JP2674578B2 - Scanning exposure apparatus and exposure method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a projection exposure apparatus and an exposure method used in a lithography process during the manufacturing process of semiconductor devices, liquid crystal display devices and the like, and more particularly, to a mask and a photosensitive substrate for a projection optical system. The present invention relates to a relative scanning exposure apparatus and an exposure method thereof.

[0002]

2. Description of the Related Art Conventionally, there are roughly two types of projection exposure apparatuses of this type. One is a wafer through a projection optical system having an exposure field capable of containing the entire mask (reticle) pattern. Step the photosensitive substrate such as plate
The other is a method of exposing by the and repeat method, and the other is a scanning method in which a mask and a photosensitive substrate are opposed to each other with a projection optical system sandwiched therebetween and relative scanning is performed under mask illumination of arc-shaped slit illumination light. Is.

The stepper using the former step-and-repeat exposure method is a mainstream apparatus in the recent lithography process, and has a higher resolution, superposition accuracy, and a higher accuracy than the aligner adopting the latter scan-exposure method.
Throughput and the like are increasing, and steppers are considered to be the mainstream for some time to come.

Recently, a new system which achieves a high resolution even in a scan exposure system is disclosed in SPIE Vol.
088 Optical / Laser Microlithography II (198
9), pages 424 to 433, a step-and-scan method was proposed. Step and
The scanning method is a combination of a scanning method in which the mask (reticle) is scanned in one dimension while the wafer is scanned in one dimension at a speed synchronized with it, and a method in which the wafer is step-moved in a direction orthogonal to the scanning exposure direction. It was done.

FIG. 9 is a diagram for explaining the concept of the step-and-scan method. In this case, the arrangement of shot areas (one chip or multi-chip) in the X direction on the wafer W is determined by arc-shaped slit illumination light RIL. Scanning exposure is performed, and the wafer W is stepped in the Y direction. In the drawing, arrows indicated by broken lines indicate exposure routes of step & scan (hereinafter, referred to as S & S), and shot areas SA1, SA2, ...
S & S exposure is performed in the order of SA6, and then the shot areas SA7, SA8,.
The same S & S exposure is performed in the order of A12.

In the S & S type aligner disclosed in the above document, the image of the reticle pattern illuminated by the arc-shaped slit illumination light RIL is formed on the wafer W via a 1/4 reduction projection optical system. Therefore, the scanning speed of the reticle stage in the X direction is precisely controlled to be four times the scanning speed of the wafer stage in the X direction. The arc-shaped slit illumination light RIL is used for a projection optical system using a reduction system in which a refraction element and a reflection element are combined, and in a narrow range of an image height point (a ring shape) separated from the optical axis by a certain distance. This is to obtain an advantage that various aberrations become almost zero. One example of such a reflection reduction projection system is disclosed in, for example, USP. 4,747,678
Is disclosed.

[0007] S using such arc-shaped slit illumination light
In addition to the & S exposure method, a normal projection optical system (full field type) having a circular image field
Attempts to apply the S exposure method have been disclosed in, for example,
No. 423. This publication discloses that a shape of exposure light for illuminating a reticle (mask) is a regular hexagon inscribed in a circular field of a projection lens system, and two opposite edges of the regular hexagon are oriented in a direction orthogonal to a scanning exposure direction. It is disclosed that by extending the length, S & S exposure with further improved throughput is realized.

That is, in this publication, the reticle (mask) illuminating area in the scanning exposure direction is made as large as possible so that the scanning speed of the reticle stage and the wafer stage can be reduced as compared with the S & S exposure method using the arc-shaped slit illumination light. It shows that it can be significantly higher.

[0009]

SUMMARY OF THE INVENTION The above-mentioned JP-A-2-22
According to the conventional technique disclosed in Japanese Patent No. 9423, the mask illumination area in the scanning exposure direction is made as large as possible, which is advantageous in throughput. However, considering the actual mask stage and the scanning sequence of the wafer stage, even in the apparatus disclosed in the above-mentioned publication,
A zigzag S & S system as shown in FIG. 9 must be used.

This is because the diameter of the wafer W is set to 150 mm (6
Inch), in order to complete the exposure of a row of shot areas corresponding to the diameter of the wafer by only one continuous X-direction scan, the reticle is assumed to use a 1 / 5-fold projection lens system. Is 7 in the scanning direction (X direction)
This is because it has reached 50 mm (30 inches), and it is extremely difficult to manufacture such a reticle.

Even if such a reticle can be manufactured, a stroke of a reticle stage for scanning the reticle in the X direction needs to be 750 mm or more.
It is essential that the device be extremely large. For this reason,
Even in the apparatus disclosed in the above-mentioned publication, zigzag scanning has to be performed. Therefore, shot areas adjacent to each other in the scanning exposure direction, for example, shot areas SA1 and SA12 in FIG.
Therefore, it is necessary to widely cover the periphery of the pattern area on the reticle with a light shielding member so that the reticle pattern is not transferred to the adjacent shot area.

FIG. 10 shows a hexagonal illumination area HIL, a circular image field IF of a projection lens system, and a reticle R.
FIG. 10A shows a state where the hexagonal illumination area HIL is set at the scan start position on the reticle R, and from this state, only the reticle R moves rightward in FIG. Move one dimension. At the end of one scan, the result is as shown in FIG.

In FIG. 10, CP1, CP2, ... CP
Each of 6 is a chip pattern formed side by side in the X direction on the reticle R, and the array of these 6 chip patterns corresponds to the shot area to be exposed by one scan in the X direction. In the figure, the hexagonal illumination area HI
The center point of L substantially coincides with the center of the image field IF, that is, the optical axis AX of the projection lens system.

As is apparent from FIG. 10, at the scanning start portion and the scanning end portion on the reticle R, a light shield having at least the width dimension of the hexagonal illumination area HIL in the scanning direction is required outside the pattern area. And At the same time, the reticle R itself has a large dimension in the scanning direction, and the moving stroke in the X direction of the reticle stage is the sum of the dimension in the X direction of the chip patterns CP1 to CP6 as a whole and the dimension in the scanning direction of the hexagonal illumination area HIL. There may be some problems in making it into a device, such as the fact that only the amount required.

Further, since the movement stroke of the reticle stage is sufficiently large, even if the area of the light shield around the pattern area on the reticle can be increased, the illumination light for exposure is used between the start period and the end period of scanning exposure. Irradiates the surrounding light shield over a wide area, which causes a serious problem that the probability of generation of stray light due to pinhole defects in the light shield and the temperature change of the reticle due to irradiation increase.

In view of the above problems, the present invention optimizes the irradiation of the reticle (mask) with the illumination light during the scanning exposure process temporally or areawise, and reduces the probability of stray light generation due to pinhole defects. It is an object of the present invention to provide a scanning exposure apparatus that reduces various effects on a mask due to irradiation, and an exposure method using such an apparatus. Further, according to the present invention, a scanning method that improves throughput without providing a particularly wide light shield around the pattern exposure area on the mask and minimizing the movement stroke of the reticle (mask) stage during scanning exposure ( Or S &
An object of the present invention is to provide a scanning exposure apparatus of S type).

[0017]

The first and second inventions of the present application are as follows.
A projection optical system for projecting a part of the image of the circuit pattern (CPn) on the mask (reticle R) illuminated with the illumination light limited to a predetermined shape (rectangular or slit shape) onto the photosensitive substrate (wafer W) ( PL) and moving means (stages 30, 48) for moving the mask and the photosensitive substrate relative to the projection optical system in order to scan and expose the entire circuit pattern on the photosensitive substrate in a predetermined sequence. It is applied to exposure equipment.

In the apparatus according to the first invention of the present application, secondary light source generating means (fly-eye lens system 14) for making light from the exposure light source (lamp 2) incident to form a secondary light source image,
A condensing optical system (lens system 24, mirror 26, main condenser lens 28) that condenses light from the secondary light source image onto a mask (reticle R) as illumination light having a predetermined shape (rectangular shape or slit shape). Secondary light source generation means (14)
And a condensing optical system (24, 26, 28), which is arranged between the light condensing optical system (24, 26, 28) and changes the irradiation area of the illumination light on the mask (R) in synchronization with the scanning exposure sequence (of the blind mechanism 20). The movable blades BL1 to BL4) are provided.

Further, in the apparatus according to the second invention of the present application, in addition to the exposure light source (lamp 2) and the secondary light source generating means (fly-eye lens system 14) similar to those of the first invention, the secondary light source generating means ( 14) and the light source (2), which is arranged between the light source (2) and a first light blocking means (rotary shutter 6) that switches between blocking and opening of the light from the light source, and the light from the secondary light source image to a predetermined shape (rectangular or Condensing optical system (lens system 24, mirror 26, main condenser lens 28) for condensing on the mask (R) as slit-shaped illumination light, secondary light source generating means (14), and condensing optical system (24). , 26, 28) for switching the irradiation state and the non-irradiation state of the illumination light to the mask (movable blades BL1 to BL4 of the blind mechanism 20) and the first light shielding means ( 6) and second shading Means (main control unit 100) for cooperatively controlling one or both of the means (BL1 to BL4) according to the sequence of scanning exposure for the photosensitive substrate (W).
And is provided.

The third invention of the present application is an optical system for projecting an image of a part of a circuit pattern (CPn) on a mask (reticle R) illuminated with illumination light limited to a predetermined shape (rectangular shape or slit shape). The mask and the photosensitive substrate are moved one-dimensionally relative to the projection optical system while projecting onto one of a plurality of exposed regions on the photosensitive substrate (wafer W) via the system (PL). The present invention is applied to a so-called step-and-scan method, in which scanning exposure of one entire exposed area on a photosensitive substrate is repeated for each of a plurality of exposed areas.

In the method according to the third aspect of the present invention, until the scanning exposure for one exposed region on the photosensitive substrate (wafer W) is completed and the scanning exposure for the next exposed region is started, Illuminance of illumination light by operating the first illumination control means (rotary shutter 6) for uniformly changing the illuminance without changing the shape (rectangular shape or slit shape) of the illumination light reaching the (reticle R). Is kept at zero, and the area is changed without changing the uniformity of the illuminance of the illumination light reaching the mask (R) during the scanning exposure of the exposed region of the photosensitive substrate (W). It is characterized in that the step (blind mechanism 20) is operated to change the area of the illumination light according to the relative movement position of the mask and the photosensitive substrate.

According to each of the inventions of the present application configured as described above, the width of the light shield formed around the circuit pattern region on the mask can be reduced, and the irradiation time and the irradiation amount of the illumination light to the light shield can be reduced. Conventional JP-A-2-229423
Compared with the method disclosed in Japanese Patent Publication, it is much shorter and the effect of irradiation (change in mask temperature, etc.) is also reduced, so it is particularly effective when using a mercury lamp that continuously emits light as a light source. is there.

Further, during scanning exposure, it is possible to prevent stray light with respect to the mask by essentially only the second light shielding means (illumination control means), but by using the first light shielding means (illumination control means) together. Not only can more reliable stray light be prevented, but also the optical components such as the secondary light source generating means and the second light shielding means (illumination control means) themselves can be protected from the irradiation of the illumination light.

[0024]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. First, FIG. 1 shows the configuration of a projection exposure apparatus according to the first embodiment of the present invention. In this embodiment, it is constituted by a bilateral telecentric refraction element of ⅕ reduction only, or a combination of a refraction element and a reflection element. A projection optical system (hereinafter, simply referred to as a projection lens) PL is used.

The exposure illumination light from the mercury lamp 2 is focused on the second focus by the elliptical mirror 4. At this second focal point, a rotary shutter 6 that switches between blocking and transmission of illumination light by a motor 8 is arranged. The illumination light flux passing through the shutter 6 is reflected by the mirror 10 and is reflected by the input lens 12.
, And enters the fly-eye lens system 14. Many secondary light source images are formed on the exit side of the fly-eye lens system 14, and illumination light from each secondary light source image is
The light is incident on a lens system (condenser lens) 18 through 6.

On the rear focal plane of the lens system 18, the movable blades BL1, BL2, B of the reticle blind mechanism 20 are arranged.
L3 and BL4 are arranged as shown in FIG. Each of the four blades BL1, BL2, BL3, BL4 has a drive system 2
2 are moved independently. In this embodiment, blade B
X direction (scanning exposure direction) depending on the edges of L1 and BL2
The width of the opening AP of the blade is determined, and the opening AP in the Y direction (stepping direction) is determined by the edges of the blades BL3 and BL4.
Shall be determined. The shape of the aperture AP defined by the edges of the four blades BL1 to BL4 is defined so as to be included in the circular image field IF of the projection lens PL.

Now, the illumination light has a uniform illuminance distribution at the position of the blind mechanism 20, and the opening A of the blind mechanism 20 is opened.
The illumination light that has passed through P illuminates the reticle R via the lens system 24, the mirror 26, and the main condenser lens 28. At this time, an image of the aperture AP defined by the four blades BL1 to BL4 of the blind mechanism 20 (light having a uniform illuminance distribution defined in a rectangular shape or a slit shape) is formed on the pattern surface of the lower surface of the reticle R. .

The lens system 24 and the condenser lens 2
8 can provide an arbitrary imaging magnification.
Here, it is assumed that the opening AP of the blind mechanism 20 is enlarged about twice and projected onto the reticle R. Accordingly, the scanning speed Vrs of the reticle R during the scanning exposure and the blades BL1, B of the blind mechanism 20 projected on the reticle R
In order to match the moving speed of the edge image of L2, the moving speed Vbl of the blades BL1 and BL2 in the X direction is set to Vrs /
It may be set to 2.

The reticle R that has received the illumination light defined by the opening AP is held by the reticle stage 30 that can move at least uniformly in the X direction on the column 32. Although not shown, the column 32 is integrated with a column for fixing the lens barrel of the projection lens PL. Reticle stage 3
In the case of 0, the drive system 34 performs one-dimensional scanning movement in the X direction, fine rotation movement for yawing correction, and the like. At one end of the reticle stage 30, a movable mirror 36 for reflecting the measurement beam from the laser interferometer 38 is fixed.
The position in the X direction and the yawing amount are measured by the laser interferometer 38 in real time. The laser interferometer 38
Fixed mirror (reference mirror) 40 is fixed to the upper end of the lens barrel of projection lens PL.

The image of the circuit pattern formed in the rectangular area on the reticle R is reduced to 1/5 by the projection lens PL and imaged on the wafer W. The wafer W is held by a micro-rotatable wafer holder 44 together with the reference mark plate FM. The holder 44 is the optical axis AX (Z) of the projection lens PL.
It is provided on a Z stage 46 which can be finely moved in the direction. The Z stage 46 is provided on an XY stage 48 that two-dimensionally moves in the X and Y directions, and the XY stage 48 is driven by a drive system 54.

The coordinate position and yawing amount of the XY stage 48 are measured by the laser interferometer 50, and the fixed mirror 42 for the laser interferometer 50 is fixed to the lower end of the lens barrel of the projection lens PL, and the moving mirror 52. Is fixed to one end of the Z stage 46. Since the projection magnification is set to ⅕ in this embodiment, the moving speed Vws of the XY stage 48 in the X direction during scan exposure is ⅕ of the speed Vrs of the reticle stage 30.

Further, in this embodiment, a TTR (through the reticle) type alignment system 60 for detecting an alignment mark (or a reference mark FM) on the wafer W via the reticle R and the projection lens PL, and the reticle R. A TTL (through the lens) type alignment system 62 for detecting the alignment mark (or the reference mark FM) on the wafer W from the lower space via the projection lens PL is provided, and before the start of the S & S exposure or during the scan exposure. The relative alignment between the reticle R and the wafer W is performed.

The photoelectric sensor 64 shown in FIG.
When the reference mark FM is of a light emission type, the light from the light emission mark is received through the projection lens PL, reticle R, condenser lens 28, lens systems 24 and 18, and beam splitter 16, and the XY stage 48 It is used when defining the position of the reticle R in the coordinate system or when defining the position of the detection center of each alignment system 60, 62.

By the way, the opening AP of the blind mechanism 20
Is a rectangular shape (or a slit shape) that is as long as possible in the Y direction orthogonal to the scanning direction (X direction).
The number of times of scanning in the direction, that is, the number of times of stepping the wafer W in the Y direction can be reduced. However, depending on the size, shape, and arrangement of the chip pattern on the reticle R, the length of the opening AP in the Y direction may be set to the blades BL3 and BL4.
It may be better to change at each edge of. For example, the opposing edges of the blades BL3 and BL4 may be adjusted so as to be aligned with the street line that defines the shot area on the wafer W. By doing so, it is possible to easily cope with the size change of the shot area in the Y direction.

When the size of one shot area in the Y direction is equal to or larger than the maximum size of the opening AP in the Y direction, as shown in the above-mentioned Japanese Patent Laid-Open No. 2-229423, the overlap in the shot area occurs. It is necessary to perform exposure to make the exposure amount seamless. The method in this case will be described later in detail. Next, the operation of the apparatus according to the present embodiment will be described.
0 is managed collectively. The basic operation of the main control unit 100 includes position information from the laser interferometers 38 and 50,
Based on the input of yawing information, the input of speed information from a tachogenerator or the like in the drive systems 34 and 54, the reticle stage 30 and the XY stage 48 are maintained at a predetermined speed ratio during scan exposure, The relative movement with respect to the pattern is kept within a predetermined alignment error.

In addition to its operation, the main controller 100 of this embodiment moves the edge positions of the blades BL1 and BL2 in the scanning direction of the blind mechanism 20 in the X direction in synchronization with the scanning of the reticle stage 30. , Drive system 22
The main feature of this is that it is controlled interlockingly. When the illumination light amount at the time of scanning exposure is constant, the reticle stage 3 becomes larger as the maximum opening width of the opening AP in the scanning direction increases.
0, the absolute speed of the XY stage 48 must be increased. In principle, when the same exposure amount (dose amount) is given to the resist on the wafer W, if the width of the opening AP is doubled, the XY stage 48 and the reticle stage 3
Zero must also be twice as fast.

FIG. 3 shows the positional relationship between the reticle R that can be mounted on the apparatus shown in FIGS. 1 and 2 and the opening AP of the blind mechanism 20. Here, four chip patterns CP1, CP2, CP3 are provided on the reticle R. , CP4 are arranged in the scanning direction. Each chip pattern is defined by a light-shielding band corresponding to a street line, and the periphery of a pattern collection region (shot region) is surrounded by a light-shielding band having a width Dsb wider than the street line. Here, it is assumed that the left and right light-shielding bands around the shot area on the reticle R are SBl and SBr, and reticle alignment marks RM1 and RM2 are formed outside thereof.

The opening AP of the blind mechanism 20 has an edge E1 of the blade BL1 and an edge E2 of the blade BL2 extending parallel to the Y direction orthogonal to the scanning direction (X direction).
And the width of the edges E1 and E2 in the scanning direction is Dap. Further, the length of the opening AP in the Y direction is substantially equal to the width of the shot area on the reticle R in the Y direction, and the edge defining the longitudinal direction of the opening AP is aligned with the center of the light shielding band extending in the X direction in the periphery. The blades BL3 and BL4 are set so as to do so.

Next, with reference to FIG. 4, the manner of S & S exposure of this embodiment will be described. Here, it is assumed that the reticle R and the wafer W shown in FIG.
It is assumed that relative alignment is performed using 0, 62, photoelectric sensor 64 and the like. FIG. 4 shows the reticle R of FIG. 3 as viewed from the side, and here, the blade BL of the blind mechanism 20 is shown.
1. To make the operation of BL2 easier to understand, reticle R
The blades BL1 and BL2 are shown just above.

First, as shown in FIG. 4A, the reticle R
Is set as the scanning start point in the X direction. Similarly, one corresponding shot area on the wafer W is set to start scanning in the X direction. At this time, the image of the aperture AP illuminating the reticle R ideally desirably has a width Dap of zero, but it is difficult to completely eliminate the width Dap due to the condition of the edges E1 and E2 of the blades BL1 and BL2. .

Therefore, in this embodiment, the width Dap of the image of the aperture AP on the reticle is set to be smaller than the width Dsb of the light-shielding band SBr on the right side of the reticle R. Normally, shading band S
The width Dsb of Br is about 4 to 6 mm, and the width Dap of the image of the aperture AP on the reticle is preferably about 1 mm. Then, as shown in FIG. 4A, the center of the opening AP in the X direction is shifted by ΔXs with respect to the optical axis AX in the direction opposite to the scanning direction of the reticle R (left side in the figure).

The distance ΔXs is set to about half the maximum opening width Dap of the opening AP with respect to the reticle R. More specifically, since the dimension of the opening AP in the longitudinal direction is naturally determined by the width of the shot area of the reticle R in the Y direction, the maximum value DAmax of the width Dap of the opening AP in the X direction is also determined by the diameter of the image field IF. Come on. The maximum value DAmax is calculated in advance by the main control unit 100. Further, assuming that the width (minimum) of the aperture AP at the scanning start point in FIG. 4A is DAmin, strictly speaking, DAmin + 2
The distance ΔXs is determined so as to satisfy the relationship ΔXs = DAmax.

Next, the reticle stage 30 and the XY stage 48 are moved in mutually opposite directions at a speed ratio proportional to the projection magnification. At this time, as shown in FIG. 4B, of the blind mechanism 20, the blade B in the traveling direction of the reticle R
Only L2 is moved in synchronization with the movement of the reticle R so that the image of the edge E2 of the blade BL2 is on the light-shielding band SBr. At this time, the rectangular area of the illumination light with which the reticle R is irradiated gradually increases as the blade BL2 moves.

When the scanning of the reticle R progresses and the edge E2 of the blade BL2 reaches the position defining the maximum opening width of the opening AP as shown in FIG. 4C, the movement of the blade BL2 is stopped thereafter. Therefore, the drive system 22 of the blind mechanism 20 is provided with an encoder, a tacho-generator, etc. for monitoring the moving amount and moving speed of each blade, and the position information and speed information from these are provided to the main control unit 10.
0 and is used to synchronize with the scanning movement of the reticle stage 30.

Thus, the reticle R has the maximum width AP.
While being illuminated by the illumination light passing through, the light is sent in the X direction at a constant speed and reaches the position shown in FIG. That is, the edge E of the blade BL1 in the direction opposite to the direction of travel of the reticle R
1 is a light-shielding band S on the left side of the shot area of the reticle R.
4E, the image of the edge E1 of the blade BL1 is run in the same direction in synchronization with the moving speed of the reticle R, as shown in FIG. At this time, the area of the illumination light that irradiates the reticle R gradually decreases as the blade BL1 moves.

Then, at the time when the left shading band SBl is shielded by the edge image of the right blade BL2 (at this time, the left blade BL1 also moves, and the width Dap of the opening AP becomes the minimum value DAmin). , The movement of the reticle stage 30 and the blade BL1 is stopped. With the above operation, exposure by one scan of the reticle (exposure for one shot) is completed, and the shutter 6 is closed. However, if the width Dap of the opening AP is sufficiently narrower than the width Dsb of the light-shielding band SBl (or SBr) at that position and the illumination light (stray light) leaking to the wafer W can be made zero, the shutter 6 is set. You can leave it open. Since the shutter 6 is arranged between the mercury lamp 2 and the fly-eye lens system 14, the shape (area) of the illumination light that can reach the reticle R by opening and closing the shutter 6 does not change, and only the light intensity is changed. It changes almost uniformly.

Next, the XY stage 48 is stepped in the Y direction by one row of the shot area, and the XY stage 48 and the reticle stage 30 are scanned in the opposite direction to the same as in the different shot areas on the wafer W. Perform scan exposure. As described above, according to the present embodiment, the stroke of the reticle stage 30 in the scanning direction can be minimized, and the width Dsb of the light-shielding bands SB1 and SBr defining both sides of the shot area in the scanning direction can be reduced. There are advantages.

It should be noted that, until the reticle stage 30 accelerates from the state of FIG. 4 (A) to uniform speed scanning, uneven exposure amount in the scanning direction occurs on the wafer W. Therefore, at the start of scanning, it is necessary to determine a prescan (running) range until the state shown in FIG. In that case, the width Dsb of the light-shielding bands SBr and SBl is increased according to the length of the pre-scan. This also applies when overscanning is required in response to the fact that the uniform velocity motion of the reticle stage 30 (XY stage 48) cannot be stopped abruptly at the end of one scan exposure. .

However, even when performing pre-scanning and over-scanning, if the shutter 6 is set to a high speed and the open response time (the time required from the fully closed state of the shutter to the full open) and the closing response time are sufficiently short, When the reticle stage 30 completes the pre-scan (acceleration) and enters the main scan (position in FIG. 4A), or when the main scan shifts to overrun (deceleration), the shutter 6 is interlocked. Just open and close it.

For example, the uniform scanning speed of the reticle stage 30 during the main scan is Vrs (mm / sec), and the light-shielding bands SBl and S.
Assuming that the width of Br is Dsb (mm) and the minimum width of the opening AP on the reticle R is DAmim (mm), the response time ts of the shutter 6 satisfies the following relationship under the condition of Dsb> DAmin. If you have. (Dsb−DAmin) / Vrs> ts In the apparatus of this embodiment, the yaw amount of the reticle stage 30 and the yaw amount of the XY stage 48 are measured independently by the laser interferometers 38 and 50, respectively. The main control unit 100 determines the difference in the yawing amount,
The reticle stage 30 or the wafer holder 44 may be slightly rotated during the scanning exposure so that the difference becomes zero. However, in this case, the rotation center of the minute rotation needs to be always at the center of the opening AP. Considering the structure of the apparatus, the guide portion of the reticle stage 30 in the X direction is minutely rotated about the optical axis AX. The method can be easily realized.

FIG. 5 shows an example of the pattern arrangement of the reticle R which can be mounted on the apparatus shown in FIGS. 1 and 2, and the chip patterns CP1, CP2, CP3 are the reticle R shown in FIG.
In the same manner as described above, it is used to expose a wafer by a step-and-scan method using illumination light from a slit-shaped opening AP. The other chip patterns CP4 and CP5 formed on the same reticle R are used to expose a wafer by a step-and-repeat (S & R) method.

The blind mechanism 2 is used properly in this way.
For example, when exposing the chip pattern CP4, the reticle stage 30 is moved so that the pattern center of the chip pattern CP4 coincides with the optical axis AX when exposing the chip pattern CP4. At the same time, it is only necessary to match the shape of the opening AP with the outer shape of the chip pattern CP4. Then, only the XY stage 48 needs to be moved in the stepping mode. With the reticle pattern shown in FIG. 5 as described above, the S & S exposure and the S & R exposure can be selectively performed by the same apparatus without changing the reticle.

FIG. 6 shows the blind mechanism 20 corresponding to the case where the size of the chip pattern on the reticle to be exposed in the direction (Y direction) orthogonal to the scanning direction becomes larger than the image field IF of the projection optical system. An example of the shapes of the blades BL1 to BL4 is shown, and the edges E1 and E2 that define the width of the opening AP in the scanning direction (X direction) extend in parallel to the Y direction as in FIG.

The edges E3 and E4 defining the longitudinal direction of the opening AP are parallel to each other but are inclined with respect to the X axis, and the opening AP becomes a parallelogram (rectangle). In this case, the four blades BL1 to BL4 move in the X and Y directions in conjunction with the movement of the reticle during scan exposure. However, although the moving speed Vbx in the X direction of the images of the edges E1 and E2 of the blades BL1 and BL2 in the scanning exposure direction is almost the same as the scanning speed Vrs of the reticle, the blade BL3,
When it is necessary to move BL4, its edges E3, E
The moving speed Vby in the Y direction of 4 is Vby = Vbx · tan θe, where θe is the inclination angle of the edges E3 and E4 with respect to the X axis.
Need to be synchronized with the relationship.

FIG. 7 shows the S & S according to the opening shape shown in FIG.
7 schematically shows a scanning sequence at the time of S exposure. In FIG. 7, the aperture AP is considered as being projected on the reticle R, and is shown by its edges E1 to E4. In the second embodiment shown in FIGS. 6 and 7, it is assumed that the chip pattern region CP on the reticle R to be projected on the wafer W has a size about twice the size of the opening AP in the longitudinal direction. Therefore, in the second embodiment, the reticle stage 30 is also structured to precisely step in the Y direction orthogonal to the scanning direction.

First, the blades BL1 and BL2 in FIG. 6 are adjusted to set the state as shown in FIG. 7A at the start of scanning. That is, the aperture AP with the narrowest width is located on the right shading band SBr of the reticle R, and the edge E1 on the left side of the aperture AP is at the position farthest from the optical axis AX (the aperture AP is Set it to the edge position when it is most widened in the X direction. In FIG. 7, the scanning direction (X
The regions Ad and As extending in a belt shape in the (direction) are regions where the exposure amount is insufficient in one scanning exposure.

The areas Ad and As are generated by the fact that the upper and lower edges E3 and E4 of the opening AP are inclined with respect to the X axis, and the widths of the areas Ad and As in the Y direction are:
DAmax · tan θe is uniquely determined by the inclination angle θe of the edges E3 and E4 and the maximum opening width DAmax of the edges E1 and E2. Areas Ad and A where this exposure amount unevenness occurs
In the area Ad set in the pattern area CP of s, the exposure amount is made uniform by performing scanning exposure by overlapping the triangular portions formed by the edges E3 and E4 of the opening AP in the Y direction. I did it. Further, the other area As is exactly aligned with the light-shielding band on the reticle R.

Now, from the state of FIG. 7A, the reticle R and the edge E2 (blade BL2) are made to run in the + X direction (right side in the figure) at substantially the same speed. Eventually, as shown in FIG. 7B, the width of the opening AP in the X direction becomes maximum, and the edge E
Stop moving 2 as well. In the state shown in FIG. 7B, the center of the opening AP substantially coincides with the optical axis AX. After that, only the reticle R moves at a constant velocity in the + X direction, and from the time when the left edge E1 of the opening AP enters the left light-shielding band SBl as shown in FIG. 7C, the edge E1 (blade BL1) becomes the reticle R. Move to the right (+ X direction) at almost the same speed. Thus, the lower half of the chip pattern area CP is exposed, and the reticle R and the opening AP are stopped in a state as shown in FIG.

Next, the reticle R is precisely stepped in the -Y direction by a fixed amount. The wafer W is similarly stepped in the + Y direction. Then, a state as shown in FIG. At this time, the overlap area Ad is overlapped and exposed in the triangular portion defined by the edge E4.
The relative positional relationship in the direction is set. At this time, the opening A
When it is necessary to change the length of P in the Y direction, the edge E
3 (Blade BL3) or Edge E4 (Blade BL3
4) Move and adjust in the Y direction.

Next, the reticle R is scanned and moved in the -X direction, and the edge E1 (blade BL1) is moved in conjunction with the -X direction. Then, when the opening width by the edges E1 and E2 becomes maximum as shown in FIG. 7F, the movement of the edge E1 is stopped and only the reticle R is continuously moved in the −X direction at a constant velocity. By the above operation, a large chip pattern area CP having a size larger than the dimension of the image field of the projection optical system in the Y direction can be exposed on the wafer W. Moreover, the overlap area Ad is set and the opening AP
Both ends (triangle part) where the amount of exposure is insufficient due to the shape of
Is overlapped by two scanning exposures, the area Ad
The amount of exposure inside is also made uniform.

FIG. 8 shows another blade shape of the blind mechanism 20, which defines blades BL1 and BL for defining the scanning direction.
The edges E1 and E2 of 2 are straight lines parallel to each other, and the edges of the blades BL3 and BL4 in the direction orthogonal to the scanning direction are triangular shapes symmetrical with respect to the Y axis passing through the optical axis AX. Here, the edges of the blades BL3, BL4 have a complementary shape so that they can shield light almost completely as they approach each other in the Y direction. Therefore, the shape of the opening AP can be a so-called chevron shape. In the case of such a chevron shape as well, if overlap exposure is performed in the triangular portions at both ends, uniformity can be similarly achieved.

As described above, in each of the embodiments of the present invention, the projection exposure apparatus is premised, but the mask and the wafer are brought close to each other, and the proxy which integrally scans the mask and the wafer with respect to the irradiation energy (X-ray, etc.) is used. The same method can be used for the Mighty Aligner. Further, in each of the above-described embodiments, the illumination light is not applied to the mask through a fixed-shaped opening (hexagonal shape, arc-shaped shape, etc.) as in the conventional scanning exposure method, but the opening AP (variable) of the blind mechanism 20 is changed. Since the width of the field stop) in the scanning direction is changed in conjunction with the mask scanning or the photosensitive substrate scanning, even if the mask is not overrun greatly at the scanning start portion or the scanning end portion on the mask, the opening AP Equivalent S only by decreasing the width sequentially
& S exposure method can be realized.

Therefore, since the overrun of the mask stage is unnecessary or can be made extremely small, the moving stroke of the mask stage can be minimized and the width of the light shield formed around the pattern formation area on the mask can be minimized. Also, the number of masks can be as small as that of a conventional mask, and there is an advantage that the time and effort for inspecting a pinhole defect in a light shield (usually a chromium layer) at the time of manufacturing a mask are reduced.

Further, by setting the shape of the opening AP of the blind mechanism 20 so as to match the pattern formation area on the mask, it can be used as a stepper equivalent to the conventional one, and the blind mechanism 20 (variable field diaphragm).
Instantly respond to mask patterns of various chip sizes by configuring the aperture position and geometric shape of the device to change in one-dimensional, two-dimensional or rotational directions within the image field of the projection optical system. You can

[0065]

As described above, according to the present invention, the irradiation area of the illumination light on the mask is changed in synchronization with the scanning exposure sequence. Therefore, the moving stroke of the mask (reticle) in the scanning exposure method is changed. Can be minimized, and the size of the light-shielding band on the mask can be reduced. At the same time, the illumination area in the scanning direction can be made small at the scanning start portion and the scanning end portion on the mask, and the illumination area in the scanning direction can be made large at the other scanning intermediate portions, so processing is performed in combination with the reduction of the movement stroke. Throughput can be significantly increased.

Further, according to the present invention, the first light shielding means (shutter) arranged between the light source and the secondary light source generating means.
Since either one or both of the second light shielding means (movable blade) arranged between the secondary light source generating means and the condensing optical system is controlled in accordance with the scanning exposure sequence, It is possible to obtain the optimum processing throughput corresponding to the sequence when sequentially scanning and exposing each of the plurality of exposed regions on the photosensitive substrate.

Further, during scanning exposure, stray light can be prevented essentially only by the second light shielding means (illumination control means), but more reliable stray light can be obtained by using the first light shielding means (illumination control means) together. Not only can it be prevented, but it is also possible to protect the optical components such as the secondary light source generating means and the second light shielding means (illumination control means) themselves from the irradiation of illumination light.

[Brief description of the drawings]

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

FIG. 2 is a plan view showing a blade shape of the blind mechanism.

FIG. 3 is a plan view showing a pattern arrangement of a reticle suitable for the apparatus shown in FIG. 1;

FIG. 4 is a view for explaining a scanning exposure operation in the embodiment of the present invention.

FIG. 5 is a plan view showing another pattern arrangement of a reticle that can be mounted on the apparatus of FIG. 1;

FIG. 6 is a plan view showing a blade shape of a blind mechanism according to a second embodiment.

FIG. 7 is a view for explaining a sequence of step & scan exposure according to the second embodiment.

FIG. 8 is a plan view showing another blade shape.

FIG. 9 is a view for explaining the concept of a conventional step-and-scan exposure method using arc-shaped slit illumination light.

10A and 10B are views for explaining a conventional scan exposure system using regular hexagonal illumination light.

[Description of Signs of Main Parts]

 R reticle PL projection optical system W wafer BL1, BL2, BL3, BL4 blade AP aperture 20 blind mechanism 30 reticle stage 34 drive system 48 XY stage 54 drive system 100 main control unit

Claims (8)

(57) [Claims] 1. A projection optical system for projecting an image of a part of a circuit pattern on a mask, which is illuminated with illumination light limited to a predetermined shape, onto a photosensitive substrate, and the entire circuit pattern on the photosensitive substrate. A scanning exposure apparatus including a moving unit that relatively moves the mask and a photosensitive substrate with respect to the projection optical system for scanning exposure in a predetermined sequence. Secondary light source generating means for forming an image; a condensing optical system for condensing the light from the secondary light source image on the mask as the illumination light of the predetermined shape; the secondary light source generating means and the condensing optics A scanning exposure apparatus, which is provided between the system and a light-shielding unit for changing the irradiation area of the illumination light on the mask in synchronization with the scanning exposure sequence. 2. The light shielding means includes a movable blade disposed at a position substantially conjugate with the mask and movably provided along a direction of relative movement between the mask and the photosensitive substrate by the moving means. The apparatus of claim 1 characterized. 3. The light shielding means has an illumination field stop mechanism having a variable rectangular aperture imaged on the mask by the condensing optical system, and the condensing optical system of the illumination field stop mechanism. The apparatus according to claim 1, further comprising an imaging magnification for enlarging and projecting an image of a rectangular aperture on the mask. 4. The variable rectangular aperture is set in a slit shape linearly extending orthogonal to the relative movement direction of the mask and the photosensitive substrate, and the illumination field diaphragm mechanism has a width of the slit-shaped variable rectangular aperture. 4. The apparatus according to claim 3, further comprising a movable light-shielding plate that changes continuously with the scanning exposure sequence in synchronism with the scanning exposure sequence. 5. A projection optical system for projecting an image of a part of a circuit pattern on a mask, which is irradiated with illumination light limited to a predetermined shape, onto a photosensitive substrate, and the entire circuit pattern on the photosensitive substrate. In a scanning exposure apparatus including a moving unit that relatively moves the mask and the photosensitive substrate relative to the projection optical system to perform scanning exposure on each of a plurality of exposed regions in a predetermined sequence, Secondary light source generating means for making light incident to form a secondary light source image; first light shielding means arranged between the secondary light source generating means and the light source to switch between blocking and opening of light from the light source A condensing optical system that condenses the light from the secondary light source image onto the mask as the illumination light having the predetermined shape; and is arranged between the secondary light source generating means and the condensing optical system. Illumination state and non-illumination of the mask A second light-shielding means for switching the irradiation state; and means for cooperatively controlling one or both of the first light-shielding means and the second light-shielding means in accordance with a scanning exposure sequence for the photosensitive substrate. A scanning exposure apparatus characterized by the above. 6. An image of a part of a circuit pattern on a mask, which is illuminated with illumination light limited to a predetermined shape, is transferred to one of a plurality of exposed regions on a photosensitive substrate via a projection optical system. While projecting, the mask and the photosensitive substrate are moved one-dimensionally relative to the projection optical system to scan-expose the entire circuit pattern onto one exposed region on the photosensitive substrate. In an exposure method which is repeated for each of a plurality of exposed areas, until the scanning exposure for the one exposed area is completed and the scanning exposure for the next exposed area is started,
During the period of scanning exposure of the exposed region, the first illumination control means for uniformly changing the illuminance without changing the shape of the illuminating light reaching the mask is operated to keep the illuminance of the illuminating light at zero. Operates the second illumination control means for changing the area without changing the uniformity of the illuminance of the illumination light reaching the mask to operate the illumination according to the relative movement position of the mask and the photosensitive substrate. An exposure method characterized by changing the area of light. 7. A rectangular shape or slit that linearly extends the intensity distribution of the illumination light with which the mask is irradiated in a non-scanning direction orthogonal to the relative one-dimensional movement direction of the mask and the photosensitive substrate. 7. The method of claim 6, wherein the method is limited to a shape. 8. The second illumination control means sets the width of the rectangular or slit intensity distribution of the illumination light reaching the mask in the one-dimensional movement direction to the one-dimensional movement of the circuit pattern on the mask. 8. The method according to claim 7, further comprising continuously varying from a constant value smaller than the dimension in the direction to almost zero.