JP2940553B2 - Exposure method - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exposure method for transferring an original pattern formed on a mask onto a sensitive substrate in order to manufacture a semiconductor device, a liquid crystal device, and the like. .

[Conventional technology]

In the manufacture of semiconductor devices, miniaturization and high integration are progressing year by year, and a lithography process of a 1 Mbit memory and a 4 Mbit memory, which is increasingly thinner, is required.

In order to respond to this demand, a reduction projection hard exposure apparatus (stepper) is mainly used as an exposure apparatus currently used in a lithography process. Especially 1/5 of reticle with original pattern
In a reduction projection lens, a method of exposing a resist layer on a wafer by reducing the size to about 15 × 15 mm square is often used.

Each year, the stepper projection lens has a higher numerical aperture (NA) to increase the resolution, and the wavelength of the exposure illumination light
At 436 nm (g-line), a NA of about 0.48 has been put to practical use.

Increasing the numerical aperture of the projection lens in this way requires:
This means that the effective depth of focus decreases accordingly, and the depth of focus of the projection lens with NA = 0.48 is, for example, ± 0.8 μm or less. That is, assuming that one shot area on the wafer is 15 × 15 mm square, the entire surface (resist layer) of this area is ±± with respect to the best imaging plane of the projection lens.
It must be accurately positioned within 0.8 μm (preferably within ± 0.2 μm).

In order to cope with the shortage of the depth of focus of the projection lens, a method has been proposed in which a pattern of the same reticle is multiple-exposed while displacing the wafer with respect to the projection lens in the optical axis direction.

This method increases the apparent depth of focus of the projection lens, and is one effective exposure method.

[Problems to be solved by the invention]

This multifocal exposure method attempts to guarantee the contrast over a wide focal range, although the contrast at the best focus is slightly reduced. According to the results of experiments and the like, this method has been applied to a pattern for a so-called contact hole process in which the pattern surface of the reticle is almost a dark area (shielding area) and rectangular openings (transmission areas) are scattered therein. Is valid, but other patterns,
In particular, at present, it is not as effective as a contact hole for a reticle pattern such as a wiring layer in which a bright and dark linear pattern is repeated. In such a reticle pattern such as a wiring layer, when the focal position is changed, light intensity due to a defocused image of a bright line portion is given to a portion that should be a dark line on the wafer, resulting in a sharp decrease in contrast and a decrease in resist. This is because the film is reduced.
Further, in the projection exposure method, the performance is limited to a value that is equal to or longer than the cycle of the repetitive pattern that can be transferred due to the performance of the projection lens. This value is also called the resolution limit of the projection lens,
Currently practically used, g-line reduces 1/5, NA
When = 0.45, the line width of the bright line and the dark line of the repeated pattern is about 0.8 μm on the wafer (4 μm on the reticle).

Therefore, even if the line width of the pattern on the reticle is reduced,
It is considered that a pattern having a line width smaller than that is not normally exposed, and the limit of lithography by the projection exposure method is determined solely by the performance (resolution) of the projection lens.

Also in the proximity exposure method, it is difficult to make the repetition period of the bright and dark lines on the mask smaller than a certain value due to the diffraction phenomenon that occurs according to the wavelength of the illumination light. doing. For this reason, special energy rays such as soft X-rays were required.

The present invention has been made in view of these problems,
It is a first object of the present invention to transfer a finer pattern without extremely increasing the numerical aperture of a projection optical system and reducing the wavelength of illumination light.

Further, a second object of the present invention is to obtain a method capable of transferring a finer pattern irrespective of a projection exposure method or a proximity exposure method.

It is a third object of the present invention to provide a method capable of sufficiently obtaining the effect of the multifocal exposure method even for most patterns other than the contact holes.

[Means to solve the problem]

The first invention of the present application is a method of exposing a first pattern and a second pattern to the same sensitive layer on a substrate sequentially to expose a desired entire pattern on the substrate.
The entire pattern is disassembled such that one of the patterns is exposed to a projection on the substrate surface and the other is exposed to a depression on the substrate surface.

The second invention of the present application is a method of forming a predetermined pattern on a substrate by sequentially exposing a first pattern and a second pattern to the same sensitive layer on the substrate, wherein the first pattern and the second pattern are formed. When the convex part of the substrate concave surface is exposed using one of the patterns, and the concave part of the substrate surface is exposed using the other pattern, the exposure using the one pattern and the exposure using the other Thus, the positional relationship between the pattern image plane by the projection optical system and the substrate is changed.

Here, the outline of the present invention will be described with reference to FIG. In FIG. 1, the whole patterns to be formed on the sensitive substrate are patterns PA and PB formed in a chip (or shot) area CP, and the pattern PA is a line-and-space (L / S) pattern. The pattern PB is a simple L / S pattern.

The patterns PA and PB are each divided into three decomposition patterns, and each decomposition pattern is formed on _three reticles R ₁ , R ₂ and R ₃ . Each of the reticles R ₁ , R ₂ , and R ₃ has three patterns PTA ₁ , PTA ₂ , and PTA in which a light-shielding band SB corresponding to the chip area CP is formed around the periphery, and a pattern PA is decomposed into the inside thereof.
₃ and three patterns PTB ₁ and PT
B ₂ and PTB ₃ are formed. Each reticle R ₁ , R ₂ ,
R ₃ is provided with alignment marks RM ₁ , RM ₂ , RM ₃ , RM ₄ , and a mark W provided along with the chip area CP.
_{M 1, WM 2, WM 3} , are used for alignment and WM _4.

The patterns PTA ₁ , PTA ₂ , PTA ₃ , PTB ₁ , PTB ₂ , and PTB ₃ are shown by dark lines in the figure, but are actually bright lines by the light transmitting portion.
After positioning and exposing the patterns PTA ₁ and PTB ₁ to the chip area CP, changing to the reticle R ₂ and positioning and exposing the patterns PTA ₂ and PTB ₂ to the chip area CP, and then positioning the reticle R ₃ The patterns PTA ₃ and PTB ₃ are exposed.

Each of the patterns PTB ₁ , PTB ₂ and PTB ₃ is L / L of the pattern PB.
Of the S pattern, a line pattern corresponding to a bright line is taken out every two lines and put together. The pitch of the line and space is three times that of the whole pattern (duty is 1/3) I have. The same applies to each of the patterns PTA ₁ , PTA ₂ , and PTA ₃ .However, in each pattern, as in each line of the pattern PA, the pattern is decomposed so that a continuous line bent at 90 ° does not occur. is there. The 90 ° bend is defined so that the ends of two lines (each line is formed on a separate reticle) that are perpendicular to each other partially overlap. As described above, in the case of the line-and-space pattern, adjacent bright lines are formed on different reticles, and the pattern density of the bright lines in one reticle is reduced (see FIG. 1). In this case, 1/3) was used to measure the isolation of the bright line.

(Operation)

FIG. 2 (A) shows a case of forming the entire pattern P _a line-and-space form as it is one of the reticle R, FIG. 2 (B) is the pattern P _a of FIG. 2 (A) shows the case of a degradation pattern P _b forming the bright line on every other. Here P _a, the width of the bright lines of P _b are equal, it is d. When these reticles R are irradiated with illumination light, diffracted light is generated in a direction corresponding to each pattern pitch P. The diffraction angle θ of the n-th order diffracted light is represented by It is expressed as That is, the diffraction angle it is the same diffraction orders greater degradation pattern P _b is the pattern pitch becomes small,
As a result, the amount of diffracted light that contributes to the primary or higher order imaging increases, and the image contrast increases. An example is shown below.

2 (C), (D) and (E) show g-line, NA = 0.45,
0.4μmL / S on a photosensitive substrate using a σ = 0.5 projection lens
The figure shows the calculated value (simulation) of the aerial image at the best focus when projecting (exposure pattern of 0.4 μm wide bright line and dark line). Here, the σ value represents the ratio of the area of the entrance pupil of the projection lens to the area of the light source image. FIG. 2 (C) shows the intensity distribution of the aerial image when exposed by one reticle. The horizontal axis is the position (μm) on the photosensitive substrate with the center of a certain bright line as the origin, and the vertical axis is relative. Strength. FIG. 2 (F) shows the sum of the aerial image intensities separated into two reticles and each exposed, and FIGS. 2 (D) and (E) show the intensity distribution of the aerial image of the decomposed pattern, respectively. . As is clear from this simulation, the contrast of the aerial image is improved by dividing and exposing the pattern.

That is, in the case of an L / S pattern, by using two or more decomposition patterns, even if a projection lens having the same numerical aperture is used, more high-order light can be used for imaging. This gives a more detailed linear pattern,
This means that the image is formed as much as possible up to the resolution limit determined by the performance of the projection lens, and the image quality of the pattern (image quality of the resist pattern) is improved.

Further, by making the pattern P _b were low ratio of bright portions for the entire pattern P _a, even when the best imaging plane and the photosensitive substrate surface of the projection lens is defocused, the dark portion of the pattern P _b de The focused image keeps the dark portion to the last, does not become brighter, and only the intensity of the brighter image is reduced. Therefore, if the multifocal exposure method is performed for each of the decomposition patterns, an effect of increasing the apparent depth of focus can be obtained as in the case of the contact hole.

〔Example〕

FIG. 3 is a perspective view showing a configuration of a projection type exposure apparatus (stepper) suitable for the embodiment of the present invention. The basic configuration of this stepper is the same as that disclosed in, for example, Japanese Patent Application Laid-Open No. 62-145730, and will be briefly described below.

Illumination light from the exposure light source 2 passes through an illumination optical system 4 having a reticle blind (illumination field stop) and the like, and illuminates one reticle on a reticle stage 6. The reticle stage 6 has four reticles R ₁ , R ₂ ,
R ₃ and R ₄ can be placed at the same time and move two-dimensionally in the x and y directions. On the reticle stage 6, movable mirrors 8x and 8y for reflecting a laser beam from a laser interferometer 10 for position measurement are fixed at right angles to each other. Reticle alignment system
12 detects the alignment marks RM ₁ ~RM ₄ reticle mark WM ₁ ~WM ₄ on the wafer W is also provided to be detected. Therefore, the alignment system 12 is four one case a reticle positioned relative placement or simultaneously detects and die-by-die marks RM ₁ ～RM ₄ marked WM ₁ ～WM _4, of the It can be used for both alignment. Although only one alignment system 12 is provided in FIG. 3, each of the marks RM ₁ , R 2 shown in FIG.
Corresponding to M _2, RM _3, RM ₄ are arranged in a plurality places. Photoelectric detector of marks RM ₁ ~RM _4, or marks WM ₁ ~WM ₄ is performed by the mark detection system 14.

Now, the image of the reticle pattern area is projected by the projection lens system 16.
Are image-formed and projected on a chip area CP formed in advance on the wafer W via the. The wafer W is placed on a wafer stage 26 that moves in the x and y directions.
A Y stage 26y moves in the direction, an X stage 26x moves on the Y stage 26y in the x direction, and a Z stage 26z moves slightly on the X stage 26x in the projection optical axis direction (Z direction). On the Z stage 26z, moving mirrors 28x and 28y that reflect laser beams from the laser interferometers 30x and 30y are fixed at right angles to each other. The wafer W is placed on the Z stage 26z.
The reference mark FM is fixed so that the height is substantially the same as that of the reference mark FM. The driving is performed by drive motors 27x and 27y in the X-axis stage 26x and the Y-stage 26y in respective axial directions. Here, the projection lens system 16 incorporates an imaging correction mechanism 18, and the optical characteristics (magnification, focus, certain types of distortion, etc.) of the projection lens system 16 that fluctuate depending on the energy accumulation state due to the exposure light exposure, environmental conditions, and the like. ) Is automatically corrected every moment. The image forming correction mechanism 18 is disclosed in detail in, for example, Japanese Patent Application Laid-Open No. Sho 60-78454, and the description thereof is omitted here. In addition, a mark (WM) on the wafer W is provided from below the reticle stage 6 via only the projection lens system 16 to this stepper.
_{1 to} WM ₄ ) and a TTL (through-the-lens) type alignment system including a mark detection system 22 that photoelectrically detects mark light information detected by the alignment optical system 20. And an off-axis type alignment system 24 separately provided in the vicinity of the projection lens system 16.

Although not shown in FIG. 3, an oblique incidence light type focus sensor for detecting the height position of the surface of the wafer W with high resolution is disclosed in Japanese Patent Application Laid-Open No. 60-78454. And operates together with the Z stage 26z as an automatic focusing mechanism for always matching the best imaging plane of the projection lens system with the wafer surface.

Here, the optical relationship between the illumination optical system 4 and the projection lens system 16 in the configuration of FIG. 3 will be described with reference to FIG. The illumination optical system 4 is configured to project a secondary light source image (surface light source) into the pupil EP of the projection lens system 16, and employs a so-called Koehler illumination method. The surface light source image is set to be slightly smaller than the size of the pupil EP. Now, looking focusing on one point of the reticle R with an entire pattern P _a,
The illumination light IL reaching this point has a certain solid angle θ _r / 2. The solid angle theta _r / 2 is stored after having passed through the entire pattern P _a, the projection lens system as a light flux D _a0 of the zero-order light 16
Incident on. The solid angle θ _r / 2 of the illumination light IL is also called the numerical aperture of the illumination light. Further assuming that the projection lens system 16 is bilateral telecentricity stick system, a people husband reticle R side and the wafer W side, the principal ray l ₁ passing through the center of the pupil EP (point where the optical axis AX passes) is an optical axis AX Be parallel. Light beam passing through the pupil EP thus the wafer W becomes imaging light beam IL _m at the wafer W side
An image is formed at one point above. In this case, the reduction magnification of the projection lens system 16 is 1/5, the solid angle theta _w / 2 of the light beam IL _m is theta _{w =} 5
· Θ a relationship of _r. It is also called the numerical aperture of the imaging light beam on the wafer W having the solid angle θ _w / 2. The projection lens system 16
The numerical aperture of the wafer side alone is defined by the solid angle of the light beam IL _m when passed through the light beam to fill the pupil EP.

Now, the entire pattern P _a is the is equivalent to that shown in FIG. 2 (A), 1 or higher-order diffracted light D _a1, D _a2, ...... occurs. These higher-order light and to those generated flare outwardly of 0 Tsugikotaba D _a0, to that generated and distributed to the inside of 0 Tsugikotaba D _a0 is. In particular some of the high-order light distributed outside of the 0 Tsugikotaba D _a0 is, even if will be eclipsed by the pupil EP as incident on the projection lens system 16, it does not reach the wafer W. Therefore, if more higher-order diffracted light is to be used for imaging, the diameter of the pupil EP must be as large as possible, that is, the numerical aperture (NA) of the projection lens system 16 must be further increased. Alternatively, by reducing the numerical aperture of the illumination light IL (solid angle theta _r / 2) (to reduce the diameter of the surface light source image), small divergence angle, such as higher-order light D _a1, D _a2 from the pattern P _a It is also possible to hold down. However, in this case,
In the wafer W side 0-order numerical aperture of the imaging light beam IL _m (solid angle theta _w /
If 2) is made extremely small, the original resolution performance will be impaired. Further Originally, since the diffraction angle of the higher-order light by the pitch or duty of the pattern P _a will uniquely determined, even it can be brought close to the solid angle theta _r / 2 of the illuminating light IL to zero temporarily, high-order More than a certain order of the folded light will be cut off by the pupil EP. However, when the entire pattern is divided into a plurality of decomposition patterns as in the present embodiment, as is clear from FIG. 2B, the diffraction angle of the high-order light spreading outside the 0-order light beam can be suppressed to a small value. pupil
EP can be easily passed.

In FIG. 3, four reticles R _{1 to} R ₄ are mounted on the same reticle stage 6, and the center of any one of the reticles is located on the optical axis AX of the projection lens system 16. Is interchangeable. Since the laser interferometer 10 is used, the positioning accuracy of each reticle at the time of replacement can be made extremely high (for example, ± 0.02 μm). Therefore, if the mutual positional relationship between the _four reticles R _{1 to} R ₄ is precisely measured in advance, each reticle is moved by moving the reticle stage 6 based only on the coordinate measurement values of the laser interferometer 10. Can be positioned. Even if the mutual positional relationship between the reticles R _{1 to} R ₄ is not measured in advance, the alignment system 12, the mark detection system 14, the reference mark FM
Positioning can be precisely performed by using the method described above.

Further, in the present embodiment, each of the reticles R _{1 to} R ₄ having the decomposition pattern uses the multiple focus exposure method at the time of exposure. For this reason, when exposing one chip area (shot area) CP on the wafer W using a certain reticle, the height position Z ₀ of the wafer surface detected as the best focus point by the oblique incident light type focus sensor; For example, a height position Z ₁ above this position Z _{0 by} about 0.5 μm and a height position Z ₀
Repeatedly to perform the exposure in each of the three focal positions of the height position Z ₂ of under about 0.5 [mu] m. Therefore, while exposing a certain chip area CP with one reticle, the height of the wafer W is moved up and down in 0.5 μm steps by the Z stage 26z.

Incidentally, instead of moving the Z stage 26z up and down during the exposure operation, the same effect can be obtained by moving the best imaging plane (reticle conjugate plane) of the projection lens system 16 itself up and down using the imaging correction mechanism 18. Can be In this case, as disclosed in Japanese Patent Application Laid-Open No. Sho 60-78454, the image forming correction mechanism 18 includes a projection lens system.
Since it is a method of adjusting the gas pressure in the sealed lens space in 16, the exposure operation uses the offset pressure value for moving the image plane up and down by about ± 0.5 μm to the pressure adjustment value for the original correction. Just add it inside. At this time, it is necessary to select a combination of lens spaces that changes only the focal plane due to the pressure offset and does not change the magnification, distortion, and the like.

Further, by taking advantage of the fact that the projection lens system 16 is telecentric on both sides, by moving the reticle up and down, the height position of the best imaging plane can be similarly changed. In general, in the case of reduced projection, the defocus amount on the image side (wafer side) is converted into the defocus amount on the object side (reticle side).
It is determined by the square of the reduction magnification. For this reason, when the defocus of ± 0.5 μm is required on the wafer side, if the reduction magnification is set to 1/5, then ± 0.5 / (1/5) ² = ± 12.5 μm on the reticle side.

Next, although there is no direct relationship with the present invention as a method of dividing the entire pattern into the decomposition patterns, some examples of the division method will be described with reference to FIGS. 5, 6, 7, and 8. Will be explained.

Entire pattern Fig. 5 is a bright line pattern PL _s of FIG. 5 bright line pattern with a width D ₁ as shown in (A) PL _c and width _{D 2 (D 2 ≒ D 1} ) are alternately repeated In the case of a line and space, each of the two reticles is shown in FIG.
This is an example of forming a decomposition pattern as shown in FIG.
The degradation pattern of degradation pattern and the fifth view of FIG. 5 (B) (C), both bright line pattern PL _c is formed on every other than the entire pattern. And in two degradation pattern comrades, the position of the bright line pattern PL _c is in complementary. In this case, the pitch in the entire pattern is D ₁ + D ₂
(≒ 2D ₁ ), the duty is D ₁ / (D ₁ + D ₂ ) ≒ 1/2, but the resolution pattern pitch is 2D ₁ + 2D ₂ (≒ 4D ₁ ), and the duty is D ₁ / (2D ₁ + 2D) ₂ ) It becomes ≒ 1/4. Therefore so that isolation of the bright line pattern PL _c on each reticle is timed.

FIG. 6 shows that the overall pattern is L / S as shown in FIG. 6 (A).
When Jo, rather than divide pretend to each bright line pattern PL _c separate reticle for each, to decompose the respective bright line patterns all smile rectangular light portion PL _d, FIG. 6 (B), (C) It shows a state where they are arranged complementarily to each other as shown in FIG. In this way, the two degradation patterns are rectangular bright portion PL _d which together isolate is defined so as to shift in a direction orthogonal to each other in the pitch direction L / S. Therefore, any one rectangular bright part
Focusing on PL _d , on both sides of the L / S pitch direction,
A dark portion having a width (D ₁ + 2D ₂ ) exists, and the duty in the pitch direction is about 1/4.

FIG. 7 shows a linear pattern which is bent at a right angle in the entire pattern as shown in FIG. 7 (A) and is divided into two directions by bending portions as shown in FIGS. 7 (B) and (C). This shows how linear patterns PT _e and PT _f are formed. Where the patterns PT _e , PT _f
The inside is a transparent part and the surrounding is a shielding part. Here, if the two patterns PT _e and PT _f are bright portions, they may be partially overlapped at the bent portions. However, the overlapping portion is set to be approximately 45 ° with respect to the longitudinal direction of each of the two patterns PT _e and PT _f . For this reason, the connecting portions of the patterns PT _e and PT _f are not formed at a right angle but are formed, for example, at a shape cut out at 45 °. Thus, the linear pattern bent at 90 ° is formed into two patterns P
When decomposed into T _e and PT _f and superposed and exposed, especially the image reproduction on the resist at the bent portion becomes good, and the shape of the inner corner portion rounded at 90 ° is exposed clearly. The same method can be applied to a linear pattern bent at another angle. Even if it is not a linear pattern,
In the case of a pattern having an edge bent at an acute angle (90 ° or less), the pattern may be decomposed into two patterns according to the two directions of the edge.

FIG. 8 shows the entire pattern intersecting in a T-shape as shown in FIG. 8 (A) into two linear patterns PT _g and PT _h depending on the directions as shown in FIGS. 8 (B) and (C). Shows the case of decomposition. Assuming that the linear patterns PT _g and PT _h are both bright portions, the tip of the linear pattern PT ₉ is an isosceles triangle having an angle of 90 ° or more, and this triangular portion is shown in FIG. as a), so as to partially overlap the straight edge of the pattern PT _h. In this way, the 90-degree corners of the T-shaped pattern are extremely sharp on the resist image, and are less likely to be rounded.

As described above, several examples of the pattern decomposition have been described.
For the entire pattern PA shown in FIG, in combination with FIG. 5 manner as FIG. 7, a plurality of degradation pattern PTA _1, PT
It was divided into A _2, PTA _3. The number to be decomposed may be two or more, and there is no particular limitation. However, if the number of decomposed patterns (reticles) is large, errors during superposition exposure are accumulated accordingly, which is disadvantageous in terms of throughput.

Each decomposed pattern is a separate reticle.
Was to form the R ₁ to R ₄ but, as disclosed in JP-A-62-145730, a single large glass substrate, a plurality of pattern regions of the same size, and decompose Each pattern may be provided in each pattern area.

Next, a typical sequence of this embodiment will be described with reference to FIG.

Each reticle R ₁ to R ₄ having the [Step 100] First degradation pattern is placed on the reticle stage 6, the respective reticle R ₁ to R ₄ on the reticle stage 6 is accurately positioned by using the alignment system 12. In particular, the rotation error of each of the reticles R _{1 to} R ₄ is reduced with sufficient accuracy. For this reason, a micro-rotation mechanism is provided at a portion of the reticle stage 6 that holds each of the reticles R _{1 to} R ₄ . However, a mechanism for minutely moving each of the reticles R _{1 to} R ₄ in the x and y directions can be omitted. It is because itself reticle stage 6 is precisely controlled coordinate position by the laser interferometer 10, the reticle stage 6 to detect marks RM ₁ ~RM ₄ of the reticle R ₁ to R ₄ in the alignment system 12 It is sufficient to store each coordinate value when positioning is performed. The rotation standard of each reticle R _{1 to} R ₂ is actually based on the laser interferometer 30 on the wafer stage side.
x, since a coordinate system defined by 30y, by detecting the reference mark FM and the mark RM ₁ ~RM ₄ in alignment system 12, a rotation error of each reticle R ₁ to R ₄ is in the coordinate system of the wafer stage side It is necessary to drive to zero. An alignment method relating to such reticle rotation is disclosed in detail, for example, in Japanese Patent Application Laid-Open No. 60-186845.

[Step 101] Next, the opening shape and dimensions of a reticle blind as an illumination field stop provided in the illumination optical system 4 are set to match the light-shielding band SB of the reticle.

[Step 102] Subsequently, the wafer W coated with the photoresist is loaded on a wafer stage, and several wafers W on the wafer W are formed using an off-axis type alignment system 24 or a TTL type alignment optical system 20. A mark attached to the chip area CP is detected, alignment of the entire wafer (global alignment) is performed, and the arrangement coordinates of the chip area CP on the wafer W and the optical axis AX of the projection lens system 16 (the center point of the reticle pattern area). Is defined in the xy plane. Here, when the exposure of the wafer W is first print, since the mark WM ₁ ~WM ₄ is not present, step 102 is omitted.

[Step 103] Next, the number of decomposition patterns, that is, the pattern number n corresponding to the number of reticles and the chip number m corresponding to the number of chip areas CP to be exposed on the wafer W are registered in the main controller including the computer. Is done. Where pattern number n
Is set to any one of the numbers A of the reticle, and the chip number m is set to 9 at maximum, and 1 in the initial state.
Is set to

[Step 104] Next, the reticle stage 6 is precisely positioned so that the reticle corresponding to the pattern number n is directly above the projection lens system 16.

[Step 105] Then, the wafer stage is stepped based on the chip number m, and the m-th chip area to be exposed
The CP is positioned immediately below the projection lens system 16. At this time,
The center of the n-th reticle and the center of the m-th chip area CP are usually aligned within a range of about ± 1 μm according to the result of global alignment.

[Step 106] Next, assuming that die-by-die alignment is to be executed, the mark WM attached to the chip area CP is used by using the alignment optical system 12 or the alignment optical system 20.
The positional deviation of the reticle mark RM ₁ ~RM ₄ of _{1 ~WM 4} precisely measured, the wafer stage 26 to the position deviation is within the allowable range, or any to one of the fine movement of the reticle stage 6.

Incidentally, instead of performing tie-by-die alignment using the alignment optical system 20 or the alignment optical system 12 of the TTL system, as described in Japanese Patent Application Laid-Open No. nine measures the respective position of the mark WM ₁ ~WM ₄ chip area CP, all enhanced global alignment seeking stepping position of the chip area (EGA) method by statistical calculation method based on the measurement value May be adopted.

[Step 107] Next, the m-th chip area CP is exposed with the n-th reticle. Here, since the multifocal exposure method is applied to each chip area, first, the chip area is exposed. The height position of the surface of the chip area with respect to the best imaging plane is accurately measured by operating the oblique incident light type defocus sensor.
Then, after adjusting to the best focus position by the Z stage 26z, the reticle pattern is exposed at about 1/3 of the normal exposure amount. Next, for example, 0.5 μm on the wafer W
When the position where the L / S pattern of m is accurately imaged is set as the best focus, +0.5 μm with respect to this height position,
Z stage 26z at each of two places changed by about -0.5μm
Is offset, and exposure is performed at each height position with an exposure amount of about 1/3. That is, in this embodiment, triple exposure is performed at a total of three height positions, that is, the best focus point and points before and after the best focus point. The exposure amount at each exposure of the multiple exposure may be approximately 1/3 of the normal exposure amount, but may be finely adjusted.
When the best image plane itself is moved up and down using the image correction mechanism 18, instead of fixing the image plane position stepwise, the image plane is continuously moved within ± 0.5 μm. Exposure can also be performed. In this case, the shutter provided in the illumination optical system 4 has one shutter for one chip area CP.
It only needs to be opened once, which is extremely advantageous in terms of throughput.

[Step 108] When the exposure of the m-th chip area is completed, the set value of m is incremented by one.

[Step 109] Here, it is determined whether or not exposure of all chip areas on the wafer W has been completed. Here, since the maximum value of m is 9, if m is 10 or more at this point, the process proceeds to the next step 110. If m is 9 or less, the process returns to step 105, and stepping to the next chip area is performed. It is.

[Step 110] When the n-th reticle is exposed on the wafer W, the wafer stage is reset to the exposure position for the first chip area, and the chip number m is set to 1.

[Step 111] When all the reticles of the prepared decomposition pattern have been exposed, it means that the exposure for one wafer has been completed. If there are any remaining reticles, the process proceeds to step 112.

[Step 112] Next, the pattern number n is changed to a value corresponding to another reticle, the process returns to step 104, and the same operation is repeated.

In each of the above steps, it goes without saying that step 106 is omitted in addition to step 102 in the first print.

As described above, the wafers W are sequentially processed. For example, when processing a plurality of wafers through the same process, all wafers in the lot are exposed with the first reticle. After that, the reticle may be replaced and the sequence may be such that all wafers in the lot are exposed by the next reticle. Further, when performing the die-by-die alignment in step 106, one kind of mark accompanying the chip area CP, if as used in common when the alignment of the respective each reticle R ₁ to R ₄ The relative displacement between the patterns of each reticle transferred onto the wafer W can be minimized.

Furthermore, when using the EGA method, there is a possibility that the drift of each alignment system, drive system, etc. during the exposure sequence may be a problem, but each time the reticle is replaced using the reference mark FM, or each time the wafer exposure is completed. By checking the drift of each system in advance, even if drift occurs, it can be corrected immediately.

As described above, in this embodiment, since each of the isolated decomposition patterns is subjected to multiple-value exposure at a plurality of focal positions, both the resolution limit and the depth of focus can be obtained. The resolution limit mentioned here means that the whole pattern on the reticle is dense like L / S, so the diffraction and other phenomena cause the bright and dark lines when the pattern is transferred onto the resist to separate well. This means a limit at which resolution cannot be achieved, and is different from the theoretical resolution of the projection lens system 16 alone. In the present embodiment, each linear pattern in the entire pattern is decomposed so as to be isolated, and the isolated pattern is projected, so that almost all of the theoretical resolution of the projection lens system 16 is used to obtain a finer line. Pattern can be transferred. This effect is obtained when the multi-focus exposure method is not used.
That while fixing the Z stage 26z in best focus in step 107 in FIG. 9, it is obtained in the same manner even in the case of overlay exposure reticle R ₁ to R ₄ each degradation pattern.

Next, a method of pattern decomposition according to a second embodiment of the present invention and a corresponding exposure method will be described. FIG. 10A is a cross-sectional view schematically showing an example of a circuit pattern configuration formed on the wafer W, and minute irregularities are formed on the wafer surface in the latter half of manufacturing. The minute unevenness may be larger than the depth of focus (for example, ± 0.8 μm) of the projection lens system 16 in some cases. In FIG. 10 (A), a resist layer PR is formed on the wafer surface, and a pattern is formed on the convex portion on the wafer.
Exposing the _{P r1, P r2, P r4} , shows the case of exposing a pattern P _r3 in the recess. In this case, in the conventional exposure method has been to form all the patterns P _r1 to P _r4 as a transparent portion on a single reticle, the pattern P _r1 in this embodiment that are exposed at the convex portion, P _r2, P _r4 reticle transmissive portion P _s1 on R _1, previously formed as a P _s2, P _s4, the pattern P _r3 to be exposed at the recess Figure 10 as shown in Figure 10 (B) preliminarily formed as a transparent portion P _s3 so on reticle R ₂ as (C).

Then, when performing the overlap exposure using the respective reticles R ₁ and R ₂ , when the reticle R ₁ is used, the exposure is performed such that the best imaging surface of the projection lens system 16 is aligned with the convex portion side on the wafer W, when the reticle R ₂ is exposed so as to match the concave side of the best focus plane. In this way, the chip area
It is possible to prevent all the patterns in the CP from being exposed with extremely high resolving power and projected onto the convex portions and the concave portions, thereby causing partial defogging.

In this embodiment, further, when exposing each of the reticles R ₁ and R ₂ ,
The multiple focus exposure method described in the first embodiment may be used together. When the linear pattern is exposed from the concave portion to the convex portion on the wafer W, the linear pattern is decomposed in the longitudinal direction on the reticle and divided into a portion corresponding to the convex portion and a portion corresponding to the concave portion. Good. Further, the convex portion and the concave portion on the wafer W may be divided into three stages to form three decomposition patterns, and exposure may be performed at three focal positions. Of course, you may use together the decomposition | disassembly rule demonstrated by FIG. 5-FIG.

FIG. 11 is a diagram for explaining a pattern decomposition method according to the third embodiment.

In recent years, it has been proposed to insert a sub-space mark for the purpose of accurately reproducing a minute isolated pattern (such as a contact hole) or a corner edge formed on a reticle for exposure. Figure 11 (A) represents a minute rectangular opening P _cm is formed on a reticle as a contact hole, the opening portion P _cm is 1 when exposed on the wafer
It is about 2 μm square. When this type of opening _Pcm is exposed by projection, the angle of 90 ° is often collapsed and rounded on the resist. So providing a sub-space mark M _sp small size enough not resolved (e.g. 0.2μm square on the wafer) in the vicinity of the corner portions of the four corners of the opening portion P _cm in the projection optical system.

Thus, in addition to the original opening P _cm , the sub space
When forming the mark M _sp , if the arrangement pitch of the openings P _cm becomes narrow, the sub-space mark
It becomes difficult to insert M _sp . However, as in the present invention, every other opening P _cm in the entire turn is sub-
By forming a separate reticle (or separate degradation pattern) with a space mark M _sp, 1 one opening P _cm
There is enough space (shield) around
There is an advantage that the degree of freedom in obtaining the sub space mark _Msp can be obtained.

FIG. 11B shows a case in which linear sub-space marks _Msp are provided on both sides near the end of the line pattern _Plm . When the entire pattern is divided into decomposed patterns, the sub-space mark _Msp attached to the rectangular or linear pattern to be exposed needs to be formed on the reticle together with the decomposed pattern. Also one
When one whole pattern (for example, a bent linear pattern) is decomposed into a plurality of patterns, and a corner edge is generated in each of the decomposition patterns, a new sub space mark is provided near the corner edge or the like. May be.

FIG. 12 is a diagram for explaining a pattern decomposition method according to the fourth embodiment.

In the present embodiment, in addition to the effects described in the previous embodiments, an effect is obtained that lithography with a fine line width exceeding the resolution limit of the projection optical system is achieved.

FIG. 12A shows an example of a cross section of the wafer W, and shows a case where thin line patterns _Pr5 , _Pr6 , and _Pr7 extending in a direction perpendicular to the paper surface of the resist layer PR are left as resist images.

_{Assuming that} the entire periphery of the patterns _Pr5 , _Pr6 , and _Pr7 on the resist layer PR is exposed, the decomposition pattern on the reticle is divided into two as shown in FIGS. 12 (B) and 12 (C). In FIGS. 12 (B) and 12 (C), a light-shielding portion is formed on each of the two reticles so as to overlap each other at the patterns _Pr5 , _Pr6 and _Pr7 . The width ΔD of the overlapping light-shielding portion determines the line width of the turns _Pr5 , _Pr6 , _Pr7 . As is clear here, in the conventional method, the patterns P _r5 , P
_r6, for exposing one of the dark line pattern corresponding to each of the P _r7 s, the line width of each pattern P _r5 to P _r7 is is limited by the performance of the projection lens. However, in the present embodiment, the width of the dark portion on the pattern of each of the two reticles decomposed is extremely large, and is hardly affected by diffraction. Therefore, the width ΔD can be made extremely small without being limited by the performance, diffraction, etc. of the projection lens. For example, a 0.4 μm line pattern can be formed using an exposure apparatus having a resolution limit of 0.8 μm. In the case of this embodiment, the dimensional accuracy of the pattern image transferred onto the wafer W is the alignment accuracy of the two reticles (each of the disassembled patterns), the alignment accuracy with each chip area CP on the wafer W, and the two It is conceivable that the deterioration will depend on the manufacturing error of the pattern area between the reticles. However, alignment accuracy is improving year by year, and it is thought that there will be few practical problems if a sequence in which errors in creating the pattern area of each reticle, errors in marking, etc. are measured in advance and the position is corrected during alignment is taken. Can be And the twelfth
As is clear from the pattern separation methods shown in FIGS. (B) and (C), the light amount at the time of exposure in each of the two separation patterns may be set to a substantially appropriate exposure amount for either of the separation patterns. . The resist layer PR may be either a positive type or a screw type, and it is effective to use the resist layer PR in combination with a multifocal exposure method.

Next, a fifth embodiment of the present invention will be described with reference to FIGS. 13 (A) and 13 (B). In recent years, attention has been paid to using an excimer laser light source as the light source of the stepper shown in FIG. As the excimer laser light source, a laser medium having a high laser power such as a rare gas halide (XeCl, KrF, ArF, etc.) is used. Therefore, when a high-pressure discharge is caused between the electrodes in the laser tube, strong light in the ultraviolet region can be stimulatedly emitted without a special resonance killer. In this case, the spectrum of the emitted light is broad, and the coherency is low both temporally and spatially. Such broadband light, depending on the material of the projection lens, generates extremely large chromatic aberration. In order to transmit ultraviolet light efficiently, a projection lens for an excimer laser is often made of only quartz. Therefore, the spectral width of the excimer laser light needs to be extremely narrow, and its absolute wavelength needs to be constant.

Therefore, in this embodiment, as shown in FIG. 13A, a total reflection mirror (rear mirror 201) acting as a resonator and a low-reflectance mirror (front mirror) 205 are provided outside the excimer laser tube 202. A little increase in coherency and mirror 2 outside laser tube 202
Between the 01 and the mirror 205
Perot etalons 203 and 204 were arranged to narrow the band of the laser beam. Here, the etalons 203 and 204 have two quartz plates opposed in parallel with a predetermined gap and function as a kind of bandpass filter. Etalon 203, 204
Among them, the etalon 203 is for coarse adjustment, and the etalon 204 is for fine adjustment.By adjusting the tilt angle of the etalon 204, the absolute value of the wavelength of the output laser light becomes a constant value.
Feedback control is performed successively while monitoring wavelength fluctuations.

Thus, in the present embodiment, the multifocal exposure method is performed by optically moving the best imaging plane up and down by positively utilizing the configuration of the excimer laser light source and the axial chromatic aberration of the projection lens. I made it. That is, a certain chip area
When exposing CP, etalon 20 in excimer laser light source
An excimer laser (pulse or the like) is irradiated while shifting either one of 4 and 203 by a predetermined amount from the tilt angle required for absolute wavelength stabilization. If you shift the tilt of the etalon,
Since the absolute wavelength slightly shifts, the position of the best image plane changes in the optical axis direction in accordance with the axial chromatic aberration of the projection lens. For this reason, if the tilt of the etalon is changed discretely or continuously during exposure with an excimer laser of 50 to 100 pulses, a similar multifocal exposure method can be performed without any mechanical movement between the reticle and the wafer. Can be implemented.

FIG. 13 (B) shows another configuration of the same excimer laser, in which a reflection type diffraction grating (grating) 206 as a wavelength selection element is tiltably provided instead of the rear mirror 201. In this case, the grating 206 is used for coarse adjustment when setting the wavelength, and the etalon 204 is used for fine adjustment. For the multifocal exposure method, if one of the etalon 204 and the grating 206 is tilted, the oscillation wavelength changes, and the best image plane moves up and down.

As described above, when an excimer laser is used, the image plane (focal position) can be changed using a physical phenomenon called chromatic aberration. However, chromatic aberration includes longitudinal chromatic aberration (axial chromatic aberration) and lateral chromatic aberration (magnification chromatic aberration). And each may occur simultaneously due to a change in wavelength. Since the chromatic aberration of magnification means to change the projection magnification, it is necessary to correct it to a negligible degree. Therefore, as an example, in the case of a photographic lens that is telecentric on both sides, a field lens group (correction optical system) for maintaining telecentric provided on the reticle side in the projection lens is moved up and down in the optical axis direction. If the field lens group is moved up and down in synchronization with the inclination, lateral chromatic aberration can be corrected.

Further, even in a system in which an offset is added to the control pressure in the projection lens 16 by using the image forming correction mechanism 18 shown in FIG. 3 in conjunction with it, the lateral chromatic aberration (magnification error) can be similarly corrected.

Next, another sequence of the multifocal exposure method described above will be described as a sixth embodiment.

For this sequence, the stepper shown in FIG. 3 is provided with a working interferometer for measuring the yawing of the wafer stage 26, and two measuring mirrors arranged in parallel with the moving mirror 28x or 28y at regular intervals. The long beam is projected, and the change in the optical path difference between the two measurement beams is measured. This measured value corresponds to a minute rotation error amount generated during movement of the wafer stage 26 or after stepping.

Therefore, first, for all chip areas on the wafer W,
Exposure is performed sequentially at one focus position by a step-and-repeat method. At this time, the yawing amount of the wafer stage 26 is measured and stored during the exposure of each chip area.
Then, the height of the Z stage 26z is changed, or the wavelength of the excimer laser light is shifted, and the like, and exposure is sequentially performed at the second focal point position in the same manner from the first chip area by the step-and-repeat method. At this time, the yawing amount when stepping each chip area is compared with the previously stored yawing amount at the time of exposing the chip area, and if there is no deviation within an allowable value, the exposure is performed as it is. If the comparison result shows a large difference, the rotation is corrected by the θ table that holds the wafer W and rotates slightly, or the rotation is corrected by rotating the θ table that holds the reticle.

At this time, the positional deviation between the reticle in the x and y directions and the chip region may be monitored in real time (correction of positional deviation) while being monitored by the alignment system 12 in a die-by-die manner. That, x, y direction of the alignment error, the mark WM ₁ ~WM ₄ accompanying the chip area, while detecting the reticle mark RM ₁ ~RM _4, the reticle stage 6 or so that the alignment error is zero, the wafer The stage 26 is kept under servo control, and at the same time, the rotation of the reticle or wafer is corrected based on the yawing measurement value from the working interferometer.

In such a sequence, the alignment time for each chip region is shortened, and a decrease in overlay accuracy due to errors in chip rotation and wafer rotation can be ignored.

Also, since the yawing amount of the wafer stage is stored, even when the multifocal exposure method is used from the time of the first layer exposure (first print), the accuracy of the overlay exposure using the disassembled reticle does not decrease at all.

As described above, in this embodiment, the focal position is not changed every time each chip area is exposed, but only when the first exposure for one wafer is completed.
An improvement in throughput can be expected.

Although the embodiments of the present invention have been described above, each of the decomposed patterns necessarily has a different image intensity because the pattern shape is different. Therefore, the appropriate exposure amount may differ for each of the separated pattern sheets. Therefore, for each of the decomposed patterns, the transmittance or the like of the pattern area of the reticle may be measured to determine an appropriate exposure amount for each decomposed pattern. Also, reducing the numerical aperture of the imaging light beam during equal exposure is useful for increasing the depth of focus. The numerical aperture of the imaging light beam is adjusted by providing a variable aperture stop plate on the pupil EP of the projection lens, and changing the size of the secondary light source image in the illumination optical system using a stop or a doubling optical system. it can. Further, the light beam passing through the pupil EP may be limited to a ring shape (ring zone shape) by an aperture as shown in FIG. Alternatively, the secondary light source image may be formed in a ring shape whose diameter and width are variable or switchable.

〔The invention's effect〕

As described above, the method can be applied to a pattern to which the multifocal exposure method has conventionally been difficult. Also, because the pattern can reduce the spatial frequency,
Even when the focus position is not changed, a finer pattern can be formed.

Further, by increasing the number of multiple exposures by changing the wavelength by excimer exposure or the like, the choice of a method of expanding the depth of focus is widened.

These are powerful methods for solving the physical limit of how to increase the depth of focus in lithography of 0.5 μm or less using light.

Furthermore, in recent years, a technique for dividing a reticle into a reticle has been developed in which a sub space mark is added to each pattern, and it is difficult to put a sub space mark together with the present pattern in the same reticle in terms of space. Also.

[Effects of the Invention] As described above, according to the present invention, the first pattern and the second pattern
When sequentially exposing the pattern and the same sensitive layer on the substrate,
Each of the first pattern and the second pattern can be exposed with good resolving power while suppressing the influence of the projections and depressions on the substrate surface.

[Brief description of the drawings]

FIG. 1 is a diagram schematically showing the method of the present invention, and FIGS. 2 (A) and 2 (B) are diagrams showing a state of generation of diffracted light from a line-and-space pattern and a thinning pattern. FIG. 2C is a graph showing a simulation result of an image intensity distribution in the case of a line and space pattern;
2 (D) and 2 (E) are graphs showing a simulation of the image intensity distribution in the case of the thinning pattern, and FIG. 2 (F).
2 is a graph showing simulation results obtained by superimposing the image intensities of FIGS. 2 (D) and 2 (E), FIG. 3 is a perspective view showing a configuration of a stepper suitable for carrying out the present invention, and FIG. 4 is a projection of the stepper. FIG. 5 is a diagram showing a state of image formation in the optical system, FIG.
FIG. 6, FIG. 7, FIG. 7, and FIG. 8 are diagrams illustrating the turn decomposition method of the method of the present invention. FIG. 9 is a flowchart illustrating one exposure procedure using the method of the present invention. Ten
FIG. 7 is a diagram for explaining a pattern decomposition method according to a second embodiment;
FIG. 11 is a view for explaining the pattern forming method according to the third embodiment, FIG. 12 is a view for explaining the pattern decomposition method according to the fourth embodiment, and FIG. 13 is a view for explaining the exposure method according to the fifth embodiment. FIG. 14 is a plan view showing an annular filter for adjusting the numerical aperture of an image forming light beam. [Explanation of Signs of Main Parts] R, R ₁ , R ₂ , R ₃ , R ₄ … reticle, W… wafer, CP… shot area, PA, PB… whole pattern, PTA ₁ , PTA ₂ , PTA ₃ … PA disassembly pattern, PTB ₁ , PTB ₂ , PTB ₃ … PB disassembly pattern, 2… Light source section, 4… Illumination optical system, 6… Reticle stage, 16… Projection lens, 18 .... Image formation correction mechanism.

 ──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-63-58825 (JP, A) JP-A-59-222840 (JP, A) JP-A-61-226924 (JP, A) JP-A-62 198863 (JP, A)

Claims (24)

(57) [Claims] An exposure method for exposing a desired overall pattern to a sensitive layer by sequentially exposing a first pattern and a second pattern to the same sensitive layer on a sensitive substrate, wherein the overall pattern is The first pattern is exposed such that one of the first pattern and the second pattern is exposed to a convex portion of the substrate surface, and the other is exposed to a concave portion of the substrate surface.
An exposure method, wherein the exposure method is separated into a pattern and the second pattern. 2. An exposure method for exposing the first pattern and the second pattern onto the sensitive substrate via a projection optical system, wherein a difference in height between a convex portion and a concave portion on the substrate surface is: 2. The exposure method according to claim 1, wherein the depth is larger than the depth of focus of the projection optical system. 3. An exposure method for exposing the first pattern and the second pattern onto the sensitive substrate via a projection optical system, wherein the first pattern is exposed and the second pattern is exposed. 2. The exposure method according to claim 1, wherein the position of the substrate in the optical axis direction of the projection optical system is different from time to time. 4. An exposure method for exposing the first pattern and the second pattern onto the sensitive substrate via a projection optical system, wherein the projection is performed during exposure of each of the first pattern and the second pattern. 2. The exposure method according to claim 1, wherein the substrate is relatively displaced with respect to a pattern image forming surface of the projection optical system with respect to an optical axis direction of the optical system. 5. The apparatus according to claim 4, wherein the relative displacement between the pattern image plane and the substrate in the optical axis direction of the projection optical system is performed by changing the wavelength of the energy ray. Exposure method. 6. The first pattern and the second pattern are provided on corresponding first and second masks, respectively, and the first and second masks are sequentially positioned at predetermined positions to perform exposure. Claim 1, characterized in that:
3. The exposure method according to any one of items 3 and 4. 7. The apparatus according to claim 6, wherein the first mask and the second mask are mounted on the same mask stage, and each of the first mask and the second mask is sequentially positioned at a predetermined position. Exposure method according to the above. 8. An exposure method for exposing the entire pattern to each of a plurality of chip regions on the sensitive substrate, the method comprising: exposing the first pattern to each of the chip regions; The exposure method according to claim 1, wherein each of the chip regions is exposed. 9. The exposure method according to claim 1, wherein the exposure amount for the sensitive substrate is different between when exposing the first pattern and when exposing the second pattern.
The exposure method according to any one of the above. 10. An exposure method for forming a predetermined pattern on a sensitive layer by sequentially exposing a first pattern and a second pattern to the same sensitive layer on a sensitive substrate via a projection optical system, When the convex portion of the sensitive layer on the substrate is exposed using one of the first pattern and the second pattern and the concave portion of the sensitive layer on the substrate is exposed using the other, the one pattern is exposed. An exposure method, wherein a relative positional relationship between a pattern imaging surface of the projection optical system and the sensitive substrate is changed between the used exposure and the exposure using the other pattern. 11. When the first pattern is exposed to a sensitive layer on the substrate through a projection optical system, the first pattern is irradiated with an energy beam, and a pattern image plane formed by the projection optical system is formed. 2. The apparatus according to claim 1, wherein the substrate and the projection optical system are relatively displaced in an optical axis direction of the projection optical system.
The method according to 10. 12. When the second pattern is exposed to a sensitive layer on the substrate via a projection optical system, the second pattern is irradiated with energy rays, and the pattern image forming surface and the substrate are connected to each other. 11. The method according to claim 10, wherein the projection optical system is relatively displaced in an optical axis direction. 13. An exposure method for forming the predetermined pattern on each of a plurality of chip regions on the sensitive substrate, the method comprising: exposing the first pattern to each of the chip regions; 11. The method according to claim 10, wherein each of the chip areas is exposed. 14. The method according to claim 1, wherein an exposure amount for the sensitive layer of the sensitive substrate is different between when exposing the first pattern and when exposing the second pattern.
The method according to 10. 15. The method according to claim 10, wherein the first pattern is illuminated with illumination light from a predetermined illumination system, and a secondary light source formed in the illumination system is limited to an annular shape. The described method. 16. The method according to claim 10, wherein the second pattern is illuminated with illumination light from a predetermined illumination system, and a secondary light source formed in the illumination system is limited to an annular shape. The described method. 17. The method according to claim 15, wherein the ring-shaped secondary light source is variable or switchable in diameter and width.
Or the method of 16. 18. An image forming light beam applied to a sensitive layer on the substrate via a projection optical system when exposing the first pattern to the sensitive layer on the sensitive substrate is a pupil plane of the projection optical system. 11. The method according to claim 10, wherein the method is limited by an optical member provided in the apparatus. 19. An image forming light beam applied to a sensitive layer on the substrate via a projection optical system when exposing the sensitive pattern on the substrate to the second pattern, is projected onto a pupil plane of the projection optical system. 11. The method according to claim 10, wherein the method is limited by an optical member provided. 20. The optical device according to claim 18, wherein the optical member restricts a light beam passing through the projection optical system into an annular shape.
Or the method according to 19. 21. The apparatus according to claim 10, wherein the first pattern includes a main pattern formed by the projection optical system and an auxiliary pattern provided to assist exposure of the main pattern. The method described in. 22. The apparatus according to claim 10, wherein the second pattern includes a main pattern formed by the projection optical system and an auxiliary pattern provided to assist exposure of the main pattern. The method described in. 23. The first pattern and the second pattern are provided on corresponding first and second masks, respectively, and the first and second masks are sequentially positioned at predetermined positions to perform exposure. 11. The method according to claim 10, wherein: 24. The method according to claim 23, wherein the first mask and the second mask are mounted on a same support.