JP2006277996A - Electron beam device and device manufacturing method using it - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide objective lenses preventing discharging between an electrostatic lens and a test piece, which can have high voltage applied to them and are provided with parameters which can be adjusted so that the absolute value of axial chromatic aberration in the objective lenses and the absolute value of axial chromatic aberration in an axial chromatic aberration compensating lens are equivalent. <P>SOLUTION: The electron beam device is provided with the objective lenses focusing the electron beams and irradiating the test piece. The objective lenses are provided with at least one conical electrode with a radius which is made smaller going toward the test piece side and an axial symmetrical electrode. The axial symmetrical electrode is an approximately grounded electrode installed more to the test piece side than the conical electrode and is installed in a position making the intensity of an electric field smaller on a test piece surface. Furthermore, a multi-pole lens producing negative axial chromatic aberration and a voltage control apparatus are provided and the absolute value of the axial chromatic aberration in the objective lenses and the axial chromatic aberration in the multi-pole lens are made equivalent by having the voltage of the axial symmetrical electrode adjusted by the voltage control device or having both the voltage of the axial symmetrical electrode and the voltage of at least one of the conical electrodes adjusted. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an electron beam apparatus, a pattern evaluation method using the apparatus, and a device manufacturing method using the apparatus. In particular, in a defect device for a sample having a pattern with a minimum line width of 0.1 μm or less, an electron beam device suitable for performing line width measurement, defect review, or pattern potential measurement, the axial chromatic aberration of the lens is reduced. In addition, the present invention relates to an apparatus capable of performing substrate evaluation with high accuracy and high throughput, and a device manufacturing method using such an apparatus.

  Major factors that limit the substrate evaluation accuracy of the electron beam apparatus are axial chromatic aberration and spherical aberration. In a conventional electron beam apparatus, an objective lens using an electrostatic lens reduces axial chromatic aberration and spherical aberration by applying a high voltage to the electrode of the electrostatic lens. Further, the longitudinal chromatic aberration of the objective lens is corrected using an axial chromatic aberration correcting lens having four stages of quadrupole lenses.

However, when a high voltage is applied to the electrode of the electrostatic lens, the electric field strength on the sample surface increases, so that there is a possibility that a discharge occurs between the electrostatic lens and the sample and the sample is destroyed.
In addition, when axial chromatic aberration correction is performed using an axial chromatic aberration correction lens having four stages of quadrupole lenses, the axial chromatic aberration is not as designed. There is a problem in that the absolute value of axial chromatic aberration of the chromatic aberration correcting lens is not equal and residual chromatic aberration is increased.

  The present invention is intended to solve these problems. The discharge between the electrostatic lens and the sample can be prevented, a high voltage can be applied, and the absolute value and axial axis of the on-axis chromatic aberration of the objective lens can be applied. It is an object of the present invention to provide an objective lens having parameters that can be adjusted so that the absolute value of the axial chromatic aberration of the upper chromatic aberration correction lens is equal.

  Another object of the present invention is to provide an electron beam apparatus including the objective lens and a device manufacturing method using the apparatus.

  The present invention is an electron beam separator that irradiates a sample to which a negative voltage is applied, accelerates secondary electrons emitted from the sample by an electric field created by the objective lens and the sample, and has at least an electromagnetic deflector. An electron beam apparatus that directs the secondary electron beam toward a detector, the electron beam apparatus including an objective lens that focuses the electron beam and irradiates the sample, and the objective lens is disposed on the sample side. The electrode has at least one conical electrode having a radius that decreases toward the opposite side, and an axially symmetric electrode, and the axially symmetric electrode is a substantially grounded electrode disposed on the sample side of the conical electrode, An electron beam apparatus is provided, which is disposed at a position where the electric field strength on the surface is reduced.

  Further, the present invention irradiates a sample to which a negative voltage is applied with an electron beam, accelerates secondary electrons emitted from the sample by an electric field created by the objective lens and the sample, and separates the electron beam having at least an electromagnetic deflector An electron beam apparatus that directs the secondary electron beam toward a detector with a detector, the electron beam apparatus comprising an objective lens that focuses the electron beam and irradiates the sample, and the objective lens is at least The present invention provides an electron beam apparatus having one electrode and a ground electrode, wherein the ground electrode is disposed at a position to reduce the electric field strength on the sample surface.

  According to the present invention, the objective lens has a conical electrode for applying a high voltage and has an axially symmetric electrode to which a voltage substantially close to ground is applied on the sample surface side, so that an electrode to which a high voltage is applied is formed. Since the electric field is partially shielded by this axisymmetric electrode, the electric field strength at the sample surface is reduced, dielectric breakdown at the sample surface is prevented, and discharge between the lens and the sample is prevented. Can do.

  In addition, according to the present invention, the objective lens has a conical ground electrode that is completely grounded in addition to the conical electrode that applies a high voltage, so that the voltage applied to the conical electrode required for a certain lens action is small. Thus, the discharge between the lens and the sample can be prevented.

  Further, according to the present invention, by applying a finely adjusted voltage to the substantially grounded axially symmetric electrode on the sample surface side, or adjusting the voltage adjusted to both the axially symmetric electrode and at least one conical electrode. By applying the voltage, the axial chromatic aberration coefficient of the objective lens is electrically controlled, and the absolute value of the positive axial chromatic aberration of the objective lens is accurately matched to the absolute value of the negative axial chromatic aberration of the axial chromatic aberration correction lens. The residual chromatic aberration can be extremely reduced.

  Furthermore, according to the present invention, by adjusting the high voltage applied to the cylindrical electrode with a control power supply, the axial chromatic aberration coefficient of the objective lens is electrically controlled, and the absolute value of the positive axial chromatic aberration of the objective lens Can be accurately canceled in accordance with the absolute value of the negative axial chromatic aberration of the longitudinal chromatic aberration correction lens, and the residual chromatic aberration can be made extremely small.

  Furthermore, in an electron beam apparatus having a small residual chromatic aberration, the NA of the NA aperture can be set to a larger value than usual, and the beam current of each beam can be increased. Therefore, the sample can be evaluated with high throughput.

  A first embodiment of an electron beam apparatus according to the present invention will be described with reference to FIG. This electron beam apparatus forms a rectangular beam from an electron beam emitted from the electron gun 1, focuses the rectangular beam on the sample 16, and an image of a secondary electron beam emitted from the surface of the sample 16. And a detection device 300 for detecting secondary electrons output from the secondary optical system.

The primary optical system 100 includes an L _a B ₆ cathode gun 1 that emits a primary electron beam, a condenser lens 3 that focuses the primary electron beam emitted from the L _a B ₆ cathode gun 1, and a focused primary electron beam. Molding opening 5 for forming a rectangular beam by molding, molding lenses 6 and 8 for finely adjusting the reduction ratio of the rectangular beam, axis alignment deflectors 2, 4, and 7 for axial alignment of the primary electron beam, and primary electrons A primary electron beam trajectory control deflector 9 for passing the beam through a different trajectory from the secondary electron trajectory, an objective lens 60 that focuses the primary electron beam and irradiates the sample 16, and a voltage applied to the objective lens is adjusted. And a voltage control power supply 70. In this way, the primary optical system forms a rectangular beam from the primary electron beam emitted from the L _a B ₆ cathode gun 1, focuses the rectangular beam on the sample 16, and the primary electron beam trajectory control deflector 9. Is controlled so as to pass through an orbit (30) different from the secondary electron orbit.

  The secondary optical system 200 includes an electrostatic deflector 17 that is accelerated by the objective lens 60 and corrects deflection chromatic aberration generated by the electromagnetic deflector 10 for an electron beam separator, a chromatic aberration correction lens 19 that generates negative axial chromatic aberration, The auxiliary lens 20 provided at the enlarged image position of the secondary electrons by the chromatic aberration correction lens 19, the magnifying lens 21 for further magnifying the secondary electron beam image, and the enlarged image position of the secondary electrons by the magnifying lens 21. An auxiliary lens 22 and a final magnifying lens 23 are provided. In this way, the secondary optical system enlarges the secondary electron beam emitted from the sample 16 and forms an image on the MCP (microchannel plate) 24.

  In the present embodiment, it has been described that the electromagnetic deflector 10 for electron beam separator is not included in the primary optical system 100 or the secondary optical system 200. However, it can be regarded as included in the primary optical system 100. It can also be regarded as being included in the secondary optical system 200. Further, it can be regarded as being included in both the primary optical system 100 and the secondary optical system 200.

  The detection device 300 includes an MCP 24, a TDI camera 504, and a control device 520 connected to the TDI camera 504 so as to be able to perform data communication. The TDI camera 504 converts the secondary electron image formed on the MCP 24 into an electronic signal.

  The objective lens 60 includes, in order from the sample 16 side, a disk-shaped axially symmetric electrode 15, an electrode 14, an electrode 13, an NA opening 12, and an electrode 11. The electrode 14 and the electrode 13 have a conical optical axis vicinity electrode whose radius decreases toward the sample side. In the present embodiment, the axially symmetric electrode 15 has a disc shape, but may have a conical shape. The electrode 11 may be omitted.

  In order to focus the primary electron beam and reduce axial chromatic aberration and spherical aberration, the voltage adjustment power supply 70 applies a positive high voltage to the electrode 14. The voltage adjusting power supply 70 applies a voltage close to the ground voltage to the axially symmetric electrode 15. Therefore, in spite of the positive high voltage applied to the electrode 14, the high electric field created by the electrode 14 is shielded by the electrode 15, so that the electric field strength on the surface of the sample 16 can be kept small. Accordingly, dielectric breakdown does not occur on the sample surface, and discharge between the electrode 14 and the sample 16 is prevented. Further, since a high voltage is applied to the electrode 14, the longitudinal chromatic aberration of the objective lens 60 is kept small.

  In order to improve the substrate evaluation accuracy of the electron beam apparatus, it is necessary to make the absolute value of the positive axial chromatic aberration produced by the objective lens 60 equal to the absolute value of the negative axial chromatic aberration produced by the chromatic aberration correction lens 19. is there. For this purpose, the assembly accuracy is set to a required value, and the voltage applied to the electrode 15 of the objective lens 60 is adjusted by the voltage adjusting power supply 70 or the voltage applied to the electrode 15 and the electrode 14 are applied. The axial chromatic aberration value is accurately adjusted by adjusting both the voltage to be applied. For example, when the voltage applied to the electrode 15 is increased, the electric field strength between the electrode 15 and the electrode 14 needs to be kept constant in order to obtain the same lens action, so the voltage applied to the electrode 14 at the same focal length is increased. Thus, the longitudinal chromatic aberration is reduced. Conversely, if the voltage applied to 15 is lowered, the electric field strength between the electrode 15 and the electrode 14 needs to be kept constant in order to obtain the same lens action, so the voltage applied to the electrode 14 is also lowered, and the axial chromatic aberration is reduced. Can be big. Thus, in an electron beam apparatus with a small residual chromatic aberration, the opening angle of the NA aperture 12 can be set to a large value of about 400 mrad (milliradian) when it is normally 200 mrad (milliradian). Therefore, the transmittance of secondary electrons is increased, a large beam current can be obtained, and the sample can be evaluated with high throughput.

  The electrode 13 is a voltage close to ground, and by changing this potential by several tens of volts, it is possible to dynamically correct the focus shift caused by the vertical movement (Z-direction movement) of the sample surface 16. Since the electrode 13 has a conical shape in accordance with the shape of the electrode 14, the necessary focal distance can be obtained without the electrodes being separated from each other near the optical axis.

  The chromatic aberration correction lens 19 is composed of a two-stage Wien filter. This Wien filter forms an image once in the middle and has the trajectory shown in FIG. The cross section of the Wien filter is shown on a double scale in FIG. That is, a 12-pole electrode is made of permalloy, and a magnetic field is also generated by passing a current through the coil 25. By applying a voltage that generates a two-fold symmetric electric field to these electrodes and an excitation current that generates a two-fold symmetric magnetic field, the Wien condition, that is, the condition in which secondary electrons go straight, is satisfied. A voltage that generates a time-symmetric electric field and a voltage that generates a six-time electric field are superimposed, and an excitation current that generates a four-time magnetic field and a six-time magnetic field is applied to the coil. Negative axial chromatic aberration is generated by a four-fold symmetric electric field / magnetic field, and negative spherical aberration is generated by a six-fold symmetric electric field / magnetic field. In the objective lens of this apparatus, axial chromatic aberration occupies most of the aberration at NA of about 200 mrad, but spherical aberration becomes a value that cannot be ignored at large NA of 400 mrad or more, so it is important to correct the spherical aberration. .

L _a B ₆ cathode gun 1 is operated in the space charge limited condition, shot noise is small.
The primary electron beam emitted from the L _a B ₆ cathode gun 1 is focused by the condenser lens 3 and irradiates the opening of the shaping opening 5 with uniform intensity. The primary electron beam is shaped into a rectangular beam by the shaping aperture 5, reduced by the shaping lens 6 and the shaping lens 8, deflected by the electromagnetic deflector 10, and enters the objective lens 60. The primary electron beam is aligned with the alignment deflectors 2, 4, and 7. The primary electron beam is further reduced by the objective lens 60 and focused on the sample 16. The objective lens corrects axial chromatic aberration as described above. Since the primary electron beam is controlled by the primary electron beam trajectory control deflector 9 so as to pass through a different orbit from the secondary electron, the space charge of the primary electron does not affect the secondary electron.

  The secondary electron beam emitted from the sample 16 is accelerated by an accelerating electric field generated between the positive voltage of the objective lens 60 and the sample 16. The secondary electron beam deflected by the electromagnetic deflector 10 is deflected in the reverse direction by the electrostatic deflector 17 to form an enlarged image at the image point 18 of the chromatic aberration correction lens 19. The electromagnetic deflector 10 is an electromagnetic deflector to separate the primary electron beam and the secondary electron beam. The distance between the electrostatic deflector 17 and the image point 18 is designed to be half the distance between the electromagnetic deflector 10 and the image point 18, and the deflection angle by the electromagnetic deflector 10 and the deflection angle by the electrostatic deflector 17 are: The direction is opposite and the absolute values are equal. Thereby, the deflection chromatic aberration generated by the electron beam separator is corrected by the electrostatic deflector 17 and becomes zero. An enlarged image of the secondary electron beam formed at the image point 18 is formed on the auxiliary lens 20 after passing through the chromatic aberration correction lens 19. The chromatic aberration correction lens 19 generates negative axial chromatic aberration for correcting positive axial chromatic aberration generated in the objective lens 60. The magnified image of the secondary electron beam formed on the auxiliary lens 20 is magnified by the magnifying lens 21 and formed on the auxiliary lens 22, and further magnified about 10 times by the final magnifying lens 23, and is equal to the element size of TDI on the MCP 24. An image of the pixel is formed. In order to change the pixel size, auxiliary lenses 26 and 27 for large pixels are installed in place of the auxiliary lens 22, an enlarged image is formed by the magnifying lens 21, and a voltage is applied to the electrode of the auxiliary lens 26 or 27. Thus, the magnification can be adjusted, and the size of the pixel image in TDI can be kept constant. The secondary electron image output from the MCP 24 is formed on the TDI camera 504, and the TDI camera 504 converts the imaged secondary electron image into an electronic signal.

  The detection device 300 further includes a control device 520 connected to the TDI camera 504 so as to be able to perform data communication. The control device 520 can be constituted by a general-purpose personal computer or the like as an example. The computer includes a control unit 522 that executes various controls and arithmetic processes according to a predetermined program, a storage device 524 that stores the predetermined program, and a CRT monitor that displays processing results, a secondary electronic image 526, and the like. 528 and an input unit 530 such as a keyboard and a mouse for an operator to input commands. Of course, the control device 520 may be configured from hardware dedicated to the defect inspection apparatus, a workstation, or the like.

  Thus, in the first embodiment of the electron beam apparatus according to the present invention, since a high voltage is applied to the electrode 14 of the objective lens 60, axial chromatic aberration can be reduced, and Since a voltage close to ground is applied, discharge between the electrode 14 and the sample 16 can be prevented despite the high voltage of the electrode 14. Furthermore, since the voltage applied to the electrodes 14 and 15 can be adjusted by the voltage adjusting power source 70, the absolute value of the positive axial chromatic aberration generated in the objective lens is the negative axial chromatic aberration generated in the chromatic aberration correcting lens 19. The axial chromatic aberration can be accurately corrected by matching the absolute value. Further, since the residual chromatic aberration is small, it is possible to increase the beam current of each beam with a large aperture angle, so that the sample can be evaluated with high throughput.

  Next, a second embodiment of the electron beam apparatus according to the present invention will be described with reference to FIG. This electron beam apparatus forms a multi-beam from an electron beam emitted from the electron gun 1, focuses a multi-beam on a sample 45 and scans it, and a secondary electron beam emitted from the sample surface. A secondary optical system 500 that expands the distance between each other and a detection device 550 that detects secondary electrons output from the secondary optical system are provided.

The primary optical system 400 includes an L _a B ₆ cathode gun 31 that emits a primary electron beam, a condenser lens 32 that focuses the primary electron beam emitted from the L _a B ₆ cathode gun 1, and a focused primary electron beam. A multi-aperture 33 that forms a multi-beam, a shaping lens 34 that reduces the multi-beam and forms an image at a focal point 38, a reduction lens 36, an NA aperture 35 that suppresses axial chromatic aberration to low aberration, a correction lens 54, a negative lens A chromatic aberration correcting lens 37 that generates axial chromatic aberration, an electrostatic deflector 40 that operates a multi-beam on the sample 45 and corrects deflection chromatic aberration generated by the electromagnetic deflector 41, and an objective lens 42. . In this way, the primary optical system forms a multi-beam from the primary electron beam emitted from the L _a B ₆ cathode gun 1, focuses the multi-beam on the sample 45, and scans it by the electrostatic deflector 40. It is done.

  The secondary optical system 500 includes magnifying lenses 48 and 50 that expand the secondary electron beam emitted from the sample and accelerated by the objective lens, and electrostatic deflectors 49 and 51 that align the secondary electron beam. I have. In this way, the secondary optical system enlarges the secondary electron beam emitted from the sample 45 and forms an image on the detector 52.

  In the present embodiment, the electromagnetic deflector 41 for the electron beam separator has been described as not included in the primary optical system 400 or the secondary optical system 500, but can be regarded as included in the primary optical system 400. It can also be regarded as being included in the secondary optical system 500. Further, it can also be regarded as being included in both the primary optical system 400 and the secondary optical system 500.

  The detection device 550 includes a detector 52 and a control device 520 connected to the A / D converter and signal processing circuit 504 so as to be able to perform data communication. The A / D converter and signal processing circuit 504 converts an SEM (scanning electron microscope) image of a plurality of channels detected by the detector 52 into an electronic signal.

In SEM (scanning electron microscope) using multi-beams, it is desirable to form as many multi-beams as possible on the sample 45. Therefore, the zooming action of the condenser lens 32 and the molded lens 34 disposed before and after the multi-aperture 33, that is, the focusing condition for creating the crossover image created by the L _a B ₆ cathode gun 31 in the NA aperture 35 is not changed. The irradiation area of the multi-opening 33 is adjusted. Since the molded lens 34 can be provided with a function as a rotation correction lens by being disposed behind the multi-aperture 34, a correction lens 54 is provided so that the molded lens 34 and the correction lens 54 are on the opposite axis. Generate a magnetic field.

  The chromatic aberration correction lens 37 is a quadrupole correction magnetic field generation lens 53 for correcting aberrations, which is disposed in a direction in which the positions of the four-stage quadrupole lenses and these lens electrodes are deviated from the 45 ° azimuth direction. The chromatic aberration correction lens 37 generates negative axial chromatic aberration. The chromatic aberration correction lens 37 may use the Wien filter shown in FIGS. 1A and 1B, and it is preferable to correct not only axial chromatic aberration but also spherical aberration.

  The objective lens 42 includes a magnetic lens 80 having an annular coil centered on the optical axis, a pipe-shaped cylindrical electrode 44 disposed along the central axis of the magnetic lens, that is, the optical axis, and 8-pole scanning. It has a deflector / dynamic focus electrode 43 and a conical earth potential magnetic pole 75 whose radius decreases toward the sample side. A magnetic gap 46 is formed on the sample side between the outer magnetic pole 81 and the inner magnetic pole 75. In order to focus the primary electron beam and reduce axial chromatic aberration and spherical aberration, the voltage adjustment power supply 47 applies a positive high voltage to the cylindrical electrode 44. The magnetic poles 81 and 75 are always grounded. For this reason, the electric field strength on the surface of the sample 45 can be kept small despite the positive high voltage applied to the cylindrical electrode 44. For example, if the distance between the cylindrical electrode 44 and the sample is 4 mm and the voltage of 44 K is 8 KV, an electric field of 8 KV / 4 mm = 2 KV / mm is applied to the sample surface if there is no ground potential outside, but the outer potential is the ground potential. Then, it has become clear through simulation that the value is reduced to about 1.5 KV / mm. Therefore, dielectric breakdown of the sample surface does not occur, and discharge between the cylindrical electrode 44 and the sample 45 is prevented. Further, since a high voltage is applied to the cylindrical electrode 44, the longitudinal chromatic aberration of the objective lens 42 is kept small. In order to make the absolute value of the positive axial chromatic aberration generated by the objective lens 42 exactly coincide with the absolute value of the negative chromatic aberration generated by the chromatic aberration correction lens 37, the objective lens 42 can be electrically controlled by a voltage adjusting power supply 47. It has become. That is, in order to increase the longitudinal chromatic aberration of the objective lens, the voltage applied from the voltage adjusting power supply 47 to the cylindrical electrode 44 is lowered. On the other hand, in order to reduce the longitudinal chromatic aberration, the voltage applied to the cylindrical electrode 44 by the voltage adjusting power source 47 may be increased. Compensation for the shift of the focusing condition by changing the voltage applied to the cylindrical electrode 44 is performed by adjusting the excitation current of the objective lens 44 by the voltage adjusting power supply 47. In this embodiment, it is better to correct spherical aberration using a Wien filter. However, since the spherical aberration of the objective lens 42 having a structure in which the magnetic gap 46 is formed on the sample side has a small value, it can be corrected even if the electromagnetic field applied to the Wien filter is small. The electrode 43 is an eight-pole electrode to which a voltage close to the ground potential is applied. By applying the same voltage to the eight-pole electrode, the focal length of the lens can be adjusted at high speed, and dynamic focusing can be performed. Further, by supplying a scanning signal to the beam separator electrostatic deflector 40 and the octupole electrode 43, the multi-beam can be scanned on the sample 45. Since the total residual aberration after correction is small, the aperture angle by the NA aperture 35 can be set to a large value of 100 mrad (milliradian) or more, usually several tens of mrad (milliradian). Therefore, each beam can obtain a large beam current, and the sample can be evaluated with high throughput.

The primary electron beam emitted from the L _a B ₆ cathode gun 31 is focused by the condenser lens 32 and irradiates all the openings of the multi-aperture 33 with uniform intensity. The multi-beam formed by the multi-aperture 33 forms a reduced image at the focal point 38 by the shaping lens 34 and the reduction lens 36. The reduced image formed at the focal point 38 that is suppressed to the low off-axis aberration by providing the NA aperture 35 is formed at the position of the focal point 39 by the on-axis chromatic aberration correction lens 37. This image of the focal point 39 is an image having negative axial chromatic aberration. The reduced image of the focal point 39 is further reduced by the objective lens 42 to form a multi-beam on the sample 45. The multi-beam is scanned on the sample 45 by the electrostatic deflector 40 and the electrode 43. The positive axial chromatic aberration generated by the objective lens 42 is corrected and canceled by the negative axial chromatic aberration generated by the axial chromatic aberration correction lens 37.

  The secondary electron beam emitted from the sample 45 is accelerated and focused by an accelerating electric field formed by the cylindrical electrode 44 provided inside the objective lens 42 and the sample 45, separated from the primary electron beam by the electromagnetic deflector 41, and a magnifying lens. 48 and 50 are expanded in two stages. The secondary electron beam is detected by the detector 52, and a multi-channel SEM image is formed. The electrostatic deflectors 49 and 51 control so that the secondary electron signal from the same primary electron always enters the same detector 52 in synchronization with the scanning of the primary electron beam. The secondary electron image output from the detector 52 is sent to the A / D converter and signal processing circuit 504 and converted into an electronic signal, and this electronic signal is processed by the control device 520 as in the first embodiment. Is done.

  As described above, in the second embodiment of the electron beam apparatus according to the present invention, since a high voltage is applied to the cylindrical electrode 44 of the objective lens 42, the longitudinal chromatic aberration can be reduced and the magnetic pole 75 can be reduced. Is grounded, it is possible to prevent discharge between the cylindrical electrode 44 and the sample 45 despite the high voltage of the cylindrical electrode 44. Further, since the voltage applied to the cylindrical electrode 44 can be adjusted by the voltage adjusting power supply 47, the absolute value of the positive axial chromatic aberration generated by the objective lens is the absolute value of the negative axial chromatic aberration generated by the chromatic aberration correcting lens 37. The axial chromatic aberration can be accurately corrected according to the value. Further, since the residual chromatic aberration is small, it is possible to increase the beam current of each beam with a large aperture angle, so that the sample can be evaluated with high throughput.

Next, an embodiment of a method for manufacturing a semiconductor device by the electron beam apparatus shown in the above embodiment will be described with reference to FIGS.
FIG. 3 is a flowchart showing an embodiment of a semiconductor device manufacturing method according to the present invention. The manufacturing process of this embodiment includes the following main processes.
(1) Wafer manufacturing process for manufacturing a wafer (or wafer preparation process for preparing a wafer) (step 600)
(2) Mask manufacturing process for manufacturing a mask used for exposure (or mask preparation process for preparing a mask) (step 602)
(3) Wafer processing process for performing necessary processing on the wafer (step 604)
(4) Chip assembly process for cutting out chips formed on the wafer one by one and making them operable (step 606)
(5) Chip inspection process for inspecting the assembled chip (step 608)
Each of the main processes described above further includes several sub-processes.

Among these main processes, the wafer processing process (3) has a decisive influence on the performance of the semiconductor device. In this process, designed circuit patterns are sequentially stacked on a wafer to form a large number of chips that operate as memories and MPUs. This wafer processing process includes the following processes.
(A) A thin film forming process for forming a dielectric thin film to be an insulating layer, a wiring portion, or a metal thin film for forming an electrode portion (using CVD, sputtering, etc.)
(B) Oxidation step for oxidizing the thin film layer and wafer substrate (C) Lithography step for forming a resist pattern using a mask (reticle) to selectively process the thin film layer and wafer substrate, etc. (D) Resist pattern Etching process (eg using dry etching technology) to process thin film layers and substrates according to
(E) Ion / impurity implantation / diffusion process (F) Resist stripping process (G) Process for inspecting a processed wafer The wafer processing process is repeated as many times as necessary to manufacture a semiconductor device that operates as designed.

FIG. 4 is a flowchart showing a lithography process which forms the core of the wafer processing process. This lithography process includes the following steps.
(A) A resist coating process for coating a resist on the wafer on which the circuit pattern is formed in the previous process (step 700).
(B) Step of exposing the resist (Step 702)
(C) Development process of developing the exposed resist to obtain a resist pattern (step 704)
(D) An annealing process for stabilizing the developed resist pattern (step 706)
The semiconductor device manufacturing process, wafer processing process, and lithography process are well known and need no further explanation.

  When the defect inspection method and the defect inspection apparatus according to the present invention are used in the inspection process of (G) above, even a semiconductor device having a fine pattern can be inspected with high throughput, so that 100% inspection can be performed and the yield of products can be improved. It becomes possible.

  The above is each embodiment of the present invention, but the present invention is not limited to the above embodiment.

FIG. 1A is a schematic diagram of an electron beam apparatus according to a first embodiment of the present invention. FIG. 1B is a schematic diagram showing a quarter of the cross section of the Wien filter of FIG. FIG. 2 is a schematic view of an electron beam apparatus according to a second embodiment of the present invention. FIG. 3 is a flowchart showing an embodiment of a semiconductor device manufacturing method. FIG. 4 is a flowchart showing a lithography process in the semiconductor device manufacturing method of FIG.

Explanation of symbols

_1: L a _{B 6} cathode gun 2: alignment deflectors,
3: Condenser lens 4: Axis alignment deflector,
5: Molded aperture 6: Molded lens 7: Axis alignment deflector 8: Molded lens 9: Primary electron beam trajectory control deflector 10: Electron beam separator electromagnetic deflector 11-15: Objective lens 12: NA aperture 16: Sample 17 : Electrostatic deflector 18: Image point 19: Chromatic aberration correction lens 20: Auxiliary lens 21: Magnifying lens 22, 26, 27: Auxiliary lens 23: Magnifying lens 24: MCP 25: Excitation coil 26: Electrode and magnetic pole 27: Permalloy core 28: Insulating spacer 29: Tightening screw 30: Primary electron beam orbit 31: L _a B ₆ cathode gun
32: Condenser lens 33: Multi-aperture
34: Molded lens 35: NA aperture
36: Reduction lens 37: Axial chromatic aberration correction lens
38: Focus 39: Focus
40: Electrostatic deflector 41: Electromagnetic deflector for electron beam separator
42: Objective lens
43: Scanning deflector and dynamic focus electrode 44: Cylindrical electrode 45: Sample 46: Lens gap 47: Voltage adjustment power supply 48: Magnifying lens 49: Axis alignment deflector 50: Magnification lens 51: Axis alignment deflector 52: Detector 53 : 4-pole magnetic pole 54: Auxiliary lens 75: Ground potential magnetic pole

Claims (10)

A sample to which a negative voltage is applied is irradiated with an electron beam, secondary electrons emitted from the sample are accelerated by an electric field created by the objective lens and the sample, and the secondary electrons are transmitted by an electron beam separator having at least an electromagnetic deflector. An electron beam device that directs the line towards the detector,
The electron beam apparatus includes an objective lens that irradiates the sample with the electron beam focused.
The objective lens has at least one conical electrode whose radius decreases toward the sample side, and an axially symmetric electrode;
2. The electron beam apparatus according to claim 1, wherein the axisymmetric electrode is a substantially grounded electrode disposed closer to the sample side than the conical electrode, and is disposed at a position where the electric field strength on the sample surface is reduced. The electron beam apparatus according to claim 1,
The electron beam device further includes a multipole lens that generates negative axial chromatic aberration, and a voltage control device,
The voltage control device adjusts the voltage of the axially symmetric electrode, or adjusts both the voltage of the axially symmetric electrode and the voltage of the at least one cone-shaped electrode, so that the axial chromatic aberration of the objective lens is reduced. An electron beam apparatus, wherein an absolute value is made equal to an absolute value of axial chromatic aberration of the multipole lens. The electron beam apparatus according to claim 1 or 2,
The electron beam apparatus according to claim 1, wherein the axisymmetric electrode is a disk-shaped or conical electrode. The electron beam apparatus according to claim 2 or 3,
The objective lens further includes a conical electrode for focus adjustment,
The conical electrode for focus adjustment is disposed on the opposite side of the sample of the at least one conical electrode, and the voltage applied to the electrode by the voltage control device is adjusted to adjust the voltage. An electron beam apparatus for correcting a change in focal length due to a change in voltage of an axially symmetric electrode. A sample to which a negative voltage is applied is irradiated with an electron beam, secondary electrons emitted from the sample are accelerated by an electric field created by the objective lens and the sample, and the secondary electrons are transmitted by an electron beam separator having at least an electromagnetic deflector. An electron beam device that directs the line towards the detector,
The electron beam apparatus includes an objective lens that irradiates the sample with the electron beam focused.
The objective lens has at least one electrode and a ground electrode,
2. The electron beam apparatus according to claim 1, wherein the ground electrode is disposed at a position where the electric field intensity on the sample surface is reduced. The electron beam apparatus according to claim 5,
The electron beam apparatus, wherein the at least one electrode is a cylindrical electrode. The electron beam apparatus according to claim 5 or 6,
The electron beam device further includes a multipole lens that generates negative axial chromatic aberration, and a voltage control device,
The voltage control device adjusts a voltage applied to the at least one electrode so that an absolute value of axial chromatic aberration of the objective lens is equal to an absolute value of axial chromatic aberration of the multipole lens. An electron beam device. The electron beam apparatus according to claim 7,
The objective lens is a synthetic lens of an electromagnetic lens and an electrostatic lens,
The electron beam apparatus according to claim 1, wherein the electromagnetic lens corrects a focal length by changing a voltage applied to the electrostatic lens by the voltage controller. The electron beam apparatus according to claim 7,
The objective lens further includes another electrode.
An electron beam characterized in that the voltage control device adjusts a voltage applied to the another electrode so that the other electrode corrects a change in focal length due to a change in voltage of the at least one electrode. apparatus. A method of manufacturing a device,
The method
a. Preparing a wafer;
b. Performing the wafer process;
c. Evaluating the wafer after the wafer process using the apparatus according to any one of claims 1 to 6;
d. Repeating the steps b and c as many times as necessary;
e. Cutting the wafer and assembling it into a device.

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