Abstract:
A light processing apparatus irradiates an ultra violet light through a square or a rectangular light transmitting window onto a work piece that has a square or rectangular pattern formation portion. The apparatus includes a light emitting unit that comprises a casing, an ultraviolet irradiance lamp arranged inside the casing and the light transmitting window member provided in one face of the casing. One side of the light transmitting window and one side of the pattern formation portion are not parallel to each other.

Description:
CROSS-REFERENCES TO RELATED APPLICATION 
     This application claims priority from Japanese Patent Application Serial No. 2011-069688 filed Mar. 28, 2011, the contents of which are incorporated herein by reference in their entirety. 
     TECHNICAL FIELD 
     The present invention relates to a light processing apparatus and, more particularly, to a light processing apparatus for performing dry cleaning processing of a surface of a template in a nanoimprinting apparatus. 
     BACKGROUND 
     In the field of manufacture of a semiconductor chip or a biochip, optical nanoimprint technology has attracted attention. This is because it is possible to manufacture those chips at low cost by such optical nanoimprinting, compared with a pattern formation method using a conventional photo lithography and etching. For example, Japanese Patent Application Publication No. 2000-194142 discloses such a method. 
     Although, in such optical nanoimprinting, a template is used to form a pattern on a workpiece to be processed, the template has to be frequently cleaned. This is because, in such nanoimprinting, the template is brought into direct contact with a resist, so that remnants of the resist adhere to the template every time a pattern is formed. 
     A wet cleaning method using an organic solvent or alkali chemical has been adopted as such a cleaning method of the template. However, in such a wet cleaning method, part of the template dissolves with the organic solvent, chemical, or the like, so that there is a possibility that the pattern shape thereof may change. 
     SUMMARY 
     The present invention relates to a light processing apparatus that includes a light emitting unit comprising a casing, an ultraviolet light irradiating lamp arranged in the casing and a square or rectangular light transmitting window. The lamp is configured to irradiate from the light emitting unit an ultraviolet light onto a work piece having an approximately rectangular (square or rectangular) pattern formation portion. The square or rectangular light transmitting window is provided in a face of the casing. One side of the window is configured not to be in parallel or perpendicular with one side of the pattern formation portion. 
     Further, the light transmitting window member and the approximately rectangular pattern formation portion may be squares, respectively. The one side of the window and one side of the pattern formation portion may intersect each other at 45 degrees. 
     A central line extending in a longitudinal direction of the lamp and the one side of the pattern formation portion may intersect each other. The work piece may be a template for nanoimprinting. 
     Furthermore, the ultraviolet irradiance lamp may be an excimer lamp having a pair of electrodes provided on an outer face of the excimer lamp. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWING 
       Other features and advantages of the present light processing apparatus will be apparent from the ensuing description, taken in conjunction with the accompanying drawings, in which: 
         FIG. 1  shows a light processing apparatus; 
         FIG. 2  shows a light processing apparatus; 
         FIG. 3  shows an ultraviolet ray radiation lamp; 
         FIGS. 4A-4B  show the arrangement relation between the window member  11  and the workpiece W (pattern formation portion) respectively; 
         FIGS. 5A-5B  show the arrangement relation between the window member  11  and the workpiece W (pattern formation portion) respectively; 
         FIGS. 6A-6B  show the arrangement relation between the window member  11  and the workpiece W (pattern formation portion) respectively; 
         FIGS. 7A-7B  show the arrangement relation between the window member  11  and the workpiece W (pattern formation portion) respectively; 
         FIGS. 8A and 8B  show the structure of an apparatus which serves as a base for the present invention; and 
         FIG. 9  shows irradiance distribution on a window member in the apparatus structure. 
     
    
    
     DESCRIPTION 
     The present invention relates to a novel apparatus in which a template is not damaged in cleaning of a nanoimprint template. 
     A subject matter of the present invention will be described in more detail below.  FIGS. 8A and 8B  show an apparatus (paper or document thereabout has not been published).  FIG. 8A  is a top plan view of the structure of the apparatus, and  FIG. 8B  shows the structure of the inside of the apparatus. An ultraviolet ray radiation lamp  11  (hereinafter referred to as a “lamp”) is arranged inside a casing  10 . A window member  12  is formed by attaching a light transmitting member such as silica glass to (an opening of) one face of the casing  10 . A workpieces W, such as, a nanoimprint template is held right above the window member  12  by a holding member, which is not shown in the figures. The workpiece W is, for example, square in shape and similarly the window member  12  is also square in shape. As shown in  FIG. 8A , when the workpiece W and the window member  12 , which are stacked, are viewed, the workpiece W and the window member  12  are positioned so that any one side of the workpiece W does not intersect with any one side of the window member  12 . That is, the diagonal lines of the work piece W and the window member  12  are overlap each other. 
     Ultraviolet rays emitted towards the workpiece W from the window member  12  vary in illuminance such that, the rays closer to the center of the window member  12  and that of the workpiece W have a higher illuminance, and the rays closer to the circumference thereof possess a lower illuminance.  FIG. 9  shows the radiation illumination of the ultraviolet rays on the window member  12 , where H represents an area where the illuminance is high, M represents an area where the illumination is a medium degree, and L represents an area where the illuminance is low. In addition, in the figure, although the window member is divided into nine regions and classified by these three levels, in fact, illuminance measurements gradually toward the circumference. The reason why the illuminance is higher closer to the center and the illuminance is lower closer to the circumference, is that, as shown in  FIG. 8B , the window member  12  is irradiated with the radiation light rays L 11 , L 12 , and L 13  from a position P 1  on a lamp surface which is located almost right under the central point of the window member  12 . On the other hand, as shown in the figure, the window member  12  is irradiated with the radiation light L 21 , L 22 , L 31 , and L 32  respectively from a position P 2  and a position P 3 , which are on the lamp surface located almost right under the circumference of the window member  12 . For this reason, it is understood that radiation light received from the lamp  11  is lower as the circumference of the window member  12  I approached. 
     Of course, if the casing  10  is designed to be sufficiently large with respect to the workpiece W, that is, the light source lamp  11  or the window member  12  is designed to be larger than the size of the workpiece W, then the varying illuminance may be accounted for. However, since miniaturization is required in this kind of apparatus, it is improper to implement a case that is larger in size than needed. Similarly, the height of the casing  10  must be kept low, since the length of the radiation face and the window member  12  of the lamp  11  are in fact also low (for example, 30 mm). 
     Therefore, in view of such circumstances, the present invention relates to effectively use radiation light emitted from a window member  12 , where a light source  11  and the window member  12  are configured as small as possible with respect to the size of a work piece W. 
     Detailed description of a light processing apparatus according to the present invention will be given below. 
       FIG. 1  is a schematic view of a light source unit of the light processing apparatus.  FIG. 2  is an explanatory cross sectional view of the light source unit. The light source unit  20  is used to clean, with light, a surface of a template (workpiece W), for example, in a nanoimprinting apparatus. The shape of entirety of the light source unit  20  is determined according to the casing  10 , whose shape is approximately rectangular parallelepiped. A lamp housing chamber  21  and a power source housing chamber  22  are provided inside the casing  10  to be aligned through a dividing wall  23 . 
     The window member  12 , which is made of quartz glass, is fixed to part of a wall portion of the lamp housing chamber  21  of the casing  10  by a frame member  13 . An ultraviolet ray radiation lamp  11  (hereinafter merely referred to as a “lamp”) is arranged in the lamp housing chamber  21 . A boosting transformer  24  for supplying electric power to the lamp  11  is arranged in the power source housing chamber  22 . In addition, it is desirable that ultraviolet rays, especially vacuum ultraviolet rays, be emitted from the lamp  11 . Therefore, an excimer lamp, that encloses xenon gas, is suitable for the lamp  11 . In the case of such an excimer lamp, which requires high voltage, it is desirable in general that only the transformer  24  be installed near the lamp and that an inverter circuit and the like be separated from the lamp. In this embodiment, the inverter circuit is arranged outside the casing  10 . 
       FIG. 3  shows an ultraviolet ray radiation lamp. Further,  FIG. 3  shows an example of the ultraviolet ray radiation lamp  11  (i.e. an excimer lamp). The excimer lamp  11  has an electric discharge container  30 , which has a flat shape as a whole, where an electrical discharge space is formed inside the electric discharge container. Mouthpieces  31  are provided at both ends of the electric discharge container  30 , respectively. A pair of net shape electrodes  32  is formed on an outer face of the electric discharge container  30  by, for example, screen printing. The electric discharge container  30  is made of material, for example, quartz glass, which suitably transmits ultraviolet rays. In the electric discharge container  30 , material, for example, rare gas (such as xenon, argon, krypton, or the like) or halogen gas (such as bromine, chlorine, iodine, or the like) in addition to the rare gas, which emits ultraviolet rays due to dielectric barrier discharge, is enclosed inside the electric discharge container  30 . When xenon is used as the enclosed gas, the typical emission wavelength is 172 nm. When argon and iodine are used as the enclosed gas, the typical emission wavelength is 191 nm. When argon and fluorine are used as the enclosed gas, the typical emission wavelength is 193 nm. The enclosure pressure of the gas is 10−100 kPa. 
     In addition, the light source unit  10  is used for cleaning the template of a nanoimprinting apparatus. The structure of such apparatus is disclosed in Japanese Patent Application Serial No. 2010-16127 filed by the present assignee. 
     Next, description of arrangement relation between a window member  11  and a workpiece W will be given below.  FIGS. 4A-7B  show the arrangement relation between the window member  11  and the workpiece W (pattern formation portion) respectively.  FIGS. 4A ,  5 A,  6 A and  7 A respectively show a conventional arrangement structure;  FIGS. 4B ,  5 B,  6 B and  7 B respectively show an arrangement structure according to the present invention. 
     In  FIGS. 4A and 4B , the window member  12  is a square and the workpiece W are square, where their relation is such that one of sides of the workpiece W and one of sides of the window member  12  are neither parallel nor perpendicular to each other so that they cross each other. In this arrangement, it turns out that portions (L regions) of the workpiece W receiving less ultraviolet ray radiation from the window member  12  become, as a whole, small. Especially, when both members are squares, if any one side of the workpiece W intersects any one of the sides of the window member  12  at 45 degrees, the usage efficiency of radiation amount can be raised by the simplest structure. 
     In  FIGS. 5A and 5B , the window member  12  is a rectangle and the workpiece W is a square. In  FIGS. 6A and 6B , the window member  12  is a square and the workpiece W is a rectangle. In  FIGS. 7A and 7B , the window member  12  and the workpiece W are rectangles. Any of those cases are similar to the case of  FIGS. 4A and 4B . That is, if any one of the sides of the workpiece W and any one of the sides of the window member  12  are neither parallel nor perpendicular to each other so they intersect, an area arranged in an L region of the workpiece W becomes small, so that the usage efficiency of radiation amount is raised. However, where either the window member  12  or the workpiece W is a rectangle does not mean that 45 degrees is optimal, is the optimal angle is decided according to the aspect ratio of the rectangle. 
     In addition, in the present invention, the rectangle (a square, a rectangle) means the shape of the pattern formation portion of the workpiece W. That is, for example, in case where there is a frame surrounding the pattern formation portion, the shape of the workpiece W excluding the frame surrounding the pattern formation portion is a rectangle. The present invention is based on the premise that the center of the window member  12  and that of the workpiece W overlap each other. 
     Also, in the present invention, various modifications and changes may be made. For example, the number of the ultraviolet ray radiation lamp is not limited to one, and two or more lamps may be arranged to form a light source unit. Moreover, the ultraviolet ray radiation lamp is not limited to such an excimer lamp, and a low pressure mercury lamp, an ultraviolet ray radiation LED, or the like may be used. 
     The preceding description has been presented only to illustrate and describe exemplary embodiments of the present light processing apparatus. It is not intended to be exhaustive or to limit the invention to any precise form disclosed. It will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the claims. 
     The invention may be practiced otherwise than is specifically explained and illustrated without departing from its spirit or scope.