JP2008096971A - Vacuum chamber apparatus, electrostatic latent image forming apparatus, electrostatic latent image measuring apparatus, and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a vacuum chamber apparatus in which a light beam from a scanning optical system is guided into a vacuum chamber and a sample is scanned with the light beam while extraneous light from outside a vacuum chamber is blocked. <P>SOLUTION: The vacuum chamber apparatus includes: a vacuum sample stage portion disposed in the vacuum chamber, used to place a sample thereon, and movable in an optional direction; a scanning optical system disposed outside the vacuum chamber, used to emit and deflect a scanning beam for scanning a sample; an extraneous light blocking means connecting the vacuum chamber and scanning optical system together, and used to block extraneous light entering the vacuum chamber; an internal observation means disposed in the connection portion of the vacuum chamber and extraneous light blocking means, and capable of transmitting the scanning beam; and a scanning beam folding means with which the scanning beam emitted from the scanning optical system is guided to the inside of the vacuum chamber via the extraneous light blocking means and internal observation means. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a vacuum chamber apparatus, an electrostatic latent image forming apparatus, an electrostatic latent image measuring apparatus, and an image forming apparatus, and a vacuum chamber apparatus applicable to measurement of surface potential distribution and surface charge distribution of a sample, The present invention relates to an electrostatic latent image forming apparatus, an electrostatic latent image measuring apparatus, and an image forming apparatus.

Conventionally, 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 (see FIG. 7).
1. Charging: The electrophotographic photosensitive member is uniformly charged.
2. Exposure: The photosensitive member is irradiated with light, and charges are partially released corresponding to the image to form an electrostatic latent image.
3. Development: A visible image is formed on the electrostatic latent image with charged fine particles (hereinafter referred to as toner).
4). Transfer: Move the developed and visualized toner image to paper or other transfer material.
5. Fixing: The toner forming the transfer image is fused to fix the image on the transfer material.
6). Cleaning: Cleans residual toner on the photoreceptor.
7). Static elimination: Removes residual charge on the photoreceptor.
The process factor and process quality of each of the above steps greatly affect the final output image quality. For this reason, in order to obtain a higher quality image, it is necessary to improve the process quality of each process. In particular, evaluating the quality of the electrostatic latent image after exposure is necessary for obtaining a high quality image. Very 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 photoreceptor. However, in spite of the fact that it should be designed so that an optimum electrostatic latent image on the photoreceptor that directly affects the behavior of the toner particles should be formed, such a design is performed. I don't mean. In addition, a clear mechanism for converting exposure energy into an electrostatic latent image has not been established. Therefore, if information obtained from the electrostatic latent image can be taken into the optical system design, higher image quality can be obtained, and it can be expected to design the image forming apparatus at a low cost.
Japanese Patent No. 3009179 JP-A-11-184188 Japanese Patent Laid-Open No. 3-49143

  However, it is extremely difficult to measure an electrostatic latent image, and the actual situation is that it 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, electrostatic attraction generated as an interaction between the electrostatic latent image and the cantilever. Or an induced current is measured and converted into a potential distribution. The electrostatic attraction type is commercially available as SPM (Scanning Probe Microscope), and the induced current type is described in, for example, Patent Document 1 and Patent Document 2.

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,
<1> Absolute distance measurement is required.
<2> Measurement takes time, during which the state of the latent image changes.
<3> Discharge and adsorption occur.
<4> The sensor itself disturbs the electric field.
Even if it can be used for other purposes, an electrostatic latent image cannot be measured in actual use.

  For this reason, as a realistic measurement method, the electrostatic latent image is visualized by applying a charge to the toner, which is a colored fine powder, and developing it by the Coulomb force acting between the charged toner and the electrostatic latent image. And a method of transferring the toner image onto paper or tape is generally employed. However, in this method, since the development and transfer processes are performed, the electrostatic latent image itself is not measured.

  On the other hand, a method for measuring a potential pattern using an electron beam is known. This has already been put to practical use for LSI failure analysis. This measurement method is a case where the sample is a conductor, and a measurement object is completely different from a dielectric material such as a photoconductor intended by the present invention, and cannot be applied to measurement of a dielectric material such as a 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 the conductor, and the potential amount is a narrow range of 0 to 5 V at most, so that no charge-up phenomenon occurs. The potential state does not change by irradiation with the electron beam.

  For example, Patent Document 3 discloses a method for observing an electrostatic latent image using an electron beam, but the sample is limited to an LSI chip or a sample that can store and hold an electrostatic latent image. That is, a normal photoconductor that causes dark decay cannot be measured.

  Since a normal dielectric can hold a charge semipermanently, even if measurement is performed over time after forming a charge distribution, the measurement result is not affected. However, in the case of a photoconductor, since the resistance value is not infinite, the charge cannot be held for a long time, dark decay occurs, and the surface potential decreases with time. The time that the photoconductor can hold the charge is at most several tens of seconds even in the dark room. Therefore, even if an attempt is made to observe in an electron microscope (SEM) after charging and exposure, the electrostatic latent image disappears in the preparation stage.

  By the way, a photoconductor sample used in an electrophotographic process has a generally cylindrical shape, and it is desired to measure the electrostatic latent image distribution generated on the cylindrical photoconductor in a non-destructive manner with high resolution. Even if the charge distribution forming means is the same, the electrostatic latent image changes due to the deterioration of the photoreceptor over time. For this reason, it is desired to evaluate the variation of the electrostatic latent image over time.

  The present invention has been made in order to solve the above-described problems of the prior art, and forms an electrostatic latent image in a measurement apparatus by irradiating a charged particle beam, and after the latent image is formed. It is an object of the present invention to provide a vacuum chamber apparatus, an electrostatic latent image forming apparatus, an electrostatic latent image measuring apparatus, and an image forming apparatus that can perform measurement within a short period of time.

  In addition, the beam profile of the electrostatic latent image is accurately and quantitatively evaluated. Furthermore, not only the static beam profile but also the electrostatic latent image obtained by dynamically scanning the beam in a state close to actual use, and by multiple exposure of dots An object of the present invention is to provide an apparatus capable of measuring and evaluating the influence on the formation of a latent image.

  In order to achieve such an object, the invention described in claim 1 is provided inside a vacuum chamber, placed on the outside of the vacuum chamber, and a vacuum sample stage portion on which a sample can be placed and moved in any direction. A scanning optical system for emitting and deflecting a scanning beam for scanning the sample, a vacuum chamber and the scanning optical system, and an external light shielding means for shielding external light incident on the inside of the vacuum chamber; An internal observation means that is provided at a connecting portion between the chamber and the external light shielding means and through which the scanning beam can be transmitted, and the scanning beam emitted from the scanning optical system is vacuum-excited through the external light shielding means and the internal observation means. Scanning beam folding means for guiding the inside of the chamber.

  According to a second aspect of the invention, in the first aspect of the invention, the scanning optical system is placed on a parallel movement device capable of parallel movement, and a scanning beam is emitted from the scanning optical system while scanning the sample. The two-dimensional scanning is enabled by moving the translation device and the vacuum sample stage.

  According to a third aspect of the present invention, in the first or second aspect of the present invention, the internal observation means is disposed at a position that is approximately 45 degrees with respect to the vertical axis of the vacuum chamber, and the scanning beam folding means The two-dimensional scanning is performed by moving the entire scanning optical system in the horizontal direction so as to be integrated with the scanning optical system so that the emission angle is approximately 45 degrees with respect to the vertical axis of the vacuum chamber.

  According to a fourth aspect of the present invention, in the invention according to any one of the first to third aspects, the scanning optical system is an optical unit substantially sealed by an optical housing and a cover. The space between the units is covered with external light shielding means.

  The invention according to claim 5 is the invention according to claim 4, wherein the external light shielding means is composed of an outer cylinder, an inner cylinder, and a flexible light-shielding member, and the outer cylinder and the inner cylinder are non-contact aligned. It has the part.

  The invention according to claim 6 is the invention according to claim 5, wherein the mating portion has a labyrinth structure.

  The invention described in claim 7 is the invention described in claim 5 or 6, characterized in that the light shielding member is an elastic member or an elastic member-drawn non-woven fabric.

  According to an eighth aspect of the present invention, in the invention according to any one of the first to seventh aspects, the scanning optical system is movable in at least three axial directions, and at least two axial directions can be finely adjusted. A mechanism is provided.

  The invention according to claim 9 is the invention according to any one of claims 1 to 8, wherein the structure in which the vacuum chamber and the scanning optical system are arranged is placed on a common vibration isolation table. The cantilever structure facilitates the operation of the sample exchange chamber provided in the vacuum chamber and the sample exchangeability.

  A tenth aspect of the invention is the invention according to any one of the first to ninth aspects, wherein the scanning optical system is disposed on a flat plate and moved in a direction of approximately 45 ° with respect to the vertical axis of the vacuum chamber. A parallel movement mechanism capable of adjusting the position is provided, and the parallel movement mechanism includes an X-axis stage and a slide guide.

  According to an eleventh aspect of the present invention, in the tenth aspect of the present invention, the translation mechanism is a direction perpendicular to the vertical axis of the vacuum chamber, parallel to the operation direction of the sample exchange chamber, or vertical of the vacuum chamber. The scanning optical system is moved in a direction orthogonal to the axis and in a direction orthogonal to the operation direction of the sample exchange chamber.

  The invention according to claim 12 is the invention according to any one of claims 1 to 11, wherein the structure on which the scanning optical system is mounted includes a plurality of substrates and a plurality of stays, The plurality of stays can be attached to and detached from the vibration isolation table in an integrated state by a fastening member.

  A thirteenth aspect of the present invention includes the vacuum chamber device according to any one of the first to twelfth aspects, wherein the sample surface is scanned with a charged particle beam to generate a charge distribution on the sample surface, and electrostatic A latent image is formed.

  A fourteenth aspect of the invention includes the vacuum chamber device according to any one of the first to twelfth aspects, and the measurement of the sample surface is performed by a detection signal obtained by scanning the sample surface with a charged particle beam. It is characterized by performing.

  A fifteenth aspect of the invention is an image forming apparatus having a photoconductor evaluated by the apparatus according to any one of the first to fifteenth aspects, wherein the writing light source wavelength is 680 nm or less, and the photoconductor surface. When the beam spot diameter on the photosensitive member surface is A and the latent image diameter to be formed is B, 1.0 <B / A <2.0 is satisfied. Features.

  According to the sixteenth aspect of the present invention, when the absolute value of the charging potential of the photosensitive member is C [V] and the latent image depth of one beam spot is D [V] in the fifteenth aspect of the present invention, the following is obtained. The writing light quantity is set so as to satisfy 7 <D / C <0.9.

  According to the present invention, it is possible to scan the sample by guiding the light beam of the scanning optical system to the inside of the vacuum chamber while blocking outside light from the outside of the vacuum chamber.

  The best mode for carrying out the present invention will be described below in detail with reference to the accompanying drawings.

First, an embodiment of the electrostatic latent image measuring device (electrostatic latent image forming device) of the present invention will be described.
FIG. 5 is a diagram showing a configuration of an electrostatic latent image measuring apparatus according to an embodiment of the present invention (here, a case where an optical system for writing with a stationary beam is provided in the vacuum chamber will be described). The electrostatic latent image measuring apparatus includes a charged particle irradiation unit 10 that irradiates a charged particle beam, an exposure unit 20 that performs exposure, a sample setting unit 16 that sets a sample, and secondary electron detection that detects secondary electrons. And a container 18. All of these are located in the same chamber and the chamber is evacuated. This vacuum chamber will be described later (see FIGS. 1 and 2). As used herein, “charged particle” refers to a particle that is affected by an electric field or magnetic field, such as an electron beam or an ion beam.

Hereinafter, the charged particle irradiation unit 10 will be described as the electron beam irradiation unit 10.
As shown in FIG. 5, 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 an ON / OFF electron beam. A beam blanker 13 for turning off, a scanning lens 14 for scanning an electron beam that has passed through the beam blanker 13, and an objective lens 15 for condensing the electron beam that has passed through the scanning lens 14 are provided. Become. The scanning lens 14 is a so-called deflection coil. A driving power source (not shown) is connected to each of the other lenses. In the case of an ion beam, a liquid metal ion gun or the like is used instead of an electron gun.

  In FIG. 5, the secondary electron detector 18 uses a scintillator, a photomultiplier tube, or the like.

  In FIG. 5, the exposure unit 20 includes a light source 21 having a wavelength having sensitivity with respect to a photoconductor configured as described later, a collimating lens 22, an aperture 23, an imaging lens 25, and the like. A desired beam diameter and beam profile can be generated on the placed sample 30. As the light source 21, an LD (Laser Diode) or the like can be used. Further, the light source 21 is controlled by an LD control means (see FIG. 10) or the like so that an appropriate exposure time and exposure energy can be irradiated. In order to form a line pattern composed of an electrostatic latent image on the sample 30, a scanning mechanism using a galvano mirror or a polygon mirror may be attached to the optical system of the exposure unit 20.

  As shown in FIG. 8, the main structure of the photoreceptor constituting the sample 30 is that a charge generation layer (CGL) and a charge transport layer (CTL) are formed on a conductive support (conductive layer). . When the surface of the charge transport layer CTL is exposed in a charged state, light is absorbed by the charge generation material (CGM) of the charge generation layer CGL, and positive and negative charge carriers are generated. One of the carriers is injected into the charge transport layer CTL and the other into the conductive support (conductive layer) by an electric field. The carriers injected into the charge transport layer CTL move in the charge transport layer CTL to the surface of the charge transport layer CTL by an electric field, and are combined with charges on the surface of the photoreceptor to disappear. Thereby, a charge distribution is formed on the surface of the photoreceptor. That is, an electrostatic latent image is formed.

Next, the operation of the electrostatic latent image measuring device (electrostatic latent image forming device) will be described with reference to FIG.
First, the charged particle beam irradiation unit 10 irradiates the photoconductor sample 30 with an electron beam. The relationship between the acceleration voltage and the secondary electron emission ratio δ at this time is shown in FIG. As shown in FIG. 6, by setting the acceleration voltage E1 to an acceleration voltage higher than the acceleration voltage E0 at which the secondary electron emission ratio δ is 1, the amount of incident electrons exceeds the amount of emitted electrons. Accumulation in the sample 30 causes charge-up. As a result, the sample 30 can be negatively charged uniformly. A desired charging potential can be formed by appropriately setting the acceleration voltage and the irradiation time. Once the charged potential is formed, the electron beam is once turned off.

  Next, the photosensitive member sample 30 is exposed via the optical system of the exposure unit 20. The optical system is adjusted to form a desired beam diameter and beam profile. By performing exposure, an electrostatic latent image can be formed on the photoreceptor 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 a secondary electron detector 18 including a scintillator, a photomultiplier tube, etc., and converted into an electrical signal. Observe the potential contrast image.

  In order to convert a potential contrast image into a potential, a conversion table representing a correlation between the potential and the signal intensity may be prepared in advance, and the potential may be calculated from the signal intensity based on the conversion table.

  Further, a method of calculating a potential distribution by arranging a known reference potential in the electron beam scan region and comparing the secondary electron signal intensity with the reference potential may be used.

  As a method of arranging this reference potential, there is a method of arranging a plurality of conductive substrates 34 on an insulator 33 and setting a reference potential to each conductive substrate 34 as shown in FIG. Specifically, the voltage of the reference voltage source is divided by a resistor, and a reference potential is applied to each conductive substrate 34. In general, a portion having a lower potential than a portion having a high potential becomes brighter because the amount of secondary electrons emitted increases. In FIG. 9, a portion having a relatively low potential is displayed in white, and a portion having a high potential is displayed in black. In FIG. 9, reference numeral 30 denotes a sample, 31 denotes an electrostatic latent image, and 32 denotes an electron beam scan area. Secondary electrons are detected by the secondary electron detector 18 while scanning the surface of the sample 30 with an electron beam. The state of change of the detection signal intensity at that time is shown in the lower part of FIG. The signal intensity on the secondary electron detector 18 may be corrected when it changes depending on the setting conditions. Further, calibration may be performed in advance.

  After the measurement of the electrostatic latent image is completed, the residual charge on the sample 30 can be removed by irradiating the entire surface of the sample 30 with light using the light source 17 shown in FIG.

  FIG. 10 is a diagram showing an example of each control unit in the electrostatic latent image measurement apparatus of the present embodiment shown in FIG. As shown in FIG. 10, the electrostatic latent image measurement device of the present embodiment controls the LD control unit 36 that controls the light source 21, the charged particle control unit 37 that controls the scanning lens 14, and the light source 17 for residual charge removal. And a sample stage control unit 39 for controlling the movement of the sample setting unit (sample stage) 16. These LD control unit 36, charged particle control unit 37, LED control unit 38, sample stage control are included. The unit 39 is controlled by the host computer 35. The output of the secondary electron detector 18 is detected by the secondary electron detector 41, and the detection signal is processed by the signal processor 42 so that the secondary electron measurement result is output from the measurement result output unit 43. It is configured.

  The secondary electron emission ratio δ is expressed as secondary electron emission ratio δ = emitted electrons / incident electrons. Strictly speaking, since it is necessary to consider transmitted electrons and reflected electrons, emitted electrons = transmitted electrons. It is good to be + reflected electron + secondary electron

  When positive charging is desired, irradiation with an accelerating voltage with a secondary electron emission ratio of 1 or more as shown in FIG. In sample observation with a normal electron microscope (SEM), in order to avoid the effect of charge-up, it is common to observe under the condition of δ = 1, and it is known that no other acceleration voltage is used. In the present embodiment, one characteristic is that a charged potential is formed by intentionally charging up.

In the above description, it was described that the electron beam is once turned off after forming the charged potential, but instead of turning it off, it is converted to an acceleration voltage at which δ = 1, and the observation condition is set so that no charge-up occurs. A method of exposing in a state may be used.
As a charging method, another means such as contact charging may be used.

  1 and 2 are views showing an embodiment of a vacuum chamber apparatus of the present invention. The vacuum chamber apparatus of this embodiment is provided in the electrostatic latent image measurement apparatus.

  The vacuum chamber used in the vacuum chamber apparatus of the present embodiment has an opening (for inserting an electron gun, a detector, etc.) and a flange mounting portion by machining the inner diameter of the material on the cylinder and performing D cut. Form. The electron gun and the detector shown in FIGS. 1 and 2 show the electron gun 11 and the secondary electron detector 18 shown in FIGS.

  Inside the vacuum chamber, as shown in FIG. 2, a vacuum sample stage portion for moving the sample in three directions is attached to the flange. As shown in FIG. 1, on the back surface of the flange is a box-shaped structure, and a sample stage driving unit (in this embodiment, a stepping motor, a micro head, etc.) for driving the vacuum sample stage unit is an O-ring or the like. It has a structure to prevent leakage and attach. As shown in FIG. 1, a harness for supplying power to the vacuum chamber and taking out a signal can be relayed while maintaining a vacuum by using a feedthrough.

  As shown in FIG. 2, the vacuum sample stage unit, the sample stage drive unit, the feedthrough, and the like are integrated into a unit with the flange. Hereinafter, this is referred to as a vacuum sample stage unit.

  This vacuum sample stage unit is placed on a mounting table (for mounting the vacuum sample stage unit) placed on the guide rail shown in FIG. Make it possible.

  By sandwiching an O-ring between the flange mounting surface of the vacuum chamber and the flange surface of the vacuum sample stage unit and fastening with screws, the vacuum sample stage unit can be driven while maintaining a high degree of vacuum.

  FIG. 3 is a plan view showing the state in which the scanning optical system (optical unit) is arranged outside the vacuum chamber from above. As shown in FIG. 3, the scanning optical system is arranged on the right side in the direction orthogonal to the direction in which the vacuum sample stage unit is attached and detached. This is determined by the position of the glass window (internal observation means) for observing the inside of the vacuum chamber, and can be arbitrarily set as long as it does not interfere with the structure.

  FIG. 4 is a cross-sectional view of the vacuum chamber apparatus of the present embodiment. As shown in FIG. 4, a glass window for observing the inside of the vacuum chamber is arranged at a position of a right shoulder of 45 ° with respect to the vertical axis of the vacuum chamber, and a cylindrical internal light shielding tube (outside light shielding) is surrounded by the glass window. Means) is integrated and attached to the vacuum chamber. The external light shielding cylinder (external light shielding means) is integrated with the scanning optical system (optical unit), and its tip has a concave dent, and has a predetermined gap in the axial and radial directions from the tip of the internal light shielding cylinder. Have and mesh. This structure is generally called a labyrinth structure. By covering the outer periphery of the meshing portion with a flexible light shielding member (external light shielding means) such as an elastic member rubber or rubberized nonwoven fabric, external light (harmful light) incident on the inside of the vacuum chamber is prevented. be able to.

  In FIG. 4, the scanning optical system (optical unit) has a light source unit, a scanning lens, synchronization detection means, an optical deflector (polygon scanner in the figure) and the like, although not shown. That is, the scanning optical system (optical unit) has the same configuration as that of a conventional optical scanning device, and can modulate and scan a light beam in accordance with an image signal.

  In FIG. 4, a folding mirror (scanning beam folding means) is disposed after the scanning lens, and is held in the optical housing so as to be approximately 45 ° with respect to the vertical axis of the vacuum chamber. The entire scanning optical system is covered with a cover, and is shielded by being integrated with the external light shielding cylinder.

  In FIG. 4, the scanning optical system (optical unit) is fixed on a parallel movement table (a parallel movement device capable of parallel movement) installed on the structure, and is driven by a drive control means such as a stepping motor (not shown). Two-dimensional scanning is possible by moving in the horizontal direction in the figure and scanning with a light beam (scanning beam) simultaneously with the movement. Even if the acceleration / deceleration time of the stepping motor is anticipated, if the clearance at the light-shielding portion is equal to or greater than (necessary movement amount + acceleration / deceleration movement amount), writing at a constant speed is possible. The required amount of movement in this vacuum chamber apparatus is on the order of several millimeters, and writing at a constant speed can be sufficiently achieved.

  Further, since the distance to the image plane is also constant, high-precision writing with a constant beam spot diameter is possible.

  In FIG. 4, since the scanning optical system (optical unit) is arranged in a non-contact manner with respect to the vacuum chamber, vibration generated when driving an optical deflector such as a polygon scanner is directly propagated to the vacuum chamber. There is no. Further, although not shown in FIG. 4, if a damper is inserted between the structure and the vibration isolation table, a more effective vibration isolation effect can be obtained.

  Also, in FIG. 4, two-dimensional scanning is possible even when the parallel movement table is stopped by scanning the vacuum sample stage portion installed in the vacuum chamber while driving in a direction orthogonal to the scanning beam. .

  Also, when performing experimental measurements using this vacuum chamber device, various experiments and measurements can be performed by determining the scanning frequency and linear velocity from the required writing density and using the beam spot diameter, exposure energy, etc. as parameters. It can be performed.

  12 and 13 are diagrams showing an embodiment of the vacuum chamber apparatus of the present invention. The vacuum chamber apparatus of this embodiment is provided in the electrostatic latent image measurement apparatus.

FIG. 12 is a cross-sectional view for explaining a schematic configuration of the vacuum chamber apparatus of the present embodiment.
A sample stage is provided inside the vacuum chamber, and a sample such as a photoreceptor is set thereon. The sample stage can be moved by operating driving elements (stepping motor, micro head) outside the vacuum chamber. A vacuum port is maintained on the right shoulder of the vacuum chamber by sealing, for example, Kovar glass at the center of a cylindrical metal member as a viewport for internal observation, and then fastening the metal part with a gasket. However, an internal observation window is provided.

  The scanning optical system is placed on the structure and is placed on a vibration isolation table common to the vacuum chamber. As shown in FIG. 14, the vacuum chamber (electron gun) is arranged at a right shoulder position of 45 ° with respect to the vertical axis. This scanning optical system can be moved in at least three axial directions by a moving mechanism to be described later. By scanning the scanning beam from the view port toward the inside of the vacuum chamber, the scanning optical system has a predetermined beam spot diameter. Can be scanned.

FIG. 13 is an external view of the vacuum chamber device of the present embodiment as viewed from the front right and obliquely upward.
As shown in FIG. 13, a base is placed on a vibration isolation table, and three stays are placed on the base and fastened with screws. The fastening portion of the stay is a long hole and can be moved in a direction orthogonal to the operation of the sample exchange chamber shown in the direction of the arrow in the drawing. [Base: Fixed 1] is arranged on the upper part of the three stays and fastened with screws.

  The X-axis stage 1 is fixed to the front side of [Base: Fixed 1], the guide rail is fixed to the back side, and two moving platforms are arranged thereon. [Base: Movement 1] bridges the movement side upper surface of the X-axis stage 1 and the two movement platforms and fixes them with screws. The X-axis stage is assembled so as to be parallel to the moving direction of the sample exchange chamber, and the position can be adjusted in accordance with the resolution of the scale by rotating the microhead. In this embodiment, when moving to the vacuum chamber side, it moves in the direction of pushing the micro head, and when returning to the opposite side, it moves by the pulling force of the return spring of the X-axis stage. If the pulling force in the return direction is insufficient due to its own weight or the frictional force of the rail, increase the returning force by placing a tension spring between the [base: fixed 1] and [base: movement 1] with a spring hook or the like. be able to.

  Two [stays: 45 °] are erected on [base: movement 1], and [base: fixed 2] are screw-fastened thereon.

  The X-axis stage 2 is fixed on the front side of [Base: Fixed 2], and the guide rail is fixed on the back side. In this case, one moving table is provided. [Base: Movement 2] allows the movable surface of the X-axis stage 2 and the movable table to be bridged and fixed, and the microhead can be rotated to move in the direction parallel to the moving direction of the sample exchange chamber and in the direction of 45 °. Become. In the scanning optical system, four [stays: shafts] are erected on the [base: movement 2] and fastened with screws. In the present invention, each stay and each base have a laminated structure, and each X-axis stage is sandwiched between them to enable parallel movement with high accuracy in a predetermined direction.

Here, a sample exchange method will be described.
When setting the sample on the sample mounting table in the vacuum chamber, slide the sample exchange chamber fitted with glass on the end face to the right in FIG. 12, and place the sample on a connecting rod with a screw cut at the tip (not shown). After screwing the sample stage placed on it and sliding the sample exchange chamber to the left to bring it into close contact with the vacuum chamber, the sample exchange chamber is evacuated, vacuumed, and the shutter is opened to slide the connecting rod toward the vacuum chamber. Set the sample together with the sample table on the sample table (fixed by pressing the spring), rotate the threaded portion of the connecting rod counterclockwise, remove the threaded portion, and pull out the connecting rod. This operation is performed while visually confirming through the glass window of the sample exchange chamber. If the shutter is then closed, the sample setting is completed. The removal of the sample may be considered the opposite.

  The difficulty in this operation is when the sample is set on the sample mounting table in the vacuum chamber. Since the connecting rod is rotatable, it is set visually while matching the fitting portion at a predetermined position. At this time, if the structure is on the front side of the vacuum chamber image forming apparatus, the operator's head and arms are blocked by the structure, which makes the above work very difficult and also makes it difficult to replace the sample. It becomes the state.

  In this embodiment, as shown in FIGS. 13 and 16, the structure such as a stay is disposed on the back side of the apparatus, the scanning optical system is disposed on the upper side of the sample exchange chamber, and a plurality of bases are laminated. By using the holding structure, the obstacles on the front side of the apparatus are eliminated and the above-mentioned problems are solved.

  In addition, an X-axis stage is arranged on the front side as a parallel movement mechanism, a slide guide is arranged on the back side, and a micro head as a driving source is arranged on the front side, thereby improving operability and the visibility of the scale. We are trying to improve.

  FIG. 15 is a plan view of the vacuum chamber device according to the present embodiment as viewed from directly above. Since the bottoms of the three stays are elongated holes, the scanning position in the main scanning direction is adjusted as necessary. Can be done.

FIG. 17 is a diagram showing a scanning optical system arranged on a flat plate with the upper cover removed.
After a single beam diameter is emitted from a light source unit that emits a single beam or a plurality of beams through a coupling lens and an aperture, a predetermined line image is formed on a polygon surface through a cylinder lens, deflected and scanned by a polygon scanner, and an fθ lens. Through this, the spot is narrowed down to a predetermined spot diameter and scanned at a constant speed. A part of the beam that has passed through the fθ lens is branched by a folding mirror for synchronization (hidden in the figure), narrowed down by a synchronization optical system, and then output as a pulse signal from the sensor of the synchronization detection plate.

  A light shielding tube is provided on a bracket provided on the side surface of the flat plate, and the scanning beam is emitted from this hole. The light shielding cylinder is fitted with a metal portion on the cylinder of the viewport provided in the vacuum chamber by providing a predetermined gap (fitting portion) in the radial direction (see FIG. 15). By providing this fitting portion, external light does not reach the inside of the vacuum chamber unless it is reflected twice or more, and therefore attenuates to a level that does not cause a problem in measurement. If necessary, a non-woven fabric or the like may be attached to the tip of the light shielding tube so as to close the gap.

  In the present embodiment, the light shielding cylinder and the viewport are fitted with a predetermined gap, so that the movement in the three-axis direction is possible and the outside light can be blocked.

  FIG. 16 is a view showing a state in which the scanning optical system and the structure are removed from the vibration isolation table. Since the entire structure is mounted on the base, assembly and maintenance work can also be removed from the vibration isolation table. No vibration or impact is applied to the vacuum pump or the like, and the durability of the vacuum pump or the like is not impaired.

  In addition, as shown in FIG. 17, the scanning optical system is arranged on a single flat plate, and only the flat plate can be removed, so the characteristics of the optical system are measured on an external measuring machine. In this case, it can be set easily, and the measurement efficiency can be increased.

  Also, when performing experimental measurements using the vacuum chamber apparatus of this embodiment, the scanning frequency and linear velocity are determined from the required writing density, and the beam spot diameter, exposure energy, lighting time duty, etc. are used as parameters. Thus, various experiments and measurements can be performed. In addition, since multi-beams can be easily formed, the influence of overlapping beam spot diameters or reciprocity failure can be measured quantitatively.

  Although the first and second embodiments of the vacuum chamber apparatus of the present invention have been described above, the configuration of the first embodiment and the configuration of the second embodiment may be arbitrarily combined.

  FIG. 7 is a diagram showing an embodiment of the image forming apparatus of the present invention. The image forming apparatus is an optical printer or the like, and has a photoconductive photosensitive member 8 formed in a cylindrical shape as a photosensitive medium.

  This photoconductor 8 is a photoconductor having the same composition as the sample evaluated by the electrostatic latent image measurement method (surface potential distribution measurement method) performed by the electrostatic latent image measurement device of this embodiment. Note that since the electrophotographic process is a method generally performed in the past, description thereof is omitted here.

  The latent image formation process can be quantitatively analyzed in detail by evaluating the photosensitive member 8 by the electrostatic latent image measurement method (surface potential distribution measurement method) performed by the electrostatic latent image measurement apparatus of the present embodiment. Therefore, the exposure amount can be optimized, charging and exposure conditions that do not place a burden on the photoreceptor can be known, and energy saving and high durability can be realized.

  Furthermore, attempts have been made to reduce the beam spot diameter to 60 μm or less by optimizing the optical system and shortening the light source wavelength to 680 nm or less in order to improve the output image quality. Photoconductors have low sensitivity to short-wavelength light, and small-diameter beams are strongly affected by light scattering and charge diffusion within the photoconductor, increasing the latent image diameter and shallowing the latent image depth. Therefore, the final output image has a problem in that the stability of gradation and sharpness cannot be obtained.

The beam spot diameter here is defined as a diameter in a range where the beam spot light quantity distribution is not less than e ^{−2 of the} maximum light quantity. The latent image diameter is defined as a diameter in a range in which the latent image charge density distribution is equal to or larger than e ⁻² of the charge density difference of the portion where the difference in charge density is the largest with reference to the charge density of the portion where the light is not irradiated.

It is known that the composition and thickness of the charge transport layer affect the light scattering and charge diffusion degree, and the charge generation layer composition affects the sensitivity, but no clear correlation is known. Therefore, the electrostatic latent image measuring method (surface potential distribution measuring method) performed by the electrostatic latent image measuring apparatus of the present embodiment is prepared by changing the composition and thickness of the charge transport layer and the composition of the charge generating layer. ) And the same conditions as those used in the image forming apparatus, for example, with a charging potential of 800 V, exposure energy of 4 mJ / m ² , exposure is performed under the conditions of a light source wavelength of 680 nm or less and a beam spot diameter of 60 μm or less. 11 (a) and 11 (b), when the beam spot diameter on the surface of the photosensitive member is A and the formed latent image diameter is B,
1.0 <B / A <2.0
If a photoconductor that satisfies the above conditions is selected, gradation and sharpness stability can be realized in the final output image.

  Here, the lower limit of 1.0 is a theoretical limit that light scattering and charge diffusion always occur in any photoconductor and cannot be less than this, and the upper limit of 2.0 is a step in the final output image. This is the limit necessary to ensure the stability of tonality and sharpness.

Further, as shown in FIG. 11C, when the absolute value of the charged potential of the photosensitive member is C [V] and the latent image depth of the beam spot is D [V],
0.7 <D / C <0.9
If the amount of writing light is set so as to satisfy the above, it is desirable because the reproducibility of one beam spot is improved and the durability of the photoreceptor is not impaired.

  Here, the lower limit of 0.7 is the latent image depth necessary for reliably developing one beam spot, and the upper limit of 0.9 is a light beam with a deeper latent image depth. In such a case, there is a limit that anxious deterioration of the photoreceptor is a concern.

  Therefore, by actually measuring the diameter of the latent image with the electrostatic latent image measuring device of the present embodiment and evaluating the photosensitive member with the electrostatic latent image measuring device, the exposure amount can be optimized. Wasteful energy consumption due to exposure can be suppressed. Further, charging and exposure conditions that do not impose a burden on the photosensitive member can be known, and the life of the photosensitive member can be extended.

In the image forming apparatus, a plurality of light sources may be provided in the optical scanning device to form a multi-beam.
In addition, a plurality of toner images having different colors may be formed using a plurality of optical scanning devices and a photoreceptor, and a color image may be formed by superimposing the toner images.

Although the embodiments of the present invention have been described above, according to the vacuum chamber apparatus of the present invention, the light beam of the scanning optical system can be guided to the inside of the vacuum chamber and scanned on the sample while blocking the outside light from the outside of the vacuum chamber. Therefore, there is an effect that the size restriction is small and the degree of freedom of arrangement is large compared to the method in which the scanning optical system is arranged inside the vacuum chamber. In addition, it is possible to prevent deterioration of measurement environment conditions such as generation of gas and lowering of the degree of vacuum due to insertion of scanning optical system drive parts and electrical parts inside the vacuum chamber.
Furthermore, since it can be used in common with an optical scanning device used in an image forming apparatus or the like, the cost can be kept low.

  Further, according to the vacuum chamber apparatus of the present invention, the translation device necessary for the two-dimensional scanning is arranged outside the vacuum chamber, so that the degree of vacuum is deteriorated and the internal contamination is caused by the lubricant of the driving source. There is nothing. Further, it is possible to perform two-dimensional scanning selectively using a vacuum sample stage in accordance with the isokinetic accuracy.

  Further, according to the vacuum chamber apparatus of the present invention, the optical path length to the image plane can be made constant, so that high-precision writing with a stable beam spot diameter can be performed.

  Further, according to the vacuum chamber apparatus of the present invention, the external light is blocked by the light shielding device to prevent image deterioration such as image unevenness and contrast reduction due to the external light, and the vacuum chamber and the scanning optical system are driven in a non-contact manner. Image degradation such as spot position deviation due to vibration does not occur.

Further, according to the vacuum chamber apparatus of the present invention, the scanning optical system can be moved in the three-axis directions, so that the beam spot diameter on the sample surface in the vacuum chamber can be arbitrarily changed, and latent image formation is also possible. Correspondingly, it can be changed arbitrarily. Therefore, a meaningful experiment can be performed using parameters such as the relationship between the electrostatic latent image diameter and the latent image depth.
In addition, since the scanning position in the main scanning direction and the sub-scanning direction with respect to the sample surface can be set arbitrarily, the sample surface can be scanned over a wide range, and macroscopic evaluations such as defects and unevenness of the photoreceptor can be performed.

  Further, according to the vacuum chamber apparatus of the present invention, the structure on which the scanning optical system is mounted has a cantilever structure on the upper side of the sample exchange chamber and on the front side from the back of the vibration isolation table of the vacuum chamber image forming apparatus. This makes it possible to easily and reliably perform the sample exchange and the position adjustment of the scanning optical system from the front surface of the vacuum chamber image forming apparatus.

  Further, according to the vacuum chamber apparatus of the present invention, the scanning optical system is arranged on the flat plate, the scanning beam is emitted in parallel with the flat plate, and is scanned from the direction of about 45 ° with respect to the vertical axis of the vacuum chamber device. Therefore, it is not necessary to arrange a folding mirror after the fθ lens, so that optical characteristics are not deteriorated and light utilization efficiency is not lowered. Further, since the scanning optical system can be moved in the 45 ° direction and positioned with high accuracy, the spot diameter can be arbitrarily changed.

  Further, according to the vacuum chamber apparatus of the present invention, the scanning optical system can be moved in a direction orthogonal to the vertical axis of the vacuum chamber apparatus and parallel to the operation direction of the sample exchange chamber or in a direction orthogonal to the operation direction of the sample exchange chamber. Thus, it is possible to adjust the position of the scanning beam with respect to the sample without impairing the operability of the sample exchange.

  Further, according to the vacuum chamber apparatus of the present invention, it is possible to easily remove and assemble the scanning optical system and the structure from the vibration isolation table, so that work such as maintenance can be removed from the vibration isolation table. Can be done in the state. Since disturbances such as vibration and shock are not given to the vacuum pump or the like, the durability of the vacuum pump or the like is not impaired.

  According to the electrostatic latent image forming apparatus of the present invention, an electrostatic latent image can be formed by forming a charge distribution on a sample in a vacuum apparatus that scans a charged particle beam.

  According to the electrostatic latent image measuring apparatus of the present invention, the surface charge of the sample, which has been extremely difficult in the past, has a means for forming a charge distribution on the sample in a vacuum device that scans a charged particle beam. The distribution can be measured.

  According to the image forming apparatus of the present invention, the writing light source wavelength is 680 nm or less, the beam spot diameter on the photoreceptor surface is 60 μm or less, the beam spot diameter on the photoreceptor surface is A, and the latent image formed Since the latent image carrier satisfying 1.0 <B / A <2.0 is used when the diameter is B, the electrostatic latent image is prevented from diffusing and the latent image depth is reduced. And early deterioration of the photoreceptor due to overexposure can be suppressed. Therefore, the life of the photoreceptor can be extended and the environmental load can be reduced. As a final output image, it is possible to realize high density, and stability of gradation and sharpness.

  Further, according to the image forming apparatus of the present invention, when the absolute value of the charged potential of the photosensitive member is C [V] and the latent image depth of the beam spot is D [V], 0.7 <D / Since the writing light quantity is set so as to satisfy C <0.9, the reproducibility of one beam spot is improved and the durability of the photoconductor is not impaired, so that the final output image has a high density and gradation. And stability of sharpness can be realized.

  Although the embodiments and examples of the present invention have been described above, the present invention is not limited to the descriptions of the above embodiments and examples, and various modifications can be made without departing from the scope of the invention.

It is a side view which shows the external appearance of the vacuum chamber apparatus which is one Example of this invention. It is a perspective view which shows the structure in the vacuum chamber of the vacuum chamber apparatus which is one Example of this invention. It is a top view which shows the state which has arrange | positioned the scanning optical system outside the vacuum chamber apparatus which is one Example of this invention. It is a sectional side view which shows the structure of the vacuum chamber apparatus which is one Example of this invention. It is a figure which shows the structure of the electrostatic latent image measuring device which is one Embodiment of this invention. It is a graph explaining an acceleration voltage. 1 is a diagram illustrating a configuration of an image forming apparatus according to an embodiment of the present invention. It is sectional drawing which shows the main structures of the photoreceptor which makes the actual condition of a sample. It is a figure explaining the method of arrange | positioning a reference electric potential. It is a figure which shows the structure of each control part in the electrostatic latent image measuring device which is one Embodiment of this invention. (A) is a graph showing the beam spot diameter A on the photoreceptor surface, (b) is a graph showing the latent image diameter B formed on the photoreceptor surface, and (c) is a charging potential of the photoreceptor. Is a graph showing the absolute value C and the latent image depth D of one beam spot. It is a sectional side view which shows schematic structure of the vacuum chamber apparatus which is one Example of this invention. It is a perspective view which shows the external appearance of the vacuum chamber apparatus which is one Example of this invention. It is a side view which shows the external appearance of the vacuum chamber apparatus which is one Example of this invention. It is a top view which shows the external appearance of the vacuum chamber apparatus which is one Example of this invention. It is a perspective view which shows the state which removed the scanning optical system and the structure from the vibration isolator. It is a perspective view which shows the scanning optical system arrange | positioned on the flat plate of the state which removed the upper cover.

Explanation of symbols

10 Charged particle irradiation unit (electron beam irradiation unit)
DESCRIPTION OF SYMBOLS 11 Electron gun 12 Condenser lens 13 Beam blanker 14 Operation lens 15 Objective lens 16 Sample installation part (sample stand)
17 Light source for residual charge removal 18 Secondary electron detector 20 Exposure unit 21 Light source 22 Collimating lens 23 Aperture 25 Imaging lens 30 Sample 31 Electrostatic latent image 32 Electron beam scan region 33 Insulator 34 Conductive substrate 35 Host computer 36 LD control unit 37 Charged particle control unit 38 LED control unit 39 Sample stage control unit 41 Secondary electron detection unit 42 Signal processing unit 43 Measurement result output unit

Claims (16)

A vacuum sample stage unit provided inside the vacuum chamber, on which a sample is placed and movable in an arbitrary direction;
A scanning optical system that is disposed outside the vacuum chamber and emits and deflects a scanning beam for scanning the sample;
An external light shielding means for coupling the vacuum chamber and the scanning optical system, and shielding external light incident on the vacuum chamber;
An internal observation means provided at a connecting portion between the vacuum chamber and the external light shielding means, and capable of transmitting the scanning beam;
A scanning beam folding means for guiding the scanning beam emitted from the scanning optical system to the inside of the vacuum chamber via the external light shielding means and the internal observation means;
A vacuum chamber apparatus comprising: The scanning optical system is placed on a translation device capable of translation,
The two-dimensional scanning is enabled by moving the parallel moving device and the vacuum sample stage while emitting the scanning beam from the scanning optical system and scanning the sample. Vacuum chamber equipment. The internal observation means is disposed at a position that is approximately 45 degrees with respect to the vertical axis of the vacuum chamber,
The scanning beam folding means is disposed integrally with the scanning optical system so that an emission angle of the scanning beam is approximately 45 degrees with respect to the vertical axis of the vacuum chamber,
3. The vacuum chamber apparatus according to claim 1, wherein the scanning optical system is moved in the horizontal direction to perform two-dimensional scanning. The scanning optical system is an optical unit substantially sealed with an optical housing and a cover,
4. The vacuum chamber apparatus according to claim 1, wherein a space between the internal observation unit and the optical unit is covered with the external light shielding unit. The external light shielding means is composed of an outer cylinder, an inner cylinder, and a flexible light shielding member,
The vacuum chamber apparatus according to claim 4, wherein the outer cylinder and the inner cylinder have a non-contact mating portion.   The vacuum chamber apparatus according to claim 5, wherein the mating portion has a labyrinth structure.   The vacuum chamber apparatus according to claim 5, wherein the light shielding member is an elastic member or an elastic member-drawn nonwoven fabric.   The vacuum chamber according to any one of claims 1 to 7, wherein the scanning optical system is movable in at least three axial directions, and an adjustment mechanism capable of fine adjustment in at least two axial directions is provided. apparatus. The structure in which the vacuum chamber and the scanning optical system are arranged is placed on a common vibration isolation table,
The vacuum according to any one of claims 1 to 8, wherein the structure is a cantilever structure that facilitates the operation of the sample exchange chamber provided in the vacuum chamber and the sample exchangeability. Chamber device. The scanning optical system is disposed on a flat plate, and has a parallel movement mechanism that can move in a direction of approximately 45 ° with respect to the vertical axis of the vacuum chamber and can be adjusted in position.
The vacuum chamber apparatus according to claim 1, wherein the parallel movement mechanism includes an X-axis stage and a slide guide.   The parallel movement mechanism is arranged in a direction perpendicular to the vertical axis of the vacuum chamber, in a direction parallel to the operation direction of the sample exchange chamber, or in a direction perpendicular to the vertical axis of the vacuum chamber. The vacuum chamber apparatus according to claim 10, wherein the scanning optical system is moved in a direction orthogonal to an operation direction.   The structure on which the scanning optical system is mounted includes a plurality of substrates and a plurality of stays, and the plurality of substrates and the plurality of stays are attached to and detached from the vibration isolation table in a state of being integrated by a fastening member. The vacuum chamber device according to claim 1, wherein the vacuum chamber device can be used. A vacuum chamber apparatus according to any one of claims 1 to 12,
An electrostatic latent image forming apparatus that scans a sample surface with a charged particle beam, generates a charge distribution on the sample surface, and forms an electrostatic latent image. A vacuum chamber apparatus according to any one of claims 1 to 12,
An electrostatic latent image measuring apparatus for measuring a sample surface based on a detection signal obtained by scanning the sample surface with a charged particle beam. An image forming apparatus having a photosensitive member evaluated by the apparatus according to claim 1,
When the wavelength of the writing light source is 680 nm or less, the beam spot diameter on the surface of the photoreceptor is 60 μm or less, the beam spot diameter on the photoreceptor surface is A, and the latent image diameter to be formed is B. An image forming apparatus satisfying 0 <B / A <2.0.   Writing is performed so as to satisfy 0.7 <D / C <0.9, where the absolute value of the charging potential of the photosensitive member is C [V] and the latent image depth of one beam spot is D [V]. The image forming apparatus according to claim 15, wherein the amount of light is set.

Images