JP5462569B2 - Electron beam exposure system - Google Patents

Description

  The present invention relates to an electron beam exposure apparatus, and more particularly to an electron beam exposure apparatus capable of improving the speed and accuracy of focus correction by a refocus lens using an electrostatic electrode.

  In recent years, in an electron beam exposure apparatus, in order to improve throughput, a variable rectangular opening or a plurality of mask patterns are prepared in a mask, and these are selected by beam deflection and transferred and exposed to a sample.

  As such an exposure apparatus, there is an electron beam exposure apparatus that performs partial batch exposure. In partial collective exposure, a beam is irradiated to one pattern region selected by beam deflection from a plurality of patterns arranged on a mask, and a beam cross section is formed into a pattern shape. Further, the beam that has passed through the mask is deflected back by a subsequent deflector, reduced at a constant reduction rate determined by the electron optical system, and transferred onto the sample.

  If a frequently used pattern is prepared on the mask in advance in partial batch exposure, the number of exposure shots required is greatly reduced and the throughput is improved as compared with the case of only a variable rectangular aperture.

  On the other hand, when electron beam exposure is performed using a variable rectangular aperture or a partial collective pattern, the beam size of the electron beam varies from shot to shot, and the phenomenon that the focus of the electron beam shifts and the beam is blurred occurs. For example, when focusing on the sample surface with a small beam size, if exposure is performed with a large beam size, the total current of the electron beam increases, the focal length increases, and beam blur occurs on the sample surface.

  In order to prevent such defocusing of the electron beam, a method of correcting the current flowing through the refocusing coil for each shot from the area of the variable rectangular opening has been studied. Patent Document 1 describes a method of controlling a converging coil in synchronization with the size of a rectangular beam.

  Japanese Patent Application Laid-Open No. H10-228561 describes a method of measuring and correcting a beam axis misalignment when performing electron beam refocusing.

  Patent Document 3 describes a method in which a refocus flyback circuit is provided on the downstream side of the refocus coil, and the electron beam position shift is corrected at high speed by a refocus flyback deflector.

  Patent Document 4 describes an apparatus that corrects focus using a quadrupole electrostatic lens.

JP-A-56-94740 JP 58-121625 A Japanese Patent Laid-Open No. 10-289841 JP 2008-91827 A

  As described above, when a variable rectangular opening or a partial collective pattern is used, the focus of the electron beam is moved for each shot, so that it is possible to prevent the deviation of the beam focus.

  Specifically, a refocusing coil is installed, and an amount of current proportional to the cross-sectional area of the shaped beam is passed through the refocusing coil to adjust the focus of the beam. For example, when the beam size is large, a larger current is passed through the refocusing coil in proportion to the cross-sectional area of the beam so as to strengthen the electron beam convergence effect.

  However, it takes time to execute the refocus, and there is a disadvantage that the exposure throughput cannot be improved despite the partial batch exposure.

  For example, although the time required to shape the electron beam is about 50 ns, the refocusing execution time is about 300 ns until a predetermined current is passed through the refocusing coil and becomes a stable current. The exposure waiting time has become longer.

  On the other hand, in Patent Document 3, the position shift due to focus correction by the refocus coil is corrected at high speed by the deflector, but the refocus itself is not performed at high speed.

  In addition, as described in Patent Document 4, when the quadrupole electrostatic lens is installed, the adjustment speed is improved as compared with the case of using the refocus coil. There is a need to improve accuracy and speed.

  The present invention has been made in view of the problems of the prior art, and provides an electron beam exposure apparatus capable of shortening the refocus time by a refocus lens using an electrostatic electrode and improving the refocus accuracy. For the purpose.

The problems described above include an electron gun that emits an electron beam, shaping means having an opening for shaping the electron beam, a projection lens that forms an image of the electron beam on a sample surface, and an upper part of the projection lens. A refocus lens comprising an electrostatic multipole electrode for correcting the focus of the electron beam, a focus correction signal generating circuit for generating a correction signal to be applied to each electrode of the refocus lens, and the correction An offset signal generation circuit that generates an offset signal to be added to a signal, and the focus correction signal generation circuit and the offset signal generation circuit are independently controlled, and the shaping is performed based on the correction signal to which the offset signal is added. A voltage corresponding to the cross-sectional area of the electron beam shaped by the means is generated and applied to each electrode of the refocus lens. And a control unit, wherein the control means, said offset signal generator, said to operate on the basis of the housing of the electron beam exposure apparatus, the focus correction signal generating circuit, is outputted by the offset signal generation circuit The offset signal is operated based on the offset signal, and the focus correction signal generation circuit is operated with a power source generated based on the offset signal output from the offset signal generation circuit. It consists of an offset DA converter that inputs a digital signal and converts it into an analog signal, and an offset amplifier that amplifies the analog offset signal. The focus correction signal generation circuit receives a digital signal of refocus data. Convert to analog refocus signal That said and fast focus amount generating DA converter from the DA converter offset, solved by an electron beam exposure apparatus composed of the offset amplifier for amplifying the analog refocus signal at a high speed amplifier.

Further, the refocusing lens may have three or more stages of quadrupole electrodes in the optical axis direction.

  In the present invention, in order to generate a voltage to be applied to the electrostatic electrode for correcting the focus of the electron beam, a focus correction signal generation circuit and an offset signal generation circuit are provided, and the correction signal generated by the focus correction signal generation circuit is provided. The offset signal generated by the offset signal generation circuit is added to the signal. The signal corresponding to the voltage actually applied to the electrostatic electrode is a signal obtained by adding an offset signal to the focus correction signal.

  As described above, since the signal corresponding to the voltage actually applied to the electrostatic electrode is generated separately for the focus correction signal and the offset signal, the range of the signal generated in the focus correction signal generation circuit is narrowed. Therefore, the focus correction signal can be generated at high speed and with high accuracy. Therefore, quadrupole focus correction that follows the drawing speed in order to improve throughput is possible, and high-speed and high-precision drawing can be performed.

It is a block diagram of the electron beam exposure apparatus which concerns on this invention. It is a block diagram of the electrode of the refocus lens in the electron beam exposure apparatus which concerns on this invention. It is a figure explaining the voltage applied to each electrode of a refocus lens. It is a figure explaining the trajectory of the electron of a 3 step | paragraph quadrupole electrostatic electrode. It is a block diagram (the 1) of the quadrupole focus correction circuit for generating the voltage applied to 1 electrode of a refocus lens. FIG. 6 is a diagram (part 1) illustrating a relationship between an output value of a DA converter and an amplifier and a refocus amount. It is a block diagram (the 2) of the quadrupole focus correction circuit for generating the voltage applied to 1 electrode of a refocus lens. FIG. 6 is a diagram (part 2) illustrating a relationship between an output value of a DA converter and an amplifier and a refocus amount.

(1) First Embodiment Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(Configuration of electron beam exposure system)
FIG. 1 is a block diagram of an electron beam exposure apparatus according to the present embodiment.

  The electron beam exposure apparatus is roughly divided into an electron optical system column 100 and a control unit 200 that controls each part of the electron optical system column 100. Among these, the electron optical system column 100 includes an electron beam generating unit 130, a mask deflecting unit 140, and a substrate deflecting unit 150, and the inside thereof is decompressed.

  In the electron beam generator 130, the electron beam EB generated from the electron gun 101 is converged by the first electromagnetic lens 102, then passes through the rectangular aperture 103 a of the beam shaping mask 103, and the cross section of the electron beam EB is rectangular. To be shaped.

  Thereafter, the electron beam EB is imaged on the exposure mask 110 by the second electromagnetic lens 105 of the mask deflection unit 140. The electron beam EB is deflected to a specific pattern S formed on the exposure mask 110 by the first and second electrostatic deflectors 104 and 106, and the cross-sectional shape thereof is shaped into the pattern S.

  Although the exposure mask 110 is fixed to the mask stage 123, the mask stage 123 is movable in a horizontal plane, and the deflection range (beam deflection region) of the first and second electrostatic deflectors 104 and 106 is set. In the case of using the pattern S in the portion exceeding, the pattern S is moved into the beam deflection region by moving the mask stage 123.

  Further, instead of the exposure mask 110, an opening capable of changing the electron beam into a predetermined shape may be arranged.

  The third and fourth electromagnetic lenses 108 and 111 arranged above and below the exposure mask 110 play a role of forming an image of the electron beam EB on the substrate W by adjusting their current amounts.

  The size of the electron beam EB that has passed through the exposure mask 110 is returned to the optical axis (beam axis) C by the deflection action of the third and fourth electrostatic deflectors 112 and 113, and then the size is adjusted by the fifth electromagnetic lens 114. Reduced.

  The mask deflection unit 140 is provided with first and second correction coils 107 and 109, which correct beam deflection aberrations generated by the first to fourth electrostatic deflectors 104, 106, 112, and 113. Is done.

  Thereafter, the electron beam EB passes through the aperture 115a of the shielding plate 115 constituting the substrate deflecting unit 150, and the focus is adjusted according to the cross-sectional area of the electron beam EB by the refocus lens 128. Two projection electromagnetic lenses 116 and 121 project the image onto the substrate W. As a result, the pattern image of the exposure mask 110 is transferred to the substrate W at a predetermined reduction ratio, for example, a reduction ratio of 1/10.

  The substrate deflecting unit 150 is provided with a fifth electrostatic deflector 119 and an electromagnetic deflector 120, and the electron beam EB is deflected by these deflectors 119 and 120, and an exposure mask is formed at a predetermined position on the substrate W. The pattern image is projected.

  Further, the substrate deflection unit 150 is provided with third and fourth correction coils 117 and 118 for correcting the deflection aberration of the electron beam EB on the substrate W.

  The substrate W is fixed to a wafer stage 124 that can be moved in the horizontal direction by a driving unit 125 such as a motor. By moving the wafer stage 124, it is possible to expose the entire surface of the substrate W.

  On the other hand, the control unit 200 includes an electron gun control unit 202, an electron optical system control unit 203, a mask deflection control unit 204, a mask stage control unit 205, a blanking control unit 206, a substrate deflection control unit 207, a wafer stage control unit 208, and A refocus control unit 209 is included. Among these, the electron gun control unit 202 controls the electron gun 101 to control the acceleration voltage of the electron beam EB, beam emission conditions, and the like. Further, the electron optical system control unit 203 controls the amount of current to the electromagnetic lenses 102, 105, 108, 111, 114, 116 and 121, and the magnification and focus of the electron optical system in which these electromagnetic lenses are configured. Adjust the position. The blanking control unit 206 controls the voltage applied to the blanking electrode 127 to deflect the electron beam EB generated before the start of exposure onto the shielding plate 115, and onto the substrate W before exposure. Prevents EB from being irradiated.

  The substrate deflection control unit 207 controls the voltage applied to the fifth electrostatic deflector 119 and the amount of current to the electromagnetic deflector 120 so that the electron beam EB is deflected to a predetermined position on the substrate W. To. The wafer stage control unit 208 adjusts the driving amount of the driving unit 125 to move the substrate W in the horizontal direction so that the desired position of the substrate W is irradiated with the electron beam EB.

  The refocus control unit 209 supplies a necessary voltage to each electrode constituting the refocus lens according to the cross-sectional area of the electron beam EB that is shaped through the exposure mask 110.

  The above-described units 202 to 209 are controlled in an integrated manner by an integrated control system 201 such as a workstation.

(Refocus lens)
FIG. 2 shows the configuration of the refocus lens used in this embodiment. FIG. 2A shows a refocus lens 128 installed above the projection lenses 116 and 121 on the electron gun 101 side. FIG. 2B shows a diagram in which the refocusing lens 128 composed of three stages is displayed so that the arrangement of the electrodes can be understood at an interval for each stage.

  As shown in FIG. 2, the refocus lens 128 is configured by overlapping an electrostatic quadrupole lens using four electrostatic electrodes in the optical axis direction (Z-axis direction) at a predetermined interval. The refocus lens is composed of three stages from the first stage LS1 to the third stage LS3.

  As shown in FIG. 2B, each stage is composed of four electrostatic electrodes, and is arranged rotationally symmetrically about the optical axis.

  The first-stage electrostatic quadrupole lens LS1 is composed of four electrostatic electrodes P11, P12, P13, and P14, and is equally spaced in the X-axis direction and Y-axis direction around the optical axis (Z-axis). Two are arranged. For example, the length of each electrode is 10 mm.

  The second-stage electrostatic quadrupole lens LS2 includes four electrostatic electrodes P21, P22, P23, and P24, and is arranged at the lower stage of the first-stage electrostatic quadrupole lens LS1. The four electrodes of the second-stage electrostatic quadrupole lens LS2 are arranged so as to overlap the four electrodes of the first-stage electrostatic quadrupole lens LS1 at a predetermined interval in the Z-axis direction. This predetermined interval is, for example, 5 mm. The length of each electrode of the second-stage electrostatic quadrupole lens LS2 is twice the length of each electrode of the first-stage electrostatic quadrupole lens LS1.

  The third-stage electrostatic quadrupole lens LS3 is composed of four electrostatic electrodes P31, P32, P33, and P34, and is arranged at the lower stage of the second-stage electrostatic quadrupole lens LS2. The four electrodes of the third-stage electrostatic quadrupole lens LS3 are arranged so as to overlap the four electrodes of the second-stage electrostatic quadrupole lens LS2 at a predetermined interval in the Z-axis direction. This predetermined interval is, for example, 5 mm.

The shape and arrangement of the electrodes (P31, P32, P33, P34) of the third stage electrostatic quadrupole lens LS3 are the same as the electrodes (P11, P12, P13, P14) of the first stage electrostatic quadrupole lens LS1.
Is the same as the shape and arrangement.

  A predetermined voltage is applied to each electrode of the refocus lens configured as shown in FIG. 2 by the refocus control unit 209, and the refocus lens 128 as a whole generates electric fields necessary for refocus, aberration correction, and beam irradiation position correction. It is trying to occur.

  In the present embodiment, a voltage having a polarity as shown in FIG. 3 is applied. FIGS. 3A to 3C show plan views of the first to third stage electrostatic quadrupole lenses (LS1, LS2, and LS3) for the sake of convenience.

  FIG. 3A to FIG. 3C show applied voltages necessary for refocusing. Refocusing is performed by a three-stage quadrupole lens from the first stage to the third stage.

  As shown in FIG. 3A, a voltage of + Vα is supplied to the electrostatic electrodes P11 and P13, and a voltage of −Vα is supplied to P12 and P14.

  As shown in FIG. 3B, a voltage is applied to each electrode of LS2 in the next stage so that the potential is opposite to that of each electrode of LS1. That is, −Vβ is applied to P21 and P23, and + Vβ is applied to P22 and P24.

  Further, as shown in FIG. 3C, the same voltage as that of the first stage LS1 is applied to each electrode of the third stage LS3. That is, a voltage of + Vα is supplied to P31 and P33, and a voltage of −Vα is supplied to P32 and P34.

  These voltages are calculated by multiplying the cross-sectional area of the electron beam shaped by the refocus control unit 209 by the refocus coefficient and supplied to each electrode.

  FIG. 4 is a diagram for explaining the trajectory of electrons of the three-stage quadrupole electrostatic electrode. Assume that the Z axis in FIG. 4 is the beam axis, and the electron beam travels from the left to the right in the figure.

  The x-axis side in FIG. 4 shows the trajectory C1 of the electron beam in the X direction, and the y-axis side shows the trajectory C2 in the Y direction of the electron beam. As shown in FIG. 4, when paying attention to the trajectory C1 in the x direction, the first-stage quadrupole lens functions as a convex lens, and the second-stage quadrupole lens functions as a concave lens. The quadrupole lens works as a convex lens. When attention is paid to the orbit C2 in the y direction, the first quadrupole lens functions as a concave lens, the second quadrupole lens functions as a convex lens, and the third quadrupole lens Acts as a concave lens. The incident angle to the final focal point z2 can be made almost the same in both the x and y directions. Therefore, the focus can be adjusted by using the three-stage quadrupole electrostatic electrode.

  In the above description, the case where the refocusing lens is configured by three stages of electrostatic electrodes is used. However, the refocusing lens may be configured by three or more stages of electrostatic electrodes.

  Hereinafter, a focus correction circuit for generating a refocus voltage will be described with reference to FIGS.

  FIG. 5 shows a block diagram of the focus correction circuit RFC1 connected to one electrode 54 of the quadrupole electrode, and FIG. 6 shows the output values and focus of the DA converter and amplifier constituting the focus correction circuit RFC1. The relationship with quantity is shown.

  As shown in FIG. 5, the focus correction circuit RFC1 is basically composed of a focus amount generation DA converter (DAC1) 51, an offset output DA converter (DAC2) 52, and an operational amplifier (AMP) 53.

  The focus amount generation DA converter 51 converts the digital signal of the refocus data into an analog signal. The refocus data is calculated in advance for each irradiation position and stored in a storage unit (not shown). The refocus data corresponds to the amount of change within a range corresponding to the output voltage of the focus correction circuit necessary for focus correction. For example, if the range of the output voltage for focus correction is Vx1 to Vx2, a value corresponding to the voltage when Vx1 is zero is output.

  The offset output DA converter 52 is controlled independently of the focus amount generation DA converter 51 and converts a digital signal of offset data into an analog signal. The offset data is a value corresponding to a voltage serving as a reference for a voltage used for focus correction.

  The operational amplifier 53 receives the combined amount of the output of the focus amount generation DA converter 51 and the output of the offset output DA converter 52, and amplifies it to a required size.

  In the focus correction circuit thus configured, the focus amount generation DA converter 51 corresponds to a “focus correction signal generation circuit”, and the offset output DA converter 52 corresponds to an “offset signal generation circuit”.

FIG. 6 shows a relationship between the output value of the focus correction circuit RFC1 and the focus amount F when a required voltage is applied to all the quadrupole electrodes and refocusing is performed. As shown in FIG. 6, the output value of the focus correction circuit RFC1 and the focus amount F have a quadratic function relationship. That is, when the output voltage of the focus correction circuit RFC1 is V and a, b, and c are constants, the focus amount F is expressed by aV ² + bV + c.

  If the focus amount F is to be changed greatly for focus adjustment, for example, in the graph of FIG. 6, it is necessary to adjust the output value in the focus correction actual use area RE0. In such a focus correction actual use region RE0, a large output is required as an output of the DA converter and the amplifier. Therefore, a general small signal / high-speed amplifier cannot be used, and the output value for obtaining a desired focus amount F cannot be changed at high speed. Further, since the DA converter also requires a wide output area (V0 to Vx2 in FIG. 6) corresponding to the output value, a high-precision DA converter is required. For this reason, the DA converter is also slow, and it is difficult to perform high-speed refocusing.

  In the refocus correction circuit RFC1 in the first embodiment, as shown in FIG. 6, the current output region RE2 by the focus amount generation DA converter 51 is made to correspond to the range of the focus correction actual use region RE0, and the offset The current output area RE1 of the DA converter 52 is from zero to immediately before the focus correction actual use area RE0.

As shown in FIG. 5, when the focus data is inputted to the focus amount generating DA converter 51, the current i _f is output accordingly. When the focus offset data is input to the offset output DA converter 52, a current _io corresponding thereto is output. At the connection point T1, the current _if and the current _io are combined to obtain a focus value _{if + o} . This value i _{f + o} is input to the operational amplifier 53, converted into a voltage, amplified to a desired value, becomes a voltage V _{f at the} output terminal T 2, and is applied to the electrode 54.

  For example, the offset output DA converter 52 outputs a signal corresponding to 10 [V], and the focus amount generating DA converter 51 outputs a signal in a range corresponding to 0 to 10 [V]. Keep it like that. As a result, the output of the focus correction circuit outputs a voltage in the range of 10 to 20 [V], and the focus amount can be adjusted in this range.

  In this way, since the focus amount generation DA converter 51 only needs to be able to adjust the output value within the range of the focus correction actual use area RE0, a DA converter with higher accuracy than the DA converter corresponding to a wide output area can be used. Can be used.

  Further, in this focus correction circuit, the offset output DA converter 52 only needs to output a constant value at all times, so it is not necessary to be high speed, and a low speed DA converter can be used. Therefore, it is possible to output the offset value with high accuracy.

(2) Second Embodiment In the second embodiment, another example of the focus correction circuit will be described. Since the configuration of the electron beam exposure apparatus including the focus correction circuit of the second embodiment and the configuration of the refocusing quadrupole lens are the same as those described in the first embodiment, description thereof will be omitted.

  The focus correction circuit according to the second embodiment will be described with reference to FIGS.

  FIG. 7 shows a block diagram of the focus correction circuit RFC2 connected to one electrode 54 of the quadrupole electrode, and FIG. 8 shows output values and focus of the DA converter and amplifier constituting the focus correction circuit RFC2. The relationship with quantity is shown.

  As shown in FIG. 7, the focus correction circuit RFC2 includes a focus amount generation DA converter (DAC1) 71, an operational amplifier (AMP1) 72, an offset output DA converter (DAC2) 73, and an operational amplifier (AMP2). ) 74.

  The focus amount generation DA converter 71 operates on the basis of the offset voltage VG generated by the offset output DA converter 73 and the operational amplifier 74, and converts the digital signal of the refocus data into an analog signal. The refocus data is calculated in advance for each irradiation position and stored in a storage unit (not shown). The refocus data corresponds to the amount of change within a range corresponding to the output voltage of the focus correction circuit necessary for focus correction. For example, if the range of the output voltage for focus correction is Vx1 to Vx2, a value corresponding to the voltage when Vx1 is zero is output.

  Since a reference voltage differs between a circuit (not shown) for outputting refocus data and a circuit after the focus amount generation DA converter 71, an isolator is provided on the input side of the focus amount generation DA converter 71.

  The operational amplifier 72 amplifies the output of the focus amount generation DA converter 71 to a required size.

  The offset output DA converter 73 is controlled independently of the focus amount generation DA converter 71 and converts a digital signal of offset data into an analog signal. The offset data is a value corresponding to a voltage serving as a reference for a voltage used for focus correction.

  The operational amplifier 74 amplifies the output of the offset output DA converter 73 to a required magnitude. The offset output DA converter 73 and the operational amplifier 74 operate using the casing of the exposure apparatus as a reference voltage.

  In the focus correction circuit configured in this way, the focus amount generation DA converter 71 and the operational amplifier 72 are “focus correction signal generation circuit”, and the offset output DA converter 73 and the operational amplifier 74 are “offset signal generation circuit”. ".

  FIG. 8 shows the relationship between the output value of the focus correction circuit RFC2 and the focus amount F when a required voltage is applied to all the quadrupole electrodes and refocusing is performed. As shown in FIG. 8, the output value of the focus correction circuit RFC2 and the focus amount F have a quadratic function relationship. As in the first embodiment, if the focus amount is to be changed greatly for focus adjustment, it is necessary to adjust the output value in the focus correction actual use area RE0 as shown in FIG. 8, for example.

  In the focus correction circuit RFC2 in the second embodiment, as shown in FIG. 8, the current output region RE2 by the focus amount generation DA converter 71 is made to correspond to the range of the focus correction actual use region RE0 and used for offset output. The current output area RE1 by the DA converter 73 is from zero to immediately before the focus correction actual use area RE0.

  Further, the output area RE5 by the operational amplifier 72 is made to correspond to the range of the focus correction actual use area RE0, and the output area RE4 by the operational amplifier 74 is from zero to immediately before the focus correction actual use area RE0.

As shown in FIG. 7, the focus data is inputted to the focus amount generating DA converter 71, the value i _f corresponding to it is output. When focus offset data is input to the offset output DA converter 73, a value _io corresponding to the focus offset data is output.

The output value i _o is converted into a voltage by the operational amplifier 74 and amplified to a desired value VG. In the focus correction circuit RFC2 of this embodiment, the output value VG is used as a reference voltage for a circuit that adjusts the focus amount. That is, the output voltage value VG is used as a reference voltage for the DA converter 71 for focus amount generation and the operational amplifier 72. In addition, a power supply circuit that generates the reference voltage value VG is configured and used as a reference voltage generator.

The value _if output from the DA converter 71 for generating the focus amount is input to the operational amplifier 72 based on the voltage value VG, converted into voltage and amplified to a desired value, and the voltage V _f is output at the output terminal T3. And applied to the electrode 54.

  Similarly to the first embodiment, the focus amount generation DA converter 71 only needs to be able to adjust the output value within the range of the focus correction actual use area RE0, so that it is higher than the DA converter corresponding to a wide output area. A precision DA converter can be used.

  The operational amplifier 74 that amplifies the output value of the offset output DA converter 73 is configured to operate independently of the operational amplifier 72 that amplifies the output value of the focus amount generation DA converter 71. That is, the output region RE4 of the operational amplifier 74 and the output region RE5 of the operational amplifier 72 are separately amplified. Therefore, since the operational amplifier 72 only needs to be able to amplify within the range of the focus correction actual use area RE0, a high speed amplifier can be used. Similarly, since the operational amplifier 74 only needs to be able to amplify within the range of the output region RE4, a high-speed amplifier can be used.

  Similarly to the first embodiment, in the focus correction circuit, the offset output DA converter 73 only needs to output a constant voltage at all times. Therefore, it is not necessary to be high speed, and a low speed DA converter is used. can do. Therefore, the offset value can be output with high accuracy.

  Further, since the offset output value only needs to be a constant output value, an IC that generates a reference voltage may be used instead of using the DA converter.

  As described above, in this embodiment, in order to generate a voltage to be applied to the electrostatic electrode that corrects the focus of the electron beam, the focus correction signal generation circuit and the offset signal generation circuit are provided. The offset signal generated by the offset signal generation circuit is added to the correction signal generated by the above. The signal corresponding to the voltage actually applied to the electrostatic electrode is a signal obtained by adding an offset signal to the focus correction signal.

  As described above, since the signal corresponding to the voltage actually applied to the electrostatic electrode is generated separately for the focus correction signal and the offset signal, the range of the signal generated in the focus correction signal generation circuit is narrowed. Therefore, the focus correction signal can be generated at high speed and with high accuracy. Therefore, quadrupole focus correction that follows the drawing speed in order to improve throughput is possible, and high-speed and high-precision drawing can be performed.

  In addition, the present invention is a patent application related to the results of the commissioned research of the national government (FY2009 New Energy and Industrial Technology Development Organization “Mask Design / Drawing / Inspection Optimization Technology Development” commissioned research, industrial technology Patent application subject to the application of Article 19 of the Strengthening Law).

51, 71: Focus conversion DA converter, 52, 73: Offset output DA converter, 53, 72, 74: Operational amplifier, 100: Electro-optic system column, 101: Electron gun, 102: First electromagnetic lens 103 ... Beam shaping mask, 103a ... Rectangular aperture, 104 ... First electrostatic deflector, 105 ... Second electromagnetic lens, 106 ... Second electrostatic deflector, 107 ... First correction coil, 108 ... Third electromagnetic 109: Second correction coil, 110: Exposure mask, 111: Fourth electromagnetic lens, 112: Third electrostatic deflector, 113: Fourth electrostatic deflector, 114: Fifth electromagnetic lens, 115: Shielding Plate 115a ... Aperture 116 ... First projection electromagnetic lens 117 ... Third correction coil 118 ... Fourth correction coil 119 ... Five electrostatic deflector 120 ... Electromagnetic deflector 121 ... Second Electromagnetic lens shade, 123 ... mask stage, 124 ... wafer stage, 125 ... driving section, 127 ... blanking electrode, 128 ... refocusing lens.

Claims (4)

An electron gun that emits an electron beam;
Shaping means having an aperture for shaping the electron beam;
A projection lens for imaging the electron beam onto the sample surface;
A refocusing lens that is installed above the projection lens and comprises an electrostatic multipole electrode that corrects the focus of the electron beam;
A focus correction signal generating circuit for generating a correction signal to be applied to each electrode of the refocus lens;
An offset signal generating circuit for generating an offset signal to be added to the correction signal;
The focus correction signal generation circuit and the offset signal generation circuit are controlled independently, according to the cross-sectional area of the electron beam shaped by the shaping means based on the correction signal to which the offset signal is added. Control means for generating a voltage and applying it to each electrode of the refocusing lens ,
The control means operates the offset signal generation circuit with reference to a housing of the electron beam exposure apparatus, and operates the focus correction signal generation circuit with reference to an offset signal output from the offset signal generation circuit. And operating the focus correction signal generation circuit with a power supply generated based on the offset signal output by the offset signal generation circuit,
The offset signal generation circuit includes an offset DA converter that inputs a digital signal of offset data and converts it into an analog signal, and an offset amplifier that amplifies the analog offset signal.
The focus correction signal generation circuit inputs a digital signal of refocus data and converts the analog refocus signal into an analog refocus signal, which is faster than the offset DA converter, and amplifies the analog refocus signal An electron beam exposure apparatus comprising an amplifier faster than the offset amplifier . 2. The electron beam exposure apparatus according to claim 1 , wherein an isolator is connected to an input side of the focus amount generating DA converter. 2. The electron beam exposure apparatus according to claim 1 , wherein the offset signal generation circuit includes a reference signal generator and an amplifier.   2. The electron beam exposure apparatus according to claim 1, wherein the refocus lens has three or more quadrupole electrostatic electrodes in the optical axis direction.

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