WO2003100838A1

WO2003100838A1 - Scanning projection aligner and aligning method

Info

Publication number: WO2003100838A1
Application number: PCT/JP2003/006342
Authority: WO
Inventors: Yuichi Shibazaki
Original assignee: Nikon Corporation
Priority date: 2002-05-23
Filing date: 2003-05-21
Publication date: 2003-12-04
Also published as: JPWO2003100838A1; AU2003242368A1; TW200400545A

Abstract

A scanning projection aligner for projecting the pattern image of a mask (2) onto a substrate (6) through a projection optical system PL by moving the mask (2) and the substrate (6) synchronously in the first direction with respect to an exposing light. The aligner comprises a unit RB for altering the setting of the irradiation area of exposing light on the mask (2), and a unit for switching the synchronous movement direction of the mask (2) and the substrate (6) to a second direction different from the first direction as the irradiation area of exposing light is altered. According to the aligner, a non-rotationally symmetric aberration occurring in the projection optical system can be controlled when a pattern on a reticle is transferred onto a wafer through the projection optical system.

Description

Description Scanning type exposure apparatus and scanning type exposure method

The present invention relates to a method for manufacturing a semiconductor device, a liquid crystal display device, an image pickup device (CCD, etc.), a thin film magnetic head, or the like by using a photolithographic process to form a pattern on a mask through a projection optical system. The present invention relates to a scanning exposure apparatus and a scanning exposure method used for exposing a substrate. The present invention is particularly suitable for a scanning exposure apparatus and a scanning exposure method in which a substantial illumination area on a mask is not rotationally symmetric with respect to the optical axis of the projection optical system. Background art

Conventionally, in a photolithographic process for manufacturing a semiconductor device or the like, a substantially square illumination area is set on a reticle as a mask, and a pattern in the illumination area is used as a photosensitive substrate via a projection optical system. A batch exposure type projection exposure apparatus such as a stepper for exposing on a wafer (or a glass plate or the like) has been widely used. On the other hand, recently, in order to cope with an increase in the size of a chip pattern of a semiconductor device or the like, it is required to transfer a larger reticle pattern to each shot area on a wafer. However, it is difficult to design and manufacture a projection optical system in which aberrations such as distortion and curvature of field are suppressed to a predetermined allowable value or less over a wide exposure field.

Therefore, recently, a slit-shaped illumination area such as a rectangle or an arc is set on the reticle, and the pattern in the illumination area is projected onto the wafer via the projection optical system, and the reticle and the wafer are projected. Attention has been focused on scanning exposure type projection exposure apparatuses, such as a step-and-scan type, which sequentially exposes a reticle pattern to each shot area on a wafer while scanning synchronously with an optical system. This scanning exposure type projection exposure apparatus exposes the slit-shaped exposure area almost inscribed in the effective exposure field of the projection optical system while scanning the wafer, so that the effective exposure field of the projection optical system In addition to maximizing the use of the diameter of the reticle, the length of the transfer pattern in the scanning direction can be longer than the diameter of the effective exposure field, resulting in the transfer of a large area reticle pattern onto the wafer with small aberrations. it can.

However, the conventional scanning exposure apparatus and scanning exposure method as described above have the following problems.

In general, in a scanning type exposure apparatus, an illumination area that is not rotationally symmetric with respect to the optical axis of a projection optical system is set on a reticle during exposure. Therefore, even if the rate of absorption of the irradiation energy of the glass material constituting the lens of the projection optical system is small, a temperature distribution of the lens is generated due to the heat absorbed by the irradiation energy. The lens thermally deforms non-rotationally symmetrically due to the temperature distribution of the lens, and the refractive index distribution of the glass material changes non-rotationally symmetrically due to a partial temperature rise. Thereby, the aberration of the projection optical system fluctuates. Such aberration fluctuations have become unacceptable under today's conditions requiring high resolution and high-accuracy transfer. -Currently, i-line with a wavelength of 365 nm is mainly used as the illumination light for exposure using an ultra-high pressure mercury lamp as a light source, but recently, a wavelength in the far ultraviolet region shorter than the i-line is 248 ! 1 111¾: F excimer laser light is being used, and the use of ArF excimer laser light with a wavelength of 193 nm is also being studied. The lens of the projection optical system of a projection exposure system that uses such pulsed laser light (hereinafter referred to as “pulse laser light”) is irradiated with pulsed laser light at a high frequency, and only the irradiated part has a transmittance. Occurs. A phenomenon in which the refractive index increases only in the part of the lens that is irradiated with the pulsed laser light also occurs.

Such a change in the refractive index is caused by a chemical change in the glass, and a partial increase in the non-rotationally symmetric distribution of the refractive index of the lens is extremely bad particularly for the aberration of the projection optical system. affect. If the temperature distribution of the lens occurs in a non-rotationally symmetric distribution, it will cause a local increase in the temperature distribution in the lens, and as a result, the lens will be non-rotationally symmetrically thermally deformed, and further adversely affect the aberration. Become. An increase in temperature also causes an increase in the refractive index of the lens, which also adversely affects the aberration of the projection optical system.

On the other hand, conventional exposure equipment controls the pressure of the gas in contact with the lens in the projection optical system. In this case, the aberration fluctuation of the projection optical system was corrected by moving or moving a part of the lens constituting the projection optical system. With this method, in the case of a one-shot exposure type using a substantially square illumination area, the degree of non-rotational symmetry of the illumination area was low, so that aberration variation could be sufficiently corrected. However, when an illumination area on the reticle is slit-shaped such as a rectangle or an arc as in a scanning exposure type projection exposure apparatus, an illumination area that is not rotationally symmetrical with respect to the optical axis is used. There is a possibility that fluctuations in aberrations such as the curvature of field do not fall within an allowable value. In particular, when non-rotational symmetry is remarkable, the best image plane of the pattern in the meridional direction and the best image plane of the pattern in the direction perpendicular to the center of the exposure field of the projection optical system are separated in the optical axis direction. There is also the disadvantage that astigmatism (hereinafter referred to as “center ass”) occurs. '

In this regard, correction is made by applying non-rotationally symmetric external forces on the optical axis from two directions to the side surface of a given part of a certain lens in the projection optical system, and deforming that lens. There is a known method. However, correcting the lens by deforming it with external force requires a considerable amount of pressure, which is not practical. For this reason, aberration fluctuations due to the slit-shaped illumination area cannot be completely canceled by deformation due to external force. As described above, when the scanning exposure is performed in a state where the aberration cannot be corrected, it is difficult to maintain the uniformity of the pattern line width, and the defect rate of the produced device may increase.

The present invention has been made in consideration of the above points, and suppresses non-rotationally symmetric aberrations generated in a projection optical system when a pattern on a reticle is transferred onto a wafer via a projection optical system. It is an object of the present invention to provide a scanning type exposure apparatus and a scanning type exposure method which can be performed. Disclosure of the invention

The scanning exposure apparatus of the present invention projects a mask pattern image onto a substrate via a projection optical system by synchronously moving the mask and the substrate in a first direction with respect to exposure light. This apparatus includes a changing device for changing the setting of the exposure light irradiation area on the mask, and a changing device for the exposure light. A switching device for switching the direction of synchronous movement between the mask and the substrate to a second direction different from the first direction in accordance with a change in the irradiation area.

In the scanning exposure method of the present invention, the mask and the substrate are synchronously moved with respect to the exposure light in a first direction, and a pattern image of the mask is projected on the substrate via a projection optical system. This method includes a step of changing the setting of the exposure light irradiation area on the mask, and a method of changing the direction of the synchronous movement between the mask and the substrate from the first direction in accordance with the change of the exposure light irradiation area. Switching the direction.

According to the present invention, the illumination area with respect to the mask is changed at an arbitrary timing, and the synchronous movement direction between the mask and the substrate is switched according to the changed illumination area. The direction (area) of illuminating the optical element of the optical system can be changed. Therefore, the non-rotational symmetry of the temperature distribution of the optical element due to the absorption heat of the irradiation energy can be reduced, and the non-rotational symmetry aberration caused by the temperature change can be suppressed.

In the present invention, by suppressing non-rotationally symmetric aberrations generated in the projection optical system in this way, it is possible to maintain excellent imaging characteristics, and have a uniform and desired line width on the substrate. A highly integrated device can be manufactured by forming a fine pattern, and device defects caused by non-rotationally symmetric aberrations can be reduced. When a plurality of stages are provided, the time required for substrate replacement alignment can be omitted, which can contribute to an improvement in throughput. BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a schematic configuration diagram of a scanning exposure apparatus according to the present invention.

2A to 2C are plan views of the reticle blind.

FIG. 3 is a schematic configuration diagram of a plane motor included in the traveling type exposure apparatus.

FIG. 4 is a control block diagram of the exposure apparatus.

FIG. 5 is a flowchart showing an embodiment of the present invention.

FIG. 6 is a diagram showing the second embodiment of the present invention, and is a plan view in which two wafer stages are provided.

FIG. 7 is a flowchart illustrating an example of a semiconductor device manufacturing process. BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, a scanning exposure apparatus and a scanning exposure method according to a first embodiment of the present invention will be described with reference to FIGS. 1 to 5. This embodiment is a step-and-scan scanning method in which a pattern on a reticle is sequentially transferred and exposed to each shot area on the wafer by scanning the reticle and wafer synchronously with respect to a projection optical system. This is an example in which the present invention is applied to a 查 -type exposure apparatus and a scanning-type exposure method.

FIG. 1 shows a schematic configuration of a scanning exposure apparatus of the present embodiment. In FIG. 1, the illumination optical system 1 includes a light source, an optical integrator (for example, an open lens or a fly-eye lens) for uniforming the illuminance distribution on the reticle, a reticle blind, a condenser lens, and the like. The illumination light (exposure light) emitted from the illumination optical system 1 forms a slit-shaped illumination area on the pattern formation surface (lower surface) of the reticle (mask) 2 set by the reticle blind (change device) RB. Illuminate with a uniform illuminance distribution. Under the illumination light, the pattern in the illumination area on the reticle 2 is inverted at a projection magnification (/ 3 is, for example, 1/4) through the projection optical system PL to form a slit on the wafer (substrate) 6. The image is projected on the exposure area. The illumination light, K r F excimer laser light, or A r F E key Shimareza light, F ₂ laser beam, harmonics of a copper vapor laser or YAG laser, or an ultra-high pressure mercury lamp bright line (g-line, i-line, etc.) Are used. Hereinafter, the description will be made by taking the Z axis parallel to the optical axis of the projection optical system PL, and the Y axis and the X axis in directions perpendicular to each other in a plane perpendicular to the optical axis.

As shown in FIG. 2A, the reticle blind RB has two L-shaped movable blades 11 and 12 and an actuator 13 that drives the movable blades.

The two movable blades 11 and 12 are arranged near a shared surface optically conjugate to the reticle 2 and the wafer 6, and are controlled by the main control system 20 (see FIG. 4). The position and size of the rectangular illumination area of the illumination light on the reticle R are variably set on the XY plane by moving independently of each other in a plane orthogonal to the optical axis of the illumination light by the drive of 13. You can use four I-shaped movable blades.

The reticle 2 is connected to a reticle holder as a holding unit via a reticle holder (not shown). (Mask stage) 3 The reticle stage 3 is supported above the reticle base (base) 4 in a plane (XY plane) perpendicular to the optical axis, and is supported two-dimensionally in the XY plane by driving a plane motor described later. The reticle 2 is moved and positioned, and is movable at a predetermined scanning speed. The reticle stage 3 has such a stroke that at least the entire pattern area of the reticle 2 can cross the illumination area in each of the X and Y scanning directions. At the end of the reticle stage 3, moving mirrors 5X and 5Y that reflect the laser beam from the laser interferometer 21 (see FIG. 4) are fixed along the Y and X directions, respectively. The position of the reticle stage 3 in the X and Y directions is constantly monitored by the laser interferometer 21. The position information of the reticle stage 3 from the laser interferometer 21 is supplied to the main control system 20. Based on the position information, the main control system 20 passes through a drive system (not shown) on the reticle base 4. Controls the position and speed of the reticle stage 3.

On the other hand, the wafer 6 is held and mounted on a wafer stage (substrate stage) 7 as a holding unit via a wafer holder (not shown). The wafer stage 7 is supported while floating above the wafer base (base) 8 in a plane (XY plane) perpendicular to the optical axis, and moves two-dimensionally in the XY plane 內 by driving a plane motor described later. As a result, the wafer 6 is positioned and can be moved at a predetermined scanning speed. A step-and-scan operation is repeated in which the wafer stage 7 repeats the operation of scanning exposure to each shot area on the wafer 6 and the operation of stepping to the next exposure start position. The wafer 6 can be moved in the Z direction by the wafer stage 7 and tilted with respect to the XY plane.

At the end of the wafer stage 7, movable mirrors 9X and 9Y for reflecting a laser beam from an external laser interferometer 22 (see FIG. 4) are fixed along the Y and X directions, respectively. The position of wafer stage 7 (wafer 6) is constantly monitored by laser interferometer 22. The position information of the wafer stage 7 from the laser interferometer 22 is sent to the main control system 20, and the main control system 20 determines the position and speed of the wafer stage 7 via a plane motor based on the position information. Controlling.

In the present embodiment, at the time of scanning exposure, the reticle 2 moves in the + Y direction (or For example, in synchronization with scanning at the speed VR, the shot area to be exposed on the wafer 6 moves in the one Y direction (or + Y direction) at a speed VW with respect to the exposure area. Is done. The ratio between the scanning speed VR and the speed VW (VW / VR) is exactly the same as the projection magnification of the projection optical system PL, whereby the pattern image on the reticle 2 is It is accurately transferred to each shot area.

FIG. 3 is a schematic configuration diagram of the planar motors (driving devices) 3M and 7M used in the reticle stage 3 and the wafer stage 7, respectively. Since the configuration of the planar motors 3M and 7M in both stages 3 and 7 is the same, only the reference numerals are used for the planar motor 3M for the reticle stage 3, and only the planar motor 7M for the wafer 7 is described below. explain.

The planar motor 7M shown in this figure drives the wafer stage 7 using electromagnetic force (Lorentz force), and includes a magnet array 24 and a coil array 26. The magnet array 24 is arranged adjacent to the coil array 26, supplies a permanent magnetic field that interacts with the current distribution of the coil array 26, and provides a thrust between the magnet array 24 and the coil array 26. Cause. The interaction between the magnetic field and the current distribution enables one of the magnetic array 24 and the coil array 26 to move relative to the other in at least three and preferably six degrees of freedom. ing. For example, the current in coil array 26 can interact with the magnetic field from magnet array 24 to produce forces in the X, Y, and Ζ directions, and torque around the X, Υ, and Ζ axes. it can.

The magnet array 24 is attached to the wafer stage 7 and moves with the wafer stage 7 relatively to the stationary coil array 26. Such a configuration in which the magnet moves is preferable to a configuration in which the coils move, since the magnet array 24 does not require a current connection. If coil cooling is required, cooling tubes (not shown) are attached to the coil array 26, but electrical connections and cooling tubes may interfere with the movement of the coil array 26. However, a configuration in which the coil array 26 is attached to the wafer stage 7 and is relatively moved with respect to the fixed magnet array 24 is also possible.

The coil array 26 is used to move the wafer stage 7 along the X axis. And a Y-coil array 52 for moving the wafer stage 7 along the Y-axis. A rectifying circuit and a current source (not shown) supply two-phase, three-phase, or multi-phase rectified current to the X coil array 50 to apply a thrust in the X-axis direction to the wafer stage 7. . In order to apply a thrust in the Y-axis direction to the wafer stage 7, a current rectified into two phases, three phases, or multiple phases is supplied to the Y coil array 52 by a rectifier circuit and a current source. Rectified currents are individually supplied to coils 54 in X coil array 50 to provide rotation to wafer stage 7 in an XY plane parallel to the X and Y axes. Alternatively, the current may be supplied to all the coils 54 of the X coil array 50 individually and in opposite polarities. In this case, one coil is supplied with force in one direction, and the other coil is supplied with force in the opposite direction, thereby generating a torque around the Z axis. The driving of the planar motors 3M and 7M including the rectifier circuit and the current source is controlled by the main control system 20, and the switching device according to the present invention is controlled by the planar motors 3M and 7M and the main control system 20. Is composed.

The X coil array 50 is oriented so that the coil 54 becomes the major axis in a direction perpendicular to the X axis, and the Y coil array 52 is oriented so that the coil 56 becomes the major axis in the direction perpendicular to the Y axis. Oriented to In operation, each coil 54, 56 produces a substantially constant thrust along each of the X or Y directions. In order to generate a thrust in the Y direction, a coil 56 placed directly below the magnet array 24 and the wafer stage 7 is excited. Similarly, the magnet array 24 and the coil 54 placed directly below the wafer stage 7 are excited to generate a thrust in the X direction.

To provide rotation parallel to the XY plane, either a coil 54, 56 or a coil array 52, 54, or both the X and Y coil arrays are selectively energized.

FIG. 4 is a block diagram showing a main configuration of a control system of the exposure apparatus according to the present embodiment. This control system is mainly composed of a main control system 20 composed of a microcomputer (or a workstation). As shown in this figure, the measurement results of the laser interferometers 21 and 22 are output to the main control system 20. The main control system 20 includes the reticle laser interferometer system 21 and the wafer laser interferometer system 2 The drive of the planar motors 3M and 7M is controlled based on the measurement result of 2, and the drive of the actuator 13 is controlled based on the recipe (exposure data).

Next, an exposure sequence by the exposure apparatus having the above configuration will be described with reference to a flowchart shown in FIG.

When the exposure process starts (Step S 0), the wafer 6 coated with the resist is transferred onto the wafer stage 7 (Step S 1) _{0 In} Step S 2, the reticle 2 on the reticle stage 3 is moved. Align with the coordinate system (projection optical system PL). The reticle alignment in step S2 may be performed anywhere after the reticle exchange processing until the completion of the wafer transfer processing. '

When the reticle alignment is completed, the main control system 20 drives the movable blades 11 and 12 via the actuator 13 to perform scanning exposure in the Y-axis direction (first direction). As shown in FIG. 2B, a rectangular illumination area (irradiation area) SY extending in the X-axis direction is set (step S3). In this case, the width of the rectangular illumination area in the Y-axis direction is set to be smaller than the width in the X-axis direction. When the wafer 6 is transported, the exposure apparatus performs focus adjustment in step S4, and performs positioning of the wafer W in the optical axis direction. Then, when the focus adjustment is completed, the exposure apparatus performs a wafer alignment in step S5 to perform alignment between the reticle 2 and the wafer 6. After the wafer alignment, in step S6, the projection optical system PL is adjusted based on the EGA parameters (scaling parameters) calculated based on the wafer alignment mark position information measured by an alignment system (not shown). Adjust the imaging characteristics such as the projection magnification of.

Thereafter, the wafer 6 is positioned at the scanning exposure start position according to the position information (coordinate value) of each shot on the wafer 6 calculated based on the above-mentioned EGA parameters and the design coordinate value of each shot. The scanning exposure of the reticle 2 and the wafer 6 is performed by driving the planar motors 3 M and 7 M to synchronously move the reticle stage 3 and the wafer stage 7 in the Y-axis direction with respect to the illumination area SY ( Step S7). At this time, in the projection optical system PL (optical element constituting the projection optical system), the illumination light is applied to a range corresponding to the illumination area SY, and is formed on the reticle 2 on a predetermined shot area. The resulting pattern is projected 'transferred.

Next, it is determined whether or not the exposure processing has been completed in the exposure of this shot area (step S8). If the exposure processing has been completed, the processing is terminated (step S11). It is determined whether the exposure process for the wafer 6 being processed is completed and the wafer is replaced (step S 9). If the exposure process for another shot region remains, the exposure process is performed for all the shot regions. The sequence of the above steps S7 to S9 is sequentially repeated until the process is performed.

On the other hand, when wafer replacement is performed in step S9, the process returns to step S1 to perform wafer transfer (unloading and loading), and changes the mounting direction of the reticle 2 in step S10. Specifically, the reticle 2 placed on the reticle stage 3 in response to the synchronous movement in the Y-axis direction is moved to the reticle stage 3 in order to correspond to the synchronous movement in the X-axis direction (second direction). ° Rotate and place. This change of the mounting direction is performed, for example, by detaching the reticle 2 from the reticle stage 3 by using a reticle transport device (not shown), and then setting the reticle 2 to 90. After rotation, a method of mounting the reticle on the reticle stage 3 again can be adopted. The reticle 2 mounting direction can be changed before or after wafer transport if it is before the reticle alignment.

Subsequently, the sequence of the above steps S2 to S7 is executed. In step S3, the main control system 20 drives the movable blades 11 and 12 via the actuator 13 and the X-axis In order to perform scanning exposure in the direction, the setting is changed to a rectangular illumination area SX extending in the Y-axis direction as shown in FIG. 2C. In this case, the rectangular illumination area is set to have a smaller width in the X-axis direction than in the Y-axis direction. In step S7, in response to the exchange of the wafer 6, the main control system 20 controls the driving of the planar motors 3M and 7M as a control device and a change device, thereby causing the reticle stage 2 and the wafer Change and switch the direction of synchronous movement with Tage 7 to X axis. That is, in the present embodiment, the main control system 20 alternately changes / switches the synchronous movement direction according to the number of processed wafers (here, each time the wafer is replaced).

As a result, in the projection optical system PL (optical element constituting the projection optical system), the illumination light is applied to an area corresponding to the illumination area SX different from the illumination area SY, and the predetermined light is projected onto the reticle 2 on a predetermined shot area. The pattern formed on is projected and transferred. As described above, in the present embodiment, the illumination area and the synchronous movement direction are switched each time the wafer is replaced. Therefore, when the illumination area of the illumination light to the projection optical system PL is considered on a time average basis, the illumination areas SY and SX are combined. Can be made equivalent to a cross shape. Therefore, in the present embodiment, the heat of absorption of the irradiation energy in the optical element of the projection optical system PL can be dispersed, and the non-rotational symmetry of the temperature distribution of the optical element due to the heat of absorption can be reduced. As a result, in the present embodiment, by suppressing non-rotationally symmetric aberrations generated in the projection optical system PL, it is possible to maintain excellent imaging characteristics, and achieve a uniform and desired line width on the wafer 6. It is possible to manufacture a highly integrated device by forming a fine pattern having a pattern, and reduce device defects due to non-rotationally symmetric aberrations.

FIG. 6 is a diagram showing a scanning exposure apparatus according to a second embodiment of the present invention.

In this figure, the same elements as those of the first embodiment shown in FIGS. 1 to 5 are denoted by the same reference numerals, and description thereof will be omitted. The difference between the second embodiment and the first embodiment is the configuration of the reticle stage 2, the wafer stage 7, and the configuration of the motor that drives these stages. Since the configurations of reticle stage 2 and wafer stage 7 are the same, only wafer stage 7 will be described below.

As shown in FIG. 6, in the present embodiment, a wafer stage (holding unit) 7 Y, which is supported above the wafer base 8 while floating above the wafer base 8 and synchronously moves and scans in the Y-axis direction, A wafer stage (holding unit) 7X that moves synchronously and runs is provided.

The wafer stage 7γ is movably supported by an X guide 31 extending in the X direction, and is moved in the X direction by driving the X linear motors 32, 32 using the X guide 31 as a guide. At one end of X guide 3 1 A mover 33 is provided. The mover 33 moves relative to a stator 34 provided on one side edge of the wafer base 8 along the Y direction. The mover 33 and the stator 34 constitute a Y linear motor 35. Similarly, the wafer stage 7X is movably supported by a Y guide 41 extending in the Y direction, and is driven by the Y linear motors 42 and 42 so that the Y guide 41 guides the Y guide 41 to move in the Y direction. Go to At one end of Y guide 41. Mover 4 03 06342

12

Three are provided. The mover 43 moves relative to the stator 44 installed on one side edge of the wafer base 8 along the X direction. The mover 43 and the stator 44 constitute an X linear motor 45.

Each of the wafer stages 7X and 7Y is set to be movable to a position directly below the projection optical system PL, and when the other stage moves to a position directly below the projection optical system PL, the other stage and the linear stage are moved. It is configured to be able to retreat to a position that does not interfere with the motor and guide. The retracted position of each wafer stage is set to an alignment position by an alignment system (not shown). Other configurations are the same as those of the first embodiment.

In the exposure apparatus having the above configuration, for example, while the wafer stage 7X is retracted, the reticle 2 and the wafer 6 are moved by driving the γ linear motor 35 to move the wafer stage 7Y in the Y-axis direction. Scanning exposure is performed by synchronously moving in the Y-axis direction. Then, when the exposure processing of the wafer held on the wafer stage 7Y is completed, the exposure processing is continuously performed on the wafer held on the wafer stage 7X. That is, by moving the wafer stage 7X in the X-axis direction by driving the X linear motor 45 while the wafer stage 7Y is retracted with respect to the wafer stage 7X, the reticle 2 and the wafer 6 are moved. Are moved synchronously in the X-axis direction to perform scanning exposure. Although not described in detail, the illumination area is also switched by the movable blades 11 and 12 in accordance with the switching of the synchronous movement direction, and the reticle is also synchronized with the movement of the wafer by a not-shown remorse motor (which is different from the wafer 6). Move in the opposite direction). At the retracted wafer stage, wafer replacement, wafer alignment, etc. are performed.

As described above, the illumination area is changed according to the number of processed wafers (here, each time the wafer is replaced), and the wafer stage used for scanning exposure is switched for each wafer. The absorption heat of the irradiation energy in the optical element of the projection optical system PL can be dispersed, so that the same effects as those of the first embodiment can be obtained. Time can be saved, which can contribute to an improvement in throughput.

In the above embodiment, both the reticle stage and the wafer stage are driven by the planar motor or the linear motor. However, the present invention is not limited to this. For example, a configuration may be adopted in which one of the reticle stage and the wafer stage is driven by a planar motor, and the other is driven by a linear motor.

In the above-described embodiment, the illumination area and the synchronous movement direction are switched every time the wafer is exchanged at a predetermined timing. In addition, the procedure is switched every time a plurality of wafers are exchanged, or every predetermined time elapses. Alternatively, the switching may be performed based on the incident history (for example, the incident time) of the illumination light incident on the projection optical system. In addition, a light quantity detector (detector) may be arranged in the illumination light path to monitor the integrated light quantity. It is also possible to switch the illumination area and the synchronous movement direction every time the integrated light amount exceeds a predetermined amount.

In the above embodiment, the illumination area and the synchronous movement direction are switched in the X-axis direction and the Y-axis direction, which are substantially orthogonal to each other, so that the configuration can be easily dealt with by a normally used linear motor. Instead, they may be moved synchronously in an oblique direction. By setting the synchronous movement direction to multiple directions in this way, the heat of absorption of irradiation energy in the optical element of the projection optical system PL can be further dispersed, and the non-rotational symmetry of the temperature distribution of the optical element can be reduced. It is possible to further ease. The irradiation area is not limited to a rectangle, and may be an arc-shaped area.

The substrate of the present embodiment includes not only a semiconductor wafer 6 for manufacturing a semiconductor device, but also a glass substrate for a display device, a ceramic wafer for a thin-film magnetic head, or an original mask or reticle used in an exposure apparatus (synthesis). Quartz, silicon wafer, etc. are applied.

As the exposure apparatus, a step of scanning and exposing the pattern of the reticle R by synchronously moving the reticle R and the wafer W, and a scanning type exposure apparatus of the scan type (scanning stepper; USP5,473,410). In addition, in the case of having an optical element that generates aberrations that are not rotationally symmetric, the reticle R and the wafer W are stationary, the pattern of the reticle R is exposed, and the wafer W is sequentially step-moved. It can also be applied to a projection exposure apparatus (stepper). The present invention can also be applied to a step-and-stitch type exposure apparatus in which at least two patterns are partially overlapped and transferred on a wafer W.

As the type of the exposure apparatus, a semiconductor element for exposing a semiconductor element pattern It is not limited to an exposure apparatus for manufacturing a device, but also an exposure apparatus for manufacturing a liquid crystal display element or a display, an exposure apparatus for manufacturing a thin B-magnet magnetic head, an imaging device (CCD), a reticle or a mask, and the like. Widely applicable.

Light source (g-line (436 nm), h-line (404 nm), i-if spring (365 nm)), KrF excimer laser (248 nm), ArF excimer laser (1 93 nm), F ₂ laser (1 57 nm), not only a r ₂ laser (1 2 6 nm), as possible out using a charged particle beam such as an electron beam or an ion beam. For example, as the electron gun in the case of using an electron beam, thermionic emission type Kisaborai bets to lanthanum (L a B _6), can be used tantalum (T a). A harmonic such as a YAG laser or a semiconductor laser may be used.

For example, a single-wavelength laser in the infrared or visible range oscillated by a DFB semiconductor laser or fiber laser is amplified by a fiber amplifier doped with erbium (or both erbium and yttrium), and a nonlinear optical crystal is amplified. Alternatively, a harmonic converted to ultraviolet light may be used as exposure light. Assuming that the oscillation wavelength of the single-wavelength laser is in the range of 1.544 to 1.553 m, the 8th harmonic in the range of 193 to 194 ηm, that is, the ultraviolet that has almost the same wavelength as the ArF excimer laser If light is obtained and the oscillation wavelength is in the range of 1.57 to 1.58 μπι, the 10th harmonic in the range of 157 to 158 nm, that is, ultraviolet light that has almost the same wavelength as the F ₂ laser Light is obtained.

A laser plasma light source or a soft X-ray region having a wavelength of about 5 to 5 O nm generated from an SOR, for example, EUV (Extreme Ultra Violet) light having a wavelength of 13.4 nm or 11.5 nm is used as exposure light. The EUV exposure apparatus uses a reflective reticle, and the projection optical system is a reduction system including only a plurality of (eg, about 3 to 6) reflective optical elements (mirrors).

The projection optical system PL may be not only a reduction system but also an equal magnification system or an enlargement system. Further, the projection optical system PL may be any of a refractive system, a reflective system, and a catadioptric system. When the wavelength of the exposure light is less than about 200 nm, it is desirable to purge the optical path through which the exposure light passes with a gas that absorbs less exposure light (an inert gas such as nitrogen or helium). When an electron beam is used, an electron lens and a deflection An electron optical system consisting of a vessel may be used. The optical path through which the electron beam passes is evacuated.

When a linear motor (see US Pat. No. 5,623,853 or US Pat. No. 5,528,118) is used for the wafer stage 7 ゃ reticle stage 3, an air levitation type using an air bearing and a magnetic levitation type using Lorentz force or reactance force are used. You can use either. Each of the stages 3 and 7 may be of a type that moves along a guide or a guideless type that does not have a guide.

The reaction force generated by the movement of the wafer stage 7 is not transmitted to the projection optical system PL as described in Japanese Patent Application Laid-Open No. Hei 8-166475 (US Pat. No. 5,528,118). It may be used to mechanically escape to the floor (ground).

The reaction force generated by the movement of the reticle stage 3 is not transmitted to the projection optical system PL, as described in JP-A-8-330224 (US S / N 08 / 416,558). Alternatively, it may be mechanically released to the floor (ground) using a frame member.

As described above, the exposure apparatus according to the embodiment of the present invention performs various subsystems including each component listed in the claims of the present application so as to maintain predetermined mechanical accuracy, electrical accuracy, and optical accuracy. It is manufactured by assembling. To ensure these various precisions, before and after this lamination, adjustments to achieve optical precision for various optical systems, adjustments to achieve mechanical precision for various mechanical systems, Various electrical systems are adjusted to achieve electrical accuracy. The process of assembling the exposure apparatus from various subsystems includes mechanical connections, wiring connections of electric circuits, and piping connections of pneumatic circuits among the various subsystems. It goes without saying that there is an individual assembly process for each subsystem before the assembly process from these various subsystems to the exposure apparatus. When the process of assembling the various subsystems into the exposure apparatus is completed, comprehensive adjustment is performed, and various precisions of the entire exposure apparatus are secured. It is desirable to manufacture the exposure equipment in a clean room where the temperature and cleanliness are controlled. For microdevices such as semiconductor devices, as shown in Fig. 7, step 201 for designing the function and performance of the microdevice, step 202 for fabricating a mask (reticle) based on this design step, and silicon material Step of manufacturing wafer from wafer 203. Using the exposure apparatus of the above-described embodiment, the reticle pattern is It is manufactured through an exposure processing step 204 for exposing to light, a device assembling step (including a dicing step, a bonding step, and a package step) 205, and an inspection step 206. Industrial applicability

According to the present invention, by suppressing non-rotationally symmetric aberrations generated in the projection optical system, it is possible to maintain excellent imaging characteristics, and have a uniform and desired line width on the substrate. A highly integrated device can be manufactured by forming a fine pattern, and device defects due to non-rotationally symmetric aberrations can be reduced. When a plurality of stages are provided, the time required for substrate exchange / alignment can be omitted, which can contribute to an improvement in throughput.

Claims

The scope of the claims

1. A scanning exposure apparatus that synchronously moves a mask and a substrate with respect to exposure light in a first direction, and projects a pattern image of the mask onto the substrate via a projection optical system, A changing device that changes a setting of an exposure light irradiation area, and a second direction different from the first direction in a direction of synchronous movement between the mask and the substrate with the change of the exposure light irradiation area. And a switching device for switching to.

2. The scanning exposure apparatus according to claim 1, wherein the switching device includes: a mask stage that moves while holding the mask; and a substrate stage that moves while holding the substrate. It has a driving device that moves each corresponding to the irradiation area.

3. The scanning exposure apparatus according to claim 2, wherein

The driving device includes: a base; a holding unit that holds the mask or the substrate and floats above the base; and a planar motor device that drives the holding unit in a plane along the base.

4. The scanning exposure apparatus according to claim 1, wherein

The switching device changes the irradiation area at an arbitrary timing.

5. The running type exposure apparatus according to claim 4, wherein

The arbitrary timing includes an incident history of the exposure light incident on the projection optical system, or the number of processed substrates.

6. The scanning exposure apparatus according to claim 2 or 4, wherein

A plurality of at least one of the mask stage and the substrate stage are provided so that the directions of the synchronous movement are different from each other.

7. The scanning exposure apparatus according to claim 1, wherein

The changing device changes an irradiation area of the exposure light extending in the second direction to an irradiation area of the exposure light extending in the first direction.

8. A scanning exposure method for projecting a pattern image of the mask onto the substrate via a projection optical system by synchronously moving a mask and a substrate in a first direction with respect to exposure light, Changing the setting of the exposure area of the exposure light, and changing the direction of the synchronous movement between the mask and the substrate in a second direction different from the first direction with the change of the exposure area of the exposure light. Including the step of switching.

9. The scanning exposure method according to claim 8, wherein

The method further includes a step of changing the irradiation area at an arbitrary timing.

10. The scanning exposure method according to claim 8, wherein

A plurality of at least one of the mask stage and the substrate stage are provided, and directions of the synchronous movement are different between the plurality of stages.

11. The scanning exposure method according to claim 8, wherein

The irradiation area extends in a direction substantially orthogonal to the first direction or the second direction.