Measurement method, use method, determination method, measurement device, spatial light modulator, and program

Abstract

In this spatial light modulator, a measurement value G*Vout reflecting the electrical resistance value R1 of a movable ribbon (61) is acquired. The measurement value G*Vout is converted into a deflection amount ε of the movable ribbon (61). That is, the deflection amount ε of the movable ribbon (61) is measured not by an optical means but by an electrical means. As a result, the deflection amount ε of the movable ribbon (61) can be accurately measured, and the unit required for measurement can be reduced in size as compared with the case where an optical means is used.

Description

Measurement method, method of use, determination method, measurement device, spatial light modulator, and program

[0001] The present invention relates to a technique for measuring the amount of deflection of a plurality of movable ribbons in a spatial light modulator having movable ribbons that can be displaced by applying a voltage.

[0002] Conventionally, a diffraction grating type spatial light modulator has been used in manufacturing devices such as exposure devices, drawing devices, and CTP (Computer to Plate) devices that irradiate an object with light. The spatial light modulator has multiple movable ribbons that can be displaced by applying a voltage. The spatial light modulator controls the voltage value applied to each movable ribbon, changing the state of diffracted light reflected on the surface of the movable ribbon, thereby modulating the light into a predetermined pattern.

[0003] A conventional device equipped with a diffraction grating type spatial light modulator is described in, for example, Japanese Patent Application Laid-Open No. 2003-222999.

[0004] Patent No. 5004279 specification

[0005] In a spatial light modulator, the position of the reflective surface of the movable ribbons must be precisely controlled. However, the movable ribbons may bend in the initial state when no voltage is applied due to manufacturing errors or the influence of gravity. This bending may cause slight variations in the optical characteristics of the multiple movable ribbons.

[0006] In conventional spatial light modulators, the intensity of reflected light when a voltage is applied to each movable ribbon is measured to obtain the variation in optical properties caused by the initial bending of each movable ribbon, and the voltage applied to each movable ribbon is then adjusted according to the obtained variation in optical properties.

[0007] However, conventional optical measurements have difficulty in accurately measuring the deflection of each movable ribbon. Furthermore, conventional methods require a unit for measuring the intensity of reflected light, and miniaturizing this unit has been an issue.

[0008] The present invention has been made in consideration of the above circumstances, and aims to provide a technology that can accurately measure the amount of deflection of a movable ribbon of a spatial light modulator and that can make the unit required for measurement smaller than conventional units.

[0009] In order to solve the above problem, the first invention of the present application is a measurement method for measuring the amount of deflection of movable ribbons in a spatial light modulator having multiple movable ribbons that can be displaced by applying a voltage, and includes a measurement step of obtaining a measurement value that reflects the electrical resistance value of the movable ribbons, and a conversion step of converting the measurement value obtained by the measurement step into the amount of deflection of the movable ribbons.

[0010] A second aspect of the present invention is the measurement method of the first aspect, wherein the measurement step applies a measurement voltage to a bridge circuit including the movable ribbon, and measures a voltage value output from the bridge circuit.

[0011] The third invention of the present application is a measurement method according to the first and second inventions, wherein the measurement voltage applied to the movable ribbon in the measurement process is smaller than the driving voltage applied to the movable ribbon when the spatial light modulator is in use.

[0012] A fourth invention of the present application is a measurement method according to any one of the first to third inventions, wherein in the conversion process, the measurement value is converted into the amount of deflection based on correspondence data indicating the correspondence between the measurement value and the amount of deflection.

[0013] The fifth invention of the present application is a method of using the spatial light modulator using the measurement method of any one of the first to fourth inventions, in which the driving voltage applied to the movable ribbon is corrected based on the amount of deflection obtained by the conversion process.

[0014] The sixth invention of the present application is a determination method for determining whether or not the spatial light modulator can be used by utilizing the measurement method of any one of the first to fourth inventions, in which if the amount of deflection obtained by the conversion process is less than a predetermined threshold, the spatial light modulator is determined to be usable, and if the amount of deflection is equal to or greater than the threshold, the spatial light modulator is determined to be unusable.

[0015] The seventh invention of the present application is a measurement device that measures the amount of deflection of movable ribbons in a spatial light modulator having multiple movable ribbons that can be displaced by applying a voltage, and includes a measurement circuit that acquires a measurement value that reflects the electrical resistance value of the movable ribbons, and a conversion processing unit that converts the measurement value obtained by the measurement circuit into the amount of deflection of the movable ribbons.

[0016] An eighth aspect of the present invention is the measurement device of the seventh aspect, wherein the measurement circuit has a bridge circuit including the movable ribbon.

[0017] A ninth invention of the present application is a measuring device according to the seventh or eighth invention, further comprising a memory unit in which correspondence data indicating the correspondence between the measurement value and the amount of deflection is stored, and the conversion processing unit converts the measurement value into the amount of deflection based on the correspondence data.

[0018] The tenth invention of the present application is a spatial light modulator equipped with a measurement device of any one of the seventh to ninth inventions, and is equipped with a voltage application circuit that applies a voltage to the movable ribbon, and a control unit that controls the voltage application circuit, and the control unit corrects the drive voltage that the voltage application circuit applies to the movable ribbon based on the amount of deflection obtained by the conversion processing unit.

[0019] An eleventh invention of the present application is a spatial light modulator equipped with a measurement device of any one of the seventh to ninth inventions, and is equipped with a control unit that determines that the spatial light modulator is usable when the amount of deflection obtained by the conversion processing unit is less than a predetermined threshold, and determines that the spatial light modulator is unusable when the amount of deflection is equal to or greater than the threshold.

[0020] The twelfth invention of the present application is a program for measuring the amount of deflection of movable ribbons in a spatial light modulator having multiple movable ribbons that can be displaced by applying a voltage, which causes a computer to execute a measurement process for obtaining a measurement value that reflects the electrical resistance value of the movable ribbons, and a conversion process for converting the measurement value obtained by the measurement process into the amount of deflection of the movable ribbons.

[0021] According to the first to twelfth aspects of the present invention, the amount of deflection of the movable ribbon is measured electrically rather than optically, which allows the amount of deflection of the movable ribbon to be measured with high accuracy and also makes it possible to make the unit required for measurement more compact than when optical means are used.

[0022] In particular, according to the second and eighth aspects of the present invention, a measurement value that reflects the resistance value of the movable ribbon can be obtained using a relatively simple measurement circuit.

[0023] In particular, according to the third aspect of the present invention, it is possible to prevent the movable ribbon from being displaced by the measurement voltage, and therefore it is possible to measure the amount of deflection of the movable ribbon in a state close to the initial state in which no voltage is applied to the movable ribbon.

[0024] In particular, according to the fourth and ninth aspects of the present invention, the amount of deflection can be determined with less error than when the amount of deflection is calculated by substituting the measured value into a predetermined mathematical formula.

[0025] In particular, according to the fifth and tenth aspects of the present invention, it is possible to suppress errors due to bending of the movable ribbons and to modulate light with high precision by the spatial light modulator.

[0026] In particular, according to the sixth and eleventh aspects of the present invention, when the amount of bending of the movable ribbon is too large, the use of the spatial light modulator can be prohibited.

[0027] FIG. 1 is a schematic perspective view of an exposure apparatus; FIG. 2 is a control block diagram of the exposure apparatus; FIG. 3 is a top view of a spatial light modulator; FIG. 4 is a side view of the spatial light modulator; FIG. 5 is a circuit diagram of an electrical circuit when the spatial light modulator is in use; FIG. 6 is a circuit diagram of an electrical circuit when measuring the amount of deflection of a movable ribbon; FIG. 7 is a flowchart showing the flow of operations when measuring the amount of deflection of a movable ribbon; and FIG. 8 is a diagram showing an example of correspondence data.

[0028] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0029] 1. Configuration of the Exposure Apparatus Fig. 1 is a schematic perspective view of an exposure apparatus 1 equipped with a spatial light modulator 60 according to one embodiment of the present invention. This exposure apparatus 1 is an apparatus that irradiates modulated light onto the upper surface of a substrate 9, such as a semiconductor wafer, on which a photosensitive material is applied, to expose a pattern onto the upper surface of the substrate 9. As shown in Fig. 1, the exposure apparatus 1 includes a base 10, a stage 20, a moving mechanism 30, an exposure unit 40, and a control unit 50.

[0030] The base 10 is a support platform that supports the moving mechanism 30 and the exposure unit 40. The base 10 has a flat plate-like outer shape that extends in the main scanning direction and the sub-scanning direction. The base 10 is fixed to the floor of a factory.

[0031] The stage 20 is a flat plate that holds the substrate 9. The stage 20 has a flat upper surface. The substrate 9 is placed in a substantially horizontal position on the upper surface of the stage 20. The stage 20 may have chuck pins that fix the substrate 9 and a plurality of suction holes that suction the substrate 9.

[0032] The movement mechanism 30 is a mechanism that moves the stage 20 relative to the base 10. The movement mechanism 30 includes a main scanning mechanism 31 and a sub-scanning mechanism 32. The main scanning mechanism 31 moves the stage 20 in a main scanning direction along a horizontal plane. The sub-scanning mechanism 32 moves the stage 20 in a sub-scanning direction that is a direction along the horizontal plane and perpendicular to the main scanning direction. When the stage 20 moves in the main scanning direction and the sub-scanning direction, the substrate 9 is also transported in the main scanning direction and the sub-scanning direction together with the stage 20.

[0033] For example, a mechanism that converts the rotational motion of a motor into linear motion using a ball screw, or a mechanism that uses a linear motor, is used for the main scanning mechanism 31 and the sub-scanning mechanism 32. Furthermore, the movement mechanism 30 may include an elevation mechanism that moves the stage 20 in the vertical direction, or a rotation mechanism that rotates the stage 20 around an axis that extends in the vertical direction.

[0034] The exposure unit 40 is a unit that exposes the substrate 9 held by the stage 20. The exposure unit 40 is located above the stage 20. As shown in Figure 1, the exposure unit 40 is fixed to a frame 44 with a bridge structure that is erected on the base 10. In this embodiment, two exposure units 40 are fixed to the frame 44 while aligned in the sub-scanning direction.

[0035] 1, each of the two exposure units 40 has a head 41, an illumination optical system 42, and a laser oscillator 43. The laser oscillator 43 emits pulsed light in accordance with a drive signal supplied from a control unit 50. The pulsed light emitted from the laser oscillator 43 is introduced into the head 41 via the illumination optical system 42. A spatial light modulator 60 is provided inside the head 41. The pulsed light introduced into the head 41 is modulated into a predetermined pattern by the spatial light modulator 60 and irradiated onto the upper surface of the substrate 9. This exposes the photosensitive material on the upper surface of the substrate 9.

[0036] When the exposure apparatus 1 is in operation, the transport of the substrate 9 by the movement mechanism 30 and the exposure by the head 41 are repeatedly performed. Specifically, the exposure apparatus 1 exposes a band-shaped area (swath) extending in the main scanning direction on the top surface of the substrate 9 by irradiating pulsed light from the head 41 while transporting the stage 20 in the main scanning direction by the main scanning mechanism 31. The exposure apparatus 1 then moves the stage 20 in the sub-scanning direction by one swath using the sub-scanning mechanism 32, and performs exposure in the main scanning direction again. In this way, the exposure apparatus 1 exposes a pattern over the entire top surface of the substrate 9 by repeating exposure in the main scanning direction and movement of the stage 20 in the sub-scanning direction.

[0037] The control unit 50 is a unit for controlling the operation of each part of the exposure apparatus 1. Figure 2 is a control block diagram of the exposure apparatus 1. As conceptually shown in Figure 2, the control unit 50 is made up of a computer having a processor 51 such as a CPU, a memory 52 such as RAM, and a storage unit 53 such as a hard disk drive. The storage unit 53 stores an exposure program P1 for causing the exposure apparatus 1 to execute an exposure process, and a measurement program P2 for measuring the deflection of the spatial light modulator 60, which will be described later. The exposure program P1 and the measurement program P2 may be stored on a storage medium such as an optical disk.

[0038] 2, the control unit 50 is electrically connected to the main scanning mechanism 31, the sub-scanning mechanism 32, the laser oscillator 43, a ribbon power supply 711 (described later), a common power supply 712, a first switch 73, a second switch 74, and an amplifier 725. The control unit 50 controls the above-mentioned components in accordance with an exposure program P1 to perform an exposure process on the substrate 9. The control unit 50 also controls the above-mentioned components in accordance with a measurement program P2 to perform deflection measurement of the movable ribbon 61 (described later).

[0039] 2. Configuration of Spatial Light Modulator Next, the configuration of the spatial light modulator 60 used in the exposure unit 40 will be described. Fig. 3 is a top view of the spatial light modulator 60. Fig. 4 is a side view of the spatial light modulator 60. This spatial light modulator 60 is a so-called diffraction grating type light modulator that modulates the ON / OFF of reflected light by changing diffracted light at each position on the reflective surface. For example, a GLV (Grating Light Valve) (registered trademark) is used as the spatial light modulator 60.

[0040] As shown in FIGS. 3 and 4, the spatial light modulator 60 has a plurality of movable ribbons 61 , a plurality of fixed ribbons 62 , and a common electrode 63 .

[0041] The multiple movable ribbons 61 are arranged at regular intervals in a predetermined direction (hereinafter referred to as the "first direction"). Each movable ribbon 61 is a metal piece extending in a direction perpendicular to the first direction (hereinafter referred to as the "second direction"). The upper surface of the movable ribbon 61 is a mirror surface capable of reflecting light. Both ends of the movable ribbon 61 in the second direction are fixed to the ribbon mounting surface 64 of the spatial light modulator 60. The center of the movable ribbon 61 in the second direction is located above and spaced from the ribbon mounting surface 64, and is capable of bending in the vertical direction.

[0042] The multiple fixed ribbons 62 are arranged between adjacent movable ribbons 61 in the first direction. That is, the movable ribbons 61 and the fixed ribbons 62 are arranged alternately along the first direction. Each fixed ribbon 62 is a metal piece extending in the second direction. The upper surface of the fixed ribbon 62 is a mirror surface that can reflect light. The entire second direction of each fixed ribbon 62 is fixed to the ribbon mounting surface 64 of the spatial light modulator 60. Therefore, the fixed ribbons 62 do not bend in the vertical direction.

[0043] The common electrode 63 is a single metal piece disposed below the plurality of movable ribbons 61 and the plurality of fixed ribbons 62. The common electrode 63 extends in the first and second directions along the ribbon mounting surface 64. The lower surfaces of the plurality of movable ribbons 61 and the upper surface of the common electrode 63 face each other with a gap in the vertical direction.

[0044] The spatial light modulator 60 also has an electric circuit 70 connected to the movable ribbons 61 and the common electrode 63. Figures 5 and 6 are circuit diagrams of the electric circuit 70. As shown in Figures 5 and 6, the electric circuit 70 includes a voltage application circuit 71, a measurement circuit 72, a first switch 73, and a second switch 74.

[0045] The voltage application circuit 71 is a circuit for applying a voltage to the multiple movable ribbons 61 and the common electrode 63. As shown in Figures 5 and 6, the voltage application circuit 71 has a ribbon power supply 711 and a common power supply 712. The anode of the ribbon power supply 711 is connected to one end of the movable ribbon 61 via a conductor. The other end of the movable ribbon 61 is connected to a first switch 73. The cathode of the ribbon power supply 711 is grounded via a conductor. The anode of the common power supply 712 is connected to one end of the common electrode 63 via a conductor. The other end of the common electrode 63 is open. The cathode of the common power supply 712 is grounded via a conductor.

[0046] 5 and 6 show one movable ribbon 61 and one ribbon power supply 711 that supplies voltage to the movable ribbon 61, but the voltage application circuit 71 has a ribbon power supply 711 for each movable ribbon 61. The multiple ribbon power supplies 711 are connected in parallel, and one ribbon power supply 711 is connected to one movable ribbon 61.

[0047] The ribbon power supply 711 is a variable power supply that can change the voltage value it outputs. The ribbon power supply 711 changes the voltage applied to the movable ribbons 61 in accordance with a control signal input from the control unit 50. In this embodiment, the common power supply 712 is also a variable power supply that can change the voltage it outputs. The common power supply 712 changes the voltage applied to the common electrode 63 in accordance with a control signal input from the control unit 50. However, the common power supply 712 may also be a fixed power supply that outputs only a constant voltage value.

[0048] The first switch 73 is interposed between the movable ribbon 61 and a second resistor 722 (described later) according to a command from the control unit 50. The first switch 73 switches between a state in which the movable ribbon 61 is connected to the open end 731 (the state in FIG. 5 ) and a state in which the movable ribbon 61 is connected to the second resistor 722 (the state in FIG. 6 ).

[0049] The second switch 74 is interposed between a connection point 75 between the ribbon power supply 711 and the movable ribbon 61 and a third resistor 723, which will be described later. In accordance with a command from the control unit 50, the second switch 74 switches between a state in which the connection point 75 is connected to the open end 741 (the state in FIG. 5 ) and a state in which the connection point 75 is connected to the third resistor 723 (the state in FIG. 6 ).

[0050] When the spatial light modulator 60 is in use, as shown in FIG. 5 , the first switch 73 is connected to the open end 731, and the second switch 74 is also connected to the open end 741. A predetermined voltage (hereinafter referred to as the "common voltage") is applied from the common power supply 712 to the common electrode 63, and a driving voltage (hereinafter referred to as the "driving voltage") is applied from the ribbon power supply 711 to the movable ribbon 61. Then, due to the potential difference between the common voltage and the driving voltage, an electrostatic attraction force is generated between the common electrode 63 and the movable ribbon 61. As a result, the center portion of the movable ribbon 61 in the second direction bends downward, as indicated by the dashed arrow in FIG. 4 . As a result, the height of the upper surface of the movable ribbon 61 changes depending on the magnitude of the driving voltage.

[0051] Furthermore, when the spatial light modulator 60 is in use, line light shaped like a straight line extending in the first direction is irradiated from the illumination optical system 42 toward the upper surfaces of the plurality of movable ribbons 61 and the plurality of fixed ribbons 62. At this time, the intensities of the specularly reflected light and diffracted light vary depending on the difference in height between adjacent movable ribbons 61 and fixed ribbons 62. For this reason, by adjusting the drive voltage for each movable ribbon 61 and selectively using the specularly reflected light and diffracted light, it is possible to switch the output light at each position in the first direction between ON and OFF.

[0052] <3. Measuring Deflection of Movable Ribbons> In such a spatial light modulator 60, the vertical position of the movable ribbons 61 must be precisely controlled. However, due to manufacturing errors, the influence of gravity, and the like, the movable ribbons 61 may be slightly deflected in the vertical direction in the initial state when no voltage is applied. For this reason, when using the spatial light modulator 60, the operation of the movable ribbons 61 must be controlled taking into account the amount of deflection of the movable ribbons 61 in this initial state.

[0053] Therefore, the electrical circuit 70 of this spatial light modulator 60 includes a measurement circuit 72 for measuring the amount of deflection ε in the vertical direction of the movable ribbons 61 in the initial state. The measurement circuit 72 is electrically connected to the control unit 50. In this embodiment, the voltage application circuit 71, the measurement circuit 72, and the control unit 50 constitute a measurement device that measures the amount of deflection ε of the movable ribbons 61.

[0054] 5 and 6 show one movable ribbon 61 and one measurement circuit 72 that measures the amount of deflection ε of the movable ribbon 61, but the electrical circuit 70 has a measurement circuit 72 for each movable ribbon 61. In other words, one measurement circuit 72 is connected to one movable ribbon 61.

[0055] 5 and 6, the measurement circuit 72 has a bridge circuit configured with the movable ribbon 61 as a first resistor 721, the first resistor 721, a second resistor 722, a third resistor 723, and a fourth resistor 724. The measurement circuit 72 also has an amplifier 725 that amplifies the output voltage of the bridge circuit.

[0056] The first resistor 721 (movable ribbon 61) and the second resistor 722 are connected in series via the first switch 73. The third resistor 723 and the fourth resistor 724 are also connected in series. Then, between the anode and cathode of the ribbon power supply 711, the string of the first resistor 721 (movable ribbon 61) and the second resistor 722 and the string of the third resistor 723 and the fourth resistor 724 are connected in parallel.

[0057] Furthermore, a midpoint M1 between the first resistor 721 (movable ribbon 61) and the second resistor 722, and a midpoint M2 between the third resistor 723 and the fourth resistor 724 are connected to the input terminal of an amplifier 725.

[0058] The second resistor 722, the third resistor 723, and the fourth resistor 724 are fixed resistors with constant electrical resistance. That is, the resistance value R2 of the second resistor 722, the resistance value R3 of the third resistor 723, and the resistance value R4 of the fourth resistor 724 are constant. In contrast, the electrical resistance value R1 of the first resistor 721 changes depending on the amount of bending ε of the movable ribbon 61 in the up-down direction.

[0059] When the resistance value R1 of the first resistor 721 changes, the potential at the midpoint M1 between the first resistor 721 and the second resistor 722 changes. This changes the potential difference Vout between the two midpoints M1 and M2. The amplifier 725 amplifies the potential difference Vout between the two midpoints M1 and M2 by a predetermined amplification factor G. The measurement circuit 72 then outputs the amplified potential difference G*Vout as a measurement value. Therefore, the measurement value G*Vout output from the measurement circuit 72 reflects the resistance value R1 of the first resistor 721 (movable ribbon 61).

[0060] 7 is a flowchart showing the flow of operations when measuring the deflection amount ε in the initial state of the movable ribbon 61. Of the processes in FIG. 7, the processes of steps S1 to S5 proceed as the control unit 50 operates in accordance with the measurement program P2.

[0061] 7, when measuring the amount of deflection ε of the movable ribbon 61 in its initial state, first, the movable ribbon 61 is connected to the measurement circuit 72 (step S1). Specifically, in response to a command from the control unit 50, the first switch 73 is connected to the second resistor 722, and the second switch 74 is connected to the third resistor 723, as shown in FIG. 6. This forms the above-mentioned bridge circuit.

[0062] Next, a measurement voltage (hereinafter referred to as "measurement voltage Vin") is applied from the ribbon power supply 711 to the bridge circuit, and the measurement value G*Vout output from the amplifier 725 is obtained (step S2: measurement step).

[0063] The relationship between Vin and Vout in the bridge circuit is expressed by the following equation (1).

[0064]

[0065] Here, if the resistance value R1 of the first resistor 721 changes by ΔR due to the bending of the movable ribbon 61, the state of the following equation (2) is obtained.

[0066]

[0067] In this embodiment, resistors having resistance values ​​equivalent to the resistance value R1 of the first resistor 721 (movable ribbon 61) when there is no deflection are used as the second resistor 722, the third resistor 723, and the fourth resistor 724. In this case, if R1 = R2 = R3 = R4 = R, then the above formula (2) can be rewritten as the following formula (3).

[0068]

[0069] Since ΔR is sufficiently smaller than R, due to the relationship ΔR<<R, the above formula (3) can be approximated to the following formula (4):

[0070]

[0071] Here, if the gauge factor specific to the material of the movable ribbon 61 is K, the relationship between the amount of deflection ε of the movable ribbon 61 and the amount of change ΔR in the resistance value is expressed by the following equation (5).

[0072]

[0073] By substituting this formula (5) into the above formula (4), the following formula (6) is obtained.

[0074]

[0075] In equation (6), the gauge factor K and the measurement voltage Vin are fixed values. Therefore, equation (6) indicates that the amount of deflection ε of the movable ribbon 61 and Vout are proportional to each other. In other words, it can be seen that the measurement value G*Vout output from the measurement circuit 72 changes depending on the amount of deflection ε of the movable ribbon 61. The measurement circuit 72 inputs the obtained measurement value G*Vout to the control unit 50.

[0076] 6, the control unit 50 has a conversion processing unit 54. The conversion processing unit 54 is a function that is realized by the computer serving as the control unit 50 in accordance with the measurement program P2.

[0077] The conversion processing unit 54 converts the input measurement value G*Vout into the amount of deflection ε of the movable ribbon 61 (step S3: conversion step). When the gauge factor K of the movable ribbon 61 is known, the conversion processing unit 54 may calculate the amount of deflection ε of the movable ribbon 61 by substituting Vout into the above formula (6). However, when the gauge factor K is unknown or when calculation using formula (6) results in a large error, the conversion processing unit 54 may convert the measurement value G*Vout into the amount of deflection ε based on correspondence data D prepared in advance.

[0078] The correspondence data D is data that defines the relationship between the measurement value G*Vout and the amount of deflection ε of the movable ribbon 61 in the vertical direction. The correspondence data D is created in advance through experiments, etc. For example, the correspondence data D is created by intentionally deflecting the movable ribbon 61, measuring the amount of deflection ε with an optical microscope, and obtaining the measurement value G*Vout with the measurement circuit 72. The created correspondence data D is stored in the memory unit 53 of the control unit 50.

[0079] Fig. 8 is a diagram showing an example of the correspondence data D. In the correspondence data D of Fig. 8, each value on the horizontal axis representing the measurement value G*Vout and each value on the vertical axis representing the amount of deflection ε are associated one-to-one by a graph line L. However, the correspondence data D may also be data in the form of a table that associates the measurement value G*Vout with the amount of deflection ε.

[0080] The conversion processing unit 54 determines the amount of deflection ε of the movable ribbon 61 in the vertical direction based on the measurement value G*Vout and the correspondence data D. Specifically, the conversion processing unit 54 refers to the correspondence data D to determine the amount of deflection ε that corresponds to the measurement value G*Vout output from the measurement circuit 72. This makes it possible to detect the amount of deflection ε of the movable ribbon 61 in the vertical direction.

[0081] As described above, this spatial light modulator 60 acquires a measurement value that reflects the electrical resistance value of the movable ribbons 61 and converts this measurement value into the amount of deflection ε of the movable ribbons 61. In other words, the amount of deflection ε of the movable ribbons 61 is measured by electrical means rather than optical means. This makes it possible to measure the amount of deflection ε of the movable ribbons 61 with high accuracy, and also makes it possible to make the unit required for measurement more compact than when optical means are used.

[0082] In particular, in the spatial light modulator 60 of this embodiment, a measurement voltage is applied to a bridge circuit including the movable ribbons 61, and the voltage value output from the bridge circuit is measured. In this way, a measurement value G*Vout that reflects the resistance value of the movable ribbons 61 can be obtained with a relatively simple measurement circuit.

[0083] Furthermore, in this embodiment, the same ribbon power supply 711 is used in the measurement process for measuring the amount of deflection ε of the movable ribbon 61 in the initial state and during actual use of the spatial light modulator 60. Therefore, the number of parts in the spatial light modulator 60 can be reduced compared to when different power supplies are used in the measurement process and during actual use of the spatial light modulator 60.

[0084] However, it is desirable that the measurement voltage Vin applied to the movable ribbons 61 in the above measurement process be a voltage smaller than the drive voltage applied to the movable ribbons 61 when the spatial light modulator 60 is in use. Specifically, it is desirable that the measurement voltage Vin be a voltage that can ignore the displacement of the movable ribbons 61 due to the voltage itself. This makes it possible to measure the amount of deflection ε of the movable ribbons 61 in a state equivalent to the initial state in which no voltage is applied to the movable ribbons 61.

[0085] In order to prevent displacement of the movable ribbon 61 due to the measurement voltage Vin itself, when measuring the amount of deflection ε of the movable ribbon 61, a voltage equivalent to the voltage applied to the movable ribbon 61 may be applied from the common power supply 712 to the common electrode 63. In this way, no electrostatic attractive force due to the potential difference is generated between the movable ribbon 61 and the common electrode 63, and therefore no displacement of the movable ribbon 61 occurs due to the electrostatic attractive force. Therefore, the amount of deflection ε of the movable ribbon 61 in its initial state can be measured with greater accuracy.

[0086] After measuring the amount of deflection ε of each movable ribbon 61 of the spatial light modulator 60 by the above measurement, the control unit 50 determines whether the spatial light modulator 60 is usable based on the obtained amount of deflection ε (step S4). Specifically, if the amount of deflection ε of at least one movable ribbon 61 of the multiple movable ribbons 61 of the spatial light modulator 60 is equal to or greater than a preset threshold, the control unit 50 determines that the spatial light modulator 60 is unusable (step S4: No). In this case, the spatial light modulator 60 needs to be replaced, so the control unit 50 outputs an error to a display or the like (step S5).

[0087] On the other hand, if the deflection amount ε of all the movable ribbons 61 of the spatial light modulator 60 is less than the preset threshold, the control unit 50 determines that the spatial light modulator 60 is usable (step S4: Yes). In this case, the control unit 50 performs exposure processing using the spatial light modulator 60.

[0088] At this time, the control unit 50 corrects the drive voltage applied from the ribbon power supply 711 to the movable ribbons 61 based on the amount of deflection ε of each movable ribbon 61. Specifically, the control unit 50 increases or decreases the drive voltage in a direction that cancels the displacement of the movable ribbons 61 due to the amount of deflection ε. This reduces errors due to the amount of deflection ε in the initial state, allowing the spatial light modulator 60 to modulate light with greater precision.

[0089] 4. Modifications Although one embodiment of the present invention has been described above, the present invention is not limited to the above embodiment.

[0090] In the above embodiment, only the amount of slack ε in the initial state of the movable ribbon 61 was measured out of the movable ribbon 61 and the fixed ribbon 62. However, the amount of slack in the initial state of the fixed ribbon 62 may also be measured using a similar method.

[0091] Furthermore, in the above embodiment, a description has been given of the spatial light modulator 60 used in the exposure apparatus 1. However, in a spatial light modulator used in other apparatuses such as a CTP (Computer to Plate) apparatus, the amount of deflection of the movable ribbon in the initial state may be measured using a similar method.

[0092] In the above embodiment, the control unit 50, which directly controls the spatial light modulator 60, measures the amount of deflection ε of the movable ribbon 61. The control unit 50 also converts the measurement value G*Vout into the amount of deflection ε, determines whether the movable ribbon 61 is usable, etc. However, these processes may be performed by a computer for remote diagnosis connected to the spatial light modulator 60 via a network.

[0093] Furthermore, in the above embodiment, the case has been described where the amount of flexure ε of the movable ribbons 61 is measured for the spatial light modulator 60 mounted on the shipped exposure apparatus 1. However, the amount of flexure ε of the movable ribbons 61 of the spatial light modulator 60 may also be measured using a similar method during manufacturing of the exposure apparatus 1 before shipping.

[0094] Furthermore, within the scope of the present invention, some of the elements appearing in the above embodiments may be deleted, or known techniques may be added to the above embodiments.

[0095] REFERENCE SIGNS LIST 1 Exposure device 9 Substrate 10 Base 20 Stage 30 Moving mechanism 40 Exposure unit 41 Head 50 Control unit 54 Conversion processing unit 60 Spatial light modulator 61 Movable ribbon 62 Fixed ribbon 63 Common electrode 64 Ribbon mounting surface 70 Electrical circuit 71 Voltage application circuit 72 Measurement circuit 73 First switch 74 Second switch 711 Ribbon power supply 712 Common power supply 721 First resistor 722 Second resistor 723 Third resistor 724 Fourth resistor 725 Amplifier P1 Exposure program P2 Measurement program D Correspondence data

Claims

1. A measurement method for measuring the amount of deflection of a spatial light modulator having multiple movable ribbons that can be displaced by applying a voltage, the measurement method comprising: a measurement step for obtaining a measurement value reflecting the electrical resistance value of the movable ribbons; and a conversion step for converting the measurement value obtained by the measurement step into the amount of deflection of the movable ribbons.

2. A measurement method according to claim 1, wherein the measurement step includes applying a measurement voltage to a bridge circuit including the movable ribbons, and measuring a voltage value output from the bridge circuit.

3. A measurement method according to claim 2, wherein the measurement voltage applied to the movable ribbons in the measurement step is smaller than a drive voltage applied to the movable ribbons when the spatial light modulator is in use.

4. A measurement method according to any one of claims 1 to 3, wherein in the conversion step, the measurement value is converted into the amount of deflection based on correspondence data indicating the correspondence between the measurement value and the amount of deflection.

5. A method of using the spatial light modulator utilizing the measurement method according to any one of claims 1 to 4, comprising correcting the drive voltage applied to the movable ribbons based on the amount of deflection obtained by the conversion process.

6. A method for determining whether or not the spatial light modulator can be used by utilizing the measurement method according to any one of claims 1 to 4, comprising the steps of: determining that the spatial light modulator can be used if the amount of deflection obtained by the conversion process is less than a predetermined threshold; and determining that the spatial light modulator cannot be used if the amount of deflection is equal to or greater than the threshold.

7. A measurement device for measuring the amount of deflection of a spatial light modulator having a plurality of movable ribbons that can be displaced by application of a voltage, comprising: a measurement circuit for acquiring a measurement value reflecting the electrical resistance value of the movable ribbons; and a conversion processing unit for converting the measurement value acquired by the measurement circuit into the amount of deflection of the movable ribbons.

8. A measuring device according to claim 7, wherein said measuring circuit comprises a bridge circuit including said movable ribbon.

9. A measuring device as described in claim 7 or claim 8, further comprising a memory unit in which correspondence data indicating the correspondence between the measurement value and the amount of deflection is stored, and the conversion processing unit converts the measurement value into the amount of deflection based on the correspondence data.

10. A spatial light modulator equipped with a measurement device according to any one of claims 7 to 9, comprising: a voltage application circuit which applies a voltage to the movable ribbon; and a control unit which controls the voltage application circuit, wherein the control unit corrects the drive voltage applied by the voltage application circuit to the movable ribbon based on the amount of deflection obtained by the conversion processing unit.

11. A spatial light modulator equipped with the measurement device according to any one of claims 7 to 9, comprising a control unit which determines that the spatial light modulator is usable when the amount of deflection obtained by the conversion processing unit is less than a predetermined threshold, and determines that the spatial light modulator is unusable when the amount of deflection is equal to or greater than the threshold.

12. A program for measuring the amount of deflection of movable ribbons in a spatial light modulator having multiple movable ribbons that can be displaced by applying a voltage, the program causing a computer to execute a measurement process for obtaining a measurement value reflecting the electrical resistance value of the movable ribbons, and a conversion process for converting the measurement value obtained by the measurement process into the amount of deflection of the movable ribbons.

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