JP2005235777A - Inspection apparatus and method by electron beam, and device manufacturing method using the inspection apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve an inspection speed detecting a failure of a sample of a wafer, etc. <P>SOLUTION: An inspection apparatus by an electron beam is one of a mapping projection type and comprises: a primary electron optical system for forming the electron beam emitted from en electron gun into a rectangle and irradiating onto a face of a sample to be inspected; a secondary electron optical system for converging secondary electrons emitted from the sample; a detection device for converting the converged secondary electrons into an optical image through a fluorescent plate to image them to a line sensor; and a control device for controlling charge moving time to transfer the line image which is imaged in a pixel string provided with the line sensor, cooperatively with the moving speed of a stage to move the sample. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an inspection apparatus for inspecting a defect or the like of a pattern formed on the surface of an inspection object such as a wafer by using an electron beam, and more specifically, in the case of detecting a defect of a wafer in a semiconductor manufacturing process. Image data is formed from the amount of secondary electrons that change according to the surface properties by irradiating the beam to the inspection object, and patterns and the like formed on the surface of the inspection object are inspected with high throughput based on the image data. The present invention relates to an inspection apparatus, an inspection method, and a device manufacturing method for manufacturing a device with high yield using such an inspection apparatus.

  In the semiconductor process, the design rule is about to reach the age of 100 nm, and the production form is shifting from small-quantity mass production represented by DRAM to high-variety small-quantity production such as SOC (Silicon on chip). Along with this, the number of manufacturing processes has increased, and it has become essential to improve the yield of each process, and defect inspection due to processes has become important. Conventionally, a wafer defect inspection is performed after each step in a semiconductor process. Along with higher integration of semiconductor devices and miniaturization of patterns, a defect inspection apparatus with high resolution and high throughput is required. This is because a resolution of 100 nm or less is required in order to investigate a defect of one wafer of a 100 nm design rule. In addition, the amount of inspection increases due to an increase in the number of manufacturing processes due to high integration of semiconductor devices, and thus high throughput is required. Further, as the number of semiconductor devices increases, the defect inspection apparatus is also required to have a function of detecting a contact failure (electrical defect) of a via that connects wirings between layers.

  Conventionally, optical defect inspection apparatuses have been used as this type of defect inspection apparatus. However, in the optical defect inspection apparatus, the resolution is limited to 1/2 of the wavelength of the light to be used, and is about 0.2 μm in the case of visible light that has been put into practical use. As described above, the optical defect inspection apparatus has a problem that the resolution cannot keep up with the demand. Furthermore, in the optical defect inspection apparatus, it is impossible to inspect the electrical continuity failure (open, short failure, etc.) generated in the semiconductor wafer, that is, contact failure inspection.

Therefore, a defect inspection apparatus using an electron beam has recently been developed in place of the optical defect inspection apparatus.
In such an electron beam system defect inspection apparatus, a scanning electron beam system (SEM system) is generally put into practical use, and its resolution is relatively high at 0.1 μm, and electrical defects (disconnection of wiring, Insufficient conduction, via conduction failure, etc.) can also be inspected. However, in the defect inspection apparatus using SEM, there is a limit to the beam current amount and the response speed of the detector, which requires a lot of time for defect inspection. For example, the inspection time takes 8 hours / piece (20 cm wafer), the inspection time is very long, and the throughput (inspection amount per unit time) is higher than that of other process equipment such as optical defect inspection equipment. There is a problem that it is low. Also, the electron beam type defect inspection apparatus is very expensive. Therefore, it is in a difficult state to use after each process of semiconductor manufacturing. At present, after an important process, for example, after etching, film formation (including copper plating), or CMP (chemical mechanical polishing) planarization treatment Etc. are used.

  A defect inspection apparatus using such a scanning electron beam system (SEM system) will be further described. In such a defect inspection apparatus, the electron beam is narrowed down (this beam diameter corresponds to the resolution) and scanned. Irradiate a sample such as a wafer in a line. On the other hand, by moving the stage on which the wafer is placed in a direction perpendicular to the scanning direction of the electron beam, the observation region on the wafer is irradiated with the electron beam in a planar shape. The scanning width of the electron beam is generally several 100 μm. Secondary electrons are generated from a sample such as a wafer by irradiation of the narrowed electron beam (referred to as a primary electron beam), and the secondary electrons are detected by a detector (scintillator + photomultiplier (photomultiplier)) or a semiconductor system. Detector (PIN diode type, etc.). The coordinates of the irradiation position of the electron beam and the amount of secondary electrons (signal intensity) are combined to form an image and stored in a storage device, or an image is output on a CRT (CRT). The above is the principle of SEM (scanning electron microscope), and a defect in a semiconductor (usually Si) wafer in the process is detected from an image obtained by this method. The inspection speed (corresponding to the throughput) is determined by the amount of primary electron beam (current value), the beam diameter, and the response speed of the detector. The beam diameter is 0.1 μm (which may be considered to be the same as the resolution), the current value is 100 nA, and the response speed of the detector is 100 MHz. In this case, as described above, one wafer having a diameter of 20 cm is used. It takes about 8 hours of inspection time. As described above, the scanning electron beam type defect inspection apparatus has a serious problem that the inspection speed is extremely slow (1/20 or less) compared to other process apparatuses such as an optical type defect inspection apparatus. Yes.

  The present invention has been made in view of such problems, and an object thereof is to improve the inspection speed for detecting defects in a sample such as a wafer.

  The present invention relates to a defect inspection apparatus using a method called a mapping projection method using an electron beam as a method for improving the inspection speed, which is a drawback of the scanning electron beam method (SEM method). The mapping projection method will be described below.

  In the mapping projection method, the observation area of the sample is irradiated with a primary electron beam at once (irradiation of a certain area without scanning), and secondary electrons generated from the irradiated area are collectively processed by a lens system. An image of an electron beam is formed on a detector (microchannel plate + fluorescent plate). The formed image is converted into an electrical signal by a two-dimensional CCD (solid-state image sensor) or a TDI-CCD (line image sensor), and is output as image information on a CRT or stored in a storage device. From this image information, a defect of the sample wafer (semiconductor (Si) wafer in the process) is detected. In the case of a CCD, the moving direction of the stage is the short axis direction (the long axis direction may be sufficient), and the movement is a step-and-repeat method. In the case of TDI-CCD, the stage is moved continuously in the integration direction. Since images can be continuously acquired with TDI-CCD, TDI-CCD is used when performing defect inspection continuously. The resolution is determined by the magnification and accuracy of the imaging optical system (secondary optical system), and in some experimental examples, a resolution of 0.05 μm is obtained. In this experimental example, when the resolution is 0.1 μm, the inspection time on the wafer is 200 μm × 50 μm, and the amount of primary electron beam (current value) is 1.6 μA with respect to the electron beam irradiation conditions. Was about 1 hour per 20 cm wafer. That is, in the mapping projection method, an inspection speed that is eight times as high as that of the SEM method is obtained. The specification of the TDI-CCD used in this experimental example was 2048 pixels (pixels) × 512 stages, and the line rate was 3.3 μs (line frequency 300 kHz).

Although the irradiation area in this example matches the specification of TDI-CCD, the irradiation area may be changed depending on the irradiation object.
Further, an outline of an electron beam inspection apparatus using a mapping projection method will be described.

  This electron beam inspection apparatus forms an electron beam emitted from an electron gun into a desired shape (for example, a rectangle or an ellipse), and a sample to be inspected (for example, a wafer or a mask) A primary electron optical system that collectively irradiates the surface of the wafer (which is often described below as a wafer), a secondary electron optical system that irradiates the detector with secondary electrons emitted from the wafer, and an optical system that receives the secondary electrons. A detector for converting the image into an image and forming an image of the wafer and a control device for controlling the detector are provided. The primary electron optical system includes an electron gun that emits an electron beam and a primary electrostatic lens that shapes the electron beam into a beam having a predetermined cross-sectional shape. The primary electron optical system has a certain angle with respect to the direction perpendicular to the surface of the wafer, and is arranged in order with the electron gun at the top. Between the primary electron optical system and the secondary electron optical system, an E × B deflector (Wien filter) for deflecting an electron beam by a field in which an electric field and a magnetic field are orthogonal to each other and separating secondary electrons from a wafer. Or an E × B separator) is arranged along a direction perpendicular to the surface of the wafer S. The secondary electron optical system is arranged in a direction perpendicular to the surface of the wafer along the optical axis of the secondary electrons from the wafer separated by the E × B separator, and deflects the secondary electrons. A secondary electrostatic lens that converges.

As the electron gun, a thermionic beam source type that emits electrons by heating an electron emitting material (cathode) is used. Lanthanum hexaboride (LaB ₆ ) is used as an electron emission material (emitter) as a cathode. Other materials can be used as long as the material has a high melting point (low vapor pressure at high temperature) and a small work function. As the cathode of lanthanum hexaboride (LaB ₆ ), a cathode having a conical shape is used, but a truncated cone having a truncated cone may be used. The diameter of the tip of the truncated cone is about 100 μm. As another method, a field emission type electron beam source or a thermal field emission type electron beam source is used, but a relatively wide area (for example, 100 × 25 to 400 × 100 μm ² ) as in the present invention. Is irradiated with a large current (about 1 μA), a thermoelectron source using LaB ₆ is optimal. In the SEM method, a thermal field emission type electron beam source is generally used. Of course, in this embodiment, a field emission type electron beam source or a thermal field emission type electron beam source may be used instead of the thermal electron beam source. The thermal field emission electron beam source is a system in which electrons are emitted by applying a high electric field to the electron emission material, and the electron beam emission part is heated to stabilize the electron emission.

  The primary electron optical system forms a primary electron beam irradiated from an electron gun and forms the primary electron beam in a desired shape, for example, a rectangle or a circle (ellipse). A portion that irradiates the wafer surface with a primary electron beam (ellipse). By controlling the conditions of the lens provided in the primary electron optical system, the beam size of the primary electron beam and the current density of the primary electron beam can be controlled. Moreover, the direction of the primary electron beam is changed by the E × B filter (Wien filter) provided at the connecting portion between the primary electron optical system and the secondary electron optical system, and can be incident on the wafer perpendicularly.

The electron gun is further provided with a Wehnelt, triple anode lens, gun aperture, and the like. Thermoelectrons emitted from the cathode composed of LaB ₆ are imaged as a crossover image on the gun stop by the Wehnelt and triple anode lenses.

  The primary electron optical system is further provided with an illumination field stop for optimizing the incident angle of the primary electron beam to the lens and an NA stop. A primary electron beam whose angle of incidence on the lens is optimized by the illumination field stop is controlled to form an image on the NA stop in a rotationally asymmetric manner by controlling the primary electrostatic lens, and then is irradiated onto the wafer surface. The subsequent stage of the primary electrostatic lens is composed of a three-stage quadrupole (QL) and a single-stage aperture aberration correcting electrode. Although the quadrupole lens has a limitation that alignment accuracy is severe, it has a feature that has a stronger convergence effect than a rotationally symmetric lens, and an aperture aberration equivalent to the spherical aberration of the rotationally symmetric lens is applied to the aperture aberration correction electrode. Then, correction can be performed. Thereby, a uniform surface beam can be irradiated to a predetermined area.

  The secondary electron optical system includes an electrostatic lens (CL) corresponding to an objective lens, an intermediate lens (TL), a field stop (FA) position, and a subsequent lens provided on the detector side with respect to the field stop position. (PL). In this way, the two-dimensional secondary electron image generated by the electron beam irradiated on the wafer is formed at the field stop position by the electrostatic lens (CL) corresponding to the objective lens and the intermediate lens (TL). And is enlarged and projected by a lens (PL) at the rear stage. This imaging projection optical system is called a secondary electron optical system.

  It is preferable that a negative bias voltage (deceleration electric field voltage) is applied to the wafer. The deceleration electric field has the effect of decelerating the irradiation beam, reducing sample damage, and accelerating secondary electrons generated from the sample surface due to the potential difference between the electrostatic lens (CL) and the wafer to reduce chromatic aberration. Has the effect of The electrons converged by the electrostatic lens (CL) are imaged on the field stop (FA) by the intermediate lens (TL), and the image is enlarged and projected by the lens (PL) at the subsequent stage, and on the microchannel plate (MCP). Make an image. In this optical system, a numerical aperture (NA) is arranged between the electrostatic lens CL and the intermediate lens TL, and an optical system capable of reducing off-axis aberrations is configured by optimizing the numerical aperture NA.

  In addition, an electrostatic octupole stigmator (for correcting astigmatism and anisotropy magnification of an image generated by passing through an E × B filter (Wien filter) and an electron optical system) is corrected. STIG) is arranged to perform correction, and axial deviation is corrected by a deflector (OP) arranged between the lenses. As a result, a mapping optical system with a uniform resolution within the field of view can be achieved.

  The E × B deflector is an electromagnetic prism optical system unit in which electrodes and magnetic poles are arranged in an orthogonal direction, and an electric field and a magnetic field are orthogonalized. When an electromagnetic field is selectively applied, the electron beam incident on the field from one direction is deflected, and the electron beam incident from the opposite direction is canceled by the influence of the force received from the electric field and the force received from the magnetic field. (Vienna condition) can be created, whereby the primary electron beam is deflected and irradiates vertically onto the wafer, and the secondary electron beam can travel straight towards the detector.

  A secondary electron image from the wafer imaged by the secondary optical system is first amplified by a microchannel plate (MCP) and then converted to an image of light by hitting a fluorescent screen. The principle of MCP is a bundle of millions of very thin conductive glass capillaries having a diameter of 6 to 25 μm and a length of 0.24 to 1.0 mm, which are shaped into a thin plate and applied with a predetermined voltage. Thus, each capillary functions as an independent secondary electron amplifier, and forms a secondary electron amplifier as a whole.

  The image converted into light by this detector is projected on the TDI-CCD on a one-to-one basis in a relay optical system that is placed in the atmosphere through a vacuum transmission window or also serves as a vacuum feedthrough.

Next, in order to clarify the relationship between the main functions of the mapping projection method and the overall image thereof, a mapping projection type electron beam inspection apparatus according to an embodiment of the present invention will be specifically described.
FIG. 1 shows an overall configuration diagram of a projection type electron beam inspection apparatus according to the present embodiment. However, a part of the configuration is omitted.

  In FIG. 1, the electron beam inspection apparatus has a primary column 1, a secondary column 2, and a chamber 3. An electron gun 4 is provided inside the primary column 1, and a primary optical system 5 is disposed on the optical axis of an electron beam (primary beam) emitted from the electron gun 4. A stage 6 is installed inside the chamber 3, and a sample W is placed on the stage 6.

  On the other hand, in the secondary column 2, on the optical axis of the secondary beam generated from the sample W, the cathode lens 8, the numerical aperture 9, the Wien filter 10, the second lens 11, the field aperture 12, and the third lens are arranged. 13, a fourth lens 14 and a detector 15 are arranged. The numerical aperture 9 corresponds to an aperture stop, and is a thin plate made of metal (such as Mo) having a circular hole. The aperture is arranged so as to be the primary beam focusing position and the focal position of the cathode lens 8. Therefore, the cathode lens 8 and the numerical aperture 29 constitute a telecentric electron optical system.

  On the other hand, the output of the detector 15 is input to the control unit 16, and the output of the control unit 16 is input to the CPU 17. A control signal from the CPU 17 is input to the primary column control unit 18, the secondary column control unit 19, and the stage drive mechanism 7. The primary column control unit 18 controls the lens voltage of the primary optical system 5, and the secondary column control unit 19 applies the lens voltage control of the cathode lens 8, the second lens 11 to the fourth lens 14 and the Wien filter 10. Perform electromagnetic field control.

  The stage drive mechanism 7 transmits stage position information to the CPU 17. Further, the primary column 18, the secondary column 19, and the chamber 3 are connected to an evacuation system (not shown), and are evacuated by a turbo pump or the like of the evacuation system, so that the inside is maintained in a vacuum state.

The primary beam from the electron gun 4 is incident on the Wien filter 10 while receiving a lens action by the primary optical system 5. Here, LaB ₆ that can extract a large current with a rectangular cathode is used as the tip of the electron gun. The primary optical system 5 uses a non-rotationally symmetric quadrupole or octupole electrostatic (or electromagnetic) lens. This can cause convergence and divergence in the X and Y axes, respectively. This lens is composed of two stages and three stages, and by optimizing each lens condition, the beam irradiation area on the sample surface is shaped into an arbitrary rectangular or elliptical shape without irradiating irradiation electrons. be able to.

Specifically, when an electrostatic lens is used, four cylindrical rods (quadrupoles) are used. Opposing electrodes are equipotential, and opposite voltage characteristics are given.
In addition, as a quadrupole lens, a lens having a shape obtained by dividing a generally used circular plate into four by an electrostatic deflector may be used instead of a cylindrical shape. In this case, the lens can be reduced in size. The orbit of the primary beam that has passed through the primary optical system 5 is bent by the deflection action of the Wien filter 10. The Wien filter 10 orthogonally crosses the magnetic field and electric field, and when the electric field is E, the magnetic field is B, and the velocity of the charged particles is v, only the charged particles that satisfy the Wien condition of E = vB travel straight. Bend the trajectory. For the primary beam, a force FB caused by a magnetic field and a force FE caused by an electric field are generated, and the beam trajectory is bent. On the other hand, for the secondary beam, since the force FB and force FE work in opposite directions, they cancel each other, so the secondary beam goes straight.

  The lens voltage of the primary optical system 5 is set in advance so that the light source image is formed at the opening of the numerical aperture 9. That is, Koehler illumination referred to as an optical microscope is realized. This numerical aperture 9 prevents an extra electron beam scattered in the apparatus from reaching the sample surface and prevents charge-up and contamination of the sample W.

When the sample is irradiated with the primary beam, secondary electrons, reflected electrons, or backscattered electrons are generated as a secondary beam from the beam irradiation surface of the sample.
The secondary beam passes through the lens while receiving the lens action of the cathode lens 8.

  Incidentally, the cathode lens 8 is composed of three electrodes. The lowermost electrode is designed to form a positive electric field with respect to the sample W, draw secondary electrons, and efficiently guide the sample into the lens.

  The lens action is performed by applying a voltage to the first and second electrodes of the cathode lens 8 to bring the third electrode to zero potential. On the other hand, the numerical aperture 9 is disposed at the focal position of the cathode lens 8, that is, the back focus position from the sample W. Therefore, the light beam of the electron beam emitted from the center of the visual field (off-axis) also becomes a parallel beam and passes through the central position of the numerical aperture 9 without being distorted.

  The numerical aperture 9 plays a role of suppressing the lens aberration of the second lens 11 to the fourth lens 14 with respect to the secondary beam. The secondary beam that has passed through the numerical aperture 9 passes straight without passing through the deflection action of the Wien filter 10.

  When the secondary beam is imaged only by the cathode lens 8, chromatic aberration and distortion of magnification are likely to occur. Therefore, one image formation is performed together with the second lens 11. The secondary beam obtains an intermediate image on the field aperture 12 by the cathode lens 8 and the second lens 11. In this case, since the magnification magnification necessary for the secondary optical system is usually insufficient, the third lens 13 and the fourth lens 14 are added as lenses for enlarging the intermediate image. The secondary beam is enlarged and imaged by the third lens 13 and the fourth lens 14 respectively, and here, the secondary beam is imaged three times in total. Note that the third lens 13 and the fourth lens 14 may be combined and imaged once (total twice).

  The second lens 11 to the fourth lens 14 are all rotational axis symmetric lenses called unipotential lenses or Einzel lenses. Each lens has a configuration of three electrodes. Usually, the outer two electrodes are set to zero potential, and the lens action is performed with a voltage applied to the center electrode. A field aperture 12 is disposed at an intermediate image point. As with the field stop of the optical microscope, the field aperture 12 limits the field of view to the necessary range, but in the case of an electron beam, the extra beam is blocked together with the third lens 13 and the fourth lens 14 in the subsequent stage, Noise generation and contamination of the detector 15 are prevented. The magnification is set by changing the lens condition (focal length) of the third lens 13 and the fourth lens 14.

  The secondary beam is enlarged and projected by the secondary optical system, and forms an image on the detection surface of the detector 15. The detector 15 includes a micro channel plate (MCP) that amplifies electrons, a fluorescent plate that converts electrons into light, a relay between the vacuum system and the outside, and lenses and other optical systems for transmitting optical images, and imaging It is comprised from an element (CCD etc.). The secondary beam forms an image on the MCP detection surface and is amplified, and the electrons are converted into an optical signal by the fluorescent plate and converted into a photoelectric signal by the imaging device.

  The control unit 16 reads the image signal of the sample from the detector 15 and transmits it to the CPU 17. The CPU 17 performs a pattern defect inspection from the image signal by template matching or the like. The stage 6 can be moved in the XY directions by a stage drive mechanism 7. The CPU 17 reads the position of the stage 6, outputs a drive control signal to the stage drive mechanism 7, drives the stage 6, and sequentially performs image detection and inspection.

  Further, for the secondary beam, all the principal rays from the sample W are incident on the cathode lens 8 perpendicularly (parallel to the optical axis of the lens) and pass through the numerical aperture 9, so that ambient light is also lost. And the image brightness at the periphery of the sample does not decrease. Further, a so-called magnification chromatic aberration occurs where the imaging position differs depending on the energy variation of the electrons (particularly, the secondary electron has a large magnification chromatic aberration due to the large energy variation), but the focal position of the cathode lens 8 Further, the chromatic aberration of magnification can be suppressed by arranging the numerical aperture 9.

  In addition, since the enlargement magnification is changed after passing through the numerical aperture 9, even if the setting magnification of the lens conditions of the third lens 13 and the fourth lens 14 is changed, a uniform image is formed on the entire field of view on the detection side. can get. In this embodiment, a uniform image with no unevenness can be obtained. However, usually, when the enlargement magnification is increased, the brightness of the image is lowered. Therefore, in order to improve this, when changing the magnification condition by changing the lens conditions of the secondary optical system, the effective field of view on the sample surface determined accordingly, and the electron beam irradiated on the sample surface, The lens conditions of the primary optical system are set so that they have the same size.

  In other words, if the magnification is increased, the field of view is narrowed accordingly, but at the same time, by increasing the irradiation energy density of the electron beam, the signal density of the detected electrons can be increased even if it is enlarged and projected by the secondary optical system. It is always kept constant and the brightness of the image does not decrease.

  Further, in the electron beam inspection apparatus of the present embodiment, the Wien filter 10 that bends the trajectory of the primary beam and travels the secondary beam straight is used. However, the invention is not limited thereto, and the trajectory of the primary beam travels straight. An inspection apparatus using a Wien filter that bends the trajectory may be used. In this embodiment, a rectangular beam is formed from a rectangular cathode and a quadrupole lens. However, the present invention is not limited to this. For example, a rectangular beam or an elliptical beam may be created from a circular beam, or the circular beam may be passed through a slit. The rectangular beam may be taken out.

  The detailed structure of the Wien filter, that is, the electron beam deflecting unit 10 as an E × B deflector will be described with reference to FIG. 2 and FIG. 3 showing a longitudinal section along the line AA in FIG. As shown in FIG. 2, the field of the electron beam deflection unit is a mapping projection optical unit (a one-dimensional image or a two-dimensional image of secondary electrons and reflected electrons generated according to the sample surface when the sample is irradiated with the electron beam. In the plane perpendicular to the optical axis of the portion that forms an image on the electron beam detector, an electric field and a magnetic field are orthogonal to each other, that is, an E × B structure.

Here, the electric field is generated by the electrodes 10-1 and 10-2 having concave curved surfaces. The electric fields generated by the electrodes 10-1 and 10-2 are controlled by the control units 10a and 10d, respectively. On the other hand, the magnetic coils 10-1a and 10-2a are disposed so as to be orthogonal to the electric field generating electrodes 10-1 and 10-2, thereby generating a magnetic field. The electric field generating electrodes 10-1 and 10-2 are point objects. (Concentric circles are also acceptable.)
In this case, in order to improve the uniformity of the magnetic field, a magnetic path is formed by providing a pole piece having a parallel plate shape. FIG. 3 shows the behavior of the electron beam in the longitudinal section along the line AA. The irradiated electron beam 1a is deflected by the electric field generated by the electrodes 10-1 and 10-2 and the magnetic field generated by the electromagnetic coils 10-1a and 10-2a, and then perpendicular to the sample surface. Is incident on.

  Here, the incident position and angle of the irradiated electron beam 1a to the electron beam deflecting unit 10 are uniquely determined when the electron energy is determined. Further, the conditions of the electric field and magnetic field, that is, the electric field generated by the electrodes 10-1 and 10-2 so that vB = E, and the electromagnetic coils 10-1a and 10-2a are The respective control units 10a and 10d, 10c and 10b control the generated magnetic field, so that the secondary electrons travel straight through the electron beam deflection unit 10 and enter the mapping projection optical unit. Here, V is the velocity (m / s) of the electron 2a, B is the magnetic field (T), and E is the electric field (V / m).

Next, another embodiment of the defect inspection apparatus using the mapping projection method will be described.
In the defect inspection apparatus using the mapping projection method, (1) it is easy to charge up on the sample surface to irradiate the electron beam at once, and (2) the electron beam current obtained by this method has a limit ( There was a problem that it hindered the improvement of the inspection speed.

  In this embodiment, a plurality of primary electron beams are used, and the observation region on the sample surface is irradiated while scanning the plurality of primary electron beams in two dimensions (XY direction) (that is, while performing a raster scan). This can be solved by adopting a mapping projection method in the electron optical system. This embodiment has the advantages of the mapping projection method described above, and is a problem of this mapping method. (1) It is easy to charge up on the sample surface in order to collectively irradiate electron beams. (2) This method The fact that there is a limit to the electron beam current obtained in (1), which hinders the improvement of the inspection speed, can be solved by scanning a plurality of primary electron beams. That is, since the electron beam irradiation point moves, the charge easily escapes and the charge-up is reduced. Further, the current value can be easily increased by increasing the number of the plurality of electron beams. In this example, for example, when four primary electron beams were used, one electron beam current was 500 nA (electron beam diameter 10 μm), and a total of 2 μA was obtained. The number of primary electron beams can be easily increased to about 16, and in this case, 8 μA can be obtained in principle. When scanning a plurality of primary electron beams, by irradiating the irradiation area so that the irradiation amount of the plurality of primary electron beams is uniform, not only raster scanning as described above, but also other Lissajous figures, etc. Shape scanning can be performed. Therefore, the scanning direction of the stage need not be perpendicular to the scanning direction of the plurality of electron beams.

As an electron beam source used in this embodiment, a thermionic beam source (a system in which electrons are emitted by heating an electron emitting material) can be used. Again, the electron emission (emitter) material is preferably a LaB _6. Other materials can be used as long as they have a high melting point (low vapor pressure at high temperature) and a low work function. Two methods can be used to obtain a plurality of electron beams. One is a method of obtaining a plurality of primary electron beams by drawing one electron beam from one emitter (one protrusion) and passing it through a thin plate (open plate) having a plurality of holes. The other method is a method in which a plurality of projections are formed on one emitter, and a plurality of primary electron beams are drawn directly therefrom. In either case, the electron beam utilizes the property of being easily emitted from the tip of the protrusion. Other types of electron beam sources such as a thermal field emission type electron beam can also be used. The thermal field emission electron beam source is a system in which electrons are emitted by applying a high electric field to the electron emission material, and the electron beam emission part is heated to stabilize the electron emission.

  Next, while irradiating the observation area of the sample surface while scanning a plurality of primary electron beams in two dimensions (XY direction) (that is, while performing raster scanning), a mapping projection method is adopted for the secondary electron optical system. The above embodiment will be described in more detail with reference to FIGS.

In the following embodiment, as a method for obtaining a plurality of primary electron beams, a method is adopted in which a plurality of projections are formed on a single emitter and a plurality of primary electron beams are directly extracted therefrom.
As shown in FIG. 4, the four electron beams 21 (21-1, 21-2, 21-3, 21-4) emitted from the electron gun 20 are shaped by the opening 50-1, and are arranged in two stages. The lenses 22-1 and 22-2 form an image of an ellipse of 10 μm × 12 μm on the deflection center plane of the Wien filter 23, and are raster-scanned by the deflector 26 in the direction perpendicular to the plane of the drawing. The image is formed so as to uniformly cover a rectangular area of × 0.25 mm. A plurality of electron beams deflected by the E × B 23 as a Wien filter are crossed over by a numerical aperture NA, reduced to 1/5 by a lens 24, covering a sample W of 200 μ × 50 μm, and perpendicular to the sample surface Irradiated and projected so that Four secondary electron beams 25 having information of a pattern image (sample image F) emitted from the sample are enlarged by lenses 24, 27-1, and 27-2, and four as a whole on the MCP 28-1. The image is formed as a rectangular image (enlarged projection image F ′) synthesized by the electron beam 25. The enlarged projection image F ′ obtained by the secondary electron beam 25 is sensitized 10,000 times by the MCP 28-1, converted into light by the fluorescent part 28-2, and the sample is continuously moved by the TDI (Time Delay Integration) -CCD 29. The electric signal was synchronized with the speed, acquired as a continuous image by the image display unit 30, and output on the CRT or the like.

  The electron beam irradiation unit needs to irradiate the sample surface with the electron beam in a rectangular shape with uniform uniformity as much as possible and with less irradiation unevenness. There is a need to. Conventional non-uniformity of electron beam irradiation is about ± 10%, and the non-uniformity of image contrast is large. Further, since the electron beam irradiation current is as small as about 500 nA in the irradiation region, there is a problem that high throughput cannot be obtained. In addition, compared with the scanning electron microscope (SEM) method, this method has a problem in that an image formation failure due to charge-up is likely to occur because a large image observation area is collectively irradiated with an electron beam.

  A primary electron beam irradiation method of this example is shown in FIG. The primary electron beam 21 is composed of four electron beams 21-1, 21-2, 21-3, and 21-4. Each beam has an elliptical shape of 2 μm × 2.4 μm, and each of them is subjected to a raster scan of a rectangular region of 200 μm × 12.5 μm. Irradiate a rectangular area. The beam 21-1 arrives at 21-1 ′ in a finite time, and then returns to the position immediately below 21-1 (21-2 direction) shifted by the beam spot diameter (10 μm) with almost no time loss. In the same finite time, it moves in parallel to 21-1 to 21-1 ′ and directly under 21-1 ′ (21-2 ′ direction), and this is repeated to make a quarter of the rectangular irradiation area indicated by the dotted line in the figure. After scanning (200 μm × 12.5 μm), the process returns to the first point 21-1 and is repeated at high speed. The other electron beams 21-2 to 21-4 are repeatedly scanned at the same speed as the electron beam 21-1, and uniformly irradiate the rectangular irradiation area (200 μm × 50 μm) as a whole at high speed. As long as the irradiation can be performed uniformly, the raster scan may not be performed. For example, scanning may be performed so as to draw a Lissajous shape. Therefore, the moving direction of the stage need not be the direction A shown in the figure. That is, the moving direction of the stage does not have to be perpendicular to the scanning direction (the high-speed scanning direction in the horizontal direction in the figure). In this example, unevenness of electron beam irradiation could be performed at about ± 3%. The irradiation current was 250 nA per electron beam, and 1.0 μA was obtained with four electron beams as a whole on the sample surface (twice as compared with the conventional method). By increasing the number of electron beams, current can be increased and high throughput can be obtained. Further, since the irradiation point is smaller than the conventional one (about 1/80 in area) and moved, the charge-up can be suppressed to 1/20 or less of the conventional one.

  Although not shown in the figure, in addition to the lens, this apparatus includes a limited field stop, a deflector (aligner) having four or more poles for adjusting the axis of the electron beam, astigmatism. A unit necessary for illumination and imaging of an electron beam such as a corrector (stigmator) and a plurality of quadrupole lenses (quadrupole lenses) for shaping the beam shape are provided.

  Next, another embodiment of a projection type electron beam inspection apparatus will be described. The electron beam inspection apparatus according to the embodiment can perform defect inspection of a sample (for example, a wafer or a mask), particularly a wafer having a device pattern with a minimum line width of 0.1 μm or less, with high throughput and high reliability. It is a thing.

First, an outline of the present embodiment will be described.
The mapping projection type electron beam inspection apparatus according to this embodiment forms an electron beam emitted from an electron gun into a rectangular electron beam, irradiates the surface of the wafer with the electron beam, and emits a secondary light emitted from the wafer surface. An electron image is formed on the detector. An electron beam inspection apparatus for defect inspection of such a mapping projection method uses a rectangular or planar beam that is larger than the beam spot diameter of a scanning electron microscope, forms an image of the irradiation area at once, Get an image. Accordingly, it is possible to satisfy the demand for higher throughput than the scanning type. In this apparatus, the stage is continuously moved to scan the entire surface of the wafer, so that secondary electrons emitted from the wafer are converted into an optical image by a fluorescent screen, and the converted image is converted into a line sensor (TDI-). CCD).

  In such a line sensor, as shown in FIG. 9, n CCD pixel columns arranged in a line of C1 to Cn in one axis direction (two directions in the figure) of two orthogonal axes are arranged. A CCD array is configured by arranging m pieces of ROW-1 to ROW-m in other axial directions (vertical direction in the figure). The charge accumulated in each CCD pixel column is transferred by one CCD pixel in the vertical direction at a time by one vertical clock signal from the outside (that is, the charge moves in the direction of arrow E). A line image of n pixels captured by ROW-1 at a certain time is transferred to ROW-2 when a clock signal is given. When a clock signal is subsequently applied, the line image transferred to ROW-2 is further moved by one pixel in the vertical direction and transferred to ROW-3. In this way, following the movement of the image, the charge transfer is repeatedly performed up to ROW-m, and finally it is taken out of the line sensor as image data from the horizontal output register.

  However, when imaging is performed with the charge transfer time (hereinafter referred to as the line rate) of the line sensor being constant, the charge of the line sensor that does not cause a problem in the defect inspection apparatus using the scanning electron microscope system due to fluctuations in the moving speed of the stage. This causes image blur due to asynchronous movement. Furthermore, the magnification mechanism of the electron optical system changes due to the focus mechanism associated with the entire wafer inspection, and the optimum line rate changes because the pixel size on the wafer changes, thereby causing the same image blur.

  One object of the present embodiment is to provide an electron beam inspection apparatus for defect inspection that can always synchronize the line rate of the line sensor with the moving speed of the stage and avoid image blur caused by asynchronous movement of charges. It is.

Another object of the present embodiment is to provide an electron beam inspection apparatus for defect inspection that can avoid image blur due to magnification fluctuation of an electron optical system.
Therefore, in the electron beam inspection apparatus for defect inspection of the projection method according to the present embodiment, the electron beam emitted from the electron gun is formed into a desired shape, and the formed electron beam is to be inspected on the sample surface. A primary electron optical system that irradiates on, a secondary electron optical system that forms an image of secondary electrons emitted from the sample, and the imaged secondary electron image is converted into an optical image via a fluorescent plate; In the projection type electron beam inspection apparatus for defect inspection provided with a detector to be detected by a line sensor, a charge transfer time when transferring a line image captured in a pixel column provided in the line sensor, A control device is provided for controlling in conjunction with the moving speed of the stage for moving the sample. By detecting the moving speed of the stage, calculating the optimum line rate, and feeding it back, the line rate of the line sensor is always synchronized with the moving speed of the stage, and image blur caused by asynchronous charge movement can be avoided. .

  Further, in one modification of the electron beam inspection apparatus according to the present embodiment, the charge transfer time of the line sensor is controlled in conjunction with the fluctuation of the magnification of the electron optical system. Thereby, even when the magnification variation of the electron optical system is caused by the focus mechanism accompanying the wafer whole surface inspection, it is possible to avoid the image blur caused by the asynchronous movement of the charge.

In another modification, in order to double the secondary electrons of the secondary electron optical system, a microchannel plate is disposed in front of the fluorescent plate.
In another modification, a laser interferometer for measuring the position of the stage is provided. As a result, the position information of the stage can be detected from the laser interferometer, the optimum line rate can be calculated from the stage moving speed and fed back, and the line rate of the line sensor can be always synchronized with the stage moving speed, Image blur caused by asynchronous movement can be avoided.

With reference to the drawings, the electron beam inspection apparatus for defect inspection of the projection method according to the present embodiment will be described more specifically below.
FIG. 6 schematically shows an electron beam inspection apparatus 1001 for defect inspection of the present embodiment. This defect inspection electron beam inspection apparatus 1001 forms an electron beam emitted from an electron gun into a desired shape (for example, a rectangle or an ellipse), and a sample (to be inspected) of the formed electron beam. A primary electron optical system 1002 that irradiates the surface of S (for example, a wafer or a mask, hereinafter referred to as a wafer in this embodiment), and a secondary electron optical that enlarges and projects secondary electrons emitted from the wafer S onto a detector. A system 1003, a detector 1004 that receives secondary electrons and converts them into an optical image and further converts them into an electrical signal, and a control device 1005 (FIG. 7) for controlling the detector 1004 are provided.

  The primary electron optical system 1002 includes an electron gun 1022 that emits an electron beam 1021 and a primary electrostatic lens 1023 that shapes the electron beam 1021 into a beam having a predetermined cross-sectional shape, as shown in FIG. They have a certain angle with respect to the direction perpendicular to the surface of the wafer S, and are arranged in order with the electron gun 1022 at the top. The primary electron optical system 1002 further includes an E × B separator 1024 for deflecting an electron beam by a field in which an electric field and a magnetic field are orthogonal to each other and separating secondary electrons from the wafer S, and an electrostatic objective lens 1025. These are arranged along a direction perpendicular to the surface of the wafer S.

  The secondary electron optical system 1003 is arranged in a direction perpendicular to the surface of the wafer S along the optical axis A of the secondary electrons 1031 from the wafer S separated by the E × B separator 1024. A secondary electrostatic lens 1032 for enlarging and projecting secondary electrons is provided.

  The detection device 1004 detects an MCP (microchannel plate) 1041, a fluorescent plate 1042 that converts secondary electrons from the secondary electron optical system into an image of light, and a line sensor 1043 that detects the image of the light. A memory 1044 for storing wafer image information and a CRT monitor 1045 for displaying a wafer image are provided.

  As shown in FIG. 7, the control apparatus 1005 includes a laser interferometer 1051 that measures the position of the stage, an A / D converter 1052 that converts a position signal from the laser interferometer 1051, and a laser interferometer 1051. A line rate control unit 1053 that calculates and outputs an optimum line rate based on the position signal from the signal, a D / A converter 1054 that converts an output signal from the line rate control unit 1053, and a signal from the line rate control unit 1053 And a line sensor control unit 1055 for controlling the line sensor 1043 based on the above.

Each of the above constituent elements may be known ones, and a detailed description of their structure is omitted.
In the electron beam inspection apparatus 100 having the above-described configuration, the electrons emitted from the electron gun 1022 are accelerated and shaped as an electron beam 1021 by the primary electrostatic lens 1023 so that the cross-sectional shape is rectangular or elliptical. The shaped electron beam forms a rectangular or elliptical image slightly above the main deflection surface of the E × B separator 1024. The beam image formed by being incident on the E × B separator 1024 is deflected in a direction perpendicular to the surface of the wafer S, and is reduced and decelerated by the electrostatic objective lens 1025 to irradiate the wafer S.

  The secondary electrons 1031 emitted from the wafer S by the electron beam irradiation are converged by the electrostatic objective lens 1025 and are incident on the E × B separator 1024. The secondary electron beam directed toward the secondary electrostatic lens 1032 by the E × B separator 1024 passes through the secondary electrostatic lens 1032 and is further enlarged and projected onto the MCP 1041.

  The secondary electrons 1031 incident on the MCP 1041 are multiplied there to irradiate the fluorescent screen 1042. The secondary electrons 1031 irradiated to the fluorescent plate 1042 are converted into a light image there. This image is detected by the line sensor 1043 and converted into an electrical signal. The wafer image data converted into the electrical signal is stored in the memory 1044 of the personal computer as wafer image information via an optical fiber cable. This wafer image information is displayed on the CRT monitor to detect defects.

  Next, the operation of the control device 1005 will be described with reference to FIGS. The wafer S to be inspected is disposed on the XY stage 1006. When the wafer is inspected by the method described above, the XY stage 1006 is moved in the Y direction at a constant speed, and the line rate calculated from the XY stage driving speed and the pixel size on the wafer is a constant. Is set in the line sensor control unit 1055, and an image of the line sensor 1043 is displayed on the CRT monitor 1045. If the synchronization is not achieved, several striped patterns are generated due to the non-synchronization between the stage speed perpendicular to the stage scanning direction and the line rate synchronized with the speed variation of the XY stage, resulting in image blurring. .

  In order to eliminate such image blur due to the stripe pattern, the control device 1005 performs the following control. The movement position of the XY stage 1006 is measured by a laser interferometer, and the serial output signal is converted into a digital signal by an A / D converter 1052 at a clock frequency of 200 MHz and 16 bits, and the current stage position information Xt is obtained. The data is output to the line rate control unit 1053. At the same time, the position information Xt-1 and the delay time of the previous cycle are also input to the line rate control unit 1053. The line rate control unit 1053 calculates the speed component of the stage from the position information and the delay time, calculates the optimum line rate from the speed component of the stage and the pixel size on the wafer, and outputs these information signals. To do. This output signal is converted to an analog signal by a D / A converter 1054 at a clock frequency of 200 MHz and 16 bits, and is input to the line sensor control unit 1055. The line rate of the line sensor 1043 is controlled by a signal from the line sensor control unit 1055. The line rate of the line sensor 1043 can be updated by a command from the line sensor control unit 1055 to avoid image blurring. In this case, the time delay of the entire control device 1005 including input and output is sufficiently small, whereas the vibration cycle of the XY stage is sufficiently longer than several microseconds.

  The wafer was actually inspected using the electron beam inspection apparatus according to this example. In FIG. 8, the upper left inspection start point S2 of the wafer inspection area S1 of about 130 mm × 130 mm is first moved to the center of the irradiation area of the electron beam 1021, and then the XY stage 1006 is moved in the + Y direction at 10 mm / sec. The wafer was inspected. Therefore, the wafer inspection area S1 is inspected in the direction of arrow B. Next, after moving the XY stage 1006 in the -X direction, the XY stage 1006 is moved stepwise by about 500 microns in the -X direction. Therefore, the wafer inspection area S1 is moved in the direction of arrow C. Next, the wafer was inspected while moving the XY stage 1006 in the -Y direction. In this case, the wafer inspection area S1 is inspected in the direction of arrow D. In this way, the entire surface of the wafer inspection area S1 was inspected while repeating scanning.

  When scanning was performed while moving the XY stage 1006 from the inspection start point S2 in the + Y direction at a stage speed of 10 mm / sec, the fluctuation of the stage speed displacement of about ± 10% was repeated every 2.5 milliseconds. In this case, a line rate having a frequency near 300 kHz was able to obtain a good image with no image blur by repeating the vibration synchronized with the speed displacement of the stage by the line rate control unit 1053.

  Also, when scanning was performed while moving the XY stage 1006 in the -Y direction at a stage speed of 10 mm / sec, the same stage speed displacement was shown as when scanning was performed in the + Y direction. A good image could be obtained by performing the above.

According to the present embodiment, the following effects can be obtained.
(1) By feeding back the optimum line rate signal calculated by the line rate control unit to the external input of the line sensor control unit that controls the line rate of the line sensor, the line rate of the line sensor is moved by the XY stage. It is always synchronized with the speed, and image blur caused by the charge transfer delay of the line sensor can be avoided.
(2) Even when the magnification change of the electron optical system occurs due to the automatic focusing mechanism accompanying the wafer whole surface inspection, the optimum line rate signal calculated by the line rate control unit is fed back to the external input of the line sensor control unit. In addition, it is possible to avoid image blur caused by asynchronous charge transfer.
(3) It is possible to actively control image blur due to the line sensor accompanying the vibration of the XY stage or the speed fluctuation of the XY stage drive motor.

Next, another embodiment of a projection type electron beam inspection apparatus will be described. The electron beam inspection apparatus according to the embodiment relates to a multipurpose electron beam inspection apparatus.
First, a related technique of the electron beam inspection apparatus of the projection type according to the present embodiment will be described.

  A projection type electron beam inspection apparatus generally has one electron beam irradiation unit. In this case, if the electron beam is irradiated obliquely with respect to the sample surface and the electron beam is taken out from the direction perpendicular to the sample surface, there is a problem that shadows are generated due to the unevenness of the sample surface. Filter) to deflect the electron beam in an oblique direction so that it is incident on the sample surface in a vertical direction, while secondary electrons from the sample are taken out from the sample surface in a vertical direction so as not to be deflected. The electric field and magnetic field strengths are set.

  FIG. 10 is a block diagram showing a configuration of a mapping projection type electron beam inspection apparatus 2034 of a related technique. This electron beam inspection apparatus 2034 detects an electron gun 2001 that irradiates a sample 2110 with a primary electron beam 2102, detects secondary electrons 2111 generated from the surface of the sample by irradiation of the primary electron beam 2102, and generates an image signal. 2114, a Wien filter 2105 having an electrode 2106 and a magnet 2107, a first lens system 2003 and a second lens system 2004 for molding the primary electron beam 2102, and a third lens system disposed between the Wien filter 2105 and the sample 2110. 2108, a fourth lens system 2109, and a sixth lens system 2112 and a seventh lens system 2113 disposed between the Wien filter 2105 and the detection unit 2114. In this electron beam inspection apparatus, the Wien filter 2105 is set so as to deflect the primary electron beam 2102 irradiated from the electron gun 2001 but the secondary electron 2111 emitted from the sample surface goes straight, and the irradiated primary electron beam 2102. Is vertically incident on the sample surface. Such an apparatus is disclosed in, for example, Japanese Patent Application Laid-Open No. 11-132975.

  Such an electron beam inspection apparatus has a single function. As the wafer size increases to 8 inches, 12 inches, and 15 inches, the floor area of the electron beam inspection apparatus increases, and various inspections and measurements are performed. Since it is necessary, there is a problem that the ratio of the floor area of the electron beam inspection apparatus to the clean room increases.

  One object of the present embodiment is to provide an electron beam inspection apparatus having a plurality of functions with a single electron beam inspection apparatus, and to enable inspection of a wafer during the process with a small number of electron beam inspection apparatuses. Another object of the present embodiment is to reduce the proportion of the floor area of the electron beam inspection apparatus in the clean room of the semiconductor manufacturing facility by providing an electron beam inspection apparatus having a plurality of functions. Other objects and advantages of the present embodiment will be clarified in the following description.

  Therefore, in the electron beam inspection apparatus for defect inspection of the projection method according to the present embodiment, the state of the sample surface is inspected by irradiating the sample with the primary electron beam and detecting secondary electrons generated from the sample surface. A multi-purpose electron beam inspection apparatus, an electron source that generates a primary electron beam, a lens system that shapes the primary electron beam, an optical system that scans the primary electron beam, a sample stage that supports the sample, and a secondary electron It has an optical system that goes to the detector, and a detector that detects secondary electrons and generates an image signal. Among the sample surface defect detection, sample surface defect review, pattern line width measurement, and pattern potential measurement It has at least two functions. The two functions can be sample surface defect detection and sample surface defect review.

  In the multipurpose electron beam inspection apparatus according to the present embodiment, the defect detection on the sample surface is performed by comparing the image obtained by the image signal with the pattern data or by comparing the images of the dies, and the defect review on the sample surface is performed. The pattern line width measurement is performed by observing the image obtained by scanning the beam on the monitor in synchronization with the scanning of the primary electron beam on the wafer surface, and the scanning of the primary electron beam on the wafer surface is performed in the short side direction of the pattern. The secondary electron image obtained at that time is used for pattern potential measurement, and a negative potential is applied to the electrode closest to the sample surface, and the secondary electrons emitted from the pattern having a high potential on the sample surface are selectively sampled. Can be done by driving back to the side.

  The multipurpose electron beam inspection apparatus according to the present embodiment, which inspects the state of the sample surface by irradiating the sample with a primary electron beam and detecting secondary electrons generated from the sample surface, And a lens system that can be shaped into at least two of the spots, a primary electron optical system having a deflection system for scanning an electron beam in an arbitrary direction, and a secondary electron emitted from the sample is detected from the sample surface And a function for automatically detecting a defect and a function for outputting position information of the defect, and a function for allowing the shape of the defect to be observed. The detection system can include a mapping projection optical system. The detection system may include a secondary electron multiplier.

  The combination of the multi-purpose electron beam inspection apparatuses according to the present embodiment is such that a plurality of the multi-purpose electron beam inspection apparatuses are arranged in one or more rows, and the samples on the common sample stage can be inspected by sharing the sample stages. To do. Further, each of the multipurpose electron beam inspection apparatuses can irradiate a sample with a plurality of primary electron beams. Such a combination can increase the throughput of the inspection process (inspection amount per unit time).

Hereinafter, the multipurpose electron beam inspection apparatus for defect inspection according to the present embodiment will be described more specifically with reference to the drawings.
FIG. 11 is a schematic diagram showing a multipurpose electron beam inspection apparatus 2030. The electron beam inspection apparatus 2030 includes a lens barrel 2028 that houses an electron gun 2001 that generates a primary electron beam 2102 and a shield case 2029 that covers a lower portion of the lens barrel 2028. The shield case 2029 accommodates the wafer (sample) 2110, communicates with the lower part of the lens barrel, and is evacuated and evacuated in the same manner as in the lens barrel. The lens barrel 2028 has an electron gun 2001, condenser lenses 2002, 2003, and 2004 for irradiating the surface 2110 with the primary electron beam 2102, a rectangular opening 2005, a circular opening 2006, lenses 2024 and 2025, and a deflector 2007. , Wien filter 2009, lens system 2012, 2010, 2015, 2017 acting on secondary electrons emitted from wafer surface 2110 irradiated with the primary electron beam, microchannel plate 2018, scintillator 2018 ′, and optical fiber bundle 2019 are accommodated. . When the shield case 2029 is made of stainless steel, it is necessary to separately shield the magnetic field. When the shield case 2029 is made of a ferromagnetic material, the magnetic shield can be eliminated.

  In the electron beam inspection apparatus 2030, the primary electron beam 2102 emitted from the electron gun 2001 passes through condenser lenses 2002, 2003, and 2004, a rectangular opening 2005, a circular opening 2006, lenses 2024 and 2025, a deflector 2007, a Wien filter 2009, and the like. As a result, the wafer (sample) surface 1110 is irradiated. The primary electron beam 2102 emitted from the electron gun 2001 is converged by condenser lenses 2002, 2003, and 2004, and irradiates the rectangular opening 2005 or the rear circular opening 2006 with uniform intensity. In the apparatus of FIG. 11, by adjusting the lenses 2024 and 2025, a reduced image of the rectangular opening 2005, a reduced image of the circular opening 2006, or a reduced image of crossover can be selectively formed on the wafer surface 2110. Further, by operating the deflector 2007, the primary electron beam 2102 can be scanned on the wafer surface.

  In the electron beam inspection apparatus 2030 of FIG. 11, the image of the wafer surface is created as follows. That is, secondary electrons emitted from the wafer surface 2110 irradiated with the primary electron beam 2102 are imaged on the microchannel plate 2018 through the lens systems 2012, 2010, 2015, and 2017, and are then scintillator 2018 ′ on the rear surface. It is converted into an image of light, taken out to the outside by optical fiber bundles 2019 and 2020, converted into an electric signal by a two-dimensional CCD 2027, and an image is created. Compare this created image with pattern data (automatic pattern alignment procedure) or compare images created at the same location on adjacent dies (ie, adjacent chips arranged on the same wafer), By comparing the dies (defect comparison processor), it is possible to automatically detect the defect and output the defect position (defect post-processor). As described above, the electron beam inspection apparatus 2030 has a function of a mapping projection type electron beam inspection apparatus.

  In the electron beam inspection apparatus 2030 of FIG. 11, the luminance modulation of the monitor 2023 is performed as follows. That is, by applying a specific voltage to the lens 2012 adjacent to the wafer surface 2110, the secondary electron trajectory 2014 is directed to the secondary electron multiplier 2021 adjacent to the edge of the wafer surface, and the secondary electrons are secondary electrons. Amplified by the multiplier 2021, the obtained electric signal is amplified by the amplifier 2022 and used for luminance modulation of the monitor 2023.

  In the electron beam inspection apparatus 2030 in FIG. 11, observation of defects on the wafer surface can also be performed as follows. That is, the deflector 2007 is operated to scan the beam of the monitor 2023 in synchronization with the scanning of the primary electron beam 2102 on the wafer surface 2110, and the obtained image, that is, the SEM image and the image by the pattern data are compared. To observe defects on the wafer surface. As described above, the electron beam inspection apparatus 2030 also has a function of an electron beam inspection apparatus using a scanning electron beam method (SEM method). Therefore, by operating the deflector 2007 and scanning the primary electron beam on the wafer surface in the rectangular or rectangular pattern, for example, in the short side direction, the secondary electron image obtained by the monitor 2023 is used along the long side direction. The line width of the arranged patterns can be measured.

  In addition, even when the electron beam inspection apparatus 2030 is used as a mapping projection method or a scanning electron beam method, a negative potential is applied to the electrode 2012a closest to the wafer of the lens 2012 adjacent to the wafer surface 2110. By selectively repelling secondary electrons emitted from the pattern with a high potential on the wafer surface to the wafer side, the potential of the pattern is evaluated, and electrical continuity failure (open) , Short-circuit failure, etc.), that is, contact failure can be inspected more accurately.

The control device 2900 can switch between the mapping projection method and the scanning electron beam method of the electron beam inspection apparatus 2030.
Since the multi-purpose electron beam inspection apparatus of this embodiment can perform multi-purpose inspection and measurement such as defect detection, defect review, pattern line width measurement, and pattern potential measurement with a single apparatus as described above, Therefore, a large number of device manufacturing apparatuses can be arranged and effective use of the clean room can be achieved.

  Next, another embodiment of a projection type electron beam inspection apparatus will be described. The electron beam inspection apparatus according to the embodiment relates to an electron beam inspection apparatus suitable for performing shape observation and defect inspection of a high-density pattern having a minimum line width of 0.1 microns or less with high accuracy and high reliability. is there.

  As described above, with the increase in the density of semiconductor devices, it becomes necessary to inspect defects on the surface of a substrate such as a semiconductor wafer with high precision, and as a response to this, a projection type electron beam inspection apparatus has been proposed. ing. This projection type electron beam inspection device irradiates the surface of a sample with a primary electron beam from an electron gun, thereby forming a secondary electron beam generated from the sample on a microchannel plate and multiplying electrons. The scintillator converts an electron beam into light representing its intensity, detects it with a TDI-CCD, converts it into an electrical signal, and synchronizes this electrical signal with the scanning of the sample, thereby obtaining a continuous image. is there.

  However, in such a projection type electron beam inspection apparatus, it is necessary to accurately match the moving direction of the stage with the arrangement direction of the light receiving surface of the TDI-CCD. Depends on the mechanical accuracy of However, in recent apparatuses that are intended for shape observation and defect inspection of 0.1 μm or less, there is a problem that it is difficult to achieve the required accuracy with the related technology.

  The present embodiment makes it possible to achieve a highly accurate alignment between the scanning direction of the sample and the arrangement direction of the TDI-CCD light receiving surface, which could not be achieved with mechanical accuracy, and enables reliable shape observation and An object of the present invention is to provide an electron beam inspection apparatus capable of performing defect inspection.

  Therefore, in the electron beam inspection apparatus for defect inspection of the projection method according to the present embodiment, an electron irradiation unit that irradiates the sample with a primary electron beam, and secondary electrons generated from the sample by irradiation with the primary electron beam An optical system that optically processes lines to generate an image of the sample, a microchannel plate that receives the image, and an output of the microchannel plate is converted into light by a scintillator, and then the optical signal is converted into an electrical signal. A CCD for conversion, an image display unit for processing the output of the CCD, and a stage for moving the sample. In the electron beam inspection in which the sample is scanned by the stage, the sample, the microchannel plate, In between, a magnetic lens for rotating the image is arranged.

The magnetic lens may be positioned between a final lens of the optical system and the microchannel plate.
The magnetic lens may be disposed at a crossover position closest to the microchannel plate.

The magnetic lens may be disposed at an imaging position closest to the final lens on the side opposite to the microchannel plate with respect to the final lens.
FIG. 12 is a diagram schematically showing the configuration of the electron beam inspection apparatus according to the present embodiment, and the electron beam inspection apparatus is realized as a mapping projection type electron beam inspection apparatus. In the figure, the electron beam inspection apparatus includes an electron gun 3001, and a primary electron beam 3002 emitted from the electron gun 3001 is shaped by a rectangular opening, passes through two stages of lenses 3003 and 3004, an electrode 3005, a magnet 3006, Is incident on a Wien filter 3007. At this time, the primary electron beam 3002 is imaged on the surface of the Wien filter 3007 with, for example, a 1 mm × 0.25 mm square. The path of the primary electron beam 3002 is changed by the Wien filter 3007, passes through the lenses 3008 and 3009, is reduced to 1/5, and is projected vertically onto the sample 3010 on the stage S. The sample 3010 is a wafer, for example, and a circuit pattern is formed on the surface thereof.

  Irradiated by the primary electron beam 3002, a secondary electron beam is emitted from the surface of the sample 3010, and a part of the primary electron beam 3002 is reflected by the surface of the sample 3010. These reflected electron beam and secondary electron beam 3011 include information representing a circuit pattern on the sample 3010. The secondary electron beam 3011 passes straight through the Wien filter 3007 via the lenses 3009 and 3008, and passes through the lenses 3012 and 3013 of the electrostatic lens system via a path deviated from the path of the primary electron beam 3002. Secondary electron beam 3011 is magnified by lenses 3009, 3008, 3012, and 3013.

  The secondary electron beam 3011 emitted from the last lens 3013 of the electrostatic lens system passes through the magnetic lens 3014 and then forms a rectangular image on the microchannel plate 3015. The reason why the magnetic lens 3014 is disposed here will be described later. The formed rectangular image is sensitized 10,000 times by the microchannel plate 3015 and irradiates the fluorescent portion 3016. Thereby, the fluorescent unit 3016 converts the sensitized rectangular image into light, and the converted light irradiates the TDI-CCD 3018 through the relay optical system 3017. Therefore, the TDICCD 3018 converts the incident light into an electrical signal synchronized with the scanning speed at which the sample 3010 is scanned by the moving stage, and provides the image processing unit 3019 as a continuous image.

  The image thus acquired by the image processing unit 3019 is used for detecting defects on the surface of the sample 3010 by comparing the images of a plurality of cells or comparing the images of a plurality of dies on time. The feature, number, position coordinates, etc. of the shape of the defect on the sample 3010 detected by the image processing unit 3019 are displayed and recorded on the CRT as necessary.

  In the above-described sample surface shape observation and defect inspection, considering that the substrate of the sample 3010 may be an oxide film or a nitride film, for example, the surface structure is different, or the manufacturing process is different. It is desirable to irradiate the sample 3010 with charged particles under appropriate conditions, perform irradiation under optimal irradiation conditions, obtain an image, and perform shape observation and defect inspection.

Further, not only secondary electrons but also images by scattered electrons and reflected electrons can be acquired as described above. Here, a case where a secondary electron image is acquired is described.
Here, the principle of operation of the magnetic lens 1304 shown in FIG. 12 will be described with reference to FIG. The magnetic lens 1304 has an annular shape when viewed from above, and has a cross-sectional shape that represents a U-shape on the left and right. FIGS. 13A and 13B show only the central portion of the magnetic lens 1304. FIG. As shown in FIGS. 13A and 13B, when the secondary electron beam 3011 passes through the center of the pole piece of the magnetic lens 3014, it is between the upper pole piece 3021a and the lower pole piece 3021b. A magnetic path is formed through the upper and lower pole pieces by an annular coil (not shown) arranged, and a magnetic field is applied to the secondary electron beam 3011, whereby the secondary electron beam 3011 is connected to the secondary electron beam 3011. It is rotated in the direction indicated by arrow 3022 with respect to the optical axis center. The amount of rotation of the secondary electron beam 3011 at this time increases as the magnetic field applied to the secondary electron beam 3011 through the pole pieces 3021a and b increases.

  Using this principle, for example, the magnetic lens 3014 is disposed between the lens 3013 and the microchannel plate 3015, and the secondary electrons emitted from the sample 3010 are adjusted by adjusting the strength of the magnetic field generated by the magnetic lens 3014. The image when the line 3011 forms an image on the microchannel plate 3015 can be rotated. Therefore, by adjusting the magnetic field strength of the magnetic lens 3014, the scanning direction when the sample 3010 is scanned by the moving stage S can be matched with the integration direction of the light receiving surface of the TDI-CCD 3018.

  Further, when the magnetic lens 3014 is disposed between the last lens 3013 of the electrostatic lens system and the microchannel plate 3015, the influence is exerted on the electrostatic lens system (for example, the magnification of the electrostatic lens system is changed). The secondary electron beam 3011 can be rotated by the magnetic lens 3014, and thus the formed image can be rotated.

In fact, as shown in FIG. 12, when the magnetic lens 3014 is disposed between the last stage lens 3013 and the microchannel plate 3015, the scanning direction of the sample 3010 and the arrangement direction of the light receiving surface of the TDICCD 3018 are mechanically preliminarily set. After adjusting within ± 1 degree, the rotation angle of the secondary electron beam was measured by changing the magnetic field intensity of the magnetic lens 3014, and it was found that the secondary electron beam could be rotated within an angle of ± 10 seconds. . This is because the angle accuracy only needs to satisfy the relationship of (field size / 2) × (angle accuracy) <(1/10) × (pixel size), and therefore the angle accuracy <(1/2048 × 5) rad = 9.77 × 10 ⁻⁵ rad = 20.2 seconds.

  The magnetic lens 3014 described above is preferably arranged at the position shown in FIG. In FIG. 14, as described above, the magnetic lens 3014 is disposed at the crossover position 3031 closest to the lens 3013 between the lens 3013 at the final stage of the electrostatic lens system and the microchannel plate 3015. As a result, the rotational action of the magnetic lens 3014 on the secondary electron beam can be used, and the influence on the focusing condition of the electrostatic lens system of the projection system can be made almost negligible.

  On the other hand, in FIG. 15, the magnetic lens 3014 is disposed at an imaging position 3041 closest to the lens 3013 on the side opposite to the microchannel plate 3015 with respect to the last lens 3013 of the electrostatic lens system. The imaging position 3041 is a position conjugate with the surface of the sample 3010 and the secondary electron beam incident surface of the microchannel plate 3015, and is a position where any lens action other than the rotating action of the magnetic lens 3014 does not work. For this reason, the magnetic lens 3014 only corrects the deviation between the scanning direction of the sample 3010 and the arrangement direction of the light receiving surface of the TDI-CCD 3018. In other words, the deviation in the direction can be easily corrected by the magnetic lens 3014. Further, since the electrostatic lens system of the mapping projection system is not affected by the rotating action of the magnetic lens 3014 and does not cause aberrations or distortions, an accuracy equal to or better than the arrangement shown in FIG. 14 is achieved. Can do.

  As described above, as can be understood from the description of the electron beam inspection apparatus according to the present embodiment, this embodiment can easily match the scanning direction of the sample and the arrangement direction of the light receiving surface of the TDI-CCD. It is possible to eliminate or minimize image blur caused by these direction mismatches, and to enable highly reliable shape observation and defect inspection with excellent resolution of 0.1 micron or less. The effect of.

  In this embodiment, even if the number of stages of TDI-CCD is increased, image blur due to inconsistency between the scanning direction of the sample and the arrangement direction of the TDI-CCD light receiving surface is small. It can be used, and an electron beam inspection with higher sensitivity can be provided. Therefore, an effect that a high throughput can be realized is also achieved.

  Next, another embodiment of the electron beam inspection apparatus will be described. This example relates to an electron beam inspection apparatus that evaluates the surface of a solid sample using a single or a plurality of electron beams, and in particular, evaluates samples such as wafers and masks having a pattern with a minimum line width of 0.1 μm or less. The present invention relates to an electron beam inspection apparatus that performs with high throughput (processing amount per hour), high accuracy, and high reliability. Evaluation items include defect inspection of a sample such as a semiconductor wafer, line width measurement, overlay accuracy measurement, potential contrast measurement with high time resolution, and the like. The potential contrast measurement enables measurement of electrical defects below the wafer surface and fine particles on the wafer surface.

  In this embodiment, the dimension D of the electron beam means the diameter dimension (diameter or diagonal length) of the image of the electron beam on the sample surface. In the present embodiment, the interval between electron beams means the distance between the centers of adjacent images on the sample surface of adjacent electron beams.

First, the related technique of the electron beam inspection apparatus according to the present embodiment will be described.
This type of electron beam inspection apparatus for evaluating defects or the like of a sample to be evaluated on a wafer is disclosed, for example, in Japanese Patent Laid-Open No. 9-311112. This publication discloses a pattern inspection apparatus that uses a secondary electron from a sample to be inspected by irradiating a sample to be inspected, such as a mask or a wafer, with a primary electron beam. In the related art, a deceleration electric field is applied between the objective lens and the sample to be inspected, the primary electron beam is narrowed down and irradiated on the sample to be inspected, and secondary electrons from the sample to be inspected are detected with high efficiency. Yes. Further, the potential contrast of the pattern on the surface of the sample is measured using a secondary electron energy filter made of a hemispherical mesh.

  The decelerating electric field type objective lens used in this type of related technology passes all secondary electrons, so it is difficult to measure the potential contrast. In addition, the secondary electron filter composed of a hemispherical mesh electrode has a problem that if the mesh electrode is provided between the objective lens and the sample, the image plane distance of the objective lens becomes long, and the axial chromatic aberration coefficient becomes large. Cannot be narrowed down, or there is a problem that the beam current becomes small when trying to narrow down. Further, since the mesh electrode irregularly bends the trajectory of the primary electron beam passing through the vicinity of the mesh, there is a problem that the beam is blurred or scanning distortion occurs.

  The purpose of the present embodiment is made in view of such problems of the related art. A large beam current can be obtained while narrowing down the primary electron beam, potential contrast can be measured, and scanning distortion can be reduced. There is no electron beam inspection to provide.

  The electron beam inspection of this example is performed by using a single potential electrostatic lens having at least three axisymmetric electrodes, that is, an electrode closer to the electron gun (upper electrode), and an electrode closer to the sample (sample side electrode, lower side). Electrode) and a central electrode between them, the primary electron beam is focused on the sample surface by the electrostatic lens, and the secondary electron generated from the sample is detected by scanning the primary electron beam with the deflector. The surface is evaluated. In the electron beam inspection, a potential contrast of a pattern on the sample surface is obtained by applying a lower voltage to the lower electrode than the sample surface.

  In the electron beam inspection of the present embodiment, when an evaluation that does not require obtaining a potential contrast is performed, a voltage close to ground is applied to the sample side electrode (lower electrode). In addition, the adjustment of the focusing condition when the voltage applied to the lower electrode is greatly changed is performed by changing the positive high voltage applied to the center electrode.

  In the electron beam inspection of the present embodiment, when the focusing condition is slightly changed at high speed, the voltage applied to the electron gun side electrode (upper electrode) from the central electrode of the electrostatic lens is adjusted. In this embodiment, a contrast image is obtained by a change in the generation of secondary electrons from the sample surface to which a potential distribution is given.

  Hereinafter, the specific contents of the present embodiment will be described in detail with reference to the drawings. FIG. 16 is a schematic diagram illustrating a schematic configuration of the electron beam inspection according to the present embodiment. As shown in FIG. 16, the electron gun 4020 includes a cathode 4022 disposed inside the Wehnelt 4021 and an anode 4023 disposed below the Wehnelt 4021. A primary electron beam is emitted from the cathode 4022 toward the anode 4023. Then, the electron beam that has passed through the anode 4023 is aligned by the alignment deflectors 4024 and 4025 and passes through the centers of the condenser lenses 4034, 4035, and 4036.

  When the cathode 4022 is a thermal field emission cathode (TEF cathode), the primary electron beam emitted from the cathode 4022 has its imaging magnification on the sample surface adjusted by condenser lenses 4034, 4035, and 4036, and primary electrons. A line 4016 is focused on the surface of the sample 4033 by the objective lenses 4032, 4038, and 4039. The primary electron beam 4016 forms a crossover at the deflection center of the E × B separator 4030 and is deflected in two stages by the electrostatic deflector 4027 and the internal electromagnetic deflector 4029 of the E × B separators 4029 and 4030, Raster scan is performed on the surface of 4033.

  In the electron beam inspection of FIG. 16, the inspection of the sample is performed by continuously scanning the stage 4041 in the y direction while scanning a predetermined width in the x direction of the surface of the sample 33 (perpendicular to the paper surface in FIG. 16) with the primary electron beam. It is done by moving. When the inspection of the sample to the end in the y direction (a certain area) is completed, the stage 4041 is moved in the x direction by a predetermined width or a slightly larger width, and the adjacent stripe (adjacent area) is inspected. When the primary electron beam 4016 irradiates the surface of the sample 4033 by raster scanning, secondary electrons are emitted from the scanning point of the sample 4033.

  Secondary electrons emitted from the irradiation point on the sample 4033 are formed by the high voltage of the central electrode 4039 of the objective lens 4031, the ground voltage of the upper electrode 4038 and the lower electrode 4032, and the negative high voltage of the sample 4033. It is pulled up to the electron gun side by the acceleration electric field for the secondary electrons, deflected from the primary optical system by the E × B separators 4029 and 4030, takes the trajectory in the direction of the dotted line in FIG. 16, and is detected by the secondary electron beam detector 4028 Then, an SEM image (scanning electron microscope image) is formed. When evaluating the potential contrast of the sample 4033, by applying a voltage having a potential lower than the sample potential to the sample-side electrode 4032 of the objective lens 4031, the axial potential distribution is made lower than the surface of the sample as shown in FIG. To be. A control device 4900 shown in FIG. 16 can apply a voltage having a desired potential to the upper electrode 4038, the center electrode 4039, and the lower electrode 4032.

  FIG. 18 shows on-axis potential distributions when 4.5 kV, 8 kV, 350 V, and 500 V are applied to the upper electrode 4038, the center electrode 4039, the lower electrode 4032, and the sample 4033, respectively. In FIG. 18, the horizontal axis represents the distance of the Z axis, that is, the axis extending perpendicularly to the surface of the sample 4033, and the reference point of 0 mm is a line extending vertically from the upper electrode 4038 toward the axis. It is an intersection with the axis. Therefore, 4.000 mm in the figure indicates the distance from the intersection. Although not shown in FIG. 18, the sample 4033 is disposed at a position corresponding to the point 4002, and the lower electrode 4032 is disposed at a position corresponding to the center position between the points 4001 and 4002. The central electrode 4039 is disposed at a position corresponding to the point 4003. Since a lower voltage than the sample potential is applied to the lower electrode 4032, the axial potential is lower than the surface of the sample 33 in the range of points 4001 and 4002 in FIG. A secondary electron generated from a pattern having a high potential is driven back to the sample side by the potential barrier between the points 4001 and 4002 and is not detected because the potential energy is low and the velocity is low. On the other hand, a secondary electron generated from a pattern having a low potential has a higher potential energy and a higher speed, and thus reaches the detector 28 across this potential barrier.

  When a potential lower than that of the sample is applied to the sample side (lower) electrode 4032, a large electric field is generated between the central electrode 4039 and the lower electrode 4032, and therefore between the upper electrode 4038 and the central electrode 4039. It is better to make it wider. Further, since the electric field between the center electrode 4039 and the lower electrode 4032 becomes large, the lens action becomes too strong, and the focusing condition is greatly deviated. In order to correct this, the positive high voltage applied to the center electrode 4039 is largely changed to give a lower voltage.

  The lens structure (condenser lenses 4034, 4035, 4036) in the electron beam inspection of FIG. 16 is made by cutting out from an integrated ceramic 4026, and selectively forming a metal on the surface to form a mirror. The outer diameter of the tube 4040 can be reduced. FIG. 17 shows a state in which lens barrels 4040 having a reduced outer diameter are arranged in 4 cylinders × 2 rows. In the example of FIG. 17, eight lens barrels 4040 are arranged on an 8-inch wafer so that the secondary electron detector 4028 faces the side that does not interfere with the adjacent optical system. When the evaluation is performed while moving the sample stage 4041 in the y direction by the arrangement of the eight lens barrels 4040 in FIG. 17 (when each outer diameter is 40 mmφ or less), the case where a single lens barrel 4040 is used is evaluated. Eight times the throughput (processing amount per hour) can be obtained.

  In the case where an image is created based on the pattern level difference or material difference of the sample 4033, it is preferable that the secondary electron detection efficiency is large. In that case, a potential close to ground may be applied to the sample-side electrode 4032. The voltage applied to the center electrode 4039 at that time is a positive high voltage. In addition, when dynamic focusing is performed in order to respond to unevenness on the surface of the sample, the voltage applied to the upper electrode 4038 having a voltage close to ground is adjusted. In this case, the control voltage can be changed at high speed.

  The electron beam inspection apparatus according to the present embodiment has been described as a scanning electron beam type (SEM type) electron beam inspection apparatus. However, the characteristic part of the present embodiment is also applicable to a mapping projection type electron beam inspection apparatus. Is possible.

  In the electron beam inspection apparatus of this embodiment, the image plane distance of the objective lens is increased by applying a voltage having a lower potential than the sample surface to the electrode closer to the sample of the electrostatic lens having three axisymmetric electrodes. There is no problem that the axial chromatic aberration coefficient becomes large or the primary electron beam cannot be narrowed down. In this case, the focusing of the primary electron beam on the sample surface is adjusted and held by changing the positive high voltage applied to the center electrode. When it is not necessary to obtain potential contrast, secondary electrons can be detected efficiently by applying a voltage close to ground to the electrode on the side close to the sample.

  Next, another embodiment of the present invention will be described. In this embodiment, a charged beam apparatus that irradiates an electron beam as a charged beam onto a sample placed on a stage (hereinafter simply referred to as a stage) movable in a two-dimensional or three-dimensional direction, and on the stage The present invention relates to a method for transporting a sample.

First, the related technology of the charged beam apparatus according to the present embodiment will be described.
In this type of electron beam apparatus that irradiates a specimen placed on a stage with a charged beam, the entire stage is placed in a vacuum vessel because the entire path of the charged beam needs to be in a vacuum environment. It is installed in. Also, in order to make the stage function in a vacuum, special considerations are required for the stage actuator, the guide support structure, lubrication, materials, and the like, unlike when the stage is operated in the atmosphere.

  For example, regarding the actuator, when the servo motor is placed in a vacuum, it is difficult to dissipate heat, so it may be necessary to set the servo motor to a high temperature specification or to limit the specification conditions of the servo motor, or to lubricate the rotating shaft. Solid lubricant or vacuum grease must be used. On the other hand, when the servo motor is arranged on the atmosphere side, a vacuum seal mechanism such as a magnetic fluid seal is provided at the rotation introduction part, and another stage guide is provided on the stage in addition to the X direction and Y direction guides. It is necessary to make the structure that does not require the servo motor to move with the guide in the X direction or the Y direction, and the structure is more complicated and larger than the stage that operates in the atmosphere.

  Regarding the support structure of the guide portion, an air bearing using a static pressure as used for a high-precision stage used in the atmosphere cannot be used in a vacuum environment. In addition, when using high-precision rolling bearings such as cross roller bearings, vacuum grease that is inferior to lubricants used in the atmosphere or fluorine-based lubricants with low vapor pressure are used as lubricants. I had to. For this reason, it has been difficult to produce a high-precision stage for vacuum.

  Regarding the material of the stage, it is necessary to select a material that emits a small amount of gas in a vacuum. Aluminum material is not often used, and special consideration is given to the finish of the part surface in order to reduce the surface area of the material. Needed.

  In addition to the above, the vacuum stage mechanism includes a vacuum container with a built-in stage, a load lock chamber for transferring the sample from the atmosphere to the vacuum environment, a sample vacuum transfer mechanism, a vacuum pipe for the vacuum container, Valves, a vacuum pump, etc. were required.

  In addition, since the sample is placed in a vacuum, a vacuum chuck that is fixed by adsorption force cannot be used as a method of fixing the sample, and an electrostatic chuck or a mechanical chuck that presses the surface or side of the sample with a stator. Had to use. However, electrostatic chucks are expensive and easy to adsorb particles, and some types of electrostatic chucks require time for static elimination. On the other hand, mechanical chucks can be held flat. In addition to this, there is a problem that the surface or side surface of the sample must be pressed by a stator and the semiconductor manufacturer's requirement that the chuck does not want to contact other than the back surface of the sample wafer cannot be satisfied.

  As described above, the related charged beam apparatus requires a stage to be provided in a vacuum environment, so the manufacturing cost of the apparatus is high, a large installation area and an occupied area are required, the mechanism is complicated, and the apparatus is maintained. Management was also difficult.

  Furthermore, in general, when an object exposed to the atmosphere is evacuated, gas molecules adsorbed on the surface are released, so that a certain amount of evacuation time is required to obtain a predetermined degree of vacuum. . Most of the desorbed gas is water molecules (that is, water vapor adsorbed on the surface in the atmosphere) at a high degree of vacuum. Therefore, when the sample exposed to the atmosphere is transferred to the charged beam irradiation region without being sufficiently evacuated, the gas adsorbed on the sample surface as soon as it is transferred into the vacuum environment of the charged beam irradiation region. Conventionally, there has been a problem that molecules are emitted and the degree of vacuum in the charged beam irradiation region is deteriorated, so that it is impossible to perform processing with a predetermined performance. Therefore, it is required to significantly reduce the amount of gas released from the sample surface and the surface of the component parts of the stage into the charged beam irradiation region and to exhaust the released gas quickly.

  One object of the present embodiment is to provide a charged beam apparatus that is compact and can be manufactured at a low manufacturing cost by providing a structure such as an actuator of a stage and a guide mechanism in the atmosphere.

  Another object is to maintain only a portion where a vacuum environment is necessary, such as a sample and a charged beam optical system, so that the sample and the charged beam optical system are not contaminated by particles or emitted gas.

Another object is to provide a charged beam apparatus that can significantly reduce the amount of gas released into the vacuum from the surface of a sample surface or a component of a stage.
Furthermore, another object is to provide a method for transporting a sample into a charged beam apparatus that can significantly reduce the amount of gas released into the vacuum from the surface of the sample surface or the components of the stage. Is to provide.

  In the charged beam apparatus according to the present embodiment, in the apparatus for irradiating the surface of the sample placed on the stage with the charged beam, the charge beam is maintained in order to keep only the vicinity of the portion irradiated with the charged beam at a predetermined degree of vacuum. At least a single differential evacuation structure is provided around the region irradiated with the beam, and a structure for injecting an inert gas toward the sample surface is provided on the outer periphery of the differential evacuation structure. With this configuration, the stage used in the atmosphere can be used, and the charged beam apparatus can be made compact and can be manufactured at a low manufacturing cost. Furthermore, it is possible to prevent particles from entering the sample surface from the atmosphere side, to reduce the chance that the sample directly touches the atmosphere, and to reduce the emitted gas in the charged beam irradiation region.

  In another modification of the charged beam apparatus according to the present embodiment, the structure for ejecting the inert gas is such that the inert gas ejected on the sample surface flows mainly outward in the charged beam irradiation region. Is formed. This facilitates evacuation of the differential evacuation section, and makes it possible to form a differential evacuation structure in a compact manner or to make the differential evacuation vacuum pump have a small capacity.

  In another modification of the charged beam apparatus, the differential exhaust structure includes a differential exhaust passage having a high degree of vacuum and a differential exhaust passage having a low degree of vacuum, and the differential exhaust passage includes the differential exhaust passage. The downstream side of the structure communicates with each other and is exhausted through the same pipe after the communication. The upstream side of the differential exhaust structure has a lower vacuum level than the high-pressure differential exhaust path. The differential exhaust passage is formed so that the exhaust resistance is larger. As a result, the number of differential exhaust passages and / or vacuum pumps can be reduced, and the charged beam device can be reduced in size and cost.

  In another variant of the charged beam device, for further fine adjustment of the stage so that the surface of the stage entering under the differential pumping structure is at the same height as the surface of the sample placed on the stage A height adjustment mechanism is provided. As a result, there is no step between the sample surface and the surface of the stage, and the gap between the differential exhaust section and the stage is maintained constant over the entire movable range of the stage. It is possible to operate normally.

  In another modification of the charged beam apparatus, the entire range in which the stage for moving the sample to a predetermined position moves or the movable range of the sample is always covered with a container filled with an inert gas. With this configuration, particles that enter the sample surface can be further reduced, and the sample surface and stage are not exposed to the atmosphere. It is possible to further reduce the amount.

  In another modification of the charged beam apparatus, a container filled with an inert gas is connected to a vacuum container via a shut-off valve, and a sample is contained in the container filled with the inert gas via the vacuum container. To be in and out. That is, after inserting the sample into the vacuum vessel, the vacuum vessel is evacuated to a predetermined pressure, and then a high-purity inert gas is introduced into the vacuum vessel, and then the shut-off valve is opened to provide a high-purity inert gas. The sample was placed on the stage in the vacuum container filled with gas. With such a configuration and procedure, the sample is first placed in a vacuum vessel and evacuated once, and a large amount of gas is released from its surface to be cleaned, and then a high purity inert gas is introduced into the vacuum vessel. Thus, the sample is transported to the stage in a high purity inert gas. Therefore, even when the sample is inserted into the charged beam irradiation region and placed in a vacuum environment, only a high purity inert gas is released from the surface of the sample. Since the high-purity inert gas has a very small adsorption energy with the surface of the object and is released from the surface of the sample in a very short time, the degree of vacuum in the charged beam irradiation region is not deteriorated. Thus, the charged beam irradiation region can be easily maintained at a high degree of vacuum, and the risk of contaminating the sample surface can be reduced.

In another variant of the charged beam device, the inert gas is jetted to the sample surface so that the inert gas is collected by a vacuum pump and / or compressor and then pressurized and jetted again to the sample surface. A circulation mechanism is provided. As a result, high-purity inert gas can be reused, so that high-purity inert gas can be saved, and since high-purity inert gas is not discharged into the room where this equipment is installed, suffocation by high-purity inert gas, etc. This eliminates the risk of accidents. Here, examples of the inert gas include nitrogen (N ₂ ), argon (Ar), and xenon (Xe).

  Another modification of the present embodiment provides a sample transport method. That is, after preparing a charged beam device in which a vacuum vessel is connected to a vessel filled with an inert gas as described above via a cutoff valve, and after inserting a sample into the vacuum vessel of the charged beam device, The vacuum vessel is evacuated to a predetermined pressure, and after introducing an inert gas into the vacuum vessel, the shutoff valve is opened and the sample is placed on the stage in the vessel filled with the inert gas. And. By such a method, the charged beam irradiation region can be easily maintained at a high degree of vacuum.

  Yet another modification is to provide a wafer defect inspection apparatus for inspecting defects on the surface of a semiconductor wafer by utilizing the invention of the charged beam apparatus or the sample transport method as described above. Thereby, it is possible to provide a highly reliable wafer defect inspection apparatus with a low installation cost and a small installation area.

  Another modification is to provide an exposure apparatus that exposes a circuit pattern of a semiconductor device on the surface of a semiconductor wafer by using the charged beam apparatus or the sample transport method as described above. Thereby, it is possible to provide a charged beam exposure apparatus having a small installation area and a small occupied area and high reliability.

  Another modification is to provide a semiconductor manufacturing method using the charged beam apparatus or the sample transport method as described above. Thereby, cost reduction of a semiconductor manufacturing method can be achieved.

Hereinafter, a charged beam apparatus according to the present embodiment will be described in detail with reference to the drawings.
FIG. 19 is a diagram showing an embodiment of the charged beam apparatus, and shows a part of the charged beam apparatus in an enlarged manner. Reference numeral 5001 denotes a lens barrel having a known structure that houses an optical system for irradiating the sample 5002 with the charged beam 5050, and only its tip is shown. A differential exhaust unit 5004 is attached so as to surround the tip of the lens barrel 5001. The hole 5041 at the center of the differential exhaust unit 5004 needs to have a size that does not affect the charged beam 5050. The sample 5002 is placed on the stage 5003 and moves together with the stage 5003. The lens barrel 5001 is placed on the frame (FIG. 24) of the apparatus so that a minute gap of several microns to several hundred microns is maintained between the differential exhaust unit 5004 and the surface of the sample (hereinafter referred to as sample surface) 5021. It is fixed. Since the optical system in the lens barrel is not the gist of the present invention, detailed description thereof is omitted.

  In the differential exhaust portion 5004, annular grooves 5005 and 5006 for differential exhaust are formed from the center to the outside in the radial direction, and communicated with vacuum pipes 5008 and 5009, respectively. By evacuating the gas flowing in from the outer peripheral side of the differential evacuation unit 5004 toward the charged beam through the annular grooves 5005 and 5006, the flow rate of the gas leaking to the charged beam irradiation region becomes less than an allowable level. And the charged beam region is maintained at a predetermined degree of vacuum. For this reason, the annular groove 5005 has a higher degree of vacuum than the annular groove 5006 and the amount of gas leakage to the charged beam irradiation region is below an allowable level, or the annular groove 5005 has a higher vacuum than the charged beam irradiation region. The shape of the annular groove 5005, the shape of the exhaust channel of the annular groove 5005, the gap 5051 between the sample surface 5021 and the differential exhaust part 5004, the performance of the vacuum piping and the vacuum pump are determined appropriately. The annular grooves for performing differential evacuation constitute a differential evacuation structure, which is formed double in FIG. 19, but is not limited to this, and the degree of vacuum of the charged beam irradiation region and Depending on the configuration of the annular groove, vacuum piping, etc., it may be formed in a single layer, or may be formed in a triple layer or more.

  An annular groove 5007 is further formed on the outer peripheral side of the annular groove 5006 of the differential exhaust portion 5004 and communicates with the pipe 5010. High-purity inert gas is supplied through the pipe 5010 and is ejected from the annular groove 5007 to the sample surface. A part of the jetted high-purity inert gas is sucked by the annular groove 5006 and discharged to the charged beam irradiation region, and the rest flows in the opposite direction and is discharged from the outer periphery of the differential exhaust part. In this way, since the high purity inert gas flows outward and acts as a shield, the atmosphere is not blocked by the flow of the high purity inert gas and does not flow into the charged beam irradiation region. If the shielding mechanism with this high purity inert gas is not provided, particles, water vapor in the atmosphere and the like enter the charged beam irradiation region due to the inflow of outside air, contaminate the sample surface and the lens in the lens barrel 5001, and the like. This may adversely affect the operations such as wafer inspection and pattern exposure onto the wafer. On the other hand, by providing a mechanism for ejecting a high-purity inert gas as in the present invention, entry of particles, water vapor, etc. in the atmosphere is prevented, so that the sample, lens, etc. are not contaminated, and the wafer Inspection, exposure, etc. can be performed without problems.

  As indicated by reference numeral 5004a (FIG. 20), the outer diameter of the differential exhaust section 5004 is extended to the outside, and the area covering the sample surface is increased, thereby providing an effect of making particles and water vapor more difficult to enter. be able to.

  FIG. 20 shows another modification of the charged beam apparatus. In this modification, the direction of the jet outlet 5007a of the high purity inert gas is formed toward the outer peripheral side. Therefore, the gas is in the direction of the arrow A between the sample surface 5021 and the differential exhaust part 5004. It flows out vigorously. The shape of the high-purity inert gas outlet 5007a is formed in this way, and the supply pressure of the high-purity inert gas is increased to an appropriate value with respect to the atmospheric pressure, so that the injection speed of the high-purity inert gas is appropriate. By setting to a small value, the flow of the high purity inert gas acts like an ejector and a flow as shown by arrow B is generated, and the inner diameter side of the differential exhaust section 5004 can be maintained at a negative pressure. it can. As a result, it is possible to further reduce the possibility of entry of contaminants such as particles and water vapor on the outside air side, and the effect of evacuation can be obtained, thereby reducing the load of evacuation in the differential exhaust mechanism. Therefore, the differential exhaust unit 5004, the vacuum pipes 5008 and 5009, and the vacuum pump can be downsized.

  In addition, the differential exhaust unit 5004 is provided with a baking heater BH to heat the differential exhaust unit, and heat and expand the gas flowing from the annular grooves 5005 and 5006 to the vacuum pipes 5008 and 5009 to increase the exhaust efficiency and A high degree of vacuum by evacuation may be achieved more easily.

  FIG. 21 shows another modification of the charged beam apparatus. In this modification, a vacuum chamber 5011 is provided in the differential exhaust section 5004, and the vacuum chamber 5011 communicates with an exhaust passage 5005a on the high vacuum side and an exhaust passage 5006a on the low vacuum side. Further, the high-vacuum-side annular groove 5005 and the low-vacuum-side annular groove 5006 for differential evacuation communicate with the high-vacuum-side exhaust passage 5005a and the low-vacuum-side exhaust passage 5006a, respectively. A vacuum is maintained by a vacuum pipe 5008a.

  The low-vacuum side exhaust passage 5006a is formed to have a very small conductance relative to the high-vacuum side exhaust passage 5005a. Accordingly, the pressures on the downstream side of the respective exhaust passages 5005a and 5006a are the same in the vacuum chamber 5011, but the pressures of the annular grooves 5005 and 5006 on the upstream side are greatly different from each other. The annular groove 5006 maintains a low degree of vacuum and the annular groove 5005 maintains a high degree of vacuum so that differential exhaust can be performed appropriately.

By forming the exhaust passage in this manner, only the vacuum pipe 5008a is required, and the apparatus can be reduced in size and cost.
FIG. 22 shows still another modified example of the charged beam apparatus. FIG. 22a shows a state where the lens barrel is located near one end of the stage, and FIG. 22b shows that the lens barrel is located at the other end of the stage. The state located in the vicinity is shown. In this modification, a sample 5002 is placed on the surface 5031 of the stage, and plate-like members 5060 and 5061 are attached around the sample 5002. The heights of the plate-like members 5060 and 5061 from the surface 5031 of the stage are adjusted so that the upper surfaces 5601 and 5611 of the plate-like members have the same height as the surface 5021 of the sample. By attaching such a height adjustment mechanism, even if the stage moves or the position of the lens barrel with respect to the stage moves to the positions indicated by 5001 ′ and 5001 ″ (FIGS. 22a and 22b), the differential The gap 5051 ′ (or 5051 ″) between the exhaust unit 5004 ′ (or 5004 ″) and the stage surface 5031 or the sample surface 5021 is always kept constant, so that the differential exhaust is appropriately performed and charged. The beam irradiation region can always maintain a predetermined degree of vacuum.

  FIG. 23 shows still another modification of the charged beam apparatus. When many samples having different thicknesses are continuously processed, it is necessary to easily adjust the height according to the thickness of the sample. Therefore, in the present modification, an up-and-down mechanism 5062 is provided under a sample table (in this embodiment, for example, a sample fixing table using an electrostatic chuck) 5063 disposed in the recess 5032 of the stage 5003 to support and fix the sample. ing. By moving the vertical mechanism 5062 up and down in accordance with the height of the sample 5002, the height of the stage surface and the sample surface are adjusted to coincide with each other. The smaller the difference in height between the sample surface and the surface of the stage, the better. For this reason, a fine adjustment mechanism using a piezoelectric element may be provided as the vertical mechanism. When processing a sample having a thickness exceeding the adjustment range of the vertical mechanism, adjustment members 5060 'and 5061' are provided on the side of the sample stage 5063, and the adjustment members are exchanged according to the thickness of the sample. You may do it.

  The adjusting members 5060 ′ and 5061 ′ may be a single component or may be divided into two or more components depending on the shape of the sample and the stage. Further, the adjusting members 5060 ′ and 5061 ′ and the vertical mechanism 5062 only replace parts in accordance with the size of the sample even if the size of the sample changes from an 8-inch wafer to a 12-inch wafer. Therefore, it is desirable to be able to cope with any size.

  FIG. 24 shows another modification of the charged beam apparatus. A sample 5002 is placed on the stage 5003, and the sample moves in a range indicated by the movable range L as the stage 5003 moves. On the other hand, the lens barrel 5001 is fixed to a gantry 5014, and a differential evacuation unit 5004 is provided at the tip of the lens barrel 5001 so as to surround the tip, and the differential evacuation unit 5004 and the sample surface 5021 or the surface of the stage are provided. Differential exhaust and high-purity inert gas are sprayed between 5031 and 5031. A container 5012 is mounted on the stage 5003 so as to completely cover the movable range L of the sample 5002, and a minute gap 5052 is provided between the sample surface 5021 or the plate-like members 5060 and 5061 and the lower surface of the container 5012. It has been. The high purity inert gas blown out from the differential exhaust unit 5004 is blown into the container 5012 through the gap 5051 between the differential exhaust unit 5004 and the sample surface 5021 or the plate-like members 5060 and 5061, and the same. An amount of gas is blown out of the container 5012 through the minute gap 5052.

  With such a configuration, the inside of the container 5012 is always filled with a high-purity inert gas, and the outside air does not enter from the minute gap 5052 and is kept clean. Therefore, even if the sample moves in the container 5012, the sample is not likely to be contaminated by particles or water vapor, and the charged beam irradiation area can be easily stabilized in a high vacuum state. As a result, the reliability and operating rate of the apparatus can be improved.

  FIG. 25 shows another modification of the charged beam apparatus. In this modified example, unlike the case of FIG. 24, the container 5015 is formed so as to completely surround not only the movable range of the sample but also the stage 5003, and the high purity inert gas blown out from the differential exhaust unit 5004 is It is discharged through a discharge pipe 5016. Such a configuration also has the same effect as that of the modified example of FIG. 24. However, since the container 5015 completely covers the stage 5003, there is a possibility that contaminants such as particles and water vapor enter from the outside air. It can be completely removed, and the reliability and operating rate of the apparatus can be further improved.

  Note that the container 5012 in FIG. 24 and the container 5015 in FIG. 25 may have a pressure slightly higher than the atmospheric pressure so that the high-purity inert gas can be discharged from the gap 5052 or the discharge pipe 5016. A simple structure such as a cover is sufficient for the containers, and even if these containers are provided, the influence on the size and cost of the apparatus is small.

  FIG. 26 shows another modification of the charged beam apparatus. As in the modification shown in FIG. 25, this modification is provided with a container 5017 that completely covers the stage 5003 and is filled with a high-purity inert gas. A vacuum container 5027 for unloading is connected. A vacuum pipe 5029 and a high purity inert gas supply pipe 5030 are connected to the vacuum container 5027, and a shutoff valve 5028 is provided between the vacuum container 5027 and the container 5017.

In such a configuration of the present modification, the charged beam apparatus performs processing by the following method.
First, the open / close lid (not shown) of the vacuum vessel 5027 is opened, the sample 5002 to be processed by the charged beam is placed in the vacuum vessel 5027, the open / close lid is hermetically closed, and the vacuum vessel 5029 is used to close the vacuum vessel 5029. 5027 is evacuated to a predetermined degree of vacuum. Next, a high purity inert gas is supplied from the supply pipe 5030 to fill the vacuum container with the high purity inert gas. When the internal pressure of the vacuum container 5027 reaches the same pressure as the internal pressure of the container 5017, the shutoff valve 5028 is moved in the direction of arrow C to put the sample 5002 into the container 5017, and the sample 5002 is supplied by a sample transport mechanism (not shown). Is placed at a predetermined position on the stage 5003. That is, after the sample is inserted into the vacuum vessel 5027, the vacuum vessel 5027 is evacuated to a predetermined pressure, and then a high purity inert gas is introduced into the vacuum vessel 5027, and then the shut-off valve is opened, A sample 5002 is placed on a stage 5003 in a vacuum vessel filled with an inert gas. After that, the stage 5003 is moved to transfer the sample 5002 to the charged beam irradiation region, and processing with a charged beam is performed.

  In this way, the sample surface 5021 cleaned by evacuation is always covered with high-purity inert gas until it is transported to the charged beam irradiation region and is not exposed to the atmosphere. Therefore, even if the sample is carried into the charged beam irradiation region and exposed again to the vacuum environment, the gas released from the sample surface 5021 is only the high-purity inert gas that has covered the sample surface, so that the time is extremely short. The degree of vacuum in the charged beam irradiation area does not deteriorate. Thus, the charged beam irradiation region can be easily maintained at a high degree of vacuum, and the risk of contaminating the sample surface can be reduced.

  FIG. 27 schematically shows one embodiment of the evacuation path of the charged beam apparatus. In this embodiment, a pipe 5013 for evacuating the inside of the lens barrel 5001 is connected to an ultrahigh vacuum pump 5018. Further, the high vacuum pipe 5008 of the differential exhaust unit 5004 is connected to the ultra-high vacuum pump 5020, and the low vacuum pipe 5009 is connected to the roughing pipe of the ultra-high vacuum pump 5020 and exhausted by the roughing pump 5201. Is done. Further, as a high purity inert gas, for example, nitrogen gas is supplied from the nitrogen gas source 5022 to the differential exhaust unit 5004 via the pipe 5010.

  FIG. 28 schematically shows another modification of the evacuation path of the charged beam apparatus. In this modification, the pipe 5013 for evacuating the lens barrel 5001 and the high vacuum pipe 5008 of the differential evacuation unit 5004 are joined and connected to the ultra high vacuum pump 5018 and evacuated by the ultra high vacuum pump 5018. On the other hand, the low vacuum pipe 5009 of the differential exhaust section 5004 is connected to the roughing pipe of the ultra-high vacuum pump 5018 and exhausted by the roughing pump 5019. With such a configuration, the number of vacuum pumps can be reduced as compared with the embodiment of FIG.

  As the ultra high vacuum pump, for example, a turbo molecular pump or an ion pump can be applied, and as a roughing pump, for example, a dry pump or a diaphragm pump can be applied.

  FIG. 29 shows another modification of the charged beam apparatus, and schematically shows the circulation path of the inert gas. High purity inert gas is supplied from a differential exhaust unit 5004 provided in the lens barrel 5001 into a container 5015 filled with high purity inert gas. The supplied high-purity inert gas is discharged from the container 5015 through the discharge pipe 5016 and pressurized by the compressor 5023. The pressurized high-purity inert gas is sent to a gas purification device 5024 such as a cold trap or a high-purity filter via a pipe 5025 and cleaned, and then sent again to the differential exhaust unit 5004 via a pipe 5010. And supplied into the container 5015. In this case, the gas purification device may not be provided if there is no problem in purity deterioration even if the gas is circulated.

  The high purity inert gas supplied from the differential exhaust unit 5004 is sucked by the differential exhaust mechanism and exhausted by the ultra-high vacuum pump 5020 and the roughing pump 5201 through the low vacuum pipe 5009 and the high vacuum pipe 5008. Is done. Since the pipe 5026 provided on the exhaust side of the roughing pump 5201 is connected to the pipe 5025 on the exhaust side of the compressor 5023, the high-purity inert gas that has passed through this path is also returned to the differential exhaust part via the pipe 5010. 5004.

  In this way, since the high purity inert gas can be circulated and reused, the high purity inert gas can be saved, and since the high purity inert gas is not discharged into the room where the apparatus is installed, The possibility of accidents such as suffocation due to inert gas is also eliminated.

Next, with reference to FIG. 30, a modification in which the projection type charged beam apparatus according to this embodiment is applied to a wafer defect inspection apparatus will be described.
In this modification, the electron beam E generated by the electron gun 5071 of the lens barrel 5070 of the primary optical system passes through the lens group 5072 and is shaped into a predetermined cross-sectional shape. The shaped electron beam (charged beam) 5050 has its trajectory changed by the Wien filter 5073, and enters the wafer 5002, which is the sample to be inspected, perpendicularly. As a result, secondary electrons are emitted from the sample surface, and the secondary electrons are accelerated by the objective lens 5074 and travel straight through the Wien filter 5073. Then, the secondary electrons are magnified by the lens unit 5075 and projected onto the detection unit 5076. The detection unit 5076 generates a secondary electron projection image. This image is subjected to image processing, and compared with images at other locations as necessary to determine whether or not the surface of the wafer is defective, and the result is recorded and displayed on the apparatus in a predetermined manner.

  The configurations and operations of the differential exhaust unit 5004, the container 5015, the vacuum pipes 5008 and 5009, the pipe 5010 for supplying high purity inert gas, and the like are the same as those in the embodiment described with reference to FIGS. It is the same as that. The high purity inert gas flows through the container 5015 as shown by the arrow D in the figure, and is discharged from the discharge pipe 5016.

According to the present embodiment, the following effects can be obtained.
(1) Since it is possible to maintain a vacuum environment only where a vacuum environment is necessary, the stage used in the atmosphere can be used, and the charged beam apparatus can be manufactured in a compact and low manufacturing cost. Can do.
(2) Since it is possible to prevent particles from entering the sample surface from the atmosphere side and to reduce the chance that the sample directly contacts the atmosphere, the sample and the charged beam optical system are contaminated with particles, water vapor, etc. Can be prevented.
(3) Since the amount of gas released from the sample surface or the surface of the component parts of the stage into the vacuum environment can be greatly reduced, the charged beam irradiation region can be maintained at a high degree of vacuum.
(4) Since the stage used in the atmosphere can be used as it is, it is also possible to use a static pressure gas bearing for the stage guide. By combining with a high precision actuator such as a linear motor, the charged beam device It is possible to make the stage for the high accuracy equivalent to the high accuracy stage for the atmosphere used in the exposure apparatus or the like.

Next, an embodiment of a semiconductor device manufacturing method according to the present invention will be described with reference to FIGS.
FIG. 31 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 6400)
(2) Mask manufacturing process for manufacturing a mask used for exposure (or mask preparation process for preparing a mask) (step 6401)
(3) Wafer processing process for performing necessary processing on the wafer (step 6402)
(4) Chip assembly process for cutting out chips formed on the wafer one by one and making them operable (step 6403)
(5) Chip inspection process for inspecting the completed chip (step 6404)
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 step, 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 step includes the following steps.
(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 process for oxidizing the thin film layer and wafer substrate (C) Lithography process 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 the processed wafer The wafer processing process is repeated as many times as necessary to manufacture a semiconductor device that operates as designed.

FIG. 32 is a flowchart showing a lithography process which is the core of the wafer processing process of FIG. 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 preceding process (step 6500)
(B) Step of exposing resist (step 6501)
(C) Development process of developing the exposed resist to obtain a resist pattern (step 6502)
(D) An annealing process for stabilizing the developed resist pattern (step 6503)
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 step (G), even a semiconductor device having a fine pattern can be inspected with high throughput, so that 100% inspection is possible, and the yield of products is improved. It becomes possible to prevent shipment of defective products.

The inspection procedure in the inspection step (G) will be described.
In general, defect inspection apparatuses using electron beams are expensive and have a lower throughput than other process apparatuses. Therefore, important processes (e.g., etching, film formation (plating), etc., which are considered to be inspected most at present. Or CMP (chemical mechanical polishing) planarization treatment).

  The wafer to be inspected is positioned on the ultra-precise XY stage through the atmospheric transfer system and the vacuum transfer system, and then fixed by the electrostatic chuck mechanism, etc., and thereafter defect inspection etc. according to the procedure of (inspection flow of FIG. 33). Is done. First, the position of each die is checked and the height of each location is detected and stored by an optical microscope as necessary (step 7001). In addition to this, the optical microscope acquires an optical microscope image of a desired location such as a defect and is used for comparison with an electron beam image. Next, recipe information corresponding to the wafer type (after which process, whether the wafer size is 20 cm or 30 cm, etc.) is input to the apparatus (step 7002), and the inspection location is designated (step 7003). After setting the above, setting the inspection conditions, etc. (step 7004), the defect inspection is usually performed in real time while acquiring the image (step 7005). Cell-to-cell comparison, die comparison, and the like are inspected by a high-speed information processing system equipped with an algorithm, and the result is output to a CRT or the like or stored in a memory as necessary (step 7006). Defects include particle defects, shape abnormalities (pattern defects), electrical defects, etc. (disconnections such as wiring or vias and poor conduction, etc.). It is also possible to automatically classify critical defects that are impossible) in real time. Detection of an electrical defect is achieved by detecting a contrast abnormality. For example, a place with poor conduction is normally positively charged by electron beam irradiation (about 500 eV), and the contrast is lowered, so that it can be distinguished from a normal place. The electron beam irradiating means in this case is a low potential (energy) electron beam generating means (thermoelectron generation, UV / photoelectron) provided to stand out contrast due to a potential difference separately from the electron beam irradiation means for normal inspection. )including. Before irradiating the inspection target region with the electron beam for inspection, this low potential (energy) electron beam is generated and irradiated. In the case of a projection method that can be positively charged by irradiating an inspection electron beam, it is not necessary to provide an electron beam generating means with a low potential depending on the specifications. Further, it is possible to detect a defect from a difference in contrast caused by applying a positive or negative potential to a sample such as a wafer with respect to a reference potential (which occurs because the flowability varies depending on the forward direction or reverse direction of the element). This can also be used for a line width measuring apparatus and alignment accuracy measurement.

  As a method for inspecting an electrical defect of an inspection sample, it is also possible to use the fact that the potential of the part is different between the part that is originally electrically insulated and the part in an energized state.

  First, by applying a charge to the sample in advance, the potential of the part that is originally electrically insulated and the part that is originally electrically insulated, but the part that is in an energized state for some reason By generating a potential difference with respect to the potential and then irradiating the beam of the present invention, data having a potential difference is acquired, and the acquired data is analyzed to detect that the current state is in an energized state.

In each of the embodiments described above, when an electron beam is generated, the target substance is floated and attracted to a high potential region by proximity interaction (charging of particles near the surface). An organic substance as an insulator is deposited on the surface of the electrode. In this way, the insulator that gradually accumulates on the surface of the electrode due to the charging of the electrode surface adversely affects the formation of the electron beam and the deflection mechanism, so the deposited insulator must be periodically removed. . Periodic removal of the insulator is performed as follows. That creates by using an electrode near the area to be deposited of the insulator, a compound containing hydrogen or oxygen or fluorine and those in vacuo _{HF, O 2, H 2 O} , the plasma, such as C _M F _N, space By maintaining the plasma potential at a potential (several kV, for example, 20 V to 5 kV) at which sputtering occurs on the electrode surface, only organic substances are removed by oxidation, hydrogenation, and fluorination.

In addition, this application is not limited to the said Example, For example, you may combine the element of the said Example arbitrarily.
The inspection of the present application includes not only detecting the presence / absence of a defective state such as a defect but also evaluating the inspection result.

The present invention is configured as follows.
1. A primary electron optical system for shaping a primary electron beam emitted from an electron gun into a desired shape and irradiating the shaped primary electron beam on a sample surface to be inspected;
A secondary electron optical system for enlarging and projecting secondary electrons emitted from the sample;
A detection device for converting the enlarged secondary electron image into a light image through a fluorescent screen and capturing the image with a line sensor;
A projection projection type electronic apparatus comprising: a control device for controlling a charge movement time when transferring a line image picked up in a pixel array provided in the line sensor in conjunction with a moving speed of a stage for moving a sample. Line inspection device.
2. The electron beam inspection apparatus according to claim 1,
The control apparatus is an electron beam inspection apparatus that controls a charge transfer time of the line sensor in conjunction with a change in magnification of the primary and secondary electron optical systems.
3. The electron beam inspection apparatus according to claim 1,
The detection apparatus is an electron beam inspection apparatus including a microchannel plate that is arranged in front of the fluorescent plate and multiplies secondary electrons of the secondary electron optical system.
4). The electron beam inspection apparatus according to claim 1,
An electron beam inspection apparatus further comprising a laser interferometer for measuring the position of the stage.
5). A device manufacturing method, wherein the wafer in the middle of the process is evaluated using the electron beam inspection apparatus according to claim 1.
6). A primary electron optical system that irradiates a sample surface to be inspected with a primary electron beam emitted from an electron gun;
A secondary electron optical system for enlarging and projecting secondary electrons emitted from the sample;
A first detector for generating an image signal based on the enlarged projected secondary electron image;
A deflector that scans the sample surface with the primary electron beam;
A multi-purpose electron beam inspection apparatus comprising: a second detector that generates an image signal based on secondary electrons emitted from the sample by irradiation of the scanned primary electron beam onto the sample surface.
7). The multipurpose electron beam inspection apparatus according to claim 6,
Multipurpose electrons capable of performing at least one of defect detection on the sample surface, defect review on the sample surface, and measurement of pattern potential on the sample surface based on the image signal output from the first detector Line inspection device.
8). The multipurpose electron beam inspection apparatus according to claim 6,
Based on the image signal output from the second detector, at least one of defect detection on the sample surface, defect review on the sample surface, pattern line width measurement on the sample surface, and pattern potential measurement on the sample surface Multipurpose electron beam inspection device that can perform one.
9. The multipurpose electron beam inspection apparatus according to claim 6,
A multipurpose electron beam inspection apparatus capable of performing at least two of defect detection on a sample surface, defect review on a sample surface, pattern line width measurement on the sample surface, and pattern potential measurement on the sample surface.
10. The multipurpose electron beam inspection apparatus according to claim 9, wherein
The sample surface defect detection is performed by comparing an image obtained by an image signal with pattern data or by comparing images of dies.
The sample surface defect review is performed by observing the image obtained by scanning the beam on the monitor synchronized with the scanning of the primary electron beam on the wafer surface.
The pattern line width measurement on the sample surface is performed by a secondary electron image when scanning of the primary electron beam on the wafer surface is performed in the short side direction of the pattern,
The pattern potential measurement is performed by applying a negative potential to the electrode closest to the sample surface and selectively repelling secondary electrons emitted from the pattern having a high potential on the sample surface to the sample side. .
11. A multipurpose electron beam inspection apparatus that inspects the state of a sample surface on a sample stage by irradiating a sample with a primary electron beam and detecting secondary electrons generated from the sample surface,
A lens system capable of forming a primary electron beam into at least two of a rectangle, a circle, and a spot;
A primary electron optical system having a deflection system for scanning an electron beam in an arbitrary direction;
A detection system for directing secondary electrons emitted from the sample from the sample surface to the detector;
A multipurpose electron beam inspection apparatus comprising: a controller that automatically detects a defect, outputs position information of the defect, and further enables observation of the shape of the defect.
12 A multi-purpose electron beam inspection apparatus according to any one of claims 1 to 3, wherein a plurality of multi-purpose electron beam inspection apparatuses are arranged in one or more rows, and the sample stage is shared so that samples on a common sample stage can be inspected. Combination of inspection equipment.
13. 13. A device manufacturing method, comprising: inspecting a semiconductor wafer in the middle of a process using the multipurpose electron beam inspection apparatus according to claim 6 or a combination thereof.
14 An electron irradiation unit for irradiating the sample with a primary electron beam;
A secondary optical system for generating an image of the sample by magnifying and projecting a secondary electron beam generated from the sample by irradiation of the primary electron beam;
A microchannel plate for receiving the image;
A TDI-CCD that converts the output of the microchannel plate into light with a scintillator and then converts the optical signal into an electrical signal;
An image display unit for processing the output of the TDI-CCD, and a stage for moving the sample;
Scanning the sample by the stage;
An electron beam inspection apparatus comprising a magnetic lens disposed between the sample and the microchannel plate for rotating the image.
15. The electron beam inspection apparatus according to claim 14, wherein
An electron beam inspection apparatus in which the magnetic lens is positioned between a final lens of the optical system and the microchannel plate.
16. The electron beam inspection apparatus according to claim 15, wherein
An electron beam inspection apparatus in which the magnetic lens is disposed at a crossover position closest to the microchannel plate.
17. The electron beam inspection apparatus according to claim 14, wherein
An electron beam inspection apparatus in which the magnetic lens is disposed at an imaging position closest to the final lens on the side opposite to the microchannel plate with respect to the final lens.
18. A device manufacturing method using the electron beam inspection apparatus according to claim 14.
19. An electron beam inspection apparatus for detecting a secondary electron generated from a sample by focusing and scanning a primary electron beam from an electron gun on the sample surface, and evaluating the sample surface,
A primary electron beam having an axially symmetric central electrode, a lower electrode disposed closer to the sample than the central electrode, and an upper electrode disposed closer to the electron gun than the central electrode is aligned with the sample surface. An electrostatic lens to focus,
An electron beam inspection apparatus comprising: a control device that applies a voltage having a potential lower than that of a sample surface to a lower electrode when obtaining a potential contrast of a pattern on the sample surface.
20. The electron beam inspection apparatus according to claim 19,
For evaluation that does not require obtaining a potential contrast, the control device is an electron beam inspection device that applies a voltage close to ground to the lower electrode.
21. The electron beam inspection apparatus according to claim 20,
Electron beam inspection characterized in that the control device adjusts the deviation of the focusing condition of the electrostatic lens that occurs when the voltage applied to the lower electrode is greatly changed by changing the positive high voltage applied to the central electrode. apparatus.
22. The electron beam inspection apparatus according to claim 20,
An electron beam inspection apparatus capable of changing the focusing condition of the electrostatic lens at high speed and small by adjusting a voltage applied to the upper electrode by the control device.
23. 20. The optical system comprising the electron gun, electrostatic lens, scanning means, and secondary electron detection means according to claim 19, wherein a plurality of optical systems are arranged on the same sample, and the inspection on the sample is simultaneously performed by the plurality of optical systems. Inspection method using a characteristic electron beam.
24. 23. A device manufacturing method, comprising: evaluating a wafer in the middle of a process using the electron beam inspection apparatus according to claim 19.
25. An apparatus for irradiating a surface of a sample placed on a stage with a charged beam,
In order to keep only the vicinity of the portion irradiated with the charged beam at a predetermined degree of vacuum, at least one differential exhaust device provided around the region irradiated with the charged beam;
A charged beam apparatus comprising: an inert gas ejection device that ejects an inert gas toward a sample surface on an outer peripheral side of the differential exhaust device.
26. The charged beam device according to claim 25.
A charged beam apparatus further comprising a container filled with an inert gas that always covers the entire range in which the stage for moving the sample to a predetermined position moves or the movable range of the sample.
27. 27. The charged beam device according to claim 26.
A container filled with the inert gas is connected to a vacuum container via a shutoff valve,
A charged beam apparatus in which a sample can enter and exit through a container filled with the inert gas through the vacuum container.
28. Providing a charged beam device according to claim 27;
Evacuating the vacuum vessel to a predetermined pressure after inserting the sample into the vacuum vessel of the charged beam device;
A sample transport method comprising: introducing an inert gas into the vacuum container; then, opening a shut-off valve and placing the sample on a stage in the container filled with the inert gas.
29. A wafer defect inspection apparatus for inspecting a surface defect of a semiconductor wafer using the charged beam apparatus according to any one of claims 25 to 27 or the transfer method according to claim 28.
30. A semiconductor manufacturing method using the apparatus according to claim 29.
31. A stage for holding the sample movably,
An irradiation device that collectively irradiates the observation region of the sample with a primary electron beam;
A detector for detecting secondary electrons generated from the observation region of the irradiated sample by collectively forming an image of an electron beam through a lens system;
A conversion device for converting the formed image into an electrical signal;
A projection type electron beam inspection apparatus comprising a storage device for storing image information converted into an electrical signal.
32. The electron beam inspection apparatus according to claim 31,
The conversion device includes a line sensor having a pixel row,
Furthermore, an electron beam inspection apparatus comprising a control device that controls a charge movement time when transferring a line image picked up in the pixel row in conjunction with a moving speed of a stage for moving a sample.
33. The electron beam inspection apparatus according to claim 32,
further,
A deflector that irradiates the sample while scanning the primary electron beam;
An electron beam inspection apparatus comprising: a second detector that detects secondary electrons generated from a sample by irradiation while scanning the primary electron beam.
34. The electron beam inspection apparatus according to claim 32,
Furthermore, the electron beam inspection apparatus provided with the magnetic lens which is arrange | positioned between the said sample and the said detector and rotates the said image.
35. The electron beam inspection apparatus according to claim 32,
In addition, an electrostatic lens for focusing the primary electron beam on the observation area of the sample is provided,
The electrostatic lens has an axially symmetric central electrode, a lower electrode disposed closer to the sample than the central electrode, and an upper electrode disposed closer to the electron gun than the central electrode,
The electron beam inspection apparatus further includes a voltage applying device that applies a voltage having a lower potential than the surface of the sample to the lower electrode in order to obtain a potential contrast of the pattern on the observation region of the sample.
36. The electron beam inspection apparatus according to claim 32,
In order to keep only the vicinity of the observation region of the sample irradiated with the primary electron beam at a predetermined degree of vacuum, at least a single differential pumping device provided around the observation region irradiated with the primary electron beam;
An electron beam inspection apparatus comprising: an inert gas ejection device that ejects an inert gas toward a sample surface on an outer peripheral side of the differential exhaust device.

FIG. 1 is an overall configuration diagram of a projection type electron beam inspection apparatus according to an embodiment of the present invention. FIG. 2 is a cross-sectional view showing a detailed configuration of an E × B deflector (that is, an electron beam deflecting unit) in the electron beam inspection apparatus. FIG. 3 is a cross-sectional view showing a longitudinal cross-sectional structure along the line AA in FIG. FIG. 4 shows an overall configuration diagram of a projection type electron beam inspection apparatus that irradiates an observation region on the sample surface while two-dimensionally scanning a plurality of primary electron beams. FIG. 5 is a diagram for explaining a primary electron beam irradiation method in the apparatus shown in FIG. FIG. 6 is a block diagram schematically showing an electron beam inspection apparatus according to another embodiment of the present invention. FIG. 7 is a block diagram showing the control device of the electron beam inspection apparatus shown in FIG. 6 in more detail. FIG. 8 is a diagram showing a procedure for inspecting a wafer. FIG. 9 is a diagram illustrating an array of pixels of the line sensor. FIG. 10 is a diagram showing a configuration of a mapping projection type electron beam inspection apparatus according to a related technique. FIG. 11 is a block diagram showing a projection type electron beam inspection apparatus according to still another embodiment of the present invention. FIG. 12 is a diagram schematically showing a mapping projection type electron beam inspection apparatus according to another embodiment of the present invention. FIG. 13A and FIG. 13B are diagrams for explaining the operating principle of the magnetic lens shown in FIG. FIG. 14 is a diagram showing an arrangement example of the magnetic lenses shown in FIG. FIG. 15 is a diagram showing another arrangement example of the magnetic lens shown in FIG. FIG. 16 is a diagram showing a schematic configuration of an electron beam inspection apparatus according to another embodiment of the present invention. FIG. 17 is a layout diagram of a multi-barrel that is a plurality of modified barrels of the electron beam inspection apparatus of FIG. FIG. 18 is a graph showing the distribution of the on-axis potential when a voltage is applied to each electrode and sample. FIG. 19 is a view showing an embodiment of a differential exhaust structure provided in a charged beam inspection apparatus as an electron beam inspection apparatus of the present invention. FIG. 20 is a view showing a modified example of the differential exhaust structure, and is a view showing a state in which the direction of the high-purity inert gas ejection port is directed toward the outer peripheral side. FIG. 20 is a view showing a modified example of the differential exhaust structure, and is a view showing a state in which the direction of the high-purity inert gas ejection port is directed toward the outer peripheral side. FIG. 22A is a view showing another modification of the differential exhaust structure, in which a height adjusting member is provided on the stage, and the lens barrel is located in the vicinity of one end of the stage. It shows the state. FIG. 22B is a diagram in which a height adjusting member is provided on the same stage as in FIG. 22A, and shows a state in which the lens barrel is positioned in the vicinity of the other end of the stage. FIG. 23 shows a modified example of the charged beam apparatus according to the present invention, in which a height adjusting mechanism is provided on the stage. FIG. 24 is a view showing another modified example of the differential exhaust structure, in which the movable range of the sample moved by the stage is covered with a container filled with an inert gas. FIG. 25 is a view showing another modification of the differential exhaust structure, and is a view showing a state in which the entire range in which the stage moves is covered with a container filled with an inert gas. FIG. 26 is a view showing another modified example of the differential exhaust structure, and is a view showing a state in which a vacuum chamber is connected to a container filled with an inert gas. FIG. 27 is a view showing another modification of the differential exhaust structure, and is a view schematically showing one embodiment of the vacuum exhaust path. FIG. 28 is a diagram showing another modification of the differential exhaust structure, and is a diagram schematically showing another modification of the vacuum exhaust path. FIG. 29 is a view showing another modification of the differential exhaust structure, and is a view schematically showing the circulation path of the inert gas. FIG. 30 is a diagram in which a charged beam apparatus according to another embodiment of the present invention is applied to a wafer defect inspection apparatus. FIG. 31 is a flowchart showing an embodiment of a semiconductor device manufacturing method according to the present invention. FIG. 32 is a flowchart showing a lithography process which is the core of the wafer processing process of FIG. FIG. 33 is a flowchart showing the inspection procedure of the present invention.

Claims (21)

A primary electron optical system for shaping a primary electron beam emitted from an electron gun into a desired shape and irradiating the shaped primary electron beam on a sample surface to be inspected;
A secondary electron optical system for enlarging and projecting secondary electrons emitted from the sample;
A detection device for converting the enlarged secondary electron image into a light image through a fluorescent screen and capturing the image with a line sensor;
A projection projection type electronic apparatus comprising: a control device for controlling a charge movement time when transferring a line image picked up in a pixel array provided in the line sensor in conjunction with a moving speed of a stage for moving a sample. Line inspection device. The electron beam inspection apparatus according to claim 1,
The control apparatus is an electron beam inspection apparatus that controls a charge transfer time of the line sensor in conjunction with a change in magnification of the primary and secondary electron optical systems. The electron beam inspection apparatus according to claim 1,
The detection apparatus is an electron beam inspection apparatus including a microchannel plate that is arranged in front of the fluorescent plate and multiplies secondary electrons of the secondary electron optical system. The electron beam inspection apparatus according to claim 1,
An electron beam inspection apparatus further comprising a laser interferometer for measuring the position of the stage.   A device manufacturing method, wherein the wafer in the middle of the process is evaluated using the electron beam inspection apparatus according to claim 1. A primary electron optical system that irradiates a sample surface to be inspected with a primary electron beam emitted from an electron gun;
A secondary electron optical system for enlarging and projecting secondary electrons emitted from the sample;
A first detector for generating an image signal based on the enlarged projected secondary electron image;
A deflector that scans the sample surface with the primary electron beam;
A multi-purpose electron beam inspection apparatus comprising: a second detector that generates an image signal based on secondary electrons emitted from the sample by irradiation of the scanned primary electron beam onto the sample surface. The multipurpose electron beam inspection apparatus according to claim 6,
The sample surface defect detection is performed by comparing an image obtained by an image signal with pattern data or by comparing images of dies.
The sample surface defect review is performed by observing the image obtained by scanning the beam on the monitor synchronized with the scanning of the primary electron beam on the wafer surface.
The pattern line width measurement on the sample surface is performed by a secondary electron image when scanning of the primary electron beam on the wafer surface is performed in the short side direction of the pattern,
The pattern potential measurement is performed by applying a negative potential to the electrode closest to the sample surface and selectively repelling secondary electrons emitted from the pattern having a high potential on the sample surface to the sample side. . A multi-purpose electron beam inspection apparatus that inspects the state of a sample surface on a sample stage by irradiating a sample with a primary electron beam and detecting secondary electrons generated from the sample surface,
A lens system capable of forming a primary electron beam into at least two of a rectangle, a circle, and a spot;
A primary electron optical system having a deflection system for scanning an electron beam in an arbitrary direction;
A detection system for directing secondary electrons emitted from the sample from the sample surface to the detector;
A multipurpose electron beam inspection apparatus comprising: a controller that automatically detects a defect, outputs position information of the defect, and further enables observation of the shape of the defect.   9. A device manufacturing method, comprising: inspecting a semiconductor wafer in the middle of a process using the multipurpose electron beam inspection apparatus according to claim 6 or a combination thereof. An electron irradiation unit for irradiating the sample with a primary electron beam;
A secondary optical system for generating an image of the sample by magnifying and projecting a secondary electron beam generated from the sample by irradiation of the primary electron beam;
A microchannel plate for receiving the image;
A TDI-CCD that converts the output of the microchannel plate into light with a scintillator and then converts the optical signal into an electrical signal;
An image display unit for processing the output of the TDI-CCD, and a stage for moving the sample;
Scanning the sample by the stage;
An electron beam inspection apparatus comprising a magnetic lens disposed between the sample and the microchannel plate for rotating the image. An electron beam inspection apparatus for detecting a secondary electron generated from a sample by focusing and scanning a primary electron beam from an electron gun on the sample surface, and evaluating the sample surface,
A primary electron beam having an axially symmetric central electrode, a lower electrode disposed closer to the sample than the central electrode, and an upper electrode disposed closer to the electron gun than the central electrode is aligned with the sample surface. An electrostatic lens to focus,
An electron beam inspection apparatus comprising: a control device that applies a voltage having a potential lower than that of a sample surface to a lower electrode when obtaining a potential contrast of a pattern on the sample surface.   12. The optical system comprising the electron gun, electrostatic lens, scanning means, and secondary electron detection means according to claim 11, wherein a plurality of optical systems are arranged on the same sample, and the inspection on the sample is simultaneously performed by the plurality of optical systems. Inspection method using a characteristic electron beam.   A device manufacturing method, wherein a wafer in the middle of a process is evaluated using the electron beam inspection apparatus according to claim 11. An apparatus for irradiating a surface of a sample placed on a stage with a charged beam,
In order to keep only the vicinity of the portion irradiated with the charged beam at a predetermined degree of vacuum, at least one differential exhaust device provided around the region irradiated with the charged beam;
A charged beam apparatus comprising: an inert gas ejection device that ejects an inert gas toward a sample surface on an outer peripheral side of the differential exhaust device. The charged beam device according to claim 14.
A container filled with the inert gas is connected to a vacuum container via a shutoff valve,
A charged beam apparatus in which a sample can enter and exit through a container filled with the inert gas through the vacuum container. Providing a charged beam device according to claim 15;
Evacuating the vacuum vessel to a predetermined pressure after inserting the sample into the vacuum vessel of the charged beam device;
A sample transport method comprising: introducing an inert gas into the vacuum container; then, opening a shut-off valve and placing the sample on a stage in the container filled with the inert gas.   A semiconductor manufacturing method using the apparatus of claim 16. A stage for holding the sample movably,
An irradiation device that collectively irradiates the observation region of the sample with a primary electron beam;
A detector for detecting secondary electrons generated from the observation region of the irradiated sample by collectively forming an image of an electron beam through a lens system;
A conversion device for converting the formed image into an electrical signal;
A projection type electron beam inspection apparatus comprising a storage device for storing image information converted into an electrical signal. The electron beam inspection apparatus according to claim 18,
The conversion device includes a line sensor having a pixel row,
Furthermore, an electron beam inspection apparatus comprising a control device that controls a charge transfer time when transferring a line image picked up in the pixel row in conjunction with a moving speed of a stage for moving a sample. The electron beam inspection apparatus according to claim 19,
further,
A deflector that irradiates the sample while scanning the primary electron beam;
An electron beam inspection apparatus comprising: a second detector that detects secondary electrons generated from a sample by irradiation while scanning the primary electron beam. The electron beam inspection apparatus according to claim 19,
In order to keep only the vicinity of the observation region of the sample irradiated with the primary electron beam at a predetermined degree of vacuum, at least one differential exhaust device provided around the observation region irradiated with the primary electron beam;
An electron beam inspection apparatus comprising: an inert gas ejection device that ejects an inert gas toward a sample surface on an outer peripheral side of the differential exhaust device.

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