JP2005086093A - Aligner and method of controlling stage apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve the throughput of an aligner by enabling the aligner to align a wafer to be treated next while another wafer is being exposed to light. <P>SOLUTION: The aligner has an exposure stage 4 used for executing exposure treatment, and an alignment stage 7 used for executing alignment and measurement. The exposure stage 4 and alignment stage 7 can operate and execute the exposure treatment and alignment and measurement in a state where holding units for wafers are respectively fitted to the stages 4 and 7, independently. Each holding unit which holds the wafer has a stage reference mark for alignment and measurement, and can be fitted to and removed from the exposure and alignment stages 4 and 7. A chuck transporting robot 12 fits a holding unit fitted to the alignment stage 7 to the exposure stage 4 by moving the unit to the stage 4 in a state where a wafer is held by and fixed to the unit. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an exposure apparatus used in a semiconductor manufacturing process, and more particularly to a projection exposure apparatus that projects and transfers a pattern of a mask original plate such as a reticle onto a photosensitive substrate such as a silicon wafer. More specifically, the present invention relates to a stage apparatus that moves a photosensitive substrate relative to a projection optical system when a reticle pattern is projected and exposed onto a wafer.

  A general exposure apparatus and its stage apparatus will be described with reference to FIGS. Reference numeral 101 denotes an illumination system unit that has an exposure light source, and exposes the exposure light generated from the exposure light source to the reticle for shaping. Reference numeral 102 denotes a reticle stage, on which a reticle which is an exposure pattern master is mounted. At the time of exposure scanning, reticle stage 102 moves the reticle at a speed obtained by multiplying the scanning speed of the wafer by the reduced exposure magnification ratio. Reference numeral 103 denotes a reduction projection lens, which guides exposure light so as to reduce and project a reticle pattern onto a wafer (substrate).

  A wafer stage 104 mounts a substrate (wafer), moves the substrate to an exposure position, and moves the wafer in the scanning direction at a predetermined scanning speed during exposure scanning. An exposure apparatus main body 105 supports the reticle stage 102, the reduction projection lens 103, and the wafer stage 104. Reference numeral 106 denotes an alignment scope, which is a microscope for measuring an alignment mark (not shown) on the wafer and an alignment reference mark (113 in FIG. 9) on the stage. The measurement result is used for in-wafer alignment and alignment between the reticle and the wafer.

  FIG. 9 shows details of the wafer stage 104. In FIG. 9, reference numeral 107 denotes a slider, which includes a fine movement stage that finely adjusts the position of the wafer in the optical axis direction and tilt direction of the reduction exposure system and the rotation direction around the optical axis. A wafer chuck 108 supports and fixes the wafer to the slider 107 by, for example, electrostatic adsorption. Reference numeral 109 denotes a wafer, which is a single crystal silicon substrate having a surface coated with a resist in order to project and transfer a reticle pattern drawn on the reticle substrate through a reduction exposure system. Reference numeral 110 denotes an X-bar mirror, which is a target for measuring the position of the slider 107 in the X direction with a laser interferometer. Reference numeral 111 denotes a Y bar mirror, which is also a target for measuring the position in the Y direction.

  An illuminance sensor 112 is provided on the upper surface of the slider 107 and measures the illuminance of exposure light before exposure. This measurement result is used for exposure amount correction. A stage reference mark 113 is provided on the upper surface of the slider 107, and a target for stage alignment measurement is provided. Reference numeral 114 denotes an X linear motor, which moves and drives the slider 107 in the X direction. An X guide 115 guides the movement of the slider 107 in the X-axis direction. Reference numeral 116 denotes a Y guide, which moves and guides the X guide 115 and the slider 107 in the Y direction. A stage surface plate 117 guides the slider 107 on a plane. Reference numerals 118 and 119 denote Y linear motors that move and drive the slider 107 in the Y direction.

In the above configuration, at the time of exposure processing, first, when a wafer to be processed is loaded into the apparatus, the wafer is chucked by the wafer chuck 108. Then, alignment is performed using the alignment scope 106 to position the wafer, and then a reticle pattern is projected. Examples of documents disclosing general configurations of the wafer chuck mechanism using the electrostatic chuck and the wafer transport mechanism using the electrostatic chuck include Patent Document 1 and Patent Document 2.
JP 2002-345273 A JP-A-11-168132

  As described above, conventionally, wafer transfer, alignment measurement, and exposure operation are performed on the same stage (wafer stage 104, slider 107). For this reason, since each operation time is added directly, the processing time per wafer finally increases. Therefore, in order to increase the throughput in the conventional apparatus, it is necessary to increase the speed of at least one of the wafer carry-in operation, the alignment operation, and the exposure operation. However, for example, if the positioning operation is speeded up, the positioning accuracy and the like may be deteriorated. Further, if the wafer delivery time is to be shortened, it is necessary to enable the wafer transfer system unit to be driven with a large output, which causes problems such as an increase in heat generation and an increase in the size of the drive source.

  The present invention has been made in view of the above problems, and an object of the present invention is to enable the alignment processing of a wafer to be processed next during the wafer exposure operation and improve the throughput of the apparatus.

In order to achieve the above object, an exposure apparatus according to the present invention comprises the following arrangement. That is,
A first stage for performing an exposure process;
A second stage for performing alignment measurement, operable independently of the first stage;
A holding unit that is detachable from the first and second stages, has a reference mark for alignment measurement, and holds a substrate;
The holding unit mounted on the second stage includes transport means for moving and mounting the holding unit mounted on the second stage to the first stage while keeping the substrate held and fixed.

Moreover, the control method of the stage apparatus according to the present invention for achieving the above object is as follows:
A first stage for performing an exposure process, a second stage for performing alignment measurement, which can be operated independently of the first stage, and detachable from the first and second stages. A method for controlling a stage apparatus comprising a holding unit having a reference mark for measurement and holding a substrate, and a transfer mechanism for transferring the holding unit between the first stage and the second stage,
An execution step of executing in parallel an exposure process using the first stage and an alignment measurement process using the second stage;
After the exposure process and the alignment measurement process are completed, a transporting process is performed to disengage the holding unit attached to the first stage and attach the holding unit attached to the second stage to the first stage. ,
In the transfer step, the holding unit mounted on the second stage holds the substrate in a fixed state.

  With the above configuration, it becomes possible to execute the alignment process of the wafer to be processed next during the wafer exposure operation, and the throughput of the apparatus can be improved.

  In the following embodiments, an exposure apparatus is provided with two areas, an exposure area and an alignment area, and an exposure stage and an alignment stage are provided in each area. The driving of each stage is controlled independently, and the exposure operation and the alignment operation can be executed in parallel. Then, a wafer holding member (for example, an electrostatic chuck top plate) of the alignment stage that has been aligned is transferred onto the exposure stage while maintaining the holding state, so that the alignment on the exposure stage side (wafer alignment is complete). The process can be started from a state in which the relative position between the mark and the stage reference mark is determined.

  The wafer holding member is transported from the alignment stage to the exposure stage by, for example, providing a mechanism for exchanging the wafer holding member on the alignment stage and the wafer holding member on the exposure stage. For example, a chuck transfer robot for transferring a wafer chuck holding a wafer is provided between the stages for transferring the wafer holding member. When an electrostatic chuck is used as the wafer chuck, the wafer holding member is transferred in a state where power is supplied from the chuck transfer robot to the electrostatic chuck. Transport the chuck. In this way, the exposure operation and the alignment operation can be continuously executed in parallel, thereby improving the throughput of the apparatus.

  Hereinafter, the details of the embodiment of the present invention will be described with reference to FIGS.

  FIG. 1 is a view showing the schematic arrangement of the exposure apparatus according to the present embodiment. In FIG. 1, an illumination system unit 1, a reticle stage 2, and a reduction projection lens 3 are the same as the illumination system unit 101, the reticle stage 102, and the reduction projection lens 103 described in FIG. Reference numeral 4 denotes an exposure stage on which a substrate (wafer) is mounted, and the wafer is moved to the exposure position of the reduction projection lens 3 for exposure processing. Reference numeral 8 denotes an X interferometer, which measures the position of the exposure stage 4 in the X-axis direction. Reference numeral 10 denotes a Y interferometer that measures the position of the exposure stage 4 in the Y-axis direction. The above constitutes the exposure area.

  In FIG. 1, reference numeral 6 denotes an alignment scope, which is a microscope that measures alignment marks (not shown) on the wafer and alignment reference marks (31A and 31B in FIG. 2) on the alignment stage 7 and performs alignment measurement. is there. Reference numeral 7 denotes an alignment stage on which a wafer is mounted and the wafer and the alignment reference mark are moved and positioned at the measurement position of the alignment scope 6 for alignment measurement processing. Reference numeral 9 denotes an X interferometer, which measures the position of the alignment stage 7 in the X-axis direction. Reference numeral 11 denotes a Y interferometer, which measures the position of the alignment stage 7 in the Y-axis direction. The above constitutes the alignment area.

  A chuck transfer robot 12 is provided between the exposure stage 4 in the exposure area and the alignment stage 7 in the alignment area, and performs a rotating up and down operation for exchanging wafers on both stages. The chuck transport robot 12 transports a holding member (electrostatic chuck top plate) that holds the wafer in exchanging the wafer between both stages. Reference numeral 5 denotes an exposure apparatus main body, which supports the above-described components.

  FIG. 2 is a view showing the configuration of the exposure stage 4 and the alignment stage 7. The configuration shown in FIG. 2 is generally a configuration in which two wafer stages described with reference to FIG. 9 are arranged with a chuck transfer robot interposed therebetween.

  In FIG. 2, reference numerals 13A and 13B denote electrostatic chuck top plates mounted on the exposure stage 4 and the alignment stage 7, respectively, for positioning and holding the wafer 14A and the wafer 14B by electrostatic attraction. Each of 14A and 14B is a wafer, which is a single crystal silicon substrate having a surface coated with a resist in order to project and transfer a reticle pattern drawn on the reticle substrate through a reduction exposure system. Reference numeral 15 denotes a slider provided on the exposure stage 4, which is floated with respect to the stage surface plate 4 </ b> A of the exposure stage 4 by an air bearing (not shown) provided on the bottom surface thereof, that is, can be moved without contact. It is supported. Reference numeral 16 denotes a slider of the alignment stage 7, which is supported by an air bearing (not shown) provided on the bottom surface thereof so as to float with respect to the stage surface plate 7A of the alignment stage 7, that is, movably in a non-contact manner. Yes. The sliders 15 and 16 hold the electrostatic chuck top plates 13A and 13B by an electrostatic chuck mechanism, respectively, and the wafers 14A and 14B electrostatically attracted to the electrostatic chuck top plates 13A and 13B are placed at the control positions of the respective stages. Move.

  Reference numeral 17 denotes an X linear motor, which moves the slider 15 in the X direction. Reference numerals 19 and 20 denote Y linear motors, which move the slider 15 in the Y direction. An X linear motor 18 moves the slider 16 in the Y direction. Reference numerals 21 and 22 denote Y linear motors that move the slider 16 in the Y direction. Reference numerals 31A and B denote stage reference marks, which are provided with targets for alignment measurement. Reference numerals 32A and B denote illuminance sensors, which measure the illuminance of the exposure light. Although the X bar mirror and the Y bar mirror shown in FIG. 9 are provided on the electrostatic chuck top plates 13A and 13B, they are not shown in FIG.

  FIG. 3 is a diagram for explaining the control system of the chuck transport robot according to the present embodiment. In FIG. 3, reference numeral 23 denotes a chuck replacement driver that drives the chuck transport robot 12. An advertisement chuck power supply unit 24 supplies power to the electrostatic chuck mechanisms provided on the electrostatic chuck top plate 13A and the electrostatic chuck top plate 13B through the chuck transport robot 12, and electrostatically attracts the wafer. Reference numeral 25 denotes a control unit that controls driving and power supply timing for wafer replacement operation with respect to the chuck replacement driver 23 and the electrostatic chuck power supply unit 24. A mechanism for supplying power via the chuck transfer robot 12 will be described later with reference to FIG.

  In the above configuration, the exposure operation on the exposure stage 4 and the alignment measurement operation on the alignment stage 7 are performed in parallel, and when each operation is completed, an operation (swap operation) for exchanging the wafers 14A and 14B is performed. Be started. Hereinafter, the swap operation of this embodiment will be described in detail with reference to FIGS. 4A and 4B are views for explaining a wafer swap operation according to the present embodiment. FIG. 5 is a diagram illustrating a state where the swap operation illustrated in FIG. 4A is viewed from the side of the stage. FIG. 6 is a diagram for explaining a mechanism for supplying power to the electrostatic chuck via the chuck transport robot 12. FIG. 7 is a flowchart showing a swap operation NO control procedure by the controller 25.

  First, at the time of executing and ending the exposure operation on the exposure stage 4 and the alignment operation on the alignment stage 7, the chuck transport robot 12 is moved to the position shown in FIG. 4A (a) (FIGS. 3 and 5A). Retracted to the state indicated by the solid line of the chuck transport robot 12). When the exposure process and the alignment measurement process are completed, the chuck transport robot rotates by a predetermined angle (90 degrees in this embodiment) as shown by the broken lines in FIGS. 3 and 5A (steps S11 and S12). Then, the sliders 15 and 16 respectively move from the position shown in FIG. 5A toward the chuck transport robot 12 (in the direction of the arrow in FIG. 5B) (step S13), and are once positioned for replacement. This state is shown in FIG. 4A (b).

  In the state shown in FIG. 4A (b) and FIG. 5 (b), it is possible to supply power to the electrostatic chuck top plates 13A and 13B via the chuck transport robot 12. This mechanism will be described in detail with reference to FIG. FIG. 6 is a cross-sectional view showing the details of the state in which the electrostatic chuck top plate 13A and the chuck transport robot 12 are coupled. As shown in FIGS. 4A (b) and 5 (b), the robot hand holds the electrostatic chuck. The state inserted in the top plate is shown. In this state, the electrostatic chuck side power supply terminal 13C provided on the electrostatic chuck top plate 13B is connected to the robot hand side power supply terminal 12A provided at the tip of the robot hand 12D. As a result, the potential supplied by the electrostatic chuck power supply cable 12C provided on the chuck transport robot 12 side is supplied via the robot hand side power supply terminal 12A and the electrostatic chuck side power supply terminal 13C. Then, power is supplied to the electrostatic chuck electrode 13E through the electrostatic chuck power supply cable 13D. As a result, an electrostatic potential is excited in the electrostatic chuck electrode 13E, and a reverse potential is generated on the wafer 14B side, whereby the wafer 14B is held electrostatically.

  As shown in FIG. 6, the electrostatic chuck top plate 13B is provided with another electrostatic chuck-side power supply terminal 13C '. The electrostatic chuck-side power supply terminal 13C ′ is connected to a power supply unit (not shown) provided on the slider in a state where the electrostatic chuck top plate 13B is held by the slider, and is connected to the electrostatic chuck electrode 13E via the slider. Power supply for electrostatic attraction is performed. In the present embodiment, in the state of FIG. 4A (b), the power supply path to the electrostatic chuck is switched from the electrostatic chuck side power supply terminal 13C ′ to the electrostatic chuck side power supply terminal 13C (step S14), whereby the power supply source is changed. The slider 16 is switched to the chuck transport robot 12.

  Next, as shown in FIG. 5C, the electrostatic chuck top plates 13 </ b> A and 13 </ b> B are moved to the sliders 15 and 16 by moving the lift rotation shaft 12 </ b> B of the chuck transport robot 12 upward (in the direction of the arrow in the drawing). To leave. At this time, the electrostatic chuck top plates 13A and 13B perform the separation operation by releasing the chucked state by the electrostatic chuck mechanism (not shown) provided between the sliders 15 and 16 (steps S15 and S16). .

  As described above, at the end of exposure and at the end of alignment measurement, a potential necessary for electrostatic chucking of the wafer is supplied from the sliders 15 and 16 to the electrostatic chuck top plates 13A and 13B. After the detachment operation, as described with reference to FIG. 6, a potential necessary for driving the electrostatic chuck is supplied from the electrostatic chuck power supply cable 12C, and the electrostatic chucking state of the wafer is maintained. This power supply timing is controlled by the control unit 25, and a potential is supplied via the electrostatic chuck power supply unit 24 in accordance with a control command from the control unit 25. In the same state as described above, the electrostatic chucking state of the electrostatic chuck top plate 13A on the exposure stage 4 side and the wafer 14A is also maintained.

  When the electrostatic chuck top plates 13A and 13B are raised as shown in FIG. 5C, the chuck transport robot 12 is moved to a predetermined angle (180 in this embodiment) as shown in FIG. 4A (c). And is positioned at the position of FIG. 4B (a) (step S17). Then, the lift rotary shaft 12B is moved downward (lowering the Z position), and the electrostatic chuck top plates 13B and A are chuck clamped by the sliders 15 and 16 (steps S18 and S19). That is, by supplying power to an electrostatic chuck mechanism (not shown) provided between the electrostatic chuck top plates 13A and 13B and the sliders 15 and 16, the electrostatic chuck top plates 13B and 13A are respectively moved to the sliders 15 and 16 respectively. The chuck is clamped. Then, by switching the power supply path to the electrostatic chuck from the electrostatic chuck side power supply terminal 13C to the electrostatic chuck side power supply terminal 13C ', the power supply source is switched from the chuck transport robot 12 to the slider 15 (step S20).

  Thereafter, the sliders 15 and 16 are retracted in the arrow direction shown in FIG. 4B (b), and the chuck transport robot 12 is rotated and retracted in the arrow direction as shown in FIG. 4B (c) (steps S21 and S22). Thus, a series of exchanging operations of the wafers 14A and 14B and the electrostatic chuck top plates 13A and 13B is completed. By repeating the above operation, it is possible to continuously transfer the wafer between the exposure stage 4 and the alignment stage 7. The exposed wafer held by the electrostatic chuck top plate conveyed to the alignment stage 7 is unloaded, and then a new wafer is loaded onto the electrostatic chuck top plate.

  As described above, according to the above embodiment, the exposure stage and the alignment stage operate independently, and the exposure process and the alignment measurement process are executed respectively. Then, the electrostatic chuck top plate holding the wafer is exchanged between the exposure stage and the alignment stage. Since the electrostatic chuck top plate is provided with the stage reference mark, the relative position between the wafer alignment mark and the stage reference mark is maintained, and the alignment measurement result on the alignment stage can be used as it is. Therefore, since the exposure process and the alignment measurement for the next wafer can proceed simultaneously, the throughput of the exposure apparatus is remarkably improved.

Although not described in detail in the above embodiment, the electrical connection of the illuminance sensor provided on the electrostatic chuck top plate is also achieved while being held by the slider.
In the above embodiment, the electrostatic chuck top plate is used as the wafer holding member, but a vacuum chuck may be used. However, in this case, a vacuum line is provided in the robot hand, and the exhaust path to the chuck top plate is switched between the stage and the robot hand.
Further, the switching timing of power supply to the electrostatic chuck in steps S14 and S20 may be switched through a state where power is supplied from both electrostatic chuck-side power supply terminals 13C and 13C ′.

It is a figure which shows schematic structure of the exposure apparatus by embodiment. It is a figure which shows the structure of the exposure stage 4 and the alignment stage 7 by embodiment. It is a figure explaining the control system of the chuck conveyance robot by an embodiment. It is a figure explaining the swap operation | movement of the wafer by embodiment. It is a figure explaining the swap operation | movement of the wafer by embodiment. It is a figure which shows a mode that the swap operation | movement shown to FIG. 4A was seen from the stage side surface. It is a figure explaining the mechanism of the electric power feeding to an electrostatic chuck via the chuck conveyance robot. FIG. 7 is a flowchart showing a swap operation NO control procedure by the controller 25. It is a figure which shows schematic structure of a general exposure apparatus. It is a figure which shows the structure of a general wafer stage.

Claims (7)

A first stage for performing an exposure process;
A second stage for performing alignment measurement, operable independently of the first stage;
A holding unit that is detachable from the first and second stages and holds a substrate;
An exposure apparatus comprising: a transport unit configured to move and mount the holding unit mounted on the second stage to the first stage while maintaining a state where the substrate is held and fixed.   2. The exposure apparatus according to claim 1, wherein a reference mark for alignment measurement is provided on the holding unit.   The exposure apparatus according to claim 1, wherein the holding unit holds and fixes the substrate by an electrostatic chuck.   The conveying means has a power feeding end for driving the electrostatic chuck, and power feeding from the power feeding end to the electrostatic chuck of the holding unit can be performed with the conveying means holding the holding unit. The exposure apparatus according to claim 3.   The exposure apparatus according to claim 1, wherein the holding unit is mounted on the first stage and the second stage by an electrostatic chuck.   6. The exposure apparatus according to claim 1, wherein the transport unit replaces holding units mounted on the first stage and the second stage, respectively. A first stage for performing an exposure process, a second stage for performing alignment measurement, which can be operated independently of the first stage, and detachable from the first and second stages. A method for controlling a stage apparatus comprising a holding unit having a reference mark for measurement and holding a substrate, and a transfer mechanism for transferring the holding unit between the first stage and the second stage,
An execution step of executing in parallel an exposure process using the first stage and an alignment measurement process using the second stage;
After the exposure process and the alignment measurement process are completed, a transporting process is performed to disengage the holding unit attached to the first stage and attach the holding unit attached to the second stage to the first stage. ,
In the transporting process, the holding unit mounted on the second stage holds the substrate and keeps the fixed state.

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