JPH11354413A - Method and device for projection alignment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To expose patterns to be transferred on the optimum focal plane of a projection optical system in accordance with the types of the patterns without making the management, etc., of process programs more complicated. SOLUTION: A projection aligner is provided with an AF system 20 which detects the attitude of the surface of a wafer W against a projection optical system 18 by projecting a light beam upon the surface, a Z-stage 21 which adjusts the attitude of the wafer W based on the detecting value of the AF system 20 so that the surface of the wafer W may become coincident with the optimum focal plane of the optical system 18, a storage device 15A which stores the offset information on the inclination of the optimum focal plane of the optical system 18 by respectively correlating the information with a plurality of exposure conditions, and a controller 15 which controls the attitude of the Z-stage 21 based on the offset information corresponding to the exposure condition when the wafer W is exposed of the plurality of exposure conditions and the detecting value of the AF system 20 by reading out the offset information from the storage device 15A.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a semiconductor integrated circuit,
The present invention relates to a projection exposure method and a projection exposure apparatus used when manufacturing a liquid crystal display element, a thin film magnetic head, and other micro devices using a lithography technique.

[0002]

2. Description of the Related Art In a photolithography process, which is one of semiconductor device manufacturing processes, a mask or a reticle is used as an exposure apparatus for transferring a pattern formed on a photoresist onto a wafer coated with a photoresist. A stepper that reduces and projects a pattern image onto a shot area on a wafer is often used.

In this type of projection exposure apparatus, a wafer to be exposed is held on a wafer holder on a stage by negative pressure suction or the like. The position of the surface of the wafer in the optical axis direction is detected by, for example, an oblique incident light type focus detection device (AF device), and the posture thereof is adjusted so as to coincide with a predetermined reference plane. It has become so.

The illumination optical system illuminates a photoresist-coated wafer with an appropriate exposure amount according to the sensitivity characteristic of the photoresist through a mask on which a pattern is formed, thereby selectively exposing the photoresist. By
For one layer, a latent image having a shape corresponding to the pattern of the mask is formed on the wafer, developed, etched,
Perform processing such as doping. Although it depends on the semiconductor device to be manufactured, a normal LSI or the like repeatedly transfers and forms such a pattern for about a dozen layers. Each layer is roughly classified into a dense line system layer composed of a periodic dense pattern (line and space), an isolated line layer composed of a discrete isolated pattern, and a contact hole (C / H) for interlayer connection. ), And the like.

In response to recent demands for further miniaturization of patterns, efforts have been made to shorten the wavelength of the light source and to increase the numerical aperture of the projection optical system. The following technologies have been developed as super-resolution techniques for improving the focal depth. That is, it relates to illumination conditions for the reticle such as small σ illumination, annular illumination, and fourth (SHRINC) illumination, and to mask conditions such as a phase shift method of shifting the phase of light by providing a phase shifter in a part of a mask. Or pupil conditions such as insertion of a pupil filter for adjusting the light intensity distribution in the pupil plane, and these are used alone or in combination.

The effectiveness of these super-resolution techniques differs depending on the type of pattern (line type, line width, etc.). For example, in the case of a dense pattern, it is sometimes effective to use annular illumination because the resolution and the depth of focus can be improved by cutting the 0th-order light that illuminates the mask vertically. In the case of a contact hole or a contact hole, the resolution may be improved by vertically illuminating the mask using small σ illumination. Further, a phase shift mask and a modified illumination may be combined in the case of a periodic dense pattern, or a pupil filter and a small σ illumination may be combined in the case of an isolated pattern or a contact hole.

Here, if the illumination conditions are changed in order to expose the target pattern, a slight change may occur in the focal plane (focal plane) depending on the combination of the apparatus used for the exposure, the target pattern and the illumination conditions. This tendency is also slightly different due to the superimposition of inherent manufacturing errors remaining in each device.

Therefore, in a conventional projection exposure apparatus,
Optimize the position in the optical axis direction so that the surface of the photosensitive substrate coincides with the predetermined reference surface under the illumination conditions when exposing the reference pattern, and for layers with different characteristics, suitable for the illumination conditions The correction value in the optical axis direction of the projection optical system (the offset value in the optical axis direction with respect to the focal plane under the illumination conditions for the reference pattern) is determined in advance,
This is registered in advance in a process program (a recipe in which a manufacturing procedure and various data of a semiconductor device to be manufactured using the projection exposure apparatus are set) used in each projection exposure apparatus configuring the semiconductor manufacturing line, and This has been dealt with by correcting the position of the surface of the photosensitive substrate in the optical axis direction based on the offset value at the time of exposure processing for another layer.

[0009]

However, according to the above-mentioned prior art, since the optimum focal plane for each layer changes three-dimensionally due to the change in exposure conditions, the position in the optical axis direction differs from the conventional one. There is a problem that correction alone is not enough.

In general, process programs for a plurality of projection exposure apparatuses constituting a semiconductor manufacturing line are common among the respective projection exposure apparatuses, but are highly efficient from the viewpoint of management and compatibility. Conventionally, it is necessary to register a correction value unique to each device in a form that is included in a process program that should be common to each device. For this purpose, some management that separates the correction value unique to the device and shared information is used. However, in some cases, the correction function itself is a useful function but is not used even though it is a useful function.

The present invention has been made in view of such problems of the prior art.
Without complicating the management of process programs, etc.
An object of the present invention is to enable exposure at an optimum focal plane according to the type of a pattern to be transferred and exposed, and to manufacture a high-precision and high-quality micro device.

[0012]

In the following description, the present invention will be described with reference to the member codes shown in the drawings showing the embodiments. However, the present invention is not limited to the members shown in the drawings attached with.

1. To achieve the above object, according to one aspect of the present invention, a projection exposure method for transferring an illuminated pattern image of a mask (R) onto a photosensitive substrate (W) via a projection optical system (18). In each of the plurality of exposure conditions, the inclination information of the optimum focal plane of the projection optical system is stored and held in advance in association with each of the exposure conditions, and based on the inclination information corresponding to the exposure conditions at the time of performing the exposure. A projection exposure method is provided, wherein a posture of the photosensitive substrate with respect to the projection optical system is corrected.

At the time of exposure processing, exposure conditions (illumination conditions, reticle conditions, pupil conditions, etc.) suitable for each are selected according to the type of pattern to be transferred (line type, line width, etc.). For each of the plurality of exposure conditions, the inclination information of the optimal focal plane of the projection optical system is stored and held in advance in association with each exposure condition, and the photosensitive substrate is adjusted based on the inclination information corresponding to the exposure condition at the time of performing the exposure. Since the posture with respect to the projection optical system is corrected, it is possible to transfer the pattern in a state where the surface of the photosensitive substrate is coincident with the optimal focal plane that changes three-dimensionally according to the type of the pattern to be transferred and formed, Therefore, a highly accurate pattern can be formed. Further, it is only necessary to set exposure conditions and the like in the process program, and it is not necessary to set inclination information as a value unique to the exposure apparatus. And management thereof can be facilitated.

2. In order to achieve the above object, according to another aspect of the present invention, an image of a pattern of a mask (R) illuminated with illumination light from an illumination optical system is exposed via a projection optical system (18) to a photosensitive substrate (W). In a projection exposure apparatus that projects onto the photosensitive substrate and projects the light onto a plurality of detection points, the position of the projection optical system in the optical axis direction is detected at a plurality of points on the surface of the photosensitive substrate. Focus detection device (24-3
(7) an adjusting device (21) for adjusting an attitude of the photosensitive substrate based on a detection value of the focus detection device such that a surface of the photosensitive substrate substantially coincides with an optimum focal plane of the projection optical system.
A storage device (15A) that stores and holds each of offset information corresponding to a plurality of detection points of the focus detection device with respect to the inclination of the optimum focal plane of the projection optical system in association with each of a plurality of exposure conditions. Reading the offset information corresponding to the exposure condition when exposing the photosensitive substrate out of the plurality of exposure conditions from the storage device, based on the read offset information and the detection value of the focus detection device, And a control device (15) for controlling the adjusting device.

At the time of exposure processing, appropriate exposure conditions (illumination conditions, reticle conditions, pupil conditions, etc.) are selected according to the type of pattern to be transferred and formed (line type, line width, etc.). For each of the plurality of exposure conditions, offset information corresponding to a plurality of detection points of the focus detection device regarding the inclination of the optimum focal plane of the projection optical system is stored and held in a storage device in advance in association with each exposure condition, and the exposure is performed. The position of the photosensitive substrate is adjusted by the adjustment device based on the offset information corresponding to the exposure condition at the time and the detection value of the focus detection device, so that it changes three-dimensionally according to the type of pattern to be transferred and formed. The pattern can be transferred with the surface of the photosensitive substrate aligned with the optimal focal plane,
Therefore, a highly accurate pattern can be formed.
Further, in the process program, it is only necessary to set exposure conditions and the like, and it is not necessary to set offset information at a plurality of detection points of the focus detection device as a value unique to the exposure device. The process program can be shared between the exposure apparatuses, and the management thereof can be facilitated.

[0017]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a perspective view showing a main configuration of a projection exposure apparatus according to an embodiment of the present invention. Illumination light 11 from a light source (not shown) is incident on a fly-eye lens 13 for uniformizing the intensity distribution of the illumination light 11 via an illumination magnification system 12. A rotary plate 14 having a plurality of aperture stops is provided near the focal plane of the fly-eye lens 13 on the reticle R side. These aperture stops set the range of angles at which light strikes the reticle R, and the size of the aperture stops determines the numerical aperture of the illumination optical system. Examples of the plurality of aperture stops provided on the rotating plate 14 include small σ illumination, annular illumination, and fourth (SHRINC) illumination in addition to normal illumination. One of these aperture stops can be selectively set by rotating the rotary plate 14 based on a command from a control device 15 such as a microcomputer. In addition, as the aperture stop, a variable aperture stop that can arbitrarily change the size of the aperture can be used.

The illumination power varying system 12 is for changing the numerical aperture of the illumination optical system based on a command from the control device 15. Although not shown, a plurality of positive lens groups and a plurality of negative A lens group and a plurality of positive lens groups are arranged on the optical axis, and one or a plurality of lens groups are moved with respect to the other lens groups. The size of the secondary light source can be changed without blocking light.

The light that has passed through the aperture stop of the rotating plate 14 is transmitted to a lens group 1 including a reticle blind (field stop) and the like.
6. Illuminate the reticle R on which the pattern to be transferred is formed, via the mirror 17, the condenser lens (not shown). The reticle R is held on a reticle stage (not shown) with its pattern surface facing down, and a plurality of types of different reticles R are selectively mounted on the reticle stage. As the type of the reticle R, a phase shift type (Shibuya-Levenson type, auxiliary pattern type, edge emphasis type, halftone type, chromeless type, etc.) is used in addition to a normal reticle having a light shielding pattern formed of chrome or the like on a glass substrate. Are selected according to the type of pattern to be transferred.

The illuminated pattern image from the reticle R is projected onto the wafer W via the projection optical system 18.
The numerical aperture of the projection optical system 18 can be arbitrarily set by controlling the size of the NA stop 19 provided on the pupil plane of the projection optical system 18 by the control device 15. This N
By changing and adjusting the numerical aperture of the projection optical system 18 by the A-stop 19, and changing and adjusting the numerical aperture of the illumination system by the above-described illumination zooming system 12 and the aperture stop of the rotating plate 15,
The so-called σ value can be set arbitrarily. Note that a pupil filter that adjusts the light intensity distribution of light transmitted through the pupil plane may be selectively inserted into the pupil plane of the projection optical system 18.

As shown in FIG. 2, the wafer W to be exposed is vacuum-sucked on a wafer holder (not shown) on the Z stage 21. The Z stage is mounted on an XY stage that is moved in the X and Y directions (in a plane substantially orthogonal to the optical axis of the projection optical system 18) via a plurality of actuators that can be displaced in the optical axis direction of the projection optical system 18. It is placed. By operating each actuator independently by the control device 15, the position of the surface of the wafer W in the direction along the optical axis of the projection optical system 18 and the inclination of the surface of the wafer W with respect to a plane orthogonal to the optical axis are determined. It can be changed arbitrarily within a minute range. The XY stage can be moved in the X and Y directions by controlling the driving of the linear motor by the control device 15. XY
The position of the stage in the X and Y directions is measured by a laser interferometer (not shown).

This projection exposure apparatus is an obliquely incident light type AF system (focus / leveling detector) 2 for making the surface of the wafer W on the Z stage 21 coincide with a predetermined reference plane.
The AF system 20 includes a light projector 22 and a light receiver 23, as shown in FIG. Illumination light of a predetermined shape which is non-photosensitive to the resist of the wafer W is obliquely applied to the wafer W from the light projector 22, and the light reflected by the wafer W is received by the light receiver 23 via a lens or a mirror. . The light receiver 23 has a photoelectric sensor such as a CCD, and uses the attitude of the projection optical system 18 on the surface of the wafer W (position in the optical axis direction and inclination with respect to a plane orthogonal to the optical axis) as a change in position on the photoelectric sensor. To detect.

The mirror 23A of the light receiver 23 is a correction plate which can be slightly rotated in an arbitrary direction, and based on a control signal from the control device 15, the correction plate 23A
By slightly rotating the reticle R, the attitude of the predetermined reference plane of the AF system 20 can be strictly adjusted so as to have a conjugate relationship with the pattern plane of the reticle R. Note that the mirror 23A is fixed, and a correction plate made of a transparent glass plate or the like that can be slightly rotated in an arbitrary direction is arranged on the optical path of the reflected light from the wafer W, and based on a control signal from the control device 15, The attitude of this AF system 20 on a predetermined reference plane may be adjusted by slightly rotating this correction plate.

The reference plane of the AF system 20 is set so as to have a conjugate relationship with the pattern plane of the reticle R as follows, for example. Although not shown, Z stage 2
A reference plate on which a reference mark (for example, a plurality of slits) for detecting a focus position is formed is provided on 1, and this reference mark is illuminated from below, and the reticle R By reaching the pattern surface and receiving the light reflected there and returned via the projection optical system 18 below the reference mark, the illuminance is detected while slightly moving the Z stage 21 in the Z direction. The optimum focus position is detected.

That is, the reference plate is located at the optimum focus position (reticle R
(The position conjugate with the pattern plane) is blurred on the reference plate, the illuminance per unit area is reduced, and when it is at the optimum focus position, it becomes sharp. Since the illuminance per unit area is increased, by detecting this, the optimum focus position can be detected.
In this embodiment, although there is no particular limitation, it is assumed that the illumination conditions for the focus position detection match as closely as possible the illumination conditions for the reference pattern from the dense line (pattern). In this state, the angle of the correction plate 23A is finely adjusted so that the reflected light on the surface of the wafer W is located at the center of the photoelectric sensor of the light receiver 23, so that the reference plane of the AF system coincides with the optimum focal plane. Will do. However, this A
The reference pattern at the time of adjusting the F system is not limited to the dense line.

Incidentally, the optimum focal plane is determined by the projection optical system 18.
And changes due to changes in exposure conditions including the illumination conditions. Therefore, such a uniform focusing method cannot be adapted to each exposure condition. For example, in the above case, it is possible to perform the exposure at the optimum focal plane for the dense line, but not for the isolated line or the contact hole.

Therefore, in this embodiment, the following countermeasures are taken. That is, information (offset information) relating to the inclination of the optimum focal plane of the projection optical system 18 is stored in advance in a storage device (memory) 15A attached to the control device 15 in association with each of a plurality of exposure conditions (illumination conditions). Let me.

FIGS. 3A to 3C are diagrams showing an example of the measurement results of the best focus (optimal focus position) at each position within the exposure field (projection area) of the projection optical system 18. A) shows the best focus under the optimal illumination condition when transferring and exposing a dense line (0.25 μm), and (B) shows the best focus under the optimal lighting condition when transferring and exposing an isolated line (0.25 μm). ,
(C) shows the best focus under the optimal illumination condition when the contact hole (0.30 μm) is transferred and exposed. As shown in the figure, due to the influence of the residual aberration of the projection optical system 18 and the like, the tendency of the best focus differs slightly depending on each illumination condition and the position in the exposure field.

The best focus corresponding to each of these lighting conditions is collected by the following method, and is input and stored as a part of the device constant in a lighting condition file stored and held in the storage device 15A. This will be described with reference to the flowchart shown in FIG. First, in ST1, a test reticle for CD (critical dimension) focus measurement or best focus measurement is prepared. This test reticle is a reticle formed with a particularly high precision for focus measurement.

Next, in ST2, the test reticle is held on a reticle stage, and illumination conditions for exposing a target pattern (line type and line width) are set (switched). Test exposure. Such test exposure is sequentially performed while slightly moving the position of the sample wafer in the Z direction. Thereafter, in ST3, the line width of the pattern transferred to the sample wafer is measured by an electron microscope, and the focus position (position in the Z direction) when the line width reaches a peak (maximum or minimum) is determined as the best position at that point. The focus value. This is obtained at each of a plurality of representative points in the exposure field. Such processing is performed under each illumination condition corresponding to each of the target patterns (line type and line width), and the best focus value at the representative point for each is obtained. As a result, FIG.
The data as shown in FIG.

Then, in ST4, the offset (difference) with respect to the obtained best focus value itself or the best focus value for dense lines is used as a leveling correction value as shown in FIG. The information is input and stored in the illumination condition file of the storage device 15A as a part of the device constant. Here, an ID (identification number) is assigned to each exposure condition (illumination condition), and a plurality of correction values are set corresponding to the ID. However, the present invention is not limited to this, and data obtained by further processing these correction values may be used. For example, an average plane may be calculated based on these correction values, and may be data including coordinate values of a specific point and a normal line of the plane, or inclination angle data of the average plane.

Then, in ST5, based on the measurement result, it is determined which illumination condition is optimal from the characteristics of the pattern (line type, line width) in order to expose the target layer. As shown in FIG. 5B, an ID corresponding to the determined lighting condition is registered in a corresponding process program. The process program is a user program (recipe) created in accordance with the microdevice to be manufactured, and the control device 15 controls the rotating plate 14, the illumination variable power system 1 according to the process program.
2. The NA aperture 19, the reticle to be used (normal reticle, phase shift reticle, etc.) and other exposure conditions are set, and an exposure process for manufacturing a micro device is performed.

Next, with reference to the flow chart shown in FIG. 6, the main part of the processing by the control device 15 during the actual exposure processing will be described. First, in ST1, a process program for exposing a target layer is input and designated by an operator or the like, and is read. Next, ST
2, the corresponding processing is performed according to various procedures set in the designated process program of the storage device 15A, and when the lighting condition ID is read, the above devices 12, 14, 19, etc. are controlled. Then, the lighting condition is switched to the corresponding lighting condition. The setting of the lighting conditions can also be manually input and designated by the operator. Next, in ST3, based on the selected (read) lighting condition ID, the lighting condition file in the storage device 15A is searched, and the corresponding leveling correction value is read.

Thereafter, in the exposure processing of the wafer W,
The AF system 20 corrects the posture of the Z table 21 so that focusing and leveling are optimized with respect to the pattern by appropriately operating each actuator of the Z table 21 based on the leveling correction value. This processing is sequentially performed for each shot on the wafer W.

After a predetermined reference surface of the AF system 20 is corrected by slightly rotating the correction plate 23A based on the leveling correction value, each actuator of the Z stage 21 is controlled according to the detection result by the AF system 20. By appropriately operating, the surface of each shot area of the wafer W is brought into a state in which the surface coincides with the predetermined reference plane, and thereafter, the exposure processing is sequentially performed.

As described above, according to the present embodiment, the inclination information (offset information) relating to the inclination of the optimum focal plane of the projection optical system 18 for each of the plurality of illumination conditions is associated with the ID of each illumination condition in advance and the storage device is used. 15A, a predetermined reference plane of the AF system 20 is corrected by a leveling correction value corresponding to the illumination condition at the time of exposure, and the stage 2 is adjusted based on the detection result of the AF system 20.
Since the first actuator is appropriately operated to make the surface of the wafer W coincide with a predetermined reference plane, the optimum three-dimensionally changes according to the type (line type, line width) of a pattern to be transferred and formed. The pattern can be transferred in a state where the surface of the wafer W always coincides with the focal plane. Therefore, a highly accurate pattern can be formed. Further, the illumination condition ID of the pattern is registered in the process program, and the illumination condition file in the storage device is searched based on the illumination condition ID, so that the offset information as a value unique to the exposure apparatus is used. Need not be registered in the process program, the process program can be shared among the exposure apparatuses, and the management thereof can be facilitated.

The AF system is not limited to the one described above, and a multi-point AF system of an oblique incident light type may be used. Multipoint A
F refers to a focusing method that detects a focus position (a position in a direction along the optical axis of the projection optical system) at a plurality of detection points in an exposure field of the projection optical system. This will be described with reference to FIG. Illuminating the slit plate 25 with non-photosensitive illumination light 24 on the resist of the wafer W;
The transmitted light irradiates the surface of the wafer W obliquely through a lens system 26, a mirror 27, a diaphragm 28, an objective lens 29, and a mirror 30. The oblique incidence angle is about 5 to 12 degrees with respect to the wafer surface.

The slit light reflected by the wafer W is transmitted to the mirror 31, the objective lens 32, the lens system 33,
4. The light reaches the slit plate 36 for light reception via a correction plate 35 formed of a plane-parallel plate or the like. The vibrating mirror 35 slightly vibrates the slit image formed on the light receiving slit plate 36 in a direction orthogonal to the longitudinal direction thereof, and the correction plate (plane parallel) 35 transmits the light from the slit on the light receiving slit plate 36 and the wafer W. Is shifted in the direction perpendicular to the longitudinal direction of the slit.

Light transmitted through the slits of the slit plate 36 is received by an array sensor 37 composed of a photodiode or the like. The array sensor 37 is configured by arranging a plurality of photoelectric cells in the longitudinal direction of the slit of the slit plate 36, and a detection signal of each photoelectric cell is input to the control device 15. This detection signal is called a so-called S-curve signal, and becomes a zero level when the slit center of the light receiving slit plate 36 coincides with the vibration center of the reflection slit image from the wafer W, and the wafer W is moved upward from that state. The level is positive when the wafer is displaced, and is negative when the wafer is displaced downward from that state. Therefore, the position on the surface of the wafer where the detection signal becomes zero level is detected as the focal point. Note that the correction plate 35 is for correcting the position of a predetermined reference plane.

When such a multipoint AF system is employed, the correction value corresponding to each illumination condition corresponds to a plurality of detection points (each photoelectric cell of the array sensor 37) of the multipoint AF system. The offset information (for example, the difference with respect to the position of the projection optical system in the optical axis direction under the optimal illumination conditions for dense lines) is stored and stored in association with each of the plurality of exposure conditions. At the time of the exposure processing, a correction value corresponding to the illumination condition optimal for the pattern to be subjected to the exposure processing is read,
With the detection values for each corresponding detection point corrected, Z
After adjusting the attitude of the stage 21, the exposure process is performed. Thus, regardless of the type of the pattern, the exposure process can always be performed on the optimum focal plane, the accuracy of pattern transfer can be improved, and a high-quality, high-precision microdevice can be manufactured.

The embodiments described above are described for facilitating the understanding of the present invention, and are not described for limiting the present invention. Therefore, each element disclosed in the above embodiment is intended to include all design changes and equivalents belonging to the technical scope of the present invention.

For example, as the focus detecting device, the above A
The method is not limited to the F system or the multipoint AF system, and the adjustment of the attitude of the predetermined reference plane of the AF system is not limited to the above-described method. For example, another method such as an aerial image measurement method can be adopted.

Further, the present invention provides a step-and-repeat type projection exposure apparatus that collectively exposes a pattern to a shot area on a wafer, sequentially moves the wafer, and repeats the batch exposure for another shot area. First, the mask and the wafer are moved synchronously, and the shot area on the wafer is sequentially exposed by scanning and illuminating with a slit light of a rectangular shape or the like, and the wafer is sequentially moved to scan and illuminate another shot area. The present invention can be applied to a step-and-scan type projection exposure apparatus that repeats exposure, and can be similarly applied to an exposure apparatus such as a mirror projection type or a proximity type.

Further, the light source of the exposure apparatus is not particularly limited, and i-line, g-line, KrF, Ar
F, excimer lasers, such as _{F 2,} further EUV (Extreme U having an oscillation spectrum in the soft X-ray region
ltra Violet).

Further, the projection optical system 18 may be an optical system including only a reflection element (mirror or the like) other than all the optical elements being refraction elements (lenses), or a combination of a refraction element and a reflection element. A catadioptric optical system including elements (concave mirror, mirror, etc.) may be used. Further, the projection optical system 18 is not limited to the reduction optical system, but may be an equal-magnification optical system or an enlargement optical system.

[0047]

Since the present invention is configured as described above in detail, it is possible to perform exposure on the optimum focal plane according to the type of pattern to be transferred and exposed without complicating the management of the process program and the like. There is an effect that a high-precision, high-quality micro device can be manufactured.

[Brief description of the drawings]

FIG. 1 is a perspective view illustrating a main configuration of a projection exposure apparatus according to an embodiment of the present invention.

FIG. 2 is a perspective view illustrating a schematic configuration of an AF system of the projection exposure apparatus according to the embodiment of the present invention.

3A and 3B are diagrams illustrating an example of a best focus measurement result at each position in an exposure field according to an embodiment of the present invention, where FIG. 3A is a dense line, FIG. 3B is an isolated line, and FIG. The case of a hole is shown.

FIG. 4 is a flowchart showing a process when collecting inclination information of an optimum focal plane according to the embodiment of the present invention.

5A and 5B are diagrams illustrating a configuration of various information stored and held in a storage device according to an embodiment of the present invention. FIG. 5A illustrates an example of tilt information, and FIG. 5B illustrates an example of a process program. .

FIG. 6 is a flowchart illustrating a main part of an exposure process according to the embodiment of the present invention.

FIG. 7 shows a multi-point AF in a projection exposure apparatus according to an embodiment of the present invention.
It is a schematic structure figure at the time of applying a system.

[Explanation of symbols]

 R: Reticle W: Wafer 11: Illumination light 12: Illumination variable power system 13: Fly-eye lens 14: Rotating plate (aperture stop) 15: Control device (computer) 15A: Storage device 18: Projection optical system 19: NA stop 20 ... AF system 21... Z stage 22.

Claims (7)

[Claims] 1. A projection exposure method for transferring an image of an illuminated mask pattern onto a photosensitive substrate via a projection optical system, wherein, for each of a plurality of exposure conditions, inclination information of an optimum focal plane of the projection optical system is obtained. A projection exposure method comprising: preliminarily storing and holding in association with the respective exposure conditions; and correcting a posture of the photosensitive substrate with respect to the projection optical system based on tilt information corresponding to the exposure conditions at the time of performing the exposure. . 2. The projection exposure method according to claim 1, wherein the plurality of exposure conditions have different illumination conditions for a mask. 3. The projection exposure method according to claim 1, wherein the plurality of exposure conditions have different light intensity distributions on a pupil plane of the projection optical system. 4. The projection exposure method according to claim 1, wherein the plurality of exposure conditions differ in the type of the mask. 5. The projection exposure method according to claim 1, wherein said exposure condition is selected according to a line type of a pattern to be transferred. 6. The projection exposure method according to claim 5, wherein the line type of the pattern includes at least one of a dense line, an isolated line, and a contact hole. 7. A projection exposure apparatus for projecting an image of a pattern of a mask illuminated with illumination light from an illumination optical system onto a photosensitive substrate via a projection optical system to expose the photosensitive substrate, A focus detection device that irradiates a point with a light beam and detects the position of the projection optical system in the optical axis direction at a plurality of points on the surface of the photosensitive substrate; and the photosensitive substrate surface is substantially the optimum focal plane of the projection optical system. An adjusting device that adjusts the posture of the photosensitive substrate based on a detection value of the focus detection device so as to match; and an offset corresponding to a plurality of detection points of the focus detection device with respect to an inclination of an optimum focal plane of the projection optical system. A storage device for storing and holding each piece of information in association with each of a plurality of exposure conditions; and the offset information corresponding to an exposure condition when exposing the photosensitive substrate among the plurality of exposure conditions. Read from the device, a projection exposure apparatus characterized by comprising a control device for controlling the adjustment device based on the detected value of the with the read offset information focus detecting device.