Abstract:
A device  1  is disclosed for inspecting, measuring defined structures, simulating structures and structural defects, repair of and to structures, and post-inspecting defined object sites on a microscopic component  2  with an immersion objective  8   a . The device  1  comprises a stage that is movable in the x-coordinate direction and in the y-coordinate direction and a holder  42  for the microscopic component  2 , whereby the holder  42  is placed on the stage  4  with the microscopic component  2  in it. The holder  42  has a reservoir  51   a  with immersion or cleaning fluid, respectively. The stage  4  is movable such that the immersion objective  8   a  is located directly above the reservoir  51   a  and may dip into the fluid with its front-most lens.

Description:
RELATED APPLICATIONS 
       [0001]    This application is a National Stage application of PCT application serial number PCT/EP2005/053212 filed on Jul. 5, 2005, which in turn claims priority to German application serial number 10 2004 033 195 filed on Jul. 9, 2004. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The invention relates to a device for inspecting a microscopic component. In particular, the invention relates to a device for inspecting a microscopic component with a stage for the microscopic component, at least one objective that is implemented as an immersion objective, and which defines an imaging beam path. 
       BACKGROUND OF THE INVENTION 
       [0003]    The term inspection is understood here as meaning all activities that can occur in the context of the control of microscopic components. These include, for example, in addition to pure inspection, measurement of defined structures, simulation of structures and structural errors, repair of and to structures, and post-inspection of defined object positions. A person skilled in the art refers to this process as review. 
         [0004]    European patent application 1 420 302 A1 discloses a lithography device and a method for producing a component using the lithography device. An immersion objective is used to increase resolution, and the immersion fluid is applied to the surface of the substrate to be structured. The entire table with the substrate to be structured is covered with a fluid. To avoid turbulence in the fluid, a transparent pan is dipped in the fluid. The pan is provided with the same fluid in which the imaging objective is dipped. This device is not suitable for inspecting masks, wafers, or components of a similar type. 
         [0005]    The publication of US patent application 2004075895 discloses a device and a method for immersion lithography. The wafer to be structured is covered completely with a fluid. There is a small space between the imaging optic and the wafer such that only a small quantity of fluid is present therein. The fluid is constantly pumped, filtered, and also replenished. 
         [0006]    None of the devices according to the state of the art suggest using an immersion objective or applying the immersion fluid directly to the microscopic component to be inspected (mask, wafer, micromechanical component). 
       SUMMARY OF THE INVENTION 
       [0007]    The object of the present invention is therefore to increase the resolution of the inspection device, while simultaneously avoiding contamination of the components to be inspected. 
         [0008]    According to the invention, this object is solved by a device for inspecting with the characteristics in claim  1 . 
         [0009]    It is of advantage if the device for inspecting a microscopic component has at least one objective that is implemented as an immersion objective. Furthermore, the device is provided with a device for applying a small dosed quantity of fluid to the surface of the microscopic component. Likewise, a device for suctioning the small quantity of fluid is positioned above the surface of the microscopic component, whereby the device at least partially surrounds the immersion objective, or whereby it is arranged in the vicinity of the objective. The small quantity of fluid is a drop of fluid that represents the immersion fluid. It is particularly advantageous to use water as the immersion fluid. Highly purified water is recommended as the immersion fluid for a number of applications. Consequently, the immersion objective is a water immersion objective. The device may also be operated with other immersion fluids that are described in the literature. 
         [0010]    In order to achieve high resolution, a portion of the light for inspecting with an immersion objective should have a wavelength of 248 nm or shorter (e.g., 193 nm). The several objectives may be mounted to a turret. Likewise, a fixed arrangement of two or several objects to each other is also conceivable, whereby one objective is the immersion objective, and the other(s) is/are used for alignment and other inspectional tasks using visible light. 
         [0011]    The arrangement of the device for suctioning a small quantity of fluid is provided with a multiplicity of suction nozzles on the surface of the opposite side of the microscopic component. The suctioning nozzles comprise an edge and a suction channel, whereby the edge is at a controlled distance of less than 300 μm from the surface of the microscopic component. Furthermore, the device has for the purpose of suctioning a prominence on the side that is opposite the surface of the microscopic component, on which the suction nozzles are arranged such that the individual suction nozzles jut out over the prominence. The prominence is implemented in the present embodiment. For the suction device to function, it is simply required that the nozzles themselves be elevated. 
         [0012]    Further advantages and advantageous embodiments of the invention are the subject of the following figures and their descriptions. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0013]    The object of the invention is schematically represented in the diagram and is described on the basis of the figures below. They show: 
           [0014]    FIG.  1 —a schematic design of the device for inspecting and/or measuring, simulating, and repairing a microscopic component; 
           [0015]    FIG.  2 —a schematic view of several objectives are arranged on a turret and their allocation to the microscopic component to be inspected; 
           [0016]    FIG.  3 —a schematic view of an immersion objective in the working position; 
           [0017]    FIG.  4 —a schematic view of the method of the device for suctioning to enable shifting of the immersion objective from the working position; 
           [0018]    FIG.  5 —a further schematic representation of an embodiment of the suction device; 
           [0019]    FIG.  6 —a schematic representation of an embodiment of the invention from  FIG. 6  along the A-A line of intersection; 
           [0020]    FIG.  7 —a bottom view of the device for inspecting a microscopic component, whereby the area around the suction device is represented; 
           [0021]    FIG.  8 —a bottom view of the device for inspecting a microscopic component, whereby the area around the suction device is represented and other elements from the area around the objective are extended; 
           [0022]    FIG.  9 —a detailed perspective view of the area around the objective and the microscopic component; 
           [0023]    FIG.  10 —a schematic representation of a further embodiment of the device for inspecting and/or measuring a microscopic component, whereby two objectives that are fixedly arranged in relation to each other are provided; 
           [0024]    FIG.  11 —a perspective top view of an embodiment of the device for suctioning the small quantities of fluid; 
           [0025]    FIG.  12 —a perspective bottom view of an embodiment of the device for suctioning the small quantities of fluid; 
           [0026]    FIG.  13 —a bottom view of the embodiment in  FIG. 11 ; 
           [0027]    FIG.  14 —a lateral view of the embodiment in  FIG. 11 ; 
           [0028]    FIG.  15 —a sectional view along the line B-B in  FIG. 13 ; 
           [0029]    FIG.  16 —a schematic view of the arrangement of the suction nozzles; 
           [0030]    FIG.  17 —a further schematic view of the arrangement of the suction nozzles; 
           [0031]    FIG.  18 —a schematic view of the switching the various segments of the U-shaped suction device; 
           [0032]    FIG.  19 —an embodiment of the segmentation of a square device for suctioning; and 
           [0033]    FIG.  20 —a further embodiment of the segmentation of a ring shaped device for suctioning. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0034]      FIG. 1  shows a schematic design of a device  1  for inspecting a microscopic component  2 . A stage  4  that is implemented as a scanning table is provided for the microscopic component  2  on the basic frame  3 . The stage  4  is movable in an x-coordinate direction and in a y-coordinate direction. The microscopic component  2  to be inspected is placed on the stage  4 . The microscopic component  2  may be held in an additional holder  6  on the stage  4 . The microscopic component  2  is a wafer, a mask, several micromechanical components on a substrate, or a component of related type. At least one objective  8 , which defines an imaging beam path  10 , is provided for imaging the microscopic component  2 . The stage  4  and the additional holder  6  are implemented such that they are suitable both for incident light illumination and also for transmitted light illumination. For this purpose, the stage  4  and the additional holder  6  are implemented with a recess (not depicted) for passage of an illumination light path  12 . The illumination light path  12  exits from a light source  20 . A beam splitter  13  that couples or outcouples an auxiliary beam for focusing  14  is provided in the imaging beam path  10 . The focal position of the microscopic component is determined or measured, as the case may be, by a detection unit  15  with which the distance between the surface of the microscopic component to the objective and the devices for applying and removing the immersion fluid may be controlled. A CCD camera  16  is provided behind the beam splitter  13  in the imaging beam path  10 , with which the image of the site on the microscopic component  2  that is to be inspected can be recorded or imaged. The CCD camera  16  is connected to a monitor  17  and a computer  18 . The computer  18  serves to control the device  1  for inspecting, for processing the image data that has been captured, and for storing the pertinent data, as well as for controlling the application and suctioning of immersion fluid. In the embodiment of the invention represented here, several objectives  8  on a turret (not depicted) are provided such that a user may select various enlargements. System automation is achieved using the computer  18 . In particular, the computer serves to control the stage  4 , to read out the CCD camera  16 , to apply a small quantity of fluid to the microscopic component  2 , and to drive the monitor  17 . The stage  4  is movable in an x-coordinate direction and a y-coordinate direction; the X-coordinate direction and a y-coordinate direction are perpendicular to each other. In this manner, each site on the microscopic component  2  that is to be inspected may be introduced into the imaging beam path  10 . The device  1  for inspecting a microscopic component  2  further comprises a device  21  for applying a small quantity of fluid to the microscopic component  2 . A nozzle  22  is provided to apply the small quantity of fluid, and which may be moved in an appropriate manner to precisely the site where the small quantity of fluid is to be applied. 
         [0035]      FIG. 2  shows a schematic view of several objectives  8  that are mounted to a turret  25 . The objectives  8  may be moved into the imaging beam path  10 , depending on the desired method of inspection. One of the several objectives  8  on the turret is an immersion objective  8   a ; in addition, there is a dry objective  8   b  (not an immersion objective) and an alignment objective  8   c . A turret  25 , which holds the various objectives  8 , is mounted above the microscopic component  2  to be inspected. In the diagram represented here, the immersion objective  8   a  is in the working position and is provided opposite the surface  2   a  of the microscopic component  2 . In addition, a device  21  for applying a small dosed quantity of fluid to the surface  2   a  of the microscopic component  2  is allocated to the immersion objective  8   a . In addition, a device  23  is mounted for suctioning the small quantity of fluid above the surface  2   a  of the microscopic component  2 . The device  21  for applying the fluid is arranged closer to the immersion objective  8   a  than is the suctioning device  23 . In the embodiment of the invention represented here, the suctioning device  23  is implemented such that it at least partially surrounds the immersion objective  8   a.    
         [0036]      FIG. 3  shows a schematic view of the immersion objective  8   a  in the working position. A small quantity of fluid  26  is applied between the immersion objective  8   a  and the surface  2   a  of the microscopic component  2 . In the process, the small quantity of fluid  26  completely wets the front-most lens  27  of the immersion objective  8   a.    
         [0037]      FIG. 4  shows a schematic view of the method of the suction device  23  in order to enable shifting of the immersion objective  8   a  from the working position. A device  23  for suctioning the small quantities of fluid are provided opposite the surface  2   a  of the microscopic component  2 . As previously detailed, the suction device  23  partially surrounds the objective  8   a . Embodiments are also feasible in which only one suction device is arranged next to the objective. In order to enable shifting of the objective, the suction device  23  must be moved out of the area of linear or pivoting movement of the objective. The suction device  23  is moved as indicated by an arrow  30  in  FIG. 4 . The suction device  23  is no longer in the area of the objective, as is evident from the bottom diagram in  FIG. 4 . 
         [0038]      FIG. 5  shows a further schematic representation of an embodiment of the suction device  23 . Here, the immersion objective  8   a  is completely surrounded by the suction device  23 . The suction device  23  is implemented in the shape of a ring. It will be obvious to a person skilled in the art that the suction device  23  may assume any closed or open shape in order to at least partially surrounds the immersion object  8   a . Within the suction device  23 , a device  24  for applying a small quantity of fluid to the microscopic component  2  is also provided. 
         [0039]      FIG. 6  is a schematic representation of the embodiment in  FIG. 5  along the A-A line of intersection. The immersion objective  8   a  is arranged opposite the surface  2   a  of the microscopic component  2 . A small quantity of fluid  26  is applied between the front-most lens  27  of the immersion objective  8   a  and the surface  2   a  of the microscopic component  2 . The immersion objective  8   a  is surrounded by the suction device  23 . The suction device  23  is implemented with several openings  34  on a side  32  that is opposite the surface  2   a  of the microscopic component  2 . The fluid from the surface  2   a  of the microscopic component  2  may be suctioned off as needed through these openings  34 . The suction device  23  is connected to a negative pressure reservoir (not depicted) via a tubing  35 . The fluid is suctioned from the surface  2   a  by applying negative pressure. 
         [0040]      FIG. 7  shows a bottom view of the device for inspecting a microscopic component  2 , whereby the area around the suction device  23  is represented. The suction device  23  is allocated to the immersion objective  8   a . In the embodiment represented here, the suction device  23  is implemented in a U-shape. Although the following description is limited to a U-shaped suction device  23 , this should not be interpreted as a limitation of the invention. The suction device  23  is mounted to a carrier  28 . The carrier  28  is movably implemented such that the suction device  23  may be moved out of the area of linear or pivoting movement of the objective  8   a , and the distance to the surface of the microscopic component can be controllably adjusted. Furthermore, a device  21  for applying a small quantity of fluid and a cleaning device  36  are provided on the carrier  8   a . The cleaning device  36  serves to remove reliably from the objective  8   a  any fluid that still adheres to it. The application device  21  and the cleaning device  36  are positioned in the area around the immersion objective  8   a  by corresponding recesses  37  and  38  in the suction device  23 . The cleaning device  36  comprises a nozzle tip  39  with which residual fluid that adheres to the immersion objective  8   a  may be suctioned off. 
         [0041]      FIG. 8  is a bottom view of the device for inspecting a microscopic component  2 , whereby the area around the suction device  23  is represented, and further elements are extended beyond the area around the objective  8   a . As previously mentioned, the further elements are the suction device  23  and the cleaning device  36 . As previously described in  FIG. 4 , the objective can only be shifted when the cleaning device  36  is completely extended beyond the suction device  23 . The cleaning device  36  is movably implemented and is mounted for the purpose to a corresponding movable mimic  40 . 
         [0042]      FIG. 9  shows a detailed perspective view of the area around the objective  8 ,  8   a , and the microscopic component  2 . The device  21  for applying a small quantity of fluid to the microscopic component  2  and the cleaning device  36  are attached to the mimic  40 , which is movably implemented. The device  23  for suctioning small quantities of fluid is provided in the working position directly opposite the surface  2   a  of the microscopic component  2 . In the embodiment represented in  FIG. 9 , the microscopic component  2  is a mask for producing semiconductors. Here, the mask is positioned in a separate mask holder  42 . The carrier  28  is mounted via a rigid arm  43  to a lifting device  44 , which lifts the carrier  28  together with the suction device  23  from the surface  2   a  of the microscopic component  2 . The arm  43  on the lifting device  44  is movable for the purpose in the direction of two elongated holes  45 . 
         [0043]      FIG. 10  is a schematic representation of a further embodiment of the device for inspecting and/or measuring a microscopic component  2 . Here, the turret  25  is replaced by two objectives  8 ,  8   a  that are fixedly arranged in relation to each other. One of the objectives is an immersion objective  8   a  that is implemented and intended for DUV illumination (248 nm or 193 nm). The second objective  8  is an objective for visible light that can be used for alignment or other inspectional tasks. Each of the objectives is allocated at least one CCD  48 , which is used for capturing images. The microscopic component  2  in this case is a mask, the substrate of which is transparent. An illumination optic  46  is provided below the mask for illumination. 
         [0044]      FIG. 11  is a perspective top view of an embodiment of the device  23  for suctioning small quantities of fluid. The suction device  23  in this embodiment is implemented in a U-shape and comprises a first leg  51 , a second leg  52 , and a third leg  53  the suction device  23  exhibits a prominence  54  on the side opposite the microscopic component  2 , in which the suction nozzles  55  are implemented (see  FIG. 12 ). 
         [0045]      FIG. 12  is a perspective bottom view of an embodiment of the device  23  for suctioning small quantities of fluid. The prominence  54  is implemented as a continuous band along the first, second, and third legs  51 ,  52 , and  54 . The prominence bears a multiplicity of suction nozzles  55  which, in the working position of the suction device  23 , lie opposite to the surface  2   a  of the microscopic component  2 . 
         [0046]      FIG. 13  shows a bottom view of the embodiment of the suction device  23  from  FIG. 11 . As mentioned previously, the multiplicity of suction nozzles  55  is formed on the prominence  54 . The suction nozzles  55  run as a continuous band along the first, second, and third legs. The individual suction nozzles  55  are themselves elevated above the prominence  54 . Furthermore, the suction nozzles are staggered. The line B-B in  FIG. 13  illustrates the staggering of the suction nozzles  55 . 
         [0047]      FIG. 14  shows a lateral view of the embodiment of the suction device  23  from  FIG. 13 . The individual suction nozzles  55  jut above the prominence  54 . The arrangement of the individual suction nozzles  55  is staggered such that they form in projection a closed barrier to the immersion fluid to be suctioned. This ensures that no immersion fluid can pass by the suction nozzles  55 . 
         [0048]      FIG. 15  shows a sectional view of the suction device  23  along the B-B line from  FIG. 13 . The individual suction nozzles  55  of the third leg  53  are connected with a suction channel  56 . Likewise, the suction nozzles  55  of the second leg  52  are connected with a further, separate suction channel  57 . As a result of this separation of the suction channels, it is possible to pressurize the individual legs  51 ,  52 , and  53  with negative pressure. 
         [0049]      FIG. 16  is a schematic view of the embodiment of the suction nozzles  55 . The suction nozzles  55  are formed with an edge  60  that is additionally elevated above the prominence  54 . The suction channels  56 ,  57  of the suction nozzles  55  have a diameter  61  of approximately 1 mm. The edge  60  is arranged parallel to the surface  2   a  of the microscopic component  2  (mask). The edge  60  is positioned at a controlled distance of less then 300 μm from the surface  2   a.    
         [0050]      FIG. 17  shows a further schematic view of the design of the suction nozzles  55 . The suction channel  57  of the suction nozzle  55  comprises a slanted edge  63 , so that the distance of the edge  63  increases from the center of the suction channel  57  outwardly in a continuous manner from the surface  2   a  of the microscopic component  2 . This design serves, in particular, to draw immersion fluid by means of capillary action in the direction of the suction channel  57  in order to achieve reliable suctioning of the immersion fluid. 
         [0051]      FIG. 18  is a schematic view of the switching of the various segments of the U-shaped suction device  23 . The first leg  51 , the second leg  52 , and the third leg  53  of the U-shaped suction device  23  are separated into discrete segments  65 . Each of the segments is provided with its own tubing  67  for applying negative pressure. Negative pressure may be applied to the corresponding segments  65  independent of the relative movement between the stage  4  (see  FIG. 1 ) and the suction device  23 . The relative movement between the stage  4  and the suction device  23  is indicated by an arrow  68  in  FIG. 18 . As a result, the first leg  51  moves toward a drop of fluid  70  such that the segment  65  of the first leg  51  must be pressurized with negative pressure. A control  71  is provided that applies negative pressure to the corresponding leg independent of the direction of movement of the suction device  23 . Optimal suctioning is achieved at each segment as a result of this circuitry. 
         [0052]      FIG. 19  shows an embodiment of the segmentation of a square suction device  23 . The individual segments  65  comprise sides  81 ,  82 ,  83 , and  84  of the square. 
         [0053]      FIG. 20  shows a further embodiment of the segmentation of a round suction device  23 . Here, the individual segments  65  are here the orthogonal sectors  91 ,  92 ,  93  and  94  of the round suction device  23 . It will be clear to a person skilled in the art that another division of the segments  65  is feasible.