JPH0794387A - Aligner - Google Patents

Abstract

PURPOSE:To enable the edge parts in scanning direction of a slit-shaped lighting region to be fully in parallel at the same time only the pattern at a desired pattern region within a plurality of pattern regions on reticle to be transferred onto a light sensitive substrate in a step-and-scan system aligner. CONSTITUTION:A reticle R is scanned in -X direction for a slit-shaped lighting region 21 which is formed by a fixed visual field diaphragm to exposing only a circuit pattern 20A which is sandwiched by light-shielding parts 20C and 20D within two circuit pattern regions on the reticle R. When scanning exposure is started. a blade 7A of a movable blind is moved while it is overlapped to the light-shielding part 20D of the reticle R and a blade 7B is moved while it is overlapped to the light-shielding part 20C when scanning exposure is completed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a so-called step in which a pattern on a mask is successively exposed on a photosensitive substrate by synchronously scanning the mask and the photosensitive substrate with respect to an illumination area having, for example, a rectangular shape or an arc shape.・ The present invention relates to an exposure apparatus of the and scan type.

[0002]

2. Description of the Related Art Conventionally, when a semiconductor element, a liquid crystal display element, a thin film magnetic head or the like is manufactured by using a photolithography technique, a photomask or a reticle (hereinafter, referred to as
A projection exposure apparatus is used to expose a pattern (collectively referred to as “reticle”) via a projection optical system onto a photosensitive substrate such as a wafer or a glass plate coated with a photoresist or the like. Recently, the size of one chip pattern of a semiconductor element tends to be large, and a projection exposure apparatus is required to have a large area for exposing a pattern having a larger area on a reticle onto a photosensitive substrate.

In order to respond to such a large area, after stepping each shot area on the photosensitive substrate to the initial position,
For example, by scanning the reticle and the photosensitive substrate in synchronization with a rectangular, arcuate, or hexagonal illumination area (this is called a "slit-shaped illumination area"), the slit-shaped illumination area on the reticle is A so-called step-and-step method of sequentially exposing a large area pattern to each shot area
A scanning type projection exposure apparatus has been developed. Conventionally, in order to set the slit-shaped illumination area on the reticle, a movable light-shielding unit that determines the slit-shaped illumination area is arranged at a position substantially conjugate with the reticle or in the vicinity of the reticle.

[0004]

The above-mentioned conventional techniques have the following two major inconveniences.
Generally, the illumination optical system of the projection exposure apparatus is designed to illuminate the reticle with illumination light (exposure light) having a uniform illuminance. Therefore, in the step-and-scan projection exposure apparatus, when the exposure is completed by scanning the reticle and the photosensitive substrate in synchronization with the slit-shaped illumination area, good illuminance is uniform on the photosensitive substrate. The width of the slit-shaped illumination area in the scanning direction must be sufficiently uniform in order to obtain the property.

This will be described with reference to FIGS. 7 to 9. First, when the scanning direction of the reticle with respect to the slit-shaped illumination area is the X direction and the non-scanning direction perpendicular to this scanning direction is the Y direction, when the width of the slit-shaped illumination area in the scanning direction is not uniform, When the parallelism in the scanning direction of the slit-shaped illumination area 30 is poor as shown in FIG. 7A, and when the slit-shaped illumination area 3 is shown as shown in FIG. 8A.
There is a case where the edge portion in the scanning direction of 1 has unevenness. In the case of FIG. 7A, the non-scanning direction (Y
The exposure amount distribution E (Y) in the (direction) gradually increases or decreases in the Y direction as shown in FIG. 7B.
On the other hand, the exposure amount distribution E (Y) in the non-scanning direction (Y direction) obtained on the photosensitive substrate in the case of FIG. 8A fluctuates irregularly in the Y direction as shown in FIG. 8B. It will be something like.

In this regard, the present projection exposure apparatus is also used in the sub-half micron region where the design rule is less than 0.5 μm. It is said that the uniformity of the exposure amount required for line width control in such an area reaches ± 1%. Therefore, in order to obtain sufficient illuminance uniformity in the step-and-scan projection exposure apparatus, the unevenness of the edge portion in the scanning direction should be set with respect to the illumination area setting means for determining the slit-shaped illumination area. In addition to being required to be small, it is required to control the movement while keeping the edge portions in the scanning direction sufficiently parallel when changing the width in the scanning direction. Therefore, if the illumination area setting means for determining the slit-shaped illumination area is variably controlled in synchronization with scanning, it is difficult to control the operation of the illumination area setting means while maintaining the required accuracy. Is,
Alternatively, there is the first inconvenience that the variable mechanism becomes very complicated.

Further, as shown in FIG.
When the reticle R is scanned with respect to the slit-shaped illumination area 33 having a width L2 in the scanning direction, assuming that two circuit pattern areas 32A and 32B are formed side by side in the scanning direction with a light-shielding portion having a width L1. think of. Also,
It is assumed that the width L2 of the slit-shaped illumination area 33 is larger than the width L1 of the light shielding portion that separates the circuit pattern areas 32A and 32B. In this case, for example, if it is attempted to expose only the pattern of the first circuit pattern area 32A of the reticle R onto the photosensitive substrate by the scanning method, the second circuit pattern area 32 will be exposed.
There is a second disadvantage that part of the pattern B is also transferred onto the photosensitive substrate. To avoid this,
The width L1 of the light-shielding portion on the reticle R may be made sufficiently large, but this reduces the area of the circuit pattern area for transfer.

In view of the above problems, the present invention is a step-and-step method capable of sequentially exposing a pattern on a reticle onto a photosensitive substrate by scanning the reticle and the photosensitive substrate in synchronization with a slit-shaped illumination area. In a scanning type exposure apparatus, by maintaining the edges of the slit-shaped illumination area in the scanning direction sufficiently parallel, sufficient illuminance uniformity can be maintained after scanning, and a desired pattern area in a plurality of pattern areas on the reticle can be maintained. It is an object of the present invention to be able to transfer only the pattern of 1 to the photosensitive substrate.

[0009]

An exposure apparatus according to the present invention exposes a slit-shaped illumination area (21) on a mask (R) on which a transfer pattern is formed, as shown in FIGS. 1 and 2, for example. An illumination optical system (1 that illuminates the substrate (W) side
˜4, 8) and relative scanning means (10, 12, 15) for synchronously scanning the mask (R) and the photosensitive substrate (W) with respect to the slit-shaped illumination area. The pattern on the mask (R) is successively exposed on the photosensitive substrate (W) by scanning the mask (R) and the photosensitive substrate (W) in synchronization with the slit-shaped illumination area by the scanning means. In the exposure apparatus, a surface of the mask (R) in the vicinity of the pattern forming surface, and a conjugate surface (R
P) and the width of the slit-shaped illumination area (21) on the mask (R) in the scanning direction, which is arranged on the first mounting surface of the mounting surface group consisting of the surface near the conjugate surface. A fixed field stop (5) for

Further, according to the present invention, a slit-shaped illumination area (2) on the mask (R) is arranged on a second mounting surface of the mounting surface group which is different from the first mounting surface.
1) is provided with a movable field stop (7) for setting a variable exposure area to be actually exposed on the photosensitive substrate (W),
The movable field stop has front and rear edge portions (7Ae, 7B) with respect to the scanning direction of the variable exposure area.
e) a first blade (7A) and a second blade (7)
B), the first blade (7A) of the movable field stop (7) is driven at the start of the exposure of the pattern of the mask (R) to move the variable exposure area to the front side in the scanning direction. The edge part (7Ae) is moved in synchronization with the slit-shaped illumination area (21) in the scanning direction, and at the end of the exposure of the pattern of the mask (R), the second blade () of the movable field stop (7) ( 7B) is driven to move the rear edge portion (7Be) of the variable exposure region with respect to the scanning direction in synchronization with the slit-shaped illumination region (21) in the scanning direction.

Further, the second exposure apparatus of the present invention is, for example, as shown in FIGS. 1 and 2, a light source (1) for generating illumination light and a mask on which a transfer pattern is formed by the illumination light. The illumination optical system (2 to 4, 5) for illuminating the slit-shaped illumination area (21) on (R) and the pattern image of the mask (R) in the slit-shaped illumination area (21) are provided on the photosensitive substrate (W). ) A relative scanning means (10, 1) for synchronously scanning the mask (R) and the photosensitive substrate (W) with respect to the projection optical system (13) for forming an image on the slit illumination area (21).
2, 15) and the relative scanning means scans the slit-shaped illumination area (21) with the mask (R) and the photosensitive substrate (W) in synchronization with each other, thereby the mask (R).
In an exposure apparatus that sequentially exposes the above pattern image onto a photosensitive substrate (W), a first defocused amount Δz from the conjugate plane (RP) of the pattern forming surface of the mask (R) in the optical axis direction of the illumination optical system. It has a fixed field stop (5) for setting the width in the scanning direction of the slit-shaped illumination area (21) on the mask (R), which is arranged on the mounting surface of No. 1.

Further, according to the present invention, a slit-shaped illumination area (2) on the mask (R) is arranged on the second mounting surface which substantially coincides with the conjugate surface of the pattern forming surface of the mask (R).
1) is provided with a movable field stop (7) for setting a variable exposure area to be actually exposed on the photosensitive substrate (W), and is provided on the photosensitive substrate (W) side of the projection optical system (13). The numerical aperture is NA _W and the coherence of the illumination light from the illumination optical system
The factor is σ, the projection magnification of the projection optical system (13) from the mask (R) to the photosensitive substrate (W) side is M _RW , and the pattern formation of the mask (R) near the fixed field stop (5) arrangement surface. The projection magnification from the surface conjugate with the surface to the pattern forming surface is M _BR , and the allowable minimum value of the blur radius on the photosensitive substrate (W) of the light emitted from one point on the arrangement surface of the fixed field stop (5) Is ΔD _min , the defocus amount Δz of the first mounting surface satisfies the following condition.

[0013]

[Expression 1] | Δz | ≧ ΔD _min / [M _BR · M _RW · tan {arcsin (M _BR · M _RW · NA _W · σ)}] In this case, the light source (1) is a pulsed light source. desirable.

[0014]

In the first exposure apparatus of the present invention, since the field stop (5) that determines the width of the slit-shaped illumination area (21) in the scanning direction is fixed, the edge portion in the scanning direction is fixed. Can be precisely manufactured or adjusted so that the two are sufficiently parallel. In addition, a movable field stop (7) having a first blade (7A) and a second blade (7B) for determining a variable exposure area that may be rougher in shape accuracy than the illumination area (21) is provided. Has been. Therefore, for example, as shown in FIG. 2, a plurality of pattern regions (20
When only the pattern of the pattern area (20A) in (A, 20B) is transferred onto the photosensitive substrate (W), the first blade (7A) is driven at the start of exposure to scan the variable exposure area. The edge portion (7Ae) on the front side with respect to the direction is moved in the scanning direction with respect to the illumination area (21), and at the end of the exposure, the second blade (7B) is driven so that The edge portion (7Be) is moved in the scanning direction with respect to the illumination area (21).

As a result, the desired pattern area (2
Only the pattern 0A) is exposed on the photosensitive substrate (W). In this case, the first blade (7A) and the second blade (7A)
The distance from B) may be slightly larger than the width of the region conjugate with the illumination region (21) at the maximum, and the blades (7A, 7A)
Since the moving stroke of B) may be slightly larger than the width of the region conjugate with the illumination region (21), the movable field stop (7) is small. Further, the width L1 of the light shielding part (20C) between the pattern areas (20A, 20B) in FIG. 2 can be made smaller than the width L2 in the scanning direction of the slit-shaped illumination area (21), and the circuit pattern for transfer is formed. The area of the region can be wide. Also, fixed field diaphragm (5)
Can be arranged so as to be displaced from the conjugate plane of the pattern forming surface of the mask (R). Therefore, a movable field stop (7) for determining an actual variable exposure area is provided, for example, on the pattern forming surface of the mask (R). It is possible to achieve both in terms of space even when it is arranged on a plane substantially conjugate with.

By the way, when the exposure light source is a pulse oscillation type such as an excimer laser, the applicant of the present invention filed Japanese Patent Application No. 5-2.
As disclosed in No. 11246 and as shown in FIG. 6B, a slope portion having a predetermined width or more is formed at the edge portion of the illumination distribution E (X) in the scanning direction of the slit-shaped illumination area (21). This is necessary for exposure amount control and illuminance uniformity control. Since the fixed field stop (5) according to the present invention is arranged so as to be displaced from the surface (RP) conjugate with the pattern forming surface of the mask (R) by Δz satisfying the condition of (Equation 1),
The illuminance distribution E (X) in the scanning direction of the slit-shaped illumination region (21) becomes trapezoidal or triangular due to the blur of the projected image, and a slope portion is automatically formed at the edge portion of the illuminance distribution in the scanning direction.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of an exposure apparatus according to the present invention will be described below with reference to FIGS. In this embodiment, the present invention is applied to a step-and-scan type projection exposure apparatus. FIG. 1 shows a projection exposure apparatus of this embodiment. In FIG. 1, the reticle R is a pulse light source 1,
The rectangular slit-shaped illumination area 21 is illuminated by the beam shaping optical system 2 and the illumination optical system including the relay lens 8 with a uniform illuminance, and the circuit pattern image of the reticle R in the slit-shaped illumination area 21 is projected onto the projection optical system. It is transferred onto the wafer W via 13. As the pulse light source 1, an excimer laser light source such as an ArF excimer laser or a KrF excimer laser, a metal vapor laser light source, or a YAG laser harmonic generator is used.

In FIG. 1, the pulse illumination light from the pulse light source 1 reaches the fly-eye lens 3 with its beam diameter enlarged by a beam shaping optical system 2 including a cylindrical lens and a beam expander. Fly eye lens 3
A large number of secondary light sources are formed on the exit surface of the, and the pulsed illumination light from these secondary light sources is condensed by the condenser lens 4, passes through the fixed field stop 5, and the movable blind 7
Reach Although the field stop 5 is arranged on the condenser lens 5 side of the movable blind 7 in FIG. 1, it may be arranged on the opposite side of the relay lens system 8 side.

A rectangular slit-shaped opening is formed in the field stop 5, and the light flux that has passed through the field stop 5 becomes a light flux having a rectangular slit-shaped cross section and enters the relay lens system 8. The relay lens system 8 is a lens system that makes the movable blind 7 and the pattern forming surface of the reticle R conjugate with each other, and the movable blind 7 has two blades (light shielding plate) that define the width in the scanning direction (X direction) described later. 7A, 7B and two blades (not shown) that define the width in the direction perpendicular to the scanning direction. The blades 7A and 7B that define the width in the scanning direction are supported by the driving units 6A and 6B so as to be independently movable in the scanning direction. In the present embodiment, the pulsed illumination light is irradiated only within the slit-shaped illumination area 21 on the reticle R set by the fixed field stop 5, and further within the desired exposure area set by the movable blind 7. The relay lens system 8 is an optical system that is telecentric on both sides, and the slit-shaped illumination area 21 on the reticle R maintains the telecentricity.

The reticle R of this example is placed on the reticle stage 9, and the image of the circuit pattern defined by the movable blind 7 in the slit-shaped illumination area 21 on the reticle R is projected onto the projection optical system. Wafer W through 13
It is projected onto and exposed. An area on the wafer W that is conjugate with the slit-shaped illumination area 21 is defined as a slit-shaped exposure area 22. Further, in the two-dimensional plane perpendicular to the optical axis of the projection optical system 13, the scanning direction of the reticle R with respect to the slit-shaped illumination area 21 is defined as the X direction (or −X direction), and the projection optical system 1
The direction parallel to the optical axis of 3 is the Z direction.

In this case, the reticle stage 9 is driven by the reticle stage driving unit 10 to scan the reticle R in the scanning direction (X direction or −X direction), and the driving units 6A and 6B of the movable blind 7 operate as the movable blind. It is controlled by the control unit 11. The main control system 12 that controls the operation of the entire apparatus controls the operations of the reticle stage drive unit 10 and the movable blind control unit 11. On the other hand, the wafer W
Is placed on the wafer stage 14 and the wafer stage 14
Is an XY that positions the wafer W in a plane perpendicular to the optical axis of the projection optical system 13 and scans the wafer W in the ± X directions.
The stage includes a Z stage for positioning the wafer W in the Z direction, and the like. The main control system 12 controls the positioning operation and the scanning operation of the wafer stage 14 via the wafer stage drive unit 15.

When the pattern image on the reticle R is exposed to each shot area on the wafer W by the scanning method through the projection optical system 13, the slit-shaped illumination area 21 set by the field stop 5 is exposed. On the other hand, in the X direction (or -X
Direction), the reticle R is scanned via the reticle stage 9. Further, in synchronization with this scanning, the slit-shaped illumination area 21 and the slit-shaped exposure area 22 which is conjugate with
The wafer W is scanned in the X direction (or the X direction) via the wafer stage 14. That is, the −X direction (or X direction) is the scanning direction of the wafer W. By synchronously scanning the reticle R and the wafer W in this manner, the circuit pattern image of the reticle R is sequentially transferred to each shot area on the wafer W.

In recent years, a plurality of circuit pattern areas are provided on the reticle R in order to shorten the time required for reticle exchange and improve the throughput. Then, the movable blind 7 is used to select a circuit pattern area to be transferred from a plurality of circuit pattern areas on the reticle R. Therefore, the projection exposure apparatus of the present embodiment is provided with an input unit 16 for inputting information on the circuit pattern area on the reticle R and a memory unit 17 for storing the circuit pattern information from the input unit 16. The control system 12 controls the blades 7 of the movable blind 7 via the movable blind control unit 11 and the driving units 6A and 6B based on the circuit pattern information of the memory unit 17.
A and 7B are driven in a predetermined sequence.

Now, FIG. 1 shows an example of the operation when performing exposure by the step-and-scan method in this embodiment.
2 and FIG. 2. At this time, as shown in FIG. 2A, two circuit pattern areas 2 are formed on the reticle R.
0A and 20B are formed, and these circuit pattern areas 2
A light-shielding portion (light-shielding band) 20C having a width L1 in the scanning direction is formed at the boundary between 0A and 20B, and the circuit pattern region 20
It is assumed that light-shielding portions 20D and 20E having the same width L1 are formed on the outer sides of A and 20B in the scanning direction, respectively. Further, as shown in FIG. 2A, the slit-shaped illumination area 21 formed on the reticle R of this example is an elongated rectangular shape having a width L2 in the scanning direction, and the light shielding portions 20C, 20D, 2 are provided.
The width L1 of 0E is set narrower than the width L2 of the illumination area 21.

At this time, first, the operator inputs information regarding the circuit pattern areas 20A and 20B on the reticle R into the memory section 17 via the input section 16 of FIG.
When the pattern image in the first circuit pattern area 20A is transferred onto the wafer W via the projection optical system 13, the main control system 12 uses the first pattern in the circuit pattern information stored in the memory unit 17. The information about the circuit pattern area 20A is read out, and the positions of the blades 7A and 7B of the movable blind 7 in the scanning direction are controlled via the movable blind controller 11 based on this information. As a result, FIG.
As shown in (f), the second circuit pattern area 20B on the reticle R is always covered with the other blade 7B, and only the first circuit pattern area 20A is irradiated with the illumination light of the slit-shaped illumination area 21. To do so. However, in FIG.
The blade 7A of the movable blind 7 is actually on the reticle R.
And 7B images are projected, which are considered as vanes 7A and 7B, respectively.

More specifically, the main control system 1 shown in FIG.
2 drives the reticle stage 9 via the reticle stage drive unit 10 to generate the circuit pattern area 2 on the reticle R.
After arranging the slit-shaped illumination area 21 on the left side of 0A, as shown in FIG. 2B, the blades 7A and 7B are closed, and the boundary portion of these blades 7A and 7B is overlapped on the light shielding portion 20D. To position. Next, the reticle stage 9 and the drive unit 6A in FIG. 1 are driven to move the reticle R and the blade 7A in the −X direction (scanning direction) in synchronization as shown in FIG. 2C. As can be seen from FIG. 1, the blade 7A actually moves in the X direction, but since the projected image is handled in FIG. 2, the scanning direction of the blades 7A and 7B is the same as the scanning direction of the reticle R. Is. In addition, the illumination area 21
The wafer W is exposed with a pattern in a variable exposure area sandwiched between the right edge portion 7Ae of the left blade 7A and the left edge portion 7Be of the right blade 7B.

As shown in FIG. 2D, when the right edge portion 7Ae of the blade 7A exceeds the left end of the illumination area 21, the blade 7A starts decelerating. In parallel with this operation, the blade 7
After the light-shielding portion 20C overlaps the left edge portion 7Be of B, the blade 7B is scanned in the -X direction in synchronization with the reticle R, as shown in FIG. Then, as shown in FIG. 2F, when the pattern area 20A passes through the illumination area 21 and the exposure is completed, deceleration of the reticle R and the blade 7B is started, and finally, when the reticle R is stationary. ,
The vanes 7A and 7B stand still on the light shield 20C in a closed manner.

On the other hand, in synchronization with the operation of the reticle R and the movable blind 7, the main control system 12 drives the wafer stage 14 via the wafer stage drive section 15 to drive the wafer W.
Are scanned in the scanning direction (X direction). Assuming that the projection magnification of the projection optical system 13 from the reticle R to the wafer W is M _RW , the reticle R moves at a velocity V in the −X direction (or the X direction) during exposure.
_In synchronism with the scanning at _R0 , the wafer W is scanned at a speed V _W0 (= M _RW · V _R0 ) in the X direction (or −X direction).
In this case, the first circuit pattern area 20 on the reticle R
Since only A is irradiated with the pulsed illumination light, only the pattern image of the first circuit pattern area 20A is transferred onto the wafer W. It should be noted that the reticle R is moved to the illumination area 21 by X
When scanning in the direction, the blades 7 of the movable blind 7
A and 7B are controlled in the order of FIG. 2 (f) to FIG. 2 (b).

Now, the relationship between the operating speeds of the reticle R and the blades 7A and 7B shown in FIG. 2 will be described with reference to FIG. The speed V _{R of the} reticle R, the speed V _{7A of} the blade _7A , and the speed V _{7B of the} blade 7B are shown in FIGS. 3 (a), (b), and (c), respectively. First, corresponding to the states of FIGS. 2B to 2C, the reticle R and the blade 7A move synchronously as shown in the period T ₁ of FIG. 3, and the velocity of the reticle R after the settling period T _SE. Exposure is performed during the period T ₂ when V _R is stable. Then, corresponding to the states of FIG. 2 (e) to (f),
As shown by a period T ₃ in FIG. 3, the reticle R and the blade 7B operate in synchronization until they stop. During this period T ₃ or the period in which the reticle R is stopped, the wafer W in FIG. 1 is stepped in the Y direction, and the shot area to be exposed next is positioned immediately before the exposure area 22.

Then, corresponding to the states of FIGS. 2 (f) to (e), the reticle R and the blade 7B move synchronously in the period T ₄ of FIG. 3, and the speed of the reticle R after the settling period T _SE. V _R
Exposure is performed during a period T ₅ during which the temperature is stable. Then, corresponding to the states of FIGS. 2C to 2B, the period T _{6 of} FIG.
As shown by, the reticle R and the blade 7A operate in synchronization until they stop. After that, this operation is repeated. Further, in FIG. 3, the speed V _7B of the vane 7B in the period T ₁ and T ₆ need only control roughened degree entering nearly 3 hatched portions 24A and the 24B in (c), the period T ₃ and T
The velocity V _7A of the blade 7A at ₄ need only be roughly controlled so as to fall within the shaded portions 23A and 23B of FIG. 3B. Therefore, it is easy to control the blades 7A and 7B.

When the pattern of the second circuit pattern area 20B on the reticle R of FIG. 2A is transferred onto the wafer W, the main control system 12 stores the input information stored in the memory section 17. Information regarding the second circuit pattern area 20B in the inside is read out, and the positions of the blades 7A and 7B in the scanning direction are controlled via the movable blind control unit 11 based on this information. That is, based on the same idea as in FIG. 2, the blade 7A is caused to follow the light shielding portion 20C at the start of exposure, and the blade 7B is made to follow the light shielding portion 20E at the end of exposure.
The circuit pattern area 20A is covered with the blade 7A, and only the second circuit pattern area 20B is illuminated with the illumination light of the slit-shaped illumination area 21. As a result, only the pattern image of the circuit pattern area 20B is transferred onto the wafer W.

As described above, according to the present embodiment, the blades 7A and 7B forming the movable blind 7 shield the area other than the circuit pattern area to be exposed from light, so that the reticle R has a narrow interval in the scanning direction. Even when a plurality of circuit pattern regions are formed, there is an advantage that only the pattern of the desired circuit pattern region among them can be exposed on the wafer W. Therefore, it is possible to form a plurality of circuit pattern regions on the reticle R with a narrow interval and high density. Furthermore, FIG.
As can be seen from the above, the maximum value of the distance between the vanes 7A and 7B may be slightly larger than the width of the region conjugate with the illumination region 21, and the moving stroke of the vanes 7A and 7B also has the width of the region conjugate with the illumination region. Since it only needs to exceed
The shape of the movable blind 7 is small.

Next, with reference to FIGS. 1 and 4, another example of the operation when performing exposure by the step-and-scan method will be described. Also in this example, the reticle R to be exposed includes two circuit pattern regions 20A and 20B as shown in FIG. 4A, as in the reticle R of FIG. The method of controlling the blades 7A and 7B is different from that in the case of FIG. In this example, before the exposure is started, as shown in FIGS.
The edge portions of A and 7B (actually, these projected images) are set in the light shielding portions 20D and 20C, respectively, and then the reticle stage 9 is driven to drive the reticle R and the blades 7A and 7C.
B is moved in synchronization with the -X direction which is the scanning direction. Further, in synchronization with this, the wafer W is moved in the scanning direction (X direction).

In this case as well, only the first circuit pattern area 20A on the reticle R is irradiated with the pulsed illumination light, so that only the pattern image of the first circuit pattern area 20A is transferred onto the wafer W. . When scanning in the reverse direction, the blades 7A and 7B of the movable blind 7 are moved to the positions shown in FIG.
The scanning is performed in the order of (f) to (b). The control method shown in FIG. 4 has an advantage that the acceleration / deceleration control of the blades 7A and 7B may be the same, but the interval between the blades 7A and 7B needs to be equal to or larger than the width of the circuit pattern region 20A, and the blade 7A is Also, the moving stroke lengths of 7B and 7B become long, and the movable blind 7 becomes large. The control accuracy of the position of the movable blind 7 shown in FIG. 2 and FIG.
It may be within the width L1 of 0D and 20E, and may be rougher than the control accuracy of the position of the reticle R.

2 and 4, the blades (light-shielding plates) in the Y direction (non-scanning direction), which is the vertical direction of the paper surface of FIGS. 2 and 4 orthogonal to the scanning direction (X direction), are not shown. However, it goes without saying that the opening formed by the blade in the non-scanning direction may be fixed during the scanning exposure. In addition, the edge portion of the cross-sectional shape of the illuminance distribution in the non-scanning direction of the slit-shaped illumination area 21 is also the field stop 5 as in the scanning direction.
Has a slope portion due to deviation from the conjugate position with the reticle R, and its cross-sectional shape is trapezoidal (since there is a sufficient length in the non-scanning direction, it is not blurred until it becomes a triangular shape). To). For this reason, it is desirable that the exposure area on the reticle R sandwiched by the light-shielding portions in the non-scanning direction is set in the slit-shaped illumination area 21 where the illuminance distribution is flat in the non-scanning direction. This is because the edge slope portion in the scanning direction is integrated by scanning exposure and does not contribute to the illuminance uniformity, but the edge slope portion in the non-scanning direction contributes to the illuminance uniformity as it is.

In this case, the shape of the substantially slit-shaped illumination area 21 on the reticle R is the field stop 5 in the scanning direction.
Therefore, the non-scanning direction is defined by the movable blind 7, respectively. The movable blind 7 of FIG.
Is configured to be able to independently drive a total of four blades, two in the scanning direction and two in the non-scanning direction, but the movable blind 7 has two L-shaped blades in the X direction and the Y direction. It may be configured so that it can be driven independently in each direction. Further, in FIGS. 2 and 4, the width L2 of the slit-shaped illumination region 21 is
Is assumed to be larger than the width L1 of the light shielding portions 20C, 20D, 20E, but the width L of the light shielding portions 20C, 20D, 20E is
If 1 can be made larger than the width L2 plus the movement amount of the reticle R during acceleration or deceleration, the movable blind 7 in the scanning direction may be omitted. In this case, the movable blind 7 is composed only of the non-scanning direction blades.

Next, referring to FIG. 5, the movable blind 7
An example of the operation when is composed of four blades 7A and 7B in the scanning direction and two blades 7C and 7D in the non-scanning direction will be described. In this case, even if a plurality of circuit pattern regions are formed on the reticle R in the non-scanning direction (Y direction), a pattern of only a desired circuit pattern region can be exposed on the wafer W. That is, when, for example, four circuit pattern regions 20F to 20I are formed on the reticle R in the form of being separated in the X direction and the Y direction, 4
By adjusting the positions of the blades 7A to 7D, it is possible to irradiate only one arbitrary circuit pattern area of the four circuit pattern areas 20F to 20I with the illumination light. Then, by scanning the reticle R and the blades 7A to 7D in the X direction with respect to the slit-shaped illumination area 21 by the method of FIG. 2 or 4, the pattern of the selected circuit pattern area on the reticle R is changed. The wafer W is exposed.

Next, in the present embodiment, the surface on which the fixed field stop 5 is arranged in FIG. 1 is displaced in the optical axis direction (Z direction) from the surface RP conjugate with the pattern forming surface of the reticle R. With this displacement amount as Δz, the condition of the displacement amount Δz is obtained with reference to FIG. First, FIG. 6A shows a simplified optical system from the field stop 5 to the wafer W. In FIG. _6A , the projection magnification of the relay lens 8 from the movable blind 7 to the reticle R is M _BR , the reticle R. Therefore, the projection magnification of the projection optical system 13 on the wafer W is M _RW . Further, the numerical aperture on the wafer W side of the projection optical system 13 is NA _W , and coherence indicating the degree of coherence of illumination light from the illumination optical system.
Let the factor be σ.

At this time, the luminous flux angle θ on the arranging surface (conjugate surface RP) of the movable blind 7 of the illumination light focused on one point on the reticle R and the wafer W is as follows.

[0040]

[Mathematical formula-see original document] θ = arcsin (M _BR · M _RW · NA _W · σ) Then, the blurring of the illumination light on the arrangement surface of the fixed field stop 5 which is away from the conjugate plane RP by Δz in the optical axis direction. Radius r
Is as follows.

[0041]

Equation 3] r = Δz · tanθ = Δz · tan {arcsin (M BR · M RW · NA W · σ)} Further, the illumination light emitted from a point arrangement surface of the fixed field stop 5 in the opposite The blur radius ΔD on the exposed surface of the wafer W is expressed as follows.

[0042]

[Formula 4] ΔD = r · M _BR · M _{RW From} (Formula 3) and (Formula 4), the following formula is established.

[0043]

[Equation 5] Δz = ΔD / [M _BR · M _RW · tan {arcsin (M _BR · M _RW · NA _W · σ)}] From (Equation 5), one point on the arrangement surface of the fixed field stop 5 When the allowable minimum value of the radius of blur on the exposed surface of the wafer W formed by the illumination light emitted from is set to ΔD _min , the deviation amount (defocus amount) Δz of the fixed field stop 5 in the optical axis direction is It may be set so as to satisfy the condition.

[0044]

[Equation 6] | Δz | ≧ ΔD _min / [M _BR · M _RW · tan {arcsin (M _BR · M _RW · NA _W · σ)}] Also, the minimum allowable value ΔD of the blur radius in (Equation 6)
_min is determined by variations in exposure energy for each pulse emission of the pulse light source 1 in FIG. In this way, the position of the fixed field stop 5 is changed to the conjugate plane R with the reticle R.
By shifting from P by Δz in the optical axis direction, the scanning direction of the slit-shaped illumination area 21 on the reticle R (X direction).
As shown in FIG. 6B, the illuminance distribution E (X) of the edges has widths ΔL ₁ and ΔL _{2 at} the edge portions in the scanning direction (see FIG.
In the example of (b), it becomes a trapezoid of ΔL ₂ = ΔL ₁ . In this case, the interval between the positions where the value of the illuminance distribution E (X) is 1/2 of the maximum value, that is, the half value width L2 is the width of the slit-shaped illumination area 21 in the scanning direction.

When a continuous light source such as a mercury lamp is used instead of the pulse light source 1, the minimum allowable radius ΔD _min of the blur radius becomes an extremely small value, and the shift amount Δz
Can be almost 0. As described above, in the present embodiment, the shape of the slit-shaped illumination region 21, that is, the shape of the aperture of the field stop 5 has been described as an example of a rectangle, but the shape is not limited to a rectangle, and, for example, Japanese Patent Publication No. 46. Hexagonal illumination area as disclosed in Japanese Patent Publication No. 34057, JP-B-53
No. 25790, a rhombic illumination area as disclosed in Japanese Patent Application Laid-Open No. 25790, or the applicant of the present application, Japanese Patent Application No. 4-242486.
Needless to say, an arc-shaped illumination area as disclosed in Japanese Patent Application No. 4-316717 can be used.

Although the pulse light source 1 is used as the exposure light source in FIG. 1, the present invention can be directly applied to the case where a continuous light source such as a mercury lamp is used as the exposure light source. Further, the projection optical system 13 in the above-mentioned embodiment is
It goes without saying that it may be a refraction system, a reflection system, or a catadioptric system. Further, it goes without saying that the present invention is not limited to the projection exposure apparatus, but can be applied to a contact type or proximity type exposure apparatus. As described above, the present invention is not limited to the above-described embodiments, and various configurations can be taken without departing from the gist of the present invention.

[0047]

According to the first exposure apparatus of the present invention, since the field stop that determines the width of the slit-shaped illumination area in the scanning direction is fixed, the edge portion in the scanning direction of the illumination area is sufficiently parallel. Can be precisely manufactured or adjusted to ensure sufficient illumination uniformity after scanning exposure. Also, the two blades of the movable field stop in the scanning direction are
Since it can be driven independently, the moving stroke of the movable field stop is shortened and the movable field stop is downsized, and even if the width of the light shielding part between different circuit patterns on the mask is narrow, only the desired circuit pattern is obtained. Can be exposed. Therefore, the pattern formation surface of the mask can be effectively utilized.

Also, since the fixed field stop is used also in the second exposure apparatus, it is possible to precisely manufacture or adjust so that the edge portions in the scanning direction of the slit-shaped illumination area are sufficiently parallel. At the same time, the movable field stop allows only the desired circuit pattern to be exposed even when the width of the light-shielding portion between different circuit patterns on the mask is narrow. Further, since the movable field stop mask is arranged almost on the conjugate plane of the pattern formation surface, and the fixed field stop is arranged on the plane deviated by Δz from the conjugate plane, the illuminance in the scanning direction of the slit-shaped illumination area is increased. A predetermined slope can be given to the edge portion of the distribution. Therefore, especially when the exposure light source is a pulsed light source such as an excimer laser, it is convenient for maintaining the illuminance uniformity.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing a projection exposure apparatus according to an embodiment of the present invention.

FIG. 2 is a diagram for explaining an example of a circuit pattern region on a reticle R and an example of a scanning exposure operation in the embodiment.

FIG. 3 is a diagram showing a moving speed relationship between the reticle R and the blades 7A and 7B of the movable blind 7 corresponding to the scanning exposure operation of FIG.

FIG. 4 is a diagram for explaining an example of a circuit pattern region on a reticle R and another example of the scanning exposure operation in the embodiment.

FIG. 5 is a plan view showing a case where the movable blind 7 has four blades.

6A is a schematic diagram of an optical system from a fixed field stop 5 to a wafer W, and FIG. 6B shows an illuminance distribution E (X) in a scanning direction in a slit-shaped illumination area on the reticle R. It is a figure.

FIG. 7 is an explanatory diagram showing an example of a case where the shape accuracy of a slit-shaped illumination region in the scanning direction affects the illuminance uniformity after scanning.

FIG. 8 is an explanatory diagram showing another example of a case where the shape accuracy in the scanning direction of the slit-shaped illumination region affects the illuminance uniformity after scanning.

FIG. 9 is a diagram showing a relationship between a plurality of circuit pattern areas arranged on a reticle and a slit-shaped illumination area.

[Explanation of symbols]

 1 pulse light source 3 fly-eye lens 5 fixed field diaphragm 7 movable blinds 7A, 7B blades 8 relay lens R reticle W wafer 9 reticle stage 10 reticle stage drive unit 11 movable blind control unit 12 main control system 13 projection optical system 14 wafer stage 15 Wafer stage drive unit 16 Input unit 17 Memory unit 21 Slit-shaped illumination area

Claims (3)

[Claims] 1. An illumination optical system for illuminating a slit-shaped illumination region on a mask on which a transfer pattern is formed toward a photosensitive substrate, and the mask and the photosensitive substrate for the slit-shaped illumination region. Relative scanning means for scanning in synchronism, and by sequentially scanning the mask and the photosensitive substrate with respect to the slit-shaped illumination area by the relative scanning means, the pattern on the mask is sequentially In an exposure apparatus for exposing the photosensitive substrate, a first mounting surface of a mounting surface group consisting of a surface near the pattern forming surface of the mask, a conjugate surface of the pattern forming surface, and a surface near the conjugate surface. A fixed field stop arranged above for setting the width of the slit-shaped illumination area on the mask in the scanning direction, and a fixed field stop different from the first mounting surface of the mounting surface group. A movable field stop for setting a variable exposure area to be actually exposed on the photosensitive substrate within the slit-shaped illumination area on the mask, The movable field stop has a first blade and a second blade that set front and rear edge portions with respect to the scanning direction of the variable exposure region, and the first and second blades are set at the start of exposure of the mask pattern. The first blade of the movable field stop is driven to move an edge portion of the variable exposure region on the front side with respect to the scanning direction, in synchronization with the slit-shaped illumination region in the scanning direction, At the end of the exposure of the mask pattern, the second blade of the movable field stop is driven so that the edge portion on the rear side with respect to the scanning direction of the variable exposure region is with respect to the slit-shaped illumination region. In sync with the scan direction An exposure apparatus characterized in that the exposure apparatus is moved. 2. A light source for generating illumination light, an illumination optical system for illuminating a slit-shaped illumination area on a mask on which a transfer pattern is formed by the illumination light, and the illumination optical system in the slit-shaped illumination area. A projection optical system for forming a pattern image of a mask on a photosensitive substrate, and a relative scanning unit for synchronously scanning the mask and the photosensitive substrate with respect to the slit-shaped illumination area, the relative scanning An exposure apparatus that sequentially exposes a pattern image on the mask onto the photosensitive substrate by scanning the mask and the photosensitive substrate synchronously with respect to the slit-shaped illumination area by means of a pattern of the mask. Of the slit-shaped illumination area on the mask, which is arranged on the first attachment surface defocused by Δz from the conjugate surface of the formation surface in the optical axis direction of the illumination optical system, A fixed field stop for setting the width, and the photosensitive member in the slit-shaped illumination area on the mask, which is arranged on the second mounting surface that substantially coincides with the conjugate surface of the pattern formation surface of the mask. A movable field stop for setting a variable exposure area to be actually exposed on the substrate, the numerical aperture of the projection optical system on the side of the photosensitive substrate is NA _W , the illumination light from the illumination optical system The coherence factor of σ, the projection magnification of the projection optical system from the mask to the photosensitive substrate side is M _RW , and the surface of the mask near the arrangement surface of the fixed field stop is conjugate with the pattern formation surface of the mask. When the projection magnification with respect to the pattern formation surface is M _BR and the allowable minimum value of the radius of blur on the photosensitive substrate of the light emitted from one point on the arrangement surface of the fixed field stop is ΔD _min , the first The mounting surface A Okasu amount Delta] z _{is, | Δz | ≧ ΔD min /} [M BR · M RW · tan {arcsin (M BR · M RW · NA W · σ)}] satisfying the condition exposure apparatus according to claim of. 3. The exposure apparatus according to claim 2, wherein the light source is a pulse light source.