WO2007049357A1

WO2007049357A1 - Secondary electron emission rate measuring apparatus

Info

Publication number: WO2007049357A1
Application number: PCT/JP2005/019935
Authority: WO
Inventors: Ali Ide; Yasuhiko Morimoto
Original assignee: Kyoto University
Priority date: 2005-10-28
Filing date: 2005-10-28
Publication date: 2007-05-03
Also published as: JPWO2007049357A1

Abstract

A low-cost and small secondary electron emission rate measuring apparatus is provided. The secondary electron emission rate measuring apparatus is provided with a secondary electron measuring section having a small secondary electron measuring unit and a sample holding section for holding a subject to be measured, in a vacuum chamber. The small secondary electron measuring unit is composed of a charged particle generating source, which has a tube-like electrode having an opening at the top and a bar-like electrode at the center axis section of the tube-like electrode, and generates charged particles by glow discharge plasma; an electrostatic lens for focusing charged particle beams and irradiating the subject with the focused beam; and a secondary electron collector section for capturing secondary electrons emitted from the subject. The secondary electron emission rate measuring apparatus is also provided with a gas exhaust section for depressurizing the vacuum chamber; a gas supplying section for supplying the charged particle generating source with a gas to be the charged particles; a voltage applying section and a current measuring section for applying voltages to the charged particle generating source, the electrostatic lens and the secondary electron collector electrode and measuring currents; and a control computer for controlling such sections and calculating secondary electron emission rates.

Description

Specification

Secondary electron emission rate measuring device

Technical field

TECHNICAL FIELD [0001] The present invention relates to a secondary electron emission rate measuring device, and more specifically, measures a secondary electron emission rate of a dielectric protective film of a plasma display panel in real time on a production line, or to a research and development facility. The present invention relates to a secondary electron emission rate measuring device for precise measurement. Background art

[0002] With the development of global networks such as the Internet and local networks, information terminals for transmitting and receiving information via these networks are dramatically increasing. In addition to those used on office desks, such information terminals are used for various purposes such as portable and conference rooms, and the display is varied accordingly.

Plasma display panels are expected to expand in demand for information terminals for conference rooms, outdoor advertisements, large TVs, etc. as large-screen displays that take advantage of their thin, self-luminous type and wide viewing angle. And

FIG. 7 is a configuration diagram of an AC type plasma display panel (hereinafter abbreviated as “PDP”).

As shown in FIG. 7, in the PDP 301, a front glass substrate 302 and a rear glass substrate 303 are disposed to face each other, and both the front and rear substrates are sealed around (not shown), and an inert gas (discharge) Gas) is enclosed. A pair of sustain electrodes 304 is formed of a transparent conductive material on the front glass substrate 302. In order to prevent the voltage drop of the sustain electrode 304, the bus electrode parallel to the sustain electrode 304 and in contact with a part of the sustain electrode 304 is formed of a metal having high conductivity. On the sustain electrode 304, a dielectric film 305 and a protective film (dielectric protective film) 306 covering the sustain electrode 304 are laminated.

On the other hand, address electrodes 307 are formed on the rear glass substrate 303. In addition, partition walls 308 are formed at regular intervals in parallel with the address electrodes 307 to partition the space between the front and back substrates into a band-shaped space in the address electrode direction. Currently, production technology has been improved, and some of the bulkheads are designed in a lattice type or meander type. Address electrode 307 is dielectric layer 31 The phosphor 309 is formed on the upper surface thereof.

In FIG. 7, for convenience of explanation, sustain electrode 304 on front glass substrate 302 and address electrode 307 on rear glass 303 are drawn in parallel. Actually, sustain electrode 304 and address electrode 307 are 90 degrees. The front and back glass are sealed so that they are arranged at an angle of torsion.

[0004] Discharging is performed by applying a voltage between address electrode 307 and sustain electrode 304, and this discharge is maintained by applying an AC voltage to a pair of sustain electrodes 304. The inert gas is excited by discharge to generate ultraviolet rays, and the phosphor 309 emits light upon receiving the ultraviolet rays. The discharge start voltage and the discharge sustain voltage of the PDP having such a structure depend on the secondary electron emission rate due to ion bombardment of the protective film 306, and if the discharge rate is high, the discharge start voltage and the discharge sustain voltage can be lowered. Power consumption is reduced. With PDPs, which consume more power than LCDs, reducing power consumption is the biggest challenge for expanding demand.

Currently, magnesium oxide thin film is widely used as a protective film. However, active research is underway to develop a protective film with a high secondary electron emission rate. There is a need for an apparatus that can be easily measured. In addition, it is important to measure and manage the secondary electron emission rate of the protective film in the production of PDP, and the demand for secondary electron emission rate measuring equipment will increase in the future.

[0005] Secondary electron measurement methods using ion beam irradiation are disclosed in Patent Document 1, Patent Document 2, and Patent Document 3, for example. For example, the apparatus of Patent Document 1 includes an ionization unit that generates charged particles in a chamber, a cathode on which a substance to be measured is placed, and an electrode that captures secondary electrons. The amount of charged particles irradiated and the amount of secondary electrons emitted are measured as the current of the cathode and collecting electrode to determine the secondary electron emission rate. The basic structure of Patent Documents 2 and 3 is the same.

[0006] However, the secondary electron emission rate measurement device using the charged particle beam based on the techniques of Patent Document 1 and Patent Document 3 is a charged particle generation source, a target substance fixing holder, an incident current measurement device, an emission device. It is a large-scale device including an electronic current measuring device and a control device. In particular, the charged particle generation source is not used for measuring the secondary electron emission rate. For example, it is used for focused ion beam (FIB) for material analysis or ion beam for material force measurement. Because it is diverted, it is very expensive. Therefore, it is difficult for small-scale research facilities and companies to conduct research on the secondary electron emission rate.

[0007] In addition, the charged particle beam used in the secondary electron emission rate measurement of Patent Documents 1 and 3 has a large current amount of several hundred eV to several keV. Therefore, when evaluating the secondary electron emission rate of insulator materials, the SN ratio deteriorates due to the surface charge-up phenomenon. The energy of charged particles in plasma display panels is several tens to several hundreds eV, and it is preferable to use charged particle beams with energy values in this region for measuring the secondary electron emission rate. Have difficulty.

[0008] Further, the measurement object described in Patent Document 1, Patent Document 2, and Patent Document 3 is an MgO thin film deposited on a substrate prepared for an experiment. The technical idea of evaluating and managing the secondary electron emission rate in real time on the production line proposed in this patent has not been disclosed so far. Equipment can be installed.

Patent Document 1: Japanese Patent Laid-Open No. 11-230923

Patent Document 2: JP 2004-28906 A

Patent Document 3: Japanese Patent Laid-Open No. 2004-177135

Disclosure of the invention

Problems to be solved by the invention

[0009] The present invention has been made in view of the above-mentioned problems of the prior art. From the viewpoint of quality control in the production of PDP, the uniformity of the secondary electron emission rate of the protective film in the production line is determined in real time. The purpose is to provide a small and inexpensive secondary electron emission rate measuring device to be monitored.

In addition, it is possible to accurately control the charged particle beam so that it is suitable for research and development on the secondary electron emission rate, and it is possible to measure the secondary electron emission rate during electron beam irradiation. An object of the present invention is to provide an emission rate measuring device.

Means for solving the problem

In order to achieve the above object, a secondary electron emission rate measuring device according to claim 1 of the present invention includes a cylindrical electrode having an opening at the top and a central axis portion of the cylindrical electrode. Provided rod-shaped electrode A charged particle generating source for generating charged particles by glow discharge plasma between the cylindrical electrode and the rod-shaped electrode and discharging the opening force; Compact size consisting of an electrostatic lens that converges the beam of charged particles emitted from the aperture and irradiates the object to be measured, and a secondary electron collector electrode that captures the secondary electrons emitted from the measured substance force A secondary electron measurement unit including a secondary electron measurement unit and a sample holding unit for holding an object to be measured in a vacuum chamber;

A voltage is applied to the gas exhaust unit that depressurizes the inside of the vacuum chamber, a gas supply unit that supplies a gas to be charged particles to the charged particle generation source, the charged particle generation source, the electrostatic lens, and the secondary electron collector electrode. A voltage applying unit for measuring current and a current measuring unit,

A control computer for controlling these and calculating a secondary electron emission rate;

It is characterized by being composed of force.

[0011] The secondary electron emission rate measuring device according to claim 2 of the present invention is the secondary electron emission rate measuring device according to claim 1, wherein the charged particle generation source is controlled by a control computer. Gas is introduced from the gas supply unit, and a positive voltage is applied to the cylindrical electrode and a negative voltage is applied to the rod electrode by the voltage application unit to generate glow discharge plasma to generate charged particles. The structure is characterized in that the pressure of the chamber is reduced and the charged particles pushed out by the pressure difference from the top opening of the cylindrical electrode are accelerated by the voltage applied to the cylindrical electrode.

[0012] The secondary electron emission rate measuring device according to claim 3 of the present invention is the secondary electron emission rate measuring device according to claim 1, wherein the electrostatic lens is charged with a space potential. At the same time as the particle beam is focused, the electrons in the charged particle beam of the charged particle generation force are reflected and removed, and the secondary electron collector electrode captures the secondary electrons that could be captured by the secondary electron collector electrode. It is comprised so that it may return to.

[0013] A secondary electron emission rate measuring device according to claim 4 of the present invention is the secondary electron emission rate measuring device according to claim 1, and further from a voltage application unit under the control of a control computer. The polarity of the voltage applied to the cylindrical electrode and rod electrode of the charged particle generation source is reversed to change the charged particle beam from the positive ion beam to the electron beam, and the polarity of the voltage applied to the electrostatic lens is also reversed. , Characterized by measuring the secondary electron emission rate irradiated with an electron beam To do.

[0014] The secondary electron emission rate measuring device according to claim 5 of the present invention is the secondary electron emission rate measuring device according to any one of claims 1 to 4, further comprising secondary electrons. The measurement unit includes a plurality of small secondary electron measurement units, and includes a drive unit that moves a plane perpendicular to the rod-shaped electrode, depending on whether the plurality of small secondary electron measurement units or the sample holding unit is misaligned. Is characterized by controlling the driving device and calculating the surface distribution of the secondary electron emission rate.

[0015] A secondary electron emission rate measuring device according to claim 6 of the present invention is the secondary electron emission rate measuring device according to any one of claims 1 to 4, further comprising a sample holding unit. Is equipped with a drive unit that holds multiple samples and moves the sample holder in a plane perpendicular to the rod-like electrode, and the control computer controls the drive unit to calculate the secondary electron emission rate of multiple samples in sequence. It is characterized by that.

The invention's effect

[0016] In the above configuration, by using a glow discharge plasma for the generation of charged particles, and a structure in which two roles of glow discharge plasma generation and charged particle acceleration are played by the cylindrical electrode. The charged particle generation source can be greatly simplified and miniaturized. As a result, a unit of a charged particle generation source, an electrostatic lens, and a part of a secondary electron collector, which has been conventionally configured separately, can be realized. As a result, it was previously necessary to adjust the position of the charged particle generation source, electrostatic lens, and secondary electron collector to adjust the position of each beam. This makes it possible to easily measure the secondary electron emission rate. Furthermore, since the conventional technology is based on the premise that the measurement chamber is equipped with a charged particle generation source, the force that the apparatus was very large and costly was used. Secondary electron emission rate of the present invention In the measurement apparatus, there is only a gas introduction unit and a current introduction unit that do not need to have a charged particle generation source in the measurement chamber by a unit of a charged particle generation source, an electrostatic lens, and a secondary electron collector. Since measurement is possible, the size and cost of the device can be reduced.

[0017] Measurement of the secondary electron emission rate using a low-energy charged particle beam of several tens to several hundreds of eV, which is almost the same as a charged particle in a PDP cell, which is difficult to generate with the conventional technology. Is easily possible. Furthermore, since the energy of the charged particle beam can be suppressed to several hundred to several tenths compared with the conventional technology, it becomes possible to perform secondary electron emission rate measurement nondestructively. On the other hand, since it is possible to stably reduce the amount of charged particle current from several nA to several tens of nA, in the conventional technology, the secondary electron emission rate was difficult due to surface charge-up. In the case of a body target, measurement is possible without being adversely affected by charge-up.

Brief Description of Drawings

FIG. 1 is a configuration diagram of a secondary electron emission rate measuring apparatus according to Embodiment 1 of the present invention.

FIG. 2 is a configuration diagram of a secondary electron emission rate measuring apparatus according to Embodiment 2 of the present invention.

FIG. 3 is an energy distribution diagram of a charged particle beam generated by the charged particle generation source of the present invention.

FIG. 4 is a time change diagram of a charged particle beam generated by the charged particle generation source of the present invention.

FIG. 5 shows the applied voltage dependence of the secondary electron collector electrode current in the secondary electron emission rate measuring device of the present invention.

[FIG. 6] Secondary electron emission rates of various substances obtained by the secondary electron emission rate measuring device of the present invention.

FIG. 7 is a configuration diagram of a plasma display panel.

Explanation of symbols

[0019] 101, 201 Gas supply section

102, 122, 202, 223

103, 203 Vacuum channel

104, 204 Gas introduction pipe

105, 205 Gas introduction pipe

106, 206 Rod electrode

107, 207 Charged particle generation chamber fixing plate

108, 208 Ceramic disc

109, 113, 115, 117, 209, 213, 215, 217 Insulating spacer

110, 210 cylindrical electrode 111, 211 Charged particle passage hole (opening)

112, 114, 116, 212, 214, 216 electrostatic lens

118, 218, 222 Tongue removal electrode

119, 219 Secondary electron collector electrode

120, 220 Substance to be measured (Protective film)

121 board

123, 224 Gas exhaust

124, 225 Vacuum gauge

125, 127, 128, 130, 227, 229, 230, 232, voltage marking section

126, 129, 131, 226, 228, 231, 233 Current measurement unit

132, 234 Control computer

221 Sample holder

301 Plasma display panel

302 Front glass substrate

303 Rear glass substrate

304 maintenance electrode

305 Dielectric film

306 Protective film (Dielectric protective film)

307 Address electrode

308 Bulkhead

309 phosphor

310 Dielectric layer

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

Example 1

[0021] Figure 1 shows the purpose of measuring the uniformity of the secondary electron emission rate (product-to-product variation, product-to-product variation) of the substance to be measured (protective film) for quality control in the PDP production line. Is a secondary electron emission rate measuring device configured as follows. This secondary electron emission rate measuring device A small secondary electron unit comprising an electron particle generation source, an electrostatic lens, and a part of a secondary electron collector, and a secondary electron equipped with the small secondary electron unit and a sample holder in a vacuum chamber. A measurement unit, a gas supply unit for operating the secondary electron measurement unit, a gas exhaust unit, a plurality of voltage application units, a plurality of current measurement units, a drive unit, and a control computer force are configured.

In order to generate charged particles, a gas for forming charged particles is supplied from the gas supply unit 101 into the cylindrical electrode 110 through the gas introduction pipe 104 and the gas introduction pipe 105.

A rod-shaped electrode 106 is formed at the position of the central axis in the cylindrical electrode 110. By applying a positive voltage to the cylindrical electrode 110 and a negative voltage to the rod-shaped electrode 106, a glow discharge is generated between both electrodes. Electroplasma is generated. A voltage is applied to the rod-shaped electrode 106 and the cylindrical electrode 110 by the voltage applying units 130 and 128, and currents are measured by the current measuring units 131 and 129. The cylindrical electrode 110 and the rod-shaped electrode 106 are fixed to the charged particle generation chamber fixing plate 107 via a ceramic disk 108, and the cylindrical electrode 110 and the rod-shaped electrode 106 are isolated from the charged particle generation chamber fixing plate 107. I keep it. The cylindrical electrode 110, the rod-shaped electrode 106, and the gas introduction tube 105 held on the ceramic disk 108 constitute a charged particle generation source.

The material of the rod-like electrode 106 and the cylindrical electrode 110 is a hard metal such as stainless steel, tantalum, or tungsten. The gas introduced to generate charged particles from the gas supply unit 101 is an active gas such as O, N, CO, or He.

Inert gas such as 2 2, Ne, Ar, Xe.

2

An opening (charged particle passage hole) 111 is formed at the top of the cylindrical electrode. The vacuum chamber 103 is depressurized to a predetermined pressure by the gas exhaust part 123. Due to the pressure difference between the inside and outside of the cylindrical electrode 110, charged particles generated by the glow discharge plasma pass through the charged particle passage hole 111. Released to the outside. At this time, the charged particle beam can be generated from the low vacuum region to the high vacuum region by adjusting the hole diameter of the charged particle passage hole 111 according to the degree of vacuum in the vacuum chamber. .

In other words, the degree of vacuum in the chamber needs to be changed in order to cope with various measurement conditions, while the degree of vacuum in the cylindrical electrode is kept at a pressure at which optimum discharge occurs depending on the introduced gas. There is a need. Therefore, the hole diameter of the charged particle passage hole 111 is adjusted in order to optimize the vacuum balance between the chamber and the cylindrical electrode. Therefore, charged particle passage The hole 111 preferably has a structure in which the hole diameter is variable or a member having a different hole diameter is detachably attached.

The charged particles emitted from the charged particle passage hole 111 are further accelerated by the voltage applied to the cylindrical electrode 110 by the voltage application unit 128 to become a charged particle beam. By controlling the voltage applied to the cylindrical electrode 110, the energy of the charged particle beam can be adjusted.

The vacuum chamber 103 is evacuated by the gas exhaust unit 123 and is controlled to a predetermined degree of vacuum.

The electrostatic lenses 112 and 116 are grounded, and a voltage is applied to the electrostatic lens 114 by the voltage application unit 127. In general, the “electrostatic lens” is a technology that applies a voltage to three electrodes and converges the charged beam by the generated space potential. In this specification, each of the three electrodes constituting the “electrostatic lens” is This is called an electrostatic lens. The charged particle beam is converged by the electrostatic lenses 112, 114, and 116, and is irradiated onto the substance 120 to be measured deposited on the substrate 121 held by the sample holder (not shown). The force in which electrons are contained in the generated charged particle beam When the charged particle beam passes through the electrostatic lenses 112, 114, and 116, these electrons are removed by the spatial potential. In addition, the secondary electrons emitted from the substance 120 to be measured are not captured by the secondary electron collector electrode 119, and the force that may jump out of the holes of the secondary electron collector electrode 11 9 It is pushed back by the space potential by 114, 116 and is captured by the secondary electron collector electrode 119. The voltage applied to the electrostatic lens 114 may be either positive or negative for the purpose of focusing the charged particle beam, but in order to eliminate unnecessary electrons as described above. Is preferably a negative voltage.

The electrostatic lens converges the charged particle beam, and at the same time, removes excess electrons in the charged particle beam so that they do not enter the secondary electron collector electrode. Furthermore, the electrostatic lens cannot capture the force with the secondary electron collector electrode. The measured substance force also plays the three roles of returning the emitted secondary electrons to the secondary electron collector electrode, enabling highly accurate measurement.

[0026] The force by which the secondary electron is emitted from the substance 120 to be measured on the substrate 121 by being irradiated with the charged particle beam. The secondary electron is applied to the secondary electron collector electrode 119 to the voltage application unit 125. The force is also captured by applying a positive voltage, and the number of electrons is measured by the current measuring unit 126 as a current amount.

The charged particle generator, the three electrostatic lenses, and the secondary electron collector electrode are united to form a small secondary electron measurement unit.

The small secondary electron measurement unit is designed so that the space potential around the secondary electron collector electrode 119 does not affect the space potential around the electrostatic lenses 112, 114, 116, and is unnecessary in the vacuum chamber 103. It is preferable to dispose the disturbance eliminating electrode 118 so that free electrons are not captured by the secondary electron collector electrode 119.

[0027] Conventionally, an ion source using a glow discharge plasma as in the present invention has been used for a secondary electron emission rate measuring apparatus. The reason is that it is difficult to generate a beam with a large current.

In the present invention, by adopting the configuration described above, (1) the rod-shaped electrode 106 is installed inside the cylindrical electrode 110, and gas is introduced into the cylindrical electrode to generate a glow discharge plasma between the electrodes. In addition, the charged particles generated by the pressure from the opening 111 at the top of the cylindrical electrode due to the pressure difference are accelerated by the voltage applied to the cylindrical electrode 110. (2) Reduce the distance between the charged particle generation sources 105-108, 110, electrostatic lenses 112, 114, 116, and secondary electron collector electrodes 118, 119. Difficult to handle due to configuration U, I realized a secondary electron emission rate measurement device of ion source using glow discharge plasma that has been focused on as an ion source. In addition, the problem of charge-up of the substance to be measured was solved by using a low-energy charged particle beam. By thus specializing the small secondary electron measurement unit for measuring the secondary electron emission rate, it is possible to easily generate a low-energy charged particle beam with a much simpler structure than before.

[0028] In the above configuration, the charged particle generation sources 105-108, 110, the electrostatic lenses 112, 114, 116, and the secondary electron collector electrodes 117, 118 are the insulating spacers 109, 113, 115, 1 17 and connected as a small secondary electron measuring unit. This small secondary electron measurement unit can be manufactured with a height of 70 mm or less and a width of φ40 mm or less. Furthermore, a secondary electron measuring unit is a unit in which a small secondary electron measuring unit and a sample holder are arranged in a vacuum chamber.

[0029] A valve 122 of a gas exhaust unit 123 that depressurizes the inside of the vacuum chamber 103, a valve 102 of a gas supply unit 101 that supplies gas that becomes charged particles to a charged particle generation source, a vacuum gauge 124, and a voltage application unit 125 , 127, 128, 130, current measuring units 126, 129, 131 and Z or signal input / output are collectively performed by the control computer 132. The measurement flow of the secondary electron emission rate performed under the control of the control computer 132 will be described below.

First, the valve 122 is opened, the vacuum in the vacuum chamber 103 is evacuated, and the degree of vacuum is measured by the vacuum gauge 124. When a predetermined degree of vacuum is reached, the valve 102 is opened to supply a predetermined amount of gas to be charged particles. The valve 102 is provided with a flow meter (not shown), and its output signal is transmitted to the system control computer and controlled to a predetermined flow rate. The voltage application units 128 and 130 are controlled to apply a predetermined voltage to the cylindrical electrode 110 and the rod-like electrode 106, thereby generating a glow discharge plasma and emitting a charged particle beam. After the glow discharge plasma is generated, the voltage application unit 127 is controlled to apply a predetermined voltage to the electrostatic lens 114 to converge the beam.

[0031] After the charged particle beam is stabilized, the voltage application unit 125 is controlled to apply a predetermined voltage to the secondary electron collector electrode 119 to capture the secondary electrons emitted from the substance 120 to be measured. A change in the amount of secondary electron current measured by the current measuring unit 126 with respect to time is output through the control computer 132. As a result, the secondary electron emission rate of the substance to be measured can be measured in real time in the factory production line.

[0032] In the present embodiment, the beam amount of the charged particles irradiated to the object to be measured is measured. However, this device is extremely stable and has no problem for quality control purposes in the manufacturing process. In Example 2, which will be described below, the charged particle beam amount is directly measured. By sufficiently obtaining basic data using the device of Example 2, the type and flow rate of the introduced gas, the rod electrode From the voltage applied to 106 and the cylindrical electrode 110, etc., it is possible to determine the beam amount of charged particles irradiated to the object to be measured.

[0033] A charged particle generation source, an electrostatic lens, a small secondary electron measurement unit in which a part of a secondary electron collector is unitized, or a sample holder for holding a substance to be measured is arranged in the longitudinal direction of a rod-shaped electrode. A small secondary electron measurement unit or sample holder is further provided for the drive unit that moves on a vertical plane, and this drive unit is controlled by a control computer so that the small secondary electron measurement unit and the substance to be measured can be controlled. Change the relative position to a predetermined relative position, and for example, a large measured substance such as a large screen PDP on the factory production line, the secondary electron emission rate of multiple points of the measured substance, or secondary electrons A secondary electron emission rate measuring device capable of measuring the emission rate surface distribution fully automatically in real time can be obtained.

In addition, it is possible to efficiently measure the secondary electron emission rate surface distribution by providing multiple small secondary electron measurement units and providing a drive unit that moves these small secondary electron measurement units or sample holders. It is.

Example 2

[0034] Fig. 2 is a secondary electron emission rate measuring device constructed for the purpose of precise measurement experiments of the secondary electron emission rate of a substance to be measured in research and development facilities. This secondary electron emission rate measuring device includes a small secondary electron unit consisting of a charged particle generation source, an electrostatic lens, and a part of a secondary electron collector, and the small secondary electron unit and a sample holder in a vacuum chamber. The secondary electron measurement unit provided in the system, and the gas supply unit, gas exhaust unit, multiple voltage application units, multiple current measurement units, drive unit, and control computer power for operating the secondary electron measurement unit are also configured. Has been. This configuration is the same as in Example 1. The details of each configuration are different from Example 1.

In order to generate charged particles, a gas to be charged particles is supplied from the gas supply unit 201 into the cylindrical electrode 210 through the gas introduction pipe 204 and the gas introduction pipe 205. When a positive voltage is applied to the cylindrical electrode 210 and a negative voltage is applied to the rod-shaped electrode 206, glow discharge plasma is generated between the two electrodes.

Voltage is applied to the rod-shaped electrode 206 and the cylindrical electrode 210 by the voltage applying units 232 and 230, respectively, and the current is measured by the current measuring units 233 and 231. The cylindrical electrode 210 and the rod-shaped electrode 206 are fixed to the charged particle generation chamber fixing plate 207 via the ceramic disk 208, and the cylindrical electrode 210 and the rod-shaped electrode 206 are insulated from the charged particle generation chamber fixing plate 207. ing.

Due to the pressure difference between the inside and outside of the cylindrical electrode 210, the glow discharge plasma is generated inside the cylindrical electrode. The generated charged particles are released to the outside through an opening (charged particle passage hole) 211 provided at the top of the cylindrical electrode due to a pressure difference between the inside and outside of the cylindrical electrode 210. The discharged charged particles are further accelerated by the voltage applied to the cylindrical electrode 210 to become a charged particle beam. By manipulating the voltage applied to the cylindrical electrode 210, the energy of the charged particle beam can be adjusted.

FIG. 3 is an energy distribution diagram of an ion beam (charged particle beam). When the applied voltage of the cathode (rod electrode) is constant and the applied voltage of the anode (tubular electrode) is increased, the peak energy of the ion beam distribution increases. A charged particle beam with low energy and a small half-value width is suitable for the secondary electron emission rate measurement device, and the distribution shown in Fig. 3 corresponds to this.

The vacuum chamber 203 is evacuated by a gas exhaust unit 224, and a predetermined degree of vacuum is controlled by a vacuum gauge 225. At this time, the charged particle beam can be generated from the low vacuum region to the high vacuum region by adjusting the hole diameter of the charged particle passage hole 211 according to the degree of vacuum in the vacuum chamber.

The electrostatic lenses 212 and 216 are grounded, and a voltage is applied to the electrostatic lens 214 by the voltage application unit 229. The charged particle beam is converged by the electrostatic lenses 212, 214, and 216, and irradiated to the measurement target material 220.

A force in which electrons are contained in the generated charged particle beam When the charged particle beam passes through the electrostatic lenses 212, 214, and 216, these electrons are removed by the space potential.

In addition, the secondary electrons emitted from the material 220 to be measured are not captured by the secondary electron collector electrode 219, and the electrons that may jump out of the holes of the secondary electron collector electrode 219. , 216 and is captured by the secondary electron collector electrode 219.

[0038] The force by which secondary electrons are emitted from the measurement target substance 220 fixed to the sample holder 221 by irradiation with the charged particle beam. The secondary electrons are applied to the secondary electron collector electrode 219. Is captured by applying a positive voltage, and the amount of electrons is measured by the current measuring unit 228 as a current amount. In addition, the current flowing through the substance to be measured Measured by part 226. The secondary electron collector electrode 219 has a shape that covers the target so that the secondary electrons from the substance 220 to be measured can be reliably captured.

[0039] In the above configuration, charged particle generation sources 205-208, 210, electrostatic lenses 212, 214, 216, and secondary electron collector parts 218, 219 are insulating spacers 209, 213, 215, Connected by 21 7 and unitized as a small secondary electron measuring unit! RU

A configuration in which the small secondary electron unit and the sample holding unit 221 are housed and installed in the vacuum chamber 203 is called a secondary electron measuring unit.

[0040] A valve 223 of a gas exhaust unit 224 for depressurizing the inside of the vacuum chamber 203, a valve 202 of a gas supply unit 201 for supplying a gas as a charged particle to a charged particle generation source, a vacuum gauge 225, a voltage marking unit, Control of 227, 229, 230, 232, current measuring unit 226, 228, 231, 233 and Z or signal input / output are performed collectively by the control computer 234. The measurement flow of the secondary electron emission rate performed under the control of the control computer 234 is described below.

First, the valve 223 is opened, the vacuum in the vacuum chamber 203 is drawn, and the degree of vacuum is measured by the vacuum gauge 225. When a predetermined degree of vacuum is reached, the valve 202 is opened to supply a gas to be charged particles at a predetermined flow rate. The voltage application units 230 and 232 are operated to apply a voltage to the cylindrical electrode 210 and the rod-shaped electrode 206 to generate a glow discharge plasma and emit a charged particle beam. After the glow discharge plasma is generated, the voltage application unit 229 is operated to apply a voltage to the electrostatic lens 214 to converge the beam.

[0042] FIG. 4 shows the change over time in the amount of current until the charged particle beam is stabilized. The measurement conditions in Fig. 4 are cylindrical electrode: 150V, rod electrode: -300V, and chamber vacuum: 3.9 X 10 ^_3 Pa. The ion beam (charged particle beam) current is about 12 nA, which is stable at a very low value compared to the conventional ion beam current. Also, it takes about 60 seconds for the ion beam to stabilize.

After the charged particle beam is stabilized, the voltage application unit 227 is operated to apply a voltage to the secondary electron collector electrode 219 to capture the secondary electrons emitted from the substance 220 to be measured. Measured as quantity (A). At the same time, the current measuring unit 226 measures the amount of current (B) flowing through the substance to be measured. The secondary electron emission rate is obtained as AZ (B−A). Secondary electron collector of secondary electron current measured by current measuring unit 226, 228 The change to the applied voltage to 1 is output through the system control computer 234. Figure 5 shows an example of the dependence of the secondary electron current and the target (substance to be measured) current on the collector voltage (voltage applied to the secondary electron collector electrode). Figure 5 shows the data obtained by measuring the secondary electron emission rate of MgO under the conditions of 150V for the cylindrical electrode, 300V for the rod electrode, ^3.9 X 10 ^_3 Pa, and Ne + as the charged particle beam. It is. When the collector applied voltage is 20V or higher, the secondary electron current and the target current amount are almost constant, indicating that the secondary electrons are reliably captured. In addition, in Fig. 5, the charged particle beam amount is about llnA, which is significantly reduced compared to the conventional technology. As a result, it is possible to easily measure the secondary electron emission rate of the substance to be measured in laboratories and the like!

FIG. 6 shows experimental data for determining secondary electron emission rates for various substances to be measured using the secondary electron emission rate measurement system of the present invention. These were obtained under the measurement conditions of 150 V applied to the cylindrical electrode, 300 V applied to the rod electrode, Ne + charged particle beam, and ^1.9 X 10 ^_3 Pa vacuum in the chamber. Data.

[0043] By reversing the polarity of the voltage applied to the cylindrical electrode and the rod-shaped electrode at the charged particle generating source, the charged particle beam can be changed to a positive ion beam force to an electron beam. In addition, by reversing the polarity of the voltage applied to the electrostatic lens, it is possible to measure the secondary electron emission rate when the electron beam is irradiated. From this, it is possible to measure two types of physical properties, the secondary electron emission rate by positive ion beam irradiation and the secondary electron emission rate by electron beam irradiation using the same apparatus.

In the case of PDP, the force mainly focused on ion-derived secondary electron emission Generally, both ion-derived secondary electron emission and electron-derived secondary electron emission are very important physical phenomena. . In particular, the number of papers on electron-derived secondary electron emission is overwhelmingly higher than that on ion-derived secondary electron emission. Therefore, the apparatus can be calibrated by measuring the electron emission type secondary electron emission rate of the object to be measured. As a result, the reliability of the measured value of the ion-derived secondary electron emission rate of the object to be measured is improved.

[0044] In addition, the sample holding unit 221 further includes a driving unit that holds a plurality of samples and moves the sample holding unit on a plane perpendicular to the longitudinal direction of the rod-shaped electrode. The It is possible to measure the secondary electron emission rate of multiple substances to be measured sequentially by controlling the control computer to move the sample holder so that the multiple samples are sequentially facing the small secondary electron measurement unit. it can. In precision experiments at research facilities, etc., the secondary electron emission rate of multiple substances to be measured can be measured automatically with a single sample loading without breaking the vacuum in the measurement chamber for each substance to be measured. The experimental time can be shortened Industrial applicability

In the above-described embodiments, the configuration suitable for measuring the secondary electron emission rate of the protective film of the PDP has been mainly described. However, the small secondary electron measurement unit can be applied to various devices that require charged particle irradiation.

Claims

The scope of the claims

[1] A cylindrical electrode having an opening at the top, a rod-shaped electrode provided at a central shaft portion of the cylindrical electrode, and a gas introduction tube for introducing gas serving as charged particles, the cylindrical electrode and the rod-shaped electrode Charged particles are generated by glow discharge plasma between electrodes, and a charged particle generating source that emits from the opening, and an electrostatic force that irradiates the object to be measured by converging the beam of charged particles emitted from the opening force. A small secondary electron measurement unit comprising a lens and a secondary electron collector electrode for capturing secondary electrons emitted from the substance to be measured, and a sample holder for holding the object to be measured are provided in the vacuum chamber. A secondary electron measurement unit prepared for

A gas exhaust unit for reducing the pressure in the vacuum chamber;

A gas supply unit configured to supply a gas serving as charged particles to the charged particle generation source; a voltage application unit configured to apply a voltage to a part of the charged particle generation source, the electrostatic lens, and the secondary electron collector and measure the current; A current measuring unit;

A control computer for controlling these and calculating the secondary electron emission rate;

Secondary electron emission rate measuring device characterized by comprising.

[2] The charged particle generation source is configured to cause a gas to be introduced from the gas supply unit under the control of the control computer, and to apply a positive voltage to the cylindrical electrode and a negative voltage to the rod-shaped electrode by the voltage application unit. Charged particles are generated by generating discharge plasma, and the vacuum chamber is depressurized by the gas exhaust unit, and charged particles pushed out by a pressure difference from the top opening of the cylindrical electrode are applied to the cylindrical electrode. 2. The secondary electron emission rate measuring device according to claim 1, wherein the secondary electron emission rate measuring device is a structure accelerated by the electron beam.

[3] The electrostatic lens converges the beam of charged particles by a spatial potential, and at the same time, reflects and removes electrons in the beam of charged particles from the charged particle generation source and captures them with a secondary electron collector electrode. 2. The secondary electron emission rate measuring device according to claim 1, wherein the secondary electron emission rate measuring device is configured to return the emitted secondary electrons with strong force to the secondary electron collector electrode.

[4] The voltage applied by the control of the control computer is changed from the positive ion beam to the electron beam by reversing the polarity of the voltage applied to the cylindrical electrode and rod electrode of the charged particle generation source. The secondary electron emission rate is measured by irradiating an electron beam with the polarity of the voltage applied to the electrostatic lens reversed and irradiating the electron beam. Child emission rate measuring device.

[5] The secondary electron measurement unit includes a plurality of small secondary electron measurement units, and drives either the plurality of small secondary electron measurement units or the sample holder to move in a plane perpendicular to the rod-shaped electrode. 5. The secondary electron emission according to claim 1, wherein the control computer controls the driving unit to calculate a surface distribution of a secondary electron emission rate. Rate measuring device.

[6] The sample holding unit includes a driving unit that holds a plurality of samples and moves the sample holding unit in a plane perpendicular to the rod-shaped electrode, the control computer controls the driving unit, and the plurality of samples The secondary electron emission rate measuring device according to claim 1, wherein the secondary electron emission rate is sequentially calculated.