JP2966804B2 - Electron beam inspection equipment - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention
Testing with an insulating film on a metal or semiconductor substrate
Material or metal or semiconductor of any shape on the insulating film
The present invention relates to an electron beam inspection apparatus for inspecting a defect of the insulating film of a sample formed in a body . 2. Description of the Related Art FIG. 1A is a sectional view of a sample having an insulating film to be inspected, 1 is a substrate made of metal or semiconductor,
Reference numeral 2 denotes an insulating film, and reference numeral 3 denotes a metal or a semiconductor formed in isolation on the insulating film 2 in an arbitrary shape. The sample as shown is a sample in the middle of a manufacturing process of a semiconductor integrated circuit or the like. FIG. 1B is a schematic perspective view of an apparatus for inspecting a defect of the insulating film 2 of a sample as shown in FIG.
Is a metal probe with a tip diameter of about 20 μm, 5 is a voltmeter,
6 is an ammeter and 7 is a DC power supply. In the inspection apparatus having such a configuration, a voltage less than the withstand voltage of the insulating film 2 is applied by the DC power supply 7 to connect the metal probe 4 to the metal or semiconductor 3.
And the insulating property of the insulating film 2 is measured by a voltmeter 5 and an ammeter 6. However, in such an inspection apparatus, the secondary size of the metal or semiconductor 3 is about 10 due to the limit due to the mechanical contact of the metal probe 4.
It is limited to 0 μm square or more. That is, when the size of the metal or semiconductor 3 is 20 μm or less of the tip diameter of the metal probe 4, measurement is impossible at all. FIG. 1 (c) is a cross-sectional view showing a defect inspection apparatus for an insulating film 2 of a sample in which only an insulating film 2 is formed on a substrate 1 made of metal or semiconductor.
A metal 8 having a low melting point, such as an ( Ga , In) alloy, is
Then, the voltage is applied by the DC power supply 7, and the insulating property of the insulating film 2 is measured by the voltmeter 5 and the ammeter 6. However, this inspection device inspects the average insulating property of the insulating film 2 and cannot know the size and number of defects of the insulating film 2. [0006] The shape of individual elements and wiring patterns formed inside a semiconductor integrated circuit or the like has already reached the order of microns, and the miniaturization of these has been further advanced. However, as described above, in the conventional defect inspection apparatus for an insulating film, fine defects such as the size and number of defects cannot be extracted. Therefore, this is one of the factors that lowers the yield after completion of the device. The present invention has been made in view of the above-mentioned circumstances of the prior art, and has as its object to have an insulating film on a metal or semiconductor substrate using an electron beam.
A sample or a metal or semi-metal of any shape on the insulating film
An object of the present invention is to provide an electron beam inspection apparatus capable of inspecting a defect of the insulating film of a sample in which a conductor is formed in isolation . [0009] As described above, the inspection of insulation using a metal probe is limited and must be performed by another method. Meanwhile, a scanning electron microscope (hereinafter referred to as a scanning electron microscope) which scans a finely focused electron beam on a sample to be inspected and displays an image on a screen of a cathode ray tube by secondary electrons generated from the sample by the irradiated electron beam. hereinafter referred to as SEM; S canning E lectron M icroscope ) there is. This SE
M is for observing the fine surface shape of the sample, and it is impossible to achieve the above-mentioned object with a normal SEM. Generally, the electron energy incident on the sample of the SEM is 1
A voltage of about 0 to 30 keV is used.
It is about eV. When the insulating film is irradiated with such high-energy electrons, charge-up occurs on the insulating film and the electron beam is shaken as described later in detail, and an accurate image cannot be obtained. Also, simply SE
If the electron beam energy is reduced to M,
Although the above-mentioned charge-up phenomenon can be reduced, the phenomenon essentially occurs, and in general, lowering the accelerating voltage lowers the brightness of the electron beam source due to electro-optical reasons. Conventionally, it has not been possible to obtain information corresponding to a defect in an insulating film due to the fact that the SN ratio of an image becomes poor and it becomes difficult to clearly observe a display screen. On the other hand, when a semiconductor sample is observed by an SEM, it is known that the semiconductor is damaged by irradiation of high-energy electrons. Therefore, in order to observe the sample without destroying the sample, it is desired to reduce the energy of the electron beam. ing. To achieve the above object, an electron beam inspection apparatus according to the present invention comprises a field emission cathode and the field emission cathode.
Focusing means for irradiating the sample with the electron beam generated at the pole
To reduce the irradiation speed of the electron beam on the sample.
A voltage applying means for applying a negative voltage to the sample;
Detect the secondary electron signal generated from the sample by irradiating the bundle
Detecting means, and the secondary electron signal obtained by the detecting means
Means for obtaining a secondary electron image of the sample surface based on
The secondary of the sample surface obtained by the means for obtaining the secondary electron image
Storage means for storing an electronic image; and
Means for obtaining a secondary electron image of the sample surface and the secondary electron image
Comparison with the secondary electron image of the sample surface obtained in step
Means . According to the present invention, the size, the number, and the like of defects in a fine insulating film are reduced by using a low-energy electron beam. The corresponding information is obtained, and the principle will be described below. First, in order to specifically show, for example, the thickness of the insulating film and the incident electron energy, a single crystal Si plate as the metal or semiconductor substrate 1 (FIG. 1) and a single crystal Si plate as the insulating film 2 are thermally treated. Consider an SiO ₂ film obtained by oxidation. FIG. 2 is a graph showing the relationship between the electron beam energy (eV) incident on the SiO ₂ film as the insulating film and the maximum penetration depth Rmax (Å) of the electrons (cited reference: HJ Fitting, Phys.Status Solidi 226 , p.5
25 (1974). The maximum penetration depth of the electrons is defined as an incident area (depth) of electrons until the incident electrons to the insulating film, that is, primary electrons, lose energy by multiple scattering and reach the diffusion area in terms of energy or velocity, ie, equivalent. A transparent region. The term "equivalent" does not mean only the transmission in the sense that one incident electron passes through the insulating film as it is, but also includes the transmission of another electron instead of the incident electron itself due to collision with a plurality of electrons. In the graph of FIG. 2, for example, it is understood that an electron beam must be irradiated with an energy of 300 eV or more in order for electrons to pass through the SiO ₂ film of 100 ° and reach the Si substrate 1. On the other hand, the radiation efficiency of the secondary electron excited by the incident electron beam, that is, the primary electron on the sample surface also depends on the primary electron energy. The secondary electron emission efficiency δ (E) is represented by the ratio of the number N _S of secondary electrons to the number N _P of primary electrons (δ (E) = N _S / N _P ). FIG. 3 shows the primary electron beam energy E (eV) and the secondary electron emission efficiency δ (E).
Is a graph showing the relationship with A, SiO ₂ , B is Poly
-Value for Si (Reference: R. Kouath, Handbuc
h der Physik XXIp.232 (1956). FIGS. 4 (a) to 4 (e) show S on the Si substrate 1. FIG.
For the sample on which the iO ₂ insulating film 2 was formed, the primary electrons e _P
Secondary electron e _S and scattered electron e _d inside the sample
It is a figure which shows the behavior of a model. As shown in FIG. 4A, for example, 100 °
When considering SiO ₂ insulating film 2 thickness of, if electrons primary electrons e _P is accelerated above 300 eV, for scattered electrons e _d reaching the substrate 1 is present, the so-called "electron-beam-induced conductivity (Electronbeam induced conductivit
Based on the phenomenon of "y)", the potential on the surface of the SiO ₂ insulating film 2 becomes almost equal to the potential of the substrate 1, and no charge-up occurs on the surface of the insulating film 2. FIG. Electronic e _P is 300 eV
3 and the secondary electron emission efficiency δ (E) is 1 or more
The case of electrons accelerated at 0 eV or more is shown. Since N _P there are more (primary electrons e number of _P) from also N _S (the number of secondary electrons e _S), because there is no leakage of scattered electrons e _d as in FIG. 4 (a), insulating Positive charges increase on the surface of the film 2, and the surface of the film 2 is charged up. Please note that this charge
Ups increase over time. To prevent the charge-up in FIG. 4 (b), as shown in FIG. 4 (c), a metal mesh or the like is formed in the space above the sample so as to face the electron beam irradiation surface of the sample. An auxiliary electrode 9 is provided, and a DC power supply 10 is connected between the auxiliary electrode 9 and the substrate 1 to apply a potential to the auxiliary electrode 9. Among the generated secondary electrons, those having relatively high energy enter the auxiliary electrode 9 or pass through the auxiliary electrode 9 to reach a secondary electron detector (not shown) with information on the sample surface. . Electrons with very low energy return to the sample surface. In such a configuration, there is a slight leak current between the surface of the insulating film 2 and the substrate 1 in an equivalent circuit, and the potential of the surface of the insulating film 2 is slightly lower than that of the substrate 1 in an equilibrium state. Has a positive potential. As shown, the DC power supply 10 has a negative side on the substrate 1 and a positive side on the auxiliary electrode 9. However, when the potential of the DC power supply 10 is relatively small, the polarity may be reversed. Even if 10 is replaced with a resistor, it is in principle equal. However, in practice, the connection as shown is convenient for increasing the collection amount of secondary electrons. As shown in FIG. 4D, under the same conditions as FIG. 4B or FIG. 4C, when the insulating film 2 has a defect, specifically, whether there is a pin hole in the insulating film 2 or not. If the insulating film 2 is partially thin even if the hole is not completely formed, the defect portion is equivalent to that shown in FIG. That is, the surface potential of the defective portion becomes the same as that of the substrate 1. FIGS. 4B to 4D show the case where the secondary electron emission efficiency δ (E ) is 1 or more, but δ (E) <1.
FIG. 4E shows the case of (1). FIG. 3 shows a case where the primary electron beam energy is accelerated at 2300 eV or more or 30 eV or less. First, 2300e
For more than V, and when the scattered electrons e _d reaches the substrate 1 [delta]
FIG. 4A is the same as FIG. 4A except that the ratio of the number of secondary electrons generated due to the difference in FIG. However, thicker insulating film 2, if the scattered electrons e _d can not reach the substrate 1, the primary electron number N _P of the incident, since most of than the secondary electrons the number N _S being released, Fig. 4 ( Contrary to (b), the surface of the insulating film 2 is charged up due to an increase in negative charges. However, in this case, even if the auxiliary electrode 9 is added as shown in FIG. 4C, this charge-up cannot be prevented since it is a negative potential, and therefore, the surface potential of the insulating film 2 is kept at a constant value. It is impossible to keep. In addition, the latter 3
Even at 0 eV or less, the phenomenon is the same as described above, except that the thickness of the insulating film 2 is different. According to the extrapolation of FIG. 2, the thickness is extremely thin, that is, 10 ° or less, and is a region which is not usually used as an insulating film. The above is summarized as follows. [0030] (1) high energy of the primary electrons e _P incident, if the scattered electrons e _d reaches the substrate 1 and equivalently permeable insulating film 2, the surface potential of the insulating film 2 on the potential of the substrate 1 It is almost equal (Fig. 4 (a)). (2) The energy of the primary electron e _P is low,
If the scattered electrons e _d is a secondary electron generation efficiency [delta] (E) is larger than 1 from the extent not equivalently transmitted through the substrate 1, or <br/> one insulating film 2, the surface potential of the insulating film 2 Indicates a potential maintained in an equilibrium state that is more positive than the potential of the substrate 1 by using the auxiliary electrode 9 (FIGS. 4B and 4C). (3) In the case of the above (2), the insulating film 2
If there is a defect such as a pinhole, the surface potential of the defective portion indicates the potential of the substrate 1 or a potential substantially equal to the potential (FIG. 4D). (4) The primary electrons e _P do not pass through the insulating film 2 equivalently, and the secondary electron generation efficiency δ from the insulating film 2
If (E) is smaller than 1, the surface potential of the insulating film 2 changes to the negative side and cannot reach an equilibrium state (FIG. 4).
(E)). A primary electron beam is scanned on the surface of the sample with an energy that does not allow the primary electrons e _P to pass through the insulating film 2 equivalently, and a secondary electron signal generated by the primary electron beam is detected. Since the difference in the yield of secondary electrons is sensitively reflected, the defect point and the normal part of the insulating film 2 are detected as the difference in the surface potential by utilizing the principles of (2) and (3). Can be distinguished. FIG. 5 is a view showing the principle of the present invention in the case of inspecting a sample in which a metal or semiconductor 3, for example, Poly-Si is formed on the insulating film 2 in isolation. Reference numeral 10 denotes a DC power supply. In such a sample, since the potential of the metal or semiconductor 3 on the insulating film 2 becomes equal to the surface potential of the neighboring insulating film 2, by detecting secondary electrons representing the surface potential of the metal or semiconductor 3, You can know its insulation. However, the yield of secondary electrons itself is that for the metal or semiconductor 3 (see FIG. 3). Embodiments of the present invention will be described below with reference to FIGS. FIG. 6 is a schematic block diagram of an electron beam inspection apparatus according to one embodiment of the present invention. In this figure, 11
Numeral denotes a field emission cathode serving as an electron beam source, which comprises a pointed needle 11a and a W filament 11b bonded thereto. Reference numeral 18 denotes a DC high voltage power supply of about -1 kV,
Is given a potential for field emission. Reference numeral 19 denotes a power supply for energizing and heating the filament 11b to keep it at about 1100 ° C. Reference numeral 12 denotes an anode, 12a denotes a throttle hole of the anode 12, and electrons are emitted from the field emission cathode 11 at a radiation angle of 1/4 rad.
The light is radiated to the aperture 12a to some extent. 13 is the anode 12
A converging means for converging the electron beam flux passing through the aperture hole 12a, that is, a magnetic converging lens, and 21 is a power supply for the magnetic converging lens. 14 is an astigmatism correction coil, 20 is a power supply of the astigmatism correction coil 14, 15 is a deflecting means or scanning coil for scanning an electron beam, 23 is a power supply of the deflection coil 15, 16 is an electron optical system mirror, Reference numeral 17 denotes an exhaust unit including an ion pump; 32, a sample (here, the sample shown in FIG. 5) having the insulating film 2 to which the electron beam converged by the magnetic focusing lens 13 is irradiated; 43, a sample table;
Is an auxiliary electrode made of a metal mesh disposed around the upper part of the sample 32, and 26 and 27 are power supplies. By applying a voltage to the sample 32 and the auxiliary electrode 9, the speed of the electron beam emitted from the field emission cathode 11 is reduced. It serves as deceleration means for decelerating to a predetermined value. The power supplies 26 and 27 can be switched by switches A and B, respectively. Reference numeral 22 denotes a secondary electron detector that collects secondary electrons generated from the sample 32 by irradiation of the electron beam, 28 denotes an amplifier, and 29 includes a cathode ray tube that displays an information signal corresponding to a defect of the insulating film 2. It is a display. Reference numeral 24 denotes an oscillator, 25 denotes a magnification corrector, 30 denotes a comparator, and 31 denotes a pattern generator, which will be described in detail later. Note that the secondary electron detector 22 and the power supply 2
3, an oscillator 24, a magnification corrector 25, an amplifier 28, a display 29, a comparator 30, and a pattern generator 31 constitute display means. The invention has been described one way for the components of the real施例of the present invention, followed by addition of further describes the field emission cathode 11. That is, one important point in carrying out the present invention is to use an electron beam having an energy that does not pass through the insulating film 2 as described above. As the insulating film 2 is thinner, an electron beam with lower energy must be used. However, as described above, according to the principle of electron optics, generally, the lower the energy, the lower the brightness of the electron beam. In order to obtain an electron beam spot diameter as small as possible in a low-speed electron beam, it is necessary to use a high-brightness cathode as an electron beam source. The field emission cathode 11 of this embodiment has an axial orientation <
This is a thermoelectric field emission cathode in which a sharp needle 11a is formed by electric field polishing from a single crystal tungsten W line of 100>, and the adsorption state of a titanium atomic layer of titanium Ti can be maintained in a heated state for a long time via oxygen. Since the work function of this cathode is lower than W at the surface of the point, a similar electron beam current can be obtained at a lower voltage as compared with a W point having the same radius of curvature. In addition, in the case of a normal W-tipped needle, instantaneous high-temperature heating called flushing is performed in order to clean the surface of the tipped needle. The tip becomes dull. On the contrary,
The Ti adsorption type field emission cathode 11 of the present embodiment does not require a high-temperature flushing operation, and can emit a field at a low voltage of about 1 kV in combination with the small work function of the surface of the pointed needle. And high brightness due to field emission despite low accelerating voltage. For such a reason, the power supply 18 uses a DC high voltage power supply of about -1 kV. Next, the principle of the present embodiment in which the energy (velocity) of the electron beam incident on the sample 32 is reduced to a required value, that is, the electron is decelerated to a value that does not pass through the insulating film 2 of the sample 32 equivalently. . That is, the power supply 18
Is -1 kV as described above, and the potential of the sample 32 is the same ground potential as the mirror 16, an electron beam having an energy of 1 keV is incident on the sample 32 from the field emission cathode 11. However, when a decelerating potential, for example, -900 V is applied by the power supply 26 as the electron beam decelerating means provided on the sample 32 as shown in the figure, the energy of the electrons incident on the sample 32 becomes 100 eV. That is, the power supply 26 is set to, for example, the aforementioned -900 V as a deceleration voltage, and by operating the switch A, the speed of electron energy is reduced to a value at which electrons do not equivalently pass through the insulating film 2 of the sample 32. The voltage of the power supply 27 is set to a voltage at which electrons pass through the insulating film 2, for example, -200 V. Therefore, the energy of the electron beam entering the sample 32 is 800 eV. The operation of the electron beam inspection apparatus of the present embodiment configured as described above will be described. When the electron beam decelerated to a required speed by the power supply 26 as the deceleration means is irradiated on the sample 32, secondary electrons are generated, and a part or most of the electrons passing through the auxiliary electrode 9 are secondary. It is collected by the electronic detector 22. As a result, the detection current output from the secondary electron detector 22 is
And is input to the display 29. The deflection signal generated by the oscillator 24 is amplified by the power supply 23 and supplied to the deflection coil 15 that scans the electron beam. The deflection signal of the oscillator 24 is also supplied to the display 29 in synchronization with the display 29, and an information signal corresponding to a defect of the insulating film 2 such as a two-dimensional luminance modulation display or a linear display, which will be described in detail later, is displayed on the display 29. Is displayed. Next, one display example (the above-described two-dimensional luminance modulation display) by the display means of this embodiment and a measurement result by the display will be described with reference to FIG. Fig. 7 (a)
Is a diagram showing the secondary electron image displayed on the screen of the display 29 of the electron beam inspection apparatus of the real施例of the present invention shown in FIG. The cross-sectional structure of the sample 32 is the same as that shown in FIG. 5, the substrate 1 is an Si single crystal plate, and the insulating film 2 is 200.
SiO ₂ , metal or semiconductor 3 has a thickness of 3500 °
poly-Si. More specifically, this sample is a sample in which Poly-Si is linearly formed with a width of 1 μm at intervals of 3 μm, that is, a so-called line and space. Based on FIG. 2, the energy of an electron beam that does not pass through a 200 ° SiO ₂ film is 500 eV or less, so an electron beam of 100 eV is used. FIG.
When the incident energy to the sample 32a is 100 eV (switch A), the secondary electron image displayed on the screen of the display 29 indicates the difference in secondary electron generation efficiency described with reference to FIG. blackened portions of -Si (secondary electron signal is weak), white insulating film SiO ₂ portion is a background (secondary electron signal is strong) visible. Note that FIG.
In (a), there is a whitish line in comparison with the others indicated by the arrow, and it is clear that there is a defect in the insulating film in that part. FIG. 7B will be described later. The analysis of the defective portion of the insulating film 2 is shown in FIG.
A simple pattern such as the sample shown in the display example of (a) or a pattern whose pattern is clearly known in advance can be determined by visually observing the screen of the display 29. In this case, as shown in FIG. 6, a defective portion can be known by comparing with information appearing on the display 29 using a pattern generator 31 and a comparator 30 that generate a pattern input in advance. . A method of analyzing a defective portion of an insulating film in a sample whose pattern is unknown will be described with reference to FIG. That is, by operating the switch B in FIG. 6, a deceleration voltage is applied to the sample 32 by the power supply 27 set to, for example, -200V. Then, this sample 32
The energy of the electron beam incident on the sample is 800 eV, which is 500 eV or more based on FIG. However, since the voltage is 2300 V or less based on FIG. 3, no charge-up occurs. FIG. 7B is a diagram showing a secondary electron image displayed on the screen of the display 29 when the deceleration voltage of the electron beam is set by the power supply 27 as described above.
(A) shows a secondary electron image of the same portion of the same sample. That is, in FIG. 7B, no defective portion is seen, and only information on the outer shape of the pattern originally formed on the sample is shown. As described above, the power source 26 set so that electrons do not pass through the insulating film equivalently is used to see the defective portion, and the electrons are set so as to pass through the insulating film to see the pattern of the sample. Power supply 27 is used. Therefore,
With respect to a sample whose pattern is unknown, a defective portion can be determined by comparing two secondary electron images appearing on the display 29 by switching the switches A and B. At this time, the samples 32 of 100 eV and 800 eV were used.
The magnification of the image appearing on the screen of the display 29 varies depending on the difference in the incident energy of the image. Therefore, the switches C and D are switched according to the switching of the power supplies 26 and 27, respectively, by using the magnification corrector 25 so that the comparison can be performed at the same magnification. By doing so, FIG.
The images (a) and (b) can be compared at the same magnification on the screen of the display 29. Further, in place of the above-mentioned pattern generator 31, a storage device 31 for storing pattern information of either a case where the electron beam energy is high or a case where the electron beam energy is low is provided.
Using the storage device 31 and the comparator 30, the display 29 can display a defective portion. FIG. 8 is a schematic block diagram of an electron beam inspection apparatus according to a reference example of the present invention. In the figure, 33 is a hot cathode, 34 Wehnelt electrode, 35 is a power supply, 26 power supply is a deceleration means of the electron beam, those of the actual施例the same symbols shown in other views 6 indicate the same members. Hot cathode 33, above
Although the brightness is lower than that of the field emission cathode 11 of the embodiment,
When a low acceleration voltage is applied and used, the luminance is further reduced.
Here, the value of the luminance is emphasized in order to reduce the spot diameter of the converged electron beam as much as possible and to obtain a current as large as possible. Therefore, considering this, it can be said that the hot cathode can be used at a low acceleration voltage depending on the purpose. That is, even if the spot diameter is not so small, the function of the defect inspection can be sufficiently performed. Book
In the reference example, a direct heat type lanthanum hexaboride (LaB ₆ ) cathode having the highest luminance among the hot cathodes is used. In the electron beam detector of the reference example having such a configuration, the hot cathode 33 is heated by the power supply 19,
Keep at about 1600 ° C. Then, the Wehnelt electrode 34
When a negative potential with respect to the potential of the hot cathode 33 is applied to the hot cathode 33 by the power supply 35 and a voltage is applied to the hot cathode 33 by the DC high-voltage power supply 18, the Wehnelt electrode 34 and the anode 1
An electron beam is emitted by forming a crossover E as shown between the two. The potential applied to the sample when using the power of about -1kV to the power supply 18, it becomes similar to the actual施例shown in FIG. Although illustration of this reference example is omitted,
The same display means and the like as those in the above embodiment are connected, and the functions thereof are also the same. In the description and examples of the principle of the present invention, the substrate 1 is made of a single crystal silicon plate, the insulating film 2 is made of SiO ₂ , and a metal or a metal isolated on the insulating film 2 is formed. Although the description has been made using Poly-Si as the semiconductor 3, the effect of the present invention does not change even when other materials are used. According to the present invention, a metal or semiconductor substrate is provided.
A sample with an insulating film above, or isolated on that insulating film
Sample with metal or semiconductor of any shape formed by
Of insulating film that could not be inspected before
The size and number of the pits can be detected. In addition, the present invention conducts a non-contact inspection using an electron beam that does not allow electrons to pass through an insulating film to be inspected in a non-contact manner. Can be inspected without damage. Therefore, the element to be inspected can be inspected during the manufacturing process, and the subsequent manufacturing process can be continued after the inspection is completed. Further, the present invention can detect a minute defect portion of about 0.1 μm corresponding to a minute spot diameter of the electron beam. Thus, the effect of the present invention is remarkable.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 (a) is a sectional view of a sample to be inspected, (b),
(C) is a schematic diagram of a conventional inspection device. FIG. 2 is a graph showing a relationship between incident electron beam energy into a SiO ₂ insulating film and the maximum penetration depth of electrons. FIG. 3 is a graph showing a relationship between electron beam energy and secondary electron emission efficiency. FIGS. 4A to 4E are schematic cross-sectional views illustrating the principle of the present invention. FIG. 5 is a schematic sectional view illustrating the principle of the present invention. FIG. 6 is a schematic block diagram of an electron beam inspection apparatus according to one embodiment of the present invention. FIGS. 7A and 7B are diagrams showing the shape of a secondary electron image of a sample projected on a screen of a cathode ray tube display of the electron beam inspection apparatus of the present invention. FIG. 8 is a schematic block diagram of an electron beam inspection apparatus according to a reference example of the present invention. [Description of Signs] 2 ... Insulating film, 9 ... Auxiliary electrode, 11, 33 ... Cathode (electron beam source), 13 ... Magnetic converging lens (Converging means), 15 ...
Deflection coils (deflection means), 26,2 7 ... power supply (reduction means), 29 ... display (display means).

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Chusuke Munakata 1-280 Higashi Koikekubo, Kokubunji-shi, Tokyo Hitachi, Ltd. Central Research Laboratory (72) Inventor Yukio Honda 1-280 Higashi Koikekubo, Kokubunji-shi, Tokyo (56) References JP-A-55-68629 (JP, A) JP-A-48-95767 (JP, A) JP-A-57-165943 (JP, A) Hiroyoshi SOEZIM A, "SOLID SURFACE O" BSERVATION AT VERY LOW ACCELERATING VOLTAGE (200V-1kV) BY SCANNING ELECTRON MICROSCOPE ", Surfence Science 85 (1979) p. 610-619 (58) Field surveyed (Int.Cl. ⁶ , DB name) H01L 21/66 G01N 23/225 H01J 37/22 502

Claims (1)

(57) [Claims] A field emission cathode; a converging means for irradiating the sample with an electron beam generated by the field emission cathode; and a voltage applying means for applying a negative voltage to the sample in order to reduce the irradiation speed of the electron beam on the sample. Detecting means for detecting a secondary electron signal generated from the sample by the convergent irradiation; means for obtaining a secondary electron image of the sample surface based on the secondary electron signal obtained by the detecting means; 2 of the sample surface obtained by the means for obtaining the secondary electron image
Storage means for storing a secondary electron image; comparing the secondary electron image of the sample surface stored in the storage means with the secondary electron image of the sample surface obtained by the means for obtaining the secondary electron image An electron beam inspection apparatus comprising: a comparison unit. 2. 2. An electron beam inspection apparatus according to claim 1, wherein said field emission cathode means is a single-crystal pointed needle having an axial orientation of <100>. 3. 2. An electron beam inspection apparatus according to claim 1, wherein said field emission cathode means is a single-crystal pointed needle having an axial orientation of <310>. 4. 2. An electron beam inspection apparatus according to claim 1, wherein said field emission cathode means is a thermal field emission cathode.