Abstract:
An apparatus and method for aligning a substrate and a mask are discussed. In one aspect of the present invention, the apparatus includes a mask stage, wherein the mask stage includes a mask fixing stage configured to fixedly support a mask; a base stage supporting the mask fixing stage; and at least one guide unit disposed in the base stage, coupled to the mask fixing stage, and configured to move the mask fixing stage, so as to move the mask in a predetermined direction.

Description:
The present application claims, under 35 U.S.C. §119, the priority benefit of Korean Patent Application No. 10-2005-0022863 filed Mar. 18, 2005 in Korea, the entire contents of which are herein fully incorporated by reference. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a proximity type exposure apparatus, and particularly, to a proximity type exposure apparatus provided with a load support unit supporting a mask stage and a guide unit driving the mask stage and to a method of aligning a mask to a substrate using the proximity type exposure apparatus. 
     2. Description of the Related Art 
     A process of forming a plurality of thin films is required in a manufacturing process of a semiconductor device or a liquid crystal display (LCD) device, and the thin film forming process is performed by a common exposure technology. Here, the exposure technology is that ultraviolet rays or X-rays are radiated through a mask having a predetermined pattern to expose a photosensitive material applied on a substrate and therefore, the predetermined pattern is transferred onto the substrate. 
     As for the LCD device, the exposure technology is used in many processes such as patterning of a gate line, a data line and a unit pixel of the LCD device and forming of a color filter layer of a color filter substrate. For this reason, the technology is considered to be important since transferring of a precise pattern on the substrate is needed. 
     In general, an exposure apparatus can be categorized into a projection type exposure apparatus allowing a reduced and magnified pattern transfer and a proximity type exposure apparatus allowing pattern transfer at a 1:1 ratio by using horizontal and parallel rays of light. 
     The projection type exposure apparatus that allows exposure with a reduced pattern can be commonly used to fabricate a device that requires integration such as a semiconductor device. When the same size pattern needs to be formed on a large area, for example, for an LCD device, the proximity type exposure apparatus using a large mask is suitable. 
     The proximity type exposure apparatus needs to perform exposure on a substrate, approaching the substrate as close as possible in order to transfer a mask pattern onto the substrate completely. There is a contact type exposure apparatus that performs exposure in a state that a mask is in complete contact with the substrate. However, such an exposure apparatus may cause damage to the mask by a foreign substance on the substrate or the contact itself between the mask and the substrate. Therefore, the proximity type exposure apparatus is directed to making a mask stage close to the substrate without any contact therebetween. 
     Each of the proximity type and projection type exposure apparatuses basically includes an illumination optical system generating light for exposure, a mask stage supporting a mask having a predetermined pattern, a substrate support chuck on which a substrate onto which the pattern of the mask is transferred is mounted, and supporters equipped with the substrate support chuck. 
     Also, because it is important for the exposure apparatus to precisely transfer a pattern of a mask onto a substrate, a plurality of alignment cameras for checking locations of the mask stage and the substrate are provided for the purpose of aligning the mask stage and the substrate. The alignment camera recognizes an alignment key that may be formed on the substrate support chuck or the substrate, thereby aligning the substrate and the mask stage. 
     As an LCD device gets larger, a mask becomes larger and a mask stage that supports the mask also becomes larger. The mask is installed under the mask stage so that the mask can approach the substrate as close as possible, and the mask is fixed to the mask stage by a fixing member. 
     The proximity type exposure apparatus having the aforementioned elements according to a related art will now be described with reference to  FIG. 1 . 
     Referring to  FIG. 1 , the proximity type exposure apparatus includes an illumination optical system  101  providing light, a mask stage  105  installed under the illumination optical system  101  and supporting a mask  110 , supporters  120  supporting four corners of the mask stage  105 , an x-axis driving plate  113  and a y-axis driving plate  112  formed under the mask stage  105  and supporting a substrate  114 , a chuck  111  supporting the x-axis driving plate  113  and the y-axis driving plate  112 , and a base plate  150  constituting a base of the exposure device. 
     The illumination optical system  101  serves to transfer a mask pattern onto the substrate  114  by generating light such as ultraviolet rays or x-rays. 
     The mask stage  105  includes an upper plate  103  directly coupled with the mask  110  and a lower plate  102  supporting the upper plate  103  of the mask stage and constituting a base of the mask plate. 
     The mask stage  105  supports the mask  110  such that the upper plate  103  on which the mask is directly arranged is coupled under the lower plate  102  to allow the mask  110  to approach the substrate  114  as close as possible. Also, the lower plate  102  and the upper plate  103  of the mask stage are vacant in the middle so as to allow light proceeding from the illumination optical system  101  to pass through the mask  110  and be emitted to the substrate  114 . 
     Also, four corners of the mask stage  105  are supported by the bar-shaped mask stage supporters  120 . 
     Under the mask stage  105  the substrate  114  is arranged and the x-axis driving plate  113  and the y-axis driving plate  112  for moving the substrate  114  are installed. 
     The y-axis driving plate  112  is installed on the support chuck  111 . A predetermined rail is installed in the y-axis direction on the support chuck  111 , and the y-axis driving plate  112  is coupled to the rail, so that the substrate can be moved in the y-axis direction. Also, a predetermined rail is also installed on the y-axis driving plate  112  and the x-axis plate  113  is coupled to the rail, so that the substrate can be moved in the x-axis direction. 
     The substrate  114  is mounted on the x-axis plate  113  and is moved to a certain coordinate by the operation of the x-axis driving plate  113  and the y-axis driving plate  112 . Because the substrate  114  is greater than the mask in general, a plurality of exposure processes are performed while the substrate  114  moves. In such a manner, a mask pattern is transferred onto the entire substrate  114 . 
     It is very important for the exposure apparatus to accurately align a mask stage and a substrate because the apparatus is directed to transferring a fine mask pattern onto a substrate. Therefore, in order to precisely align the mask stage and the substrate, an alignment camera (not shown) for the alignment between the substrate and the mask stage is installed on the mask stage, and an alignment key is installed on the substrate or the x-axis driving plate. 
     The alignment camera precisely aligns the substrate and the mask stage by checking the alignment key. 
     However, because the x-axis driving plate  113  and the y-axis driving plate  112  are used to move the substrate to align the substrate and the mask stage, a limitation exists in that the mask and the substrate are not or cannot easily be aligned with precision, which is a problem since the mask and the substrate should be aligned by the unit of micrometer or smaller. 
     BRIEF DESCRIPTION OF THE INVENTION 
     Therefore, an object of the present invention is to provide a mask aligning device for precisely aligning a mask and a substrate in a proximity type exposure apparatus. 
     It is another object to provide a mask aligning device that does not cause a defective adjustment due to a load in an exposure apparatus provided with a large mask stage, by installing the mask aligning device so as not to be affected by a load of the mask stage. 
     It is another object of the present invention to provide a mask aligning device and method, which overcome the limitations and disadvantages associated with the related art. 
     To achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described herein, there is provided according to an aspect of the present invention, an exposure apparatus comprising: a mask stage including a mask fixing stage to which a mask is fixed and a base stage supporting the mask fixing stage; load support units dispersing a load of the mask fixing stage to the base stage; guide units serving precise driving of the mask fixing stage; supporters supporting the mask stage; a substrate onto which a pattern of the mask is transferred; and a driving plate moving the substrate. 
     According to one aspect of the present invention, the mask fixing stage can be installed in the middle of the base stage and is connected to the base stage by the load support units. One side of each load support unit is coupled to the mask fixing plate by a coupling member and the other side thereof is connected to the base stage, wherein a sliding member is interposed between the load support unit and the base stage so as to allow the mask fixing plate to slightly move from the base stage. 
     According to one aspect of the present invention, the base stage guide units that can slightly move the mask fixing stage are installed at at least three of four sides of the mask fixing stage to thereby slightly move the mask fixing stage in the a-axis, y-axis and θ-axis directions. 
     Therefore, in the exposure apparatus in accordance with the present invention, even if the mask fixing stage is large and heavy, the guide units can precisely move the mask fixing stage because the load support units withstand the weight of the mask fixing stage. Accordingly, the precise alignment of the mask can be achieved in the exposure apparatus that requires precise alignment between the substrate and the mask. 
     According to one aspect of the present invention, there is provided an exposure apparatus comprising a mask stage including a mask fixing stage to which a mask is fixed and a base stage supporting the mask fixing stage, at least one load support unit dispersing a load of the mask fixing stage to the base stage, at least one guide unit configured to move the mask fixing stage, at least one supporter supporting the mask stage, and at least one driving plate configured to move a substrate onto which a pattern of the mask is to be transferred. 
     According to one aspect of the present invention, there is provided an exposure apparatus comprising a mask stage including a mask fixing stage configured to fixedly support a mask, a base stage supporting the mask fixing stage, and at least one guide unit disposed in the base stage, coupled to the mask fixing stage, and configured to move the mask fixing stage, so as to move the mask in a predetermined direction. 
     According to one aspect of the present invention, there is provided a method of aligning a substrate and a mask with respect to each other using an exposure apparatus, the exposure apparatus including a mask fixing stage configured to fixedly support the mask, at least one guide unit configured to move the mask fixing stage, and at least one substrate driving member configured to move the substrate, the method comprising coarsely moving the substrate by an operation of the at least one substrate driving member to coarsely align the substrate with the mask, and finely moving the mask fixing stage by an operation of the at least one guide unit to finely align the substrate with the mask. 
     The foregoing and other objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a unit of this specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention. 
       In the drawings: 
         FIG. 1  is a front view of a general proximity type exposure apparatus; 
         FIG. 2  is a perspective view of a mask stage of a proximity type exposure apparatus in accordance with an embodiment of the present invention; 
         FIG. 3  is a plan view of the mask stage of  FIG. 2  in accordance with the present invention; 
         FIG. 4  is a perspective view that illustrates a guide unit and a load support unit in accordance with an embodiment of the present invention; and 
         FIG. 5  is a perspective view that illustrates the guide unit of  FIG. 4  in accordance with the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings. 
     A structure of a proximity type exposure apparatus in accordance with the present invention will now be described with reference to  FIG. 2 . 
       FIG. 2  is a perspective view that illustrates a mask stage  200  and a supporter  202  supporting the stage  200  of the proximity type exposure apparatus in accordance with the present invention. 
     Referring to  FIG. 2 , the mask stage  200  in accordance with the present invention includes a rectangular base stage  201  constituting a base of the mask stage, a mask fixing stage  204  formed in the middle of the base stage  201 , to which a mask  210  with a predetermined pattern is fixed, supporters  202  connected to edges of the base stage  201  to support the base stage  201 , load support units  206  withstanding a load of the mask fixing stage  204  and connecting the mask fixing stage  204  with the base stage  201 , and a plurality of guide units  205   a ,  205   b  and  205   c  moving the mask fixing stage  204  precisely. 
     The mask stage  200 , the base stage  201  and the mask fixing stage  204  have a generally rectangular shape but can be in other shapes. Also, the supporter  202  for supporting the mask stage  200  is installed at four corners of the base stage  201 . 
     The supporter  202  may be four columns respectively formed at the four corners of the base stage  201  and can extend in a longitudinal direction so as to control the height of the mask stage  200 . The supporter  202  is connected to a base plate constituting a bottom of the exposure apparatus. 
     The base stage  201  has a vacant space in its middle area for installation of the mask fixing stage  204 , and the mask fixing stage  204  is installed at that vacant space. The mask fixing stage  204  installed at that vacant space also has a vacant space in its middle area. The mask  210  is installed at that vacant space of the mask fixing stage  204  and therefore receives light proceeding from an illumination optical system (e.g.,  101  in  FIG. 1 ). For the base stage  201  and the mask fixing stage  204 , the vacant space can be formed in other locations, instead of the middle areas. 
     Because the exposure apparatus in accordance with an embodiment of the present invention is designed to be suitable for exposing a large LCD panel or the like, a mask should be large to expose the large LCD panel. Thusly, the mask fixing stage  204  fixing the mask also becomes large. If the large mask fixing stage  204  is formed of a metallic material, it has a very large weight which may be in unit of tons. Therefore, a member for withstanding the weight of the mask fixing stage  204  and connecting the mask fixing stage  204  with the base stage  201  is required, and a load support unit  206  is provided for this reason according to an embodiment of the present invention. 
     At least one load support unit  206  is formed at each of four sides of the mask fixing stage  204  and is coupled with the mask fixing stage  204  by any coupling member, e.g., a bolt  230  in  FIG. 4 . Also, the other end of the load support unit  206  is connected to the base stage  201  with ball bearing(s) interposed therebetween (i.e., between the base stage  201  and the load support unit  206 ), so that the load support unit  206  can slightly move on the base stage  201 . Namely, the bearing support unit is in direct contact with the ball bearing(s) formed on the base stage  201  and can slightly move on the ball bearing(s). The construction of the load support unit  206  will be described later in more detail. 
     An important technical structure of the exposure apparatus is aligning the mask and the substrate for the exposure. As a result, for example, a plurality of alignment keys are provided on the substrate to be exposed or on a substrate driving plate in order to align the substrate and the mask fixed on the mask stage, and a detecting camera that can detect the alignment keys is provided on the mask stage. Also, because the mask stage is fixed to the base plate by the supporter, a substrate driving system for moving the substrate for the alignment between the mask and the substrate is required. 
     As a member for supporting and driving the substrate, the present invention provides substrate driving plates in addition to the guide units  205   a - 205   c . These substrate driving plates are formed under the mask stage  200  and include an x-axis driving plate that can move the substrate in the x-axis direction and a y-axis driving plate that can move the substrate in the y-axis direction. These x-axis and y-axis driving plates can be the same as or similar to those of the related art, e.g.,  112  and  113  in  FIG. 1 . 
     One of the x-axis driving plate and the y-axis driving plate is coupled with a rail formed on the base plate to move in the x-axis or y-axis direction. 
     Also, for example, if the x-axis driving plate is formed on the base plate, the y-axis driving plate is formed on the x-axis driving plate to move the substrate in the y-axis direction. Thusly, the substrate can move to a predetermined position by the operation of the x-axis driving plate and the y-axis driving plate. Because the substrate is larger than the mask in general, the substrate is moved to be entirely exposed. 
     Therefore, the present invention provides the guide units  205   a - 205   c  that can very precisely control a movement of a mask separately from the movement of the substrate (which is controlled by the substrate driving plates) when the mask and the substrate are aligned. 
     The guide unit serves to provide the precise alignment of a mask by controlling the movement of the mask fixing stage  204  directly coupled with the mask. 
     In order to align the mask and the substrate with precision, the mask should be moved in the x-axis, y-axis and  0 -axis directions. In the present invention, at least three guide units  205   a ,  205   b  and  205   c  are provided at at least three of the four sides of the mask fixing stage  204  so as to move the mask  210  in the x-axis, y-axis and/or θ-axis directions. 
     The guide units  205   a ,  205   b  and  205   c  serve to move the mask fixing stage  204 , and include an x-axis driving guide unit  205   a , a y-axis driving guide unit  205   b  and a θ-axis driving guide unit  205   c . The x-axis driving guide unit  205   a  moves the mask fixing stage  204  in the x-axis direction, the y-axis driving guide  205   b  moves the mask fixing stage  204  in the y-axis direction, and the θ-axis driving guide unit  205   c  allows the mask fixing stage  204  to rotate in the θ-axis direction, namely in the direction of rotation about the z-axis, by combining with the x-axis and y-axis driving guide units  205   a  and  205   b.    
     Therefore, in aligning the mask and the substrate in the exposure apparatus in accordance with the present invention, the substrate and the mask are aligned coarsely by the x-axis and y-axis driving plates (substrate driving plates), and then, the mask fixing stage is precisely or finely moved further by using the guide units  205   a - 205   c , thereby precisely aligning the mask and the substrate. 
     Here, the guide units  205   a ,  205   b  and  205   c  are spaced apart from the mask fixing stage  204  at a predetermined interval (gap) therebetween so as not to be affected by the load of the mask fixing stage  204 . This is because, if the guide units  205   a - 205   c  are installed right under the mask fixing stage  204 , the guide units  205   a - 205   c  can be greatly affected by the large load of the mask fixing stage  204  and consequently, it can become difficult to control the mask fixing stage  204  precisely. A connection member such a leaf spring is installed at the gap to connect the mask fixing stage  204  with the corresponding guide unit. 
     Therefore, the exposure apparatus in accordance with the present invention withstands the load of the mask fixing stage  204  by the load support units  206  and thusly supports the mask fixing stage  204 . Also, each load support unit  206  is connected with the base stage  201  by a ball bearing or other connectors so as to allow the free movement of the mask stage  200  within a predetermined range when the mask fixing stage  204  is slightly moved by the guide unit(s)  206 . 
     A plane structure of the mask stage  200  according to an embodiment of the present invention will now be described in more detail with reference to  FIG. 3 . 
     Referring to  FIG. 3 , the mask stage  200  includes a rectangular mask stage  200  constituting a base of the mask stage, and a mask fixing stage  204  installed in the middle of the base stage  201  and having a rectangular shape. 
     The base stage  201  is vacant in the middle so that the mask fixing stage  204  can be installed thereto. The mask fixing stage  204  is installed at that vacant space. The mask stage  200 , if used to expose a large LCD panel, can have a large size reaching, e.g., several meters widthwise and lengthwise and can be very heavy, and the mask fixing stage  204  also has a very large weight because it is made of a metallic material such as aluminum alloy. 
     In order to support the heavy mask fixing stage  204 , the present invention specially provides one or more load support units  206  that withstand the mask fixing stage  204 . 
     The load support units  206  may be respectively installed at four coroners or corner area of the rectangular mask fixing stage  204 , connect the mask fixing stage  204  with the base stage  201  and disperse a load of the mask fixing stage  204  to the base stage  201 . Other locations for the load support units  206  are possible. 
     One side of the load support unit(s)  206  is coupled with the mask fixing stage  204  by a fixing member such as a bolt or the like, and the other side thereof is connected to the base stage  201  with a ball bearing or the like interposed therebetween. Namely, because a plurality of ball bearings are installed at an upper end of the base stage  201  where the load support unit  206  and the base stage  201  are connected, the load support units  206  can move on the base stage  201  within a certain range, which consequently allows the mask fixing stage  204  (fixed to the load support units  206 ) to move on the mask stage  200  within a predetermined range. 
     One load support unit  206  may be formed at each of the four corners of the mask fixing stage  204 , but any number of load support units  206  may be installed at each corner or other location of the mask fixing stage  204 . 
     A plurality of guide units  205  are installed on the base stage  201  as a driving member that moves the rectangular mask fixing stage  204 . In order to install each of the guide units  205 , a portion of an upper side of the base stage  201  is cut and forms a recess. Namely, each of the guide units  205  is installed in the corresponding recess portion of the base stage  201  so that an upper surface of the guide unit may be on the same plane/level with an upper surface of the mask fixing stage  204 . 
     At least three guide units  205  may be respectively installed at three sides or locations of the rectangular mask fixing stage  204  and allow the mask fixing stage  204  to move with precision in the x-axis, y-axis and θ-axis directions, respectively. Namely, the x-axis guide unit  205   a  is operated to move the mask fixing stage  204  in the x-axis direction within a predetermined range, the y-axis guide unit  205   b  is operated to move the mask fixing stage  204  in the y-axis direction, and the x-axis, y-axis and θ-axis guide units  205   a - 205   c  are simultaneously operated to move the mask fixing stage  204  in the θ-axis direction. A power transfer unit of the guide unit  205  is connected to the mask fixing stage  204  by a connection member such as a leaf spring. 
     The mask fixing stage  204  is vacant in the middle. A mask such as  210  in  FIG. 2  having a predetermined pattern is installed at that vacant space, and a pattern of the mask is transferred onto the substrate below by light proceeding from the illumination optical system. 
     The structures of the guide units  205  and the load support units  206  in accordance with an embodiment of the present invention will now be described in more detail with reference to  FIG. 4 . 
       FIG. 4  is a view that illustrates the guide unit  205  and the load support unit  206  installed on the mask stage  200  in accordance with the present invention. 
     The load support units  206  are installed at the four corners of the mask fixing stage  204 , and the guide units  205  moving the mask fixing stage  204  are formed on the base stage  201  corresponding to at least three of the four sides of the mask fixing stage  204 . 
     As shown in  FIG. 4 , each load support unit  206  is coupled with the mask fixing stage  204  by a coupling member such as a bolt  230 , and is connected onto the base stage  201  by a sliding member of the mask fixing stage  204  such as a ball bearing  220 . 
     Each guide unit  205  transfers power linearly by, e.g., a piston movement, and allows the mask fixing stage  204  to move in the x-axis, y-axis and/or θ-axis directions. 
     A head portion of each guide unit  205  constitutes a power transfer unit transferring power to the mask fixing stage  204 , and an upper surface of the power transfer unit connects the guide unit  205  and the mask fixing stage  204  to each other by a connection member  208  such as a leaf spring. One reason for using the leaf spring as the connection member  208  is because it can transfer power of the guide unit  205  properly even when the mask fixing stage  204  is moving. Accordingly, to properly transfer the power of the guide unit  205 , an upper end of the power transfer unit is preferably on the same level with an upper surface of the mask fixing stage  204 . 
     The structure of the guide unit  205  according to an embodiment of the present invention will now be described in more detail with reference to  FIG. 5 . 
     Referring to  FIG. 5 , each guide unit  205  in accordance with the present invention includes a power generating unit  301  generating power such as a motor, a power generating unit supporter  302  supporting the power generating unit  301 , a ball screw unit  304  transferring the power of the power generating unit  301 , a ball screw supporter  303  supporting the ball screw, and a power transfer unit  305  transferring power to the mask fixing stage  204 . The ball screw unit  304  can include a shaft receiving the power. 
     The power transfer unit  305  includes a guide rail portion  310  providing a path of a horizontal movement of the power transfer unit, a sliding portion  311  moving on the guide rail portion  310  to move the power transfer unit  305 , a power transfer unit upper plate  312  installed on the sliding portion  311 , and a connection member fixing member  313  fixing the connection member  208  that connects the mask fixing stage  204  with the power transfer unit  305  in the power transfer unit upper plate  312 . 
     Thusly, the power generated from the power generating unit  301  is moved back and forth by the ball screen to move the power transfer unit  305  and thusly move the mask fixing stage  204  connected to the power transfer unit  305  by the connection member. 
     The guide units  205  are formed at at least three of the four sides of the rectangular mask fixing stage  204  and move the mask fixing stage  204  in the x-axis and y-axis directions. Also, the mask fixing stage  204  may be rotated as the operations of the three guide units are combined. 
     Also, an x-axis driving stage (plate) and a y-axis driving stage (plate) for moving the substrate to be patterned in x-axis and y-axis are provided under the mask stage in accordance with the present invention. By the driving stages, the substrate can move to a predetermined position, and the entire substrate is exposed by light irradiated through the mask stage. 
     In the exposure apparatus in accordance with the present invention, a substrate is primarily or coarsely aligned by a movement of a substrate driving stage that moves the substrate, and then a mask fixing stage is controlled and moved minutely or finely by the guide units. As a result, a precise alignment between the mask stage and the substrate is made. 
     Accordingly, the substrate and the mask stage can be precisely aligned in the exposure process that requires high precision. Also, the load support units that support the mask stage having a large weight are provided to allow the precise movement of the guide units. Accordingly, the alignment between the mask and the substrate can be controlled, more precisely in an effective manner. 
     As described so far, the exposure apparatus in accordance with the present invention is provided with the guide unit(s) that can drive the mask stage, and the load support unit(s) that withstand the weight of the mask stage. Thusly, the mask stage can be precisely aligned and therefore, the mask and the substrate can be aligned with respect to each other precisely. 
     Also, because both the substrate driving plate and the guide units driving the mask stage are provided, accurate alignment between the mask stage and the substrate is possible without delay. 
     The exposure apparatus can be applied to any substrate or layer that needs to be exposed through a mask for patterning or other purposes. For instance, the substrate can be a layer in a display device such as an LCD device. 
     As the present invention may be embodied in several forms without departing from the spirit or essential characteristics thereof, it should also be understood that the above-described embodiments are not limited by any of the details of the foregoing description, unless otherwise specified, but rather should be construed broadly within its spirit and scope as defined in the appended claims, and therefore all changes and modifications that fall within the metes and bounds of the claims, or equivalence of such metes and bounds are therefore intended to be embraced by the appended claims.