JPH09186082A - Scanning exposure method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable applying a successive focus exposure method similar to the conventional static projection exposure time, in spite of a scanning exposure system, and scanning and exposing a fine circuit pattern without deteriorating throughput, in the state that the apparent focal depth is increased. SOLUTION: While projecting the image of a part of a circuit pattern on a mask R, on a photosesitive board W via a projection optical system PL, the mask R and the board W are one-dimensionally scanned, and the whole image of the circuit pattern is exposed on the board W. In this case, the form of the luminous flux illuminating the mask R is limited in a rectangular type or a slit type which has a constant width in the one-dimensional scanning direction and rectilinearly stretches in the direction intersecting the scanning direction. The relative inclination and interval between the imagery surface of the projection optical system PL and the board W surface are so controlled that the partial image of the rectangular type or the slit type of the circuit pattern projected on the board W by the luminous flux continues to coincide with the board W surface in the range of the focal depth of the projection optical system PL.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a scanning exposure method using a projection exposure apparatus used in a lithography process during the manufacturing process of semiconductor devices, liquid crystal display devices and the like.

[0002]

2. Description of the Related Art Heretofore, there are roughly two types of projection exposure apparatuses of this type. One is a wafer exposure system which has a light exposure field capable of enclosing the entire pattern of a mask (reticle). The other is a method of exposing a photosensitive substrate such as a plate by a step-and-repeat method. This is a scanning method for performing exposure.

A stepper adopting the former step-and-repeat exposure method is a mainstream apparatus in recent lithography processes, and has a higher resolution, overlay accuracy, throughput, etc. than an aligner employing the latter scan exposure method. Both are getting higher, and steppers are considered to be the mainstream for some time to come. In this step-and-repeat exposure method, in order to increase the apparent depth of focus of the projection optical system, an exposure method in which the photosensitive substrate and the projection optical system are relatively moved in the optical axis direction of the projection optical system during exposure of one exposure area. It has also been proposed to use a progressive focus exposure method together. The amount of movement in the optical axis direction in this progressive focus exposure method takes into consideration the original depth of focus of the projection optical system and minute unevenness on the photosensitive substrate, and at least the upper and lower parts of the unevenness on the photosensitive substrate are moved during the movement. The best image plane of the projection optical system comes to and.

Recently, a new system which achieves a high resolution even in a scan exposure system is disclosed in SPIE Vol.
Optical / Laser Microlithography II (1989) 42nd
It was proposed as a step-and-scan method on pages 4 to 433. The step-and-scan method is a method in which a mask (reticle) is one-dimensionally scanned while a wafer is one-dimensionally scanned at a speed synchronized with the mask, and a method in which the wafer is step-moved in a direction orthogonal to a scanning exposure direction. Are mixed.

FIG. 11 is a diagram for explaining the concept of the step-and-scan method. Here, the arrangement of shot areas (one chip or multi-chips) in the X direction on the wafer W is defined by arcuate slit illumination light RIL. Scanning exposure is performed and the wafer W is stepped in the Y direction. In the figure, the arrow indicated by the broken line is a step-and-scan (hereinafter referred to as S & S).
), And the shot areas SA1, SA
S & S exposure is performed in the order of 2,..., SA6.
Shot areas SA7, SA8,
The same S & S exposure is performed in the order of SA12.

In the S & S type aligner disclosed in the above-mentioned document, the image of the reticle pattern illuminated by the arcuate slit illumination light RIL is imaged on the wafer W through the 1/4 times reduction projection optical system. Because of the reticle stage X
The scanning speed in the direction is precisely controlled to 4 times the scanning speed in the X direction of the wafer stage. Further, the arc-shaped slit illumination light RIL is used in a narrow range of an image height point at a certain distance from the optical axis (a ring shape) using a reduction system combining a refraction element and a reflection element as a projection optical system. This is to obtain an advantage that various aberrations become almost zero. An example of such a catoptric reduction projection system is disclosed, for example, in USP 4,747,678.

[0007]

However, it is impossible to apply the progressive focus exposure method similar to the step-and-repeat method to the step-and-scan apparatus disclosed in the above-mentioned document. That is, in the case of the step-and-repeat method, the reticle, the illumination light beam / the wafer, and the exposure light beam do not relatively move in a direction perpendicular to the optical axis of the projection optical system (in-plane direction of the wafer). By relatively moving the wafer and the projection optical system in the optical axis direction (Z direction), multiple exposures can be performed in the transfer area at a plurality of focal positions.

On the other hand, in the case of the above-described step-and-scan apparatus, the reticle, the illumination light beam / the wafer, and the exposure light beam are in a direction (X or Y direction) perpendicular to the optical axis of the projection optical system.
When the wafer and the projection optical system are simply moved relative to each other in the optical axis direction during the exposure, a portion to be focused and a portion to be out of focus are mixed depending on the position in the transfer area. Will be. Therefore, simply applying the progressive focus exposure method similar to the step-and-repeat method not only cannot expect the effect of increasing the depth of focus but also lowers the resolution of the image.

Therefore, it is a first object of the present invention to provide a scanning exposure method such as a step-and-scan method to which a conventional progressive focus exposure method can be easily applied, and a scanning exposure method to which the progressive focus exposure method is applied. In this case, the second object is to provide a scanning exposure method capable of improving the throughput as compared with the conventional case.

[0010]

A first invention (claim 1) of the present application for achieving the above object is a mask (reticle).
While projecting a part of the circuit pattern IR on R onto the sensitive substrate (wafer) W via the projection optical system PL, the reticle R and the wafer W are projected to the projection magnification (1/5 or 5) of the projection optical system PL. The present invention is applied to a method of scanning and exposing the entire image of the circuit pattern IR of the reticle R on the wafer W by performing relative one-dimensional scanning at a speed ratio according to (1/4).

In the first invention of the present application, a partial image of the circuit pattern IR projected on the wafer W is projected onto the projection optical system P.
The reticle R is exposed for exposure so that the reticle R is limited to a slit region linearly extending in the direction (Y direction) intersecting the direction (X direction) of the one-dimensional scanning in the center of the circular projection field IF of L. Irradiate with slit-shaped illumination light IL,
During the relative one-dimensional scanning between the reticle R and the wafer W, the image plane (B
F) and the surface of the exposed portion of the wafer W are the projection optical system PL.
The projection optical system P
The relative inclination (leveling) between the image plane and the wafer W by L and the interval (focus) are controlled.

In the second invention (claim 10) of the present application, a part of the circuit pattern IR on the mask (reticle R) is projected onto a sensitive substrate (wafer) W through the projection optical system PL. , The reticle R and the wafer W are relatively one-dimensionally scanned at a speed ratio corresponding to the projection magnification (1/5 or 1/4) of the projection optical system PL to form the circuit pattern I of the reticle R.
It is applied to a method of scanning and exposing the entire image of R on the wafer W.

In the second invention of the present application, a partial image of the circuit pattern IR projected on the wafer W is projected onto the projection optical system P.
Direction of one-dimensional scanning in the circular projection field IF of L (X direction)
One-dimensional scanning direction (X) so as to be restricted within a plurality of slit-shaped regions extending in parallel to the direction intersecting with (Y direction)
A plurality of slit-shaped illumination luminous fluxes (I
L) toward the reticle R, and during relative one-dimensional scanning between the reticle R and the wafer W, the projection optical system PL forms an image plane (BF) in the slit-shaped area on the wafer W. So that the surface of the exposed portion of the projection optical system PL remains substantially in agreement within the depth of focus of the projection optical system PL, the relative inclination (leveling) between the image plane (BF) by the projection optical system PL and the wafer W and the distance ( Focus).

[0014]

According to the present invention, when a mask and a substrate are moved relative to a projection optical system for scanning exposure, a part of a circuit pattern projected on the substrate by the projection optical system is exposed. The image extends within a circular field of view of the projection optical system in a direction intersecting the one-dimensional scanning direction and has a substantially constant width in the one-dimensional scanning direction within one linear slit region.
Alternatively, since it is configured to be limited to a plurality of parallel slit areas, the best imaging plane of the projection optical system and the surface of the exposed area on the substrate are tilted relative to the one-dimensional scanning direction as necessary for scanning. It becomes possible to perform exposure, and a progressive focus exposure method that expands the apparent depth of focus can be easily realized.

When the progressive focus exposure method is carried out, the relative tilt between the image plane in the slit area limited within the circular visual field of the projection optical system and the surface of the exposed area on the substrate is determined by the projection optical system. Only by controlling the leveling state and the focus state in conjunction with the movement of the substrate during one-dimensional scanning so as to be maintained within the width of the depth of focus of the slit area, it is possible to make the slit area substantially uniform in the longitudinal direction (non-scanning direction). The effect of expanding the depth of focus will be obtained. Therefore, the configuration and operation of the projection exposure apparatus to which the scanning exposure method according to the present invention is applied will be described below.

FIG. 1 shows a configuration of a reduction projection type exposure apparatus suitable for carrying out the present invention. In this apparatus, a 1/5 element composed of only a refraction element or a combination of a refraction element and a reflection element is used.
It is assumed that a projection optical system PL that is telecentric on both sides of reduction is used. The illumination light for exposure from the mercury lamp 1 is an elliptical mirror 2
At the second focal point. In this second focus, the motor 4
A rotary shutter 3 that switches between blocking and transmitting illumination light is arranged. The illumination light beam passing through the shutter 3 is reflected by the mirror 5 and enters the fly-eye lens system 7 via the input lens 6.

Many secondary light source images are formed on the exit side of the fly-eye lens system 7, and illumination light from each secondary light source image enters a lens system (condenser lens) 9 via a beam splitter 8. . The movable blades BL1, BL of the reticle blind mechanism 10 are provided on the rear focal plane of the lens system 9.
2, BL3 and BL4 are arranged as shown in FIG. Four
The blades BL1, BL2, BL3, BL4 are independently moved by the drive system 50. In the present apparatus example, the width of the opening AP in the X direction (scanning exposure direction) is determined by the edges of the blades BL1 and BL2,
It is assumed that the length of the opening AP in the Y direction (stepping direction) is determined by the edge of L4. An opening AP defined by each edge of the four blades BL1 to BL4
Is defined so as to be included in the circular image field (field of view) IF of the projection optical system PL.

At the position of the blind mechanism 10, the illumination light has a uniform illuminance distribution, and the aperture A of the blind mechanism 10
The illumination light having passed through P irradiates the reticle R via the lens system 11, the mirror 12, and the main condenser lens 13. At this time, an image of the opening AP defined by the four blades BL1 to BL4 of the blind mechanism 10 is formed on the pattern surface on the lower surface of the reticle R. The reticle R that has received the illumination light defined by the opening AP is held on a reticle stage 14 that can move on the column 15 at least in the X direction at a constant speed.

The column 15 is integrated with a column (not shown) for fixing the lens barrel of the projection optical system PL. The reticle stage 14 performs a one-dimensional scanning movement in the X direction and a minute rotation movement for yawing correction by a driving system 51. A moving mirror 31 that reflects the measurement beam from the laser interferometer 30 is fixed to one end of the reticle stage 14, and the position of the reticle R in the X direction and the yawing amount are determined by the laser interferometer 3.
It is measured in real time by 0. The fixed mirror (reference mirror) 32 for the laser interferometer 30 is fixed to the upper end of the lens barrel of the projection optical system PL.

The image of the pattern formed on the reticle R is reduced to 1/5 by the projection optical system PL and formed on the wafer W. The wafer W is held together with the reference mark plate FM by a wafer holder 16 that can be rotated slightly and tilted at an arbitrary angle. The holder 16 is a Z stage 17 that can be finely moved in the optical axis AX direction (Z direction) of the projection optical system PL.
Provided above. The Z stage 17 is provided on an XY stage 18 that moves two-dimensionally in the X and Y directions.
The Y stage 18 is driven by the drive system 52.

The coordinate position and the yawing amount of the XY stage 18 are measured by a laser interferometer 33. A fixed mirror (reference mirror) 34 for the laser interferometer 33 is provided at the lower end of the lens barrel of the projection optical system PL. The movable mirror 35 is the Z stage 17
Are fixed to one end of each. In this device example, the projection magnification is 1
Therefore, the moving speed Vws of the XY stage 18 in the X direction at the time of scan exposure is 1/5 of the speed Vrs of the reticle stage 14.

Further, in the present apparatus example, a TTR (through-the-reticle) type alignment system 40 for detecting an alignment mark (or a reference mark FM) on the wafer W via the reticle R and the projection optical system PL, and a reticle R And a TTL (through-the-lens) type alignment system 41 for detecting an alignment mark (or a reference mark FM) on the wafer W from the space below through the projection optical system PL, before starting S & S exposure or scanning exposure The relative positioning between the reticle R and the wafer W is performed during the process.

The photoelectric sensor 42 shown in FIG.
When the reference mark FM is of a light emitting type, the light from the light emitting mark is received through the projection optical system PL, the reticle R, the condenser lens 13, the lens systems 11 and 9, and the beam splitter 8, and the XY stage 18 This is used when defining the position of the reticle R in the coordinate system of 1 or when defining the position of the detection center of each alignment system 40, 41. However, these alignment systems are not particularly essential for achieving the present invention.

The opening AP of the blind mechanism 10
By increasing the length in the Y direction orthogonal to the scanning direction (X direction) as much as possible, the number of scans in the X direction, that is, the number of steppings of 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, it may be better to change the length of the opening AP in the Y direction at each edge of the blades BL3, BL4.

For example, it is preferable to adjust the edges of the blades BL3 and BL4 so that the opposing edges coincide with the street lines defining 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, overlap exposure is performed inside the shot area, as disclosed in Japanese Patent Laid-Open No. 2-229423. It is necessary to make the exposure dose seamless. Since the method in this case is not an essential requirement of the present invention, the description is omitted.

Here, the configuration of the wafer holder 16 which can be tilted to an arbitrary angle and its surroundings will be described with reference to FIG. Z stage 1 on XY stage 18
7 is provided with a motor 21 to move the Z stage 17 to the optical axis A
Drive in the X direction. The wafer holder 16 is mounted on the Z stage 17 with its center substantially supported. The wafer holder 16 has a leveling drive unit 20
A, 20B are provided, and the wafer W on the holder 16 can be inclined at an arbitrary angle.

In order to control the tilt angle of the wafer W, a light projecting unit 19A for irradiating a light beam BPL having a non-exposure wavelength.
And a light receiving unit 19B for receiving the light beam BRL in which the light beam BPL is reflected on the wafer surface is provided with a focus and leveling sensor. The focal point of the light beam BPL from the focus and leveling sensor substantially coincides with the line on the wafer W including the point where the optical axis AX of the projection optical system PL passes.

The leveling drive units 20A and 20B are driven by a command from a leveling control system 53 which determines the tilt amount of the wafer holder 16 based on the leveling information from the light receiving unit 19B and the information from the main control unit 100. . Further, it is possible to maintain an appropriate tilt angle of the wafer W by always feeding back the leveling information from the light receiving section 19B.

Further, from the information from the focus and leveling sensors, it is also possible to obtain focus information for always positioning the position on the wafer W that intersects with the optical axis AX on the best imaging plane of the projection optical system. In this case, the light receiving unit 19
Z stage control system 54 based on the position information obtained in B
By driving the motor 21 according to a command from the
The Z stage 17 is driven in the direction of the optical axis AX.

The light beam BPL has a rectangular irradiation area A defined by the opening AP of the blind as shown in FIG.
The wafer W is irradiated with slit-shaped light SLI inclined by about 45 ° with respect to P ′. As a result, the chip regions CP1 to CP already formed on the wafer W
The inclination of the wafer W can be controlled without being affected by the directionality of the circuit pattern in P4. Although only two points are shown for the sake of convenience, it is needless to say that driving at three points is better.

Next, the operation of this example of the apparatus will be described. The sequence and control are managed by the main control unit 100 as shown in FIG. The basic operation of the main control unit 100 is based on scan exposure based on input of position information and yaw information from the laser interferometers 30 and 33, input of speed information from a tachogenerator in the drive systems 51 and 52, and the like. Sometimes, the reticle stage 14 and the XY stage 18 are relatively moved while maintaining a predetermined speed ratio and keeping a relative positional relationship between the reticle pattern and the wafer pattern within a predetermined alignment error.

The main controller 100 of the present apparatus example performs the progressive focus exposure method in addition to its operation, so that the best image plane of the projection optical system PL and the transfer area on the wafer W are relatively moved. The projection optical system P is tilted and the central portion of the transfer area is substantially centered.
The scanning exposure is performed while the focus state of the pattern image of the reticle is continuously or discretely changed according to the position in the one-dimensional scanning direction in the irradiation region by being positioned at or near the best imaging plane of L. As described above, the leveling control system 5
3 and the Z stage control system 54 is interlockingly controlled.

FIG. 4 is a diagram schematically showing an exposure method using the present apparatus example. Positions 1 to 9 in the circuit pattern IR on the reticle R correspond to positions 1 to 9 on the wafer W, respectively, and the wafer W is inclined relative to the pattern IR. Here, for convenience, the circuit pattern IR is displayed directly above the wafer W, and the projection magnification of the circuit pattern IR onto the wafer W is shown as 1. Further, three light fluxes of LR, LC and LL among the exposure light fluxes defined by the single aperture AP are shown.

The light beams LR and LL of these three light beams are:
The optical axis AX is defined by the edges of the blades BL1 and BL2 shown in FIG.
Are located almost symmetrically with respect to the center. The width of the light beams LR and LL corresponds to the width of the opening AP in the X direction, and represents the irradiation range of the exposure light beam in the scanning direction. Within this irradiation range, the intensity distribution of the exposure light beam is almost uniform. The light flux LC has a principal ray that passes through substantially the center of the irradiation range of the exposure light flux, and this principal ray is assumed to coincide with the optical axis AX of the projection optical system PL.

Further, the best imaging plane of the projection optical system PL is indicated by a broken line BF. This scanning exposure is performed on the XY stage 1
8 is driven in the X direction and at the same time the Z stage 17 is moved to the optical axis A.
Driving in the X direction, control is performed such that the approximate center of the irradiation area of the wafer W (coincident with the approximate center of the irradiation range of the exposure light beam) is always located on the best imaging plane BF of the projection optical system PL.

At this time, the width of the irradiation area (exposed area) AP 'on the wafer W in the scanning direction of the scanning exposure is Da
p, Dap · sin θ1 ≧ Δ, where θ1 is the inclination angle between the irradiation area AP ′ on the wafer W and the best imaging plane BF, and ΔZ1 is the width (DOF) of the depth of focus of the projection optical system PL in the optical axis direction.
At least one of the width Dap of the irradiation region and the inclination angle θ1 is adjusted so as to satisfy the relationship of Z1. still,
Generally, the theoretical depth of focus is ΔZ1 = λ / NA
² (λ: exposure wavelength, NA: numerical aperture of the projection optical system).

FIG. 4 shows the positional relationship between the wafer W and the pattern IR with respect to the exposure light beam immediately after the start of the scanning exposure.
In the state shown in FIG. 7A, focusing on a position 2 in the circuit pattern IR, the position 2 has just entered the irradiation range of the exposure light beam. However, in this state, the image at position 2 on the corresponding wafer W is in a defocused state deviated from the best imaging plane BF, and the intensity distribution of the projected image has a gentle peak.

FIG. 4B shows a state in which the scanning exposure is further advanced.
Therefore, the position 2 on the wafer W is located on the best imaging plane BF. In this state, the image at position 2 is in the best focus state, and the peak of the intensity distribution of the image is sharp. When the wafer W moves to the position shown in FIG.
Is a defocused state that is deviated from the best imaging plane BF, which is the opposite of the state shown in FIG. 4A, and the peak of the image intensity distribution is gentle.

FIG. 5 shows the distribution of the amount of exposure applied to the position 2 on the wafer W in the optical axis AX direction (Z direction) by the above scanning exposure (constant speed scan). That is, the exposure amount at the position 2 is substantially uniform in the range of Dap · sin θ1 in the Z direction (the depth of focus DOF). FIG. 6 shows the intensity distribution of the image given at position 2 as a result. The intensity distributions ER, EC, and EL are the luminous fluxes LR and L, respectively.
C, LL represents the image intensity obtained, and the intensity distribution E represents the integrated value of the image intensity obtained by the exposure light beam including the light beams LR, LC, LL.

In this case, since the position 2 is irradiated with the light beam (receives light energy) throughout the irradiation range of the exposure light beam, the integrated intensity distribution E has a gentle peak distribution. . Therefore, the width W having an intensity equal to or more than the exposure amount Eth for exposing (completely removing) the photoresist on the wafer W is relatively wide as shown in the drawing. In order to narrow the width W, the intensity distribution of the rectangular illumination light flux may be maximized at least at two points in the one-dimensional scanning direction of scanning exposure.

For this reason, for example, as shown in FIG.
Structure that shields the central part of P from light (double slit-shaped opening)
Reticle blind mechanism. This is one in which the blade BL4 of the four blades of the blind mechanism 10 is shaped so as to have a light shielding piece extending in the Y direction so as to shield the central portion of the opening AP with a predetermined width in the X direction. It is.

When such a blind mechanism is used,
Position 2 on wafer W by scanning exposure (constant speed scan)
FIG. 8 shows the distribution of the amount of exposure irradiated on the optical axis AX direction (Z direction). That is, the exposure amount at the position 2 is Z
Range of Dap · sin θ1 (direction of depth of focus DO
F) has the same strength at two places near both ends. Therefore, it is possible to give strength only to portions corresponding to the light beams LR and LL of the exposure light beam shown in FIG.

When the above-mentioned scanning exposure (constant speed scan) is performed using this light beam, the intensity distribution of an image obtained at an arbitrary position (for example, the above-mentioned position 2) on the wafer W is as shown in FIG. become. The intensity distributions ER 'and EL' are respectively the light flux L
This is the intensity distribution of the image given by R and LL, and the intensity distribution E 'is obtained by integrating the intensity distributions ER' and EL '.
At this time, the intensity distribution E 'has a sharper peak than the intensity distribution E shown in FIG. 6, and has a width W' having an intensity equal to or more than the exposure amount Eth for exposing (completely removing) the photoresist on the wafer W. Can be smaller than the width W shown in FIG.

Further, the intensity distribution of the rectangular illumination light flux may be maximized at three points in the one-dimensional scanning direction of scanning exposure. For this purpose, a reticle blind mechanism having a blade whose opening is formed as three slits is used as in the case shown in FIG. In this case, similarly, the distribution of the exposure amount applied to the position 2 on the wafer W by the scanning exposure in the direction of the optical axis AX is as shown in FIG. In other words, the exposure amount at the position 2 has almost the same intensity at a total of three places, that is, the vicinity of the best imaging plane BF and two places near both ends of the range of Dap · sin θ1 in the Z direction (the depth DOF width DOF). It is in a state.

Accordingly, the exposure light flux reaching the wafer W is shown in FIG.
Only the light fluxes corresponding to the light fluxes LR, LC, LL shown in FIG. The light beams LR and LL are set to be substantially symmetric with respect to the light beam LC having the same optical axis as the optical axis AX of the projection optical system. Even when scanning exposure is performed with a light beam having the maximum intensity distribution at three locations within such an irradiation range, the intensity distribution of the image projected on the wafer W should have a sharper peak than the intensity distribution E shown in FIG. become. Therefore, the width of the projected image can be made smaller than the width W shown in FIG.

When the light intensity of the illumination light flux is almost the same, comparing the intensity distribution of the rectangular illumination light flux at two locations and three locations in the one-dimensional scanning direction of scanning exposure,
In the case of three locations, the moving speed of the XY stage can be increased, and the throughput is higher. That is, conventional USP.4,
The effect opposite to that of the progressive focus exposure method known as 869,999 etc. can be obtained.

In the above example, the blade of the blind mechanism is provided with a light shielding piece. However, in addition to this, the size and shape corresponding to the region to be shielded at a position substantially conjugate with the circuit pattern IR in the optical path. The same effect can be obtained even with a configuration in which a light reducing member such as the ND filter is provided.

[0048]

As described above, according to the present invention, an image of a part of a circuit pattern projected on a photosensitive substrate is formed in a direction crossing the one-dimensional scanning direction within the circular projection field of the projection optical system. Since the scanning exposure is limited to the extended linear slit area (rectangular area), when performing the progressive focus exposure method that increases the depth of focus, simply use the image plane of the projection optical system and the substrate. With a very simple operation such as tilting the surface of the exposed area of the substrate relative to the direction of the one-dimensional scanning by a predetermined amount, a substantially uniform depth of focus for one shot area on the substrate can be obtained. It is possible to transfer the circuit pattern with the enlargement effect.

According to the invention, the width of the linear slit area of the image of a part of the circuit pattern limited in the circular projection field in the one-dimensional scanning direction is optimized, and the one-dimensional area of such slit area is optimized. A number related to the scanning direction (for example, 1 to
By the optimization of 3), a remarkable effect that a scanning exposure method with improved throughput while achieving a desired resolution can be realized.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a projection exposure apparatus suitable for carrying out the present invention.

FIG. 2 is a plan view showing an arrangement of blades that form a reticle blind.

3A is a diagram illustrating a schematic configuration around a wafer holder, and FIG. 3B is a diagram illustrating a state of irradiation of a light beam from a leveling sensor onto a wafer.

FIG. 4 is a view schematically showing an exposure method using a projection exposure apparatus suitable for the present invention.

FIG. 5 is a diagram showing a distribution in the optical axis direction of an exposure amount applied to an arbitrary position on a wafer by scanning exposure.

FIG. 6 is a diagram showing an intensity distribution of an image given to an arbitrary position on a wafer when a progressive exposure method is performed by the scanning exposure method of the present invention.

FIG. 7 is a plan view showing another example of the blade constituting the reticle blind.

FIG. 8 is a diagram showing a distribution in the optical axis direction of an exposure amount applied to an arbitrary position on a wafer by scanning exposure.

FIG. 9 is a diagram showing an intensity distribution of an image given to an arbitrary position on a wafer when scanning exposure is performed using another blade example.

FIG. 10 is a diagram showing a distribution in the optical axis direction of an exposure amount applied to an arbitrary position on a wafer by scanning exposure.

FIG. 11 is a diagram illustrating the concept of a conventional step-and-scan exposure method.

[Explanation of symbols]

 14 ... Mask stage 16 ... Substrate holder 17 ... Z stage 18 ... XY stage 20A, 20B ... Leveling drive unit 21 ... Motor 53 ... Leveling control system 54 ... Z stage control system PL ... Projection optical system BF ... Best result of projection optical system Image plane R ... Reticle (mask) IR ... Circuit pattern W ... Photosensitive substrate

Claims (15)

[Claims] 1. A part of a circuit pattern on a mask is projected onto a sensitive substrate through a projection optical system, and the mask and the substrate are moved at a speed ratio corresponding to a projection magnification of the projection optical system. A method of scanning and exposing an entire image of a circuit pattern of the mask on the substrate by relatively one-dimensionally scanning, wherein an image of a part of the circuit pattern projected on the substrate is a circle of the projection optical system. The mask is formed by a rectangular or slit-shaped distribution of exposure illumination light so as to be limited to a rectangular or slit region that extends linearly in a direction intersecting with the direction of the one-dimensional scanning in substantially the center of the projection visual field. During the relative one-dimensional scanning between the mask and the substrate, the image plane in the rectangular or slit area by the projection optical system and the surface of the exposed portion on the substrate are projected by the projection optical system. Depth of focus As it continues substantially coincides with the inner scanning exposure method characterized by controlling the relative tilt and distance between the substrate and the imaging plane by the projection optical system. 2. A non-exposure beam for detecting defocus and tilt is obliquely projected onto the surface of the exposed portion on the substrate corresponding to the rectangular or slit region, and the reflected beam is photoelectrically converted. 2. The method according to claim 1, wherein the relative tilt and distance between the image plane formed by the projection optical system and the substrate are controlled by detecting. 3. The substrate is mounted on a substrate holder that is tiltable and Z-movable on an XY stage that is two-dimensionally movable in an XY plane, and the XY is used for one-dimensional scanning of the substrate. While moving the stage at a constant speed in the one-dimensional scanning direction in the XY plane, the substrate holder is moved in the Z direction perpendicular to the XY plane based on the photoelectrically detected defocus for focusing the substrate. The method of claim 2 wherein: 4. The substrate holder comprises a reference mark provided so as to be arranged within a circular projection field of the projection optical system, and the reference mark is detected via the projection optical system and the mask. The method of claim 3, wherein the position of the mask in the moving coordinate system of the XY stage is defined thereby. 5. The method according to claim 3, wherein the projection optical system is constituted by only a refracting element or a combination of a refracting element and a reflecting element so as to be telecentric on both sides. 6. The fly-eye lens that receives light from a predetermined light source to generate a large number of secondary light sources on the exit side, and the light from the large number of secondary light sources enters the exposure illumination light. And a condenser lens that irradiates a predetermined irradiation surface with a substantially uniform distribution, and a rectangular or slit-shaped opening that is arranged on the irradiation surface and linearly extends in a direction orthogonal to the one-dimensional scanning direction. 6. The method of claim 5, wherein the illumination system comprises a blind mechanism having a section. 7. The size of the circuit pattern on the mask is defined by the longitudinal direction orthogonal to the one-dimensional scanning direction of the rectangular or slit-shaped distribution of the exposure illumination light defined by the opening of the blind mechanism. 7. The method according to claim 6, wherein the method is changed according to the shape, the shape, and the arrangement. 8. A shot on the substrate is defined as an edge in a longitudinal direction orthogonal to the one-dimensional scanning direction of a rectangular or slit-shaped distribution of the exposure illumination light defined by an opening of the blind mechanism. 7. The method according to claim 6, wherein the position is matched with the position of a street line that divides the area.
The method described in the section. 9. A dimension of a shot area on the substrate to which an entire image of the circuit pattern of the mask is transferred in a non-scanning direction orthogonal to the one-dimensional scanning direction is rectangular or slit of the exposure illumination light. 4. The method according to claim 3, wherein when the size distribution is larger than the maximum dimension in the non-scanning direction, overlapping exposure is performed inside the shot area to make the exposure amount seamless. 10. A part of a circuit pattern on a mask is projected onto a sensitive substrate through a projection optical system, and the mask and the substrate are moved at a speed ratio corresponding to a projection magnification of the projection optical system. A method of scanning and exposing an entire image of a circuit pattern of the mask on the substrate by relatively one-dimensionally scanning, wherein an image of a part of the circuit pattern projected on the substrate is a circle of the projection optical system. A plurality of slit-shaped illumination light fluxes arranged at a predetermined interval in the one-dimensional scanning direction so as to be limited to a plurality of slit-shaped regions extending in a direction crossing the one-dimensional scanning direction in the projection visual field. To the mask, and during the relative one-dimensional scanning between the mask and the substrate, the image plane in the slit-shaped region by the projection optical system and the surface of the exposed portion on the substrate. Of the projection optical system Scanning exposure method, wherein a so continue substantially coincides with the point depth, controls the relative inclination and spacing between the substrate and the imaging plane by the projection optical system. 11. The substrate is mounted on a substrate holder that is tiltably and Z-movably provided on an XY stage that is two-dimensionally movable in an XY plane, and is used for one-dimensional scanning of the substrate. 11. The XY stage according to claim 10, wherein the substrate holder is moved in the Z direction perpendicular to the XY plane for focusing the substrate while moving the XY stage at a constant velocity in the one-dimensional scanning direction. Method. 12. The substrate holder comprises a reference mark that is provided so as to be arranged within a circular projection field of the projection optical system, and the reference mark is detected via the projection optical system and the mask. 12. The method of claim 11, wherein the position of the mask in the moving coordinate system of the XY stage is defined thereby. 13. The method according to claim 11, wherein the projection optical system comprises a birefringent element or a combination of a refracting element and a refracting element so as to be telecentric on both sides. 14. The fly-eye lens for generating a plurality of secondary light sources on the exit side of the plurality of slit-shaped illumination light fluxes, and the light from the plurality of secondary light sources. A condenser lens which irradiates a given irradiation surface with a substantially uniform distribution and irradiates it, and a plurality of slit-like lenses which are arranged on the irradiation surface and linearly extend in a direction orthogonal to the one-dimensional scanning direction. 14. A method according to claim 13, characterized in that it is illuminated from an illumination system including a blind mechanism having an opening. 15. The size, shape, and arrangement of the circuit pattern on the mask in the longitudinal direction orthogonal to the one-dimensional scanning direction in the distribution of the plurality of slit-shaped illumination light fluxes defined by the opening of the blind mechanism. The method according to claim 14, wherein the method is changed according to