Abstract:
According to an aspect of the present invention, an imprinting apparatus is provided with: a mount to support a subject body; a movable body capable of moving away from and close to the mount; a support swingably attached to the movable body; a template being attached to the support and including an imprinting face, the imprinting face being patterned to make an impression on the subject body; and a regulator intervening between the movable body and the support and including at least three actuators, the actuators being independently controllably driven so as to regulate an orientation of the imprinting face.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]     This application is based upon and claims the benefit of priority from the prior Japanese Patent Application No. 2005-051757 (filed Feb. 25, 2005); the entire contents of which are incorporated herein by reference.  
       BACKGROUND OF THE INVENTION  
       [0002]     1. Field of the Invention  
         [0003]     The present invention relates to an imprinting apparatus for imprint of a pattern from a template to a subject body and, in particular, to an imprinting apparatus for imprint of a pattern from a template to a subject body with high accuracy in parallelism between the template and the subject body.  
         [0004]     2. Description of the Related Art  
         [0005]     An art named “nano-imprinting” for forming a nano-sized fine pattern on a resist has been under development in recent years. In the art, a negative pattern as a complement of a desired pattern on the resist is incised on a quartz substrate by an electron beam writing method with nano-sized fineness, which serves as a template (or, a stamper). Next the template is pressed on the resist with a predetermined pressure so as to imprint a positive pattern on the resist. Thereby a desired nano-sized pattern can be formed on the resist. An art of nano-imprinting is disclosed in an article of “Precision Engineering Journal of the International Societies for Precision Engineering and Nanotechnology, 25 (2001) 192-199”.  
         [0006]     In the aforementioned step of imprinting, it is important for precise formation of the pattern on the resist to closely and uniformly press the template on the resist. Precise regulation in parallelism between the template and the resist is required. For close and uniform pressing, the above article discloses a flexible support which is flexible enough to passively regulate a orientation of the template when the template is pressed to a subject body. However, the flexible support is inapplicable to a case where a pressure to press the template is relatively great, because the flexible support is made so flexible.  
         [0007]     Any imprinting apparatus, which is capable of imprinting with a relatively great pressure, is desired.  
       SUMMARY OF THE INVENTION  
       [0008]     According to a first aspect of the present invention, an imprinting apparatus is provided with: a mount to support a subject body; a movable body capable of moving away from and close to the mount; a support swingably attached to the movable body; a template being attached to the support and including an imprinting face, the imprinting face being patterned to make an impression on the subject body; and a regulator intervening between the movable body and the support and including at least three actuators, the actuators being independently controllably driven so as to regulate an orientation of the imprinting face.  
         [0009]     According to a second aspect of the present invention, an imprinting apparatus is provided with: a mount to support a subject body; a support to support a template configured to imprint a pattern on the subject body, the support defining an axis and being controllably movable toward the mount along the axis and swingable around the axis; and three or more regulation sets attached to the support and arranged around the axis at intervals, each of the regulation set including an actuator in contact with the support so as to swing the support and a distance measurement device configured to measure a distance to the subject body, the actuator and the distance measurement device being opposed to each other with respect to the axis. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0010]      FIG. 1  is an explanatory drawing schematically illustrating an imprinting apparatus in accordance with a first embodiment of the present invention;  
         [0011]      FIG. 2  is an explanatory drawing illustrating a relation between actuators and distance measurement devices of the imprinting apparatus;  
         [0012]      FIG. 3  is a graph illustrating a property of the distance measurement device;  
         [0013]      FIG. 4  is an explanatory drawing illustrating measurement by the distance measurement devices;  
         [0014]      FIG. 5  is an explanatory drawing illustrating a relation between a measured value and a compensated value;  
         [0015]      FIG. 6  is an explanatory drawing illustrating an arrangement of the actuators; and  
         [0016]      FIG. 7  is an explanatory drawing illustrating an imprinting apparatus in accordance with a second embodiment of the present invention. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0017]     Reference is now made to  FIG. 1 . An imprinting apparatus  1  in accordance with a first embodiment of the present invention is provided with a frame  3  for construction of the whole of the apparatus. The frame  3  is further provided with an upper frame  5 , a lower frame  7  and plural (typically four) guide rods  9 . The guide rods  9 , which also serve as tie rods, stand vertical and parallel with each other. The upper frame  5  and the lower frame  7  are fixed to each other in a unitary body by the parallel guide rods  9 . A movable table  11  is attached on the lower frame  7  and is smoothly controllably movable in directions perpendicular to the guide rods, namely in horizontal directions. A supporting mount  15  for supporting a subject body  13  is attached on the movable table  11 .  
         [0018]     A so-called X-Y table is preferably applied to the movable table  11 , which is provided with X and Y tables respectively movable in X and Y directions perpendicular to each other and X and Y servomotors respectively controllably driving the X and Y tables. The X and Y tables are layered with each other so that the movable table  11  is controllably movable in any horizontal directions. Since the X-Y table is publicly known, more detailed description will not be given to the movable table  11 . The subject body  13  is a plate provided composed of a substrate of a proper material such as silicon, glass or any ceramics and a resist of a thermoplastic resin having a thickness of from several tens nm to several μm coated on the substrate. The supporting mount  15  is provided with heating means  17  for heating and hence softening the resist, such as a heater.  
         [0019]     A movable body  19  is provided so as to span the guide rods  9  and face the support mount  15 . Proper bushings such as ball bushings intervene between the movable body  19  and the guide rods  9  for enabling movement of the movable body  19  along the guide rods  9 . Thereby the movable body  19  is capable of moving away from and close to the supporting mount  15 , like as a ram in a press machine. The frame  3  is provided with a pair of linear guides  21  in parallel with the guide rods  9 . A pair of sliders  23  slidably move along the linear guides  21  and are attached to the movable body  19  for guiding the movement of the movable body  19 .  
         [0020]     More specifically, as the imprinting apparatus  1  is provided with the vertically movable sliders  23  and the parallel plural guide rods  9 , the movable body  19  is prevented from moving in the horizontal direction and swinging and enabled to move in the vertical direction with accuracy and keeping the horizontal.  
         [0021]     The upper frame  5  is provided with a drive mechanism for driving the movable body  19  in the vertical direction. Hydraulic mechanisms such as a hydraulic cylinder, crank mechanisms and link mechanism are exemplified as preferable examples for the drive mechanism, however, any mechanism enabling controllable, accurate and reciprocal drive may be applied to the drive mechanism of the present embodiment. For convenience of explanation, a ball screw mechanism is exemplified as the drive mechanism to describe the present embodiment.  
         [0022]     More specifically, the ball screw mechanism  25  is attached to the upper frame  5  so that a drive rod  27  of the ball screw mechanism  25  is linked with the movable body  19 . By rotating a drive nut or a drive screw of the ball screw mechanism  25 , the drive rod  27  ascends or descends so as to controllably drive the movable body  19 . Meanwhile, whether the drive nut or the drive screw is rotated depends on a constitution of the ball screw mechanism  25  and has no significance for the present invention.  
         [0023]     A follower wheel  29  is drivingly attached to the drive nut or the drive screw of the ball screw mechanism  25 . The follower wheel  29  is linked with a drive wheel  35  driven by a servomotor  33  via a timing belt  37 , which are supported by the upper frame  5  via a bracket  31 . More specifically, the servomotor  33  drives the ball screw mechanism  25  via the wheels  29  and  35 , the timing belt  37  and such. Alternatively, it may be modified so that the servomotor  33  directly drives the ball screw mechanism  25  without any transfer members.  
         [0024]     Therefore, by rotating the servomotor  33  in the regular or reverse direction under control of a controller  39 , the movable body  19  vertically controllably descends or ascends along the guide rods  9  and the linear guides  21 . A vertical position of the movable body  19  may be detected by detection means (not shown). As examples of the detection means, a rotary detector such as a rotary encoder for detecting a rotational position of the servomotor  33  or a linear scale provided parallel to the linear guide  21  for directly detecting the vertical position may be exemplified.  
         [0025]     A support plate  43  to which a template  41  is attached is swingably supported by a lower face of the movable body  19 . The lower face of the movable body  19  has a spherical bearing  45  substantially at a center thereof, in a manner that an axial center of the spherical bearing  45  coincides with an axial center of the ball screw mechanism  25 . The spherical bearing  45  allows swingable support of the support plate  43 . The spherical bearing  45  may be configured to have a general constitution and assures small frictional drag and extremely small play.  
         [0026]     The template  41  is made of silicon, glass or any ceramics for example and has a fine pattern for being imprinted on a subject body. The pattern is formed by, for example, an electron beam writing method with nano-sized fineness.  
         [0027]     At a time of imprinting the pattern on the subject body  13  from the template  41 , a deflection angle of the support plate  43  is regulated so as to regulate parallelism between the patterned face of the template  41  and a surface of the subject body  13 . For this regulation, three or more actuators  47 A,  47 B and  47 C are provided between the movable body  19  and the support plate  43 . The actuators  47 A,  47 B and  47 C are respectively provided with plural accumulated piezoelectric elements (electrostrictive elements) or magnetostrictive elements. By applying respectively controlled voltages, the actuators  47 A,  47 B and  47 C respectively make controlled small deformations. The actuators  47 A,  47 B and  47 C are disposed at even intervals along a circle centered around the center of the spherical bearing  45  as shown in  FIG. 2 .  
         [0028]     The small deformations of the actuators  47 A,  47 B and  47 C controlled by the respectively applied voltages lead to deflection of the support plate  43  centered around the center of the spherical bearing  45 . Therefore, by proper regulating the deformations of the actuators  47 A,  47 B and  47 C with the applied voltages, the orientation of the support plate  43  is properly regulated so as to regulate the parallelism between the patterned face of the template  41  and the surface of the subject body  13 .  
         [0029]     For regulation of the parallelism, distance measurement devices  49 A,  49 B and  49 C are respectively arranged correspondently to and faced to the actuators  47 A,  47 B and  47 C. More specifically, the actuators  47 A,  47 B and  47 C and the distance measurement devices  49 A,  49 B and  49 C are respectively provided as pairs, each of which serves as a regulation set for regulation of the orientation of the support plate  43 . The distance measurement devices  49 A,  49 B and  49 C are respectively configured to measure distances from the devices itself to the surface of the subject body  13 . To the distance measurement devices, for example, reverberatory CCD displacement sensors with high resolution may be preferably applied.  
         [0030]     The CCD displacement sensor detects a displacement distance from a particular point as a measurement center LO and outputs the measured distance as an analog signal, which is in linear relation to the measured distance within a limited range as shown in  FIG. 3 . A commercially available sensor in the trade name of “Z300-S10” (OMRON corporation) may be preferably applied thereto. As this CCD displacement sensor is capable of detecting displacement with a resolution of 1 μm, a distance between a particular point on the surface of the subject body  13  and the patterned face of the template  41  can be measured with a solution of 1 μm by this sensor.  
         [0031]     The distance measurement devices  49 A,  49 B and  49 C are respectively so arranged as to determine compensation quantities required to regulate the actuators  47 A,  47 B and  47 C. In a simplest arrangement, the distance measurement devices may be respectively aligned with the actuators. However, to avoid dimensional interaction between the distance measurement devices and the actuators, the distance measurement devices could be deviated from such aligned positions. In accordance with the present embodiment, the actuators  47 A,  47 B and  47 C and the distance measurement devices  49 A,  49 B and  49 C are arranged as illustrated in  FIG. 2 . As in the plan view, each of the distance measurement devices  49 A,  49 B and  49 C is disposed on a straight line passing through a center of the correspondent actuator  47 A,  47 B or  47 C and the center of the spherical bearing  45  and opposite to the correspondent actuator  47 A,  47 B or  47 C with respect to the center of the spherical bearing  45 . The disposition of the distance measurement devices  49 A,  49 B and  49 C is not necessarily required to be accurate and they may be deviated therefrom to some extent.  
         [0032]     More specifically, each of the distance measurement devices  49 A,  49 B and  49 C is on a region opposite to the correspondent actuator  47 A,  47 B or  47 C with respect to a line perpendicular to the center of swinging movement of the support plate  43 , namely the center of the spherical bearing  45 .  
         [0033]     When distances from the devices  49 A,  49 B and  49 C to correspondent points on the surface of the subject body  13  are measured by means of the distance measurement devices  49 A,  49 B and  49 C, voltages for displacement command to regulate the actuators  47 A,  47 B and  47 C are respectively applied thereto, thereby deformations of the actuators  47 A,  47 B and  47 C are regulated in fine tune. Consequently, an orientation of the patterned face of the template  41  is regulated so that parallelism between the patterned face of the template  41  and the surface of the subject body  13  is regulated in fine tune.  
         [0034]     At a time of carrying out the distance measurement, distances are measured with respect to the measurement center L 0 . Therefore, provided that values of the distances to the surface of the subject body  13  measured by the distance measurement devices  49 A,  49 B and  49 C are respectively L 1 , L 2  and L 3  (see  FIG. 4 ), compensation quantities required to regulate parallelism at the points, where the distance measurement devices  49 A,  49 B and  49 C are disposed, are respectively obtained as these differences from the measurement center L 0 , namely (L 1 -L 0 ), (L 2 -L 0 ) and (L 3 -L 0 ).  
         [0035]     The above compensation quantities should be converted to those at points where the actuators  47 A,  47 B and  47 C are disposed because the distance measurement devices  49 A,  49 B and  49 C are respectively deviated from the actuators  47 A,  47 B and  47 C. Extension of the actuators  47 A,  47 B and  47 C leads to decrease in distances from correspondent points on the patterned face of the template  41  to the surface of the subject body  13 . Accordingly, since each of the distance measurement devices  49 A,  49 B and  49 C is arranged opposite to the correspondent actuator  47 A,  47 B or  47 C with respect to the center of the spherical bearing  45  as mentioned above, extension of the actuators  47 A,  47 B and  47 C leads to increase in distances from correspondent distance measurement devices  49 A,  49 B and  49 C to the surface of the subject body  13 . This situation is illustrated in  FIG. 5 . The compensation quantities  11 ,  12  and  13  required to regulate parallelism at the points, where the actuators  47 A,  47 B and  47 C are disposed, are respectively converted by the following manner.  
         [0036]     For convenience of conversion calculation, the following description will be given on the assumption that the upper surface of the support plate  43  and the rotational center of the spherical bearing  45  are in the same plane at an initial state of not applying any voltage to the actuators. Further an X-Y-Z spatial coordinate system with its origin at the rotational center of the spherical bearing  45 , as shown in  FIG. 6 , is supposed. Meanwhile, points P 1 , P 2  and P 3  represent contact points between the actuators  47 A,  47 B and  47 C and the support plate  43 . A pitch circle of the points P 1 , P 2  and P 3  has a radius R.  
         [0037]     Given that voltages applied to the actuators  47 A,  47 B and  47 C respectively yield displacements L 1 , A 2  and A 3  thereof, respective coordinates P 1 , P 2  and P 3  of tip ends thereof in the X-Y-Z coordinate system are; 
 
 P 1=(− R, 0,Δ1) 
 
 P 2=( R/ 2,√{square root over (3)}/2 R,Δ 2) 
 
 P 3=( R/ 2,−√{square root over (3)}/2 R,Δ 3) 
 
 Planes centered on an origin O are generally represented by an equation of; 
 
 ax+by+cz= 0 
 
 Because the tip ends are in the plane, the following equations can be obtained; 
 
− aR+cΔ 1=0  (2) 
 
 aR/ 2+ b √{square root over (3)}/2× R+cΔ 2=0  (3) 
 
 aR/ 2− b √{square root over (3)}/2× R+cΔ 3=0  (4) 
 
 When assigning the equation (2) to the equations (3) and (4); 
 
 cΔ 1/2+ b √{square root over (3)}/2× R+cΔ 2=0  (5) 
 
 cΔ 1/2− b √{square root over (3)}/2× R+cΔ 3=0  (6) 
 
 By adding the equation (5) to the equation (6); 
 
 c (Δ1+Δ2+Δ3)=0  (7) 
 
 Therefore, Δ 1 , Δ 2  and Δ 3  must satisfy the following condition; 
 
Δ1+Δ2+Δ3=0  (8) 
 
 Supposing that the required quantities l 1 , l 2  and l 3  given from the condition of the distance measurement devices  49 A,  49 B and  49 C added to an offset Δ are respectively equal to Δ 1 , Δ 2  and Δ 3 , the following equations are obtained;  
                       Δ   ⁢           ⁢   1     =       l   1     +   Δ                   Δ   ⁢           ⁢   2     =       l   2     +   Δ                   Δ   ⁢           ⁢   3     =       l   3     +   Δ             }           (   9   )             
 
 By assigning the equations (9) to the equation (8), l 1 +l 2 +l 3 3Δ=0 and hence;  
             Δ   =     -         l   1     +     l   2     +     l   3       3               (   10   )             
 
 Therefore, the displacements Δ 1 , Δ 2  and Δ 3  which should be given to the respective actuators  47 A,  47 B and  47 C are obtained as;  
                       Δ   ⁢           ⁢   1     =         2   ⁢     l   1       -     l   2     -     l   3       3                   Δ   ⁢           ⁢   2     =     -         -     l   1       +     2   ⁢     l   2       -     l   3       3                     Δ   ⁢           ⁢   3     =         -     l   1       -     l   2     +     2   ⁢     l   3         3             }           (   11   )             
 
 When voltages in proportion to these values are applied to the respective actuators  47 A,  47 B and  47 C, the template  41  is properly oriented so as to regulate the parallelism. 
 
         [0038]     The controller  39  carries out the aforementioned calculations.  
         [0039]     Regulation of the parallelism is carried out as follows. The servomotor  33  drives the movable body  19  to descend under control of the controller  39  so that the measurement centers L 0  of the distance measurement devices  49 A,  49 B and  49 C are substantially correspondent with the upper surface of the subject body  13 . Subsequently, distances to the upper surface of the subject body  13  are respectively measured by the distance measurement devices  49 A,  49 B and  49 C and the measured values L 1 , L 2  and L 3  are input to the controller  39 . Then, the required voltages V 1 , V 2  and V 3  are calculated therefrom as mentioned above and applied to the actuators  47 A,  47 B and  47 C. Thereby the support plate  43  are controllably oriented so as to regulate the parallelism between the patterned face of the template  41  and the upper surface of the subject body  13 .  
         [0040]     After regulation of the parallelism as described above, with keeping the orientation of the template  41  in this state, the template  41  is pressed onto a resist on the upper surface of the subject body  13 . The resist is preferably heated to soften by means of the heating means  17  in advance. Subsequently, the subject body  13  is cooled so as to harden the resist and then the template  41  is separated from the subject body  13 . Thereby a fine pattern is imprinted from the patterned face of the template  41  onto the subject body  13  as an impression thereof.  
         [0041]     The controller  39  is preferably provided with storage means for memory of the measured values L 1 , L 2  and L 3  and the compensation voltages V 1 , V 2  and V 3 . When the controller  39  comes to be re-active, the orientation of the template  41  can be restored from the stored data. Thereby imprinting by the template  41  can be repeatably and stably carried out in the consistent condition until the template  41  is exchanged.  
         [0042]     Meanwhile, the aforementioned description was given to a case where the thermoplastic resist on the subject body  13  is heated to soften and then imprinting is accomplished. However, the present invention may be applied to a case where an ultraviolet curing resist is used. In this case, it is preferred that the template  41  is constituted transparent and a light source  51  is attached to the support plate  43 . Alternatively, a light source  51  and an optical guide-way to conduct light of the light source are preferably provided in combination.  
         [0043]     In stead of the CCD displacement sensors as described above, laser displacement sensors, LED displacement sensors, ultrasonic sensors or contact displacement sensors for example may be applied to the distance measurement devices  47 A,  47 B and  47 C. Moreover, the above description was given to the upright imprinting apparatus, however, the imprinting apparatus may be constituted and used as a horizontal apparatus.  
         [0044]     As being understood from the above description, the imprinting apparatus in accordance with the present embodiment of the present invention is capable of closely and uniformly pressing the template onto the subject body. Since the apparatus is free from a flexible support, relatively large pressure can be applied to imprinting though precision is not degraded. Moreover, precise imprinting can be carried out independent of the material quality of the subject body and whether it is soft or hard.  
         [0045]     Additional advantages and modifications will readily occur to those skilled in the art. Therefore, the invention in its broader aspects is not limited to the specific details and representative embodiments shown and described herein. Accordingly, various modifications may be made without departing from the spirit or scope of the general inventive concept as defined by the appended claims and their equivalents.