Charged particle beam exposure apparatus
This is a continuation of application Ser. No. 763,145, filed on Sep. 20, 1991, now U.S. Pat. No. 5,281,827. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a charged particle beam exposure apparatus, and particularly, to a charged particle beam exposure apparatus which is suitable for application to the manufacture of LSI&#39;s. 
     2. Description of the Related Art 
     There are two cases for the structure of a charged particle beam exposure apparatus, that is the case of integrating a main body of the apparatus (including a charged particle generator section and a sample carrier section) and a control unit for controlling these units, and the case of separating the main body of the apparatus from the control unit. In the case of separating these units, it is typical that the apparatus main body is separated from the control unit. In this case, it is necessary to have an analog signal cable wired from the control unit to the apparatus main body, with a maximum limit of about 10 m for the wiring distance between the two units. Further, in the case of integrating the apparatus main body and the control unit, an area for the installation of the apparatus is unnecessarily increased. 
     In order to minimize the necessary floor area within a clean room at the side of the user of the apparatus, it is desirable that only a portion requiring stable cleanliness, temperature and humidity the installed within the clean room. From this viewpoint, in the case of structuring the charged particle beam exposure apparatus by integrating the main body of the apparatus and the control unit, there is a problem that the floor area required for the installation of the apparatus within the clean room is unnecessarily increased. Further, in the case of separating the main body of the apparatus from the control unit to structure the charged particle beam exposure apparatus, there is a problem that the layout of the apparatus is constrained by the wiring of an analog signal cable. 
     As described above, there is a problem that constraints in the floor area and in the layout of the apparatus are imposed on the user of the apparatus, because no consideration has been given either to reduce the floor area for the installation of the apparatus in the clean room or to guarantee the layout of the apparatus with a high degree of freedom to match the idea of the configuration of the manufacturing line at the side of the user of the apparatus. 
     SUMMARY OF THE INVENTION 
     It is an object of the present invention to provide a charged particle beam exposure apparatus which is dividedly disposed within and outside the clean room so as to reduce the floor area required for the installation of the apparatus within the clean room and which is suitable for having a long distance between the portions of the divided installation of the apparatus. 
     According to one aspect of the present invention, a charged particle beam exposure apparatus is provided which comprises a main body section including means for generating a charged particle beam, means for irradiating a sample with the charged particle beam, and means for controlling both the deflection of the charged particle beam and the irradiation of the sample with the charged particle beam; means for analog controlling the deflection and irradiation control means; and means for digital controlling the analog control means, the main body section and the analog control means being disposed within a clean room of a clean room area that comprises the clean room and a space under the floor thereof and the digital control means being disposed outside the clean room. 
     According to another aspect of the present invention, a charged particle beam exposure apparatus is provided which comprises a main body section including means for generating a charged particle beam, means for irradiating a sample with the charged particle beam and means for controlling both the deflection of the charged particle beam and the irradiation of the sample with the charged particle beam; means for analog controlling the deflection and irradiation control means; and means for digital controlling the analog control means, the main body section being disposed within a clean room of a clean room area comprising the clean room and a space under the floor therefor, the analog control means being disposed in the space under the floor and the digital control means being disposed outside the clean room. 
     Other objects of the present invention and their characteristics will be clear from the following description to be made with reference to the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a block of a charged particle beam exposure apparatus showing one embodiment according to the present invention; and 
     FIG. 2 is a perspective view of the apparatus shown in FIG. 1 according to one embodiment of the present invention. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to FIG. 1, a control computer 1 supplies data and instructions to each section of the apparatus in accordance with the input of an operation and display section 2. The control computer 1 transfers drawing data to a buffer memory 4 and then starts a data control section 5 through a parallel interface 3a. The data control section 5 sequentially reads the drawing data from the buffer memory 4, breaks down the drawing data into drawing data which enables a drawing to be formed with an electron beam, and then generates digital data for deflecting and turning on and off an electron beam. The digital data is then transferred to a beam deflection control section 10. The beam deflection control section 10 generates an analog signal for beam deflection and on/off control through a digital/analog converter and an amplifier by using the digital data from the data control section 5. 
     A deflector and blanker 10&#39; for deflecting and turning on and off an electron beam within an electron beam column 18 are controlled by the signal generated by the beam deflection control section 10, and a sample wafer 24 is irradiated with the electron beam which is discharged from an electron gun applied with a high voltage by a high-voltage power source 15. 
     In the case of drawing an LSI pattern with of an electron beam, it is typical that the LSI pattern is drawn on a wafer 24 on which a drawing pattern has already been drawn. In order to accurately match and expose a predetermined position on the wafer to the electron beam, it is necessary to determine the relative positional relationship in the X, Y and Z directions between the wafer and the electron beam by accurately detecting a reference mark on the wafer and the height of the wafer before drawing the LSI pattern. The reference mark on the wafer and the height of the wafer can be detected by utilizing an electron beam and a light beam. A signal including information about these items is obtained from a detector 22, amplified by a signal detection amplifier 11, and processed to accurately extract positional information by a signal processing section 6. The information processed by the signal processing section 6 is read by the control computer 1 through the parallel interface 3a and is utilized to draw the LSI pattern by superposition. The signal processing section 6 is started by a command of the control computer 1 dispatched by the data control section 5. 
     Prior to drawing the LSI pattern, it is necessary to align the electron beam within the electron beam column 18 in the X, Y and Z directions. The data for alignment is supplied to a lens aligner control section 13 by the control computer 1 through the parallel interface 3a and a lens aligner register interface 8. Based on the alignment data, the lens aligner control section 13 generates analog data for controlling an electron lens and aligner 13&#39; within the electron beam column 18 through a digital/analog converter and an amplifier. 
     A stage 20 for holding the wafer 24 is kept in a vacuum in a sample chamber 19 and is moved together with the drawing to make it possible to draw within a range covering an area larger than an electron beam deflection range. A stage position is measured by a laser interferometer 23. The control computer 1 instructs starting of the stage 20 and reading of a laser beam from the laser interferometer 23 to a stage/laser control section 7 through the parallel interface 3a. The stage/laser control section 7 generates a stage operation pattern by referring to a stage position outputted from the laser interferometer 23. A stage servo-driver 12 generates an analog drive signal for controlling the stage 20 from the stage operation pattern generated and servo-controls the stage 20. 
     Through a serial interface 3b, the control computer 1 controls a carrier alignment mechanism section 21 such as a loader and the like for mounting and dismounting the wafer 24 to and from the stage 20, a vacuum exhaust section 17 for vacuum exhausting the electron beam column 18 and the sample chamber 19 through a vacuum valve, the high-voltage power source 15 and a temperature monitoring section 16 for monitoring the temperature of each portion of the main body. 
     Data indicating the states of various portions such as the position of the stage, a current value (a set value) of the electron lens, the current position of the wafer, the open and close state of the vacuum valve, etc., are serially transferred to the operation and display section 2 and are displayed in this section. 
     In the above configuration, as shown in FIG. 1, the control computer 1 and the operation display section 2 are provided in one operation unit 28 which can be divided, the parallel interface 3a, the serial interface 3b, the buffer memory 4, the data control section 5, the signal processing section 6, the stage/laser control section 7 and the lens aligner register interface 8 are grouped in a digital control section 9, and the beam deflection control section 10, the signal detection amplifier 11, the stage servo-driver 12, the lens aligner control section 13 and the temperature monitoring section 16 are grouped in an analog control section 14. The high-voltage power source 15 and the vacuum exhaust section 17 are associated with the main body, and the electron beam column 18, the sample chamber 19, the stage 20, the laser interferometer 23 and the carrier alignment mechanism 21 constitute a main body. 
     In this case, the control computer 1 and the digital control section 9, and the digital control section 9 and the analog control section 14, are connected with each other by a parallel or serial digital transmission path 27. Particularly, deflection data and beam blanking data are parallel transferred between the data control section 5 and the beam deflection control section 10 and a parallel transfer period can be varied in accordance with conditions for irradiating the electron beam. 
     The digital transmission path 27 is provided by the combination of a current driver and a wire cable, or an optical fiber performing optical conversion, to enable a cable wiring with a length of 50 m to 100 m. 
     An example of the configuration of an apparatus according to the present invention is shown in FIG. 2. 
     The main body section 25 is accommodated in a thermostatic chamber 26 and the analog control section 14 is disposed adjacent to the main body section. The thermostatic chamber 26 accommodating the main body section 25 and the analog control section 14 are disposed within a clean room. The digital control section 9 can be freely layed out within the distance of 50 m to 100 m, for example in a space under the floor of the clean room or outside the clean room. The control computer 1 and the operation display section 2 are provided in the operation unit 28. The operation unit 28 can also be freely layed out within the distance of 50 m to 100 m. The operation unit can have any format such as a rack mount, disk top or disk side, and can be disposed in a desired format near the main body section or within the clean room, to facilitate the use of the operation unit. By this arrangement, a flexible use of the operation unit is made possible to match the idea of the user of the apparatus. 
     According to the present embodiment, the operation unit 28 and the digital control section 9 can be disposed at the outside of the clean room within the distance of 50 m to 100 m so that the charged particle beam exposure apparatus can be disposed to meet the idea of the manufacturing line at the side of the user of the apparatus. Further, the digital control section a and the operation unit 28 can be disposed at a remote place, so that the floor area required for installing the apparatus in the clean room can be reduced. Further, the digital control section a and the beam deflection control section 10 are connected with each other by the digital parallel transmission path 27, with a parallel transfer period being set to be variable in accordance with conditions for irradiating the electron beam, so that the productivity can be improved and it becomes possible to draw LSI patterns with resists having various levels of photosensitivity. 
     It is needless to mention that the analog control section 14 can be disposed beneath the clean room if it is near the main body so that the floor area within the clean room can be reduced further.