exposing a wafer to a device pattern using the exposure apparatus, and a step of developing the exposed wafer.

[0041]

[0042]

[0043]

[0044]

[0045]

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

[0047]

FIG. 1 is a schematic view of an exposure apparatus according to an embodiment of the present invention. In FIG. 1, reference numeral RS denotes a reticle stage (mask stage) in which an arbitrary pattern reticle (reticle R) having an ordinary pattern of an arbitrary shape and an L & S pattern plate (plate) M having a periodic pattern are arranged. . Reference numeral PL denotes a projection optical system, which collectively or scan-exposes the normal pattern of the reticle R, and projects and scans the periodic pattern of the plate M onto the wafer W.

FIG. 2 is a schematic diagram when reticle stage RS of FIG. 1 is viewed from above. The plate M has a periodic pattern MP having a minimum line width and a plate alignment mark M
a and Mb. Note that the pattern MP is
When performing projection exposure on the wafer, the wafer stage WS is pointed by the arrow Xa.
Moving in the direction. The reticle R has various shapes of circuit patterns (normal patterns) and reticle alignment marks Ra and Rb.

In this embodiment, the plate M having the periodic pattern MP is provided on the side of the reticle R such that the periodic pattern is projected onto the wafer by scanning and exposing. Further, the size of the plate M is reduced to facilitate manufacture of the plate M.

As shown in FIG. 1, in this embodiment, when a periodic pattern is projected and exposed on a wafer (photosensitive substrate), the plate M having the periodic pattern is positioned on the optical axis of the projection optical system PL. ing.

Then, the periodic pattern of the plate M placed on the reticle stage RS is projected onto the wafer W. At this time, the reticle stage RS is fixed, and the wafer stage WS is scanned in a direction (arrow Xa direction) orthogonal to the pattern arrangement direction of the periodic pattern MP to project and scan the periodic pattern within one shot on the wafer W. Exposure.

When the scanning exposure of the periodic pattern is completed at this time, the reticle stage RS is driven to project and expose the normal pattern of the reticle R onto the wafer W at a time, or to scan both at regular intervals. Projection scanning exposure,
Thus, multiple exposure is performed.

In this embodiment, when projecting the periodic pattern on the plate M, the wafer stage WS is fixed, the reticle stage RS is moved in the direction of the arrow Xa, and the periodic pattern is scanned and exposed on the wafer W. Is also good.

FIG. 3 is an explanatory view of a periodic pattern for multiple exposure and a normal pattern according to the present invention. FIG. 3 shows a normal pattern (pattern area) SP, a periodic pattern MP having a minimum line width of line and space (L & S), and reticle alignment marks Ra and Rb in each area on the substrate.
Is provided.

As shown in the figure, the periodic pattern MP has a smaller dimension in one direction than a dimension projected in one shot on the wafer surface.

As described above, two exposures for multiple exposure are formed on one substrate.
One mask pattern is formed and an alignment mark is also formed to improve the alignment accuracy, while simplifying the entire apparatus.

FIGS. 4 to 12 are explanatory diagrams of the exposure method according to the first embodiment of the present invention. FIG. 4 is a flowchart showing the exposure method of the present invention. FIG. 4 shows each block of the periodic pattern exposure step, the projection exposure step (normal pattern exposure step), and the development step, which constitute the exposure method of the present invention, and their flow. In the figure, the order of the periodic pattern exposure step and the projection exposure step may be reversed, and when one of the steps includes a plurality of exposure steps, each step may be performed alternately. Also, between each exposure step. Although there is a step of performing precise alignment, the illustration is omitted here.

The exposure method and the exposure apparatus according to the present invention are characterized in that double exposure (multiple exposure) of a periodic pattern exposure by scanning and a normal exposure is performed on a substrate to be exposed (photosensitive substrate).

Here, the normal pattern exposure is an exposure in which the resolution is lower than that of the periodic pattern exposure, but the exposure can be performed in an arbitrary pattern, and includes a projection exposure for projecting a mask pattern by the projection optical system shown in FIG.

The pattern (normal pattern) exposed by the normal pattern exposure includes a fine pattern having a resolution lower than the resolution, and the periodic pattern exposure forms a periodic pattern having substantially the same line width as the fine pattern. A large pattern having a resolution equal to or larger than the resolution of the normal pattern exposure is not limited to the line width of the periodic pattern exposure, but an integer multiple is effective.

Normally, the pattern exposure has an arbitrary shape and may be oriented in various directions. Generally, an IC pattern has two directions, one direction and the direction perpendicular to the other.
In many cases, it is oriented in a direction, and the finest pattern is often limited to only one specific direction.

When performing periodic pattern exposure by double exposure, it is important that the direction of the periodic pattern matches the direction of the finest pattern of the normal pattern.

Further, the exposure is performed so that the center of the peak of the periodic pattern coincides with the center of a fine pattern having a resolution lower than that of the normal pattern.

The double exposure in the present invention means a double exposure of a periodic pattern exposure and a normal pattern exposure. The periodic pattern exposure is repeated several times in parallel with the direction of the finest pattern of the normal pattern exposure. Scanning exposure.

Each of the periodic pattern exposure and the normal pattern exposure of the exposure method and the exposure apparatus of the present invention comprises one or a plurality of exposure steps. Different exposure dose distributions are given to the photosensitive substrate.

When exposure is performed according to the flow of FIG.
First, the wafer (photosensitive substrate) is scanned and exposed in a periodic pattern as shown in FIG. The numbers in FIG. 5 represent the exposure amounts, and the hatched portions in FIG.
(Actually arbitrary) and the exposure amount is 0 in the white portion.

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 set between the exposure amounts 0 and 1 as shown in the lower graph of FIG. The upper part of FIG. 5B shows a lithography pattern (concavo-convex pattern) finally obtained.

FIG. 6 shows the relationship between the exposure value and the exposure threshold of the film thickness after development of the resist on the photosensitive substrate in this case. The resist is referred to as a positive resist (hereinafter referred to as "positive") and a negative resist. Each of the resists (hereinafter referred to as “negative type”) is shown. In the case of the positive type, when the exposure threshold value Eth or more, and in the case of the negative type, the exposure threshold value Eth or less,
The film thickness after development becomes zero.

FIG. 7 is a schematic diagram showing a state in which a lithography pattern is formed through the development and etching processes in the case of performing such exposure, for a negative type and a positive type.

In the present embodiment, different from the normal exposure sensitivity setting, FIG. 8 (same as FIG. 5A) and FIG.
As shown in the figure, when the central exposure amount in the periodic pattern exposure is 1, the exposure threshold value Eth of the resist on the exposed substrate is 1
It is set larger than. When the exposure pattern (exposure amount distribution) obtained by performing only the base pattern exposure shown in FIG. 5 is developed, the exposure amount of the photosensitive substrate becomes insufficient. Does not occur, and no lithography pattern is 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 using a negative type, but the present invention can also be applied to a positive type). .

In FIG. 9, the upper part shows a lithography pattern (nothing can be done), and the lower part shows the relationship between the exposure amount distribution and the exposure threshold. Incidentally, E ₁ according to bottom the exposure amount in the periodic pattern exposure, E ₂ represents an exposure amount in the conventional projection exposure.

The feature of the present embodiment is that a high-resolution exposure pattern, which is apparently lost only by periodic pattern exposure, is fused with an exposure pattern of an arbitrary shape including a pattern having a size equal to or smaller than the resolution of an exposure apparatus by ordinary projection exposure. And selectively exposing only the desired area to the exposure threshold or more of the resist,
Finally, a desired lithography pattern can be formed.

FIG. 10A shows an exposure pattern obtained by normal projection exposure (normal pattern exposure). Since the pattern is a fine pattern, it cannot be resolved and the intensity distribution on the object to be exposed is blurred and spread. . In the present embodiment, a fine pattern having a paper width of about half the resolution of normal projection exposure is used.

Assume that the projection exposure for forming the exposure pattern of FIG. 10A is performed on the same region of the same resist without the development step after the periodic pattern exposure of FIG.
FIG. 10B shows the total exposure distribution on the resist surface.
It looks like the graph below. Here, the ratio of the exposure amount E ₂ of the exposure amount E ₁ and the projection exposure of the periodic pattern exposure is 1:
1. The exposure threshold value Eth of the resist is equal to the exposure amount E ₁ (=
1) The sum of the exposure amount E ₁ and the exposure amount E ₂ of the projection exposure (= 2)
Therefore, the lithography pattern shown in the upper part of FIG. 10B is formed.

At this time, the center of the normal pattern is matched with the peak of the periodic pattern. Also, the direction of the normal pattern and the direction of the periodic pattern are matched.

The isolated line pattern shown in the upper part of FIG. 10 (B) has a resolution of periodic pattern exposure and has no simple periodic pattern. Therefore, a high-resolution pattern higher than the resolution that can be realized by ordinary projection exposure is obtained.

Here, suppose that the projection exposure for forming the exposure pattern shown in FIG. 11 (projection exposure with a line width twice as large as the exposure pattern shown in FIG. 8 and an exposure threshold or more (here, an exposure amount twice as large as the threshold)) 8) is superimposed on the same region of the same resist without the development step after the periodic pattern exposure of FIG. At this time, by making the center of the normal pattern coincide with the peak position of the periodic pattern exposure, the symmetry of the superposed pattern is good, and a good pattern image can be obtained.

The total exposure distribution of this resist is shown in FIG.
(B), the exposure pattern of the two-beam interference scanning exposure (periodic pattern exposure) disappears, and only a lithography pattern by projection exposure is finally formed.

Also, as shown in FIG. 12, the principle is the same when the exposure is performed with a line width three times the exposure pattern of FIG.
In an exposure pattern with a line width of twice or more, basically, a line width of a finally obtained lithography pattern is obvious from a combination of an exposure pattern with a double line width and an exposure pattern with a triple line width, All lithography patterns that can be realized by projection exposure can be formed in this embodiment as well.

By adjusting the exposure amount distribution (absolute value and distribution) and the threshold value of the resist on the photosensitive substrate by each of the periodic pattern exposure and the projection exposure briefly described above,
9, 10 (B), 11 (B), and 12 (B)
And the minimum line width is the resolution of the periodic pattern exposure (FIG. 10B).
Can be formed.

The principles of the above-described exposure methods can be summarized as follows: (A-1) A pattern area not subjected to projection exposure (normal pattern exposure), that is, a periodic exposure pattern equal to or less than the exposure threshold of a resist disappears by development.

(A-2) Regarding the pattern area of the projection exposure performed with the exposure amount equal to or less than the exposure threshold value of the resist, the exposure pattern having the resolution of the periodic pattern exposure determined by the combination of the projection exposure and the periodic pattern exposure is used. It is formed.

(A-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 (corresponding to a mask) which is not resolved only by the projection exposure is similarly 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 two-beam interference scanning exposure, a much larger depth of focus can be obtained as compared with the normal exposure.

In the above description, the order of the periodic pattern exposure and the projection exposure is the order of the periodic pattern exposure, but is not limited to this order.

Next, a second embodiment of the present invention will be described. This embodiment is directed to a so-called gate type pattern shown in FIG. 13 as a circuit pattern (lithography pattern) obtained by exposure.

The gate pattern in FIG. 13 has a minimum line width of 0.1 μm in the horizontal direction, that is, the direction of AA ′ in the figure, whereas it has a minimum line width of 0.2 μm or more in the vertical direction. According to the present invention, it is possible to obtain a high resolution only in such a one-dimensional direction.
For a dimensional pattern, two-beam interference scanning exposure (periodic pattern exposure) may be performed only in the one-dimensional direction that requires such high resolution.

Next, an example of a combination of two-beam interference scanning exposure in one-dimensional direction and ordinary projection exposure will be described with reference to FIG.

FIG. 14A shows a periodic exposure pattern by two-beam interference scanning exposure only in 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. 14 represent exposure amounts.

As an exposure apparatus for realizing such two-beam interference scanning exposure, an apparatus in which a mask and an illumination method are configured as shown in FIG. 20 or FIG. 21 in a projection exposure apparatus as shown in FIG. 1 or FIG. is there.

The exposure apparatus shown in FIG. 19 is, for example, a projection exposure apparatus using a normal step-and-repeat type or step-and-scan type reduction projection optical system (comprising a large number of lenses), and currently has an exposure wavelength of 248 nm. On the other hand, there are those having NA of 0.6 or more.

In FIG. 19, reference numeral 161 denotes a mask; 162, an object-side exposure light exiting from the mask 161 and entering the optical system 163; 163, a projection optical system; 164, an aperture stop; 165, a wafer exiting from the projection optical system 163; Image-side exposure light 166 incident on the wafer 166 indicates a wafer serving as a photosensitive substrate.
FIG. 9 is an explanatory diagram showing the position of a light beam on the pupil plane corresponding to the circular opening of the stop 164 by a pair of black dots. FIG. 19 is a schematic view showing a state in which two-beam interference scanning exposure is performed. Both the object-side exposure light 162 and the image-side exposure light 165 are different from the normal projection exposure in FIG. It consists only of bunch.

Then, the mask 161 and the wafer 166 are relatively scanned. At the time of scanning exposure of a periodic pattern, the mask 161 uses the plate M shown in FIG.

In order to perform two-beam interference scanning exposure (periodic pattern exposure) in a normal projection exposure apparatus as shown in FIG. 19, the mask 161 and its illumination method are shown in FIG.
It should just be set like 1. Hereinafter, these three examples will be described.

FIG. 20A shows a Levenson-type phase shift mask 173, in which the light shielding portion 17 made of chrome is used.
The pitch PO of 1 is a mask represented by the formula (4), and the pitch POS of the phase shifter 172 is represented by the formula (5).

P ₀ = MP = 2MR = Mλ / (2NA) ‥‥‥ (4) P _OS = 2P ₀ = Mλ / (NA) ‥‥‥ (5) where M is the projection magnification of the projection optical system 163. , Λ indicates the exposure wavelength, and NA indicates the numerical aperture of the projection optical system 163 on the image side. P
Is L & S (line and space) on the wafer surface
Is the width of each of the L & S on the wafer surface (interference
(The width of each of the bright and dark portions of the stripe). Where P = 2R
is there.

On the other hand, the mask 174 shown in FIG. 20B is a shifter edge type phase shift mask made of chrome without a light-shielding portion, and is the same as the Levenson type.
The pitch POS of No. 5 is configured to satisfy the above equation (5).

To perform two-beam interference scanning exposure using the phase shift masks of FIGS. 20A and 20B, these masks are subjected to so-called coherent illumination with σ = 0 (or a value close to 0). . Specifically, as shown in FIG.
The mask 170 is irradiated with a parallel light beam from a direction perpendicular to 70 (a direction parallel to the optical axis).

Here, σ = numerical aperture of the illumination optical system / numerical aperture of the projection optical system. When such illumination is performed, with respect to the zero-order transmitted diffracted light emitted from the mask 170 in the above-described vertical direction, the phase difference between adjacent transmitted lights becomes π by the phase shifter 172 (175), and the lights do not cancel each other.
The two parallel ray bundles of ± 1st-order transmitted diffracted light are generated from the mask 170 symmetrically with respect to the optical axis of the projection optical system 163.
The two object-side exposures 165 interfere on the wafer 166. Further, second-order or higher-order diffracted light does not enter the aperture of the aperture stop 164 of the projection optical system 163 and does not contribute to image formation.

The mask 180 shown in FIG. 21 is a mask in which the pitch PO of the light shielding portion 181 made of chromium is expressed by the equation (6) similar to the equation (4).

P ₀ = MP = 2MR = Mλ / (2NA) ‥‥‥ (6) where M is the projection magnification of the projection optical system 163, λ is the exposure wavelength, and NA is the aperture on the image side of the projection optical system 163. Indicates a number.

The mask without the phase shifter shown in FIG. 21 is subjected to oblique illumination using one or two parallel light beams. In this case, the incident angle θ of the parallel light beam to the mask 180
₀ is set to satisfy Expression (7). When two parallel light fluxes are used, the mask is illuminated with parallel light fluxes inclined by θ _{0 in} opposite directions with respect to the optical axis.

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 obliquely illuminating a mask having no phase shifter shown in FIG. 21 with a parallel light beam satisfying the above equation (7), the mask 180 outputs an angle θ with respect to the optical axis.
_0- order transmitted diffracted light that travels straight at 0, and travels along an optical path symmetrical with respect to the optical path of the 0-order transmitted diffracted light and the optical axis of the projection optical system (travels at an angle -θ ₀ with respect to the optical axis) —first-order transmission Two light beams of the diffracted light are generated as two object-side exposure light beams 162 in FIG. 16, and these two light beams enter the opening of the aperture stop 164 of the projection optical system 163 to form an image.

In the present invention, such oblique incidence illumination using one or two parallel light beams is also treated as "coherent illumination".

The technique for performing two-beam interference scanning exposure using a normal projection exposure apparatus has been described above. The illumination optical system of the normal projection exposure apparatus as shown in FIG. 22 is configured to perform partial coherent illumination. Since the aperture stop (not shown) corresponding to 0 <σ <1 of the illumination optical system in FIG. 22 can be replaced with a special aperture stop corresponding to σ ≒ 0, the projection exposure apparatus is substantially used. Can be configured to perform coherent illumination.

Returning to the description of the second embodiment shown in FIGS. In the present embodiment, the projection is performed by normal projection exposure (normal pattern exposure) (for example, the apparatus shown in FIG. 21 in which partial coherent illumination is performed on a mask) after the two-beam interference scanning exposure (periodic pattern exposure) described above. 14
Exposure is performed on the gate pattern shown in FIG. FIG.
The upper part of (C) shows the relative positional relationship with the exposure pattern by the two-beam interference scanning exposure and the exposure amount in the area of the exposure pattern of the normal projection exposure, and the lower part of the figure shows the wafer by the normal projection exposure. The exposure amount of the resist is mapped in the vertical and horizontal directions with the resolution of the minimum line width pitch.

The exposure amount distribution shown in the lower part of FIG. 14 shows an intensity distribution for exposing the wafer with the light intensity incident from the mask as 1.

Although the exposure amount distribution due to the exposure of the periodic pattern in FIG. 14A should ideally be a rectangular wave of 1 and 0, the line width near the resolution limit of the two-beam interference scanning exposure is used. Therefore, it is a sine wave formed by only the zero-order light and the first-order light. Io the maximum value of the sin wave, a minimum value represented as I _1. At this time, the values of I ₀ and I ₁ are determined by σ of the illumination condition.

The distribution of the exposure amount by the normal projection exposure shown in FIG. 14B shows a typical value in each portion. The portion of the minimum line width of the exposure pattern by this projection exposure is blurred and widened without resolution, and the value of the light intensity at each store decreases. The exposure is
Generally, the center of the pattern is denoted by b, both sides are denoted by d, and the center of the blurred image from both sides is denoted by c. The line width twice as large as the minimum line width is larger than the values of b, c, and d. However, since the line width is near the resolution limit of the projection exposure, the value of a is slightly blurred. These values of a, b, c, d change depending on the lighting conditions.

The exposure amount distribution shown in FIG. 14C is obtained as a result of adding the exposure amounts of the exposure pattern shown in FIG. 14A and the exposure pattern shown in FIG. 14B.

The light amount ratio in each of the two-beam interference scanning exposure and the projection exposure differs depending on the illumination conditions of each exposure.
The light quantity ratio in each exposure in the addition is set as two-beam interference scanning exposure: projection exposure = 1: k as the illuminance ratio of the illumination system, and the value of k is obtained as follows.

The exposure distribution shown in FIG. 14C can be expressed by the following equation using the above-described exposure distribution and light amount ratio.

A ′ = k × a + I ₀ a ″ = k × a + I ₁ b ′ = k × b + I ₀ c ′ = k × c + I ₁ d ′ = k × d + I ₁ desired gate In order to obtain the pattern, a relational expression with the threshold value Ic of exposure of the resist is obtained, for example, when the resist is a negative type,

[0114] _{a '> I C a ">} I C b'> I C c '<I C d'<I C a ', a", b' is it is desirable difference is less, c 'and particularly b' It is desirable to have a difference with By solving these equations, the optimum light amount ratio under each illumination condition can be obtained. Particularly, the following two equations related to the fine pattern are important. When the resist is negative type, k × b + I ₀ > I _C k × c + I ₁ <I _C resist is positive type, k × b + I ₁ <I _C k × c + I ₀ > I _C resist is positive type. Although the magnitude relationship of the amount distribution is inverted and the inequality sign is inverted with respect to the resist threshold value Ic, the optimum light amount ratio is similarly obtained.

The manner in which the fine circuit pattern shown in FIG. 15 is formed by combining two different illumination methods of the two-beam interference scanning exposure and the ordinary projection exposure described above will be described. In this embodiment, there is no development process between the two-beam interference scanning exposure and the normal projection exposure. Therefore, the exposure amount in the region where the exposure pattern of each exposure overlaps is added, and a new exposure pattern is generated by the added exposure amount (distribution).

FIGS. 15, 16 and 17 show K at a wavelength of 248 nm.
This is a specific example using an rF excimer stepper.

As shown in FIG. 15, a gate pattern having a minimum line width of 0.12 μm is usually exposed, and a periodic pattern is overlapped with a Levenson-type phase shift mask so as to overlap the minimum line width.

The NA of the projection lens was 0.6, and the σ of the illumination system was 0.3 for exposure using a Levenson mask. At the time of normal mask exposure, σ = 0.3, 0.6, 0.8 and annular illumination.

When exposing a periodic pattern by two-beam interference such as a phase shift mask, coherent illumination is σ
Is zero or a value close to it, but if it is too small, the amount of exposure per unit time will be small and the time required for exposure will be long, which is not practical.

In the case of periodic pattern exposure, σ is desirably 0.3 or less, and in exposure using a Levenson mask, σ, which is the maximum, is set to 0.3.

In normal exposure, partial coherent illumination is generally used. However, when σ is increased, reproducibility of a complicated shape is improved and depth is increased. In so-called annular illumination in which the illuminance distribution is lower on the inside than on the outside, this tendency is remarkable, but there is a disadvantage that the contrast is reduced.

As shown in FIG. 16A, the σ of the normal exposure
Is set to 0.3 which is the same as σ of the periodic pattern exposure, and the double exposure is performed under the same illumination condition, the gate pattern is defocused to 0.
Although the resolution is within the range of ± 0.2 μm, the line pattern is undulating, and the narrowed portion causes disconnection, which is not preferable.

In the case of normal pattern exposure, σ = 0.6
It is better to do above. As shown in FIG. 16B, when σ of the normal exposure is set to 0.6, the gate pattern can be resolved within the range of defocus 0 ± 0.4 μm, and the undulation of the line pattern is eliminated. Set the exposure amount ratio between normal exposure and periodic pattern exposure to normal exposure: periodic pattern exposure =
1.5: 1.

As shown in FIG. 17A, the σ of the normal exposure
When is increased to 0.8, the reproducibility of a complicated shape is slightly improved. The exposure amount ratio between normal exposure and periodic pattern exposure was set to normal pattern exposure: periodic pattern exposure = 2: 1. In the case of the normal pattern exposure, it is preferable to set the exposure amount to twice or more as compared with the periodic pattern exposure.

In FIG. 17 (B), the normal exposure is the annular illumination, and the illuminance from 0.6 inside the ring to 0.8 outside the ring is 1, and
This is a two-dimensional intensity distribution in the case where the illuminance is set to 0 or less on the inner side of the ring. The exposure amount ratio between normal exposure and periodic pattern exposure was set to normal exposure: periodic pattern exposure = 2.5: 1.

In the annular illumination, the reproducibility of a complicated shape is improved and the depth is increased as compared with when σ is 0.8. A good image was obtained with a defocus of ± 0.4 μm or less.

The fine circuit pattern is formed by double exposure with periodic pattern exposure. Normally, the fine pattern of the exposure pattern is not resolved because the light intensity is low and the contrast is low, but it is not resolved normally. Become imaged.

On the other hand, even a large pattern having a resolution equal to or higher than the resolution of the normal exposure pattern is superimposed on the intensity of the periodic pattern exposure and the contrast is enhanced. According to the exposure method of the present invention, a circuit pattern having a fine line width of 0.12 μm can be formed by using a projection exposure apparatus having an illumination optical system capable of switching illumination conditions such as changing σ or a light amount ratio of illuminance. And

The optimum value of the light amount ratio between the periodic pattern exposure and the normal pattern exposure was determined by the above-mentioned formula based on the combination of the illumination conditions.

Illumination condition 1 Periodic pattern exposure is σ = 0.
3. For normal pattern exposure, σ = 0.3 Exposure amount distribution by periodic pattern exposure shown in the lower part of FIG. 14A and exposure amount distribution by normal projection exposure shown in the lower part of FIG. ) Are shown below.

I ₀ = 0.80 I ₁ = 0.23 a = 1.31 b = 0.34 c = 0.61 d = 0.09 k = 1.0 Optimum, a '= 2.11 a "= 1.54 b' = 1.21 c '= 0.89 d' = 0.32. For the later comparison, the maximum value a 'is normalized by 1 as follows.

A '= 1.0 a "= 0.73 b' = 0.57 c '= 0.42
d '= 0.15 I ₀ = 0.38 Illumination condition 2 σ = 0.3 for periodic pattern exposure, σ = 0.6 I ₀ = 0.80 I ₁ = 0.23 a = 1.25 b = 0.44 c = 0.53 d = 0.13 k = 1.5 for normal pattern exposure Is optimal, and a '= 2.68 a "= 2.11 b' = 1.46 c '= 1.03 d' = 0.43. For later comparison, when the maximum value a 'is normalized by 1, the following is obtained. .

A '= 1.0 a "= 0.79 b' = 0.55 c '= 0.38
d '= 0.16 I ₀ = 0.30 Illumination condition 3 σ = 0.3 for periodic pattern exposure, σ = 0.8 for normal pattern exposure I ₀ = 0.80 I ₁ = 0.23 a = 1.20 b = 0.48 c = 0.47 d = 0.16 k = 2.0 is optimal, and a '= 3.20 a "= 2.63 b' = 1.76 c '= 1.17 d' = 0.55. Normalizing the maximum value a 'to 1 gives the following.

A '= 1.0 a "= 0.82 b' = 0.55 c '= 0.37
d '= 0.17 I ₀ = 0.25 Illumination condition 4 Periodic pattern exposure is σ = 0.3, normal pattern exposure is σ = 0.8, annular illumination, inner (inner zone) σ
Illuminance distribution of 0.6 or less was set to zero.

I ₀ = 0.80 I ₁ = 0.23 a = 1.10 b = 0.47 c = 0.36 d = 0.19 k = 2.5 It is optimal when a = 3.55 a ″ = 2.98 b ′ = 1.98 c ′ = 1.13 d ′ = 0.71 and the maximum value a ′ is normalized by 1 as follows.

A '= 1.0 a "= 0.84 b' = 0.56 c '= 0.32
d '= 0.20 I ₀ = 0.23 In the discussion so far, the resist threshold value was 1.5 when the maximum exposure amount was 3, so if normalized with the maximum exposure amount, the resist threshold value would be 0.5. Looking at this normalized exposure distribution, a ', a ", b' are normalized resist threshold values of 0.
It is larger than 5 and c ', d', I ₀ is smaller than the threshold.

Since a portion where the exposure amount is larger than the resist threshold value by the development is exposed, only the exposure amount a ′, a ″, and b ′ remains as a pattern after the development, so that FIG.
The part shown in gray below is the shape after development.

In general, when exposing a normal exposure pattern, an exposure amount that is about twice as large as that for exposing a periodic pattern is appropriate.
There is an optimum exposure amount ratio depending on a combination of illumination conditions when exposing the periodic pattern, and it can be obtained by the above-described formula.

As a result of calculation of various combinations of illumination conditions from the above-described formula, the following was shown. When σ = 0.3 at the time of periodic pattern exposure and the illumination condition σ of the normal pattern exposure is smaller than 0.8, the exposure amount at the time of exposing the normal pattern is set to be twice or less than the exposure amount at the time of exposing the periodic pattern. Good.

In the case of a periodic pattern, when σ = 0.3 and the illumination condition for exposing the normal pattern is annular illumination, when the width of the annular zone is small, the exposure amount for exposing the normal pattern is equal to the periodic pattern. It is preferable that the exposure amount is twice or more than the exposure amount at the time of exposure.

Illumination condition σ when exposing periodic pattern
Is smaller than 0.3, the exposure amount for exposing the normal pattern should be at least twice the exposure amount for exposing the periodic pattern.

FIG. 23 is a schematic view showing a high-resolution exposure apparatus capable of performing both two-beam interference exposure and normal projection exposure according to the present invention.

In FIG. 22, reference numeral 221 denotes KrF or Ar
F excimer laser; 222, an illumination optical system; 223, a mask (reticle); 224, a mask stage; To selectively supply the stage 224 with a normal reticle and one of the aforementioned Levenson phase shift mask (reticle), edge shifter type mask (reticle), or periodic pattern mask (reticle) having no phase shifter. It is provided.

The mask stage has a function of rotating the mask based on information previously drawn on a bar code or the like in order to make the direction of the fine pattern parallel to the direction of the periodic pattern. .

In FIG. 23, reference numeral 229 denotes one XYZ stage shared by the two-beam interference scanning exposure and the projection exposure. Thus, the position in the XY directions is accurately controlled using a laser interferometer or the like. When performing scanning exposure, the mask stage 224 and the stage 229 are relatively scanned and exposed as described above to form a periodic pattern.

The apparatus shown in FIG. 23 includes a reticle positioning optical system (not shown) and a wafer positioning optical system (off-axis positioning optical system, TTL positioning optical system, and TT
R positioning optical system).

The illumination optical system 222 of the exposure apparatus shown in FIG. 23 is configured so as to be able to switch between partially coherent illumination and coherent illumination. (1b)
Is supplied to one of the above-described Levenson-type phase shift reticles or edge shifter-type reticles or one of the periodic pattern reticles having no phase shifter. ) Is supplied to a desired reticle. Switching from partially coherent lighting to coherent lighting
The aperture stop usually placed immediately after the fly-eye lens of the optical system 222 may be replaced with a coherent illumination stop whose aperture diameter is sufficiently smaller than this stop.

The exposure method and exposure apparatus of the present invention
When the second exposure is a projection exposure, the exposure wavelength of the first exposure and the second exposure in the double exposure is both 400 nm or less, and preferably 250 nm or less. 250n
In order to obtain light having an exposure wavelength of less than m, a KJrF excimer laser (about 248 nm) or an ArF excimer laser (about 193 nm) is used.
nm).

In the present invention, the term “projection exposure” refers to an exposure in which three or more parallel light beams from an arbitrary pattern formed on a mask are incident on an image plane at various angles different from each other. Things.

The exposure apparatus of the present invention has a projection optical system for projecting a mask pattern onto a wafer, and a mask illumination optical system capable of performing both partial coherent illumination and coherent illumination. By performing normal exposure and performing two-beam interference scanning exposure by coherent illumination, it is characterized by periodic pattern exposure. “Partial coherent illumination” is illumination in which the value of σ = (numerical aperture of the illumination optical system / numerical aperture of the projection optical system) is greater than zero and less than 1, and “coherent illumination” is
The value of σ is zero or a value close to it, and is considerably smaller than σ of the partially coherent illumination.

In coherent illumination in periodic pattern exposure, σ is set to 0.3 or less. Partial coherent illumination during normal exposure makes σ 0.6 or more. σ = 0.8 is desirable. Furthermore, it is still more effective to use annular illumination in which the illuminance distribution is lower on the inside than on the outside.

The exposure wavelength of this exposure apparatus is 400 nm or less, preferably 250 nm or less. 250n
In order to obtain light having an exposure wavelength of less than m, a KrF excimer laser (about 248 nm) or an ArF excimer laser (about 193
m).

In the embodiments of the present invention, an optical system capable of switching between partially coherent illumination and coherent illumination is disclosed as a mask illumination optical system.

The exposure wavelength of this exposure apparatus is also 400 nm or less, preferably 250 nm or less. 250n
In order to obtain light having an exposure wavelength of less than m, a KrF excimer laser (about 248 nm) or an ArF excimer laser (about 193
m).

Next, a third embodiment of the present invention will be described. The exposure apparatus used in this embodiment has the same configuration as that shown in FIG.

FIG. 24 is an explanatory diagram of the mask (M) according to the present embodiment. In this embodiment, the mask 223 is an FM mask and R
Two masks of the M mask are provided on the same substrate 223a or on the same plane. FM mask can be used with normal projection exposure
It is composed of a periodic pattern FMP in which fine patterns that cannot be resolved are periodically arranged. The RM mask is formed of a normal circuit pattern (for example, a gate pattern) RMP having a line width that can be resolved by projection exposure. The bottom view of the figure shows a cross section, and shows a case where the FM pattern is a phase type pattern.

FIG. 25 is an explanatory view of the exposure state of the patterns F and M of the FM mask and the RM mask of the mask 223 on the surface of the wafer 228.

The figure shows a state in which the projected pattern image F of the FM mask and the projected pattern image R of the RM mask on the mask substrate MP are stepwise exposed on the surface of the photosensitive substrate (wafer) W in the direction of the arrow.

In the figure, one shot area SP corresponds to one chip. FM mask and RM in one shot area SP
The pattern image of the mask is sequentially exposed stepwise in the direction of the arrow (step direction) ST, and then exposed in the opposite direction with a shift of one shot, thereby performing multiple exposure (double exposure) on the same shot area. .

The mask 223 has an FM mask and an RM mask arranged in a direction perpendicular to the step direction ST, and simultaneously projects pattern images on different shot areas SP.

In this embodiment, the size of the mask M is twice the normal size. By repeating such step exposure, multiple exposures (double exposures) are performed in the same shot SP with different patterns at high throughput.

FIG. 30 is an explanatory view showing a projected pattern image when a pattern of a conventional mask M is projected and exposed on a wafer surface and a shot area on the wafer surface. When multiple exposure is to be performed by the conventional method, one shot area is step-exposed with one mask pattern as shown in the figure, and after that, step exposure is similarly performed using the next new mask. .

On the other hand, in this embodiment, multiple exposure can be performed at high throughput by using the exposure method as shown in FIG.

FIG. 26 is an explanatory diagram of an exposure state of the RM mask and the patterns F and M of the RR mask on the wafer surface in another embodiment of the present embodiment.

In the present embodiment, the size of the FM mask and the RM mask on the surface of the mask M in the step direction and the vertical direction is halved compared to the embodiment of FIG. The difference is that they are the same size as the mask.

Two chip areas C are included in one shot area SP.
P is provided. The pattern image F of the FM mask and the pattern image R of the RM mask are simultaneously projected and exposed on each chip area CP in one shot SP, and this is step-exposed in the direction of the arrow as in FIG. The same chip area is subjected to multiple exposures with different patterns F and M by performing step exposure with only a shift.

In the present embodiment, one chip area is arranged at regular intervals with chips in adjacent shots including scribe lines.

The illumination optical system 222 of the exposure apparatus in FIG. 23 is configured so that partial coherent illumination and coherent illumination can be performed at the same time, as will be described later. 1
The illumination light of a) or (1b) is supplied to one mask such as a Levenson type phase shift reticle, an edge shifter type reticle, or a periodic pattern reticle having no phase shifter, and a partially coherent illumination is shown in a block 230. The illumination light of (2a) is supplied to another mask having a normal pattern. Simultaneous illumination of the partial coherent illumination and the coherent illumination is, as described later, among a plurality of fly-eye lenses included in the optical system 222, an arrangement angle of a plurality of fly-eye lenses in a central region and a plurality of fly-eye lenses in a peripheral region. The shape and the shape are adjusted, and the emission angle of the light beam emitted therefrom is changed.

The exposure method and exposure apparatus of the present invention
The exposure wavelength in the double exposure is 400 nm or less, preferably 250 nm or less. To obtain light having an exposure wavelength of 250 nm or less, use a KrF excimer laser (about 248 nm).
m) or an ArF excimer laser (about 193 nm).

In the present invention, the term "projection exposure" refers to exposure in which three or more parallel light beams from an arbitrary pattern formed on a mask are incident on an image plane at various angles different from each other. Things.

The exposure apparatus of the present invention has a projection optical system for projecting a mask pattern onto a wafer, and a mask illumination optical system 222 capable of simultaneously performing both partial coherent illumination and coherent illumination. Exposure of the normal pattern of the FM mask is performed by illumination, and two-beam interference exposure is performed by coherent illumination.
It is characterized in that the periodic pattern exposure of the M mask is performed simultaneously. “Partial coherent illumination” is illumination in which the value of σ = (numerical aperture of the illumination optical system / numerical aperture of the projection optical system) is greater than zero and less than 1, and is “coherent illumination”.
Means that the value of σ is zero or a value close to it, and is considerably smaller than σ of the partially coherent illumination.

In coherent illumination in periodic pattern exposure, σ is set to 0.3 or less. Partial coherent illumination during normal exposure makes σ 0.6 or more. σ = 0.8 is desirable. Furthermore, it is still more effective to use annular illumination in which the illuminance distribution is lower on the inside than on the outside.

FIGS. 27 and 28 are explanatory diagrams of an optical system capable of simultaneously performing partial coherent illumination and coherent illumination as the mask illumination optical system 222 in the embodiment of the present invention.

In the figure, reference numeral 51 denotes a fly-eye lens (optical integrator), on which a plurality of secondary light sources are formed on the exit surface. The fly-eye lens 51 is tilted so that the exit angle of the light beam from the plurality of fly-eye lenses 51a in the central region and the exit angle of the light beam from the plurality of fly-eye lenses 51b in the peripheral region are different from each other. , Shape, etc. are set.
The luminous flux from the secondary light source on the exit surface of the fly-eye lens 51a (51b) passes through the stop 52,
3, one surface 54a (54b) on the stop 54 surface is overlapped.

A condenser lens 55 illuminates the FM mask (RM mask) of the mask M with a light beam having passed through the openings 54a (54b) of the diaphragm 54. Here, the small σ in FIG.
FIG. 28 shows a large σ (ring zone) illumination system.

In the optical systems shown in FIGS. 27 and 28, F
It is preferable to provide light amount adjusting means (such as an ND filter) for adjusting the illumination intensity of the M mask and the RM mask in one optical path.

FIG. 29 is an explanatory diagram showing the relationship between the effective light source and the mask in the illumination systems of FIGS. 27 and 28. FIG.
FIG. 29A shows the case of the small σ illumination system of FIG.
B) shows the case of the large σ illumination system of FIG.

The projected state of the pattern of the FM mask illuminated by the illumination system of FIG. 27 is the same as in FIGS. 19 to 21 described above.

Using the above-described exposure method and exposure apparatus, 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 image pickup elements such as CCDs can be manufactured. .

The present invention is not limited to the embodiments described above, and can be variously modified without departing from the gist of the present invention. In particular, the number of exposures and the number of exposure steps in each step of the two-beam interference exposure and the normal exposure can be appropriately selected, and the exposure can be appropriately adjusted, for example, by shifting the overlapping of the exposures. By performing such an adjustment, variations in circuit patterns that can be formed increase.

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

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

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

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

FIG. 31 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), the circuit of the 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 manufacturing), a wafer is manufactured using a material such as silicon. Step 4
The (wafer process) is called a pre-process, and an actual circuit is formed on the wafer by lithography using the prepared mask and wafer.

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

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

FIG. 32 shows a detailed flow of the wafer process. Step 11 (oxidation) oxidizes the wafer's surface. Step 12 (CVD) forms an insulating film on the wafer surface.

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

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

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

[0194]

As described above, the present invention provides (a-1) an exposure method and an exposure apparatus capable of performing multiple exposures in a relatively short time.

(B-2) A circuit pattern having a complicated shape can be formed by using two exposure methods, a periodic pattern exposure represented by a two-beam interference scanning exposure and a normal pattern exposure (normal exposure) not including the periodic pattern. An exposure method and an exposure apparatus that can be formed on a wafer.

(A-3) An exposure method and an exposure apparatus capable of easily obtaining a circuit pattern having a portion having a line width of 0.15 μm or less.

(A-4) An exposure apparatus capable of performing two exposure methods, periodic pattern exposure and normal exposure. Can be achieved.

In particular, according to the present invention, (a-5) a complex pattern having a fine line width of, for example, 0.15 μm or less can be obtained by fusing two-beam interference exposure with ordinary exposure.

[Brief description of the drawings]

FIG. 1 is a schematic view of an embodiment of an exposure apparatus of the present invention.

FIG. 2 is an explanatory view of a reticle and a plate according to the present invention.

FIG. 3 is an explanatory view of a reticle and a plate according to the present invention.

FIG. 4 is a flowchart of an exposure method according to the present invention.

FIG. 5 is an explanatory view showing an exposure pattern by two-beam interference exposure.

FIG. 6 is an explanatory diagram showing exposure sensitivity characteristics of a resist.

FIG. 7 is an explanatory view showing pattern formation by development.

FIG. 8 is an explanatory view showing an exposure pattern by ordinary two-beam interference exposure.

FIG. 9 is an explanatory view showing an exposure pattern by two-beam interference exposure in the present invention.

FIG. 10 is an explanatory view showing an example of an exposure pattern (lithography pattern) that can be formed in the first embodiment of the present invention.

FIG. 11 is an explanatory view showing another example of an exposure pattern (lithography pattern) that can be formed in the first embodiment of the present invention.

FIG. 12 is an explanatory view showing another example of an exposure pattern (lithography pattern) that can be formed in the first embodiment of the present invention.

FIG. 13 is an explanatory view showing a gate pattern according to the second embodiment of the present invention.

FIG. 14 is an explanatory view showing Embodiment 2 of the present invention.

FIG. 15 illustrates a gate pattern.

FIG. 16 is an explanatory diagram of a formed gate pattern.

FIG. 17 is an explanatory diagram of a formed gate pattern.

FIG. 18 is a schematic view showing an example of a conventional two-beam interference exposure apparatus.

FIG. 19 is a schematic diagram illustrating an example of a projection exposure apparatus that performs two-beam interference exposure.

20 is an explanatory view showing an example of a mask and an illumination method used in the apparatus shown in FIG.

21 is an explanatory view showing another example of a mask and an illumination method used in the apparatus of FIG.

FIG. 22 is a schematic view showing a conventional projection exposure apparatus.

FIG. 23 is a schematic view showing an example of a two-beam interference exposure apparatus of the present invention.

FIG. 24 is an explanatory view of the mask of FIG. 23;

FIG. 25 is an explanatory diagram of a projection mask pattern on the wafer surface of FIG. 23;

FIG. 26 is an explanatory diagram of a projection mask pattern on the wafer surface of FIG. 23;

FIG. 27 is an explanatory diagram of the illumination optical system of FIG. 23;

FIG. 28 is an explanatory diagram of the illumination optical system of FIG. 23;

FIG. 29 is an explanatory view of exposure conditions of the exposure apparatus of FIG.

FIG. 30 is an explanatory diagram of a conventional exposure sequence.

FIG. 31 is a flowchart of a device manufacturing method of the present invention.

FIG. 32 is a flowchart of a device manufacturing method according to the present invention.

[Explanation of symbols]

 221 Excimer laser 222 Illumination optical system 223 Mask (reticle) 224 Mask (reticle) stage 225 2 Light beam interference mask and mask for normal projection exposure 226 Mask (reticle) changer 227 Projection optical system 228 Wafer 229 XYZ stage

Continuation of the front page (56) References JP-A-6-181164 (JP, A) JP-A-4-273245 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01L 21 / 027 G03F 7/20 521

Claims (22)

(57) [Claims] 1. A plurality of masks different from each other by light from a light source.
An illumination optical system for illuminating a mask pattern, and the mask pattern
A projection optical system for projecting light from the
An exposure apparatus, wherein the exposure apparatus has an exposure mode for performing multiple exposure,
Holds multiple mask patterns on a common mask stage
The plurality of mask patterns are provided under different illumination conditions.
Exposure apparatus characterized in that illumination is performed simultaneously by using the same. 2. The method according to claim 1, wherein the different illumination conditions include a partial
Features include coherent lighting and coherent lighting
The exposure apparatus according to claim 1, wherein 3. The method according to claim 1, wherein the plurality of mask patterns are
And the periodic coherent illumination.
Illuminating said normal pattern with light, said coherent illumination
Illuminating the periodic pattern with
3. The exposure apparatus according to item 2. 4. The lighting conditions different from each other are σ
2. The method according to claim 1, wherein (sigma) is different.
Exposure equipment. 5. The lighting conditions different from each other are N
A (numerical aperture) is different, The characteristic of Claim 1 characterized by the above-mentioned.
Exposure equipment. 6. The lighting conditions different from each other are different from each other.
2. The method according to claim 1, wherein incident angles of bright light are different.
Exposure equipment. 7. The illumination optical system according to claim 1, wherein a plurality of lights in a central area are provided.
Emission angle of luminous flux from lie-eye lens and multiple surrounding areas
The exit angle of the light beam from the fly-eye lens
Having an optical integrator such that
The luminous flux from a plurality of fly-eye lenses in the central region
To the first mask pattern of a plurality of mask patterns
Illumination and a plurality of fly-eye lenses in the peripheral area
A second mask of the plurality of mask patterns by a light beam;
It is characterized in that illumination of the mask pattern is performed simultaneously.
The exposure apparatus according to claim 1. 8. The method according to claim 1, wherein the first mask pattern is a periodic pattern.
And the second mask pattern is a normal pattern.
8. The exposure apparatus according to claim 7, wherein the exposure apparatus is provided. 9. The mask pattern different from one another,
Claims characterized in that they are formed on separate substrates.
Item 9. An exposure apparatus according to any one of Items 1 to 8. 10. The mask patterns different from each other are shared.
4. The method according to claim 1, wherein the substrate is formed on a common substrate.
8. The exposure apparatus according to any one of 8 above. 11. The method according to claim 11, wherein the substrate is transparent.
An exposure apparatus according to claim 9. 12. A method according to claim 11, wherein said mask patterns are different from each other.
One of them is a line and space pattern,
The line and space pattern is a Levenson-type phase
Shift mask or shifter edge type phase without light shielding
12. A shift mask, comprising: a shift mask.
The exposure apparatus according to claim 1. 13. A KrF excimer laser and an ArF excimer laser.
Use the light from a Shima laser or F2 excimer laser to
Illuminating a number of mask patterns
13. The exposure apparatus according to any one of 1 to 12. 14. A projection optical system comprising a reflecting system.
2. The method according to claim 1, wherein the mask pattern is projected.
14. The exposure apparatus according to any one of claims 13 to 13. 15. A mask line and space pattern.
An exposure method for exposing a substrate to be exposed with
Line and space pattern
Formed in a rectangular area that is long in the return direction,
The substrate is exposed while the mask is fixed.
Scanning in a direction orthogonal to the return direction.
Light method. 16. The line and space pattern
Is a Levenson-type phase shift mask or no light-shielding part.
Characteristic shifter edge type phase shift mask
The exposure method according to claim 15, wherein 17. KrF excimer laser, ArF excimer laser
The light from a Shima laser or F2 excimer laser
The pattern is illuminated.
7. The exposure method according to 6. 18. A projection optical system comprising a reflecting system.
And projecting said pattern.
18. The exposure method according to any one of 17). 19. The method according to claim 15, wherein
Dew, characterized in that it comprises an exposure method as the exposure mode
Light device. 20. An exposure apparatus comprising : a step-and-repeat device;
Wherein the exposure apparatus is of a reduced projection type.
The exposure apparatus according to any one of claims 1 to 14. 21. A method according to claim 21, wherein said exposure apparatus is a step-and-scan.
A reduction projection type exposure apparatus.
20. The exposure apparatus according to any one of 1 to 14 and 19. 22. Claims 1 to 14 and 19 to 21
The device pattern using the exposure apparatus according to any one of the preceding items.
Exposing the wafer; and developing the exposed wafer.
Device manufacturing method comprising the steps of:
Law.