Abstract:
A mask drawing method includes: disposing a grounding body provided with a grounding pin at a plurality of different places on a mask substrate to measure resistance values; disposing the grounding body at a position where the resistance value is lowest, among the plural positions where the resistance values are measured; and irradiating an electron beam to the mask substrate to draw a desired pattern.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
       [0001]    This application is based upon and claims the benefit of priority from the prior Japanese Patent Application No. 2012-148275, filed on Jul. 2, 2012; the entire contents of which are incorporated herein by reference. 
       FIELD 
       [0002]    Embodiments of the present invention relate generally to a mask drawing method and a mask drawing apparatus. 
       BACKGROUND 
       [0003]    A mask drawing apparatus is an apparatus to draw a desired pattern by irradiating an electron beam to a mask substrate (blank) comprising a substrate (mainly glass substrate) and a light shielding film (for example, chromium (Cr)) formed on the substrate. A resist film is formed on a surface of the mask substrate, and to draw the desired pattern, the resist film is exposed to the electron beam. 
         [0004]    The mask substrate is grounded at the time of the drawing by the electron beam. This is because without the mask substrate being grounded, electric charges accumulate on the mask substrate due to the electron beam to bend a trajectory of the electron beam or to cause a blur due to the diffusion of the electron beam. It is impossible to draw a desired pattern on the mask substrate when the bending of the trajectory of the electron beam or the blur of the electron beam is occurred. 
         [0005]    Because of this, in the mask drawing apparatus, at the time of the drawing by the electron beam, a grounding body is set on the mask substrate. Because the electric charges accumulating on the mask substrate due to the electron beam are discharged via the grounding body, the charging of the mask substrate can be prevented. 
         [0006]    However, it is known that an unexpected increase of a contact resistance value between the grounding body and the mask substrate (hereinafter, referred to as a resistance value) sometimes occurs. Further, when the grounding body is set on the mask substrate, the resistance value sometimes differs depending on the direction in which the grounding body is set. There are various possible factors that cause such phenomenon, and a possible factor is, for example, that the grounding body does not reach a light shielding film of the mask substrate. If the drawing by the electron beam is performed in such a case, the electric charges accumulate on the mask substrate to bend the trajectory of the electron beam or to blur the electron beam. As a result, it is impossible to draw a desired pattern on the mask substrate. Therefore, there have conventionally been proposed various methods that can reduce the resistance value between the grounding body and the mask substrate. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0007]      FIG. 1A  and  FIG. 1B  are schematic diagrams of a mask drawing apparatus according to a first embodiment. 
           [0008]      FIG. 2A  and  FIG. 2B  are schematic views of a grounding body housing chamber according to the first embodiment. 
           [0009]      FIG. 3A  and  FIG. 3B  are a side view and a plane view of a grounding body according to the first embodiment. 
           [0010]      FIG. 4  is a block diagram of a resistance measuring mechanism according to the first embodiment. 
           [0011]      FIG. 5  is table data stored in a memory according to the first embodiment. 
           [0012]      FIG. 6  is table data stored in a memory according to a modification example of the first embodiment. 
       
    
    
     DETAILED DESCRIPTION 
       [0013]    Hereinafter, embodiments will be described with reference to the drawings. 
       First Embodiment 
       [0014]      FIG. 1A  is a schematic plane diagram of a mask drawing apparatus  10 .  FIG. 1B  is a schematic sectional view of the mask drawing apparatus  10 . Hereinafter, the structure of the mask drawing apparatus  10  will be described with reference to  FIG. 1A  and  FIG. 1B . Note that an electron beam column  500  is not illustrated in  FIG. 1A . 
         [0015]    As shown in  FIG. 1A  and  FIG. 1B , the mask drawing apparatus  10  includes an interface (I/F)  100 , an input/output (I/O) chamber  200 , a robot chamber (R chamber)  300 , a writing chamber (W chamber)  400 , the electron beam column  500 , a control mechanism  600 , and gate valves G 1  to G 3 . Note that the robot chamber (R chamber)  300  constitutes a transfer chamber. Further the chain lines in  FIG. 1A  and  FIG. 1B  represent flows of control signals, data, and so on. 
         [0016]    The I/F  100  includes a mounting table  110  where to place containers C (for example, SMIFPods) each housing a mask substrate W and a transfer robot  120  which transfers the mask substrate W. 
         [0017]    The I/O chamber  200  is what is called a load lock chamber via which the mask substrate W is loaded/unloaded while an air pressure in the R chamber  300  is kept vacuum low. The I/O chamber  200  is provided with the gate valve G 1  between itself and the I/F  100  and includes a vacuum pump  210  and a gas supply system  220 . The vacuum pump  210  is, for example, a dry pump, a turbo molecular pump, or the like and it evacuates the inside of the I/O chamber  200 . The gas supply system  220  supplies vent gas (for example, nitrogen gas or clean dry air (CDA)) into the I/O chamber  200  when setting the inside of the I/O chamber  200  to an atmospheric pressure. 
         [0018]    When evacuating the inside of the I/O chamber  200 , the vacuum pump  210  connected to the I/O chamber  200  is used for the evacuation. Further, when the inside of the I/O chamber  200  is returned to the atmospheric pressure, the vent gas is supplied from the gas supply system  220  to set the inside of the I/O chamber  200  to the atmospheric pressure. Note that when the inside of the I/O chamber  200  is set to vacuum or the atmospheric pressure, the gate valves G 1 , G 2  are closed. 
         [0019]    The R chamber  300  includes a vacuum pump  310 , an alignment chamber  320 , a grounding body housing chamber  330 , and a transfer robot  340 . The R chamber  300  is connected to the I/O chamber  200  via the gate valve G 2 . 
         [0020]    The vacuum pump  310  is, for example, a Cryo pump, a turbo molecular pump, or the like. The vacuum pump  310  is connected to the R chamber  300  and evacuates the inside of the R chamber  300  to keep it highly vacuum. The alignment chamber  320  is a chamber where to align the mask substrate W. 
         [0021]    The grounding body housing chamber  330  houses a grounding body H for grounding the mask substrate W. The grounding body housing chamber  330  is provided with a resistance measuring mechanism  40  which measures a contact resistance value between the grounding body H and the mask substrate W (hereinafter, simply referred to as a resistance value) while the grounding body H is set on the mask substrate W. The resistance measuring mechanism  40  will be described later with reference to  FIG. 4 . 
         [0022]    The transfer robot  340  includes an arm  341  and an end effector  342  provided at an end of the arm  341 . The transfer robot  340  transfers the mask substrate W to/from the I/O chamber  200 , the alignment chamber  320 , the grounding body housing chamber  330 , and the W chamber  400 . 
         [0023]    The W chamber  400  includes a vacuum pump  410 , an X-Y stage  420 , drive mechanisms  430 A,  430 B and is connected to the R chamber  300  via the gate valve G 3 . 
         [0024]    The vacuum pump  410  is, for example, a Cryo pump, a turbo molecular pump, or the like. The vacuum pump  410  is connected to the W chamber  400  and evacuates the inside of the W chamber  400  to keep it highly vacuum. The X-Y stage  420  is a table where to place the mask substrate W. The drive mechanism  430 A drives the X-Y stage  420  in an X direction. The drive mechanism  430 B drives the X-Y stage  420  in a Y direction. 
         [0025]    The electron beam column  500  includes an electron beam irradiator which comprising an electron gun  510 , apertures  520 , deflectors  530 , lenses  540  (condenser lens (CL), shaping lens (SL), objective lens (OL)), and so on. And the electron beam column  500  irradiates the electron beam to the mask substrate W placed on the X-Y stage  420 . 
         [0026]    The control mechanism  600  is, for example, a computer or the like and includes a MPU  601 , a memory  602  (for example, solid state drive (SSD), hard disk drive (HDD)), and so on. The control mechanism  600  controls the operation of the mask drawing apparatus  10 . 
       (Structure of Grounding Body H) 
       [0027]      FIG. 2A  is a plane view of the grounding body H.  FIG. 2B  is a cross-sectional view taken along the L-L in  FIG. 2A . Note that  FIGS. 2A and 2B  show the grounding body H set on the mask substrate W. 
         [0028]    As shown in  FIG. 2A  and  FIG. 2B , the grounding body H includes three conductive grounding pins H 1   a  to H 1   c  and a conductive frame H 2  in a frame shape. Note that the grounding pin H 1   b  or H 1   c  is provided on the frame H 2  via an insulator. Further, the mask substrate W has a structure in which a light shielding film Wb (for example, chromium (Cr)) and a resist film Wc are stacked on a glass substrate Wa. 
         [0029]    When the grounding body H is set on the mask substrate W, the grounding pins H 1   a  to H 1   c  of the grounding body H pierce through the resist film Wc due to their own weights to come into contact with the light shielding film Wb being a conductor. Consequently, the electric charges accumulating on the mask substrate W due to the irradiation of the electron beam are discharged via the grounding body H. 
       (Structure of Grounding Body Housing Chamber  330 ) 
       [0030]      FIG. 3A  is a side view of the grounding body housing chamber  330 .  FIG. 3B  is a plane view of the grounding body housing chamber  330 . Hereinafter, the structure of the grounding body housing chamber  330  will be described with reference to  FIG. 3A  and  FIG. 3B . 
         [0031]    As shown in  FIG. 3A , inside of the grounding body housing chamber  330 , a mounting shelf  20  where to place the grounding body H and a rotating mechanism  30  which rotates the mask substrate W are provided. 
         [0032]    The rotating mechanism  30  includes a mounting table  31  where to place the mask substrate W and a rotating shaft  32  having one end connected to the mounting table  31 . In the mounting table  31 , escape grooves  33  allowing the end effector  342  of the transfer robot  340  to escape thereto are provided in four directions. Further, the rotating shaft  32  has another end connected to a not-shown motor and is structured to be capable of rotating the mounting table  31  by 90° at a time. 
         [0033]      FIG. 4  is a block diagram of the resistance measuring mechanism  40 . As shown in  FIG. 4 , the resistance measuring mechanism  40  includes a DC power source  41  disposed outside the grounding body housing chamber  330  and a controller  42  connected to the DC power source  41 . The controller  42  includes a current control circuit  42   a , a voltage measuring circuit  42   b , and a resistance value calculating circuit  42   c  and it measures an electric resistance between terminals  40   a ,  40   b . The terminals  40   a ,  40   b  are provided in the grounding body housing chamber  330  and are connectable with the aforesaid grounding pins H 1   b , H 1   c  of the grounding body H. 
         [0034]    The resistance measuring mechanism  40  measures the contact resistance (resistance value) between the grounding body H and the mask substrate W while the grounding body H is set on the mask substrate W. Concretely, while the grounding body H is set on the mask substrate W, the current control circuit  42   a  supplies a current with a predetermined value between the terminals  40   a ,  40   b , and the voltage measuring circuit  42   b  measures a voltage between the terminals  40   a ,  40   b . Then, the resistance value calculating circuit  42   c  calculates the resistance value between the terminals  40   a ,  40   b  from the value of the current flowing between the terminals  40   a ,  40   b  and the measured voltage value. Note that when the resistance value is measured, the terminals  40   a ,  40   b  of the resistance measuring mechanism  40  and the grounding pins H 1   b , Inc of the grounding body H are in a connected state. 
         [0035]    As described above, the grounding pin H 1   b  or H 1   c  is provided on the frame H 2  via the insulator. Accordingly, the current applied by the current control circuit  42   a  flows between the terminals  40   a ,  40   b  via the grounding pins H 1   b , H 1   c  and the light shielding film Wb of the mask substrate W. Here, connection resistance values between the terminals  40   a ,  40   b  and the grounding pins H 1   b , H 1  are very small and almost negligible. Therefore, it is possible to measure the resistance value between the grounding pins H 1   b , H 1   c , concretely between the grounding pins H 1   b , H 1   c  and the light shielding film Wb of the mask substrate W. 
       (Operation of Mask Drawing Apparatus  10 ) 
       [0036]    Next, the operation of the mask drawing apparatus  10  will be described. Note that the operation of the mask drawing apparatus  10  described below is controlled by the control mechanism  600 . 
         [0037]    First, the container C housing the mask substrate W is placed on the mounting table  110 . The transfer robot  120  takes out the mask substrate W from the container C. Next, the I/O chamber  200  is set to an atmospheric pressure and the gate valve G 1  is opened. 
         [0038]    After placing the mask substrate W in the I/O chamber  200 , the transfer robot  120  retracts from the inside of the I/O chamber  200 . Next, the gate valve G 1  is closed. After the inside of the I/O chamber  200  is evacuated to a predetermined pressure, the gate valve G 2  is opened. Next, the transfer robot  340  takes out the mask substrate W from the inside of the I/O chamber  200 . Thereafter, the gate valve G 2  is closed. 
         [0039]    Next, the transfer robot  340  sets the grounding body H, which is placed on the mounting shelf  20  of the grounding body housing chamber  330 , on the mask substrate W. The resistance measuring mechanism  40  of the grounding body housing chamber  330  measures the resistance value between the grounding body H and the mask substrate W. The control mechanism  600  stores, in the memory  602 , the resistance value measured by the resistance measuring mechanism  40 . Next, the transfer robot  340  returns the grounding body H to the mounting shelf  20  and places the mask substrate W on the mounting table  31  of the rotating mechanism  30 . 
         [0040]    Next, the rotating shaft  32  rotates by 90° to change the direction of the mask substrate W, which is placed on the mounting table  31 , by 90°. The transfer robot  340  lifts up the mask substrate W on the mounting table  31  whose direction has been changed by 90° and sets the grounding body H on the mask substrate W. The resistance measuring mechanism  40  of the grounding body housing chamber  330  measures the resistance value between the grounding body H and the mask substrate W. The control mechanism  600  stores, in the memory  602 , the resistance value measured by the resistance measuring mechanism  40 . 
         [0041]    The resistance measuring mechanism  40  and the control mechanism  600  repeat the above-described operations to measure the resistance value between the grounding body H and the mask substrate W every time the direction is changed by 90° and stores, in the memory  602 , the resistance values between the grounding body H and the mask substrate W measured when the direction is 0°, 90°, 180°, 270°. Note that the direction in which the mask substrate W is rotated may either be clockwise (CW) or counter clockwise (CCW). 
         [0042]      FIG. 5  shows an example of the measurement result. Table data shown in  FIG. 5  is stored in the memory  602  of the control mechanism  600 . The control mechanism  600  refers to the table data stored in the memory  602  to rotate the mask substrate W by an angle at which the measured resistance value is low. In the example shown in  FIG. 5 , the resistance value is lowest when the angle is 90°. Therefore, the control mechanism  600  rotates the rotating mechanism  30  so that the direction of the mask substrate W becomes 90°. 
         [0043]    Next, after setting the grounding body H on the mask substrate W, the transfer robot  340  transfers the mask substrate W to the alignment chamber  320 . In the alignment chamber  320 , the mask substrate W is aligned. When the alignment is finished, the gate valve G 3  is opened, and the transfer robot  340  places the mask substrate W on the X-Y stage  420  in the R chamber  400 . After the transfer robot  340  retracts from the inside of the R chamber  400 , the gate valve G 3  is closed. 
         [0044]    The drive mechanisms  430 A,  430 B move the X-Y stage  420  to a predetermined position. Next, the electron beam is irradiated to the mask substrate W from the electron beam column  500 . 
         [0045]    The drive mechanisms  430 A,  430 B move the X-Y stage  420  in the X direction and the Y direction, and the electron beam B is irradiated to the mask substrate W except its peripheral end portion to draw a desired pattern. 
         [0046]    When the drawing on the mask substrate W is finished, the drive mechanisms  430 A,  430 B move the X-Y stage  420  to a predetermined position. Next, the gate valve G 3  is opened. The transfer robot  340  takes out the mask substrate W from the W chamber  400 . Next, the gate valve G 3  is closed. The transfer robot  340  transfers the mask substrate W into the grounding body housing chamber  330  and houses the grounding body H in the grounding body housing chamber  330  in a procedure reverse to that for setting the grounding body H on the mask substrate W. 
         [0047]    Next, the gate valve G 2  is opened, and after placing the mask substrate W in the I/O chamber  200 , the transfer robot  340  retracts from the inside of the I/O chamber  200 . Next, the gate valve G 2  is closed. After the vent gas is supplied from the gas supply system  220  to increase the pressure in the I/O chamber  200  to the atmospheric pressure, the gate valve G 1  is opened. 
         [0048]    The transfer robot  120  takes out the mask substrate W from the inside of the I/O chamber  200  and retracts from the inside of the I/O chamber  200 . Next, the gate valve G 1  is closed. Next, the transfer robot  120  houses the mask substrate W into the container C. 
         [0049]    As described above, in the first embodiment, the rotating mechanism  30  which rotates the mask substrate W is provided in the grounding body housing chamber  330 , and while the grounding body H is set on the mask substrate W, the resistance value is measured every time the direction of the mask substrate W is changed by 90°. Then, the grounding body H is set on the mask substrate W which has been rotated in the direction (to the angle) where the resistance value is lowest, and the drawing by the electron beam is performed. 
         [0050]    Therefore, it is possible to reduce the electric charges accumulating on the mask substrate W to effectively reduce the bending of the trajectory of the electron beam and the occurrence of a blur due to the diffusion of the electron beam. As a result, it is possible to more accurately draw a desired pattern on the mask substrate W. 
       Second Embodiment 
       [0051]    In a mask drawing apparatus, an unexpected increase of a resistance value between a mask substrate and a grounding body sometimes occurs. There are various possible factors that cause such phenomenon, such as that the grounding body is set on the mask substrate in an inclined state, that grounding pins of the grounding body do not reach a light shielding film without piercing through a resist layer of the mask substrate, and so on. 
         [0052]    This phenomenon is liable to occur even when the grounding body is set at the same place of the mask substrate, and therefore, the method of the first embodiment in which the resistance value is measure every time the mask substrate W is rotated by 90° and the grounding body is set on the mask substrate which has rotated to the direction (angle) where the resistance value becomes lowest has a difficulty in preventing the phenomenon. For example, a possibility that the unexpected increase of the resistance value occurs in all the four directions (0°, 90°, 180°, 270°) is very low. However, when this occurs, there is a possibility that the electric charges accumulate on the mask substrate even if the grounding body is set on the mask substrate which has been rotated to the direction where the resistance value is lowest. 
         [0053]    In a second embodiment, an embodiment will be described that the resistance value is measured a plurality of times in the same direction (angle) and a threshold value is calculated from these resistance values, then the direction for setting the grounding body on the mask substrate is decided based on the calculated threshold value. In the second embodiment which will be hereinafter described, the structure of a mask drawing apparatus is the same as the mask drawing apparatus  10  according to the first embodiment described with reference to  FIG. 1  to  FIG. 4 . Therefore, the operation of the mask drawing apparatus  10  according to the second embodiment will be described with reference to  FIG. 1  to  FIG. 4 . 
       (Operation of Mask Drawing Apparatus) 
       [0054]    Next, the operation of the mask drawing apparatus  10  will be described. Note that the operation of the mask drawing apparatus  10  described below is controlled by the control mechanism  600 . 
         [0055]    First, the container C housing the mask substrate W is placed on the mounting table  110 . The transfer robot  120  takes out the mask substrate W from the container C. Next, the I/O chamber  200  is set to an atmospheric pressure, and the gate valve G 1  is opened. 
         [0056]    After placing the mask substrate W in the I/O chamber  200 , the transfer robot  120  retracts from the inside of the I/O chamber  200 . Next, the gate valve G 1  is closed. After the inside of the I/O chamber  200  is evacuated to a predetermined pressure, the gate valve G 2  is opened. Next, the transfer robot  340  takes out the mask substrate W from the inside of the I/O chamber  200 . Thereafter, the gate valve G 2  is closed. 
         [0057]    Next, the transfer robot  340  transfers the mask substrate W into the grounding body housing chamber  330  and sets the grounding body H, which is placed on the mounting shelf  20  of the grounding body housing chamber  330 , on the mask substrate W. The resistance measuring mechanism  40  of the grounding body housing chamber  330  measures a resistance value between the grounding body H and the mask substrate W. The control mechanism  600  stores, in the memory  602 , the resistance value measured by the resistance measuring mechanism  40 . 
         [0058]    Next, the transfer robot  340  returns the grounding body H to the mounting shelf  20  and sets the grounding body H on the mask substrate W again. The resistance measuring mechanism  40  measures the resistance value between the grounding body H and the mask substrate W. That is, in this embodiment, the resistance values for the same direction are measured without the mask substrate W being rotated. The resistance measuring mechanism  40  and the control mechanism  600  perform the above-described operations a plurality of times and stores the measured resistance values in the memory  602 . 
         [0059]      FIG. 6  shows an example of the measurement result. In the memory  602  of the control mechanism  600 , table data shown in  FIG. 6  is stored. In the example shown in  FIG. 6 , the resistance value is measured five times, and the resistance values measured the second time and the fifth time unexpectedly increase to abnormal values. The control mechanism  600  refers to the table data stored in the memory  602 , and calculates an average value (threshold value) of the measured resistance values. 
         [0060]    Next, the control mechanism  600  rotates the rotating mechanism  300  by 90° to measure the resistance value. The control mechanism  600  determines whether or not the measured resistance value is a value within a predetermined range with respect to the average value (threshold value) (for example, +5% or less from the average value). 
         [0061]    Note that the number of times the resistance value is measured is preferably about five to about ten. When the number of the measurement times is less than five, the sample number (n number) is too small and accuracy of the calculated average value becomes low. On the other hand, the number of the measurement times is over ten, the light shielding film Wb of the mask substrate W is liable to be damaged by the grounding pins H 1   a  to H 1   c.    
         [0062]    When the measured resistance value is a value within the predetermined range with respect to the average value (threshold value) (for example, +5% or less from the average value), robot  340  transfers the mask substrate W to the alignment chamber  320 . In the alignment chamber  320 , the mask substrate W is aligned. 
         [0063]    On the other hand, when the measured resistance value is not within the predetermined range with respect to the calculated average value (threshold value) (for example, +5% or less from the average value), the control mechanism  600  measures the resistance value while rotating the mask substrate W by 90° each time until the resistance value becomes a value within the predetermined range with respect to the average value (threshold value (for example, +5% or less from the average value). 
         [0064]    Then, when the measured resistance value becomes a value within the predetermined range with respect to the average value (threshold value) (for example, +5% or less from the average value), the transfer robot  340  transfers the mask substrate W to the alignment chamber  320 . In the alignment chamber  320 , the mask substrate W is aligned. Note that, when none of the average values of the resistance values which are measured when the mask substrate W is set in the four directions becomes a value within the predetermined range, an error may be displayed to stop the drawing operation or to accept the handling by a user. 
         [0065]    Note that +5% or less from the average value is an example for deciding the predetermined range. If the trajectory of the electron beam does not bend or the electron beam does not diffuse, a width from the average value may be arbitrarily changed. For example, the predetermined range may be +10% or less or +3σ from the average value. Further, the direction in which the mask substrate W is rotated may be either clockwise (CW) or counter clockwise (CCW). 
         [0066]    After the alignment is finished, the gate valve G 3  is opened, and the transfer robot  340  places the mask substrate W onto the X-Y stage  420  in the W chamber  400 . After the transfer robot  340  retracts from the inside of the W chamber  400 , the gate valve G 3  is closed. 
         [0067]    The drive mechanisms  930 A,  430 B move the X-Y stage  420  to a predetermined position. Next, an electron beam is irradiated to the mask substrate W from the electron beam column  500 . The drive mechanisms  430 A,  430 B move the X-Y stage  420  in the X direction and the Y direction, and the electron beam B is irradiated to the mask substrate W except its peripheral end portion to draw a desired pattern. 
         [0068]    When the drawing on the mask substrate W is finished, the drive mechanisms  430 A,  430 B move the X-Y stage  420  to a predetermined position. Next, the gate valve G 3  is opened. The transfer robot  340  takes out the mask substrate W from the W chamber  400 . Next, the gate valve G 3  is closed. The transfer robot  340  transfers the mask substrate W into the grounding body housing chamber  330  and houses the grounding body H in the grounding body housing chamber  330  in a procedure reverse to that for setting the grounding body H on the mask substrate W. 
         [0069]    Next, the gate valve G 2  is opened, and after placing the mask substrate W in the I/O chamber  200 , the transfer robot  340  retracts from the inside of the I/O chamber  200 . Next, the gate valve G 2  is closed. The vent gas is supplied from the gas supply system  220 , and after a pressure in the I/O chamber  200  is increased up to an atmospheric pressure, the gate valve G 1  is opened. 
         [0070]    The transfer robot  120  takes out the mask substrate W from the inside of the I/O chamber  200  and retracts from the inside of the I/O chamber  200 . Next, the gate valve G 1  is closed. Next, the transfer robot  120  houses the mask substrate W in the container C. 
         [0071]    As described above, in the second embodiment, the resistance value is measured a plurality of times while the mask substrate W is set in the same direction, and the threshold value (average value) is calculated from the measured resistance values. Then, the direction of the mask substrate W is changed, and the resistance value is measured, and when the resistance value is within the predetermined range with respect to the calculated threshold value (for example, the threshold value +5% or less), the drawing on the mask substrate W is performed. 
         [0072]    Therefore, it is possible to prevent the drawing on the mask substrate W while the resistance value between the mask substrate W and the grounding body H is unexpectedly high. The other effects are the same as the effects of the mask drawing apparatus  10  according to the first embodiment. 
       (Modification Example of Second Embodiment) 
       [0073]    Incidentally, in the second embodiment, the resistance value is measured a plurality of times while the mask substrate W is set in the same direction and the threshold value (average value) is calculated from the measured resistance values, but the threshold value may be stored in the memory  602  of the control mechanism  600  in advance. 
         [0074]    A sheet resistance of the mask substrate W is desirably 30 kΩ or less. Therefore, when the measured resistance value of the mask substrate W is 30 kΩ (sheet resistance equivalent) or less, the drawing on the mask substrate W is started, and when the resistance value is over 30 kΩ (sheet resistance equivalent), the mask substrate W is rotated by 90° each time by the rotating mechanism  30 , and the resistance value of the mask substrate W is measured, and the drawing on the mask substrate W may be performed when the mask substrate W is set in the direction (angle) where the resistance value becomes 30 kΩ or less. 
         [0075]    Incidentally, there may be a case where the sheet resistance differs depending on the kind of the mask substrate W. For example, there may be a case where a thickness of the light shielding film differs depending on the kind (type) of the mask substrate W. In this case, the threshold value for each kind of the mask substrate W may be stored. 
       Other Embodiments 
       [0076]    While certain embodiments have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the inventions. Indeed, the novel embodiment described herein may be embodiment in a variety of other forms; furthermore, substitutions and changes in the form of the embodiments described herein may be made without departing from the spirit of the inventions. The accompanying claims and their equivalents are intended to cover such forms or modifications as would fall within the scope and spirit of the inventions.