Moving apparatus, exposure apparatus, and device manufacturing method

A moving apparatus including a movable portion which is supported so as to move in a first direction, a first actuator having a movable element and a stator, the movable element being connected to the movable portion, a reference structure which has a guide surface parallel to the first direction and which supports the stator in the first direction, a second actuator configured to drive the stator in a rotation direction around an axis which is perpendicular to the guide surface, and a control unit configured to control the second actuator so as to suppress the rotation of the stator accompanied by the movement of the movable portion.

This application also claims the benefit of Japanese Patent Application No. 2002-295014, filed on Oct. 8, 2002, which is hereby incorporated by reference herein in its entirety.

FIELD OF THE INVENTION

The present invention relates to a moving apparatus, an exposure apparatus, and a device manufacturing method.

BACKGROUND OF THE INVENTION

In recent years, demand has arisen for higher-accuracy control for a moving apparatus which moves with an object such as a structure placed on its stage. For example, with an exposure apparatus used for the manufacture of semiconductor devices, or the like, as the integration density of the semiconductor devices increases, a higher-accuracy micropatterning technique is demanded. In order to realize this, a moving apparatus, such as a wafer stage, must be controlled at a high accuracy.

Typical examples of an exposure apparatus used for the manufacture of semiconductor devices include a step-and-repeat exposure apparatus (to be referred to as a “stepper” hereinafter) and a step-and-scan exposure apparatus (to be referred to as a “scanner” hereinafter).

A stepper is an exposure apparatus that sequentially exposes the pattern of a master (e.g., a reticle, mask, or the like) onto a plurality of exposure regions on a substrate (e.g., a wafer, glass substrate, or the like), used for manufacturing semiconductor devices, through a projection optical system while stepping the substrate.

A scanner is an exposure apparatus that repeats exposure and transfer onto the plurality of regions on the substrate by repeating stepping and scanning exposure. The scanner limits exposure light with a slit, so that it uses that portion of a projection optical system which is relatively close to the optical axis. For this reason, generally, the scanner can expose a fine pattern with a wider angle of view at higher accuracy than with the stepper.

Such an exposure apparatus has a stage (e.g., a wafer stage, a reticle stage, or the like) for moving a wafer or reticle at a high speed. When the stage is driven, a reaction force of an inertial force accompanying acceleration and deceleration of the stage occurs. When the reaction force is transmitted to the stage surface plate, the stage surface plate swings or vibrates. Consequently, characteristic vibration is excited in the mechanical system of the exposure apparatus to generate high-frequency vibration. This vibration interferes with high-accuracy control for the moving apparatus.

To decrease the vibration of the apparatus caused by the reaction force, a moving apparatus as shown inFIG. 6is proposed. As shown inFIG. 6, a conventional moving apparatus has a stage51and a movable body (to be referred to as a “counter” hereinafter)52for canceling the reaction force. The stage51and counter52are driven by feedback control controlling a position in the Y direction, and a target value is given such that the ratio of the moving distance of the stage51in the Y direction to that of the counter52in the Y direction is substantially constant. This improves the canceling efficiency for the reaction force of the stage51.

With the conventional moving apparatus, however, as shown inFIG. 6, it is difficult to overlay the power point in the X direction of the stage51and the barycenter in the X direction of the counter52completely. Hence, due to the displacement in the X direction of the power point of the stage51and the barycenter of the counter52, when the stage51moves in the Y direction, a moment is produced in the counter52, and the counter52rotates. Therefore, with the conventional moving apparatus, it is difficult to control positioning of the stage at high accuracy.

SUMMARY OF THE INVENTION

The present invention has been made in view of the above problem, and has as its object to control, e.g., positioning of a stage at high accuracy.

The first aspect of the present invention relates to a moving apparatus, characterized by comprising a first actuator having a movable element and a stator, a second actuator which drives the stator, wherein the second actuator drives the stator in a direction to suppress rotation of the stator which accompanies movement of the movable element. The second actuator comprises an actuator which drives the stator in the Y direction and an actuator which drives the stator in the X and θ directions.

A preferred embodiment of the present invention preferably comprises a feed forward compensator which controls the second actuator on the basis of a signal supplied to the first actuator or a physical quantity of the movable element.

A preferred embodiment of the present invention further preferably comprises a compensator which controls the second actuator on the basis of an acceleration of the movable element.

According to a preferred embodiment of the present invention, a target acceleration is preferably used as the acceleration of the movable element.

According to a preferred embodiment of the present invention, an actual acceleration measured by a measurement unit is preferably used as the acceleration of the movable element.

According to a preferred embodiment of the present invention, the signal preferably includes a manipulated variable with which the first actuator is operated.

According to a preferred embodiment of the present invention, a gain of the compensator is preferably determined in accordance with a distance between a power point of the movable element in a predetermined direction and a barycenter of the stator when the movable element is driven by the first actuator.

According to a preferred embodiment of the present invention, the stator preferably absorbs a reaction force that acts on the stator when the movable element is driven by the first actuator.

A second aspect of the present invention relates to an exposure apparatus, characterized by comprising an optical system which projects exposure light, to be irradiated to a master having a pattern, onto a substrate, a stage which can move while holding the substrate or the master, a first actuator having a movable element and a stator, the movable element being connected to the stage, a second actuator which drives the stator in the Y direction, and a third actuator which drives the stator in the X and θ directions, wherein the third actuator drives the stator in a direction to suppress rotation of the stator which accompanies movement of the movable element.

A third aspect of the present invention relates to a semiconductor device manufacturing method, characterized by comprising an applying step of applying a photosensitive material on a substrate, an exposure step of transferring a pattern onto the substrate, applied with the photosensitive material in the applying step, by utilizing the above exposure apparatus, and a developing step of developing the photosensitive material on the substrate where the pattern has been transferred in the exposure step.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. The same constituent elements in the drawings are denoted by the same reference numerals.

First Embodiment

A moving apparatus as the first preferred embodiment of the present invention will be described with reference to the drawings.

FIG. 1Ais a plan view showing the arrangement of the moving apparatus according to a preferred embodiment of the present invention, andFIG. 1Bis a sectional view of the same. As shown inFIG. 1B, a flat guide surface6as the reference surface of the moving apparatus is formed on a reference structure4. A movable portion3is supported above the flat guide surface6in a non-contact manner by static pressure bearings7. As shown inFIG. 1A, the movable portion3can move in the Y direction along the flat guide surface6. Electromagnetic actuators8and8′ for moving the movable portion3in the Y direction are provided on the two sides of the movable portion3, as shown inFIG. 1B. The movable portion3, is driven by the two sets of electromagnetic actuators8and8′. The electromagnetic actuators8and8′ include movable elements2and2′ connected to the movable portion3, which moves along the flat guide surface6, and stators1and1′. For example, a top plate5is formed on the movable portion3. A moving target object (e.g., a wafer or the like) can be placed on the top plate5.

The stators1and1′ are supported above the flat guide surface6in a non-contact manner by static pressure bearings9, and can move in the Y direction. The stators1and1′ have predetermined masses, and can absorb a reaction force generated by acceleration and deceleration of the movable portion3. The stators1and1′ can be formed of permanent magnets, and the movable elements2and2′ can be formed of coils. Conversely, the stators1and1′ may be formed of coils, and the movable elements2and2′ may be formed of permanent magnets.

One or a plurality of interferometers (not shown) is provided to control the moving apparatus, and can position the movable elements2and2′ or movable portion3with reference to the reference structure4. Similarly, an interferometer (not shown) for measuring the positions of the stators1and1′ is provided to position the stators1and1′ which move within a plane. In the above manner, a movable body300serving as a stage having the movable portion3(including the top plate5provided on it) and the movable elements2and2′ can move in the Y direction in a non-contact manner with the flat guide surface6.

When the movable body300moves, the stators1and1′ receive the reaction force of a force acting on the movable body300. Upon reception of the reaction force, the stators1and1′ can move along the flat guide surface6. More specifically, the stators1and1′ serve to absorb the reaction force accompanying the driving operation of the movable body300by moving along the flat guide surface6. For example, when the movable body300, including the movable portion3, and the like, is driven in the +Y direction, the stators1and1′ receive the reaction force in the −Y direction and move in the −Y direction, so that they can absorb the reaction force.

As described above, the reaction force during acceleration and deceleration, which acts on the movable body300when it moves, can be absorbed by the stators1and1′. The reaction force is converted into kinetic energy when the stators1and1′ (reaction force movable portion), which have received the reaction force, move. Although two stators are provided in this case, the present invention is not limited to this. The number of stators may be one, or three or more.

With the above arrangement, the force acting on the movable body300and its reaction force are limited on the flat guide surface6of the reference structure4. Hence, the reference structure4can be prevented from vibrating due to the driving force acting on the movable body300and the reaction force acting on the stators1and1′. Furthermore, according to this embodiment, vibration can be prevented from transmitting to the floor of the area where the moving apparatus is installed, or to other apparatuses.

When the masses of the stators1and1′ are increased to be sufficiently larger than the mass of the movable body300including the movable portion3, and the like, the movable range of the stators1and1′ can be limited to be small. This enables downsizing of the apparatus, and reduces the floor area of the semiconductor factory, thus contributing to the reduction of the construction cost of the entire semiconductor factory.

A more practical arrangement of the moving apparatus according to the first preferred embodiment of the present invention will be described.FIG. 2shows the more practical arrangement of the moving apparatus according to the preferred embodiment of the present invention. As shown inFIG. 2, the flat guide surface6as the reference surface of the moving apparatus is formed on the reference structure4. The movable portion3(seeFIG. 1B) provided under the top plate (X-Y stage)5is supported on the flat guide surface6in a non contact manner through the static pressure bearings7, and can move in an X-Y direction. The electromagnetic actuators8(not shown) and8′ for driving the movable portion3with a long stroke in the Y direction and with a short stroke in the X direction are provided on the two sides of the movable portion3. The electromagnetic actuators8and8′ include the movable elements2and2′ and stators1and1′ which are separate from and independent of each other on the right and left sides (seeFIGS. 1A and 1B). Two, right and left movable-portion Y magnets10and two, right and left movable-portion X magnets11are attached to the right and left movable elements2and2′. The stators1and1′ are supported on the flat guide surface6in a non-contact manner through the static pressure bearings8(seeFIG. 1B), and can move in the X-Y direction (planar directions). The stators1and1′ have predetermined masses, and can absorb the reaction force, generated by acceleration and deceleration of the movable body300including the movable portion3and movable elements2and2′, by moving on the flat guide surface6. X-axis linear motor single-phase coils12and Y-axis linear motor multiphase coils13having an array of a plurality of coils in the Y direction are arranged in the stators1and1′, and are switched to achieve movement in the X and Y axes.

The position of the top plate (X-Y stage)5is measured by a laser interferometer formed of a laser head16, a Y-axis measurement mirror17, an X-axis measurement bar mirror18, left and right two Y-axis measurement detectors19, front and rear two X-axis measurement detectors20, and the like. More specifically, optical elements22and22′ loaded on the top plate5are irradiated with laser beams in the Y direction. The measurement beams are reflected or polarized in the X-axis direction to irradiate the X axis measurement bar mirror18, and are measured by the X-axis measurement detector20, so that the position in the X-axis direction of the top plate5is measured. The position in the Y-axis direction of the top plate5is measured in the following manner. The Y-axis measurement mirror17is irradiated with a laser beam in the Y direction, and the laser beam is measured by the Y-axis measurement detector19. The positions in the Y-axis direction of the stators1and1′ are measured by two, right and left stator Y-axis measurement detectors21.

The movable portion3in which the substrate (wafer) is placed on the top plate (X-Y stage)5is moved in the X-Y direction by the electromagnetic actuators8and8′ constituted by the movable elements2and2′ and stators1and1′. The stators1and1′ receive the reaction force of the force acting on the movable body300, including the movable portion3and movable elements2and2′. The stators1and1′ move on the flat guide surface6by the reaction force. The stators1and1′ can absorb the reaction force by moving on the flat guide surface6. In this embodiment, when the movable body300including the movable portion3moves in the +Y direction, the stators1and1′ receive the reaction force in the −Y direction and move in the −Y direction.

Furthermore, according to this embodiment, as the actuators for driving the stators1and1′ in the Y-axis direction, two, right and left Y-axis position control linear motors14and14′ are provided to the reference structure4. Similarly, four, left, right, front, and rear X-axis position control linear motors15and15′ for driving the stators1and1′ in the X-axis direction are provided to the reference structure4.

A total of four, front and rear X direction position measurement units (not shown) are provided, two on the left side of the support line of the X-axis position control linear motor15and two on the right side of the support line of the X-axis position control linear motor15′, so that the positions in the X direction of the stators1and1′ can be measured.

A process of the moving apparatus according to the first preferred embodiment of the present invention will be described.

FIG. 3is a control block diagram of the moving apparatus according to the first preferred embodiment of the present invention. A feedback control system A is a feedback control system for the movable elements2and2′, and a feedback control system B is a feedback control system for the stators1and1′. The target value R1of the feedback control system A is fed forward to the feedback control system B via a derivative element (K*s*s).

As shown inFIG. 1B, a case will be described wherein the movable portion3having the top plate5is to be driven in the Y direction by the electromagnetic actuators8and8′ having the movable elements2and2′ connected to the movable portion3and stators1and1′. The movable portion3is positioned when the electromagnetic actuators8and8′ including the movable elements2and2′ and stators1and1′ are feedback-controlled on the basis of the position information of the movable portion3measured by the Y-axis measurement detectors19. Reference numeral P1(s) denotes the dynamic characteristics of the electromagnetic actuators8and8′, including the movable elements2and2′ and stators1and1′. An output from P1(s) indicates the measurement position, i.e., a position Y1of the movable portion3measured by the Y-axis measurement detectors19. A compensator C1(s) provides a manipulated variable to P1(s), i.e., the electromagnetic actuators8and8′ on the basis of the deviation between target value R1and controlled variable Y1.

As described above, the movable portion3can be driven to a predetermined position by causing the controlled variable (position controlled variable) Y1of the movable portion3to follow a target value (position target value) R1with the feedback control system A of the movable portion3.

The moving apparatus according to the first preferred embodiment of the present invention has the feedback control system B for controlling the rotation amount on the X-Y plane of the stators1and1′, so that the stators1and1′ are kept horizontal to the movable direction (Y direction) of the movable portion3. Referring toFIG. 3, reference numeral P2(s) denotes the dynamic characteristics of electromagnetic actuators having the linear motors15and15′ and right and left stators1and1′ for driving the stators1and1′. An output from P2(s) indicates the measurement position, i.e., a rotation amount θ1of the stator elements1and1′. The rotation amount θ1is calculated by the two X-direction position measurement units (not shown) attached to each of the stators1and1′. A compensator C2(s) is arranged as an input stage with respect to the stators1and1′ serving as the control target. A compensator C2(s) provides a manipulated variable to P2(s), i.e., the electromagnetic actuators for driving the stators1and1′ on the basis of the deviation between target value zero and the rotation amount θ1.

With the above arrangement, in the feedback control system B for the stators1and1′, the target value is set to 0, so that the rotation amount of the stators1and1′ can be kept at zero.

According to this embodiment, as shown inFIG. 3, the derivative element (K*s*s) differentiates the target value R1for controlling the movable elements2and2′ and feeds forward the target acceleration calculated from the target value to the feedback control system B, which controls the rotation amount of the stators1and1′. Reference symbol K denotes the feed forward gain of a signal to be supplied to the electromagnetic actuators of the feedback control system B. According to this embodiment, a manipulated variable to P2(s), i.e., the electromagnetic actuators for driving the stators1and1′ is generated by combining the target acceleration calculated by the derivative element (K*s*s) and the output from the compensator C2(s). Hence, in the feedback control system B, the electromagnetic actuators for driving the stators1and1′ can be controlled to suppress the rotation of the stators1and1by applying the target acceleration calculated by the derivative element (K*s*s) to the manipulated variable in advance. The stators1and1′ can be driven in the direction to suppress their rotation that accompanies the movement of the movable elements2and2′. As a result, rotation of the stators1and1′, which occurs when accelerating the movable elements2and2′ and movable portion3, is suppressed, so that the stage can be positioned at high accuracy.

Second Embodiment

FIG. 4is a control block diagram of a moving apparatus according to the second preferred embodiment of the present invention. In this embodiment, the output from the compensator C1(s) is fed forward to the feedback control system B via a proportional element (K). As shown inFIG. 4, a manipulated variable for manipulating the electromagnetic actuators8and8′ of a feedback control system A is increased by a factor of N and is fed forward to a feedback control system B which controls the rotation amount of stators1and1′. Similarly to the first embodiment, reference symbol K denotes the feed forward gain of a signal to be supplied to the electromagnetic actuators of the feedback control system B. According to this embodiment, a manipulated variable to P2(s), i.e., the electromagnetic actuators for driving the stators1and1′ is generated by combining the output from the compensator C1(s) being increased by a proportional element (K) by a factor of N and the output from the compensator C2(s). Hence, in the feedback control system B, the electromagnetic actuators for driving the stators1and1′ can be controlled to suppress the rotation of the stators1and1′ by applying the output from the compensator C1(s) being increased by a proportional element (K) by a factor of N to the manipulated variable in advance.

Third Embodiment

FIG. 5is a block diagram of a moving apparatus according to the third preferred embodiment of the present invention. In this embodiment, the controlled value (position information) of the feedback control system A is fed forward to the feedback control system B via a derivative element (K*s*s). As shown inFIG. 5, the derivative element (K*s*s) differentiates the position information Y1of movable elements2and2′ measured by Y-axis measurement detectors19, a feedback control system A feeds forward the acceleration (actual acceleration) of the movable elements2and2′ calculated from the position information to a feedback control system B, which controls the rotation amount of stators1and1′. In the same manner as in the first and second embodiments, reference symbol K denotes the feed forward gain of a signal to be supplied to the electromagnetic actuators of the feedback control system B. According to this embodiment, a manipulated variable to P2(s), i.e., the electromagnetic actuators for driving the stators1and1′ is generated by combining the actual acceleration calculated by the derivative element (K*s*s) and the output from the compensator C2(s). Hence, in the feedback control system B, the electromagnetic actuators for driving the stators1and1′ can be controlled to suppress the rotation of the stators1and1′ by applying the target acceleration calculated by the derivative element (K*s*s) to the manipulated variable in advance. An acceleration meter may be provided in place of the Y-axis measurement detectors19.

Other Embodiment

A moving apparatus according to a preferred embodiment of the present invention is formed such that its movable portion3is movable in the X direction and the power point in the X direction of the movable portion3with respect to counter masses (stators)1and1′ changes in accordance with the position in the X direction of the movable portion3. In this case, the moving apparatus can be formed such that the gain (feed forward gain) of a signal to be supplied to the electromagnetic actuators of a feedback control system B changes in accordance with the distance between the power points of movable elements2and2′ during driving in the X direction and the barycenters of the stators1and1′. This enables higher accuracy positioning control.

As described above, according to the preferred embodiment of the present invention, when the signal used in the control system for the movable portion is fed forward to a control system for the stators, swing, rotation, and the like, of the stators, which occur due to acceleration of the movable elements, can be suppressed.

FIG. 7is a conceptual view of an exposure apparatus, which is used when the moving apparatus according to any preferred embodiment of the present invention is applied to a semiconductor device manufacturing process. Referring toFIG. 7, a reticle72serving as a master is irradiated with light emerging from an illumination optical system71. The reticle72is held on a reticle stage73, and its pattern is reduced and projected with the magnification of a reduction projection lens74to form a reticle pattern image on the image surface of the reduction projection lens74. The image surface of the reduction projection lens74is perpendicular to the Z direction. A resist is applied to the surface of a substrate75as an exposure target sample, and shots formed in an exposure process are arrayed on the resist. The substrate75is placed on a stage300including a movable body, and the like. The stage300is formed of a chuck for fixing the substrate75, an X-Y stage horizontally movable in X- and Y-axis directions, and the like. The position information of the stage300is constantly measured by a stage interferometer78with respect to a mirror77fixed to the stage300. The moving apparatus according to the embodiment of the present invention generates a control signal from a position signal output from the stage interferometer78, and the like, and controls the position of the stage300.

The exposure apparatus may perform scanning and exposure of transferring a predetermined region of the pattern of a master onto a substrate by moving and scanning both the master and substrate with respect to an optical system. In this case, the exposure apparatus can drive at least one of the master and substrate during scanning by means of a stage provided to the moving apparatus according to any preferred embodiment of the present invention. Ultraviolet rays may be used as the exposure light. In this case, as the ultraviolet rays, for example, a laser beam from a fluorine eximer laser, an ArF eximer laser, or the like, which uses a laser as the light source, is preferably used.

A semiconductor device manufacturing process utilizing the above exposure apparatus will be described.FIG. 8is a flow chart of the flow of the overall semiconductor device manufacturing process. In step1(circuit design), circuit design of a semiconductor device is performed. In step2(mask fabrication), a mask is fabricated based on the designed circuit pattern. In step3(wafer fabrication), a wafer is manufactured by using a material such as silicon. In step4(wafer process), called a pre-process, an actual circuit is formed on the wafer by lithography using the prepared mask and wafer. In step5(assembly), called a post-process, a semiconductor chip is formed by using the wafer fabricated in step4, and includes processes such as an assembly process (dicing and bonding) and a packaging process (chip encapsulation). In step6(inspection), inspections such as the operation confirmation test and durability test of the semiconductor device fabricated in step5are performed. After these steps, the semiconductor device is completed, and shipped (step7).

FIG. 9is a flow chart showing the detailed flow of the wafer process. In step11(oxidation), the surface of the wafer is oxidized. In step12(CVD), an insulating film is formed on the wafer surface. In step13(electrode formation), an electrode is formed on the wafer by vapor deposition. In step14(ion implantation), ions are implanted in the wafer. In step15(resist processing), a photosensitive agent is applied to the wafer. In step16(exposure), the circuit pattern is transferred to the wafer by using the above exposure apparatus. In step17(development), the exposed wafer is developed. In step18(etching), the resist is etched except for the developed resist image. In step19(resist removal), an unnecessary resist after etching is removed. These steps are repeated to form multiple circuit patterns on the wafer.

According to the present invention, for example, positioning of a stage can be controlled at high accuracy.