JP5201915B2 - Drive device - Google Patents

Description

  The present invention relates to a driving device, and is suitably used for driving, for example, an optical element constituting an optical system of a semiconductor exposure apparatus.

  A semiconductor exposure apparatus used in a lithography process in the manufacture of semiconductor elements and microdevices is an apparatus that exposes and transfers a pattern formed on an original (reticle) to a substrate (silicon wafer). The degree of integration of semiconductor elements is increasing year by year, and in order to create a highly integrated circuit pattern, it is essential to reduce the aberration and distortion of the projection optical system.

  As a driving device for an optical element constituting an optical system of a semiconductor exposure apparatus, a mechanism using a parallel leaf spring is proposed in Patent Document 1. In the driving device disclosed in Patent Document 1, the pressure or volume of the space sandwiched between two parallel leaf springs is changed using a driving fluid to drive the optical element.

Further, in Patent Document 2, by using three flexure (elastic hinge) mechanisms, the movable lens is driven to shift in the optical axis direction and two axial directions orthogonal to the optical axis, and around two axes orthogonal to the optical axis. Discloses a structure capable of tilt driving. In Patent Document 2, the rotational displacement of the horizontal direction drive lever and the vertical direction drive lever is converted into the horizontal and vertical shift displacements of the displacement output portion of the flexure mechanism.
JP 2000-357651 A JP 2002-131605 A

  However, with the drive mechanism disclosed in Patent Document 1, as the semiconductor device pattern becomes higher definition, it becomes difficult for the drive accuracy (parallel eccentricity and inclination accompanying the movement of the optical element) to satisfy the required accuracy. ing.

  Further, the drive mechanism disclosed in Patent Document 2 adjusts the tip displacement of the horizontal drive lever and the vertical drive lever with an adjustment washer and an adjustment button, and has a structure for automatically controlling the lens drive displacement. Not. Even if the adjustment washer and the adjustment button are replaced with a piezo actuator or the like and the structure can be automatically adjusted, the actuator protrudes in the optical axis direction and the thickness in the optical axis direction becomes large.

  An object of the present invention is to provide a driving device that can accurately drive an object in the direction of six degrees of freedom while being thin in view of the above-described conventional technology.

In order to achieve the above object, the present invention is a drive device having three drive units each including a pair of linear actuators and capable of driving an optical element in six axial directions, each drive unit including a pair of linear actuators. Are arranged so as to face each other in the direction along the same axis and transmit the driving force, and a link mechanism that transmits the driving force in a direction different from the driving direction by the pair of linear actuators is provided between the pair of linear actuators. It possesses the further connected to outer ends of the pair of linear actuators, only in the central portion located below the linkage mechanism is characterized with a member fixed to the fixed lens barrel.
According to another aspect, the present invention is a drive device having three drive units each including a pair of linear actuators and capable of driving an optical element in six axial directions with respect to a fixed barrel, The drive unit is arranged so that a pair of linear actuators face each other in the direction along the same axis and transmits a driving force, and transmits the driving force in a direction different from the driving direction by the pair of linear actuators. A link mechanism is provided between the pair of linear actuators, and further includes a member connected to an outer end of the pair of linear actuators, and the member is arranged at the central portion located below the link mechanism. It is fixed to the fixed barrel and is fixed to the fixed barrel via elastic hinges on both sides of the central portion.

  According to the driving device of the present invention, it is possible to drive an object with high accuracy in the direction of six degrees of freedom while being thin.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments of a drive device of the present invention will be described with reference to the drawings.

  FIG. 1 is a view showing an example of a schematic configuration of a semiconductor exposure apparatus to which a driving apparatus of the present invention is applied.

  The exposure apparatus according to the present embodiment is a projection exposure apparatus that exposes a circuit pattern formed on a reticle onto a wafer using EUV light (for example, wavelength 13.4 nm) as exposure light. Hereinafter, an exposure apparatus using EUV light will be described. However, the driving apparatus of the present invention can also be applied to an exposure apparatus using a light source that emits exposure light other than EUV light, such as a KrF, ArF excimer laser, or F2 laser. is there.

  Such an exposure apparatus is suitable for a lithography process of sub-micron or quarter-micron or less, and in the present embodiment, a step-and-scan type exposure apparatus (also referred to as “scanner”) will be described as an example.

  Referring to FIG. 1, the exposure apparatus of the present embodiment takes an image of a circuit pattern formed on reticle 5 (not shown) on which reticle 5 is placed, wafer stage 9 on which wafer 8 is placed, and reticle 5. A projection optical system 1 for projecting onto the wafer 8 is provided.

  Further, since EUV light has a low transmittance to the atmosphere, at least the optical path through which the EUV light passes (that is, the entire optical system) is a vacuum atmosphere.

  The reticle 5 is a reflective reticle, on which a circuit pattern to be transferred is formed. The reticle 5 is supported and fixed to the reticle stage using an electrostatic chuck or the like, and is driven integrally with the reticle stage. The diffracted light emitted from the reticle 5 is reflected by the projection optical system 1 and projected onto the wafer 8. Since the exposure apparatus of the present embodiment is a step-and-scan type exposure apparatus, the pattern of the reticle 5 is reduced and projected onto the wafer 8 while the reticle 5 and the wafer 8 are scanned in synchronization.

  The projection optical system 1 includes a plurality of reflection mirrors (optical elements 103). The number of mirrors is about 4 to 8. FIG. 1 shows an example of six mirror systems. In order to realize a wide exposure region with a small number of mirrors, such as four to eight, it is preferable to use only a thin arc-shaped region (ring field) separated from the optical axis by a certain distance. The numerical aperture (NA) of the projection optical system 1 is about 0.2 to 0.4.

  The lens barrel surface plate 2 and the base frame 3 are fastened via the vibration isolation mechanism 4 so that the vibration of the floor to be installed is not transmitted to the projection optical system 1 and further to each mirror constituting the projection optical system 1.

  An optical element control unit 10 controls the optical element driving device in accordance with a predetermined control flow. Specifically, as a result of calculation so as to minimize an error amount such as a magnification error obtained from exposure aberration and alignment information, a command is given to the drive device based on a program, and a predetermined optical element is adjusted and driven. Thus, the optical performance of the projection optical system 1 is optimized.

  FIG. 2 is a diagram showing a drive device that is mounted with the drive unit 115 of this embodiment and three drive units 115 and can drive an optical element in a desired direction. 2A is a plan view, FIG. 2B is a BB sectional view in FIG. 2A, and FIG. 2C is an EE sectional view in FIG. 2A. FIG. 3 is a cross-sectional view taken along the line AA in FIG.

  2 and 3, reference numeral 101 denotes a fixed lens barrel. The fixed barrel 101 has a flat portion that fixes a drive unit 115 and a position detection unit 102, which will be described later, and a side wall portion that is coupled to other optical elements adjacent vertically. In the figure, the fixed barrel 101 is shown in a cylindrical shape, but this is not restrictive. An optical element support frame 104 serves as a support member that supports the optical element. Reference numeral 115 denotes a drive unit, and three identical drive units are installed on the bottom flat portion of the fixed barrel 101. Reference numeral 102 denotes a position detection unit that detects the displacement in the optical axis direction of the optical element support frame 104 or the holding mechanism 106, the direction displacement orthogonal to the optical axis, and the angle around the orthogonal translation axis direction. As the position detection unit, an interference type length measuring device, a capacitance displacement meter, a linear encoder, a differential transformer displacement meter, an eddy current displacement meter, and the like are suitably used according to required accuracy and a measurement distance range.

  When the optical element 103 has a rotationally symmetric shape with respect to the optical axis, the drive unit 115 can be easily arranged at an equal angle of 120 degrees with respect to the optical axis and at an equal distance from the optical axis. It is. However, in the case of a reflection type projection optical system as shown in FIG. 1, the in-lens structure must be arranged so as not to block the optical path, and the degree of freedom of arrangement of the drive unit 115 is limited. Yes. In such a case, the centroid of the triangle formed by the three contact portions of the drive unit 115 and the optical element support frame 104 projects the center of gravity of the movable portion supported by the three drive units 115 onto the plane formed by the triangle. It is desirable to coincide with the point (see FIG. 4). When the degree of mismatch is large, posture control performance is likely to deteriorate, and as a result, imaging performance is likely to deteriorate. The range of coincidence depends on the sensitivity of the optical system, the control configuration, and the like, but the point where the center of gravity of the movable part is projected onto the triangle should be inside the triangle.

  FIG. 5 is an example showing a connected state of the drive unit 115 and the optical element support frame 104. Thus, the dodging mechanism 107 may be provided between the drive unit 115 and the optical element support frame 104. The dodging mechanism 107 can suppress the deformation of the surface of the optical element 103 caused by the force applied by the operation of the drive unit 115 being applied to the optical element support frame 104. As an example, the dodging mechanism 107 has a structure in which a slit is formed by wire electric discharge machining or the like from four directions of a cubic block to form a cross spring as shown in the figure. When this dodging mechanism 107 is attached to the drive unit 115, one of the two surfaces not subjected to slit processing is fixed to the output surface of the drive unit 115 with a screw, and the other surface is attached to the optical element support frame 104. Secure with screws. The fixing of the drive unit 115 and the dosing mechanism 107 is shown as an example in which the drive unit 115 is fixed by screws from the lower surface of the drive unit 115.

  The heights of the three drive units 115 and the dosing mechanism 107 in the Z direction are not exactly the same. Therefore, the height of the dosing mechanism 107 is processed at a pitch of 5 μm, for example, and can be replaced in place of the spacer, so that the height of the three portions can be relatively aligned and the optical element support frame 104 can be leveled. It is. As a result, unintended deformation of the optical element 103 can be reduced.

  Incidentally, a holding mechanism 106 is provided between the optical element 103 and the optical element support frame 104, and this holding mechanism 106 has a function of reducing deformation transmission to the optical element 103. For this reason, depending on the sensitivity to the image formation performance due to the deformation reduction performance of the holding mechanism 106 and the deformation of the optical element 103, the dodging mechanism 107 may not be provided. The holding mechanism 106 also functions to compensate for the position and shape attachment reproducibility in the assembly adjustment process of the projection optical system 1.

  FIG. 6 shows an example of the holding mechanism 106 in an exploded perspective view. The holding mechanism 106 is mainly composed of two parts. The first block 106a includes leaf springs on the left and right sides, and has a structure that is fixed to the optical element support frame 104 by a fixing portion at the tip. The optical element 103 is brought into contact with a groove on a radial projection provided on the mirror by putting a steel ball (both not shown) in a cone shape provided in the first block. The second block 106b is provided with a cone shape so as to form an isosceles triangle with the cone portion provided in the first block, and the two blocks on the opposite surface coupled to the first block provided in the mirror via the steel ball 108 are provided. Fixed by a groove. At this time, in order to make the fixing force constant, the second block 106b is provided with two leaf spring portions, and this deflection is made constant.

  As described above, the position of the optical element 103 is detected by the position detection unit 102 attached to the fixed barrel 101. The target of the detection unit is any one of the optical element 103, the holding mechanism 106, and the optical element support frame 104. It is desirable that it is provided. If the holding mechanism 106 and the optical element support frame 104 are not sufficiently rigid and the required optical accuracy cannot be satisfied, a target may be provided on the optical element 103.

  When the target of the detection unit 102 is provided in the holding mechanism 106, for example, the first block 106a and the second block 106b can also serve as the target. When an interference type length measuring device is used as the detection unit, a reflecting mirror is used, and when a capacitance type length measuring device is used, a target electrode is attached.

  2 and 3, the optical element position detection unit 102 is provided at three places in the Z-axis direction and three places along the X and Y planes. FIG. 2 is an example in which a detection unit in the Z direction and a detection unit in the direction along the X and Y planes are integrally formed.

  From the above, by arbitrarily operating the three drive units 115, it becomes possible to operate the optical element 103 to be driven in six axial directions. If the control system is configured such that the optical element 103 is at a desired position based on the detection result of the position detection unit 102, an optical element driving device having high positioning accuracy can be realized.

  Next, details of the drive unit 115 will be described with reference to FIG. In FIG. 7, local orthogonal coordinate systems α, β, and γ are defined in order to distinguish from the coordinate system of the entire exposure apparatus shown in FIGS.

  The drive unit 115 has a pair of linear actuators and a link mechanism provided therebetween. The link mechanism is a mechanism for transmitting the driving force of a pair of linear actuators in a direction different from the driving direction of the actuator, and is formed from a single metal block by wire electric discharge machining and cutting. In FIG. 7, 112a and 112b are stacked piezoelectric actuators as an example of a linear actuator. The piezo actuators 112a and 112b are arranged to face each other in the direction along the same axis (direction along the α axis) and transmit the driving force. Each of the piezo actuators 112a and 112b is a piezoelectric in which a drive source in which electrostrictive elements and electrodes are alternately stacked is enclosed in an expandable / contracted sealed cylindrical container, and the total length in the α-axis direction increases approximately in proportion to the applied voltage. Actuator.

  Reference numeral 113 denotes an adjusting screw for correcting a dimensional error of the piezo actuators 112a and 112b and applying pressure. The adjustment screw 113 is interposed between the drive unit 115 and the piezoelectric actuators 112a and 112b. This adjusting screw can be fixed by a nut.

Reference numeral 114 denotes a drive unit mounting screw. The drive unit 115 is screwed to the fixed barrel 101 with the screw 114. As shown in FIG. 7, the drive unit 115 is attached to the fixed barrel 101 at a part of the lower surface thereof. This is because the driving force by the actuator deforms the barrel and the error of the optical element position detecting means 102 is detected. This is to reduce the occurrence of the above .

  Next, a manufacturing method of the drive unit 115 will be described.

  The drive unit 115 forms the outer portion of the link mechanism shown in FIG. 7B by milling from a plate-shaped metal block having a predetermined thickness as a base material. Next, using a drilling machine, after processing a round hole for a screw to be attached to the fixed barrel, an adjustment screw hole for loading the adjustment screw 113 is processed. And in order to form an elastic hinge part precisely, wire electric discharge machining is performed and the machining is completed.

  The drive unit 115 is attached to the fixed barrel 101 accurately by abutting the fixed barrel 101 with a positioning pin. Next, piezo actuators are loaded into the drive unit 115 one by one from the side surface, tightened with the adjusting screw 113 so that the preload amount becomes a constant amount, and fixed with nuts to complete the assembly. The preload amount can be managed by applying a height gauge such as a dial gauge to the upper surface of the optical element frame drive link 115g and tightening the preload adjusting screw so that the amount of increase in the γ-axis direction becomes a constant value. it can. In the case of such a drive unit 115, it is desirable that the preload amounts of the two left and right piezo actuators are also constant. Therefore, the preload is measured while measuring the lateral displacement (α direction) of the optical element frame drive link 115g with a dial gauge or the like. It is good to make adjustments.

  FIG. 8 is a diagram for explaining the link operation of the drive unit 115.

  When an arbitrary voltage is applied to electrode terminals (not shown) provided on the piezo actuators 112a and 112b, the total length L of the piezo actuators 112a and 112b expands by dx1 and dx2 (leftward in the drawing), respectively. Accordingly, the horizontal links 115a and 115b, which are a pair of linear motion guide link mechanisms respectively corresponding to the piezoelectric actuators 112a and 112b, are also displaced by approximately dx1 and dx2, respectively.

  Then, the direction conversion links 115c and 115d arranged at an angle θ with respect to the α axis rotate to raise the optical element frame drive link 115g by dz in the γ axis direction and to displace dx3 in the α axis direction. If the displacement amounts dx1, dx2 given by the left and right piezo actuators 112a, 112b are equal, dx3 becomes almost zero, and an output displacement is obtained only in the γ-axis direction. The γ-axis direction displacement dz is approximately cot θ times the average value of the displacements of the horizontal links 115a and 115b. Here, this magnification is called the geometric magnification of the direction change links 115a and 115b, and is defined as λ (= cot θ).

  In order to extract a large displacement from slight generated displacements of the piezo actuators 112a and 112b and to realize a wide range of driving amounts of optical elements, it is desirable to increase λ. In order to increase λ, it is preferable to decrease θ. However, if the enlargement ratio is increased, the natural frequency of the drive unit 115 is reduced. For example, vibration from the outside of the lens barrel is transmitted to the optical element 103, which may cause deterioration in image performance or decrease in drive speed. Or Therefore, consideration must be given to the size of the enlargement ratio. In the case of a driving device for adjusting and driving the optical element 103, it is particularly preferable in terms of vibration characteristics that the geometric magnification λ is set to 0.5 or more and 2 or less. Further, from the viewpoint of the space in the γ-axis direction, the angle θ formed with the α-axis of the direction conversion links 115c and 115d of the drive unit 115 is preferably between 30 and 60 degrees. In this case, the geometric magnification λ is approximately between 0.57 and 1.72.

  As described above, the optical element frame drive link 115g moves in the γ direction and the α direction as the piezo actuators 112a and 112b extend, but this link may be displaced only in these two directions and not in the β direction. desirable. Therefore, support links 115e and 115f are connected to the left and right sides of the optical element frame drive link 115g for guiding in the γ-axis direction. Further, the support links 115s and 115t are connected so that the piezoelectric actuators 112a and 112b operate along the α axis. By providing the auxiliary link in this way, the optical element frame drive link 115g is moved only in the γ direction and the α direction.

  As shown in FIG. 2, the driving unit 115 operable in the two directions of the γ direction and the α direction is arranged around the movable portion, and the optical element is supported by arbitrarily operating a total of six piezoelectric actuators. The frame 104 and the optical element 103 can be operated with six degrees of freedom.

  FIG. 9 is a control block diagram for controlling the exposure operation and the optical element driving operation of the exposure apparatus shown in FIG. 21 is a main body CPU for controlling the operation of the entire exposure apparatus, 31 is a mount control means for controlling the vibration isolation operation of the lens barrel mount 3, and 41 is an illumination control means for controlling the illumination mode and light quantity of the illumination unit. Further, 61 is a reticle stage control means for controlling the driving of the reticle stage, and 91 is a wafer stage control means for controlling the driving of the wafer stage 9.

  An optical element control means 10 has a plurality of optical elements CPU11, and each optical element CPU performs drive control of one optical element shown in FIG. Six piezo drivers 12 are connected to each optical element CPU 11, and each piezo driver drives each piezo actuator 112a, 112b built in the three drive units of FIG.

  In addition, six position detection units 102 are connected to each optical element CPU11. Of the six detection units, the three position detection units 102 detect displacement along the coaxial axis of the optical element 103, the optical element support frame 104, or the holding mechanism 106, that is, the Z-axis direction displacement. The remaining three position detection units 102 detect the position in the horizontal plane direction in the vicinity of the optical element 103, the optical element support frame 104, or the holding mechanism 106. The other optical element CPU 11 is also connected to the piezo driver and the position detection unit in the same manner as described above.

  The drive device of Example 2 will be described. The drive unit of the present embodiment is different from the first embodiment in the configuration of the drive unit, but the method of use, the control method, and the like are essentially the same as those of the first embodiment.

  FIG. 10 is a diagram for explaining the configuration of the drive unit according to the second embodiment. The members having the same reference numerals as those in FIG. 7 have the same functions, and thus description thereof is omitted.

  Reference numeral 215 denotes a drive unit of the present embodiment. The drive unit 215 has a pair of linear actuators and a link mechanism provided therebetween. Reference numerals 212a and 212b denote stacked piezoelectric actuators similar to those in the first embodiment. Reference numeral 213 denotes an adjustment screw for correcting a dimensional error of the piezoelectric actuators 212a and 212b and applying a preload.

  The piezoelectric actuators 212a and 212b of this embodiment are configured to be sandwiched between the inner actuator holders 216a and 216b and the outer actuator holders 217a and 217b, respectively. The inner and outer actuator holders are provided with elastic hinges H37, H38, H47, and H48 (see FIG. 11) for reducing moments caused by a shape error of the piezoelectric actuator, a shape error of the drive unit 215, and the like. .

  The inner actuator holders 216a and 216b have U-shaped grooves (different from the elastic hinge portion), and the position in the γ-axis direction is constrained by the positioning pins 218 formed in the drive unit 215. A hole (not shown) is provided on the outside of one of the outer actuator holders 217a and 217b, and by engaging with an emboss provided at the tip of the adjustment screw 213, the screw is rotated while being aligned. Therefore, the structure can be adjusted for preload.

  Reference numeral 214 denotes a drive unit mounting screw. The drive unit 215 is screwed to the fixed barrel 101 with a screw 214.

  As shown in FIG. 10B, further elastic hinges 215h and 215i are provided in the vicinity of the attachment surfaces at both ends of the drive unit 215. This has a role of reducing transmission of the driving force of the piezo actuator to the fixed barrel 101 and a role of reducing thermal distortion caused by a difference in thermal expansion coefficient between the drive unit 215 and the fixed barrel 101. In order to reduce thermal deformation, the fixed barrel 101 is often made of a material having a coefficient of thermal expansion as small as possible, such as Super Invar. On the other hand, the drive unit 215 often selects a material having high rigidity and high yield strength. When such a combination of materials is selected, a thermal strain generated by exposure heat or the like may cause a position error of the position detection unit, which may cause a decrease in positioning accuracy of the optical element. In order to alleviate this, elastic hinges 215h and 215i are provided in the vicinity of fixed portions at both ends (both ends in the longitudinal direction) of the drive unit 215 in the large dimension direction.

In addition, when the rigidity of the fixed barrel 101 is sufficiently high, the influence on the position detection unit is reduced. Therefore, in this case , the fixed barrel 101 may be tightened without using the additional elastic hinges 215h and 215i on both sides of the drive unit 215.

  FIG. 11 is a diagram for explaining the link operation of the drive unit 215.

  When an arbitrary voltage is applied to electrode terminals (not shown) provided on the piezo actuators 212a and 212b, the total length L of the piezo actuators 212a and 212b expands by dx1 and dx2 (leftward in the figure) in the α-axis direction, respectively. At the same time, the horizontal links 215a and 215b are also displaced by dx1 and dx2, respectively.

  Then, the direction conversion links 215c and 215d arranged at an angle θ with respect to the α axis rotate to raise the optical element frame drive link 215g by dz in the γ axis direction. As a result, the driven object is displaced by dx3 in the α-axis direction. If the displacement amounts dx1, dx2 given by the left and right piezo actuators 212a, 212b are equal, dx3 is almost zero, and an output displacement is obtained only in the γ-axis direction. For the purpose of adjusting the driving of the optical element 103, the geometric magnification λ is preferably 0.5 or more and 2 or less as in the first embodiment.

  As described above, as the piezoelectric actuators 212a and 212b extend, the optical element frame drive link 215g moves in the γ direction and the α direction as in the first embodiment. As shown in FIG. 2, the drive unit 215 that performs such an operation is arranged at three locations around the drive target, and arbitrarily operates a total of six piezo actuators, whereby the optical element support frame 104 and the optical element are operated. 101 can be driven in six axes.

  Of the elastic hinges in the drive unit 215, the four elastic hinges H31, H32, H41, and H42 at both ends of the direction change links 215c and 215d are preferably capable of acting as spherical joints. This enables operation in the β-axis direction. On the other hand, support links 215e, 215f, 215s, and 215t are auxiliary links that enable the piezoelectric actuators 212a and 212b to move linearly on the α axis. H33 and H34 are elastic hinges of the support link 215e, and H43 and H44 are elastic hinges of the support link 215f. H35 and H36 are elastic hinges of the support link 215s, and H45 and H46 are elastic hinges of the support link 215t.

  Next, a manufacturing method of the drive unit 215 of this embodiment will be described.

  The drive unit 215 forms the outer portion of the link mechanism shown in FIG. 10 by milling from a plate-shaped metal block having a predetermined thickness as a base material. Next, in order to give the four elastic hinges H31, H32, H41, and H42 the role of a spherical joint, the portions forming the elastic hinges H31, H32, H41, and H42 are formed from both sides of the plate metal block by an end mill or the like. Drill holes (see FIG. 12). The hole is not penetrated and processed so that the necessary thickness remains in the center of the plate-like metal block. Thereafter, the entire elastic hinge is formed by wire electric discharge machining or the like. As a result, the portions of the elastic hinges H31, H32, H41, and H42 have a prismatic shape and can be rotated not only in one direction but also in two directions, thereby serving as a spherical joint.

  The hole processing for leaving the central thin plate of the metal plate in advance may be performed by electric discharge. When processing with an end mill or the like, the bottom surface of the hole is tapered due to the dent of the blade, so that it is necessary to flatten the bottom surface with an end mill or the like having a small diameter.

  The assembly is shown in a perspective view including a partially exploded view of FIG. After the drive unit 215 is attached to the fixed barrel 101, the piezoelectric actuators 212a and 212b sandwiched between the inner actuator holders 216a and 216b and the outer actuator holders 217a and 217b are inserted into the drive unit 215.

  As shown in the partially enlarged view of FIG. 12, a positioning pin 218 is provided at the actuator side end of the link mechanism. The positioning of the actuator portion is performed by fitting the positioning pins 218 and the U-shaped grooves formed in the inner actuator holders 216a and 216b. There is an adjustment screw 213 on the outer actuator holder 217a, 217b side. The preload adjustment amount is managed by the adjusting screw 213 and fixed with a nut. The preload adjustment amount is managed by applying a height gauge such as a dial gauge to the upper surface of the optical element frame drive link 115g and tightening the preload adjustment screw so that the amount of increase in the γ-axis direction becomes a constant value. In the case of the drive unit 115 of this embodiment, it is desirable that the preload amounts of the left and right piezo actuators are also constant, so that the lateral displacement (α direction) of the optical element frame drive link 115g is measured with a dial gauge or the like. It is better to adjust the preload.

  The drive device of Example 3 will be described. The drive device of the present embodiment also has a drive unit configuration that is different from that of the first embodiment, but its usage, control method, and the like are essentially the same as those of the first embodiment.

  FIG. 13 is a diagram for explaining the configuration of the drive unit 315 according to the third embodiment. In FIG. 13, the fixed barrel 101 is not shown, but the drive unit 315 is screwed to the fixed barrel 101 as in the second embodiment. FIG. 14 is a cross-sectional view taken along the line AA in FIG. 13A and shows the relationship between the piezoelectric actuator 213a, the outer actuator holder 317a, and the adjusting screw 313.

  The drive unit 315 has a pair of linear actuators and a link mechanism provided therebetween. 312a and 312b are stacked piezoelectric actuators similar to the first and second embodiments. Reference numeral 313 denotes an adjustment screw for correcting a dimensional error of the piezo actuators 312a and 312b and applying a preload.

  317a and 317b are outer actuator holders provided outside the piezo actuators 312a and 312b, respectively. The outer actuator holders 317a and 317b are provided with elastic hinges H37 and H47 (see FIG. 15) for reducing the moment caused by the shape error of the piezoelectric actuator, the shape error of the drive unit 315, and the like from being applied to the piezoelectric actuator. It has been. In addition, a hole is provided on the outside of the outer actuator holders 317a and 317b, and the preload adjustment is performed by rotating the screw while aligning by fitting with an emboss provided at the tip of the adjustment screw 313. It has a possible structure.

  The operation principle of the drive unit 315 of this embodiment is shown in FIG.

  Although the principle is basically the same as that of the second embodiment, the drive unit 315 is configured to be separable into three parts in order to easily attach and detach the piezoelectric actuators 312a and 312b. As shown in FIG. 15, “separation” refers to the central portion 320, the first support housing 321a, and the second support housing 321b. As shown in FIG. 11, in the case of Example 2, the fixing to the fixed barrel 101 was performed at three locations, ie, the central portion and both end portions (the fixing portion is indicated by hatching). However, in the case of the present embodiment, it is configured to be fixed only at the central portion. However, also in this embodiment, a three-point fixing method in which both ends are fixed may be used.

  When an arbitrary voltage is applied to electrode terminals (not shown) provided on the piezo actuators 312a and 312b, the total length L of the piezo actuators 312a and 312b expands by dx1 and dx2 (leftward in the drawing), respectively. At the same time, the horizontal links 315a and 315b are also displaced by dx1 and dx2, respectively.

  Then, the direction conversion links 315c and 315d arranged at an angle θ with respect to the α axis rotate to raise the optical element frame drive link 315g by dz in the γ axis direction. As a result, the driven object is displaced by dx3 in the α-axis direction. If the displacement amounts dx1 and dx2 given by the left and right piezo actuators 312a and 312b are equal, dx3 becomes almost zero, and an output displacement is obtained only in the γ-axis direction. For the purpose of driving and adjusting the optical element 103, the geometric magnification λ is preferably 0.5 or more and 2 or less, as in the first and second embodiments.

  As described above, as the piezoelectric actuators 312a and 312b extend, the optical element frame drive link 315g moves in the γ direction and the α direction as in the first and second embodiments. As shown in FIG. 2, the drive unit 315 that performs such an operation is arranged at three locations around the drive target, and arbitrarily operates a total of six piezo actuators, whereby the optical element support frame 104 and the optical element are operated. 103 can be driven in six axes.

  Of the elastic hinges in the drive unit 315, the four elastic hinges H31, H32, H41, and H42 at both ends of the direction change links 315c and 315d are preferably capable of acting as spherical joints. This enables operation in the β-axis direction. On the other hand, support links 315e, 315f, 315s, and 315t are auxiliary links that allow the piezo actuators 312a and 312b to move linearly on the α axis. H33 and H34 are elastic hinges of the support link 315e, and H43 and H44 are elastic hinges of the support link 315f. H35 and H36 are elastic hinges of the support link 315s, and H45 and H46 are elastic hinges of the support link 315t.

  The formation method of the central portion 320 is generally the same as that of the drive unit 215 of the second embodiment. It is preferable to use a method in which holes are drilled from the surfaces (both sides) on which the positioning pins 322 are provided in portions directly contacting the piezoelectric actuators 312a and 312b, and the bottom surface is finished by grinding.

  The first and second support housings 321a and 321b are perforated from the surface side in contact with the drive unit center 320 so as to surround the piezoelectric actuators 312a and 312b, respectively. In order to avoid contact with the piezo actuators 312a and 312b, the holes having a larger diameter than the piezo actuators 312a and 312b are preferable. Further, a groove is formed from the side so as to be perpendicular to the hole. This groove is used to take out the wiring of the piezoelectric actuators 312a and 312b from the inside to the outside of the first and second support housings 321a and 321b, and is used as a positioning guide for the outside actuator holders 317a and 317b.

  Next, the assembly procedure of the drive unit 315 of the present embodiment will be described.

  As a first step, the drive unit center 320 is screwed to the fixed barrel (not shown) from the back side. As a second step, the adjustment screw 313 is inserted into the first support housing 321a in advance, and the outer actuator holder 317a and the piezoelectric actuator 312a are inserted into the holes and grooves. As a third step, the first support housing 321 a and the drive unit center 320 are coupled with a fixing screw 323. In this case, the positioning in the γ direction is performed by a spacer sandwiched between the fixed barrel. Positioning in the β direction is performed by a pin attached to the drive unit center 320. As a fourth step, the second support housing 321b opposite to the drive unit center 320 is also assembled in the same manner as the first support housing 321a. As a fifth step, preload adjustment to the piezoelectric actuators 312a and 312b is performed in the same manner as in the first and second embodiments.

  The drive device of Example 4 will be described. The drive unit of the present embodiment is similar to the third embodiment in the configuration of the drive unit. The usage method and control method of the drive unit are essentially the same as in the first embodiment.

  FIG. 16 is a diagram for explaining the configuration of the drive unit 415 of the fourth embodiment.

  In FIG. 16, reference numerals 412a and 412b denote a pair of stacked piezoelectric actuators similar to the first and second embodiments. Reference numeral 413 denotes an adjusting screw for correcting a dimensional error of the piezoelectric actuators 412a and 412b and applying a preload. 415a and 415b are horizontal links. Reference numerals 415c and 415d denote direction change links. Reference numeral 415g denotes an optical element frame drive link.

  The drive unit of this embodiment is different from that of Embodiment 3 in that the cross section of the drive unit 415 is a substantially parallelogram as shown in FIG. In the configuration of the third embodiment, the drive unit can drive in the α direction and the γ direction, but cannot actively drive in the β direction. Therefore, when a parallel link mechanism as shown in FIG. 2 is configured by combining three drive units, driving in the X and Y directions is performed by combining a combination of displacement in the α direction in the local coordinate system of the drive unit and the β direction. It depends on the position that balances with the rigidity. Since the displacement in the α direction is obtained by the difference between the generated displacements of a pair of actuators in one drive unit, the two actuators must have a large stroke in order to obtain a large displacement in the X and Y directions. is there.

  On the other hand, in this embodiment, since the cross section of the drive unit 415 is a parallelogram, the displacement operation in three directions α, β, and γ is possible. Therefore, it is easy to take a large displacement in the X and Y directions compared to the drive unit of the third embodiment.

  FIG. 17 schematically shows a state where the cross section of the drive unit is a parallelogram. A circle (sphere) in FIG. 17 represents an elastic hinge part. FIG. 17A shows the cases of the first to third embodiments, and the direction change links, that is, 315c and 315d in the third embodiment are arranged vertically. On the other hand, FIG. 17B shows the case of this embodiment, in which the links between the elastic hinges, that is, 415c and 415d are inclined from the vertical. The inclination angle is φ from the vertical axis as shown in the AA cross-sectional view of FIG. As the inclination φ increases, that is, as the distance from the vertical increases, the movable range in the X and Y directions becomes larger.

  When three parallel drive mechanisms of this embodiment are combined as shown in FIG. 2 to form a parallel link mechanism as schematically shown in FIG. 17B, the upper part is tilted toward the center of the movable part. It is good to use in combination.

  The processing method of the central portion 420 is substantially the same as the embodiment described on the left, but the hole processing for forming the elastic hinge is preferably formed substantially vertically from the inclined side surface. The state of the cross section of the hole is shown in FIG. Although machining may be performed perpendicular to the α-γ plane, stress is likely to concentrate at the end of the elastic hinge during operation, which is not a good idea.

  The optical element driving apparatus using the driving unit described in the present embodiment has an advantage that the movable range in the XY direction can be relatively large. However, the optical element driving apparatus can be moved even when translationally driven only in the Z direction. It is an operation method that easily applies torque to the part. As a result, surface deformation of the optical element 103 is likely to occur. Therefore, the projection optical system may be configured by appropriately combining with the driving devices of other embodiments according to the optical sensitivity and the direction in which the optical element 103 is to be operated.

  In the first to fourth embodiments, the laminated piezoelectric actuator has been described as an example of the linear actuator. However, a linear motion mechanism combining a rotary motor and a ball screw or a linear motion mechanism using a fluid cylinder may be used. In addition, it may be a self-holding drive unit such as a New Focus Picomotor.

  Further, as an optical element to be driven, a mirror for an EUV exposure apparatus has been described as an example, but other optical elements such as a lens, a parallel plate glass, a prism, and a diffractive optical element may be used.

  Furthermore, the drive device of the present invention can be used for applications such as a three-dimensional measuring instrument, a machine tool work, a precision moving table, a microscope sample stage, and the like to scan a movable part on six axes in addition to the adjustment of the optical element as described above. Can also be used.

  According to the driving devices of Embodiments 1 to 4, it is possible to configure a thin driving device that can operate in the direction of six degrees of freedom without having a large thickness. In particular, when applied to an optical system composed of a plurality of optical elements, an optical system having a large number of drive mechanisms can be realized because of a thin mechanism, and high imaging adjustment performance can be provided. Alternatively, the space of the optical system can be saved, so that the temperature control device can be easily mounted, and the function and performance of the entire optical system can be improved.

  Next, with reference to FIGS. 18 and 19, an embodiment of a device manufacturing method using an exposure apparatus capable of adjusting the driving of an optical element by the driving apparatus of the present invention will be described.

  18 is a flowchart for explaining how to fabricate devices (ie, semiconductor chips such as IC and LSI, LCDs, CCDs, and the like). Here, a semiconductor chip manufacturing method will be described as an example.

  First, in step S1 (circuit design), a semiconductor device circuit is designed. In step S2 (mask production), a mask is produced based on the designed circuit pattern. In step S3 (wafer manufacture), a wafer is manufactured using a material such as silicon. Step S4 (wafer process) is referred to as a pre-process, and an actual circuit is formed on the wafer using the reticle and the wafer by using the lithography apparatus using the lithography apparatus. Step S5 (assembly) is called a post-process, and is a process for forming a semiconductor chip using the wafer manufactured in step S4. The assembly process includes an assembly process (dicing, bonding), a packaging process (chip encapsulation), and the like. including. In step S6 (inspection), inspections such as an operation check test and a durability test of the semiconductor device manufactured in step S5 are performed. Through these steps, the semiconductor device is completed and shipped (step S7).

  FIG. 19 is a detailed flowchart of the wafer process in Step 4.

  In step S11 (oxidation), the surface of the wafer is oxidized. In step S12 (CVD), an insulating film is formed on the surface of the wafer. In step S13 (electrode formation), an electrode is formed on the wafer. In step S14 (ion implantation), ions are implanted into the wafer. In step S15 (resist process), a photosensitive agent is applied to the wafer. In step S16 (exposure), the exposure apparatus exposes the circuit pattern of the reticle on the wafer. In step S17 (development), the exposed wafer is developed. In step S18 (etching), portions other than the developed resist image are removed. In step S19 (resist stripping), the resist that has become unnecessary after the etching is removed.

  By repeatedly performing these steps, multiple circuit patterns are formed on the wafer. According to the device manufacturing method of the present embodiment, it is possible to manufacture a device with higher reliability by utilizing high-precision exposure performance based on the application of the driving apparatus of the present invention.

It is a schematic block diagram of exposure apparatus. 3 is an explanatory diagram of a driving device for an optical element according to Embodiment 1. FIG. It is sectional drawing explaining the attachment relationship of a drive unit and an optical element support frame. It is a figure which shows the relationship between arrangement | positioning of a drive unit, and the gravity center of a movable part. It is a figure which shows the example of the connection state of a drive unit and an optical element support frame. It is an expansion | deployment perspective view of a holding mechanism. FIG. 3 is a structural diagram of a drive unit according to the first embodiment. FIG. 3 is an operation principle diagram of the drive unit according to the first embodiment. It is a control block diagram of a drive device. FIG. 6 is a structural diagram of a drive unit according to a second embodiment. FIG. 10 is an operation principle diagram of the drive unit according to the second embodiment. FIG. 6 is a partially enlarged view of a drive unit according to Embodiment 2. FIG. 6 is a structural diagram of a drive unit according to a third embodiment. FIG. 6 is a partially enlarged cross-sectional view of a drive unit according to a third embodiment. FIG. 10 is an operation principle diagram of the drive unit according to the third embodiment. FIG. 6 is a structural diagram of a drive unit according to a fourth embodiment. It is a figure which shows the outline | summary at the time of applying the drive unit of Example 4 to an optical element. It is a flowchart for demonstrating a device manufacturing method. It is a detailed flowchart of the wafer process of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Projection optical system 2 Lens-barrel base plate 3 Base frame 4 Anti-vibration mechanism 5 Reticle 8 Wafer 9 Wafer stage 10 Optical element control means 103 Optical element 112a, 112b Piezo actuator 115a, 115b Horizontal link 115c, 115d Direction change link 115g Optical element Frame drive link

Claims (6)

A drive device having three drive units each including a pair of linear actuators and capable of driving an optical element in six axial directions with respect to a fixed barrel , wherein the drive unit has a pair of linear actuators on the same axis together are arranged to transmit opposite to the driving force in a direction along the, have a link mechanism for transmitting a driving force in a direction different from the driving direction by the pair of linear actuators between the pair of linear actuators Further, the driving apparatus further comprises a member connected to the outer end of the pair of linear actuators and fixed to the fixed barrel only at a central portion located below the link mechanism .   2. The drive according to claim 1, wherein the link mechanism includes a pair of linear motion guide links corresponding to the respective linear actuators, and a direction changing link provided between the pair of linear motion guide link mechanisms. apparatus. Wherein a position detection unit for detecting an attitude of the optical element, according to claim 1 or 2, characterized in that to control the attitude of the optical element by the three drive units in accordance with a detection result of the position detection unit Drive device. A drive device having three drive units each including a pair of linear actuators and capable of driving an optical element in six axial directions with respect to a fixed barrel , wherein the drive unit has a pair of linear actuators on the same axis together are arranged to transmit opposite to the driving force in a direction along the, have a link mechanism for transmitting a driving force in a direction different from the driving direction by the pair of linear actuators between the pair of linear actuators And a member connected to the outer ends of the pair of linear actuators, the member being fixed to the fixed barrel at a central portion located below the link mechanism and on both sides of the central portion. The driving device is fixed to the fixed barrel through an elastic hinge . An exposure apparatus for transferring a pattern formed on a reticle onto a wafer, comprising: an optical system comprising the optical element, wherein the optical element is driven by the driving device according to claim 1. apparatus. 6. A device comprising: applying a resist to a wafer; exposing the wafer to a pattern formed on a mask using the exposure apparatus according to claim 5; and developing the exposed wafer. Manufacturing method.

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