JP2830869B2 - Circuit element manufacturing 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 method for manufacturing a circuit element using a projection exposure apparatus used in a lithography step in the process of manufacturing a semiconductor element, a liquid crystal display element 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 account the original depth of focus of the projection optical system and minute irregularities on the photosensitive substrate. The best imaging plane of the projection optical system comes to come.

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 view for explaining the concept of the step-and-scan method. Here, the arrangement of shot areas (one chip or multi-chip) in the X direction on the wafer W is determined by the arc-shaped 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,
, And the same S & S exposure is performed in the order of SA12.

In the S & S type aligner disclosed in the above document, an image of the reticle pattern illuminated by the arc-shaped slit illumination light RIL is formed on the wafer W via a 投影 -fold reduction projection optical system. Therefore, X of the reticle stage
The scanning speed in the direction is precisely controlled to be four 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 reflection reduction projection system is disclosed in, for example, US Pat. No. 4,747,678.

[0007]

However, it is impossible to apply the same progressive focus exposure method as the step-and-repeat method as it is to the step-and-scan apparatus disclosed in the above 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.

Accordingly, the first object of the present invention is to provide a method of manufacturing a circuit element by scanning exposure such as a step-and-scan method to which a conventional progressive focus exposure method can be easily applied.
It is a second object of the present invention to provide a method of manufacturing a circuit element capable of improving throughput in the case of scanning exposure to which a progressive focus exposure method is applied, as compared with the conventional method.

[0010]

SUMMARY OF THE INVENTION Therefore, according to the present invention, a part of a circuit pattern formed on a mask (reticle R) is placed on a sensitive substrate (wafer W) through a reduction projection system (PL). A projection system (PL) that projects a mask (R) and a substrate (W) at a speed ratio according to a reduction ratio while projecting.
The present invention is applied to a method for manufacturing a circuit element including a lithography step of scanning and exposing a whole image of a circuit pattern on a predetermined region on a substrate by one-dimensionally scanning a projection field of view (IF).
In the present invention, the partial image of the circuit pattern projected on the substrate (W) is elongated in a direction orthogonal to the one-dimensional scanning direction and has a rectangular shape or a slit having a substantially constant width in the one-dimensional scanning direction. The mask (R) and the substrate (W) are reduced so that the relative positional relationship between the circuit pattern of the mask (R) and the predetermined region of the substrate (W) is kept within a predetermined alignment error in a state where the shape is limited. The relative scanning in the one-dimensional scanning direction at a speed ratio according to the rate, and during the relative scanning, the one-dimensional scanning direction of the partial image of the circuit pattern restricted to a rectangular or slit shape on the substrate (W) The focus difference between the best image plane position near each of the two ends and the surface position of the substrate corresponding to the vicinity of the both ends is determined by the reduction projection system (P
L) controlling the state of focusing or leveling of the substrate (W) so as to be maintained within the range of the depth of focus of (L).

Further, according to the invention described in claim 2, the reduction projection system defined in claim 1 is a combination of a refraction element and a reflection element, or a double-sided telecentric reduction projection optical system composed of only a refraction element. And a circular projection field of view (IF) centered on the optical axis. Further, in the invention according to claim 3, in order to obtain a partial image of the rectangular or slit circuit pattern defined in claim 2, exposure energy having a rectangular or slit distribution is applied to the mask (R). Irradiation is performed, and the distribution of the exposure energy is controlled by the optical axis (A) within the circular projection field of view (IF) of the reduction projection optical system (PL).
X) It was arranged to include the center.

According to a fourth aspect of the present invention, a part of a circuit pattern formed on a mask (reticle R) is projected onto a sensitive substrate (wafer W) through a projection optical system (PL) while the mask (reticle R) is projected. R) and the substrate (W) are one-dimensionally scanned with respect to the projection visual field (IF) of the projection optical system (PL) at a speed ratio according to the projection magnification, and the entire circuit pattern is placed in a predetermined area on the substrate (W). The present invention is applied to a method for manufacturing a circuit element including a lithography step of scanning and exposing an image. In the present invention, the partial image of the circuit pattern projected on the substrate (W) is elongated in a direction orthogonal to the one-dimensional scanning direction,
The mask stage (14) on which the mask (R) is mounted and the substrate stage (16 to 16) on which the substrate (W) is mounted in a state limited to a rectangular shape or a slit shape having a substantially constant width in the one-dimensional scanning direction. 18) relative scanning in the one-dimensional scanning direction at a speed ratio according to the projection magnification (for example, 1/5);
During the relative scanning, the substrate (W) is moved to the image plane (B) of the projection optical system in accordance with the scanning position of the substrate stage (16 to 18).
And F) continuously finely moving in a direction perpendicular to the direction.

According to a fifth aspect of the present invention, the projection optical system (PL) defined in the fourth aspect is a combination of a refracting element and a reflecting element, or a double-sided telecentric reduction comprising only a refracting element. The projection optical system had a circular projection field of view (IF) centered on the optical axis (AX). Further, in the invention according to claim 6, the partial projection image of the circuit pattern having a rectangular or slit distribution defined in claim 5 is converted into an optical axis (IF) within the circular projection field of view (IF) of the reduction projection optical system (PL). AX) Restricted to the range including the center.

[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.
Or, since it is configured to be limited to a plurality of parallel slit regions, the best imaging surface of the projection optical system and the surface of the region to be exposed on the substrate are scanned while being inclined relative to the one-dimensional scanning direction as necessary. Exposure becomes possible, and the manufacture of circuit elements to which the progressive focus exposure method for expanding the apparent depth of focus is easily applied can be realized.

When the progressive focus exposure method is performed, the relative inclination between the image plane in the slit area limited in the circular visual field of the projection optical system and the surface of the exposure area on the substrate is determined by the projection optical system. 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 range of the depth of focus of the slit area, the slit area is substantially uniform in the longitudinal direction (non-scanning direction). The effect of increasing the depth of focus can be obtained. The configuration and operation of a projection exposure apparatus suitable for manufacturing circuit elements by a scanning exposure method in a lithography process will be described below with reference to the drawings.

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 transmission of the illumination light is disposed. 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. . On the rear focal plane of the lens system 9, movable blades BL1 and BL of the reticle blind mechanism 10 are provided.
2, BL3 and BL4 are arranged as shown in FIG. 4
The blades BL1, BL2, BL3, and BL4 are independently moved by the drive system 50, respectively. 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 determined 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 slightly 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 a 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 respectively to one end of the. 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 via the projection optical system PL, reticle R, condenser lens 13, lens systems 11, 9 and beam splitter 8, and the XY stage 18 Is used to define the position of the reticle R in the coordinate system of, or to define the position of the detection center of each alignment system 40, 41. However, these alignment systems are not essential requirements 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 patterns 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 and 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. With this configuration, it is possible to easily cope with a change in the size of the shot area in the Y direction. When the dimension of one shot area in the Y direction is equal to or larger than the maximum dimension of the opening AP in the Y direction, as shown in JP-A-2-229423, overlapping exposure is performed inside the shot area. It is necessary to make the exposure amount seamless. Since the method in this case is not an essential requirement of the present invention, further 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, a motor 21 is provided, and the Z stage 17 is
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 amount of tilt 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, by always feeding back the leveling information from the light receiving unit 19B, it is possible to maintain an appropriate inclination angle of the wafer W.

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 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 light is irradiated onto the wafer W as slit-shaped light SLI inclined at, for example, 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 control unit 100 of the present apparatus example performs the progressive focus exposure method in addition to the operation thereof, so that the best imaging plane of the projection optical system PL and the transfer area on the wafer W are relatively determined. The projection optical system P is tilted and almost in the center of the transfer area.
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 relatively inclined with respect 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. Also, three light beams LR, LC, and LL among the exposure light beams 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 beam LC has a principal ray passing substantially through the center of the irradiation range of the exposure light beam, and this principal ray coincides 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 in the X direction and at the same time, the Z stage 17
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 irradiation area width Dap 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.
And 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 defocus state shifted from the best imaging plane BF opposite to the state of FIG. 4A, and the peak of the intensity distribution of the image is a gentle state.

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 luminous fluxes LR, 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 light beam irradiation range, 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 reduce the width W, the intensity distribution of the rectangular illumination light beam may be maximized at at least two places in the one-dimensional scanning direction of the scanning exposure.

For this reason, for example, as shown in FIG.
Structure shielding 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 in the direction (width DO of DOF)
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
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 beam may be maximized at three places in the one-dimensional scanning direction of the 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 beams corresponding to the light beams LR, LC, and 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.

Incidentally, when the light intensity of the illumination light beam is substantially the same, the intensity distribution of the rectangular illumination light beam is compared with two cases and three cases in the one-dimensional scanning direction of the 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,
An effect opposite to that of the progressive exposure method known at 869,999 or the like can be obtained.

In the above example, an example is shown in which the blade of the blind mechanism is provided with a light-shielding piece. However, the size and shape of the light-shielding piece are set at a position almost conjugate with the circuit pattern IR in the optical path. The same effect can be obtained by providing a dimming member such as an ND filter.

[0048]

As described above, according to the present invention, an image of a part of a circuit pattern projected on a photosensitive substrate extends in a direction intersecting a one-dimensional scanning direction within a projection field of view of a projection optical system. Since the scanning exposure is limited to a linear slit area (rectangular area), when the progressive focus exposure method for increasing the depth of focus is performed, simply the projection surface of the projection optical system and the image plane on the substrate are used. By adding a very simple operation such as tilting the surface in the exposure area relative to the surface in the one-dimensional scanning direction by a predetermined amount, the depth of focus is substantially uniform over the entire one shot area on the substrate. The circuit pattern can be transferred with the effect.

Further, according to the present invention, the width of the linear slit area (rectangular area) of the partial image of the circuit pattern in the one-dimensional scanning direction can be optimized, and the width of the partial image in the slit area can be optimized in the one-dimensional scanning direction. Optimize intensity distribution (2-
(Maximization of three places) has a remarkable effect that a circuit element can be manufactured with improved throughput while achieving a desired resolution.

[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 constituting 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 illustrating an intensity distribution of an image given to an arbitrary position on a wafer when scanning exposure is performed using another example of a blade.

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]

 Reference Signs List 14 mask stage 16 substrate holder 17 Z stage 18 XY stage 20A, 20B leveling drive 21 motor 53 leveling control system 54 Z stage control system PL projection optical system R reticle (mask) IR Circuit pattern W: photosensitive substrate

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁶ , DB name) H01L 21/027

Claims (6)

(57) [Claims] 1. A method according to claim 1, wherein a portion of the circuit pattern formed on the mask is projected onto a sensitive substrate through a reduction projection system.
A lithography step of one-dimensionally scanning the mask and the substrate with respect to a projection field of view of the reduction projection system at a speed ratio corresponding to a reduction ratio, and scanning and exposing the entire image of the circuit pattern on a predetermined region on the substrate; In a method for manufacturing a circuit element, a partial image of the circuit pattern projected on the substrate is elongated in a direction orthogonal to the one-dimensional scanning direction, and has a substantially constant width in the one-dimensional scanning direction. In a state limited to the shape or the slit shape, the mask and the substrate are adjusted according to the reduction ratio so that the relative positional relationship between the circuit pattern of the mask and a predetermined region of the substrate is suppressed within a predetermined alignment error. Performing relative scanning in the one-dimensional scanning direction at a speed ratio; and during the relative scanning, a partial image of the circuit pattern limited to a rectangular shape or a slit shape on the substrate. Each focus difference between the best image plane position near each end in the one-dimensional scanning direction and the surface position of the substrate corresponding to the vicinity of both ends is maintained within the range of the depth of focus of the reduction projection system. Controlling the focus or leveling state of the substrate. 2. The reduction projection system is a combination of a refraction element and a reflection element, or a double-sided telecentric reduction projection optical system composed of only a refraction element, and has a circular projection field centered on the optical axis. The method according to claim 1, characterized in that: 3. A method for irradiating the mask with exposure energy distributed in a rectangular or slit shape in order to make a partial image of the circuit pattern projected on the substrate into a rectangular or slit shape. 3. The method according to claim 2, wherein the distribution is arranged so as to pass through the center of the optical axis within the circular projection field of the reduced projection optical system. 4. While projecting a part of a circuit pattern formed on a mask onto a sensitive substrate through a projection system, the mask and the substrate are projected onto a projection field of the projection system at a speed ratio according to a projection magnification. A method for manufacturing a circuit element including a lithography step of scanning and exposing the entire image of the circuit pattern on a predetermined region on the substrate by performing one-dimensional scanning on the substrate, wherein the partial image of the circuit pattern projected on the substrate is A mask stage on which the mask is placed and the substrate are placed in a state of being elongated in a direction perpendicular to the direction of the one-dimensional scanning and limited to a rectangular shape or a slit shape having a substantially constant width in the one-dimensional scanning direction. Relative scanning in a one-dimensional scanning direction with a substrate stage to be placed at a speed ratio according to the projection magnification; Circuit device manufacturing method characterized by comprising the step of continuously or discretely fine moving said substrate on an imaging plane and a direction perpendicular of the projection system in accordance with the scanning speed. 5. The projection system is a combination of a refraction element and a reflection element, or a double-sided telecentric reduction projection optical system composed of only a refraction element, and has a circular projection field centered on the optical axis. The method according to claim 4, characterized in that: 6. A rectangular or slit distribution of a partial image of the circuit pattern projected on the substrate is limited to a range including an optical axis center within a circular projection field of view of the reduction projection optical system. The method according to claim 5, characterized in that: