JP4559063B2 - Method for measuring surface potential distribution and apparatus for measuring surface potential distribution - Google Patents

Description

  The present invention relates to a surface potential distribution measuring method and a surface potential distribution measuring apparatus.

  A method of observing or measuring the surface potential distribution on the object surface by scanning with an electron beam is known (Patent Document 1, etc.). This method observes or measures the surface potential distribution by scanning a measurement sample having a surface potential distribution with an electron beam and detecting secondary electrons generated in the measurement sample along with the scanning. The sample to be measured is an LSI chip or the like that “can hold a charge on its surface for a sufficiently long time”.

  The electrostatic latent image formed on the photoconductive photoconductor by charging / exposure in analog or digital electronic copying machines or optical printers is a “factor that directly affects the behavior of toner particles”. It is important to evaluate the quality of the electrostatic latent image on the body. If the electrostatic latent image on the photoconductor can be measured and the results can be fed back to the design, the process quality in the charging and exposure processes can be improved, resulting in image quality, durability, stability, and energy saving Further improvement can be expected.

  However, since the electrostatic latent image formed on the photoconductive photoreceptor disappears in a short time due to dark decay, the “measurable time” is only about several tens of seconds. Then, since the electrostatic latent image disappears in the measurement preparation stage, the measurement cannot be performed. The inventor has proposed a measurement method capable of measuring even an electrostatic latent image on a photoreceptor having dark decay (Patent Documents 2 and 3).

  In the invention described in Patent Document 1, secondary electrons generated in the scanned measurement sample are detected along with the scanning of the electron beam. The amount of secondary electrons emitted is “the material of the measurement sample and the unevenness of the surface. Since it depends on the “state”, theoretical prediction and “control of the amount of secondary electron emission for regulating the correspondence between the surface potential distribution and the amount of secondary electron emission” are not easy.

Japanese Patent Laid-Open No. 3-49143 Japanese Patent Application No. 2002-103355 Japanese Patent Application No. 2003-43587

The present invention provides a surface potential distribution measuring method capable of measuring the surface potential distribution of an object with very high accuracy without using secondary electrons, and a photoconductive photosensitive device as a surface potential distribution measuring apparatus for carrying out this measuring method. An object of the present invention is to realize a surface potential distribution measuring apparatus capable of satisfactorily measuring a surface potential distribution by an “electrostatic latent image with dark decay” formed on a body .

The surface potential distribution measuring method according to the present invention is “a method in which a charged particle beam is scanned two-dimensionally on a sample having a surface potential distribution, and the surface potential distribution of the sample is measured by a detection signal obtained by this scanning”. And having the following characteristics (claim 1) .
That is, the surface potential distribution to be measured is an “electrostatic latent image”, and is formed by uniform charging and exposure of the photoconductive sample to the sample surface. That is, a “sample having a surface potential distribution” is a photoconductive sample on which an electrostatic latent image is formed .

Among the charged particles incident on the sample surface by two-dimensional scanning of the charged particle beam, the repulsion is caused by the surface potential of the photoconductive sample, and the incident velocity vector of the sample at the surface of the sample does not reach the photoconductive sample. Only the charged particles whose “normal direction component” is inverted are detected to obtain a detection signal.
“Two-dimensional scanning” means that a two-dimensional area of a sample is uniformly scanned with a charged particle beam.

Here, the “surface potential distribution (electrostatic latent image) ” as the object of measurement is the potential on the substantial surface of the photoconductive sample, that is, the “surface of the sample and its immediate vicinity (about several μm from the surface)”. Distribution .

The photoconductive sample is planarly supported by a sample support means having a conductive layer, and the photoconductive sample supported by the support means is irradiated with a charged particle beam scanned two-dimensionally by a charged particle optical system. Thus, after the photoconductive sample is uniformly charged to a desired potential, the uniformly charged photoconductive sample is exposed to light and exposed to light, and the electrostatic potential that is the surface potential distribution as the measurement target is measured. A latent image is formed.
Then, two-dimensional scanning with a charged particle beam is performed in a state where the photoconductive sample on which the electrostatic latent image is formed is supported by the sample support means. By applying a bias voltage to the “conductive layer of the sample support means” during this scanning, the surface potential distribution formed on the photoconductive sample is changed. Since the bias voltage is applied to the “conductive layer” of the support member, the conductive layer becomes a uniform potential due to the bias potential, and the “potential of the surface having the surface potential distribution of the measurement sample” is changed substantially uniformly. The polarity of the bias potential can be the same as or opposite to the polarity of the surface potential distribution as the measurement target.

2. The surface potential distribution measuring method according to claim 1, wherein the bias potential is changed by changing a uniform bias potential applied to the conductive layer of the sample support means with respect to the surface potential distribution on the surface of the photoconductive sample. It is possible to perform measurement for each and “calculate a profile of the surface potential distribution in an arithmetic manner” based on a plurality of measurement results obtained ( claim 2 ).

In the surface potential distribution measuring method according to claim 1 or 2, the acceleration voltage with respect to the charged particles of the charged particle beam scanned two-dimensionally with respect to the sample is changed, and the measurement is performed each time the acceleration voltage is changed. perform, based on a plurality of measurement results obtained, it is possible to determine the profile of the surface potential distribution computationally (claim 3). In the case of the measuring method according to claim 3 , each time a uniform bias potential is applied to the surface potential distribution on the surface of the photoconductive sample and “at least one of the acceleration voltage and the bias potential” is changed. was measured, based on a plurality of measurement results obtained, it is possible to determine the profile of the surface potential distribution computationally (claim 4). That is, the measuring method according to claim 2 and the measuring method according to claim 3 can be used together.

5. The surface potential distribution measuring method according to claim 1, wherein an electron beam is used as a charged particle beam for two-dimensionally scanning a sample having a surface potential distribution. 5 ) or “ion beam” can be used ( claim 6 ).

The surface potential measurement method according to any one of claims 1 to 6 , wherein the charged particle irradiation direction is “a method in which a charged particle beam incident direction is a measurement sample surface in a central portion of a scanning region”. However, the present invention is not limited to this, and “a charged particle beam can be incident on a sample having a surface potential distribution from an oblique direction with respect to a scanning region” ( claim 7 ).

As described above, the surface potential distribution measuring method according to any one of claims 1 to 7 is “surface potential distribution by an electrostatic latent image formed on a photoconductive photoreceptor” as a photoconductive sample. Can be measured as a measurement object .
In the case where the photoconductive photosensitive member has a structure in which a photoconductive layer having a photoconductive function is formed on the surface of the conductive substrate, the conductive substrate itself can be used as a sample support means.

A surface potential distribution measuring apparatus according to claim 8 is an apparatus for carrying out the measuring method according to any one of claims 1 to 7, comprising a sample support means, a charging means, an exposure means, and a voltage applying means. , Charged particle beam scanning means and measuring means.
“Supporting means” is a means that consists of a dielectric layer and a conductive layer, and supports the photoconductive sample as a measurement sample on the conductive layer in a planar manner with the surface forming the surface potential distribution as the surface to be scanned. is there.
“Charging means” is means for uniformly charging the photoconductive sample supported by the sample support means.
The “exposure unit” is a unit that exposes the photoconductive sample uniformly charged by the charging unit by irradiation with a light image to form an electrostatic latent image as a surface potential distribution on the photoconductive sample.
"Voltage applying means" a bias potential is applied to the conductive layer of the specimen support means is means you superimposing a uniform bias potential to the surface potential distribution formed on the photoconductive sample.
“Charged particle beam scanning means” is a two-dimensional representation of the surface of a photoconductive sample that has been set at a scanning position by a charged particle beam and on which an electrostatic latent image has been formed by a charging means / exposure means. Means for scanning.

  The “measuring means” is a charged particle beam in which the normal component of the incident velocity vector on the sample surface is reversed without reaching the photoconductive sample due to the surface potential of the photoconductive sample. This is means for capturing particles by a capturing means, detecting the intensity (number of particles) corresponding to the position on the sample surface, and measuring the surface potential distribution state.

The surface potential distribution measuring apparatus according to claim 8 is a "bias potential variable means" for changing a bias potential applied by " a bias potential applying means for applying a uniform bias potential to the surface potential distribution on the sample surface"; based on the measurement result in the application state of two or more different bias potentials to determine the profile of the surface potential distribution computationally can have "operation device" (claim 9).

The apparatus for measuring surface potential distribution according to claim 8 or 9 includes an acceleration voltage varying means for changing the “acceleration voltage for charged particles” of a charged particle beam scanned two-dimensionally with respect to the sample, and two or more different acceleration voltage based on the measurement result by, determining the profile of the surface potential distribution computationally may have a "calculation unit" (claim 10), a uniform bias potential for this case, the surface potential distribution of the sample surface A bias potential applying means for applying a bias potential and a bias potential varying means for changing the bias potential applied by the bias potential applying means, and based on the measurement result in a state where “at least one of the bias potential or the acceleration voltage” is different, it can be configured to have a calculation means for obtaining a profile of the potential distribution computationally (claim 11).

The surface potential distribution measuring apparatus according to any one of claims 8 to 11 , wherein an electron gun is used as a “charged particle beam generation source” for two-dimensionally scanning a sample having a surface potential distribution ( can either claim 12) that can be used to "liquid metal ion gun" (claim 13).

14. The surface potential distribution measuring apparatus according to claim 8 , wherein the charged particle beam scanning unit is set to "inject the charged particle beam from the oblique direction with respect to the scanning region" and captured by the measuring unit. The means can be arranged “on the side opposite to the incident direction of the charged particle beam through the scanning region” ( claim 14 ).

As described above, the surface potential distribution measuring apparatus according to claims 8 to 13 “measures the surface potential distribution by the electrostatic latent image formed on the photoconductive photoreceptor (photoconductive sample) as a measurement object. Is.

The above-mentioned “exposure means” can be a projection exposure of a mask pattern (claim 15), or can be a “write latent image pattern by optical scanning” (claim 17).

16. The surface potential distribution measuring apparatus according to claim 15, wherein the exposure means is configured to “set an optical path for exposure outside a region through which a charged particle beam that performs two-dimensional scanning of a photoconductive sample passes”. Preferred ( claim 16 ).

The surface potential distribution measuring apparatus according to any one of claims 8 to 17 , wherein the exposure means may include a semiconductor laser as a light source for exposure ( claim 18 ). In the surface potential distribution measuring apparatus according to any one of claims 8 to 18 , it is preferable that the exposure time of the exposure means can be controlled ( claim 19 ).

The surface potential distribution measuring apparatus according to any one of claims 8 to 19 , wherein the charged particle beam scanning means is configured to uniformly charge the photoconductive sample with an electron beam that is two-dimensionally scanned. can the particle beam scanning means configured to "serve as the charging means photoconductive sample" (claim 20).

As described above, in the “surface potential distribution measuring method and surface potential distribution measuring apparatus” of the present invention, among the charged particles incident on the sample surface of the photoconductive sample by the two-dimensional scanning of the charged particle beam, the photoconductive property is measured. the surface potential of the sexual samples, without reaching the photoconductive samples to obtain a detection signal by detecting only the charged particles, "the normal direction of the component in the sample surface" is inverted in the incident velocity vector. In other words, the charged particles to be detected are charged particles constituting a charged particle beam that scans the sample surface, not secondary electrons generated on the sample surface.

When detecting secondary electrons, the amount of secondary electrons emitted depends on the material of the photoconductive sample and the surface roughness, and theoretical predictions and “correspondence between surface potential distribution and amount of secondary electrons emitted. However, the detection particles in the present invention are not secondary electrons, so the above-mentioned problem in detecting secondary electrons does not occur. The surface potential distribution can be measured accurately and easily with certainty using the electrostatic latent image formed on the photoconductive sample as a measurement target .

FIG. 1A shows only one part of one form of the surface potential distribution measuring apparatus .
This apparatus measures the surface potential distribution of sample 0. Each part of the apparatus is housed in a hermetic casing 27, and the inside of the hermetic casing 27 can be decompressed to a “substantial vacuum state” by the suction means 29.
Sample 0 is a photoconductive photoreceptor (photoconductive sample), and the surface potential distribution as a measurement target is an electrostatic latent image. As described later, an electrostatic latent image is formed in a sealed casing 27. It is formed by arranging means (not shown in FIG. 1).

In FIG. 1A, it is assumed that the surface potential distribution is formed as an electrostatic latent image on the sample 0 and the inside of the sealed casing 27 is decompressed.
In this embodiment, an “electron beam” is used as a charged particle beam that scans the sample 0 two-dimensionally. That is, the electron beam is generated by the electron gun 10, passes through the beam monitor 13, passes through the condenser lens 15 while converging the positions of the aperture 17 and the beam blanker 18, and is two-dimensionally scanned by the scanning lens 19 over the deflection coil. Biased. The electron beam deflected in this way is focused toward the surface of the sample 0 by the objective lens 21.

  The beam monitor 13 is for monitoring the intensity of the electron beam emitted from the electron gun 10, and the aperture 17 is the “current density (number of irradiated particles per unit time) of the electron beam irradiated on the sample 0. The beam blanker 18 is for “turning the electron beam on and off”. Each unit arranged in the electron beam irradiation path from the electron gun 10 to the sample 0 is connected to a power source (not shown), and these are controlled by a control means such as a computer (not shown).

As described above, the electron beam deflected two-dimensionally by the scanning lens 19 scans the surface of the sample 0 two-dimensionally.
In the example in the description, the sample 0 having the surface potential distribution is “charged negatively on the surface or in the vicinity of the surface” and has a surface potential distribution corresponding to the charged state. The sample 0 is planarly supported by a support portion 23 as a sample support means as shown in the figure. The support portion 23 is a “conductive plate-like member” and is grounded. The surface potential distribution of the sample 0 forms a “potential barrier that applies a strong repulsive force to each electron of the electron beam” in the very vicinity of the sample surface.

As shown in FIG. 1B, the z direction is “the direction of the normal line upright on the surface of the sample 0”, the x axis and the y axis are taken in parallel to the sample surface, and the (x, y) coordinates are set on the surface of the sample 0. Set (y direction is orthogonal to the drawing).
At this time, if “region scanned two-dimensionally by an electron beam: S” is expressed by S (x, y) using two-dimensional coordinates, for example, 0 mm ≦ x ≦ 1 mm and 0 mm ≦ y ≦ 1 mm. is there. The surface potential distribution formed in this region: S (x, y) is V (x, y) (<0).
Assuming that the time from the start to the end of the two-dimensional scanning of the sample 0 by the electron beam is T ₀ ≦ T ≦ _TF , the time when scanning is performed: T is the scanning region: S (x, It corresponds to each scanning position in y) 1: 1.

  FIG. 1B illustrates the situation near the sample in an explanatory manner. The size of the “scanned region: S” in the sample 0 can be changed by setting the magnification of the scanning lens 19. For example, variously from a low magnification of about 5 mm × 5 mm to a high magnification of about 1 μm × 1 μm. It can be observed at a high magnification.

  The velocity of the electron beam emitted from the electron gun 10 is “v”, and the components in the x, y, and z directions are “vx, vy, vz”. Strictly speaking, the velocity components of each electron in the electron beam: vx, vy, and vz change with the scanning of the electron beam, but the distance from the objective lens 21 to the surface of the sample 0 is the actual measurement apparatus size. Since the scanning area of the sample 0 is as large as about 5 mm × 5 mm as described above, under this condition, vx = vy = 0 and vz = v. You may think.

At this time, in the scanned electron beam, the kinetic energy of the electrons towards the surface of the sample 0 is a mv ^2/2 electrons mass as m, which, accelerator acceleration provided to the electron gun 10 voltage: Va and electron charge: equal to the product of e, which is therefore ^"mv 2/2 = e · Va".

Since the surface potential distribution V (x, y) formed in the scanning region S (x, y) of the sample 0 is the same polarity as the electron and acts as a barrier potential for the electron.
^{mv 2/2 = e · Va} > -e · V (x, y)
If so, the electrons of the electron beam pass through the potential barrier and reach the surface of the sample 0.
^{mv 2/2 = Va <-e} · V (x, y)
If so, the electron is decelerated by the barrier potential, its velocity: vz becomes 0, and is pushed back in the incident direction by the surface potential of the sample 0. That is, the electrons pushed back in this way have their velocity: vz (component of the incident velocity vector in the normal direction on the sample surface) reversed from the “direction at the time of incidence”.

  This state is shown in FIG. FIG. 2A shows the case where Va <−V (x, y) and “the velocity of electrons: vz is reversed from the direction of incidence”, and FIG. 2B shows Va> −V (x, y y) shows the case where the electrons of the electron beam reach the surface of the sample 0 through the potential barrier.

  As described above, the repulsive force of the surface potential distribution: V (x, y) indicates that “the component in the normal direction (z direction) of the incident velocity vector on the sample surface: the electron whose vz is inverted (hereinafter“ velocity component inversion electron ”). Is captured by the detector 25 (FIG. 1). As shown in FIG. 1B, a “drawing voltage” having a polarity opposite to that of electrons (positive polarity) is applied to the detector 25 from the power supply EA, and the “velocity component inversion electrons” are captured by this drawing voltage. . The trapped velocity component inversion electrons are amplified by an electron multiplier or the like and converted into a detection signal corresponding to the intensity (the number of velocity component inversion electrons captured per unit time).

  Since the velocity component inversion electrons captured by the detector 25 are repelled by the surface potential distribution of sample 0: V (x, y), the intensity of velocity component inversion electrons captured at time: T: F (T) has a correspondence relationship with surface potential distribution: V {x (T), y (T)} with time: T as a parameter.

  In the case described above, the velocity component inversion electrons captured by the detector 25 satisfy Va <−V (x, y). Therefore, the measurement result is “surface potential distribution of sample 0: V ( x, y) is obtained by regionally dividing the acceleration voltage: Va in the electron gun 10 into two regions using a measurement threshold value.

  That is, in the scanning region: S (x, y), the “region in which velocity component inversion electrons are captured” is a region of surface potential distribution: −V (x, y)> Va, and the above velocity component inversion electrons. The region where no is captured is a region of surface potential distribution: −V (x, y) <Va.

  Therefore, by sampling the detection signal obtained from the detector 25 at an appropriate interval, it is possible to specify for each “small region corresponding to sampling” whether −V (x, y) is larger or smaller than the measurement threshold value Va. .

In the above, the case of the “electron beam” as the charged particle beam has been described. However, in the above example, if the “liquid metal ion gun” is used instead of the electron gun 10, the measurement using the ion beam as the charged particle beam is performed. It can be carried out.
When the surface potential distribution of the sample 0: V (x, y)> 0, positive ions such as gallium or protons may be used as charged particles of the charged particle beam.
In general, when the maximum absolute value of the surface potential distribution: V (x, y) is Max | V (x, y) |, the acceleration voltage Va is
Va <Max | V (x, y) |
By scanning the charged particle beam under the following conditions, it is possible to specify the “surface magnitude: V (x, y)“ measurement threshold: magnitude relationship with Va ”.

  The surface potential distribution shown in FIG. 3 is V (x, y) (<0, the surface potential distribution when the surface on the support portion 23 supporting the sample 0 is in a grounded state) at the center portion (x = 0). The potential increases in the minus direction as the distance from the center is approximately −520V, and is approximately −830V in the peripheral region that is 0.01 mm or more away from the center.

With respect to such a surface potential distribution: V (x, y), an area where V (x, y)> − 600 V is measured when the acceleration voltage: Va is −600 V and −750 V: S600, and Region of V (x, y)> − 750 V: S750 is shown. In these regions S600 and S750, the number of electrons detected by the detector is very small.

  If measurement is performed by switching the acceleration voltage: Va to a plurality of stages, a surface potential distribution: V (x, y) can be obtained as an acceleration voltage for each measurement (that is, a threshold for measurement): a region in which each Va is rounded. By using these, the “surface potential distribution: the overall state of V (x, y)” can be specified by calculation. Of course, the finer the step of switching the acceleration voltage: Va and the higher the number of measurements, the more accurate measurement becomes possible.

  Above, by changing the acceleration voltage Va by the accelerator provided in the electron gun 10, the threshold value of measurement (of the electrons incident on the sample surface, the velocity component in the normal direction of the sample surface is inverted) However, as another method of changing the measurement threshold, there is a method of applying a uniform bias potential to the surface potential distribution on the sample surface. .

An embodiment in this case will be described with reference to FIG.
In FIG. 4, a support part (sample support means) 230 for supporting the sample 0 in a planar manner has a three-layer structure in which a dielectric layer 232 is sandwiched between conductive layers 231 and 233, and the conductive layer 233 is installed. A bias voltage is applied to the conductive layer 231 from the variable DC power supply EB.

  When a bias voltage is applied to the conductive layer 231, the potential distribution on the surface side of the sample 0 is obtained by superimposing a “uniform bias potential” on the surface potential distribution of the sample 0. In the case of using an electron beam as the charged particle beam, the electron beam acceleration voltage: Va is sufficiently increased in advance, and the polarity of the bias voltage applied to the conductive layer 231 is set to have a negative polarity so as to be incident as an electron beam. A bias potential that repels electrons is formed.

Assuming that the original surface potential distribution of sample 0 is V (x, y) and the potential superimposed by applying the bias voltage is V _B (<0), the electric field acting on the incident electrons is near the surface of sample 0. And
V (x, y) + V _B
Therefore, with respect to the acceleration voltage: Va (this value is constant),
Va <− {V (x, y) + V _B }
If so, the electrons become velocity component inversion electrons and are detected by the detector 25,
Va> − {V (x, y) + V _B }
Then, the electrons reach the sample 0.

For example, in the example of FIG. 3, if acceleration voltage: Va = 1.6 kV is set and −1000 V is applied as bias voltage: V _B , the region where the reversal of the velocity component repelled on the sample surface is not detected is shown in FIG. 3 area S600 is obtained, the bias voltage: by setting the V _B to -850 V, as a region where the velocity component inversion electrons is not detected, the area S750 of FIG. 3 is obtained. Alternatively, the bias voltage: the _{V B} constant value: while keeping the -1000 V, applied voltage: by changing from 1.6kV to 1.75kV the Va, it is possible to obtain the region S750.

When measuring the “potential distribution by the conductor pattern” when the sample is a conductor, a method of applying a bias voltage to the back surface and a method of weighting the bias voltage to the voltage applied to the conductor itself may be used.
Applies a bias voltage, when changing at least one of a change in the bias voltage or the acceleration voltage to "threshold measurement", and the polarity of the "surface potential of the charge polarity and the sample 0 of charged particles in a charged particle beam In the case of “reverse polarity”, the surface potential distribution can be measured. For example, if the surface potential distribution of the sample is V (x, y)> 0, the acceleration voltage of the electron beam is Va, and the bias voltage is VB (<0),
Va <V (x, y) -VB
Or
Va> V (x, y) -VB
Depending on whether the velocity component of the incident electrons in the z direction is reversed or not.

Thus, accelerating voltage: Va and the bias voltage: by varying one or both of V _B, it is possible to change the threshold of the measurement, making measurements every time of changing the threshold value of the measurement in this way Thus, an overall image of the surface potential distribution can be obtained by calculation. The calculation result can be easily displayed as, for example, a three-dimensional figure on the display.

  The case where the incident direction of the charged particle beam that scans the sample 0 two-dimensionally is “substantially orthogonal to the sample surface” has been described above. However, as in the embodiment shown in FIG. In addition, a charged particle beam (an electron beam is assumed in the example in the figure) can be made incident from an “oblique direction with respect to the scanning region of the sample 0”. Also in this case, the detector 25 detects “a charged particle that is incident on the sample surface, a charged particle having an inverted velocity component: vz in the normal direction of the incident velocity vector on the sample surface, that is, velocity. “Inverted particles”.

  When the configuration as shown in FIG. 5 is adopted, for example, even a slight change in the bias voltage applied to the conductive layer 231 has a merit in measurement because the number of velocity component inversion particles changes sensitively. Further, the “drawing voltage” of the detector 25 can be reduced, and separation from secondary electrons generated in the sample 0 is easy. Further, by changing the incident angle of the charged particle beam to the sample 0, the above-described “measurement threshold value” can be changed. In addition, the degree of freedom of layout of each part of the measuring apparatus is increased.

  The surface potential distribution as shown in FIG. 3 is a “latent image”, and its profile (V (x, y) in FIG. 3 is a shape “latent image profile” viewed from, for example, the y direction (direction orthogonal to the drawing). ”) Is taken as an example, and a simple description will be given according to the flowchart of FIG. 6 showing the procedure.

  For the sake of concreteness of explanation, here, it is assumed that the measurement threshold is changed by “change in bias potential” and the measurement threshold is switched to N stages.

  In the state of “start” in step SP1, the sample is set in the measuring apparatus, the parameter indicating the number of measurements: j is set to j = 1, and the bias potential of the first stage (j = 1): Vth (j = 1) is set (step SP2).

Subsequently, a contrast image is captured.
The “contrast image” is a “surface potential distribution: a region obtained by rounding the surface potential distribution V (x, y) for each threshold value for each measurement” as indicated by reference numerals S600 and S750 in FIG. The data is processed and imported into a computer as “calculation means” as digital data.

  Subsequently, in step SP4, the latent image diameter: Dj, that is, “the diameter of the contrast image in the x direction” is calculated based on the acquired data. Next, the value of parameter j is incremented by 1 (step SP6), a new measurement threshold value is set, and a contrast image is taken in and a latent image diameter is calculated. When this process is performed by incrementing the parameter: j by 1 until j = N, the latent image diameters: D1 to DN correspond to the N-level measurement thresholds Vth (1) to Vth (N) that change stepwise. Thus, the latent image profile can be calculated and calculated using a computer.

  Here, the detector 25 shown in FIGS. 1, 4 and 5 will be briefly described. The detector 25 is a combination of a scintillator (phosphor) and a photomultiplier tube. Since the repelled velocity component inversion electrons have low energy, they are captured by the scintillator and converted into scintillation light by the electric field of the drawing voltage applied to the surface of the scintillator by the power source EA. This light is amplified as a current by a photomultiplier tube through a light pipe and is taken out as a current signal.

Usually, since the drawing voltage applied to the scintillator is about 10 kV, the electric field formed by the drawing voltage in the vicinity of the surface of the sample 0 is as small as about 10 ⁴ to 10 ⁶ V / m, and depends on the surface potential distribution of the sample 0. In a region where the electric field is larger, electrons near the sample surface are easily affected by the electric field from the sample.

  Since the secondary electrons generated in the sample 0 by the electron beam scanned on the sample 0 have a small energy, most of the secondary electrons are pulled back to the sample 0 side and captured by the detector 25 is very small. In particular, by disposing the detector 25 on the side opposite to the incident direction through the scanning region in which the electron beam is “obliquely incident” as shown in FIG. Thus, the rate at which “secondary electrons generated in the sample 0” are captured can be further reduced, and the S / N ratio of the measurement can be improved.

  A microchannel plate (MCP) may be used instead of the scintillator. When MCP is used, it is possible to collect and amplify the electrons trapped in the MCP by a collecting electric field applied to the input surface of the MCP to “increase by several thousand times”, and obtain a good detection signal. be able to.

In the embodiment described above, the charged particle beam is scanned two-dimensionally with respect to the sample 0 having the surface potential distribution, and the surface potential distribution of the sample is measured by the detection signal obtained by this scanning. There is a measuring method for obtaining a detection signal by detecting charged particles having an incident velocity vector reversed in a normal direction component: vz of the incident velocity vector among charged particles incident on the sample surface by two-dimensional scanning. To be implemented .

In the case of the embodiment shown in FIGS. 3 and 4, a uniform bias potential is applied to the surface potential distribution on the sample surface , and the uniform bias potential is applied to the surface potential distribution on the sample surface. : Measurement is performed each time VB is changed and the bias potential is changed, and a profile of the surface potential distribution can be obtained in an arithmetic manner based on a plurality of measurement results obtained .

In addition, the acceleration voltage: Va with respect to the charged particles of the charged particle beam scanned two-dimensionally with respect to the sample 0 is changed, and measurement is performed each time the acceleration voltage: Va is changed, and based on a plurality of measurement results obtained. The surface potential distribution profile can be calculated computationally . Furthermore, a uniform bias potential: VB is applied to the surface potential distribution on the sample surface, and the bias potential: VB is changed to accelerate voltage: Measurement is performed every time Va and / or bias potential: VB is changed, and a profile of the surface potential distribution can be obtained in an arithmetic manner based on a plurality of measurement results obtained .

In each embodiment described above, as the charged particle beam that two-dimensionally scans the sample 0 having a surface potential distribution, the electron beam is Ru is used, "ion beam" as a charged particle beam The charged particle beam can also be “incident from the oblique direction” with respect to the scanning region of the sample 0 as in the embodiment shown in FIG.

The surface potential distribution measuring apparatus whose embodiment is shown in FIG. 1 is an apparatus for carrying out a surface potential distribution measuring method, and a surface having a surface potential of a sample 0 having a surface potential distribution is charged with a charged particle beam. The charged particle beam scanning means 10 to 21 etc. that scans two-dimensionally at the same time, and among the charged particle beam, the charged particles whose incident velocity vector is inverted in the normal direction on the sample surface are captured by the capturing means 25. Measuring means (such as a computer (not shown)) for detecting the intensity corresponding to the position on the surface and measuring the surface potential distribution state .

In the surface potential distribution measuring apparatus shown in FIG. 4 and FIG. 5, the apparatus has bias potential applying means (support 230 and power source EB) for applying a uniform bias potential to the surface potential distribution on the sample surface . Bias potential variable means EB for changing the bias potential applied by the bias potential application means, and calculation means for calculating the profile of the surface potential distribution on the basis of the measurement results in the application state of two or more different bias potentials (illustrated) A computer that is not) .

In addition, the measurement is performed using acceleration voltage variable means (accelerator provided in the electron gun 10) for changing the acceleration voltage for the charged particles of the charged particle beam that is two-dimensionally scanned with respect to the sample 0, and two or more different acceleration voltages. Based on the result, a calculation means (such as a computer (not shown)) for calculating a profile of the surface potential distribution is obtained .

Also, as in the embodiment of FIGS. 4 and 5, the bias potential applying means (support 230 and power source EB) for applying a uniform bias potential to the surface potential distribution on the sample surface and the bias potential applying means A bias potential varying means (power supply EB) for changing the applied bias potential, and computing means for calculating the profile of the surface potential distribution based on the measurement result in a state where the bias potential and / or the acceleration voltage are different ( A computer not shown) .

Each measuring apparatus described above has the electron gun 10 as a generation source of a charged particle beam that scans the sample 0 having the surface potential distribution two-dimensionally, but as described above. Further, a liquid metal ion gun can be provided as a charged particle beam generation source. As in the embodiment shown in FIG. 5, the charged particle beam scanning means causes the charged particle beam to enter the scanning region from an oblique direction. In this way, the capturing means 25 in the measuring means may be arranged on the opposite side to the incident direction of the charged particle beam via the scanning region .

Hereinafter, the case where “measurement is performed using the surface potential distribution of the electrostatic latent image formed on the photoconductive photoreceptor as a measurement target” will be described in detail .

  As described above, since the electrostatic latent image formed on the photoconductive photoconductor has a “measurable time” of only about several tens of seconds due to dark decay, the measurement sample 0 is the photoconductive photoconductor. In the case of (photoconductive sample), the “electrostatic latent image forming means” is disposed in the sealed casing.

  FIG. 7 is a diagram showing one embodiment of a surface potential distribution measuring apparatus having such an “electrostatic latent image forming unit”. In the figure, the electron gun 10, the beam monitor 13, the condenser lens 15, the aperture 17, the beam blanker 18, the scanning lens 19, the objective lens 21, and the support portion 23 are the same as those in the embodiment shown in FIG. Therefore, the description relating to FIG. 1 is incorporated.

  The electron gun 10, the beam monitor 13, the condenser lens 15, the aperture 17, the beam blanker 18, the scanning lens 19, and the objective lens 21 constitute a charged particle beam irradiation unit 11A, and each of the charged particle beam irradiation units 11A. The components are controlled by the charged particle beam control unit 31, and the charged particle beam irradiation unit 11A and the charged particle beam control unit 31 constitute a “charged particle beam scanning unit”.

  Sample 0 is a “photoconductive photoreceptor”, and is supported in a planar manner on the upper surface of a grounded conductive support portion 23.

  Reference numeral 34 denotes a semiconductor laser as a light source, reference numeral 35 denotes a collimating lens, reference numeral 36 denotes an aperture, reference numeral 37 denotes a mask, and reference numerals 38, 39, and 40 denote lenses constituting an “imaging lens”. These constitute a “light image irradiation unit” and constitute an “exposure means” together with the semiconductor laser control unit 33 and a light image irradiation control unit (not shown).

  A light image irradiation control unit (not shown) can perform focusing and magnification conversion by adjusting the positional relationship between the imaging lenses 38, 39, and 40 and the mask 37.

  Reference numeral 25 denotes a detector (capturing means), reference numeral 26 denotes a signal processing unit, reference numeral 26A denotes a monitor, and reference numeral 28 denotes an output device such as a printer. The detector 25, the signal processing unit 26, the monitor 26 </ b> A, and the output device 28 constitute “measurement means”. Reference numeral 29 denotes a light-emitting element for charge removal.

  Each of the above parts is disposed in the casing 30 as shown in the figure, and the inside of the casing can be highly decompressed by the suction means 32. That is, the casing 30 functions as a “vacuum chamber”. The entire apparatus is controlled by a host computer 50 (control means, which controls each part of the apparatus comprehensively). The charged particle beam control unit 31 and the signal processing unit 26 described above can be set as “part of their functions” in the host computer 50.

  In the state shown in FIG. 7, the sample 0 whose surface is uniformly charged is placed on the support portion 23, and the inside of the casing 30 is highly decompressed. In this state, the semiconductor laser 34 is turned on to form an optical image of the mask 37 on the uniformly charged surface of the sample 0. By this exposure, a pattern of an electrostatic latent image corresponding to the irradiated light image is formed on the sample 0.

  The surface on which the pattern of the electrostatic latent image is thus formed is scanned two-dimensionally with an electron beam, and as described above, the velocity component inversion electrons repelled by the barrier potential due to the surface potential of the sample 0 are detected by the detector 25. Is detected, and its intensity is detected and converted into an electric signal.

  As in the above-described embodiment, the acceleration voltage: Va is switched, and the measurement is repeated each time the switching is performed. The signal processing unit 26 can calculate and output the result to the output device 28.

In order to form a pattern of an electrostatic latent image on the sample 0, which is a photoconductive sample, it is necessary to uniformly charge the surface prior to exposure with the light image.
In the embodiment of FIG. 7, the charged particle beam scanning unit 11A is used to perform charging with an electron beam.

  That is, when the sample 0 is irradiated with the electron beam, “secondary electrons” are generated from the photoconductive sample SP by the impact of the irradiated electrons, but the amount of electrons irradiated to the sample 0 as the electron beam is generated 2. In the balance with the amount of secondary electrons, the amount of secondary electrons emitted: the amount of irradiated electrons with respect to R2: the ratio of R1: If R1 / R2 is 1 or more, the amount of electrons irradiated by subtraction is the amount of secondary electrons. The difference between the two is accumulated in the photoconductive sample SP, and the sample 0 is charged.

Accordingly, the amount of electrons emitted from the electron gun 10 and the acceleration voltage thereof are adjusted, and the “ratio: the condition that R1 / R2 is greater than 1” is set, and the electron beam is scanned two-dimensionally, whereby the sample 0 can be uniformly charged. Such adjustment of the amount of emitted electrons and the acceleration voltage is performed by the charged particle beam control unit 31. Further, the charged particle beam control unit 31 controls the beam blanker 18 to turn on / off the electron beam accompanying the scanning of the electron beam.
As other charging means, contact charging, injection charging, and ion irradiation charging are also possible.

  FIG. 8 schematically shows a state in which the surface of the sample 0 is charged by the electron beam as described above. FIG. 8 shows a so-called “function-separated type photoreceptor” as sample 0 which is a photoconductive sample. A charge generation layer 2 is provided on a conductive layer 1, and a charge transport layer 3 is provided thereon. Formed.

  Electrons irradiated by the electron gun 10 are shot into the surface of the charge transport layer 3, captured by the electron orbits of charge transport layer material molecules on the surface of the charge transport layer 3, and charge transported in a state where the molecules are negatively ionized. It remains on the surface of layer 3. This state is a state in which the sample 0 is charged.

  When the sample LT in such a charged state is irradiated with the light LT, the irradiated light LT passes through the charge transport layer 3 and reaches the charge generation layer 2. Generate negative charge carriers. Of the generated positive and negative charge carriers, the negative carriers move to the conductive layer 1 due to the repulsive force due to the negative charges on the surface of the charge transport layer 3, and the positive carriers are transported through the charge transport layer 3 to the same layer. It counteracts with the negative charge (captured electrons) on the surface of 3.

  In this way, in the portion of the sample 0 irradiated with the light LT, the charged charge is attenuated, and a charge distribution according to the intensity distribution of the light LT is formed. The surface potential distribution based on this charge distribution pattern is a pattern of an electrostatic latent image and is nothing but a measurement object.

  The sample 0 uniformly charged as described above is exposed to a light image to form a pattern of an electrostatic latent image. This exposure is performed by the aforementioned “exposure means (FIG. 7)”. That is, the semiconductor laser 34 is turned on, and the image of the mask 37 is formed on the surface of the sample 0 by the action of the imaging lenses 38, 39 and 40.

  As the semiconductor laser 34, of course, one having “the sample 0 has a light emission wavelength in the wavelength region with sensitivity” is used, and the exposure energy is time integration of the optical power on the surface of the sample 0. By controlling the lighting time by the LD control unit 33, the sample 0 can be exposed with a desired exposure energy.

FIG. 9 shows a simplified “light image irradiator” in “exposure means”.
Reference numeral 34 denotes a semiconductor laser as a light source, reference numeral 35 denotes a collimating lens, reference numeral 36 denotes an aperture, and reference numeral 37 denotes a mask. Reference numeral 380 indicates a simplified “imaging lens” composed of the three lenses 38, 39, and 40 in FIG. 7 as a single lens.

The light beam emitted from the semiconductor laser 34 is converted into a parallel light beam by the collimator lens 35, and the diameter of the light beam is regulated by the aperture 36 so that the mask 37 is irradiated. The light beam that has passed through the mask 37 forms an image of the mask pattern of the mask 37 on the image plane by the action of the imaging lens 380. The “image plane” is a “uniformly charged surface” of the sample 0 placed on the support portion 23.
In this way, the sample 0 is exposed, and an electrostatic latent image pattern corresponding to the mask pattern is formed.

  As shown in FIG. 9, when the object distance of the mask 37 in the imaging lens 380 is L1 and the image distance is L2, the imaging magnification of the imaging lens 380 in the “perpendicular direction to the optical axis”: β = L2 / L1, and a mask pattern image corresponding to this magnification is formed.

The imaging lens 380 is arranged so that the mask 37 and the surface of the photoconductive sample are conjugated. Imaging magnification: Since β and the size of the mask pattern are known in advance, the size of the mask pattern image formed on the surface of the photoconductive sample can be calculated, and the desired electrostatic latent image pattern can be applied to the photoconductive sample. In order to set the exposure optical path in the exposure means “outside the region through which the charged particle beam that performs two-dimensional scanning of the photoconductive sample passes”, the optical axis of the imaging lens 380 is set to be photoconductive. It is tilted with respect to the normal that stands on the uniformly charged surface of the sample.

  Therefore, the mask 37 is also tilted with respect to the optical axis of the imaging lens 380 as shown in FIG. 9 so that the “mask pattern image” by the imaging lens 380 matches the surface of the photoconductive sample. Has been. “Inclination angles with respect to the optical axis of the imaging lens 380: α, θ” of the mask 37 and the photoconductive sample surface are α = θ = 45 degrees in the embodiment being described, and this is the imaging magnification. This is because it is the same magnification (L1 = L2).

For this reason, the mask pattern image formed on the surface of the photoconductive sample is √2 times in a plane parallel to the drawing in the direction orthogonal to the drawing of FIG. To design a mask pattern. In a general case where the imaging magnification is other than equal magnification, if the object distance is L1 and the image distance is L2, the relationship between these distances L1 and L2 and the inclination angles α and θ is as follows:
L1 · tanα = L2 · tanθ
Holds.

  The mask pattern in the mask 37 is a “mask pattern for resolving power inspection”. In the embodiment being described, the mask pattern is also a negative pattern so that a negative latent image can be formed on the photoconductive material, and the portion corresponding to the portion irradiated with light when forming the electrostatic latent image is light transmissive. The other part is light-shielding.

  As described above, in the surface potential distribution measuring apparatus according to the embodiment shown in FIG. 7, the optical axis of the image formation in the exposure means is inclined with respect to the normal line standing on the surface of the sample 0. In order to make the image of the mask 37 formed on the surface parallel to the sample surface, it is necessary to devise such as tilting the mask 37 with respect to the optical axis.

  As shown in FIG. 5, when the charged particle beam irradiation direction is set to be inclined with respect to the sample surface, the collimator lens 35, the mask 37A, the connection from the semiconductor laser 34 as in the embodiment shown in FIG. The optical path to the surface of the sample 0 via the image lens 38A is orthogonal to the surface of the sample 0, and the image of the mask 37A can be imaged on the surface of the sample 0 by the imaging lens 38A. 37A can be placed parallel to the sample surface.

  FIG. 11 shows another embodiment of a surface potential distribution measuring apparatus for measuring an electrostatic latent image formed on a photoconductive photoreceptor. In order to avoid confusion, the same reference numerals as those in FIGS. 1 and 7 are assigned to those which are not likely to be confused.

  The electron gun 10, aperture 13, condenser lens 15, aperture 17, beam blanker 18, scanning lens 19, and objective lens 21 constituting the charged particle beam irradiation unit 11A have the same configuration as that shown in FIGS. The detector 25 and the signal processing unit (not shown) are the same as those described above with reference to FIG. Reference numeral 30A denotes a casing.

A sample 01, which is a photoconductive photoconductor, is formed in a drum shape, which is a general form of a photoconductive photoconductor, and is rotated at a constant speed in the direction of the arrow (counterclockwise) by a driving unit (not shown). After the sample 01 is set in the casing 30A, the inside of the casing 31A is highly decompressed by suction means (not shown). In this case, naturally, the conductive substrate itself that supports the photoconductive layer in the sample 01 constitutes the sample support means.

  The charging unit denoted by reference numeral 42 is, for example, a contact-type charging unit such as a charging brush or a charging roller, and uniformly charges the sample 01 in a casing under reduced pressure. At this time, the sample 01 is rotated at a constant speed in the direction of the arrow (counterclockwise). Of course, as in the example described with reference to FIG. 7, the sample 01 can also be charged by charging using an electron beam.

  The “exposure section” denoted by reference numeral 41 performs exposure by irradiating the uniformly charged sample 01 with a light image. As the exposure unit 41, for example, an “optical scanning device” that is widely known in connection with an optical printer or the like can be used, and “optical image irradiation” can be performed by optical writing. Thus, when “irradiation of optical image” is performed by optical writing, the form of the pattern of the electrostatic latent image formed by writing can be arbitrarily changed, and a desired pattern of the electrostatic latent image can be easily formed. .

  When an optical scanning device is used as the exposure unit 41 and the optical scanning device is large and difficult to install in the casing 31A, the optical scanning device is provided outside the casing 31A, and the casing 31A is provided with the optical scanning device. A transparent window part may be provided, and the photoconductive sample 01 may be irradiated with a light image from the outside through this window part.

  Scanning of the electron beam by the charged particle beam irradiation unit 11A may be performed by deflecting the electron beam two-dimensionally, as in the embodiment of FIGS. 1 and 7, but the sample 01 is constant in the direction of the arrow. Since scanning is performed while rotating, the electron beam can be deflected one-dimensionally in a direction orthogonal to the drawing, and two-dimensional scanning can be realized by combining this deflection and the rotation of the sample 01.

The surface potential distribution measuring apparatus described in the embodiment with reference to FIGS. 7 to 11 described above “measures the surface potential distribution by the electrostatic latent image formed on the photoconductive photosensitive member as a measurement object. And a charging means 11A for uniformly charging a photoconductive sample as a measurement sample and an exposure means for performing exposure by irradiating a light image onto the uniformly charged photoconductive sample .

7, in the embodiment shown in FIG. 10, the exposure means is a "one which projection exposure mask pattern 37,37A", in the embodiment of FIG. 7, the optical path for the exposure of the exposure unit, photoconductive It is set outside the region through which the charged particle beam that performs two-dimensional scanning of the sample 0 passes . Further, in the surface potential distribution measuring apparatus whose embodiment is shown in FIG. 11, the exposure means 41 is “to write a latent image pattern by optical scanning” .

In each of these embodiments, a semiconductor laser 34 can be used as the exposure light source of the exposure means, and the exposure time of the exposure means can be controlled . Further, in the surface potential distribution measuring apparatus whose embodiments are shown in FIG. 7 and FIG. 10, the charged particle beam scanning unit 11A “shall uniformly charge the photoconductive sample 01 with an electron beam scanned two-dimensionally”. Thus, it also serves as a charging means for the photoconductive sample .

It is a figure for demonstrating one Embodiment of a surface potential distribution measuring apparatus. It is a figure for demonstrating a measurement principle. It is a figure for demonstrating the measurement of surface potential distribution. It is a figure for demonstrating application of a uniform bias potential with respect to the surface potential distribution of the sample surface. It is a figure for demonstrating embodiment which makes a charged particle beam inject into a scanning area from the diagonal direction with respect to the sample which has surface potential distribution. It is a flowchart which shows the procedure in the case of measuring a latent image profile. It is a figure for demonstrating one Embodiment of the surface potential distribution measuring apparatus which measures the electrostatic latent image formed in the photoconductive sample as a measuring object. It is a figure for demonstrating model formation of the electrostatic latent image to a photoconductive sample. In the embodiment of FIG. 7, it is a figure for demonstrating irradiation of the optical image to the photoconductive sample surface. It is a figure for demonstrating another example of the optical image irradiation to the photoconductive sample surface. It is a figure for demonstrating another form of implementation of the surface potential distribution measuring apparatus which measures the electrostatic latent image formed in the photoconductive sample as a measuring object.

Explanation of symbols

0 Sample having surface potential distribution 10 Electron gun 15 Condenser lens 19 Deflection lens 21 Objective lens 25 Detector

Claims (20)

In a method of measuring a surface potential distribution of a photoconductive sample as a measurement sample by two-dimensionally scanning a charged particle beam with respect to a sample having a surface potential distribution and using a detection signal obtained by the scanning,
A sample supporting means having a conductive layer supports a photoconductive sample as a measurement sample,
After the photoconductive sample supported by the supporting means is irradiated with a charged particle beam scanned two-dimensionally by a charged particle optical system, the photoconductive sample is uniformly charged to a desired potential, A uniformly charged photoconductive sample is irradiated with a light image and exposed to form an electrostatic latent image that is a surface potential distribution as a measurement target.
Two-dimensional scanning with a charged particle beam is performed on the photoconductive sample on which the electrostatic latent image is formed in a state where the photoconductive sample is supported by the support means,
During this two-dimensional scanning, by applying a bias potential to the conductive layer of the sample support means , a uniform bias potential is superimposed on the surface potential distribution formed on the photoconductive sample,
Among charged particles incident on the sample surface by two-dimensional scanning, the normal velocity component of the incident velocity vector on the sample surface without reaching the photoconductive sample due to the surface potential of the photoconductive sample. A method for measuring a surface potential distribution, wherein a detection signal is obtained by detecting only charged particles having a reversed inversion. In the measuring method of surface potential distribution according to claim 1,
The bias potential applied to the surface potential distribution on the sample surface is changed, and measurement is performed each time the bias potential is changed, and the profile of the surface potential distribution is obtained arithmetically based on a plurality of measurement results obtained. A method for measuring surface potential distribution. In the measuring method of the surface potential distribution according to claim 1 or 2,
The charged voltage of the charged particle beam that is scanned two-dimensionally with respect to the sample is changed, the measurement is performed each time the acceleration voltage is changed, and the surface potential distribution of the surface potential distribution is measured based on a plurality of measurement results obtained. A method for measuring a surface potential distribution, wherein the profile is obtained in an arithmetic manner. The method for measuring a surface potential distribution according to claim 3 ,
Measurement is performed each time a bias potential is applied to the surface potential distribution on the sample surface and at least one of the acceleration voltage and the bias potential is changed, and the profile of the surface potential distribution is determined based on the obtained measurement results. A method for measuring a surface potential distribution, wherein the surface potential distribution is obtained by calculation. In the measuring method of the surface potential distribution according to any one of claims 1 to 4,
A method for measuring a surface potential distribution, wherein an electron beam is used as a charged particle beam for two-dimensionally scanning a photoconductive sample having a surface potential distribution. In the measuring method of the surface potential distribution according to any one of claims 1 to 4,
A method for measuring a surface potential distribution, comprising using an ion beam as a charged particle beam for two-dimensionally scanning a sample having a surface potential distribution. In the measuring method of surface potential given in any 1 of Claims 1-6,
A method for measuring a surface potential distribution, characterized in that a charged particle beam is incident on a scanning region obliquely with respect to a sample having a surface potential distribution. An apparatus for carrying out the surface potential distribution measuring method according to any one of claims 1 to 7,
A sample support means having a conductive layer and supporting a photoconductive sample as a measurement sample as a surface to be scanned by a charged particle beam, the surface forming the surface potential distribution;
Charging means for uniformly charging the photoconductive sample supported by the sample support means;
Exposure means for performing exposure by light image irradiation on the photoconductive sample uniformly charged by the charging means, and forming an electrostatic latent image as a surface potential distribution on the photoconductive sample;
A bias potential is applied to the conductive layer of the specimen support means, and voltage application means you superimposing a uniform bias potential to the surface potential distribution formed on the photoconductive sample,
A charged particle beam scanning means for two-dimensionally scanning a sample surface of the photoconductive sample formed on the electrostatic support image by the exposure means and supported by the sample support means;
Of the charged particle beam, only the charged particles that do not reach the photoconductive sample due to the surface potential of the photoconductive sample and whose normal component of the incident velocity vector on the sample surface is reversed are captured. A surface potential distribution measuring apparatus, comprising: a measuring means which captures the intensity of the light by detecting the intensity of the light in correspondence with a position on the sample surface and measures the surface potential distribution state. The surface potential distribution measuring apparatus according to claim 8,
Bias potential varying means for changing the bias potential applied by the bias potential applying means;
An apparatus for measuring a surface potential distribution, comprising a calculation means for calculating a profile of a surface potential distribution based on a measurement result when two or more different bias potentials are applied. The surface potential distribution measuring device according to claim 8 or 9,
Accelerating voltage variable means for changing the accelerating voltage for the charged particles of the charged particle beam scanned two-dimensionally with respect to the photoconductive sample;
A surface potential distribution measuring apparatus comprising: a calculation means for calculating a surface potential distribution profile based on measurement results obtained by two or more different acceleration voltages. In the surface potential distribution measuring apparatus according to claim 10,
Bias potential applying means for applying a uniform bias potential to the surface potential distribution on the sample surface, and bias potential variable means for changing the bias potential applied by the bias potential applying means,
An apparatus for measuring a surface potential distribution, comprising: a calculation means for calculating a profile of a surface potential distribution based on a measurement result in a state where at least one of a bias potential and an acceleration voltage is different. In the surface potential distribution measuring apparatus according to any one of claims 8 to 11,
An apparatus for measuring surface potential distribution, comprising an electron gun as a generation source of a charged particle beam that two-dimensionally scans a photoconductive sample having a surface potential distribution. In the surface potential distribution measuring apparatus according to any one of claims 8 to 11,
A surface potential distribution measuring apparatus comprising a liquid metal ion gun as a generation source of a charged particle beam that two-dimensionally scans a photoconductive sample having a surface potential distribution. In the surface potential distribution measuring apparatus according to any one of claims 8 to 13,
The charged particle beam scanning means is set so that the charged particle beam is incident on the scanning region from an oblique direction,
A surface potential distribution measuring apparatus, wherein the capturing means in the measuring means is disposed on the opposite side to the incident direction of the charged particle beam through the scanning region. The surface potential distribution measuring apparatus according to any one of claims 8 to 14,
An apparatus for measuring a surface potential distribution, wherein the exposure means projects and exposes a mask pattern. The surface potential distribution measuring apparatus according to claim 15,
An apparatus for measuring a surface potential distribution, wherein an exposure optical path is set outside an area through which a charged particle beam for performing two-dimensional scanning of a photoconductive sample passes. The surface potential distribution measuring apparatus according to any one of claims 8 to 14,
A surface potential distribution measuring device, wherein the exposure means writes a latent image pattern by optical scanning. The surface potential distribution measuring apparatus according to any one of claims 8 to 17,
A surface potential distribution measuring apparatus, wherein the exposure means has a semiconductor laser as a light source for exposure. In the surface potential distribution measuring apparatus according to any one of claims 8 to 18,
A surface potential distribution measuring apparatus characterized in that the exposure time of the exposure means can be controlled. In the surface potential distribution measuring apparatus according to any one of claims 8 to 19,
A surface potential distribution measuring apparatus, wherein the charged particle beam scanning unit uniformly charges the photoconductive sample with an electron beam scanned two-dimensionally, and also serves as a charging unit for the photoconductive sample.

Images