JP2003295696A - Method and apparatus for forming electrostatic latent image and measurement method and measurement instrument for electrostatic latent image - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method and an apparatus for forming an electrostatic latent image and a measurement instrument which has a means forming the electrostatic latent image in an instrument performing a measurement by irradiating with a charged particle beam, enables the measurement in a short time after forming the latent image and enables a non-destructive measurement. <P>SOLUTION: The surface of a sample is scanned with the charged particle beam and the electrostatic latent image on the surface of the sample is measured on the basis of a detection signal obtained by the scanning. By charging the sample 30 and exposing the charged sample via an optical system in the instrument scanning the charged particle beam, a charge distribution is generated on the sample 30. The measurement of electrostatic latent image on the surface of the sample while moving the sample having a charge distribution is preferably performed. A charging means is permitted to be a means 10 irradiating with an electron beam and a means 18 detecting secondary electrons from the sample is disposed. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrostatic latent image forming method and apparatus, an electrostatic latent image measuring method and measuring apparatus, and is applicable to measurement of surface potential distribution and surface charge distribution of a sample. It is a thing.

[0002]

2. Description of the Related Art In order to obtain an output image in an electrophotographic image forming apparatus such as a copying machine or a laser printer, the following process is usually performed. An example of an electrophotographic apparatus that executes each process to obtain an output image is shown in FIG. Hereinafter, description will be given with reference to FIG. 1. Charging: The electrophotographic photoreceptor is uniformly charged. 2. Exposure: The photoconductor is irradiated with light to partially release electric charges corresponding to an image to form an electrostatic latent image. 3. Development: charged fine particles (hereinafter referred to as "toner")
Then, a visible image is formed on the electrostatic latent image. 4. Transfer: Transfer the developed and visualized toner image to paper or other transfer material. 5. Fixing: Fusing the toner forming the transferred image,
Fix the image on the transfer material. 6. Cleaning: Clean the residual toner on the photoconductor. 7. Static elimination: Eliminates the residual charge on the photoconductor.

The process factor and process quality in each of the above steps have a great influence on the final output image quality. Therefore, in order to obtain higher quality images, it is necessary to improve the process quality of each process, and it is important to evaluate the quality of the electrostatic latent image after exposure in order to obtain high quality images. Extremely important. In particular, the design of the writing optical system used in the exposure process is optimized as the beam spot diameter on the surface of the photoconductor. However, even though it should be designed so that an optimum electrostatic latent image on the photoconductor that directly affects the behavior of the toner particles should be formed, such a design is performed. Not necessarily. In addition, no clear mechanism has been established when exposure energy is converted into an electrostatic latent image. Therefore, if the information obtained from the electrostatic latent image can be incorporated into the optical system design, higher image quality can be obtained, and it can be expected to design the image forming apparatus at low cost.

[0004]

However, it is extremely difficult to measure the electrostatic latent image, and it is the current situation that the electrostatic latent image cannot be measured at all in actual use. A well-known method for measuring an electrostatic latent image is to bring a sensor head such as a cantilever close to a sample having a potential distribution, and at that time, an electrostatic attractive force generated as an interaction between the electrostatic latent image and the cantilever. It is a method of measuring the induced current and the induced current, and converting this to a potential distribution. The electrostatic attraction type is SPM (scan
Ning probe microscope), and the induced current type is the patent No. 300.
No. 9179 and Japanese Patent Application No. 11-184188.

However, in order to use these methods, it is necessary to bring the sensor head close to the sample. For example, in order to obtain a spatial resolution of 10 μm, the distance between the sensor and the sample needs to be 10 μm or less. Under these conditions: -Absolute distance measurement is required.・ Measurement takes time, and the state of the latent image changes during that time.・ Discharge and adsorption occur.・ The sensor itself disturbs the electric field. However, even if it can be used for other purposes, the electrostatic latent image cannot be measured in actual use.

Therefore, as a practical measuring method, in order to visualize an electrostatic latent image, an electric charge is applied to a toner, which is a colored fine powder, and a Coulomb force acting between the toner having the electric charge and the electrostatic latent image. Generally, a method is used in which the toner image is developed and then the toner image is transferred to paper or tape. However, this does not mean that the electrostatic latent image itself is measured because the development and transfer processes have been performed.

On the other hand, a method of measuring a potential pattern using an electron beam is known. This has already been put to practical use for failure analysis of LSI. This measurement method is for the case where the sample is a conductor, and the measurement object is completely different from the dielectric material such as the photoconductor targeted by the present invention, and cannot be applied to the measurement of the dielectric material such as the photoconductor. . If the object to be measured is a conductor, the potential distribution can be maintained for a long time by passing a constant current through it, and the potential amount is 0 to at most.
It is a narrow range of 5V, and the phenomenon of charge-up does not occur. The irradiation of the electron beam does not change the potential state.

As a method of observing an electrostatic latent image with an electron beam, there is a method described in Japanese Patent Application No. 03-49143, and as a sample, an LSI chip or a sample capable of storing and holding an electrostatic latent image is used. Limited. That is, ordinary photoconductors that produce dark decay cannot be measured. Since ordinary dielectrics can hold charges semipermanently, even if the measurement is performed over time after forming the charge distribution,
It does not affect the measurement results. However, in the case of the photoconductor, since the resistance value is not infinite, the charge cannot be retained for a long time, dark decay occurs, and the surface potential decreases with time. The time that the photoreceptor can hold the charge is
Even in a dark room, it is at most tens of seconds. Therefore,
Even if an attempt is made to observe it in an electron microscope (SEM) after exposure, the electrostatic latent image disappears in the preparation stage.

By the way, the photosensitive member sample used in the electrophotographic process is generally in the shape of a cylinder, and the electrostatic latent image distribution generated on the cylindrical photosensitive member can be measured nondestructively with high resolution. desired. Even if the charge distribution forming means is the same, the electrostatic latent image changes due to the deterioration of the photoconductor with time. Therefore, it is desired to evaluate the variation of the electrostatic latent image with time.

The present invention has been made to solve the above-mentioned problems of the prior art, and has means for irradiating a charged particle beam to form an electrostatic latent image in an apparatus for measurement, An object of the present invention is to provide an electrostatic latent image forming method and apparatus, an electrostatic latent image measuring method and a measuring apparatus capable of performing measurement within a short time after forming a latent image. Another object of the present invention is to provide a method and a device for measuring an electrostatic latent image that can be measured nondestructively.

[0011]

The invention according to claim 1 is
The present invention relates to an electrostatic latent image forming method, characterized in that an electrostatic latent image is formed by scanning a sample surface with a charged particle beam in a device for scanning a charged particle beam to generate a charge distribution on the sample. To do. The invention according to claim 2 relates to an electrostatic latent image forming apparatus, wherein an apparatus for scanning a charged particle beam,
It is characterized in that a device is provided which scans the sample surface with a charged particle beam to generate a charge distribution on the sample and forms an electrostatic latent image.

According to a third aspect of the present invention, there is provided a method of scanning a sample surface with a charged particle beam and measuring the sample surface by a detection signal obtained by this scanning. It is characterized in that the surface is scanned with a charged particle beam to generate a charge distribution on the sample. A fourth aspect of the present invention is a method of scanning a sample surface with a charged particle beam, and measuring the sample surface by a detection signal obtained by this scanning. The sample is charged and exposed by an exposure optical system. It is characterized in that the charge distribution is generated.

According to a fifth aspect of the present invention, there is provided an apparatus for scanning a sample surface with a charged particle beam, and measuring the sample surface by a detection signal obtained by this scanning. And an optical system means for generating a charge distribution. Claim 6
According to a fifth aspect of the present invention, in the fifth aspect, the means for charging the sample comprises means for irradiating the sample with an electron beam. The invention according to claim 7 is
In the invention according to claim 6, the means for charging the sample is a means for charging the sample by irradiating the sample with an electron beam at an acceleration voltage higher than the acceleration voltage at which the secondary electron emission ratio of the sample is 1. Is characterized by.

According to an eighth aspect of the present invention, in the invention according to the fifth, sixth or seventh aspect, a known reference potential is arranged in the scanning region of the charged particle beam, and the secondary electron signal intensity of the reference potential is set. It is characterized by having a means for calculating the amount of potential by comparing the signal intensities of the measurement samples.

According to a ninth aspect of the present invention, in a method of scanning a sample surface with a charged particle beam and measuring an electrostatic latent image on the sample surface by a detection signal obtained by this scanning, the sample surface is moved while the sample is moved. It is characterized by measuring an electrostatic latent image. According to a tenth aspect of the present invention, in the method of scanning a sample surface with a charged particle beam and measuring an electrostatic latent image of the sample surface by a detection signal obtained by this scanning, the sample surface having a charge distribution is moved. The electrostatic latent image of is measured.

According to an eleventh aspect of the present invention, the sample surface is scanned with a charged particle beam, and a sample having a charge distribution is moved in an apparatus for measuring an electrostatic latent image on the sample surface by a detection signal obtained by this scanning. It is characterized by having means for measuring the electrostatic latent image on the sample surface while performing the above.

According to a twelfth aspect of the present invention, an apparatus for scanning a sample surface with a charged particle beam and measuring an electrostatic latent image on the sample surface by a detection signal obtained by this scanning, forms an electrostatic latent image on the sample. It is characterized in that it has an electrostatic latent image forming means for forming and a measuring means for moving and measuring a sample having a charge distribution to a charged particle beam irradiation position. According to a thirteenth aspect of the present invention, in the second aspect of the invention, the electrostatic latent image forming means includes an exposing means. According to a fourteenth aspect of the invention, in the thirteenth aspect of the invention, the sample and the exposure means are arranged in the same chamber.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of an electrostatic latent image measuring method and measuring apparatus according to the present invention will be described below with reference to the drawings. FIG. 1 shows an embodiment of an electrostatic latent image measuring device according to the present invention. This electrostatic latent image measuring device
It comprises a charged particle irradiation unit 10 for irradiating a charged particle beam, an exposure unit 20, a sample setting unit 16, and a secondary electron detection unit 18. These are all arranged in the same chamber, and the inside of the chamber is evacuated. Here, the charged particles refer to particles that are affected by an electric field or a magnetic field, such as an electron beam or an ion beam.

Hereinafter, the charged particle irradiation unit will be described as an embodiment including an electron beam irradiation unit. The electron beam irradiation unit 10 includes an electron gun 11 for generating an electron beam, a condenser lens 12 for focusing the electron beam emitted from the electron gun 11, and a beam blanker 13 for turning on / off the electron beam. , Beam Blanker 13
Scan lens 1 for scanning the electron beam that has passed through
4 and an objective lens 15 for refocusing the electron beam that has passed through the scanning lens 14. The scanning lens 14 is a so-called deflection coil. A driving power source (not shown) is connected to each of the other lenses and the like. In the case of an ion beam, a liquid metal ion gun or the like is used instead of the electron gun. A scintillator, a photomultiplier tube, or the like is used for the secondary electron detector 18.

The exposure section 20 includes a light source 21 having a wavelength sensitive to the photosensitive member, which will be described later, a collimate lens 22, an aperture 23, an image forming lens 25, and the like. On the placed sample 30,
It is possible to generate a desired beam diameter and beam profile. An LD (laser diode) or the like can be used as the light source 21. Also, L
The light source 21 is controlled by the D control means or the like so that appropriate exposure time and exposure energy can be emitted. In order to form a line pattern composed of an electrostatic latent image on the sample 30, the optical system of the exposure unit 20 may be provided with a scanning mechanism using a galvano mirror or a polygon mirror.

As shown in FIG. 4, the structure of the photosensitive member which is the actual condition of the sample 30 is mainly composed of a charge generating layer (CGL) and a charge transporting layer (CTL) formed on a conductive support.
When exposed while the surface is charged, the light is absorbed by the charge generation material (CGM) of the charge generation layer CGL, and positive and negative charge carriers are generated. This carrier is generated by the electric field, and on the one hand, the charge transport layer CT
L, the other is injected into the conductive support. Charge transport layer C
The carriers injected into the TL pass through the charge transport layer CTL,
It moves to the surface of the charge transport layer CTL by the electric field, and combines with the charge on the surface of the photoconductor to disappear. As a result, a charge distribution is formed on the surface of the photoconductor. That is, an electrostatic latent image is formed.

Next, a method of forming an electrostatic latent image and a method of measuring an electrostatic latent image will be described together with the operation of the embodiment shown in FIG. First, the charged particle beam irradiation unit 10 is attached to the photoreceptor sample 30.
To irradiate an electron beam. The relationship between the acceleration voltage and the secondary electron emission ratio δ at this time is shown in FIG. Acceleration voltage E
1 is the acceleration voltage E0 at which the secondary electron emission ratio δ becomes 1.
By setting the accelerating voltage higher than that, the amount of incident electrons exceeds the amount of emitted electrons, so that electrons are accumulated in the sample 30 and charge-up occurs. As a result, the sample 30 can generate negative uniform charging. A desired charging potential can be formed by appropriately setting the acceleration voltage and the irradiation time. When the charging potential is formed, the electron beam is turned off once.

Next, the photoreceptor sample 30 is exposed through the optical system of the exposure section 20. The optical system is adjusted to form a desired beam diameter and beam profile. By performing the exposure, an electrostatic latent image can be formed on the photoconductor sample 30. After forming the electrostatic latent image, the mode is changed to the observation mode. In the observation mode, the photoconductor sample 30 is scanned with an electron beam, and the emitted secondary electrons are detected by the secondary electron detector 18 including a scintillator, a photomultiplier tube, etc., and converted into an electric signal. Observe the potential contrast image.

In order to convert the potential contrast image into the potential, a conversion table representing the correlation between the potential and the signal strength may be prepared in advance, and the potential may be calculated from the signal strength based on the conversion table. Alternatively, a known reference potential may be arranged in the electron beam scan region and the secondary electron signal intensity may be compared with the reference potential to calculate the potential distribution. As a method of arranging the reference potential, refer to FIG.
As shown in FIG. 3, there is a method of disposing a plurality of conductive substrates 34 on the insulator 33 and setting a reference potential on each of the conductive substrates 34. Specifically, the voltage of the reference voltage source is divided by a resistor, and a reference potential is applied to each conductive substrate 34. Generally, the lower potential portion becomes brighter than the higher potential portion because the amount of secondary electrons emitted is larger. In FIG. 5, a portion having a relatively low potential is displayed in white and a portion having a relatively high potential is displayed in black. In FIG. 5, reference numeral 30 is a sample, 31 is an electrostatic latent image, and 32 is an electron beam scan area. Sample 30
While scanning the surface of the object with an electron beam
To detect secondary electrons. The manner in which the detected signal strength changes at that time is shown in the lower portion of FIG.

The signal strength on the detector 18 may be corrected if it changes depending on the set conditions. Further, it may be calibrated in advance. After the measurement is completed, the light source 17 shown in FIG. 1, such as an LED, is used to irradiate the entire surface of the sample 30 with light, so that the residual charges of the sample 30 can be removed.

FIG. 6 shows an example of the control unit of the above embodiment. 6, the LD control unit 3 that controls the light source 21
6, a charged particle control unit 37 that controls the scanning lens 14, an LED control unit 38 that controls the light source 17 for removing residual charge,
A sample table controller 39 for controlling the movement of the sample table 16 is provided, and these LD controller 36, charged particle controller 37 and L are provided.
The ED control unit 38 and the sample stage control unit 39 are controlled by the host computer 35. The output of the detector 18 is detected by the secondary electron detector 41, the detection signal is processed by the signal processing unit 42, and the secondary electron measurement result is output from the measurement result output unit 43. There is.

The secondary electron emission ratio δ is expressed as the secondary electron emission ratio δ = emitted electron / incident electron, but more strictly speaking, since it is necessary to consider the transmitted electron and the reflected electron, the emitted electron = Transmission electron + Reflection electron + Secondary electron

When positive charging is desired, irradiation may be performed with an accelerating voltage such that the secondary electron emission ratio is 1 or more as shown in FIG. In order to avoid the influence of charge-up, it is common to observe a sample by a normal SEM under the condition of δ = 1, and it is known that no other accelerating voltage is used. One of the features of this embodiment is that the charging potential is intentionally charged to form a charging potential.

In the above method, after forming the charging potential,
Although it has been described that the electron beam is turned off once, the method may be such that the electron beam is converted to an accelerating voltage such that δ = 1 without turning off, and the observation condition is set so that charge-up does not occur, and exposure is performed in that state. As the charging method, another means such as contact charging may be used.

Next, another embodiment of the present invention will be described. In this embodiment, the electrostatic latent image distribution can be measured within a short time after the electrostatic latent image is formed on the photoconductor, and the photoconductor sample is non-destructive and under the condition close to the actual machine. It is possible to measure. The same components as those in the above-described embodiment are designated by common reference numerals.

In FIG. 7, in one housing, an electron beam irradiation unit 10, a sample 30 composed of a cylindrical photosensitive member,
An electrostatic latent image forming unit and a secondary electron detector 18 for forming a charge distribution on the surface of the sample 30 are arranged. The electron beam irradiation unit 10 turns on the electron gun 11 for generating the electron beam, the condenser lens 12 for focusing the electron beam emitted from the electron gun 11, and the electron beam.
Beam blanker 13 for turning on / off, a scanning lens (deflection coil) 14 for scanning the electron beam that has passed through the beam blanker 13, and an objective lens 15 for refocusing the electron beam that has passed through the scanning lens 14.
And have. A driving power source (not shown) is connected to each lens and the like. As the detector 18, a scintillator, a photomultiplier tube, or the like is used.

The electrostatic latent image forming section is provided around the cylindrical photosensitive member sample 30 and is provided with a charging section 45 and an exposing section 4.
6. It has a static elimination unit 47. The charging unit 45 irradiates the surface of the sample 30 with electric charges to uniformly charge the surface of the sample 30, and the exposure unit 46 exposes the surface of the sample 30 uniformly charged with a predetermined pattern to form a charge distribution. The charge removing unit 47 is for eliminating charges. A drive unit is attached to the photoconductor 30 on the center axis of the photoconductor, and the photoconductor 30 is rotationally driven by the drive unit. As the driving means, a stepping motor, DC
A servo motor or the like can be used. As the charging unit 45, there are methods such as charging by electron beam irradiation, contact charging, and charge injection charging. The charge removing unit 47 is provided on the photoconductor 30.
It can be configured with an LED or the like that illuminates the entire surface of the.

The operation or measuring method of the embodiment shown in FIG. 7 is as follows. 1. The photoconductor 30 is rotated. 2. In the charging section 45, the photoconductor 30 is uniformly charged so that the surface of the photoconductor 30 has a desired potential. 3. In the exposure section 46, the surface of the photoconductor 30 is irradiated with light to partially release the electric charge and form an electrostatic latent image. 4. In the measurement unit 18, the acceleration voltage of the electron beam irradiation unit 10 is set so that the secondary electron emission ratio becomes 1. The surface of the photoreceptor sample 30 is scanned with an electron beam, the emitted secondary electrons are detected by a detector 18 such as a scintillator, converted into an electric signal, and a potential contrast image is observed. 5. In the static eliminator 47, the residual charge on the photoconductor 30 is erased by irradiating the surface of the photoconductor 30 with light from an LED or the like. By using such a method, it is possible to dynamically measure the electrostatic latent image on the photoconductor 30.

Further, the rotation driving mechanism may be means for driving the photoconductor 30 once. By mounting the drive means capable of rotating once, the electrostatic latent image can be dynamically measured over the entire circumference of the photoconductor 30. When evaluating the change with time of the photoconductor 30,
It is advisable to rotate the photoconductor 30 continuously and repeat the above operations 1 to 5 to measure. According to this embodiment, since the photoconductor 30 as a sample is the same as the cylindrical photoconductor used in the electrophotographic apparatus, the photoconductor 30 used in the actual machine or the photoconductor used in the actual machine is used as it is.
That is, it can be measured as a sample without breaking. Therefore, it is possible to easily measure a photoconductor that has been used for many years.

8 and 9 show an example of the exposure section 46. In the examples shown in FIGS. 8 and 9, the light emitting element array 51 is used as the exposure light source. LED as the light emitting element
And EL can be used. Light emitting element array 51
The light emitted from is irradiated onto the photosensitive member 30 by the same-magnification imaging element 52 including a rod lens array in which rod lenses 53 are arranged, and is exposed. A scanning optical system is used as an exposure apparatus for a general photoconductor, but by using an exposure unit 46 including a light emitting element array 51 and a unity-magnification imaging element 52 as in the example shown in FIGS. As compared with a general scanning optical system, the space in the chamber 50 can be saved. Therefore, it becomes easy to dispose the cylindrical photoconductor 30 and the exposure device in the same chamber 50. In FIG. 9, reference numeral 54 denotes an opaque member that fills the periphery of the rod lens 53, and 55 denotes an opaque member 54 and a side plate fixed to the opaque member 54 and arranged outside the rod lens 53.

FIG. 10 shows another example of the exposure apparatus. This exposure apparatus is constructed similarly to the general scanning optical system described above. In FIG. 10, a light source 61 such as an LD (laser diode), a collimate lens 62, a cylinder lens 63, an aperture, and a polygon mirror 6 as a deflector having a wavelength having a sensitivity with respect to the cylindrical photoconductor 30.
5, scanning lenses 66, 67 and the like. It is possible to generate an electrostatic latent image by irradiating the surface of the photoconductor 30 as a sample with a light beam having a desired beam diameter and beam profile. Reference numerals 64 and 68 denote mirrors. Light source 6
1 is controlled by an LD control unit (not shown) so that the photoconductor 30 can be irradiated with an appropriate exposure time and exposure energy. In this way, by attaching the scanning mechanism using the polygon mirror 65, the photoconductor 3
An arbitrary latent image pattern including a line pattern can be formed in the generatrix direction of 0.

Yet another embodiment of the present invention is shown in FIG. Unlike the electron beam, the exposure optical system basically behaves the same in vacuum and in the atmosphere, so that the exposure optical system can be arranged in the atmosphere. In the embodiment of FIG. 11, the exposure unit 46 including the exposure optical system is provided in the chamber 5.
It was placed in the atmosphere outside 0. Chamber 50
The inside is a vacuum, and an entrance window 51 having a high transmitted wavefront accuracy is placed at the boundary between the vacuum and the atmosphere. The entrance window 51 is fixed by interposing an O-ring or the like in order to maintain the degree of vacuum in the chamber 50. Since the configuration other than the exposure unit 46 is the same as that of the embodiment shown in FIG. 9, description thereof will be omitted.

Yet another embodiment of the present invention is shown in FIG. This embodiment is different from the embodiments shown in FIGS. 9 and 11 in that the photoreceptor sample is not a cylindrical one but a planar photoreceptor sample 30 and a sample on which the photoreceptor sample 30 is mounted. The installation unit 16 moves horizontally to move the photoconductor sample 3
That is, it is movable between the position where the electron beam is irradiated to 0 and the exposure position by the electrostatic latent image forming unit 20 for forming the charge distribution on the photosensitive sample 30.

As a method of forming an electrostatic latent image on the surface of the photoreceptor by the electrostatic latent image forming section 20, a method of directly drawing electrons or ions to form a latent image pattern, or a method of uniformly forming the surface of the photoreceptor once. There is a method in which the latent image pattern is formed by partially discharging the electric charge by previously charging. As a measuring method, first, the sample 30 is moved to a position facing the electrostatic latent image forming unit 20, and an electrostatic latent image is formed by the above method. After that, the sample 30 having the charge distribution is moved to the measuring unit that irradiates the charged particle beam, the charged particle beam is irradiated from the charged particle irradiation unit 10 to the sample 30, and the secondary electrons are detected by the detector 18. Other configurations, operations, and measuring methods are the same as those in the above-described embodiment, and therefore description thereof will be omitted.

[0040]

According to the first and second aspects of the present invention, an electrostatic latent image can be formed by forming a charge distribution on a sample in an apparatus for scanning a charged particle beam. Becomes

According to the third aspect of the present invention, the surface charge distribution of the sample, which has been extremely difficult in the past, is provided by providing the means for forming the charge distribution on the sample in the apparatus for scanning the charged particle beam. Can be measured.

According to the fourth and fifth aspects of the present invention, by providing the charging means and the exposing means necessary for forming the electrostatic latent image in the same device as the measuring means, real-time measurement becomes possible, and the time can be measured. At the same time, it becomes possible to measure the electrostatic latent image of the photoconductor in which the amount of surface charge is attenuated with high resolution on the order of microns.

According to the invention of claim 6, in the invention of claim 5, there is no need to use a separate means for charging because the electron beam used for measurement is irradiated to charge. According to the invention of claim 7, in the invention of claim 6, the sample can be negatively charged.
According to the invention described in claim 8, in the inventions described in claims 5, 6 and 7, it becomes possible to quantitatively measure the surface potential distribution of the sample.

According to the invention described in claims 9, 10 and 11, by providing means for forming a charge distribution on the sample in the apparatus for scanning the charged particle beam, the prior art is
It is possible to measure the surface charge distribution of the sample with high accuracy, which was extremely difficult. Further, by measuring the electrostatic latent image on the sample surface while moving the sample, it is possible to measure in a wider area than the area irradiated with the charged particle beam.

According to the twelfth aspect of the present invention, the surface charge of the sample, which has been extremely difficult in the prior art, is provided by providing the means for forming the charge distribution on the sample in the apparatus for scanning the charged particle beam. It is possible to measure the distribution with high accuracy. In addition, since the electrostatic latent image forming position and the measurement position can be arranged apart from each other, there is an advantage that the degree of freedom of layout is increased. According to the invention of claim 13,
An electrostatic latent image can be formed by an exposure unit that is conventionally used.

According to the fourteenth aspect of the invention, by disposing the charging means and the exposing means necessary for forming the electrostatic latent image in the same device as the measuring means, real-time measurement becomes possible, and with time. It is possible to measure the electrostatic latent image of the photoconductor in which the amount of surface charge is attenuated with a high resolution of micron order. Further, since the photoconductor sample and the exposure optical system are arranged in the same chamber, it is possible to measure the electrostatic latent image in a state close to an actual machine. And,
The device configuration becomes easy.

[Brief description of drawings]

FIG. 1 is an optical layout diagram showing an embodiment of a method and apparatus for measuring an electrostatic latent image according to the present invention.

FIG. 2 is a graph showing a relationship between an accelerating voltage and a secondary electron emission ratio δ in the charged particle beam irradiation part of the above embodiment.

FIG. 3 is a front view schematically showing an example of an image forming apparatus in which a photoconductor as a measurement object of the present invention is used.

FIG. 4 is an enlarged cross-sectional view showing a structure of a photoconductor that is a measurement target of the present invention.

FIG. 5 is a plan view showing a measurement example according to the present invention and an example in which a known reference potential is arranged in an electron beam scan region.

FIG. 6 is a block diagram showing an example of each part control system applied to the embodiment of the present invention.

FIG. 7 is an optical layout diagram showing another embodiment of the electrostatic latent image measuring method and the measuring apparatus according to the present invention.

FIG. 8 is a front view showing an example of an exposure optical system that can be used in the above embodiment.

FIG. 9A is an end view and FIG. 9B is a perspective view showing an example of a rod lens array forming a part of the exposure optical system.

FIG. 10 is a perspective view showing an example of a scanning optical system that can be used in the present invention.

FIG. 11 is an optical layout diagram showing still another embodiment of the method and apparatus for measuring an electrostatic latent image according to the present invention.

FIG. 12 is an optical layout diagram showing still another embodiment of the method and apparatus for measuring an electrostatic latent image according to the present invention.

[Explanation of symbols]

10 Electron beam irradiation unit 11 electron gun 12 Condenser lens 13 Beam Blanker 14 Scan lens 16 Sample setting section 18 detector 20 Exposure section 30 samples (photoreceptor)

Claims (14)

[Claims] 1. An electrostatic latent image, wherein an electrostatic latent image is formed by scanning a sample surface with a charged particle beam in a device for scanning a charged particle beam to generate a charge distribution on the sample. Forming method. 2. A device for scanning a charged particle beam to scan a sample surface with the charged particle beam to generate a charge distribution on the sample to form an electrostatic latent image. Electrostatic latent image forming device. 3. A method of scanning a sample surface with a charged particle beam and measuring the sample surface by a detection signal obtained by this scanning, comprising: A method of measuring an electrostatic latent image, which comprises scanning to generate a charge distribution on a sample. 4. A method of scanning a sample surface with a charged particle beam and measuring the sample surface by a detection signal obtained by this scanning, comprising charging a sample, exposing the sample with an exposure optical system, and distributing the charge distribution. A method of measuring an electrostatic latent image, which comprises: 5. An apparatus for scanning a sample surface with a charged particle beam and measuring the sample surface by a detection signal obtained by the scanning, comprising: a means for charging the sample; and an optical system means for exposing the sample. An electrostatic latent image measuring device, characterized in that it has means for generating a charge distribution. 6. The electrostatic latent image measuring device according to claim 5, wherein the means for charging the sample comprises means for irradiating the sample with an electron beam. 7. The device for charging the sample is a device for charging the sample by irradiating the sample with an electron beam at an accelerating voltage higher than an accelerating voltage at which the secondary electron emission ratio of the sample is 1. Electrostatic latent image measuring device. 8. A means for calculating a potential amount by arranging a known reference potential in a scanning region of a charged particle beam and comparing the secondary electron signal intensity of the reference potential with the signal intensity of a measurement sample. The electrostatic latent image measuring device according to claim 5, 6 or 7, characterized in that it has. 9. A method of measuring the electrostatic latent image on the sample surface by scanning the sample surface with a charged particle beam and measuring the electrostatic latent image on the sample surface by the detection signal obtained by this scanning. A method for measuring an electrostatic latent image, which comprises: 10. A method of scanning a sample surface with a charged particle beam and measuring an electrostatic latent image on the sample surface by a detection signal obtained by the scanning, comprising: electrostatically moving the sample surface while moving a sample having a charge distribution. A method for measuring an electrostatic latent image, which comprises measuring a latent image. 11. An apparatus for scanning a sample surface with a charged particle beam and measuring an electrostatic latent image on the sample surface by a detection signal obtained by the scanning, while moving a sample having a charge distribution while moving the sample surface. An electrostatic latent image measuring device having means for measuring an electrostatic latent image. 12. An apparatus for scanning a sample surface with a charged particle beam and measuring an electrostatic latent image on the sample surface by a detection signal obtained by the scanning, wherein the electrostatic latent image is formed on the sample. An apparatus for measuring an electrostatic latent image, comprising: forming means; and measuring means for moving a sample having a charge distribution to a charged particle beam irradiation position for measurement. 13. The electrostatic latent image forming apparatus according to claim 2, further comprising an exposing unit as the electrostatic latent image forming unit. 14. The electrostatic latent image forming apparatus according to claim 13, wherein the sample and the exposing means are arranged in the same chamber.