JP3161430B2 - Scanning exposure method, scanning exposure apparatus, and element manufacturing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a scanning exposure method and a scanning exposure apparatus used in a lithography step in the process of manufacturing a semiconductor device, a liquid crystal display device 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 progressive focus exposure method similar to the step-and-repeat method 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 perpendicular to the optical axis of the projection optical system (X or Y direction)
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 expanding the depth of focus but also lowers the resolution of the image.

Accordingly, a first object of the present invention is to provide a scanning exposure method and apparatus such as a step-and-scan method to which a conventional progressive focus exposure method can be easily applied, and to which a progressive focus exposure method is further applied. It is a second object of the present invention to provide a scanning exposure method and apparatus capable of obtaining the effect of increasing the depth of focus over the entire case.

[0010]

In order to solve the above problems, the present invention provides, for example, a mask (R) for illuminating light.
When the substrate (W) is moved relative to the illumination light passing through the projection optical system (PL) in synchronization with the relative movement of the substrate (W), the substrate (W) is scanned and exposed on the substrate (W). The first area (AP ′) of the illumination light including the optical axis (AX) in the field of view (IF) of the projection optical system (PL) and the substrate (W) being moved during the scanning exposure. X) is limited to a rectangular shape or a slit shape linearly extending along a second (Y) direction orthogonal to the direction, and the irradiation area (A
P ′) and the image plane of the projection optical system (PL) and the substrate (W)
The substrate (W) is driven at three points in the direction of the optical axis of the projection optical system (PL) in order to adjust the positional relationship with the projection optical system (PL).

In order to solve the above-mentioned problem, the present invention relates to, for example, an illumination light passing through a projection optical system (PL) in synchronization with a relative movement of a mask (R) with respect to the illumination light. When the substrate (W) is scanned and exposed by relatively moving the substrate (W), the projection optical system (P
First, the substrate (W) is moved within the field of view (IF) of L).
A beam (SLI) whose projection position is set is projected on the substrate along a direction intersecting both the (X) direction and the second (Y) direction orthogonal to the (X) direction, and the projection optical system (PL)
The positional relationship between the image forming plane and the substrate (W) in the optical axis direction of the projection optical system is detected.

In order to solve the above-mentioned problem, the present invention relates to, for example, an illumination light passing through a projection optical system (PL) in synchronization with a relative movement of a mask (R) with respect to the illumination light. When the substrate (W) is scanned and exposed by relatively moving the substrate (W), a beam is projected into an irradiation area (AP ′) of the illumination light on the substrate (W) during the scanning exposure,
The reflected beam (BRL) is photoelectrically detected and the irradiation area (A
Information on the tilt of the substrate (W) within P ′) is obtained, and the image plane of the projection optical system (PL) and the substrate (W) are relatively moved based on the obtained information. .

In order to solve the above-mentioned problems, the present invention relates to, for example, an illumination light passing through a projection optical system (PL) synchronized with a relative movement of a mask (R) with respect to the illumination light. When scanning and exposing the substrate (W) by relatively moving the substrate (W), a predetermined point on the substrate (W) is present in the irradiation area (AP ′) of the illumination light during the scanning exposure. In the meantime, by changing the position of the predetermined point in the optical axis (AX) direction of the projection optical system (PL), the predetermined point is irradiated with illumination light at each of different positions in the optical axis direction. I have.

[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 a progressive focus exposure method that enlarges the apparent depth of focus can be easily 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 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 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.

A large number of 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, 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, 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 reticle pattern image is continuously or discretely changed according to the position in the one-dimensional scanning direction in the irradiation area by being positioned at or near the best image forming plane 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 / NA2
(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. As described above, according to the above example, a part of the image of the circuit pattern projected on the photosensitive substrate is formed into a linear shape extending in a direction intersecting the one-dimensional scanning direction in the circular projection field of view of the projection optical system. The scanning exposure is limited within the slit area (rectangular area), so if the progressive focus exposure method for increasing the depth of focus is to be performed, the image forming plane of the projection optical system and the exposure area on the substrate are simply used. By adding a very simple operation of inclining the inner surface relative to the direction of the one-dimensional scan by a predetermined amount, an almost uniform depth-of-focus expanding effect can be achieved over the entire one shot area on the substrate. The circuit pattern can be transferred. According to the above example, the width of a part of the image of the circuit pattern limited in the circular projection field of view is optimized in the one-dimensional scanning direction of the linear slit region, and the one-dimensional scanning direction of such a slit region is determined. By optimizing the number (for example, 1 to 3), a remarkable effect that a scanning exposure method with an improved throughput while achieving a desired resolution can also be achieved.

[0048]

As described above, according to the present invention, the positional relationship between the image plane of the projection optical system and the substrate can be controlled to a desired state even during scanning exposure, and the progressive focus can be easily applied to scanning exposure. An exposure method can be applied.

Further, according to the present invention, even when the progressive focus exposure method is applied to the scanning exposure, for example, the exposure within the one shot area on the substrate is performed with a substantially uniform depth of focus expansion effect. It can be performed.

[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]

 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 connection of projection optical system Image surface R: reticle (mask) IR: Circuit pattern W: Photosensitive substrate

Continuation of front page (56) References JP-A-2-229423 (JP, A) JP-A-63-12134 (JP, A) JP-A-3-40417 (JP, A) JP-A-62-208629 (JP) JP-A-63-58930 (JP, A) JP-A-4-277612 (JP, A) JP-A-2-28312 (JP, A) JP-A-2-57333 (JP, B2) PROCEEDINGS OF SP IE, VOL. 922, OPTICAL / LASER MICROLITHOG RAPHY P. 256-269 (58) Field surveyed (Int. Cl. ⁷ , DB name) H01L 21/027 G03F 7/20 INSPEC (DIALOG)

Claims (34)

(57) [Claims] 1. A method of scanning and exposing a substrate by relatively moving a substrate with respect to said illumination light passing through a projection optical system in synchronization with a relative movement of a mask with respect to the illumination light. The irradiation area of the illumination light on the substrate includes a second direction orthogonal to a first direction including the optical axis in the field of view of the projection optical system and moving the substrate during the scanning exposure. Limiting to a rectangular or slit shape extending linearly, during the scanning exposure, in order to adjust the positional relationship between the imaging surface of the projection optical system and the substrate in the irradiation area, the projection optical system A scanning exposure method, wherein the substrate is driven at three points in an optical axis direction. 2. The scanning exposure method according to claim 1, wherein the relative inclination between the image plane of the projection optical system and the substrate is adjusted by driving the substrate. 3. The method according to claim 1, wherein a beam is projected obliquely onto the substrate, and the driving of the substrate is controlled based on information obtained by photoelectrically detecting the reflected beam.
3. The scanning exposure method according to 1. 4. The method according to claim 1, wherein the driving of the substrate is feedback-controlled based on the obtained information so that an image forming plane of the projection optical system and the substrate coincide with each other substantially at the center of the irradiation area. The scanning exposure method according to claim 3, wherein: 5. A plane including the first direction and the optical axis of the projection optical system , and the second direction and an optical axis of the projection optical system.
The scanning exposure method according to claim 3, wherein the beam is projected onto the substrate from a direction intersecting both of the planes including : 6. The method according to claim 3, wherein a projection position of the beam on the substrate is set along a direction intersecting both the first direction and a second direction orthogonal to the first direction. The scanning exposure method according to any one of the preceding claims. 7. A method of scanning and exposing the substrate by relatively moving the substrate with respect to the illumination light passing through a projection optical system in synchronization with the relative movement of the mask with respect to the illumination light. A beam whose projection position is set along a direction that intersects both a first direction in which the substrate is moved in the field of view of the projection optical system and a second direction orthogonal to the first direction during scanning exposure is transmitted to the substrate. A scanning exposure method, wherein the projection is performed on an upper surface to detect a positional relationship between an imaging plane of the projection optical system and the substrate in an optical axis direction of the projection optical system. 8. The scanning exposure method according to claim 6, wherein the beam has a slit shape extending on the substrate along a direction intersecting both the first and second directions. . 9. beam projected onto the substrate, on the substrate, the distributed within a predetermined range with respect to the first direction DOO
The method according to any one of claims 3 to 8 , further comprising a distribution within a predetermined width in the second direction . 10. synchronously mask relative to the illumination light to relative movement, by relative movement of the substrate relative to the illumination light passing through the projection optical system, a method of scanning exposure of the substrate, wherein During scanning exposure, the imaging surface of the projection optical system and the substrate
Detecting the positional relationship of the projection optical system in the optical axis direction.
The substrate emits a beam that is projected onto the substrate for
A plane including a first direction to be moved and an optical axis of the projection optical system.
A plane, a second direction orthogonal to the first direction, and the projection light
Incident from a direction that intersects both the optical axis of the system and the plane containing the optical axis
And during the scanning exposure, the beam is irradiated on the substrate by the
Distributed within a predetermined width in one direction, and
A scanning exposure method characterized by being distributed within a predetermined width in a direction . 11. The scanning exposure method according to claim 3, wherein the beam is projected onto a part of an irradiation area of the illumination light within a field of view of the projection optical system. . 12. A method of scanning and exposing a substrate by relatively moving a substrate with respect to said illumination light passing through a projection optical system in synchronization with relative movement of a mask with respect to illumination light. During scanning exposure, a beam is projected into the irradiation area of the illumination light on the substrate, and the reflected beam is photoelectrically detected to obtain information on the inclination of the substrate in the irradiation area, and the obtained information is obtained. A scanning exposure method characterized by relatively moving an image forming surface of the projection optical system and the substrate based on the following. Wherein said during the scanning exposure, the plane including the optical axis of the projection optical system and the first direction in which the substrate is moved, and before
A second direction orthogonal to the first direction and an optical axis of the projection optical system;
13. The scanning exposure method according to claim 12, wherein the beam is projected onto the substrate from a direction intersecting both of the planes including : During 14. The scanning exposure, the beam is projected on the exposure area of the illumination light, on the substrate, when the substrate is distributed within a predetermined range with respect to the first direction to be moved together
Within a predetermined width in a second direction orthogonal to the first direction.
14. The method according to claim 12 or 13 , wherein the distribution is: During 15. The scanning exposure, while a predetermined point on the substrate is present in the irradiation region of the illumination light, the position of the predetermined point and about the optical axis of the projection optical system The scanning exposure method according to any one of claims 1 to 14, wherein the illumination light is applied to the predetermined points at different positions in the optical axis direction by changing the illumination light. 16. A method of scanning and exposing the substrate by relatively moving the substrate with respect to the illumination light passing through the projection optical system in synchronization with the relative movement of the mask with respect to the illumination light. during scanning exposure, while a predetermined point on the substrate is present in the irradiation region of the illumination light, by changing the position of the predetermined point and about the optical axis of the projection optical system, wherein A scanning exposure method comprising irradiating the illumination light to the predetermined points at different positions in the optical axis direction. 17. The scanning exposure method according to claim 15, wherein the position of the predetermined point in the optical axis direction changes within a range of a depth of focus of the projection optical system. 18. An irradiation area of the illumination light on the substrate, including an optical axis in a field of view of the projection optical system, and orthogonal to a first direction in which the substrate is moved during the scanning exposure .
The scanning exposure method according to any one of claims 6 to 17, wherein the shape is limited to a rectangular shape or a slit shape linearly extending along the second direction. 19. The projection optical system has a circular visual field, and the irradiation area of the illumination light moves the substrate during the scanning exposure about the optical axis of the projection optical system substantially in the circular visual field.
19. The scanning exposure method according to claim 1, wherein the scanning exposure method extends linearly in a second direction orthogonal to the first direction to be moved. 20. A substrate which is orthogonal to a first direction in which the substrate is moved during the scanning exposure according to a pattern on the mask.
A rectangular or slit-shaped illumination light in a second direction;
The length of an irradiation area is changed, The claim 1 characterized by the above-mentioned.
20. The scanning exposure method according to 19. 21. In a second direction orthogonal to a first direction in which the substrate is moved for scanning exposure, when a shot area on the substrate on which the pattern of the mask is transferred is larger than the illumination light, The scanning exposure method according to any one of claims 1 to 20, wherein overlap exposure is performed inside the shot area to make the exposure amount seamless. 22. A device manufacturing method using the method according to claim 1. 23. A projection optical system for projecting illumination light applied to a mask onto a substrate, and the mask and the substrate are relatively moved with respect to the illumination light to scan and expose the substrate. In the apparatus, a second direction orthogonal to a first direction in which the irradiation area of the illumination light on the substrate includes an optical axis thereof within a field of view of the projection optical system and the substrate is moved during the scanning exposure Limiting means for limiting to a rectangular shape or a slit shape extending linearly, during the scanning exposure, in order to adjust the positional relationship between the imaging surface of the projection optical system and the substrate in the irradiation area, A driving unit for driving the substrate at three points in the optical axis direction of the projection optical system. 24. The driving means drives the substrate such that an image forming surface of the projection optical system and an exposure surface of the substrate coincide with each other substantially at the center of the irradiation area of the illumination light. A scanning exposure apparatus according to claim 23. 25. A position detecting system for projecting a beam obliquely onto the substrate and photoelectrically detecting the reflected beam, wherein the driving means drives the substrate based on information obtained by the position detecting system. 25. The scanning exposure apparatus according to claim 23, wherein the scanning exposure is performed. 26. The method of claim 25, wherein the position detection system, a straight plane, and in the first direction including the optical axis of the projection optical system and the first direction
Of a plane including a second direction intersecting with the optical axis of the projection optical system.
26. The scanning exposure apparatus according to claim 25, wherein the beam is projected onto the substrate from a direction intersecting both . 27. The position detection system distributes a beam projected on the substrate along a direction intersecting both the first direction and a second direction orthogonal to the first direction on the substrate. The scanning exposure apparatus according to claim 25, wherein: 28. The apparatus according to claim 25, wherein the position detection system irradiates a part of an irradiation area of the illumination light with the beam in a field of view of the projection optical system. 3. The scanning exposure apparatus according to claim 1. 29. During the scanning exposure, the beam is projected onto the substrate by the position detection system, on the substrate, as well as distributed within a predetermined range with respect to the first direction in which the substrate is moved, the substrate Is orthogonal to the first direction in which
The scanning exposure apparatus according to any one of claims 25 to 28, wherein the scanning exposure apparatus is distributed within a predetermined width in the second direction . 30. A scanning exposure apparatus according to claim 23, wherein said projection optical system extends straight without bending its optical axis. 31. A mask stage for holding the mask
When measures a substrate stage for holding the substrate, a first drive system for moving the mask stage, a second drive system for moving the substrate stage, the position of the mask stage in the scanning exposure
A first interferometer for measuring the position of the substrate stage during the scanning exposure.
A second interferometer, wherein the projection optical system is a reduction system, and each of the mask stage and the substrate stage is
It moves at a speed corresponding to the projection magnification of the projection optical system.
Scanning according to any one of claims 23 to 30, characterized in that
Exposure equipment. 32. A reference mirror for the first interferometer and the reference mirror for the first interferometer.
2. A reference mirror for the interferometer is provided in the lens barrel of the projection optical system.
32. The device of claim 31, wherein 33. The projection optical system comprises only a refractive element.
A two-sided telecentric optical system, wherein the irradiation area is a circular image field of the projection optical system.
Is defined to be included in the field
Apparatus according to any one of claims 23 to 32. 34. A device manufacturing method using the device according to claim 23.